JP3714905B2

JP3714905B2 - Thermal insulation material for building made of polystyrene resin foam particle molding

Info

Publication number: JP3714905B2
Application number: JP2001399918A
Authority: JP
Inventors: 孝雄廉田; 正行若林
Original assignee: ダウ化工株式会社
Priority date: 2001-12-28
Filing date: 2001-12-28
Publication date: 2005-11-09
Anticipated expiration: 2021-12-28
Also published as: JP2003192821A

Description

【０００１】
【発明の属する技術分野】
本発明は、建築用断熱材に係り、より詳しく述べると、建築物の断熱材として好適な熱伝導率が良好で低密度なポリスチレン系樹脂発泡粒子成型体からなる合成樹脂発泡体に関する。
【０００２】
【従来の技術】
熱可塑性樹脂発泡体は大きく分けて次の押出発泡法と型内発泡法の２方法により製造されている。
【０００３】
押出発泡法：押出板状熱可塑性樹脂発泡体は熱可塑性樹脂を高温・高圧下の押出機中で溶融し、続いて発泡ガスを注入し、樹脂中に分散溶解して流動性のゲルを形成し、これを押出機のダイスから低圧域に押出して急速に発泡させ、冷却し板状の製品とする方法である。
【０００４】
従来、発泡剤は熱伝導率の低い塩素フッ素化炭化水素又はフッ素化炭化水素（以下総称してフロンという）を用い、発泡体中に封じこめることにより良好な熱伝導率の製品が得られていた。
【０００５】
また、表層に水酸基を有する鉱物質微粉末を添加し、水を押出機に圧入することにより大小の気泡が気泡膜を介して海島状に分散されている合成樹脂押出発泡体が得られることが提案されている。しかし、この方法では、水を使用するため押出機系内の腐食、特に水を難燃剤等のハロゲン系添加剤と併用した場合の腐食が問題となり、耐食性の設備とするために高額な設備費が必要となる問題がある。更に水の樹脂中への分散が良くないため大小気泡径の割合を一定にコントロールすることは非常に困難であり、品質の安定しない製品となるという問題もある。即ち、装置が高い、品質安定性に乏しいという問題がある。
【０００６】
型内発泡法：熱可塑性合成樹脂発泡粒子成型体は、熱可塑性合成樹脂を懸濁重合法又は含浸法によって発泡ガスを注入したビーズ状又はペレット状原料を予備発泡機にて所定の密度の予備発泡粒子に蒸気発泡させて、熟成養生後、それを金型キャビティー内に充填し、続いて水蒸気を吹き込み予備発泡粒子を軟化状態にさせ、二次発泡膨張圧で予備発泡粒子同士を融着成型させ、その後、冷却し製品とする方法である。
【０００７】
【発明が解決しようとする課題】
近年、押出発泡法により得られる発泡体も、オゾン層破壊、地球温暖化の観点からフロンの使用が問題視されている。しかし、フロンを使用しない発泡体は良好な熱伝導率を得ることが困難であるという問題がある。また、フロンを使用せずに熱伝導率の良好な発泡体を得るために、輻射による熱伝導率を改善するため、カーボンブラック等の熱線吸収剤の添加、グラファイト等の熱線反射剤を添加する方法が提案されているが、屋外に当該発泡板を仮置きした場合や、屋上等に施工し放置した場合に、発泡板の表面温度が上昇し、反りが発生する問題が生じるという問題がある。
【０００８】
建築用断熱材として利用される熱伝導率が良好な成型体を作製するためには、気泡径を小さくし、輻射を低減する必要があるが、気泡径を小さくすると密度が高くなり、押出法の場合には所定の大きな断面サイズが得られないという問題がある。
【０００９】
そこで、本発明は、フロンガス等の環境に影響を及ぼす発泡ガスを使用せずに、低密度、低コストで優れた断熱性と寸法安定性を有する成型性の良好な成型体を提供することを目的とする。
【００１０】
【課題を解決するための手段】
本発明者は、フロンを使用せずに熱伝導率が良好で寸法安定性が良く施工上問題のない低コストなポリスチレン系樹脂発泡板を得るためには、型内発泡法により気泡径の小さい粒子と気泡径の大きな粒子とを混合し、更には輻射を低減する添加剤を用いて製造するポリスチレン系樹脂発泡粒子成型体が最も良いことを見出した。
【００１１】
こうして本発明は下記を提供する。
【００１２】
（１）平均気泡径の異なる２種類以上の発泡粒子からなるポリスチレン系樹脂発泡粒子成型体であり、平均気泡径が０．１５ mm 以下である気泡粒子の占める体積割合が１０％以上であることを特徴とする建築用断熱材。
【００１３】
（２）前記発泡粒子が輻射低減剤を含有していることを特徴とする（１）記載の建築用断熱材。
【００１４】
（３）前記輻射低減剤がカーボンブラックまたはグラファイトであることを特徴とする（２）記載の建築用断熱材。
【００１５】
（４）前記ポリスチレン系樹脂発泡粒子成型体が輻射低減剤を含有し、かつ該成型体の厚み方向の少なくとも上下面が輻射低減剤が含有されてない発泡粒子層で構成されている（２）（３）記載の建築用断熱材。
【００１６】
（５）前記輻射低減剤が含有されてない発泡粒子層が熱可塑性樹脂発泡粒子成型体の全体体積に対して５０％以下であることを特徴とする（２）〜（４）記載の建築用断熱材。
【００１７】
