JP3664969B2 - Heat-shrinkable polylactic acid polymer film - Google Patents

Heat-shrinkable polylactic acid polymer film Download PDF

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Publication number
JP3664969B2
JP3664969B2 JP2000330921A JP2000330921A JP3664969B2 JP 3664969 B2 JP3664969 B2 JP 3664969B2 JP 2000330921 A JP2000330921 A JP 2000330921A JP 2000330921 A JP2000330921 A JP 2000330921A JP 3664969 B2 JP3664969 B2 JP 3664969B2
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film
polylactic acid
acid
heat
lactic acid
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JP2002128918A (en
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隆 比留間
滋憲 寺田
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Mitsubishi Plastics Inc
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Mitsubishi Plastics Inc
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  • Manufacture Of Macromolecular Shaped Articles (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Biological Depolymerization Polymers (AREA)

Description

【0001】
【発明の属する技術分野】
本発明はポリ乳酸系重合体を主成分とする熱収縮性フィルム状物に関し、特に、収縮包装、収縮結束包装や収縮ラベル等に好適な、耐衝撃性に優れた熱収縮性ポリ乳酸系重合体フィルム状物に関する。
【0002】
【従来の技術と発明が解決しようとする課題】
収縮包装、収縮結束包装や収縮ラベル等に用いられる熱収縮性フィルムは、ポリ塩化ビニル(PVC)、スチレン−ブタジエンブロック共重合体(SBS)、ポリエステル系樹脂等を主たる材料とすることが知られている。これらは広く利用されているが、使用後に廃棄されると、化学的に安定で生分解性がないため、ほとんど分解されることなく残留し蓄積される。そのため、ゴミ処理用地の能力を短期間で飽和させてしまう。
そこで、燃焼熱量が低く、かつ人体等に安全である生分解性の材料が要求され、多くの研究がなされてきた。その一つとして、ポリ乳酸が知られている。ポリ乳酸は、燃焼熱量がポリエチレンの半分以下であり、土中や水中で自然に加水分解が進行し、次いで微生物により無害な分解物となる。特開平5−212790号公報には、ポリ乳酸からなる熱収縮性フィルムが開示されているが、収縮温度が140〜150℃と高いので特殊な用途にしか用いることができない。
元来、ポリ乳酸のフィルムやシートは、素材が本来有する脆性のため脆くて耐衝撃性に劣っているので、実用に供し難い。特に、一軸延伸して収縮性フィルムを形成する場合には、延伸しない方向の脆性が改良されないので、かかる方向の衝撃に弱く、裂けやすい。これを改良するために、脂肪族ポリエステルをブレンドする方法が知られている。かかる方法によれば、引張試験等の低速での破断性(耐破断性)においては良好な結果が得られるものの、瞬間的な衝撃(耐衝撃性)に対しては弱く、裂けてしまう、という問題があった。
そのため、ポリ乳酸を主成分とする実質一軸延伸のフィルムにおいて、耐衝撃性に優れた熱収縮性ポリ乳酸系フィルムが求められていた。
【0003】
【課題を解決するための手段】
本発明者等は、上記課題を解決すべく鋭意検討した結果、本発明を完成するに至った。
即ち本発明の熱収縮性ポリ乳酸系重合体フィルム状物は、ポリ乳酸系重合体および芳香族脂肪族ポリエステル樹脂を主成分とする樹脂組成物からなるフィルム状物を少なくとも一方向に延伸したフィルム状物であって、80℃の温水中に10秒間浸漬した後の熱収縮率が少なくとも一方向において10%以上であり、かつ、ハイドロショット値が10kgf・mm以上であることを特徴とする。
ここで、前記芳香族脂肪族ポリエステル樹脂は、脂肪族ジカルボン酸成分、芳香族ジカルボン酸成分および脂肪族ジオール成分からなることができる。
また、前記芳香族脂肪族ポリエステル樹脂は、芳香族ジカルボン酸成分を50モル%以下の範囲で含有することができる。
