JP4226104B2 - Manufacturing method of resin-coated aluminum seamless cans - Google Patents
Manufacturing method of resin-coated aluminum seamless cans Download PDFInfo
- Publication number
- JP4226104B2 JP4226104B2 JP13605298A JP13605298A JP4226104B2 JP 4226104 B2 JP4226104 B2 JP 4226104B2 JP 13605298 A JP13605298 A JP 13605298A JP 13605298 A JP13605298 A JP 13605298A JP 4226104 B2 JP4226104 B2 JP 4226104B2
- Authority
- JP
- Japan
- Prior art keywords
- processing
- resin film
- ironing
- cup
- resin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【０００１】
【発明の属する技術分野】
本発明は、樹脂被覆アルミニウムシームレス缶の製造方法に関する。
【０００２】
【従来の技術】
アルミニウムやスチールを素材とした金属缶・容器は、その形状からスリーピース缶とツーピース缶とに大別される。スリーピース缶は、地蓋、缶胴、天蓋からなるためスリーピース缶と呼ばれている。一方ツーピース缶は、地蓋と缶胴とが一体となったもので、それに天蓋とからなるためツーピース缶、または、缶胴部に接合部がないことからシームレス缶とも呼ばれている。
【０００３】
金属缶の場合、缶内面には耐食性を確保するため塗装が施されて使用されているが、近年、樹脂フィルムを積層したラミネート缶が開発され、市場に出回っている。ラミネート缶は、金属素材に樹脂フィルムを積層させたものから、缶体成形加工を行うものが主であり、特にツーピース缶を得るには高度な成形加工技術を必要とする。かかる意味においても、ツーピースのラミネート缶に関わる技術は、例えば特開平７−２２４１号公報、特開平７−１９５６１９号公報、特開平８−２４４７５０号公報等、数多く提案され、開示されている。
【０００４】
ラミネート缶のメリットは、消費者側から見た場合、適用する有機樹脂フィルムにもよるが、耐内容物性、特に内容物の味、風味といったフレーバー性に優れている点が第一に挙げられている。一方、デメリットとしては、今度はメーカー側からであるが、前述したようにツーピース缶の場合、有機樹脂フィルム被覆金属板の加工度合（又は、変形度合）が大きいので成形時に内面樹脂フィルムに傷が入ったりして、缶内面の品質確保ができなくなるため、缶体の品質検査を厳重に行う必要があることと、製品歩留りが現行の塗装缶に比し劣るといった点が挙げられる。
【０００５】
特に、スチール素材を用いたツーピースラミネート缶の場合、前記の傾向が大きいが、アルミニウム素材のラミネート缶でも同様なことが起こる。こうしたラミネート缶の内面樹脂フィルムの皮膜欠陥は、前述したように缶成形加工時に入るものであり、この欠陥を最小限に押さえることは、品質、製品歩留まりの点から重要な技術課題であることは言うまでもない。
しかし、しごき加工を伴うツーピース缶成形の場合、特にその高加工率の場合、適切な方法がないのが現状である。
【０００６】
【発明が解決しようとする課題】
本発明の目的は、皮膜欠陥のない高品質なシームレス缶を歩留まりよく提供する点にある。
【０００７】
【課題を解決するための手段】
本発明は、アルミニウム板の両面にポリエステル樹脂フィルムを被覆してなるラミネートアルミニウム板を、カップへの絞り加工（第１工程）、カップの再絞り加工（第２工程）、更にしごき加工（第３工程）を行ってシームレス缶を得るポリエステル樹脂被覆アルミニウムシームレス缶の製造方法において、前記アルミニウム板の両面に被覆したポリエステル樹脂フィルムが、（１）ポリエチレンテレフタレート、（２）ポリブチレンテレフタレート、（３）ポリエチレンイソフタレート、（４）ポリエチレンテレフタレートとポリエチレンイソフタレートとの共重合樹脂、および（５）これらのブレンド樹脂、よりなる群から選ばれたものであり、このフィルムを厚み１０〜５０μｍ、密度１．３６ｇ／ｃｍ３未満の非晶質状態となるようにした後、第１工程のカップへの絞り加工を被覆樹脂のガラス転移温度（Ｔｇ）から樹脂の冷結晶化温度（Ｔｃ）の範囲で、ストレッチ加工および／またはしごき加工を付加した絞り加工を行い、次いで、第２工程のカップの再絞り加工を被覆樹脂のガラス転移温度（Ｔｇ）から樹脂の冷結晶化温度（Ｔｃ）の範囲でストレッチ加工および／またはしごき加工を付加した再絞り加工を行い、次にカップの缶体温度を３０〜５０℃にした後、第３工程のしごき加工を、加工金型の温度を５０〜１２０℃に保持して加工し、得られた缶体を加熱、冷却して再度樹脂フィルムの密度を１．３６ｇ／ｃｍ３未満の非晶質状態にした後、ネック加工およびフランジ加工することを特徴とする樹脂被覆アルミニウムシームレス缶の製造方法に関する。
【０００８】
【発明の実施の形態】
以下、本発明の方法の実施形態について詳細に説明する。
まず、本発明の方法における缶体の成形加工について述べる。
本発明の方法では、缶体の成形加工は、樹脂被覆ラミネートアルミニウム板を、絞り加工にてカップ状に成形する第１工程と、ついで第１工程で得たカップを更に再絞り加工し、第１工程で得たカップより缶径が小さく缶高さの高いカップを成形する第２工程と、このカップの缶壁部をパンチとしごきダイスの間に通し、缶壁を薄く伸ばすしごき加工を行う第３工程と、第３工程で得た缶体を適当な缶高さに切断するトリミングを行った後、缶開口部を縮径にするネック加工と天蓋を巻き締めるのに必要なフランジ加工を同一加工機で行う第４工程から基本的には成っている。
【０００９】
本発明の方法では、前記の第１工程であるカップの絞り加工、第２工程であるカップの再絞り加工、更には第３工程であるしごき加工で、それぞれアルミニウム板の板厚減少を伴った加工を行うが、第４工程であるネック加工およびフランジ加工ではアルミニウム板の板厚減少はない加工となっている。
したがって、缶壁部の板厚減少を伴う加工としては、第３工程を経た缶体が最終缶体となる。
【００１０】
本発明の方法における加工度とは、缶壁部の最も薄い部位のアルミニウム板厚（Ｗｔ）が、缶底部のアルミニウム板厚（Ｂｔ）との関係において、式（１）で求められる値を示す。
【数２】
加工度＝〔（Ｂｔ−Ｗｔ）／Ｂｔ〕×１００ ・・・（１）
【００１１】
本発明の方法では、第１工程の絞り加工はラミネート板の温度を被覆樹脂フィルムのガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲にして行うが、この絞り加工の際ストレッチ加工および／またはしごき加工を付加し、合わせて、第１工程後の加工度は式（１）で求められる値として１０％以内で行うことが好ましい。
【００１２】
第２工程の再絞り加工もラミネート板の温度を被覆樹脂フィルムのガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲において行うが、この再絞り加工の際もストレッチ加工および／またはしごき加工を付加し、第２工程の加工度は式（１）で求められる値として第１工程の加工度と合わせて２５％以内で行うことが好ましい。
【００１３】
