JP4120227B2 - Heat-sealable laminated polypropylene resin film and package - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、ヒートシール性積層ポリプロピレン系樹脂フィルム及び包装体に関し、さらに詳しくは、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で包装用途に好適に用いることができるヒートシール性積層ポリプロピレン系樹脂フィルム及びかかるフィルムを用いてなる包装体に関する。
【０００２】
【従来の技術】
従来から、包装用に使用するヒートシーラブルフィルムとしては、一般的に、ポリプロピレン系樹脂に低融点のポリオレフィン系樹脂を積層した共押出し積層ポリプロピレン系樹脂フィルム、無延伸ポリエチレン系樹脂フィルム又はポリプロピレン系樹脂フィルムと延伸ポリプロピレン系樹脂フィルムとをラミネートした積層ポリプロピレン系樹脂フィルムが多用されている。しかしながら、ポリプロピレン系樹脂に低融点のポリオレフィン系樹脂を積層した共押出し積層ポリプロピレン系樹脂フィルムでは、ある程度のシール強度はあるものの、水物などの重量物を包装するまでのシール強度はなく、無延伸ポリエチレン系樹脂フィルム又はポリプロピレン系樹脂フィルムと延伸ポリプロピレン系樹脂フィルムとをラミネートした積層ポリプロピレン系樹脂フィルムにおいては、十分なシール強度はあるものの、有機溶剤等を使用するラミネート工程が必要であり、経済的にも地球環境に与える影響の面からも好ましくない。
【０００３】
【発明が解決しようとする課題】
本発明は、上記従来の積層ポリプロピレン系樹脂フィルムの有する問題点を解決し、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で包装用途に好適に用いることができるヒートシール性積層ポリプロピレン系樹脂フィルム及びかかるフィルムを用いてなる包装体を提供することを目的とする。
【課題を解決するための手段】
【０００４】
上記目的を達成するため、本発明のヒートシール性積層ポリプロピレン系樹脂フィルムは、結晶性ポリプロピレン系樹脂からなる基材層Ａ、中間層Ｂ及び融点が１５０℃以下の熱融着層Ｃが順に積層されてなる積層二軸延伸ポリプロピレン系樹脂フィルムであって、基材層Ａのメルトフローレート（ＭＦＲ(Ａ)）、中間層Ｂのメルトフローレート（ＭＦＲ(Ｂ)）及び熱融着層Ｃのメルトフローレート（ＭＦＲ(Ｃ)）が下記式（１）を満足し、かつ、中間層Ｂを形成する樹脂が、基材層Ａを形成する樹脂と熱融着層Ｃを形成する樹脂をそれぞれ一種類以上含有することを特徴とする。
ＭＦＲ(Ｃ)≧２×ＭＦＲ(Ａ)≧ＭＦＲ(Ｂ) （１）
【０００５】
上記の構成からなる本発明のヒートシール性積層ポリプロピレン系樹脂フィルムは、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で包装用途に好適に用いることができる。
【０００６】
この場合、ヒートシール性積層ポリプロピレン系樹脂フィルムの中間層Ｂを形成する樹脂は、熱融着層Ｃを形成する樹脂の少なくとも一種類を４０重量％以上含有することができる。
【０００７】
また、本発明の包装体は、上記ヒートシール性積層ポリプロピレン系樹脂フィルムを用いてなることを特徴とする。
【０００８】
上記の構成からなる本発明の包装体は、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で、重量物を包装することができる。
【発明の実施の形態】
【０００９】
以下、本発明のヒートシール性積層ポリプロピレン系樹脂フィルム及び包装体の実施の形態を説明する。
【００１０】
