JP4430528B2 - Heat shrinkable biodegradable film - Google Patents
Heat shrinkable biodegradable film Download PDFInfo
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- JP4430528B2 JP4430528B2 JP2004375409A JP2004375409A JP4430528B2 JP 4430528 B2 JP4430528 B2 JP 4430528B2 JP 2004375409 A JP2004375409 A JP 2004375409A JP 2004375409 A JP2004375409 A JP 2004375409A JP 4430528 B2 JP4430528 B2 JP 4430528B2
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- 229920000747 poly(lactic acid) Polymers 0.000 claims description 44
- 239000004626 polylactic acid Substances 0.000 claims description 44
- 125000001931 aliphatic group Chemical group 0.000 claims description 40
- 229920001577 copolymer Polymers 0.000 claims description 38
- 229920000728 polyester Polymers 0.000 claims description 35
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 claims description 22
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims description 18
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 17
- 238000006068 polycondensation reaction Methods 0.000 claims description 17
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 claims description 16
- 229920001634 Copolyester Polymers 0.000 claims description 14
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 14
- PUPZLCDOIYMWBV-UHFFFAOYSA-N (+/-)-1,3-Butanediol Chemical compound CC(O)CCO PUPZLCDOIYMWBV-UHFFFAOYSA-N 0.000 claims description 13
- 229920006257 Heat-shrinkable film Polymers 0.000 claims description 13
- KDYFGRWQOYBRFD-UHFFFAOYSA-N succinic acid Chemical compound OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 claims description 13
- 229920005989 resin Polymers 0.000 claims description 12
- 239000011347 resin Substances 0.000 claims description 12
- 239000004310 lactic acid Substances 0.000 claims description 11
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 10
- 235000014655 lactic acid Nutrition 0.000 claims description 9
- 239000001361 adipic acid Substances 0.000 claims description 8
- 235000011037 adipic acid Nutrition 0.000 claims description 8
- -1 aromatic dicarboxylic acids Chemical class 0.000 claims description 7
- 235000011187 glycerol Nutrition 0.000 claims description 7
- 239000001384 succinic acid Substances 0.000 claims description 6
- 125000003118 aryl group Chemical group 0.000 claims description 4
- 238000010030 laminating Methods 0.000 claims description 3
- 239000010410 layer Substances 0.000 description 85
- 238000004806 packaging method and process Methods 0.000 description 17
- JVTAAEKCZFNVCJ-REOHCLBHSA-N L-lactic acid Chemical compound C[C@H](O)C(O)=O JVTAAEKCZFNVCJ-REOHCLBHSA-N 0.000 description 16
- JVTAAEKCZFNVCJ-UWTATZPHSA-N D-lactic acid Chemical compound C[C@@H](O)C(O)=O JVTAAEKCZFNVCJ-UWTATZPHSA-N 0.000 description 9
- 229940022769 d- lactic acid Drugs 0.000 description 9
- 229930182843 D-Lactic acid Natural products 0.000 description 8
- 229920001896 polybutyrate Polymers 0.000 description 8
- 239000000203 mixture Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000001771 impaired effect Effects 0.000 description 4
- 239000000314 lubricant Substances 0.000 description 4
- 238000002844 melting Methods 0.000 description 4
- 230000008018 melting Effects 0.000 description 4
- 239000004014 plasticizer Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 239000000539 dimer Substances 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000007151 ring opening polymerisation reaction Methods 0.000 description 3
- 229920003002 synthetic resin Polymers 0.000 description 3
- 239000000057 synthetic resin Substances 0.000 description 3
- 208000034530 PLAA-associated neurodevelopmental disease Diseases 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 230000003796 beauty Effects 0.000 description 2
- 230000006399 behavior Effects 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 238000009264 composting Methods 0.000 description 2
- 229920005839 ecoflex® Polymers 0.000 description 2
- UAUDZVJPLUQNMU-KTKRTIGZSA-N erucamide Chemical compound CCCCCCCC\C=C/CCCCCCCCCCCC(N)=O UAUDZVJPLUQNMU-KTKRTIGZSA-N 0.000 description 2
- 229920001519 homopolymer Polymers 0.000 description 2
- JJTUDXZGHPGLLC-UHFFFAOYSA-N lactide Chemical compound CC1OC(=O)C(C)OC1=O JJTUDXZGHPGLLC-UHFFFAOYSA-N 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- JJTUDXZGHPGLLC-IMJSIDKUSA-N 4511-42-6 Chemical compound C[C@@H]1OC(=O)[C@H](C)OC1=O JJTUDXZGHPGLLC-IMJSIDKUSA-N 0.000 description 1
- 229920002472 Starch Polymers 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002981 blocking agent Substances 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000004611 light stabiliser Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 235000021485 packed food Nutrition 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004629 polybutylene adipate terephthalate Substances 0.000 description 1
- 229920013716 polyethylene resin Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920005990 polystyrene resin Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 229920006300 shrink film Polymers 0.000 description 1
- 239000008107 starch Substances 0.000 description 1
- 235000019698 starch Nutrition 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 230000037303 wrinkles Effects 0.000 description 1
Landscapes
- Laminated Bodies (AREA)
- Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
Description
本発明は、生分解性を有する熱収縮性フィルムに関する。 The present invention relates to a heat-shrinkable film having biodegradability.
従来から包装分野において多量の熱収縮性フィルムが、熱収縮包装の用途に使用されている。熱収縮性フィルムに用いられる合成樹脂としては、ポリプロピレン系樹脂やポリエチレン系樹脂、塩化ビニル系樹脂、ポリスチレン系樹脂などが挙げられる。しかしながら、これらの合成樹脂からなる熱収縮性フィルムは、包装材としての用を終えた後に自然環境中に投棄されると、その化学的安定性のため分解されることなく、自然環境に長期にわたって残留し環境汚染の一因になっている。また、熱収縮性フィルムによる収縮包装は食品容器の包装にも頻繁に利用されているが、最近ではゴミ減量化の観点から生ゴミのコンポスト化が推進されており、包装された食品容器を取り出すために破り取ったフィルムが生ゴミに混入した場合、分別は困難であり、生ゴミのコンポスト化の妨げの一因になっている。 Conventionally, a large amount of heat-shrinkable film has been used for heat-shrink packaging in the packaging field. Examples of the synthetic resin used for the heat-shrinkable film include polypropylene resins, polyethylene resins, vinyl chloride resins, and polystyrene resins. However, when heat-shrinkable films made of these synthetic resins are disposed in the natural environment after being used as a packaging material, they are not decomposed due to their chemical stability, and do not decompose in the natural environment for a long time. It remains and contributes to environmental pollution. Shrink packaging using heat-shrinkable film is also frequently used for packaging food containers, but recently, composting of garbage has been promoted from the viewpoint of reducing garbage, and the packaged food containers are taken out. For this reason, when the film that has been torn off is mixed into the garbage, it is difficult to separate the film, which is one of the factors that hinder the composting of the garbage.