第３工程のしごき加工後の、最終缶体の加工度は５０〜７０％の範囲で成形加工を行うことが好ましい。
【００１４】
式（１）から求められる値として、第１工程の絞り加工後の加工度を１０％以内で、第２工程の再絞り加工後の加工度を第１工程の加工度と合わせて２５％以内で行うことが好ましい理由は、一度に高加工を行うと、加工時の熱と伸ばし加工により、樹脂フィルムが配向結晶化し、成形に耐えられずフィルムに亀裂が発生する場合が有るのからであり、それを避けるためには、前記のように順次加工を行い、最終のしごき加工の加工度はなるべく低く抑える方が良い。このようにすれば、フィルムに亀裂が発生することなく缶内面の樹脂フィルムが健全な状態を維持している成形が可能となる。
【００１５】
なお本発明の方法では、前記の第１工程および第２工程で行う、ストレッチ加工および／またはしごき加工を付加した絞り加工および再絞り加工は、ストレッチ加工のみを付加した方法でも、しごき加工を付加した方法でも、ストレッチ加工としごき加工を付加した方法でも、いずれの方法でも良く、適宜適用される。
【００１６】
更に、第１工程の絞り加工および第２工程の再絞り加工を被覆樹脂フィルムのガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲に限定した理由は、絞り加工による缶底部コーナーの被膜健全性を確保するためである。絞り加工および再絞り加工による缶底部コーナーの被膜は、パンチが最初に当たる個所であり、高い衝撃が掛かる。従って、この部位の樹脂フィルムにマイクロクラックが生じた場合、その後のしごき加工で、激しい被膜欠陥となってしまう危険性が大きく、絞り加工による缶底部コーナーの被膜健全性確保は、缶体の内面品質からは重要な要素となる。かかる意味において、樹脂フィルムのガラス転移温度（Ｔｇ）以下での加工は、缶底部コーナーの樹脂フィルムにマイクロクラックが生じ易く、好ましくない。
【００１７】
また、冷結晶化温度（Ｔｃ）以上で絞り加工を行った場合は、樹脂の熱結晶化が起こり易くなり、樹脂フィルムの衝撃強度が低下し、缶底部コーナーの樹脂フィルムにマイクロクラックが生じやすく、好ましくない。特に、第１工程の絞り加工における缶底コーナー部は、第２工程の再絞り加工および第３工程のしごき加工では、缶壁部となるため、第１工程の絞り加工における缶底コーナー部の樹脂フィルムにマイクロクラックが発生した状態では、その後の再絞り加工およびしごき加工で、重大な欠陥と成ってしまう危険性が大きく、好ましくない。
【００１８】
第１工程の絞り加工および第２工程の再絞り加工を、被覆樹脂フィルムのガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲に限定したのは、上記の理由からで、好ましくはガラス転移温度（Ｔｇ）＋５℃から冷結晶化温度（Ｔｃ）−１０℃の範囲が良い。
絞り加工および再絞り加工に供するラミネート板やカップの温度とは、接触式温度計等で測定される表面温度を指し、ラミネート板やカップの温度を、被覆樹脂フィルムのガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲に制御する手段としては、ラミネート板やカップを電気炉中で加熱する方法や熱風で加熱する方法等、常用の手段が適用される。
また、絞り加工や再絞り加工を行う金型の表面温度を、ガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲に加熱して成形加工する加温加工方法も、ラミネート板やカップを加熱した場合と同様な効果が得られるが、この場合は、絞り加工や再絞り加工を行う前のラミネート板やカップの表面温度により、加工金型の設定温度を決める必要があるが、ラミネート板やカップの表面温度が、例えば常温の場合は、設定温度はガラス転移温度（Ｔｇ）より１０〜１５℃高めに設定すると良い。
また、上記の常用の手段でラミネート板やカップの加熱を、ガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲にして成形加工する方法と、加工を行う金型の表面温度を、ガラス転移温度（Ｔｇ）から冷結晶化温度（Ｔｃ）の範囲に加熱して成形加工する加温加工方法の併用も可能であり、設備にあった手段が採用できる。
次に、しごき加工について述べる。
本発明の方法では、しごき加工は、絞り加工で得たカップの缶体温度を５０℃以下にした後、加工金型の温度を１２０℃以下で行う。
前述した缶体内面の皮膜欠陥は、しごき加工で最も起こり易い。
その理由は、成形加工の際に金属の加工熱が発生し、樹脂フィルムの特性を大きく変化させるためである。
熱による樹脂フィルムの特性変化は、（１）樹脂フィルムの軟化、（２）樹脂フィルムの結晶化等があるが、いずれの特性変化も成形加工による皮膜欠陥の発生原因となる。
【００１９】
即ち、（１）樹脂フィルムが軟化した場合は、樹脂フィルムと成形加工金型との離型性が悪くなり、その結果離型時に樹脂フィルムに傷を付け易くなる。また、（２）樹脂フィルムが結晶化した場合は、アルミニウム板の成形加工形状に樹脂フィルムが追随し難くなり、その結果樹脂フィルムに欠陥が発生し易くなる。
【００２０】
従って、このしごき加工の温度制御は樹脂フィルムの欠陥発生防止の点から重要な要素で、本発明の方法では第２工程の再絞り加工で得たカップの缶体温度を５０℃以下とする。
カップの缶体温度が５０℃を超えると、樹脂フィルムと成形加工金型との離型性が悪く、樹脂フィルムが傷つき易く、缶体の内面側は耐食性確保が難しい。
また、外面側は「カジリ」といった、缶高さ方向への傷が入り易くなり、その後行われる印刷での外観性が劣り、好ましくない。
【００２１】
また、加工金型の温度は、５０〜１２０℃として再絞り加工およびしごき加工を行うが、１２０℃を超える温度では、樹脂フィルムと成形加工金型との離型性が悪く、樹脂フィルムの傷つきが激しくなって、缶内面側は耐食性確保が難しいと共に、場合によっては樹脂フィルムと成形加工金型との離型の際に缶胴部が座屈し、正常な缶体が得られないといった事態が発生することがある。
また、外面側は、前述した「カジリ」が激しく入り、その後行われる印刷での外観性が劣るだけでなく、場合によっては「カジリ」部を起点とする缶胴破断が起こり、好ましくない。
再絞り加工およびしごき加工の際、加工金型全体の温度を１２０℃以下で行うのが好ましいが、特に加工度が低い場合は、加工パンチの温度を１２０℃以下にするだけでも、樹脂フィルムの欠陥防止効果は得られる。
しごき加工の際の加工金型全体の温度、または加工パンチの温度は、基本的には低い方が良く、好適な温度としては１００℃以下にするのが好ましい。
なお、しごき加工はしごきダイスを１枚で行う１段しごき加工や、２枚ないしは３枚で行う多段しごき加工などが適用できる。
【００２２】
再絞り加工で得たカップの缶体温度を５０℃以下にする手段としては、絞り加工で得たカップが５０℃を超えている場合は冷風を当てる等の手法が採用でき、また、加工金型の温度を１２０℃以下にする手段としては、金型に冷却水を通す方法、水、又は潤滑成分を水に溶解または分散させたものを吹きかけて冷却する方法、更にはこれらの併用といった方法が採用できる。
どの手法を採用するかは、設備との関係で適宜選択することが好ましい。
【００２３】
次に、アルミニウム板について説明する。
本発明の方法に適用されるアルミニウム板は、通常缶容器に用いられる３００４系アルミニウム合金や５０５２系アルミニウム合金、５０８１系アルミニウム合金等種々のアルミニウム合金が適用される。
アルミニウム合金の板厚としては、０．２０ｍｍ〜０．３２ｍｍのものが適用される。