本発明において、基材層Ａに用いるポリプロピレン系樹脂としては、通常の押出成形などで使用するｎ−ヘプタン不溶性のアイソタクチックのプロピレン単独重合体又はプロピレンを７０重量％以上含有するポリプロピレンと他のα−オレフィンとの共重合体であればよい。共重合成分としてのα−オレフィンは、炭素数が２〜８のα−オレフィン、例えば、エチレン、ブテン−１、ペンテン−１、ヘキセン−１、４−メチル−１−ペンテンなどが好ましい。ここで共重合体とは、ランダム又はブロック共重合体が含まれる。また、メルトフローレート（ＭＦＲ）は０．１〜１００ｇ／１０ｍｉｎ、好ましくは０．５〜２０ｇ／１０ｍｉｎ、さらに好ましくは、１．０〜１０ｇ／１０ｍｉｎの範囲のものを例示することができる。さらに、基材層Ａの結晶性ポリプロピレン系樹脂は、２種以上の混含物であってもよい。
【００１１】
また、本発明において、熱融着層Ｃに用いる樹脂は融点が１５０℃以下の熱可塑性樹脂であって、エチレン、プロピレン、ブテン、ペンテン、ヘキセン、オクテン、デセン等の炭素数が２〜１０のα−オレフィン系モノマーから選ばれた２種以上を重合して得たランダム共重合体又はブロック共重合体が好ましく、また、この共重合体は単独又は混合して使用することができる。
【００１２】
さらにまた、熱融着層Ｃを形成する熱可塑性樹脂の融点は１５０℃以下、好ましくは６０〜１５０℃にすることが望ましい。このようにすることにより、ヒートシール性積層ポリプロピレン系樹脂フィルムに十分なヒートシール強度を与えることができる。熱融着層Ｃを形成する熱可塑性樹脂の融点が６０℃未満ではヒートシール部の耐熱性が乏しく、１５０℃を越えるとヒートシール強度の向上が期待できない傾向にある。
【００１３】
熱融着層ＣのＭＦＲは、基材層ＡのＭＦＲの２倍以上であるが、２〜１０倍であるのが好ましい。熱融着層ＣのＭＦＲが基材層ＡのＭＦＲの２倍を下回る場合は、溶融時の樹脂の流れ性が悪くなり、ヒートシール時の熱融着層Ｃ同士の接着が不十分になる傾向があり好ましくない。逆に、熱融着層ＣのＭＦＲが基材層ＡのＭＦＲの１０倍を越える場合は、溶融時の樹脂の流れ性がよくなり過ぎて、ヒートシール時に熱融着層Ｃの層厚みが薄くなり、十分なヒートシール強度が得られない傾向にある。
【００１４】
中間層Ｂを形成する樹脂は、基材層Ａ及び熱融着層Ｃをそれぞれ形成する樹脂を、少なくとも１種類ずつ以上含有し、好ましくは、熱融着層Ｃを形成する樹脂を４０％以上、より好ましくは４０〜８０％の範囲で含有することが望ましい。中間層Ｂに基材層Ａ及び熱接着層Ｃを形成する樹脂を含まない場合は、基材層Ａと中間層Ｂ、熱融着層Ｃと中間層Ｂそれぞれの層間での接着力が不十分となり、十分なヒートシール強度が得られない傾向にあり好ましくない。
【００１５】
また、中間層Ｂを形成する樹脂中の熱融着層Ｃを形成する樹脂の含有量が４０％未満の場合は、中間層Ｂと熱融着層Ｃの層間での接着力が低くなる傾向にあり、８０％を越える場合は、フィルムの腰がなくなり、自動包装機械適性やハンドリング性が悪くなる傾向にある。
【００１６】
また、中間層ＢのＭＦＲは、基材層ＡのＭＦＲの２倍以下であるが、好ましくは基材層ＡのＭＦＲの値以上であって２倍以下である。中間層ＢのＭＦＲが、基材層ＡのＭＦＲの２倍よりも大きい場合は、基材層Ａ、中間層Ｂ、熱融着層Ｃを溶融共押出しするようなときには、各層間の樹脂の流れに差が生じ、各層間がうろこ状の斑となり、透明性が悪くなる傾向にあり、また、ヒートシール時の熱により中間層Ｂが変形して皺等が発生する傾向にあり、実用上好ましくない。一方、中間層ＢのＭＦＲが、基材層ＡのＭＦＲより小さい場合も、基材層Ａ、中間層Ｂ、熱融着層Ｃを溶融共押出しするようなときには、各層間の樹脂の流れに差が生じ、各層間がうろこ状の斑となり、透明性が悪くなる傾向にある。
【００１７】