（６）前記成型体の密度が３５Kg／ｍ^３以下であり且つ熱伝導率が０．０２８Ｗ／m・K 以下であることを特徴とする（１）〜（５）に記載の建築用断熱材。
【００１８】
【発明の実施の形態】
本発明の建築用断熱材はポリスチレン系樹脂発泡粒子成型体からなる。ポリスチレン系樹脂発泡粒子成型体は、軽量で優れた成形性、安定した品質等の特性を有するので、建築用断熱材として多用されている材料である。
【００１９】
本発明で使用されるポリスチレン系樹脂は、例えば、スチレン、α−メチルスチレン、クロルスチレン、ジクロルスチレン、ジメチルスチレン、ｔ−ブチルスチレン、ビニルトルエンなどのスチレン誘導体、またはこれらの２種以上の組み合わせからなる共重合体、あるいはそれらとアクリル酸、アクリル酸エステル、メタクリル酸、無水マレイン酸、またはブタジエンのような他と容易に重合し得る化合物との共重合体をいう。
【００２０】
本発明のポリスチレン系樹発泡粒子成型体の発泡剤は、フロン即ち塩素化あるいはフッ素化炭化水素などの環境に影響のあるとされ使用が控えられる化合物以外の化合物である。
【００２１】
これらの環境上好ましくない発泡剤でない発泡剤としては、限定するわけではないが、例えば、物理発泡剤がある。物理発泡剤としては、プロパン、ブタン、ペンタン、ヘキサンなどの脂肪族炭化水素などを挙げることができる。
【００２２】
本発明のポリスチレン系樹脂発泡粒子成型体において発泡剤の量は一般的にポリスチレン系樹脂１００重量部当たり約３〜３０重量部の範囲内が好適である。
【００２３】
本発明の建築用断熱材は平均気泡径の異なる発泡粒子を含むポリスチレン系樹脂型内発泡粒子成型体からなることを特徴とする。
【００２４】
図１に本発明の平均気泡径の異なる発泡粒子を含むポリスチレン系樹脂型内発泡粒子成型体の断面構造の一部を拡大して模式的に示すが、成型体は大気泡粒子１と小気泡粒子２が混合されて存在し、それぞれの発泡粒子１，２は型内二次発泡成型の際に相互に融着している。３は融着層である。大気泡粒子１と小気泡粒子２は、それぞれ、型内発泡法のゆえにそれぞれ比較的に均一な径の気泡からなりまた平均気泡径も比較的に均一である。
【００２５】
発泡体の気泡径を小さくすれば、伝熱方向の気泡膜の数が多くなり輻射を低減でき熱伝導率の低下をもたらす。一方、発泡体の気泡径を大きくすれば、気泡膜厚みが大きくなり、発泡時の膜の張力が減少し、気泡膜を破る事無く低密度化できる。また気泡径が大きいと気泡膜厚が厚くなり良好な寸法安定性と機械的強度をもたらす。しかし、本発明に従い、平均気泡径が異なる発泡粒子を混合して含む型内発泡粒子成型体として構成することにより、低密度で熱伝導率の良好な発泡体の製造が可能である。しかも本発明によれば、単に一次発泡粒子の種類を変えて混合するだけでよいので、成型体全体に所望の気泡径の発泡粒子を所望に分布させた発泡板が簡単に得られ、しかも各発泡粒子の気泡径及びそれらの体積割合も所望に仕立てることが可能である利点を有する。
【００２６】
本発明の建築用断熱材のポリスチレン系樹脂発泡粒子成型体において平均気泡径の異なる２種以上の発泡粒子は、最小の平均気泡径を有する発泡粒子を、最大の平均気泡径を有する発泡粒子の平均気泡径の０．９倍以下、好ましくは０．８倍以下、さらに好適には０．７倍以下の平均気泡径を有することが好ましい。この大小平均気泡径の発泡粒子の気泡径の差が小さいと、本発明の目的である低密度、低熱伝導率、寸法安定性などの所望の特性を両立させることができない。発泡粒子の平均気泡径の差の上限は実用的な観点から決定すればよいが、最小の平均気泡径が最大の平均気泡径の０．２倍以上であることが好ましい。０．２倍未満では最小の平均気泡径を有する発泡粒子と最大の平均気泡径を有する発泡粒子との物性が異なりすぎて成型がしづらく、更に最小の平均気泡径が小さすぎても密度が高くなり、最大の平均気泡径が大きすぎても熱伝導率が劣る傾向にある。
【００２７】
しかし、特に良好な熱伝導率（低熱伝導率）を達成するために、平均気泡径が０．２mm以下である発泡粒子が１０体積％以上を占めることが必要である。この要件を満たさないと、本発明の目的を達成する上で気泡径大小２種類以上の発泡粒子を混合する意味がない。平均気泡径が０．１５ mm 以下である発泡粒子を１０体積％以上含まないと、フロンを含有しない発泡体の輻射熱を所望に低減する効果が十分に得られない。また、平均気泡径が０．１５mm以下である発泡粒子を２０体積％以上、さらには３０体積％以上、特に４０体積％以上含むことが好ましい。しかし、平均気泡径が０．１５mm以下である発泡粒子が多すぎても、密度が高くなるので、平均気泡径が０．１５mm以下である発泡粒子が占める体積は、一般的には９０体積％以下、好ましくは８０体積％以下、さらには７０体積％以下、特に６０体積％以下にされる。
【００２８】
本発明の建築用断熱材において大きい方の平均気泡径の発泡粒子の平均気泡径は、平均気泡径が小さい発泡粒子に対して平均気泡径に実質的な差があればよく特に限定されないが、一般的には０．１５〜０．５mm、より好ましくは０．２〜０．４mmの範囲内から選択される。
【００２９】
本発明の建築用断熱材の異なる平均気泡径の発泡粒子は、２種類あるいは３種類以上でもよい。
【００３０】
本発明の建築用断熱材の発泡粒子成型体の厚みは、用途に依存し、特に限定されないが、一般的には、２０〜１５０mmの範囲内から選択される。
【００３１】
本発明の発泡体を製造する方法は、基本的に慣用の型内発泡法において二次発泡後に平均気泡径が異なる一次発泡粒子を混合使用すればよく、特に限定されるものではないが、以下に例として説明する。
