JP4393737B2 - Film sticking metal can - Google Patents

Description

この表１に示されるように、従来のシルバー顔料の個々のアルミフレークは、例えば、低輝度タイプのシルバー顔料の場合には、その粒径が１０μｍから２０μｍまでの範囲を占めるとともに、その平均粒径が１５μｍとされ、その厚みが５μｍから６μｍまでの範囲を占めるように形成されている。また、高輝度タイプのシルバー顔料の場合には、その粒径が２０μｍから３０μｍまでの範囲を占めるとともに、その平均粒径が２０μｍとされ、その厚みが５μｍから６μｍの範囲を占めるように形成されている。さらに、超高輝度タイプのシルバー顔料の場合には、その粒径が１０μｍから８０μｍの範囲を占めるとともに、その平均粒径が３０μｍとされ、その厚みが５μｍから８μｍの範囲を占めるように形成されている。
【００８１】
なお、表中に示した各シルバー顔料を含んだインキの輝度は、光沢度計を使用して計測され、この光沢度計の機種として、日本電色社製のＶＧＳ―３００Ａが使用されている。この測定機は、各種試料の色相および色差が測定でき、また、布地や塗膜、紙などの表面色の測定だけでなく、粉末試料の反射測定やフィルム、液体試料の透過測定を行うことができものである。また、測定された輝度は、これらのインキが印刷されたＰＥＴフィルム２の圧延方向に沿って測定した場合と、ＰＥＴフィルム２の圧延方向に対して直角方向（表中にＣ方向として表記した）に測定した場合とでは、僅かに異なることから、それぞれ、圧延方向の欄と、上記のＣ方向の欄に分けて、測定した結果を示した。
【００８２】
さらに、デザイン画などにより意匠を現わす第１印刷層３ａを網点印刷を用いて形成したことにより、このデザイン層の下層に形成された鏡面シルバーインキによる第２印刷層３ｂによって高輝度性を充分に発揮できるようにしている。
【００８３】
この網点印刷としては、例えば、グラビア印刷などが用いられ、このグラビア印刷に使用する印刷版を製版する方法としては、原画パターンを感光フイルムに焼き付け、次に、このフイルムパターンを感光剤を塗布した版材に焼き付け、電気分解によって非感光部を電蝕させるエッチング法や、フイルムを介さずにレーザースポットで感光させ同じく非感光部を電蝕させる方法や、円筒版材の外周面をダイヤモンドビットで直接彫刻することによって多数の微小凹部を作成する方法などがあるが、本例においては、上記のレーザー腐食製法が用いられているものとする。
【００８４】
また、一般に、グラビア印刷によって再現される画像の階調変化は、個々の網点の大きさや、印刷された単位面積当たりの網点数、各網点の印刷濃度の高低のいずれか、または、これらの組み合わせによって表現されている。
【００８５】
上記単位面積当たりの網点の数は、網点が印刷面に配置された細かさの程度を表わす網点線数（スクリーン線数とも呼ばれるが以降、単に線数と称する）により記され、単位１インチ（２５．４ｍｍ）を基準の単位として、その中に１列状（線状）に並んだ網点が何本あるかで示されている。また、一般に多用される上記線数は、１５０〜２５０線／インチとされ、このうちの１７５線／インチが最も使用される線数となっている。
【００８６】
なお、本例の鏡面シルバーインキを用いてグラビア印刷する印刷版のインキ量の目安は、例えば、この線数と、上記の網点を形成する印刷版に形成された凹部の深度とから、以下の通りに設定されている。すなわち、１５０線で版深度が３０μｍの場合には、インキ量の目安が１．５とされ、１７０線で版深度が２０μｍの場合には、インキ量の目安が１．０とされ、１７５線で版深度が１５μmの場合には、インキ量の目安が０．７５とされている。
【００８７】
そして、第２印刷層３ｂの鏡面シルバーインキ層の上層に不透明層が形成された場合には、図４（ａ），（ｂ）に示すように、第２印刷層３ｂのシルバー顔料に反射した光が、この上層の不透明層によって隠蔽されてしまうことから、全面的な反射とならないので、第２印刷層３ｂの鏡面シルバーインキ層による鏡面性が充分に得られなかった。
【００８８】
そこで、任意の色の鏡面印刷を行なう場合には、図３（ａ），（ｂ）に示すように、有色インキを網点状に印刷して、第２印刷層３ｂの鏡面シルバーインキ層の上層に第１印刷層３ａを形成することによって、この第１印刷層３ａを第２印刷層３ｂの鏡面シルバーインキ層からの反射光が通過できるように構成でき、有色インキによる発色を確保しながら、鏡面シルバーインキ層の鏡面性による反射効果を充分に発揮させることができる。この結果、有色インキによるデザイン画などの装飾効果に、鏡面シルバーインキ層による高輝度感を附加することができる。
【００８９】
なお、第１印刷層３ａは、その個々の網点の合計面積が、着色の対象領域の単位面積当たり２０〜４０％を占有する面積となるように設定されている。この網点の面積率％は、印刷された網点が単位面積当たりに占有した面積率％として現わされ、本例においては、２０〜４０％が選択され、デザイン画による意匠効果と鏡面シルバー顔料による装飾効果とを相乗的に作用させて、特有な装飾効果を得られるようにしている。
【００９０】
すなわち、上記の網点の面積率％が２０％未満の場合には、着色顔料が少ないので、第１印刷層３ａ自体による意匠性が充分に発揮されなくなる不都合が生じる。他方、網点の面積率％が４０％を越えた場合には、第２印刷層３ｂによる反射光が第１印刷層３ａ自体により遮断された状態となり、従来より高い光輝感を付与する効果が得られないことになる。そこで、上記の網点の面積率％を２０〜４０％の範囲に設定することにより、両者の装飾効果を充分に発揮させることができるので、単独では得られない相乗的な装飾効果を得ることが可能となる。
【００９１】
また、本具体例においては、上記網点の形状を円形に形成した例を説明したが、これ以外に菱形、チェーンドットなどように形成してよく、缶体１に施されるデザインなどの要請に応じて、適宜、網点形状を選択してよい。
【００９２】
さらに、リーフ状に形成されたアルミニウム蒸着剥離片を第２印刷層３ｂに配合させた構成によって、鏡面状の表面による光沢を充分に得られるようにしている。
【００９３】
すなわち、従来は、ＰＥＴフィルム２面に対し印刷によるインキ面の表面が平滑ではないので、その下層のシルバーインキ層も平滑が失われてしまうことになった。また、従来のシルバーインキのアルミフレークはリーフ状に形成されてなく、粒状に形成されていることから、これらの粒状のフレークからなる印刷表面は平滑とならないので、この印刷層の表面を印刷見本と比較して、充分になめらかな表面が得られないことになり、その表面で乱反射が生じて、鏡面状の表面による光沢感を出現させることができなかった。
【００９４】
しかし、本具体例の鏡面シルバーインキのアルミフレークを、リーフ状に形成されたアルミニウム蒸着剥離片としたことにより、フレークの厚さが薄いので、このフレークが配合された第２印刷層３ｂの表面の平滑さを安定して確保でき、表面での乱反射が防止され、鏡面状の表面による光沢を充分に得ることができる。
【００９５】
さらに、リーフ状のアルミニウム蒸着剥離片を隙間なく敷き詰めることにより、例えば、アルミフレークが配合された第２印刷層３ｂを１層だけでなく、２層以上に連続させることによって、第２印刷層３ｂによる隠蔽性を向上させて、表面の鏡面反射性を得るようにしている。
【００９６】
すなわち、従来のシルバー顔料は、その顔料を構成するフレークの形状が粒状に形成されていたので、粒径が大きい、つまり輝度が高い程、顔料同士の間の隙間が多くなっていた。したがって、鏡面状の全面反射を得るためには、この隙間を埋める必要があることから、シルバーインキ層を厚くして対処していた。このため、インキの使用量が増加したり、印刷工程が複雑化したりして、製造コストの上昇を招く不都合が生じた。
【００９７】
これに対して、本具体例の鏡面シルバー顔料によれば、その顔料のフレークが薄いリーフ状に形成されているので、フレークが薄膜中でも重なり合って、フレーク同士の間に隙間が生じないことになり、薄膜でも鏡面性を得られることになる。つまり、印刷層の表面に充分な鏡面性が確保できるので、印刷表面に対する入射光を全面反射させることが可能となり、充分な光輝感を得ることができる。
【００９８】
また、従来のシルバー顔料と比較して、本例の鏡面シルバー顔料は動粘度が低いことから、従来と同一の粘度のインキ中においても、鏡面シルバー顔料が泳ぎ現象を発生させやすい傾向があるので、可能な限り薄膜で印刷することが好ましい。
【００９９】
すなわち、高い流動性を有したインキ中に分散されたアルミフレークは、その厚みが薄く、かつリーフ状に形成されていることにより、インキの溶剤成分が蒸発するのに伴って、印刷の対象面に対して個々のアルミフレークが平坦状に折り重なることになるので、これらの積み重ねられたアルミフレーク同士の間に影が生成されるような大きな隙間が生じることが解消される。この結果、高輝度のメタリック感を現出させることができる。
【０１００】
なお、従来のシルバー顔料を含んだインキと、本例の鏡面シルバー顔料を含んだインキとを、ザーンカップ♯３によって同一の印刷粘度を有するように調整した場合にも、これらの両者をＢ型回転粘度計によって、それぞれの粘度を測定すると、以下の表２に示すように、明らかに鏡面シルバー顔料のインキの方が、その粘度が低く、かつその粘性も少ない比較結果が得られた。
【０１０１】
【表２】

なお、各インキは、オリフィス径が３ミリのザーンカップ＃３から規定量が流出するまでの時間が１６．５秒となるように、ケトン系希釈溶液としてＤＳＫレデューサーＳ―５を用いて、各インキを希釈することによって調整し、希釈後に直ちにＢ型回転粘度計による測定を行なった。また、各インキを測定した時の測定温度は、２３度に設定された。
【０１０２】
また、このＢ型回転粘度計は、測定対象とした資料の液体中で円筒または円板を回転させたときに、円筒または円板に対して作用する液体の粘性抵抗トルクを測定する構成とされている。
【０１０３】
さらに、表中に示されたチキソトロピー（ｔｈｉｘｏｔｒｏｐｙ）とは、揺変性とも呼称され、撹拌すると流動性が増加し、その後に一定時間だけ静置すると流動性を失うチキソトロピー現象のことを意味し、印刷インキはチキソトロピー性を有する粘性物とされ、表中のＴＩ値により、各インキにこのような現象が生じる程度を示している。また、チキソトロピー性の強いインキは、印刷版によって指定された印刷の寸法や色の再現性、およびインキの厚盛り性に優れているが、レベリング性が良くないとされている。なお、このチキソトロピーは、一般に、せん断速度の増加によって粘度が上昇する現象を意味するダイラタンシーに対応する言葉として用いられることが多い。
【０１０４】
また、鏡面シルバーインキには、インキの貯蔵安定性を良好にするために、必要に応じてポリエチレンワックスなどの沈降防止剤を添加することにより、インキのチキソトロピー性を向上させて確保するようにしている。
【０１０５】
また、鏡面シルバー顔料をインキ化した鏡面シルバーインキの粘度が、上記ザーンカップ＃３による計測で、１５秒を下回ると、その印刷結果に「泳ぎ」という現象が発生しやすくなる一方、１７秒を上回ると、「スクリーニング」という現象が生じやすくなり、どちらかの一方の現象が生じた場合には、良好な外観性が確保された印刷面が得られないという不都合が生じる。
【０１０６】
このように、上記シルバーインキの粘度設定は、印刷の塗面における仕上がり状態に対して重要な因子となっているので、上記のザンカップ＃３による計測結果が１６±１秒の範囲に収まるように、希釈剤などを用いて、鏡面シルバーインキの粘度を調整している。
【０１０７】
また、鏡面シルバーインキ中の鏡面シルバー顔料が沈降しやすいことから、その使用前に十分に撹拌してから印刷を開始するとともに、その印刷の実行時には、インキパンと貯蔵タンクとインキを循環させる構成とすること、およびダイヤフラム方式などにより、常に上記の所定粘度に調整することが必須とされている。
【０１０８】
したがって、例えば、本例においては、その印刷装置を含んだ製造ラインのインキ粘度コントローラとして、英国のプレステック社製ビスコメックス５００（Ｖｉｓｃｏｍｅｘ５００）を用いて、印刷中でも連続的かつ正確に、上記の粘度に自動的に調整するようにしている。
【０１０９】
なお、上記の泳ぎ現象とは、印刷面の平滑であるべきベタ部分に、流れたような細かい濃淡のむらや、小さい斑点状の模様（モットリング）が生成されてしまう現象で、印刷面の外観が不良になってしまう。また、スクーリーニング現象とは、本来、インキで完全に覆われて平滑なベタ面となる印刷部分が、版の網点から転移したインキが充分にレベリングしないので、スクリーン目が現れる現象で、印刷の外観性が低下するとともに、重ね印刷を行なった場合に、その後刷りのインキによって発生しやすいことが知られている。また、レベリングとは、版から印刷対象の表面に移動されたインキの表面が平らになることである。
【０１１０】
そして、前者の泳ぎ現象が生じる原因として、以下の４つの原因が挙げられる。
【０１１１】
すなわち、１）インキが印刷対象の表面に転移してから乾燥するまでの間に、インキ層内で流動や対流などが発生しやすくなっている場合で、この要因としては、ａ）インキ粘度が低い、ｂ）印刷スピードが遅い、ｃ）版深度が深い、ｄ）テンションバランスが不良などが考えられる。
【０１１２】
また、２）インキの流動性が悪く、インキが転移してから乾燥するまでの間に、顔料や樹脂が凝集しやすくなっている場合で、この要因としては、例えば、ａ）チキソトロピー性の強いインキを使用した、ｂ）ゲル化、増粘したインキ、ソアリングの状態のインキを使用した、溶剤バランスを崩したインキの使用や、タイプの異なるインキを混合したり、希釈溶剤を間違えて使用したときなどが考えられる。
【０１１３】
さらに、３）印刷対象とされた原反つまりＰＥＴフィルム２に偏肉があるので、部分的に弛みなどが生じた場合や、４）静電気による障害が生じた場合などが挙げられる。
【０１１４】
上記の１）および２）の原因に対する対策としては、可能な限りインキの粘度を高く調整するとともに、印刷のスピードを上昇させることが挙げられる。
【０１１５】
また、１）および２）に対する対策としては、改版を行うことが挙げられる。すなわち、版深が浅く、土手幅が狭く設定された印刷版に交換したり、スクリーンのメッシュ数を多くしたり、スクリーン角度を変えたりすることが挙げられる。
【０１１６】
上記の２）の対策としては、インキが使用されている状態を確認して、インキを確認したり、または、インキのソアリング状態、流動性不良と増粘、ゲル化などを解消させるために、各種の補助剤を添加してインキの粘度を再調整したり、さらには、使用しているインキのインキメーカーへ直接問い合わせたりすることが挙げられる。
