JP4184023B2

JP4184023B2 - Covering structure, method for producing the same, and heat-shrinkable composite sheet

Info

Publication number: JP4184023B2
Application number: JP2002289711A
Authority: JP
Inventors: 博文岩崎; 絵美子梶田
Original assignee: Asahi Kasei Fibers Corp
Current assignee: Asahi Kasei Corp
Priority date: 2002-10-02
Filing date: 2002-10-02
Publication date: 2008-11-19
Anticipated expiration: 2022-10-02
Also published as: JP2004122568A

Description

【０００１】
【発明の属する技術分野】
本発明は被覆構造体、その製造方法に関し、さらに詳しくは金属、プラスチック、ガラスなどからなる容器の外表面を熱収縮性複合シートで被覆した、密着性、断熱性、結露防止性および意匠性等に優れた被覆構造体、およびその製造方法に関する。
【０００２】
【従来の技術】
お茶、紅茶、コーヒー、お酒などが入ったガラス、缶、プラスチックなどの飲料容器には耐衝撃性を向上させるために収縮性フィルムが包装材として使用されている。しかし、収縮性フイルムは各種容器の形状に容易に追随させて包装することができるが、突起物の損傷を受け易く、また内容物を容器に入れたまま加熱するとその容器を手で持つことが難しくなるなどの問題があった。
このような問題を改善するため、容器を収縮性不織布で包装する方法が提案されている（例えば、特許文献１参照）。しかし、フィルムを用いた場合に比べて包装材としての強度や加熱容器の断熱性には優れるが、容器との密着性に劣り、包装材を容器に固定できないという問題があった。
【０００３】
また熱収縮しない不織布と熱収縮性のポリエチレンフィルムからなるシーラントフイルムを積層した収縮性包装材料が提案されている（例えば、特許文献２参照）。しかし、この収縮性包装材料はポリエチレンフィルム面を容器に密着させ、不織布を外側にして被覆包装するため、内側のフィルム面を容器形状に追随させて密着させることが難しく、また収縮時に凹凸のシワが発生し易く、外観形状に劣り、また不織布が容器の外側になるため、印刷適性が悪く、印刷表示文字が不鮮明となり、容器の意匠性を向上させることができず、さらに容器が滑り難いという問題があった。また、１０％以上の熱収縮率を有するポリエステル長繊維不織布と熱可塑性フイルムとを積層した収縮性複合シートが提案されている（例えば、特許文献３参照）。しかし、この場合にも、上記と同様に収縮性複合シートのフィルム面を容器の外表面に密着するように熱収縮させるため、上記と同様の問題があった。
【０００４】
上記のように薄く低目付の不織布を容器の外側になるようにして被覆包装すると、不織布の間隙が大きくなり断熱効果が低く、加熱した容器を安心して手で直に持つことができず、また容器を冷却した場合には結露水が発生し易いなどの問題があった。特にジュース、お茶などの飲料の入った容器を冷蔵庫で冷却後、外出時に携帯すると飲料容器の表面が結露により濡れ、該容器を収納したバッグ等が濡れてしまうなどの問題があった。さらに不織布が外側にあるため、表面が毛羽立ち易く、特にに生産ラインでの容器同士の衝突により毛羽が発生し易いという問題があった。また被覆容器を熱水や冷水に入れて加温や冷却をした場合には、容器表面の不織布により水切れが悪くなり、その取扱性に劣るという欠点があった。
【０００５】
【特許文献１】
特開昭６１−２１３６４号公報
【特許文献２】
特公平４−７７００号公報
【特許文献３】
特公平８- １１４３２号公報
【０００６】
【発明が解決しようとする課題】
本発明の課題は、上記従来技術の問題を解決し、密着包装性、表面保護性の他に、特に断熱性、結露防止性、意匠性、耐表面摩耗性および取扱性に優れた被覆構造体、およびその製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
本発明者らは、上記課題について鋭意検討した結果、特定の不織布とフィルムを部分的に接合した熱収縮性複合シートを、フィルム側を外側にして任意の形状を有する容器などの構造体に被覆させて熱収縮させることにより、容器表面とフィルムの間に存在する不織布内に空気層を効率よく閉じ込めることができ、かつフィルムの収縮によるシワの発生をも効率よく防止できるため、密着包装性および表面保護性のみならず、意匠性、断熱性、結露防止性、耐表面摩耗性および取扱性をも大幅に向上させることができることを見いだし、本発明に到達した。
上記課題を達成するために本願で特許請求される発明は以下の通りである。
【０００８】
（１）厚みが０．０５〜０．３ｍｍ、目付が１０〜５０ｇ／ｍ² 、平均見かけ密度が０．０５〜０．３ｇ／ｃｍ^３、部分熱圧着率が３〜３０％であり、潜在収縮率が６％以下であるポリオレフィン系繊維スパンボンド不織布、および厚みが０．０２〜０．１ｍｍ、潜在収縮率が１０％以上である熱可塑性合成樹脂フイルムを、接着剤で接合した、厚みが０．１〜０．４ｍｍで８０〜１８０℃における少なくとも一方向の収縮率が１０〜６０％である熱収縮性複合シートと、該熱収縮性複合シートによって被覆された任意の形状を有する構造体とからなる被覆構造体であって、前記熱可塑性合成繊維不織布が前記構造体の外表面に密着していることを特徴とする断熱性、結露防止性に優れた被覆構造体。