【００３２】
懸濁重合法若しくは含浸法、または押出機内でポリスチレンの溶融した状態下で発泡剤、溶剤を混合し、実質的に発泡しない温度で発泡ガスを注入したビーズ状又はペレット状原料を予備発泡機にて所定の密度の予備発泡粒子に蒸気発泡させる。熟成養生後、気泡径の小さな粒子と気泡径の大きな粒子を金型内に充填し、スチーム等の熱媒体によって加熱して気泡径の小さな粒子と大きな粒子の混じった成型体とすることにより、熱伝導率が良好で低密度な発泡成型体の製造が可能であることを見出した。詳しくは、例えば、
１）同一の原料樹脂で揮発性発泡ガスの種類が異なる原料を使用し、別々に予備発泡した予備発泡粒子を混合し金型内に充填し成型する。
【００３３】
２）同一の原料樹脂で気泡調整剤の添加量が異なる原料を使用し、別々に予備発泡した予備発泡粒子を混合し金型内に充填し成型する。
【００３４】
３）同一の原料樹脂で作製された発泡性粒子の熟成（アニーリング）時間が異なる原料を使用し、別々に予備発泡した予備発泡粒子を混合し金型内に充填し成型する。
【００３５】
ここで、上記は同時に予備発泡した予備発泡粒子を金型内に充填し成型しても良い。また、予備発泡粒子の大きさは異なっていても良い。
【００３６】
また、本発明においては、ポリスチレン系樹脂発泡粒子成型体内に輻射を低減する添加剤を含有させることが好ましい。低密度のポリスチレン系樹脂発泡粒子成型体において熱伝導率を低下させるために特に問題になる輻射熱の伝播を低減して発泡体の全体としての熱伝導率を所望に低減させるためである。
【００３７】
本発明では、輻射低減添加剤としては、カーボンブラック、グラファイトを好適に用いることができる。しかしながら、白色系の酸化チタン等の屈折率の大きな物質を添加することによっても熱線を散乱減衰させるため輻射を低減させる効果がある。
【００３８】
本発明のポリスチレン系樹脂発泡粒子成型体に輻射低減添加剤を含有させる場合、日射により断熱材の温度が上昇しすぎて変形が発生する恐れがあるので、成型体の厚み方向の上下表面だけあるいは周囲だけは輻射低減添加剤を含有しない発泡粒子層で構成することが好ましい。このように上下表面だけあるいは周囲は輻射低減添加剤を含有しない発泡粒子層で構成する方法としては、例えば、成型体の厚み方向の上下表面だけを輻射低減剤を含有しない発泡粒子層で構成するためには、先ず輻射低減剤を含有しない一次発泡粒子を金型底部に充填し、続いて輻射低減剤を含有する一次発泡粒子を金型に充填し、最後にまた輻射低減剤を含有しない一次発泡粒子を金型に充填し、蒸気加熱することにより発泡粒子成型体が得られる方法を採用すればよい。その場合、輻射低減効果を十分に達成するためには輻射低減添加剤を含有しない発泡粒子層の体積が成型体全体の５０体積％以下であることが好ましい。
【００３９】
輻射低減添加剤を添加し、さらには輻射低減添加剤を含む発泡粒子成型体層の少なくとも上下面に当該添加剤を含まない発泡粒子層を形成することにより、断熱材の熱伝導率を顕著に低減する効果を得ると共に、輻射低減添加剤に起因する日射吸収による温度上昇を防ぎ、仮置き時、施工時、施工後に日射により反り等の寸法変化が生じないようにすることができる。
【００４０】
また、本発明のポリスチレン系樹脂発泡粒子成型体には、必要に応じて気泡の大きさを調整するためタルク、珪酸カルシウムなどの気泡調整剤、難燃性を付与するためヘキサブロモドデカン、モノクロロペンタブロモシクロヘキサンの如き難燃剤などを添加することができる。
【００４１】
本発明によれば、フロンガスなどの環境に影響を及ぼす発泡剤を用いることなしで、発泡粒子成型体の密度３８Kg／ｍ^３以下且つ製造後１週間経過後にＪＩＳ−Ａ−９５１１に規定された熱伝導率の測定方法による熱伝導率０．０２８Ｗ／m・K 以下の実用的なポリスチレン系樹脂発泡粒子成型体からなる建築用断熱材が低コストで製造できる。発泡成型体の密度としてはさらに３５Kg／ｍ^３以下、特に３２Kg／ｍ^３以下あるいは３０Kg／ｍ^３以下でも、熱伝導率０．０２８Ｗ／m・K 以下を達成することができる。熱伝導率も０．０２７Ｗ／m・K 以下、さらには０．０２６Ｗ／m・K 以下を達成することも可能である。
【００４２】
【実施例】
実施例１
水２０００部、懸濁剤として９５部のＮ−ビニルピロリドンと５部のアクリル酸メチルエステル、ならびに２部のピロりん酸ナトリウムからなるコポリマー３２部、スチレンモノマー１０００部及び触媒としてベンゾイルパーオキサイドを４５部を耐圧容器に入れ、かき混ぜながら７０℃で２０時間、続いて８５℃で１５時間加熱し、更に７０℃で１１時間重合させた後、２時間の間にペンタン７重量部を反応容器に入れ、重合を完了した。発泡性ポリスチレン樹脂粒子を耐圧容器から取りだし養生後に蒸気で加熱することにより一次発泡させ一次発泡粒子Ａを得た。
【００４３】
平均径約１mmのポリスチレン樹脂１００重量部に発泡剤としてブタン８重量部、トルエン２重量部の組成で水分散系オートクレーブ内で含浸して、発泡性ポリスチレン樹脂を得た。この得られた発泡性ポリスチレン樹脂をフリーザー中で５日間放置した後、蒸気で加熱することにより、一次発泡させ一次発泡粒子Ｂを得た。
【００４４】
一次発泡粒子Ａ及びＢを１日養生後、Ａ：Ｂ＝５０：５０の割合で混合し金型の中に充填し、蒸気加熱することにより成型品を得た。該成型品を６０℃オーブン中で１週間保存し、水分等を除去した後、密度、気泡径、熱伝導率、赤外線照射による表面温度及び反りの発生について評価し、第１表に示した。
【００４５】