【０１１７】
上記の３）の対策としては、原反を確認し、交換することがが挙げられる。
【０１１８】
上記の４）の対策としては、静電気による障害を解消するために、ａ）原反が静電気を帯びやすいときには、原反を帯電防止タイプなどに変更し、ｂ）印刷機の陰電が十分でないときには、陰電器具の清掃やアースの確認を行なったり、除電方法の検討を行ない、ｃ）インキが帯電しやすいときには、帯電防止剤を添加し、ｄ）印刷室内の湿度が低いときには、印刷室内に撒水したり、加湿器を用いるなどして、湿度を上昇させることが挙げられる。
【０１１９】
なお、全ての静電障害に対しては、ａ）原反を帯電防止タイプなどに変更する、ｂ）除電器具の清掃やアースを確認し、除電方法の検討を行なう、ｃ）帯電防止剤を添加する、ｄ）印刷室内の湿度を撒水や加湿器などで適切に調整する、ｅ）静電気によって印刷の境界部分にひげが発生したときはインキ粘度を上げる、ｆ）印刷の画線部分の周囲にインキが霧状に付着したミスチング現象が発生したときには、インキが低粘度の場合が多いので、溶剤やコンパウンドを適宜添加する、ｇ）その他の印刷トラブルについては帯電防止剤を添加することが挙げられる。
【０１２０】
また、上記のスクーリーニング現象が生じる主な原因として、以下の６つの原因が挙げられる。
【０１２１】
すなわち、１）インキの粘度が高く、インキがレベリングしない場合、２）インキの乾燥が早いので、インキがレベリングする前に乾燥してしまう場合、３）先に印刷した印刷面と後刷りのインキとの濡れ性が悪いので、レベリングしない場合、４）印刷時にスキージが版を通して被印刷物に加える圧力である印圧が不足する場合、５）セルの土手幅が広いので、インキがレベリングしない場合で、シリンダー面が摩耗して版深が浅く、土手幅が広くなっている。また、スクリーン角度が４５度以外に設定されているときには、印刷面に斜めのラインが入りやすいことが知られている。６）インキ量が少ないなどによって、ドクターの位置までインキが充分に上がっていない場合が挙げられる。
【０１２２】
そして、上記の１）から３）まで原因に対する対策としては、インキ粘度を低下させたり、遅乾性の溶剤を併用して、インキの乾燥速度を低下させるとともに、ドクターの位置を可能な限り圧胴に近づけた設定とすることが挙げられる。
【０１２３】
また、上記の４）に対する対策としては、先に印刷したインキにマット剤を添加し、印刷対象の表面積を大きくして、濡れ性を向上させることが挙げられる。
【０１２４】
上記の４）の対策としては、印圧を上昇させることが挙げられる。
【０１２５】
上記の５）の対策としては、土手幅を狭くするなどの改版を行なうことが挙げられる。
【０１２６】
上記の６）の対策としては、インキパンを上昇させた位置に設置したり、インキ量を追加することが挙げられる。
【０１２７】
すなわち、本例の鏡面シルバーインキを用いるグラビア印刷装置５１は、例えば、図５に示すように、所定径の円筒形状に形成された版ロール５２を回転可能に軸支し、その外周面の全周には、上記の網点セルを印刷するための多数の微小凹部５２ａが形成されている。この版ロール５２は、その下側の外面がインキパン５３に充填されたインキＡ中に浸されており、版ロール５２が回転駆動されることにより、版ロール５２の全微小凹部５２ａ内にそれぞれインキＡを貯留できるようにしている。
【０１２８】
なお、版ロール５２の外周面に付着した余分なインキＡは、インキドクターブレード（以降、ドクターと呼称する）５４によって掻き落とされる。
【０１２９】
また、版ロール５２の外周面には、圧胴５５が版ロール５２の回転に従動して回転可能に接触されており、この圧胴５５と版ロール５２間にＰＥＴフイルム２が通されるように構成されている。
【０１３０】
そして、このグラビア印刷装置では、版ロール５２の一部をインキパン５３内に浸した状態で回転させることにより、全微小凹部５２ａ内にインキＡを貯留させ、ドクター５４で余分なインキＡを掻き落とした後、微小凹部５２ａ内に残留されたインキＡを印刷基材であるＰＥＴフィルム２に転写（印刷）するようにしている。
【０１３１】
上記ドクター５４の材質は、通常のＭＤＣ（スウェーデン鋼）タイプが使用され、ドクター５４を版ロール５２に接触させるための圧力設定は、通常の使用圧にするとシェアーによる顔料の凝集が認められるので、通常よりも弱めの設定とされている。
【０１３２】
すなわち、このドクター５４は、エアーシリンダー（図示せず）によって、版ロール５２に接近する方向に押圧されるように構成され、この版ロール５２の全周の長さである面長１２００ｍｍに対して、このエアーシリンダー圧を加減することにより、ドクター５４が版ロール５２に接触される圧力（以降、ドクター圧と称する）が調整され管理するようにしている。このシリンダー圧力の範囲は、０．６ｋｇ〜１．２ｋｇに管理されているが、０．３ｋｇ〜１．８ｋｇの範囲でも、印刷は可能とされている。
【０１３３】
したがって、上記ドクター圧は、通常、その線圧で０．００２５〜０．０１５ｋｇ／ｃｍの範囲に管理されているが、本例の鏡面シルバーインキを用いる場合は、０．００２５〜０．０１ｋｇ／ｃｍの範囲内に管理されて、印刷を実施するようにしている。
【０１３４】
なお、ドクター圧が上記の適正な範囲の値を越えて維持されると、ドクターの接触部分の摩耗や、版ロール５２に設けられた版胴の表面へのキズ付きが多くなるので、部品の交換が必要となり、運用コストが上昇するため経済的に好ましくない。また、インキの顔料によっては、ドクターの裏側にインキの凝集物が形成されてしまうので、印刷面にドクター筋が生成されるなどの印刷結果に不良が発生してしまう。さらに、ドクター圧が上記の適正な範囲の値より低くなると、ドクター切れが悪くなり、インキかぶり他、印刷上の品質不良を引き起こすことが知られている。
【０１３５】
上記印刷装置による本例の鏡面シルバーインキの厚みは、１〜３０ｍｇ／平方デシメートルの範囲で設定されていることが望ましく、より有効な範囲として、３〜１５ｍｇ／平方デシメートルが好ましい。
【０１３６】
すなわち、１ｍｇ／平方デシメートル未満では、鏡面シルバー顔料の密度が低いことから、鏡面状の光沢が十分に得ることができない。
【０１３７】
また、３０ｍｇ／平方デシメートルを越えた場合には、インキとしての凝集力が充分に得られないことから、その後の製缶加工によって、印刷層が形成されている缶体が変形された場合には、印刷層による高輝度感を充分に確保することができない。
【０１３８】
すなわち、例えば、ラミネート缶の場合には、ラミネート後の製缶加工、特にネック加工のような缶体の一部を圧縮させることを主体とした加工である場合および、エキスパンド加工のような缶体の一部を延伸させることを主体とした加工である場合のいづれの加工にも、加工による変形にインキが追従できなくなるので、第２印刷層３ｂの表面の鏡面状態が維持されなくなり、この箇所の高輝度感が損なわれて印刷面の外観性が低下してしまうことになる。
【０１３９】
特に、缶の内容物が食品であり、缶に内容物が充填された後に殺菌のためにレトルト処理などの殺菌工程が実施される場合には、缶全体が１００℃から１４０℃の高温に晒されるので、上記の製缶工程の加工処理によって変形された印刷箇所には、そのインキの弛緩によるインキ凝集の破壊が顕著に観られることになり、上記と同様に表面の鏡面状態が損なわれてしまい、さらに高輝度感が損なわれてしまう。
【０１４０】
なお、インキソリッドに関しては、比重に大きく影響する成分の配合比率は、樹脂：鏡面シルバー顔料の比率が１２：２０となるように設定されている。なお、この場合には、樹脂はウレタン−塩化ビニルＳ．ｇ．１．１を鏡面シルバー顔料はアルミペーストＳ．ｇ．２．７を用いるものとする。
【０１４１】
したがって、この条件を満たす、鏡面シルバーインキのドライの比重は、２．１となる。因みに、３ｍｇ／平方デシメートルはＯ．３ｇ／平方メートルに相当し、上記のように鏡面シルバーインキのドライの比重が２．１のときに、その膜厚は０．１４μｍとなる。
【０１４２】
以上のように、この具体例のフィルムが貼着された金属缶によれば、ＰＥＴフィルムがその一方の面に設けられた接着剤層によって缶体材料用の金属板に接着されて保護被覆層を形成するときに、ＰＥＴフィルムに設けられている第１印刷層および第２印刷層によって、上記の金属板に直接塗装を施すことなく、金属板の缶外面側に所定の表示およびデザインの画像を形成することができるとともに、第１印刷層と缶体材料用の金属板の金属下地との間に金属蒸着剥離片が混入された樹脂組成物からなる第２印刷層を介在させた構成としたことにより、第１および第２印刷層の印刷が缶体を構成する金属下地の色調に支配されることがなくなり、さらには第２印刷層によって缶体の外面に現わされた所定の表示およびデザインの画像に、従来以上のメタリック感、いわゆる鏡面状の光沢感を有する特殊な色調を付与することができる。
【０１４３】
すなわち、第２印刷層を構成する樹脂組成物に混入されたアルミニウム蒸着剥離片がリーフ状に形成されていることにより、このアルミニウム蒸着剥離片が配合された第２印刷層の表面の平滑さが安定して確保され、表面での乱反射が防止されるとともに、個々のアルミニウム蒸着剥離片が平坦状に折り重なるので、これらの積み重ねられたアルミニウム蒸着剥離片同士の間に影が生成されるような大きな隙間が生じることが解消され、入射光に対して鏡面状の表面による全面反射が可能になり、従来以上の高輝度感を得ることが可能になる。この結果、従前のシルバー顔料を用いた金属缶に比較して、鏡面性の高い光沢による光輝感を得ることができ、美粧性やデザイン面での優位性を確保することができ、その内部に収容した商品イメージを反映できる意匠性の優れた金属缶を提供することができる。
【０１４４】
また、第２印刷層を、リーフ状のアルミニウム蒸着剥離片を樹脂組成物によってインキ化した印刷インキを、平方デシメートル当たり１〜３０ｍｇの範囲内の密度で設置して形成した構成としたことにより、インキの凝集力を充分に確保することができるので、インクの印刷適性を適切に設定できるとともに、この第２印刷層による鏡面状の光沢感を得ることを維持しながら、その後の製缶工程による変形加工に第２印刷層を構成するインクを追従させることができ、このような変形加工による印刷面の外観性が低下することを防止することができる。
【０１４５】
さらに、アルミニウム蒸着剥離片がリーフ状に形成され、従来よりも小さく薄いことにより、アルミニウム蒸着剥離片が配合された樹脂組成物から形成された印刷層の膜厚を薄くしても、膜表面の平滑さを安定させて確保することができるので、印刷層の表面での乱反射が防止できるとともに、印刷層による隠蔽性をさらに向上させることができ、印刷層に鏡面状の光沢が付与された優れた美粧性を得ることができる。
【０１４６】
すなわち、上記のアルミニウム蒸着剥離片が、印刷層を形成する薄膜中でも重なり合って、アルミニウム蒸着剥離片同士の間に隙間が生じないことになり、薄膜でも、この印刷層の表面に全面反射が可能な鏡面性を得ることができる。
【０１４７】
また、リーフ状のアルミニウム蒸着剥離片が配合されている第１印刷層あるいは第２印刷層のポリエステルフィルム側の上面に、顔料による着色領域の単位面積当たり２０〜４０％の占有面積となるように印刷層が形成されていることにより、この第１印刷層の下層となる第２印刷層に含まれたアルミニウム蒸着剥離片に反射した光が第１印刷層によって隠蔽されないことになり、第２印刷層の鏡面性による光輝効果を充分に発揮させることができる。
【０１４８】
この結果、アルミニウム蒸着剥離片が配合された樹脂組成物によって形成された第２印刷層による光輝感の効果を充分に発揮させながら、顔料の着色による第１印刷層の装飾効果を確保できることになり、第２印刷層の光輝感を第１印刷層の顔料による装飾に附加することができるので、両者の相乗効果によって缶体の外面に現わされた装飾における視覚上の印象を充分に確保することができ、優れた美粧性を得ることができる。
【０１４９】
ここで、具体例の構成とこの発明の構成との対応関係を説明すれば、缶体１がこの発明の金属缶に相当し、ＰＥＴフィルム２がこの発明の熱可塑性樹脂フィルムに相当し、印刷層３ａがこの発明の有色インキを網点状に印刷した印刷層に相当し、印刷層３ｂがこの発明の金属蒸着剥離片が混入された樹脂組成物からなる印刷層に相当し、接着剤層４がこの発明の接着剤層に相当し、鏡面シルバー顔料がこの発明の金属蒸着剥離片に相当する。
【０１５０】
【発明の効果】
以上説明したように、請求項１の発明によれば、第２印刷層を構成する樹脂組成物に混入されたアルミニウム蒸着剥離片が、粒径（縦方向の長さおよび横方向の長さ）が５〜１０μｍで厚さが０．０１〜０．５μｍのリーフ状に形成されていることにより、このアルミニウム蒸着剥離片が配合された第２印刷層の表面の平滑さが安定して確保され、表面での乱反射が防止されるとともに、個々のアルミニウム蒸着剥離片が平坦状に折り重なるので、これらの積み重ねられたアルミニウム蒸着剥離片同士の間に影が生成されるような大きな隙間が生じることが解消され、入射光に対して鏡面状の表面による全面反射が可能になり、第２印刷層によって缶体の外面に現わされた所定の表示およびデザインの画像に、従来以上のメタリック感、いわゆる鏡面状の光沢感を有する特殊な色調を付与することができる。また、従来と比較して印刷層の厚みを薄くすることができるため、製缶工程でのネック加工及び／又は、フランジ加工時、缶胴端部にかかる成形力が減少して、缶胴端部のフィルムが剥離するのを防止することができる。
【０１５１】
また、第２印刷層を、リーフ状のアルミニウム蒸着剥離片が混入された樹脂組成物を、平方デシメートル当たり１〜３０ｍｇの範囲内の密度で塗布して形成した構成としたことにより、樹脂組成物の印刷インキとしての凝集力を充分に確保することができるので、印刷適性を適切に設定できるとともに、この第２印刷層による鏡面状の光沢感を得ることを維持しながら、その後の製缶工程による変形加工に第２印刷層を追従させることができ、このような変形加工による印刷面の外観性が低下することを防止することができる。さらに、アルミニウム蒸着剥離片がリーフ状に形成されたことにより、このようにアルミニウム蒸着剥離片が配合された樹脂組成物から形成された印刷層の膜厚を薄くしても、膜表面の平滑さを安定させて確保することができるので、印刷層の表面での乱反射が防止できるとともに、印刷層による隠蔽性をさらに向上させることができ、印刷層に鏡面状の光沢が付与された優れた美粧性を得ることができる。
【０１５２】