本発明において、基材層Ａを形成する結晶性ポリプロピレン系樹脂及び熱融着層Ｃを形成する熱可塑性樹脂は、必要に応じて各層の特性を阻害しない範囲で、各種添加材、充填材、例えば、熱安定剤、酸化防止剤、光安定剤、帯電防止剤、滑剤、核剤、難燃剤、顔料、染料、炭酸カルシウム、硫酸カルシウム、硫酸バリウム、水酸化マグネシウム、マイカ、タルク、クレー等を添加することができる。さらにまた、その他の熱可塑性樹脂、熱可塑性エラストマー、ゴム類、炭化水素樹脂、石油樹脂等を本発明のフィルムの特性を害さない範囲で配合してもよい。
【００１８】
本発明のヒートシール性積層ポリプロピレン系樹脂フィルムの各層の厚み構成は、その用途に応じて任意に定めることができ、特に限定するものではないが、好ましい範囲としては、基材層Ａは１０〜１００μｍ、熱融着層Ｃは１．５〜１０μｍ、中間層Ｂは５〜５０μｍを例示することができる。
【００１９】
本発明のヒートシール性の良好な積層ポリプロピレン系樹脂フィルムはそれ自体公知の方法で任意に製造することができ、特に制限するものではない。例えば、積層数に見合う押出機を用いてＴダイ法又はインフレーション法等で溶融積層した後、冷却ロール法、水冷法又は空冷法で冷却して積層フィルムとし、逐次２軸延伸法、同時２軸延伸法、チューブ延伸法等で延伸する方法を例示することができる。
【００２０】
本発明のヒートシール性の良好な積層ポリプロピレン系樹脂フィルムは、基材層Ａの表面に他の樹脂層、例えば、エチレン−酢酸ビニル共重合体けん化物、ポリビニルアルコール等のガスバリヤ性樹脂層をさらに積層してもよく、また、基材層Ａと中間層Ｂの間、中間層Ｂと熱融着層Ｃの間に同様に積層することも、その特性を害しない限り、特に制限されない。
【００２１】
本発明のヒートシール性の良好な積層ポリプロピレン系樹脂フィルムは、印刷性、ラミネート性等を向上させるために表面処理を行うことができる。表面処理の方法としては、コロナ放電処理、プラズマ処理、火炎処理、酸処理等が例示でき、特に制限はない。連続処理が可能であり、このフィルムの製造過程の巻取り工程前に容易に実施できるコロナ放電処理、プラズマ処理、火炎処理を行うのが好ましい。
【００２２】
本発明のヒートシール性積層ポリプロピレン系樹脂フィルムは、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で小麦粉、米、麦などの穀物類や板・糸こんにゃく類、たくあん漬、醤油漬、奈良漬などの各種漬物類、各種味噌類、だしのもと、めんつゆ、醤油、ソース、ケチャップ、マヨネーズなどの包装材料として好適であり、また、これらは、ペーパーカートン、チューブ用、袋用、カップ用、スタンディングパック用、トレイ用などの包装体として用いることができる。
【００２３】
【実施例】
以下、本発明の具体例を実施例によってさらに説明するが、本発明は、その要旨を逸脱しない限り以下の実施例に限定されるものではない。なお、本明細書中における特性は下記の方法により評価を行った。
【００２４】
（ヒートシール強度）
ヒートシール温度１４０℃、圧力９．８×１０ｋＰａ、ヒートシール時間１秒の条件で、積層フィルムの熱融着層Ｃ面同士を重ね合せて熱板シールを行い、１５ｍｍ幅の試験片を作製した。この試験片の１８０度剥離強度を測定し、ヒートシール強度（Ｎ／１５ｍｍ）とした。
【００２５】
（ヘイズ）
ＪｌＳ−Ｋ−７１０５に準拠してヘイズ（％）を測定した。
【００２６】
（メルトフローレート）
ＪｌＳ−Ｋ−６７５８に示されるポリプロピレン系樹脂試験方法（２３０℃、２１．１８Ｎ）に準拠してメルトフローレート（ＭＦＲ）（ｇ／１０分）を測定した。各層を形成する樹脂が２種類以上である場合は、それぞれの樹脂の単独のＭＦＲ値を各層の樹脂配合比をもとに荷重平均した値を、当該層のＭＦＲとした。
【００２７】
（実施例１）
