JP3683321B2 - Resin composition - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、エチレン−ビニルアルコール系共重合体（以下、ＥＶＯＨと略記する）樹脂組成物に関し、更に詳しくは、透明性、ガスバリヤー性（耐酸素透過性、耐二酸化炭素透過性）がともに優れたＥＶＯＨ樹脂組成物に関するものである。
【０００２】
【従来の技術】
一般に、ＥＶＯＨはフィルム成形された時の透明性、ガスバリヤー性、保香性、耐溶剤性、耐油性等に優れた樹脂であり、この特徴を生かし種々の分野に利用されている。特に、透明性の点については、その向上を目的として種々検討されており、例えば、ＥＶＯＨの製膜過程で急冷する操作を行ったり、又ケン化度の低いＥＶＯＨを用いたりする等の方法がある。
一方、ＥＶＯＨの耐衝撃性を改善させる目的では、特開昭５７−３４１４８号公報、特開昭５７−５９９４０号公報等には、ＥＶＯＨにアルコール系可塑剤及びホウ酸又はホウ酸塩を含有せしめることが提案されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、透明性とガスバリヤー性の両方を満足することは難しく、ＥＶＯＨフィルムの透明性を上げるためには前述のように製膜過程で急冷する操作が必要となるが、かかる急冷操作により結晶化度が低下し、それに伴ってガスバリヤー性も低下することになる。又、ケン化度の低いＥＶＯＨを用いた場合もガスバリヤー性が低下することになってしまう。
【０００４】
又、特開昭５７−３４１４８号公報及び特開昭５７−５９９４０号公報開示技術では、耐衝撃性について検討されているものの、透明性、ガスバリヤー性については何ら考慮されておらず、本発明者等が詳細に検討した結果、透明性及びガスバリヤー性の両方がともに優れたものは得難く、最近の技術の高度化に伴い更なる改良が望まれる。
本発明は、このような背景下において、上記課題を解決した樹脂組成物、即ち透明性及びガスバリヤー性がともに優れ、更には一般的な酸素に対するガスバリヤー性だけでなく二酸化炭素に対するガスバリヤー性にも優れた樹脂組成物を提供することを目的とする。
【０００５】
【問題を解決するための手段】
しかるに、本発明者等は、かかる問題を解決すべく鋭意研究を重ねた結果、エチレン含有量２０〜６０モル％のＥＶＯＨ（Ａ）の溶剤含有率を０．１〜７０重量％とした状態で、ホウ酸、硫酸銅から選ばれる少なくとも一種の化合物を反応させてなり、かつ、ＨＣＴ（Half Crystallization Time）が２３０秒以上である樹脂組成物が、かかる課題を解決することを見出し本発明を完成した。
但し、ＨＣＴとは、エチレン−ビニルアルコール系共重合体（Ａ）の融点より１２℃低い温度で示差走査熱量計によって求められるピーク面積を２等分する時間（秒）であり、示差走査熱量計での測定に当たっては、まず組成物を１０℃／ｍｉｎで２３０℃まで昇温し、５分間ホールドした後、ＥＶＯＨ（Ａ）の融点より１２℃低い温度まで８０℃／ｍｉｎで冷却し、該温度でホールドして行う。
【０００６】
更に詳しく図１を用いて説明すれば、図１は本発明の樹脂組成物の一典型例の等温結晶化曲線（縦軸；熱流量（ｍＷ）、横軸；時間（秒））であり（これに限られることはない）、ＨＣＴは、該結晶化曲線のピークの下がり始めの点をａ、ピークの終点をｂとし、直線ａ−ｂと該ピーク（曲線ａ〜ｂ）で囲まれる面積をＳとした場合に、面積Ｓを半分に区切るように縦軸を引いたときの横軸と交わる時間ｃ（秒）のことである。
【０００７】
又、本発明においては、上記樹脂組成物に更に、融点の差が１５℃以内であるＥＶＯＨ（Ｂ）を配合することで、更に酸素や二酸化炭素のガスバリヤー性の優れた樹脂組成物が得られる。
【０００８】
【発明の実施の形態】
以下に、本発明を詳細に述べる。
本発明のＥＶＯＨ（Ａ）としては、エチレン含有量２０〜６０モル％、好ましくは２３〜５８モル％、更に好ましくは２５〜５５モル％であれば特に制限されることはない。エチレン含有量が２０モル％未満では溶融成形性が悪く、又、６０モル％を越えるとガスバリヤー性が低下する傾向がある。ケン化度については特に制限されないが、７０〜１００モル％、好ましくは８０〜１００モル％が好ましい。又、メルトインデックス（２１０℃、荷重２１６０ｇ）については０．１〜８０ｇ／１０分、好ましくは１〜７０ｇ／１０分である。
