JP4016303B2 - Expandable styrenic resin particles and foam molded products using the same - Google Patents

Description

【００１５】
（式中、Ｒ_fはＣ_nＦ_2n+1 で表されるフッ化アルキル基（ｎは１〜１６の整数）、Ｒ₁は水素または炭素数１〜１８のアルキル基、Ｒ₂は炭素数１〜１０のアルキレン基、Ｒ₃は水素又はメチル基をそれぞれ示す。）
【００１６】
【化５】

【００１７】
（式中、Ｒ₄は水素又はメチル基、Ｒ₅は炭素数１〜４のアルキレン基、Ｒ₆は炭素数は１〜４のアルキル基をそれぞれ示す。）
【００１８】
このように一部に親水性高分子を含んで発泡性スチレン系樹脂粒子を構成することにより、親水性高分子であるプルランが接着剤の役目を果たすとともに、含フッ素ビニル重合体がより効率的に撥油性を発揮することができるためと推定されるが、優れた内容物の遮蔽性を保持したまま、浸透性が高い油性の内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透するおそれが著しく少なくなる。
【００１９】
ここで、プルランとは、オウレオバシヂウムプルラン（Ａｕｒｅｏｂａｓｉｄｉｕｍ ｐｕｌｌｕｌａｎｓ）によって生成される水溶性の菌体外多糖類であり、グルコピラノース残基を有する水溶性の線状グルカンと定義される。
【００２０】
また、発泡性スチレン系樹脂粒子を構成するにあたり、被覆物中において、含フッ素ビニル系共重合体１００重量部に対して、プルランを５〜１５０重量部の割合で含むことが好ましい。
【００２１】
このような範囲でプルランを被覆物中に含むことにより、親水性成分や油成分の浸透をより効率的に防止することができる。したがって、発泡性スチレン系樹脂粒子を、浸透性が高い油性の内容物あるいは乳化剤成分と油脂成分が混在する油性の内容物に対する容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透するおそれが少ない。
また、このようなプルランの使用量であれば、予備加熱時には、発泡性スチレン系樹脂粒子同士が凝集して集塊化するおそれが少ない一方、成形加熱時には、プルランが接着剤としての役目を果たし、優れた融着性を示すことが可能となる。
したがって、内容物の遮蔽性および生産性の効率とのバランスに優れている観点から、被覆物中におけるプルランの使用量を、含フッ素ビニル系共重合体１００重量部に対して、１０〜１３０重量部の範囲内の値とするのがより好ましく、最適には５０〜１２０重量部の範囲内の値とすることである。
【００２２】
また、発泡性スチレン系樹脂粒子を構成するにあたり、含フッ素ビニル系共重合体が、下記式（３）で表されるビニル系単量体（第２のビニル系単量体）をさらに含んで重合させて得られたものであることが好ましい。
【００２３】
【化６】

【００２４】
（式中、Ｒ₇は水素又はメチル基、Ｒ₈は炭素数１〜４のアルキレン基、Ｒ₉およびＲ₁₀は炭素数１〜４のアルキル基をそれぞれ示す。）
【００２５】
このように第２のビニル系単量体を含むことにより、含フッ素ビニル系共重合体の分子量や極性の制御が容易となり、発泡性スチレン系樹脂粒子本体への密着性や加熱成形時の発泡性スチレン系樹脂粒子同士の融着性を調製することができる。
【００２６】
また、本発明の発泡性スチレン系樹脂粒子を構成するにあたり、プルランの平均分子量を５００〜１００、０００の範囲内の値とするのが好ましい。
プルランの平均分子量（重量平均分子量）がこのような範囲内の値であれば、当該プルラン自身の耐熱性が高くなり、また、発泡性スチレン系樹脂粒子本体に対するプルランの密着力がより向上するためである。したがって、浸透性が高い、比較的高温の油性の内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透することがより少なくなる。さらには、プルランの平均分子量がこのような範囲内の値であれば、成形加熱時に、発泡性スチレン系樹脂粒子の融着を阻害するおそれもより少ないためである。
したがって、内容物の遮蔽性および生産性の効率とのバランスがより優れている観点から、プルランの平均分子量を、８００〜１０、０００の範囲内の値とするのがより好ましく、最適には１、０００〜５、０００の範囲内の値とすることである。
【００２７】
また、本発明の発泡性スチレン系樹脂粒子を構成するにあたり、プルランを濃度１〜３０重量％の水溶液として使用することが好ましい。
含フッ素ビニル系共重合体は油性であり、親水性のプルランとは一般に相溶性に乏しいため、それぞれをそのまま混合しても時間が経過すると分離してしまうおそれがある。しかるに、使用するプルランが、このような濃度の水溶液であれば、かかる混合分離の問題が生じず、任意の量で以て、含フッ素ビニル系共重合体とプルランとを均一に混合することができる。
【００２８】
また、本発明のプルランが、グルコピラノース残基を３個含むマルトトリオース単位、あるいは、当該マルトトリオース単位をさらに複数個含む構造単位を有していると、当該プルランにおいて、より効率的に粘性や接着性を発現することができる。
【００２９】
また、本発明の発泡性スチレン系樹脂粒子を構成するにあたり、プルランとしてエステル化されたプルラン、エーテル化されたプルランあるいは水添されたプルランの少なくとも一つを使用することが好ましい。
このようにプルランを反応させることにより、当該プルランの耐熱性を向上させたり、あるいは、当該プルランの水溶性を調節することができる。
【００３０】
また、発泡性スチレン系樹脂粒子を構成するにあたり、使用する含フッ素ビニル系共重合体が、水系エマルション（水系エマルジョンと称する場合もある。）であることが好ましい。
前述したとおり、含フッ素ビニル系共重合体は油性であり、親水性のプルランとは一般に相溶性に乏しいため、そのまま混合しても時間が経過すると分離してしまうおそれがある。しかるに、使用する含フッ素ビニル系共重合体が、水系エマルションであれば、かかる混合分離の問題が生じず、任意の量で以て、含フッ素ビニル系共重合体とプルランとを均一に混合することができる。
【００３１】
また、発泡性スチレン系樹脂粒子を構成するにあたり、被覆物（含フッ素ビニル系共重合体およびプルランを含む）の被覆量を、発泡性スチレン系樹脂粒子本体１００重量部に対して、０．００６〜０．５重量部の範囲内の値とするのが好ましい。
被覆物の被覆量がこのような範囲内の値であれば、より効率的に油成分等の浸透を防止して、浸透性が高い油性の内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透するおそれがより少なくなる。また、このような範囲の被覆量であれば、より短時間で成形可能な発泡性スチレン系樹脂粒子及び発泡成形品を提供することが可能となる。
したがって、内容物の遮蔽性および生産性の効率とのバランスにより優れている観点から、被覆物の被覆量を、発泡性スチレン系樹脂粒子本体１００重量部に対して、０．０１５〜０．２５重量部の範囲内の値とするのがより好ましい。
【００３２】
また、発泡性スチレン系樹脂粒子を構成するにあたり、プルランの被覆量を、発泡性スチレン系樹脂粒子本体１００重量部に対して、０．００１〜０．１重量部の範囲内の値とするのが好ましい。
プルランの被覆量がこのような範囲内の値であれば、より効率的に油成分等の浸透を防止して、浸透性が高い油性の内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透するおそれがより少なくなる。また、このような範囲の被覆量であれば、より短時間で成形可能な発泡性スチレン系樹脂粒子及び発泡成形品を提供することが可能となる。
したがって、内容物の遮蔽性および生産性の効率とのバランスにより優れている観点から、プルランの被覆量を、発泡性スチレン系樹脂粒子本体１００重量部に対して、０．００５〜０．０５重量部の範囲内の値とするのがより好ましい。
【００３３】
また、発泡性スチレン系樹脂粒子を構成するにあたり、含フッ素ビニル系共重合体の被覆量を、前記発泡性スチレン系樹脂粒子本体１００重量部に対して、０．００５〜０．３重量部の範囲内の値とするのが好ましい。
含フッ素ビニル系共重合体の被覆量がこのような範囲内の値であれば、より効率的に撥油性を発揮して油成分等の浸透を防止して、浸透性が高い油性の内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透するおそれがより少なくなる。また、このような範囲の被覆量であれば、成形時の発泡性スチレン系樹脂粒子同士の融着を阻害するおそれがより少なくなる。
したがって、内容物の遮蔽性および生産性の効率とのバランスにより優れている観点から、含フッ素ビニル系共重合体の被覆量を、発泡性スチレン系樹脂粒子本体１００重量部に対して、０．０１〜０．２重量部の範囲内の値とするのがより好ましい。
【００３４】
また、本発明の別な態様は、上記発泡性スチレン系樹脂粒子を発泡成形して得られる発泡成形品である。
プルランを含む発泡性スチレン系樹脂粒子から成形した発泡成形品は、一部の浸透性が高い内容物における容器等に使用した場合であっても、収容される内容物が容器外壁または成形品内部へ浸透することが少なく、かつ短時間で成形することが可能である。
【００３５】
また、本発明の発泡成形品を加熱成形するにあたり、発泡性スチレン系樹脂粒子を、加熱温度が９０〜１５０℃、加熱時間が１〜６０秒の条件で発泡成形するのが好ましい。
このような加熱成形条件であれば、内容物の遮蔽性と生産性の効率とのバランスに優れた発泡成形品を製造することができる。
したがって、内容物の遮蔽性と生産性の効率とのバランスにより優れた発泡成形品を製造することができる観点から、加熱温度を１００〜１４０℃とし、加熱時間を２〜１０秒の範囲内の値とするのがより好ましく、最適には、加熱温度を１２０〜１４０℃とし、加熱時間を３〜５秒の範囲内の値とすることである。
【００３６】
【発明の実施の形態】
以下、本発明の実施の形態を具体的に説明する。すなわち、含フッ素ビニル系単量体とビニル系単量体とを重合させて得られる含フッ素ビニル系共重合体及びプルランを含んでなる被覆物を、発泡性スチレン系樹脂粒子本体の表面に被覆してなる本発明の発泡性スチレン系樹脂粒子において、以下のような、発泡性スチレン系樹脂粒子、含フッ素ビニル系共重合体、プルラン等を使用して、発泡成形品を加熱成形することができる。
【００３７】
１．発泡性スチレン系樹脂粒子
本発明の発泡性スチレン系樹脂粒子は、発泡性樹脂粒子本体の表面に対して、所定の含フッ素ビニル系重合体等を被覆材（被覆層を含む。）として被覆することにより得られるものである。
【００３８】
（１）発泡性スチレン系樹脂粒子本体
発泡性スチレン系樹脂粒子本体は、上述のようにスチレン系樹脂粒子に、発
泡剤を含浸させることにより調製することができる。
【００３９】
１）スチレン系樹脂粒子
スチレン系樹脂粒子としては、特に制限はないが、例えばスチレンホモポリ
マー、またはスチレンモノマーと共重合可能な成分、例えばアクリロニトリル、メタクリル酸メチル、メタクリル酸ブチル等のメタクリル酸エステル類、アクリル酸メチル、アクリル酸エチル、アクリル酸ブチル等のアクリル酸エステル類、α−メチルスチレン、クロルスチレン、ビニルトルエン等のスチレン誘導体のモノマーなどとスチレンモノマーとの一種または二種以上の共重合体を挙げることができる。
また、当該スチレン系樹脂粒子の粒子径についても特に制限されるものではないが、例えば、平均粒子径が０．８〜０．２５ｍｍの範囲内の値であるスチレン系樹脂粒子を使用するのが好ましい。このような範囲内のスチレン系樹脂粒子であれば、適度に発泡して緻密な成形品とすることができる。
【００４０】
２）発泡剤の種類
発泡剤の種類としては、特に制限はないが、例えばプロパン、ブタン、ペンタン、ヘキサン等の脂肪族炭化水素、またはフレオン１１、フレオン１２等のフロン系化合物などの常温で液体または気体状の化合物を挙げることができる。
３）発泡剤の含浸方法および含浸量
発泡剤の含浸方法としては、特に制限はなく、従来一般的に使用されてきた方法を採用することができる。また、スチレン系樹脂粒子への発泡剤の含浸量を１〜１０重量％の範囲内の値とすることが好ましい。このような範囲で以て発泡剤を含浸すれば、発泡性スチレン系樹脂粒子（スチレン系樹脂粒子）を適度に発泡させて緻密な成形品とすることができる。
【００４１】
２．含フッ素ビニル系共重合体
含フッ素ビニル系共重合体として、下記式（１）で示される含フッ素ビニル系単量体と、下記式（２）で示されるビニル系単量体（第１のビニル系単量体と称する。）とを重合して得られる共重合体（二成分系）を用いても良く、あるいは、式（１）で示される含フッ素ビニル系単量体と、式（２）で示されるビニル系単量体（第１のビニル系単量体）と、下記式（３）で示されるビニル系単量体（第２のビニル系単量体と称する。）とを重合して得られる共重合体（三成分系）等を用いてもよい。
【００４２】
（１）含フッ素ビニル系単量体
含フッ素ビニル系単量体は、下記式（１）で示される化合物が用いられる。
【００４３】
【化７】

