【０００１】
【発明の属する技術分野】
本発明は、紙を主体とし、且つ断熱性を有する断熱性紙製成型物及びその製造方法に関し、詳しくは断熱保温性、剛性、緩衝性に優れ、廃棄物として焼却した場合に燃焼エネルギーや環境汚染の低減が図れる断熱性紙製成型物及びその製造方法に関する。
【０００２】
【従来の技術】
断熱保温性、剛性、緩衝性を有する成型物として、従来、発泡ポリスチレン樹脂シートを用いて熱圧成型機により成型された食品容器が広く用いられているが、近年の環境汚染問題、焼却時の焼却炉の損傷防止、石油資源の節約等の観点から紙を主体とした、例えば、紙基材の一方の面にクレープ紙、段ボール紙、不織布等を貼合した複合体からなる紙コップや丼型容器が提案されている（例えば、特許文献１参照。）。
【０００３】
【特許文献１】
特開２００２−１７３１３０号公報（［０００９］段）
【０００４】
【発明が解決しようとする課題】
しかしながら、紙を主体とした、例えば前記クレープ紙、段ボール紙、不織布等を紙基材に貼合した複合体は、プラスチック基材と比較して伸び特性が本質的に劣るため複雑な形状の成型物が得られず、成型性に難点があり、また、紙は一般的なプラスチック成型機では成型できず、成型方法が限定される問題点を有している。
【０００５】
そこで、プラスチックと同様に容易に３次元曲面の形状に成型でき、且つ断熱保温性を有する断熱性紙製成型物及びその成型物を簡便且つ安価に得ることができる製造方法が望まれている。
【０００６】
本発明の目的は、発泡ポリスチレン樹脂シートに匹敵する十分な断熱性及び緩衝性を有する紙を用いた断熱性紙製成型物を得ることにある。
本発明の他の目的は、従来のプラスチック成型機を用いて成型できる断熱性紙製成型物の製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
上記の目的を達成する本発明の手段を説明すると、次の通りである。
請求項１に記載の断熱性紙製成型物は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、熱可塑性高分子樹脂発泡層が積層された成型素材で成型されてなることを特徴とする。
【０００８】
かかる構成からなる断熱性紙製成型物は、紙層に熱可塑性高分子樹脂発泡層が積層された成型素材で成型されているので、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性がある。また、前記成型素材を構成する紙層の紙が、破断伸びが縦方向及び横方向共に１０％以上有するので、複雑な成型物を得ることができる。更には、この断熱性成型物の合成樹脂部分は前記熱可塑性高分子樹脂発泡層だけなので、成型物全体が合成樹脂からなっている発泡ポリスチレン樹脂シートからなる成型物と較べ廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる。
【０００９】
請求項２に記載の断熱性紙製成型物は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、熱可塑性高分子樹脂発泡層の一面側が積層され、この熱可塑性高分子樹脂発泡層の他面側に破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層が積層された成型素材で成型されてなることを特徴とする。
【００１０】
かかる構成からなる断熱性紙製成型物は、紙層に熱可塑性高分子樹脂発泡層が積層された成型素材で成型されているので、発泡ポリスチレン樹脂シートに匹敵する十分な断熱性、緩衝性がある。また、前記成型素材を構成する紙層の紙が、破断伸びが縦方向及び横方向共に１０％以上有するので、複雑な成型物を得ることができる。更には、この断熱性成型物の合成樹脂部分は前記熱可塑性高分子樹脂発泡層だけなので、成型物全体が合成樹脂からなっている発泡ポリスチレン樹脂シートからなる成型物と較べ廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる。
【００１１】
請求項３に記載の断熱性紙製成型物は、請求項１又は２のいずれか１項に記載の、前記熱可塑性高分子樹脂発泡層の重量が前記紙層の重量の９０％〜２０％であることを特徴とする。
【００１２】
このように熱可塑性高分子樹脂発泡層の重量比が紙１００％に対して９０％〜２０％であると、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られる。熱可塑性高分子樹脂発泡層の重量比が９０％を超えると、成型物としての紙成分が少なくなるため、環境汚染の観点から好ましくなく、２０％未満では、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られず、好ましくない。
【００１３】
請求項４に記載の断熱性紙製成型物は、請求項１乃至３のいずれか１項に記載の、前記熱可塑性高分子樹脂発泡層を構成している熱可塑性高分子樹脂が、生分解性樹脂または水溶性高分子樹脂であることを特徴とする。
【００１４】
このように、熱可塑性高分子樹脂発泡層を構成している熱可塑性高分子樹脂が、生分解性樹脂または水溶性高分子樹脂であると、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる他、生分解性樹脂の場合は、土壌中に埋設することにより、容易に分解されるので、また、水溶性高分子樹脂の場合は、容易に紙層を形成する紙を回収できるので、いずれにしても廃棄物の減容化が図れる。
【００１５】
請求項５に記載の断熱性紙製成型物の製造方法は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、発泡剤を含む熱可塑性高分子樹脂層が積層された成型素材を用い、この成型素材を加熱し熱可塑性高分子樹脂層を発泡させた後、金型を用いて成型することを特徴とする。
【００１６】
かかる構成から、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【００１７】
請求項６に記載の断熱性紙製成型物の製造方法は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、発泡剤を含む熱可塑性高分子樹脂層が積層された成型素材を用い、加熱した金型を用いて前記熱可塑性高分子樹脂層を発泡させながら成型することを特徴とする。
【００１８】
かかる構成から、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【００１９】
請求項７に記載の断熱性紙製成型物の製造方法は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、発泡剤を含む熱可塑性高分子樹脂層の一面側が積層され、この発泡剤を含む熱可塑性高分子樹脂層の他面側に破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層が積層された成型素材を用い、この成型素材を加熱し熱可塑性高分子樹脂層を発泡させた後、金型を用いて成型することを特徴とする。
【００２０】
かかる構成から、発泡ポリスチレン樹脂シートに匹敵する十分な剛性、断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な熱圧成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【００２１】
請求項８に記載の断熱性紙製成型物の製造方法は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、発泡剤を含む熱可塑性高分子樹脂層の一面側が積層され、この発泡剤を含む熱可塑性高分子樹脂層の他面側に破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層が積層された成型素材を用い、加熱した金型を用いて前記熱可塑性高分子樹脂層を発泡させながら成型することを特徴とする。
【００２２】
かかる構成から、発泡ポリスチレン樹脂シートに匹敵する十分な断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な熱圧成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【００２３】
請求項９に記載の断熱性紙製成型物の製造方法は、請求項５乃至８のいずれか１項に記載の、前記熱可塑性高分子樹脂層の重量が前記紙層の重量の９０％〜２０％であることを特徴とする。
【００２４】