得られた成型品の物性を下記の方法で測定した。
【００４６】
（密度）
発泡体密度＝発泡体重量／発泡体体積
（気泡径）
ＡＳＴＭＤ３５６７に準じて測定
（熱伝導率）
ＪＩＳＡ９５１１に準じて測定
（片面加熱試験）
表面温度：赤外線ランプで成型品表面を約１時間照射し、定常状態で表面温度を測定
反り：そのときの反りの発生をノギスで測定
実施例２
実施例１の一次発泡粒子Ａと一次発泡粒子Ｂとを１０：９０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例３
実施例１の一次発泡粒子Ａと一次発泡粒子Ｂとを９０：１０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例４〜５
一次発泡の蒸気加熱時間を変えた以外は同様な方法により得られた実施例１の一次発泡粒子Ａと発泡性ポリスチレン樹脂をフリーザー中で３日間放置した以外は実施例１と同様な方法により得られた一次発泡粒子Ｂとを５０：５０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例６
実施例１の一次発泡粒子Ａと発泡性ポリスチレン樹脂をフリーザー中で８日間放置した以外は実施例１と同様な方法により得られた一次発泡粒子Ｂとを５０：５０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例７
一次発泡の蒸気加熱時間を長くした以外は同様な方法により得られた実施例１の一次発泡粒子Ａと実施例１の一次発泡粒子Ｂとを５０：５０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例８
実施例１の一次発泡粒子Ａと同じ懸濁法により得られた発泡性粒子の蒸気加熱時間を長くした以外は同様にして一次発泡粒子Ｃを得た。一次発泡粒子Ａ：Ｂ：Ｃを２５：５０：２５の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
実施例９
ポリスチレン樹脂１００重量部に対してカーボンブラック７重量部を含む含浸法による未発泡粒子を実施例１の一次発泡粒子Ｂと同様な方法により得てＢ９とした。Ａ粒子、Ｂ９粒子、Ａ粒子の順で２５：５０：２５の割合で金型中に充填し、蒸気加熱することにより上下面がＡ粒子層で構成された成型品を得た。
実施例１０
実施例９のＡ粒子、Ｂ９粒子、Ａ粒子の順で１０：８０：１０の割合で金型中に充填した以外は、実施例９と同様に実施した。
実施例１１
実施例９のカーボンブラックに代えてグラファイトを用いた以外は実施例９と同様に実施した。
実施例１２
実施例９のカーボンブラックに代えて酸化チタンを用いた以外は実施例９と同様に実施した。
比較例１
ポリスチレン樹脂１００重量部に対してタルク０．１重量部、ステアリン酸バリウム０．０５重量部を混合した混合物を単軸押出機ホッパーより投入し、ブタン３重量部、ペンタン１重量部、二酸化炭素２．５重量部を圧入し十分に混練した後均一に冷却し、ダイより押出発泡した。密度、気泡径、熱伝導率、赤外線照射による表面温度及び反りの発生について評価し、第１表に示した。
比較例２
ポリスチレン樹脂１００重量部に対してカーボンブラックを７重量部を追加して添加した以外は比較例１と同様に実施した。
比較例３
実施例１で得られた一次発泡粒子Ａのみを金型中に充填した以外は実施例１と同様に実施した。
比較例４
実施例４で得られた一次発泡粒子Ｂのみを金型中に充填した以外は実施例１と同様に実施した。
比較例５
一次発泡の蒸気加熱時間を変えた以外は実施例１と同様な方法により得られた一次発泡粒子Ａと発泡性ポリスチレン樹脂をフリーザー中で３日間放置した以外は実施例１と同様な方法により得られた一次発泡粒子Ｂとを５０：５０の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
比較例６
実施例１で得られた一次発泡粒子Ａと一次発泡粒子Ｂとを５：９５の割合で混合し金型中に充填した以外は実施例１と同様に実施した。
参考例
実施例９のＢ９粒子、Ａ粒子、Ｂ９粒子の順で２５：５０：２５の割合で金型中に充填した以外は、実施例９と同様に実施した。
【００４７】
表１から明らかなように、本発明による低密度で熱伝導率、寸法安定性の良好な成型体が得られた。
【００４８】
【表１】

【００４９】
【発明の効果】
本発明によれば、フロンガス等の環境に影響を及ぼす発泡ガスを使用せずに、低密度、低コストで優れた断熱性と寸法安定性を有する成型性の良好な成型体が得られる。また、気泡径の大きい発泡粒子を混合しているため、その気泡膜の厚みが厚いため比較的圧縮強度等の機械的強度の高いものが得られる。
【図面の簡単な説明】
【図１】本発明のポリスチレン系樹脂粒発泡粒子成型体の模式断面図である。
１…大気泡粒子
２…小気泡粒子
３…融着層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat insulating material for buildings, and more specifically, relates to a synthetic resin foam made of a polystyrene resin foamed particle molded body having a good thermal conductivity and a low density suitable as a heat insulating material for buildings.