板厚が０．２０ｍｍ以下では、炭酸飲料やビール等を充填・密封する内圧缶の場合、耐圧強度が十分でなく缶底部が張り出した状態になる場合があり、好ましくない。
一方、０．３２ｍｍを超えた場合、缶の耐圧強度は十分に確保されるが、実質的には品質過剰であり、経済的でない。
【００２４】
板厚の限定理由は、上述のように缶の耐圧強度から限定したものである。
従って適用するアルミニウム合金板の機械的特性、特に耐力強度と関わりがある。即ち、耐力強度が高い場合は板厚の薄手化が可能となるが、実際に本発明を実施する際は、板厚は缶全体の強度バランスを考慮し、適宜選択することが望ましい。
【００２５】
次に、本発明の方法に適用される樹脂フィルムについて説明する。
本発明方法での樹脂フィルムは、ポリエステル樹脂フィルムが適用される。
ポリエステル樹脂は、例えばポリエチレンテレフタレート（ＰＥＴ）、ポリブチレンテレフタレート（ＰＢＴ）、ポリエチレンイソフタレート（ＰＥＩ）のようなホモポリマーや、例えばポリエチレンテレフタレートとポリエチレンイソフタレートとの共重合樹脂であるコーポリマーや、またこうしたホモポリマーのブレンド樹脂等が適用される。
【００２６】
樹脂フィルムの厚みとしては、１０〜５０μｍである。
缶の内面に当たる面に積層されるフィルム厚みは、缶内面の耐食性の点から限定されるものであり、１０μｍ未満では缶の成形加工後に充填する内容物にもよるが、十分な耐食性を確保するのは難しい場合がある。
一方、５０μｍを超えると、内容物に対し耐食性は十分確保されるが、実質的に過剰品質となり、経済的でない。
フィルム厚みとしては、１２〜４０μｍが品質および経済性からは好ましい範囲である。
【００２７】
また、本発明の方法を実施する際フィルム厚の選定は、後述する缶壁部の薄肉化の加工度との関係があることも選定の際の重要な要素である。
即ち、加工度が高い場合は、当然その加工度に応じフィルム厚みも薄くなるため、その結果として、缶内面の耐食性も低下する。従って予め厚手の樹脂フィルムを使用することが望ましいし、一方、加工度が低い場合はそれに応じて予め薄手のフィルムを適用することが可能となる。
【００２８】
本発明の方法に適用されるポリエステル樹脂フィルムの密度は１．３６ｇ／ｃｍ ３ 未満である。
密度は樹脂の結晶状態を示す指標となり、例えば、熱や延伸によって結晶化が進み、密度は大きくなる。密度が１．３６ｇ／ｃｍ ３ 未満であるということは、ポリエステル樹脂フィルムの結晶状態としては実質的に非晶質であることを示す。
従って、本発明の方法では、樹脂フィルムは、カップの絞り加工、カップの再絞り加工、更にしごき加工を行う直前のアルミニウム板に被覆された状態の樹脂フィルムと、ネック加工およびフランジ加工直前の缶体に被覆された状態の樹脂フィルムと、二度非晶質状態となる。
【００２９】
まず、樹脂被覆ラミネート材を非晶質にする理由は、その後行うカップの絞り加工、カップの再絞り加工、更にしごき加工において、樹脂フィルムの加工性を十分に確保することを目的にしたもので、密度が１．３６ｇ／ｃｍ ３ 未満では、成形加工にフィルムが耐えられずフィルム破断が起こる場合がある。特に、加工度が大きい時はこの傾向が顕著に現れ、缶体の耐食性が十分に確保できない。
【００３０】
また、ネック加工およびフランジ加工直前の缶体を加熱し、再度樹脂フィルムの状態を非晶質にする理由は、ネック加工及びフランジ加工に耐える加工性を有する樹脂フィルムにするためで、特に、ネック加工率の高いいわゆる高縮径缶体においては、樹脂フィルムの密度が１．３６ｇ／ｃｍ ３ を超えた場合はフィルム剥離が発生し易くなる。
従って、本発明の方法では、カップの絞り加工、カップの再絞り加工、更にしごき加工の缶成形加工を施した後、得られた缶体を加熱し再度樹脂フィルムの密度を１．３６ｇ／ｃｍ ３ 未満にした後、ネック加工およびフランジ加工を行う。
【００３１】
カップの絞り加工、カップの再絞り加工、更にしごき加工を経て得られる缶体は、この時の加工により、樹脂フィルムの密着性は著しく低下しており、この状態でネック加工およびフランジ加工を行うと、樹脂フィルムは剥離する。
そこで、本発明の方法では、缶体を加熱・冷却し再度樹脂フィルムの密度を１．３６ｇ／ｃｍ ３ 未満にした後、ネック加工およびフランジ加工に供するものである。
樹脂フィルムの密度を１．３６ｇ／ｃｍ ３ 未満にすることで、樹脂フィルムは剥離やクラックが発生することなくネック加工およびフランジ加工を行うことができる。
特に、ネック加工率が高い、高縮径化への対応については、樹脂フィルムの耐加工密着性が一層必要となり、この場合樹脂フィルムの密度は低い方が非晶質化度が高いため、良好となる。
樹脂フィルムの密度は、カップへの絞り加工やネック加工・フランジ加工前の状態として、好ましくは１．３５ｇ／ｃｍ ３ 未満が好適である。
【００３２】
【実施例】
以下、実施例にて、本発明の方法の効果を具体的に説明するが、その前に本発明の方法で行った評価方法について述べる。
（１）樹脂フィルムの密度は、密度勾配管法により測定した。
（２）樹脂フィルムのガラス転移温度（Ｔｇ）および冷結晶化温度（Ｔｃ）の測定は、示差走査熱量計（ＤＳＣ）で、１０℃／分の昇温速度で測定し、ガラス転移温度は転移が始まる点をその温度とし、また冷結晶化温度はピークをその温度とした。
（３）カップの絞り加工後の缶底部コーナーのマイクロクラックについては、光学顕微鏡で観察しその程度を評価した。評価は次のように評価基準を設定定して行った。
〇：クラックなく良好 □：軽微なクラック発生
△：明確なクラック発生 ×：激しいクラック発生
（４）再絞り加工およびしごき加工時の樹脂フィルムと加工パンチの離型性は、成形缶上部に起こる缶体の座屈程度を観察し評価した。また、缶外面に発生するカジリ程度は、傷付き程度を肉眼観察や光学顕微鏡で観察し評価した。
▲１▼離型性の評価は、次のように評価基準を設定し行った。
〇：缶開口部の座屈なく良好 □：軽微な缶開口部の座屈あり
△：開口部円周の１／３程度座屈 ×：開口部円周の１／３以上座屈
▲２▼カジリ性の評価は、次のように評価基準を設定し行った。
〇：カジリなく良好 □：軽微なカジリが１〜３本発生
△：明確なカジリが１〜３本発生 ×：激しいカジリ発生
（５）ネック加工及びフランジ加工での樹脂フィルムの状態については、剥離状況やクラック発生状況を肉眼観察や光学顕微鏡で観察し評価した。
剥離状況やクラック発生状況の評価は、次のように評価基準を設定し行った。
〇：剥離やクラックなく良好 □：軽微なクラック発生
△：一部剥離やクラック発生 ×：剥離発生
（６）缶内面の樹脂フィルムの傷付き程度については、１．０ｗｔ％食塩水に
界面活性剤０．１ｗｔ％を添加した電解液で、缶体を陽極、陰極は銅線とし、印加電圧６Ｖで３秒後の電流値を測定し、樹脂フィルムの被膜の健全性の評価とした（以下、この評価法をＱＴＶ試験と称する）。
【００３３】
実験例１
板厚０．２６ｍｍのアルミニウム板の両面に、ガラス転移温度（Ｔｇ）が６４℃、冷結晶化温度（Ｔｃ）が１１８℃の、厚み２０μｍのポリエステル樹脂フィルムを被覆したラミネートアルミニウム板に潤滑油を塗布した後加熱し、温度５０℃（テスト１）、７０℃（テスト２）、９０℃（テスト３）、１１０℃（テスト４）、１３０℃（テスト５）にて、加工度が７％のストレッチ加工およびしごき加工を付加したカップ絞り加工を行った。
この時得られたカップについて、缶底部コーナー樹脂フィルムのマイクロクラック発生状況について観察した。なお、カップ絞り加工する前のラミネート樹脂フィルムの密度は１．３４８ｇ／ｃｍ ３ である。
【００３４】
