JP4101684B2 - Styrenic resin foam plate and manufacturing method thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、断熱性及び難燃性に優れたスチレン系樹脂発泡板及びその製造方法に関する。
【０００２】
【従来の技術】
従来からスチレン系樹脂発泡板は建築用断熱材に汎用されており、このスチレン系樹脂発泡板は、スチレン系樹脂を押出機に供給して溶融、混練した後、この溶融状態のスチレン系樹脂に発泡剤を圧入した上で押出機から押出発泡させて製造されている。
【０００３】
そして、上記発泡剤としては、ジクロロジフルオロメタン（フロン−１２）等の塩素原子含有ハロゲン化炭化水素（ＣＦＣ）が用いられていたが、オゾン層を破壊するという環境上の問題点があることから、１−モノクロロ−１，１−ジフルオロエタン（フロン−１４２ｂ）等の塩素原子を部分的に水素化した水素原子含有ハロゲン化炭化水素（ＨＣＦＣ）への改善が試みられ、更に、ＨＣＦＣから１、１，１，２−テトラフルオロエタン（フロン−１３４ａ）等のフッ素化炭化水素（ＨＦＣ）への転換が行われている。
【０００４】
加えて、発泡剤のノンフロン化を図るために、塩化メチルや塩化エチル等のハロゲン化炭化水素と、ブタンやプロパン等の炭化水素とを組み合わせた発泡剤の使用も行われているが、塩化メチルや塩化エチル等は塩素原子を含んでいることから、環境上、可能であれば代替されることが好ましいとされている。
【０００５】
そこで、特許文献１には、ジメチルエーテル等のエーテル類及びブタンやプロパン等の炭化水素からなる発泡剤及び水を用いて製造された、大小径気泡が共存するセル構造を有するスチレン系樹脂発泡体が提案されている。
【０００６】
しかしながら、上記スチレン系樹脂発泡体は、ＪＩＳ Ａ９５１１で規定されたＢ類２種程度の断熱性しか有せず、断熱性に劣るものであって、ノンフロンの発泡剤を用いて製造された断熱性に優れたスチレン系樹脂発泡板が所望されていた。
【０００７】
【特許文献１】
ＷＯ９９／５４３９０（特許請求の範囲）
【０００８】
【発明が解決しようとする課題】
本発明は、断熱性及び難燃性に優れ、特に、断熱性にあっては、ＪＩＳ Ａ９５１１で規定されたＢ類３種を満たす優れた断熱性を有し、建築用断熱材等に好適に用いることができるスチレン系樹脂発泡板及びその製造方法を提供する。
【０００９】
【課題を解決するための手段】
本発明のスチレン系樹脂発泡板は、ジメチルエーテル、ブタン及び水からなる発泡剤を用いて押出発泡により製造されたスチレン系樹脂発泡板であって、スチレン系樹脂１００重量部に対してヘキサブロモシクロドデカン２．０〜４．０重量部及び合成雲母０．３〜３．０重量部を含有し、且つ、少なくとも一つの表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が０．０５〜０．２０ｍｍであると共に、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、上記表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径の１．４５〜２．５０倍であることを特徴とする。
【００１０】
上記スチレン系樹脂発泡板の少なくとも一つの表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径は、小さいと、中心層の気泡における厚み方向の平均気泡径が小さくなって厚みの厚いスチレン系樹脂発泡板とすることができず、又、大きいと、気泡壁による熱の遮断回数が少なくなってしまってスチレン系樹脂発泡板の断熱性が低下するので、０．０５〜０．２０ｍｍに限定され、０．０８〜０．１５ｍが好ましい。なお、スチレン系樹脂発泡板の二つの表面の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、０．０５〜０．２０ｍｍに限定され、０．０８〜０．１５ｍとされるのが好ましい。