（２）厚みが０．０５〜０．３ｍｍ、目付が１０〜５０ｇ／ｍ² 、平均見かけ密度が０．０５〜０．３ｇ／ｃｍ^３、部分熱圧着率が３〜３０％であり、潜在収縮率が６％以下であるポリオレフィン系繊維スパンボンド不織布、および厚みが０．０２〜０．１ｍｍ、潜在収縮率が１０％以上である熱可塑性合成樹脂フイルムを、接着剤で接合した、厚みが０．１〜０．４ｍｍで８０〜１８０℃における少なくとも一方向の収縮率が１０〜６０％である熱収縮性複合シートを用いて、前記熱可塑性合成樹脂フィルムが外側になるように筒状体とし、該筒状体中に任意の形状を有する金属製容器、プラスチック製容器またはガラス製容器の少なくとも一部を挿入し、その外表面を被覆した後、８０℃以上の温度に加熱して前記筒状体を熱収縮させ、前記容器の外表面に前記ポリオレフィン系繊維不織布を密着させることを特徴とする被覆構造体の製造方法。
【００１０】
【発明の実施の形態】
本発明における被覆構造体は、後述する熱可塑性合成繊維不織布および熱可塑性合成樹脂フィルムを接着剤で接合した熱収縮性複合シートと、該熱収縮性複合シートに内包された任意の形状を有する構造体とからなり、前記熱可塑性合成繊維不織布が前記構造体の外表面に密着されている。
このように、本発明の被覆構造体は、その表面が熱可塑性合成樹脂フィルムで覆われ、構造体とフィルムの間に多くの空気層を持つ不織布が存在するため、優れた断熱効果を確保することができる。また表面がフィルムで覆われているため、印刷適性に優れ、優れた意匠性が得られ、また生産ライン等での容器同士の衝突による表面毛羽立ちを防止できるるとともに、該被覆構造体を熱水や冷水に入れた場合でも水切れ性がよく、その取扱が容易となる。
【００１１】
本発明に用いられる熱可塑性合成繊維不織布は、厚みが０．０５〜０．３ｍｍ、好ましくは０．０７〜０．２５ｍｍ、より好ましくは０．１〜０．２０ｍｍであり、目付が１０〜５０ｇ／ｍ²、好ましくは１２〜４０ｇ／ｍ²、より好ましくは１４〜３０ｇ／ｍ²であることが必要である。
熱可塑性合成繊維不織布の厚みが０．０５ｍｍ未満では密着包装性は向上するが、厚みが薄く、空気層が少なくなり、断熱効果が不足し、さらに強度および保護効果が低下する。また厚みが０．３ｍｍを超えると厚みが厚くなり、空気層が多くなるため、断熱効果および保護効果は向上するが、密着包装性が低下する。また被覆された容器の外径が大きくなるため、既存の生産ラインが使用できなくなる。また熱可塑性合成繊維不織布の目付が１０ｇ／ｍ²未満では厚みが薄くなるが、強度が不足し、包装材としての保護効果が低下する。また目付が５０ｇ／ｍ²を超えると強度が高くなるが、厚みが厚くなり、柔軟性が不足する。
【００１２】
熱可塑性合成繊維不織布に用いられる合成繊維としては、ポリエチレン、ポリプロピレン、共重合ポリプロピレンなどのポリオレフイン系繊維が挙げられる。これらは単独または２種以上混合、積層してもよい。これらの繊維を用いた不織布は、スパンボンド法で得られる部分熱圧着された長繊維不織布が、厚みおよび強度の点で好ましい。
【００１３】
熱可塑性合成繊維不織布は、さらに繊維の見かけ密度が小さく、引裂強度、引張強度などの強度があり、柔軟性に優れていることが好ましい。
具体的には熱可塑性合成繊維不織布の平均見かけ密度は、断熱効果を向上させる点から０．０５〜０．３ｇ／ｃｍ³の範囲が好ましく、より好ましくは０．１〜０．２５ｇ／ｃｍ³である。見かけ密度が０．０５ｇ／ｃｍ³未満では強度が得られない場合があり、０．３ｇ／ｃｍ³を超えると繊維比率が大きくなり、断熱効果が少なくなり、柔軟性が不足する場合がある。
また熱可塑性合成繊維不織布の平均繊維径は１〜４０μｍが好ましく、３〜３０μｍがより好ましい。平均繊維径が１μｍ未満では、強度が不足し、包装材としての保護性が得られない場合があり、４０μｍを超えると柔軟性が不足する場合がある。
【００１４】
また、熱可塑性合成繊維不織布は部分的に熱圧着されていることが好ましく、その部分熱圧着率は３〜３０％が好ましく、より好ましくは５〜２５％である。部分熱圧着率が３％未満では、接合面積が少なくなり、強度が不足し易く、３０％を超えると接合面積が多くなり、強度が高くなるが、柔軟性が不足する場合がある。また部分熱圧着することにより部分圧着された部分に空気層をより多く保持させることができる。
さらに熱可塑性合成繊維不織布の潜在収縮率は６％以下であることが好ましい。熱可塑性合成繊維不織布の潜在収縮率が９．５％を超えると、収縮後の不織布の厚みが大きくなり、嵩高となりやすく、また収縮時にしわや凹凸が発生し易く、外観性が低下し易くなる。不織布の潜在収縮率が９．５％以下の場合には、不織布の繊維間隙の存在により、フィルムの収縮に不織布が追随し易くなるため、フィルム表面にしわや凹凸が発生するのを抑制し易くなる。
【００１５】
本発明に用いられる熱可塑性合成樹脂フイルムは、厚みが０．０２〜０．１ｍｍ、好ましくは０．０３〜０．０８ｍｍで、潜在収縮率が１０％以上、好ましくは１０〜７０％、より好ましくは２０〜６０％、特に好ましくは３０〜５５％であることが必要である。該フィルムの厚みが０．０２ｍｍ未満では収縮力が小さくなり密着包装が難しくなり、０．１ｍｍを超えると収縮力が大きくなるが、柔軟性が劣り、容器形状への追随性が劣る。またフィルムの潜在収縮率が１０％未満では、容器に対する密着包装性が低下する。
熱可塑性合成樹脂フイルムとしては、ポリエチレン、ポリプロピレン、共重合ポリエチレン、共重合ポリプロピレンなどのポリオレフイン系樹脂、ポリ塩化ビニール樹脂、ポリエステル系樹脂、ポリスチレン系樹脂などからなるフィルムが用いられるが、ポリエステル系樹脂フィルムが耐熱性、加工性等の点で好ましい。また熱可塑性合成樹脂フィルムは、その潜在収縮率が１０％以上であれば、縦または横方向のいずれか一方向のみに収縮する一軸延伸フィルムでも、縦および横方向のいずれにも収縮する二軸延伸フィルムであってもよい。
【００１６】