【００４４】
（式中、Ｒ_fはＣ_nＦ_2n+1 で表されるフッ化アルキル基（ｎは１〜１６の整数）、Ｒ₁は水素または炭素数１〜１８のアルキル基、Ｒ₂は炭素数１〜１０のアルキレン基、Ｒ₃は水素又はメチル基をそれぞれ示す。）
【００４５】
このような含フッ素ビニル系単量体としては、具体的に以下のものが挙げられる。
Ｃ₈F₁₇ＳＯ₂-Ｎ（ＣＨ₃）−ＣＨ₂ＣＨ₂ＯＣＯＣＨ＝ＣＨ₂
Ｃ₈F₁₇ＳＯ₂-Ｎ（ＣＨ₃）−ＣＨ₂ＣＨ₂ＯＣＯＣ（ＣＨ₃）＝ＣＨ₂
Ｃ₈F₁₇ＳＯ₂-Ｎ（Ｃ₂Ｈ₅）−ＣＨ₂ＣＨ₂ＯＣＯＣＨ＝ＣＨ₂
Ｃ₈F₁₇ＳＯ₂-Ｎ（Ｃ₂Ｈ₅）−ＣＨ₂ＣＨ₂ＯＣＯＣ（ＣＨ₃）＝ＣＨ₂
【００４６】
（２）ビニル系単量体（第１のビニル系単量体）
第１のビニル系単量体としては、下記式（２）で示される化合物が用いられる。
【００４７】
【化８】

【００４８】
（式中、Ｒ₄は水素又はメチル基、Ｒ₅は炭素数１〜４のアルキレン基、Ｒ₆は炭素数１〜４のアルキル基をそれぞれ示す。）
【００４９】
このような第１のビニル系単量体としては、具体的に以下のものを挙げることができる。
ＣＨ₂=ＣＨ−ＣＯＯＣ₂Ｈ₄ＯＣＨ₃
ＣＨ₂=Ｃ（ＣＨ₃）−ＣＯＯＣ₂Ｈ₄ＯＣＨ₃
ＣＨ₂=ＣＨ−ＣＯＯＣ₂Ｈ₄ＯＣ₂Ｈ₅
ＣＨ₂=Ｃ（ＣＨ₃）−ＣＯＯＣ₂Ｈ₄ＯＣ₂Ｈ₅
【００５０】
（３）ビニル系単量体（第２のビニル系単量体）
第２のビニル系単量体は、下記式（３）で示される化合物が用いられる。
【００５１】
【化９】