次いで、テスト２で得られたカップを温度７０℃にて加工度が２２％のストレッチ加工およびしごき加工を付加したカップ再絞り加工を行った後、缶体温度を３０℃（テスト６）、４０℃（テスト７）、５０℃（テスト８）、６０℃（テスト９）にした後、金型温度１００℃で加工率が６０％になるようにしごき加工を行った。
また、更に前記テスト５で得た再絞り加工後のカップについて、カップの缶体温度を４０℃（テスト１０）、６０℃（テスト１１）にした後、金型温度１００℃で最終加工度が６０％になるしごき加工を行った。
こうして得られた缶体について、樹脂フィルムと金型との離型性、外面樹脂フィルムのカジリ程度を観察すると共に、ＱＴＶ試験で缶内面樹脂フィルムの傷付き程度を測定した。
その結果を表１〜３に示した。
【００３５】
表１〜３から分かるように、本発明例は比較例と比較してカップの絞り加工で缶底部コーナーのフィルムに欠陥が入り難いことが分かる。また、その後の再絞り加工としごき加工においても、樹脂フィルムと金型パンチとの離型性やカジリ等も良好で、樹脂フィルムの欠陥も極微小でありＱＴＶ値は小さい。従って、樹脂フィルムの健全性が十分確保されていることが分かる。
【００３６】
実験例２
実験例１で用いたテスト２で得られた再絞り加工のカップを用いて、カップの缶体温度４０℃にした後、金型パンチ温度５０℃（テスト１２）、８０℃（テスト１３）、１００℃（テスト１４）、１２０℃（テスト１５）、１４０℃（テスト１６）にて、最終加工度が６０％になるようにしごき加工を行った。
こうして得られた缶体について、樹脂フィルムと金型との離型性、外面樹脂フィルムのカジリ程度を観察すると共に、ＱＴＶ試験で缶内面樹脂フィルムの傷付き程度を測定した。
その結果を表４に示した。
【００３７】
表３〜４から分かるように、本発明例は比較例と比較して、再絞り加工としごき加工においても、樹脂フィルムと金型パンチとの離型性やカジリ等も良好で、樹脂フィルムの欠陥も極微小でありＱＴＶ値は小さい。従って、樹脂フィルムの健全性が十分確保されていることが分かる。
【００３８】
以下の表中、＊1〜＊5は下記の説明のとおり。
＊1 ネック／フランジ加工前のフィルム密度を指す。
＊2 カップ内面缶底のコーナークラック状況を表わす。
＊3 ＱＴＶ試験のデーターであり、単位はｍＡ／缶である。
＊4 缶外面のカジリ性を示す。
＊5 ネック・フランジ部の剥離、クラック状況を表わす。
【００３９】
【表１】
次いで、温度７５℃にて加工度が１８％のストレッチ加工およびしごき加工を付加したカップ再絞り加工を行った後、カップの缶体温度を４５℃にした後、金型温度１００℃で加工度が６２％になるようにしごき加工を行った。
こうして得られた缶体について、樹脂フィルムと金型との離型性、外面樹脂フィルムのカジリ程度を観察すると共に、ＱＴＶ試験で缶内面樹脂フィルムの傷付き程度を測定した。
その結果を表５〜６に示した。
【００４１】
更に、前記テスト１９で得たしごき加工後の缶体を再度加熱と冷却を行い、樹脂フィルムの密度が１．３４６ｇ／ｃｍ ３ （テスト２３）、１．３５３ｇ／ｃｍ ３ （テスト２４）、１．３６９ｇ／ｃｍ ３ （テスト２５）の缶体を得た。次いでネック加工、フランジ加工を行い、樹脂フィルムの剥離とクラック発生状況について肉眼観察および光学顕微鏡で観察すると共にＱＴＶ試験でラミネート樹脂フィルムの健全性を調べた。
その結果を表６に示した。
【００４２】
【表５】
表５〜６からわかるように、本発明例は比較例と比較して再絞り加工としごき加工においても、樹脂フィルムと金型パンチとの離型性やカジリ等も良好で、樹脂フィルムの欠陥も極微小でありＱＴＶ値は小さい。
また、ネック加工およびフランジ加工においても、樹脂フィルムの健全性が十分確保されていることが分かる。
【００４４】
実験例４
板厚０．２４ｍｍの加熱されたアルミニウム板の両面に、ガラス転移温度（Ｔｇ）が５３℃、冷結晶化温度（Ｔｃ）が１１３℃の、厚み２０μｍのポリエステル樹脂フィルムをラミネートし、必要に応じ再加熱と急冷を行い、密度が１．３５７ｇ／ｃｍ ３ （テスト２６）、１．３５２ｇ／ｃｍ ３ （テスト２７）、１．３４７ｇ／ｃｍ ３ （テスト２８）、１．３６８ｇ／ｃｍ ３ （テスト２９）、１．３７５ｇ／ｃｍ ３ （テスト３０）のラミネートアルミニウム板を得た。
このラミネート材に潤滑油を塗布した後加熱し、温度６５℃にて加工度が７％のストレッチ加工およびしごき加工を付加したカップ絞り加工を行った。
この時得られたカップについて、缶底部コーナー樹脂フィルムのマイクロクラック発生状況について観察した。
【００４５】
次いで、６５℃にて加工度が２２％のストレッチ加工およびしごき加工を付加したカップ再絞り加工を行った後、缶体温度を４０℃にした後、金型温度８０℃で加工率５６％の再絞り加工およびしごき加工を行った。
こうして得られた缶体について、樹脂フィルムと金型との離型性、外面樹脂フィルムのカジリ程度を観察すると共に、ＱＴＶ試験で缶内面樹脂フィルムの傷付き程度を測定した。
その結果を表７に示した。
【００４６】
【表７】
表７からわかるように、本発明例は比較例と比較して、カップの絞り加工で缶底部コーナーのフィルムに欠陥が入り難いことが分かる。また、その後の再絞り加工としごき加工においても、樹脂フィルムと金型パンチとの離型性やかじり等も良好で、樹脂フィルムの欠陥も極微小でありＱＴＶ値は小さい。従って、樹脂フィルムの健全性が十分確保されていることが分かる。
【００４８】
実験例５
実験例１で用いたポリエステル樹脂フィルム被覆アルミニウム板に潤滑油を塗布した後加熱し、温度６５℃にて加工度が３％のストレッチ加工を付加したカップ絞り加工（テスト３１）、加工度が５％のしごき加工を付加したカップ絞り加工（テスト３２）を行った。
なお、比較のため温度６５℃にてストレツチ加工および／またはしごき加工を付加しないカップ絞り加工（テスト３３）も行った。
この時得られたカップについて、缶底部コーナー樹脂フィルムのマイクロクラック発生状況について観察した。
【００４９】
次いで、テスト３１および３２の絞り加工後のカップについては、温度６５℃にて加工度が２２％のストレッチ加工およびしごき加工を付加したカップ再絞り加工を行った後、缶体温度を４０℃にした後、金型温度１００℃で加工率６０％の再絞り加工およびしごき加工を行った。
【００５０】
また、テスト３３の絞り加工後のカップについては、温度６５℃にてストレッチ加工および／またはしごき加工を付加しないカップ再絞り加工を行った後、缶体温度を４０℃にした後、金型温度１００℃で加工率６０％の再絞り加工およびしごき加工を行った。
【００５１】
こうして得られた缶体について、樹脂フィルムと金型との離型性、外面樹脂フィルムのかじり程度を観察すると共に、ＱＴＶ試験で缶内面樹脂フィルムの傷付き程度を測定した。
その結果を表８に示した。
表８から、本発明例は、カップの絞り加工で缶底部コーナーのフィルムに欠陥、フィルムと金型パンチとの離型性やかじり等は比較例と差異はないが、本発明例の方が、樹脂フィルムの欠陥発生状況は比較例に比べ良好でＱＴＶ値は小さい。従って、樹脂フィルムの健全性が充分確保されていることが分かる。
【００５２】
【表８】
【発明の効果】
以上、説明したように、本発明の方法で得られる樹脂被覆アルミウムシームレス缶は、内面品質の良い、高耐食性を有する缶であり、ユーザーが安心して使用できるものである。
また、生産歩留まりも良いため、経済的にもメリットがあり、社会的ニーズに応えられる缶体であることから、その意義は大きいものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a resin-coated aluminum seamless can.