さらに、前記第１印刷層は、有色インキを網点状に印刷するとともに、その網点の合計面積が着色対象域の単位面積当たり２０〜４０％を占有する面積となるように設定されていることにより、この第１印刷層の下層となる第２印刷層に含まれたアルミニウム蒸着剥離片に反射した光が第１印刷層によって隠蔽されないので、第２印刷層の鏡面性による光輝効果を充分に発揮させることができ、アルミニウム蒸着剥離片が配合された樹脂組成物によって形成された第２印刷層による光輝感の効果を充分に発揮させながら、顔料の着色による第１印刷層の装飾効果が確保されて、両者の相乗効果によって缶体の外面に現わされた装飾における視覚上の印象が充分に確保された優れた美粧性を得ることができる。
そして、この発明によれば、印刷層の厚みを薄くすることができるため、製缶工程でのネック加工及び／又はフランジ加工時、缶胴端部にかかる成形力が減少して、缶胴端部のフィルムが剥離するのを防止することができる。
【図面の簡単な説明】
【図１】 この発明の実施形態であり、熱硬化型樹脂系接着剤層を備えた缶体の外面に貼着された樹脂フィルムの構成の主要部を示す拡大断面図である。
【図２】 この発明の他の実施形態であり、電子線硬化型樹脂系接着剤層を備えた缶体の外面に貼着された樹脂フィルムの構成の主要部を示す拡大断面図である。
【図３】 この発明の印刷層の構成を説明し、（ａ）は、鏡面シルバーインク層の上にデザイン層が網点印刷により形成された状態を拡大して示す模式図であり、（ｂ）は、同状態の印刷層の断面を示す模式図である。
【図４】 従来の印刷層の構成を説明し、（ａ）は、シルバーインク層の上にデザイン層が形成された状態を拡大して示す模式図であり、（ｂ）は、同状態の印刷層の断面を示す模式図である。
【図５】 この発明の実施形態であり、フィルムに印刷層を形成するグラビア印刷機の主要部の構成を示す模式図である。
【符号の説明】
１…缶体、 ２…ＰＥＴフイルム、 ３ａ…表示およびデザイン画像用の第１印刷層、 ３ｂ…鏡面シルバーインキにより形成された第２印刷層、 ４ａ…熱硬化型樹脂系接着剤層、 ４ｂ…電子線硬化型樹脂系接着剤層、 ５…硬化オーバーコート層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal can having a thermoplastic resin film on which decorative printing has been applied, in which a printed layer including a metal-deposited release piece is formed on the film, and the metal-deposited release piece is a metal Is evaporated in a vacuum to solidify a thin metal film on the surface of the film substrate, and then the metal film is peeled off from the film substrate to be subdivided.
[0002]
[Prior art]
Generally, metal cans (containers) made of aluminum or steel are roughly classified into three types: three-piece cans, two-piece cans, and bottle-type cans. This three-piece can is called a three-piece can because it consists of three parts: a bottom lid, a can body joined by welding or adhesion, and a canopy. In addition, the two-piece can has a structure in which a canopy is attached to a can body with an integrated can bottom, and is called a two-piece can because it consists of a can body and a canopy. It is also called a seamless can because there is no. Furthermore, the bottle-shaped can consists of a side seamless can body having a threaded portion at one open end of the can body, a cap and a bottom lid that are screwed into the threaded portion, and the overall shape is traditional. It is called a bottle-shaped can because it is similar to a glass bottle.
[0003]
On the outer surface of these metal cans, not only the display of the contents, but also a variety of decorations according to the contents accommodated in the interior, improving the identification of the accommodated goods, We are trying to contribute to the sale of products.
[0004]
In particular, if the content is a favorite beverage such as beer, coffee, or soft drink, the beverage itself has a strong character as an image product, so the appearance of the metal can is an important appeal point along with its naming. It has become.
[0005]
That is, it is desired that the image presented by the product is not impaired and that the product image is adapted and further the product image can be promoted. In addition to this, metal cans with a more beautiful appearance are required due to diversification of demands for products due to changes in consumption trends and needs.
[0006]
Therefore, in recent years, in order to meet such demands and secure a superiority in design, a special visual effect is added to this decoration to add new added value or It is made to stand out from surrounding competitors.
[0007]
In order to meet these requirements, a can made by sticking a preprinted thermoplastic resin film such as polyester to the outer surface of the metal can as an alternative to a can printed directly on the outer surface of the metal can. Various proposals have been made.
[0008]
In addition to offset printing, gravure printing or flexographic printing can be selected as a method for making this printing film. These printing methods are more decorative than conventional dry offset printing. High quality, good print quality, and printing on a continuous thermoplastic resin film instead of a can, so high-speed printing can be expected, and cannot be obtained with conventional dry offset printing directly on a can Has advantages.
[0009]
In addition, a printing film has been proposed in which a metallic pigment is used for the printing to obtain a decorative effect due to metallic luster.
[0010]
That is, for example, a first printing layer made of a resin composition containing a pigment is provided on one surface of a polyester film, and a second printing layer made of a resin composition in which metal powder is dispersed on the first printing layer. Further, a polyester film for covering a can body material provided with a thermosetting resin adhesive layer on the second printed layer, and a thermosetting resin adhesive on a metal plate for the can body material. Japanese Patent Application Laid-Open No. 7-41744 describes a metal can in which a protective coating layer is formed by heat bonding. According to this configuration, a special color tone having a metallic feeling can be imparted to the display and design image formed by the first print layer by the second print layer containing the metal powder. . In addition, when aluminum powder is used as the metal powder, the effect of imparting the above-described color tone can be obtained by adding aluminum powder in the range of 17 to 25% by weight to the resin composition. Yes.
[0011]
[Problems to be solved by the invention]
However, in metal cans that use the above-mentioned metal pigments for printing that decorates cans, it is difficult to obtain a glittering feeling due to a specular gloss even if the decorative surface can have a metallic feeling due to metallic luster. It was.
[0012]
In other words, the conventional metal pigment has a flake shape that is formed in a granular shape. Therefore, the larger the flake particle size, that is, the larger the reflection area and the higher the brightness, the more the inter-pigment between the pigments. In this case, gaps are likely to be generated, the size of the gaps is large, and the number of gaps is large. Therefore, in order to obtain a mirror-like full-surface reflection by a printing layer containing a metal pigment, it is necessary to fill this gap and ensure the whole surface reflection. Therefore, this is dealt with by increasing the thickness of the printing layer. It was. For this reason, at the time of neck processing (opening end side of the can body) or flange processing in the can manufacturing process, problems such as peeling of the film at the end of the can body due to the forming force occurred.
