JP3813524B2 - Welded part coating film, welded part coating method, and resin-coated can - Google Patents

Description

【００３６】
なお、実施例１は、熱可塑性ポリエステル層１３として、ＰＥＴ（融点２５５℃）とＰＥＴ／イソフタレート共重合体（融点２０７℃）とからなる二層構造のポリエステルフィルム（デュポンシュア製メリネックス８５０、膜厚２０μｍ、配向係数０．１６６）を適用した。また、熱硬化性樹脂層１２として、エポキシ系樹脂 (東洋インキ製エポキシ−フェノール樹脂）を適用した。さらに、変性ポリオレフィン層１１として、無水マレイン酸変性ポリエチレン (三井化学製アドマーＸＥ０７０、融点８５℃）を適用した。
【００３７】
実施例２は、熱可塑性ポリエステル層１３として、ＰＥＴ単層フィルム（ユニチカ製ｓ−２５、膜厚２５μｍ、配向係数０．１６８、融点２５５℃）を用いた以外は、実施例１と同様の条件で評価を行った。
実施例３は、熱可塑性ポリエステル層１３として、ＰＥＴ（融点２５５℃）とＰＥＴ／イソテレフタレート共重合体（融点２０７℃）からなる二層構造のポリエステルフィルム（ガルワレ社製ＰＴＯ５５、膜厚３０μｍ、配向係数０．１６５）を用いた以外は、実施例１と同様の条件で評価を行った。
【００３８】
実施例４は、変性ポリオレフィン層１１として、実施例１と同様の材料を用い、膜厚を３０μｍとした以外は、実施例１と同様の条件で評価を行った。
実施例５は、変性ポリオレフィン層１１として、実施例１と同様の材料を用い、膜厚を１５０μｍとした以外は、実施例１と同様の条件で評価を行った。
実施例６は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ＰＥＴ（デュポン社製メリネックス８５０）を使用し、変性ポリオレフィン層１１として、無水マレイン酸変性ポリエチレン（三井化学製アドマーＳＦ７３１、融点７０℃）を使用した以外は、実施例１と同様の条件で評価を行った。
【００３９】
実施例７は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ＰＥＴ（デュポン社製メリネックス８５０）を使用し、変性ポリオレフィン層１１として、エポキシ変性ポリエチレン（ＰＥにグリシジルメタクレレートを３重量％、パーオキサイド（日本油脂製パークミルＤ）を０．３％添加し、２軸押出機中、１８０℃で変性したもの、融点９０℃）を用いた以外は、実施例１と同様の条件で評価を行った。
【００４０】
実施例８は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ポリプロピレン（三菱樹脂製、ホモポリプロピレンと無水マレイン酸変性ランダム共重合ポリプロピレンの二層構造、膜厚５０μｍ）を用い、変性ポリオレフィン層１１として、無水マレイン酸変性ポリプロピレン（三井化学製アドマーＱＦ５７０、融点８０℃）を用いた以外は、実施例１と同様の条件で評価を行った。
【００４１】
また、比較例１は、溶接部被覆フィルムとして、ポリエステル層のみからなるフィルム（ガルワレ社製ＰＴＯ５５、ＰＥＴとＰＥＴ／イソフタレート共重合体からなる二層構造、膜厚３０μｍ、配向係数０．１６５）を用いた以外は、実施例１と同様の条件で評価を行った。
比較例２は、比較例１で用いたフィルムを用い、膜厚を４５μｍとした以外は、実施例１と同様の条件で評価を行った。
【００４２】
比較例３は、溶接部被覆フィルムとして、ポリエチレンと、変性ポリエチレンとの二層構造のフィルム（三井化学製アドマーＸＥ０７０、膜厚１５０μｍ）を用いた以外は、実施例１と同様の条件で評価を行った。
比較例４は、比較例２で用いたフィルムを用い、膜厚を１５０μｍとした以外は、実施例１と同様の条件で評価を行った。
【００４３】
比較例５は、溶接部被覆フィルムとして、ポリエステル系粉体塗料（デクスターミドランド社製ＶＰ）を用いた以外は、実施例１と同様の条件で評価を行った。
表１及び図３に示すように、熱可塑性ポリエステル層１３と、熱硬化性樹脂層１２と、変性ポリオレフィン層１１とからなる溶接部被覆フィルム１０で溶接部Ｗを被覆した樹脂被覆缶１００においては、ピンホール及び溶接部Ｗにおける空隙がいずれも発生していないことが確認できた。さらに、樹脂被覆缶１００における耐蝕性も確保できていることが確認できた。
（第二実施形態）
図４は、本発明の溶接部被覆フィルムの他の構成例を示す断面図である。
【００４４】
本実施形態における樹脂被覆缶１００Ａは、第一実施形態における樹脂被覆缶１００において、その溶接部Ｗを被覆する溶接部被覆フィルム１０Ａを変えて構成している。
本実施形態における溶接部被覆フィルム１０Ａは、図４に示すように、第一の変性ポリオレフィン層１４と、ポリオレフィン層１５と、第二の変性ポリオレフィン層１６と、熱硬化性樹脂層１２と、熱可塑性ポリエステル層１３とを順次積層した五層構造を有しており、第一の変性ポリオレフィン層１４側と鋼板１の溶接部Ｗ側とが接するように接着している。
【００４５】
第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６は、第一実施形態で用いた変性ポリオレフィン層１１と同一の材料から構成することができ、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６を同一材料から構成しても、それぞれ異なる材料から構成しても構わない。
この第一の変性ポリオレフィン１４及び第二の変性ポリオレフィン層１６の厚みは、特に限定されることはないが、好ましくは、１〜３０μｍ、さらに好ましくは、３〜２０μｍとするのがよい。ここで、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６の厚みを１μｍ以下にすると熱硬化性樹脂層１２との接着性や溶接部Ｗとの接着性が低下してしまい、一方、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６の厚みを３０μｍ以上とするとコストが増大してしまうため、上述の範囲とするのが好ましい。なお、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６の厚みは、上述の範囲内であれば、同一であっても、それぞれ異なるように形成しても構わない。
【００４６】
ポリオレフィン層１５は、低密度ポリエチレン、高密度ポリエチレン、直鎖低密度ポリエチレン、ポリプロピレン、ポリプロピレン単独重合体、ポリプロピレンと少量のα−オレフィンからなるブロック又はランダム共重合体、エチレン−プロピレンラバーなどのポリオレフィン系熱可塑性エラストマー、これらのポリオレフィン系樹脂を混合したものなどが挙げられる。特に、低密度ポリエチレン、高密度ポリエチレン、直鎖低密度ポリエチレン、ポリプロピレン単独重合体、ポリプロピレンと少量のα−オレフィンからなるブロック又はランダム共重合体が望ましい。
【００４７】
このポリオレフィン層１５の厚みは、特に限定されないが、好ましくは５〜１８０μｍ、さらに好ましくは１０〜１５０μｍとするのがよい。ここで、ポリオレフィン層の厚みを５μｍ以下とするとピンホールが発生しやすくなり、一方、ポリオレフィン層１５の厚みを１５０μｍ以上とするとコストが増大してしまうため、上述の範囲とするのが望ましい。
【００４８】
熱硬化性樹脂層１２、熱可塑性ポリエステル層１３は、第一実施形態で説明したものと同じものとすることができる。
ここで、上述の五層を積層して溶接部被覆フィルム１０Ａを形成する方法は、いずれの方法を用いてもよいが、例えば、以下に示す方法などが挙げられる。
まず、所望の厚みの熱可塑性ポリエステル層１３と、第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６の三層フィルムとを、Ｔダイエクストルージョン法などによって製膜する。
【００４９】
続いて、熱可塑性ポリエステル層１３の一面に、未硬化の熱硬化性樹脂層１２を塗布したのち、この熱硬化性樹脂層１２側に第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６の三層フィルムを積層し、ドライラミネートによって五層を接着させる。このドライラミネートを行う際の温度は、１００〜２００℃とすることが好ましい。ここで、ドライラミネートの温度を１００℃以下で行うと、熱硬化性樹脂層１２の硬化反応が進行しにくく、熱可塑性ポリエステル層１３と熱硬化性樹脂層１２との接着強度が低下する。一方、ドライラミネートの温度を２００℃以上で行うと、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６が著しく溶融してしまうため、溶接部被覆フィルム１０Ａの製膜が困難になってしまう。
【００５０】
ここで、第一の変性ポリオレフィン層１４と、ポリオレフィン層１５と、第二の変性ポリオレフィン層１６との総厚みは、特に限定されないが、好ましくは３０〜２００μｍ、さらに好ましくは４０〜１８０μｍとするのがよい。ここで、この総厚みを３０μｍ以下とするとピンホールが発生しやすくなり、一方、この総厚みを２００μｍ以上とするとコストが増大してしまうため、上述の範囲とすることが望ましい。
【００５１】