微生物の働きによって、生分解性を有する樹脂組成物からなる各種の熱収縮性フィルムが提案されている。例えば、９０℃の油浴中に１分間浸漬した後の少なくとも一方向の収縮率が２０％以上であることを特徴とするポリ乳酸を主成分とする熱収縮性フィルムが提案されている（特許文献１）。ポリ乳酸を主成分とすることで、透明性に優れた熱収縮性フィルムを得ることが可能であるが、得られた熱収縮性フィルムは柔軟性が乏しく、脆く裂けやすい等の問題があった。また、ポリ乳酸の脆く裂けやすいという問題を改善することを目的に、ポリ乳酸、可塑剤および必要に応じて滑剤、熱安定剤を含む組成物を主成分とした熱可塑性ポリマー組成物を用いた熱収縮性生分解フィルムが提案されている（特許文献２）。ポリ乳酸に可塑剤を配合することで、柔軟性を付与することは可能であるが、可塑剤がブリードアウトして時間の経過と共にフィルムの物性が変化したり、ブリードアウトした可塑剤によって被包装物が汚染されるという問題があった。
そこで、本願発明者らは透明性に優れたポリ乳酸を両外層に、柔軟性に優れた脂肪族−芳香族共重合ポリエステルを中間層に配し、ポリ乳酸の特長である透明性と延伸性および収縮性は維持したまま、柔軟性を付与した生分解性二軸延伸フィルムを提案している（特許文献３）。しかしながら、こうして得られたフィルムで熱収縮包装を行うと、フィルムの一部が白濁し、美麗な包装袋が得られない場合があるという問題点があった。
Therefore, the present inventors arranged polylactic acid excellent in transparency in both outer layers and an aliphatic-aromatic copolymer polyester excellent in flexibility in the intermediate layer, and transparency and stretchability that are the characteristics of polylactic acid. And the biodegradable biaxially stretched film which provided the softness | flexibility is proposed, maintaining a contractibility (patent document 3). However, when heat shrink wrapping is performed with the film thus obtained, there is a problem that a part of the film becomes cloudy and a beautiful packaging bag may not be obtained.
本発明はこのような状況に鑑みなされたもので、ポリ乳酸からなる層と脂肪族−芳香族共重合ポリエステルからなる層を積層し、柔軟性、透明性および低温収縮性に優れた熱収縮性生分解フィルムであり、さらに、商品を熱収縮包装した際にもフィルムが白濁せず、美麗な収縮包装体を得ることが可能な熱収縮性生分解フィルムを提供することを課題とする。 The present invention has been made in view of such a situation, and a layer made of polylactic acid and a layer made of an aliphatic-aromatic copolymer polyester are laminated, and heat shrinkability excellent in flexibility, transparency and low temperature shrinkability. It is another object of the present invention to provide a heat-shrinkable biodegradable film that is a biodegradable film, and that does not become cloudy when a product is heat-shrink-wrapped, and that can provide a beautiful shrink-wrapped body.
本願発明者らは鋭意検討を行った結果、主としてポリ乳酸（Ａ）からなるＡ層と、主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層を、主として脂肪族共重合ポリエステル（Ｃ）からなるＣ層を介して、Ａ層とＢ層が隣接しないように積層し、二軸延伸することによって、上記課題が解決された熱収縮性生分解フィルムが得られることを見出し本発明に至った。
即ち本発明は、
（１）主としてポリ乳酸（Ａ）からなるＡ層と、主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層、主として脂肪族共重合ポリエステル（Ｃ）からなるＣ層が、Ａ層／Ｃ層／Ｂ層／Ｃ層／Ａ層の順で積層され、複数の押出機から各々の樹脂を押し出して得られた未延伸フィルムを二軸延伸されてなる熱収縮性フィルムであって、
脂肪族−芳香族共重合ポリエステル（Ｂ）が、脂肪族および芳香族ジカルボン酸と脂肪族ジオールを重縮合して得られるものであり、脂肪族共重合ポリエステル（Ｃ）が、脂肪族オキシカルボン酸と脂肪族ジカルボン酸ならびに脂肪族ジオールを重縮合して得られるものであることを特徴とする熱収縮性生分解フィルムが提供され、
（２）脂肪族共重合ポリエステル（Ｃ）が、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてコハク酸、脂肪族オキシカルボン酸として乳酸を重縮合して得られるものであることを特徴とする（１）に記載の熱収縮性生分解フィルムが提供され、
（３）脂肪族共重合ポリエステル（Ｃ）が、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてコハク酸およびアジピン酸、脂肪族オキシカルボン酸として乳酸を重縮合して得られるものであることを特徴とする（１）または（２）記載の熱収縮性生分解フィルムが提供され、
（４）脂肪族−芳香族共重合ポリエステル（Ｂ）が、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてアジピン酸、芳香族ジカルボン酸としてテレフタル酸を重縮合して得られるものであることを特徴とする（１）〜（３）のいずれかに記載の熱収縮性生分解フィルムが提供され、
（５）縦方向および横方向のヤング率が７００〜２５００ＭＰａであり、
８０℃のグリセリン中での縦方向および横方向の収縮率が３０％以上であることを特徴とする請求項（１）〜（４）のいずれかに記載の熱収縮性生分解フィルムが提供され、
（６）全層の厚みに対する各樹脂層の合計厚み割合が、
主としてポリ乳酸（Ａ）からなるＡ層が２０〜７０％、
主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層が１０〜７５％、
主として脂肪族共重合ポリエステル（Ｃ）からなるＣ層が５〜４０％、
であることを特徴とする（１）〜（５）のいずれかに記載の熱収縮性生分解フィルムが提供される。
As a result of intensive studies, the inventors of the present application have obtained a layer A mainly composed of polylactic acid (A) and a layer B mainly composed of aliphatic-aromatic copolymer polyester (B). It is found that a heat-shrinkable biodegradable film in which the above-mentioned problems are solved can be obtained by laminating the A layer and the B layer so as not to be adjacent to each other through the C layer and the biaxial stretching. It came.