【０００９】
又、かかるＥＶＯＨ（Ａ）に反応させる化合物は、ホウ酸、硫酸銅から選ばれる少なくとも一種の化合物である。
【００１０】
本発明では、上記の如くＥＶＯＨ（Ａ）に、ホウ酸、硫酸銅から選ばれる少なくとも一種の化合物を反応させるわけであるが、更に、ＨＣＴが２３０秒以上、好ましくは２３５〜９００秒、更に好ましくは２４０〜６００秒であることが必要で、かかる点に本発明の最大の特徴があるのである。該ＨＣＴが２３０秒未満では、十分なガスバリヤー性と透明性を併せ持つフィルムが得られず好ましくない。
【００１１】
本発明で該ＨＣＴが２３０秒以上の樹脂組成物を得る方法としては、以下の方法が採用される。
即ち、ＥＶＯＨ（Ａ）の溶剤含有率を０．１〜７０重量％、好ましくは０．３〜６５重量％、より好ましくは０．５〜６０重量％とした状態でホウ酸、硫酸銅から選ばれる少なくとも一種の化合物を反応させることである。かかる溶剤含有率が０．１重量％未満では反応が不十分で、かつ不均一となり、本発明の効果が顕著に発揮されず、一方７０重量％を越えると樹脂の乾燥工程に長時間を要することとなり経済的でなくなる。
【００１２】
該ＥＶＯＨ（Ａ）の溶剤含有率を上記範囲にコントロールする方法としては、特に制限されず、例えば、ＥＶＯＨのペレットを水、アルコール等の溶剤に浸漬し、その浸漬時間によりコントロールしたり、乾燥工程によりコントロールしたりする等の方法がある。
【００１３】
かかるＥＶＯＨ（Ａ）の溶剤含有率を０．１〜７０重量％とした状態でホウ酸、硫酸銅から選ばれる少なくとも一種の化合物を反応させる方法としては、例えば該化合物を水、アルコール等の溶媒に溶解し、溶剤含有量を０．１〜７０重量％としたＥＶＯＨ（Ａ）に混合したり、該化合物の溶液に、溶剤含有量を０．１〜７０重量％としたＥＶＯＨ（Ａ）を浸漬したり、溶剤含有量を０．１〜７０重量％としたＥＶＯＨ（Ａ）と該化合物とを押出機内で反応させたりする等の方法があるが、これに限定されるものではない。
【００１４】
ＥＶＯＨ（Ａ）に反応させるホウ酸、硫酸銅から選ばれる少なくとも一種の化合物の量としては、ＥＶＯＨ（Ａ）に対して１〜１００００ｐｐｍ、好ましくは５〜９０００ｐｐｍ、更に好ましくは１０〜８０００ｐｐｍである。かかる量が１ｐｐｍ未満では透明性が好ましくなく、又、１００００ｐｐｍを越えると樹脂の溶融粘度が高くなり過ぎ製膜性に劣るため好ましくない。
【００１５】
かくして得られる樹脂組成物（Ｃ）は、透明性及びガスバリヤー性がともに優れたフィルム又はシート等を得ることができる組成物であり、該樹脂組成物（Ｃ）のみでも本発明の目的を充分満足するものであるが、本発明においては、上記樹脂組成物（Ｃ）に更に、（Ａ）の融点との差が１５℃以内であるＥＶＯＨ（Ｂ）を配合することで、更にガスバリヤー性の優れた樹脂組成物が得られる。
【００１６】
該ＥＶＯＨ（Ｂ）は、ＥＶＯＨ（Ａ）との融点の差が１５℃以内であれば特に限定されないが、なかでもエチレン含有量が２０〜６０モル％、好ましくは２５〜５５モル％、ケン化度が７０〜１００モル％、好ましくは８０〜１００モル％、メルトインデックス（２１０℃、荷重２１６０ｇ）が０．１〜８０ｇ／１０分、好ましくは０．５〜７０ｇ／１０分が用いられる。
【００１７】
樹脂組成物（Ｃ）とＥＶＯＨ（Ｂ）の配合割合は１／９９〜７５／２５、好ましくは５／９５〜６５／３５、更に好ましくは１０／９０〜５０／５０である。該配合割合が１／９９未満ではＥＶＯＨ（Ｂ）の結晶化が支配的となり透明性が低下し、７５／２５を越えるとバリヤー性の向上が見られず、本発明の効果を顕著に発揮しない。
【００１８】
配合方法としては、特に限定されず、ＥＶＯＨ（Ｂ）及び樹脂組成物（Ｃ）を水−アルコール溶媒に溶解して混合する方法、ＥＶＯＨ（Ｂ）又は樹脂組成物（Ｃ）を水−アルコール溶媒に溶解して他方と混合する方法、あるいはＥＶＯＨ（Ｂ）、樹脂組成物（Ｃ）を溶融混合する方法等が挙げられるが、通常は溶融混合する方法が採用される。例えば、ＥＶＯＨ（Ｂ）及び樹脂組成物（Ｃ）をドライブレンドした後に溶融してブレンドする方法、ＥＶＯＨ（Ｂ）及び樹脂組成物（Ｃ）を溶融状態でブレンドする方法、あるいはＥＶＯＨ（Ｂ）又は樹脂組成物（Ｃ）を溶融状態にした後他方を乾燥状態で添加する方法等が挙げられる。なかでもＥＶＯＨ（Ｂ）及び樹脂組成物（Ｃ）をドライブレンドした後に溶融してブレンドする方法が装置の簡便さ、ブレンド物のコスト面等で実用的である。