[0002]
[Prior art]
Thermoplastic resin foams are roughly classified into the following two methods: extrusion foaming and in-mold foaming.
[0003]
Extrusion foaming method: Extruded plate-like thermoplastic resin foam is made by melting thermoplastic resin in an extruder under high temperature and high pressure, then injecting foaming gas, and dispersing and dissolving in the resin to form a fluid gel. Then, this is extruded from a die of an extruder into a low pressure region and rapidly foamed and cooled to obtain a plate-like product.
[0004]
Conventionally, as a foaming agent, chlorine fluorinated hydrocarbons or fluorinated hydrocarbons (hereinafter collectively referred to as chlorofluorocarbons) having low thermal conductivity are used, and products with good thermal conductivity have been obtained by encapsulating them in foams. It was.
[0005]
Further, by adding a mineral fine powder having a hydroxyl group to the surface layer and press-fitting water into the extruder, a synthetic resin extruded foam in which large and small bubbles are dispersed in a sea-island shape through a cell membrane may be obtained. Proposed. However, since this method uses water, corrosion in the extruder system, particularly when water is used in combination with a halogen-based additive such as a flame retardant, becomes a problem. There is a problem that requires. Furthermore, since the dispersion of water in the resin is not good, it is very difficult to control the ratio of the large and small bubble diameters at a constant level, and there is a problem that the product becomes unstable in quality. That is, there is a problem that the apparatus is high and quality stability is poor.
[0006]
In-mold foaming method: Thermoplastic synthetic resin foamed molded body is prepared by pre-foaming a bead-like or pellet-like raw material in which foaming gas is injected by suspension polymerization method or impregnation method. After foaming and foaming the foamed particles, filling them into the mold cavity, and subsequently blowing water vapor to soften the pre-expanded particles and fusing the pre-expanded particles with secondary expansion pressure This is a method of forming and then cooling to obtain a product.
[0007]
[Problems to be solved by the invention]
In recent years, the use of chlorofluorocarbons has been regarded as a problem for foams obtained by the extrusion foaming method from the viewpoint of ozone layer destruction and global warming. However, foams that do not use Freon have a problem that it is difficult to obtain good thermal conductivity. In addition, in order to obtain a foam with good thermal conductivity without using chlorofluorocarbon, in order to improve thermal conductivity by radiation, a heat ray absorbent such as carbon black is added, and a heat ray reflector such as graphite is added. Although a method has been proposed, there is a problem that the surface temperature of the foam plate rises and warpage occurs when the foam plate is temporarily placed outdoors or when it is left on the rooftop. .
[0008]
In order to produce a molded article with good thermal conductivity used as a heat insulating material for buildings, it is necessary to reduce the bubble diameter and reduce radiation. However, if the bubble diameter is reduced, the density increases and the extrusion method In this case, there is a problem that a predetermined large cross-sectional size cannot be obtained.
[0009]
Therefore, the present invention provides a molded article having good moldability having excellent heat insulation and dimensional stability at low density and low cost without using a foaming gas that affects the environment such as chlorofluorocarbon gas. Objective.
[0010]
[Means for Solving the Problems]
In order to obtain a low-cost polystyrene-based resin foam plate having good thermal conductivity, good dimensional stability and no problem in construction without using chlorofluorocarbon, the present inventors have a small bubble diameter by the in-mold foaming method. It has been found that a polystyrene-based resin foam particle molded body produced by mixing particles and particles having a large bubble diameter and further using an additive for reducing radiation is the best.
[0011]
Thus, the present invention provides the following.
[0012]
(1) A polystyrene-based resin foam particle molded body composed of two or more kinds of foam particles having different average cell diameters, and the volume ratio of the cell particles having an average cell diameter of 0.15 mm or less is 10% or more. Thermal insulation for buildings characterized by
[0013]
(2) The building heat insulating material according to (1), wherein the foamed particles contain a radiation reducing agent.
[0014]
(3) The architectural heat insulating material according to (2), wherein the radiation reducing agent is carbon black or graphite.
[0015]
(4) The polystyrene-based resin foamed particle molded body contains a radiation reducing agent, and at least upper and lower surfaces in the thickness direction of the molded body are composed of a foamed particle layer not containing the radiation reducing agent (2). (3) The heat insulating material for construction as described.
[0016]
(5) The foamed particle layer not containing the radiation reducing agent is 50% or less with respect to the total volume of the thermoplastic resin foamed particle molded body, and is for construction as described in (2) to (4) Insulation.
[0017]
(6) The building heat insulating material according to any one of (1) to (5), wherein the density of the molded body is 35 kg / m ³ or less and the thermal conductivity is 0.028 W / m · K or less. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The heat insulating material for building of the present invention comprises a polystyrene-based resin foam particle molded body. Polystyrene-based resin foamed particles are lightweight and have excellent moldability, stable quality, and other characteristics, and are therefore frequently used as heat insulating materials for buildings.
[0019]
Examples of the polystyrene resin used in the present invention include styrene derivatives such as styrene, α-methylstyrene, chlorostyrene, dichlorostyrene, dimethylstyrene, t-butylstyrene, vinyltoluene, or combinations of two or more thereof. Or a copolymer of these with a compound that can be easily polymerized with others such as acrylic acid, acrylic ester, methacrylic acid, maleic anhydride, or butadiene.
[0020]
The foaming agent of the molded polystyrene-based foamed particle of the present invention is a compound other than chlorofluorocarbon, that is, a compound that has an influence on the environment such as chlorinated or fluorinated hydrocarbon and is refrained from use.