このように熱可塑性高分子樹脂層の重量比が紙１００％に対して９０％〜２０％であると、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られる。熱可塑性高分子樹脂層の重量比が９０％を超えると、成型物としての紙成分が少なくなるため、環境汚染の観点から好ましくなく、２０％未満では、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られず、好ましくない。
【００２５】
請求項１０に記載の断熱性紙製成型物の製造方法は、請求項５乃至９のいずれか１項に記載の、前記熱可塑性高分子樹脂層を構成している熱可塑性高分子樹脂が、生分解性樹脂または水溶性高分子樹脂であることを特徴とする。
【００２６】
このように、熱可塑性高分子樹脂層を構成している熱可塑性高分子樹脂が、生分解性樹脂または水溶性高分子樹脂であると、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる他、生分解性樹脂の場合は、土壌中に埋設することにより、容易に分解されるので、また、水溶性高分子樹脂の場合は、容易に紙層を形成する紙を回収できるので、いずれにしても廃棄物の減容化が図れる。
【００２７】
【発明の実施の形態】
以下、本発明に係る断熱性紙製成型物及びその製造方法の実施の形態の一例を説明する。
先ず、断熱性紙製成型物の実施の形態を説明する。
図１は断熱性紙製成型物の実施の形態の第１例を示すもので、本例では、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１の一面側に、熱可塑性高分子樹脂発泡層２が積層された成型素材３で成型されている。
【００２８】
図２は断熱性紙製成型物の実施の形態の第２例を示すもので、本例では、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１の一面側に、熱可塑性高分子樹脂発泡層２の一面側が積層され、この熱可塑性高分子樹脂発泡層２の他面側に破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１が積層された成型素材３で成型されている。
【００２９】
前記第１例及び第２例に示す成型素材３を構成する紙層１及び熱可塑性高分子樹脂発泡層２は共通するので、区別しないで説明する。
前記成型素材３を構成する紙層１は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙、いわゆる伸張紙からなる。前記紙は、その原料が針葉樹パルプまたは広葉樹パルプのいずれか一方または双方からなる天然パルプ１００％からなり、坪量が５０ｇ／ｍ２〜３００ｇ／ｍ２の範囲にあることが好ましい。坪量が５０ｇ／ｍ２未満であると、成型物の剛性不足や断熱性不足となり、好ましくない。また、坪量が３００ｇ／ｍ２を超えると、紙の絶対強度が高く、成型時の負荷が大きくなるため、経済的でない。
【００３０】
前記熱可塑性高分子樹脂発泡層２は、発泡剤を含んだ熱可塑性高分子樹脂層を発泡させて形成されている。前記熱可塑性高分子樹脂としては、熱可塑性があれば特に限定されるものではないが、溶融温度、粘度、発泡特性等の点から一般的な生分解性樹脂、ポリスチレン系樹脂、アイオノマー樹脂、またはポリビニルアルコール、デンプン、カルボキシメチルセルロース等の水溶性高分子樹脂が好適である。
【００３１】
また、発泡剤としては、物理発泡剤や化学発泡剤等、公知の発泡剤が使用できるが、発泡層の形成性や、紙への積層が印刷機、塗工機または押出しラミネート機等の汎用設備を使用して行える等の観点から化学発泡剤、所謂熱分解型発泡剤が好適である。熱分解型発泡剤は、重炭酸ナトリウム等の無機系分解型発泡剤、アゾジカーボンアミド、アゾビスイソブチロニトリル、ジアゾアミノベンゼン、ジニトロソペンタメチレンテトラミン等の有機系分解型発泡剤が使用できる。特に、分解温度のシャープ性、発生ガス量が多く少量の添加で高発泡倍率が得られる等から、アゾジカーボンアミドが好適である。
【００３２】
発泡剤を含む熱可塑性高分子樹脂層は熱可塑性高分子樹脂と発泡剤の他、必要に応じて、可塑剤、耐水化剤、無機充填剤等が混合される。
【００３３】
前記熱可塑性高分子樹脂発泡層２の重量比は前記紙層１の１００％に対して９０％〜２０％であることが好ましい。熱可塑性高分子樹脂発泡層２の重量比が９０％を超えると、成型物としての紙成分が少なくなるため、環境汚染の観点から好ましくなく、２０％未満であると、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られず、好ましくない。
【００３４】
前記のように構成される断熱性紙製成型物は、紙層１に熱可塑性高分子樹脂発泡層２が積層された成型素材３で成型されているので、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性が得られる。また、前記成型素材３を構成する紙層１の紙が、破断伸びが縦方向及び横方向共に１５％以上有するので、複雑な成型物を得ることができる。更には、この断熱性成型物の合成樹脂部分は前記熱可塑性高分子樹脂発泡層２だけなので、成型物全体が合成樹脂からなっている発泡ポリスチレン樹脂シートからなる成型物と較べ、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる。
【００３５】
次に前記第１例及び第２例に示す断熱性紙製成型物の製造方法の実施の形態の一例を説明する。
先ず、成型素材３としては、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１の一面側に、発泡剤を含む熱可塑性高分子樹脂層２ａが積層された成型素材３ａ（図３）又は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１の一面側に、発泡剤を含む熱可塑性高分子樹脂層２ａの一面側が積層され、この熱可塑性高分子樹脂層２ａの他面側に破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層１が積層された成型素材３ｂ（図４）が用いられる。
【００３６】
前記紙層１は、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙、いわゆる伸張紙からなる。前記紙は、その原料が針葉樹パルプまたは広葉樹パルプのいずれか一方または双方からなる天然パルプ１００％からなり、坪量が５０ｇ／ｍ２〜３００ｇ／ｍ２の範囲にあることが好ましい。坪量が５０ｇ／ｍ２未満であると、成型物の剛性不足や断熱性不足となり、好ましくない。また、坪量が３００ｇ／ｍ２を超えると、紙の絶対強度が高く、成型時の負荷が大きくなるため、経済的でない。
【００３７】
前記発泡剤を含む熱可塑性高分子樹脂層２ａの熱可塑性高分子樹脂としては、熱可塑性があれば特に限定されるものではないが、溶融温度、粘度、発泡特性等の点から一般的な生分解性樹脂、ポリスチレン系樹脂、アイオノマー樹脂、またはポリビニルアルコール、デンプン、カルボキシメチルセルロース等の水溶性高分子樹脂が好適である。
【００３８】
また、発泡剤としては、物理発泡剤や化学発泡剤等、公知の発泡剤が使用できるが、発泡層の形成性や、紙への積層が印刷機、塗工機または押出しラミネート機等の汎用設備を使用して行える等の観点から化学発泡剤、所謂熱分解型発泡剤が好適である。熱分解型発泡剤としては、重炭酸ナトリウム等の無機系分解型発泡剤、アゾジカーボンアミド、アゾビスイソブチロニトリル、ジアゾアミノベンゼン、ジニトロソペンタメチレンテトラミン等の有機系分解型発泡剤が使用できる。特に、分解温度のシャープ性、発生ガス量が多く少量の添加で高発泡倍率が得られる等から、アゾジカーボンアミドが好適である。
【００３９】
発泡剤を含む熱可塑性高分子樹脂層２ａは熱可塑性高分子樹脂と発泡剤の他、必要に応じて、可塑剤、耐水化剤、無機充填剤等が混合される。
【００４０】
前記熱可塑性高分子樹脂層２ａの重量比は前記紙層１の１００％に対して９０％〜２０％であることが好ましい。熱可塑性高分子樹脂層２ａの重量比が９０％を超えると、成型物としての紙成分が少なくなるため、環境汚染の観点から好ましくなく、２０％未満であると、断熱性、剛性、紙との接着性等の観点で所望の成型物が得られず、好ましくない。
【００４１】
前記紙層１に発泡剤を含む熱可塑性高分子樹脂層２ａを積層して成型素材３ａ，３ｂを得る方法としては、印刷機、塗工機または押出しラミネート機等の公知の方式を用いることができ、使用した発泡剤の熱分解温度以下の温度で行うことによって発泡剤を含む熱可塑性高分子樹脂層２ａを未発泡状態で紙層１に積層することができる。