That is, the present invention
(1) primarily the A layer made of polylactic acid (A), predominantly aliphatic - B layer composed of an aromatic copolyester (B), C layer is mainly composed of an aliphatic copolyester (C), A layer / A heat-shrinkable film that is laminated in the order of C layer / B layer / C layer / A layer and biaxially stretched from an unstretched film obtained by extruding each resin from a plurality of extruders ,
The aliphatic-aromatic copolymer polyester (B) is obtained by polycondensation of aliphatic and aromatic dicarboxylic acids and aliphatic diols, and the aliphatic copolymer polyester (C) is an aliphatic oxycarboxylic acid. And a heat-shrinkable biodegradable film characterized by being obtained by polycondensation of an aliphatic dicarboxylic acid and an aliphatic diol,
(2) The aliphatic copolymer polyester (C) is obtained by polycondensation of 1,4-butanediol as an aliphatic diol, succinic acid as an aliphatic dicarboxylic acid, and lactic acid as an aliphatic oxycarboxylic acid. A heat-shrinkable biodegradable film as described in (1) is provided,
( 3 ) An aliphatic copolyester (C) obtained by polycondensation of 1,4-butanediol as an aliphatic diol, succinic acid and adipic acid as an aliphatic dicarboxylic acid, and lactic acid as an aliphatic oxycarboxylic acid The heat-shrinkable biodegradable film according to (1) or (2) is provided,
( 4 ) An aliphatic-aromatic copolymer polyester (B) obtained by polycondensation of 1,4-butanediol as an aliphatic diol, adipic acid as an aliphatic dicarboxylic acid, and terephthalic acid as an aromatic dicarboxylic acid The heat-shrinkable biodegradable film according to any one of (1) to ( 3 ) is provided,
( 5 ) Young's modulus in the longitudinal direction and the transverse direction is 700 to 2500 MPa,
The heat shrinkable biodegradable film according to any one of claims (1) to ( 4), wherein the shrinkage in the vertical direction and the horizontal direction in glycerin at 80 ° C is 30% or more. ,
( 6 ) The total thickness ratio of each resin layer to the thickness of all layers is
20 to 70% of A layer mainly composed of polylactic acid (A),
10 to 75% of the B layer mainly composed of the aliphatic-aromatic copolymer polyester (B),
5 to 40% of C layer mainly composed of aliphatic copolyester (C),
The heat-shrinkable biodegradable film according to any one of (1) to ( 5 ) is provided.
本発明の熱収縮性生分解フィルムは柔軟性、透明性および低温収縮性に優れており、熱収縮包装後にフィルムの白濁が発生しないので、広い包装条件範囲で美麗な包装体を得られるという効果がある。 The heat-shrinkable biodegradable film of the present invention is excellent in flexibility, transparency and low-temperature shrinkage, and since the film does not become cloudy after heat-shrink packaging, it is possible to obtain a beautiful package in a wide range of packaging conditions. There is.
以下、本発明の内容を詳細に説明する。
本発明の熱収縮性生分解フィルムに用いられるポリ乳酸（Ａ）としては、主としてＬ−乳酸またはＤ−乳酸の単独重合体や共重合体、例えば、構造単位がＬ−乳酸であるポリＬ−乳酸や、構造単位がＤ−乳酸であるポリＤ−乳酸、Ｌ−乳酸とＤ−乳酸の共重合体であるポリＬＤ−乳酸などが例示される。また、上記ポリ乳酸の単独重合体や共重合体を単独で使用しても良いし、複数を混合して使用しても良い。
Hereinafter, the contents of the present invention will be described in detail.
The polylactic acid (A) used in the heat-shrinkable biodegradable film of the present invention is mainly a homopolymer or copolymer of L-lactic acid or D-lactic acid, for example, poly L- whose structural unit is L-lactic acid. Examples thereof include lactic acid, poly-D-lactic acid whose structural unit is D-lactic acid, and poly-LD-lactic acid which is a copolymer of L-lactic acid and D-lactic acid. Moreover, the said polylactic acid homopolymer and copolymer may be used independently, and plural may be mixed and used.
また、ポリ乳酸（Ａ）は、重縮合法や開環重合法などの従来公知の方法で製造されたものを使用することができる。例えば、Ｌ−乳酸やＤ−乳酸またはこれらの混合物を直接脱水重縮合することで任意の組成を持つポリ乳酸が得られる。また、開環重合法では乳酸の環状二量体であるラクチドを、必要に応じて重合調整剤なども用いながら、所定の触媒存在下で開環重合して任意の組成を持つポリ乳酸を得られる。上記ラクチドには、Ｌ−乳酸の二量体であるＬ−ラクチド、Ｄ−乳酸の二量体であるＤ−ラクチド、Ｌ−乳酸とＤ−乳酸の二量体であるＬＤ−ラクチドがあり、これらを必要に応じて混合することにより任意の組成、すなわち様々な結晶性を有する重合体を得ることができる。
ポリＬＤ−乳酸は、Ｌ−乳酸またはＤ−乳酸の主構造を構成するいずれか一方の構造単位が９０％以上占めるものが、結晶性が高いので耐熱性に優れ、延伸加工性や熱収縮特性に優れているので好ましい。
Moreover, what was manufactured by conventionally well-known methods, such as a polycondensation method and a ring-opening polymerization method, can be used for polylactic acid (A). For example, polylactic acid having an arbitrary composition can be obtained by directly dehydrating polycondensation of L-lactic acid, D-lactic acid or a mixture thereof. In addition, in the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, is subjected to ring-opening polymerization in the presence of a predetermined catalyst while using a polymerization regulator as necessary to obtain polylactic acid having an arbitrary composition. It is done. The lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and LD-lactide, which is a dimer of L-lactic acid and D-lactic acid, A polymer having any composition, that is, various crystallinity can be obtained by mixing them as necessary.
Poly LD-lactic acid is composed of 90% or more of either structural unit constituting the main structure of L-lactic acid or D-lactic acid, and has high crystallinity, so it has excellent heat resistance, stretch processability and heat shrinkage properties. It is preferable because of its superiority.