次に、本実施形態における樹脂被覆缶１００Ａの製造方法と、この樹脂被覆缶１００Ａへの溶接部Ｗに溶接被覆フィルム１０Ａをする被覆する方法について説明する。なお、第一実施形態と重複する部分は省略する。
本実施形態における樹脂被覆缶１００Ａは、その缶胴部内面における溶接部Ｗを、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６並びにポリオレフィン層１５の融点よりも高く、熱可塑性ポリエステル層１３の融点よりも低い温度、例えば、１２０〜２４０℃で加熱した状態で、その溶接部Ｗに、第一の変性ポリオレフィン層１４側が鋼板１と接するように、溶接部被覆フィルム１０Ａを熱圧着させている。
【００５２】
このとき、加熱温度よりも低い温度の融点を有する第一の変性ポリオレフィン層１４、ポリオレフィン層１５及び第二の変性ポリオレフィン層１６は溶融し、溶接部Ｗの段差Ｓや突起部Ｐの隙間をカバーするように鋼板１と接着する。また、加熱温度よりも高い温度の融点を有する熱可塑性ポリエステル層１３は、溶融せず、溶接部Ｗの段差Ｓや突起部Ｐへの破損やピンホールの発生を抑制する機能を有する。さらに、第二の変性ポリオレフィン層１６は、ポリオレフィン層１５と熱硬化性樹脂層１２との接着性を向上させる機能をも有する。
【００５３】
このように、本実施形態における樹脂被覆缶１００Ａは、その溶接部Ｗに上述した溶接部被覆フィルム１０Ａで被覆されていることによって、鋼板１の溶接部Ｗと溶接部被覆フィルム１０Ａとの間に間隙が存在せず、且つ、ピンホールが発生しないため、耐蝕性を大幅に向上させることが可能となる。
また、本実施形態における溶接部被覆フィルム１０Ａによれば、バリアー性に優れたポリオレフィン層１５を含むことによって、外部からの水分などの浸入を効果的に抑制することができるため、樹脂被覆缶１００Ａにおける耐蝕性をさらに向上させることが可能となる。
【００５４】
なお、本実施形態における溶接部被覆フィルム１０Ａの形成方法として、熱可塑性ポリエステル層１３の一面に未硬化の熱硬化性樹脂層１２を塗布し、この熱硬化性樹脂層１２側に第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６からなる三層フィルムを積層し、ドライラミネートして接着させたが、熱可塑性ポリエステル層１３と第二の変性ポリオレフィン層１６との間に熱硬化性樹脂層１２を介層するのであればこれに限らない。
例えば、第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６からなる三層フィルムにおける第二の変性ポリオレフィン層１６側に、未硬化の熱硬化性樹脂層１２を塗布しておき、この熱硬化性樹脂層１２側に熱可塑性ポリエステル層１３を積層し、ドライラミネートするようにしても構わない。
【００５５】
【第二実施例】
次に、本実施形態の樹脂被覆缶におけるピンホールの発生の有無及び溶接部段差における空隙の有無、並びに耐蝕性を評価した結果について説明する。表２は、実施例９〜１６において使用した溶接部被覆フィルム１０の形成材料と、ピンホールの発生の有無及び溶接部段差における空隙の有無を評価した結果について示す。ここで、比較例及び評価方法、並びに試験条件は、第一実施例と同様の条件で行った。
【００５６】
【表２】

【００５７】
なお、実施例９は、熱可塑性ポリエステル層１３として、ＰＥＴ（融点２５５℃）とＰＥＴ／イソフタレート共重合体（融点２０７℃）とからなる二層構造のポリエステルフィルム（デュポン社製メリネックス８５０、膜厚２０μｍ、配向係数０．１６６）を使用した。また、熱硬化性樹脂１２として、エポキシ系樹脂（東洋インキ製エポキシ−フェノール樹脂）を使用した。さらに、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６として、無水マレイン酸変性ポリエチレン（三井化学製アドマー、融点８５℃）を使用した。さらにポリオレフィン層１５として、ポリエチレン（日石化学製レクスロンＶ３５１、融点１２５℃）を使用した。ここで、第一の変性ポリオレフィン層１４である無水マレイン酸変性ポリエチレンと、ポリオレフィン層１５であるポリエチレンと、第二の変性ポリオレフィン層１６である無水マレイン酸変性ポリエチレンとは、Ｔダイエクストルージョン法によって共押出し、無水マレイン酸変性ポリエチレン（５μｍ）／ポリエチレン（４０μｍ）／無水マレイン酸変性ポリエチレン（５μｍ）の三層フィルムを製膜した。そして、この三層フィルムと、熱可塑性ポリエステル層１３とを第一実施例と同様にドライラミネートし、５層構造の溶接部被覆フィルム１０Ａを作製している。
【００５８】
実施例１０は、熱可塑性ポリエステル層１３として、ＰＥＴ単層フィルム（ユニチカ製ｓ−２５、膜厚２５μｍ、配向係数０．１６８、融点２５５℃）を用いた以外は、実施例９と同様の条件で評価を行った。
実施例１１は、熱可塑性ポリエステル層１３として、ＰＥＴ (融点２５５℃）とＰＥＴ／イソテレフタレート共重合体（融点２０７℃）からなる二層構造のポリエステルフィルム（ガルワレ社製ＰＴＯ５５、膜厚３０μｍ、配向係数０．１６５）を用いた以外は、実施例９と同様の条件で評価を行った。
【００５９】
実施例１２は、第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６の膜厚を、それぞれ５μｍ／２０μｍ／５μｍとした以外は、実施例９と同様の条件で評価を行った。
実施例１３は、第一の変性ポリオレフィン層１４／ポリオレフィン層１５／第二の変性ポリオレフィン層１６の膜厚を、それぞれ１０μｍ／１３０μｍ／１０μｍとした以外は、実施例９と同様の条件で評価を行った。
【００６０】
実施例１４は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ＰＥＴ（デュポン社製メリネックス８５０）を使用し、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６として、無水マレイン酸変性ポリエチレン（三井化学製アドマーＳＦ７３１、融点７０℃）を使用した以外は、実施例９と同様の条件で評価を行った。
【００６１】
実施例１５は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ＰＥＴ（デュポン社製メリネックス８５０）を使用し、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６として、エポキシ変性ポリエチレン（ＰＥにグリシジルメタクレレートを３重量％、パーオキサイド（日本油脂製パークミルＤ）を０．３％添加し、２軸押出機中、１８０℃で変性したもの、融点９０℃）を用いた以外は、実施例９と同様の条件で評価を行った。
【００６２】
実施例１６は、鋼板１にラミネートする熱可塑性樹脂フィルム２として、ポリプロピレン（三菱樹脂製、ホモポリプロピレンと無水マレイン酸変性ランダム共重合ポリプロピレンの二層構造、膜厚５０μｍ）を用い、第一の変性ポリオレフィン層１４及び第二の変性ポリオレフィン層１６として、無水マレイン酸変性ポリプロピレン（三井化学性アドマーＱＦ５７０、融点８０℃）を用いた以外は、実施例９と同様の条件で評価を行った。
【００６３】
表２に示すように、熱可塑性ポリエステル層１３と、熱硬化性樹脂層１２と、第一の変性ポリオレフィン層１４と、ポリオレフィン層１５と、第二の変性ポリオレフィン層１６とからなる５層構造の溶接部被覆フィルム１０で溶接部Ｗを被覆した樹脂被覆缶１００Ａにおいては、ピンホール及び溶接部Ｗにおける空隙がいずれも発生していないことが確認できた。さらに、樹脂被覆缶１００Ａにおける耐蝕性も確保できていることが確認できた。
【００６４】
なお、第一及び第二の実施形態における樹脂被覆缶１００、１００Ａとして、円筒形状のものについて説明したが、これに限らず、四角形状、多角形状などいずれの形状の樹脂被覆缶１００に適用することが可能である。
また、第一及び第二の実施形態においては、本発明の溶接部被覆フィルム１０、１０Ａを樹脂被覆缶１００、１００Ａの溶接部Ｗに被覆する例について説明したが、金属板の溶接部を被覆するものであれば、その他の用途に適用することも可能である。
【００６５】
【発明の効果】
以上説明したように、請求項１に記載の溶接部被覆フィルムによれば、軟性を有する変性ポリオレフィンによって溶接部の段差に密着して接着するとともに、硬性を有する熱可塑性ポリエステル層によって、溶接部の段差や突起部でのピンホールの発生を抑制することが可能となる。すなわち、溶接部を確実に被覆することができ、溶接部の耐蝕性を向上させることが可能となる。
【００６６】
また、変性ポリオレフィン層と熱可塑性ポリエステル層との接着性を向上させることが可能となる。このため、本発明における溶接部被覆フィルムを金属板に接着したのち、この金属板の加工成形を容易且つ確実に行うことが可能となる。
請求項２に記載の溶接部被覆方法によれば、金属板に、容易且つ確実に溶接部被覆フィルムを被覆させることが可能となる。
【００６７】
請求項３に記載の樹脂被覆缶によれば、耐蝕性を大幅に向上させることが可能となる。 請求項４に記載の溶接部被覆フィルムによれば、軟性を有する変性ポリオレフィンによって溶接部の段差に密着して接着するとともに、硬性を有する熱可塑性ポリエステル層によって、溶接部の段差や突起部でのピンホールの発生を抑制することが可能となる。すなわち、溶接部を確実に被覆することができ、溶接部の耐蝕性を向上させることが可能となる。