【００４２】
前記のようにして得られた成型素材３ａ，３ｂを加熱し、前記熱可塑性高分子樹脂層２ａを発泡させた後、雄型と雌型からなる成型金型を有する成型機でプレスして所定の形状に成型し、成型物を得る。前記加熱温度にあっては、前記熱可塑性高分子樹脂層２ａの軟化温度＋２０℃以上であることが好ましい。前記加熱温度が、前記熱可塑性高分子樹脂層２ａの軟化温度＋２０℃以上であると、前記熱可塑性高分子樹脂層２ａを十分に発泡させることができるとともに、紙層と発泡した熱可塑性高分子樹脂層が接着し一体化した断熱性紙製成型物が得られる。前記加熱温度が、前記熱可塑性高分子樹脂層２ａの軟化温度＋２０℃未満であると、前記熱可塑性高分子樹脂層２ａを十分に発泡させることができず、また、紙層と発泡した熱可塑性高分子樹脂層を接着させ一体化することができない場合がある。
【００４３】
前記熱可塑性高分子樹脂層２ａは発泡倍率が３倍以上であることが好ましく、特に、５倍〜２０倍が望ましい。熱可塑性高分子樹脂層２ａの発泡倍率が３倍以下であると、断熱性や剛性が不足し好ましくなく、また２０倍以上では気泡が潰れ易く実用的でない。熱可塑性高分子樹脂層２ａの発泡後の厚さにあっては、発泡倍率や独立気泡率によって断熱特性が異なり、一概に特定することは難しいが、発泡後の厚さは１ｍｍ以上であることが望ましく、０．５ｍｍ〜３ｍｍの範囲が好適である。発泡後の厚さが０．５ｍｍより薄いと断熱特性が不十分であり、３ｍｍより厚くしても断熱特性はさして向上せず、しかも成型物の嵩が大きくなり、流通保管上経済的でない。ここでいう独立気泡率は、例えばＡＳＴＭ（米国材料試験協会規格） Ｄ ２８５６に規定された方法で測定することができ、発泡の独立気泡率が高いと熱の伝達速度が遅くなり、断熱特性が向上することが知られている。
【００４４】
なお、発泡倍率や厚さは、必要に応じて熱可塑性高分子樹脂と発泡剤の混合比や、これらの混合物の塗工厚みを任意に変えることで適宜調整することができる。
【００４５】
前記のようにして成型する成型物の形状は成型絞り率１２０％〜２００％の範囲であることが好ましい。成型絞り率が１２０％未満であると、成型物のデザインが限定され、複雑な形状の成型物が得られず、また、成型絞り率が２００％を超えると、紙層の伸びが追随できず、成型時に亀裂や破断の不具合を生じる場合がある。
【００４６】
前記成型絞り率は、次式によって算出した。
（成型物の表面積／成型物の開口面積）×１００＝成型絞り率
ここでいう成型物の開口面積とは、例えば一般的なトレー容器を想定した場合、トレーの開口部の面積を指し、凹状に成型された部分の全表面積を成型物の表面積とする。従って、同じ開口面積では凹状の深さによって全体の表面積が変わり、深くなるほど成型絞り率は増すことになる。
【００４７】
前記の製造方法では、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【００４８】
なお、本例では、成型素材３ａ，３ｂを加熱し、前記熱可塑性高分子樹脂層２ａを発泡させた後、雄型と雌型からなる金型を用いてプレスして所定の形状に成型し、成型物を得ているが、成型素材３ａ，３ｂを加熱して熱可塑性高分子樹脂層２ａを発泡させた後、加熱した金型を用いて成型するようにしてもよい。
【００４９】
また、発泡剤を含む熱可塑性高分子樹脂層２ａが積層された成型素材３ａ，３ｂを用い、加熱した金型を用いて前記熱可塑性高分子樹脂層２ａを発泡させながら成型してもよい。この場合の加熱温度にあっても、前記熱可塑性高分子樹脂層２ａの軟化温度＋２０℃以上であることが好ましい。
【００５０】
本発明で成型素材を金型を用いて成型するために使用される成型機としては、特に限定されるものではなく、プラスチック成型機として汎用されている圧空成型方式、真空成型方式及びプレス成型方式の成型機が好適に使用できる。
【００５１】
【実施例】
以下、本発明を実施例によって詳しく説明するが、本発明はこれに限定されるものではない。
（実施例１）
図３に示す紙層１として、天然パルプ１００％からなり、坪量２００ｇ／ｍ２、厚さ３００μｍ、破断伸びが縦方向２１．２％、横方向１６．２％の紙（イタリヤ国カリオラーロ社製）を用いた。一方、水溶性高分子樹脂のポリビニルアルコール樹脂（ＰＶＡ２１０：クラレ製）と化学発泡剤アゾジカーボンアミド（セルマイクＣ−１：三協化成製）と可塑剤グリセリン（一般薬品）と耐水化剤（スミレッツレジン６３６：住友化学製）と水とを、その配合比が２０／３／２０／１／８６（重量比）となるように塗料を調製し、この塗料を一般的なロール塗工装置にて乾燥重量約１５０ｇ／ｍ２の塗工層を上記紙層１の一方の面に積層した後、１０５℃の温度条件で乾燥し、紙層１に発泡剤を含む未発泡状態の熱可塑性高分子樹脂層２ａが積層されている坪量３５０ｇ／ｍ２、厚さ４４５μｍの２層構成の成型素材３ａを得た。
【００５２】
次いで、この成型素材３ａを２３０℃に加熱した図示しない予熱装置で予熱することにより、熱可塑性高分子樹脂層２ａを発泡させてから、雄型と雌型を有するプレス成型機で６ショット／分の成型速度でプレス成型し、図１に示す２層構造の断熱性紙製成型物を得た。
【００５３】
得られた断熱性紙製成型物の熱可塑性高分子樹脂発泡層２は、発泡倍率約８倍、厚さ約１．１ｍｍ、成型物の形状は図１に示すトレー形状（縦辺１１ｃｍ、横辺２１ｃｍ、テーパ角度４５°、深さ２．５ｃｍ）であり、成型絞り率は１２４．３％であった。
【００５４】
なお、成型絞り率は、以下のように算出した。
成型物の開口面積
縦辺１１ｃｍ×横辺２１ｃｍ＝２３１ｃｍ２
成型物の表面積
▲１▼底面積：縦辺６ｃｍ×横辺１６ｃｍ＝９６．０ｃｍ２
▲２▼縦辺側面（台形面積）：（長辺１１ｃｍ＋短辺６ｃｍ）×高さ２．５√２ｃｍ÷２の面積の面が２面あるので＝６０．１８ｃｍ２
▲３▼横辺側面（台形面積）：（長辺２１ｃｍ＋短辺１６ｃｍ）×高さ２．５√２ｃｍ÷２の面積の面が２面あるので＝１３０．９８ｃｍ２
▲１▼＋▲２▼＋▲３▼＝２８７．１６ｃｍ２
成型絞り率
２８７．１６ｃｍ２（表面積）÷２３１ｃｍ２（開口面積）×１００＝１２４ ．３％
得られた成型物は亀裂や破断による成型不良が全くなく、絞り皺のない美麗なトレー状成型物で経時後の型戻りや変形がなく熱可塑性高分子樹脂発泡層２と紙層１が積層一体化された剛性の高い成型物であった。また、得られた成型物に９５℃のお湯を入れ、外底面を持ったところ十分に持ち続けることができ、目的の断熱性が付与できた。
【００５５】
（実施例２）
実施例１と同様に紙層１の一方の面に積層した発泡剤を含む未発泡状態の熱可塑性高分子樹脂層２ａの他方の面に、天然パルプ１００％からなり、坪量２００ｇ／ｍ２、厚さ３００μｍ、破断伸びが縦方向２１．２％、横方向１６．２％の紙（イタリヤ国カリオラーロ社製）からなる紙層１を積層し、３層構成の成型素材３ｂを得た。
【００５６】
この成型素材３ｂを、２３０℃に加熱した雄型と雌型を有するプレス成型機で熱圧成型すると同時に、発泡剤を含む熱可塑性高分子樹脂層２ａの発泡と、紙層１への接着一体化を行うことによって、紙層１の一方の面に熱可塑性高分子樹脂発泡層２が積層され、この熱可塑性高分子樹脂発泡層２の他方の面に紙層１が積層された図２に示す３層構造の断熱性紙製成型物を得た。
【００５７】
得られた断熱性紙製成型物の熱可塑性高分子樹脂発泡層２は、発泡倍率約６倍、厚さ約０．８ｍｍ、成型物７の形状はトレー形状（縦辺１１ｃｍ、横辺２１ｃｍ、テーパ角度４５°、深さ２．５ｃｍ）であり、成型絞り率は１２４．３％であった。
【００５８】
得られた成型物は亀裂や破断による成型不良が全くなく、絞り皺のない美麗なトレー状成型物で経時後の型戻りや変形がなく、熱可塑性高分子樹脂発泡層２とその両面の紙層１，１の３層が積層一体化された剛性の高い成型物であった。また、得られた成型物に９５℃のお湯を入れ、外底面を持ったところ十分に持ち続けることができ、目的の断熱性が付与できた。
【００５９】
（実施例３）
紙層１として、坪量２７５ｇ／ｍ２、厚さ３９５μｍ、破断伸びが縦方向１９．８％、横方向１５．７％の紙（イタリヤ国カリオラーロ社製）を用い、実施の形態１と同様にして塗料を調製し、この塗料を乾燥重量約４０ｇ／ｍ２で紙層１の一方の面に積層し、紙層１に発泡剤を含む未発泡状態の熱可塑性高分子樹脂層２ａが積層されている坪量３１５ｇ／ｍ２、厚さ４３５μｍの２層構成の成型素材３ａを得た。次いで、この成型素材３ａを２３０℃に加熱した予熱装置で予熱することにより、熱可塑性高分子樹脂層２ａを発泡させてから、雄型と雌型の金型を有する成型機で６ショット／分の成型速度でプレス成型し、２層構成の断熱性紙製成型物を得た。