また、本発明の熱収縮性生分解フィルムに用いられる脂肪族共重合ポリエステル（Ｃ）としては、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてコハク酸、脂肪族オキシカルボン酸として乳酸を直接脱水重縮合して得られる脂肪族共重合ポリエステル（Ｃ）、または、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてコハク酸およびアジピン酸、脂肪族オキシカルボン酸として乳酸を直接脱水重縮合して得られる脂肪族共重合ポリエステル（Ｃ）が好適に利用される。さらに、１９０℃、せん断速度１００（ｓｅｃ−１）における溶融粘度が４００〜２，０００（Ｐａ・ｓ）であり、融点が８０〜１２０℃である上記脂肪族共重合ポリエステル（Ｃ）がより好適に利用される。
上記の様な脂肪族共重合ポリエステルとしては、三菱化学（株）から市販されている「ＧＳ Ｐｌａ」（商品名）などを例示することができる。
The aliphatic copolyester (C) used in the heat-shrinkable biodegradable film of the present invention includes 1,4-butanediol as an aliphatic diol, succinic acid as an aliphatic dicarboxylic acid, and aliphatic oxycarboxylic acid. Aliphatic copolyester (C) obtained by direct dehydration polycondensation of lactic acid, or 1,4-butanediol as aliphatic diol, succinic acid and adipic acid as aliphatic dicarboxylic acid, lactic acid as aliphatic oxycarboxylic acid An aliphatic copolymer polyester (C) obtained by direct dehydration polycondensation of is preferably used. Furthermore, the aliphatic copolyester (C) having a melt viscosity of 400 to 2,000 (Pa · s) at 190 ° C. and a shear rate of 100 (sec −1 ) and a melting point of 80 to 120 ° C. is more preferable. Used for
Examples of the aliphatic copolymer polyester as described above include “GS Pla” (trade name) commercially available from Mitsubishi Chemical Corporation.
さらに、本発明の熱収縮性生分解フィルムに用いられる脂肪族−芳香族共重合ポリエステル（Ｂ）は、脂肪族ジオールとして１，４−ブタンジオール、脂肪族ジカルボン酸としてアジピン酸、芳香族ジカルボン酸としてテレフタル酸を重縮合して得られる、柔軟性に富んだ脂肪族−芳香族共重合ポリエステル（Ｂ）が好適に利用される。さらに、ジカルボン酸成分としてテレフタル酸の割合が３０〜６０ｍｏｌ％であるものがより好適に利用される。
上記のような脂肪族−芳香族共重合ポリエステル（Ｂ）としては、ＢＡＳＦ社から市販されている「エコフレックス」（商品名）などを例示することができる。
Further, the aliphatic-aromatic copolymer polyester (B) used in the heat-shrinkable biodegradable film of the present invention is composed of 1,4-butanediol as an aliphatic diol, adipic acid as an aliphatic dicarboxylic acid, and aromatic dicarboxylic acid. The aliphatic-aromatic copolymer polyester (B) rich in flexibility obtained by polycondensation of terephthalic acid is preferably used. Furthermore, what has the ratio of a terephthalic acid as a dicarboxylic acid component of 30-60 mol% is utilized more suitably.
Examples of the aliphatic-aromatic copolymer polyester (B) described above include “Ecoflex” (trade name) commercially available from BASF.
本発明の熱収縮性生分解フィルムは、主としてポリ乳酸（Ａ）からなるＡ層と、主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層、脂肪族ジオール成分と脂肪族ジカルボン酸成分、脂肪族オキシカルボン酸成分から構成される脂肪族共重合ポリエステル（Ｃ）を主成分とするＣ層の少なくとも三層からなり、Ａ層とＢ層が隣接しないようにＡ層とＢ層はＣ層を介して積層されなければならない。例えば、Ａ層／Ｃ層／Ｂ層の順に積層されなければならない。
主としてポリ乳酸（Ａ）からなるＡ層と主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層が隣接するように積層した場合には、Ａ層とＢ層の層間の接着強度が弱く、さらに、ポリ乳酸（Ａ）と脂肪族−芳香族共重合ポリエステル（Ｂ）ではフィルム収縮時の収縮率や収縮速度、収縮応力などの収縮挙動が異なる。そのため、Ａ層とＢ層が隣接して積層されている熱収縮性生分解フィルムを用いて熱収縮包装を行うとポリ乳酸（Ａ）からなるＡ層と脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層との層間の界面でズレが生じ、フィルムが白濁して収縮包装後の包装体の美麗性が損なわれてしまう。
The heat-shrinkable biodegradable film of the present invention comprises an A layer mainly composed of polylactic acid (A), a B layer mainly composed of aliphatic-aromatic copolymer polyester (B), an aliphatic diol component and an aliphatic dicarboxylic acid component. The A layer and the B layer are composed of at least three layers of a C layer composed mainly of an aliphatic copolyester (C) composed of an aliphatic oxycarboxylic acid component, so that the A layer and the B layer are not adjacent to each other. Must be stacked through layers. For example, they must be laminated in the order of A layer / C layer / B layer.
When the A layer mainly composed of polylactic acid (A) and the B layer mainly composed of aliphatic-aromatic copolymer polyester (B) are laminated adjacent to each other, the adhesive strength between the A layer and the B layer is weak. Furthermore, the polylactic acid (A) and the aliphatic-aromatic copolymer polyester (B) have different shrinkage behaviors such as shrinkage rate, shrinkage rate, and shrinkage stress during film shrinkage. Therefore, when heat shrink packaging is performed using a heat shrinkable biodegradable film in which the A layer and the B layer are laminated adjacent to each other, the A layer made of polylactic acid (A) and the aliphatic-aromatic copolymer polyester (B ), The film is clouded and the beauty of the package after shrink wrapping is impaired.