[0002]
[Prior art]
Metal cans / containers made of aluminum or steel are roughly classified into three-piece cans and two-piece cans based on their shapes. A three-piece can is called a three-piece can because it consists of a ground, a can body, and a canopy. On the other hand, the two-piece can is an integrated unit of a ground cover and a can body, and since it is composed of a canopy, it is also called a two-piece can or a seamless can because there is no joint in the can body.
[0003]
In the case of metal cans, the inner surface of the can is coated and used to ensure corrosion resistance. In recent years, laminated cans laminated with resin films have been developed and are on the market. Laminate cans are mainly formed by laminating a resin film on a metal material, and performing can body forming processing. In particular, in order to obtain a two-piece can, advanced forming processing technology is required. In this sense as well, many techniques relating to the two-piece laminate can have been proposed and disclosed, for example, in JP-A-7-2241, JP-A-7-195619, and JP-A-8-244750.
[0004]
The merit of laminated cans is, depending on the organic resin film to be applied, seen from the consumer side, but the first point is that they are excellent in content resistance, especially flavor such as taste and flavor of the contents. Yes. On the other hand, as a demerit, this time it is from the manufacturer side, but as described above, in the case of a two-piece can, the processing degree (or degree of deformation) of the organic resin film-coated metal plate is large, so the internal resin film is damaged during molding. The quality of the inner surface of the can cannot be ensured because it enters, so that it is necessary to strictly inspect the quality of the can body, and the product yield is inferior to that of the current paint can.
[0005]
In particular, in the case of a two-piece laminate can using a steel material, the above-mentioned tendency is large, but the same thing occurs in a laminate can made of an aluminum material. The film defects of the resin film on the inner surface of such laminated cans are entered during can molding as described above, and minimizing these defects is an important technical issue in terms of quality and product yield. Needless to say.
However, in the case of two-piece can molding with ironing, there is currently no suitable method, especially when the processing rate is high.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a high-quality seamless can having no film defects with a high yield.
[0007]
[Means for Solving the Problems]
In the present invention, a laminated aluminum plate obtained by coating a polyester resin film on both surfaces of an aluminum plate is drawn into a cup (first step), redrawn (second step) into a cup, and further ironed (third). In the method for producing a polyester resin-coated aluminum seamless can, wherein the polyester resin film coated on both sides of the aluminum plate is (1) polyethylene terephthalate, (2) polybutylene terephthalate, (3) polyethylene. The film is selected from the group consisting of isophthalate, (4) a copolymer resin of polyethylene terephthalate and polyethylene isophthalate, and (5) a blend resin thereof, and this film has a thickness of 10 to 50 μm and a density of 1.36 g. It will be in an amorphous state of less than / cm 3 After that, the drawing process to the cup in the first step is performed by adding the stretch process and / or the ironing process within the range of the glass transition temperature (Tg) of the coated resin to the cold crystallization temperature (Tc) of the resin. Next, redrawing of the cup in the second step is performed by adding stretch processing and / or ironing processing within the range of the glass transition temperature (Tg) of the coated resin to the cold crystallization temperature (Tc) of the resin. Next, after the cup body temperature is raised to 30 to 50 ° C., the ironing process in the third step is processed while maintaining the temperature of the working mold at 50 to 120 ° C., and the resulting can body is heated. The present invention relates to a method for producing a resin-coated aluminum seamless can characterized in that after cooling and again bringing the density of the resin film into an amorphous state of less than 1.36 g / cm 3 , neck processing and flange processing are performed.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the method of the present invention will be described in detail.
First, the can body forming process in the method of the present invention will be described.
In the method of the present invention, the can body is formed by a first step of forming a resin-coated laminated aluminum plate into a cup shape by drawing, and then redrawing the cup obtained in the first step. The second step of forming a cup having a smaller can diameter and a higher can height than the cup obtained in one step, and the can wall portion of this cup is passed through a punching die as a punch, and the can wall is thinned and subjected to ironing processing After performing trimming to cut the can body obtained in the third step and the third step to an appropriate can height, neck processing to reduce the diameter of the can opening and flange processing necessary to tighten the canopy It basically consists of the fourth process performed by the same processing machine.
[0009]
In the method according to the present invention, the cup drawing as the first step, the redrawing of the cup as the second step, and the ironing as the third step are accompanied by a reduction in the thickness of the aluminum plate, respectively. Although the processing is performed, the fourth step, which is neck processing and flange processing, is processing that does not reduce the thickness of the aluminum plate.
Therefore, as a process accompanied by a reduction in the plate thickness of the can wall, the can body that has undergone the third step becomes the final can body.
[0010]
The degree of processing in the method of the present invention is a value obtained by the formula (1) in which the aluminum plate thickness (Wt) of the thinnest portion of the can wall portion is related to the aluminum plate thickness (Bt) of the can bottom portion. .
[Expression 2]
Degree of processing = [(Bt−Wt) / Bt] × 100 (1)
[0011]
In the method of the present invention, the drawing process in the first step is performed by setting the temperature of the laminate plate in the range of the glass transition temperature (Tg) to the cold crystallization temperature (Tc) of the coated resin film. Further, it is preferable to add the ironing process, and the processing degree after the first step is preferably within 10% as the value obtained by the expression (1).
[0012]
The redrawing process in the second step is also performed in the range of the temperature of the laminate plate from the glass transition temperature (Tg) to the cold crystallization temperature (Tc) of the coated resin film. Processing is added, and the degree of processing in the second step is preferably 25% or less in combination with the degree of processing in the first step as a value obtained by Equation (1).
[0013]
After the ironing process in the third step, it is preferable that the final can body has a degree of processing of 50 to 70%.
[0014]
As a value obtained from equation (1), the degree of processing after drawing in the first step is within 10%, and the degree of processing after redrawing in the second step is within 25% when combined with the degree of processing in the first step. The reason why it is preferable to carry out is that if high processing is performed at once, the resin film may be oriented and crystallized due to heat and stretching during processing, and the film may not withstand molding and may crack. In order to avoid this, it is better to perform the processing sequentially as described above, and to keep the processing degree of the final ironing process as low as possible. If it does in this way, the shaping | molding in which the resin film of a can inner surface maintains the healthy state, without generating a crack in a film is attained.
[0015]
In the method of the present invention, the drawing process and the redrawing process to which the stretching process and / or the ironing process are performed in the first step and the second process described above are performed by the method of adding only the stretching process. Any of these methods may be used as appropriate, and any method may be used as appropriate, such as stretching and ironing.
[0016]
Furthermore, the reason why the drawing process in the first step and the redrawing process in the second step are limited to the range of the glass transition temperature (Tg) to the cold crystallization temperature (Tc) of the coated resin film is that This is to ensure the film integrity. The coating on the bottom corner of the can bottom by drawing and redrawing is the place where the punch hits first, and a high impact is applied. Therefore, if micro cracks occur in the resin film at this site, there is a great risk of severe film defects in the subsequent ironing process. From quality, it becomes an important factor. In this sense, processing below the glass transition temperature (Tg) of the resin film is not preferable because microcracks are likely to occur in the resin film at the corner of the bottom of the can.