[0013]
On the other hand, it is possible to obtain a mirror-like high gloss by using a film in which a metal is deposited on the can film for laminating, but in this case, the side surface of the can body is uniform over the entire surface. Since it will become a glossy surface and a part having glossiness cannot be formed, there is a disadvantage that the decorative design of the metal can is restricted.
[0014]
In addition, using a vapor deposition film for a laminated can requires equipment for vapor deposition of metal on the film, which is different from the can manufacturing process, which increases the equipment cost and increases the manufacturing cost as a can. There was also inconvenience.
[0015]
The present invention has been made against the background of the above circumstances, and in the can body in which a protective coating layer is formed by coating the outer surface side of a metal plate for a can body material with a thermoplastic resin film, the outer surface of the can body For cosmetics using a thermoplastic resin film for covering can materials, which can give a special color tone with a metallic feeling, so-called specular gloss, to an image of a predetermined display and design shown in The object is to provide an excellent metal can.
[0016]
[Means for Solving the Problem and Action]
  In order to achieve the above object, the invention of claim 1 is characterized in that a thermoplastic resin film is bonded to the outer surface of a can through a resin adhesive, and the resin adhesive layer and the thermoplastic resin film are In the meantime, in the film-bonded metal can in which the printing layer made of the resin composition is formed, the printing layer prints the colored ink on the thermoplastic resin film in the form of halftone dots, and the total area of the halftone dots is Formed between the first printed layer formed so as to occupy 20 to 40% per unit area of the coloring target area, and formed between the first printed layer and the resin-based adhesive, and metal vapor deposition peeling It is composed of a resin composition mixed with a piece or one or more second printed layers made of a resin composition containing a pigment, and the metal vapor-deposited release piece of the second printed layer has a leaf shape and Particle size (longitudinal length and transverse direction Length) is 5 to 15 μm and 0.01 to 0.5 μm thick aluminum vapor-deposited exfoliated piece, and the aluminum vapor-deposited exfoliated piece is 1 to 5 wt% of the resin composition forming the second printed layer The resin composition in which the leaf-like aluminum vapor-deposited exfoliation pieces are mixed is applied at 1 to 30 mg / square decimeter while the total thickness of the second printed layer of the one or more layers is mixed. Is the formed film thicknessThe first printed layer is formed by halftone gravure printing using a printing plate made using a screen having a halftone dot number of 150 to 175 lines / inch,The can body to which the thermoplastic resin film on which the second printing layer, the first printing layer, and the resin adhesive layer are formed is bonded is subjected to an expanding process and / or a neck process. It is characterized by this.
[0017]
  Examples of the thermoplastic resin film for covering the can body material include a polyester film having excellent strength and transparency, and the polyester film bonded to the metal material via the resin adhesive is an ester repeat 75-100% of the units consist of ethylene terephthalate units, and ester units other than ethylene terephthalate units include ester units such as phthalic acid, isophthalic acid, succinic acid, and adipic acid.RankI can make it. Moreover, it is preferable that surface treatments, such as a corona discharge process, are normally performed for the surface of a polyester film in order to improve adhesiveness with an adhesive agent.
[0018]
Moreover, a polyethylene film, a polypropylene film, etc. can be used besides said polyester film. Further, it is a thermoplastic resin film made of a transparent polymer resin body selected from polypropylene resin, polycarbonate resin, polystyrene resin, vinyl chloride resin, polyvinylidene chloride copolymer, etc., or a composite of the above resins. The thickness of the thermoplastic resin film selected from these may be appropriately determined depending on the difference in material.
[0019]
Moreover, as a resin composition which forms said 1st and 2nd printed layer, it is preferable to use the resin composition which consists of urethane type resin, vinyl chloride type resin, or a vinyl chloride-vinyl acetate copolymer type resin. .
[0020]
That is, in the metal can, when the resin-based adhesive layer is formed of an electrocurable adhesive, the adhesive layer is bonded by irradiating an electron beam, so the contents are food. In such a case, after the metal can is filled with the contents, the above-mentioned printing is performed because the heat treatment such as retort sterilization is performed or the product is exposed to sunlight during transportation after completion. The layer may be discolored and faded, resulting in an unclear image such as a design formed by these printed layers. However, when the first and second printing layers are formed of a resin composition comprising a urethane resin, a vinyl chloride resin, or a vinyl chloride-vinyl acetate copolymer resin, Even if a metal can body manufactured from a metal plate for a can body material, on which a protective coating layer is formed by a polyester film for heat treatment, is subjected to heat treatment such as electron beam irradiation or retort sterilization treatment, or sunlight irradiation. The printing layer is preferable because no discoloration or discoloration occurs and a clear image can be maintained.
[0021]
  Moreover, as a metal vapor deposition peeling piece mixed in the resin composition which forms a 2nd printing layer,, ExcellentIn order to give a color tone having a mirror-like glossiness, the particle size (length in the vertical direction, length in the horizontal direction) is 5 to 15 μm, and the thickness (height) is 0.01 to 0.5 μm. Leaf-like aluminum vapor-deposited exfoliation piece having a glossy shapeIs used.
[0022]
According to invention of Claim 1, when a thermoplastic resin film is adhere | attached on the metal plate for can body materials by the said adhesive bond layer provided in the one surface, a thermoplastic resin is formed. With the first printed layer and the second printed layer provided on the film, it is possible to form a predetermined display and design image on the outer surface side of the metal plate without directly coating the metal plate. The first and second printed layers are made of a resin composition in which a metal-deposited strip is mixed between the first printed layer and the metal base of the metal plate for the can body material. The printing of the second printed layer is no longer controlled by the color tone of the metal base constituting the can body, and further, the image of a predetermined display and design displayed on the outer surface of the can body by the second printed layer has been conventionally used. More metallic feeling It is possible to impart special shades having mirror-like luster loose.
[0023]
That is, since the aluminum vapor-deposited strips mixed in the resin composition constituting the second printed layer are formed in a leaf shape, the smoothness of the surface of the second print layer in which the aluminum vapor-deposited strips are blended is It is ensured stably, the irregular reflection on the surface is prevented, and the individual aluminum vapor deposition exfoliation pieces are folded flat, so that a large shadow is generated between these stacked aluminum vapor deposition exfoliation pieces. The generation of the gap is eliminated, the entire surface can be reflected by the mirror-like surface with respect to the incident light, and a higher brightness feeling than before can be obtained.
[0024]
In addition, since the first and second printed layers are configured to be provided between the thermoplastic resin film and the adhesive layer, the first printed layer is particularly shielded from the outside by the thermoplastic resin film. It is possible to protect from external damage, and it is possible to stably secure an image of a predetermined display and design by the first printing layer and the second printing layer and a mirror-like glossiness by the second printing layer.
[0025]
In addition, since a mirror-like glitter can be obtained by a printed layer containing leaf-like aluminum vapor-deposited strips in the range of 1 to 5% by weight of the resin composition, conventional metal powder such as aluminum powder is at least Compared with the fact that the proportion exceeding 10% by weight of the resin composition is required, the amount of the aluminum vapor-deposited strip as a pigment can be reduced, so that the thickness of the printed layer can be reduced. Therefore, at the time of neck processing or flange processing in the can manufacturing process, the forming force applied to the end portion of the can body can be reduced, and the film on the end portion of the can body can be prevented from peeling off.
[0026]
In addition, since the glitter is obtained by the printed layer formed by printing or the like in this way, it is possible to flexibly cope with the design requirements, thereby restricting the degree of freedom in decoration design. Therefore, it is possible to develop various products as metal cans for storing products.
[0027]
Furthermore, the first2 Printed layer filmThickness isIt is a film thickness formed by applying the resin composition mixed with the leaf-like aluminum vapor-deposited exfoliation piece at 1 to 30 mg / square decimeter.The
[0028]
In addition, although said 2nd printing layer can be set as the structure formed by making the aluminum vapor deposition peeling piece into ink with a resin composition, and printing using this ink, in this case, the storage of ink is used. In order to improve the stability, it is desirable to add an anti-settling agent such as polyethylene wax as necessary to increase the thixotropic property (thixotropic property) of the ink.
[0029]
In addition, when the first or second printing layer is printed, the pigment, which is an aluminum vaporized release piece, mixed in the ink tends to settle, so that sufficient agitation is performed before use for printing and printing is performed. The ink is circulated between the ink pan that supplies the ink to the printing surface during the execution of the ink and the storage tank that replenishes the used ink to the ink pan to prevent the sedimentation of the pigment, and is adjusted to a predetermined viscosity by a diaphragm method or the like. It is desirable.
[0030]
  In particular, since the ink viscosity is an important factor for the finished surface of the printed surface, the setting of the ink viscosity to be used is adjusted to 16 ± 1 seconds with a Zancup # 3 with an orifice diameter of 3 mm, and the UK By using an automatic viscosity controller such as Viscocoms 500 manufactured by Prestec Co., Ltd., the ink viscosity is always kept within the above range even during printing.ProperIt is desirable to ensure the viscosity. That is, for example, when the first printing layer is printed, if the ink viscosity setting is less than 15 seconds and the viscosity is low, the printed surface should be smooth on the solid portion that should be smooth, such as uneven shading or small spots. The phenomenon of “swimming” in which a pattern (Mottling) is generated tends to occur. On the other hand, when the ink viscosity is set higher than 17 seconds and the viscosity is high, the ink is completely covered with the ink. Since the printed part of the surface is not sufficiently leveled with the ink transferred from the halftone dots of the plate, the phenomenon of `` screening '' in which screen eyes appear is likely to occur, and when any of these phenomena occurs This is because the appearance of the printed surface is deteriorated.
[0031]
This departureAccording to MingThe second2 The resin composition that forms the printing layer is coated with the printing ink containing the leaf-like aluminum vapor-deposited strips at a density in the range of 1 to 30 mg per square decimeter, so that the cohesive strength of the ink is sufficient. As a result, the printability of the ink can be set appropriately, while maintaining the effect of adding an excellent mirror-like gloss to the image of the specified display and design, while maintaining the printing surface. It can prevent that the external appearance property falls.
[0032]
That is, when the thickness of the printing ink by the aluminum vapor-deposited strips blended in the resin composition is less than 1 mg / square decimeter, the density of the vapor-deposited strips is too low, and the mirror-like glossiness by the printed layer is sufficient. It will not be obtained. In addition, if the thickness of the printing ink exceeds 30 mg / square decimeter, sufficient cohesive force as ink cannot be obtained, so depending on the deformation process in the can manufacturing process after forming the printing layer, the appearance of the printing surface The nature will decline.
[0033]
This is, for example, when the film sticking can is a laminated can, and can processing after lamination, especially processing that mainly compresses a part of the can body such as neck processing and In the case of processing that mainly involves stretching a part of the can body, such as expanding processing, the ink cannot follow the deformation due to processing in any of these processing, so the appearance of the printing surface This is because the performance is lowered. However, by applying printing ink obtained by mixing the leaf-like aluminum vapor-deposited exfoliation piece into the resin composition into an ink at a density within a range of 1 to 30 mg per square decimeter, the above-mentioned problems can be avoided in advance. And the appearance of the printed surface can be maintained.
[0034]
In addition, the aluminum vaporized exfoliated strips are leaf-like and thin, so that the smoothness of the film surface is ensured even if the thickness of the printed layer formed from the resin composition containing the aluminum vaporized exfoliated strips is reduced. Therefore, the irregular reflection on the surface of the printing layer can be prevented, the concealing property by the printing layer can be further improved, and an excellent cosmetic property in which a mirror-like gloss is imparted to the printing layer can be obtained. it can.
[0035]
In other words, the aluminum vapor deposition exfoliation piece overlaps even in the thin film forming the printing layer, and no gap is formed between the aluminum vapor deposition exfoliation pieces. Even in the thin film, the entire surface of the printing layer can be reflected. Specularity can be obtained.