一方、脂肪族ジオール成分と脂肪族ジカルボン酸、脂肪族オキシカルボン酸を重縮合して得られる脂肪族共重合ポリエステル（Ｃ）は、ポリ乳酸（Ａ）および脂肪族−芳香族共重合ポリエステル（Ｂ）との層間接着性が良好である。そのため、ポリ乳酸（Ａ）からなるＡ層と脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層の間に、該脂肪族共重合ポリエステル（Ｃ）を主成分とするＣ層を配することにより、Ａ層とＣ層間およびＢ層とＣ層間の接着強度が向上し、ポリ乳酸（Ａ）と脂肪族−芳香族共重合ポリエステル（Ｂ）の収縮挙動が著しく異なっていても、各層間の界面でズレが発生しないので、収縮包装後にフィルムが白濁して包装体の美麗性が損なわれることがない。 On the other hand, an aliphatic copolymer polyester (C) obtained by polycondensation of an aliphatic diol component, an aliphatic dicarboxylic acid and an aliphatic oxycarboxylic acid is composed of polylactic acid (A) and an aliphatic-aromatic copolymer polyester (B). ). Therefore, a C layer mainly composed of the aliphatic copolymer polyester (C) is disposed between the A layer composed of polylactic acid (A) and the B layer composed of the aliphatic-aromatic copolymer polyester (B). This improves the adhesive strength between the A layer and the C layer and between the B layer and the C layer, and even if the shrinkage behavior of the polylactic acid (A) and the aliphatic-aromatic copolymer polyester (B) is remarkably different, Therefore, the film does not become cloudy after shrink wrapping and the beauty of the package is not impaired.
また、主としてポリ乳酸（Ａ）からなるＡ層と主として脂肪族共重合ポリエステル（Ｃ）からなるＣ層、主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層は、ポリ乳酸（Ａ）からなるＡ層が両外層となるように積層されていることが好ましい。例えば、Ａ層／Ｃ層／Ｂ層／Ｃ層／Ａ層の順で積層されていることが好ましい。
ポリ乳酸（Ａ）は、透明性ならびに光沢に優れているので、ポリ乳酸（Ａ）からなるＡ層を両外層に位置するように各層を積層することで、透明性ならびに光沢に優れた熱収縮性生分解フィルムを得ることが可能となる。こうして得られる熱収縮性生分解フィルムの透明性は、ヘーズ値で４．０以下であることが好ましい。ヘーズ値が４．０を超えると、フィルムの曇りによって被包装物がくすんで見えてしまい、ディスプレー効果が損なわれるので好ましくない。
Also, mainly C layer consisting of polylactic acid A layer mainly aliphatic copolyester consisting (A) (C), predominantly aliphatic - aromatic copolymerized made of polyester (B) B layer, polylactic acid (A) It is preferable to laminate | stack so that A layer which consists of may become both outer layers. For example, the layers are preferably laminated in the order of A layer / C layer / B layer / C layer / A layer.
Since polylactic acid (A) is excellent in transparency and gloss, by laminating each layer so that the A layer made of polylactic acid (A) is located in both outer layers, heat shrink excellent in transparency and gloss A sex biodegradable film can be obtained. The heat-shrinkable biodegradable film thus obtained preferably has a haze value of 4.0 or less. If the haze value exceeds 4.0, the packaged object will appear dull due to cloudiness of the film, and the display effect will be impaired, which is not preferable.
本発明の熱収縮性生分解フィルムの８０℃のグリセリン中での縦方向および横方向の収縮率は３０％以上であることが好ましい。８０℃グリセリン中での収縮率が３０％以上、つまり低温収縮性に優れていれば、収縮包装の際のフィルム収縮温度の設定を低く、かつ、加熱時間も短く設定できるので、熱によって変質しやすい被包装物の包装に好適に利用される。８０℃グリセリン中での収縮率が３０％未満だと収縮包装した際にフィルムのコーナー部分が十分に収縮しないで硬い突起状になった、いわゆる、角（つの）が発生したり、被包装体と接する部分が十分に収縮しないでシワが発生したりして美麗な包装体が得られない。 The heat shrinkable biodegradable film of the present invention preferably has a shrinkage ratio of 30% or more in the vertical and horizontal directions in glycerin at 80 ° C. If the shrinkage rate in glycerin at 80 ° C is 30% or higher, that is, excellent in low-temperature shrinkability, the film shrinkage temperature can be set low during shrink wrapping and the heating time can be set short, so it is altered by heat. It is suitably used for packaging easy-to-be packaged items. When the shrinkage rate in glycerin at 80 ° C. is less than 30%, when the film is shrink-wrapped, the corner portion of the film is not sufficiently shrunk and becomes a hard protrusion, so-called corner (one) is generated, or packaged body A beautiful package cannot be obtained because wrinkles are generated because the portion in contact with the substrate does not shrink sufficiently.
また、熱収縮性生分解フィルムのヤング率は、７００〜２５００ＭＰａであることが好ましい。ヤング率が２５００ＭＰａを超えると、熱収縮性生分解フィルムの柔軟性が低下し、収縮包装を行った際に、収縮しきらないで残った角（つの）の部分が硬くなり、包装袋の美観が損なわれるのみならず、包装体を取り扱う際に硬く残った角（つの）の部分で手指を傷つけたり、包装体を積み重ねて梱包した際に角（つの）の部分でフィルムが破れたりする恐れがあるので好ましくない。一方、７００ＭＰａ未満では、熱収縮性生分解フィルムの柔軟性が増すものの、熱収縮性生分解フィルムの製膜時の取り扱いや、高速自動包装機で使用した場合に包装適性が低下するので好ましくない。 Moreover, it is preferable that the Young's modulus of a heat-shrinkable biodegradable film is 700-2500 MPa. When the Young's modulus exceeds 2500 MPa, the flexibility of the heat-shrinkable biodegradable film decreases, and when shrink-wrapping is performed, the remaining corners (one) become hard and the aesthetics of the packaging bag are hardened. In addition to damage, the fingers may be damaged by the hard left corners when handling the package, or the film may be torn at the corners when the packages are stacked and packed This is not preferable. On the other hand, if it is less than 700 MPa, the flexibility of the heat-shrinkable biodegradable film is increased, but it is not preferable because the packaging suitability is lowered when the heat-shrinkable biodegradable film is handled during film formation or when used in a high-speed automatic packaging machine. .