【００５２】
（式中、Ｒ₇は水素又はメチル基、Ｒ₈は炭素数１〜４のアルキレン基、Ｒ₉およびＲ₁₀炭素数１〜４のアルキル基をそれぞれ示す。）
【００５３】
このような第２のビニル系単量体としては、具体的に以下に示すものを挙げることができる。
ＣＨ₂=ＣＨ−ＣＯＯＣ₂Ｈ₄Ｎ（ＣＨ₃）₂
ＣＨ₂=Ｃ（ＣＨ₃）−ＣＯＯＣ₂Ｈ₄Ｎ（ＣＨ₃）₂
【００５４】
（４）重合割合
式（１）で示される含フッ素ビニル系単量体と、式（２）で示されるビニル系単量体（第１のビニル系単量体）とを重合して得られる含フッ素ビニル系共重合体（二成分系）の場合、全体量を１００重量％としたときに、含フッ素ビニル系単量体の重合割合を４０〜９５重量％の範囲内の値、および第１のビニル系単量体の重合割合を５〜５０重量％の範囲内の値とするのが好ましい。
含フッ素ビニル系単量体の重合割合が９５重量％を越えると、加熱成形時における発泡性スチレン系樹脂粒子の熱融着を阻害する傾向があり、一方、４０重量％未満となると、発泡成形品としたときに、十分な撥水、撥油性を付与することが困難となる傾向がある。
したがって、かかる成形性と撥水、撥油性とのバランスがより良好な観点から、全体量を１００重量％としたときに、含フッ素ビニル系単量体の重合割合を５０〜８０重量％の範囲内の値、および第１のビニル系単量体の重合割合を２０〜５０重量％の範囲内の値とするのがより好ましい。
【００５５】
また、式（１）で示される含フッ素ビニル系単量体と、式（２）で示されるビニル系単量体（第１のビニル系単量体）と、式（３）で示されるビニル系単量体（第２のビニル系単量体）を重合して得られる含フッ素ビニル系共重合体（三成分系）の場合、全体量を１００重量％としたときに、含フッ素ビニル系単量体の重合割合を５０〜８５重量％の範囲内の値、第１のビニル系単量体の重合割合を５〜４０重量％の範囲内の値、第２のビニル系単量体の重合割合を１〜１０重量％の範囲内の値とするのが好ましい。
第２のビニル系単量体の重合割合が１０重量％を越えると、発泡性スチレン系樹脂粒子への付着性が低下する傾向があり、一方、１重量％未満となると、撥水性等の発現が不十分となる傾向がある。
したがって、かかる成形性と撥水、撥油性とのバランスがより良好な観点から、含フッ素ビニル系単量体の重合割合を５０〜８０重量％の範囲内の値、第１のビニル系単量体の重合割合を５〜４０重量％の範囲内の値、第２のビニル系単量体の重合割合を１〜１０重量％の範囲内の値とするのがより好ましい。
【００５６】
（５）重合方法
本発明における含フッ素ビニル系共重合体の重合方法としては、特に制限はないが、例えば溶液重合、乳化重合等を挙げることができる。また、重合に用いられる重合開始剤としては、溶液重合においては過酸化ラウロイル、過酸化ベンゾイル、ｔ−ブチルパーオキシイソブチレート、ｔ−ブチルパ−オキシピバレート等を挙げることができる。また、乳化重合に於いては、過硫酸カリウム、過硫酸アンモニウム等を挙げることができる。
【００５７】
（６）含フッ素ビニル系共重合体の性状
前述したとおり、含フッ素ビニル系共重合体が、使用する際に水系エマルション（水系エマルジョンと称する場合もある。）であることが好ましい。水系エマルションであれば、プルランとの混合分離の問題が生じず、含フッ素ビニル系共重合体とプルランとを均一に混合することができるためである。
【００５８】
３．プルラン
（１）プルランの種類
本発明に使用できるプルランは、商業的に入手できるものをそのまま使用することができ、例えば、林原生化学研究所製プルランＰＦ−２０を使用することができる。そして、上述したとおり、平均分子量が５００〜１００、０００の範囲内のプルランを使用するのが好ましい。
また、上述したとおり、エステル化されたプルラン、エーテル化されたプルランあるいは水添されたプルランが好ましい。
【００５９】
さらに、プルランの形態として特に制限されるものではないが、濃度１〜３０重量％の水溶液とするのが好ましい。そして、作業性が良好な観点から、当該プルランの濃度５重量％の水溶液粘度が、１〜１００センチポイズ（ｃｐ）の範囲内の値、より好ましくは１０〜８０センチポイズ（ｃｐ）の範囲内の値である。
また、加熱成形時の発泡性スチレン系樹脂粒子同士の融着性がより良好な観点から、プルランのガラス転移点を、３０〜１００℃の範囲内の値とするのが好ましく、より好ましくは、４０〜８０℃の範囲内の値である。
【００６０】
なお、プルランのガラス転移点を調整したり、柔軟性を改良したり、あるいは含フッ素ビニル系単量体との混合性をより良好とするために、添加剤として、グリセリン、エチレングリコール、ＤＢＰ（ジブチルフタレート）、ＤＯＰ（ジオクチルフタレート）、アルギン酸アミド、アクリルアミド、澱粉、ＣＭＣ、メチルセルロース、グリオキサゾール、ジメチロール尿素等の一つまたは二つ以上を添加することができる。
【００６１】
（２）プルランの使用方法
プルランは、含フッ素ビニル系単量体と混合後に発泡性スチレン系樹脂粒子本体に対して被覆処理することも可能であるし、また、含フッ素ビニル系単量体とは別に、単独で発泡性スチレン系樹脂粒子本体に対して被覆処理することも好ましい。含フッ素ビニル系単量体と混合後に被覆処理することにより、一度の操作で発泡性スチレン系樹脂粒子本体に対して被覆処理することができる点で好ましく、一方、単独で発泡性スチレン系樹脂粒子本体に対して被覆処理することにより、含フッ素ビニル系単量体との分離による濃度むらが生じるおそれが少なくなる点で好ましい。
【００６２】
４．その他の被覆剤
発泡性スチレン系樹脂粒子本体の被覆においては、前述の共重合体のほかに従来公知の被覆剤を併用することができる。例えば、一次発泡における集塊化防止のため使用されるステアリン酸亜鉛、ステアリン酸カルシュウムなどの金属石鹸エチレンビスアミド、ステアリン酸アミドのような高級脂肪酸アミドを挙げることができる。これらの集塊化防止剤は発泡性スチレン系樹脂粒子本体１００重量部に対し０．０５〜０．５重量部の範囲内で使用することが好ましい。中でも集塊化防止効果に特に優れており、また安価で経済的観点からステアリン酸亜鉛が好ましい。
【００６３】
また成形工程においてこの発泡性スチレン系樹脂粒子本体の融着促進効果のある添加剤も使用可能である。かかる物質としては従来公知のものが使用できる。例えばステアリン酸グリセライド、オレイン酸グリセライドなどの高級脂肪酸のトリエステル、ジエステル、モノエステル類、蔗糖エステル類等の１種または２種以上が使用できる。
【００６４】
さらに、一次発泡性スチレン系樹脂粒子本体の静電防止剤として使用されるグリセリン、ソルビトール、ポリエチレングリコール、ポリプロピレングリコール等の多価アルコール類、ソルビタンエステル、高級脂肪酸のエチレングリコール付加物等のノニオン系界面活性剤の、１種または２種以上の併用も可能である。これら静電防止剤は発泡性スチレン系樹脂粒子本体１００重量部に対し０．００５〜０．２重量部の範囲内で使用することが好ましい。
【００６５】
５．被覆物（被覆層）の形成
本発明における発泡性スチレン系樹脂粒子本体の表面への含フッ素ビニル系共重合体およびプルランの被覆の形成方法は、特に制限はなく従来既知の手段で行なうことができる。
例えば、リボンブレンダー、Ｖ形ブレンダー、ヘンシェルミキサー、レディゲミキサー等の混合機を用い、室温、１００〜１０、０００ｒｐｍの回転数、および１０秒〜１時間の撹拌時間の条件で、発泡性スチレン系樹脂粒子本体、含フッ素ビニル系共重合体、プルラン及び前述の被覆剤各成分等をそれぞれ混合することによって被覆形成することができる。
但し、発泡性スチレン系樹脂粒子本体、含フッ素ビニル系共重合体、プルラン及び前述の被覆剤各成分等をそれぞれ個別に層状に被覆形成することもできる。
【００６６】
６．発泡成形品
本発明の発泡成形品は、前述の発泡性スチレン系樹脂粒子を成形することによって得ることができる。すなわち、上述した発泡性スチレン系樹脂粒子を使用することにより、短い成形加熱時間で以て、発泡粒子同士が強固に融着しかつその粒子界面が優れた撥油性を有する発泡成形品を得ることができる。
ここで、具体的な成形加熱条件は特に制限されるものではないが、前述したとおり、金型等を用いて、加熱温度が９０〜１５０℃、加熱時間が１〜６０秒の条件で以て発泡成形するのが好ましい。従って、このように本発明の発泡成形品を製造すれば、例えば発泡成形品（容器）内に、ラ−ド、即席ラ−メン類、カレ−ルウ、マヨネ−ズ、マ−ガリン等の浸透性の高い油性及び脂肪性の食品あるいは機械油等を直接包装あるいは収容しても、当該発泡成形品を構成する発泡性スチレン系樹脂粒子間から容器外へ油脂等が浸透するのを有効に防止することができ、発泡成形品の製品寿命を長くすることも可能となる。
【００６７】
【実施例】
以下実施例によって本発明をさらに詳細に説明するが、当該実施例は本発明の一例を示すのみであり、本発明はこれらの記載に制限されるものではない。
【００６８】
［実施例１］
（１）試料の作製
発泡剤として５．５重量％のペンタン（ｉｓｏ―ペンタン／n―ペンタンの重量比＝３０／７０）を含む平均粒子径（直径）０．３５〜０．６０ｍｍの発泡性ポリスチレン粒子（日立化成工業社製ハイビーズ５ＳＧ）２０００ｇをヘンシェルミキサーに入れた。
次いで、５００〜１０００ｒｐｍの回転数で以て攪拌しながらステアリン酸亜鉛（表１中、成分３）６ｇ、シュガーエステル（第一工業製薬社製Ａ−１０Ｅ）（表１中、成分４）０．４ｇ、グリセリン（表１中、成分５）０．４ｇ、濃度５重量％の溶液粘度が２０ｃｐであるプルラン水溶液を、固形分として（表１中、成分２）０．４ｇ、および含フッ素ビニル系共重合体（表１中、成分１）の２０％水性エマルション２．２ｇ（含フッ素ビニル系共重合体の固形分０．４ｇ）を順次加えた。
【００６９】
なお、含フッ素ビニル系共重合体（表１中、成分１）を構成する単量体の種類および割合は以下のとおりである。
Ｃ₈F₁₇ＳＯ₂-Ｎ（ＣＨ₃)−ＣＨ₂ＣＨ₂ＯＣＯＣＨ＝ＣＨ₂ ６５重量％
ＣＨ₂=Ｃ（ＣＨ₃）−ＣＯＯＣ₂Ｈ₄ＯＣ₂Ｈ₅ ３０重量％
ＣＨ₂=ＣＨ−ＣＯＯＣ₂Ｈ₄Ｎ（ＣＨ₃）₂ ５重量％
【００７０】
それから、約９０秒間撹拌を続けた後、撹拌を止めて、原料溶液とした。次いで、バッチ式一次発泡装置を用い、当該固形分を熱風とスチームの混合気を熱媒として嵩密度１０ｍｌ／ｇになるよう発泡させ、一次発泡樹脂粒子を得た。
その後、この一次発泡樹脂粒子を常温、常圧下で１６時間熟成したのち、内容積５００ｃｃ、肉厚２．０ｍｍの成形品を得るための金型に充填した。それから、加熱温度１４０℃、加熱時間４秒の条件で以て発泡成形品（カップ）を加熱成形した。
なお、このとき加熱時間以外に、原料充填時間、金型を室温から加熱温度（１４０℃）に到達するまでの予備加熱時間、および、発泡成形品を取り出すために金型を所定温度以下まで冷却する必要があるが、そのための時間を別途、約８秒要した。
【００７１】
（２）性能評価
１）融着度の測定
発泡成形品（カップ）を手で以て割り、破断面を露出させた。それから、当該破断面を光学顕微鏡で観察し、単位面積当たりの凝集破壊している部分の面積割合を融着度（％）として測定した。なお、発泡性スチレン系樹脂粒子同士が良好に融着している場合には、破断面において凝集破壊している部分が多くなり、逆に発泡性スチレン系樹脂粒子同士の融着が不十分な場合には、粒子界面で破壊されることとなる。
【００７２】
２）界面活性剤の遮蔽性テスト
加速試験として界面活性剤に対する遮蔽性テストを行った。すなわち、界面活性剤水溶液（花王社製スコアロール７００、濃度０．１重量％）を約３００ｇ入れたのち、当該カップをサラン樹脂製ラッッピングフィルムで包装した。そして、このように包装したカップを、６０℃雰囲気下のオーブンに放置し、カップの外壁に界面活性剤水溶液が浸透してくるまでの時間（表１中、浸透時間１で表す。以下同様である。）を測定した。
【００７３】
３）油脂成分の遮蔽性テスト
油脂成分に対する遮蔽性の確認として、得られた発泡成形品（カップ）にカレールウ２００ｇを入れたのち、当該カップをサラン樹脂製ラッッピングフィルムで包装した。そして、このように包装したカップを、６０℃雰囲気下のオーブン中に放置し、カップの外壁にカレールウが浸透してくるまでの時間（表１中、浸透時間２で表す。以下同様である。）を測定した。それぞれの測定結果を表１に示した。
【００７４】
この結果から明らかなように、加熱時間が４秒と極端に短いにもかかわらず、融着度は８０％とかなり高い値を示した。また、乳化剤成分としての界面活性剤の浸透時間１は５０分、油脂成分としてのカレールウの浸透時間２は２４時間と、実用的に全く問題がないレベルであった。
したがって、本発明の発泡性スチレン系樹脂粒子は、発泡成形品（カップ）に成形した場合に、浸透性の高い内容物であっても、当該内容物が発泡成形品の外壁まで浸透する時間（浸透時間）を著しく長くして、水性成分の内容物に対する浸透時間と同等かそれ以上の浸透時間を得ることができ、また、本発明の発泡性スチレン系樹脂粒子は短時間で以て発泡成形品を加熱成形することが可能であることが確認された。
【００７５】
［実施例２および３］
実施例１において、加熱成形時間を、５秒（実施例２）および６秒（実施例３）にした以外は、実施例１と同様の条件で以て発泡成形品（カップ）を得た。そして、実施例１と同様に性能評価を行った。
【００７６】
それぞれの測定結果を表１に示す。この結果から明らかなように、加熱時間が５秒および６秒と若干長くなったため、融着度は１００％と最高値を示した。
また、界面活性剤の浸透時間１は６０分以上（５および６秒加熱）、油脂成分としてのカレールウの浸透時間２は４８時間（５秒加熱）あるいは７２時間（６秒加熱）と、極めて優れた遮蔽性を示した。
したがって、本発明の発泡性スチレン系樹脂粒子は、上述したように、加熱時間が４秒でも発泡成形品（カップ）として、実用的に十分な内容物の遮蔽性と発泡成形品の加熱成形性とを得ることができるが、より長い加熱時間（５または６秒加熱）を採ることにより、さらに優れた内容物の遮蔽性と、発泡成形品の加熱成形性とが得られることが確認された。
【００７７】
［実施例４および５］
実施例１におけるプルラン（表１中、成分２）の、発泡性ポリスチレン粒子１００重量部当たりの使用量を、０．０２重量部から、０．００５重量部に変更し、０．０２重量部添加したグリセリンの代わりにポリエチレングリコールを成分５（表１中）として０．０１重量部添加した以外は、実施例１〜２と同様の条件で以てそれぞれ発泡成形品（カップ）を得た。そして、実施例１と同様に性能評価を行った。
【００７８】
それぞれの測定結果を表１に示す。この結果から明らかなように、プルランの使用量を減少させると、加熱時間が４秒の場合の融着度は９０％であり、加熱時間が５秒の場合の融着度は１００％であった。すなわち、融着度に関しては、プルランの使用量が少ないほうが、より良好な結果が得られる傾向が見られた。
それに対して、界面活性剤の浸透時間１は、加熱時間が４秒の場合に４０分であり、加熱時間が５秒の場合には６０分であった。また、油脂成分としてのカレールウの浸透時間２としては、２４時間（４秒加熱および５秒加熱）という長い値を示した。
したがって、内容物の遮蔽性に関しては、プルランが大きく寄与しており、プルランの使用量が少なくなると、当該遮蔽性は低下する傾向が見られた。
【００７９】
［実施例６および７］
実施例１における含フッ素ビニル系共重合体（表１中、成分１）の、発泡性ポリスチレン粒子１００重量部当たりの使用量を０．０２重量部から、０．０３重量部に変更し、また、グリセリンの代わりにポリエチレングリコール（三洋化成（株）製、ＰＥＧ−４００）を成分５（表１中）として添加した以外は、実施例１〜２と同様の条件で以てそれぞれ発泡成形品（カップ）を得た。そして、実施例１〜２と同様に性能評価を行った。それぞれの測定結果を表１に示した。
【００８０】
この結果から明らかなように、グリセリンの代わりにポリエチレングリコールを用いた場合にも、グリセリンを用いた場合と同様に、優れた内容物の遮蔽性と、発泡成形品の加熱成形性とが得られることが確認された。
【００８１】
［実施例８〜９］
実施例１の含フッ素ビニル系共重合体に代わりに、市販の含フッ素ビニル系共重合体（米国スリーエム（株）製、スコッチバンＦＸ−８４５）を成分１（表１中）として用いた以外は、実施例１〜３と同様の条件で以てそれぞれ発泡成形品（カップ）を得た。そして、実施例１〜３と同様に性能評価を行った。測定結果を表１に示す。
なお、スコッチバンＦＸ−８４５は、実施例１〜７で使用した含フッ素ビニル系共重合体に相当するものであることが、ＦＴ−ＩＲ、ＮＭＲ、ＧＣ−ＭＳの測定から判明している。
【００８２】
この結果から明らかなように、市販の含フッ素ビニル系共重合体を用いた場合にも、優れた内容物の遮蔽性と、発泡成形品の加熱成形性とが得られることが確認された。
【００８３】
［比較例１〜３］
実施例１〜３において、それぞれプルランのみを除いて発泡性スチレン系樹脂粒子としたこと以外は実施例１〜３と同様の条件で以て発泡成形品（カップ）を得た。そして、実施例１〜３と同様に性能評価を行った。それぞれの測定結果を表１に示した。
【００８４】
この結果から明らかなように、プルランを全く使用しない場合でも、加熱時間が４秒の場合の融着度は８０％であり、加熱時間が５秒および６秒の場合の融着度はそれぞれ１００％であった。すなわち、融着度に関しては、プルランを使用しない場合であっても、使用した場合と大差ない結果が得られる傾向が見られた。
それに対して、界面活性剤の浸透時間１は、加熱時間が４秒の場合に２０分であり、加熱時間が５秒の場合には４５分であり、加熱時間が６秒の場合に６０分であった。また、油性成分としてのカレールウの浸透時間２は、加熱時間が４秒の場合に４時間未満であり、加熱時間が５秒の場合には８時間であり、加熱時間が６秒の場合であっても２４時間であった。したがって、内容物の遮蔽性に関しては、プルランが大きく寄与しており、プルランを使用しないと、当該遮蔽性は著しく低下する傾向が見られた。
【００８５】
［比較例４〜６］
実施例１〜３において、それぞれ含フッ素共重合体のみを除いて発泡性スチレン系樹脂粒子としたこと以外は実施例１〜３と同様の条件で以て発泡成形品（カップ）を得た。そして、実施例１〜３と同様に性能評価を行った。それぞれの測定結果を表１に示した。
【００８６】
この結果から明らかなように、特定の含フッ素共重合体を使用しない場合、加熱時間が４秒において、融着度は８０％であり、加熱時間が５秒および６秒の場合の融着度はそれぞれ１００％であった。すなわち、融着度に関しては、特定の含フッ素共重合体を使用しない場合であっても、使用した場合と大差ない結果が得られる傾向が見られた。
それに対して、界面活性剤の浸透時間１は、加熱時間が４秒および５秒の場合に２０分であり、加熱時間が６秒の場合であっても３０分であった。また、油性成分としてのカレールウの浸透時間２は、加熱時間が４秒および５秒の場合に４時間未満であり、加熱時間が６秒の場合であっても２４時間であった。
したがって、内容物の遮蔽性に関しては、特定の含フッ素共重合体の存在が大きく寄与しており、当該特定の含フッ素共重合体を使用しないと、内容物の遮蔽性は著しく低下する傾向が見られた。
【００８７】
［比較例７〜９］
実施例１〜３において、それぞれ含フッ素共重合体およびプルランを除いて発泡性スチレン系樹脂粒子としたこと以外は実施例１〜３と同様の条件で以て発泡成形品（カップ）を得た。そして、実施例１〜３と同様に性能評価を行った。それぞれの測定結果を表１に示した。
【００８８】
この結果から明らかなように、特定の含フッ素共重合体およびプルランを使用しない場合でも、加熱時間が４秒において、融着度は８０％であり、加熱時間が５秒および６秒の場合の融着度はそれぞれ１００％であった。
すなわち、融着度に関しては、特定の含フッ素共重合体およびプルランを使用しない場合であっても、使用した場合と大差ない結果が得られる傾向が見られた。
それに対して、界面活性剤の浸透時間１は、加熱時間が４秒の場合に１０分であり、加熱時間が５秒の場合に１５分であり、加熱時間が６秒の場合であっても３０分であった。また、油性成分としてのカレールウの浸透時間２は、加熱時間が４秒および５秒の場合に４時間未満であり、加熱時間が６秒の場合であっても４時間であった。
したがって、内容物の遮蔽性に関しては、特定の含フッ素共重合体およびプルランの存在が大きく寄与しており、当該特定の含フッ素共重合体およびプルランをそれぞれ使用しないと、内容物の遮蔽性は著しく低下する傾向が見られた。
【００８９】
【表１】