３台の溶融押出機を用い、第１の押出機にてプロピレン単独重合体（密度０．９０ｇ／ｃｍ3、ＭＦＲ２．５ｇ／１０分、融点１５７℃）を基材層（Ａ）として、第２の押出機にて、プロピレン・エチレン・ブテンランダム共重合体（密度０．８９ｇ／ｃｍ3、ＭＦＲ４．０ｇ／１０分、融点１３５℃）を４０重量％、プロピレン・ブテンランダム共重合体（密度０．９０ｇ／ｃｍ3、ＭＦＲ９．０ｇ／１０分、融点１３０℃）を６０重量％とした混合樹脂を熱融着層Ｃとして、第３の押出機にて、基材層Ａ使用のプロピレン単独重合体を４０重量％、熱融着層Ｃ使用のプロピレン・エチレン・ブテンランダム共重合体を６０重量％とした混合樹脂を中間層Ｂとして、ダイス内にて基材層Ａ／中間層Ｂ／熱融着層Ｃとなるように、基材層Ａ、中間層Ｂ、熱融着層Ｃの順にＴダイ方式にて溶融共押出し後、チルロールにて冷却固化し、縦方向に４．５倍、横方向に８倍延伸し、基材層Ａ、中間層Ｂ、熱融着層Ｃの厚みがそれぞれ順に１４μｍ、１４μｍ、２μｍである積層フィルムを得た。得られた積層フィルムは本発明の要件を満足するものであり、十分なヒートシール強度と透明性を有するものであった。
【００２８】
（比較例１）
熱融着層Ｃ及び中間層Ｂに用いるプロピレン・エチレン・ブテンランダム共重合体が、密度０．８９ｇ／ｃｍ3、ＭＦＲ８．０ｇ／１０分、融点１３５℃である以外は、実施例１と同様にして積層フィルムを得た。得られた積層フィルムは中間層ＢのＭＦＲが基材層ＡのＭＦＲの２倍より高く、透明性が著しく悪いものであった。
【００２９】
（比較例２）
中間層Ｂが、基材層Ａに使用のプロピレン単独重合体により形成されてなる以外は、実施例１と同様にして積層フィルムを得た。得られた積層フィルムは中間層Ｂを形成する樹脂が、基材層Ａ使用の樹脂のみからなりヒートシール強度が不十分なものであった。
【００３０】
（比較例３）
中間層Ｂが、熱融着層Ｃに使用のプロピレン・エチレン・ブテンランダム共重合体により形成されてなる以外は、実施例１と同様にして積層フィルムを得た。得られた積層フィルムは中間層Ｂを形成する樹脂が、熱融着層Ｃ使用の樹脂のみからなりヒートシール強度が不十分なものであった。
【００３１】
（比較例４）
熱融着層Ｃが、プロピレン・エチレン・ブテンランダム共重合体（密度０．８９ｇ／ｃｍ3、ＭＦＲ４．０ｇ／１０分、融点１３５℃）により形成されてなる以外は、実施例１と同様にして積層フィルムを形成した。得られた積層フィルムは熱融着層ＣのＭＦＲが、基材層ＡのＭＦＲの２倍よりも小さく、ヒートシール強度が不十分なものであった。
【００３２】
得られた実施例１、比較例１〜４のフィルムについてヒートシール強度とヘイズを測定し、表１に示した。
【００３３】
【表１】
【発明の効果】
本発明のヒートシール性積層ポリプロピレン系樹脂フィルムによれば、重量物を包装するのに十分なヒートシール強度を有し、透明性が良好で包装用途に好適に用いることができる。
【００３５】
本発明の包装体によれば、重量物の包装が可能な十分なヒートシール強度を有し、透明性が良好な包装体とすることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-sealable laminated polypropylene-based resin film and a package, and more specifically, has a heat-seal strength sufficient for packaging heavy objects, has good transparency, and is suitably used for packaging applications. The present invention relates to a heat-sealable laminated polypropylene resin film and a package using such a film.
