JP6012064B2 - Polyethylene heat-shrinkable multilayer film for integrated packaging - Google Patents
Polyethylene heat-shrinkable multilayer film for integrated packaging Download PDFInfo
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- JP6012064B2 JP6012064B2 JP2009275512A JP2009275512A JP6012064B2 JP 6012064 B2 JP6012064 B2 JP 6012064B2 JP 2009275512 A JP2009275512 A JP 2009275512A JP 2009275512 A JP2009275512 A JP 2009275512A JP 6012064 B2 JP6012064 B2 JP 6012064B2
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- 238000004806 packaging method and process Methods 0.000 title claims description 124
- -1 Polyethylene Polymers 0.000 title claims description 33
- 239000004698 Polyethylene Substances 0.000 title claims description 29
- 229920000573 polyethylene Polymers 0.000 title claims description 29
- 229920000092 linear low density polyethylene Polymers 0.000 claims description 28
- 239000004707 linear low-density polyethylene Substances 0.000 claims description 28
- 239000012792 core layer Substances 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 20
- 239000004700 high-density polyethylene Substances 0.000 claims description 19
- 229920001903 high density polyethylene Polymers 0.000 claims description 17
- 239000010410 layer Substances 0.000 claims description 14
- 239000002344 surface layer Substances 0.000 claims description 13
- 239000012968 metallocene catalyst Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000009825 accumulation Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 229920005678 polyethylene based resin Polymers 0.000 claims description 4
- 238000006116 polymerization reaction Methods 0.000 claims description 2
- 229920005989 resin Polymers 0.000 description 23
- 239000011347 resin Substances 0.000 description 23
- 235000013361 beverage Nutrition 0.000 description 17
- 229920006257 Heat-shrinkable film Polymers 0.000 description 16
- 238000002844 melting Methods 0.000 description 16
- 230000008018 melting Effects 0.000 description 16
- 239000002994 raw material Substances 0.000 description 15
- 238000010438 heat treatment Methods 0.000 description 13
- 238000001816 cooling Methods 0.000 description 12
- 239000000047 product Substances 0.000 description 11
- 238000007789 sealing Methods 0.000 description 11
- 229920013716 polyethylene resin Polymers 0.000 description 10
- 230000002087 whitening effect Effects 0.000 description 8
- 239000003054 catalyst Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000004743 Polypropylene Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 230000037303 wrinkles Effects 0.000 description 3
- 235000013405 beer Nutrition 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 235000011389 fruit/vegetable juice Nutrition 0.000 description 2
- 238000004898 kneading Methods 0.000 description 2
- 229920004889 linear high-density polyethylene Polymers 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 235000014214 soft drink Nutrition 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
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Description
本発明は、缶、瓶、ペットボトルなどの集積包装に適した機械適性、ヒートシール性及び包装仕上がり性のよい集積包装用ポリエチレン系熱収縮性多層フィルムに関するものである。 The present invention relates to a polyethylene-based heat-shrinkable multilayer film for integrated packaging that is suitable for integrated packaging such as cans, bottles, and PET bottles and has good heat sealability and packaging finish.
従来から被包装物を熱収縮性フィルムで収縮包装することは、被包装物の保護、不規則な形状の被包装物も美しく包装できること、複数の被包装物を強固に結束できること、及び自動包装に適していることなどの理由から広く利用されている。これらの収縮包装に使用される熱収縮性フィルムは、被包装物の形状、出荷形態、包装速度、包装機械等に応じて選択され、例えばスリーブ収縮包装、オーバーラップ収縮包装、ストレッチ収縮包装等があり、包装方式によって要求される特性も異なっている。特に缶ビール、缶ジュース、瓶詰め、清涼飲料水などの集積包装には、内容物が重量物であるために包装物が破れないように耐引裂性や耐衝撃性が要求され、更にシール部の破れが無い程度の十分なシール適性等が要求される。 Traditionally, shrink-wrapping a package with a heat-shrinkable film protects the package, can package irregularly-shaped packages beautifully, can firmly bundle multiple packages, and automatic packaging Widely used for reasons such as being suitable for The heat-shrinkable film used for these shrink wrapping is selected according to the shape of the package, the shipping form, the packaging speed, the packaging machine, etc., for example, sleeve shrink wrap, overlap shrink wrap, stretch shrink wrap, etc. There are different characteristics required for each packaging method. Especially for integrated packaging such as canned beer, canned juice, bottling, and soft drinks, the contents are heavy, so tear resistance and impact resistance are required to prevent the package from being torn. Sufficient sealing suitability that does not cause tearing is required.
スリーブ包装の場合、これら要求特性を満足すべく、ポリエチレンを主原料としたインフレーション法で製造されたフィルムが従来から広く用いられている。インフレーション法で製造されたフィルムは、原料の融点以上の温度で延伸されるため、低温シール性には優れるが、透明性や光沢性に劣り、柔らかくて伸び易く、耐熱性と収縮性に乏しい。そのため、十分な結束力と強度を得るため５０μm以上の厚みのフィルムが多く、包装後は多量のゴミとなっている。 In the case of sleeve packaging, a film produced by an inflation method using polyethylene as a main raw material has been widely used so far to satisfy these required characteristics. A film produced by the inflation method is stretched at a temperature equal to or higher than the melting point of the raw material, and thus has excellent low-temperature sealing properties, but is inferior in transparency and gloss, soft and easy to stretch, and poor in heat resistance and shrinkage. Therefore, in order to obtain a sufficient binding force and strength, there are many films having a thickness of 50 μm or more, and a large amount of garbage is formed after packaging.
二軸延伸されスリーブ包装にも適するフィルムとして、特許第１１０６８３７号公報にはポリプロピレンを主原料としてチューブラー延伸後にＭＤに再延伸を行った熱収縮性フィルムの製造方法が提案されている。しかしながら、該公報で得られたフィルムは、ポリプロピレン系単層フィルムであるため、例えば図１に示すような包装形態で仮包装すると、底面のシールができず、小さな傷などからフィルムが容易に裂けて集積包装が解けてしまうことがあった。また、チューブラー延伸の延伸倍率が小さいため、透明性や光沢性が十分ではなく、低温収縮性に劣るため収縮包装後にシワが多く、高温で収縮させると被包装物のラベルが溶けるなどの問題があった。 As a film that is biaxially stretched and is suitable for sleeve packaging, Japanese Patent No. 106837 proposes a method for producing a heat-shrinkable film in which polypropylene is the main raw material and tubular stretching is performed and MD is re-stretched. However, since the film obtained in this publication is a polypropylene-based single-layer film, for example, if it is temporarily packaged in a packaging form as shown in FIG. 1, the bottom cannot be sealed, and the film is easily torn from small scratches. As a result, the integrated packaging sometimes unraveled. In addition, because the draw ratio of tubular stretching is small, transparency and gloss are not sufficient, and low temperature shrinkability is inferior, so there are many wrinkles after shrink packaging, and the label of the package is melted when shrinking at high temperature was there.
一方、オーバーラップ包装の場合、ポリプロピレン等を主原料としてチューブラー延伸法、テンター同時二軸延伸法やテンター逐次二軸延伸法等の原料の融点より低い温度で延伸する方法で製造されたフィルムが一般的に用いられ、被包装物をよりタイトに収縮包装できるようにＭＤとＴＤの収縮率がバランスしていて、厚みも５０μm以下と薄く、透明光沢性にも優れている。オーバーラップ包装の場合、単一の被包装物を収縮包装することがほとんどであり、被包装物の保護等を目的に使用することが多い。前述したようにポリプロピレン系を主原料とするフィルムは、耐引き裂き性、低温収縮性に劣るため、集積包装、特に重量物の集積包装には適用されていないのが実状である。このような問題を解決すべく、特許第３０６８９２０号公報にはポリエチレンを主原料に用いたチューブラー延伸で製造された熱収縮性フィルムが提案されている。しかしながら、該公報で得られたフィルムは、溶断シールするとピンホールの発生が多く、収縮包装後にシール部から破れる問題があった。更に、オーバーラップ包装は収縮前の仮包装袋の大きさが被包装物の大きさよりも大きく、即ち余裕率が２０〜３０％程度になる包装形態であるため、これらのオーバーラップ包装用フィルムで集積包装を行うと、収縮力が減じられてしまい、結束力が小さくなってしまう欠点があった。 On the other hand, in the case of overlap packaging, a film produced by a method of stretching at a temperature lower than the melting point of the raw material, such as a tubular stretching method, a tenter simultaneous biaxial stretching method or a tenter sequential biaxial stretching method, using polypropylene or the like as a main raw material. Generally used, the shrinkage ratio of MD and TD is balanced so that the packaged object can be shrink-wrapped more tightly, the thickness is as thin as 50 μm or less, and the transparent glossiness is also excellent. In the case of overlap packaging, a single packaged object is mostly shrink-wrapped, and is often used for the purpose of protecting the packaged object. As described above, a film mainly made of polypropylene is inferior in tear resistance and low-temperature shrinkage, and therefore is not applied to integrated packaging, particularly heavy packaging. In order to solve such problems, Japanese Patent No. 3068820 proposes a heat-shrinkable film manufactured by tubular stretching using polyethylene as a main raw material. However, the film obtained in the above publication has a problem that pinholes are often generated when melt-sealed, and the film is torn from the sealed portion after shrink wrapping. Furthermore, since the overlap packaging is a packaging form in which the size of the temporary packaging bag before shrinkage is larger than the size of the article to be packaged, that is, the margin ratio is about 20 to 30%. When integrated packaging is performed, the shrinkage force is reduced and the binding force is reduced.