[0017]
In addition, when drawing is performed at a temperature equal to or higher than the cold crystallization temperature (Tc), thermal crystallization of the resin is likely to occur, the impact strength of the resin film is reduced, and microcracks are likely to occur in the resin film at the corner of the bottom of the can. It is not preferable. In particular, the can bottom corner portion in the drawing process of the first step becomes a can wall portion in the redrawing processing of the second step and the ironing processing of the third step. In a state in which micro cracks are generated in the resin film, there is a great risk that it will become a serious defect in subsequent redrawing and ironing.
[0018]
The reason why the drawing process in the first step and the redrawing process in the second step are limited to the range of the glass transition temperature (Tg) to the cold crystallization temperature (Tc) of the coated resin film is as described above. A range from the glass transition temperature (Tg) + 5 ° C. to the cold crystallization temperature (Tc) −10 ° C. is preferable.
The temperature of the laminate and cup used for drawing and redrawing refers to the surface temperature measured with a contact thermometer, etc., and the temperature of the laminate and cup is determined from the glass transition temperature (Tg) of the coated resin film. Usable means such as a method of heating a laminate plate or cup in an electric furnace or a method of heating with hot air as the means for controlling the cold crystallization temperature (Tc) range.
In addition, there is a heating processing method in which the surface temperature of the mold for drawing and redrawing is heated to a range of the glass crystallization temperature (Tg) to the cold crystallization temperature (Tc). However, in this case, it is necessary to determine the set temperature of the processing mold depending on the surface temperature of the laminate plate and cup before drawing or redrawing. When the surface temperature of the plate or cup is, for example, room temperature, the set temperature is preferably set to be 10 to 15 ° C. higher than the glass transition temperature (Tg).
In addition, the method of molding the laminated plate or cup by the above-mentioned conventional means within the range of the glass transition temperature (Tg) to the cold crystallization temperature (Tc), and the surface temperature of the mold for processing, It is possible to use a warming processing method in which molding is performed by heating in the range of the glass transition temperature (Tg) to the cold crystallization temperature (Tc), and means suitable for the equipment can be employed.
Next, ironing will be described.
In the method of the present invention, the ironing is performed by setting the temperature of the working mold at 120 ° C. or lower after the temperature of the can body of the cup obtained by drawing is reduced to 50 ° C. or lower.
The aforementioned film defects on the inner surface of the can body are most likely to occur during ironing.
The reason is that metal processing heat is generated during the forming process, and the characteristics of the resin film are greatly changed.
The characteristic change of the resin film due to heat includes (1) softening of the resin film, (2) crystallization of the resin film, etc., and any characteristic change causes a film defect due to molding.
[0019]
That is, (1) when the resin film is softened, the releasability between the resin film and the molding die is deteriorated, and as a result, the resin film is easily damaged. Further, (2) when the resin film is crystallized, it becomes difficult for the resin film to follow the molded shape of the aluminum plate, and as a result, defects are likely to occur in the resin film.
[0020]
Therefore, the temperature control of the ironing process is an important factor from the viewpoint of preventing the occurrence of defects in the resin film. In the method of the present invention, the cup body temperature obtained by the redrawing process in the second step is set to 50 ° C. or less.
When the cup body temperature exceeds 50 ° C., the releasability between the resin film and the molding die is poor, the resin film is easily damaged, and it is difficult to ensure corrosion resistance on the inner surface side of the can body.
Further, the outer surface side is easily damaged, such as “galling”, and the appearance in printing performed thereafter is inferior.
[0021]
In addition, redrawing and ironing are performed at a processing mold temperature of 50 to 120 ° C. However, if the temperature exceeds 120 ° C, the releasability between the resin film and the molding mold is poor, and the resin film is damaged. However, it is difficult to ensure corrosion resistance on the inner surface of the can, and in some cases, the can body can buckle when the resin film and mold are released, and a normal can body cannot be obtained. May occur.
In addition, the above-mentioned “galling” enters the outer surface side violently, and the appearance of the subsequent printing is not only inferior, but in some cases, the can body breaks starting from the “galling” portion, which is not preferable.
During redrawing and ironing, the temperature of the entire processing mold is preferably 120 ° C. or lower. However, when the degree of processing is particularly low, the temperature of the processing punch can be reduced to 120 ° C. or lower. Defect prevention effect is obtained.
In general, the temperature of the entire processing die during the ironing process or the temperature of the processing punch is preferably low, and a preferable temperature is preferably 100 ° C. or less.
For the ironing process, a one-stage ironing process in which a single ironing die is used, or a multistage ironing process in which two or three sheets are used can be applied.
[0022]
As a means for lowering the can body temperature of the cup obtained by redrawing to 50 ° C. or lower, a technique such as applying cold air when the cup obtained by drawing is over 50 ° C. can be adopted. As a means for lowering the mold temperature to 120 ° C. or less, a method of passing cooling water through a mold, a method of cooling by spraying water or a solution in which a lubricating component is dissolved or dispersed in water, and a method of using these in combination Can be adopted.
It is preferable to select an appropriate method depending on the equipment.
[0023]
Next, the aluminum plate will be described.
Various aluminum alloys such as a 3004 series aluminum alloy, a 5052 series aluminum alloy, and a 5081 series aluminum alloy that are usually used in can containers are applied to the aluminum plate applied to the method of the present invention.
The thickness of the aluminum alloy is 0.20 mm to 0.32 mm.
When the plate thickness is 0.20 mm or less, in the case of an internal pressure can that is filled and sealed with carbonated beverages or beer, the pressure strength is not sufficient and the bottom of the can may be overhanging, which is not preferable.
On the other hand, if it exceeds 0.32 mm, the pressure resistance of the can is sufficiently secured, but the quality is substantially excessive and not economical.
[0024]
The reason for limiting the plate thickness is limited from the pressure strength of the can as described above.
Therefore, it is related to the mechanical properties of the aluminum alloy sheet to be applied, particularly the yield strength. That is, when the proof strength is high, the plate thickness can be reduced. However, when actually carrying out the present invention, the plate thickness is preferably selected in consideration of the strength balance of the entire can.
[0025]
Next, the resin film applied to the method of the present invention will be described.
A polyester resin film is applied as the resin film in the method of the present invention.
The polyester resin is, for example, a homopolymer such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene isophthalate (PEI), a copolymer such as a copolymer resin of polyethylene terephthalate and polyethylene isophthalate, Such a homopolymer blend resin is applied.
[0026]
The thickness of the resin film is 10 to 50 μm.
The thickness of the film laminated on the inner surface of the can is limited from the point of corrosion resistance of the inner surface of the can, and if it is less than 10 μm, depending on the contents to be filled after the can molding process, sufficient corrosion resistance is ensured. It can be difficult.
On the other hand, if it exceeds 50 μm, the corrosion resistance is sufficiently ensured for the contents, but it becomes substantially excessive quality and is not economical.
As film thickness, 12-40 micrometers is a preferable range from quality and economical efficiency.
[0027]
In addition, when the method of the present invention is carried out, the selection of the film thickness is also an important factor in the selection because it has a relationship with the degree of processing for reducing the wall thickness of the can wall described later.
That is, when the degree of processing is high, the film thickness is naturally reduced according to the degree of processing, and as a result, the corrosion resistance of the inner surface of the can is also reduced. Therefore, it is desirable to use a thick resin film in advance. On the other hand, if the degree of processing is low, a thin film can be applied in advance accordingly.
[0028]
The density of the polyester resin film applied to the method of the present invention is less than 1.36 g / cm 3 .
The density is an index indicating the crystalline state of the resin. For example, the crystallization proceeds by heat or stretching, and the density increases. A density of less than 1.36 g / cm 3 indicates that the crystalline state of the polyester resin film is substantially amorphous.
Therefore, in the method of the present invention, the resin film comprises a resin film coated with an aluminum plate immediately before performing cup drawing, cup redrawing, and ironing, and a can immediately before necking and flange processing. It becomes a resin film in a state of being covered with a body and an amorphous state twice.