[0002]
[Prior art]
Conventionally, heat-sealable films used for packaging are generally co-extruded laminated polypropylene resin films, unstretched polyethylene resin films, or polypropylene resins obtained by laminating low melting point polyolefin resins to polypropylene resins. A laminated polypropylene resin film obtained by laminating a film and a stretched polypropylene resin film is often used. However, co-extrusion laminated polypropylene resin film in which low melting point polyolefin resin is laminated on polypropylene resin has a certain level of sealing strength, but does not have enough sealing strength to package heavy objects such as water, and is not stretched. A laminated polypropylene resin film obtained by laminating a polyethylene resin film or a polypropylene resin film and a stretched polypropylene resin film has sufficient sealing strength, but requires a laminating process using an organic solvent, etc. Moreover, it is not preferable from the aspect of influence on the global environment.
[0003]
[Problems to be solved by the invention]
The present invention solves the problems of the above-described conventional laminated polypropylene resin film, has sufficient heat seal strength to package heavy objects, has good transparency, and can be suitably used for packaging applications. An object is to provide a heat-sealable laminated polypropylene resin film and a package using such a film.
[Means for Solving the Problems]
[0004]
In order to achieve the above object, the heat-sealable laminated polypropylene resin film of the present invention comprises a base material layer A made of a crystalline polypropylene resin, an intermediate layer B, and a heat-sealable layer C having a melting point of 150 ° C. or lower in order. A laminated biaxially stretched polypropylene-based resin film comprising a base material layer A having a melt flow rate (MFR (A)), an intermediate layer B having a melt flow rate (MFR (B)), and a heat-sealing layer C. The melt flow rate (MFR (C)) satisfies the following formula (1), and the resin that forms the intermediate layer B is a resin that forms the base layer A and a resin that forms the thermal fusion layer C, respectively. One or more types are contained.
MFR (C) ≧ 2 × MFR (A) ≧ MFR (B) (1)
[0005]
The heat-sealable laminated polypropylene resin film of the present invention having the above-described configuration has a heat-seal strength sufficient for packaging heavy objects, has good transparency, and can be suitably used for packaging applications.
[0006]
In this case, the resin forming the intermediate layer B of the heat-sealable laminated polypropylene resin film can contain at least 40% by weight or more of the resin forming the heat-sealing layer C.
[0007]
The package of the present invention is characterized by using the above heat-sealable laminated polypropylene resin film.
[0008]
The packaging body of the present invention having the above-described configuration has sufficient heat seal strength to package heavy objects, has good transparency, and can package heavy objects.
DETAILED DESCRIPTION OF THE INVENTION
[0009]
Hereinafter, embodiments of the heat-sealable laminated polypropylene resin film and the package of the present invention will be described.
[0010]
In the present invention, the polypropylene resin used for the base layer A is an n-heptane-insoluble isotactic propylene homopolymer used in ordinary extrusion molding or the like, and polypropylene containing 70% by weight or more of propylene and other Any copolymer with an α-olefin may be used. The α-olefin as the copolymerization component is preferably an α-olefin having 2 to 8 carbon atoms, such as ethylene, butene-1, pentene-1, hexene-1, 4-methyl-1-pentene. Here, the copolymer includes a random or block copolymer. Moreover, a melt flow rate (MFR) is 0.1-100 g / 10min, Preferably it is 0.5-20 g / 10min, More preferably, the thing of the range of 1.0-10 g / 10min can be illustrated. Further, the crystalline polypropylene resin of the base material layer A may be a mixture of two or more.
[0011]
In the present invention, the resin used for the heat sealing layer C is a thermoplastic resin having a melting point of 150 ° C. or less, and has 2 to 10 carbon atoms such as ethylene, propylene, butene, pentene, hexene, octene, and decene. Random copolymers or block copolymers obtained by polymerizing two or more selected from α-olefin monomers are preferred, and these copolymers can be used alone or in admixture.
[0012]
Furthermore, it is desirable that the melting point of the thermoplastic resin forming the heat sealing layer C is 150 ° C. or less, preferably 60 to 150 ° C. By doing in this way, sufficient heat seal intensity | strength can be given to a heat-sealable laminated polypropylene resin film. When the melting point of the thermoplastic resin forming the heat-sealing layer C is less than 60 ° C., the heat seal portion has poor heat resistance, and when it exceeds 150 ° C., the heat seal strength tends not to be improved.