また、上述したようなオーバーラップ包装用ポリエチレン系熱収縮性フィルムで前記図１の包装形態で包装を行うと、ＭＤの収縮力が不足して十分な結束力が得られず、反対にＴＤの収縮が大きくなりすぎて被包装物を十分に覆うことができない、或いは収縮後に印刷柄がＴＤに大きく歪むことがあった。 Further, when packaging is performed in the packaging form of FIG. 1 with the above-described polyethylene-based heat-shrinkable film for overlap packaging, the shrinkage force of MD is insufficient and sufficient binding force cannot be obtained. The shrinkage becomes too large to sufficiently cover the packaged object, or the printed pattern may be greatly distorted to TD after shrinkage.
本発明は、結束力が高く、自動包装機適性に優れ、薄くても十分な強度を有し、収縮包装後も透明性光沢性に優れ、また低温ヒートシール性、低温収縮性、耐熱性によってスリーブ包装に特に適し、厚みが薄いために廃棄されるフィルムの量が減量できる集積包装用ポリエチレン系の熱収縮性フィルムを提供することを目的とする。 The present invention has high binding power, excellent suitability for automatic packaging machines, has sufficient strength even if it is thin, has excellent transparency and glossiness after shrink wrapping, and has low temperature heat sealability, low temperature shrinkability, and heat resistance. The object is to provide a polyethylene-based heat-shrinkable film for integrated packaging, which is particularly suitable for sleeve packaging and can reduce the amount of film discarded due to its thin thickness.
本発明者らは、フィルムの原料と層構成、及び延伸加工条件を特定することによって、このような要求特性を満足するフィルムが得られることを見出した。
即ち、本発明は、
（１）ポリエチレン系多層フィルムを二軸延伸によりＭＤ及びＴＤ共に延伸倍率３．０倍以上で延伸した後、熱ロール処理により６０〜１００℃の温度でＭＤに１．１〜３．０倍に延伸して得られる集積包装用ポリエチレン系熱収縮性多層フィルム、
（２） 前記ポリエチレン系多層フィルムが、少なくとも３層以上の多層であり、両表層のポリエチレン系樹脂の平均密度（ａ）と芯層のポリエチレン系樹脂の平均密度（ｂ）が（ａ）≦（ｂ）であることを特徴とする前記（１）記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（３） 前記ポリエチレン系多層フィルムが、少なくとも片方の表層が密度０．９００〜０．９２０g/cm3の直鎖状低密度ポリエチレンからなり、芯層が密度０．９１５〜０．９２５g/cm3の直鎖状低密度ポリエチレン５０〜１００重量％と、密度０．９３０〜０．９６５g/cm3の高密度ポリエチレン０〜５０重量％との組成物からなることを特徴とする前記（１）または(２)に記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（４） 前記芯層に用いる高密度ポリエチレンが、メタロセン系触媒で重合して製造された、密度０．９３０〜０．９５０g/cm3の高密度ポリエチレンであることを特徴とする前記（１）〜(３)に記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（５） フィルム全体の厚みが４０μm以下であることを特徴とする前記（１）〜(４)に記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（６） フィルムのヘーズが８％以下、グロスが１００％以上であり、８０℃の熱収縮率のＭＤが５〜２０％且つＴＤが５％未満であり、８０〜１００℃のヒートシール強度が1N/cm以上であることを特徴とする前記（３）〜(５)のいずれか一つに記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（７）１２０℃の熱収縮率のＭＤとＴＤが共に５０％以上であることを特徴とする前記（３）〜(６)のいずれか一つに記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（８）引張破断伸度がＭＤとＴＤ共に３００％以下であることを特徴とする前記（３）〜(７)のいずれか一つに記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
（９）スリーブ方式の集積包装に用いることを特徴とする前記（１）〜(８)のいずれか一つに記載の集積包装用ポリエチレン系熱収縮性多層フィルム、
に係るものである。
The present inventors have found that a film satisfying such required characteristics can be obtained by specifying the raw material and layer structure of the film, and the stretching processing conditions.
That is, the present invention
(1) A polyethylene-based multilayer film is stretched at a stretching ratio of 3.0 times or more for both MD and TD by biaxial stretching, and then heated to a temperature of 60 to 100 ° C. to a size of 1.1 to 3.0 times by hot roll treatment. Polyethylene heat-shrinkable multilayer film for integrated packaging obtained by stretching,
(2) The polyethylene-based multilayer film is a multilayer of at least three layers, and the average density (a) of the polyethylene-based resin on both surface layers and the average density (b) of the polyethylene-based resin on the core layer are (a) ≦ ( b) a polyethylene heat-shrinkable multilayer film for integrated packaging according to the above (1),
(3) The polyethylene-based multilayer film, at least one of the surface layer is made of linear low density polyethylene having a density of 0.900~0.920g / cm 3, the core layer density 0.915~0.925g / cm 3 The linear low density polyethylene of 50 to 100% by weight and the density of 0.930 to 0.965 g / cm 3 of high density polyethylene of 0 to 50% by weight of the above (1) or A polyethylene-based heat-shrinkable multilayer film for integrated packaging according to (2),
(4) The high density polyethylene used for the core layer is a high density polyethylene having a density of 0.930 to 0.950 g / cm 3 produced by polymerization with a metallocene catalyst. -Polyethylene heat-shrinkable multilayer film for integrated packaging according to (3),
(5) The polyethylene-based heat-shrinkable multilayer film for integrated packaging according to any one of (1) to (4) above, wherein the thickness of the entire film is 40 μm or less,
(6) The haze of the film is 8% or less, the gloss is 100% or more, the MD of the thermal shrinkage at 80 ° C. is 5 to 20%, the TD is less than 5%, and the heat seal strength at 80 to 100 ° C. The polyethylene heat-shrinkable multilayer film for integrated packaging according to any one of the above (3) to (5), which is 1 N / cm or more,
(7) The heat-shrinkable MD and TD at 120 ° C. are both 50% or more, and the polyethylene-based heat-shrinkable multilayer for integrated packaging according to any one of the above (3) to (6) the film,
(8) The polyethylene-based heat-shrinkable multilayer film for integrated packaging according to any one of (3) to (7), wherein the tensile breaking elongation is 300% or less for both MD and TD,
(9) The polyethylene-based heat-shrinkable multilayer film for integrated packaging according to any one of (1) to (8), which is used for sleeve-type integrated packaging,
It is related to.
本発明の集積包装用ポリエチレン系熱収縮フィルムは、自動包装機適性に優れ、集積包装において商品を十分な力で結束することができるため、荷崩れを起こさない。また、従来からスリーブ集積包装に使用されてきているインフレーション法で製造されたフィルムよりも、収縮包装後の透明性光沢性が良好であるためにディスプレイ効果が高いものである。また低温ヒートシール性、低温収縮性、耐熱性があるため、スリーブ包装にも適する。さらに、薄くても十分な強度を有するためフィルムを薄くすることができ、その結果、包装後に廃棄されるフィルムの量を減量することもできるため、環境に対する負荷が軽減されるものである。 The polyethylene heat-shrinkable film for integrated packaging of the present invention is excellent in suitability for automatic packaging machines, and can bind products with sufficient force in integrated packaging, and therefore does not collapse. In addition, the display effect is higher than the film produced by the inflation method that has been conventionally used for sleeve integrated packaging because the transparency glossiness after shrink packaging is better. It is also suitable for sleeve packaging due to its low temperature heat sealability, low temperature shrinkability, and heat resistance. Furthermore, since the film has sufficient strength even if it is thin, the film can be thinned. As a result, the amount of the film discarded after packaging can be reduced, thereby reducing the burden on the environment.
以下に本発明の実施の形態を以下説明する。
本発明は、まず未延伸のポリオレフィン系多層フィルムについて二軸延伸を行う。二軸延伸のＭＤおよびＴＤの延伸倍率はそれぞれ３．０倍以上、好ましくは３．５倍以上、更に好ましくは４．０倍以上がよい。ＭＤ、ＴＤそれぞれの延伸倍率が３．０倍未満であると、良好な透明性と光沢性、フィルム強度、及び十分な収縮性が得られない。特に、ＭＤの収縮性については再延伸で再度付与することができるが、ＴＤの収縮性については、延伸倍率が３．０倍未満になると幅方向の収縮が不足して、包装品にシワが残るなど十分な仕上がりが得られない。例えば、図１に示すようなスリーブ包装では、被包装物の幅よりフィルム幅を大きく包装するため、スリーブ箇所にフィルムが収縮せずに余り、大変見栄えが悪くなってしまう。
Embodiments of the present invention will be described below.
In the present invention, biaxial stretching is first performed on an unstretched polyolefin-based multilayer film. The biaxial stretching MD and TD stretching ratios are each 3.0 times or more, preferably 3.5 times or more, and more preferably 4.0 times or more. When the draw ratios of MD and TD are less than 3.0 times, good transparency and gloss, film strength, and sufficient shrinkage cannot be obtained. In particular, the shrinkage of MD can be reapplied by re-stretching. However, as for the shrinkage of TD, when the draw ratio is less than 3.0 times, the shrinkage in the width direction is insufficient, and the packaged product is wrinkled. A sufficient finish such as remaining is not obtained. For example, in the case of sleeve packaging as shown in FIG. 1, since the film width is larger than the width of the article to be packaged, the film does not shrink at the sleeve portion, and the appearance is very poor.
