JP4522562B2 - Packaging materials and containers - Google Patents

Packaging materials and containers Download PDF

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Publication number
JP4522562B2
JP4522562B2 JP2000276337A JP2000276337A JP4522562B2 JP 4522562 B2 JP4522562 B2 JP 4522562B2 JP 2000276337 A JP2000276337 A JP 2000276337A JP 2000276337 A JP2000276337 A JP 2000276337A JP 4522562 B2 JP4522562 B2 JP 4522562B2
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layer
melting point
packaging material
paper
peel
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JP2001158064A (en
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秀明 高橋
康晴 杉山
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Dai Nippon Printing Co Ltd
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Dai Nippon Printing Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/14—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers
    • B32B37/15—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state
    • B32B37/153—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the properties of the layers with at least one layer being manufactured and immediately laminated before reaching its stable state, e.g. in which a layer is extruded and laminated while in semi-molten state at least one layer is extruded and immediately laminated while in semi-molten state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D1/00—Rigid or semi-rigid containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material or by deep-drawing operations performed on sheet material
    • B65D1/22—Boxes or like containers with side walls of substantial depth for enclosing contents
    • B65D1/26—Thin-walled containers, e.g. formed by deep-drawing operations
    • B65D1/28—Thin-walled containers, e.g. formed by deep-drawing operations formed of laminated material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
    • B65D77/10—Container closures formed after filling
    • B65D77/20—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers
    • B65D77/2024—Container closures formed after filling by applying separate lids or covers, i.e. flexible membrane or foil-like covers the cover being welded or adhered to the container
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2323/00—Polyalkenes
    • B32B2323/04—Polyethylene
    • B32B2323/046—LDPE, i.e. low density polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2435/00—Closures, end caps, stoppers
    • B32B2435/02—Closures, end caps, stoppers for containers

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Ceramic Engineering (AREA)
  • Laminated Bodies (AREA)
  • Wrappers (AREA)
  • Packages (AREA)
  • Closures For Containers (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、包装材料及び容器に関する。
【０００２】
【従来の技術】
イージーピール性を有する易開封包装材料は、剥離機構の違いによって界面剥離タイプ、層間剥離タイプ、凝集剥離タイプに大別される。これらの中でも凝集剥離タイプの材料は、ピール層樹脂が開封時に内部凝集破壊を生ずることによりイージーピール性を発現するものである。凝集剥離タイプの材料としては、ワックスや粘結材をブレンドしたＥＶＡ系材料や、ポリオレフイン／ポリスチレン系、ポリエチレン／ポリプロピレン系などの非相溶ポリマーアロイが知られており、ピール強度のシール温度安定性、夾雑物シール性、耐内容物性に優れているという特徴がある。ここで「夾雑物シール性に優れる」とは、ヒートシール材料に比較的大きな粒子サイズを有する夾雑物が混入している場合でも良好なヒートシール性能を示すことを言う。
【０００３】
【発明が解決しようとする課題】
しかし、凝集破壊タイプに属する従来の易開封材料は、開封時のシール剥離面にピール層樹脂が繊維伏に残存する、いわゆる「糸ひき現象」を生じ易いという問題がある。また、ピール強度のコントロールが難しいため、ポリエチレンコート紙を被着体とするような場合には、剥離強度が強すぎるため被着体の紙が破壊する、いわゆる「紙剥け現象」を生じやすいという問題もある。
【０００４】
さらに、従来の易開封材料を押出ラミネート法などにより紙、フィルム、金属箔などの基材に積層した場合、得られた易開封包装材料はカールを生じやすいため、蓋材として容器にヒートシールするときの供給・ハンドリングにトラブルを生じることが多いという問題もある。
【０００５】
本発明の課題は、密封容器のヒートシール部をピールして開封する容器の分野において、カールが少なくて、開封時に糸ひきがなく、易開封性を示す包装材料及び容器を提供することである。
【０００６】
【課題を解決するための手段】