【００６０】
得られた断熱性紙製成型物の熱可塑性高分子樹脂発泡層２は、発泡倍率約８倍、厚さ約０．３ｍｍ、成型物の形状は図２に示したと同様のトレー形状（縦辺１１ｃｍ、横辺２１ｃｍ、テーパ角度４５°、深さ２．５ｃｍ）であり、成型絞り率は１２４．３％であった。
【００６１】
得られた成型物は亀裂や破断による成型不良が全くなく、絞り皺のない美麗なトレー状成型物で経時後の型戻りや変形がなく紙層１と熱可塑性高分子樹脂発泡層２の２層が積層一体化された剛性の高い成型物であった。また、得られた成型物に９５℃のお湯を入れ、外底面を持ったところやや熱さを感じたが、十分に持ち続けることができた。
【００６２】
（比較例１）
天然パルプ１００％からなり、坪量２００ｇ／ｍ２、厚さ３００μｍ、破断伸びが縦方向２１．２％、横方向１６．２％の紙（イタリヤ国カリオラーロ社製）からなる２枚の紙層の間に、５０μｍの低密度ポリエチレン樹脂フィルムを介在させ、２３０℃に加熱した雄型と雌型の金型を有するプレス成型機で実施例１〜３と同様のトレー形状に熱圧成型すると同時に、低密度ポリスチレンとその両面の紙との接着一体化を行い、３層構成の紙製成型物を得た。
【００６３】
得られた成型物は亀裂や破断による成型不良が全くなく、絞り皺のない美麗なトレー状成型物で経時後の型戻りや変形がなく紙同士が十分に接着一体化した成型物であった。しかし、成型物は剛性に劣り、また９５℃のお湯を入れ、外底面を持ったところ熱くて持ち続けることができず、殆ど断熱性のない成型物であった。
【００６４】
【表１】
【００６５】
【発明の効果】
以上のように、本発明に係る断熱性紙製成型物によれば、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、熱可塑性高分子樹脂発泡層が積層された成型素材で成型されてなるので、発泡ポリスチレン樹脂シートに匹敵する剛性、断熱性、緩衝性が得られ、また、前記成型素材を構成する紙層の紙が、破断伸びが縦方向及び横方向共に１０％以上有するので、複雑な成型物を得ることができ、更には、この断熱性成型物の合成樹脂部分は前記熱可塑性高分子樹脂発泡層だけなので、成型物全体が合成樹脂からなっている発泡ポリスチレン樹脂シートからなる成型物と較べ、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等を図ることができる。
【００６６】
また、本発明に係る断熱性紙製成型物の製造方法によれば、破断伸びが縦方向１０％以上、横方向１０％以上を有する紙層の一面側に、発泡剤を含む熱可塑性高分子樹脂層が積層された成型素材を用い、この成型素材を加熱し熱可塑性高分子樹脂層を発泡させた後、金型を用いて成型するので、発泡ポリスチレン樹脂シートに匹敵する断熱性、緩衝性があり、廃棄による環境汚染問題が少なく、焼却時の焼却炉の損傷防止、石油資源の節約等が図れる複雑な成型物を容易に得ることができ、そして、その成型にあっては、プラスチック成型に使用される一般的な成型機で成型できるので、かかる成型物を簡便且つ安価に得ることができる。
【図面の簡単な説明】
【図１】本発明に係る断熱性紙製成型物の実施の形態の第１例を示す断面図。
【図２】本発明に係る断熱性紙製成型物の実施の形態の第２例を示す断面図。
【図３】本発明で用いられる成型素材の一例を示す断面図。
【図４】本発明で用いられる成型素材の他例を示す断面図。
【符号の説明】
１ 紙層
２ 熱可塑性高分子樹脂発泡層
２ａ 熱可塑性高分子樹脂層
３，３ａ，３ｂ 成型素材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heat-insulating paper molded product mainly composed of paper and having heat-insulating properties and a method for producing the same, and in particular, has excellent heat-insulating and heat-retaining properties, rigidity, excellent buffering properties, and combustion energy and energy when incinerated as waste. The present invention relates to a molded article made of heat-insulating paper capable of reducing environmental pollution and a method for producing the same.
[0002]
[Prior art]
As a molded product having heat insulation, heat retention, rigidity, and cushioning properties, a food container molded by a hot-press molding machine using a foamed polystyrene resin sheet has been widely used. Paper cups and bowls composed mainly of paper from the viewpoint of preventing damage to incinerators and saving petroleum resources, for example, a composite in which crepe paper, corrugated paper, non-woven fabric, etc. are bonded to one side of a paper base material A mold container has been proposed (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-2002-173130 ([0009] stage)
[0004]
[Problems to be solved by the invention]
However, composites mainly composed of paper, for example, the above-mentioned crepe paper, corrugated paper, non-woven fabric, etc. bonded to a paper substrate are inherently inferior in elongation characteristics as compared to plastic substrates, and thus have complex shapes. A product cannot be obtained, and there is a problem in moldability. Further, paper cannot be molded by a general plastic molding machine, and there is a problem that a molding method is limited.
[0005]
Therefore, there is a demand for a heat-insulating paper molded product that can be easily formed into a three-dimensional curved shape similarly to plastic and that has heat insulating and heat retaining properties, and a manufacturing method that can obtain the molded product simply and inexpensively. .
[0006]
An object of the present invention is to obtain a heat-insulating paper molded product using paper having sufficient heat-insulating and buffering properties comparable to expanded polystyrene resin sheets.