次いで二軸延伸後のフィルムについて、ＭＤに再延伸を行う。この再延伸は、熱ロールを用いて、原料の融点以下の温度である６０〜１００℃の温度範囲でＭＤに１．１〜３．０倍に延伸することによって、低温収縮性、特にＭＤの収縮性に優れ、集積包装における結束力に優れたフィルムが得られる。 Next, the film after biaxial stretching is re-stretched in MD. This re-stretching is performed at a temperature range of 60 to 100 ° C., which is a temperature equal to or lower than the melting point of the raw material, by using a heat roll, and stretched to MD by 1.1 to 3.0 times, thereby causing low temperature shrinkage, particularly MD. A film excellent in shrinkability and excellent in binding power in integrated packaging can be obtained.
再延伸を行う温度は６０〜１００℃が好ましく、７０〜９０℃が更に好ましい。６０℃未満の温度では熱ロール等のモーター負荷上昇で再延伸が困難となり、１００℃を超える温度では、特に芯層の融点に近い温度で再延伸するとＭＤの収縮性が十分得られず、収縮力も小さくなるため十分な結束力が得られなくなってしまう。また、１００℃を超える温度で緊張熱処理や弛緩処理の後ＭＤに延伸を行っても、二軸延伸で付与したＭＤとＴＤの延伸配向が完全に緩和してしまって、耐引き裂き性などの強度が著しく低下してしまうとともに、ＴＤの収縮がなくなって結束力が不足する。 The temperature at which restretching is performed is preferably 60 to 100 ° C, more preferably 70 to 90 ° C. If the temperature is lower than 60 ° C, re-stretching becomes difficult due to an increase in the load of a motor such as a hot roll. If the temperature exceeds 100 ° C, re-stretching particularly at a temperature close to the melting point of the core layer does not provide sufficient MD shrinkage and shrinkage Since the force becomes small, a sufficient binding force cannot be obtained. In addition, even if the MD is stretched after the tension heat treatment or relaxation treatment at a temperature exceeding 100 ° C., the stretching orientation of MD and TD imparted by biaxial stretching is completely relaxed, and the strength such as tear resistance. Significantly decreases, and the shrinkage of TD disappears and the binding force is insufficient.
再延伸の倍率は、１．１〜３．０倍が好ましく、１．２〜２．０倍が更に好ましい。再延伸の倍率が１．１倍未満の場合集積包装時の結束力が不足する。再延伸倍率が３．０倍を超える場合は、熱ロール上のフィルム切れ防止やロールモーター負荷上昇を防止するために熱ロール温度を高く設定しなければならず、本発明の効果を失ってしまう。 The redraw ratio is preferably 1.1 to 3.0 times, and more preferably 1.2 to 2.0 times. When the redrawing ratio is less than 1.1 times, the binding force at the time of stacking and packaging is insufficient. When the re-stretch ratio exceeds 3.0 times, the hot roll temperature must be set high to prevent film breakage on the hot roll and to prevent the roll motor load from increasing, and the effect of the present invention will be lost. .
本発明に用いる原料は、ポリエチレン系の原料であれば耐引き裂き性等十分な強度を有し、再延伸によってＭＤの収縮性と結束力に優れる集積包装用フィルムを得ることができる。 If the raw material used for this invention is a polyethylene-type raw material, it has sufficient intensity | strength, such as tear resistance, and can obtain the film | membrane for integrated packaging which is excellent in the shrinkage | contraction property and binding force of MD by redrawing.
特にスリーブ包装を行う場合は、低温シール性と耐熱性の両立が必要であり、ポリエチレン系フィルムの層構成を特定するとこれらの要求特性を満足するフィルムが得られる。即ち、少なくとも３層以上の多層であり、両表層のポリエチレン系樹脂の平均密度（ａ）と芯層のポリエチレン系樹脂の平均密度（ｂ）が（ａ）≦（ｂ）であることを特徴とする集積包装用熱収縮性フィルムである。
図１のような包装形態の場合、収縮トンネル内で、先に底面がシールされ、その後フィルムが収縮することが望ましいため、表層のポリエチレン系樹脂の平均密度が芯層のポリエチレン系樹脂の平均密度よりも低い、或いは表層のポリエチレン系樹脂の融点が芯層のポリエチレン系樹脂の融点よりも低いことが必要である。表層のポリエチレン系樹脂の平均密度が芯層のポリエチレン系樹脂の平均密度よりも高くなると、底面がシールされないまま収縮してしまうため、特に軽量の被包装物の場合には底面のフィルムの重なりがなくなって、収縮包装できなくなるからである。
In particular, when sleeve packaging is performed, it is necessary to satisfy both low temperature sealing properties and heat resistance. When the layer structure of the polyethylene film is specified, a film satisfying these required characteristics can be obtained. That is, it is a multilayer of at least 3 layers, and the average density (a) of the polyethylene resin of both surface layers and the average density (b) of the polyethylene resin of the core layer are (a) ≦ (b) It is a heat shrinkable film for integrated packaging.
In the case of the packaging form as shown in FIG. 1, it is desirable that the bottom surface is sealed first in the shrink tunnel, and then the film shrinks, so that the average density of the polyethylene resin of the surface layer is the average density of the polyethylene resin of the core layer. Or the melting point of the polyethylene resin in the surface layer must be lower than the melting point of the polyethylene resin in the core layer. If the average density of the polyethylene resin in the surface layer is higher than the average density of the polyethylene resin in the core layer, the bottom surface shrinks without being sealed, so in the case of a lightweight package, the bottom film overlaps. This is because it becomes impossible to shrink-wrap.
更に、特定のポリエチレン系樹脂を用いると、低温シール性と耐熱性が両立すると供に、低温収縮性と仕上がり性を満足するフィルムが得られやすい。即ち、少なくとも片方の表層が密度０．９００〜０．９２０g/cm3の直鎖状低密度ポリエチレンからなり、芯層が密度０．９１５〜０．９２５g/cm3の直鎖状低密度ポリエチレン５０〜１００重量％と、密度０．９３０〜０．９６５g/cm3の高密度ポリエチレン０〜５０重量％との組成物からなることを特徴とする集積包装用熱収縮性フィルムである。 Further, when a specific polyethylene resin is used, a film satisfying both the low temperature shrinkability and the finishing property can be easily obtained while the low temperature sealing property and the heat resistance are compatible. That is, at least one of the surface layer is made of linear low density polyethylene having a density of 0.900~0.920g / cm 3, linear low density polyethylene 50 of the core layer density 0.915~0.925g / cm 3 A heat-shrinkable film for integrated packaging, comprising a composition of ˜100% by weight and 0-50% by weight of high density polyethylene having a density of 0.930 to 0.965 g / cm 3 .
表層の樹脂は、低温シール性を得る目的では高圧法低密度ポリエチレンでも良いが、フィルムの強度や透明性から直鎖状低密度ポリエチレンが好ましく、更には低温シール性やホットタック性、耐ブロッキング性等が両立するメタロセン系触媒の直鎖状低密度ポリエチレンがより好ましい。直鎖状低密度ポリエチレンの密度は、密度０．９００〜０．９２０g/cm3が好ましく、更には密度０．９０５〜０．９１５g/cm3がより好ましい。密度０．９００g/cm3未満では、原料ペレットやフィルム状態でのブロッキングが著しくなって製造工程におけるトラブルの要因となりやすく、０．９２０g/cm3超では、スリーブ集積包装の際にフィルムのシール温度域が収縮温度域よりも高温側になって、シールができていないまま収縮するため集積包装ができなくなってしまうことがある。 The surface resin may be high-pressure low-density polyethylene for the purpose of obtaining low-temperature sealing properties, but linear low-density polyethylene is preferable from the strength and transparency of the film, and further low-temperature sealing properties, hot tack properties, and blocking resistance. It is more preferable to use a linear low-density polyethylene that is a metallocene catalyst that is compatible with each other. The density of the linear low density polyethylene is preferably the density 0.900~0.920g / cm 3, even the density 0.905~0.915g / cm 3 more preferred. If the density is less than 0.900 g / cm 3 , blocking in the raw material pellets or film state becomes remarkable, which is likely to cause troubles in the manufacturing process. If it exceeds 0.920 g / cm 3 , the sealing temperature of the film during sleeve integrated packaging Since the region becomes higher than the shrinkage temperature region and shrinks without being sealed, the integrated packaging may not be possible.
芯層の樹脂は直鎖状低密度ポリエチレン、もしくは直鎖状低密度ポリエチレンと高密度ポリエチレンの混合物が好ましい。直鎖状低密度ポリエチレンの密度は０．９１５〜０．９２５g/cm3が好ましい。密度０．９１５g/cm3未満ではフィルム全体の耐熱性が不足するため、収縮包装の際の収縮トンネル内でフィルムが白化や溶融穴開き状態になりやすく、密度０．９２５g/cm3超では低温収縮性も得られにくくなって仕上がり性が低下する。高密度ポリエチレンの密度は０．９３０〜０．９６５g/cm3が好ましく、更には０．９３０〜０．９５０g/cm3がより好ましい。高密度ポリエチレンは耐熱性に向上やフィルムの伸び抑制するために混合するが、密度０．９３０g/cm3未満では耐熱性向上や伸び抑制の効果が得られにくく、密度０．９６５g/cm3超ではフィルムの耐引裂性の低下や収縮温度域が高温側になりすぎてしまう。 The resin of the core layer is preferably linear low density polyethylene or a mixture of linear low density polyethylene and high density polyethylene. The density of the linear low density polyethylene is preferably 0.915 to 0.925 g / cm 3 . Because it is less than a density 0.915 g / cm 3 to insufficient heat resistance of the entire film, easy film in shrink tunnel during shrink packaging ready opening whitening or melting holes, density 0.925 g / cm 3 in greater low temperature It becomes difficult to obtain shrinkage and the finish is reduced. The density of high-density polyethylene is preferably 0.930~0.965g / cm 3, more and more preferably 0.930~0.950g / cm 3. High density polyethylene is mixed in order to stretch the suppression of increase and film in heat resistance, difficult to obtain the effect of improving heat resistance and elongation suppression is less than a density 0.930 g / cm 3, density of 0.965 g / cm 3 greater In this case, the tear resistance of the film is lowered and the shrinkage temperature region is too high.