本発明に用いられる熱収縮性複合シートは、上記した熱可塑性合成繊維不織布と熱可塑性合成樹脂フイルムとを接着剤を接合することにより得られる。該熱収縮性複合シートは、厚みが０．１〜０．４ｍｍ、好ましくは０．１3 〜０．３ｍｍ、より好ましくは０．１5 〜０．２５ｍｍであり、かつ８０〜１８０℃における少なくとも一方の収縮率が１０〜６０％、好ましくは２０〜５０％、より好ましくは２５〜４５％である。
熱収縮性複合シートの厚みが０．１ｍｍ未満では、厚さは薄く、柔軟性、密着加工性などが良好となるが、薄すぎて断熱性が不足する。また厚みが０．４ｍｍを超えると断熱性が良好となるが、柔軟性、密着加工性が不足する。また熱収縮性複合シートの収縮率が８０〜１８０℃における少なくとも一方向の収縮率が１０％未満では容器の凹凸に対する追従性が不足し、６０％を超えると容器の凹凸に対する追随性は向上するが、フィルム表面に印刷を施した場合にフィルムの収縮により印刷文字などが変形し、意匠性が低下する。
【００１７】
熱可塑性合成繊維不織布と熱可塑性合成樹脂フイルムは、フィルム収縮時に不織布が剥離せずに一体となって熱収縮加工ができるように接合する必要があるが、このような接合は、熱可塑性合成繊維不織布または熱可塑性合成樹脂フイルムの一方に接着剤を好ましくは２〜１５％ｇ／ｍ²の塗布量で塗布して行うことができる。接着剤のより好ましい塗布量は４〜１２ｇ／ｍ²である。接着剤としては１液タイプまたは２液タイプのウレタン系樹脂、アクリル系樹脂、ポリオレフイン系樹脂、ポリアミド系樹脂、ポリエステル系樹脂、ホットメルト系樹脂などが好ましく用いられる。接着方法には特に制限はなく、たとえば、ウエットラミネート方式、ドライラミネート方式、押出しラミネート方式、またはホットメルト系樹脂を熱風と共に加熱溶融させるカーテンスプレー方式などで行うことができる。
【００１８】
本発明において、熱可塑性合成繊維不織布と熱可塑性合成樹脂フイルムの重量比（熱可塑性合成繊維不織布：熱可塑性合成樹脂フイルム）は１０〜５０：９０〜５０が好ましく、より好ましくは２０〜４５：８０〜５５である。熱可塑性合成繊維不織布の重量比が１０％未満では、フイルム比率が大きくなり、密着包装性が良くなるが、不織布の比率が少なくなり、断熱性が得られない場合がある。一方、５０％を超えると不織布の比率が多くなり、断熱性が良くなるが、フイルムの比率が少なく、収縮包装の時、収縮力が不足し、シワや凹凸が生じやすく、密着包装ができない場合がある。
【００１９】
本発明における被覆構造体は、例えば、上記熱収縮性複合シートを熱可塑性合成樹脂フィルムが外側になるように熱シール等により筒状体とし、該筒状体により任意の形状を有する金属製容器、プラスチック製容器またはガラス製容器などの構造体の外表面の少なくとも一部を被覆した後、該筒状体を８０〜１８０℃以上の温度の熱風や加熱蒸気などで数秒〜数十秒加熱して熱収縮させることにより得ることができる。各種容器の外周部分は熱収縮性複合シートの収縮で容器形状に密着包装されて被覆される。
熱収縮性複合シートを用いて筒状体とする場合には、熱により収縮する方向が少なくとも円周方向になるようにし、また、二軸方向に収縮する場合には、収縮率の少ない方向を容器の高さ方向とするのが密着性および意匠性の点で好ましい。筒状体は熱収縮性複合シートの両端部を重ね合わせて熱シールなどで接合させて得ることができる。
【００２０】
本発明における被覆構造体は、印刷適性に優れたフイルム面が容器の外側となっているため、あらかじめフィルム面に文字印刷、商標、写真、絵柄などを印刷しておくことにより容器の意匠性等を大幅に向上させることができる。また、不織布層がフィルム層と容器との間に存在するため、容器形状に追随した良好な密着性が得られ、かつ、フィルム面と容器の間には空気層をより多く含んだ薄い不織布が介在するため、優れた断熱効果が得られ、容器を加温または冷却した場合でも、不安なく、その容器を直に手にもって容器内の飲料物を飲むことができる。また容器を冷凍庫に入れて内容物を凍らせて運搬する場合でも、容器表面に結露水が発生するのを防止できる。さらに容器を直接熱水や冷水に入れて加温または冷却する場合でも、容器表面がフィルムであるために水切れがよく、その取扱性が向上する。
【００２１】
例えば、夏の暑い季節に、お茶、ジュース、コーヒー、紅茶、水などを冷たい状態で飲料する目的で飲料容器を冷蔵庫、冷凍庫、冷却水などに入れて冷却した容器を取り出すとき、または冬の寒い季節に、お茶、コーヒー、紅茶、水などを温かい状態で飲料する目的で飲料容器を加温機、加熱器、熱水などに入れて加温した容器を取り出すとき、該容器を素手で手に持つことができ、また水切れもよいため、その取扱が容易になる。
【００２２】
【実施例】
以下、本発明を実施例により具体的に説明するが、本発明はこれらに限定されるものではない。また例中の特性は、下記の方法で測定した。
１）目付（ｇ／ｍ²）：縦２０ｃｍ×横２５ｃｍの試料を３カ所から切り取り、その重量を測定し、その平均値を単位当たりの質量に換算して求める。
２）平均繊維径（μｍ）：顕微鏡で５０0 倍の拡大写真を取り、１０本の平均値で求める。
３）平均見かけ密度（ｇ／ｃｍ³)：目付と荷重１０ｋＰａの厚みから単位容積当たりの重量を求め３カ所の平均で求める。
４）厚み（ｍｍ）：荷重１０ｋＰａの厚みを３カ所以上測定して、平均値で求める。
５）収縮率（％）：ＪＩＳ−Ｌ−１９０６湿熱収縮率に準じる。試料２５ｃｍを切り取り、沸騰水中に３分浸漬し、軽く水をふきとり、縦と横の寸法を測定して求める。
【００２３】
６）引張強度（Ｎ／５ｃｍ）：ＪＩＳ−Ｌ−１９０６引張強度に準じる。
７）引裂強度（Ｎ）：ＪＩＳ−Ｌ−１９０６引裂強度（ペンジュラム法）に準じる。
８）断熱性：被覆構造体に８０℃に温めた熱湯を入れ、これを手で直に持って被覆構造体の断熱性を下記のように評価した。
○…８０℃の熱湯を入れた被覆構造体を５分以上手でもつことができる。
△…８０℃の熱湯を入れた被覆構造体を１〜５分間手でもつことができる。
×…８０℃の熱湯を入れた被覆構造体を１分間手にもつことができない。
９）密着包装性：構造体に被覆された包装材を手で移動させることができるかどうかを調べ、下記のように評価した。