【００６８】
また、溶接部被覆フィルムにおいて、内容物のバリアー性に優れたポリオレフィン層を含むことによって、耐蝕性をさらに向上させることが可能となる。
さらに、第二の変性ポリオレフィン層と熱可塑性ポリエステル層との接着性を向上させることが可能となる。このため、本発明における溶接部被覆フィルムを金属板に接着したのち、この金属板の加工成形を容易且つ確実に行うことが可能となる。
【００６９】
請求項５の記載の溶接部被覆方法によれば、金属板に、容易且つ確実に溶接部被覆フィルムを被覆させることが可能となる。
請求項６に記載の樹脂被覆缶によれば、耐蝕性を大幅に向上させることが可能となる。
【図面の簡単な説明】
【図１】本発明における溶接部被覆フィルムの一構成例を示す断面図である。
【図２】本発明における溶接部被覆フィルムの他の構成例を示す断面図である。
【図３】本発明における溶接部被覆フィルムの厚みと、ピンホール発生率との関係を示す図である。
【図４】本発明における溶接部被覆フィルムの他の構成例を示す断面図である。
【符号の説明】
１ 鋼板（金属板）
２ 熱可塑性樹脂フィルム（樹脂）
１０、１０Ａ 溶接部被覆フィルム
１１ 変性ポリオレフィン層
１２ 熱硬化性樹脂層
１３ 熱可塑性ポリエステル層
１４ 第一の変性ポリオレフィン層
１５ ポリオレフィン層
１６ 第二の変性ポリオレフィン層
１００、１００Ａ 樹脂被覆缶
Ｐ 突起部
Ｓ 段差
Ｗ 溶接部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a welded part covering film and a welded part covering method for covering a welded part of a metal plate, and a resin-coated can.
[0002]
[Prior art]
In recent years, as a general can such as a square 18L can and a pail can, in order to ensure corrosion resistance, a resin-coated can whose inner surface is coated with a thermoplastic resin such as a polyester resin or a polyolefin resin has been applied. Yes.
In order to manufacture such a resin-coated can, first, a metal plate coated with resin avoiding the welded portion is processed into a desired shape such as a cylindrical shape or a rectangular tube shape so that the resin is located on the inner surface. The can body is formed by welding the seam. Next, in order to secure the corrosion resistance of the welded portion, the inner surface of the welded portion is covered with a synthetic resin film or the like. Next, by applying bead processing, curling processing, etc., a top plate, a base plate, a hand ring, etc. are attached to the can body part to complete a resin-coated can.
[0003]
Here, as a method of covering the welded portion in this resin-coated can, a method of coating a polyester-based resin film by thermocompression bonding (see Japanese Patent Publication No. 5-58995), or a two-layer resin film such as a thermoplastic resin / modified polyolefin There is known a method of coating a film by thermocompression bonding (see JP 2001-31926 A).
[0004]
[Problems to be solved by the invention]
However, in the method of covering with the polyester resin film described in the above-mentioned Japanese Patent Publication No. 5-58995, the polyester resin film is hard and the step of the welded portion where the two metal plates are overlapped and welded There is a problem that a gap is easily formed between the metal plate welded portion and the resin film.
[0005]
In the above-mentioned Japanese Patent Application Laid-Open No. 2001-31926, a thermoplastic resin having a melting point of 15 ° C. higher than that of the lower modified polyolefin is used as the surface thermoplastic resin, and a polyolefin having a carboxyl group is used as the lower modified polyolefin. In the examples, only a case where a polyolefin resin is used as the surface-layer thermoplastic resin is disclosed. A resin film whose surface layer is made of polyolefin resin is soft and still insufficient from the viewpoint of pinhole resistance. Moreover, this publication does not suggest that the pinhole resistance is improved by using a thermoplastic polyester for the surface layer as in the present invention.
[0006]
The present invention has been made in view of the above circumstances, and is capable of improving the corrosion resistance of a metal plate by bringing it into close contact with the welded portion of the metal plate and suppressing the occurrence of pinholes. It is an object of the present invention to provide a part coating film, a welding part coating method, and a resin coated can.
[0007]
[Means for Solving the Problems]
  In order to solve such a problem, the invention according to claim 1 is a welded part covering film for covering a welded part of a metal plate, wherein the modified polyolefin layerWhen,Thermoplastic polyester layerAn epoxy thermosetting resin layer cured with a phenolic compound is interposed betweenIt is characterized by being layered.