直鎖状低密度ポリエチレンと高密度ポリエチレンを混合する場合、直鎖状低密度ポリエチレン５０〜１００重量％と高密度ポリエチレン０〜５０重量％の混合物が好ましい。高密度ポリエチレンが５０ｗｔ％超混合されるとフィルムの耐引裂性が著しく低下し、収縮温度域が高温側になりすぎて美麗な収縮包装体が得られにくくなる。 When mixing a linear low density polyethylene and a high density polyethylene, the mixture of a linear low density polyethylene 50-100 weight% and a high density polyethylene 0-50 weight% is preferable. When high density polyethylene exceeds 50 wt%, the tear resistance of the film is remarkably lowered, and the shrinkage temperature range becomes too high, making it difficult to obtain a beautiful shrink package.
更に、高密度ポリエチレンがメタロセン系触媒で重合して製造された密度０．９３０〜０．９５０g/cm3の場合、従来のチーグラー系やフィリップス系触媒で重合された高密度ポリエチレンを用いた場合に比べて、引裂強度や衝撃強度等が高く、重量のある内容物の包装に適するため、更に好ましい。 Furthermore, in the case of a density of 0.930 to 0.950 g / cm 3 produced by polymerizing a high-density polyethylene with a metallocene catalyst, when a high-density polyethylene polymerized with a conventional Ziegler-type or Philips-type catalyst is used. Compared to high tear strength, impact strength and the like, and suitable for packaging heavy contents, it is more preferable.
尚、これらのポリエチレン系樹脂には必要に応じて滑剤、アンチブロッキング剤、粘着性付与剤、帯電防止剤、防曇剤等の添加剤を必要に応じて加えてもなんらさしつかえない。 It should be noted that additives such as lubricants, antiblocking agents, tackifiers, antistatic agents, antifogging agents and the like can be added to these polyethylene resins as necessary.
本発明における二軸延伸法とロール再延伸法について、以下に詳細に説明するが、フィルムを製造する際の二軸延伸は公知の方法で行うことができ、本報ではチューブラー延伸法にて具体的に説明する。 The biaxial stretching method and roll restretching method in the present invention will be described in detail below, but biaxial stretching at the time of producing a film can be performed by a known method. In this report, the tubular stretching method is used. This will be specifically described.
直鎖状低密度ポリエチレンが両表層、直鎖状低密度ポリエチレン、若しくは直鎖状低密度ポリエチレンと高密度ポリエチレンの混合物が芯層となるように３台の押出機により溶融混練し、三層環状ダイより管状に共押出し、延伸することなく一旦急冷固化してチューブ状未延伸フィルムを作製する。得られたチューブ状未延伸フィルムを例えば図２で示すようなチューブラー延伸装置に供給し、高度な配向が可能な温度範囲、例えば芯層の融点以下１０℃、好ましくは融点以下１５℃よりも低い温度で、２つのニップロール間の周速比でＭＤに延伸すると同時に、チューブ内部にガス圧を適用して膨脹させてＴＤに延伸することにより同時二軸配向を起こさせる。延伸倍率は、優れた強度、収縮率などの物性を得るためにはＭＤとＴＤ共に３．０倍以上、好ましくは４．０倍以上、更に好ましくは４．５倍以上に延伸するのが好適である。 Three layers of linear low-density polyethylene are melt-kneaded by three extruders so that both surface layers, linear low-density polyethylene, or a mixture of linear low-density polyethylene and high-density polyethylene forms a core layer It is coextruded into a tubular shape from a die, and then rapidly cooled and solidified without stretching to produce a tubular unstretched film. The obtained tubular unstretched film is supplied to a tubular stretching apparatus as shown in FIG. 2, for example, and a temperature range in which high orientation is possible, for example, 10 ° C. or lower, preferably 15 ° C. or lower, of the melting point of the core layer. At the same time, the film is stretched in the MD at a peripheral speed ratio between the two nip rolls at the same time, and at the same time, the gas pressure is applied to the inside of the tube to be expanded and stretched to TD to cause simultaneous biaxial orientation. In order to obtain excellent physical properties such as strength and shrinkage, the stretching ratio is preferably 3.0 times or more, preferably 4.0 times or more, more preferably 4.5 times or more for both MD and TD. It is.
チューブラー延伸工程の後に、６０〜１００℃の加温ロールと２０〜４０℃の冷却ロール間にてＭＤに１．１〜３．０倍に延伸し、その後アニーリングを行う。加温ロールと冷却ロールの組み合わせは１対に限らず、２対以上になってもよい。製品厚みは、チューブラー延伸やロール再延伸の延伸倍率を考慮して、チューブ状未延伸フィルムの厚みで調整され、厚み４０μm以下にする。本発明の効果を十分に得るには１０μm以上４０μm以下、更に好ましくは１５μm以上３５μm以下が好ましい。 After the tubular stretching process, the film is stretched 1.1 to 3.0 times in the MD between a heating roll at 60 to 100 ° C. and a cooling roll at 20 to 40 ° C., and then annealed. The combination of the heating roll and the cooling roll is not limited to one pair, and may be two or more pairs. The product thickness is adjusted by the thickness of the tubular unstretched film in consideration of the stretch ratio of tubular stretching and roll restretching, and the thickness is made 40 μm or less. In order to sufficiently obtain the effects of the present invention, it is preferably 10 μm or more and 40 μm or less, more preferably 15 μm or more and 35 μm or less.
本発明のフィルムは、ヘーズが８％以下、グロスが１００％以上であり、８０℃の熱収縮率のＭＤが５〜２０％且つＴＤが５％未満であり、８０〜１００℃のヒートシール強度が1N/cm以上であることが特徴である。原料の融点よりも低い温度で延伸されるため良好な透明性及び光沢性が得られ、従来のインフレーション法で製造されたフィルムより優位となる。 The film of the present invention has a haze of 8% or less, a gloss of 100% or more, a heat shrinkage MD at 80 ° C. of 5 to 20% and a TD of less than 5%, and a heat seal strength of 80 to 100 ° C. Is characterized by being 1 N / cm or more. Since the film is stretched at a temperature lower than the melting point of the raw material, good transparency and gloss can be obtained, which is superior to a film produced by a conventional inflation method.
熱収縮率は、芯層原料の密度や融点、チューブラー延伸やロール再延伸の温度と延伸倍率によって調整されるが、ＭＤ再延伸温度を６０〜１００℃でＭＤ延伸倍率を１．１〜３．０倍にすることによって、８０℃の熱収縮率のＭＤが５〜１５％且つＴＤが５％未満のアンバランスなフィルムが得られ、ＭＤに結束性とタイト感がある収縮が可能となり、同時にＴＤに過剰収縮がないため、集積包装、特にスリーブ包装に好適なフィルムが得られるようになる。更に、例えば図１に示すようなスリーブ包装では、スリーブ箇所にフィルムが収縮せずに余り、大変見栄えが悪くなってしまうため、１２０℃の熱収縮率のＭＤとＴＤが共に５０％以上であることが好ましい。 The heat shrinkage ratio is adjusted by the density and melting point of the core layer raw material, the temperature of tubular stretching and roll re-stretching, and the stretching ratio. The MD re-stretching temperature is 60 to 100 ° C. and the MD stretching ratio is 1.1 to 3. By setting the ratio to 0.0, an unbalanced film having an MD with a thermal shrinkage of 80 ° C. of 5 to 15% and a TD of less than 5% can be obtained. At the same time, since there is no excessive shrinkage of TD, a film suitable for integrated packaging, particularly sleeve packaging, can be obtained. Further, in the case of sleeve packaging as shown in FIG. 1, for example, the film does not shrink at the sleeve portion, and the appearance is very poor. Therefore, both the MD and TD of 120 ° C. thermal shrinkage are 50% or more. It is preferable.
ヒートシール温度は、主として表層の原料の密度や融点によって調整され、８０〜１００℃のいずれかの温度以上でヒートシール強度が1N/cm以上になることが必要である。前述したように図１に示したスリーブ包装を行う場合、収縮前に底面のシール強度が十分になった状態で収縮が開始するので、綺麗な収縮包装品が得られるようになる。反対に１００℃を超えた温度でヒートシール強度が1N/cm以上になるような場合は、底面のシールが完成しない状態でフィルムが大きく収縮するため、底面の２枚のフィルムが離れて収縮包装ができない、或いは、底面のシール強度が不十分な状態となって、包装品を持ち上げた際に底面から被包装物が落下する、などの不具合が発生する。 The heat seal temperature is mainly adjusted by the density and melting point of the raw material of the surface layer, and it is necessary that the heat seal strength be 1 N / cm or more at a temperature of 80 to 100 ° C. or higher. As described above, when the sleeve packaging shown in FIG. 1 is performed, the shrinkage starts in a state where the sealing strength of the bottom surface is sufficient before the shrinkage, so that a beautiful shrink-wrapped product can be obtained. On the other hand, if the heat seal strength exceeds 1 N / cm at a temperature exceeding 100 ° C, the film shrinks greatly without the bottom seal being completed, so the two films on the bottom are separated and shrink-wrapped. Or the sealing strength of the bottom surface becomes insufficient, and when the packaged product is lifted, the packaged item falls from the bottom surface.