○…包装材を手で移動できない程度に密着している。
×…包装材を手で移動させることができ、しかも表面に凹凸があり、密着していない。
【００２４】
１０）意匠性：熱収縮性複合シートのフィルム面に予め文字を印刷し、この複合シートを用いて被覆構造体を製造し、フィルム面の印刷文字およびしわ等の発生を目視で観察し、以下のように評価した。
○…印刷文字の変形が少なく、しわ、凹凸などがなく、外観が良好である。
×…印刷文字が変形し、シワ、凹凸などが発生しており、外観が悪い。
１１）結露防止性：被覆構造体に２℃の冷水を入れた後、２０℃の恒温室に３０分間放置し、被複構造体の表面に生じる結露水の発生状況を目視で観察し、以下のように評価した。
○：容器の表面に結露水が目立たない。
△：容器の表面に結露水が目立たないが、表面が濡れた状態。
×：容器の表面に結露水が多く発生して目立つ状態。
【００２５】
実施例１〜３および比較例１〜２
公知のスパンボンド法でポリプロピレン樹脂（ＭＦＲ３９）を用い、エクスルーダー、ギヤポンプ、紡糸口金を通じ溶融紡糸、延伸、開繊、捕集工程で、繊維径、目付を変え、各種の繊維ウエブを得た。次いでエンボスロールと平滑ロール間を通過させて加熱、加圧して部分熱圧率の異なるポリプロピレン長繊維不織布を得た。
また、熱可塑性合成樹脂フイルムは、ポリエチレン樹脂で、収縮性の横一軸延伸フイルムを公知の方法で、厚みの異なるフイルムを得た。
次いでポリプロピレン長繊維不織布と、収縮性の一軸延伸ポリエチレンフィルムを、ホットメルト系樹脂（ポリプロピレン系樹脂、日立化成ポリマー製ＹＨ１５０−３Ｐ）接着剤を用い、カーテンスプレー方法で塗布量７ｇ／ｍ²で、接合させて熱収縮性複合シートを得た。得られた不織布層、フィルム層および複合シートのそれぞれの特性を表１に示した。
次いで、得られた各熱収縮性複合シートを用いてアルミ製缶（直径７３ｍｍ、高さ１６０ｍｍ）を収縮包装した。まず、熱収縮性複合シートの不織布を内側とし、円周方向が収縮するようにして缶の円周より５〜３０ｍｍ大きめに切り取り（縦１００ｃｍ、横２４０ｃｍ）に切り取り、円周方向の両端部を５ｍｍ重ね、幅２ｍｍの熱シールバーを１５０℃に加熱して接合し、筒形状の収縮包装材を形成し、これをアルミ製缶に被せ、1 ２０℃の加熱ゾーンを６秒で通過させて収縮包装して被覆構造体を得た。なお、上記複合シートのフィルム面には予めグラビア印刷により文字印刷を行った。
【００２６】
【表１】

【００２７】
表１から、本発明の被覆構造体は意匠性、密着包装性、断熱性、強度、結露防止性に優れることが確認された。これに対し、比較例１では、不織布の厚みおよび目付が大きく、かつ複合シートの不織布の比率が多いため、フィルムの収縮性が不足し、密着包装性、意匠性が不足し、さらに密着されていない容器表面から結露が生じ、結露防止性に劣るものであった。また比較例２では、フイルムのみで包装したため、断熱性不足し、加熱した容器では手で持つことができず、結露防止性も得られなかった。
【００２８】
実施例４
実施例３において、収縮性の一軸延伸ポリエチレンフィルムの代わりに、収縮性ポリエステルフィルムを用いた以外は実施例３と同様にして被覆構造体を製造し、その特性を調べ、その結果を表２に示した。
比較例３
実施例１において、熱収縮性複合シートをフィルム面が内側になるように筒状体を形成した以外は実施例１と同様にして被覆構造体を製造し、その特性を調べ、その結果を表２に示した。
【００２９】
【表２】

【００３０】
表２から、ポリエステルフィルムを用いた場合または不織布層の潜在熱収縮率を大きくした場合（実施例４）でも被覆構造体の意匠性、密着包装性、断熱性、強度、結露防止性に優れることが確認された。これに対し、比較例３では不織布層が被覆構造体の外側に存在するため、表示ラベルの印刷文字が不鮮明で見えにくく、意匠性に劣り、断熱性および結露防止性に劣っていた。
また比較例３で得られた被複構造体の収縮包装材の表面を消しゴムで５回ほど擦ったところ、表面の不織布層に毛羽が多く発生し、印刷文字が不鮮明になり、表面耐摩耗性に劣るものであった。またこの被覆構造体を熱水に入れて取り出したが、外側の不織布層内に熱水が内包され、水切れが悪く、その取扱性に劣るものであった。これに対し、実施例４の本発明の被覆構造体では、外側の表面がフィルム層であるため、毛羽の発生は生じることはなく、さらに水切れがよく、その取扱いが容易であった。
【００３１】
【発明の効果】
本発明の被覆構造体およびその製造方法によれば、熱収縮性複合シートの密着包装性および表面保護性に優れるとともに、容器表面とフィルムの間に存在する不織布内に空気層を効率よく閉じ込めることができ、かつフィルムの収縮によるシワの発生をも効率よく防止でき、さらに外側に位置するフィルム面への印刷が容易であるため、被覆構造体の意匠性、断熱性、結露防止性、耐表面摩耗性および取扱性を大幅に向上させることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention covers a structure, related to the manufacture how, more particularly metal, plastic, an outer surface of a container made of glass coated with heat-shrinkable composite sheet, adhesion, thermal insulation, dew condensation-preventing property and design The present invention relates to a covering structure excellent in property and the like, and a manufacturing method thereof .