【００９０】
【発明の効果】
本発明により、発泡成形品（カップ）を成形した場合に、浸透性の高い内容物であっても、当該内容物が発泡成形品の外壁まで浸透する時間（浸透時間）を著しく長くすることができるようになった。そして、特にカレールウのような浸透性の高い内容物に対しても優れた遮蔽性を示し、当該内容物を著しく長い間保持することができるようになった。
また、このように発泡性スチレン系樹脂粒子を構成することにより、上記の優れた遮蔽性を有しながら、当該発泡性スチレン系樹脂粒子の生産性を損なうことがないことが確認された。
よって、本発明により、浸透性の高い内容物の遮蔽性と加熱成形性とのバランスに優れた発泡性スチレン系樹脂粒子及び発泡成形品を提供することが出来るようになった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to expandable styrenic resin particles and a foam molded article using the same. More specifically, the present invention relates to an expandable styrene resin particle suitable for use as a container for a highly permeable content, for example, a content in which an emulsifier component and an oil and fat component are mixed, and a foam molded product using the same.
[0002]
[Prior art]
In general, expandable styrenic resin particles (sometimes simply referred to as resin particles) are pre-expanded with steam or the like to form pre-expanded particles, and the pre-expanded particles are filled into a mold having small holes. By heating again, it can be molded into a predetermined shape. The molded article thus obtained exhibits excellent properties such as economy, light weight, and hygiene, and is used in many fields as a packaging material, a heat insulating material, a container, and the like.
[0003]
Here, the expandable styrenic resin particles are obtained by dispersing a foaming agent (generally a liquid or gaseous aliphatic hydrocarbon such as propane, butane, pentane, hexane, etc. at room temperature) in an aqueous medium together with the styrenic resin particles, It is produced by a method of impregnating a foaming agent into particles or a method of impregnating a foaming agent in an aqueous suspension containing a small amount of a solvent such as toluene or cyclohexane having solubility in styrene resin particles. And the expandable styrene resin particle obtained in this way is shape | molded through the above-mentioned process.
[0004]
However, since the obtained molded product is obtained by stacking expandable styrene resin particles on a stone wall and fusing them with foaming pressure and heat, the resin particles may not be integrated. As a result, when used as a container, the contents may permeate into the outer wall of the container or the inside of the molded product depending on the type of contents to be stored.
In order to prevent such contents from penetrating, a method for minimizing the voids in the molded article that becomes the way when the contents penetrate the inside of the container, and the surface energy of the particle surface is reduced. Thus, it is possible to generally adopt a method of increasing the contact angle of the surface of the molded product with respect to the permeating contents.
[0005]
In general, the former method is to strengthen the heating conditions during molding. In order to obtain a molded product with fewer defects, the molding temperature is set lower and the expandable styrene resin particles are longer. The method of heating for hours is taken.
However, this method requires a long time for molding and heating the expandable styrenic resin particles, and it is difficult to say that it is a useful method in the molding industry because the productivity is significantly reduced.
[0006]
On the other hand, as the latter method, the amount of metal soap (carboxylate) generally used for preventing agglomeration of expandable styrene resin particles in the pre-foaming is increased. ing.
However, even in this method, it is necessary to lengthen the molding heating time in order not to exhibit the property of inhibiting the fusion of the expandable styrene resin particles due to the metal soap, and it is difficult to say that this is an industrially useful method. .
[0007]
Accordingly, various foamable styrene resin particles with less permeability of the contents have been proposed with a shorter molding heating time.
For example, in Japanese Examined Patent Publication No. 56-34172, expandable styrenic resin particles whose surface is coated with sucrose ester or a derivative thereof are used. In JP-A-2-88652, a specific perfluoroalkyl group-containing copolymer is coated. The foamable thermoplastic resin particle composition used as a foamed styrenic resin particle having a coating layer containing a metal salt of ricinoleic acid in JP-A-2-115242 and in JP-A-3-190941 Expandable styrene resin particles coated with a copolymer of a specific fluorine-containing vinyl monomer and a lipophilic monomer are disclosed.
Japanese Patent Application Laid-Open No. 62-158730 discloses expandable thermoplastic resin particles coated or contained with a copolymer comprising a fluorine-containing vinyl polymer portion and a hydrophilic vinyl polymer portion. ing.
[0008]
[Problems to be solved by the invention]
However, expandable styrenic resin particles or expandable thermoplastic resin particles disclosed in JP-B-56-34172, JP-A-2-88652, JP-A-2-115242 and JP-A-3-190941. Although the composition can exhibit excellent shielding (penetration prevention) for general aqueous (including emulsifying systems) or oily contents, it is contained in the molded product when processed into a molded product. Depending on the type of contents, there was a risk that the permeation prevention performance would be insufficient.
That is, the container molded with the above-mentioned expandable styrene resin particles has a wide range of uses due to its economic efficiency, heat retention, etc., but when used for a long time as a container of some highly permeable contents, etc. There was a risk that the contents would permeate.
[0009]
Of course, the expandable styrenic resin particles disclosed in Japanese Examined Patent Publication No. 56-34172, etc. are partly oily contents having high permeability (for example, curry roux, machine oil, etc. in which an emulsifier component and an oil component are mixed). In addition, by performing heat molding for a relatively long time, excellent shielding properties (permeation preventing properties) can be exhibited. However, it cannot be denied about the decrease in productivity due to long-time heat forming.
[0010]
The expandable thermoplastic resin particles disclosed in JP-A-62-158730 use a copolymer comprising a fluorine-containing vinyl polymer portion and a hydrophilic vinyl polymer portion. There has been a problem that the compatibility of the fluorine-containing vinyl monomer and the hydrophilic vinyl monomer, which are raw materials for the copolymer, is poor and the characteristics of the copolymer are likely to vary.
[0011]
Therefore, when the foamable thermoplastic resin particles disclosed in Japanese Patent Application Laid-Open No. Sho 62-158730 are thermoformed into containers (cups) such as instant noodles, fats and oils in which emulsifier components and fat components are mixed in the distribution stock The contents such as the ingredients, curry ingredients or soup ingredients may be affected by the temperature and humidity and ooze out to the outer wall of the container (cup). In addition, when thermoformed as a returnable box for machine parts, the machine parts are used in a state where the machine parts are attached to machine oil in the returnable box. In some cases, it penetrated into the outer wall.
[0012]
That is, in the expandable styrene resin particles and the like disclosed in any of the aforementioned patent publications, there is a balance between the shielding property (penetration prevention property) for the highly permeable content and the productivity represented by the molding heating time. (Balance) was not always satisfactory.
The present invention has been made in view of the above-described problems, and even when a specific part of the highly permeable content is used for a container or the like, the content to be stored penetrates into the outer wall of the container or the inside of the molded product. It is an object of the present invention to provide an expandable styrene resin particle and an expanded molded product that are excellent in the balance of these properties and can be molded in a short time.
[0013]
[Means for Solving the Problems]
The present invention is obtained by polymerizing a fluorinated vinyl monomer represented by the following formula (1) and a vinyl monomer (first vinyl monomer) represented by the following formula (2). The present invention relates to expandable styrene resin particles obtained by coating the surface of the expandable styrene resin particle main body with a coating containing the fluorine-containing vinyl copolymer and pullulan.
[0014]
[Formula 4]