更に本発明のフィルムは、引張破断伸度がＭＤとＴＤ共に３００％以下であることが特徴である。例えば、２リットルの飲料ペットボトル６本をスリーブ包装した後、フィルムに指をかけてこれを持ち上げようとした場合、フィルムが伸びてペットボトル同士に隙間ができ、フィルム内部からペットボトルが抜け出てしまうことある。この現象を防止するため、包装に用いるフィルムは、ＭＤとＴＤの引張破断伸度が共に３００％以下でなければならない。 Furthermore, the film of the present invention is characterized in that the tensile elongation at break is 300% or less for both MD and TD. For example, after sleeve-wrapping six 2 liter beverage PET bottles, if you put your finger on the film and try to lift it, the film will stretch to create a gap between the PET bottles, and the PET bottle will come out of the film. It may end up. In order to prevent this phenomenon, the film used for packaging must have a tensile elongation at break of MD and TD of 300% or less.
以下に、本発明を更に詳細に説明する。なお、本発明及び実施例における機械的性質及び物理的性質は以下の方法によって測定した。 Hereinafter, the present invention will be described in more detail. In addition, the mechanical property and physical property in this invention and an Example were measured with the following method.
＜ヘーズ＞ ＪＩＳ Ｋ ７１０５に準拠して、フィルムの透明性について測定した。 <Haze> The transparency of the film was measured in accordance with JIS K 7105.
＜グロス＞ ＪＩＳ Ｋ ７１０５に準拠して、フィルムの光沢性について測定した。 <Gloss> The gloss of the film was measured according to JIS K 7105.
＜収縮率＞ ＪＩＳ Ｚ１７０９に準拠して、フィルムのＭＤ及びＴＤについて測定した。 <Shrinkage ratio> Based on JIS Z1709, it measured about MD and TD of the film.
＜ヒートシール強度＞ 二枚に重ねたフィルムを、温度８０℃、９０℃、１００℃にそれぞれ温調された上下２つの幅１０ｍｍの金属製ダイで、圧力１kgf/cm2、シール時間１．０秒でシールする。その後、フィルムを１５ｍｍ幅に切り出して、シール部を剥離するように引っ張り試験機つかみ器具に装着し、シール強度をＪＩＳ Ｚ １７０７に準拠して測定した。 <Heat seal strength> Two stacked 10 mm wide metal dies, each with a temperature of 80 ° C., 90 ° C., and 100 ° C., each having a pressure of 1 kgf / cm 2 and a sealing time of 1.0 second. Seal with. Thereafter, the film was cut into a width of 15 mm, and attached to a tensile tester gripping tool so as to peel off the seal portion, and the seal strength was measured in accordance with JIS Z 1707.
＜引張破断伸度＞ ＪＩＳ Ｚ １７０７に準拠して、フィルムのＭＤ及びＴＤについて測定した。 <Tensile rupture elongation> Based on JISZ1707, it measured about MD and TD of the film.
＜２％モジュラスの値＞ ＪＩＳ Ｋ ７１２７に準拠し、測定のつかみ間隔を１００ｍｍとして、フィルムのＭＤ及びＴＤについて測定し、伸度２％の時の値を算出した。 <Value of 2% Modulus> Based on JIS K 7127, the measurement grip interval was set to 100 mm, and the film was measured for MD and TD, and the value at an elongation of 2% was calculated.
＜スリーブ包装時のヒートシール性＞ シールの状態を目視で評価。更に１．５ｍの高さから包装体を落下させた後のシール部の状態を評価した。
○：全面的にシールされていて、シール部での破袋無し。
△：一部シールされていない箇所があるが、シール部での破袋無し。
×：シール部での破袋有り。
<Heat sealability during sleeve packaging> Visually evaluate the state of the seal. Furthermore, the state of the seal part after dropping the package from a height of 1.5 m was evaluated.
○: Sealed over the entire surface and no bag breakage at the seal part.
Δ: There is a part that is not sealed, but there is no bag breakage at the seal part.
X: There is a broken bag at the seal part.
＜スリーブ包装時の耐熱性＞ 加熱時にフィルムが溶融のため白化しているかどうかを目視で判断した。
○：白化無し。
△：全体的に白く曇ったように見える。
×：局部的に著しく白化が有り、フィルム強度が劣化若しくは穴が開いている。
<Heat resistance at the time of sleeve packaging> It was visually determined whether the film was whitened due to melting during heating.
○: No whitening.
Δ: It looks white and cloudy as a whole.
X: There is remarkable whitening locally, film strength is deteriorated or a hole is formed.
＜スリーブ包装時の仕上がり＞ 包装後のスリーブ面の仕上がり状態を目視で評価した。
○：良好
△：スリーブ面以外の箇所に細かなシワが見られる。
×：スリーブ面に皺やめくれが有る。
<Finish at the time of sleeve packaging> The finished state of the sleeve surface after packaging was visually evaluated.
◯: Good △: Fine wrinkles are seen in places other than the sleeve surface.
X: There are wrinkles and turns on the sleeve surface.
＜スリーブ包装時の結束力＞ 包装後の被包装物の結束状態で評価した。
○：良好。
△：ゆるみ小。
×：ゆるみ大。
<Bundling force at the time of sleeve packaging> It evaluated in the bundling state of the to-be packaged object after packaging.
○: Good.
Δ: Small looseness.
X: Large looseness.
また、実施例及び比較例に用いた原料種は、次の通りである。
ＬＬ１：メタロセン系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度は０．９１３g/cm3
ＬＬ２：チーグラー系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．９２０g/cm3
ＬＬ３：チーグラー系触媒で重合された、Ｃ８コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．９２０g/cm3
ＬＬ４：メタロセン系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．９０５g/cm3
ＬＬ５：メタロセン系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．８０５g/cm3
ＬＬ６：チーグラー系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．９２５g/cm3
ＬＬ７：チーグラー系触媒で重合された、Ｃ６コモノマーを有する直鎖状低密度ポリエチレンであり、密度０．９３０g/cm3
ＨＤ１：メタロセン系触媒で重合された高密度ポリエチレンであり、密度０．９４５g/cm3
ＨＤ２：チーグラー系触媒で重合された高密度ポリエチレンであり、密度０．９６５g/cm3
ＨＤ３：メタロセン系触媒で重合された高密度ポリエチレンであり、密度０．９３５g/cm3
Moreover, the raw material seed | species used for the Example and the comparative example is as follows.
LL1: a linear low-density polyethylene having a C6 comonomer polymerized with a metallocene catalyst and having a density of 0.913 g / cm 3
LL2: linear low density polyethylene with C6 comonomer polymerized with Ziegler catalyst, density 0.920 g / cm 3
LL3: linear low density polyethylene with C8 comonomer polymerized with Ziegler catalyst, density 0.920 g / cm 3
LL4: linear low-density polyethylene having a C6 comonomer polymerized with a metallocene catalyst and having a density of 0.905 g / cm 3
LL5: linear low density polyethylene having a C6 comonomer polymerized with a metallocene catalyst and having a density of 0.805 g / cm 3
LL6: linear low density polyethylene with C6 comonomer polymerized with Ziegler catalyst, density 0.925 g / cm 3
LL7: linear low density polyethylene with C6 comonomer polymerized with Ziegler catalyst, density 0.930 g / cm 3
HD1: high density polyethylene polymerized with a metallocene catalyst, density 0.945 g / cm 3
HD2: high density polyethylene polymerized with Ziegler catalyst, density 0.965 g / cm 3
HD3: high density polyethylene polymerized with metallocene catalyst, density 0.935 g / cm 3
＜参考例１＞
表１に示すように、密度０．８０５g/cm3の直鎖状低密度ポリエチレン樹脂を両表層とし、密度０．９２０g/cm3の直鎖状低密度ポリエチレン樹脂を芯層として３台の押出機（芯層用、最内層用、最外層用）でそれぞれ１７０℃〜２４０℃にて溶融混練し、全層の厚みに対する芯層の厚みの割合が８０％になるように各押出機の押出量を設定し、２４０℃に保った３層環状ダイスより下向きに共押出した。形成された３層構成チューブ状溶融樹脂を、内側は冷却水が循環している円筒状冷却マンドレルの外表面を摺動させながら、外側は水槽を通すことにより冷却して引き取り、未延伸フィルムを得た。最終的に得られるフィルムの厚みは２５μmになるように、押出機のスクリュー回転数及び引き取り速度を調整することにより行った。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを上下段１枚に切り開いて上限段の熱ロール装置に導き、１００℃加温ロールと３０℃の冷却ロールの２つのロール間で３．０倍に延伸を行った後、更に３０〜７０℃に適宜調整された熱ロールで数％程度の弛緩処理を施して、上下段それぞれで１本のロールに巻取った。延伸中の延伸バブルの安定性は良好で、延伸点の上下動や延伸チューブの揺動もなく、又、ネッキングなどの不均一延伸状態も観察されなかった。得られた延伸フィルムの特性は表１に示したように、優れた透明性と光沢性、低温収縮性を有し、特に７０℃でもヒートシール強度が1N/cm以上で、極めて低温シール性に優れるものであった。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、底シールが低温ででき、破袋やフィルムの白化もなく、収縮トンネル温度も比較的低温側で十分な収縮仕上り状態であった。収縮包装品を上から手で押さえて前後左右に揺らしても６本の缶に隙間ができることはなかった。
< Reference Example 1 >
As shown in Table 1, three extrusions using a linear low density polyethylene resin with a density of 0.805 g / cm 3 as both surface layers and a linear low density polyethylene resin with a density of 0.920 g / cm 3 as the core layer. Melting and kneading at 170 ° C. to 240 ° C. with a machine (for the core layer, for the innermost layer, for the outermost layer), respectively, the extrusion of each extruder so that the ratio of the thickness of the core layer to the thickness of all layers is 80%. The amount was set and co-extruded downward from a three-layer annular die maintained at 240 ° C. The formed three-layered tube-shaped molten resin is cooled by passing the outer surface of a cylindrical cooling mandrel in which cooling water circulates inside while passing through a water tank, and the unstretched film is taken out. Obtained. It was performed by adjusting the screw rotation speed and the take-up speed of the extruder so that the final film thickness was 25 μm. This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film is cut into one upper and lower stage and led to a hot roll apparatus at the upper limit stage, and after stretching 3.0 times between two rolls of a 100 ° C. heating roll and a 30 ° C. cooling roll, A relaxation treatment of about several percent was performed with a hot roll appropriately adjusted to 30 to 70 ° C., and each roll was wound on one roll. The stability of the stretched bubble during stretching was good, there was no vertical movement of the stretching point, rocking of the stretching tube, and no nonuniform stretching state such as necking was observed. As shown in Table 1, the properties of the obtained stretched film are excellent in transparency, gloss, and low temperature shrinkage. Especially at 70 ° C, the heat seal strength is 1 N / cm or more, and extremely low temperature sealability is achieved. It was excellent. As a result of stacking and wrapping six 500ml beverage cans in the packaging form shown in FIG. 1 using this film with a stacking sleeve packaging machine, the bottom seal can be made at low temperature, there is no bag breaking or whitening of the film, and the shrink tunnel temperature is also high. The shrinkage finish was sufficient on the relatively low temperature side. There were no gaps in the six cans even when the shrink-wrapped product was pressed from above and shaken back and forth and left and right.