[0002]
[Prior art]
Shrinkable films are used as packaging materials to improve impact resistance in glass, cans, plastics and other beverage containers containing tea, tea, coffee, liquor and the like. However, the shrinkable film can easily follow the shape of various containers and can be packaged. However, it is easy to damage the protrusions, and if the contents are heated in the container, the container can be held by hand. There were problems such as difficulty.
In order to improve such a problem, a method of packaging a container with a shrinkable nonwoven fabric has been proposed (see, for example, Patent Document 1). However, the strength as a packaging material and the heat insulation of the heating container are superior to the case of using a film, but there is a problem that the packaging material cannot be fixed to the container because of poor adhesion to the container.
[0003]
Further, a shrinkable packaging material in which a non-heat-shrinkable nonwoven fabric and a sealant film made of a heat-shrinkable polyethylene film are laminated has been proposed (for example, see Patent Document 2). However, since this shrinkable packaging material is coated and wrapped with the polyethylene film surface in close contact with the container and the nonwoven fabric on the outside, it is difficult to make the inner film surface follow the shape of the container, and it is difficult to cause uneven wrinkles when shrinking. The appearance shape is inferior, and the non-woven fabric is outside the container, so the printability is poor, the printed display characters are unclear, the design of the container cannot be improved, and the container is difficult to slip. There was a problem. Further, a shrinkable composite sheet in which a polyester long fiber nonwoven fabric having a heat shrinkage rate of 10% or more and a thermoplastic film are laminated has been proposed (for example, see Patent Document 3). However, in this case as well, there is a problem similar to the above because the film surface of the shrinkable composite sheet is thermally contracted so as to be in close contact with the outer surface of the container.
[0004]
Covering and wrapping a thin, low-weight nonwoven fabric on the outside of the container as described above, the gap between the nonwoven fabric becomes large and the heat insulation effect is low, and the heated container cannot be directly held by hand, When the container is cooled, there is a problem that condensed water is easily generated. In particular, when a container containing beverages such as juice and tea is cooled in the refrigerator and carried outside, there is a problem that the surface of the beverage container gets wet due to condensation and the bag containing the container gets wet. Furthermore, since the non-woven fabric is on the outside, there is a problem that the surface is easily fluffed, and fluff is particularly likely to occur due to collision between containers on the production line. In addition, when the coated container is heated or cooled in hot or cold water, the nonwoven fabric on the surface of the container deteriorates the water, resulting in poor handling properties.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 61-21364 [Patent Document 2]
Japanese Patent Publication No. 4-7700 [Patent Document 3]
Japanese Patent Publication No. 8-11432 [0006]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems of the prior art, and in addition to close-packaging and surface protection properties, in particular, a coated structure excellent in heat insulation, anti-condensation, design, surface wear resistance and handleability And a method of manufacturing the same.
[0007]
[Means for Solving the Problems]
As a result of intensive studies on the above problems, the present inventors coated a heat-shrinkable composite sheet in which a specific nonwoven fabric and a film are partially bonded to a structure such as a container having an arbitrary shape with the film side facing outward. By making it heat shrink, it is possible to efficiently confine the air layer in the non-woven fabric existing between the container surface and the film, and it is possible to efficiently prevent wrinkles due to film shrinkage. It has been found that not only the surface protective properties but also the design properties, heat insulation properties, anti-condensation properties, surface wear resistance and handling properties can be greatly improved, and the present invention has been achieved.
The invention claimed in the present application in order to achieve the above object is as follows.
[0008]
(1) thickness of 0.05 to 0.3 mm, a basis weight of 10 to 50 g / m ^2, an average apparent density of 0.05 to 0.3 g / cm ^3, partial thermocompression bonding rate Ri 3% to 30% der, A thickness obtained by bonding a polyolefin-based fiber spunbonded nonwoven fabric having a latent shrinkage of 6% or less and a thermoplastic synthetic resin film having a thickness of 0.02 to 0.1 mm and a latent shrinkage of 10% or more with an adhesive. Is a heat-shrinkable composite sheet having a shrinkage rate of 10 to 60% in at least one direction at 80 to 180 ° C. and a structure having an arbitrary shape covered with the heat-shrinkable composite sheet A covering structure having excellent heat insulation and anti-condensation properties , wherein the thermoplastic synthetic fiber nonwoven fabric is in close contact with the outer surface of the structure.
(2) thickness of 0.05 to 0.3 mm, a basis weight of 10 to 50 g / m ^2, an average apparent density of 0.05 to 0.3 g / cm ^3, partial thermocompression bonding rate Ri 3% to 30% der, A thickness obtained by bonding a polyolefin-based fiber spunbonded nonwoven fabric having a latent shrinkage of 6% or less and a thermoplastic synthetic resin film having a thickness of 0.02 to 0.1 mm and a latent shrinkage of 10% or more with an adhesive. Using a heat-shrinkable composite sheet having a shrinkage ratio of 10 to 60% in at least one direction at 80 to 180 ° C. with a thickness of 0.1 to 0.4 mm, so that the thermoplastic synthetic resin film is on the outside After inserting at least a part of a metal container, plastic container or glass container having an arbitrary shape into the cylindrical body, covering the outer surface, and heating to a temperature of 80 ° C. or higher Heat shrink the cylindrical body Method for producing a coated structure, characterized in that for adhering the polyolefin fiber nonwoven fabric on the outer surface of the container.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The covering structure in the present invention includes a heat-shrinkable composite sheet obtained by joining a thermoplastic synthetic fiber nonwoven fabric and a thermoplastic synthetic resin film, which will be described later, with an adhesive, and a structure having an arbitrary shape included in the heat-shrinkable composite sheet. And the thermoplastic synthetic fiber nonwoven fabric is in close contact with the outer surface of the structure.
As described above, the coated structure of the present invention has a surface covered with a thermoplastic synthetic resin film, and a non-woven fabric having a large number of air layers between the structure and the film, thus ensuring an excellent heat insulating effect. be able to. In addition, since the surface is covered with a film, it is excellent in printability, has excellent design properties, can prevent surface fluff due to collision between containers in a production line, etc. Even when placed in cold water, it has good drainage and is easy to handle.