本発明に係る易開封包装材料は、少なくとも、基材と当該基材の一面側に設けられたヒートシール層とからなり、前記ヒートシール層は、前記基材に近い側からエチレン−不飽和カルボン酸共重合体よりなる樹脂層（Ｂ）と、低密度ポリエチレンを５５〜７５重量部とポリブテン−１を４５〜２５重量部の割合で含有する樹脂層（Ａ）を、この順序で設けた積層構造を有すると共に、前記樹脂層（Ａ）と樹脂層（Ｂ）は共押出し法により互いに積層されていることを特徴とする。
【０００７】
また、本発明に係る易開封容器は、包装材料が、融点１０５〜１１５℃のポリエチレンを最内層にコートした紙カップ容器の蓋材としてヒートシールされており、開封時には前記樹脂層（Ａ）が凝集破壊することを特徴とする。
【０００８】
前記樹脂層（Ａ）の厚みが５〜１５μｍの範囲であり、且つ、前記樹脂層（Ｂ）の厚みが樹脂層（Ａ）の厚さ以上であることが好ましい。
【０００９】
また、前記低密度ポリエチレンが融点１１０℃以下の高圧法低密度ポリエチレンであり、且つ、前記ポリブテン−１が融点１２０℃以上のホモポリマーであり、更に、前記エチレン−不飽和カルボン酸共重合体の融点が前記低密度ポリエチレンの融点よりも低いことが好ましい。
【００１０】
また、前記ヒートシール層が共押出ラミネート法により前記基材に積層されていることが好ましい。
【００１１】
【発明の実施の形態】
図１は、本発明の包装材料の層構成の一例を示す模式的な断面図である。図２は、本発明の包装材料の層構成の別の例を示す模式的断面図である。図３は、本発明の包装材料を被着体から剥離する時の状態を説明する概念図であり、（ａ）はヒートシールした状態、（ｂ）はヒートシール部を剥離した状態である。図４は、本発明の包装材料を蓋材として使用した容器の実施例を示しており、（ａ）は容器の斜視図、（ｂ）Ｘ一Ｘ部断面図、（ｃ）シール部の部分断面図、（ｄ）蓋材をピールした時におけるピール部の部分断面図である。
【００１２】
本発明の包装材料１は、図１または図２に示すように、少なくとも基材層３とヒートシール層２とからなり、前記ヒートシール層２が、互いに異なる樹脂を積層することにより形成された少なくとも２層（２Ａ、２Ｂ）から構成されたものである。図１の例は、紙などの基材にヒートシール層を押出コート法により直接製膜するものであり、図２の例は、予めヒートシール層２を製膜しておき、ドライラミネート法などによって接着剤４を用いて、プラスチックフイルムなどの基材と貼合したものである。
【００１３】
基材としては、紙、金属箔、プラスチックフィルムの単体、または、これらが２種以上積層されたものを利用できる。プラスチックフィルムは、シリカやアルミナのような酸化物やアルミニウムのような金属薄膜が形成された蒸着フィルムであってもよい。
【００１４】
本発明の包装材料におけるヒートシール層２は、図１に示すように、低密度ポリエチレンが５５〜７５重量部とポリブテン−１が４５〜２５重量部の割合で混合されている樹脂層２Ａと、エチレン−不飽和カルボン酸共重合体よりなる樹脂層２Ｂが共押出法により接着層を介さずに積層されたものである。前記ヒートシール層２は、基材３とのラミネートにおいて、前記エチレン−不飽和カルボン酸共重合体よりなる樹脂層２Ｂ側を基材側に配置して、積層する。言い変えれば、ヒートシール層２は、樹脂層２Ｂ側を基材に対向させて、積層する。
【００１５】
前記低密度ポリエチレンとポリブテン−１の混合物層２Ａは、開封時に凝集破壊を生じることの可能なピール層を形成する。ポリブテン−１は低密度ポリエチレンと実質的に非相溶であり、これらの混合物は、いわゆる「海島構造」を形成するため、ピール層の凝集力を低下させ、凝集破壊タイプのイージーピール性を発現させることができる。ポリブテンー１の配合比が２５重量％未満ではピール強度が強すぎるため、ポリエチレンコート紙を被着体とする場合、紙剥けを生じる。ポリブテン−１の配合比が４５重量％を超えると、ピール強度が不十分となり、さらに糸ひきが生じやすくなる。
【００１６】
エチレン−不飽和カルボン酸共重合体としては、ＥＭＡＡ（エチレン−メタクリル酸共重合体）、又は、ＥＡＡ（エチレン−アクリル酸共重合体）を用いることができる。エチレン−不飽和カルボン酸共重合体の樹脂層２Ｂをピール層に隣接して設けることにより、開封時におけるピール層の凝集破壊を２Ａ層と２Ｂ層の境目近傍に集中させることができ、ピール強度を安定化し、糸ひきの発生を抑制することができる。また、エチレン−不飽和カルボン酸共重合体の層を設けることにより、ヒートシール層を基材と積層したときのカールを抑制する効果がある。
【００１７】
２Ａ層と２Ｂ層を積層することにより、所定の層比で容易にヒートシール層を形成できる。２Ａ層と２Ｂ層より形成されるヒートシール層２と基材３との積層方法としては、ドライラミネート法、サンドイッチラミネート法、共押出ラミネート法等が利用できる。
【００１８】
ヒートシール層の２Ａ層の厚みが５μｍ未満ではシール強度が不安定となりやすく、夾雑物シールも不十分となる。また、ヒートシール層の２Ａ層の厚みが１５μｍを超えると開封時に糸ひきを生じやすくなる。一方、ヒートシ一ル層を形成する２Ｂ層の厚みが２Ａ層よりも薄い場合、ヒートシール層を基材と積層した時のカールが大きくなり、さらに共押出法による２Ａ層と２Ｂ層の積層加工も困難となる。
【００１９】
ヒートシール層の前記２Ａ層に含有される低密度ポリエチレンの融点が１１０℃を超えると、低温でのヒートシール強度が弱くなり、糸ひきも生じやすくなる。また、エチレンとαオレフィンの共重合体である直鎖状低密度ポリエチレン、いわゆるＬＬＤＰＥを２Ａ層に利用した場合には、シール強度が強くなり紙剥けを生じやすくなる。ヒートシール層の前記２Ａ層に用いる低密度ポリエチレンとしては、密度０．９１５〜０．９２０、ＭＦＲが０．５〜５０、好ましくは２０〜５０の範囲の高圧法低密度ポリエチレンが好適である。
【００２０】
ポリブテン−１の融点が１２０℃未満では、シール強度が強くなり、ピールの際に紙剥けが発生しやすい。ブテン−１を主体とし、当該ブテンー１と他のオレフィンとを共重合させた共重合体を利用した場合は、シール強度が強くなり、紙剥けが生じやすい。ポリブテン−１は、密度が０．９０５〜０．９１７、ＭＦＲが０．２〜２０の範囲のものを用いることが望ましい。
【００２１】
ヒートシール層の２Ｂ層のエチレン−不飽和カルボン酸共重合体としては、ＥＭＡＡ、ＥＡＡを好適に用いることができる。エチレン−不飽和カルボン酸共重合体の融点が前記２Ａ層に用いられる低密度ポリエチレンよりも高い場合には、開封時に糸ひきが発生しやすくなる。ＥＭＡＡは、密度が０．９３０〜０．９４０、ＭＦＲが２〜２０の範囲のものが好適に利用できる。ＥＡＡとしては、密度が０．９２４〜０．９４１、ＭＦＲが２〜２０の範囲のものが好適に利用できる。
【００２２】
以下において、本発明の包装材料を用いた容器の開封について説明する。図３（ａ）に示すように、本発明の包装材料１のヒートシール層を、被着体１０のヒートシール層に対面させて、熱板３０によりヒートシールしてヒートシール部１３を形成する。該ヒートシール部１３を剥離（開封）すると、図３（ｂ）に示すように、ヒートシール層２のブレンド樹脂からなる２Ａ層において凝集破壊１４が発生して易開封性を示し、糸引きのない剥離面が形成される。
【００２３】
ヒートシール層２が積層される基材３が、紙、アルミニウム箔、又は、ポリエチレンのようなプラスチックフィルムの場合には、２Ａ層及び２Ｂ層より構成されるヒートシール層２は、共押出ラミネート法を利用して基材に直接積層することができ、製造工程が簡易となる。
【００２４】
本発明の包装材料は、図４（ａ）に示すように、ポリエチレンコート紙カップ容器２２にヒートシールされる蓋材２１として好適に利用できる。紙容器は、容器本体２２のリップカール部をプレスして平滑なフランジ２３を形成し、当該フランジ部に蓋体２１をヒートシールして密封される。開封時には、蓋体のヒートシールした部分を剥離する。本発明の包装材科を蓋材として用い、開封のためにピールした状態を図（ｄ）に示した。前記紙容器は、即席麺類、ヨーグルト、スナック類、納豆などの食品用として広く用いられている。本発明の包装材料をを当該紙容器の蓋材として用いることにより、ピール面に優れた易開封性を付与することができる共に、紙容器において従来みられた剥離面の糸引きを生じなくすることができた。
【００２５】
【実施例】
次に、本発明の包装材料及び容器について実施例を示して具体的に説明するが、本発明はこれらによって限定されるものではない。