【００１１】
又、上記スチレン系樹脂発泡板の中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径は、上記表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径の１．４５〜２．５０倍に限定され、１．５０〜２．３０倍が好ましく、１．５０〜２．００倍がより好ましい。
【００１２】
これは、スチレン系樹脂発泡板の中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、上記表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径の１．４５倍を下回ると、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径と、表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径との差が小さくなって、スチレン系樹脂発泡板の気泡径が全体的に小さくなり、厚みの厚いスチレン系樹脂発泡板を得ようとすると、気泡がスチレン系樹脂発泡板の厚み方向に長い紡錘形状となり、気泡壁による熱の遮断回数が少なくなってスチレン系樹脂発泡板の断熱性が低下し、或いは、スチレン系樹脂発泡板がその押出方向に収縮するといった問題点が発生するからである。
【００１３】
一方、スチレン系樹脂発泡板の中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、上記表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径の２．５０倍を上回ると、中心層の気泡径が大きくなり、気泡壁による熱の遮断回数が少なくなってスチレン系樹脂発泡板の断熱性が低下するからである。
【００１４】
なお、スチレン系樹脂発泡板の厚み方向とは、スチレン系樹脂発泡板の肉薄方向であって、スチレン系樹脂発泡板の表面に対する法線方向をいう。そして、スチレン系樹脂発泡板の表面層とは、スチレン系樹脂発泡板の表面と、この表面から厚み方向に４ｍｍだけ内側に入った部分との間にある部分をいい、又、スチレン系樹脂発泡板の中心層とは、スチレン系樹脂発泡板から、スチレン系樹脂発泡板の表面と、この表面から厚み方向に１０ｍｍだけ内側に入った部分との間にある部分を除いた残余部分をいう。
【００１５】
ここで、スチレン系樹脂発泡板の表面層又は中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径は下記の要領で測定されたものをいう。即ち、スチレン系樹脂発泡板を任意の箇所にて押出方向に直交する面で切断する。そして、スチレン系樹脂発泡板の切断面にて目的とする層、即ち、表面層又は中心層から任意に三点を選択し、この選択された三点のそれぞれについて電子顕微鏡を用いて２０倍の拡大写真を撮影する。
【００１６】
得られた拡大写真上に長さ８０ｍｍの直線を三本、スチレン系樹脂発泡板の厚み方向に任意に描き、各直線上にある気泡の数を数え、各直線毎に下記式に基づいて、スチレン系樹脂発泡板の厚み方向の気泡径を算出する。
【００１７】
そして、９本の直線のそれぞれから算出された、スチレン系樹脂発泡板の厚み方向の気泡径の平均を、表面層又は中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径とする。なお、直線上にある気泡の数を数える際、気泡の一部分が僅かでも直線上にある場合は一つとして数えた。
【００１８】
スチレン系樹脂発泡板の厚み方向の気泡径（ｍｍ）
＝８０／２０×ｎ（ｎ：直線上にある気泡の数）
【００１９】
上記スチレン系樹脂発泡板の表面層及び中心層における気泡構造としては、各層毎に均一な気泡径を有する気泡構造であっても、大きな気泡径の気泡（大径気泡）と小さな気泡径の気泡（小径気泡）とが同一層内において存在し、大径気泡が小径気泡中に不規則に存在している気泡構造であってもよいが、気泡壁による熱の遮断効果が高く、得られるスチレン系樹脂発泡板の断熱性が高いことから、大小径気泡が同一層内において存在し、大径気泡が小径気泡中に不規則に存在している気泡構造が好ましい。