[0011]
The thermoplastic synthetic fiber nonwoven fabric used in the present invention has a thickness of 0.05 to 0.3 mm, preferably 0.07 to 0.25 mm, more preferably 0.1 to 0.20 mm, and a basis weight of 10 to 50 g. / M ² , preferably 12 to 40 g / m ² , more preferably 14 to 30 g / m ² .
When the thickness of the thermoplastic synthetic fiber nonwoven fabric is less than 0.05 mm, the adhesive packaging property is improved, but the thickness is thin, the air layer is reduced, the heat insulating effect is insufficient, and the strength and the protective effect are further reduced. On the other hand, if the thickness exceeds 0.3 mm, the thickness increases and the air layer increases, so that the heat insulating effect and the protective effect are improved, but the close-packaging property is lowered. Further, since the outer diameter of the coated container is increased, the existing production line cannot be used. Further, when the basis weight of the thermoplastic synthetic fiber nonwoven fabric is less than 10 g / m ² , the thickness becomes thin, but the strength is insufficient and the protective effect as a packaging material is lowered. On the other hand, if the basis weight exceeds 50 g / m ² , the strength increases, but the thickness increases and the flexibility is insufficient.
[0012]
The synthetic fibers used in the thermoplastic synthetic fibrous nonwoven fabric, polyethylene, polypropylene, polyolefin-based textiles such as copolymerized polypropylene. These mixtures alone or two or more may be laminated. Nonwoven fabric using these fibers, the long-fiber nonwoven fabric is partially thermocompression bonding obtained by scan Panbondo method is preferable in terms of thickness and strength.
[0013]
It is preferable that the thermoplastic synthetic fiber non-woven fabric has a smaller apparent fiber density, strength such as tear strength and tensile strength, and excellent flexibility.
Specifically, the average apparent density of the thermoplastic synthetic fiber nonwoven fabric is preferably in the range of 0.05 to 0.3 g / cm ³ , more preferably 0.1 to 0.25 g / cm ³ from the viewpoint of improving the heat insulating effect. It is. Apparent density may not strength is obtained is less than 0.05 g / cm ^3, the fiber ratio increases exceeds 0.3 g / cm ^3, the heat insulating effect is reduced, there is a case where flexibility is insufficient.
Moreover, 1-40 micrometers is preferable and, as for the average fiber diameter of a thermoplastic synthetic fiber nonwoven fabric, 3-30 micrometers is more preferable. If the average fiber diameter is less than 1 μm, the strength may be insufficient and the protective properties as a packaging material may not be obtained, and if it exceeds 40 μm, the flexibility may be insufficient.
[0014]
Moreover, it is preferable that the thermoplastic synthetic fiber nonwoven fabric is partially thermocompression bonded, and the partial thermocompression bonding rate is preferably 3 to 30%, more preferably 5 to 25%. When the partial thermocompression bonding rate is less than 3%, the bonding area decreases and the strength tends to be insufficient. When it exceeds 30%, the bonding area increases and the strength increases, but flexibility may be insufficient. In addition, it is possible to hold more air layers in the partially crimped portion by performing partial thermocompression bonding.
Furthermore, the latent shrinkage of the thermoplastic synthetic fiber nonwoven fabric is preferably 6 % or less. If the latent shrinkage of the thermoplastic synthetic fiber nonwoven fabric exceeds 9.5%, the thickness of the nonwoven fabric after shrinkage tends to be large and bulky, and wrinkles and irregularities are likely to occur during shrinkage, and the appearance is liable to deteriorate. . When the non-woven fabric has a latent shrinkage of 9.5% or less, the presence of fiber spaces in the non-woven fabric makes it easier for the non-woven fabric to follow the shrinkage of the film, so it is easy to suppress the occurrence of wrinkles and irregularities on the film surface. Become.
[0015]
The thermoplastic synthetic resin film used in the present invention has a thickness of 0.02 to 0.1 mm, preferably 0.03 to 0.08 mm, and a latent shrinkage of 10% or more, preferably 10 to 70%, more preferably. Needs to be 20 to 60%, particularly preferably 30 to 55%. If the thickness of the film is less than 0.02 mm, the shrinkage force becomes small and adhesion packaging becomes difficult. If the thickness exceeds 0.1 mm, the shrinkage force becomes large, but the flexibility is inferior and the followability to the container shape is inferior. Moreover, if the latent shrinkage rate of the film is less than 10%, the tight packaging property with respect to the container is lowered.
As the thermoplastic synthetic resin film, a film made of a polyolefin resin such as polyethylene, polypropylene, copolymer polyethylene, or copolymer polypropylene, a polyvinyl chloride resin, a polyester resin, or a polystyrene resin is used. Is preferable in terms of heat resistance, workability, and the like. A thermoplastic synthetic resin film can be a uniaxially stretched film that contracts in only one of the longitudinal and lateral directions or a biaxial that contracts in both the longitudinal and lateral directions if the latent shrinkage is 10% or more. It may be a stretched film.
[0016]
The heat-shrinkable composite sheet used in the present invention is obtained by joining the above-mentioned thermoplastic synthetic fiber nonwoven fabric and a thermoplastic synthetic resin film with an adhesive. The heat-shrinkable composite sheet has a thickness of 0.1 to 0.4 mm, preferably 0.13 to 0.3 mm, more preferably 0.15 to 0.25 mm, and at least one at 80 to 180 ° C. The shrinkage rate is 10 to 60%, preferably 20 to 50%, more preferably 25 to 45%.
When the thickness of the heat-shrinkable composite sheet is less than 0.1 mm, the thickness is thin and the flexibility, adhesion workability, and the like are good, but the heat-shrinkability is insufficient. Moreover, when thickness exceeds 0.4 mm, heat insulation will become favorable, but a softness | flexibility and close_contact | adherence workability will be insufficient. Further, if the shrinkage rate of the heat-shrinkable composite sheet is 80% to 180 ° C. and the shrinkage rate in at least one direction is less than 10%, the followability to the unevenness of the container is insufficient, and if it exceeds 60%, the followability to the unevenness of the container is improved. However, when printing is performed on the film surface, the printed characters and the like are deformed by the shrinkage of the film, and the design properties are lowered.