[0029]
First, the reason for making the resin-coated laminate material amorphous is to ensure sufficient processability of the resin film in subsequent cup drawing, cup redrawing, and ironing. If the density is less than 1.36 g / cm 3 , the film may not be able to withstand the forming process, and film breakage may occur. In particular, when the degree of processing is large, this tendency appears remarkably, and the corrosion resistance of the can cannot be sufficiently ensured.
[0030]
The reason for heating the can body immediately before necking and flange processing to make the state of the resin film amorphous again is to make it a resin film having workability to withstand neck processing and flange processing. In a so-called high-reduction can body having a high processing rate, film peeling tends to occur when the density of the resin film exceeds 1.36 g / cm 3 .
Therefore, in the method of the present invention, after the drawing of the cup, the redrawing of the cup, and the can forming process of the ironing process, the resulting can body is heated and the density of the resin film is again set to 1.36 g / After making it less than cm 3 , neck processing and flange processing are performed.
[0031]
The can obtained by drawing the cup, redrawing the cup, and further squeezing has significantly reduced the adhesion of the resin film due to the processing at this time. In this state, the neck processing and the flange processing are performed. Then, the resin film peels off.
Therefore, in the method of the present invention, the can body is heated and cooled to make the density of the resin film less than 1.36 g / cm 3 again, and then subjected to necking and flange processing.
By setting the density of the resin film to less than 1.36 g / cm 3 , the resin film can be necked and flanged without peeling or cracking.
In particular, in order to cope with a high neck processing rate and a high diameter reduction, it is necessary to have higher resistance to processing adhesion of the resin film. In this case, the lower the density of the resin film, the higher the degree of amorphization. It becomes.
The density of the resin film is preferably less than 1.35 g / cm 3 as a state before drawing into the cup, necking and flange processing.
[0032]
【Example】
Hereinafter, the effects of the method of the present invention will be described in detail by way of examples, but before that, evaluation methods performed by the method of the present invention will be described.
(1) The density of the resin film was measured by a density gradient tube method.
(2) The glass transition temperature (Tg) and cold crystallization temperature (Tc) of the resin film are measured with a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min. The temperature at which the starting point was determined was the temperature, and the cold crystallization temperature was the peak.
(3) About the microcrack of the can bottom part corner after drawing of a cup, it observed with the optical microscope and evaluated the grade. The evaluation was performed by setting evaluation criteria as follows.
◯: Good without cracking □: Minor crack generation Δ: Clear crack generation ×: Severe crack generation (4) The releasability of the resin film and the processing punch during redrawing and ironing processing can occur at the top of the molded can The degree of body buckling was observed and evaluated. Further, the degree of galling generated on the outer surface of the can was evaluated by observing the degree of scratching with the naked eye or an optical microscope.
(1) Evaluation of releasability was performed by setting evaluation criteria as follows.
◯: good without buckling of can opening □: slight buckling of can opening △: buckling about 1/3 of the circumference of the opening ×: buckling more than 1/3 of the circumference of the opening ▲ 2 ▼ The evaluation of galling was performed by setting evaluation criteria as follows.
◯: Good without galling □: Minor galling occurs 1-3 △: Clear galling occurs 1-3: Excessive galling (5) The state of the resin film in the necking and flange processing is peeled off The situation and the occurrence of cracks were observed and evaluated with the naked eye and an optical microscope.
Evaluation of the peeling situation and crack occurrence situation was performed by setting evaluation criteria as follows.
◯: Good without peeling or cracking □: Minor cracking Δ: Partial peeling or cracking ×: Peeling occurrence (6) About the degree of scratches on the resin film on the inner surface of the can, 1.0 wt% saline solution The electrolyte was added with 0.1 wt%, the can body was an anode, the cathode was a copper wire, the current value after 3 seconds was measured at an applied voltage of 6 V, and the soundness of the coating film of the resin film was evaluated (hereinafter, This evaluation method is called QTV test).
[0033]
Experimental example 1
Lubricating oil is applied to a laminated aluminum plate coated with a 20 μm thick polyester resin film having a glass transition temperature (Tg) of 64 ° C. and a cold crystallization temperature (Tc) of 118 ° C. on both sides of an aluminum plate having a thickness of 0.26 mm. After coating, it is heated and processed at a temperature of 50 ° C. (Test 1), 70 ° C. (Test 2), 90 ° C. (Test 3), 110 ° C. (Test 4), and 130 ° C. (Test 5). Cup drawing with added stretch and ironing.
About the cup obtained at this time, the micro crack generation | occurrence | production situation of the can bottom part corner resin film was observed. The density of the laminated resin film before cup drawing is 1.348 g / cm 3 .
[0034]
Next, the cup obtained in Test 2 was subjected to cup redrawing with a stretch and ironing process having a processing degree of 22% at a temperature of 70 ° C., and then the can body temperature was set to 30 ° C. (Test 6), 40 After the temperature was set to 0 ° C. (Test 7), 50 ° C. (Test 8), and 60 ° C. (Test 9), ironing was performed at a mold temperature of 100 ° C. so that the processing rate was 60%.
Further, for the cup after redrawing obtained in Test 5, the cup body temperature was set to 40 ° C. (Test 10) and 60 ° C. (Test 11), and the final processing degree was reached at a mold temperature of 100 ° C. Ironing was performed to 60%.
With respect to the can thus obtained, the releasability between the resin film and the mold and the galling degree of the outer surface resin film were observed, and the degree of damage of the inner surface resin film was measured by a QTV test.
The results are shown in Tables 1-3.
[0035]
As can be seen from Tables 1 to 3, it can be seen that the example of the present invention is less likely to have defects in the film at the corner of the bottom of the can by drawing the cup as compared with the comparative example. Also in the subsequent redrawing and ironing, the releasability and galling of the resin film and the die punch are good, the defects of the resin film are extremely small, and the QTV value is small. Therefore, it can be seen that the soundness of the resin film is sufficiently secured.
[0036]
Experimental example 2
Using the redrawn cup obtained in Test 2 used in Experimental Example 1, the cup body temperature was set to 40 ° C., then the mold punch temperature was 50 ° C. (Test 12), 80 ° C. (Test 13), Ironing was performed at 100 ° C. (Test 14), 120 ° C. (Test 15), and 140 ° C. (Test 16) so that the final degree of processing was 60%.
With respect to the can thus obtained, the releasability between the resin film and the mold and the galling degree of the outer surface resin film were observed, and the degree of damage of the inner surface resin film was measured by a QTV test.
The results are shown in Table 4.
[0037]
As can be seen from Tables 3 to 4, the present invention example has better releasability and galling between the resin film and the die punch in redrawing and ironing as compared with the comparative example. The defects are extremely small and the QTV value is small. Therefore, it can be seen that the soundness of the resin film is sufficiently secured.
[0038]
In the following table, * 1 to * 5 are as described below.
* 1 Neck / Flange density before flange processing.
* 2 Shows the corner crack situation on the inner cup bottom.
* 3 Data from QTV test. The unit is mA / can.
* 4 Indicates the caulking property of the outer surface of the can.
* Indicates the state of peeling and cracking at the 5 neck and flange.
[0039]
[Table 1]
Next, after performing cup redrawing with the addition of stretch processing and ironing processing at a processing temperature of 18% at a temperature of 75 ° C., the cup body temperature was set to 45 ° C., and then the processing temperature at a mold temperature of 100 ° C. Ironing was performed so that the ratio was 62%.
With respect to the can thus obtained, the releasability between the resin film and the mold and the galling degree of the outer surface resin film were observed, and the degree of damage of the inner surface resin film was measured by a QTV test.
The results are shown in Tables 5-6.