【００１９】
更に、本発明では必要に応じて、可塑剤、熱安定剤、紫外線吸収剤、酸化防止剤、着色剤、帯電防止剤、滑剤、充填剤、フィラー、他樹脂等の添加剤を使用することも可能である。特に、ゲル発生防止剤として、ハイドロタルサイト系化合物、ヒンダードフェノール系、ヒンダードアミン系熱安定剤、高級脂肪族カルボン酸の金属塩を添加することもできる。
【００２０】
かくして本発明の樹脂組成物（樹脂組成物（Ｃ）あるいは樹脂組成物（Ｃ）及びＥＶＯＨ（Ｂ）のブレンド物）は成形物の用途に多用され、溶融混練によりペレット、フィルム、シート、容器、繊維、棒、管、等各種成形品に成形される。これらの粉砕品（回収品を再利用する時など）やペレットを用いて再び溶融成形することも多い。
【００２１】
溶融成形方法としては、押出成形法、例えばＴ−ダイ押出法、インフレーション押出法、ブロー成形法、溶融紡糸法、異型押出法等や、射出成形法が主として採用される。なかでも、本発明の樹脂組成物を製膜するに際してはＴ−ダイ押出法、インフレーション押出法が好適に用いられる。
【００２２】
特に、本発明においてはＴ−ダイ押出法により製膜する場合、押出成形機の冷却ロール温度を樹脂組成物のガラス転位温度（Ｔｇ）〜融点（Ｔｍ）の間に制御することが好ましい。
又、インフレーション押出法により製膜する場合は、空冷インフレーション方法を用いることができる。即ち、通常透明性を上げるためには水冷インフレーション方法が用いられるが、これではガスバリヤー性が低下してしまうのに対して、本発明の樹脂組成物では急冷操作を必要としない空冷インフレーション方法を用いてもガスバリヤー性を低下させることなく透明性の優れたフィルムが得られるので好ましい。
【００２３】
かくして上記方法により得られたフィルム等は、透明性、ガスバリヤー性がともに優れており、食品包装材料等の用途に大いに有効で、特に、透明性、二酸化炭素に対するガスバリヤー性も良好であることから植物の光合成が促進されるため、これを考慮すると農業用フィルムとしても非常に有用である。
【００２４】
【実施例】
以下、実施例を挙げて本発明を具体的に説明する。
尚、実施例中「部」、「％」とあるのは特に断りのない限り重量基準を示す。
実施例１
樹脂組成物（Ｃ）の製造
エチレン含有量３８モル％、ケン化度９９．５モル％、メルトインデックス（ＭＩ）２５ｇ／１０分（２１０℃、荷重２１６０ｇ）のＥＶＯＨ（Ａ）のパウダーを８０℃の水に浸漬することにより溶剤含有率を４０％にした状態で、１％のホウ酸水溶液中に投入し、８０℃で１２時間撹拌した（ＥＶＯＨ（Ａ）に対してホウ酸１５００ｐｐｍ含有）。その後、２０℃の純水で洗浄し、１２０℃で８時間乾燥を行い、本発明の樹脂組成物（Ｃ）を得た。
かかる樹脂組成物（Ｃ）のＨＣＴは４８０秒であった。尚、ＨＣＴはＥＶＯＨ（Ａ）の融点より１２℃低い温度、即ち１６１℃で示差走査熱量計（パーキネルマー製ＤＳＣ７）を用いて測定を行った。
【００２５】
該樹脂組成物（Ｃ）をＴ−ダイを備えた単軸押出機に供給し、下記の如き製膜条件でＴ−ダイ押出法により、厚さ３０μフィルムを作製した。
得られたフィルムについて、透明性、ガスバリヤー性（酸素透過度、二酸化炭素透過度）を下記の如く評価した。
（透明性）
村上色彩技術研究所製の反射透過率計 ＲＭ−１５Ａを用いて、フィルムのヘイズ値を測定した。
【００２７】
（ガスバリヤー性）
・酸素透過度
フィルムの酸素透過度を、ＭＯＤＥＲＮ−ＣＯＮＴＯＲＯＬ社のＯＸ−ＴＲＡＮ１０−５０を用いて２０℃、６５％ＲＨの条件下で測定した（ｃｃ・２０μｍ／ｍ2・ｄａｙ・ＭＰａ）。
・二酸化炭素透過度
フィルムの二酸化炭素透過度を柳本ガス透過測定装置（柳本製作所（株）製：ＧＴＲ−３０ＸＮ）を用いて２０℃、０％ＲＨの条件下で測定した（ｃｃ・２０μｍ／ｍ2・ｄａｙ・ＭＰａ）。尚、測定条件は下記の通りである。