さらに、全層の厚みに対する各樹脂層の合計の厚み割合は、ポリ乳酸（Ａ）からなるＡ層が２０〜７０％、脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層が１０〜７５％、脂肪族共重合ポリエステル（Ｃ）からなるＣ層が５〜４０％であることが好ましい。
さらに、ポリ乳酸（Ａ）からなるＡ層の合計の厚み割合は、５０〜７０％であることがより好ましい。ポリ乳酸（Ａ）は、デンプンなどの植物由来原料から製造されている。植物は大気中の二酸化炭素を固定するため、たとえ廃棄後に焼却された場合でも、二酸化炭素があらたに発生することがない。そのため、生分解性の観点だけではなく、地球温暖化の解決策の一つとして植物由来原料を使用した樹脂に対する社会の関心は高まっており、植物由来原料から製造されたポリ乳酸（Ａ）をより多く使用することが好ましく、Ａ層の合計の厚み割合が５０％以上あることが好ましい。
Furthermore, the total thickness ratio of each resin layer with respect to the thickness of all layers is 20 to 70% for the A layer made of polylactic acid (A), and 10 to 10 for the B layer made of the aliphatic-aromatic copolymer polyester (B). It is preferable that C layer which consists of 75% and aliphatic copolyester (C) is 5 to 40%.
Furthermore, the total thickness ratio of the A layer made of polylactic acid (A) is more preferably 50 to 70%. Polylactic acid (A) is manufactured from plant-derived raw materials such as starch. Since plants fix carbon dioxide in the atmosphere, carbon dioxide will not be newly generated even if incinerated after disposal. Therefore, not only from the viewpoint of biodegradability, but also as a solution to global warming, there is an increasing social interest in resins using plant-derived raw materials. Polylactic acid (A) produced from plant-derived raw materials has been increased. It is preferable to use more, and it is preferable that the total thickness ratio of the A layer is 50% or more.
脂肪族共重合ポリエステル（Ｃ）からなるＣ層の合計厚みの割合が５％未満でれば、Ｃ層の厚みのバラツキによって極端に薄い場所が生じた場合に、所定の層間接着性が得られなくなり、収縮包装後にフィルムの白濁が発生することがあるので好ましくない。一方、脂肪族共重合ポリエステル（Ｃ）からなるＣ層の合計厚みの割合が４０％を超えると、透明性が低下するので好ましくない。さらに、Ｃ層の厚みをこれ以上厚くしても、ポリ乳酸（Ａ）からなるＡ層、および、脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層との層間の接着強度の向上は見られない。 If the ratio of the total thickness of the C layer made of the aliphatic copolyester (C) is less than 5%, a predetermined interlayer adhesion can be obtained when an extremely thin place is generated due to the variation in the thickness of the C layer. This is not preferable because the film may become cloudy after shrink wrapping. On the other hand, when the ratio of the total thickness of the C layer made of the aliphatic copolymer polyester (C) exceeds 40%, the transparency is lowered, which is not preferable. Furthermore, even if the thickness of the C layer is increased further, the adhesion strength between the A layer made of polylactic acid (A) and the B layer made of aliphatic-aromatic copolymer polyester (B) is improved. can not see.
本発明の生分解性二軸延伸フィルムの厚みは、５〜３００μｍであることが好ましい。高速自動包装機などで包装を行う軟包装の用途に使用する場合には、１０〜５０μｍであることがより好ましい。 The thickness of the biodegradable biaxially stretched film of the present invention is preferably 5 to 300 μm. In the case of use for soft packaging where packaging is performed with a high-speed automatic packaging machine or the like, the thickness is more preferably 10 to 50 μm.
なお、本発明の熱収縮性生分解フィルムには、本発明の目的を損なわない範囲において、酸化防止剤や紫外線吸収剤、光安定剤、滑剤、ブロッキング防止剤、粘着性付与剤、防曇剤、耐電防止剤、各種充填剤などの従来公知の添加剤やその他の合成樹脂を適宜配合しても良い。 In the heat-shrinkable biodegradable film of the present invention, an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, an anti-blocking agent, a tackifier, and an antifogging agent are provided as long as the object of the present invention is not impaired. Conventionally known additives such as antistatic agents and various fillers and other synthetic resins may be appropriately blended.
本発明の熱収縮性生分解フィルムは、従来公知の方法によって製造される。例えば、サーキュラーダイを備えた複数の押出機から各々の樹脂を押し出して得られたチューブ状の未延伸フィルムを同時二軸延伸することによって製造することができる。また、Ｔ型ダイスを備えた複数の押出機から各々の樹脂を押し出して得られたフラットな未延伸フィルムをテンター延伸機によって同時二軸延伸、或いは逐次二軸延伸することによっても製造することができる。 The heat-shrinkable biodegradable film of the present invention is produced by a conventionally known method. For example, it can be manufactured by simultaneously biaxially stretching a tube-shaped unstretched film obtained by extruding each resin from a plurality of extruders equipped with a circular die. It can also be produced by simultaneously biaxially or sequentially biaxially stretching a flat unstretched film obtained by extruding each resin from a plurality of extruders equipped with T-shaped dies with a tenter stretching machine. it can.
以下、実施例及び比較例によって本発明を詳細に説明するが、本発明は以下に記載される事項によって限定されるものではない。なお、本発明における熱収縮性生分解フィルムの評価方法は以下の通りである。 EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited by the matter described below. In addition, the evaluation method of the heat-shrinkable biodegradable film in the present invention is as follows.
［熱収縮性］
フィルムを裁断して、縦方向（長手方向）、横方向ともに１００ｍｍの正方形の試験片を作成する。この試験片を８０℃に設定したグリセリン中に３０秒間浸漬した後、試験片の縦方向および横方向の寸法（Ｌ）を測定して下記の式を用いて収縮率を算出する。
収縮率（％）＝１００×（１００−Ｌ）／１００［Ｌ：所定温度に設定されたグリセリン中に３０秒間浸漬した後の試験片の長さ（ｍｍ）］
［ヤング率］
ＡＳＴＭ Ｄ ８８２に準拠して、引張速度５ｍｍ／ｍｉｎで測定する。
［透明性（ヘーズ）］
ＡＳＴＭ Ｄ １００３に準拠して、株式会社村上色彩技術研究所製ＨＭ−１５０にて測定する。
［接着強度］
二軸延伸前の未延伸フィルムを１０ｍｍ幅に裁断し、引張速度５００ｍｍ／ｍｉｎで、各層間の１８０°剥離強度を測定する。
［収縮後のフィルム白濁］
各種フィルムで被包装物（ポリプロピレン製、幅１２０ｍｍ×長さ１９５ｍｍ×高さ３０ｍｍの箱状体）を外周に対する余裕率１８％で仮包装した後、協和電機社製熱風循環式収縮トンネルＰＳ−２４００ＦＦを通過させて収縮包装体を得た。なお、収縮トンネルの設定条件は以下の通りである。
設定温度：１６０℃
通過時間：５秒
収縮後のフィルムの白濁の状態を下記の判断基準に基づき目視により評価した。
○：白濁なし、または、ほとんどなし。
×：白濁あり。
[Heat shrinkage]
The film is cut to produce a square test piece of 100 mm in both the vertical direction (longitudinal direction) and the horizontal direction. After immersing this test piece in glycerin set at 80 ° C. for 30 seconds, the vertical and horizontal dimensions (L) of the test piece are measured, and the shrinkage is calculated using the following equation.