【００２６】
［実施例１］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）３５重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、エチレン−メタクリル酸共重合体（以下において「ＥＭＡＡ」と記載する）（融点９８℃）を第２層（厚さ２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００２７】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００２８】
［実施例２］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（２０μｍ）として、アルミニウム箔（厚さ５０μｍ）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００２９】
アルミニウム箔（５０μｍ）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００３０】
［実施例３］
ＥＭＡＡに替えて、エチレン−アクリル酸共重合体（以下において「ＥＡＡ」と記載する）（融点９６℃）を用い、実施例１と同様に行った。すなわち、低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＡＡ（融点９６℃）を第２層（厚さ２０μｍ）として、ＥＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００３１】
紙（１００ｇ／ｍ2）／ＥＡＡ（２０μｍ）／ピール層（１０μｍ）
【００３２】
［実施例４］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層とし、ＥＭＡＡ（融点９８℃）を第２層として、多層インフレーション成形法によりシーラントフィルムを作成し、このフィルムのＥＭＡＡ側にコロナ処理を施した後、１６μｍ厚のＰＥＴフィルムの一面側に２液硬化型ウレタン系接着剤を用いてドライラミネートを行い、下記構成の包装材料を得た。
【００３３】
ＰＥＴ（１６μｍ）／接着剤層／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００３４】
［実施例５］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（２０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（１０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００３５】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００３６】
［実施例６］
低密度ポリエチレン（融点１１１℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００３７】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００３８】
［実施例７］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１００℃）を３５重量部との混合物をピール層として第１層（１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００３９】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００４０】
［実施例８］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（１０μｍ）とし、ＥＭＡＡ（融点１０５℃）を第２層（２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００４１】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００４２】
［比較例１］
低密度ポリエチレン（融点１０５℃）を８０重量都とポリブテン−１（融点１２５℃）２０重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（厚さ２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００４３】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００４４】
［比較例２］
低密度ポリエチレン（融点１０５℃）を５０重量部とポリブテン−１（融点１２５℃）を５０重量部との混合物をピール層として第１層（１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００４５】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００４６】
［比較例３］
低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、低密度ポリエチレン（ＬＤＰＥ）（融点１０５℃、密度＝０．９２、ＭＦＲ＝７）を第２層（厚さ２０μｍ）として、ＬＤＰＥ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００４７】
紙（１００ｇ／ｍ2）／ＬＤＰＥ（２０μｍ）／ピール層（１０μｍ）
【００４８】
［比較例４］
直鎖状低密度ポリエチレン（以下において「ＬＬＤＰＥ」と記載する）（融点１１０℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（１０μｍ）、ＥＭＡＡ（融点９８℃）を第２層（２０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、コロナ処理を施した紙（１００ｇ／ｍ2）に押し出し温度３００℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００４９】
紙（１００ｇ／ｍ2）／ＥＭＡＡ（２０μｍ）／ピール層（１０μｍ）
【００５０】
＜試験＞
融点１０６℃の低密度ポリエチレンを２０μｍ厚で押出コーティングしたカップ原紙（２８０ｇ／ｍ2）をフランジ部を有するカップ形状に成形し、そのフランジ部に実施例１で作成した包装材料を蓋材として用い、１５０℃、０．６ｓｅｃの条件でヒートシールした後、開封し、剥離面の断面を顕微鏡観察した。蓋材のピール層が蓋材側とカップ側の双方に観察されたため、ピール層が開封時に凝集破壊されたことが確認できた。
【００５１】
また、各実施例及び比較例で作成した包装材料を、融点１０６℃の低密度ポリエチレン（厚さ２０μｍ）が押出コーティングされたカップ原紙（２８０ｇ／ｍ2）に、１４０℃、９８Ｋｐａ、１ｓｅｃの条件でヒートシールし、ピール強度と剥離面の糸ひき状況を比較した。カールについては目視観察で評価した。
【００５２】
実施例および比較例の易開封性及びカールの発生は、次の通りであった。
【００５３】
【表１】

Figure 0004522562
【００５４】
実施例１〜４の包装材料は、適度なピール強度を示し、剥離面の糸引きを引き起こすことなく、カールは小さかった。実施例５の包装材料は、ピール層と比べてＥＭＡＡ層の厚さが若干薄いため、カールが少し目立ち、糸引きもやや多かった。実施例６の包装材料は、低密度ポリエチレンの融点が若干高いため、ピール強度がやや弱く、糸引きもやや多かった。実施例７の包装材料は、ポリブテン−１の融点が若干低いため、ピール強度がやや強かった。実施例８の包装材料は、ＥＭＡＡの融点が若干高く、低密度ポリエチレンの融点と同じであるため、糸引きがやや多く、ピール強度も弱めで、カールも少し目立った。
【００５５】
比較例１の包装材料は、ポリブテン−１の配合割合が少なすぎるので、ピール強度が強すぎて、紙剥けが発生した。比較例２の包装材料は、ポリブテン−１の配合割合が大きすぎるので、ピール強度が弱すぎてしまい、糸引きもやや多かった。比較例３の包装材料は、第２層としてエチレン−不飽和カルボン酸共重合体の代わりに低密度ポリエチレンを用いたので、糸引きが多く、カールも大きかった。比較例４の包装材料は、低密度ポリエチレンの代わりにＬＬＤＰＥを用いたので、ピール強度が強すぎて、紙剥けが発生した。