【0004】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の熱収縮性ポリ乳酸系重合体フィルム状物は、ポリ乳酸系重合体および芳香族脂肪族ポリエステル樹脂を主成分とする樹脂組成物からなる。
ここでフィルム状物とは、シート又はフィルムをいう。JISにおける定義上、シートとは、薄く、一般にその厚さが長さと幅のわりには小さな平らな製品をいい、フィルムとは、長さ及び幅に比べて厚さが極めて小さく、最大厚さが任意に限定されている薄い平らな製品で、通例、ロールの形で供給されるものをいう(JIS K 6900)。したがって、シートの中でも厚さの特に薄いものがフィルムであるといえる。しかし、シートとフィルムとの境界は定かでなく、明確に区別することは困難であるので、本願においては、上記のとおり、シートとフィルムの両方を含んだ概念として「フィルム状物」の用語を使用する。
【0005】
本発明において使用されるポリ乳酸系重合体は、構造単位がL−乳酸であるポリ(L−乳酸)、構造単位がD−乳酸であるポリ(D−乳酸)、構造単位がL−乳酸及びD−乳酸であるポリ(DL−乳酸)やこれらの混合体を主成分とするものをいう。本発明においては、さらには、後述する他のヒドロキシカルボン酸単位との共重合体であってもよく、また少量の鎖延長剤残基を含んでもよい。
ポリ乳酸に共重合される上記他のヒドロキシカルボン酸単位としては、乳酸の光学異性体(L−乳酸に対してはD−乳酸、D−乳酸に対してはL−乳酸)、グリコール酸、3−ヒドロキシ酪酸、4−ヒドロキシ酪酸、2−ヒドロキシ−n−酪酸、2−ヒドロキシ−3,3−ジメチル酪酸、2−ヒドロキシ−3−メチル酪酸、2−メチル乳酸、2−ヒドロキシカプロン酸等の2官能脂肪族ヒドロキシカルボン酸やカプロラクトン、ブチロラクトン、バレロラクトン等のラクトン類が挙げられる。
【0006】
ポリ乳酸の構成としてはD−乳酸:L−乳酸=100:0〜85:15または0:100〜15:85であることが好ましい。また、D−乳酸とL−乳酸の構成割合が異なる2種類以上のポリ乳酸をブレンドすることも可能である。
D−乳酸のみ又はL−乳酸のみのポリ乳酸系重合体は結晶性樹脂となり、融点が高く、耐熱性、機械的物性に優れる傾向にある。ただし、熱収縮性フィルム状物として使用する場合には、結晶性が非常に高いと延伸時に延伸配向結晶化が進行してしまうので、熱収縮率を調製することが難しくなる。一方、DL−乳酸は、その光学異性体の割合が増加するにつれて結晶性が低下することが知られている。したがって、熱収縮性フィルム状物として使用する場合には、適度に結晶性を低下させることが好ましい。
【0007】
ポリ乳酸系重合体の重合方法としては、縮合重合法、開環重合法等公知の方法を採用することができる。例えば、縮合重合法では、L−乳酸またはD−乳酸、あるいはこれらの混合物等を直接脱水縮合重合して任意の組成を有するポリ乳酸系重合体を得ることができる。
また、開環重合法(ラクチド法)では、乳酸の環状2量体であるラクチドを、必要に応じて重合調節剤等を用いながら、適当な触媒を使用してポリ乳酸系重合体を得ることができる。なお、ラクチドには、L−乳酸の2量体であるラクチド、D−乳酸の2量体であるD−ラクチド、D−乳酸とL−乳酸の2量体であるDL−ラクチドがあり、これらを必要に応じて混合し、重合することによって任意の組成、結晶性を有するポリ乳酸を得ることができる。
【0008】
本発明において使用されるポリ乳酸系重合体は、重量平均分子量が6万〜70万であることが好ましく、より好ましくは8万〜40万、特に好ましくは10万〜30万である。分子量が小さすぎると機械物性や耐熱性等の実用物性がほとんど発現されず、大きすぎると溶融粘度が高すぎて成形加工性に劣る。
【0009】
本発明において好適に使用される芳香族脂肪族ポリエステルは、脂肪族ジカルボン酸成分、芳香族ジカルボン酸成分および脂肪族ジオール成分からなる生分解性を有する芳香族ポリエステルである。
脂肪族ジカルボン酸および脂肪族ジオールからなる脂肪族ポリエステルは生分解性を有することが知られているが、芳香族ポリエステルにおいて生分解性を発現させるためには、芳香環の合間に脂肪族鎖が存在することが必要である。そのため、本発明に用いられる芳香族脂肪族ポリエステルの芳香族ジカルボン酸成分は、50モル%以下にすることが好ましい。
芳香族ジカルボン酸成分としては、例えば、イソフタル酸、テレフタル酸、2,6−ナフタレンジカルボン酸等が挙げられ、脂肪族ジカルボン酸成分としては、例えば、コハク酸、アジピン酸、スベリン酸、セバシン酸、ドデカン二酸等が挙げられ、脂肪族ジオールとしては、例えば、エチレングリコール、1,4−ブタンジオール、1,4−シクロヘキサンジメタノール等が挙げられる。なお、芳香族ジカルボン酸成分、脂肪族ジカルボン酸成分あるいは脂肪族ジオール成分は、それぞれ2種類以上を用いることもできる。
本発明において、最も好適に用いられる芳香族ジカルボン酸成分はテレフタル酸であり、脂肪族ジカルボン酸成分はアジピン酸であり、脂肪族ジオール成分は1,4−ブタンジオールである。
【0010】
ポリ乳酸系重合体と芳香族脂肪族ポリエステルとの混合割合については、特に限定されるものではないが、PETボトルや瓶ボトルに用いられる熱収縮性ラベルの場合には、芳香族脂肪族ポリエステルが50重量%以下であることが好ましい。芳香族脂肪族ポリエステルの混合割合が50重量%を超えると、フィルム状物が柔らかくなりすぎて収縮仕上がり性が低下しやすくなる。