[0021]
Examples of these foaming agents that are not preferable in terms of environment include, but are not limited to, physical foaming agents. Examples of the physical foaming agent include aliphatic hydrocarbons such as propane, butane, pentane, and hexane.
[0022]
In the molded polystyrene resin particle molded body of the present invention, the amount of the foaming agent is generally preferably in the range of about 3 to 30 parts by weight per 100 parts by weight of the polystyrene resin.
[0023]
The heat insulating material for building of the present invention is characterized in that it is composed of a polystyrene-based resin-molded expanded particle molded body containing expanded particles having different average cell diameters.
[0024]
FIG. 1 schematically shows an enlarged part of the cross-sectional structure of a foamed polystyrene resin-molded molded body containing foamed particles having different average cell diameters according to the present invention. The particles 2 are present in a mixed state, and the respective expanded particles 1 and 2 are fused to each other during the in-mold secondary foam molding. Reference numeral 3 denotes a fusion layer. The large bubble particles 1 and the small bubble particles 2 are each composed of bubbles having a relatively uniform diameter due to the in-mold foaming method, and the average bubble diameter is also relatively uniform.
[0025]
If the bubble diameter of the foam is reduced, the number of bubble films in the heat transfer direction increases, and radiation can be reduced, resulting in a decrease in thermal conductivity. On the other hand, if the bubble diameter of the foam is increased, the thickness of the bubble film increases, the tension of the film during foaming decreases, and the density can be reduced without breaking the bubble film. On the other hand, if the bubble diameter is large, the bubble film thickness is increased, which provides good dimensional stability and mechanical strength. However, according to the present invention, it is possible to produce a foam having a low density and a good thermal conductivity by constituting as an in-mold foam particle molded body containing a mixture of foam particles having different average cell diameters. In addition, according to the present invention, it is only necessary to change the kind of primary foam particles and mix them, so that it is possible to easily obtain a foam plate in which foam particles having a desired cell diameter are distributed as desired throughout the molded body. The cell diameters of the expanded particles and their volume ratios have the advantage that they can be tailored as desired.
[0026]
Two or more types of foam particles having different average cell diameters in the molded polystyrene resin foam particle molded body of the building heat insulating material of the present invention are foam particles having the smallest average cell diameter and foam particles having the largest average cell diameter. It is preferable that the average cell diameter is 0.9 times or less, preferably 0.8 times or less, more preferably 0.7 times or less of the average cell diameter. If the difference in cell diameter between the large and small average cell diameters is small, desired characteristics such as low density, low thermal conductivity, and dimensional stability, which are the objects of the present invention, cannot be achieved. The upper limit of the difference in the average cell diameter of the expanded particles may be determined from a practical viewpoint, but it is preferable that the minimum average cell diameter is 0.2 times or more the maximum average cell diameter. If it is less than 0.2 times, the physical properties of the expanded particles having the smallest average cell diameter and the expanded particles having the largest average cell size are too different to be molded, and even if the minimum average cell size is too small, the density is too small. The thermal conductivity tends to be inferior even when the maximum average bubble diameter is too large.
[0027]
However, in order to achieve particularly good thermal conductivity (low thermal conductivity), it is necessary that the foamed particles having an average cell diameter of 0.2 mm or less occupy 10% by volume or more. If this requirement is not satisfied, there is no point in mixing two or more types of foam particles having a large and small cell diameter in achieving the object of the present invention. If the foamed particles having an average cell diameter of 0.15 mm or less are not contained in an amount of 10% by volume or more, the effect of reducing the radiant heat of the foam containing no chlorofluorocarbon as desired cannot be obtained sufficiently. Further, it is preferable that the foamed particles having an average cell diameter of 0.15 mm or less are contained in an amount of 20% by volume or more, further 30% by volume or more, and particularly 40% by volume or more. However, even if there are too many foamed particles having an average cell diameter of 0.15 mm or less, the density is increased, so that the volume occupied by the foamed particles having an average cell diameter of 0.15 mm or less is generally 90%. The volume is set to not more than volume%, preferably not more than 80 volume%, further not more than 70 volume%, particularly not more than 60 volume%.
[0028]
The average cell diameter of the foam particles having the larger average cell diameter in the building insulation material of the present invention is not particularly limited as long as there is a substantial difference in the average cell diameter with respect to the expanded particles having a small average cell diameter, Generally, it is selected from the range of 0.15 to 0.5 mm, more preferably 0.2 to 0.4 mm.
[0029]
Two or more types of foamed particles having different average cell diameters of the heat insulating material for building of the present invention may be used.
[0030]
The thickness of the foamed particle molded body of the building heat insulating material of the present invention depends on the application and is not particularly limited, but is generally selected from the range of 20 to 150 mm.
[0031]
The method for producing the foam of the present invention is basically not particularly limited as long as primary foam particles having different average cell diameters after secondary foaming are mixed and used in a conventional in-mold foaming method. Will be described as an example.
[0032]
In the pre-foaming machine, bead-like or pellet-like raw materials in which a foaming agent and a solvent are mixed in a suspension polymerization method or impregnation method or in a state where polystyrene is melted in an extruder and a foaming gas is injected at a temperature that does not substantially foam. And vapor-foamed into pre-expanded particles of a predetermined density. After aging and curing, filling the mold with small bubbles and particles with large bubbles and heating with a heat medium such as steam to form a mixture of small bubbles and large particles, It has been found that it is possible to produce a foam molded article having a good thermal conductivity and a low density. Specifically, for example,
1) Using raw materials having the same raw material resin and different types of volatile foaming gases, separately pre-foamed pre-foamed particles are mixed, filled in a mold and molded.
[0033]
2) Using raw materials with the same raw material resin and different addition amount of the air conditioning agent, separately pre-expanded pre-expanded particles are mixed, filled in a mold and molded.