【００５６】
［実施例９］
〔紙／ポリエチレン／アルミニウム箔〕の層構成を有する基材のアルミニウム箔側に、ウレタン系アンカー剤を介して低密度ポリエチレン（融点１０６℃）を６０重量部とポリブテン−１（融点１２５℃）を４０重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＭＡＡ（融点１００℃）を第２層（厚さ３０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、押し出し温度２６０℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００５７】
〔紙（７６ｇ／ｍ2）／ポリエチレン（２０μｍ）／アルミニウム箔（７μｍ）／ＥＭＡＡ（３０μｍ）／ピール層（１０μｍ）〕
この包装材料を、融点１１０℃のポリエチレンで内面コートされた紙（２８０ｇ／ｍ2）により成形されたインスタントラーメン（即席麺）用紙カップの蓋材として用いたところ、開封時の紙剥けや糸引きは発生せず、密封性と耐熱性に優れた易開封性容器を得ることができた。
【００５８】
［実施例１０］
〔紙／ポリエチレン／アルミニウム箔／ＰＥＴ〕の層構成を有する基材のＰＥＴ側に、ウレタン系アンカー剤を介して低密度ポリエチレン（融点１０５℃）を７０重量部とポリブテン−１（融点１２５℃）を３０重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＭＡＡ（融点９８℃）を第２層（厚さ４０μｍ）として、ＥＭＡＡ層側にオゾン処理を施しながら、押し出し温度２５０℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００５９】
〔紙（７９ｇ／ｍ2）／ポリエチレン（２０μｍ）／アルミニウム箔（７μｍ）／ＰＥＴ（１２μｍ）／ＥＭＡＡ（４０μｍ）／ピール層（１０μｍ）〕
この包装材料を、〔紙（２１０ｇ／ｍ2）／ポリエチレン（２０μｍ）／アルミニウム箔（７μｍ）／ＥＭＡＡ（１０μｍ）／ポリエチレン（２０μｍ）〕
の層構成を有する原紙を用いて成形したスナック菓子用の紙カップの蓋材として用いたところ、開封時の紙剥けや糸引きは発生せず、密封性と耐熱性に優れた易開封性容器を得ることができた。
【００６０】
［実施例１１］
〔ＰＥＴ（１２μｍ）／アルミニウム箔（１０μｍ）〕の層構成を有する基材のアルミニウム箔側に、低密度ポリエチレン（融点１０５℃）を６５重量部とポリブテン−１（融点１２５℃）を３５重量部との混合物をピール層として第１層（厚さ１０μｍ）とし、ＥＭＡＡ（融点１００℃）を第２層（厚さ３５μｍ）として、押し出し温度２９０℃で共押出ラミネートを行い、下記構成の包装材料を得た。
【００６１】
〔ＰＥＴ（１２μｍ）／アルミニウム箔（１０μｍ）ＥＭＡＡ（３５μｍ）／ピール層（１０μｍ）〕
この包装材料を、融点１０７℃のポリエチレンで内面コートされた紙（２４０ｇ／ｍ2）により成形されたヨーグルト用紙カップの蓋材として用いたところ、開封時の紙剥けや糸引きは発生せず、密封性と耐熱性に優れた易開封性容器を得ることができた。
【００６２】
【発明の効果】
本発明の包装材料は、ピール層を含むヒートシール層を有している。この包装材料を用いてヒートシール方式で密封したヒートシール部をピールして開封すると、ピール層において凝集破壊を生じ、易開封性を示す。しかも、開封部の糸引きを発生させない。
【００６３】
そして、この包装材料を、内面がポリエチレンからなる紙カッブの蓋材として用いると、易開封を有する密封の紙カップが得られる。このようにして得られる容器は、消費者にとって極めて使用性がよい。
【図面の簡単な説明】
【図１】木発明の包装材料の層構成の一例を示す模式的断面図である。
【図２】本発明の包装材料の層構成の別の例を示す模式的断面図である。
【図３】本発明の包装材料を被着体から剥離する時の状態を説明する概念図であり、（ａ）はヒートシールした状態、（ｂ）はヒートシール部を剥離した状態である。
【図４】本発明の包装材料を蓋材として使用した容器の一実施例を示しており、（ａ）は容器の斜視図、（ｂ）Ｘ一Ｘ部断面図、（ｃ）シール部の部分断面図、（ｄ）蓋材をピールした時におけるピール部の部分断面図である。
【符号の説明】
１…包装材料
２…ヒートシール層
３…基材
４…接着剤層
１０…被着体
１１…被着体ヒートシール層
１３…ヒートシール部
１４…剥離部
２０…容器
２１…蓋
２２…容器本体
２３…フランジ部
３０…熱板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packaging material and a container.
[0002]
[Prior art]
Easy-open packaging materials having easy peel properties are roughly classified into an interfacial peel type, an interlayer peel type, and an agglomerated peel type depending on the peel mechanism. Among these, the cohesive peeling type material exhibits easy peel properties by causing internal cohesive failure when the peel layer resin is opened. As cohesive peeling type materials, EVA materials blended with wax and binders, and incompatible polymer alloys such as polyolefin / polystyrene and polyethylene / polypropylene are known, and the seal temperature stability of peel strength is known. , It is characterized by excellent contamination sealing and content resistance. Here, “excellent in sealing property of impurities” means that excellent heat sealing performance is exhibited even when impurities having a relatively large particle size are mixed in the heat sealing material.
[0003]
[Problems to be solved by the invention]
However, the conventional easy-opening material belonging to the cohesive failure type has a problem that the peel layer resin remains on the fiber peeling surface on the seal peeling surface at the time of opening, so that a so-called “stringing phenomenon” is likely to occur. In addition, since it is difficult to control the peel strength, when the polyethylene coated paper is used as an adherend, the peel strength is too strong and the paper on the adherend is easily broken, so-called “paper peeling phenomenon” is likely to occur. There is also a problem.