＜実施例２＞
表１に示すように、密度０．９２５g/cm3の直鎖状低密度ポリエチレン樹脂を両表層とし、密度０．９２０g/cm3の直鎖状低密度ポリエチレン樹脂を芯層として３台の押出機（芯層用、最内層用、最外層用）でそれぞれ１７０℃〜２４０℃にて溶融混練し、全層の厚みに対する芯層の厚みの割合が８０％になるように各押出機の押出量を設定し、２４０℃に保った３層環状ダイスより下向きに共押出した。形成された３層構成チューブ状溶融樹脂を、内側は冷却水が循環している円筒状冷却マンドレルの外表面を摺動させながら、外側は水槽を通すことにより冷却して引き取り、未延伸フィルムを得た。最終的に得られるフィルムの厚みは２５μmになるように、押出機のスクリュー回転数及び引き取り速度を調整することにより行った。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを熱ロール装置に導き、７５℃加温ロールと３０℃の冷却ロールの２つのロール間で１．２倍に延伸を行った後、更に３０〜７０℃に適宜調整された熱ロールで数％程度の弛緩処理を施して、上下段１枚に切り開いてそれぞれ１本のロールに巻取った。延伸中の延伸バブルの安定性は良好で、延伸点の上下動や延伸チューブの揺動もなく、又、ネッキングなどの不均一延伸状態も観察されなかった。得られた延伸フィルムの特性は表１に示したように、優れた透明性と光沢性を有するものであった。このフィルムで、集積用スリーブ包装機にて３５０ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、収縮トンネル内の底シールと収縮状態を観察すると、収縮しながら底シールされる状況であったが、破袋や白化などなく、十分に仕上がった。
<Example 2>
As shown in Table 1, three extrusions using a linear low-density polyethylene resin with a density of 0.925 g / cm 3 as both surface layers and a linear low-density polyethylene resin with a density of 0.920 g / cm 3 as the core layer. Melting and kneading at 170 ° C. to 240 ° C. with a machine (for the core layer, for the innermost layer, for the outermost layer), respectively, the extrusion of each extruder so that the ratio of the thickness of the core layer to the thickness of all layers is 80%. The amount was set and co-extruded downward from a three-layer annular die maintained at 240 ° C. The formed three-layered tube-shaped molten resin is cooled by passing the outer surface of a cylindrical cooling mandrel in which cooling water circulates inside while passing through a water tank, and the unstretched film is taken out. Obtained. It was performed by adjusting the screw rotation speed and the take-up speed of the extruder so that the final film thickness was 25 μm. This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film was led to a hot roll device, and after being stretched 1.2 times between two rolls of a 75 ° C. heating roll and a 30 ° C. cooling roll, the heat adjusted to 30 to 70 ° C. as appropriate. The rolls were subjected to a relaxation treatment of about several percent, cut into one upper and lower stage, and wound on one roll. The stability of the stretched bubble during stretching was good, there was no vertical movement of the stretching point, rocking of the stretching tube, and no nonuniform stretching state such as necking was observed. As shown in Table 1, the properties of the obtained stretched film were excellent in transparency and gloss. With this film, as a result of stacking and packaging six 350 ml beverage cans in the packaging form shown in FIG. 1 using a stacking sleeve packaging machine, when the bottom seal and the contracted state in the contracting tunnel are observed, the bottom seal is contracted while contracting. It was the situation, but it was finished without bag breakage or whitening.
＜実施例３＞
表１に示す樹脂構成にて実施例２と同様の方法で熱収縮性フィルムを作製した。優れた透明性と光沢性を有したものであった。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、底シールが低温ででき、破袋やフィルムの白化もなく、収縮トンネル温度はやや高温側であったがフィルムの白化等なく、十分な仕上り状態であった。収縮包装品を上から手で押さえて前後左右に揺らしても６本の缶に隙間ができることはなかった。
<Example 3>
A heat-shrinkable film having the resin structure shown in Table 1 was produced in the same manner as in Example 2. It had excellent transparency and gloss. As a result of stacking and packaging six 500 ml beverage cans in the packaging form shown in FIG. 1 with this film packaging sleeve packaging machine, the bottom seal can be made at a low temperature, the bag is not broken and the film is not whitened. Although it was slightly on the high temperature side, it was in a sufficiently finished state without whitening of the film. There were no gaps in the six cans even when the shrink-wrapped product was pressed from above and shaken back and forth and left and right.
＜実施例４＞
表１に示す樹脂構成にて実施例２と同様の方法で熱収縮性フィルムを作製した。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、低温シール性であり、特に低温収縮性に優れているため収縮トンネルの低温域で良好な仕上がり状態が得られた。
<Example 4>
A heat-shrinkable film having the resin structure shown in Table 1 was produced in the same manner as in Example 2. With this film, as a result of stacking and packaging six 500 ml beverage cans in the packaging form shown in FIG. 1 using a stacking sleeve packaging machine, it has a low-temperature sealing property and is particularly excellent in low-temperature shrinkage. A good finished state was obtained.
＜参考例２＞
表１に示す樹脂構成にて実施例２と同様の方法で熱収縮性フィルムを作製した。このフィルムで、集積用スリーブ包装機にてティッシュケース５箱を積み重ねた状態で集積包装した結果、底シールが低温ででき、破袋やフィルムの白化もなく、収縮トンネル温度はやや高温側であったがフィルムの白化等なく、十分な仕上り状態であった。
< Reference Example 2 >
A heat-shrinkable film having the resin structure shown in Table 1 was produced in the same manner as in Example 2. With this film, as a result of stacking and packaging with 5 tissue cases stacked in a stacking sleeve packaging machine, the bottom seal can be made at a low temperature, the bag is not broken and the film is not whitened, and the shrink tunnel temperature is slightly higher. However, there was no whitening of the film and the finish was satisfactory.
＜実施例６＞
表１に示す樹脂構成にて実施例２と同様の方法で熱収縮性フィルムを作製した。得られた延伸フィルムは透明性、低温シール性、低温収縮性、耐熱性に優れたものであった。このフィルムで、集積用スリーブ包装機にて２０００ｍｌ飲料ペットボトル６本を図１に示した包装形態で集積包装する際に収縮トンネル内を観察すると、底面がシールされた後に収縮が開始する状態であった。シール部の破袋やフィルムの白化もなく、スリーブ面の仕上がりが綺麗になる十分な収縮トンネル温度範囲を有していて、収縮包装品を上から手で押さえて前後左右に揺らしても６本のペットボトルに隙間ができることがなく、スリーブ面上部のフィルムに指をかけて持ち上げてもフィルムが伸びるようなことがなかった。また、集積包装品を４個ずつパレットに段積みして輸送後、フィルムにスリキズが入った状態で、再度持ち上げてもキズからフィルムが破れるようなことはなかった。
<Example 6>
A heat-shrinkable film having the resin structure shown in Table 1 was produced in the same manner as in Example 2. The obtained stretched film was excellent in transparency, low temperature sealability, low temperature shrinkage, and heat resistance. With this film, when the inside of the shrink tunnel is observed when six 2000ml beverage PET bottles are piled and packaged in the packaging form shown in FIG. 1 using the sleeve packaging machine for accumulation, the shrinkage starts after the bottom surface is sealed. there were. It has a sufficient shrink tunnel temperature range where the sleeve part is not broken and the film is not whitened, and the finish of the sleeve surface is beautiful. There was no gap in the PET bottle, and the film did not stretch even when lifted with a finger on the film on the upper surface of the sleeve. In addition, after the stacked packages were stacked on a pallet by four pieces and transported, the film was not torn from the scratches even if it was lifted again with the scratches on the film.