カラム：６０／８０メッシュ 活性炭素充填 長さ１５０ｃｍ
カラム温度：８０℃
インレット温度：１５０℃
キャリアガス：ヘリウム
【００２８】
実施例２〜６、比較例１〜４
表１に示すＥＶＯＨ（Ａ）、及び添加剤を用いて実施例１に準じて樹脂組成物（Ｃ）を得た（ＨＣＴは表１に示される通りである）。該樹脂組成物（Ｃ）について、実施例１に準じてフィルムを作製し、各物性を実施例１と同様に評価した。尚、実施例６及び比較例４については、冷却ロール温度を２０℃にして冷却速度を高めて製膜した。
【００２９】
実施例７
実施例１の樹脂組成物（Ｃ）を用いて下記の如き製膜条件でインフレーション製膜を行った。
【００３０】
実施例８
実施例２の樹脂組成物を用いて、実施例７に準じてフィルムを作製し、各物性を実施例１と同様に評価した。
【００３１】
実施例９
実施例３の樹脂組成物を用いて、実施例７に準じてフィルムを作製し、各物性を実施例１と同様に評価した。
【００３２】
比較例５
比較例２の樹脂組成物を用いて、実施例７に準じてフィルムを作製し、各物性を実施例１と同様に評価した。
【００３３】
比較例６
比較例３の樹脂組成物を用いて、実施例７に準じてフィルムを作製し、各物性を実施例１と同様に評価した。
実施例１〜９、比較例１〜５のそれぞれの評価結果を表２に示す。
【００３４】
【表１】
注）Ｅｔ：エチレン含有量（モル％）
Ｓｖ：ケン化度（モル％）
ＭＩ：メルトインデックス（ｇ／１０分）（２１０℃、荷重２１６０ｇ）
添加剤の含有量は原子吸光法により求めた。
【００３６】
【表２】
尚、実施例７、８、９はそれぞれ実施例１、２、３の樹脂組成物を、又、比較例５、６はそれぞれ比較例２、３の樹脂組成物を用いた。
【００３８】
実施例１０
実施例１の樹脂組成物（Ｃ）とエチレン含有量３２モル％、ケン化度９９．５モル％、ＭＩ３ｇ／１０分（２１０℃、荷重２１６０ｇ）のＥＶＯＨ（Ｂ）（ＥＶＯＨ（Ａ）との融点の差は１０℃）とを混合し、二軸押出機に供給しペレットを作製した後、実施例１に準じてＴ−ダイ押出法にてフィルムを作製した。樹脂組成物（Ｃ）とＥＶＯＨ（Ｂ）の配合割合は２５／７５である。
得られたフィルムについて、実施例１と同様に透明性、ガスバリヤー性を評価した。
【００３９】
実施例１１〜１４
表３の如き樹脂組成物（Ｃ）及びＥＶＯＨ（Ｂ）を用いて、実施例１０に準じて混合物を得た。該混合物について、実施例１０に準じてフィルムを作製し、各物性を実施例１と同様に評価した。
実施例１０〜１４の結果を表４に示す。
【００４０】
【表３】
【表４】
【発明の効果】
本発明の樹脂組成物は、ＥＶＯＨ（Ａ）の溶剤含有率を０．１〜７０重量％とした状態で、ホウ酸、硫酸銅から選ばれる少なくとも一種の化合物から選ばれる少なくとも一種の化合物を反応させてなり、かつ、示差走査熱量計で測定される特定のＨＣＴを示すものであるため、透明性及びガスバリヤー性の両方がともに優れ、更に融点が１５℃以内のＥＶＯＨ（Ｂ）を配合することで、特にガスバリヤー性が向上するものであり、包装材料等の用途や農業用フィルム用途として非常に有用である。又、本発明の樹脂組成物は製膜時に急冷する必要がなく、製膜性にも優れたものである。
【図面の簡単な説明】
【図１】本発明の樹脂組成物における差動走査熱量計により測定される等温結晶化曲線
【符号の説明】
ａ：等温結晶化曲線のピークの下がり始めの点
ｂ：等温結晶化曲線のピークの終点
Ｓ：直線ａ−ｂと該ピーク（曲線ａ〜ｂ）で囲まれる面積
ｃ：面積Ｓを半分に区切るように縦軸を引いたときの横軸と交わる点[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) resin composition, and more specifically, it has excellent transparency and gas barrier properties (oxygen permeation resistance, carbon dioxide permeation resistance). The present invention relates to an EVOH resin composition.