【0011】
本発明においては、熱収縮性ポリ乳酸系重合体フィルム状物の特性を損なわない範囲内で、他の生分解性樹脂、例えば、脂肪族ポリエステル、ポリカプロラクトン、脂肪族ポリエステルカーボネート等を配合することができる。
また、諸物性を調整する目的で、熱安定剤、光安定剤、光吸収剤、滑剤、可塑剤、無機充填材、着色剤、顔料等を添加することもできる。
【0012】
フィルム状物の厚さは用途により適宜選択され、通常の熱収縮包装等に使用できる程度の厚さであれば特に制限されず、具体的には、総厚さが約0.01〜2.0mmの範囲であることが好ましく、約0.01〜1.5mmの範囲であることが更に好ましい。
【0013】
本発明のフィルム状物の製造方法としては、ポリ乳酸系重合体および芳香族脂肪族ポリエステルを十分に乾燥し、水分を除去した後、押出機を用いて溶融混合し、押し出す方法が一般的であるが、これらに限定されるものではない。押出しには、Tダイキャスト法、チューブラー法等公知の方法を採用することができる。ただし、分解による分子量の低下等を考慮して、適宜温度設定をする必要がある。
溶融押出しされたフィルム状物は、回転するキャスティングドラム(冷却ドラム)に接触させて、あるいは空気、水等で冷却された後、熱風、温水、赤外線、マイクロウェーブ等により適当に加熱され、フィルム状物を周速差のある2個のロール間で延伸するロール法、テンターを用いてクリップでフィルム状物を把持しながらクリップ列の列間隔を拡大させて延伸するテンター法、チューブラー法等により、少なくとも一方向に延伸される。
【0014】
延伸温度や延伸倍率は、ポリ乳酸系重合体と芳香族脂肪族ポリエステルとの混合比やポリ乳酸系重合体の結晶性等により、また、適用される用途等により適宜決定されるが、一般に延伸温度は約70〜95℃の範囲で制御され、延伸倍率は収縮方向に対して約1.5〜6倍の範囲で適宜決定される。また、一軸延伸、二軸延伸等についても、用途に応じて適宜決定される。
なお、延伸後のフィルム状物は、80℃の温水中に10秒間浸漬した後の熱収縮率が少なくとも一方向において10%以上であることが好ましい。
【0015】
本発明の熱収縮性ポリ乳酸系重合体フィルム状物は、包装材や収縮ラベル材として使用することができる。この包装材や収縮ラベルが使用される被包装物としては、容器、生鮮食品等の食品等が挙げられる。容器としては、ガラス瓶、ガラス容器、硬質プラスチック容器等の硬度の高い容器、または、紙や、ポリスチレン、ポリエチレン、ポリエチレンテレフタレート等のプラスチックから成形される容器等が挙げられる。これらの容器は食品用、飲料用、薬品用等任意の用途に使用されるものである。
【0016】
【実施例】
以下に実施例を用いて具体的に説明するが、これらにより本発明は何ら制限を受けるものではない。
なお、実施例における測定値および評価は以下のようにして行った。ただし、フィルム状物の引き取り(流れ)方向をMD、その直交方向をTDと記載する。
【0017】
評価方法:
1)熱収縮率
フィルム状物を、MDが100mm、TDが100mmの大きさとなるように切断し、80℃の温水バスに10秒間浸漬した後、その標線間の寸法を測定し、次式にしたがって熱収縮率を算出した。ただし、熱収縮率は、TD方向の収縮率を測定した。
熱収縮率(%)=[{(収縮前の寸法)−(収縮後の寸法)}/(収縮前の寸法)]×100
2)引張破断伸度(耐破断性)
JIS K7127に準拠して、引張試験を行い、フィルム状物の伸びを測定して、耐破断性の代用評価を行った。試験条件は、引張速度200mm/分で雰囲気温度23℃におけるフィルム状物のMD方向のシートの伸びを測定した。なお、試験は5回行い、その平均値を求めた。フィルム状物の伸びが小さいものは耐破断性が低く、伸びが大きいものは耐破断性が高いことを示す。
3)ハイドロショット(耐衝撃性)
ハイドロショット高速衝撃試験機HTM−1型((株)島津製作所製)を用いて、耐衝撃性を測定した。100mm×100mmの大きさに切り出したフィルム状物をクランプで固定し、フィルム状物の中央に錘を落下させて衝撃を与え、フィルム状物が破壊したときの破壊エネルギーを読みとった。ただし、測定温度は23℃、錘の落下速度は3m/秒である。
【0018】
(実施例1)
L−乳酸とD−乳酸との混合割合が95.0:5.0のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4050D」)を35重量%、L−乳酸とD−乳酸との混合割合が90.3:9.7のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4060D」)を35重量%、テレフタル酸48モル%、アジピン酸52モル%、1,4−ブタンジオール100モル%からなる芳香族脂肪族ポリエステル(BASF社製、商品名「Ecoflex」)30重量%の各樹脂を、それぞれ乾燥させた。次いで、これらを混合してTダイ押出機に搭載し、温度210℃で溶融押出しし、溶融体を約43℃のキャスティングロールにて急冷し、未延伸フィルム状物を得た。続いて、未延伸フィルム状物を長手方向(MD)に65℃で1.01倍にロール延伸し、次いで、幅方向(TD)にテンターを用いて75℃で4倍に横延伸し、約50μmの熱収縮性フィルム状物を作製した。