【００２０】
上記スチレン系樹脂発泡板を構成するスチレン系樹脂としては、特に限定されず、例えば、スチレン、メチルスチレン、エチルスチレン、イソプロピルスチレン、ジメチルスチレン、クロロスチレン、ブロモスチレン等のスチレン系単量体の単独重合体又はこれらスチレン系単量体を２種以上組み合わせた共重合体；アクリル酸、メタクリル酸、アクリル酸メチル、メタクリル酸メチル、アクリロニトリル、無水マレイン酸、ブタジエン等の単量体と上記スチレン系単量体との共重合体等が挙げられる。なお、共重合体は、ブロック共重合体、ランダム共重合体、グラフト共重合体の何れであってもよい。又、上記スチレン系樹脂が５０重量％以上含有しておれば、スチレン系樹脂以外の熱可塑性樹脂を添加させてもよい。
【００２１】
なお、上記スチレン系樹脂発泡板には、その物性を損なわない範囲内において、タルク、炭酸カルシウム、珪酸カルシウム、酸化チタン、グラファイト、ベントナイト等の気泡調整剤；フェノール系抗酸化剤；耐光性安定剤；ヘキサブロモシクロドデカン等の難燃剤、リン系難燃剤等の難燃剤；ステアリン酸モノグリセライド等の帯電防止剤；顔料等の着色剤；ステアリン酸マグネシウム等の高級脂肪酸金属塩等の添加剤が含有されてもよい。なお、難燃剤としてヘキサブロモシクロドデカンを添加する場合には、スチレン系樹脂１００重量部に対して２．０〜４．０重量部が好ましい。
【００２２】
次に、スチレン系樹脂発泡板の製造方法を説明する。このスチレン系樹脂発泡板は、スチレン系樹脂１００重量部、ヘキサブロモシクロドデカン２．０〜４．０重量部及び合成雲母０．３〜３．０重量部を押出機に供給して溶融、混練し、この溶融状態のスチレン系樹脂中にジメチルエーテル６０〜８０重量％及びブタン２０〜４０重量％からなる有機系発泡剤３〜１５重量部及び水０．７〜１．５重量部を圧入した後、押出機に取り付けた金型のリップ先端温度を下記式を満たす温度に保持しつつ、上記金型から押出発泡することにより製造することができる。
押出機から吐出された樹脂温度−４０℃≦
金型のリップ先端温度≦押出機から吐出された樹脂温度−１５℃
【００２３】
そして、上記ヘキサブロモシクロドデカンの添加量は、少ないと、スチレン系樹脂発泡板の難燃性が低下し、又、多いと、表面層及び中心層における気泡を所定大きさに制御することができず、スチレン系樹脂発泡板の機械的強度や、スチレン系樹脂の発泡性が低下するので、スチレン系樹脂１００重量部に対して２．０〜４．０重量部が好ましく、２．５〜３．５重量部がより好ましい。
【００２４】
又、上記合成雲母は、天然の雲母とは異なり、天然の雲母の結晶構造中の全ての−ＯＨ基が−Ｆ基で置換された組成を有する人工的に作られた雲母であり、ＫＭｇ3 ＡｌＳｉ3 Ｏ10Ｆ2 を理想組成とするものである。
【００２５】
そして、合成雲母の平均粒径は、小さいと、嵩比重が小さくなり、押出機へ供給する際に凝集して樹脂中への分散が不十分となって、スチレン系樹脂発泡板内に合成雲母の凝集体が発生したり或いは連続気泡率が高くなることがあり、又、大きいと、スチレン系樹脂発泡板の気泡数が減少して平均気泡径が大きくなることがあるので、１〜５０μｍが好ましく、１〜２０μｍがより好ましく、１〜１０μｍが特に好ましい。
【００２６】
なお、上記合成雲母の平均粒径は、レーザー散乱法によって測定されたものをいい、具体的には、島津製作所社から商品名「ＳＡＬＤ−２１００」、日機装社から商品名「マイクロトラック ９３２０ＨＲＡ」で市販されている測定装置を用いて湿式法にて測定することができる。
【００２７】