[0002]
[Prior art]
In general, EVOH is a resin excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance and the like when film-formed, and is utilized in various fields by taking advantage of this feature. In particular, the transparency has been variously studied for the purpose of improving it. For example, a method of performing rapid cooling in the EVOH film-forming process or using EVOH having a low saponification degree is used. is there.
On the other hand, for the purpose of improving the impact resistance of EVOH, JP-A-57-34148, JP-A-57-59940, etc. include an alcohol plasticizer and boric acid or borate in EVOH. It has been proposed.
[0003]
[Problems to be solved by the invention]
However, it is difficult to satisfy both transparency and gas barrier properties, and in order to increase the transparency of the EVOH film, it is necessary to perform a quenching operation in the film forming process as described above. As a result, the gas barrier properties are also lowered. Further, when EVOH having a low saponification degree is used, the gas barrier property is also lowered.
[0004]
Further, in the techniques disclosed in Japanese Patent Application Laid-Open Nos. 57-34148 and 57-59940, although impact resistance has been studied, transparency and gas barrier properties are not considered at all, and the present invention As a result of detailed examinations by those skilled in the art, it is difficult to obtain a material that is excellent in both transparency and gas barrier property, and further improvement is desired with the recent advancement of technology.
Under such circumstances, the present invention is a resin composition that solves the above-mentioned problems, that is, it has both excellent transparency and gas barrier properties. Furthermore, it has not only general gas barrier properties against oxygen but also gas barrier properties against carbon dioxide. Another object of the present invention is to provide an excellent resin composition.
[0005]
[Means for solving problems]
However, as a result of intensive studies to solve such problems, the present inventors have made the solvent content of EVOH (A) having an ethylene content of 20 to 60 mol% 0.1 to 70 wt%. , boric acid, it is reacted with at least one compound selected from copper sulfate, and, HCT (Half Crystal l ization Time ) is a resin composition is at least 230 seconds, the present invention found that the solution to such problems Was completed.
However, HCT is a time (second) for dividing the peak area obtained by the differential scanning calorimeter into two equal parts at a temperature 12 ° C. lower than the melting point of the ethylene-vinyl alcohol copolymer (A). In the measurement, the composition was first heated to 230 ° C. at 10 ° C./min, held for 5 minutes, and then cooled to 80 ° C./min to a temperature 12 ° C. lower than the melting point of EVOH (A). Hold with.
[0006]
More specifically, FIG. 1 is an isothermal crystallization curve (vertical axis: heat flow rate (mW) , horizontal axis: time (seconds)) of a typical example of the resin composition of the present invention ( HCT is an area surrounded by the straight line ab and the peak (curves a and b), where a is the point at which the peak of the crystallization curve begins to fall and b is the end point of the peak. Is the time c (seconds) that intersects the horizontal axis when the vertical axis is drawn so as to divide the area S in half.
[0007]
Further , in the present invention, a resin composition having further excellent gas barrier properties of oxygen and carbon dioxide can be obtained by further blending EVOH (B) having a melting point difference of 15 ° C. or less with the above resin composition. It is done.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The EVOH (A) of the present invention is not particularly limited as long as it has an ethylene content of 20 to 60 mol%, preferably 23 to 58 mol%, more preferably 25 to 55 mol%. If the ethylene content is less than 20 mol%, the melt moldability is poor, and if it exceeds 60 mol%, the gas barrier property tends to decrease. The degree of saponification is not particularly limited, but is preferably 70 to 100 mol%, preferably 80 to 100 mol%. The melt index (210 ° C., load 2160 g) is 0.1 to 80 g / 10 minutes, preferably 1 to 70 g / 10 minutes.