得られたフィルム状物について、熱収縮率、引張破断伸度およびハイドロショットの評価を行った。その結果を表1に示す。
【0019】
(実施例2)
実施例1において、L−乳酸とD−乳酸との混合割合が95.0:5.0のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4050D」)を40重量%、L−乳酸とD−乳酸との混合割合が90.3:9.7のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4060D」)を40重量%、テレフタル酸43モル%、アジピン酸57モル%、1,4−ブタンジオール100モル%からなる芳香族脂肪族ポリエステル(イーストマンケミカル社製、商品名「イーストボンド14766」)20重量%の各樹脂を用いた以外は実施例1と同様にして、熱収縮性フィルム状物を得た。
得られたフィルム状物について、実施例1と同様の評価を行った。その結果を表1に示す。
【0020】
(実施例3)
実施例1において、L−乳酸とD−乳酸との混合割合が95.0:5.0のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4050D」)を35重量%、L−乳酸とD−乳酸との混合割合が90.3:9.7のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4060D」)を35重量%、テレフタル酸48モル%、アジピン酸52モル%、1,4−ブタンジオール100モル%からなる芳香族脂肪族ポリエステル(BASF社製、商品名「Ecoflex」)20重量%、脂肪族ポリエステルであるポリブチレンサクシネート/アジペート(昭和高分子社製、商品名「ビオノーレ#3003」)10重量%の各樹脂をそれぞれ乾燥させて用いた以外は実施例1と同様にして、熱収縮性フィルム状物を得た。
得られたフィルム状物について、実施例1と同様の評価を行った。その結果を表1に示す。
【0021】
(比較例1)
実施例1において、L−乳酸とD−乳酸との混合割合が95.0:5.0のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4050D」)を50重量%、L−乳酸とD−乳酸との混合割合が90.3:9.7のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4060D」)を50重量%の各樹脂をそれぞれ乾燥させて用いた以外は実施例1と同様にして、熱収縮性フィルム状物を得た。
得られたフィルム状物について、実施例1と同様の評価を行った。その結果を表1に示す。
【0022】
(比較例2)
実施例1において、L−乳酸とD−乳酸との混合割合が95.0:5.0のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4050D」)を35重量%、L−乳酸とD−乳酸との混合割合が90.3:9.7のポリ乳酸系重合体(カーギルダウポリマー社製、商品名「EcoPLA4060D」)を35重量%、脂肪族ポリエステルであるポリブチレンサクシネート/アジペート(昭和高分子社製、商品名「ビオノーレ#3003」)30重量%の各樹脂をそれぞれ乾燥させて用いた以外は実施例1と同様にしてフィルム状物を得た。得られたフィルム状物について、実施例1と同様の評価を行った。その結果を表1に示す。
【0023】
【表1】

Figure 0003664969
【0024】
表1から明らかなように、実施例1〜3は耐破断性および耐衝撃性ともに優れていることが分かった。すなわち、本発明によれば実質一軸延伸フィルム状物でも、瞬間的な衝撃に対して良好な結果が得られることが分かった。
一方、ポリ乳酸系重合体のみからなる比較例1のフィルム状物は耐破断性および耐衝撃性ともに低い値となり、ポリ乳酸系重合体と脂肪族ポリエステルとをブレンドした比較例2のフィルム状物は、引張試験等の低速での破断性は良好であったが瞬間的な衝撃に対しては弱いことが分かった。
なお、良好な耐衝撃性は、ハイドロショットでの打ち抜き後の破断フィルム状物が延伸方向に裂けないレベルであり、数値では10kgf・mm以上である。
【0025】
【発明の効果】
以上、詳しく説明したように、本発明によれば、生分解性があり、かつ耐破断性および耐衝撃性に優れた熱収縮性ポリ乳酸系重合体フィルム状物を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-shrinkable film-like material comprising a polylactic acid-based polymer as a main component, and particularly suitable for shrink-wrapping, shrink-bound packaging, shrink-labeling, etc. It relates to a united film.