[0013]
The MFR of the heat-fusible layer C is twice or more the MFR of the base material layer A, but preferably 2 to 10 times. When the MFR of the heat-sealing layer C is less than twice the MFR of the base material layer A, the flowability of the resin at the time of melting is deteriorated, and the adhesion between the heat-sealing layers C at the time of heat sealing becomes insufficient. There is a tendency and it is not preferable. On the contrary, when the MFR of the heat-sealing layer C exceeds 10 times the MFR of the base material layer A, the flowability of the resin at the time of melting becomes too good, and the layer thickness of the heat-sealing layer C at the time of heat sealing is Thinning tends to result in insufficient heat seal strength.
[0014]
The resin for forming the intermediate layer B contains at least one kind of resin for forming the base layer A and the heat sealing layer C, respectively, preferably 40% or more of the resin for forming the heat sealing layer C. More preferably, it is contained in the range of 40 to 80%. When the intermediate layer B does not contain the resin for forming the base layer A and the thermal adhesive layer C, the adhesive strength between the base layer A and the intermediate layer B, and the thermal fusion layer C and the intermediate layer B is not sufficient. This is not preferable because it tends to be sufficient and sufficient heat seal strength cannot be obtained.
[0015]
Further, when the content of the resin forming the heat-sealing layer C in the resin forming the intermediate layer B is less than 40%, the adhesive force between the layers of the intermediate layer B and the heat-sealing layer C tends to be low. In the case where it exceeds 80%, the film loses its elasticity and suitability for automatic packaging machines and handling properties tend to deteriorate.
[0016]
Moreover, although MFR of the intermediate | middle layer B is 2 times or less of MFR of the base material layer A, Preferably it is more than the value of MFR of the base material layer A, and 2 times or less. When the MFR of the intermediate layer B is larger than twice the MFR of the base layer A, when the base layer A, the intermediate layer B, and the heat fusion layer C are melt-coextruded, the resin of each layer There is a difference in flow, scaly spots between each layer, and transparency tends to deteriorate, and the intermediate layer B tends to deform due to heat at the time of heat sealing, causing wrinkles, etc. It is not preferable. On the other hand, even when the MFR of the intermediate layer B is smaller than the MFR of the base layer A, when the base layer A, the intermediate layer B, and the heat fusion layer C are melt-coextruded, the flow of resin between the respective layers A difference arises, each layer becomes a scale-like spot, and there exists a tendency for transparency to worsen.
[0017]
In the present invention, the crystalline polypropylene resin that forms the base layer A and the thermoplastic resin that forms the heat-fusible layer C are various additives, fillers, For example, heat stabilizer, antioxidant, light stabilizer, antistatic agent, lubricant, nucleating agent, flame retardant, pigment, dye, calcium carbonate, calcium sulfate, barium sulfate, magnesium hydroxide, mica, talc, clay, etc. Can be added. Furthermore, other thermoplastic resins, thermoplastic elastomers, rubbers, hydrocarbon resins, petroleum resins, and the like may be blended within a range that does not impair the characteristics of the film of the present invention.
[0018]
The thickness configuration of each layer of the heat-sealable laminated polypropylene resin film of the present invention can be arbitrarily determined according to the application, and is not particularly limited. 100 μm, the heat sealing layer C may be 1.5 to 10 μm, and the intermediate layer B may be 5 to 50 μm.
[0019]
The laminated polypropylene resin film having good heat sealability according to the present invention can be arbitrarily produced by a method known per se, and is not particularly limited. For example, after melt lamination by a T-die method or inflation method using an extruder suitable for the number of layers, the film is cooled by a cooling roll method, a water cooling method or an air cooling method to form a laminated film, sequentially biaxial stretching method, simultaneous biaxial Examples of the stretching method include a stretching method and a tube stretching method.
[0020]
The laminated polypropylene resin film having good heat sealability of the present invention is further provided with another resin layer on the surface of the base material layer A, for example, a gas barrier resin layer such as saponified ethylene-vinyl acetate copolymer or polyvinyl alcohol. Lamination may also be performed, and the same lamination between the base layer A and the intermediate layer B and between the intermediate layer B and the heat-sealing layer C is not particularly limited as long as the characteristics are not impaired.