＜実施例７＞
実施例２と同様の方法で、表１に示す樹脂構成、厚み、延伸倍率にて熱収縮性フィルムを作製した。得られた延伸フィルムは透明性、低温シール性、低温収縮性、耐熱性に優れたものであった。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、シール部の破袋やフィルムの白化もなく、スリーブ面の仕上がりが綺麗になる十分な収縮トンネル温度範囲を有していた。収縮包装品のスリーブ面上部のフィルムに指をかけて持ち上げてもフィルムが伸びるようなことがなく、更に１．５ｍの高さから数回落下させてもフィルムが破れることなく、６本の缶に隙間もできなかった。また、集積包装品を４個ダンボール入れて輸送後、フィルムにスリキズが入った状態で、再度持ち上げてもキズからフィルムが破れるようなことはなかった。
<Example 7>
A heat-shrinkable film was prepared in the same manner as in Example 2 with the resin configuration, thickness, and stretch ratio shown in Table 1. The obtained stretched film was excellent in transparency, low temperature sealability, low temperature shrinkage, and heat resistance. As a result of collecting and packaging six 500 ml beverage cans in the packaging form shown in FIG. 1 using this film packaging machine, there is no breakage of the seal portion or whitening of the film, and the finish of the sleeve surface is beautiful. It had a sufficient shrink tunnel temperature range. 6 cans without tearing the film even if it is dropped several times from a height of 1.5m, even if it is lifted by placing a finger on the film on the sleeve surface of the shrink-wrapped product and lifting it There was no gap. In addition, after the package of four integrated packages was put in a cardboard box and transported, the film was not torn from the scratch even if it was lifted again in a state where the film had scratches.
＜実施例８＞
参考例１と同様の方法で、表１に示す樹脂構成、厚み、延伸倍率にて熱収縮性フィルムを作製した。得られた延伸フィルムの特性は表１に示したように、優れた透明性と光沢性、低温収縮性を有し、特に８０℃でもヒートシール強度が1N/cm以上で、極めて低温シール性に優れるものであった。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料６本を図１に示した包装形態で集積包装する際に収縮トンネル内を観察すると、底面がシールされた後に収縮が開始する状態であった。シール部の破袋やフィルムの白化もなく、スリーブ面の仕上がりが綺麗になる十分な収縮トンネル温度範囲を有していて、収縮包装品を上から手で押さえて前後左右に揺らしても６本の缶に隙間ができることがなく、スリーブ面上部のフィルムに指をかけて持ち上げてもフィルムが伸びるようなことがなかった。また、集積包装品を４個ダンボール入れて輸送後、フィルムにスリキズが入った状態で、再度持ち上げてもキズからフィルムが破れるようなことはなかった。
<Example 8>
A heat-shrinkable film was produced in the same manner as in Reference Example 1 with the resin configuration, thickness, and stretch ratio shown in Table 1. As shown in Table 1, the properties of the obtained stretched film are excellent in transparency, gloss, and low temperature shrinkage. Especially at 80 ° C, the heat seal strength is 1 N / cm or more, and it is extremely low temperature sealable. It was excellent. With this film, when the inside of the shrinking tunnel was observed when six 500 ml beverages were piled and packed in the packaging form shown in FIG. 1 using a sleeve packaging machine for accumulation, the shrinkage started after the bottom surface was sealed. . It has a sufficient shrink tunnel temperature range where the sleeve part is not broken and the film is not whitened, and the finish of the sleeve surface is beautiful. There was no gap in the can, and the film did not stretch even when lifted with a finger on the film on the upper surface of the sleeve. In addition, after the package of four integrated packages was put in a cardboard box and transported, the film was not torn from the scratch even if it was lifted again in a state where the film had scratches.
＜実施例９＞
表１に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。この未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ３．３倍にＴＤ３．０倍に延伸した後、実施例２と同様に再延伸等を行って、延伸フィルムを得た。得られた延伸フィルムの特性は表１に示したように、優れた透明性と光沢性、低温収縮性を有したものであった。このフィルムで、集積用スリーブ包装機にて５００ｍｌ飲料缶６本を図１に示した包装形態で集積包装する際に収縮トンネル内を観察すると、底面がシールされた後に収縮が開始する状態であった。シール部の破袋がなく、スリーブ面の仕上がりが綺麗になる十分な収縮トンネル温度範囲を有していて、特に収縮トンネルを高温にしてもフィルムが白化するようなことはなかった。収縮包装品を上から手で押さえて前後左右に揺らしても６本の缶に隙間ができることがなく、スリーブ面上部のフィルムに指をかけて持ち上げてもフィルムが伸びるようなことがなかった。
<Example 9>
An unstretched film having a resin structure as shown in Table 1 was obtained in the same manner as in Reference Example 1 . This unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched at 95 to 105 ° C. by MD 3.3 times to TD 3.0 times, and then re-stretched in the same manner as in Example 2. A stretched film was obtained. As shown in Table 1, the properties of the obtained stretched film were excellent in transparency, gloss, and low-temperature shrinkage. With this film, the inside of the shrink tunnel was observed when six 500 ml beverage cans were piled and packed in the packaging form shown in FIG. 1 using a sleeve wrapping machine, and the shrinkage started after the bottom surface was sealed. It was. There was no bag breakage at the seal part, and there was a sufficient shrink tunnel temperature range in which the finish of the sleeve surface was beautiful, and even when the shrink tunnel was at a high temperature, the film did not whiten. Even if the shrink-wrapped product was pressed from above and shaken back and forth, left and right, there were no gaps in the six cans, and the film did not stretch even when lifted by placing a finger on the film on the upper surface of the sleeve.
＜実施例１０＞
実施例２と同様の方法で、表１に示す樹脂構成、厚み、延伸倍率にて熱収縮性フィルムを作製した。得られた延伸フィルムの特性は表１に示したように、優れた透明性と光沢性、低温収縮性を有したものであった。このフィルムで、集積用スリーブ包装機にてティッシュケース５箱を図１に示した包装形態で集積包装する際に収縮トンネル内を観察すると、底面がシールされた後に収縮が開始する状態であった。シール部の破袋がなく、スリーブ面の仕上がりが綺麗になる十分な収縮トンネル温度範囲を有していて、特に収縮トンネルを高温にしてもフィルムが白化するようなことはなかった。収縮包装品を上から手で押さえて前後左右に揺らしても5箱の重ねた面が大きくずれることがなかった。また、集積包装品を８個ずつダンボール詰めして輸送後、フィルムにスリキズが入った状態で、再度持ち上げてもキズからフィルムが破れるようなことはなかった。
<Example 10>
A heat-shrinkable film was prepared in the same manner as in Example 2 with the resin configuration, thickness, and stretch ratio shown in Table 1. As shown in Table 1, the properties of the obtained stretched film were excellent in transparency, gloss, and low-temperature shrinkage. With this film, when collecting and
＜比較例１＞
表２に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。この未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ２．７倍にＴＤ２．５倍に延伸した後、実施例２と同様に再延伸等を行って、延伸フィルムを得た。延伸中の延伸バブルの安定性は良好で、延伸点の上下動や延伸チューブの揺動もなく、又、ネッキングなどの不均一延伸状態も観察されなかった。得られた延伸フィルムの特性は表２に示したように、優れた透明性と光沢性を有するものであったが、ＴＤの１２０℃の収縮率が小さいものであった。このフィルムで、集積用スリーブ包装機にて３５０ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、シールは十分にできていたが、収縮が不十分で全体にシワが多く、特にスリーブ箇所にフィルムが収縮せずに余った状態になった。収縮包装品を上から手で押さえて前後左右に揺らすと、徐々に６本の缶に隙間ができ、タイト感がなくなってしまった。
<Comparative Example 1>
An unstretched film having a resin structure as shown in Table 2 was obtained in the same manner as in Reference Example 1 . This unstretched film was guided to the tubular biaxial stretching apparatus shown in FIG. 2, and stretched at TD 2.5 times to MD 2.7 times at 95 to 105 ° C., and then re-stretched in the same manner as in Example 2. A stretched film was obtained. The stability of the stretched bubble during stretching was good, there was no vertical movement of the stretching point, rocking of the stretching tube, and no nonuniform stretching state such as necking was observed. As shown in Table 2, the properties of the obtained stretched film were excellent in transparency and gloss, but had a small TD 120 ° C. shrinkage. With this film, as a result of collecting and packaging six 350 ml beverage cans in the packaging form shown in FIG. 1 with a sleeve packaging machine for accumulation, the seal was sufficient, but the shrinkage was insufficient and the whole was wrinkled, In particular, the film remained in the sleeve portion without shrinking. When holding the shrink-wrapped product from above and shaking it back and forth and left and right, gaps were gradually formed in the six cans and the tight feeling disappeared.