[0009]
Further, compounds to be reacted with such EVOH (A) is boric acid, Ru least one compound der selected from copper sulfate.
[0010]
In the present invention, EVOH (A) is reacted with at least one compound selected from boric acid and copper sulfate as described above, and the HCT is 230 seconds or more, preferably 235 to 900 seconds, more preferably Needs to be 240 to 600 seconds, and this is the greatest feature of the present invention. If the HCT is less than 230 seconds, a film having sufficient gas barrier properties and transparency cannot be obtained, which is not preferable.
[0011]
As a method for obtaining a resin composition having an HCT of 230 seconds or more in the present invention, the following method is employed.
That is, the solvent content of EVOH (A) is selected from boric acid and copper sulfate in a state of 0.1 to 70% by weight, preferably 0.3 to 65% by weight, more preferably 0.5 to 60% by weight. Reaction of at least one compound. If the solvent content is less than 0.1% by weight, the reaction is insufficient and non-uniform, and the effects of the present invention are not remarkably exhibited. On the other hand, if it exceeds 70% by weight, the resin drying process takes a long time. It becomes uneconomical.
[0012]
The method for controlling the solvent content of EVOH (A) to the above range is not particularly limited. For example, EVOH pellets are immersed in a solvent such as water or alcohol and controlled by the immersion time, or the drying step. There is a method of controlling by.
[0013]
As a method for reacting at least one compound selected from boric acid and copper sulfate in a state where the solvent content of EVOH (A) is 0.1 to 70% by weight, for example, the compound is a solvent such as water or alcohol. Or mixed with EVOH (A) having a solvent content of 0.1 to 70% by weight, or EVOH (A) having a solvent content of 0.1 to 70% by weight in a solution of the compound. Although there are methods such as immersion or EVOH (A) having a solvent content of 0.1 to 70% by weight and the compound reacted in an extruder, the method is not limited thereto.
[0014]
The amount of at least one compound selected from boric acid and copper sulfate to be reacted with EVOH (A) is 1 to 10,000 ppm, preferably 5 to 9000 ppm, more preferably 10 to 8000 ppm with respect to EVOH (A). If the amount is less than 1 ppm, the transparency is not preferable, and if it exceeds 10,000 ppm, the melt viscosity of the resin becomes too high and the film-forming property is inferior.
[0015]
The resin composition (C) thus obtained is a composition capable of obtaining a film or sheet having both excellent transparency and gas barrier properties, and the object of the present invention is sufficient even with the resin composition (C) alone. Although satisfactory, in the present invention, the resin composition (C) is further blended with EVOH (B) having a difference from the melting point of (A) within 15 ° C. to further improve gas barrier properties. Excellent resin composition can be obtained.
[0016]
The EVOH (B) is not particularly limited as long as the difference in melting point from the EVOH (A) is within 15 ° C. Among them, the ethylene content is 20 to 60 mol%, preferably 25 to 55 mol%. The degree is 70 to 100 mol%, preferably 80 to 100 mol%, and the melt index (210 ° C., load 2160 g) is 0.1 to 80 g / 10 min, preferably 0.5 to 70 g / 10 min.
[0017]
The blending ratio of the resin composition (C) and EVOH (B) is from 1/99 to 75/25, preferably from 5/95 to 65/35, and more preferably from 10/90 to 50/50. When the blending ratio is less than 1/99, the crystallization of EVOH (B) is dominant and the transparency is lowered, and when it exceeds 75/25, the improvement of the barrier property is not seen and the effect of the present invention is not exhibited remarkably. .
[0018]
The blending method is not particularly limited, and a method in which EVOH (B) and the resin composition (C) are dissolved and mixed in a water-alcohol solvent. The method of melt | dissolving in 1 and mixing with the other, or the method of melt-mixing EVOH (B) and the resin composition (C) etc. are mentioned, Usually, the method of melt-mixing is employ | adopted. For example, EVOH (B) and the resin composition (C) are dry blended and then melted and blended, EVOH (B) and the resin composition (C) are blended in a molten state, or EVOH (B) or Examples thereof include a method in which the resin composition (C) is melted and the other is added in a dry state. Among them, a method of melt-blending EVOH (B) and the resin composition (C) after dry blending is practical in terms of simplicity of equipment, cost of the blended product, and the like.
[0019]
Furthermore, in the present invention, additives such as plasticizers, heat stabilizers, ultraviolet absorbers, antioxidants, colorants, antistatic agents, lubricants, fillers, fillers, and other resins may be used as necessary. Is possible. In particular, hydrotalcite compounds, hindered phenols, hindered amine heat stabilizers, and metal salts of higher aliphatic carboxylic acids can be added as gel generation inhibitors.