[0002]
[Prior art and problems to be solved by the invention]
Heat-shrinkable films used for shrink wrap, shrink-bound wrap, shrink labels, etc. are known to mainly contain polyvinyl chloride (PVC), styrene-butadiene block copolymer (SBS), polyester resin, and the like. ing. Although these are widely used, when discarded after use, they are chemically stable and non-biodegradable, so they remain and accumulate almost without being decomposed. As a result, the capacity of the waste disposal site is saturated in a short period of time.
Therefore, biodegradable materials that have low combustion heat and are safe for the human body and the like have been demanded, and many studies have been conducted. As one of them, polylactic acid is known. Polylactic acid has a calorific value less than half that of polyethylene, and is naturally hydrolyzed in soil and water, and then becomes a harmless decomposition product by microorganisms. Japanese Patent Application Laid-Open No. 5-221790 discloses a heat-shrinkable film made of polylactic acid. However, since the shrinkage temperature is as high as 140 to 150 ° C., it can be used only for special purposes.
Originally, polylactic acid films and sheets are brittle and inferior in impact resistance due to the inherent brittleness of the material, and are therefore difficult to put into practical use. In particular, when a shrinkable film is formed by uniaxial stretching, the brittleness in the non-stretching direction is not improved. In order to improve this, a method of blending aliphatic polyester is known. According to such a method, although a good result is obtained in the breaking property (breaking resistance) at a low speed such as a tensile test, it is weak against an instantaneous impact (impact resistance) and is torn. There was a problem.
Therefore, there has been a demand for a heat-shrinkable polylactic acid-based film excellent in impact resistance in a substantially uniaxially stretched film mainly composed of polylactic acid.
[0003]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, the heat-shrinkable polylactic acid polymer film-like material of the present invention is a film obtained by stretching a film- like material composed of a polylactic acid-based polymer and an aromatic aliphatic polyester resin as main components in at least one direction. The heat-shrinkage rate after being immersed in warm water at 80 ° C. for 10 seconds is 10% or more in at least one direction, and the hydroshot value is 10 kgf · mm or more .
Here, the aromatic aliphatic polyester resin may include an aliphatic dicarboxylic acid component, an aromatic dicarboxylic acid component, and an aliphatic diol component.
The aromatic aliphatic polyester resin may contain an aromatic dicarboxylic acid component in a range of 50 mol% or less.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The heat-shrinkable polylactic acid-based polymer film-like product of the present invention comprises a resin composition containing a polylactic acid-based polymer and an aromatic aliphatic polyester resin as main components.
Here, the film-like material means a sheet or a film. According to the definition in JIS, a sheet is a thin, generally flat product whose thickness is small compared to the length and width, and a film is extremely small compared to the length and width and has a maximum thickness. An arbitrarily limited thin flat product, usually supplied in the form of a roll (JIS K 6900). Therefore, it can be said that a particularly thin sheet is a film. However, since the boundary between the sheet and the film is not clear and it is difficult to distinguish clearly, in the present application, as described above, the term “film-like product” is used as a concept including both the sheet and the film. use.
[0005]
The polylactic acid-based polymer used in the present invention includes poly (L-lactic acid) having a structural unit of L-lactic acid, poly (D-lactic acid) having a structural unit of D-lactic acid, a structural unit of L-lactic acid, and The main component is poly (DL-lactic acid) which is D-lactic acid or a mixture thereof. In the present invention, it may be a copolymer with other hydroxycarboxylic acid units described later, or may contain a small amount of a chain extender residue.
Examples of the other hydroxycarboxylic acid units copolymerized with polylactic acid include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3 2-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, etc. Examples thereof include lactones such as functional aliphatic hydroxycarboxylic acids, caprolactone, butyrolactone, and valerolactone.
[0006]
The polylactic acid is preferably D-lactic acid: L-lactic acid = 100: 0 to 85:15 or 0: 100 to 15:85. It is also possible to blend two or more types of polylactic acid having different constituent ratios of D-lactic acid and L-lactic acid.
A polylactic acid polymer containing only D-lactic acid or L-lactic acid is a crystalline resin, has a high melting point, and tends to be excellent in heat resistance and mechanical properties. However, when used as a heat-shrinkable film-like material, if the crystallinity is very high, stretching and orientation crystallization proceeds at the time of stretching, so that it is difficult to adjust the heat shrinkage rate. On the other hand, it is known that the crystallinity of DL-lactic acid decreases as the proportion of the optical isomer increases. Therefore, when used as a heat-shrinkable film-like product, it is preferable to moderately reduce the crystallinity.