  According to the welded part covering film in claim 1, the modified polyolefin layer and the thermoplastic polyester layer,Through an epoxy thermosetting resin layer cured with a phenolic compoundIf the modified polyolefin layer is arranged on the contact surface side with the welded portion of the metal plate so as to cover the welded portion by being laminated, the modified polyolefin layer having flexibility becomes the step of the welded portion. It is possible to suppress the occurrence of pinholes due to the steps of the welded portions and the protruding portions by the thermoplastic polyester layer having the hardness while being in close contact with each other. That is, the welded part can be reliably covered, and the corrosion resistance of the welded part can be improved.
[0008]
  Also, StrangeBetween the conductive polyolefin layer and the thermoplastic polyester layer,Epoxy system cured with phenolic compoundsBy interposing the thermosetting resin, the adhesion between the modified polyolefin layer and the thermoplastic polyester layer can be improved. By improving the adhesion of both layersWhat, Even with highly corrosive or highly swellable contents such as paint, weldingPartThe peeling of the covering portion can be suppressed as much as possible.
[0009]
  Also, Claims2The invention described in claim 1 is a welded portion of a metal plate.1It is a welding part coating method which coat | covers with the welding part coating film of description, Comprising: The welding part of the said metal plate is heated at the temperature higher than melting | fusing point of the said modified polyolefin layer and lower than the melting point of the said thermoplastic polyester layer. In this state, the modified polyolefin layer side is subjected to thermocompression bonding so as to adhere to the welded portion of the metal plate.
[0010]
  Here, it is preferable to heat to a temperature of 120 to 240 ° C. as a temperature higher than the melting point of the modified polyolefin layer and lower than the melting point of the thermoplastic polyester layer.
  Claim2According to the method for covering a welded portion described in 1), it becomes possible to reliably cover the welded portion in the metal plate with the welded portion covering film of the present invention.
[0011]
  And claims3In the resin-coated can in which the can body portion is formed by bending and welding a metal plate coated with a resin, the welded portion of the metal plate is the invention according to claim 1.1It is characterized by being covered with the described weld coating film.
  Claim3According to the resin-coated can according to claim 1, the welded portion formed in the can body portion,1Corrosion resistance can be improved by covering the described welded portion covering film. At this time, the modified polyolefin layer side of the welded part covering film covers the welded part of the metal plate.
[0012]
  And claims4The invention described in the above is a welded portion covering film for covering a welded portion of a metal plate, on the upper surface of the first modified polyolefin layer, a polyolefin layer, a second modified polyolefin layer,An epoxy thermosetting resin layer cured with a phenolic compound;A thermoplastic polyester layer is sequentially laminated.
  Claim4According to the weld coating film described in the above, on the upper surface of the first modified polyolefin layer, a polyolefin layer, a second modified polyolefin layer,An epoxy thermosetting resin layer cured with a phenolic compound;By sequentially laminating the thermoplastic polyester layer, if the first modified polyoleophine layer is disposed on the contact surface side with the welded portion of the metal plate so as to cover the welded portion, the flexible first layer is obtained. The modified polyolefin layer, the polyolefin layer, and the second modified polyolefin layer are closely adhered to and bonded to the step of the welded portion, and the thermoplastic polyester layer having hardness is used to prevent the pinhole at the stepped portion of the welded portion and the protrusion. Occurrence can be suppressed. That is, the welded part can be reliably covered, and the corrosion resistance of the welded part can be improved.
[0013]
  In addition, in the welded portion covering film, by including a polyolefin layer having excellent barrier properties of the contents, intrusion of moisture and the like from the outside is suppressed, so that the corrosion resistance can be further improved..
[0014]
  further, Between the second modified polyolefin layer and the thermoplastic polyester layer,Epoxy system cured with phenolic compoundsBy interposing the thermosetting resin, the adhesion between the second modified polyolefin layer and the thermoplastic polyester layer can be improved.
  And claims5The invention described in claim 1 is a welded portion of a metal plate.4A welded portion covering method for covering with a welded portion covering film according to claim 1, wherein the welded portion of the metal plate is higher than the melting points of the first and second modified polyolefin layers and the polyolefin layer, and the heat In the state heated at a temperature lower than the melting point of the plastic polyester layer, thermocompression bonding is performed so that the first modified polyolefin layer side adheres to the welded portion of the metal plate.
[0015]
  Here, it is preferable to heat to a temperature of 120 to 240 ° C. as a temperature higher than the melting points of the first and second modified polyolefin layers and the polyolefin layer and lower than the melting point of the thermoplastic polyester layer.
  Claim5According to the method for covering a welded portion described in 1), it becomes possible to reliably cover the welded portion in the metal plate with the welded portion covering film of the present invention. By improving the adhesion of both layersWhatEven if a highly corrosive or highly swellable content such as paint is used, it is possible to suppress the peeling of the welded portion covering portion as much as possible.
[0016]
  And claims6In the resin-coated can in which the can body is formed by bending and welding a metal plate coated with a resin, the welded portion of the metal plate includes4It is coat | covered with the welding part coating film as described in above.
  Claim6According to the resin-coated can according to claim 1, the welded portion formed in the can body portion,4It becomes possible to improve corrosion resistance by coat | covering with the welding part coating | film | coat film as described in above. At this time, the first modified polyolefin layer side of the welded part covering film covers the welded part of the metal plate.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a structural example of a welded portion covering film of the present invention.
The resin-coated can 100 according to the present embodiment includes a steel plate 1 having a polyester-based or polyolefin-based thermoplastic resin film (resin) 2 bonded on one side, and the thermoplastic resin film 2 on the inner surface side (upper surface side in FIG. 1). The can body portion is formed by bending and welding into a cylindrical shape so as to be positioned at (). The welded portion W inside the can is covered with the welded portion coating film 10.
[0018]
The welded part covering film 10 has a three-layer structure in which a modified polyolefin layer 11, a thermosetting resin layer 12, and a thermoplastic polyester layer 13 are sequentially laminated, and the modified polyolefin layer 11 side is a welded part of the steel plate 1. Bonded to contact W.
The modified polyolefin layer 11 has a function of bringing the weld coating film 10 into close contact with the weld W, and has at least one functional group selected from a carboxyl group, an acid anhydride group, an epoxy group, a hydroxyl group, and an ester group. It is comprised from the polyolefin modified | denatured with the compound which has. For example, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene homopolymer, block or random copolymer composed of polypropylene and a small amount of α-olefin, polyolefin-based thermoplastic elastomer such as ethylene-propylene rubber, etc. , Polar groups such as maleic anhydride, acrylic acid and glycidyl methacrylate are introduced by graft reaction or the like. A mixture of two or more of these modified polyolefins may be used. In particular, in order to improve adhesion to the weld, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene homopolymer, polypropylene-α-olefin copolymer, maleic anhydride, acrylic acid, It is preferable to use a graft copolymerized glycidyl methacrylate.
[0019]
The thickness of the modified polyolefin layer 10 is not particularly limited, but is preferably 30 to 200 μm, and more preferably 40 to 150 μm. Here, if the thickness of the modified polyolefin layer is 30 μm or less, pinholes are likely to be generated due to the step S or the protrusion P of the welded portion W, while the cost increases if the thickness of the modified polyolefin layer 11 is 150 μm or more. Therefore, it is desirable to set the above range.
[0020]
  The thermosetting resin layer 12 functions as an adhesive for bonding the modified polyolefin layer 11 and the thermoplastic polyester layer 13,Uses epoxy thermosetting resin cured with phenolic compoundsYes. For example, condensates of aromatic bisphenol and epichlorohydrin are converted to phenolic compounds.To thingsTherefore, the cured thermosetting resinAllI can get lost.