[0015]
(Wherein R_fIs C_nF_{2n + 1} Fluoroalkyl group represented by (n is an integer of 1 to 16), R₁Is hydrogen or an alkyl group having 1 to 18 carbon atoms, R₂Is an alkylene group having 1 to 10 carbon atoms, R_ThreeRepresents hydrogen or a methyl group, respectively. )
[0016]
[Chemical formula 5]

[0017]
(Wherein R_FourIs hydrogen or methyl group, R_FiveIs an alkylene group having 1 to 4 carbon atoms, R₆Represents an alkyl group having 1 to 4 carbon atoms. )
[0018]
In this way, by forming expandable styrene resin particles that partially contain a hydrophilic polymer, pullulan, which is a hydrophilic polymer, serves as an adhesive, and the fluorine-containing vinyl polymer is more efficient. It is presumed that it can exhibit oil repellency, but it is contained even when it is used for containers with oily contents with high permeability while maintaining excellent shielding of the contents. There is a significant reduction in the risk that the contents will penetrate into the outer wall of the container or the inside of the molded product.
[0019]
Here, a pullulan is an aureobasidium pullulan (Aureobasidium pullulans)Is a water-soluble exopolysaccharide produced by, and is defined as a water-soluble linear glucan having a glucopyranose residue.
[0020]
Further, in constituting the expandable styrene-based resin particles, it is preferable that pullulan is included in the coating at a ratio of 5 to 150 parts by weight with respect to 100 parts by weight of the fluorine-containing vinyl-based copolymer.
[0021]
By including pullulan in the coating within such a range, it is possible to more efficiently prevent the penetration of the hydrophilic component and the oil component. Therefore, even when the expandable styrene resin particles are used in a container for an oily content having high permeability or an oily content in which an emulsifier component and an oil and fat component are mixed, the content to be stored is the container. There is little risk of penetration into the outer wall or inside the molded product.
In addition, when the amount of pullulan is used, the foamable styrenic resin particles are less likely to aggregate and agglomerate during preheating, while pullulan serves as an adhesive during molding heating. It is possible to show excellent fusion properties.
Therefore, from the viewpoint of excellent balance between the shielding properties of the contents and the efficiency of productivity, the amount of pullulan used in the coating is 10 to 130 weights with respect to 100 parts by weight of the fluorinated vinyl copolymer. A value within the range of parts is more preferable, and a value within the range of 50 to 120 parts by weight is optimal.
[0022]
Further, in constituting the expandable styrene resin particles, the fluorine-containing vinyl copolymer further contains a vinyl monomer (second vinyl monomer) represented by the following formula (3). It is preferable to be obtained by polymerization.
[0023]
[Chemical 6]