[0007]
As a polymerization method for the polylactic acid polymer, known methods such as a condensation polymerization method and a ring-opening polymerization method can be employed. For example, in the condensation polymerization method, a polylactic acid polymer having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid, or a mixture thereof.
In addition, in the ring-opening polymerization method (lactide method), a lactate which is a cyclic dimer of lactic acid is obtained by using a suitable catalyst while using a polymerization regulator or the like as necessary. Can do. In addition, the lactide includes lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, and DL-lactide which is a dimer of D-lactic acid and L-lactic acid. Can be mixed and polymerized as necessary to obtain polylactic acid having an arbitrary composition and crystallinity.
[0008]
The polylactic acid polymer used in the present invention preferably has a weight average molecular weight of 60,000 to 700,000, more preferably 80,000 to 400,000, and particularly preferably 100,000 to 300,000. If the molecular weight is too small, practical physical properties such as mechanical properties and heat resistance are hardly expressed, and if it is too large, the melt viscosity is too high and the molding processability is poor.
[0009]
The aromatic aliphatic polyester preferably used in the present invention is a biodegradable aromatic polyester comprising an aliphatic dicarboxylic acid component, an aromatic dicarboxylic acid component, and an aliphatic diol component.
Aliphatic polyesters composed of aliphatic dicarboxylic acids and aliphatic diols are known to have biodegradability, but in order to develop biodegradability in aromatic polyesters, aliphatic chains are not between aromatic rings. It is necessary to exist. For this reason, the aromatic dicarboxylic acid component of the aromatic aliphatic polyester used in the present invention is preferably 50 mol% or less.
Examples of the aromatic dicarboxylic acid component include isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of the aliphatic dicarboxylic acid component include succinic acid, adipic acid, suberic acid, sebacic acid, Examples include dodecanedioic acid, and examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like. Two or more types of aromatic dicarboxylic acid components, aliphatic dicarboxylic acid components, or aliphatic diol components can be used.
In the present invention, the aromatic dicarboxylic acid component most preferably used is terephthalic acid, the aliphatic dicarboxylic acid component is adipic acid, and the aliphatic diol component is 1,4-butanediol.
[0010]
The mixing ratio of the polylactic acid polymer and the aromatic aliphatic polyester is not particularly limited, but in the case of a heat-shrinkable label used for PET bottles and bottle bottles, the aromatic aliphatic polyester is It is preferable that it is 50 weight% or less. If the mixing ratio of the aromatic aliphatic polyester exceeds 50% by weight, the film-like product becomes too soft and the shrinkage finish property tends to be lowered.
[0011]
In the present invention, other biodegradable resins, for example, aliphatic polyester, polycaprolactone, aliphatic polyester carbonate, etc. are blended within the range that does not impair the properties of the heat-shrinkable polylactic acid polymer film. Can do.
In addition, for the purpose of adjusting various physical properties, a heat stabilizer, a light stabilizer, a light absorber, a lubricant, a plasticizer, an inorganic filler, a colorant, a pigment, and the like can be added.
[0012]
The thickness of the film-like material is appropriately selected depending on the application, and is not particularly limited as long as it is a thickness that can be used for ordinary heat shrink wrapping or the like. Specifically, the total thickness is about 0.01 to 2. It is preferably in the range of 0 mm, more preferably in the range of about 0.01 to 1.5 mm.
[0013]
As a method for producing the film-like product of the present invention, a method in which a polylactic acid polymer and an aromatic aliphatic polyester are sufficiently dried to remove moisture, and then melt mixed using an extruder and extruded is generally used. However, it is not limited to these. For the extrusion, a known method such as a T-die casting method or a tubular method can be employed. However, it is necessary to appropriately set the temperature in consideration of a decrease in molecular weight due to decomposition.
The melt-extruded film-like material is brought into contact with a rotating casting drum (cooling drum) or cooled with air, water, etc., and then appropriately heated with hot air, hot water, infrared rays, microwaves, etc. By a roll method that stretches an object between two rolls with a difference in peripheral speed, a tenter method that stretches a row of clip rows while holding a film-like object with a clip using a tenter, a tubular method, etc. , Stretched in at least one direction.
[0014]
The stretching temperature and stretching ratio are appropriately determined depending on the mixing ratio of the polylactic acid polymer and the aromatic aliphatic polyester, the crystallinity of the polylactic acid polymer, etc., and the application to be applied. The temperature is controlled in the range of about 70 to 95 ° C., and the draw ratio is appropriately determined in the range of about 1.5 to 6 times with respect to the shrinking direction. Further, uniaxial stretching, biaxial stretching, and the like are also appropriately determined according to the application.