Shrinkage rate (%) = 100 × (100−L) / 100 [L: length of test piece after being immersed in glycerin set to a predetermined temperature for 30 seconds (mm)]
[Young's modulus]
Measured at a tensile speed of 5 mm / min according to ASTM D882.
[Transparency (haze)]
Based on ASTM D 1003, measurement is performed with HM-150 manufactured by Murakami Color Research Laboratory.
[Adhesive strength]
The unstretched film before biaxial stretching is cut into a width of 10 mm, and the 180 ° peel strength between the layers is measured at a tensile speed of 500 mm / min.
[Film turbidity after shrinkage]
After temporarily wrapping an article to be packaged (made of polypropylene, width 120 mm × length 195 mm × height 30 mm) with various films with a margin of 18% with respect to the outer periphery, hot air circulation type shrinkable tunnel PS-2400FF made by Kyowa Denki Co., Ltd. Was passed through to obtain a shrink wrap. The setting conditions for the contracting tunnel are as follows.
Set temperature: 160 ° C
Passing time: The state of cloudiness of the film after shrinking for 5 seconds was visually evaluated based on the following criteria.
○: No cloudiness or almost none.
X: There is cloudiness.
実施例及び比較例には以下の樹脂を使用した。
＜ポリ乳酸（Ａ）＞
Ｌ−乳酸：９６％、Ｄ−乳酸：４％からなるポリ乳酸（三井化学（株）製、商品名：レイシアＨ４４０、密度：１．２５ｇ／ｃｍ３、融点：１５５℃）・・以下ＰＬＡと略称する。
＜脂肪族−芳香族共重合ポリエステル（Ｂ）＞
１，４−ブタンジオールとアジピン酸、テレフタル酸の共重合体であるポリブチレンアジペートテレフタレート共重合体（ＢＡＳＦ社製、商品名：エコフレックスＦＢＸ７０１１、密度：１．２６ｇ／ｃｍ３、融点：１０５〜１１５℃）・・以下ＰＢＡＴと略称する。
＜脂肪族共重合ポリエステル（Ｃ）＞
１，４−ブタンジオールとコハク酸、アジピン酸、乳酸を直接脱水重縮合して得られる脂肪族共重合ポリエステル（三菱化学（株）製、商品名：ＧＳ Ｐｌａ ＡＤ９２Ｗ、密度：１．２５ｇ／ｃｍ３、融点：８７℃）・・以下ＰＢＳＬａと略称する。
The following resins were used in Examples and Comparative Examples.
<Polylactic acid (A)>
L-lactic acid: 96%, D-lactic acid: 4% polylactic acid (Mitsui Chemicals, trade name: Lacia H440, density: 1.25 g / cm 3 , melting point: 155 ° C.) Abbreviated.
<Aliphatic-aromatic copolymer polyester (B)>
Polybutylene adipate terephthalate copolymer which is a copolymer of 1,4-butanediol, adipic acid and terephthalic acid (manufactured by BASF, trade name: Ecoflex FBX7011, density: 1.26 g / cm 3 , melting point: 105- 115 ° C.) .. Hereinafter abbreviated as PBAT.
<Aliphatic copolymer polyester (C)>
Aliphatic copolyester obtained by direct dehydration polycondensation of 1,4-butanediol, succinic acid, adipic acid, and lactic acid (Mitsubishi Chemical Corporation, trade name: GS Pla AD92W, density: 1.25 g / cm 3. Melting point: 87 ° C.) Hereinafter, abbreviated as PBSLa.
［実施例１〜３］
エルカ酸アミド（滑剤）２００ｐｐｍを含有するＰＬＡおよびＰＢＳＬａ、ＰＢＡＴを三台の押出機及び下向きサーキュラーダイを備えたチューブラー製膜機に供給し、溶融押出しした後、直ちに３５℃の水で冷却し、ＰＬＡ／ＰＢＳＬａ／ＰＢＡＴ／ＰＢＳＬａ／ＰＬＡの順に積層されたチューブ状の五層の未延伸フィルムを得た。各層の厚みの割合は表１に示した通りである。次いで、該未延伸フィルムを卓上二軸延伸試験機（岩本製作所製）にて、延伸温度１００℃、余熱時間２分、延伸速度３０ｍｍ／ｓｅｃ、延伸倍率４．０×４．０倍で同時二軸延伸を行い、厚さ１５μｍの生分解性主縮フィルムを得た。こうして得られた熱収縮性生分解フィルムの性能評価結果も併せて表１に示す。
[Examples 1 to 3]
PLA containing 200 ppm of erucic acid amide (lubricant), PBSLa, and PBAT were supplied to a tubular film forming machine equipped with three extruders and a downward circular die, melt-extruded, and immediately cooled with water at 35 ° C. A tube-shaped five-layer unstretched film laminated in the order of PLA / PBSLa / PBAT / PBSLa / PLA was obtained. The ratio of the thickness of each layer is as shown in Table 1. Subsequently, the unstretched film was simultaneously measured with a desktop biaxial stretching tester (manufactured by Iwamoto Seisakusho) at a stretching temperature of 100 ° C., a preheating time of 2 minutes, a stretching speed of 30 mm / sec, and a stretching ratio of 4.0 × 4.0. The film was axially stretched to obtain a biodegradable main shrink film having a thickness of 15 μm. The performance evaluation results of the heat-shrinkable biodegradable film thus obtained are also shown in Table 1.