[0034]
3) Using raw materials having different aging (annealing) times of expandable particles made of the same raw material resin, separately pre-expanded pre-expanded particles are mixed, filled in a mold, and molded.
[0035]
Here, the above-mentioned pre-expanded particles may be filled in a mold and molded at the same time. Moreover, the size of the pre-expanded particles may be different.
[0036]
Moreover, in this invention, it is preferable to contain the additive which reduces radiation in the polystyrene-type resin expanded particle molding. This is because the propagation of radiant heat, which is a particular problem in reducing the thermal conductivity of the low-density polystyrene resin foam particle molded body, is reduced, and the overall thermal conductivity of the foam is reduced as desired.
[0037]
In the present invention, carbon black and graphite can be suitably used as the radiation reducing additive. However, adding a substance having a large refractive index such as white titanium oxide also has the effect of reducing radiation because it scatters and attenuates heat rays.
[0038]
When the radiation-reducing additive is contained in the polystyrene resin foamed particle molded body of the present invention, since the temperature of the heat insulating material may rise too much due to solar radiation, only the upper and lower surfaces in the thickness direction of the molded body or It is preferable that only the periphery is composed of a foamed particle layer that does not contain a radiation reducing additive. As described above, as a method of forming only the upper and lower surfaces or the surroundings with the expanded particle layer not containing the radiation reducing additive, for example, only the upper and lower surfaces in the thickness direction of the molded body are configured with the expanded particle layer not containing the radiation reducing agent. For this purpose, firstly, the primary foam particles containing no radiation reducing agent are filled in the bottom of the mold, then the primary foam particles containing the radiation reducing agent are filled in the mold, and finally, the primary foam containing no radiation reducing agent is also contained. What is necessary is just to employ | adopt the method of filling a foaming particle into a metal mold | die and obtaining a foamed particle molded object by carrying out steam heating. In that case, in order to sufficiently achieve the radiation reduction effect, the volume of the expanded particle layer not containing the radiation reduction additive is preferably 50% by volume or less of the entire molded body.
[0039]
By adding a radiation-reducing additive, and further forming a foamed particle layer that does not contain the additive on at least the upper and lower surfaces of the foamed particle molded body layer containing the radiation-reducing additive, the thermal conductivity of the heat insulating material is remarkably increased. While obtaining the effect to reduce, the temperature rise by the solar radiation absorption resulting from a radiation reduction additive can be prevented, and dimensional changes, such as curvature, can be prevented by solar radiation at the time of temporary placement, construction, and construction.
[0040]
In addition, the polystyrene resin foamed particle molded body of the present invention includes a bubble regulator such as talc and calcium silicate for adjusting the size of bubbles as needed, hexabromododecane and monochloropenta for imparting flame retardancy. Flame retardants such as bromocyclohexane can be added.
[0041]
According to the present invention, without using a foaming agent that affects the environment such as Freon gas, the density of the foamed particle molded body is 38 kg / m ³ or less and the heat specified in JIS-A-9511 after one week has elapsed after production. The heat insulating material for construction which consists of a practical polystyrene-type resin foaming particle molding whose thermal conductivity is 0.028 W / m * K or less by the measuring method of conductivity can be manufactured at low cost. Foam further 35 Kg / ^{m 3} or less as the density of the molded body, in particular 32 kg / ^{m 3} at less or 30 Kg / ^{m 3} or less, to achieve the following thermal conductivity of 0.028W / m · K. It is also possible to achieve a thermal conductivity of 0.027 W / m · K or less, and further 0.026 W / m · K or less.
[0042]
【Example】
Example 1
2000 parts of water, 95 parts of N-vinylpyrrolidone and 5 parts of acrylic acid methyl ester as a suspending agent, 32 parts of a copolymer consisting of 2 parts of sodium pyrophosphate, 1000 parts of styrene monomer and 45 parts of benzoyl peroxide as a catalyst The mixture was placed in a pressure vessel, heated at 70 ° C. for 20 hours with stirring, then heated at 85 ° C. for 15 hours, further polymerized at 70 ° C. for 11 hours, and then 7 parts by weight of pentane in 2 hours. The polymerization was complete. The expandable polystyrene resin particles were taken out from the pressure vessel, and after curing, heated with steam to perform primary foaming to obtain primary foamed particles A.
[0043]
100 parts by weight of polystyrene resin having an average diameter of about 1 mm was impregnated in an aqueous dispersion autoclave with a composition of 8 parts by weight of butane and 2 parts by weight of toluene as a foaming agent to obtain an expandable polystyrene resin. The obtained expandable polystyrene resin was left in a freezer for 5 days and then heated with steam to perform primary foaming to obtain primary foamed particles B.
[0044]
After the primary foamed particles A and B were cured for 1 day, they were mixed at a ratio of A: B = 50: 50, filled in a mold, and heated by steam to obtain a molded product. The molded product was stored in an oven at 60 ° C. for 1 week, and after removing moisture and the like, the density, bubble diameter, thermal conductivity, surface temperature due to infrared irradiation and generation of warp were evaluated, and are shown in Table 1.
[0045]
The physical properties of the obtained molded product were measured by the following methods.
[0046]
(density)
Foam density = foam weight / foam volume (bubble diameter)
Measured according to ASTM D 3567 (thermal conductivity)
Measured according to JIS A 9511 (single side heating test)
Surface temperature: The surface of the molded product is irradiated with an infrared lamp for about 1 hour, and the surface temperature is measured in a steady state. Warpage: The occurrence of warpage is measured with calipers.
The same procedure as in Example 1 was performed except that the primary foamed particles A and the primary foamed particles B of Example 1 were mixed at a ratio of 10:90 and filled in a mold.