Another object of the present invention is to provide a method for producing a heat-insulating paper molded product that can be molded using a conventional plastic molding machine.
[0007]
[Means for Solving the Problems]
The means of the present invention for achieving the above object will be described as follows.
The molded article made of heat-insulating paper according to claim 1, wherein a foamed thermoplastic polymer resin layer is laminated on one surface side of a paper layer having a breaking elongation of 10% or more in a vertical direction and 10% or more in a horizontal direction. It is characterized by being molded from a material.
[0008]
Since the heat-insulating paper molded product having such a configuration is molded from a molding material in which a thermoplastic polymer resin foam layer is laminated on a paper layer, the heat-insulating paper molded product has heat insulation and buffer properties comparable to foamed polystyrene resin sheets. . In addition, since the paper of the paper layer constituting the molding material has a breaking elongation of 10% or more in both the vertical and horizontal directions, a complicated molded product can be obtained. Furthermore, since the synthetic resin portion of this heat-insulating molded product is only the thermoplastic polymer resin foam layer, there is a problem of environmental pollution due to disposal compared to a molded product made of a foamed polystyrene resin sheet in which the entire molded product is made of a synthetic resin. It is possible to prevent damage to the incinerator during incineration and save petroleum resources.
[0009]
The molded article made of heat-insulating paper according to claim 2, wherein one surface of a foamed thermoplastic polymer resin layer is laminated on one surface of a paper layer having a breaking elongation of 10% or more in a vertical direction and 10% or more in a horizontal direction. It is characterized by being molded from a molding material in which a paper layer having a breaking elongation of 10% or more in the longitudinal direction and 10% or more in the horizontal direction is laminated on the other surface side of the thermoplastic polymer resin foam layer.
[0010]
Since the heat-insulating paper molded product having such a configuration is molded from a molding material in which a thermoplastic polymer foam layer is laminated on a paper layer, sufficient heat insulation and cushioning properties comparable to foamed polystyrene resin sheets are obtained. There is. In addition, since the paper of the paper layer constituting the molding material has a breaking elongation of 10% or more in both the vertical and horizontal directions, a complicated molded product can be obtained. Furthermore, since the synthetic resin portion of this heat-insulating molded product is only the thermoplastic polymer resin foam layer, there is a problem of environmental pollution due to disposal compared to a molded product made of a foamed polystyrene resin sheet in which the entire molded product is made of a synthetic resin. It is possible to prevent damage to the incinerator during incineration and save petroleum resources.
[0011]
The molded article made of heat insulating paper according to claim 3, wherein the weight of the thermoplastic polymer resin foam layer according to claim 1 is 90% to 20% of the weight of the paper layer. %.
[0012]
When the weight ratio of the foamed thermoplastic polymer resin layer is 90% to 20% with respect to 100% of paper, a desired molded product can be obtained from the viewpoint of heat insulation, rigidity, adhesion to paper, and the like. . If the weight ratio of the thermoplastic polymer resin foam layer exceeds 90%, the paper component as a molded product is reduced, which is not preferable from the viewpoint of environmental pollution. If the weight ratio is less than 20%, heat insulation, rigidity, and adhesion to paper are reduced. A desired molded product cannot be obtained from the viewpoint of properties and the like, which is not preferable.
[0013]
According to a fourth aspect of the present invention, there is provided a heat-insulating paper molded product, wherein the thermoplastic polymer resin constituting the thermoplastic polymer resin foam layer according to any one of the first to third aspects is made of green paper. It is a degradable resin or a water-soluble polymer resin.
[0014]
As described above, when the thermoplastic polymer resin constituting the foamed thermoplastic polymer resin layer is a biodegradable resin or a water-soluble polymer resin, there is little problem of environmental pollution due to disposal, and the incinerator at the time of incineration is used. In addition to preventing damage to oil and saving petroleum resources, biodegradable resins can be easily decomposed by burying them in the soil. Since the paper forming the layer can be collected, the volume of waste can be reduced in any case.
[0015]
The method for producing a heat-insulating paper molded product according to claim 5, wherein a thermoplastic polymer resin containing a foaming agent is provided on one surface side of a paper layer having a breaking elongation of 10% or more in a vertical direction and 10% or more in a horizontal direction. The method is characterized by using a molding material in which layers are laminated, heating the molding material to foam the thermoplastic polymer resin layer, and then molding using a mold.
[0016]
With such a configuration, it has heat insulation and buffer properties comparable to foamed polystyrene resin sheets, has less environmental pollution problems due to disposal, can prevent damage to the incinerator during incineration, and can easily produce complex molded products that can save petroleum resources. Since it can be obtained and can be molded by a general molding machine used for plastic molding, such a molded product can be obtained simply and inexpensively.
[0017]
The method for producing a heat-insulating paper molded product according to claim 6, wherein the thermoplastic polymer resin contains a foaming agent on one surface side of a paper layer having a breaking elongation of 10% or more in a vertical direction and 10% or more in a horizontal direction. It is characterized in that the thermoplastic polymer resin layer is molded while being foamed using a heated mold by using a molding material in which the layers are laminated.
[0018]
With such a configuration, it has heat insulation and buffer properties comparable to foamed polystyrene resin sheets, has less environmental pollution problems due to disposal, can prevent damage to the incinerator during incineration, and can easily produce complex molded products that can save petroleum resources. Since it can be obtained and can be molded by a general molding machine used for plastic molding, such a molded product can be obtained simply and inexpensively.
[0019]
The method for producing a heat-insulating paper molded product according to claim 7, wherein the thermoplastic polymer resin contains a foaming agent on one surface side of a paper layer having a breaking elongation of 10% or more in a vertical direction and 10% or more in a horizontal direction. Using a molding material in which one side of the layer is laminated, and a paper layer having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction is laminated on the other surface of the thermoplastic polymer resin layer containing the foaming agent, The molding material is heated to foam the thermoplastic polymer resin layer, and then molded using a mold.
[0020]
With such a configuration, it has sufficient rigidity, heat insulation and cushioning properties comparable to foamed polystyrene resin sheets, has few environmental pollution problems due to disposal, prevents damage to incinerators during incineration, and complicates molding that can save petroleum resources. The molded product can be easily obtained, and can be molded by a general hot-press molding machine used for plastic molding, so that the molded product can be obtained simply and inexpensively.
[0021]
The method for producing a heat-insulating paper molded product according to claim 8, wherein the thermoplastic polymer resin containing a foaming agent on one surface side of a paper layer having a breaking elongation of 10% or more in a longitudinal direction and 10% or more in a lateral direction. Using a molding material in which one side of the layer is laminated, and a paper layer having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction is laminated on the other surface of the thermoplastic polymer resin layer containing the foaming agent, The method is characterized in that the thermoplastic polymer resin layer is molded while being foamed using a heated mold.
[0022]
With such a configuration, there is sufficient heat insulation and buffering properties comparable to foamed polystyrene resin sheets, there are few environmental pollution problems due to disposal, prevention of damage to the incinerator at incineration, saving of petroleum resources, etc. Since it can be easily obtained and can be molded by a general hot-press molding machine used for plastic molding, such a molded product can be obtained simply and inexpensively.
[0023]
The method for producing a heat-insulating paper molded product according to claim 9, wherein the weight of the thermoplastic polymer resin layer according to any one of claims 5 to 8 is 90% of the weight of the paper layer. -20%.
[0024]
When the weight ratio of the thermoplastic polymer resin layer is 90% to 20% with respect to 100% of paper, a desired molded product can be obtained from the viewpoints of heat insulation, rigidity, adhesion to paper, and the like. If the weight ratio of the thermoplastic polymer resin layer exceeds 90%, the paper component as a molded product is reduced, which is not preferable from the viewpoint of environmental pollution. In view of the above, a desired molded product cannot be obtained, which is not preferable.