[0021]
By providing such a thermosetting resin layer 12, the adhesion between the modified polyolefin layer 11 and the thermoplastic polyester layer 13 is significantly improved.
The thickness of the thermosetting resin layer 12 is not particularly limited, but is preferably 0.1 to 10.0 μm, and more preferably 0.3 to 5.0. Here, if the thickness of the thermosetting resin layer 12 is 0.1 μm or less, the adhesiveness with the modified polyolefin layer 11 is lowered. On the other hand, if the thickness of the thermosetting resin layer 12 is 10.0 μm or more, the cost is reduced. Therefore, the above range is desirable.
[0022]
The thermoplastic polyester layer 13 has a function of suppressing the generation of pinholes due to the step S or the protrusion P of the welded portion W, and is made of a thermoplastic polyester resin. For example, polyester homopolymers such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene 2,6-naltalate, and these polyester homopolymers are isophthalic acid, butanediol, 2,6-naphthalenedicarboxylic acid, bisphenol. A, adipic acid, sebacic acid, azelaic acid, a copolymerized polyester obtained by copolymerizing diethylene glycol, triethylene glycol, propylene glycol, and the like, and a polyester composition obtained by mixing two or more of the above-described polyester resins. In particular, in order to ensure excellent content barrier properties, it is preferable to use polyethylene terephthalate, polyethylene terephthalate / isophthalate copolymer, polyethylene terephthalate / polybutylene terephthalate copolymer, and the like.
[0023]
Here, the thermoplastic polyester layer 13 may have a single-layer structure made of one of the above-described thermoplastic polyester resins or compositions, or a laminated structure made of two or more kinds.
Moreover, although melting | fusing point of the thermoplastic polyester resin which comprises the thermoplastic polyester layer 13 is not specifically limited, It is preferable not to melt | dissolve by the heat processing at the time of coating | covering.
[0024]
Further, the thickness of the thermoplastic polyester layer 13 is not particularly limited, but is preferably 5 to 50 μm, more preferably 10 to 40 μm. Here, if the thickness of the thermoplastic polyester layer 13 is 5 μm or less, pinholes are likely to occur. On the other hand, if the thickness of the thermoplastic polyester layer 13 is 50 μm or more, the cost increases. It is desirable.
[0025]
Here, any method may be used as a method of laminating the above three layers to form the welded portion covering film 10, and examples thereof include the following methods.
First, a thermoplastic polyester layer 13 and a modified polyolefin layer 11 having a desired thickness are formed by a T-die extrusion method or the like.
At this time, the thermoplastic polyester layer 13 is desirably oriented crystallized by uniaxial stretching, biaxial stretching, or the like in order to improve strength and barrier properties of the contents. The plane orientation coefficient that serves as a measure of the oriented crystallinity is not particularly limited, but is preferably in the range of 0.12 to 0.18. Here, if the plane orientation coefficient is 0.12 or less, the content barrier property is lowered. On the other hand, if the plane orientation coefficient is 0.18 or more, heat shrinkage easily occurs during the heat treatment. A range is desirable. The plane orientation coefficient is determined by the following formula using an Abbe refractometer and measuring the refractive index in the thickness direction (α), width direction (β), and longitudinal direction (γ) of the weld coating film. Calculated.
Orientation coefficient ΔP = {(β + γ) / 2} −α
Subsequently, after applying an uncured thermosetting resin layer 12 to one surface of the thermoplastic polyester layer 13, the modified polyolefin layer 11 is laminated on the thermosetting resin layer 12 side, and the three layers are bonded by dry lamination. Let The temperature during this dry lamination is preferably 100 to 200 ° C. Here, when the temperature of the dry laminate is 100 ° C. or less, the curing reaction of the thermosetting resin layer 12 is difficult to proceed, and the adhesive strength between the thermoplastic polyester layer 13 and the thermosetting resin layer 12 is lowered. On the other hand, when the dry lamination temperature is 200 ° C. or higher, the modified polyolefin layer 11 is remarkably melted, so that it becomes difficult to form the weld coating film 10.
[0026]
Next, the manufacturing method of the resin-coated can 100 in this embodiment and the coating method of the welding part coating film to the welding part W in this resin-coated can 100 are demonstrated.
2A and 2B show a part of a method for producing a resin-coated can according to the present invention, wherein FIG. 2A is a plan view of a metal plate which is a material for forming the resin-coated can, and FIG. It is sectional drawing which shows the state welded cylindrically.
[0027]
First, a polyester or polyolefin-based thermoplastic resin film 2 is adhered to one surface of the steel plate 1 that is a constituent material of the resin-coated can 100 except for an end portion of a welded portion W that is a joint. Then, the steel plate 1 to which the thermoplastic resin film 2 is bonded is cut into a predetermined size, bent so that the surface of the thermoplastic resin film 2 is located inside, and the end portion is overlapped by about 1 mm. Form a cylinder.
[0028]
Then, the can body part of the resin-coated can 100 is formed by seam welding the end part. At this time, since the end portions of the metal plate are overlapped and welded, a step S corresponding to a plate thickness of about 0.3 to 0.4 mm is generated in the welded portion W. Moreover, since the steel plate 1 melted by the welding heat protrudes and hardens from the welded portion W, a protruding portion P called dust is also generated.
[0029]
And the welding part W in the can body inner surface of the resin-coated can 100 is heated at a temperature higher than the melting point of the modified polyolefin layer 11 and lower than the melting point of the thermoplastic polyester layer 13, for example, 120 to 240 ° C. The weld coating film 10 is thermocompression bonded so that the modified polyolefin layer 11 side is in contact with the steel plate 1.
Here, the modified polyolefin layer 11 having a melting point lower than the heating temperature is melted and bonded to the steel plate 1 so as to cover the gap between the stepped portion S and the protruding portion P of the welded portion W. Further, the thermoplastic polyester layer 13 having a melting point higher than the heating temperature does not melt and has a function of suppressing breakage of the stepped portion S and the protruding portion P of the welded portion W and occurrence of pinholes.
[0030]
  The resin-coated can 100 having such a configuration has a gap between the welded portion W of the steel sheet 1 and the welded portion-covered film 10 because the welded portion W is covered with the welded portion-covered film 10 described above. Since it does not exist and no pinholes are generated, the corrosion resistance can be greatly improved..
[0031]
Further, as a method of forming the weld coating film 10 in the present embodiment, a modified polyolefin layer is formed on one surface of the thermoplastic polyester layer 13 to which the uncured thermosetting resin layer 12 is applied, and on the thermosetting resin layer 12 side. 11 is laminated and dry-laminated to be bonded, but the present invention is not limited to this as long as the thermosetting resin layer 12 is interposed between the thermoplastic polyester layer 13 and the modified polyolefin layer 11. For example, an uncured thermosetting resin layer 12 may be applied to one surface of the modified polyolefin layer 11, and a thermoplastic polyester layer 13 may be laminated on the thermosetting resin layer 12 side, followed by dry lamination. Absent.