Example 3
The same procedure as in Example 1 was performed except that the primary foamed particles A and the primary foamed particles B of Example 1 were mixed at a ratio of 90:10 and filled in a mold.
Examples 4-5
Example 1 obtained by the same method as in Example 1 except that the primary foamed particles A and the expandable polystyrene resin obtained in the same manner as in Example 1 were left in a freezer for 3 days except that the steam heating time for primary foaming was changed. The same procedure as in Example 1 was conducted except that the obtained primary expanded particles B were mixed at a ratio of 50:50 and filled in a mold.
Example 6
The primary foamed particles A of Example 1 and the foamable polystyrene resin were mixed in a ratio of 50:50 with the primary foamed particles B obtained by the same method as in Example 1 except that the foamed polystyrene resin was left in a freezer for 8 days. The same operation as in Example 1 was carried out except that the inside was filled.
Example 7
The primary foamed particles A of Example 1 and the primary foamed particles B of Example 1 obtained by the same method except that the steam heating time for primary foaming was lengthened were mixed in a ratio of 50:50 and filled in the mold. The same operation as in Example 1 was performed except that.
Example 8
Primary expanded particles C were obtained in the same manner except that the steam heating time of the expandable particles obtained by the same suspension method as that of the primary expanded particles A of Example 1 was increased. The process was performed in the same manner as in Example 1 except that the primary expanded particles A: B: C were mixed at a ratio of 25:50:25 and filled in the mold.
Example 9
Unfoamed particles obtained by the impregnation method containing 7 parts by weight of carbon black with respect to 100 parts by weight of polystyrene resin were obtained in the same manner as the primary expanded particles B of Example 1, and designated as B9. The mold was filled in the mold in the order of A particles, B9 particles, and A particles in a ratio of 25:50:25, and heated to obtain a molded product having upper and lower surfaces composed of A particle layers.
Example 10
The same procedure as in Example 9 was performed, except that the mold was filled in a ratio of 10:80:10 in the order of A particles, B9 particles, and A particles in Example 9.
Example 11
The same operation as in Example 9 was performed except that graphite was used in place of the carbon black of Example 9.
Example 12
The same operation as in Example 9 was performed except that titanium oxide was used in place of the carbon black of Example 9.
Comparative Example 1
A mixture obtained by mixing 0.1 part by weight of talc and 0.05 part by weight of barium stearate with respect to 100 parts by weight of polystyrene resin is charged from a single screw extruder hopper, 3 parts by weight of butane, 1 part by weight of pentane, 2 carbon dioxide .5 parts by weight was press-fitted and kneaded sufficiently, then cooled uniformly, and extruded and foamed from a die. The density, bubble diameter, thermal conductivity, surface temperature due to infrared irradiation and generation of warp were evaluated and are shown in Table 1.
Comparative Example 2
The same operation as in Comparative Example 1 was conducted except that 7 parts by weight of carbon black was added to 100 parts by weight of polystyrene resin.
Comparative Example 3
The same operation as in Example 1 was carried out except that only the primary expanded particles A obtained in Example 1 were filled in the mold.
Comparative Example 4
The same operation as in Example 1 was performed except that only the primary expanded particles B obtained in Example 4 were filled in the mold.
Comparative Example 5
Obtained by the same method as in Example 1 except that the primary foamed particles A obtained by the same method as in Example 1 and the expandable polystyrene resin were left in a freezer for 3 days except that the steam heating time for primary foaming was changed. The same procedure as in Example 1 was conducted except that the obtained primary expanded particles B were mixed at a ratio of 50:50 and filled in a mold.
Comparative Example 6
The same procedure as in Example 1 was performed except that the primary foamed particles A and the primary foamed particles B obtained in Example 1 were mixed at a ratio of 5:95 and filled in the mold.
Reference Example The same procedure as in Example 9 was performed except that the mold was filled in the order of B9 particles, A particles, and B9 particles in Example 9 at a ratio of 25:50:25.
[0047]
As is apparent from Table 1, a molded article having a low density, good thermal conductivity and good dimensional stability according to the present invention was obtained.
[0048]
[Table 1]

[0049]
【The invention's effect】
According to the present invention, it is possible to obtain a molded article with good moldability having excellent heat insulation and dimensional stability at low density and low cost without using a foaming gas such as chlorofluorocarbon gas. In addition, since foamed particles having a large bubble diameter are mixed, the thickness of the bubble film is thick, so that a relatively high mechanical strength such as compressive strength can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a molded polystyrene resin particle foam particle body of the present invention.
DESCRIPTION OF SYMBOLS 1 ... Large bubble particle 2 ... Small bubble particle 3 ... Fusion layer

Claims

It is a polystyrene-based resin foam particle molded body composed of two or more types of foam particles having different average cell diameters, and the volume ratio of the cell particles having an average cell diameter of 0.15 mm or less is 10% or more. Building insulation.

The building heat insulating material according to claim 1, wherein the foamed particles contain a radiation reducing agent.

The heat insulating material for building according to claim 2, wherein the radiation reducing agent is carbon black or graphite.

The building according to claim 2 or 3, wherein the foamed particle molded body contains a radiation reducing agent, and at least the upper and lower surfaces in the thickness direction of the molded body are composed of a foamed particle layer containing no radiation reducing agent. Insulation.

The building according to any one of claims 2 to 4, wherein the foamed particle layer not containing the radiation reducing agent is 50% or less with respect to the total volume of the thermoplastic resin foamed particle molded body. Insulation.

The density of the said molded object is 35 kg / m < ³ > or less, and thermal conductivity is 0.028 W / m * K or less, The heat insulating material for buildings of any one of Claims 1-5 characterized by the above-mentioned. .