[0024]
(Wherein R₇Is hydrogen or methyl group, R₈Is an alkylene group having 1 to 4 carbon atoms, R₉And R_TenRepresents an alkyl group having 1 to 4 carbon atoms. )
[0025]
By including the second vinyl monomer in this way, the molecular weight and polarity of the fluorinated vinyl copolymer can be easily controlled, and the adhesion to the expandable styrene resin particle body and foaming during thermoforming It is possible to adjust the fusibility between the functional styrene resin particles.
[0026]
Moreover, when comprising the expandable styrene-type resin particle of this invention, it is preferable to make the average molecular weight of a pullulan into the value within the range of 500-100,000.
If the average molecular weight of pullulan (weight average molecular weight) is a value within such a range, the heat resistance of the pullulan itself is increased, and the adhesion of pullulan to the expandable styrene resin particle body is further improved. It is. Therefore, even when it is used for a container or the like of oily contents having a high permeability and a relatively high temperature, the contained contents are less likely to penetrate into the outer wall of the container or the inside of the molded product. Furthermore, if the average molecular weight of pullulan is a value within such a range, there is less possibility of inhibiting the fusion of the expandable styrene resin particles during molding and heating.
Therefore, it is more preferable to set the average molecular weight of pullulan to a value in the range of 800 to 10,000, and optimally 1 from the viewpoint that the balance between the shielding properties of the contents and the efficiency of productivity is more excellent. , 5,000 to 5,000.
[0027]
In constituting the expandable styrene resin particles of the present invention, pullulan is preferably used as an aqueous solution having a concentration of 1 to 30% by weight.
Fluorine-containing vinyl copolymers are oily and generally poor in compatibility with hydrophilic pullulans. Therefore, even if they are mixed as they are, they may be separated over time. However, if the pullulan used is an aqueous solution having such a concentration, such a problem of mixing and separation does not occur, and the fluorinated vinyl copolymer and the pullulan can be uniformly mixed in an arbitrary amount. it can.
[0028]
In addition, when the pullulan of the present invention has a maltotriose unit containing three glucopyranose residues or a structural unit further containing a plurality of the maltotriose units, the pullulan can be more efficiently used. Viscosity and adhesiveness can be expressed.
[0029]
In forming the expandable styrene resin particles of the present invention, it is preferable to use at least one of an esterified pullulan, an etherified pullulan, or a hydrogenated pullulan as the pullulan.
By reacting pullulan in this way, the heat resistance of the pullulan can be improved, or the water solubility of the pullulan can be adjusted.
[0030]
Further, in constituting the expandable styrene resin particles, the fluorine-containing vinyl copolymer to be used is preferably an aqueous emulsion (sometimes referred to as an aqueous emulsion).
As described above, the fluorinated vinyl copolymer is oily and generally poor in compatibility with hydrophilic pullulan. Therefore, even if it is mixed as it is, it may be separated over time. However, if the fluorine-containing vinyl copolymer to be used is an aqueous emulsion, the problem of mixing and separation does not occur, and the fluorine-containing vinyl copolymer and pullulan are uniformly mixed in an arbitrary amount. be able to.
[0031]
In forming the expandable styrene resin particles, the coating amount (including the fluorine-containing vinyl copolymer and pullulan) is set to 0.006 with respect to 100 parts by weight of the expandable styrene resin particle main body. A value within the range of ˜0.5 parts by weight is preferred.
If the coating amount is a value within such a range, even more efficiently preventing the penetration of oil components, etc., even when used for containers in oily contents with high permeability The risk of the contained contents penetrating into the outer wall of the container or the inside of the molded product is reduced. Moreover, if the coating amount is in such a range, it is possible to provide expandable styrene resin particles and a foam-molded product that can be molded in a shorter time.
Therefore, from the viewpoint of being superior in balance between the shielding properties of the contents and the efficiency of productivity, the coating amount of the coating is 0.015 to 0.25 with respect to 100 parts by weight of the expandable styrene resin particle body. A value within the range of parts by weight is more preferable.
[0032]
Further, in configuring the expandable styrene resin particles, the pullulan coating amount is set to a value within the range of 0.001 to 0.1 parts by weight with respect to 100 parts by weight of the expandable styrene resin particle main body. Is preferred.
If the amount of the pullulan coating is within such a range, more efficiently preventing the penetration of oil components and the like, even when used for containers in oily contents with high permeability, There is less risk that the contents to be stored will penetrate into the outer wall of the container or the inside of the molded product. Moreover, if the coating amount is in such a range, it is possible to provide expandable styrene resin particles and a foam-molded product that can be molded in a shorter time.
Therefore, from the viewpoint of being excellent in balance between the shielding performance of the contents and the efficiency of productivity, the amount of pullulan coated is 0.005 to 0.05 weight with respect to 100 parts by weight of the expandable styrene resin particle body. More preferably, the value is within the range of parts.
[0033]
Further, in constituting the expandable styrene resin particles, the coating amount of the fluorine-containing vinyl copolymer is 0.005 to 0.3 parts by weight with respect to 100 parts by weight of the expandable styrene resin particle main body. A value within the range is preferable.
If the coating amount of the fluorinated vinyl copolymer is within such a range, the oily content is highly permeable and more effectively exhibits oil repellency to prevent the penetration of oil components and the like. Even if it is a case where it uses for the container etc., there is less possibility that the content to be accommodated may penetrate into the outer wall of the container or the inside of the molded product. Moreover, if it is the coating amount of such a range, a possibility that the fusion | bonding of the expandable styrene-type resin particles at the time of shaping | molding may be lessened.
Therefore, from the viewpoint of being excellent in balance between the shielding properties of the contents and the efficiency of productivity, the coating amount of the fluorine-containing vinyl copolymer is set to 0. A value in the range of 01 to 0.2 parts by weight is more preferable.
[0034]
Another aspect of the present invention is a foam molded product obtained by foam molding of the above expandable styrene resin particles.
Even when foamed molded products molded from expandable styrene resin particles containing pullulan are used for containers with some highly permeable contents, the contents to be stored are inside the outer wall of the container or inside the molded product. It can be molded in a short time.
[0035]
Moreover, in heat-molding the foam-molded article of the present invention, it is preferable to foam-mold the expandable styrene resin particles under the conditions of a heating temperature of 90 to 150 ° C. and a heating time of 1 to 60 seconds.
Under such thermoforming conditions, it is possible to produce a foam molded article having an excellent balance between the shielding performance of the contents and the efficiency of productivity.
Therefore, from the viewpoint of producing an excellent foamed molded article with a balance between the shielding properties of the contents and the productivity efficiency, the heating temperature is set to 100 to 140 ° C., and the heating time is within a range of 2 to 10 seconds. More preferably, the heating temperature is 120 to 140 ° C., and the heating time is 3 to 5 seconds.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described. That is, the surface of the foamable styrene resin particle body is coated with a coating containing a fluorine-containing vinyl copolymer obtained by polymerizing a fluorine-containing vinyl monomer and a vinyl monomer and pullulan. In the expandable styrenic resin particles of the present invention, the foamed molded product can be heat-molded using the following expandable styrene resin particles, fluorine-containing vinyl copolymer, pullulan, etc. it can.
[0037]
1. Expandable styrene resin particles
The expandable styrene resin particles of the present invention are obtained by coating the surface of the expandable resin particle main body with a predetermined fluorine-containing vinyl polymer or the like as a coating material (including a coating layer). is there.
[0038]
(1) Expandable styrene resin particle body
As described above, the expandable styrene resin particle main body has a
It can be prepared by impregnating a foaming agent.
[0039]
1) Styrenic resin particles
The styrene resin particles are not particularly limited.
Or a component copolymerizable with a styrene monomer, for example, methacrylic acid esters such as acrylonitrile, methyl methacrylate, butyl methacrylate, acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, α-methyl Mention may be made of one or more copolymers of styrene derivatives such as styrene, chlorostyrene, vinyltoluene and the like and styrene monomers.
Further, the particle diameter of the styrene resin particles is not particularly limited, but for example, styrene resin particles having an average particle diameter in the range of 0.8 to 0.25 mm may be used. preferable. If it is the styrene resin particle in such a range, it can be foamed moderately and can be set as a dense molded product.
[0040]
2) Types of foaming agents
The type of foaming agent is not particularly limited, but a liquid or gaseous compound at room temperature such as aliphatic hydrocarbons such as propane, butane, pentane and hexane, or fluorocarbon compounds such as Freon 11 and Freon 12 is used. Can be mentioned.
3) Impregnation method and amount of foaming agent
There is no restriction | limiting in particular as an impregnation method of a foaming agent, The method generally used conventionally can be employ | adopted. Moreover, it is preferable to make the amount of impregnation of the foaming agent into the styrene resin particles be a value within the range of 1 to 10% by weight. If the foaming agent is impregnated in such a range, the foamable styrene resin particles (styrene resin particles) can be appropriately foamed to form a dense molded product.
[0041]
2. Fluorine-containing vinyl copolymer
As the fluorine-containing vinyl copolymer, a fluorine-containing vinyl monomer represented by the following formula (1) and a vinyl monomer represented by the following formula (2) (referred to as a first vinyl monomer) )) May be used, or a fluorine-containing vinyl monomer represented by the formula (1) and a vinyl polymer represented by the formula (2) may be used. Copolymer obtained by polymerizing a monomer (first vinyl monomer) and a vinyl monomer represented by the following formula (3) (referred to as a second vinyl monomer) A combination (three-component system) or the like may be used.
[0042]
(1) Fluorine-containing vinyl monomer
As the fluorine-containing vinyl monomer, a compound represented by the following formula (1) is used.
[0043]
[Chemical 7]

[0044]
(Wherein R_fIs C_nF_{2n + 1} Fluoroalkyl group represented by (n is an integer of 1 to 16), R₁Is hydrogen or an alkyl group having 1 to 18 carbon atoms, R₂Is an alkylene group having 1 to 10 carbon atoms, R_ThreeRepresents hydrogen or a methyl group, respectively. )
[0045]
Specific examples of such fluorine-containing vinyl monomers include the following.
C₈F₁₇SO₂-N (CH_Three) -CH₂CH₂OCOCH = CH₂
C₈F₁₇SO₂-N (CH_Three) -CH₂CH₂OCOC (CH_Three) = CH₂
C₈F₁₇SO₂-N (C₂H_Five) -CH₂CH₂OCOCH = CH₂
C₈F₁₇SO₂-N (C₂H_Five) -CH₂CH₂OCOC (CH_Three) = CH₂
[0046]
(2) Vinyl monomer (first vinyl monomer)
As the first vinyl monomer, a compound represented by the following formula (2) is used.
[0047]
[Chemical 8]

[0048]
(Wherein R_FourIs hydrogen or methyl group, R_FiveIs an alkylene group having 1 to 4 carbon atoms, R₆Represents an alkyl group having 1 to 4 carbon atoms. )
[0049]
Specific examples of such a first vinyl monomer include the following.
CH₂= CH-COOC₂H_FourOCH_Three
CH₂= C (CH_Three) -COOC₂H_FourOCH_Three
CH₂= CH-COOC₂H_FourOC₂H_Five
CH₂= C (CH_Three) -COOC₂H_FourOC₂H_Five
[0050]
(3) Vinyl monomer (second vinyl monomer)
As the second vinyl monomer, a compound represented by the following formula (3) is used.
[0051]
[Chemical 9]