[0004]
Furthermore, when a conventional easy-opening material is laminated on a base material such as paper, film, or metal foil by an extrusion laminating method or the like, the resulting easy-open packaging material is likely to curl, so heat-seal the container as a lid. There is also a problem that troubles often occur in supply and handling.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a packaging material and a container that are easy to open in the field of a container that peels and opens a heat-sealed portion of a sealed container, has little curling, does not have string at the time of opening. .
[0006]
[Means for Solving the Problems]
The easy-open packaging material according to the present invention comprises at least a base material and a heat seal layer provided on one surface side of the base material, and the heat seal layer is an ethylene-unsaturated carboxylic acid from the side close to the base material. A laminate in which an acid copolymer resin layer (B) and a resin layer (A) containing 55 to 75 parts by weight of low density polyethylene and 45 to 25 parts by weight of polybutene-1 are provided in this order. While having a structure, the resin layer (A) and the resin layer (B) are laminated to each other by a co-extrusion method.
[0007]
In the easy-open container according to the present invention, the packaging material is heat-sealed as a cover material of a paper cup container in which polyethylene having a melting point of 105 to 115 ° C. is coated on the innermost layer, and the resin layer (A) is aggregated when opened. It is characterized by destruction.
[0008]
The thickness of the resin layer (A) is preferably in the range of 5 to 15 μm, and the thickness of the resin layer (B) is preferably equal to or greater than the thickness of the resin layer (A).
[0009]
The low-density polyethylene is a high-pressure method low-density polyethylene having a melting point of 110 ° C. or lower, the polybutene-1 is a homopolymer having a melting point of 120 ° C. or higher, and the ethylene-unsaturated carboxylic acid copolymer The melting point is preferably lower than the melting point of the low density polyethylene.
[0010]
Moreover, it is preferable that the said heat seal layer is laminated | stacked on the said base material by the coextrusion lamination method.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the packaging material of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the packaging material of the present invention. FIG. 3 is a conceptual diagram for explaining a state when the packaging material of the present invention is peeled from the adherend, in which (a) is a heat-sealed state and (b) is a state where the heat-sealed part is peeled off. FIG. 4 shows an example of a container using the packaging material of the present invention as a lid, (a) is a perspective view of the container, (b) a cross section of X part X, (c) part of the seal part. It is sectional drawing, (d) It is a fragmentary sectional view of a peel part when a cover material is peeled.
[0012]
As shown in FIG. 1 or 2, the packaging material 1 of the present invention comprises at least a base material layer 3 and a heat seal layer 2, and the heat seal layer 2 is formed by laminating different resins. It is composed of at least two layers (2A, 2B). In the example of FIG. 1, a heat seal layer is directly formed on a substrate such as paper by an extrusion coating method. In the example of FIG. 2, the heat seal layer 2 is formed in advance, and the dry lamination method is used. Is bonded to a substrate such as a plastic film using the adhesive 4.
[0013]
As the substrate, paper, metal foil, a single plastic film, or a laminate of two or more of these can be used. The plastic film may be a deposited film on which an oxide such as silica or alumina or a metal thin film such as aluminum is formed.
[0014]
As shown in FIG. 1, the heat seal layer 2 in the packaging material of the present invention has a resin layer 2A in which low density polyethylene is mixed at a ratio of 55 to 75 parts by weight and polybutene-1 at a ratio of 45 to 25 parts by weight; A resin layer 2B made of an ethylene-unsaturated carboxylic acid copolymer is laminated by a coextrusion method without using an adhesive layer. The heat seal layer 2 is laminated with the resin layer 2B made of the ethylene-unsaturated carboxylic acid copolymer on the substrate side in the laminate with the substrate 3. In other words, the heat seal layer 2 is laminated with the resin layer 2B side facing the substrate.
[0015]
The mixture layer 2A of the low-density polyethylene and polybutene-1 forms a peel layer capable of causing cohesive failure when opened. Polybutene-1 is substantially incompatible with low-density polyethylene, and these mixtures form a so-called “sea-island structure”, thus reducing the cohesive strength of the peel layer and exhibiting an easy peel property of cohesive failure type. Can be made. If the blending ratio of the polybutene 1 is less than 25% by weight, the peel strength is too strong. Therefore, when polyethylene coated paper is used as the adherend, paper peeling occurs. When the compounding ratio of polybutene-1 exceeds 45% by weight, the peel strength becomes insufficient, and stringing tends to occur.
[0016]
As the ethylene-unsaturated carboxylic acid copolymer, EMAA (ethylene-methacrylic acid copolymer) or EAA (ethylene-acrylic acid copolymer) can be used. By providing the ethylene-unsaturated carboxylic acid copolymer resin layer 2B adjacent to the peel layer, the cohesive failure of the peel layer at the time of opening can be concentrated near the boundary between the 2A layer and the 2B layer, and the peel strength Can be prevented and the occurrence of stringing can be suppressed. Further, by providing a layer of the ethylene-unsaturated carboxylic acid copolymer, there is an effect of suppressing curling when the heat seal layer is laminated with the base material.
[0017]
By laminating the 2A layer and the 2B layer, the heat seal layer can be easily formed at a predetermined layer ratio. As a method for laminating the heat seal layer 2 formed from the 2A layer and the 2B layer and the substrate 3, a dry laminating method, a sandwich laminating method, a coextrusion laminating method, or the like can be used.
[0018]
When the thickness of the 2A layer of the heat seal layer is less than 5 μm, the seal strength tends to be unstable, and the sealing of impurities is insufficient. Further, if the thickness of the 2A layer of the heat seal layer exceeds 15 μm, stringing tends to occur at the time of opening. On the other hand, when the thickness of the 2B layer forming the heat seal layer is thinner than the 2A layer, the curl when the heat seal layer is laminated with the base material is increased, and the 2A layer and the 2B layer are laminated by the coextrusion method. It will also be difficult.
[0019]
When the melting point of the low density polyethylene contained in the 2A layer of the heat seal layer exceeds 110 ° C., the heat seal strength at a low temperature becomes weak, and stringing tends to occur. Further, when linear low density polyethylene which is a copolymer of ethylene and α-olefin, so-called LLDPE, is used for the 2A layer, the sealing strength is increased and paper peeling tends to occur. As the low density polyethylene used for the 2A layer of the heat seal layer, a high pressure method low density polyethylene having a density of 0.915 to 0.920 and an MFR of 0.5 to 50, preferably 20 to 50 is suitable.