In addition, it is preferable that the film-like thing after extending | stretching is 10% or more in a heat shrink rate at least in one direction after being immersed in 80 degreeC warm water for 10 second.
[0015]
The heat-shrinkable polylactic acid polymer film-like product of the present invention can be used as a packaging material or a shrinkable label material. Examples of the objects to be packaged in which the packaging material and the shrinkage label are used include containers, foods such as fresh foods, and the like. Examples of the container include a container having high hardness such as a glass bottle, a glass container, and a hard plastic container, or a container formed from paper, plastic such as polystyrene, polyethylene, and polyethylene terephthalate. These containers are used for arbitrary uses such as foods, beverages, and medicines.
[0016]
【Example】
The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In addition, the measured value and evaluation in an Example were performed as follows. However, the take-up (flow) direction of the film-like material is described as MD, and its orthogonal direction is described as TD.
[0017]
Evaluation methods:
1) Cut the film with a heat shrinkage rate so that the MD is 100 mm and the TD is 100 mm, immerse in a hot water bath at 80 ° C. for 10 seconds, measure the dimension between the marked lines, The heat shrinkage rate was calculated according to However, the thermal shrinkage was measured by shrinkage in the TD direction.
Thermal shrinkage rate (%) = [{(dimension before shrinkage) − (dimension after shrinkage)} / (dimension before shrinkage)] × 100
2) Tensile elongation at break (breaking resistance)
In accordance with JIS K7127, a tensile test was performed, the elongation of the film-like material was measured, and substitute evaluation of the fracture resistance was performed. As test conditions, the elongation of the sheet in the MD direction of the film-like material at an atmospheric temperature of 23 ° C. at a tensile speed of 200 mm / min was measured. In addition, the test was performed 5 times and the average value was calculated | required. A film-like product having a small elongation has low fracture resistance, and a film having a large elongation has high fracture resistance.
3) Hydroshot (impact resistance)
Impact resistance was measured using a hydroshot high-speed impact tester HTM-1 type (manufactured by Shimadzu Corporation). A film-like material cut out to a size of 100 mm × 100 mm was fixed with a clamp, a weight was dropped on the center of the film-like material to give an impact, and the breaking energy when the film-like material was broken was read. However, the measurement temperature is 23 ° C. and the falling speed of the weight is 3 m / sec.
[0018]
(Example 1)
35% by weight of a polylactic acid polymer (trade name “EcoPLA4050D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of L-lactic acid and D-lactic acid of 95.0: 5.0, L-lactic acid and D-lactic acid Is a polylactic acid polymer (trade name “EcoPLA4060D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of 90.3: 9.7, 35 wt%, terephthalic acid 48 mol%, adipic acid 52 mol%, 1, Each resin of 30% by weight of aromatic aliphatic polyester (trade name “Ecoflex”, manufactured by BASF Corp.) consisting of 100 mol% of 4-butanediol was dried. Subsequently, these were mixed and mounted on a T-die extruder, melt extruded at a temperature of 210 ° C., and the melt was quenched with a casting roll at about 43 ° C. to obtain an unstretched film. Subsequently, the unstretched film-like material was roll-stretched 1.01 times at 65 ° C. in the longitudinal direction (MD), and then transversely stretched 4 times at 75 ° C. using a tenter in the width direction (TD). A 50 μm heat-shrinkable film was produced.
The obtained film-like product was evaluated for heat shrinkage, tensile elongation at break and hydroshot. The results are shown in Table 1.
[0019]
(Example 2)
In Example 1, 40% by weight of a polylactic acid polymer having a mixing ratio of L-lactic acid and D-lactic acid of 95.0: 5.0 (trade name “EcoPLA4050D” manufactured by Cargill Dow Polymer Co., Ltd.), L- 40% by weight of polylactic acid polymer (trade name “EcoPLA4060D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of lactic acid and D-lactic acid of 90.3: 9.7, terephthalic acid 43 mol%, adipic acid 57 Example 1 except that 20% by weight of each aliphatic aliphatic polyester (trade name “East Bond 14766”, manufactured by Eastman Chemical Co.) consisting of 100% by mole of 1,4-butanediol was used. A heat-shrinkable film was obtained.
About the obtained film-form thing, evaluation similar to Example 1 was performed. The results are shown in Table 1.