[0036]
The first printing layer in the present invention is set so that the colored ink is printed in a halftone dot shape, and the total area of the halftone dots is an area that occupies 20 to 40% per unit area of the coloring target area. ing.
[0037]
Therefore this departureAccording to Ming,On the upper surface on the thermoplastic resin film side of the first printed layer or the second printed layer, in which the sheet-like aluminum vapor-deposited exfoliation piece is blended, the occupied area is 20 to 40% per unit area of the colored region by the pigment. As a result of the printing layer being formed in this way, the reflected light is not concealed on the aluminum vapor deposition exfoliation piece contained in the lower printing layer than this printing layerThe secondThe glitter effect by the specularity of 2 printing layers can fully be exhibited.
[0038]
  As a result, the effect of glitter by the printed layer formed by the resin composition in which the aluminum vapor-deposited release piece is blended can be sufficiently exerted, and this glitter can be added to the decoration by coloring the pigment. It is possible to ensure a sufficient visual impression on the decoration that appears on the outer surface of the body, and to obtain excellent cosmetics.The
Further, the present invention provides an expansion process and / or a neck process on the can body to which the thermoplastic resin film on which at least the second print layer, the first print layer, and the resin adhesive layer are formed is bonded. It is a film sticking metal can characterized by being applied.
Therefore, according to the present invention, since the thickness of the printing layer can be reduced, the forming force applied to the end of the can body at the time of neck processing or flange processing in the can manufacturing process is reduced, and the film of the end of the can body is reduced. Can be prevented from peeling off.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Specific examples of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged cross-sectional view showing a state in which a polyester film, which is a thermoplastic resin film on which a printed layer for decorating the outer surface of the can body of this specific example is formed, is stuck to the can body.
[0040]
That is, the can 1 used in the present invention is made of metal, and the metal plate as the material thereof is an aluminum plate, tin-free steel, stainless steel, tinplate, chrome-plated steel plate, aluminum-plated steel plate, nickel-plated steel plate. Surface-treated steel plates and metal plates such as turn-plated steel plates and other various alloy-plated steel plates are coated with thermosetting or electron beam curable paints, or with resin-coated metal plates coated with thermoplastic resin Can be used.
[0041]
Further, the can body 1 includes a bottomed can body in which a can bottom and a can body such as a drawn can (including a can subjected to a drawing process and a stretch process), a drawn iron can, and an impact can are integrally formed, That is, it can be set as a two-piece can. Further, a three-piece can or a bottle-type can generally referred to may be used.
[0042]
Furthermore, the polyester film 2 (hereinafter abbreviated as “PET film”) is a polyester film that is bonded to the outer surface side of the metal plate as the material, and has excellent strength and transparency.
[0043]
In this PET film 2, 75 to 100% of ester repeating units are composed of ethylene terephthalate units. Examples of ester units other than ethylene terephthalate units include ester units such as phthalic acid, isophthalic acid, succinic acid, and adipic acid. be able to. In addition, the PET film 2 is preferable because a film having a high melting point of about 260 ° C. can be obtained by appropriately selecting an alcohol component and an acid component, so that sufficient heat resistance can be secured.
[0044]
Furthermore, in this specific example, in addition to the PET film 2, a polyethylene film, a polypropylene film, or the like can also be used. Furthermore, a resin having thermoreversibility comprising a transparent polymer resin body selected from polypropylene resin, polycarbonate resin, polystyrene resin, vinyl chloride resin, polyvinylidene chloride copolymer, etc., or a composite of the above resins. A film may be used, and the thickness of the thermoreversible resin film is appropriately determined according to the difference in the selected material.
[0045]
Moreover, it is preferable that the surface of the PET film 2 on the side where the adhesive layers 4a and 4b are formed is preliminarily subjected to surface oxidation treatment by corona discharge or the like. The adhesive force can be improved, and the bonding strength between the PET film 2 and the adhesive layer 4 can be increased.
[0046]
And as shown in FIG. 1, the 1st printing layer 3a by which the character and the design were made to appear by dot-printing the coloring pigment contained in the resin component on one surface of the PET film 2, and the mirror surface silver A second printed layer 3b formed of a resin composition containing a pigment (leaf-like aluminum vapor-deposited strip) and an adhesive layer 4a formed of a thermosetting resin-based or electron beam-curable resin-based adhesive 4b, and a transparent cured overcoat layer 5 formed of a thermosetting resin system or an electron beam curable resin is provided on the opposite surface of the PET film 2.
[0047]
The first printing layer 3a is formed of a printing ink having a configuration in which a pigment is blended with a urethane resin, a vinyl chloride resin, or a vinyl chloride-vinyl acetate copolymer resin. As will be described later, the first printing layer 3a is printed in multiple colors by printing halftone dot printing inks containing pigments of each color, and has a predetermined display on the outer surface of the can. A design consisting of a design image is formed.
[0048]
The second printed layer 3b has a structure in which 1 to 5% by weight of a specular silver pigment is dispersed in a urethane resin, a vinyl chloride resin, or a vinyl chloride-vinyl acetate copolymer resin as described later. It is made of mirror surface silver ink.
[0049]
The adhesive layer 4 is formed using a thermosetting resin-based or electron beam curable resin-based adhesive.
[0050]
That is, the thermosetting resin adhesive is a resin in which an epoxy resin having a number average molecular weight of 5000 to 20000 and an acid anhydride curing agent are blended in a weight ratio of 70/30 to 99/1, or a polyester resin. And aminoplast resin are used in a weight ratio of 70/30 to 90/10. Therefore, in this case, by thermally bonding the PET film 2 to the metal plate forming the can body 1 through the thermosetting resin-based adhesive layer 4a by heating at a high temperature for a short time, The PET film 2 is adhered to a metal plate, and excellent adhesive strength can be obtained between the metal plate.
[0051]
In addition, the electron beam curable resin adhesive is a stress relaxation agent in a resin composition in which 2 to 30 parts by weight of a polyester oligomer having an unsaturated double bond is added to 100 parts by weight of a polyester resin. Is added to 0.5 to 250 PHR (parts by weight relative to 100 parts by weight of the resin). Therefore, in this case, the PET film 2 is pressed against a metal plate and irradiated with an electron beam in this state, thereby allowing the PET film 2 to pass through the electron beam curable resin adhesive layer 4b. By adhering to the metal plate forming the can 1, the PET film 2 can be adhered to the metal plate.
[0052]
And manufacture of the film sticking can using the tin two-piece can body (350 mDl can whose inner diameter of the can body is 65.8 mm) formed by drawing and ironing is performed as described below, for example.
[0053]
This PET film 2 has a halftone dot on one surface of a polyethylene terephthalate resin film 2 having a thickness of 16 μm, and the same length range as the circumference of the outer periphery of the can body with ink made of urethane resin. 1 μm-thick printed layer 3 a that has been colored and printed, second printed layer 3 b on which a mirror-like silver pigment is dispersed, and polyester resin, isocyanate resin, and amine What formed the 6-micrometer-thick thermosetting adhesive layer 4 which consists of a system resin (compounding ratio 94: 3: 3) is used.
[0054]
In addition, the overcoat layer is formed by applying an overcoat paint, and a transparent paint made of an ultraviolet curable resin is used, and an epoxy acrylate-based prepolymer is used in order to obtain a smooth coating surface. Ford Cup # 4 by uniformly mixing 70% by weight of resin, 30% by weight of triacrylate as a photopolymerizable monomer, 5-7% by weight of benzophenone as a photopolymerization initiator, and 1-2% by weight of silicon as a lubricant. The viscosity is adjusted to 60 to 90 seconds (200 to 350 cp) at 25 ° C.
[0055]
Furthermore, an overcoat coating material is hardened | cured by irradiating the ultraviolet rays with a wavelength of 200-450 nm for 0.5 second by the irradiation process of a radiation. Further, since the overcoat layer 5 after curing is solvent-free, there is very little loss of paint due to the curing of the paint, and a paint film surface that substantially maintains the wet paint film surface is formed.
[0056]
And the PET film 2 of the said structure is affixed on the outer periphery of the two-piece can body in which the neck-in process and the flange process are not given. That is, the PET film 2 is pressed against the can body surface of the can body 1 heated by the heating device and heated, and is attached to the can body 1 with the adhesive layer 4a.
[0057]
Note that a well-known epoxy-phenolic paint may be spray-coated on the inner surface and the bottom surface of the two-piece can body 1, and then the coating is dried at 220 ° C. at 60 ° C. in order to dry the coating and heat and cure the adhesive layer 4. Only heated for seconds. Thereafter, the opening end of the can body 1 is subjected to a three-stage neck-in process (neck inner diameter of 57.4 mm) and a flange process for winding the lid on the can body by a known method.
[0058]
Moreover, the manufacture of the laminated film sticking can using the three-piece can body is performed as described below, for example.
[0059]
That is, as shown in FIG. 2 as a schematic cross-sectional view, an electron beam curable adhesive is applied to a PET film having a thickness of 5 to 30 μm in which the printing layer 3a and the printing layer 3b are formed in the same manner as the above two-piece can body. Is coated using a normal coater, such as roll coater, gravure, gravure offset, spray coating, etc., so that the film thickness after drying is 1-5 μm, and is tack-free as necessary. Until dry, at a temperature of 50 ° C. to 150 ° C. for only a few seconds. Next, a metal plate is bonded to the adhesive layer, and laminating is performed by heating to a temperature not higher than the temperature at which the PET film 2 is softened (about 230 ° C. or lower) for 2 seconds or shorter.
[0060]
The laminated metal plate is irradiated with an electron beam through the PET film 2. As an accelerator for an electron beam generation source used for the electron beam irradiation, a cockcroft type, a cockcroft Walton type, a van de Graaf type, a resonance A transformer type, a transformer type, an insulated core transformer type, a dynamitron type, a linear filament type, an area beam type, a high frequency type and the like are used as appropriate. The electron beam energy required to cure and dry the electron beam curable adhesive according to this specific example is suitably in the range of 100 KeV to 300 KeV, preferably 150 KeV to 200 KeV. The irradiation dose is preferably 0.2 Mrad to 15 Mrad, and particularly preferably 1 Mrad to 5 Mrad. When the irradiation dose is less than 0.2 Mrad, the adhesive is not completely cured and the adhesive strength performance by a sufficient adhesive layer cannot be obtained. Further, when the irradiation dose exceeds 15 Mrad, there is a possibility that the mechanical strength of the PET film 2 is lowered. The irradiation time of the electron beam is about 1 second or less, which is about 1/50 of the time required for heat curing the thermosetting adhesive.
[0061]
Welding cans are made using this metal plate, then necking is applied to the first, second, third, and fourth stages, and flanges are formed to wind the lid on the cans. The lid is wound around the can body by tightening.
[0062]
In the two-piece can body and the three-piece can body, after the can body 1 is filled with a drink such as coffee liquid by a conventional method, the can body 1 is sealed with a lid and heated at 125 ° C. for about 30 minutes. Sterilization is performed.
[0063]
Therefore, according to the metal can 1 to which the PET film 2 previously decorated by printing is pasted in this way, since the metal can 1 is not directly printed or coated, an oven or the like can be used in the can making process. Since the process of drying the paint using the heat treatment becomes unnecessary, it is possible to save energy in the can manufacturing process and to reduce the discharge of carbon dioxide by the oven.
[0064]
Moreover, since the 1st printing layer 3a and the 2nd printing layer 3b have urethane-type resin or vinyl chloride resin or vinyl chloride-vinyl acetate copolymer resin as main vehicle components, as mentioned above, the can 1 It can be suitably used when the content is a food such as a drink.
[0065]
That is, when the contents of the can body 1 are foods such as drinks, after the can body 1 is filled with the contents, a heat sterilization process (for example, a retort sterilization process) is performed. When an electron beam curable adhesive is used for 1, the electron beam is irradiated to cure and fix the adhesive, or it is exposed to sunlight when transported as a product, Since the printed layer is discolored or faded, there is a disadvantage that the decoration such as the design formed by the printed layer becomes unclear.