[0025]
The method for producing a heat-insulating paper molded product according to claim 10 is characterized in that the thermoplastic polymer resin constituting the thermoplastic polymer resin layer according to any one of claims 5 to 9 is used. , A biodegradable resin or a water-soluble polymer resin.
[0026]
As described above, when the thermoplastic polymer resin constituting the thermoplastic polymer resin layer is a biodegradable resin or a water-soluble polymer resin, there is little problem of environmental pollution due to disposal, and the incinerator at the time of incineration is used. In addition to preventing damage and saving petroleum resources, biodegradable resins can be easily decomposed by burying them in the soil. In any case, the volume of waste can be reduced.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example of an embodiment of a heat insulating paper molded product and a method for manufacturing the same according to the present invention will be described.
First, an embodiment of a heat insulating paper molded product will be described.
FIG. 1 shows a first example of an embodiment of a heat-insulating paper molded product. In this example, the elongation at break is 10% or more in the longitudinal direction and 10% or more in the horizontal direction. It is molded with a molding material 3 in which a thermoplastic polymer foam layer 2 is laminated.
[0028]
FIG. 2 shows a second example of the embodiment of the heat-insulating paper molded product. In this example, the elongation at break is 10% or more in the longitudinal direction and 10% or more in the horizontal direction. One side of the thermoplastic polymer foam layer 2 is laminated, and the paper layer 1 having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction is laminated on the other surface of the thermoplastic polymer resin foam layer 2. It is molded with the molded material 3.
[0029]
Since the paper layer 1 and the foamed thermoplastic polymer layer 2 constituting the molding material 3 shown in the first and second examples are common, they will be described without distinction.
The paper layer 1 constituting the molding material 3 is made of a paper having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction, that is, a so-called stretched paper. The paper is made of 100% natural pulp whose raw material is one or both of softwood pulp and hardwood pulp, and has a basis weight of 50 g / m2.2~ 300g / m2Is preferably within the range. Basis weight 50g / m2If the amount is less than the above, the rigidity of the molded product becomes insufficient and the heat insulating property becomes insufficient. In addition, the basis weight is 300 g / m2If it exceeds, the absolute strength of the paper is high and the load at the time of molding becomes large, so that it is not economical.
[0030]
The thermoplastic polymer foam layer 2 is formed by foaming a thermoplastic polymer resin layer containing a foaming agent. The thermoplastic polymer resin is not particularly limited as long as it has thermoplasticity, but is generally a biodegradable resin, a polystyrene-based resin, an ionomer resin, or the like in terms of melting temperature, viscosity, foaming characteristics, or the like. Water-soluble polymer resins such as polyvinyl alcohol, starch and carboxymethyl cellulose are preferred.
[0031]
As the foaming agent, known foaming agents such as a physical foaming agent and a chemical foaming agent can be used. However, a foaming layer can be formed and lamination on paper can be performed by a general-purpose machine such as a printing machine, a coating machine or an extrusion laminating machine. A chemical foaming agent, a so-called thermal decomposition type foaming agent, is preferable from the viewpoint that it can be performed using equipment. The thermal decomposition type foaming agent used is an inorganic decomposition type foaming agent such as sodium bicarbonate, and an organic decomposition type foaming agent such as azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, dinitrosopentamethylenetetramine. it can. In particular, azodicarbonamide is preferable because the sharpness of the decomposition temperature, the large amount of generated gas, and the high expansion ratio can be obtained by adding a small amount.
[0032]
In the thermoplastic polymer resin layer containing a foaming agent, in addition to the thermoplastic polymer resin and the foaming agent, a plasticizer, a waterproofing agent, an inorganic filler, and the like are mixed as necessary.
[0033]
The weight ratio of the thermoplastic polymer foam layer 2 is preferably 90% to 20% with respect to 100% of the paper layer 1. If the weight ratio of the thermoplastic polymer resin foam layer 2 exceeds 90%, the paper component as a molded product is reduced, which is not preferable from the viewpoint of environmental pollution. If the weight ratio is less than 20%, heat insulation, rigidity, paper A desired molded product cannot be obtained from the viewpoint of adhesiveness to the adhesive, and this is not preferred.
[0034]
Since the heat-insulating paper molded product configured as described above is molded with the molding material 3 in which the thermoplastic polymer foam layer 2 is laminated on the paper layer 1, the heat insulation paper is comparable to the foamed polystyrene resin sheet. Properties and buffering properties are obtained. Further, since the paper of the paper layer 1 constituting the molding material 3 has a breaking elongation of 15% or more in both the vertical and horizontal directions, a complicated molded product can be obtained. Further, since the synthetic resin portion of the heat-insulating molded article is only the thermoplastic polymer resin foam layer 2, environmental pollution due to disposal is lower than that of a molded article made of a foamed polystyrene resin sheet in which the entire molded article is made of a synthetic resin. There are few problems, and damage to the incinerator during incineration, saving of petroleum resources, etc. can be achieved.
[0035]
Next, an example of the embodiment of the method for manufacturing the heat insulating paper molding shown in the first and second examples will be described.
First, as a molding material 3, a molding material 3a in which a thermoplastic polymer resin layer 2a containing a foaming agent is laminated on one surface side of a paper layer 1 having a breaking elongation of 10% or more in a longitudinal direction and 10% or more in a lateral direction. (FIG. 3) Alternatively, one surface of a thermoplastic polymer resin layer 2a containing a foaming agent is laminated on one surface of a paper layer 1 having a breaking elongation of 10% or more in a longitudinal direction and 10% or more in a lateral direction. A molding material 3b (FIG. 4) is used in which a paper layer 1 having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction is laminated on the other surface side of the polymer resin layer 2a.
[0036]
The paper layer 1 is made of paper having a breaking elongation of 10% or more in a longitudinal direction and 10% or more in a horizontal direction, that is, a so-called stretched paper. The paper is made of 100% natural pulp whose raw material is one or both of softwood pulp and hardwood pulp, and has a basis weight of 50 g / m2.2~ 300g / m2Is preferably within the range. Basis weight 50g / m2If the amount is less than the above, the rigidity of the molded product becomes insufficient and the heat insulating property becomes insufficient. In addition, the basis weight is 300 g / m2If it exceeds, the absolute strength of the paper is high and the load at the time of molding becomes large, so that it is not economical.
[0037]
The thermoplastic polymer resin of the thermoplastic polymer resin layer 2a containing the foaming agent is not particularly limited as long as it has thermoplasticity. A decomposable resin, a polystyrene resin, an ionomer resin, or a water-soluble polymer resin such as polyvinyl alcohol, starch, and carboxymethyl cellulose are preferable.
[0038]
As the foaming agent, known foaming agents such as a physical foaming agent and a chemical foaming agent can be used. However, a foaming layer can be formed and lamination on paper can be performed by a general-purpose machine such as a printing machine, a coating machine or an extrusion laminating machine. A chemical foaming agent, a so-called thermal decomposition type foaming agent, is preferable from the viewpoint that it can be performed using equipment. Examples of the thermal decomposition type foaming agent include inorganic decomposition type foaming agents such as sodium bicarbonate, and organic decomposition type foaming agents such as azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, and dinitrosopentamethylenetetramine. Can be used. In particular, azodicarbonamide is preferable because the sharpness of the decomposition temperature, the large amount of generated gas, and the high expansion ratio can be obtained by adding a small amount.