[0017]
Thermoplastic synthetic fiber nonwoven fabric and thermoplastic synthetic resin film need to be joined so that the nonwoven fabric can be united and heat-shrinkable without peeling when the film shrinks. An adhesive can be applied to one of the nonwoven fabric or the thermoplastic synthetic resin film, preferably in an application amount of ^{2 to} 15% g / m ² . A more preferable coating amount of the adhesive is 4 to 12 g / m ² . As the adhesive, one-pack type or two-pack type urethane resin, acrylic resin, polyolefin resin, polyamide resin, polyester resin, hot melt resin and the like are preferably used. There is no particular limitation on the bonding method, and for example, a wet laminating method, a dry laminating method, an extrusion laminating method, or a curtain spray method in which a hot melt resin is heated and melted together with hot air can be used.
[0018]
In the present invention, the weight ratio of the thermoplastic synthetic fiber nonwoven fabric to the thermoplastic synthetic resin film (thermoplastic synthetic fiber nonwoven fabric: thermoplastic synthetic resin film) is preferably 10-50: 90-50, more preferably 20-45: 80. ~ 55. If the weight ratio of the thermoplastic synthetic fiber nonwoven fabric is less than 10%, the film ratio increases and the close-packing property improves, but the nonwoven fabric ratio decreases and the heat insulation may not be obtained. On the other hand, if it exceeds 50%, the ratio of non-woven fabric will increase and the heat insulation will improve, but the ratio of film will be small, the shrinkage force will be insufficient when shrink wrapping, wrinkles and irregularities are likely to occur, and close packaging is not possible There is.
[0019]
The covering structure in the present invention is, for example, a metal container in which the heat-shrinkable composite sheet is formed into a cylindrical body by heat sealing or the like so that the thermoplastic synthetic resin film is on the outside, and the cylindrical body has an arbitrary shape. Then, after covering at least a part of the outer surface of the structure such as a plastic container or glass container, the cylindrical body is heated for several seconds to several tens of seconds with hot air or heated steam having a temperature of 80 to 180 ° C. or higher. It can be obtained by heat shrinking. The outer peripheral portions of various containers are covered and covered in a container shape by shrinkage of the heat-shrinkable composite sheet.
When using a heat-shrinkable composite sheet to make a cylindrical body, the direction of shrinkage due to heat should be at least the circumferential direction. The height direction of the container is preferable in terms of adhesion and design. The cylindrical body can be obtained by superimposing both end portions of the heat-shrinkable composite sheet and bonding them with a heat seal or the like.
[0020]
The covering structure that put the present invention has excellent film surface printability because that is the outside of the container, previously characters printed on the film surface, trademarks, pictures, of the container by previously printing and picture Designability etc. can be improved significantly. In addition, since the nonwoven fabric layer exists between the film layer and the container, good adhesion following the shape of the container is obtained, and a thin nonwoven fabric containing more air layers between the film surface and the container. Therefore, even if the container is heated or cooled, it is possible to drink the beverage in the container by directly holding the container. Even when the container is placed in a freezer and the contents are frozen and transported, it is possible to prevent the formation of condensed water on the surface of the container. Further, even when the container is directly heated or cooled in hot water or cold water, the container surface is a film, so that the water is easily drained, and the handleability is improved.
[0021]
For example, in the hot summer season, when drinking beverage containers in refrigerators, freezers, cooling water, etc. for the purpose of drinking tea, juice, coffee, tea, water, etc. in a cold state, or when the winter is cold In the season, when you take out a heated container in a warming machine, heater, hot water, etc. for the purpose of drinking tea, coffee, tea, water, etc. in a hot state, take the container with your bare hands. Since it can be held and the drainage is good, the handling becomes easy.
[0022]
【Example】
Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. The characteristics in the examples were measured by the following methods.
1) Weight per unit area (g / m ² ): Samples of 20 cm long × 25 cm wide are cut out from three locations, their weights are measured, and the average value is calculated by converting to mass per unit.
2) Average fiber diameter (μm): Take an enlarged photograph of 500 times with a microscope and obtain the average value of 10 fibers.
3) Average apparent density (g / cm ³ ): The weight per unit volume is obtained from the basis weight and the thickness of the load of 10 kPa, and the average is obtained at three locations.
4) Thickness (mm): Three or more thicknesses with a load of 10 kPa are measured, and the average value is obtained.
5) Shrinkage rate (%): Conforms to JIS-L-1906 wet heat shrinkage rate. A 25 cm sample is cut out, immersed in boiling water for 3 minutes, lightly wiped off, and the vertical and horizontal dimensions are measured.
[0023]
6) Tensile strength (N / 5 cm): Conforms to JIS-L-1906 tensile strength.
7) Tear strength (N): according to JIS-L-1906 tear strength (pendulum method).
8) Thermal insulation: Hot water heated to 80 ° C. was put into the coating structure, and this was directly held by hand to evaluate the thermal insulation of the coating structure as follows.
○: A covering structure containing hot water at 80 ° C. can be held by hand for 5 minutes or longer.
Δ: A covering structure containing hot water at 80 ° C. can be held by hand for 1 to 5 minutes.
X: The covering structure containing hot water at 80 ° C. cannot be held in one hand.
9) Adhesive packaging property: Whether or not the packaging material coated on the structure can be moved by hand was examined and evaluated as follows.
○: The packing material is in close contact with the hand so that it cannot be moved by hand.
X: The packaging material can be moved by hand, and the surface has irregularities and is not in close contact.
[0024]
10) Designability: Characters are printed in advance on the film surface of the heat-shrinkable composite sheet, a coated structure is produced using this composite sheet, and the occurrence of printed characters and wrinkles on the film surface is visually observed. It was evaluated as follows.
○: Little deformation of printed characters, no wrinkles, irregularities, etc., and good appearance.
X: Printed characters are deformed, wrinkles, irregularities are generated, and the appearance is poor.
11) Anti-condensation property: After putting cold water at 2 ° C into the coated structure, leave it in a constant temperature room at 20 ° C for 30 minutes, and visually observe the occurrence of condensed water on the surface of the composite structure. It was evaluated as follows.
○: Condensed water is not noticeable on the surface of the container.
Δ: Condensed water is not noticeable on the surface of the container, but the surface is wet.
X: A conspicuous state with a lot of condensed water generated on the surface of the container.