[0020]
When the melting point of polybutene-1 is less than 120 ° C., the sealing strength becomes strong, and paper peeling tends to occur during peeling. When a copolymer comprising butene-1 as a main component and the butene-1 and other olefins are copolymerized is used, the sealing strength is increased and paper peeling tends to occur. It is desirable to use polybutene-1 having a density of 0.905 to 0.917 and an MFR of 0.2 to 20.
[0021]
As the ethylene-unsaturated carboxylic acid copolymer of the 2B layer of the heat seal layer, EMAA and EAA can be suitably used. When the melting point of the ethylene-unsaturated carboxylic acid copolymer is higher than that of the low density polyethylene used in the 2A layer, stringing tends to occur at the time of opening. EMAA having a density of 0.930 to 0.940 and an MFR of 2 to 20 can be suitably used. As the EAA, those having a density of 0.924 to 0.941 and an MFR of 2 to 20 can be suitably used.
[0022]
Hereinafter, the opening of the container using the packaging material of the present invention will be described. As shown in FIG. 3A, the heat seal layer of the packaging material 1 of the present invention is opposed to the heat seal layer of the adherend 10 and heat-sealed by a hot plate 30 to form the heat seal portion 13. . When the heat seal portion 13 is peeled off (opened), as shown in FIG. 3B, the cohesive failure 14 occurs in the 2A layer made of the blend resin of the heat seal layer 2 to show easy opening, No release surface is formed.
[0023]
When the base material 3 on which the heat seal layer 2 is laminated is a plastic film such as paper, aluminum foil, or polyethylene, the heat seal layer 2 composed of the 2A layer and the 2B layer is a coextrusion laminating method. Can be directly laminated on the base material, which simplifies the manufacturing process.
[0024]
The packaging material of the present invention can be suitably used as a lid member 21 that is heat-sealed to a polyethylene-coated paper cup container 22 as shown in FIG. The paper container is sealed by pressing the lip curl portion of the container body 22 to form a smooth flange 23 and heat-sealing the lid 21 on the flange portion. At the time of opening, the heat-sealed portion of the lid is peeled off. The packaging material department of the present invention is used as a lid material, and the peeled state for opening is shown in FIG. The paper container is widely used for foods such as instant noodles, yogurt, snacks, and natto. By using the packaging material of the present invention as a cover material for the paper container, excellent peelability can be imparted to the peel surface, and stringing of the release surface that has been conventionally observed in paper containers is prevented. I was able to.
[0025]
【Example】
Next, the packaging material and container of the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
[0026]
[Example 1]
A mixture of 65 parts by weight of low density polyethylene (melting point: 105 ° C.) and 35 parts by weight of polybutene-1 (melting point: 125 ° C.) is used as a peel layer as a first layer (thickness: 10 μm), and an ethylene-methacrylic acid copolymer (hereinafter referred to as “the first layer”). (Referred to as “EMAA”) (melting point: 98 ° C.) as the second layer (thickness: 20 μm), while the ozone treatment is applied to the EMAA layer side, the paper is subjected to corona treatment (100 g / m 2 ) and the extrusion temperature is 300. Co-extrusion lamination was performed at 0 ° C. to obtain a packaging material having the following constitution.
[0027]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0028]
[Example 2]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a peel layer as a first layer (thickness 10 μm), and EMAA (melting point 98 ° C.) is the first layer. As two layers (20 μm), coextrusion lamination was performed on an aluminum foil (thickness 50 μm) at an extrusion temperature of 300 ° C. to obtain a packaging material having the following configuration.
[0029]
Aluminum foil (50 μm) / EMAA (20 μm) / peel layer (10 μm)
[0030]
[Example 3]
An ethylene-acrylic acid copolymer (hereinafter referred to as “EAA”) (melting point: 96 ° C.) was used in the same manner as in Example 1 instead of EMAA. That is, a mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a peel layer as a first layer (thickness 10 μm), and EAA (melting point 96 ° C.) As a second layer (thickness 20 μm), co-extrusion laminating is performed on paper (100 g / m 2 ) subjected to corona treatment while applying ozone treatment to the EAA layer side at an extrusion temperature of 300 ° C. Got.
[0031]
Paper (100 g / m 2 ) / EAA (20 μm) / peel layer (10 μm)
[0032]
[Example 4]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a first layer as a peel layer, and EMAA (melting point 98 ° C.) is used as a second layer. After creating a sealant film by the inflation molding method, applying corona treatment to the EMAA side of this film, dry laminating using a two-component curable urethane adhesive on one side of a 16 μm thick PET film, Packaging material was obtained.
[0033]
PET (16 μm) / Adhesive layer / EMAA (20 μm) / Peel layer (10 μm)
[0034]
[Example 5]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a first layer (20 μm) as a peel layer, and EMAA (melting point 98 ° C.) is a second layer. As (10 μm), co-extrusion lamination was performed at a temperature of 300 ° C. on a corona-treated paper (100 g / m 2 ) while performing ozone treatment on the EMAA layer side to obtain a packaging material having the following constitution.
[0035]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0036]
[Example 6]
A mixture of 65 parts by weight of low density polyethylene (melting point: 111 ° C.) and 35 parts by weight of polybutene-1 (melting point: 125 ° C.) is used as a peel layer as the first layer (10 μm), and EMAA (melting point: 98 ° C.) is the second layer. As (20 μm), coextrusion laminating was performed on a corona-treated paper (100 g / m 2 ) at an extrusion temperature of 300 ° C. while performing ozone treatment on the EMAA layer side to obtain a packaging material having the following constitution.
[0037]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0038]
[Example 7]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 100 ° C.) is used as a first layer (10 μm) as a peel layer, and EMAA (melting point 98 ° C.) is a second layer. As (20 μm), coextrusion laminating was performed on a corona-treated paper (100 g / m 2 ) at an extrusion temperature of 300 ° C. while performing ozone treatment on the EMAA layer side to obtain a packaging material having the following constitution.