[0066]
On the other hand, this example uses an urethane resin, a vinyl chloride resin, or a vinyl chloride-vinyl acetate copolymer resin as the main vehicle component of the first printing layer 3a and the second printing layer 3b, so that an electron beam Even if it receives the retort process by irradiation and heating and irradiation of sunlight, the discoloration and fading of the 1st printing layer 3a and the 2nd printing layer 3b can be prevented, and by these 1st printing layer 3a and the 2nd printing layer 3b A clear image is maintained and good decorative properties can be secured.
[0067]
The cured overcoat layer 5 is formed using a thermosetting or electron beam curable resin. That is, examples of the thermosetting resin that forms the cured overcoat layer 5 include an epoxy resin and an aminoplast resin, to which a phosphoric acid catalyst is added. Examples of the electron beam curable resins include epoxy acrylate resins, polyester acrylate resins, polyurethane acrylate resins, polyether acrylate resins, polybutadiene acrylate resins, and the like. What is necessary is just to show a polymerization reaction with radiation. The electron beam curable resin can be used alone or as a mixture of two or more.
[0068]
Therefore, by providing the cured overcoat layer 5 on the outermost surface of the can body 1, the PET film 2 is not exposed to the outer surface, and the deterioration of the slipperiness of the outer surface of the can body 1 due to the PET film 2 can be prevented. The transportability of the can 1 in the subsequent can manufacturing process and can manufacturing process is ensured, and the efficiency of can manufacturing and can manufacturing can be maintained.
[0069]
The cured overcoat layer 5 is made of silicon in order to improve the scratch resistance of the PET film 2 and the slipperiness of the surface of the can body 1 in the can body 1 in which the protective coating layer is formed of the PET film 2. Or it is preferable that the wax is added.
[0070]
Further, an electron beam curable overcoat layer 5 is formed on the can body surface of the can body 1 to which the PET film 2 is adhered, and a cured overcoat layer 5 is formed, and an electron beam curable adhesive is bonded to the adhesive layer 4b. When an agent is used, it is possible to accelerate the curing of the adhesive at the same time as curing the overcoat paint by electron beam irradiation, so the solidifying step of the adhesive is omitted and the electron beam irradiation step is performed. The adhesive can be solidified together, the number of steps required for manufacturing can be reduced, and the cost can be reduced.
[0071]
Furthermore, when the overcoat layer 5 is an electron beam curable resin, it is not necessary to heat the overcoat layer 5 to cure it, so that deformation due to thermal contraction of the thermoplastic resin film is prevented, and a good can The appearance of the body 1 can be ensured.
[0072]
And in this example, the 2nd printing layer 3b in which the mirror surface silver pigment which consists of aluminum vapor deposition peeling pieces was disperse | distributed is formed in the lower layer of the 1st printing layer 3a in which the pattern of the predetermined display and design was formed. Thus, the decoration appearing on the outer surface of the can body 1 can be given a cosmetic property having a specular gloss.
[0073]
That is, a predetermined display is obtained by dot printing by overlaying any single color or several colors of colored ink on the mirror-like second printing layer 3b formed of mirror-like silver ink containing aluminum vaporized peeling pieces. In addition, with the configuration in which the first printing layer 3a on which the design pattern is formed is installed, printing having a specular glitter of any color is obtained.
[0074]
As such an aluminum pigment of a metal paint, an aluminum paste mixed with aluminum flakes is known. Moreover, as a manufacturing method of this aluminum flake, for example, an aluminum vapor deposition film is formed on a base material made of a plastic film, and the aluminum vapor deposition film is peeled off from this film base material, and this aluminum vapor deposition film is removed from stearic acid or other A method is known in which a fatty acid is added as a crushing aid (lubricant) and crushed together to form a flake to a predetermined particle size.
[0075]
Further, this metal pigment has a flake structure in which a specific shape factor, which is a ratio of an average diameter to its thickness, is a value in the range of 10 to 500. And, it is highly dependent on such particle shape that high gloss such as metallic silver or metallic gold is obtained by the reflection characteristics of the surface of the metallic material constituting the metallic pigment.
[0076]
In this specific example, as the metal vapor deposition exfoliation piece dispersed in the resin composition forming the second printed layer 3b, a vapor deposition exfoliation piece formed of aluminum, titanium, tantalum, hafnium, niobium, stainless steel or the like in a leaf shape is used. In order to give a color tone with a mirror-like glossiness excellent in the decorative effect by the first and second printing layers 3b, the particle size (length in the vertical direction, length in the horizontal direction) can be given. It is preferable that the thickness (height) is 5 to 15 μm and the thickness (height) is 0.01 to 0.5 μm.
[0077]
Further, the blending amount of the mirror surface silver pigment with respect to the resin as the paint is preferably adjusted to a range of 1 to 5 parts by weight with respect to 100 parts by weight of the vehicle component (solid content) so that sufficient glitter can be obtained. ing.
[0078]
That is, when the amount of the mirror surface silver pigment is less than 1% by weight, the amount of the pigment dispersed is small, so that the intensity of reflection by the pigment with respect to the incident light is lowered and the glossiness is not sufficiently developed. . On the other hand, when the compounding amount of the mirror surface silver pigment exceeds 5% by weight, the effect of imparting glitter is saturated, and the effect of further enhancement cannot be obtained.
[0079]
In addition, the individual aluminum flakes of the mirror surface silver pigment are formed in a leaf shape, and as shown in Table 1 below, they are formed to be smaller and thinner than the conventional aluminum pigment aluminum flakes. That is, the particle size occupies a range from 5 μm to 15 μm, the average particle size is 10 μm, and the thickness occupies a range from 0.3 μm to 0.5 μm.
[0080]
[Table 1]

As shown in Table 1, the individual aluminum flakes of the conventional silver pigment, for example, in the case of a low-luminance type silver pigment, the particle diameter occupies a range from 10 μm to 20 μm, and the average particle size The diameter is 15 μm, and the thickness is formed to occupy a range from 5 μm to 6 μm. In the case of a high-luminance type silver pigment, the particle size occupies a range from 20 μm to 30 μm, the average particle size is 20 μm, and the thickness occupies a range from 5 μm to 6 μm. ing. Further, in the case of a super high brightness type silver pigment, the particle size occupies a range of 10 μm to 80 μm, the average particle size is 30 μm, and the thickness occupies a range of 5 μm to 8 μm. ing.
[0081]
The brightness of the ink containing each silver pigment shown in the table is measured using a gloss meter, and Nippon Denshoku VGS-300A is used as a model of the gloss meter. . This measuring instrument can measure the hue and color difference of various samples, and can measure not only the surface color of fabrics, coatings, paper, etc., but also the reflection measurement of powder samples and the transmission measurement of films and liquid samples. It is a product. In addition, the measured brightness is measured along the rolling direction of the PET film 2 on which these inks are printed, and the direction perpendicular to the rolling direction of the PET film 2 (denoted as C direction in the table). Since the measurement was slightly different from the case of the measurement, the measurement results are shown separately in the rolling direction column and the C direction column.
[0082]
Furthermore, by forming the first printing layer 3a showing the design by a design image or the like by using halftone printing, the second printing layer 3b made of mirror surface silver ink formed under the design layer gives high brightness. We are trying to fully demonstrate it.
[0083]
As the halftone dot printing, for example, gravure printing is used, and as a method for making a printing plate used for gravure printing, an original pattern is baked on a photosensitive film, and then a photosensitive agent is applied to the film pattern. An etching method in which a non-photosensitive portion is eroded by electrolysis and electro-decomposed, a method in which a non-photosensitive portion is exposed by a laser spot without passing through a film, and the non-photosensitive portion is also eroded by a diamond bit. In this example, it is assumed that the above-mentioned laser corrosion manufacturing method is used.
[0084]
In general, the gradation change of an image reproduced by gravure printing is either the size of each halftone dot, the number of halftone dots printed per unit area, the print density of each halftone dot, or the print density of each halftone dot. It is expressed by a combination of
[0085]
  The number of halftone dots per unit area is indicated by the number of halftone lines (also called the number of screen lines, but hereinafter simply called the number of lines) representing the degree of fineness in which the halftone dots are arranged on the printing surface. It is shown how many halftone dots are arranged in a line (line shape) in an inch (25.4 mm) as a reference unit. Further, the number of lines generally used is 150 to 250 lines / inch, of which 175 lines / inch is the most.Also usedThe number of lines
[0086]
In addition, the standard of the amount of ink of the printing plate to be gravure printed using the mirror surface silver ink of this example, for example, from the number of lines and the depth of the concave portion formed in the printing plate forming the halftone dot, the following Is set as follows. That is, when the plate depth is 150 μm and the plate depth is 30 μm, the ink amount standard is 1.5, and when the plate depth is 170 μm and the plate depth is 20 μm, the ink amount standard is 1.0 and 175 lines. When the plate depth is 15 μm, the ink amount is set to 0.75.
[0087]
And when the opaque layer was formed in the upper layer of the mirror surface silver ink layer of the 2nd printing layer 3b, as shown to FIG. 4 (a), (b), it reflected on the silver pigment of the 2nd printing layer 3b. Since the light is concealed by the upper opaque layer, it is not totally reflected, so that the mirror surface by the mirror silver ink layer of the second printing layer 3b cannot be sufficiently obtained.
[0088]
Therefore, when performing mirror surface printing of an arbitrary color, as shown in FIGS. 3A and 3B, the colored ink is printed in a halftone dot shape, and the mirror surface silver ink layer of the second printed layer 3b is printed. By forming the first printed layer 3a as the upper layer, the first printed layer 3a can be configured so that the reflected light from the mirror surface silver ink layer of the second printed layer 3b can pass therethrough, while ensuring color development with colored ink. The reflection effect by the specularity of the mirror surface silver ink layer can be sufficiently exhibited. As a result, it is possible to add a high brightness feeling due to the mirror surface silver ink layer to the decoration effect such as the design image with the colored ink.
[0089]
  In addition, the 1st printing layer 3a is set so that the total area of the individual halftone dots may become an area which occupies 20 to 40% per unit area of the coloring object area | region. The area percentage of the halftone dots is expressed as the area percentage occupied by the printed halftone dots per unit area. In this example, 20 to 40% is selected, and the design effect by the design image and the mirror surface silver Synergistic effects with the decorative effects of pigmentsPossessionThe decoration effect is obtained.
[0090]
That is, when the area ratio% of the halftone dots is less than 20%, there is a problem that the design property by the first printing layer 3a itself is not sufficiently exhibited because there are few colored pigments. On the other hand, when the area ratio% of the halftone dots exceeds 40%, the reflected light from the second print layer 3b is blocked by the first print layer 3a itself, which has the effect of giving a higher glitter feeling than before. It will not be obtained. Therefore, by setting the area ratio% of the halftone dots in the range of 20 to 40%, the decorative effect of both can be sufficiently exhibited, so that a synergistic decorative effect that cannot be obtained alone can be obtained. Is possible.
[0091]
Moreover, in this specific example, although the example which formed the shape of the said halftone dot in the circle was demonstrated, you may form in addition to this, such as a rhombus and a chain dot, and the request | requirement of the design etc. which are given to the can 1 The halftone dot shape may be appropriately selected according to the above.
[0092]
Furthermore, the gloss of the mirror-like surface can be sufficiently obtained by the configuration in which the aluminum vapor-deposited strip formed in a leaf shape is blended with the second printed layer 3b.
[0093]
That is, conventionally, since the surface of the ink surface by printing is not smooth with respect to the two surfaces of the PET film, the smoothness of the underlying silver ink layer is lost. In addition, since the conventional aluminum ink aluminum flakes are not formed in a leaf shape but in a granular form, the printed surface made of these granular flakes does not become smooth. Compared to the above, a sufficiently smooth surface could not be obtained, irregular reflection occurred on the surface, and glossiness due to a mirror-like surface could not appear.
[0094]
However, the aluminum flakes of the mirror surface silver ink of this specific example are made into the aluminum vapor deposition exfoliation pieces formed in a leaf shape, so that the thickness of the flakes is thin, so the surface of the second printed layer 3b in which the flakes are blended Can be ensured stably, irregular reflection on the surface can be prevented, and sufficient gloss can be obtained by a mirror-like surface.