[0039]
In the thermoplastic polymer resin layer 2a containing a foaming agent, a plasticizer, a waterproofing agent, an inorganic filler, and the like are mixed as necessary in addition to the thermoplastic polymer resin and the foaming agent.
[0040]
Preferably, the weight ratio of the thermoplastic polymer resin layer 2a is 90% to 20% with respect to 100% of the paper layer 1. If the weight ratio of the thermoplastic polymer resin layer 2a exceeds 90%, the paper component as a molded product is reduced, which is not preferable from the viewpoint of environmental pollution. If the weight ratio is less than 20%, heat insulation, rigidity, paper and However, a desired molded product cannot be obtained from the viewpoint of adhesiveness and the like, which is not preferable.
[0041]
As a method of laminating the thermoplastic polymer resin layer 2a containing a foaming agent on the paper layer 1 to obtain the molding materials 3a and 3b, a known method such as a printing machine, a coating machine or an extrusion laminating machine may be used. By carrying out at a temperature lower than the thermal decomposition temperature of the used foaming agent, the thermoplastic polymer resin layer 2a containing the foaming agent can be laminated on the paper layer 1 in an unfoamed state.
[0042]
After heating the molding materials 3a and 3b obtained as described above to foam the thermoplastic polymer resin layer 2a, the material is pressed by a molding machine having a molding die composed of a male mold and a female mold, and pressed. To obtain a molded product. The heating temperature is preferably equal to or higher than the softening temperature of the thermoplastic polymer resin layer 2a plus 20 ° C. When the heating temperature is equal to or higher than the softening temperature of the thermoplastic polymer resin layer 2a + 20 ° C., the thermoplastic polymer resin layer 2a can be sufficiently foamed and the thermoplastic polymer foamed with the paper layer A heat-insulating paper molded product in which the resin layer is bonded and integrated is obtained. When the heating temperature is lower than the softening temperature of the thermoplastic polymer resin layer 2a + 20 ° C., the thermoplastic polymer resin layer 2a cannot be sufficiently foamed, and the thermoplastic polymer foamed with the paper layer cannot be foamed. In some cases, the polymer resin layer cannot be bonded and integrated.
[0043]
The expansion ratio of the thermoplastic polymer resin layer 2a is preferably 3 times or more, and more preferably 5 times to 20 times. If the expansion ratio of the thermoplastic polymer resin layer 2a is 3 times or less, heat insulation and rigidity are insufficient, which is not preferable. If it is 20 times or more, bubbles are easily crushed, which is not practical. Regarding the thickness of the thermoplastic polymer resin layer 2a after foaming, the heat insulation properties vary depending on the foaming ratio and the closed cell rate, and it is difficult to specify it unconditionally, but the thickness after foaming must be 1 mm or more. And a range of 0.5 mm to 3 mm is preferable. When the thickness after foaming is less than 0.5 mm, the heat insulating properties are insufficient, and when the thickness is more than 3 mm, the heat insulating properties do not improve much, and the bulk of the molded product becomes large, which is not economical in distribution storage. The closed cell ratio referred to here can be measured, for example, by a method specified in ASTM (American Society for Testing and Materials) D2856. If the closed cell ratio of foaming is high, the heat transfer speed becomes slow, and the heat insulating property becomes poor. It is known to improve.
[0044]
The expansion ratio and the thickness can be appropriately adjusted by arbitrarily changing the mixing ratio of the thermoplastic polymer resin and the blowing agent and the coating thickness of the mixture as needed.
[0045]
The shape of the molded product to be molded as described above is preferably in the range of 120% to 200%. When the molding draw ratio is less than 120%, the design of the molded product is limited, and a molded product having a complicated shape cannot be obtained. When the mold drawing ratio exceeds 200%, the elongation of the paper layer cannot follow. In some cases, cracks or breakage may occur during molding.
[0046]
The molding draw ratio was calculated by the following equation.
(Surface area of molded article / opening area of molded article) x 100 = Mold drawing ratio
The opening area of the molded product here refers to the area of the opening of the tray when a general tray container is assumed, for example, and the total surface area of the concavely molded portion is defined as the surface area of the molded product. Therefore, for the same opening area, the entire surface area changes depending on the concave depth, and the deeper the molding, the greater the drawing reduction ratio.
[0047]
In the above-mentioned manufacturing method, there is a heat insulating property comparable to the expanded polystyrene resin sheet, there is a buffer property, there are few environmental pollution problems due to disposal, prevention of damage to the incinerator at the time of incineration, a complicated molded product that can save oil resources and the like. Since it can be easily obtained and can be molded by a general molding machine used for plastic molding, such a molded product can be obtained simply and inexpensively.
[0048]
In this example, after the molding materials 3a and 3b are heated to foam the thermoplastic polymer resin layer 2a, the molding materials 3a and 3b are pressed into a predetermined shape using a male and female mold. Although the molded product is obtained, the molding materials 3a and 3b may be heated to foam the thermoplastic polymer resin layer 2a, and then molded using a heated mold.
[0049]
Alternatively, the thermoplastic polymer resin layer 2a may be molded while foaming the thermoplastic polymer resin layer 2a using a heated mold using molding materials 3a and 3b in which the thermoplastic polymer resin layer 2a containing a foaming agent is laminated. In this case, the heating temperature is preferably equal to or higher than the softening temperature of the thermoplastic polymer resin layer 2a plus 20 ° C.
[0050]
The molding machine used for molding the molding material by using a mold in the present invention is not particularly limited, and a pressure molding method, a vacuum molding method, and a press molding method, which are widely used as a plastic molding machine. Molding machine can be suitably used.
[0051]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.
(Example 1)
The paper layer 1 shown in FIG. 3 is made of 100% natural pulp and has a basis weight of 200 g / m.2Paper having a thickness of 300 μm, a breaking elongation of 21.2% in a longitudinal direction and a 16.2% in a lateral direction (manufactured by Cariolarro, Italy) was used. On the other hand, a polyvinyl alcohol resin (PVA210: Kuraray) as a water-soluble polymer resin, a chemical foaming agent azodicarbonamide (Celmic C-1: manufactured by Sankyo Chemical Co., Ltd.), a plasticizer glycerin (general chemical) and a waterproofing agent (Sumi Let's resin 636: manufactured by Sumitomo Chemical Co., Ltd.) and water to prepare a coating such that the mixing ratio is 20/3/20/1/86 (weight ratio), and apply this coating to a general roll coating apparatus. About 150g / m dry weight2Is laminated on one surface of the paper layer 1 and then dried under a temperature condition of 105 ° C., and an unfoamed thermoplastic polymer resin layer 2 a containing a foaming agent is laminated on the paper layer 1. 350 g / m2Thus, a molding material 3a having a thickness of 445 μm and having a two-layer structure was obtained.
[0052]
Next, the molding material 3a is preheated by a preheating device (not shown) heated to 230 ° C. to foam the thermoplastic polymer resin layer 2a, and then is subjected to 6 shots / minute by a press molding machine having a male mold and a female mold. Press molding was performed at a molding speed of 1 to obtain a heat insulating paper molded product having a two-layer structure shown in FIG.
[0053]
The foamed thermoplastic polymer resin layer 2 of the obtained heat-insulating paper molded article has an expansion ratio of about 8 times, a thickness of about 1.1 mm, and a molded article having a tray shape (11 cm long, 11 cm long) shown in FIG. The width was 21 cm, the taper angle was 45 °, and the depth was 2.5 cm), and the molding reduction ratio was 124.3%.
[0054]
In addition, the molding drawing ratio was calculated as follows.