[0039]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0040]
[Example 8]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a peel layer as the first layer (10 μm), and EMAA (melting point 105 ° C.) is the second layer. As (20 μm), coextrusion laminating was performed on a corona-treated paper (100 g / m 2 ) at an extrusion temperature of 300 ° C. while performing ozone treatment on the EMAA layer side to obtain a packaging material having the following constitution.
[0041]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0042]
[Comparative Example 1]
A mixture of 80 parts by weight of low density polyethylene (melting point 105 ° C.) and 20 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a peel layer as a first layer (thickness 10 μm), and EMAA (melting point 98 ° C.) is second. As a layer (thickness 20 μm), co-extrusion lamination was performed at an extrusion temperature of 300 ° C. on paper (100 g / m 2 ) subjected to corona treatment while performing ozone treatment on the EMAA layer side, thereby obtaining a packaging material having the following constitution. .
[0043]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0044]
[Comparative Example 2]
A mixture of 50 parts by weight of low density polyethylene (melting point 105 ° C.) and 50 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a peel layer as the first layer (10 μm), and EMAA (melting point 98 ° C.) is the second layer. As (20 μm), coextrusion laminating was performed on a corona-treated paper (100 g / m 2 ) at an extrusion temperature of 300 ° C. while performing ozone treatment on the EMAA layer side to obtain a packaging material having the following constitution.
[0045]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0046]
[Comparative Example 3]
A mixture of 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) is used as a first layer (thickness 10 μm) as a peel layer, and low density polyethylene (LDPE) (melting point) 105 ° C., density = 0.92, MFR = 7) as the second layer (thickness 20 μm), while applying the ozone treatment to the LDPE layer side, the extrusion temperature 300 was applied to the paper (100 g / m 2 ) subjected to the corona treatment. Co-extrusion lamination was performed at 0 ° C. to obtain a packaging material having the following constitution.
[0047]
Paper (100 g / m 2 ) / LDPE (20 μm) / Peel layer (10 μm)
[0048]
[Comparative Example 4]
First layer (10 μm) using a mixture of 65 parts by weight of linear low density polyethylene (hereinafter referred to as “LLDPE”) (melting point 110 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) as a peel layer ), EMAA (melting point: 98 ° C.) as the second layer (20 μm), co-extrusion laminating at the extrusion temperature of 300 ° C. on the paper (100 g / m 2 ) subjected to corona treatment while performing ozone treatment on the EMAA layer side A packaging material having the following constitution was obtained.
[0049]
Paper (100 g / m 2 ) / EMAA (20 μm) / Peel layer (10 μm)
[0050]
<Test>
A cup base paper (280 g / m 2 ) obtained by extrusion coating of low-density polyethylene having a melting point of 106 ° C. with a thickness of 20 μm is formed into a cup shape having a flange portion, and the packaging material prepared in Example 1 is used as a lid material on the flange portion. After heat sealing under conditions of 150 ° C. and 0.6 sec, it was opened and the cross section of the peeled surface was observed with a microscope. Since the peel layer of the lid material was observed on both the lid material side and the cup side, it was confirmed that the peel layer was agglomerated and broken at the time of opening.
[0051]
Further, the packaging materials prepared in each of the examples and comparative examples were subjected to conditions of 140 ° C., 98 Kpa, 1 sec on cup base paper (280 g / m 2 ) coated with low-density polyethylene (thickness 20 μm) having a melting point of 106 ° C. Heat-sealed, and compared the peel strength and the stringing condition of the peeled surface. The curl was evaluated by visual observation.
[0052]
The easy-openability and the occurrence of curling in Examples and Comparative Examples were as follows.
[0053]
[Table 1]
Figure 0004522562
[0054]
The packaging materials of Examples 1 to 4 exhibited moderate peel strength, and the curling was small without causing stringing on the peeled surface. In the packaging material of Example 5, the thickness of the EMAA layer was slightly thinner than that of the peel layer, so the curl was slightly conspicuous and the stringing was slightly higher. In the packaging material of Example 6, the melting point of the low density polyethylene was slightly high, so that the peel strength was slightly weak and the stringing was slightly high. The packaging material of Example 7 had a slightly high peel strength because the melting point of polybutene-1 was slightly low. The packaging material of Example 8 had a slightly higher melting point of EMAA and the same melting point as that of low-density polyethylene, so that the stringing was slightly higher, the peel strength was weaker, and the curl was slightly noticeable.
[0055]
In the packaging material of Comparative Example 1, since the blending ratio of polybutene-1 was too small, the peel strength was too strong and paper peeling occurred. In the packaging material of Comparative Example 2, since the blending ratio of polybutene-1 was too large, the peel strength was too weak and the amount of stringing was slightly high. In the packaging material of Comparative Example 3, low density polyethylene was used instead of the ethylene-unsaturated carboxylic acid copolymer as the second layer, so that there was much stringing and curl was large. Since the packaging material of Comparative Example 4 used LLDPE instead of low-density polyethylene, the peel strength was too strong and paper peeling occurred.
[0056]
[Example 9]
60 parts by weight of low density polyethylene (melting point: 106 ° C.) and polybutene-1 (melting point: 125 ° C.) are placed on the aluminum foil side of the base material having a layer structure of [paper / polyethylene / aluminum foil] via a urethane anchor agent. A mixture with 40 parts by weight is used as a peel layer as a first layer (thickness 10 μm), EMAA (melting point 100 ° C.) as a second layer (thickness 30 μm), and an extrusion temperature 260 is applied while performing ozone treatment on the EMAA layer side. Co-extrusion lamination was performed at 0 ° C. to obtain a packaging material having the following constitution.
[0057]
[Paper (76 g / m 2 ) / Polyethylene (20 μm) / Aluminum foil (7 μm) / EMAA (30 μm) / Peel layer (10 μm)]
When this packaging material was used as a lid for an instant noodle paper cup formed from paper (280 g / m 2 ) coated with polyethylene having a melting point of 110 ° C. No easy-open container having excellent sealing properties and heat resistance was obtained.