[0021]
The laminated polypropylene resin film having good heat sealability of the present invention can be subjected to surface treatment in order to improve printability, laminating properties and the like. Examples of the surface treatment method include corona discharge treatment, plasma treatment, flame treatment, and acid treatment, and are not particularly limited. It is preferable to perform a corona discharge treatment, a plasma treatment, and a flame treatment that can be carried out continuously and can be easily carried out before the winding step of the film production process.
[0022]
The heat-sealable laminated polypropylene-based resin film of the present invention has sufficient heat-seal strength to wrap heavy objects, has good transparency, and grains such as flour, rice, and wheat, boards and yarn konjacs, It is suitable for packaging materials such as various pickles such as takuan pickles, soy sauce pickles, nara pickles, miso, miso soup, noodle soup, soy sauce, sauces, ketchup, mayonnaise, etc. , Bags, cups, standing packs, trays and the like.
[0023]
【Example】
Hereinafter, specific examples of the present invention will be further described with reference to examples. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the characteristic in this specification evaluated by the following method.
[0024]
(Heat seal strength)
Under the conditions of a heat sealing temperature of 140 ° C., a pressure of 9.8 × 10 kPa, and a heat sealing time of 1 second, the heat sealing layer C surfaces of the laminated film were overlapped to perform hot plate sealing, and a test piece having a width of 15 mm was produced. . The 180-degree peel strength of this test piece was measured and set as a heat seal strength (N / 15 mm).
[0025]
(Haze)
Haze (%) was measured based on JlS-K-7105.
[0026]
(Melt flow rate)
The melt flow rate (MFR) (g / 10 min) was measured according to the polypropylene resin test method (230 ° C., 21.18 N) shown in JlS-K-6758. When two or more kinds of resins forming each layer were used, a value obtained by load-averaging the single MFR value of each resin based on the resin blend ratio of each layer was defined as the MFR of the layer.
[0027]
(Example 1)
Using three melt extruders, a propylene homopolymer (density 0.90 g / cm 3 , MFR 2.5 g / 10 min, melting point 157 ° C.) was used as the base layer (A) in the first extruder. No. 2 extruder, propylene / ethylene / butene random copolymer (density 0.89 g / cm 3 , MFR 4.0 g / 10 min, melting point 135 ° C.) 40% by weight, propylene / butene random copolymer (density) Propylene alone using the base material layer A in the third extruder using a mixed resin with 0.90 g / cm 3 , MFR 9.0 g / 10 min, melting point 130 ° C.) of 60% by weight as the heat-fusible layer C A mixed resin comprising 40% by weight of the polymer and 60% by weight of the propylene / ethylene / butene random copolymer using the heat-sealing layer C is defined as an intermediate layer B, and the base layer A / intermediate layer B / The base material layer A, so as to become the heat fusion layer C, After melt coextrusion by the T-die method in the order of the interlayer B and the heat-sealing layer C, it is cooled and solidified with a chill roll, and stretched 4.5 times in the vertical direction and 8 times in the horizontal direction, and the base material layer A, intermediate A laminated film in which the thicknesses of the layer B and the heat sealing layer C were 14 μm, 14 μm, and 2 μm, respectively, was obtained. The obtained laminated film satisfied the requirements of the present invention and had sufficient heat seal strength and transparency.
[0028]
(Comparative Example 1)
The same as in Example 1 except that the propylene / ethylene / butene random copolymer used for the heat-sealing layer C and the intermediate layer B has a density of 0.89 g / cm 3 , MFR 8.0 g / 10 min, and a melting point of 135 ° C. Thus, a laminated film was obtained. The obtained laminated film had an MFR of the intermediate layer B higher than twice the MFR of the base material layer A, and the transparency was extremely poor.
[0029]
(Comparative Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the intermediate layer B was formed of the propylene homopolymer used for the base material layer A. In the obtained laminated film, the resin forming the intermediate layer B was composed only of the resin used for the base material layer A, and the heat seal strength was insufficient.
[0030]
(Comparative Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the intermediate layer B was formed of the propylene / ethylene / butene random copolymer used for the heat-sealing layer C. In the obtained laminated film, the resin forming the intermediate layer B was composed only of the resin used for the heat-sealing layer C, and the heat seal strength was insufficient.