[0032]
[First Example]
  Next, the presence or absence of pinholes in the resin-coated can according to the present embodiment, the presence or absence of voids in the weld step, and the results of evaluating the corrosion resistance will be described. Table 1 shows the results of evaluating the forming material of the weld coating film 10 used in Examples 1 to 8 and Comparative Examples 1 to 5, the presence or absence of pinholes, and the presence or absence of voids in the weld step. The presence or absence of pinholes can be determined as a resin-coated can.MadeIn 10 pail cans, the number of pinholes generated in the weld was measured using a wet pinhole meter. Moreover, the presence or absence of the space | gap in a welding part level | step difference investigated visually the space | gap in a welding part level | step difference. In addition, corrosion resistance is a pail can that has been evaluated for pinholes and voids.InThe corrosion state of the weld was investigated by filling with a surfactant (Johnson floor detergent) and leaving it at 40 ° C. for 3 months. Figure3 isIt is a figure which shows the relationship between the thickness of a welding part coating film, and a pinhole incidence rate, and the result in Examples 1, 4, and 5 and Comparative Examples 1-4 was shown here.
[0033]
Here, in the manufacturing method of the resin-coated can 100 in the present embodiment, first, polyethylene (PE) is formed on the upper surface of the steel plate 1 made of TFS (Tin Free Steel, plate thickness 0.25 mm) preheated to 180 ° C. : Idemitsu Unitech 765C, film thickness 70 μm) was laminated by a roll laminator.
Next, the steel plate 1 was bent in a pail can production line, and the can body was welded. And in the state which heated the welding part W at 180 degreeC, the welding part coating | coated film 10 used as a sample is thermocompression bonded so that the modified polyolefin layer 11 side may adhere | attach the welding part W with a roll crimping | compression-bonding method. Here, the welding part coating | coated film 10 used by the present Example used what was processed into the tape shape of width 20mm and length 10m all.
[0034]
Next, after performing bead processing and curling, the top plate and the base plate were attached using a conventional technique to complete a pail can.
[0035]
[Table 1]

[0036]
In Example 1, as the thermoplastic polyester layer 13, a polyester film having a two-layer structure composed of PET (melting point 255 ° C.) and a PET / isophthalate copolymer (melting point 207 ° C.) (Merinex 850 manufactured by DuPont Sure, film) A thickness of 20 μm and an orientation coefficient of 0.166) were applied. Moreover, as the thermosetting resin layer 12, an epoxy resin (epoxy-phenol resin manufactured by Toyo Ink) was applied. Furthermore, as the modified polyolefin layer 11, maleic anhydride-modified polyethylene (Mitsui Chemicals Admer XE070, melting point 85 ° C.) was applied.
[0037]
Example 2 was the same as Example 1 except that a PET single layer film (s-25 manufactured by Unitika, film thickness 25 μm, orientation coefficient 0.168, melting point 255 ° C.) was used as the thermoplastic polyester layer 13. Was evaluated.
In Example 3, a polyester film having a two-layer structure composed of PET (melting point: 255 ° C.) and a PET / isoterephthalate copolymer (melting point: 207 ° C.) as the thermoplastic polyester layer 13 (PTO55, manufactured by Garware Co., Ltd., film thickness: 30 μm, orientation) Evaluation was performed under the same conditions as in Example 1 except that the coefficient 0.165) was used.
[0038]
In Example 4, evaluation was performed under the same conditions as in Example 1 except that the modified polyolefin layer 11 was made of the same material as in Example 1 and the film thickness was changed to 30 μm.
In Example 5, the modified polyolefin layer 11 was evaluated under the same conditions as in Example 1 except that the same material as in Example 1 was used and the film thickness was 150 μm.
Example 6 uses PET (Melenex 850 manufactured by DuPont) as the thermoplastic resin film 2 to be laminated on the steel sheet 1, and maleic anhydride-modified polyethylene (Admer SF731, manufactured by Mitsui Chemicals, melting point 70 ° C.) as the modified polyolefin layer 11. ) Was used under the same conditions as in Example 1.
[0039]
Example 7 uses PET (Merinex 850 manufactured by DuPont) as the thermoplastic resin film 2 to be laminated on the steel plate 1, and epoxy-modified polyethylene (3 wt% of glycidyl methacrylate in PE) as the modified polyolefin layer 11. Evaluation was performed under the same conditions as in Example 1 except that 0.3% peroxide (Nippon Yushi Park Mill D) was added and a twin screw extruder was modified at 180 ° C., melting point 90 ° C. went.
[0040]
Example 8 uses polypropylene (two-layer structure of homopolypropylene and maleic anhydride-modified random copolymerized polypropylene, film thickness 50 μm) as the thermoplastic resin film 2 to be laminated on the steel plate 1, and the modified polyolefin layer 11 The evaluation was performed under the same conditions as in Example 1 except that maleic anhydride-modified polypropylene (Mitsui Chemicals Admer QF570, melting point 80 ° C.) was used.
[0041]
Further, Comparative Example 1 is a film made of only a polyester layer as a welded portion covering film (PTO55, manufactured by Galware Inc., two-layer structure made of PET and PET / isophthalate copolymer, film thickness 30 μm, orientation coefficient 0.165). Evaluation was performed under the same conditions as in Example 1 except that was used.
Comparative Example 2 was evaluated under the same conditions as in Example 1 except that the film used in Comparative Example 1 was used and the film thickness was 45 μm.
[0042]
Comparative Example 3 was evaluated under the same conditions as in Example 1 except that a film having a two-layer structure of polyethylene and modified polyethylene (Mitsui Chemicals Admer XE070, film thickness 150 μm) was used as the weld coating film. went.
Comparative Example 4 was evaluated under the same conditions as in Example 1 except that the film used in Comparative Example 2 was used and the film thickness was 150 μm.
[0043]
Comparative Example 5 was evaluated under the same conditions as in Example 1 except that a polyester powder coating material (VP manufactured by Dexter Midland Co.) was used as the weld coating film.
As shown in Table 1 and FIG. 3, in the resin-coated can 100 in which the welded portion W is covered with a welded portion coating film 10 composed of a thermoplastic polyester layer 13, a thermosetting resin layer 12, and a modified polyolefin layer 11. It was confirmed that no voids were generated in the pinhole and the welded portion W. Furthermore, it was confirmed that the corrosion resistance in the resin-coated can 100 could be secured.
(Second embodiment)
FIG. 4 is a cross-sectional view showing another configuration example of the welded portion covering film of the present invention.
[0044]
The resin-coated can 100A in the present embodiment is configured by changing the welded portion covering film 10A that covers the welded portion W in the resin-coated can 100 in the first embodiment.
As shown in FIG. 4, the weld-coated film 10 </ b> A in this embodiment includes a first modified polyolefin layer 14, a polyolefin layer 15, a second modified polyolefin layer 16, a thermosetting resin layer 12, and a heat It has a five-layer structure in which a plastic polyester layer 13 is sequentially laminated, and is bonded so that the first modified polyolefin layer 14 side and the welded portion W side of the steel plate 1 are in contact with each other.
[0045]
The first modified polyolefin layer 14 and the second modified polyolefin layer 16 can be made of the same material as the modified polyolefin layer 11 used in the first embodiment. The modified polyolefin layer 16 may be made of the same material or different materials.
The thicknesses of the first modified polyolefin 14 and the second modified polyolefin layer 16 are not particularly limited, but are preferably 1 to 30 μm, and more preferably 3 to 20 μm. Here, when the thickness of the first modified polyolefin layer 14 and the second modified polyolefin layer 16 is 1 μm or less, the adhesiveness with the thermosetting resin layer 12 and the adhesiveness with the welded portion W are reduced. Since the cost increases when the thickness of the first modified polyolefin layer 14 and the second modified polyolefin layer 16 is 30 μm or more, the above range is preferable. In addition, as long as the thickness of the 1st modified polyolefin layer 14 and the 2nd modified polyolefin layer 16 is in the above-mentioned range, you may form the same even if it is the same.