[0095]
Further, by spreading the leaf-like aluminum vapor-deposited exfoliation pieces without any gaps, for example, the second printed layer 3b is formed by continuing the second printed layer 3b containing aluminum flakes not only in one layer but also in two or more layers. The concealing property by the surface is improved, and the specular reflectivity of the surface is obtained.
[0096]
That is, in the conventional silver pigment, since the shape of the flakes constituting the pigment is formed in a granular shape, the larger the particle size, that is, the higher the luminance, the more gaps between the pigments. Therefore, in order to obtain a mirror-like full-surface reflection, it is necessary to fill this gap, so that the silver ink layer has been increased in thickness. For this reason, the amount of ink used increases and the printing process becomes complicated, resulting in inconveniences that increase the manufacturing cost.
[0097]
On the other hand, according to the specular silver pigment of this specific example, the flakes of the pigment are formed in a thin leaf shape, so that the flakes overlap even in a thin film, and no gap is generated between the flakes. Specularity can be obtained even with a thin film. That is, since sufficient mirror surface property can be ensured on the surface of the printing layer, it becomes possible to reflect the entire incident light on the printing surface and to obtain a sufficient glitter.
[0098]
In addition, the specular silver pigment of this example has a lower kinematic viscosity compared to the conventional silver pigment, so the specular silver pigment tends to cause a swimming phenomenon even in ink of the same viscosity as the conventional one. It is preferable to print as thin a film as possible.
[0099]
In other words, the aluminum flakes dispersed in the ink with high fluidity are thin and formed in a leaf shape, and as the solvent component of the ink evaporates, the surface to be printed On the other hand, since the individual aluminum flakes are folded in a flat shape, it is possible to eliminate a large gap in which a shadow is generated between the stacked aluminum flakes. As a result, a high-brightness metallic feeling can be revealed.
[0100]
Even when the ink containing the conventional silver pigment and the ink containing the specular silver pigment of this example were adjusted to have the same printing viscosity by Zahn cup # 3, both of these were B-type. When the respective viscosities were measured with a rotary viscometer, as shown in Table 2 below, comparatively clear inks with a mirror surface silver pigment had lower viscosity and lower viscosity.
[0101]
[Table 2]

In addition, each ink uses each DSK reducer S-5 as a ketone-based diluting solution so that the time until the specified amount flows out from Zahn cup # 3 having an orifice diameter of 3 mm is 16.5 seconds. Adjustment was made by diluting the ink, and immediately after dilution, measurement was performed with a B-type rotational viscometer. The measurement temperature when each ink was measured was set to 23 degrees.
[0102]
The B-type rotational viscometer is configured to measure the viscous resistance torque of the liquid acting on the cylinder or the disk when the cylinder or the disk is rotated in the liquid of the material to be measured. ing.
[0103]
Furthermore, thixotropy shown in the table is also called thixotropy, which means thixotropic phenomenon that increases fluidity when agitated and loses fluidity when allowed to stand for a certain time thereafter. The ink is a viscous material having thixotropy, and the TI value in the table indicates the degree to which such a phenomenon occurs in each ink. Further, an ink having strong thixotropy is excellent in printing dimensions and color reproducibility specified by the printing plate, and ink embedding property, but it is said that the leveling property is not good. This thixotropy is often used as a term corresponding to dilatancy, which generally means a phenomenon in which the viscosity increases due to an increase in shear rate.
[0104]
In addition, in order to improve the storage stability of the ink, it is necessary to improve the thixotropy of the ink by adding an anti-settling agent such as polyethylene wax to the mirror surface silver ink as necessary. Yes.
[0105]
In addition, if the viscosity of the mirror surface silver ink obtained by converting the mirror surface silver pigment into ink is less than 15 seconds as measured by the Zahn cup # 3, a phenomenon of “swimming” tends to occur in the printed result, while 17 seconds. If it exceeds the upper limit, the phenomenon of “screening” is likely to occur, and if either one of the phenomena occurs, there is a disadvantage that a printed surface with a good appearance cannot be obtained.
[0106]
As described above, the viscosity setting of the silver ink is an important factor for the finished state on the printing surface, so that the measurement result by the Zancup # 3 is within the range of 16 ± 1 second. The viscosity of the mirror silver ink is adjusted using a diluent or the like.
[0107]
In addition, since the mirror surface silver pigment in the mirror surface silver ink tends to settle, the printing is started after sufficiently stirring before use, and the ink pan, the storage tank, and the ink are circulated when the printing is performed. Therefore, it is essential to always adjust to the above predetermined viscosity by a diaphragm method or the like.
[0108]
Therefore, for example, in this example, the above-mentioned viscosity is continuously and accurately even during printing using a Viscomex 500 manufactured by Prestec of the UK as an ink viscosity controller of a production line including the printing apparatus. To automatically adjust.
[0109]
The above-mentioned swimming phenomenon is a phenomenon in which fine shading unevenness and small spotted patterns (mottling) are generated on the solid portion of the printing surface that should be smooth. Will be defective. In addition, the screening phenomenon is a phenomenon in which the screen part appears because the printed part that is completely covered with ink and has a smooth solid surface does not level the ink transferred from the halftone dots of the plate sufficiently. It is known that the appearance of the ink is deteriorated, and it is likely to be generated by ink after printing when overprinting is performed. Leveling means that the surface of the ink moved from the plate to the surface to be printed becomes flat.
[0110]
The following four causes can be cited as causes of the former swimming phenomenon.
[0111]
That is, 1) In the case where flow or convection is likely to occur in the ink layer between the time when the ink is transferred to the surface to be printed and the time when the ink is dried. Low, b) slow printing speed, c) deep plate depth, d) poor tension balance, etc.
[0112]
In addition, 2) In the case where the fluidity of the ink is poor and the pigment or resin is likely to aggregate during the period from the transfer of the ink to the drying, this may be caused by, for example, a) strong thixotropy B) using ink, b) gelled, thickened ink, soared ink, use of ink with unbalanced solvent, mix of different types of ink, or use diluting solvent by mistake Time is considered.
[0113]
Further, there are 3) the case where the raw material to be printed, that is, the PET film 2 is uneven, and the case where partial looseness occurs, and 4) the case where a failure due to static electricity occurs.
[0114]
Measures against the causes of the above 1) and 2) include adjusting the ink viscosity as high as possible and increasing the printing speed.
[0115]
In addition, as a countermeasure against 1) and 2), there is a revision. That is, it is possible to replace the printing plate with a shallow plate depth and a narrow bank width, increase the number of meshes of the screen, or change the screen angle.
[0116]
As a countermeasure of the above 2), in order to confirm the state in which the ink is used and confirm the ink, or to eliminate the soaring state of the ink, poor fluidity and thickening, gelation, For example, various auxiliary agents may be added to readjust the viscosity of the ink, or to directly contact the ink manufacturer of the ink being used.
[0117]
As a countermeasure of the above 3), it is possible to check and replace the original fabric.
[0118]
As countermeasures for 4) above, in order to eliminate troubles caused by static electricity, a) When the original fabric is easily charged with static electricity, change the original fabric to an anti-static type, etc. b) Insufficient negative electricity in the printing press Occasionally, negative electrical appliances are cleaned, grounding is confirmed, and static elimination methods are studied. C) When the ink is easily charged, an antistatic agent is added. D) When the humidity in the printing chamber is low, the printing chamber It is possible to increase the humidity by flooding or using a humidifier.
[0119]
For all electrostatic disturbances, a) Change the original fabric to an antistatic type, b) Check the cleaning of the static eliminator and grounding, and examine the static elimination method. C) Use an antistatic agent. D) Adjust the humidity in the printing chamber appropriately with water or a humidifier, etc. e) Increase the ink viscosity when the whiskers occur at the boundary of printing due to static electricity, f) Around the printed line area When a misting phenomenon occurs in which the ink adheres in a mist state, the ink is often low in viscosity. Therefore, a solvent or a compound is appropriately added. G) For other printing troubles, an antistatic agent may be added. It is done.
[0120]
In addition, the following six causes can be cited as the main causes of the above-mentioned screening phenomenon.
[0121]
That is, 1) When the viscosity of the ink is high and the ink does not level, 2) When the ink dries before the leveling because the ink dries quickly, and 3) When the printing surface printed earlier and after printing If the level does not level, 4) If the printing pressure, which is the pressure that the squeegee applies to the printed material through the plate during printing, is insufficient. 5) If the bank does not level, the ink is not leveled. The cylinder surface is worn, the plate depth is shallow, and the bank width is wide. Further, it is known that when the screen angle is set to other than 45 degrees, an oblique line tends to enter the printing surface. 6) There is a case where the ink is not sufficiently raised to the position of the doctor due to a small amount of ink.
[0122]
As measures against the causes 1) to 3) above, the ink viscosity is reduced or a slow-drying solvent is used in combination to reduce the ink drying speed, and the doctor position is set as much as possible to the impression cylinder. It is possible to use a setting close to.
[0123]
Further, as a measure against the above 4), a matting agent is added to the previously printed ink to increase the surface area of the printing target and improve wettability.
[0124]
As a countermeasure for the above 4), there is an increase in printing pressure.
[0125]
As a countermeasure of the above 5), there is a revision such as narrowing the bank width.
[0126]
As a countermeasure of the above 6), it is possible to install an ink pan at a raised position or add an ink amount.
[0127]
  That is, the gravure printing apparatus 51 using the mirror surface silver ink of this example, as shown in FIG. 5, for example, rotatably supports a plate roll 52 formed in a cylindrical shape with a predetermined diameter, and the entire outer peripheral surface thereof is supported. A large number of minute recesses 52a for printing the halftone cells are formed on the periphery. The plate roll 52 is soaked in the ink A filled in the ink pan 53 at the lower outer surface, and the plate roll 52 is driven to rotate so that all the minute recesses of the plate roll 52 are obtained.In part 52aInk A can be stored respectively.
[0128]
Excess ink A adhering to the outer peripheral surface of the plate roll 52 is scraped off by an ink doctor blade (hereinafter referred to as a doctor) 54.
[0129]
A pressure drum 55 is rotatably contacted with the outer peripheral surface of the plate roll 52 by the rotation of the plate roll 52, and the PET film 2 is passed between the pressure drum 55 and the plate roll 52. It is configured.
[0130]
  In this gravure printing apparatus, a part of the plate roll 52 is inserted.Within Kipan 53By rotating in a state immersed inIn part 52aInk A is stored in the ink, and after the excess ink A is scraped off by the doctor 54,In part 52aInk A remaining on the printing baseTo PET film 2 which is materialI try to transfer (print).
[0131]
As the material of the doctor 54, a normal MDC (Swedish steel) type is used, and the pressure setting for bringing the doctor 54 into contact with the plate roll 52 is that the aggregation of the pigment due to the shear is recognized when the normal use pressure is set. The setting is weaker than usual.
[0132]
That is, the doctor 54 is configured to be pressed in a direction approaching the plate roll 52 by an air cylinder (not shown), and with respect to a surface length of 1200 mm, which is the entire length of the plate roll 52. By adjusting the air cylinder pressure, the pressure at which the doctor 54 contacts the plate roll 52 (hereinafter referred to as doctor pressure) is adjusted and managed. The range of this cylinder pressure is controlled to 0.6 kg to 1.2 kg, but printing is also possible in the range of 0.3 kg to 1.8 kg.
[0133]
Therefore, although the said doctor pressure is normally managed in the range of 0.0025-0.015kg / cm by the linear pressure, when using the mirror surface silver ink of this example, it is 0.0025-0.01kg / The printing is performed within the range of cm.
[0134]
In addition, if the doctor pressure is maintained beyond the value in the above-mentioned proper range, the wear of the contact portion of the doctor and scratches on the surface of the plate cylinder provided on the plate roll 52 increase, Since replacement is necessary and the operating cost increases, it is not economically preferable. In addition, depending on the pigment of the ink, an aggregate of ink is formed on the back side of the doctor, resulting in a defective print result such as generation of doctor streaks on the printing surface. Furthermore, it is known that when the doctor pressure is lower than the above-mentioned value in the proper range, the doctor is cut off, causing ink fogging and other poor printing quality.