[0020]
(Example 3)
In Example 1, 35% by weight of a polylactic acid polymer having a mixing ratio of L-lactic acid and D-lactic acid of 95.0: 5.0 (trade name “EcoPLA4050D” manufactured by Cargill Dow Polymer Co., Ltd.), L- 35% by weight of polylactic acid polymer (trade name “EcoPLA4060D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of lactic acid and D-lactic acid of 90.3: 9.7, terephthalic acid 48 mol%, adipic acid 52 20% by weight of an aromatic aliphatic polyester (trade name “Ecoflex” manufactured by BASF Corporation) consisting of 100% by mole of 1,4-butanediol, polybutylene succinate / adipate which is an aliphatic polyester (Showa Polymer Co., Ltd.) Manufactured under the trade name “Bionore # 3003”) 10% by weight of each resin was used in the same manner as in Example 1 except that each resin was dried and used. To obtain things.
About the obtained film-form thing, evaluation similar to Example 1 was performed. The results are shown in Table 1.
[0021]
(Comparative Example 1)
In Example 1, 50% by weight of a polylactic acid polymer (trade name “EcoPLA4050D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of L-lactic acid and D-lactic acid of 95.0: 5.0, L- A polylactic acid polymer having a mixing ratio of lactic acid and D-lactic acid of 90.3: 9.7 (manufactured by Cargill Dow Polymer Co., Ltd., trade name “EcoPLA4060D”) was used by drying 50% by weight of each resin. Except for this, a heat-shrinkable film was obtained in the same manner as in Example 1.
About the obtained film-form thing, evaluation similar to Example 1 was performed. The results are shown in Table 1.
[0022]
(Comparative Example 2)
In Example 1, 35% by weight of a polylactic acid polymer having a mixing ratio of L-lactic acid and D-lactic acid of 95.0: 5.0 (trade name “EcoPLA4050D” manufactured by Cargill Dow Polymer Co., Ltd.), L- Polybutylene succinate which is 35% by weight of polylactic acid polymer (trade name “EcoPLA4060D” manufactured by Cargill Dow Polymer Co., Ltd.) having a mixing ratio of lactic acid and D-lactic acid of 90.3: 9.7, aliphatic polyester / Adipate (made by Showa Polymer Co., Ltd., trade name “Bionore # 3003”) A film-like product was obtained in the same manner as in Example 1 except that each resin was dried and used. About the obtained film-form thing, evaluation similar to Example 1 was performed. The results are shown in Table 1.
[0023]
[Table 1]
Figure 0003664969
[0024]
As is apparent from Table 1, Examples 1 to 3 were found to be excellent in both fracture resistance and impact resistance. That is, according to the present invention, it has been found that even a substantially uniaxially stretched film-like product can obtain a good result against an instantaneous impact.
On the other hand, the film-like product of Comparative Example 1 consisting only of a polylactic acid polymer has low values for both fracture resistance and impact resistance, and the film-like product of Comparative Example 2 blended with a polylactic acid polymer and an aliphatic polyester. It was found that the breaking property at a low speed such as a tensile test was good, but it was weak against an instantaneous impact.
In addition, good impact resistance is a level at which a ruptured film-like product after being punched by hydroshot does not tear in the stretching direction, and is numerically 10 kgf · mm or more.
[0025]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a heat-shrinkable polylactic acid-based polymer film that is biodegradable and excellent in fracture resistance and impact resistance.

Claims (3)

ポリ乳酸系重合体および芳香族脂肪族ポリエステル樹脂を主成分とする樹脂組成物からなるフィルム状物を少なくとも一方向に延伸したフィルム状物であって、80℃の温水中に10秒間浸漬した後の熱収縮率が少なくとも一方向において10%以上であり、かつ、ハイドロショット値が10kgf・mm以上であることを特徴とする熱収縮性ポリ乳酸系重合体フィルム状物。A film-like product made of a resin composition composed mainly of a polylactic acid-based polymer and an aromatic aliphatic polyester resin, which is stretched in at least one direction, and is immersed in warm water at 80 ° C. for 10 seconds. A heat-shrinkable polylactic acid polymer film-like product having a heat shrinkage ratio of 10% or more in at least one direction and a hydroshot value of 10 kgf · mm or more . 前記芳香族脂肪族ポリエステル樹脂が、脂肪族ジカルボン酸成分、芳香族ジカルボン酸成分および脂肪族ジオール成分からなることを特徴とする請求項1に記載の熱収縮性ポリ乳酸系重合体フィルム状物。  The heat-shrinkable polylactic acid-based polymer film according to claim 1, wherein the aromatic aliphatic polyester resin comprises an aliphatic dicarboxylic acid component, an aromatic dicarboxylic acid component, and an aliphatic diol component. 前記芳香族脂肪族ポリエステル樹脂が、芳香族ジカルボン酸成分を50モル%以下の範囲で含有することを特徴とする請求項1または2のいずれか一項に記載の熱収縮性ポリ乳酸系重合体フィルム状物。  The heat-shrinkable polylactic acid-based polymer according to claim 1, wherein the aromatic aliphatic polyester resin contains an aromatic dicarboxylic acid component in a range of 50 mol% or less. Film-like product.
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