[0041]
Furthermore, the can body after the ironing process obtained in Test 19 is heated and cooled again, and the density of the resin film is 1.346 g / cm 3 (Test 23), 1.353 g / cm 3 (Test 24). to obtain a can body of 1.369 g / cm 3 (test 25). Next, neck processing and flange processing were performed, and the peeling of the resin film and the occurrence of cracks were observed with the naked eye and an optical microscope, and the soundness of the laminated resin film was examined by a QTV test.
The results are shown in Table 6.
[0042]
[Table 5]
As can be seen from Tables 5 to 6, the present invention example has good releasability and galling between the resin film and the die punch, and the defect of the resin film, even in redrawing and ironing as compared with the comparative example. Is extremely small and the QTV value is small.
Moreover, it turns out that the soundness of the resin film is sufficiently ensured also in the necking and the flange processing.
[0044]
Experimental Example 4
A 20 μm thick polyester resin film having a glass transition temperature (Tg) of 53 ° C. and a cold crystallization temperature (Tc) of 113 ° C. is laminated on both sides of a heated aluminum plate having a thickness of 0.24 mm. Reheating and quenching are performed, and the density is 1.357 g / cm 3 (test 26), 1.352 g / cm 3 (test 27), 1.347 g / cm 3 (test 28), 1.368 g / cm 3 (test 29), to obtain a laminated aluminum plate of 1.375 g / cm 3 (test 30).
After applying a lubricating oil to this laminate material, it was heated, and a cup drawing process was performed at a temperature of 65 ° C. to which a stretch process and an iron process with a processing degree of 7% were added.
About the cup obtained at this time, the micro crack generation | occurrence | production situation of the can bottom part corner resin film was observed.
[0045]
Next, after performing cup redrawing processing at 65 ° C. with stretch processing and ironing processing having a processing degree of 22%, the can body temperature was set to 40 ° C., and the mold temperature was 80 ° C. and the processing rate was 56%. Redrawing and ironing were performed.
With respect to the can thus obtained, the releasability between the resin film and the mold and the galling degree of the outer surface resin film were observed, and the degree of damage of the inner surface resin film was measured by a QTV test.
The results are shown in Table 7.
[0046]
[Table 7]
As can be seen from Table 7, it can be seen that the example of the present invention is less likely to have defects in the film at the corner of the bottom of the can by drawing the cup as compared with the comparative example. Also in the subsequent redrawing and ironing, the releasability and galling of the resin film and the die punch are good, the defects of the resin film are extremely small, and the QTV value is small. Therefore, it can be seen that the soundness of the resin film is sufficiently secured.
[0048]
Experimental Example 5
After applying lubricating oil to the polyester resin film-coated aluminum plate used in Experimental Example 1 and heating, a cup drawing process (test 31) with a stretch process of 3% processing degree at a temperature of 65 ° C. has a processing degree of 5 Cup drawing (test 32) with an additional ironing process of% was performed.
For comparison, a cup drawing process (test 33) was also performed at a temperature of 65 ° C. without adding a stretching process and / or an ironing process.
About the cup obtained at this time, the micro crack generation | occurrence | production situation of the can bottom part corner resin film was observed.
[0049]
Next, with regard to the cups after the draw processing in tests 31 and 32, after performing cup redrawing processing with a stretch processing and ironing processing having a processing degree of 22% at a temperature of 65 ° C., the can body temperature was raised to 40 ° C. Then, redrawing and ironing were performed at a mold temperature of 100 ° C. and a processing rate of 60%.
[0050]
In addition, for the cup after the drawing process of Test 33, after performing the cup redrawing process without adding the stretch process and / or the ironing process at the temperature of 65 ° C., the can body temperature was set to 40 ° C., and then the mold temperature Redrawing and ironing were performed at 100 ° C. with a processing rate of 60%.
[0051]
With respect to the can body thus obtained, the releasability between the resin film and the mold and the galling degree of the outer surface resin film were observed, and the degree of damage of the inner surface resin film was measured by a QTV test.
The results are shown in Table 8.
From Table 8, the example of the present invention is not different from the comparative example in terms of defects in the film at the corner of the bottom of the can in the drawing process of the cup, the mold release property and galling of the film and the mold punch, etc. The defect occurrence state of the resin film is better than that of the comparative example and the QTV value is small. Therefore, it can be seen that the soundness of the resin film is sufficiently secured.
[0052]
[Table 8]
【The invention's effect】
As described above, the resin-coated aluminum seamless can obtained by the method of the present invention is a can with good inner surface quality and high corrosion resistance, and can be used with peace of mind by the user.
In addition, since the production yield is good, it is economically advantageous and is a can body that can respond to social needs, so its significance is significant.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13605298A JP4226104B2 (en) | 1998-04-30 | 1998-04-30 | Manufacturing method of resin-coated aluminum seamless cans |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13605298A JP4226104B2 (en) | 1998-04-30 | 1998-04-30 | Manufacturing method of resin-coated aluminum seamless cans |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11314123A JPH11314123A (en) | 1999-11-16 |
| JP4226104B2 true JP4226104B2 (en) | 2009-02-18 |
Family
ID=15166066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13605298A Expired - Fee Related JP4226104B2 (en) | 1998-04-30 | 1998-04-30 | Manufacturing method of resin-coated aluminum seamless cans |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4226104B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5125044B2 (en) * | 2006-09-25 | 2013-01-23 | 東洋製罐株式会社 | Method for producing resin-coated can |
-
1998
- 1998-04-30 JP JP13605298A patent/JP4226104B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11314123A (en) | 1999-11-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5582319A (en) | Can end formed from laminated metal sheet | |
| JP4278271B2 (en) | Laminated seamless can | |
| JP4226103B2 (en) | Manufacturing method of resin-coated aluminum seamless cans | |
| JP4103974B2 (en) | Polyester resin-coated aluminum seamless can and method for producing the same | |
| JP4226104B2 (en) | Manufacturing method of resin-coated aluminum seamless cans | |
| JP3986170B2 (en) | Polyester resin-coated aluminum seamless can and method for producing the same | |
| JP2803854B2 (en) | Composite steel sheet excellent in formability of drawn and ironed cans | |
| JP3949283B2 (en) | Polyester resin-coated aluminum plate for seamless cans and method for producing seamless cans | |
| JP4445787B2 (en) | Polyester resin film coated metal plate and polyester resin film coated metal can | |
| JP4278272B2 (en) | Film-coated two-piece can | |
| JPH0631362A (en) | Manufacture of multi-drawing can made of laminated steel sheet with high adhesion | |
| JP4278270B2 (en) | Film laminated two-piece can | |
| JP4297779B2 (en) | Method for producing polyester film-coated metal sheet | |
| JP2803837B2 (en) | Manufacturing method of polyester resin film laminated steel sheet | |
| JP4405301B2 (en) | Polyester resin film coated metal plate with excellent galling resistance | |
| JP4405300B2 (en) | Polyester film-coated metal plate and polyester film-coated metal can excellent in dent resistance | |
| KR20000005343A (en) | Manufacturing method for resin-coated aluminum alloy plate for drawing and ironing can | |
| JP4278273B2 (en) | Film-coated seamless can | |
| JPH02169246A (en) | Composite steel plate for can and processed can | |
| JP2000033430A (en) | Polyester resin-coated aluminum sheet for seamless can and production of seamless can using the sheet | |
| JP4297778B2 (en) | Method for producing polyester film-coated metal sheet | |
| JP4405299B2 (en) | Polyester resin film coated metal plate and metal can for metal can molding with excellent dent resistance | |
| JP3147031B2 (en) | Laminated body for cans and seamless cans | |
| KR20000005344A (en) | Method for manufacturing resin-coated aluminum alloy plate for drawn/1 ron ed(di)can | |
| JPH01180336A (en) | Preparation of composite steel excellent in di moldability |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050228 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20070125 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20070306 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20070501 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20071002 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20071121 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080513 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20080709 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20081125 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20081126 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313114 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 3 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111205 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121205 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121205 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131205 Year of fee payment: 5 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |