JP3634117B2 - Package - Google Patents

Description

【００３８】
表１に示すように、水蒸気透過度はそれぞれのフィルムで異なっており、フィルムを構成する材料及びフィルムの厚さを選択することにより、所望の水蒸気透過度を有するフィルムを得ることができる。
【００３９】
以下に、本発明の原理について説明する。
一般に、ＰＶＡ等の樹脂からなるバリア層は、酸素バリア性が湿度に大きく影響を受けるという欠点を有している。これは、以下の理由によると考えられる。すなわち、通常、ＰＶＡ等の樹脂は、分子内または分子間で、水酸基により水素結合しているため緻密な構造となり、高い酸素バリア性を有している。しかしながら、湿度が高くなると、これら樹脂の水酸基と水分子とが水素結合するため、分子内または分子間の水素結合が断たれ、緻密さが低下し、酸素バリア性が低下してしまうのである。
【００４０】
それに対し、本発明の包装体に用いられる包装材料のバリア層２は、上述の樹脂の他に無機層状化合物を含有している。本発明の包装体で用いられる無機層状化合物は、吸着性や膨潤性が非常に高いので、上述の樹脂の膨潤を防ぎ、バリア層の酸素バリア性の低下を抑えることができる。
【００４１】
しかしながら、このようにして構成されるバリア層は、通常は高い酸素バリア性を有しているが、例えば、気温が３０℃以上で、湿度が９０％以上になると、酸素バリア性が著しく低下する。これは、無機層状化合物の湿度吸収量が飽和に達し、樹脂が膨潤してしまうこと等によると考えられる。
【００４２】
したがって、上述のバリア層を用いて包装体を構成する場合、バリア層に蓄積される水分の量を極力抑える必要がある。
本発明者は、物品を包装材料により包装する場合、包装される物品の水分活性、及びその保存状態に応じて、包装体の内部と外部とでは湿度が異なることに着目した。
【００４３】
例えば、ハムやソーセージ等の水分活性が０．８７以上の食品、すなわち、包装時に包装体の内部の相対湿度が８７％以上になる水分を多く含む物品は、通常、冷蔵されて流通・保存される。このような物品の冷蔵は、一般に、１０℃以下、３０％ＲＨ以下の低温・低湿度下で行われるため、包装体の内部の方が外部に比べて湿度が高くなる。そのため、水分子のバリア層への移動は、包装体の外部からよりも内部からの方が多くなる。
【００４４】
したがって、このような場合は、包装体の外側に、内側のフィルムよりも水蒸気透過度の高いフィルムを用いることにより、バリア層中の水分を包装体の外部に放出させ、バリア層に蓄積される水分の量を低減することが可能となり、良好な酸素バリア性を得ることができるのである。なお、この場合、バリア層を挟持する２枚のフィルムの防湿性が同じであるとすると、バリア層中の水分の包装体外への移動が抑制されて、バリア層内に過剰な量の水分が蓄積されてしまうため、良好な酸素バリア性を得ることができない。
【００４５】
一方、包装される物品が水分活性が０．６０以下の乾燥物である場合、これらは、一般には、常温・常湿下で流通・保存され、場合によっては、４０℃近い高温や、９０％程度の高湿度条件下に晒される。そのため、包装体の外部の方が内部に比べて湿度が高くなり、水分子のバリア層への移動は、包装体の内部からよりも外部からの方が多くなる。
【００４６】
したがって、このような場合は、包装体の内側に、外側のフィルムよりも水蒸気透過度の高いフィルムを用いることにより、バリア層中の水分を包装体の内部に放出させて、バリア層に蓄積される水分の量を低減することができる。
【００４７】
このように、本発明の包装体では、バリア層を挟持する２枚のフィルムが、それぞれ異なる水蒸気透過度を有し、相対的に水蒸気透過度の高いフィルムが低湿度側になるように配置されるので、バリア層中への水分の蓄積が防止される。したがって、基材フィルム及び被覆フィルムのうち、水蒸気透過度の高いフィルムのバリア層とは逆の面には、水分の移動を妨げないように、別のフィルムを積層しないことが好ましい。
【００４８】
また、この包装材料に、さらに別のフィルムを積層する場合、相対的に水蒸気透過度の低いフィルム上には、それ以下の水蒸気透過度を有するフィルムを積層することが好ましい。このような構成では、バリア層中への水分の蓄積を生じさせることなく、包装材料の水蒸気透過度を低減することができる。
【００４９】
また、相対的に水蒸気透過度の高いフィルム上に、さらに別のフィルムを積層する場合、それ以上の水蒸気透過度を有するフィルムを積層することが好ましい。このような構成では、バリア層中の水蒸気の放出が妨げられることがない。
【００５０】
上述のように、本発明の包装体では、バリア層を挟持する基材フィルムと被覆フィルムとで、水蒸気透過度が異なる。これらフィルムの水蒸気透過度の差は、用いる材料の組み合せを選択することや、フィルムの厚さを制御することにより調節することが可能である。
【００５１】
これらフィルムの水蒸気透過度は、３０℃、１気圧下で、フィルムの一方の面側を湿度９０％とし、他方の面側を湿度７０％とした場合に、１ｇ／ｍ^２ ・ｄａｙ・ａｔｍ以上異なればバリア層中に蓄積される水分の量を低減することができる。しかしながら、水蒸気透過度が、０．５ｇ／ｍ^２ ・ｄａｙ・ａｔｍ以上異なることが好ましく、２ｇ／ｍ^２ ・ｄａｙ・ａｔｍ以上異なることがより好ましい。これらフィルムの水蒸気透過度の差が、上記範囲内にあると、バリア層中に蓄積される水分の量を良好に低減することができる。
【００５２】
なお、図６に、１気圧下での、温度と単位体積当りの飽和水蒸気量との関係をグラフにして示す。このグラフで、横軸は温度を示し、縦軸は単位体積当りの飽和水蒸気量を示している。
【００５３】
このグラフに示すように、飽和水蒸気量は、温度の下降とともに減少し、１０℃での飽和水蒸気量は、４０℃での飽和水蒸気量の５分の１以下である。そのため、冷蔵して保存する場合は、室温で保存する場合に比べて遥かに低水蒸気量の雰囲気下にあるため、包装材料に高い防湿性は要求されない。
【００５４】
したがって、基材フィルムを被覆フィルムに比べてより高防湿性にして乾燥物の包装に用いる場合、基材フィルムとして二軸延伸ポリプロピレンを用い、被覆フィルムとして無延伸ポリプロピレンを用いることが好ましい。また、被覆フィルムを基材フィルムに比べてより高防湿性にして水分を多く含む物品の包装に用いる場合、基材フィルムとしてポリエチレンテレフタレートを用い、被覆フィルムとして無延伸ポリプロピレンを用いることが好ましい。このような構成では、高い酸素バリア性が得られるとともに、低コストで包装体を製造することができる。
【００５５】
【実施例】
以下、本発明の実施例について説明する。
（実施例１）
５重量％のポリビニルアルコール（ＰＶＡ）水溶液に、モンモリロナイトを、ＰＶＡとモンモリロナイトとの重量比が１：１となるように混合して、塗布液Ａを調製した。
【００５６】
次に、基材フィルム１として、厚さが２０μｍで、水蒸気透過度が６〜７ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製二軸延伸ポリプロピレンフィルムＵ１を用い、この一方の主面上に、塗布液Ａをバーコータを用いて塗布し、１２０℃の温度で１分間乾燥させて、厚さ０．５μｍの被膜を形成した。
【００５７】
以上のようにして、厚さ０．５μｍの塗膜を積層することにより、バリア層２を形成した。
次に、このバリア層２上に、接着層５として、武田薬品工業社製ウレタン系２液硬化型接着剤Ａ−９６５を、グラビア法により、４ｇ／ｍ^２ となるように塗布した。さらに、この接着層上に、被覆フィルム３として、厚さが３０μｍで水蒸気透過度が１０ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製無延伸ポリプロピレンフィルムＧＬＣを、ドライラミネート法により積層して、包装材料４を作製した。
【００５８】
以上のようにして作製した包装材料４を２枚用い、それぞれの包装材料４の被覆フィルム３が内側になるようにして３辺をシールして、１辺が開口した袋状の包装体６を作製した。これに水分活性が０．１〜０．２の煎餅、ピーナッツを入れ、包装体６内を窒素ガスで置換した（酸素濃度約５％）後、開口部をシールした。この袋を、ポリプロピレン製の外装袋に入れて保存した。
【００５９】
この煎餅、ピーナッツを包装した包装体６を、温度を４０℃とし、湿度を９０％として、７日間放置した。その結果、包装体内部の酸素濃度に変化は見られず、包装体内の煎餅、ピーナッツに含まれる油脂の酸化や細菌・微生物等の増殖は見られなかった。また、包装体内の湿度の上昇はごく僅かであった。
【００６０】
（実施例２）
基材フィルム１として、厚さが２５μｍで、水蒸気透過度が３．０ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製多層共押出し延伸フィルムＨＭ−１を用いたこと以外は、実施例１と同様にして包装材料４を作製した。
【００６１】
この包装材料４を用いて、実施例１と同様にして、物品の包装、殺菌処理を行い、酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度の変化は見られず、油脂の酸化や細菌・微生物等の増殖は見られなかった。また、包装体内の湿度の上昇はごく僅かであった。
【００６２】
（実施例３）
基材フィルム１として、厚さが２５μｍで、水蒸気透過度が３．０ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製多層共押出し延伸フィルムＨＭ−１を用い、この一方の主面上に、実施例１で調製したのと同様の塗布液Ａをバーコータを用いて塗布し、１２０℃の温度で１分間乾燥させて、厚さ０．２μｍの被膜を形成した。
【００６３】
次に、テトラエトキシシラン１０ｇに０．１Ｎの塩酸２６ｇを加え、３０分間攪拌して、テトラエトキシシランを加水分解させた。また、１００体積％の水を溶媒とする、５重量％のＰＶＡ溶液に、平均粒度が１２０μｍのモンモリロナイトを、ＰＶＡとモンモリロナイトとの重量比が１：１となるように混合した。
【００６４】
このＰＶＡ・モンモリロナイト混合液と、上述のテトラエトキシシランの加水分解溶液とを、重量比で４：６となるように混合して、塗布液Ｂを調製した。
以上のようにして調製した塗布液Ｂを、塗布液Ａを用いて形成した皮膜上に、バーコータを用いて塗布し、１２０℃の温度で１分間乾燥させて、厚さ０．２μｍの被膜を形成した。
【００６５】
このようにして、塗布液Ａ及びＢを用いて、厚さ０．４μｍのバリア層２を形成した。
次に、このバリア層２上に、武田薬品工業社製ウレタン系２液硬化型接着剤Ａ−５１５を、グラビア法により、４ｇ／ｍ^２ となるように塗布した。さらに、この接着層上に、被覆フィルム３として、厚さ３０μｍのユニ加工社製無延伸ポリプロピレンフィルムＲＳ５０Ｃを、ドライラミネート法により積層して、包装材料４を作製した。
【００６６】
この包装材料４を用いて、実施例１と同様にして、物品の包装、殺菌処理を行い、酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度の上昇はごく僅かであり、油脂の酸化や細菌・微生物等の増殖は見られなかった。また、包装体内の湿度の上昇はごく僅かであった。
【００６７】
（実施例４）
塗布液Ａ及びＢを用いて被膜を２層形成する代わりに、塗布液Ｂのみを用いて被膜を２層形成したこと以外は、実施例３と同様にして包装材料４を作製した。
【００６８】
この包装材料４を用いて、実施例１と同様にして、物品の包装、殺菌処理を行い、酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度は殆ど上昇せず、油脂の酸化や細菌・微生物等の増殖は全く見られなかった。また、包装体内の湿度の上昇はごく僅かであった。
【００６９】
（実施例５）
基材フィルム１として、厚さが２０μｍで、水蒸気透過度が６〜７ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製二軸延伸ポリプロピレンフィルムＵ１を用いたこと以外は、実施例４と同様にして包装材料４を作製した。
【００７０】
この包装材料４を用いて、実施例１と同様にして、物品の包装、殺菌処理を行い、酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度は殆ど上昇せず、油脂の酸化や細菌・微生物等の増殖は全く見られなかった。また、包装体内の湿度の上昇はごく僅かであった。
【００７１】
（比較例１）
ポリ塩化ビニリデンがコートされ、厚さが２０μｍであり、水蒸気透過度が３ｇ／ｍ^２ ・ｄａｙ・ａｔｍのダイセル化学社製二軸延伸ポリプロピレンＥＧ−１０の一方の主面上に、接着層として、武田薬品工業社製ウレタン系２液硬化型接着剤Ａ−５１５を、グラビア法により、４ｇ／ｍ^２ となるように塗布した。さらに、この接着層上に、被覆フィルムとして、厚さが３０μｍで、水蒸気透過度が１０ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東セロ社製無延伸ポリプロピレンフィルムＧＬＣを、ドライラミネート法により積層して、包装材料を作製した。
【００７２】
この包装材料を用いて、実施例１と同様にして、物品の包装、殺菌処理を行い、酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度が上昇し、油脂の酸化や細菌・微生物等の増殖が僅かに見られた。
【００７３】
以上のようにして作製した実施例１及び比較例１の包装材料について、３０℃の温度条件下で、湿度を７０％及び９０％とした場合の、基材フィルム側から被覆フィルム側への酸素透過度を、ＭＯＣＯＮ法により測定した。
表２に、実施例１及び比較例１で作製した包装材料の酸素透過度と湿度との関係を示す。
【００７４】
【表２】

【００７５】
この表に示すように、実施例１の包装材料は、湿度が７０％の場合は、比較例１の包装材料に比べて非常に良好な酸素バリア性を有している。しかしながら、湿度が９０％の場合は、比較例１の包装材料は湿度が７０％の場合と同様の酸素透過度を有しており、酸素バリア性の湿度依存性はないのに対し、実施例１の包装材料は、酸素透過度が大幅に増加している。すなわち、実施例１の包装材料は、基材フィルム側と被覆フィルム側の両方を高湿度条件にした場合には、バリア層に水分が蓄積されて、酸素バリア性が低下してしまうのである。
【００７６】
これら実施例１及び比較例１の包装材料について、３０℃の温度条件下で、基材フィルム及び被覆フィルムのいずれか一方側を９０％の湿度とし、他方側の湿度を７０％にして、基材フィルム側から被覆フィルム側への酸素透過度を測定した。その結果を表３に示す。
【００７７】
【表３】

【００７８】
表３において、７０％ＲＨ／９０％ＲＨ及び９０％ＲＨ／７０％ＲＨは、それぞれ基材フィルム側の湿度を７０％、被覆フィルム側の湿度を９０％にした場合と、基材フィルム側の湿度を９０％、被覆フィルム側の湿度を７０％にした場合とを示している。
【００７９】
表３に示すように、基材フィルム側の湿度を７０％とした場合、実施例１の包装材料は比較例１の包装材料に比べて酸素バリア性が低いが、被覆フィルム側の湿度を７０％にすると、実施例１の包装材料でも比較例１の包装材料とほぼ同等の酸素バリア性を得ることができる。したがって、実施例１の包装材料は、被覆フィルム側を基材フィルム側に比べて相対的に低湿度にすることにより、高湿度条件下でも、高い酸素バリア性を得ることができるのである。
【００８０】
次に、実施例１〜５で作製した包装材料、及び比較例１で作製した包装材料について、３０℃の温度条件下で、基材フィルム側を９０％の湿度とし、被覆フィルム側の湿度を、５０、６０、７０、８０、９０％と変化させて、基材フィルム側から被覆フィルム側への酸素透過度を測定した。その結果を表４に示す。
【００８１】
【表４】

【００８２】
表４から明らかなように、実施例１〜５の包装材料は、被覆フィルム側の湿度が低い場合は、いずれも酸素透過度が低く、被覆フィルム側の湿度の上昇とともに酸素透過度が上昇している。
【００８３】
図４に、表４に示す包装材料の酸素透過度と湿度差との関係を、グラフにして示す。また、図５に、図４の一部を拡大して示す。これら図で、横軸は被覆フィルム側の湿度を示し、縦軸は基材フィルム側から被覆フィルム側への酸素透過度を示している。また、グラフ中で、曲線４１〜４５は、それぞれ実施例１〜５の包装材料のデータを示し、曲線４６は、比較例１の包装材料のデータを示している。
【００８４】
図４から明らかなように、実施例４及び５の包装材料は、全ての湿度領域で、比較例１の包装材料よりも低い酸素透過度を示している。
また、実施例１〜３の包装材料は、湿度の上昇とともに酸素透過度が増加しているが、図５に示すように、被覆フィルム側の湿度が７０％以下の場合は、比較例１の包装材料と同等またはそれ以下の酸素透過度を示しており、被覆フィルム側の湿度が６０％以下の場合は、実施例１〜５の包装材料の全てが、比較例１の包装材料よりも低い酸素透過度を示している。
【００８５】
以上の結果から、以下のことが分かる。すなわち、上記実施例１〜５の包装体は、被覆フィルムが基材フィルムよりも内側になるように配置されている。したがって、包装体内に乾燥物を収容する場合は、外気の湿度が９０％程度の高湿度になったとしても、包装体の内部と外部との間に十分な湿度の差があるため、高い酸素バリア性を得ることができるのである。
【００８６】
（実施例６）
基材フィルム１として、厚さが１２μｍで、水蒸気透過度が５５ｇ／ｍ^２ ・ｄａｙ・ａｔｍの東レ社製ポリエチレンテレフタレートフィルムＰ６０を用い、被覆フィルム３として、厚さが３０μｍで、水蒸気透過度が１０ｇ／ｍ^２ ・ｄａｙ・ａｔｍのユニ加工社製無延伸ポリプロピレンフィルムＲＳ５０３Ｃを用いたこと以外は、実施例１と同様にして包装材料４を作製した。
【００８７】
この包装材料４を用い、実施例１と同様にして、水分活性が０．８〜０．９のスライスハムを包装した。
このスライスハムを包装した包装体６を、９０℃でボイルして殺菌を行った後、温度を１０℃とし、湿度を３０％として、７日間放置した。その結果、包装体内部の酸素濃度は殆ど上昇せず、包装体内のスライスハムに含まれる油脂の酸化や細菌・微生物等の増殖、及び色の変化は全く見られなかった。また、包装体内の湿度の変化はごく僅かであった。
【００８８】
（比較例２）
比較例１と同様にして、実施例６で包装した物品を包装した。
これら包装体を用いて、実施例６と同様にして、物品の包装、殺菌処理を行い酸素濃度の変化及び細菌・微生物等の増殖について調べた。その結果、包装体内部の酸素濃度は上昇し、油脂の酸化や細菌・微生物等の増殖が僅かに見られた。
【００８９】
【発明の効果】
以上示したように、本発明によると、無機層状化合物と樹脂とを含有するバリア層を、基材フィルム及び被覆フィルムで挟み、保存時に相対的に低湿度雰囲気下に晒されるフィルムの水蒸気透過度を、他方のフィルムの水蒸気透過度よりも高くすることにより、高湿度条件下でもバリア層中への水分の蓄積が防がれ、高い酸素バリア性を有する包装体が提供される。また、無機層状化合物と樹脂とを含有するバリア層に酸素バリア性を与えているため、塩化物フィルムを用いる必要がない。さらに、通常の塗布法を用いてバリア層を形成することができるので、安価に製造することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る包装体で用いられる包装材料を示す断面図。
【図２】本発明の第１の実施形態に係る包装体を示す断面図。
【図３】本発明の第２の実施形態に係る包装体を示す断面図。
【図４】本発明の実施例及び比較例に係る包装材料の酸素透過度と湿度差との関係を示すグラフ。
【図５】本発明の実施例及び比較例に係る包装材料の酸素透過度と湿度差との関係を示すグラフ。
【図６】１気圧下での温度と単位体積当りの飽和水蒸気量との関係を示すグラフ。
【符号の説明】
１…基材フィルム
２…バリア層
３…被覆フィルム
４…包装材料
５…接着層
６…包装体
７…成形包装容器
８…包装体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a package, and more particularly to a package having a good oxygen barrier property.
[0002]
[Prior art]
In general, packaging of dry foods such as snacks, strawberries, and chocolates, and foods that contain a lot of water such as hams and sausages is expensive in order to prevent the oxidation of fats and bacteria and microorganisms in the foods. Oxygen barrier properties are required. In addition, non-food packaging such as electronic parts and mechanical parts is also required to have high oxygen barrier properties in order to prevent metal rust.
[0003]
Conventionally, packaging materials containing chlorides such as vinyl chloride and vinylidene chloride have been used for packaging bodies for packaging such articles, and sufficient oxygen barrier properties are obtained. However, since the above-mentioned package uses chloride, it has a problem that chlorine gas is generated during incineration.
[0004]
A package that does not use a chloride film is also known. For example, by using a packaging material in which an inorganic material such as aluminum or ceramic is vapor-deposited on a base film, high oxygen barrier properties can be obtained without using chloride. However, in this method, since the vapor deposition method is used, there arises a problem that the cost of the package is increased.
[0005]
[Problems to be solved by the invention]
As described above, the conventional package has a problem that chlorine gas is generated during incineration or the manufacturing cost is high.
An object of this invention is to provide the package which has a high oxygen barrier property and can be manufactured cheaply, without using a chloride film.
[0006]
[Means for Solving the Problems]
The present invention includes a base film, a barrier layer that is laminated on one main surface of the base film, contains an inorganic layered compound and a resin, and is laminated on the barrier layer. Provided is a packaging body comprising a packaging material having a coating film having a water vapor permeability different from that of the material film as a wall material for isolating an article to be packaged from outside air.
[0007]
The present invention is characterized in that, in the above package, the packaging material is formed in a bag shape.
The present invention is characterized in that the packaging body includes a molded container provided with an opening, and the packaging material is a sealing lid for sealing the opening of the molded container.
[0008]
The present invention is characterized in that, in the above package, the barrier layer contains a hydrolysis / polycondensation product of a metal alkoxide.
The present invention is characterized in that, in the above package, the inorganic layered compound is montmorillonite.
[0009]
The present invention is characterized in that, in the above package, the resin is a water-soluble polymer.
The present invention is characterized in that, in the above package, the water-soluble polymer is polyvinyl alcohol.
[0010]
The present invention is characterized in that, in the above package, the hydrolysis / polycondensation product of the metal alkoxide contains silicon oxide.
The present invention wraps an article having a water activity of 0.87 or more in the packaging body, the base film has a higher water vapor permeability than the cover film, and the base film is formed of the cover film. It is arranged on the outside.
[0011]
The present invention wraps an article having a water activity of 0.60 or less in the packaging body, the base film has a lower water vapor permeability than the cover film, and the base film is formed of the cover film. It is arranged on the outside.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, sectional drawing of the packaging material used with the package which concerns on embodiment of this invention is shown.
[0013]
In FIG. 1, the packaging material 4 has a structure in which a barrier layer 2 and a covering film 3 are sequentially laminated on a base film. The barrier layer 2 contains an inorganic layered compound and a resin, and the coating film 3 has a water vapor permeability different from that of the base film 1. An adhesive layer 5 is provided between the barrier layer 2 and the covering film 3 as necessary, and the barrier layer 2 and the covering film 3 are adhered to each other.
[0014]
The package of the present invention is a packaging container in which the packaging material is used as a wall material that isolates articles to be packaged from outside air.
In FIG. 2, sectional drawing of the package which concerns on the 1st Embodiment of this invention is shown. In FIG. 2, the bag-shaped package 6 has a structure in which the packaging material 4 is formed into a bag shape so that the coating film 3 (see FIG. 1) is located inside.
[0015]
In the present invention, the bag-shaped package is a bag-shaped packaging container such as a pillow packaging bag, a four-side sealed bag, a three-side sealed bag, a gusset-shaped bag, and a standing pouch.
FIG. 3 shows a cross-sectional view of a package according to the second embodiment of the present invention. In FIG. 3, the packaging material 4 is pasted as a sealing lid material at the opening of the molded packaging container 7, thereby constituting a package 8. The package 8 is configured such that the covering film 3 (see FIG. 1) is in contact with the opening of the molded packaging container 7.
[0016]
Examples of the molded packaging container include polyethylene, polypropylene, ethylene-vinyl alcohol copolymer, polystyrene, nylon, and composite co-extruded multilayer sheets of these materials, which are generally used materials.
[0017]
These packaging bodies 6 and 8 can be used not only for dry foods such as snacks, candy and chocolate, but also for foods containing a lot of moisture such as ham and sausages, as well as for non-food packaging such as electronic parts and machine parts. .
[0018]
Moreover, normally in these packaging bodies, a coating film is arrange | positioned inside a base film, and the water vapor permeability of a base film and a coating film is selected according to the water activity and preservation | save form of the articles | goods to be packaged. .
[0019]
Hereinafter, the packaging body of the present invention will be described in more detail.
As the base film 1 used in the package of the present invention, polyolefin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyamide such as nylon-6 and nylon-66, polychlorinated Examples thereof include plastic films or sheets having heat resistance such as vinyl, polyimide, polyacrylonitrile, and copolymers of these polymers.
[0020]
Moreover, it is also possible to use paper impregnated with clay coat or the like as the base film.
The thickness of these substrate films is preferably 5 to 200 μm, and more preferably 12 to 30 μm. The water vapor permeability of the base film can be changed by selecting the type of material constituting the base film, and can be controlled by adjusting the thickness of the base film. This base film may contain commonly used additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, and colorants.
[0021]
In the package of the present invention, the substrate film has a water vapor transmission rate of 0 when one surface side is 90% humidity and the other surface side is 0% humidity at 40 ° C. and 1 atm. .1 to 100 g / m²  -It is preferable that it is day * atm.
[0022]
The barrier layer 2 of the package of the present invention contains an inorganic layered compound and a resin.
In the package of the present invention, the inorganic layered compound contained in the barrier layer is a crystalline inorganic compound having a layered structure, such as clay minerals such as kaolinite group, smectite group, and mica group. The kind, particle size, aspect ratio, and the like of these inorganic layered compounds are appropriately selected according to the usage form of the package and are not particularly limited.
[0023]
However, the smectite group such as montmorillonite, hectorite, and saponite easily incorporates other resin components between layers of the inorganic layered compound, and easily forms a complex. Is most preferable, and montmorillonite is preferably used.
[0024]
In the package of the present invention, the resin contained in the barrier layer is not particularly limited as long as it is easily taken in between the layers of the inorganic layered compound described above, but a water-soluble polymer is preferably used. Examples of the water-soluble polymer include polyvinyl alcohol (PVA), polyvinyl pyrrolidone, starch, methyl cellulose, carboxymethyl cellulose, sodium alginate, and an acrylic resin. In particular, the use of PVA is preferable because the highest gas barrier property can be obtained.
[0025]
In addition, PVA here is obtained by, for example, saponifying polyvinyl acetate, and includes from partially saponified PVA in which several tens percent of acetate groups remain to completely saponified PVA in which only several percent of acetate groups remain. .
[0026]
The barrier layer of the package of the present invention preferably contains a hydrolysis / polycondensation product of a metal alkoxide. This metal alkoxide has the following general formula, where M is a metal, R is an alkyl group, and n is the coordination number of an alkoxy group:
M (OR)_n
It is a compound shown by these. It is preferable that M is selected from the group consisting of Si, Ti, Al and Zr, and R is selected from a methyl group and an ethyl group. In particular, tetraethoxysilane [Si (OC₂  H₅  )₄  ] And triisopropoxyaluminum [Al (O-2'-C₃  H₇  )₃  ] Or the like is preferable because the hydrolysis product of alkoxide exists relatively stably in an aqueous solvent. These metal alkoxides can also be used as a mixture.
[0027]
In the package of the present invention, the barrier layer 2 is formed as follows. First, an aqueous solution or water / alcohol solution of the above-mentioned inorganic layered compound and a resin are mixed, and further, a metal alkoxide is mixed as necessary to prepare a coating agent. The metal alkoxide may be hydrolyzed in advance before mixing, or may be hydrolyzed after mixing.
[0028]
Next, this coating agent is coated on the above-mentioned base film, and this is heated and dried at 40 to 150 ° C. to form a barrier layer.
Additives such as isocyanate compounds, silane coupling agents, dispersants, stabilizers, viscosity modifiers, and colorants are added to the above-described coating agent as long as the oxygen barrier property of the formed barrier layer is not impaired. be able to.
[0029]
The isocyanate compound used in the package of the present invention has two or more isocyanate groups (NCO groups) in the molecule. For example, tolylene diisocyanate (TDI), triphenylmethane triisocyanate (TTI), tetra Mention may be made of monomers such as methylxylene diisocyanate (TMXDI), polymers of these monomers, and derivatives of these monomers and polymers.
[0030]
Moreover, as a coating method of a coating agent, a dipping method, a roll coating method, a screen printing method, a spray method and the like that are usually used can be exemplified.
[0031]
In the package of the present invention, the thickness of the barrier layer is preferably 0.01 to 2.0 μm, and more preferably 0.1 to 0.5 μm in a dry state. Increasing the thickness of the barrier layer can reduce the water vapor permeability of the package and increase the oxygen barrier property, but if the thickness of the barrier layer exceeds 2.0 μm, cracks and the like are likely to occur in the barrier layer. Processing suitability is inferior, such as drying time. Moreover, when the thickness of the barrier layer is less than 0.01 μm, sufficient oxygen barrier properties cannot be obtained.
[0032]
In the package of the present invention, the barrier layer preferably contains 10 to 90% by weight of the inorganic layered compound and 10 to 90% by weight of the resin. In the package of the present invention, the barrier layer preferably contains 10 to 90% by weight of a metal alkoxide hydrolysis / polycondensation product.
[0033]
Examples of the covering film 3 used in the package of the present invention include resin films having heat sealing properties such as polyethylene, polypropylene, ethylene copolymer, and saturated polyester. In particular, when heat resistance is required, it is preferable to use an unstretched polypropylene film. Moreover, when the polyolefin synthesize | combined using the metallocene catalyst is used, adhesion of the resin odor to the packaged article can be reduced.
[0034]
By adjusting the thickness of these coating films, the water vapor transmission rate of the coating films can be controlled. The thickness of the coating film is preferably 10 to 200 μm, and more preferably 20 to 50 μm.
[0035]
In the package of the present invention, the coating film has a water vapor transmission rate of 3 to 20 g / 40% at 40 ° C. and 1 atm, when one surface side has a humidity of 90% and the other surface side has a humidity of 0%. m²  -It is preferable that it is day * atm.
[0036]
This coating film is preferably laminated on the barrier layer via an adhesive such as a two-component or one-component curable urethane adhesive having heat resistance. It is also possible to laminate by directly extrusion coating the molten resin.
An example of the film used for the base film and the covering film described above is shown in Table 1.
[0037]
[Table 1]

[0038]
As shown in Table 1, the water vapor permeability is different for each film, and a film having a desired water vapor permeability can be obtained by selecting the material constituting the film and the thickness of the film.
[0039]
The principle of the present invention will be described below.
In general, a barrier layer made of a resin such as PVA has a drawback that oxygen barrier properties are greatly affected by humidity. This is considered to be due to the following reason. That is, normally, a resin such as PVA has a dense structure because it is hydrogen-bonded by a hydroxyl group in a molecule or between molecules, and has a high oxygen barrier property. However, when the humidity is increased, the hydroxyl groups of these resins and water molecules are hydrogen-bonded, so the hydrogen bonds within or between the molecules are broken, the density is lowered, and the oxygen barrier properties are lowered.
[0040]
On the other hand, the barrier layer 2 of the packaging material used for the package of the present invention contains an inorganic layered compound in addition to the above-described resin. Since the inorganic layered compound used in the package of the present invention has very high adsorptivity and swelling property, it is possible to prevent the above-mentioned resin from swelling and to suppress a decrease in oxygen barrier property of the barrier layer.
[0041]
However, the barrier layer configured in this manner usually has a high oxygen barrier property. However, for example, when the temperature is 30 ° C. or higher and the humidity is 90% or higher, the oxygen barrier property is significantly reduced. . This is presumably because the moisture absorption amount of the inorganic layered compound reaches saturation and the resin swells.
[0042]
Therefore, when a package is configured using the above-described barrier layer, it is necessary to suppress the amount of moisture accumulated in the barrier layer as much as possible.
The present inventor has paid attention to the fact that when the article is packaged with a packaging material, the humidity differs between the inside and the outside of the package according to the water activity of the article to be packaged and its storage state.
[0043]
For example, foods having a water activity of 0.87 or more such as ham or sausage, that is, articles containing a lot of water whose relative humidity inside the package is 87% or more during packaging are usually refrigerated and distributed and stored. The Since refrigeration of such articles is generally performed at a low temperature and low humidity of 10 ° C. or lower and 30% RH or lower, the humidity inside the package is higher than the outside. Therefore, the movement of water molecules to the barrier layer is greater from the inside than from the outside of the package.
[0044]
Therefore, in such a case, by using a film having a higher water vapor permeability than the inner film on the outside of the package, the moisture in the barrier layer is released to the outside of the package and is accumulated in the barrier layer. It becomes possible to reduce the amount of moisture, and good oxygen barrier properties can be obtained. In this case, if the moisture resistance of the two films sandwiching the barrier layer is the same, the movement of moisture in the barrier layer to the outside of the package is suppressed, and an excessive amount of moisture is contained in the barrier layer. Since it accumulates, good oxygen barrier properties cannot be obtained.
[0045]
On the other hand, when the article to be packaged is a dried product having a water activity of 0.60 or less, these are generally distributed and stored under normal temperature and normal humidity. Exposed to moderately high humidity conditions. Therefore, the humidity outside the package is higher than the inside, and the movement of water molecules to the barrier layer is greater from the outside than from the inside of the package.
[0046]
Therefore, in such a case, by using a film having a higher water vapor permeability than the outer film on the inner side of the package body, moisture in the barrier layer is released into the package body and accumulated in the barrier layer. The amount of moisture to be reduced can be reduced.
[0047]
As described above, in the package of the present invention, the two films sandwiching the barrier layer have different water vapor permeability, and the films having a relatively high water vapor permeability are arranged on the low humidity side. Therefore, accumulation of moisture in the barrier layer is prevented. Therefore, it is preferable not to laminate another film on the surface opposite to the barrier layer of the film having a high water vapor permeability among the base film and the covering film so as not to prevent the movement of moisture.
[0048]
Further, when another film is laminated on the packaging material, it is preferable to laminate a film having a water vapor permeability lower than that on a film having a relatively low water vapor permeability. With such a configuration, the water vapor permeability of the packaging material can be reduced without causing moisture accumulation in the barrier layer.
[0049]
When another film is laminated on a film having a relatively high water vapor permeability, it is preferable to laminate a film having a water vapor permeability higher than that. In such a configuration, the release of water vapor in the barrier layer is not hindered.
[0050]
As described above, in the package of the present invention, the water vapor permeability is different between the base film and the covering film that sandwich the barrier layer. The difference in water vapor permeability of these films can be adjusted by selecting a combination of materials to be used or by controlling the thickness of the film.
[0051]
The water vapor permeability of these films is 1 g / m at 30 ° C. and 1 atm when one side of the film has a humidity of 90% and the other side has a humidity of 70%.²  If the difference is more than day · atm, the amount of moisture accumulated in the barrier layer can be reduced. However, the water vapor permeability is 0.5 g / m²  ・ Day · atm is preferably more than 2g / m²  It is more preferable that they differ by more than day · atm. If the difference in water vapor permeability between these films is within the above range, the amount of moisture accumulated in the barrier layer can be reduced satisfactorily.
[0052]
FIG. 6 is a graph showing the relationship between the temperature and the saturated water vapor amount per unit volume at 1 atm. In this graph, the horizontal axis indicates the temperature, and the vertical axis indicates the saturated water vapor amount per unit volume.
[0053]
As shown in this graph, the saturated water vapor amount decreases with a decrease in temperature, and the saturated water vapor amount at 10 ° C. is 1/5 or less of the saturated water vapor amount at 40 ° C. Therefore, when stored in a refrigerated state, the packaging material is not required to have high moisture resistance because it is in a much lower water vapor atmosphere than when stored at room temperature.
[0054]
Therefore, when making a base film more moisture-proof compared with a covering film and using it for packaging of a dried product, it is preferable to use a biaxially stretched polypropylene as a base film and to use an unstretched polypropylene as a covering film. Further, when the coated film is made more moisture-proof than the substrate film and used for packaging of articles containing a lot of moisture, it is preferable to use polyethylene terephthalate as the substrate film and unstretched polypropylene as the coating film. With such a configuration, a high oxygen barrier property can be obtained, and a package can be manufactured at a low cost.
[0055]
【Example】
Examples of the present invention will be described below.
Example 1
A coating liquid A was prepared by mixing montmorillonite with a 5 wt% polyvinyl alcohol (PVA) aqueous solution so that the weight ratio of PVA to montmorillonite was 1: 1.
[0056]
Next, the base film 1 has a thickness of 20 μm and a water vapor permeability of 6 to 7 g / m.²  Using a biaxially stretched polypropylene film U1 made by Toh Cello Co., day / atm, the coating liquid A was applied onto one main surface using a bar coater and dried at a temperature of 120 ° C. for 1 minute to obtain a thickness of 0 A film having a thickness of 5 μm was formed.
[0057]
Thus, the barrier layer 2 was formed by laminating | stacking a 0.5 micrometer-thick coating film.
Next, on the barrier layer 2, as the adhesive layer 5, a urethane two-component curable adhesive A-965 manufactured by Takeda Pharmaceutical Co., Ltd.²  It applied so that it might become. Further, on this adhesive layer, as the coating film 3, the thickness is 30 μm and the water vapor permeability is 10 g / m.²  A non-stretched polypropylene film GLC manufactured by Tosero Co., Ltd., day / atm, was laminated by a dry laminating method to produce a packaging material 4.
[0058]
Using two sheets of the packaging material 4 produced as described above, and sealing the three sides so that the covering film 3 of each packaging material 4 is on the inside, a bag-like packaging body 6 having one side opened is formed. Produced. A rice cracker and peanuts having a water activity of 0.1 to 0.2 were added thereto, and the inside of the package 6 was replaced with nitrogen gas (oxygen concentration about 5%), and then the opening was sealed. The bag was stored in a polypropylene outer bag.
[0059]
The package 6 packaged with the rice crackers and peanuts was left for 7 days at a temperature of 40 ° C. and a humidity of 90%. As a result, no change was observed in the oxygen concentration inside the package, and oxidization of fats and oils contained in the package, peanuts, and growth of bacteria and microorganisms were not observed. Also, the increase in humidity in the package was negligible.
[0060]
(Example 2)
The base film 1 has a thickness of 25 μm and a water vapor permeability of 3.0 g / m.²  A packaging material 4 was produced in the same manner as in Example 1 except that a multilayer coextruded stretched film HM-1 manufactured by Tosero Co., Ltd., day / atm was used.
[0061]
Using this packaging material 4, packaging and sterilization of articles were performed in the same manner as in Example 1, and changes in oxygen concentration and growth of bacteria, microorganisms, etc. were examined. As a result, no change in the oxygen concentration inside the package was observed, and no oxidation of fats and oils and growth of bacteria, microorganisms, etc. were observed. Also, the increase in humidity in the package was negligible.
[0062]
(Example 3)
The base film 1 has a thickness of 25 μm and a water vapor permeability of 3.0 g / m.²  Using a multilayer coextrusion stretched film HM-1 manufactured by Toh Cello Co., Ltd. of day.atm, the same coating liquid A as prepared in Example 1 was applied onto this one main surface using a bar coater. The film was dried at a temperature of 1 minute for 1 minute to form a film having a thickness of 0.2 μm.
[0063]
Next, 26 g of 0.1N hydrochloric acid was added to 10 g of tetraethoxysilane and stirred for 30 minutes to hydrolyze tetraethoxysilane. Further, montmorillonite having an average particle size of 120 μm was mixed with a 5 wt% PVA solution using 100 vol% water as a solvent so that the weight ratio of PVA to montmorillonite was 1: 1.
[0064]
This PVA / montmorillonite mixed solution and the above-mentioned tetraethoxysilane hydrolyzed solution were mixed at a weight ratio of 4: 6 to prepare a coating solution B.
The coating liquid B prepared as described above is applied onto the film formed using the coating liquid A using a bar coater and dried at a temperature of 120 ° C. for 1 minute to form a film having a thickness of 0.2 μm. Formed.
[0065]
In this manner, a barrier layer 2 having a thickness of 0.4 μm was formed using the coating liquids A and B.
Next, on this barrier layer 2, a urethane type two-component curable adhesive A-515 manufactured by Takeda Pharmaceutical Company Limited is 4 g / m by gravure method.²  It applied so that it might become. Further, on this adhesive layer, a non-stretched polypropylene film RS50C having a thickness of 30 μm manufactured by Uni Processing Co. was laminated as a coating film 3 by a dry laminating method to produce a packaging material 4.
[0066]
Using this packaging material 4, packaging and sterilization of articles were performed in the same manner as in Example 1, and changes in oxygen concentration and growth of bacteria, microorganisms, etc. were examined. As a result, the increase in oxygen concentration inside the package was negligible, and oxidation of fats and oils and growth of bacteria and microorganisms were not observed. Also, the increase in humidity in the package was negligible.
[0067]
Example 4
A packaging material 4 was produced in the same manner as in Example 3 except that two coating layers were formed using only the coating solution B instead of forming two coating layers using the coating solutions A and B.
[0068]
Using this packaging material 4, packaging and sterilization of articles were performed in the same manner as in Example 1, and changes in oxygen concentration and growth of bacteria, microorganisms, etc. were examined. As a result, the oxygen concentration inside the package hardly increased, and the oxidation of fats and oils and the growth of bacteria and microorganisms were not observed at all. Also, the increase in humidity in the package was negligible.
[0069]
(Example 5)
The base film 1 has a thickness of 20 μm and a water vapor permeability of 6 to 7 g / m.²  A packaging material 4 was produced in the same manner as in Example 4 except that a biaxially stretched polypropylene film U1 manufactured by Tosero Co., Ltd., day / atm was used.
[0070]
Using this packaging material 4, packaging and sterilization of articles were performed in the same manner as in Example 1, and changes in oxygen concentration and growth of bacteria, microorganisms, etc. were examined. As a result, the oxygen concentration inside the package hardly increased, and the oxidation of fats and oils and the growth of bacteria and microorganisms were not observed at all. Also, the increase in humidity in the package was negligible.
[0071]
(Comparative Example 1)
Coated with polyvinylidene chloride, thickness is 20 μm, water vapor permeability is 3 g / m²  On the main surface of the biaxially stretched polypropylene EG-10 manufactured by Daicel Chemical Industries, which is a day / atm, as an adhesive layer, a urethane-based two-component curable adhesive A-515 manufactured by Takeda Pharmaceutical Co., Ltd. 4g / m²  It applied so that it might become. Further, on this adhesive layer, as a coating film, the thickness is 30 μm and the water vapor permeability is 10 g / m.²  A non-stretched polypropylene film GLC manufactured by Tosero Co., Ltd., day.atm, was laminated by a dry laminating method to produce a packaging material.
[0072]
Using this packaging material, the product was packaged and sterilized in the same manner as in Example 1, and changes in oxygen concentration and growth of bacteria, microorganisms, and the like were examined. As a result, the oxygen concentration inside the package increased, and the oxidation of fats and oils and the growth of bacteria and microorganisms were slightly observed.
[0073]
About the packaging material of Example 1 and Comparative Example 1 produced as described above, oxygen from the base film side to the coating film side when the humidity is 70% and 90% under the temperature condition of 30 ° C. The transmittance was measured by the MOCON method.
Table 2 shows the relationship between oxygen permeability and humidity of the packaging materials produced in Example 1 and Comparative Example 1.
[0074]
[Table 2]

[0075]
As shown in this table, the packaging material of Example 1 has a very good oxygen barrier property as compared with the packaging material of Comparative Example 1 when the humidity is 70%. However, when the humidity is 90%, the packaging material of Comparative Example 1 has the same oxygen permeability as when the humidity is 70%, and there is no humidity dependency of the oxygen barrier property. The packaging material of 1 has a significantly increased oxygen permeability. That is, in the packaging material of Example 1, when both the base film side and the coating film side are subjected to a high humidity condition, moisture is accumulated in the barrier layer and the oxygen barrier property is lowered.
[0076]
With respect to the packaging materials of Example 1 and Comparative Example 1, under the temperature condition of 30 ° C., either one of the base film and the covering film is set to 90% humidity, and the other side humidity is set to 70%. The oxygen permeability from the material film side to the coating film side was measured. The results are shown in Table 3.