[0025]
Examples 1-3 and Comparative Examples 1-2
Polypropylene resin (MFR39) was used by a known spunbonding method, and various fiber webs were obtained by changing the fiber diameter and basis weight in the melt spinning, drawing, fiber opening, and collecting steps through an extruder, gear pump, and spinneret. Subsequently, it passed between the embossing roll and the smooth roll, and heated and pressurized to obtain polypropylene long fiber nonwoven fabrics having different partial heat pressure ratios.
Further, the thermoplastic synthetic resin film was a polyethylene resin, and a shrinkable lateral uniaxially stretched film was obtained by a known method to obtain films having different thicknesses.
Next, a polypropylene long fiber nonwoven fabric and a shrinkable uniaxially stretched polyethylene film are coated with a hot melt resin (polypropylene resin, YH150-3P manufactured by Hitachi Chemical Polymer) with a coating amount of 7 g / m ² by a curtain spray method. A heat-shrinkable composite sheet was obtained by bonding. Table 1 shows the characteristics of the obtained nonwoven fabric layer, film layer, and composite sheet.
Next, aluminum cans (diameter 73 mm, height 160 mm) were shrink-wrapped using the obtained heat-shrinkable composite sheets. First, the nonwoven fabric of heat-shrinkable composite sheet is inside, and the circumferential direction shrinks so that it is 5-30 mm larger than the circumference of the can (length 100 cm, width 240 cm), and both ends in the circumferential direction are cut off. A heat seal bar of 5 mm in width and 2 mm in width is heated to 150 ° C. and joined to form a cylindrical shrink wrapping material, which is covered with an aluminum can and passed through a 120 ° C. heating zone in 6 seconds. The coated structure was obtained by shrink wrapping. The film surface of the composite sheet was previously printed by gravure printing.
[0026]
[Table 1]

[0027]
From Table 1, it was confirmed that the coating structure of the present invention is excellent in design properties, adhesive packaging properties, heat insulation properties, strength, and dew condensation prevention properties. On the other hand, in Comparative Example 1, since the nonwoven fabric has a large thickness and basis weight, and the ratio of the nonwoven fabric of the composite sheet is large, the shrinkage of the film is insufficient, the close-packaging property and the design property are insufficient, and the contact is further achieved. Condensation occurred from the surface of the container which was not, and the anti-condensation property was poor. Further, in Comparative Example 2, since the film was wrapped only with the film, the heat insulation was insufficient, the heated container could not be held by hand, and the anti-condensation property was not obtained.
[0028]
Example 4
In Example 3, a coated structure was produced in the same manner as in Example 3 except that a shrinkable polyester film was used instead of the shrinkable uniaxially stretched polyethylene film. The characteristics were examined, and the results are shown in Table 2. Indicated.
Comparative Example 3
In Example 1, a coated structure was produced in the same manner as in Example 1 except that the heat-shrinkable composite sheet was formed into a cylindrical body so that the film surface was on the inside. It was shown in 2.
[0029]
[Table 2]

[0030]
From Table 2, when the polyester film is used or the latent heat shrinkage rate of the nonwoven fabric layer is increased (Example 4) , the covering structure has excellent design properties, adhesive packaging properties, heat insulation properties, strength, and anti-condensation properties. Was confirmed. On the other hand, in Comparative Example 3, since the nonwoven fabric layer was present outside the covering structure, the printed characters on the display label were unclear and difficult to see, and the design was inferior, and the heat insulation and dew condensation prevention properties were inferior.
In addition, when the surface of the shrink wrapping material of the composite structure obtained in Comparative Example 3 was rubbed with an eraser about 5 times, a lot of fuzz was generated on the nonwoven fabric layer on the surface, the printed characters became unclear, and the surface abrasion resistance It was inferior to. Further, this covering structure was taken out in hot water, but the hot water was included in the outer nonwoven fabric layer, the water drainage was poor, and the handling property was inferior. On the other hand, in the coating structure of the present invention of Example 4, since the outer surface was a film layer, the generation of fluff did not occur, the water was well drained, and the handling was easy.
[0031]
【The invention's effect】
According to the covering structure of the present invention and the method for producing the same, the heat-shrinkable composite sheet is excellent in the adhesion packaging property and the surface protection property, and the air layer is efficiently trapped in the nonwoven fabric existing between the container surface and the film. Can be effectively prevented from wrinkling due to shrinkage of the film, and it is easy to print on the film surface located on the outside, so the design, heat insulation, anti-condensation, surface resistance of the coated structure Wearability and handleability can be greatly improved.

Claims

The thickness is 0.05 to 0.3 mm, the basis weight is 10 to 50 g / m ² , the average apparent density is 0.05 to 0.3 g / cm ³ , the partial thermocompression bonding rate is 3 to 30%, and the potential shrinkage rate is Polyolefin fiber spunbonded nonwoven fabric having a thickness of 6% or less, and a thermoplastic synthetic resin film having a thickness of 0.02 to 0.1 mm and a latent shrinkage of 10% or more, joined with an adhesive, having a thickness of 0.1 A heat-shrinkable composite sheet having a shrinkage rate of 10 to 60% in at least one direction at 80 to 180 ° C. at −0.4 mm and a structure having an arbitrary shape covered with the heat-shrinkable composite sheet A covering structure having excellent heat insulation and anti-condensation properties, wherein the thermoplastic synthetic fiber nonwoven fabric is in close contact with the outer surface of the structure.

The thickness is 0.05 to 0.3 mm, the basis weight is 10 to 50 g / m ² , the average apparent density is 0.05 to 0.3 g / cm ³ , the partial thermocompression bonding rate is 3 to 30%, and the potential shrinkage rate is Polyolefin fiber spunbonded nonwoven fabric having a thickness of 6% or less, and a thermoplastic synthetic resin film having a thickness of 0.02 to 0.1 mm and a latent shrinkage of 10% or more, joined with an adhesive, having a thickness of 0.1 Using a heat-shrinkable composite sheet having a shrinkage rate of 10 to 60% in at least one direction at 80 to 180 ° C. at −0.4 mm, a tubular body is formed so that the thermoplastic synthetic resin film is on the outside, After inserting at least a part of a metal container, plastic container or glass container having an arbitrary shape into the cylindrical body, covering its outer surface, the cylindrical body is heated to a temperature of 80 ° C. or higher. Heat shrink Method for producing a coated structure, characterized in that for adhering the polyolefin fiber nonwoven fabric on the outer surface of the vessel.