[0052]
(Wherein R₇Is hydrogen or methyl group, R₈Is an alkylene group having 1 to 4 carbon atoms, R₉And R_TenAn alkyl group having 1 to 4 carbon atoms is shown. )
[0053]
Specific examples of the second vinyl monomer include the following.
CH₂= CH-COOC₂H_FourN (CH_Three)₂
CH₂= C (CH_Three) -COOC₂H_FourN (CH_Three)₂
[0054]
(4) Polymerization ratio
The fluorine-containing vinyl copolymer obtained by polymerizing the fluorine-containing vinyl monomer represented by the formula (1) and the vinyl monomer represented by the formula (2) (first vinyl monomer). In the case of a polymer (two-component system), when the total amount is 100% by weight, the polymerization rate of the fluorinated vinyl monomer is within the range of 40 to 95% by weight, and the first vinyl unit It is preferable to set the polymerization ratio of the monomer to a value in the range of 5 to 50% by weight.
When the polymerization ratio of the fluorine-containing vinyl monomer exceeds 95% by weight, there is a tendency to inhibit the heat fusion of the expandable styrene resin particles at the time of heat molding. When used as a product, it tends to be difficult to provide sufficient water and oil repellency.
Therefore, from the viewpoint of a better balance between moldability, water repellency and oil repellency, the polymerization rate of the fluorinated vinyl monomer is in the range of 50 to 80% by weight when the total amount is 100% by weight. It is more preferable to set the value within the range and the polymerization ratio of the first vinyl monomer within the range of 20 to 50% by weight.
[0055]
Moreover, the fluorine-containing vinyl-type monomer shown by Formula (1), the vinyl-type monomer (1st vinyl-type monomer) shown by Formula (2), and the vinyl shown by Formula (3) In the case of a fluorine-containing vinyl copolymer (three-component system) obtained by polymerizing a monomer (second vinyl monomer), when the total amount is 100% by weight, The polymerization rate of the monomer is in the range of 50 to 85% by weight, the polymerization rate of the first vinyl monomer is in the range of 5 to 40% by weight, the second vinyl monomer The polymerization ratio is preferably set to a value within the range of 1 to 10% by weight.
If the polymerization ratio of the second vinyl monomer exceeds 10% by weight, the adhesion to the expandable styrene resin particles tends to decrease, whereas if it is less than 1% by weight, water repellency and the like are exhibited. Tends to be insufficient.
Therefore, from the viewpoint of a better balance between moldability, water repellency and oil repellency, the polymerization ratio of the fluorine-containing vinyl monomer is a value within the range of 50 to 80% by weight, the first vinyl monomer. It is more preferable to set the polymerization rate of the body to a value within the range of 5 to 40% by weight and the polymerization rate of the second vinyl monomer to a value within the range of 1 to 10% by weight.
[0056]
(5) Polymerization method
Although there is no restriction | limiting in particular as a polymerization method of the fluorine-containing vinyl-type copolymer in this invention, For example, solution polymerization, emulsion polymerization, etc. can be mentioned. Examples of the polymerization initiator used for the polymerization include lauroyl peroxide, benzoyl peroxide, t-butyl peroxyisobutyrate, and t-butyl peroxypivalate in solution polymerization. Examples of emulsion polymerization include potassium persulfate and ammonium persulfate.
[0057]
(6) Properties of fluorinated vinyl copolymer
As described above, the fluorine-containing vinyl copolymer is preferably an aqueous emulsion (sometimes referred to as an aqueous emulsion) when used. This is because the aqueous emulsion does not cause a problem of mixing and separation with pullulan, and the fluorine-containing vinyl copolymer and pullulan can be uniformly mixed.
[0058]
3. Pullulan
(1) Types of pullulan
As the pullulan that can be used in the present invention, commercially available pullulan can be used as it is, for example, pullulan PF-20 manufactured by Hayashibara Biochemical Research Institute can be used. And as above-mentioned, it is preferable to use the pullulan in the range whose average molecular weight is 500-100,000.
Further, as described above, esterified pullulan, etherified pullulan, or hydrogenated pullulan is preferable.
[0059]
Further, the form of pullulan is not particularly limited, but an aqueous solution having a concentration of 1 to 30% by weight is preferable. From the viewpoint of good workability, the viscosity of the aqueous solution having a pullulan concentration of 5% by weight is a value in the range of 1 to 100 centipoise (cp), more preferably a value in the range of 10 to 80 centipoise (cp). It is.
Also, from the viewpoint of better fusion between the expandable styrenic resin particles at the time of thermoforming, the pullulan glass transition point is preferably a value within the range of 30 to 100 ° C., more preferably, It is a value within the range of 40-80 degreeC.
[0060]
In order to adjust the glass transition point of pullulan, improve the flexibility, or to improve the mixing property with the fluorine-containing vinyl monomer, glycerol, ethylene glycol, DBP ( One or two or more of dibutyl phthalate), DOP (dioctyl phthalate), alginic acid amide, acrylamide, starch, CMC, methylcellulose, glyoxazole, dimethylol urea and the like can be added.
[0061]
(2) How to use pullulan
Pullulan can be coated on the expandable styrenic resin particle body after mixing with the fluorine-containing vinyl monomer, and separately from the fluorine-containing vinyl monomer, It is also preferable to coat the styrene resin particle body. It is preferable in that it can be coated on the expandable styrenic resin particle main body by a single operation by coating after mixing with the fluorine-containing vinyl monomer. On the other hand, the expandable styrene resin particle alone By subjecting the main body to a coating treatment, it is preferable in that the possibility of uneven density due to separation from the fluorine-containing vinyl monomer is reduced.
[0062]
4). Other coating agents
In the coating of the foamable styrene resin particle main body, a conventionally known coating agent can be used in combination with the above-mentioned copolymer. Examples thereof include metal soaps such as zinc stearate and calcium stearate used for preventing agglomeration in primary foaming, and higher fatty acid amides such as stearamide. These agglomeration inhibitors are preferably used in the range of 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the expandable styrene resin particle body. Of these, zinc stearate is particularly preferred from the viewpoint of agglomeration prevention and is inexpensive and economical.
[0063]
In the molding step, an additive having an effect of promoting fusion of the expandable styrene resin particle main body can be used. A conventionally well-known thing can be used as this substance. For example, one or more of higher fatty acid triesters, diesters, monoesters, sucrose esters such as stearic acid glyceride and oleic acid glyceride can be used.
[0064]
Further, nonionic interfaces such as polyhydric alcohols such as glycerin, sorbitol, polyethylene glycol and polypropylene glycol, sorbitan esters, and ethylene glycol adducts of higher fatty acids used as antistatic agents for the primary foamable styrene resin particles. One or more active agents may be used in combination. These antistatic agents are preferably used in the range of 0.005 to 0.2 parts by weight with respect to 100 parts by weight of the expandable styrene resin particle body.
[0065]
5. Formation of coating (coating layer)
The method for forming the coating of the fluorine-containing vinyl copolymer and pullulan on the surface of the expandable styrenic resin particle main body in the present invention is not particularly limited and can be carried out by conventionally known means.
For example, using a blender such as a ribbon blender, V-shaped blender, Henschel mixer, Redige mixer, etc., at room temperature, at a rotational speed of 100 to 10,000 rpm, and at a stirring time of 10 seconds to 1 hour, a foaming styrene type The coating can be formed by mixing the resin particle main body, the fluorine-containing vinyl copolymer, pullulan, each component of the aforementioned coating agent, and the like.
However, the expandable styrene resin particle main body, the fluorine-containing vinyl copolymer, pullulan, the above-described coating agent components, and the like can be individually coated in layers.
[0066]
6). Foam molding
The foamed molded product of the present invention can be obtained by molding the above-mentioned expandable styrene resin particles. That is, by using the above-mentioned expandable styrene resin particles, it is possible to obtain a foam-molded article having excellent oil repellency in which the foam particles are firmly fused and the particle interface is excellent with a short molding heating time. Can do.
Here, the specific molding heating conditions are not particularly limited, but as described above, using a mold or the like, the heating temperature is 90 to 150 ° C. and the heating time is 1 to 60 seconds. Foam molding is preferred. Accordingly, when the foamed molded product of the present invention is produced in this way, for example, the penetration of lard, instant ramen, kareulu, mayonnaise, margarine, etc. into the foamed molded product (container). Even if highly oily and fatty foods or machine oils are directly packaged or contained, it is possible to effectively prevent oils and fats from penetrating from between the expandable styrene resin particles constituting the foamed molded product to the outside of the container. It is also possible to extend the product life of the foam molded product.
[0067]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples. However, the examples are only examples of the present invention, and the present invention is not limited to these descriptions.
[0068]
[Example 1]
(1) Sample preparation
Expandable polystyrene particles having an average particle size (diameter) of 0.35 to 0.60 mm containing 5.5% by weight of pentane (weight ratio of iso-pentane / n-pentane = 30/70) as a foaming agent (Hitachi Chemical Industry) 2000 g of High Beads 5SG) was put into a Henschel mixer.
Next, 6 g of zinc stearate (in Table 1, component 3) and sugar ester (A-10E manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (in Table 1, component 4) 0. 0 while stirring at a rotational speed of 500 to 1000 rpm. 4 g, 0.4 g of glycerin (in Table 1, component 5), 0.4 g of an aqueous pullulan solution having a concentration of 5 wt% and a solution viscosity of 20 cp (in Table 1, component 2), and fluorine-containing vinyl system 2.2 g of a 20% aqueous emulsion of a copolymer (component 1 in Table 1) (solid content of fluorine-containing vinyl copolymer 0.4 g) was sequentially added.
[0069]
In addition, the kind and ratio of the monomer which comprise a fluorine-containing vinyl-type copolymer (in Table 1, component 1) are as follows.
C₈F₁₇SO₂-N (CH_Three) -CH₂CH₂OCOCH = CH₂        65% by weight
CH₂= C (CH_Three) -COOC₂H_FourOC₂H_Five                    30% by weight
CH₂= CH-COOC₂H_FourN (CH_Three)₂                       5% by weight
[0070]
Then, after stirring was continued for about 90 seconds, stirring was stopped to obtain a raw material solution. Subsequently, using a batch type primary foaming apparatus, the solid content was foamed to a bulk density of 10 ml / g using a mixture of hot air and steam as a heat medium to obtain primary foamed resin particles.
Thereafter, the primary foamed resin particles were aged at room temperature and normal pressure for 16 hours, and then filled in a mold for obtaining a molded product having an internal volume of 500 cc and a wall thickness of 2.0 mm. Then, the foamed molded product (cup) was heat-molded under the conditions of a heating temperature of 140 ° C. and a heating time of 4 seconds.
At this time, in addition to the heating time, the raw material filling time, the preheating time until the mold reaches the heating temperature (140 ° C.) from room temperature, and the mold is cooled to a predetermined temperature or less to take out the foam molded product. However, it took about 8 seconds for that.
[0071]
(2) Performance evaluation
1) Measurement of fusion degree
The foamed molded product (cup) was broken by hand to expose the fracture surface. Then, the fracture surface was observed with an optical microscope, and the area ratio of the cohesive fracture portion per unit area was measured as the degree of fusion (%). In addition, when the expandable styrene resin particles are fused well, there are many portions that are cohesively broken on the fracture surface, and conversely, the fusion between the expandable styrene resin particles is insufficient. In some cases, it will be destroyed at the particle interface.
[0072]
2) Surfactant shielding test
As an acceleration test, a shielding test for a surfactant was performed. That is, after adding about 300 g of a surfactant aqueous solution (score roll 700 manufactured by Kao Corporation, concentration 0.1% by weight), the cup was wrapped with a wrapping film made of saran resin. Then, the cup thus packaged is left in an oven at 60 ° C., and the time until the aqueous surfactant solution penetrates into the outer wall of the cup (represented by penetration time 1 in Table 1). Measured).
[0073]
3) Oil / oil component shielding test
As confirmation of the shielding property against oil and fat components, 200 g of curry roux was put into the obtained foamed molded product (cup), and then the cup was wrapped with a salan resin wrapping film. And the cup packaged in this way is left in an oven at 60 ° C., and the time until the curry leach penetrates into the outer wall of the cup (represented by the permeation time 2 in Table 1. The same applies hereinafter. ) Was measured. The respective measurement results are shown in Table 1.
[0074]
As is clear from this result, the degree of fusion was as high as 80% despite the extremely short heating time of 4 seconds. Further, the penetration time 1 of the surfactant as the emulsifier component was 50 minutes, and the penetration time 2 of the curry leu as the fat and oil component was 24 hours, which were practically no problem.
Therefore, when the expandable styrenic resin particles of the present invention are molded into a foam molded product (cup), even if the content is highly permeable, the time for the content to penetrate to the outer wall of the foam molded product ( The penetration time) can be remarkably lengthened to obtain a penetration time equal to or longer than the penetration time for the content of the aqueous component, and the expandable styrenic resin particles of the present invention can be foamed in a short time. It was confirmed that the product could be heat molded.
[0075]
[Examples 2 and 3]
In Example 1, a foamed molded article (cup) was obtained under the same conditions as in Example 1 except that the heat molding time was 5 seconds (Example 2) and 6 seconds (Example 3). And performance evaluation was performed similarly to Example 1.
[0076]
Each measurement result is shown in Table 1. As is apparent from this result, the heating time was slightly longer at 5 seconds and 6 seconds, so that the degree of fusion was 100%, which was the highest value.
Further, the surfactant penetration time 1 is 60 minutes or longer (5 and 6 seconds heating), and the oil penetration component 2 is 48 hours (5 seconds heating) or 72 hours (6 seconds heating). Showed good shielding properties.
Therefore, as described above, the expandable styrenic resin particles of the present invention have a practically sufficient content shielding property and heat moldability of the foam molded product as a foam molded product (cup) even when the heating time is 4 seconds. However, it was confirmed that by taking a longer heating time (heating for 5 or 6 seconds), it was possible to obtain more excellent shielding properties of the contents and heat moldability of the foam molded product. .
[0077]
[Examples 4 and 5]
The amount of pullulan (component 2 in Table 1) used in Example 1 per 100 parts by weight of expandable polystyrene particles was changed from 0.02 parts by weight to 0.005 parts by weight, and 0.02 parts by weight was added. Foam molded articles (cups) were obtained under the same conditions as in Examples 1 and 2 except that 0.01 parts by weight of polyethylene glycol was added as component 5 (in Table 1) instead of the glycerin. And performance evaluation was performed similarly to Example 1.
[0078]
Each measurement result is shown in Table 1. As is clear from this result, when the amount of pullulan used is reduced, the degree of fusion when the heating time is 4 seconds is 90%, and the degree of fusion when the heating time is 5 seconds is 100%. It was. That is, with respect to the degree of fusion, there was a tendency that better results were obtained when the amount of pullulan used was smaller.
In contrast, the penetration time 1 of the surfactant was 40 minutes when the heating time was 4 seconds, and 60 minutes when the heating time was 5 seconds. Moreover, as the penetration time 2 of curry roux as an oil and fat component, a long value of 24 hours (4 seconds heating and 5 seconds heating) was shown.
Therefore, pullulan contributes greatly to the shielding properties of the contents, and when the amount of pullulan used decreases, the shielding properties tend to decrease.
[0079]
[Examples 6 and 7]
The amount of the fluorine-containing vinyl copolymer (component 1 in Table 1) used in Example 1 per 100 parts by weight of expandable polystyrene particles was changed from 0.02 parts by weight to 0.03 parts by weight, In addition to the addition of polyethylene glycol (PEG-400, manufactured by Sanyo Chemical Co., Ltd.) instead of glycerin as component 5 (in Table 1), each of the foam-molded articles (under the same conditions as in Examples 1 and 2) Cup). And performance evaluation was performed similarly to Examples 1-2. The respective measurement results are shown in Table 1.
[0080]
As is apparent from this result, when polyethylene glycol is used in place of glycerin, excellent shielding of the contents and heat moldability of the foam molded product can be obtained as in the case of using glycerin. It was confirmed.
[0081]
[Examples 8 to 9]
A commercially available fluorine-containing vinyl copolymer (manufactured by 3M Co., Ltd., Scotch Van FX-845) was used as component 1 (in Table 1) instead of the fluorine-containing vinyl copolymer of Example 1. Respectively obtained foam molded articles (cups) under the same conditions as in Examples 1 to 3. And performance evaluation was performed similarly to Examples 1-3. The measurement results are shown in Table 1.
Scotch van FX-845 is found to correspond to the fluorine-containing vinyl copolymer used in Examples 1 to 7 from the measurements of FT-IR, NMR, and GC-MS.
[0082]
As is clear from this result, it was confirmed that even when a commercially available fluorine-containing vinyl-based copolymer was used, excellent shielding of the contents and heat moldability of the foam molded product were obtained.
[0083]
[Comparative Examples 1-3]
In Examples 1 to 3, foamed molded articles (cups) were obtained under the same conditions as in Examples 1 to 3 except that only pullulan was used to obtain expandable styrene resin particles. And performance evaluation was performed similarly to Examples 1-3. The respective measurement results are shown in Table 1.
[0084]
As is clear from this result, even when pullulan is not used at all, the degree of fusion when the heating time is 4 seconds is 80%, and the degree of fusion when the heating time is 5 seconds and 6 seconds is 100%, respectively. %Met. That is, with respect to the degree of fusion, even when pullulan was not used, there was a tendency to obtain results that were not significantly different from those when it was used.
On the other hand, the penetration time 1 of the surfactant is 20 minutes when the heating time is 4 seconds, 45 minutes when the heating time is 5 seconds, and 60 minutes when the heating time is 6 seconds. Met. Further, the penetration time 2 of curry roux as an oil component is less than 4 hours when the heating time is 4 seconds, 8 hours when the heating time is 5 seconds, and 6 hours when the heating time is 6 seconds. It was 24 hours. Therefore, pullulan contributes greatly to the shielding properties of the contents, and if the pullulan is not used, the shielding properties tend to be significantly reduced.
[0085]
[Comparative Examples 4 to 6]
In Examples 1 to 3, foamed molded articles (cups) were obtained under the same conditions as in Examples 1 to 3 except that only the fluorinated copolymer was used to obtain expandable styrene resin particles. And performance evaluation was performed similarly to Examples 1-3. The respective measurement results are shown in Table 1.
[0086]
As is clear from this result, when a specific fluorine-containing copolymer is not used, the degree of fusion is 80% when the heating time is 4 seconds, and the degree of fusion when the heating time is 5 seconds and 6 seconds. Was 100% respectively. That is, with respect to the degree of fusion, even when a specific fluorine-containing copolymer was not used, there was a tendency to obtain a result that was not significantly different from that when it was used.
In contrast, the penetration time 1 of the surfactant was 20 minutes when the heating time was 4 seconds and 5 seconds, and was 30 minutes even when the heating time was 6 seconds. Moreover, the penetration time 2 of curry roux as an oil component was less than 4 hours when the heating time was 4 seconds and 5 seconds, and was 24 hours even when the heating time was 6 seconds.
Therefore, the presence of a specific fluorine-containing copolymer contributes greatly to the shielding properties of the contents, and unless the specific fluorine-containing copolymer is used, the shielding properties of the contents tend to decrease significantly. It was seen.
[0087]
[Comparative Examples 7 to 9]
In Examples 1 to 3, a foamed molded article (cup) was obtained under the same conditions as in Examples 1 to 3 except that the fluorinated copolymer and pullulan were used to form expandable styrene resin particles. . And performance evaluation was performed similarly to Examples 1-3. The respective measurement results are shown in Table 1.
[0088]
As is clear from this result, even when the specific fluorine-containing copolymer and pullulan are not used, the fusion degree is 80% at a heating time of 4 seconds, and the heating time is 5 seconds and 6 seconds. The degree of fusion was 100%.
That is, with respect to the degree of fusion, even when a specific fluorine-containing copolymer and pullulan were not used, there was a tendency to obtain a result that was not significantly different from the case where it was used.
On the other hand, the penetration time 1 of the surfactant is 10 minutes when the heating time is 4 seconds, 15 minutes when the heating time is 5 seconds, and even when the heating time is 6 seconds. It was 30 minutes. Moreover, the penetration time 2 of curry roux as an oil component was less than 4 hours when the heating time was 4 seconds and 5 seconds, and was 4 hours even when the heating time was 6 seconds.
Therefore, regarding the shielding properties of the contents, the presence of the specific fluorine-containing copolymer and pullulan greatly contributes, and if the specific fluorine-containing copolymer and pullulan are not used, the shielding properties of the content are There was a tendency to decrease significantly.
[0089]
[Table 1]