[0077]
[Table 3]

[0078]
In Table 3, 70% RH / 90% RH and 90% RH / 70% RH indicate that the humidity on the base film side is 70% and the humidity on the cover film side is 90%, respectively, It shows the case where the humidity is 90% and the humidity on the coated film side is 70%.
[0079]
As shown in Table 3, when the humidity on the base film side is 70%, the packaging material of Example 1 has a lower oxygen barrier property than the packaging material of Comparative Example 1, but the humidity on the coating film side is 70%. %, The packaging material of Example 1 can obtain oxygen barrier properties substantially equivalent to those of the packaging material of Comparative Example 1. Therefore, the packaging material of Example 1 can obtain a high oxygen barrier property even under high humidity conditions by setting the coating film side to a relatively low humidity compared to the base film side.
[0080]
Next, about the packaging material produced in Examples 1-5 and the packaging material produced in Comparative Example 1, the substrate film side is set to 90% humidity under the temperature condition of 30 ° C., and the humidity on the coating film side is set. , 50, 60, 70, 80, and 90%, and the oxygen permeability from the base film side to the coating film side was measured. The results are shown in Table 4.
[0081]
[Table 4]

[0082]
As is clear from Table 4, the packaging materials of Examples 1 to 5 have low oxygen permeability when the humidity on the coated film side is low, and the oxygen permeability increases with increasing humidity on the coated film side. ing.
[0083]
FIG. 4 is a graph showing the relationship between the oxygen permeability of the packaging material shown in Table 4 and the humidity difference. FIG. 5 is an enlarged view of a part of FIG. In these figures, the horizontal axis indicates the humidity on the side of the coated film, and the vertical axis indicates the oxygen permeability from the substrate film side to the coated film side. Moreover, in the graph, the curves 41 to 45 show the data of the packaging materials of Examples 1 to 5, respectively, and the curve 46 shows the data of the packaging material of Comparative Example 1.
[0084]
As is clear from FIG. 4, the packaging materials of Examples 4 and 5 exhibit lower oxygen permeability than the packaging material of Comparative Example 1 in all humidity regions.
The packaging materials of Examples 1 to 3 increased in oxygen permeability with an increase in humidity. However, as shown in FIG. 5, when the humidity on the coating film side was 70% or less, When the oxygen permeability is equal to or lower than that of the packaging material and the humidity on the coated film side is 60% or less, all of the packaging materials of Examples 1 to 5 are lower than the packaging material of Comparative Example 1. Oxygen permeability is shown.
[0085]
From the above results, the following can be understood. That is, the packaging bodies of Examples 1 to 5 are arranged so that the covering film is inside the base film. Therefore, when the dry matter is stored in the package, even if the humidity of the outside air becomes as high as about 90%, there is a sufficient difference in humidity between the inside and the outside of the package, so high oxygen Barrier properties can be obtained.
[0086]
(Example 6)
The base film 1 has a thickness of 12 μm and a water vapor transmission rate of 55 g / m.²  -Uses a polyethylene terephthalate film P60 manufactured by Toray Industries, Inc. day / atm.²  A packaging material 4 was produced in the same manner as in Example 1 except that unstretched polypropylene film RS503C manufactured by Uni Processing Co., Ltd., day / atm was used.
[0087]
Using this packaging material 4, sliced ham having a water activity of 0.8 to 0.9 was packaged in the same manner as in Example 1.
The package 6 in which the sliced ham was packaged was boiled at 90 ° C. for sterilization, and then left for 7 days at a temperature of 10 ° C. and a humidity of 30%. As a result, the oxygen concentration inside the package hardly increased, and oxidation of fats and oils contained in the sliced ham in the package, growth of bacteria and microorganisms, and color change were not seen at all. Moreover, the change in humidity in the package was negligible.
[0088]
(Comparative Example 2)
In the same manner as in Comparative Example 1, the article packaged in Example 6 was packaged.
Using these packages, packaging of articles and sterilization treatment were performed in the same manner as in Example 6 to examine changes in oxygen concentration and growth of bacteria and microorganisms. As a result, the oxygen concentration inside the package increased, and the oxidation of fats and oils and the growth of bacteria and microorganisms were slightly observed.
[0089]
【The invention's effect】
As described above, according to the present invention, the water vapor permeability of a film that is sandwiched between a base film and a coating film and exposed to a relatively low humidity atmosphere during storage according to the present invention. By making the water vapor permeability higher than that of the other film, accumulation of moisture in the barrier layer is prevented even under high humidity conditions, and a package having high oxygen barrier properties is provided. Further, since the oxygen barrier property is imparted to the barrier layer containing the inorganic stratiform compound and the resin, it is not necessary to use a chloride film. Furthermore, since a barrier layer can be formed using a normal coating method, it can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a packaging material used in a package according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a package according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a package according to a second embodiment of the present invention.
FIG. 4 is a graph showing the relationship between oxygen permeability and humidity difference of packaging materials according to examples and comparative examples of the present invention.
FIG. 5 is a graph showing the relationship between oxygen permeability and humidity difference of packaging materials according to examples and comparative examples of the present invention.
FIG. 6 is a graph showing the relationship between the temperature under 1 atm and the amount of saturated water vapor per unit volume.
[Explanation of symbols]
1 ... Base film
2 ... Barrier layer
3 ... Coating film
4 ... Packaging materials
5 ... Adhesive layer
6 ... Packaging body
7 ... Molded packaging container
8 ... Packaging body

Claims (8)

A package for packaging a dried product having a water activity of 0.60 or less,
A base film;
A barrier layer laminated on one main surface of the base film and containing an inorganic layered compound and a resin;
Laminated on the barrier layer, a water vapor permeability coating film different from the water vapor permeability of the base film,
Packaging materials having a, comprises a wall material that isolates the dry matter from the outside air, the base film has a low water vapor transmission rate than that of the coating film, on the outside of the base film is the coating film A package characterized by being arranged . The package according to claim 1, wherein the packaging material is formed in a bag shape. Comprising a molded container provided with an opening,
The package according to claim 1, wherein the packaging material is a sealing lid material that seals an opening of the molded container. The package according to claim 1, wherein the barrier layer contains a hydrolysis / polycondensation product of a metal alkoxide. The package according to claim 1, wherein the inorganic layered compound is montmorillonite. The package according to claim 1, wherein the resin is a water-soluble polymer. The package according to claim 6, wherein the water-soluble polymer is polyvinyl alcohol. The package according to claim 4, wherein the hydrolysis / polycondensation product of the metal alkoxide contains silicon oxide.

Images