[0020]
Thus, the resin composition (resin composition (C) or a blend of the resin composition (C) and EVOH (B)) of the present invention is frequently used for molded products, and is formed into pellets, films, sheets, containers, Molded into various molded products such as fibers, rods, tubes, etc. In many cases, these pulverized products (such as when the collected products are reused) and pellets are melt-molded again.
[0021]
As the melt molding method, an extrusion molding method such as a T-die extrusion method, an inflation extrusion method, a blow molding method, a melt spinning method, a profile extrusion method, or an injection molding method is mainly employed. Especially, when forming the resin composition of this invention into a film, the T-die extrusion method and the inflation extrusion method are used suitably.
[0022]
In particular, in the present invention, when a film is formed by the T-die extrusion method, it is preferable to control the cooling roll temperature of the extruder between the glass transition temperature (Tg) to the melting point (Tm) of the resin composition.
Moreover, when forming into a film by the inflation extrusion method, the air cooling inflation method can be used. That is, a water-cooled inflation method is usually used to increase transparency, but this reduces gas barrier properties, whereas the resin composition of the present invention uses an air-cooled inflation method that does not require a rapid cooling operation. Even if it is used, it is preferable because a film having excellent transparency can be obtained without deteriorating the gas barrier property.
[0023]
Thus, the film obtained by the above method is excellent in both transparency and gas barrier properties, and is very effective for food packaging materials and the like, and particularly has good transparency and gas barrier properties against carbon dioxide. Therefore, it is very useful as an agricultural film.
[0024]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
In the examples, “parts” and “%” are based on weight unless otherwise specified.
Example 1
Production of resin composition (C) EVOH (A) having an ethylene content of 38 mol%, a saponification degree of 99.5 mol%, a melt index (MI) of 25 g / 10 min (210C, load of 2160 g) The powder was immersed in water at 80 ° C. to give a solvent content of 40%, and then poured into a 1% boric acid aqueous solution and stirred at 80 ° C. for 12 hours (boric acid with respect to EVOH (A)). 1500ppm contained). Then, it wash | cleaned with 20 degreeC pure water, and it dried at 120 degreeC for 8 hours, and obtained the resin composition (C) of this invention.
The HCT of the resin composition (C) was 480 seconds. HCT was measured using a differential scanning calorimeter (DSC7 manufactured by Perkinelmer) at a temperature 12 ° C. lower than the melting point of EVOH (A), that is, 161 ° C.
[0025]
The resin composition (C) was supplied to a single screw extruder equipped with a T-die, and a 30 μm-thick film was produced by the T-die extrusion method under the following film forming conditions.
The obtained film was evaluated for transparency and gas barrier properties (oxygen permeability, carbon dioxide permeability) as follows.
(transparency)
The haze value of the film was measured using a reflection transmittance meter RM-15A manufactured by Murakami Color Research Laboratory.
[0027]
(Gas barrier properties)
Oxygen permeability The oxygen permeability of the film was measured under the conditions of 20 ° C. and 65% RH (cc · 20 μm / m 2 · day · MPa) using OX-TRAN10-50 manufactured by MODERN-CONTROL.
Carbon dioxide permeability The carbon dioxide permeability of the carbon dioxide film was measured under the conditions of 20 ° C. and 0% RH using a Yanagimoto gas permeation measuring device (manufactured by Yanagimoto Seisakusho Co., Ltd .: GTR-30XN) (cc · 20 μm / m 2 · day · MPa). Measurement conditions are as follows.
Column: 60/80 mesh Activated carbon packing Length 150cm
Column temperature: 80 ° C
Inlet temperature: 150 ° C
Carrier gas: helium [0028]
Examples 2-6, Comparative Examples 1-4
Resin composition (C) was obtained according to Example 1 using EVOH (A) and additives shown in Table 1 (HCT is as shown in Table 1). About this resin composition (C), the film was produced according to Example 1, and each physical property was evaluated similarly to Example 1. FIG. In addition, about Example 6 and the comparative example 4, the cooling roll temperature was 20 degreeC and the cooling rate was raised, and it formed into a film.
[0029]
Example 7
Inflation film formation was performed using the resin composition (C) of Example 1 under the following film formation conditions.
[0030]
Example 8
Using the resin composition of Example 2, a film was produced according to Example 7, and each physical property was evaluated in the same manner as Example 1.
[0031]
Example 9
Using the resin composition of Example 3, a film was produced according to Example 7, and each physical property was evaluated in the same manner as Example 1.
[0032]
Comparative Example 5
Using the resin composition of Comparative Example 2, a film was produced according to Example 7, and each physical property was evaluated in the same manner as Example 1.