[0046]
The polyolefin layer 15 is a low density polyethylene, a high density polyethylene, a linear low density polyethylene, a polypropylene, a polypropylene homopolymer, a block or random copolymer composed of polypropylene and a small amount of α-olefin, a polyolefin system such as ethylene-propylene rubber. Examples thereof include thermoplastic elastomers and mixtures of these polyolefin resins. In particular, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene homopolymer, and a block or random copolymer composed of polypropylene and a small amount of α-olefin are desirable.
[0047]
The thickness of the polyolefin layer 15 is not particularly limited, but is preferably 5 to 180 μm, more preferably 10 to 150 μm. Here, if the thickness of the polyolefin layer is 5 μm or less, pinholes are likely to occur. On the other hand, if the thickness of the polyolefin layer 15 is 150 μm or more, the cost increases.
[0048]
The thermosetting resin layer 12 and the thermoplastic polyester layer 13 can be the same as those described in the first embodiment.
Here, any method may be used as a method of laminating the five layers described above to form the welded portion covering film 10A, and examples thereof include the following methods.
First, a thermoplastic polyester layer 13 having a desired thickness and a three-layer film of a first modified polyolefin layer 14 / polyolefin layer 15 / second modified polyolefin layer 16 are formed by a T-die extrusion method or the like.
[0049]
Subsequently, after applying an uncured thermosetting resin layer 12 to one surface of the thermoplastic polyester layer 13, the first modified polyolefin layer 14 / polyolefin layer 15 / second layer is formed on the thermosetting resin layer 12 side. A three-layer film of the modified polyolefin layer 16 is laminated, and the five layers are adhered by dry lamination. The temperature during this dry lamination is preferably 100 to 200 ° C. Here, when the temperature of the dry laminate is 100 ° C. or less, the curing reaction of the thermosetting resin layer 12 is difficult to proceed, and the adhesive strength between the thermoplastic polyester layer 13 and the thermosetting resin layer 12 is lowered. On the other hand, when the dry lamination temperature is 200 ° C. or higher, the first modified polyolefin layer 14 and the second modified polyolefin layer 16 are remarkably melted, which makes it difficult to form the weld-coated film 10A. End up.
[0050]
Here, the total thickness of the first modified polyolefin layer 14, the polyolefin layer 15, and the second modified polyolefin layer 16 is not particularly limited, but is preferably 30 to 200 μm, more preferably 40 to 180 μm. Is good. Here, if the total thickness is 30 μm or less, pinholes are likely to occur. On the other hand, if the total thickness is 200 μm or more, the cost increases.
[0051]
Next, a method for manufacturing the resin-coated can 100A according to the present embodiment and a method for covering the welded portion W to the resin-coated can 100A with the weld-coated film 10A will be described. In addition, the part which overlaps with 1st embodiment is abbreviate | omitted.
In the resin-coated can 100A according to the present embodiment, the welded portion W on the inner surface of the can body is higher than the melting points of the first modified polyolefin layer 14, the second modified polyolefin layer 16, and the polyolefin layer 15, and is a thermoplastic polyester layer. In a state heated at a temperature lower than the melting point of 13, for example, 120 to 240 ° C., the weld coating film 10A is thermocompression bonded to the weld W so that the first modified polyolefin layer 14 side is in contact with the steel plate 1. ing.
[0052]
At this time, the first modified polyolefin layer 14, the polyolefin layer 15, and the second modified polyolefin layer 16 having a melting point lower than the heating temperature are melted to cover the gap between the step S and the projection P of the welded portion W. It adheres to the steel plate 1 as shown. Further, the thermoplastic polyester layer 13 having a melting point higher than the heating temperature does not melt and has a function of suppressing breakage of the stepped portion S and the protruding portion P of the welded portion W and occurrence of pinholes. Further, the second modified polyolefin layer 16 also has a function of improving the adhesion between the polyolefin layer 15 and the thermosetting resin layer 12.
[0053]
Thus, the resin-coated can 100A in the present embodiment is covered between the welded portion W of the steel sheet 1 and the welded portion coated film 10A by covering the welded portion W with the welded portion coated film 10A described above. Since there is no gap and no pinhole is generated, the corrosion resistance can be greatly improved.
In addition, according to the welded portion covering film 10A in the present embodiment, the inclusion of the polyolefin layer 15 having excellent barrier properties can effectively suppress intrusion of moisture and the like from the outside. It is possible to further improve the corrosion resistance in the case.
[0054]
  In addition,BookAs a method for forming the weld coating film 10A in the embodiment, an uncured thermosetting resin layer 12 is applied to one surface of the thermoplastic polyester layer 13, and the first modified polyolefin layer 14 is provided on the thermosetting resin layer 12 side. A three-layer film consisting of / polyolefin layer 15 / second modified polyolefin layer 16 was laminated, dry laminated and adhered, but the thermosetting property was between the thermoplastic polyester layer 13 and the second modified polyolefin layer 16. If it interposes the resin layer 12, it will not restrict to this.
  For example, the uncured thermosetting resin layer 12 is applied to the second modified polyolefin layer 16 side of the three-layer film composed of the first modified polyolefin layer 14 / polyolefin layer 15 / second modified polyolefin layer 16. Alternatively, the thermoplastic polyester layer 13 may be laminated on the thermosetting resin layer 12 side and dry laminated.
[0055]
[Second embodiment]
Next, the presence or absence of pinholes in the resin-coated can according to the present embodiment, the presence or absence of voids in the weld step, and the results of evaluating the corrosion resistance will be described. Table 2 shows the results of evaluating the forming material of the weld coating film 10 used in Examples 9 to 16, the presence or absence of pinholes, and the presence or absence of voids in the weld step. Here, the comparative example, the evaluation method, and the test conditions were the same as those in the first example.
[0056]
[Table 2]

[0057]
    In Example 9, as the thermoplastic polyester layer 13, a polyester film having a two-layer structure composed of PET (melting point 255 ° C.) and a PET / isophthalate copolymer (melting point 207 ° C.) (Melnex 850 manufactured by DuPont, film) A thickness of 20 μm and an orientation coefficient of 0.166) were used. In addition, as the thermosetting resin 12, an epoxy resin (epoxy-phenol resin manufactured by Toyo Ink) was used. Furthermore, as the first modified polyolefin layer 14 and the second modified polyolefin layer 16, maleic anhydride-modified polyethylene (Mitsui Chemicals Admer, melting point 85 ° C.) was used. Further, polyethylene (Lexlon V351 manufactured by Nisseki Chemical Co., Ltd., melting point 125 ° C.) was used as the polyolefin layer 15. Here, the maleic anhydride-modified polyethylene that is the first modified polyolefin layer 14, the polyethylene that is the polyolefin layer 15, and the maleic anhydride-modified polyethylene that is the second modified polyolefin layer 16 are obtained by a T-die extrusion method. Co-extrusion was performed to form a three-layer film of maleic anhydride-modified polyethylene (5 μm) / polyethylene (40 μm) / maleic anhydride-modified polyethylene (5 μm). Then, this three-layer film and the thermoplastic polyester layer 13 are dry-laminated in the same manner as in the first embodiment to produce a welded layer covering film 10A having a five-layer structure.Madeis doing.
[0058]
Example 10 was the same as Example 9 except that a PET single layer film (s-25 manufactured by Unitika, film thickness 25 μm, orientation coefficient 0.168, melting point 255 ° C.) was used as the thermoplastic polyester layer 13. Was evaluated.