[0090]
【The invention's effect】
According to the present invention, when a foam molded product (cup) is molded, even if the content is highly permeable, the time (permeation time) for the content to permeate to the outer wall of the foam molded product can be significantly increased. I can do it now. And the shielding property which was excellent also with respect to the content with especially high permeability | transmittance, such as Kalerou, was able to be hold | maintained for the said remarkably long time.
Moreover, it was confirmed that the foamable styrenic resin particles are composed of the foamable styrenic resin particles as described above, and the productivity of the foamable styrenic resin particles is not impaired while having the excellent shielding property.
Therefore, according to the present invention, it is possible to provide expandable styrene-based resin particles and a foam-molded product excellent in the balance between the shielding property of the highly permeable content and the heat moldability.

Claims (9)

A fluorine-containing vinyl-based copolymer obtained by polymerizing a fluorine-containing vinyl-based monomer represented by the following formula (1) and a vinyl-based monomer represented by the following formula (2), and pullulan: Expandable styrene resin particles obtained by coating the surface of the expandable styrene resin particle main body with a coating containing the same.

(In the formula, R _f is a fluorinated alkyl group represented by C _n F _{2n + 1} (n is an integer of _{1 to} 16), R ₁ is hydrogen or an alkyl group having 1 to 18 carbon atoms, and R ₂ is the number of carbon atoms. 1 to 10 alkylene groups, R ₃ represents hydrogen or methyl group, respectively)

(In the formula, R ₄ represents hydrogen or a methyl group, R ₅ represents an alkylene group having 1 to 4 carbon atoms, and R ₆ represents an alkyl group having 1 to 4 carbon atoms.)   2. The expandable styrene resin particle according to claim 1, wherein the covering includes 5 to 150 parts by weight of the pullulan with respect to 100 parts by weight of the fluorine-containing vinyl copolymer. Resin particles. 3. The expandable styrene resin particle according to claim 1 or 2, wherein the fluorine-containing vinyl copolymer is a vinyl monomer represented by the following formula (3) as a second vinyl monomer. Expandable styrenic resin particles obtained by further polymerizing.

(Wherein R ₇ is hydrogen or a methyl group, R ₈ is an alkylene group having 1 to 4 carbon atoms, and R ₉ and R ₁₀ are each an alkyl group having 1 to 4 carbon atoms.)   The expandable styrenic resin particle according to any one of claims 1 to 3, wherein the pullulan has a molecular weight in a range of 500 to 100,000.   The expandable styrenic resin particle according to any one of claims 1 to 4, wherein the pullulan is an aqueous solution having a concentration of 1 to 30% by weight.   The expandable styrenic resin particle according to any one of claims 1 to 5, wherein the pullulan is at least one of an esterified, etherified or hydrogenated pullulan.   The expandable styrenic resin particle according to any one of claims 1 to 6, wherein the fluorinated vinyl copolymer is an aqueous emulsion.   The expandable styrenic resin particles according to any one of claims 1 to 7, wherein the coating amount of the coating is 0.006 to 0.00 with respect to 100 parts by weight of the expandable styrene resin particle main body. Expandable styrene resin particles having a value within the range of 5 parts by weight.   A foam-molded product obtained by foam-molding the expandable styrenic resin particles according to any one of claims 1 to 8.