［比較例１］
エルカ酸アミド（滑剤）２００ｐｐｍを含有するＰＬＡおよびＰＢＡＴを使用して、実施例と同様にしてＰＬＡ／ＰＢＡＴ／ＰＬＡの順に積層された三層で、厚さ１５μｍの熱収縮性生分解フィルムを得た。得られた延伸フィルムについて、実施例と同様にして性能評価を行い、その結果と実施例１の結果を併せて表２に示す。
[Comparative Example 1]
Using PLA and PBAT containing 200 ppm of erucic acid amide (lubricant), a heat-shrinkable biodegradable film having a thickness of 15 μm was obtained with three layers laminated in the order of PLA / PBAT / PLA in the same manner as in the Examples. It was. About the obtained stretched film, performance evaluation was performed similarly to the Example, and the result and the result of Example 1 are shown together in Table 2.
実施例１〜３で得られた熱収縮性生分解フィルムは、透明性、柔軟性、収縮特性、製膜性優れていた。また、未延伸フィルムにおいてＰＬＡ層とＰＢＳＬａ層の間の剥離強度が２．９Ｎ／１０ｍｍと強固に接着しており、さらに、ＰＢＡＴ層とＰＢＳＬａ層の間は剥離しないほど接着しており、二軸延伸を行った後の熱収縮性フィルムを用いて収縮包装してもフィルムの白濁は発生しなかった。尚、実施例１〜３で得られた生分解性収縮フィルの包装適性は、フィルムのコーナー部分が十分に収縮しないで硬く突起状になった、いわゆる角（つの）の発生もなく良好であった。
一方、比較例１で得られたＰＬＡとＰＢＡＴの二種三層構成の熱収縮性生分解フィルムでは、透明性、柔軟性、収縮特性、製膜性優れているものの、収縮包装後フィルムの全面にわたって白濁が発生し、包装体の美麗性が劣っていた。また、未延伸フィルムのＰＬＡ層とＰＢＡＴ層間の剥離強度は０．０５Ｎ／１０ｍｍであり、容易に剥離した。
The heat-shrinkable biodegradable films obtained in Examples 1 to 3 were excellent in transparency, flexibility, shrinkage characteristics, and film forming properties. In the unstretched film, the peel strength between the PLA layer and the PBSLa layer is firmly adhered to 2.9 N / 10 mm, and the PBAT layer and the PBSLa layer are adhered to each other so as not to peel off. Even when shrink-wrapped using the heat-shrinkable film after stretching, no cloudiness of the film occurred. The packaging suitability of the biodegradable shrinkable films obtained in Examples 1 to 3 was good without the occurrence of so-called corners (corners) where the corner portions of the film did not shrink sufficiently and became hard and protruding. It was.
On the other hand, the heat-shrinkable biodegradable film of PLA and PBAT, which is obtained in Comparative Example 1, has excellent transparency, flexibility, shrinkage characteristics, and film-forming properties. White turbidity occurred over the course of the product, and the package was not beautiful. Further, the peel strength between the PLA layer and the PBAT layer of the unstretched film was 0.05 N / 10 mm, and it was easily peeled off.
尚、実施例１〜３で得られた熱収縮性フィルムの生分解性については記載していないが、使用している樹脂の特性から、生分解性を有することは明らかである。 In addition, although it does not describe about the biodegradability of the heat-shrinkable film obtained in Examples 1-3, it is clear that it has biodegradability from the characteristic of the resin currently used.
本発明の熱収縮性生分解フィルムは、ポリ乳酸からなるフィルムの欠点である硬さや脆さがなく、柔軟性に優れている。また、収縮包装後にフィルムが白濁することなく、コーナー部分が十分に収縮しないで硬い突起状になった、いわゆる、角（つの）が発生しないので、広い包装条件範囲で美麗な収縮包装体を得ることが可能となる。 The heat-shrinkable biodegradable film of the present invention does not have hardness and brittleness, which are disadvantages of a film made of polylactic acid, and is excellent in flexibility. In addition, the film does not become cloudy after shrink wrapping, and the corner portion is not sufficiently shrunk, so that a so-called corner (one) does not occur, so a beautiful shrink wrapping body is obtained over a wide range of packaging conditions. It becomes possible.
Claims (6)
脂肪族−芳香族共重合ポリエステル（Ｂ）が、脂肪族および芳香族ジカルボン酸と脂肪族ジオールを重縮合して得られるものであり、脂肪族共重合ポリエステル（Ｃ）が、脂肪族オキシカルボン酸と脂肪族ジカルボン酸ならびに脂肪族ジオールを重縮合して得られるものであることを特徴とする熱収縮性生分解フィルム。 A layer mainly composed of polylactic acid (A), B layer mainly composed of aliphatic-aromatic copolymer polyester (B), C layer mainly composed of aliphatic copolymer polyester (C) , A layer / C layer / A heat-shrinkable film formed by biaxially stretching an unstretched film obtained by laminating in order B layer / C layer / A layer and extruding each resin from a plurality of extruders ,
The aliphatic-aromatic copolymer polyester (B) is obtained by polycondensation of aliphatic and aromatic dicarboxylic acids and aliphatic diols, and the aliphatic copolymer polyester (C) is an aliphatic oxycarboxylic acid. A heat-shrinkable biodegradable film obtained by polycondensation of an aliphatic dicarboxylic acid and an aliphatic diol.
８０℃のグリセリン中での縦方向および横方向の収縮率が３０％以上であることを特徴とする請求項１〜４のいずれかに記載の熱収縮性生分解フィルム。 The Young's modulus in the longitudinal and transverse directions is 700-2500 MPa,
The heat-shrinkable biodegradable film according to any one of claims 1 to 4, wherein the shrinkage in the vertical direction and the horizontal direction in glycerin at 80 ° C is 30% or more .
主としてポリ乳酸（Ａ）からなるＡ層が２０〜７０％、
主として脂肪族−芳香族共重合ポリエステル（Ｂ）からなるＢ層が１０〜７５％、
主として脂肪族共重合ポリエステル（Ｃ）からなるＣ層が５〜４０％、
であることを特徴とする請求項１〜５のいずれかに記載の熱収縮性生分解フィルム。
The total thickness ratio of each resin layer to the thickness of all layers is
20 to 70% of A layer mainly composed of polylactic acid (A),
10 to 75% of the B layer mainly composed of the aliphatic-aromatic copolymer polyester (B),
5 to 40% of C layer mainly composed of aliphatic copolyester (C),
The heat-shrinkable biodegradable film according to claim 1, wherein the film is a heat-shrinkable biodegradable film.
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