[0031]
(Comparative Example 4)
Except that the heat-sealing layer C is formed of a propylene / ethylene / butene random copolymer (density 0.89 g / cm 3 , MFR 4.0 g / 10 min, melting point 135 ° C.), it is the same as in Example 1. A laminated film was formed. The obtained laminated film had an MFR of the heat-fusible layer C smaller than twice the MFR of the base material layer A, and the heat seal strength was insufficient.
[0032]
The heat seal strength and haze of the obtained films of Example 1 and Comparative Examples 1 to 4 were measured and shown in Table 1.
[0033]
[Table 1]
【The invention's effect】
According to the heat-sealable laminated polypropylene resin film of the present invention, it has sufficient heat-seal strength for packaging heavy objects, has good transparency, and can be suitably used for packaging applications.
[0035]
According to the packaging body of the present invention, a packaging body having sufficient heat seal strength capable of packaging heavy objects and good transparency can be obtained.
Claims (3)
ＭＦＲ(Ｃ)≧２×ＭＦＲ(Ａ)≧ＭＦＲ(Ｂ) （１）A laminated biaxially oriented polypropylene-based resin film in which a base material layer (A) made of a crystalline polypropylene-based resin, an intermediate layer (B), and a heat-fusible layer (C) having a melting point of 150 ° C. or lower are sequentially laminated. The melt flow rate (MFR (A)) of the base layer (A), the melt flow rate (MFR (B)) of the intermediate layer (B), and the melt flow rate (MFR (C) of the heat-fusible layer (C) ) Satisfies the following formula (1), and the resin for forming the intermediate layer (B) is one kind of resin for forming the base layer (A) and the resin for forming the heat fusion layer (C). A heat-sealable laminated polypropylene resin film comprising the above.
MFR (C) ≧ 2 × MFR (A) ≧ MFR (B) (1)
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| JP2002027640A JP4120227B2 (en) | 2002-02-05 | 2002-02-05 | Heat-sealable laminated polypropylene resin film and package |
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| JP2002027640A JP4120227B2 (en) | 2002-02-05 | 2002-02-05 | Heat-sealable laminated polypropylene resin film and package |
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Cited By (1)
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| US10773498B2 (en) | 2015-05-28 | 2020-09-15 | Toppan Printing Co., Ltd. | Laminate film and packaging bag |
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| JP2005104152A (en) * | 2003-09-12 | 2005-04-21 | Toyobo Co Ltd | Heat-sealable laminated polypropylene resin film and package |
| JP4747538B2 (en) * | 2003-09-12 | 2011-08-17 | 東洋紡績株式会社 | Heat-sealable laminated polypropylene resin film and package |
| US7879439B2 (en) | 2004-03-18 | 2011-02-01 | Toyo Boseki Kabushiki Kaisha | Polypropylene laminate film, and package comprising the same |
| KR101096846B1 (en) * | 2004-03-26 | 2011-12-22 | 토요 보세키 가부시기가이샤 | Heat-sealable layered polypropylene resin film and package |
| JP4613571B2 (en) * | 2004-03-26 | 2011-01-19 | 東洋紡績株式会社 | Heat-sealable polypropylene resin laminated film and package |
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| JP4872344B2 (en) * | 2005-12-28 | 2012-02-08 | 東洋紡績株式会社 | Heat-sealable laminated polypropylene resin film and package |
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| WO2010115312A1 (en) * | 2009-04-10 | 2010-10-14 | Dow Global Technologies Inc. | High performance sealable coextruded biaxially oriented polypropylene film |
| JP6984593B2 (en) * | 2016-03-30 | 2021-12-22 | 東洋紡株式会社 | Polypropylene resin multilayer film and packaging using it |
| WO2018117268A1 (en) * | 2016-12-22 | 2018-06-28 | 凸版印刷株式会社 | Multilayer stretched film, substrate for decorative sheets, decorative sheet and decorative panel |
| JP2020157715A (en) * | 2019-03-28 | 2020-10-01 | 大日本印刷株式会社 | Laminate for packaging material, and packaging material |
| JP7471053B2 (en) * | 2018-12-25 | 2024-04-19 | グンゼ株式会社 | Film used for packaging bags for fruits and vegetables |
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| US10773498B2 (en) | 2015-05-28 | 2020-09-15 | Toppan Printing Co., Ltd. | Laminate film and packaging bag |
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