[0058]
[Example 10]
70 parts by weight of low density polyethylene (melting point 105 ° C.) and polybutene-1 (melting point 125 ° C.) via a urethane anchor agent on the PET side of the substrate having a layer structure of [paper / polyethylene / aluminum foil / PET] 30 parts by weight of the mixture as a peel layer as a first layer (thickness: 10 μm), EMAA (melting point: 98 ° C.) as a second layer (thickness: 40 μm), and the extrusion temperature while performing ozone treatment on the EMAA layer side Co-extrusion lamination was performed at 250 ° C. to obtain a packaging material having the following configuration.
[0059]
[Paper (79 g / m 2 ) / Polyethylene (20 μm) / Aluminum foil (7 μm) / PET (12 μm) / EMAA (40 μm) / Peel layer (10 μm))
This packaging material is [paper (210 g / m 2 ) / polyethylene (20 μm) / aluminum foil (7 μm) / EMAA (10 μm) / polyethylene (20 μm)].
When used as a lid for paper cups for snacks formed using base paper having the layer structure of the above, there is no paper peeling or stringing at the time of opening, and an easy-open container with excellent sealing and heat resistance is obtained. I was able to.
[0060]
[Example 11]
On the aluminum foil side of the substrate having a layer structure of [PET (12 μm) / aluminum foil (10 μm)], 65 parts by weight of low density polyethylene (melting point 105 ° C.) and 35 parts by weight of polybutene-1 (melting point 125 ° C.) As a peel layer, the first layer (thickness: 10 μm) is used as the peel layer, and EMAA (melting point: 100 ° C.) is used as the second layer (thickness: 35 μm). Got.
[0061]
[PET (12 μm) / aluminum foil (10 μm) EMAA (35 μm) / peel layer (10 μm)]
When this packaging material was used as a cover material for a yoghurt paper cup formed of paper (240 g / m 2 ) whose inner surface was coated with polyethylene having a melting point of 107 ° C., no paper peeling or stringing occurred during opening, An easy-open container with excellent sealing and heat resistance could be obtained.
[0062]
【The invention's effect】
The packaging material of the present invention has a heat seal layer including a peel layer. When the heat-sealed portion sealed by the heat-sealing method is peeled and opened using this packaging material, cohesive failure occurs in the peel layer, and easy-openability is exhibited. In addition, stringing of the unsealed portion is not generated.
[0063]
And when this packaging material is used as a cover material for a paper cuff whose inner surface is made of polyethylene, a sealed paper cup having easy opening is obtained. The container thus obtained is extremely usable for consumers.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of a packaging material according to the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the packaging material of the present invention.
FIGS. 3A and 3B are conceptual diagrams for explaining a state when the packaging material of the present invention is peeled from the adherend, in which FIG. 3A shows a heat-sealed state, and FIG. 3B shows a state where the heat-sealed portion is peeled off.
FIG. 4 shows an embodiment of a container using the packaging material of the present invention as a lid, wherein (a) is a perspective view of the container, (b) a cross-sectional view of X part X, and (c) a seal part. It is a fragmentary sectional view, (d) It is a fragmentary sectional view of a peel part when a cover material is peeled.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Packaging material 2 ... Heat seal layer 3 ... Base material 4 ... Adhesive layer 10 ... Adhered body 11 ... Adhered body heat seal layer 13 ... Heat seal part 14 ... Peeling part 20 ... Container 21 ... Lid 22 ... Container main body 23 ... Flange 30 ... Hot plate

Claims (5)

少なくとも、基材と当該基材の一面側に設けられたヒートシール層とからなり、前記ヒートシール層は、前記基材に近い側からエチレン−メタクリル酸共重合体、又はエチレン−アクリル酸共重合体よりなる樹脂層（Ｂ）と、低密度ポリエチレンを６５重量部とポリブテン−１を３５重量部の割合で含有する樹脂層（Ａ）を、この順序で設けた積層構造を有すると共に、前記樹脂層（Ａ）と樹脂層（Ｂ）は共押出し法により互いに積層されていることを特徴とする易開封包装材料。It comprises at least a base material and a heat seal layer provided on one surface side of the base material, and the heat seal layer is an ethylene-methacrylic acid copolymer or ethylene-acrylic acid copolymer from the side close to the base material. The resin layer (B) made of a coalesced resin and the resin layer (A) containing 65 parts by weight of low density polyethylene and 35 parts by weight of polybutene-1 are provided in this order, and the resin An easy-open packaging material, wherein the layer (A) and the resin layer (B) are laminated together by a coextrusion method. 前記樹脂層（Ａ）の厚みが５〜１５μｍの範囲であり、且つ、前記樹脂層（Ｂ）の厚みが樹脂層（Ａ）の厚さ以上であることを特徴とする、請求項１に記載の包装材料。  The thickness of the resin layer (A) is in the range of 5 to 15 µm, and the thickness of the resin layer (B) is equal to or greater than the thickness of the resin layer (A). Packaging materials. 前記低密度ポリエチレンが融点１１０℃以下の高圧法低密度ポリエチレンであり、且つ、前記ポリブテン−１が融点１２０℃以上のホモポリマーであり、更に、前記エチレン−不飽和カルボン酸共重合体の融点が前記低密度ポリエチレンの融点よりも低いことを特徴とする、請求項１または請求項２に記載の包装材料。  The low-density polyethylene is a high-pressure method low-density polyethylene having a melting point of 110 ° C. or lower, the polybutene-1 is a homopolymer having a melting point of 120 ° C. or higher, and the ethylene-unsaturated carboxylic acid copolymer has a melting point of The packaging material according to claim 1 or 2, wherein the packaging material is lower than a melting point of the low density polyethylene. 前記ヒートシール層が共押出ラミネート法により前記基材に積層されていることを特徴とする、請求項１〜請求項３のいずれかに記載の包装材料。  The packaging material according to any one of claims 1 to 3, wherein the heat seal layer is laminated on the substrate by a coextrusion laminating method. 請求項１〜請求項４の包装材料が、融点１０５〜１１５℃のポリエチレンを最内層にコートした紙カップ容器の蓋材としてヒートシールされており、開封時には前記樹脂層（Ａ）が凝集破壊することを特徴とする、易開封容器。  The packaging material according to claims 1 to 4 is heat-sealed as a lid for a paper cup container in which polyethylene having a melting point of 105 to 115 ° C. is coated on the innermost layer, and the resin layer (A) cohesively breaks when opened. Easy-open container characterized by.
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