[0033]
Comparative Example 6
A film was produced in accordance with Example 7 using the resin composition of Comparative Example 3, and each physical property was evaluated in the same manner as in Example 1.
The evaluation results of Examples 1 to 9 and Comparative Examples 1 to 5 are shown in Table 2.
[0034]
[Table 1]
Note) Et: ethylene content (mol%)
Sv: degree of saponification (mol%)
MI: Melt index (g / 10 min) (210 ° C., load 2160 g)
The content of the additive was determined by an atomic absorption method.
[0036]
[Table 2]
Examples 7, 8, and 9 used the resin compositions of Examples 1, 2, and 3, respectively, and Comparative Examples 5 and 6 used the resin compositions of Comparative Examples 2 and 3, respectively.
[0038]
Example 10
Example 1 Resin composition (C) with EVOH (B) (EVOH (A)) having an ethylene content of 32 mol%, a saponification degree of 99.5 mol%, MI of 3 g / 10 min (210 ° C., load of 2160 g) The difference in melting point was 10 ° C.) and the mixture was supplied to a twin-screw extruder to produce pellets, and then a film was produced by a T-die extrusion method according to Example 1. The compounding ratio of the resin composition (C) and EVOH (B) is 25/75.
The resulting film was evaluated for transparency and gas barrier properties in the same manner as in Example 1.
[0039]
Examples 11-14
A mixture was obtained according to Example 10 using the resin composition (C) and EVOH (B) as shown in Table 3. About this mixture, the film was produced according to Example 10, and each physical property was evaluated similarly to Example 1. FIG.
The results of Examples 10-14 are shown in Table 4.
[0040]
[Table 3]
[Table 4]
【The invention's effect】
The resin composition of the present invention reacts with at least one compound selected from boric acid and at least one compound selected from copper sulfate in a state where the solvent content of EVOH (A) is 0.1 to 70% by weight. In addition, since it shows a specific HCT measured by a differential scanning calorimeter, both transparency and gas barrier properties are excellent, and EVOH (B) having a melting point within 15 ° C. is blended. In particular, the gas barrier property is improved, and it is very useful for applications such as packaging materials and agricultural films. Further, the resin composition of the present invention does not need to be rapidly cooled during film formation, and has excellent film forming properties.
[Brief description of the drawings]
1 is an isothermal crystallization curve measured by a differential scanning calorimeter in a resin composition of the present invention.
a: point at which the peak of the isothermal crystallization curve begins to fall b: end point of the peak of the isothermal crystallization curve S: area surrounded by the straight line ab and the peak (curves a and b) c: the area S is divided in half The point that intersects the horizontal axis when the vertical axis is drawn
Claims (2)
但し、ＨＣＴとは、エチレン−ビニルアルコール系共重合体（Ａ）の融点より１２℃低い温度で示差走査熱量計によって求められるピーク面積を２等分する時間（秒）である。At least one compound selected from boric acid and copper sulfate in a state where the solvent content of the ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% is 0.1 to 70% by weight. reacted becomes in and, HCT (Half Crystal l ization Time ) is a resin composition characterized in that at least 230 seconds.
However, HCT is time (second) which divides the peak area calculated | required by a differential scanning calorimeter into two equal parts at the temperature 12 degreeC lower than melting | fusing point of an ethylene-vinyl alcohol type copolymer (A).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34719795A JP3683321B2 (en) | 1995-12-13 | 1995-12-13 | Resin composition |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34719795A JP3683321B2 (en) | 1995-12-13 | 1995-12-13 | Resin composition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09165483A JPH09165483A (en) | 1997-06-24 |
| JP3683321B2 true JP3683321B2 (en) | 2005-08-17 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34719795A Expired - Lifetime JP3683321B2 (en) | 1995-12-13 | 1995-12-13 | Resin composition |
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| Country | Link |
|---|---|
| JP (1) | JP3683321B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1135772A (en) * | 1997-07-18 | 1999-02-09 | Nippon Synthetic Chem Ind Co Ltd:The | Ethylene-vinyl acetate-based copolymer saponified product composition and molded product therefrom |
| US6447845B1 (en) | 2000-03-03 | 2002-09-10 | Dow Corning Corporation | Barrier coatings using polyacids |
| KR20020075406A (en) | 2000-12-12 | 2002-10-04 | 유니티카 가부시끼가이샤 | Gas-barrier resin composition, gas-barrier coating material, and gas-barrier molding |
-
1995
- 1995-12-13 JP JP34719795A patent/JP3683321B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09165483A (en) | 1997-06-24 |
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