Opening area of molded product
11cm length x 21cm width = 231cm2
Surface area of molded product
(1) Bottom area: 6 cm (vertical side) x 16 cm (horizontal side) = 96.0 cm2
{Circle around (2)} Vertical side (trapezoidal area): (long side 11 cm + short side 6 cm) × height 2.5√2 cm ÷ 2 because there are two faces = 60.18 cm2
{Circle around (3)} Lateral side surface (trapezoidal area): (long side 21 cm + short side 16 cm) × height 2.5√2 cm の 2 because there are two faces = 130.98 cm2
(1) + (2) + (3) = 287.16cm2
Mold drawing ratio
287.16 cm2(Surface area) $ 231cm2(Opening area) × 100 = 124. 3%
The obtained molded product has no molding failure due to cracks or breakage, and is a beautiful tray-shaped molded product without drawing wrinkles, without mold return or deformation after a lapse of time. The thermoplastic polymer foam layer 2 and the paper layer 1 are laminated. It was an integrated, highly rigid molded product. In addition, hot water at 95 ° C. was put into the obtained molded product, and when the outer bottom surface was held, it was possible to keep it sufficiently, and the desired heat insulating property was imparted.
[0055]
(Example 2)
In the same manner as in Example 1, the other surface of the unfoamed thermoplastic polymer resin layer 2a containing a foaming agent laminated on one surface of the paper layer 1 is made of 100% natural pulp and has a basis weight of 200 g / m2.2Then, a paper layer 1 made of paper (manufactured by Cariolarro, Italy) having a thickness of 300 μm, a breaking elongation of 21.2% in the longitudinal direction and a 16.2% in the transverse direction was laminated to obtain a molding material 3b having a three-layer structure.
[0056]
The molding material 3b is hot-pressed by a press molding machine having a male mold and a female mold heated to 230 ° C., and at the same time, the foaming of the thermoplastic polymer resin layer 2a containing the foaming agent and the bonding to the paper layer 1 are integrated. FIG. 2 shows that the thermoplastic polymer foam layer 2 is laminated on one surface of the paper layer 1 and the paper layer 1 is laminated on the other surface of the thermoplastic polymer resin layer 2. A heat-insulating paper molded product having the three-layer structure shown was obtained.
[0057]
The foamed thermoplastic polymer resin layer 2 of the obtained heat-insulating paper molded product has a foaming ratio of about 6 times, a thickness of about 0.8 mm, and a molded article 7 having a tray shape (11 cm long, 21 cm wide). , A taper angle of 45 °, and a depth of 2.5 cm), and a molding reduction ratio of 124.3%.
[0058]
The obtained molded product is a beautiful tray-shaped molded product having no molding defects due to cracks and breaks, no drawing wrinkles, no mold return or deformation after a lapse of time, and a thermoplastic polymer resin foam layer 2 and paper on both surfaces thereof. It was a highly rigid molded product in which three layers, layers 1 and 1, were laminated and integrated. In addition, hot water at 95 ° C. was put into the obtained molded product, and when the outer bottom surface was held, it was possible to keep it sufficiently, and the desired heat insulating property was imparted.
[0059]
(Example 3)
As the paper layer 1, a basis weight of 275 g / m2A paint was prepared in the same manner as in Embodiment 1 using paper (manufactured by Cariolarro, Italy) having a thickness of 395 μm, a breaking elongation of 19.8% in a longitudinal direction and a 15.7% in a transverse direction, and drying the paint. Weight about 40g / m2And a non-foamed thermoplastic polymer resin layer 2a containing a foaming agent is laminated on the paper layer 1 with a basis weight of 315 g / m.2Thus, a molding material 3a having a thickness of 435 μm and having a two-layer structure was obtained. Next, the molding material 3a is preheated by a preheating device heated to 230 ° C. to foam the thermoplastic polymer resin layer 2a, and is then shot at 6 shots / minute by a molding machine having a male mold and a female mold. Press molding at a molding speed of 2 to obtain a two-layer heat insulating paper molded product.
[0060]
The foamed thermoplastic polymer resin layer 2 of the obtained molded article made of heat insulating paper has a foaming ratio of about 8 times, a thickness of about 0.3 mm, and the molded article has the same tray shape as shown in FIG. (Side 11 cm, side 21 cm, taper angle 45 °, depth 2.5 cm), and the molding draw ratio was 124.3%.
[0061]
The obtained molded product has no molding defects due to cracks and breaks, and is a beautiful tray-shaped molded product without drawing wrinkles. It was a highly rigid molded product in which the layers were integrated. In addition, hot water of 95 ° C. was put into the obtained molded product, and although the outer bottom surface was slightly heated, it was possible to keep it sufficiently.
[0062]
(Comparative Example 1)
Consists of 100% natural pulp, basis weight 200g / m2A 50 μm low-density polyethylene resin film is interposed between two paper layers made of paper (manufactured by Cariolarro, Italy) having a thickness of 300 μm, a breaking elongation of 21.2% in a longitudinal direction and a 16.2% in a lateral direction. At the same time, hot-press molding to the same tray shape as in Examples 1 to 3 using a press molding machine having a male mold and a female mold heated to 230 ° C., and simultaneously bonding the low-density polystyrene with the paper on both sides thereof Then, a three-layer paper molded product was obtained.
[0063]
The resulting molded article was a beautiful tray-shaped molded article with no molding defects due to cracks and breaks, no drawing wrinkles, no mold return or deformation after a lapse of time, and was a molded article in which papers were sufficiently bonded and integrated. . However, the molded product was inferior in rigidity, was hot at 95 ° C., had an outer bottom surface, was hot and could not be held, and had almost no heat insulation.
[0064]
[Table 1]
[0065]
【The invention's effect】
As described above, according to the heat-insulating paper molded product according to the present invention, the thermoplastic polymer foam layer is provided on one surface side of the paper layer having a breaking elongation of 10% or more in the vertical direction and 10% or more in the horizontal direction. Since it is molded from a laminated molding material, rigidity, heat insulating properties and cushioning properties comparable to foamed polystyrene resin sheets are obtained, and the paper of the paper layer constituting the molding material has a breaking elongation in the longitudinal direction. And 10% or more in both lateral directions, so that a complicated molded product can be obtained. Furthermore, since the synthetic resin portion of this heat insulating molded product is only the thermoplastic polymer foam layer, the entire molded product is made of synthetic resin. As compared with a molded article made of a foamed polystyrene resin sheet made of, there are less environmental pollution problems due to disposal, and it is possible to prevent damage to the incinerator during incineration, save petroleum resources, and the like.
[0066]
Further, according to the method for producing a heat-insulating paper molded product according to the present invention, a thermoplastic layer containing a foaming agent is provided on one surface side of a paper layer having a breaking elongation of 10% or more in the longitudinal direction and 10% or more in the horizontal direction. Using a molding material with a molecular resin layer laminated, heating this molding material to foam the thermoplastic polymer resin layer, and then molding using a mold, heat insulation and buffering comparable to foamed polystyrene resin sheet It is possible to easily obtain complex molded products that have low environmental pollution problems due to disposal, prevent incinerator damage during incineration, save petroleum resources, etc. Since molding can be performed by a general molding machine used for molding, such a molded product can be obtained simply and inexpensively.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first example of an embodiment of a heat-insulating paper molded product according to the present invention.
FIG. 2 is a sectional view showing a second example of the embodiment of the heat-insulating paper molded product according to the present invention.
FIG. 3 is a sectional view showing an example of a molding material used in the present invention.
FIG. 4 is a sectional view showing another example of a molding material used in the present invention.
[Explanation of symbols]
1 Paper layer
2 Thermoplastic polymer resin foam layer
2a Thermoplastic polymer resin layer
3,3a, 3b molding material