In Example 11, as a thermoplastic polyester layer 13, a polyester film having a two-layer structure composed of PET (melting point: 255 ° C.) and a PET / isoterephthalate copolymer (melting point: 207 ° C.) (PTO55 manufactured by Galware Co., Ltd., film thickness: 30 μm, orientation) Evaluation was performed under the same conditions as in Example 9 except that the coefficient 0.165) was used.
[0059]
Example 12 was evaluated under the same conditions as in Example 9 except that the film thickness of the first modified polyolefin layer 14 / polyolefin layer 15 / second modified polyolefin layer 16 was 5 μm / 20 μm / 5 μm, respectively. went.
Example 13 was evaluated under the same conditions as in Example 9 except that the film thicknesses of the first modified polyolefin layer 14 / polyolefin layer 15 / second modified polyolefin layer 16 were 10 μm / 130 μm / 10 μm, respectively. went.
[0060]
In Example 14, PET (Melnex 850 manufactured by DuPont) was used as the thermoplastic resin film 2 laminated on the steel sheet 1, and maleic anhydride-modified was used as the first modified polyolefin layer 14 and the second modified polyolefin layer 16. Evaluation was carried out under the same conditions as in Example 9 except that polyethylene (Admer SF731, manufactured by Mitsui Chemicals, melting point: 70 ° C.) was used.
[0061]
In Example 15, PET (Melnex 850 manufactured by DuPont) was used as the thermoplastic resin film 2 laminated on the steel sheet 1, and epoxy-modified polyethylene (as the first modified polyolefin layer 14 and the second modified polyolefin layer 16) was used. Except for using PE with 3% by weight of glycidyl methacrylate and 0.3% of peroxide (Nippon Oil & Fats Park Mill D), modified at 180 ° C in a twin-screw extruder, melting point 90 ° C) Evaluation was performed under the same conditions as in Example 9.
[0062]
Example 16 uses polypropylene (two-layer structure of homopolypropylene and maleic anhydride-modified random copolymerized polypropylene, film thickness 50 μm) as the thermoplastic resin film 2 to be laminated on the steel plate 1, and the first modification. Evaluation was performed under the same conditions as in Example 9 except that maleic anhydride-modified polypropylene (Mitsui Chemical Admer QF570, melting point 80 ° C.) was used as the polyolefin layer 14 and the second modified polyolefin layer 16.
[0063]
As shown in Table 2, it has a five-layer structure consisting of a thermoplastic polyester layer 13, a thermosetting resin layer 12, a first modified polyolefin layer 14, a polyolefin layer 15, and a second modified polyolefin layer 16. In the resin-coated can 100 </ b> A in which the welded portion W is covered with the welded portion coating film 10, it has been confirmed that neither a pinhole nor a gap in the welded portion W is generated. Furthermore, it was confirmed that the corrosion resistance in the resin-coated can 100A could be secured.
[0064]
In addition, although the cylindrical-shaped thing was demonstrated as the resin-coated cans 100 and 100A in 1st and 2nd embodiment, it is not restricted to this, It applies to the resin-coated cans 100 of any shape, such as square shape and polygonal shape. It is possible.
Moreover, in 1st and 2nd embodiment, although the example which coat | covers the welding part coating films 10 and 10A of this invention to the welding part W of the resin coating cans 100 and 100A was demonstrated, it coat | covers the welding part of a metal plate. It is also possible to apply to other uses as long as it does.
[0065]
【The invention's effect】
As described above, according to the welded portion covering film of the first aspect, the modified polyolefin having flexibility adheres to and adheres to the step of the welded portion, and the thermoplastic polyester layer having hardness causes the welded portion of the welded portion to adhere. It is possible to suppress the occurrence of pinholes at the steps and the protrusions. That is, the welded part can be reliably covered, and the corrosion resistance of the welded part can be improved.
[0066]
  AlsoIt becomes possible to improve the adhesion between the modified polyolefin layer and the thermoplastic polyester layer. For this reason, after the welding part coating film in this invention is adhere | attached on a metal plate, it becomes possible to process this metal plate easily and reliably.
  Claim2According to the method for covering a welded portion described in 1), it becomes possible to easily and reliably coat the welded portion covering film on the metal plate.
[0067]
  Claim3According to the resin-coated can described in (1), the corrosion resistance can be greatly improved. Claim4According to the welded part covering film described in the above, the modified polyolefin having softness closely adheres to the stepped part of the welded part, and the thermoplastic polyester layer having the rigidity causes the stepped part of the welded part and the pinhole at the protruding part. Occurrence can be suppressed. That is, the welded part can be reliably covered, and the corrosion resistance of the welded part can be improved.
[0068]
  Moreover, it becomes possible to further improve corrosion resistance by including the polyolefin layer which was excellent in the barrier property of the content in a welding part coating film.
  furtherThe adhesion between the second modified polyolefin layer and the thermoplastic polyester layer can be improved. For this reason, after the welding part coating film in this invention is adhere | attached on a metal plate, it becomes possible to process this metal plate easily and reliably.
[0069]
  Claim5According to the method for covering a welded portion described above, it is possible to easily and surely cover the metal plate with the welded portion covering film.
  Claim6According to the resin-coated can described in (1), the corrosion resistance can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a structural example of a welded portion covering film in the present invention.
FIG. 2 is a cross-sectional view showing another configuration example of a welded portion covering film in the present invention.
FIG. 3 is a diagram showing the relationship between the thickness of a welded portion covering film and the pinhole occurrence rate in the present invention.
FIG. 4 is a cross-sectional view showing another configuration example of a welded portion covering film in the present invention.
[Explanation of symbols]
1 Steel plate (metal plate)
2 Thermoplastic resin film (resin)
10, 10A Welding part covering film
11 Modified polyolefin layer
12 Thermosetting resin layer
13 Thermoplastic polyester layer
14 First modified polyolefin layer
15 Polyolefin layer
16 Second modified polyolefin layer
100, 100A resin-coated can
P Projection
S steps
W weld

Claims (6)

It is a welded part covering film for covering a welded part of a metal plate,
And a modified polyolefin layer, between the thermoplastic polyester layer, weld coating film characterized in that epoxy thermosetting resin layer cured with phenolic compounds, which are via layers. A welded part coating method for coating a welded part of a metal plate with the welded part covering film according to claim 1,
In a state where the welded portion of the metal plate is heated at a temperature higher than the melting point of the modified polyolefin layer and lower than the melting point of the thermoplastic polyester layer, the modified polyolefin layer side becomes a welded portion of the metal plate. A method for covering a welded portion, wherein the heat bonding is performed so as to adhere . In a resin-coated can in which a can body is formed by bending and welding a metal plate coated with a resin,
The resin-coated can characterized by the weld part of the said metal plate being coat | covered with the weld part coating film of Claim 1 . It is a welded part covering film for covering a welded part of a metal plate,
A polyolefin layer, a second modified polyolefin layer, an epoxy thermosetting resin layer cured with a phenolic compound, and a thermoplastic polyester layer are sequentially laminated on the upper surface of the first modified polyolefin layer. A welded part covering film characterized by A welded portion covering method for covering a welded portion of a metal plate with the welded portion covering film according to claim 4 ,
In a state where the welded portion of the metal plate is heated at a temperature higher than the melting points of the first and second modified polyolefin layers and the polyolefin layer and lower than the melting point of the thermoplastic polyester layer, A method for covering a welded portion, wherein the modified polyolefin layer side is thermocompression-bonded so that the modified polyolefin layer side adheres to the metal plate . In a resin-coated can in which a can body is formed by bending and welding a metal plate coated with a resin,
A resin-coated can, wherein the welded portion of the metal plate is covered with the welded portion covering film according to claim 4 .

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