＜比較例２＞
表２に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを上下段１枚に切り開いて上限段の熱ロール装置に導き、芯層の樹脂の融点より５℃低い１１５℃の加温ロールと３０℃の冷却ロールの２つのロール間で１．２倍に延伸を行った後、更に３０〜７０℃に適宜調整された熱ロールで数％程度の弛緩処理を施して、上下段それぞれで１本のロールに巻取った。延伸中の延伸バブルの安定性は良好であったが、熱処理ロールでフィルム両端部の収縮が著しく、最終製品の取り幅が狭くなった。得られた延伸フィルムの特性は表２に示したように、透明性と光沢性に欠け、１２０℃の収縮率が小さいものであった。このフィルムで、集積用スリーブ包装機にて３５０ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、シールは十分にできていたが、収縮が不十分で全体にシワが多く、タイト感がない仕上がり状態になってしまった。スリーブ面上部のフィルムに指をかけて持ち上げると、フィルムが伸びて、その間から飲料缶が抜け落ちてしまった。
<Comparative example 2>
An unstretched film having a resin structure as shown in Table 2 was obtained in the same manner as in Reference Example 1 . This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film is cut into one upper and lower stage and led to a hot roll apparatus at the upper limit stage. Between the two rolls, a 115 ° C. heating roll and a 30 ° C. cooling roll, 5 ° C. lower than the melting point of the core layer resin. The film was stretched by a factor of 2 and then subjected to a relaxation treatment of about several percent with a hot roll appropriately adjusted to 30 to 70 ° C., and wound on one roll at each of the upper and lower stages. Although the stability of the stretched bubble during stretching was good, the shrinkage at both ends of the film was remarkable with the heat treatment roll, and the width of the final product was narrowed. As shown in Table 2, the properties of the obtained stretched film were lacking in transparency and gloss, and the shrinkage rate at 120 ° C. was small. With this film, as a result of collecting and packaging six 350 ml beverage cans in the packaging form shown in FIG. 1 with a sleeve packaging machine for accumulation, the seal was sufficient, but the shrinkage was insufficient and the whole was wrinkled, The finish has no tightness. When I put my finger on the film on the upper surface of the sleeve and lifted it, the film stretched and the beverage can dropped out from there.
＜比較例３＞
表２に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを上下段１枚に切り開いて上限段の熱ロール装置に導き、芯層の樹脂の融点より５℃低い１１５℃の加温ロールと３０℃の冷却ロールの２つのロール間で緊張熱処理を行い、次いで７５℃加温ロールと３０℃の冷却ロールの２つのロール間で１．２倍に延伸を行った後、更に３０〜７０℃に適宜調整された熱ロールで数％程度の弛緩処理を施して、上下段それぞれで１本のロールに巻取った。得られた延伸フィルムの特性は表２に示したように、透明性と光沢性に欠け、１２０℃の収縮率が小さいものであった。このフィルムで、集積用スリーブ包装機にて３５０ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、シールは十分にできていたが、収縮が不十分で全体にシワが多く、タイト感がない仕上がり状態になってしまった。スリーブ面上部のフィルムに指をかけて持ち上げると、フィルムがＭＤに裂けてしまい、飲料缶が抜け落ちてしまった。
<Comparative Example 3>
An unstretched film having a resin structure as shown in Table 2 was obtained in the same manner as in Reference Example 1 . This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film is cut into one upper and lower stage, led to a hot roll apparatus at the upper limit stage, and tensioned between two rolls of a 115 ° C. heating roll and a 30 °
＜比較例４＞
表２に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを上下段１枚に切り開いて上限段の熱ロール装置に導き、再延伸を行わずに３０〜８５℃に適宜調整された熱ロールで数％程度の弛緩処理を施して、上下段それぞれで１本のロールに巻取った。得られた延伸フィルムの特性は表２に示したように、透明性と光沢性は良好であったが、８０℃の収縮率がＭＤとＴＤ共に大きいものであった。このフィルムで、集積用スリーブ包装機にて３５０ｍｌ飲料缶６本を図１に示した包装形態で集積包装した結果、シールは十分にできていたが、幅方向の収縮が大きくなりすぎて飲料缶６本を全て覆うことができなかった。このフィルムに印刷を施し、フィルム幅を大きくして同様のスリーブ包装を行うと、飲料缶６本を全て覆うことはできるようになったが、印刷した図柄が大きく歪んでしまった。
<Comparative example 4>
An unstretched film having a resin structure as shown in Table 2 was obtained in the same manner as in Reference Example 1 . This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film is cut into one upper and lower stage and led to a hot roll apparatus at the upper limit stage, and subjected to a relaxation treatment of about several percent with a hot roll appropriately adjusted to 30 to 85 ° C. without redrawing. Each lower stage was wound on one roll. As shown in Table 2, the properties of the obtained stretched film were good in transparency and gloss, but the shrinkage at 80 ° C. was large for both MD and TD. With this film, as a result of stacking and packaging six 350 ml beverage cans in the packaging form shown in FIG. 1 using a stacking sleeve packaging machine, the seal was sufficient, but the shrinkage in the width direction became too large and the beverage can I couldn't cover all six. When this film was printed and the same width of the sleeve packaging was performed by increasing the film width, it was possible to cover all six beverage cans, but the printed pattern was greatly distorted.
＜比較例５＞
表２に示すような樹脂構成の未延伸フィルムを参考例１と同様にして得た。このチューブ状未延伸フィルムを図２に示したチューブラー二軸延伸装置に導き、９５〜１０５℃でＭＤ４．５倍にＴＤ４．０倍に延伸した後、４０℃以下まで冷却し、２つに折りたたんだ。次いでこの延伸フィルムを熱ロール装置に導き、１００℃の加温ロールと３０℃の冷却ロールの２つのロール間で３．５倍に延伸を行うべく徐々に倍率を上げると、加温ロール及び冷却ロールの駆動モーターの負荷電流が徐々に上昇し、３．５倍まで延伸することができなかった。
<Comparative Example 5>
An unstretched film having a resin structure as shown in Table 2 was obtained in the same manner as in Reference Example 1 . This tubular unstretched film is guided to the tubular biaxial stretching apparatus shown in FIG. 2 and stretched to TD 4.0 times to MD 4.5 times at 95 to 105 ° C., and then cooled to 40 ° C. or lower to be divided into two. I collapsed. Next, this stretched film is guided to a hot roll device, and when the magnification is gradually increased to stretch 3.5 times between two rolls of a 100 ° C. heating roll and a 30 ° C. cooling roll, the heating roll and cooling roll The load current of the roll drive motor gradually increased and could not be stretched up to 3.5 times.
本発明の集積包装用ポリエチレン系熱収縮性多層フィルムは、スリーブ収縮包装、オーバーラップ収縮包装といった集積包装に用いることができる。特に缶ビール、缶ジュース、瓶詰め、清涼飲料水などの重量物のスリーブ包装にも好適に用いうるものである。 The polyethylene heat-shrinkable multilayer film for integrated packaging of the present invention can be used for integrated packaging such as sleeve shrink packaging and overlap shrink packaging. In particular, it can be suitably used for sleeve packaging of heavy goods such as canned beer, canned juice, bottling, and soft drinks.
１ スリーブ形態包装時のフィルム
２ スリーブ形態包装時の被包装物(飲料缶等)
３ スリーブ形態包装時のフィルム幅
４ チューブラー延伸装置のニップロール
５ チューブラー延伸装置の予熱ヒーター
６ チューブラー延伸装置の主熱ヒーター
７ チューブラー延伸装置の冷却エアーリング
８ チューブラー延伸時のフィルム
1 Film in sleeve form packaging 2 Packaged items in sleeve form packaging (drink cans, etc.)
3 Film width at the time of
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| JP5896714B2 (en) * | 2011-12-13 | 2016-03-30 | 興人フィルム＆ケミカルズ株式会社 | Polyethylene heat-shrinkable multilayer film for pack-in-box packaging, pack-in-box package and packaging method thereof. |
| JP6496981B2 (en) * | 2014-03-28 | 2019-04-10 | 凸版印刷株式会社 | Sealant film, and film laminate and standing pouch using the same |
| US20170297312A1 (en) * | 2014-10-02 | 2017-10-19 | Kohjin Film & Chemicals Co., Ltd. | Polyethylene-based thermally-shrinkable multilayer film for packaging, and package and packaging method therefor |
| JP2017137110A (en) * | 2016-02-05 | 2017-08-10 | 積水フィルム株式会社 | Shrink packaging method, heat-shrinkable film, and package |
| JP7108266B2 (en) * | 2018-11-07 | 2022-07-28 | 興人フィルム＆ケミカルズ株式会社 | Polyethylene multilayer film for overwrap heat-shrinkable packaging |
| JP2020093794A (en) * | 2018-12-10 | 2020-06-18 | 日本製紙クレシア株式会社 | Shrink film package |
| CN111231470A (en) * | 2020-04-03 | 2020-06-05 | 汕头市明佳热收缩膜有限公司 | Multilayer co-extruded polyethylene heat shrinkable film and preparation method thereof |
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| JPH0815777B2 (en) * | 1987-08-27 | 1996-02-21 | 大倉工業株式会社 | Laminated heat shrinkable film |
| JP2916853B2 (en) * | 1993-05-31 | 1999-07-05 | 大倉工業株式会社 | Polyolefin-based heat-shrinkable laminated film |
| JP2001179905A (en) * | 1999-12-22 | 2001-07-03 | Okura Ind Co Ltd | Polyethylenic multilayered stretched film |
| JP4841368B2 (en) * | 2005-09-28 | 2011-12-21 | 株式会社興人 | Polyethylene-based crosslinked shrink film |
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