[0135]
The thickness of the mirror surface silver ink of this example by the printing apparatus is desirably set in the range of 1 to 30 mg / square decimeter, and more preferably 3 to 15 mg / square decimeter.
[0136]
That is, if the density is less than 1 mg / square decimeter, the density of the specular silver pigment is low, so that the specular gloss cannot be sufficiently obtained.
[0137]
In addition, when it exceeds 30 mg / square decimeter, cohesion as an ink cannot be sufficiently obtained. Therefore, when the can body on which the printing layer is formed is deformed by subsequent can manufacturing processing. Cannot secure a high brightness feeling due to the printed layer.
[0138]
That is, for example, in the case of a laminated can, the can manufacturing process after laminating, especially when the process is mainly for compressing a part of the can body such as a neck process, and the can body such as an expanding process Since the ink cannot follow the deformation caused by the processing, the mirror surface state of the surface of the second printed layer 3b is not maintained, and any part of the processing that mainly involves stretching a part of the ink cannot be maintained. The high brightness feeling is impaired, and the appearance of the printed surface is deteriorated.
[0139]
In particular, when the contents of the can are food, and the sterilization process such as retorting is performed for sterilization after the contents are filled in the can, the entire can is exposed to a high temperature of 100 ° C to 140 ° C. Therefore, in the printing part deformed by the processing in the can manufacturing process, the destruction of the ink aggregation due to the relaxation of the ink is noticeably observed, and the mirror surface state of the surface is impaired as described above. As a result, the feeling of high brightness is further impaired.
[0140]
Regarding the ink solid, the blending ratio of components that greatly affect the specific gravity is set so that the ratio of resin: mirror silver pigment is 12:20. In this case, the resin is urethane-vinyl chloride S.P. g. 1.1 mirror surface silver pigment is aluminum paste S.I. g. 2.7 shall be used.
[0141]
Therefore, the specific gravity of the mirror surface silver ink that satisfies this condition is 2.1. Incidentally, 3 mg / square decimeter is O.D. When the specific gravity of the mirror silver ink is 2.1 as described above, the film thickness is 0.14 μm.
[0142]
As described above, according to the metal can on which the film of this specific example is adhered, the PET film is adhered to the metal plate for the can body material by the adhesive layer provided on one surface thereof, and the protective coating layer When the film is formed, the first printed layer and the second printed layer provided on the PET film do not directly coat the metal plate, and a predetermined display and design image are formed on the outer surface side of the metal plate. And a structure in which a second printed layer made of a resin composition in which a metal vapor-deposited strip is mixed between the first printed layer and the metal base of the metal plate for can body material is formed. As a result, the printing of the first and second printing layers is not controlled by the color tone of the metal base constituting the can body, and the predetermined display displayed on the outer surface of the can body by the second printing layer. And traditional to design images Metallic effect above, it is possible to impart a special color with gloss of the so-called mirror surface.
[0143]
That is, since the aluminum vapor-deposited strips mixed in the resin composition constituting the second printed layer are formed in a leaf shape, the smoothness of the surface of the second print layer in which the aluminum vapor-deposited strips are blended is It is ensured stably, the irregular reflection on the surface is prevented, and the individual aluminum vapor deposition exfoliation pieces are folded flat, so that a large shadow is generated between these stacked aluminum vapor deposition exfoliation pieces. The generation of the gap is eliminated, the entire surface can be reflected by the mirror-like surface with respect to the incident light, and a higher brightness feeling than before can be obtained. As a result, compared to conventional metal cans using silver pigments, it is possible to obtain a glittering feeling with high specularity, and to ensure superiority in cosmetics and design. It is possible to provide a metal can with excellent design that can reflect the stored product image.
[0144]
In addition, the second printing layer has a configuration in which a printing ink in which a leaf-like aluminum vapor-deposited release piece is inked with a resin composition is installed and formed at a density in the range of 1 to 30 mg per square decimeter. Since the ink cohesion can be sufficiently secured, the printing ability of the ink can be set appropriately, and the subsequent printing process can be performed while maintaining the mirror-like glossiness by the second printing layer. The ink constituting the second printing layer can be made to follow the deformation processing by the above-described, and the appearance of the printed surface due to such deformation processing can be prevented from being deteriorated.
[0145]
Furthermore, the aluminum vapor deposition exfoliation piece is formed in a leaf shape, which is smaller and thinner than the conventional one, so even if the thickness of the printed layer formed from the resin composition containing the aluminum vapor deposition exfoliation piece is reduced, the film surface Since the smoothness can be secured stably, the irregular reflection on the surface of the printing layer can be prevented, and the concealing property by the printing layer can be further improved, and the printing layer is provided with a specular gloss. High cosmetics can be obtained.
[0146]
In other words, the aluminum vapor deposition exfoliation piece overlaps even in the thin film forming the printing layer, and no gap is formed between the aluminum vapor deposition exfoliation pieces. Even in the thin film, the entire surface of the printing layer can be reflected. Specularity can be obtained.
[0147]
In addition, on the upper surface on the polyester film side of the first printed layer or the second printed layer in which the leaf-shaped aluminum vapor-deposited exfoliation piece is blended, an occupied area of 20 to 40% per unit area of the pigmented colored region is obtained. Since the printed layer is formed, the light reflected on the aluminum vapor-deposited strip included in the second printed layer, which is the lower layer of the first printed layer, is not concealed by the first printed layer. The glitter effect due to the specularity of the layer can be sufficiently exhibited.
[0148]
As a result, the decorative effect of the first printed layer by coloring the pigment can be ensured while fully exhibiting the effect of glitter by the second printed layer formed by the resin composition containing the aluminum vaporized release piece. Since the glitter of the second printing layer can be added to the decoration of the pigment of the first printing layer, the visual impression of the decoration appearing on the outer surface of the can body is sufficiently secured by the synergistic effect of both. And excellent cosmetic properties can be obtained.
[0149]
  Here, the correspondence between the configuration of the specific example and the configuration of the present invention will be described. The can body 1 corresponds to the metal can of the present invention, the PET film 2 corresponds to the thermoplastic resin film of the present invention, and printing. Layer 3a is the present inventionA mark printed with halftone dots of colored inkThe printing layer 3b corresponds to the printing layer, the printing layer 3b corresponds to the printing layer made of the resin composition mixed with the metal-deposited strip of the invention, the adhesive layer 4 corresponds to the adhesive layer of the invention, and the mirror surface silver pigment. Corresponds to the metal-deposited exfoliation piece of the present invention.
[0150]
【The invention's effect】
  As described above, according to the first aspect of the invention, the aluminum vapor-deposited exfoliation piece mixed in the resin composition constituting the second printed layer.Is a particle size (length in the vertical direction and length in the horizontal direction) of 5 to 10 μm and a thickness of 0.01 to 0.5 μm.By being formed in a sheet shape, the smoothness of the surface of the second printed layer in which the aluminum vapor-deposited exfoliation piece is blended is ensured stably, irregular reflection on the surface is prevented, and individual aluminum vapor-deposition is achieved. Since the peeling pieces are folded flat, it is eliminated that a large gap that generates a shadow between the stacked aluminum vapor deposition peeling pieces is generated, and the entire surface is reflected by a mirror-like surface with respect to incident light. It is possible to give a special color tone having a metallic feeling, that is, a so-called specular glossiness, to an image of a predetermined display and design that is displayed on the outer surface of the can body by the second printed layer. it can. In addition, since the thickness of the printed layer can be reduced compared to the conventional case, the neck in the can manufacturing process can be increased.Work and / orDuring the lung processing, the forming force applied to the end portion of the can body can be reduced, and the film on the end portion of the can body can be prevented from peeling off.
[0151]
Also,By forming the second printed layer by applying a resin composition mixed with leaf-like aluminum vapor-deposited strips at a density in the range of 1 to 30 mg per square decimeter, Since sufficient cohesion as printing ink can be ensured, printing suitability can be set appropriately, and while maintaining the mirror-like glossiness by this second printing layer, the subsequent can-making process The second printing layer can follow the deformation process, and the appearance of the printed surface due to such deformation process can be prevented from being deteriorated. Further, since the aluminum vapor-deposited strip is formed in a leaf shape, the film surface is smooth even if the printed layer formed from the resin composition containing the aluminum vapor-deposited strip is thinned. As a result, it is possible to prevent irregular reflection on the surface of the printed layer, to further improve the concealment property by the printed layer, and to provide an excellent cosmetic with a specular gloss on the printed layer. Sex can be obtained.
[0152]
Furthermore, the first printing layer is set so that the colored ink is printed in a halftone dot shape, and the total area of the halftone dots is an area that occupies 20 to 40% per unit area of the coloring target area.As a result, the light reflected on the aluminum vapor-deposited strip contained in the second printed layer, which is the lower layer of the first printed layer, is not concealed by the first printed layer, so that the glitter effect due to the specularity of the second printed layer is sufficient. The decorative effect of the first printed layer by the coloring of the pigment is achieved while the effect of the glitter by the second printed layer formed by the resin composition containing the aluminum vapor-deposited strip is sufficiently exhibited. It is possible to obtain excellent cosmetics with a sufficient visual impression on the decoration that is secured on the outer surface of the can body by the synergistic effect of both.The
According to the present invention, since the thickness of the printing layer can be reduced, the forming force applied to the end of the can body at the time of neck processing and / or flange processing in the can manufacturing process is reduced, and the end of the can body It can prevent that the film of a part peels.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view showing the main part of the structure of a resin film that is an embodiment of the present invention and is adhered to the outer surface of a can body provided with a thermosetting resin-based adhesive layer.
FIG. 2 is an enlarged cross-sectional view showing the main part of the configuration of a resin film attached to the outer surface of a can body provided with an electron beam curable resin adhesive layer according to another embodiment of the present invention.
FIG. 3 illustrates the configuration of a printing layer according to the present invention. FIG. 3A is a schematic diagram illustrating an enlarged state in which a design layer is formed by dot printing on a mirror surface silver ink layer; ) Is a schematic view showing a cross section of the printed layer in the same state.
4A and 4B are diagrams illustrating a configuration of a conventional print layer, in which FIG. 4A is a schematic diagram illustrating an enlarged state in which a design layer is formed on a silver ink layer, and FIG. It is a schematic diagram which shows the cross section of a printing layer.
FIG. 5 is a schematic diagram illustrating a configuration of a main part of a gravure printing machine according to an embodiment of the present invention, which forms a printing layer on a film.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Can body, 2 ... PET film, 3a ... 1st printing layer for a display and a design image, 3b ... 2nd printing layer formed with the mirror surface silver ink, 4a ... Thermosetting resin adhesive layer, 4b ... Electron beam curable resin adhesive layer, 5 ... cured overcoat layer.

Claims (1)

A film paste in which a thermoplastic resin film is bonded to the outer surface of a can through a resin adhesive, and a printed layer made of a resin composition is formed between the resin adhesive layer and the thermoplastic resin film. In metal cans,
The printing layer is formed on the thermoplastic resin film so that the colored ink is printed in a halftone dot shape, and the total area of the halftone dots is an area that occupies 20 to 40% per unit area of the coloring target area. A first printed layer;
From a resin composition formed between the first printed layer and the resin-based adhesive and mixed with a metal vapor-deposited release piece, or one or more second printed layers made of a resin composition containing a pigment Configured,
The metal-deposited exfoliation piece of the second printed layer has a leaf shape and has a particle size (length in the vertical direction and length in the horizontal direction) of 5 to 15 μm and a thickness of 0.01 to 0.5 μm. It is an aluminum vapor deposition exfoliation piece, The aluminum vapor deposition exfoliation piece is mix | blended in the resin composition which forms a 2nd printing layer in 1-5 weight%, and the film | membrane of the whole 2nd printing layer of the said 1 layer or more thickness, wherein the resin composition leaf-shaped aluminum deposited release strip is mixed 1 to 30 mg / square decimeter at a film thickness formed by coating, or one the first printed layer, the halftone Formed by dot gravure printing using a printing plate made using a screen of several 150 to 175 lines / inch,
The can body to which the thermoplastic resin film on which the second printing layer, the first printing layer, and the resin adhesive layer are formed is bonded is subjected to an expanding process and / or a neck process. A film-attached metal can characterized by that.

Images