そして、合成雲母の添加量は、少ないと、溶融状態のスチレン系樹脂に圧入した水が合成雲母に吸収されずに溶融状態のスチレン系樹脂から分離して押出機のシリンダ内面に付着し、スチレン系樹脂に対する押出機の推進力が低下して、押出発泡が不安定となり、又、多いと、合成雲母同士が凝集し、表面層及び中心層の気泡径を特定大きさで形成することが困難となってスチレン系樹脂発泡板の断熱性が低下するので、スチレン系樹脂１００重量部に対して０．３〜３．０重量部が好ましく、０．５〜２．０重量部がより好ましく、０．８〜１．５重量部が特に好ましい。
【００２８】
又、有機系発泡剤としては、ジメチルエーテル及びブタンからなるものが用いられる。上記ブタンとしては、イソブタン、ノルマルブタンが挙げられ、単独で用いられても併用されてもよい。
【００２９】
そして、ブタンとしてイソブタンとノルマルブタンとを併用する場合、ブタン中におけるイソブタンの含有量は、少ないと、スチレン系樹脂発泡板の断熱性が低下することがあるので、３０重量％以上が好ましく、５０重量％以上がより好ましい。
【００３０】
又、有機系発泡剤中におけるジメチルエーテルの含有量は、少ないと、相対的にブタン量が多くなってスチレン系樹脂発泡板の難燃性が低下し、又、多いと、相対的にブタン量が少なくなってスチレン系樹脂発泡板の断熱性が低下するので、６０〜８０重量％が好ましい。同様の理由で、有機系発泡剤中におけるブタンの含有量は、２０〜４０重量％が好ましい。
【００３１】
そして、上記有機系発泡剤の添加量は、少ないと、スチレン系樹脂発泡板の発泡倍率が低下して断熱性や軽量性が低下し、又、多いと、スチレン系樹脂発泡板内部にボイド（大きな空隙部）が生じるので、スチレン系樹脂１００重量部に対して３〜１５重量部が好ましい。
【００３２】
更に、溶融状態のスチレン系樹脂中に圧入される水は、特に限定されないが、不純物の少ないもの、例えば、純水を用いることが好ましい。なお、水の添加量は、スチレン系樹脂１００重量部に対して０．７〜１．５重量部が好ましく、０．９〜１．３重量部がより好ましい。
【００３３】
これは、水の添加量がスチレン系樹脂１００重量部に対して０．７重量部を下回ると、表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径と、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径との差が小さくなって、スチレン系樹脂発泡板の気泡径が全体的に小さくなり、厚みの厚いスチレン系樹脂発泡板を得ようとすると、気泡がスチレン系樹脂発泡板の厚み方向に長い紡錘形状となり、厚み方向の気泡数が減少して気泡壁による熱の遮断回数が少なくなってスチレン系樹脂発泡板の断熱性が低下し、或いは、スチレン系樹脂発泡板がその押出方向に収縮するといった問題点が発生する一方、水の添加量がスチレン系樹脂１００重量部に対して１．５重量部を上回ると、押出発泡時に押出変動が発生して良好なスチレン系樹脂発泡板を得ることができないからである。
【００３４】
又、上記有機系発泡剤及び水を溶融状態のスチレン系樹脂中に圧入するタイミングとしては、有機系発泡剤と水とをスチレン系樹脂中に同時に圧入しても別々に圧入してもよいが、有機系発泡剤を先にスチレン系樹脂中に圧入した後に水をスチレン系樹脂中に圧入するのが好ましい。
【００３５】
これは、水は、ヘキサブロモシクロドデカンを分解して難燃剤の効果を損なわせる作用があるため、押出機中における水とヘキサブロモシクロドデカンとの接触時間をできるだけ短くして、水によるヘキサブロモシクロドデカンの分解を最小限にとどめ、スチレン系樹脂発泡板の難燃性を向上させるためである。
【００３６】
そして、押出機に取り付けた金型のリップ先端温度を下記式を満たすように保持しつつ、金型から押出発泡している。
押出機から吐出された樹脂温度−４０℃≦
金型のリップ先端温度≦押出機から吐出された樹脂温度−１５℃
【００３７】
更に、押出機に取り付けた金型のリップ先端温度を下記式を満たすように保持しつつ、金型から押出発泡するのが好ましい。
押出機から吐出された樹脂温度−３５℃≦
金型のリップ先端温度≦押出機から吐出された樹脂温度−２０℃
【００３８】
なお、金型のリップ内に形成された冷却媒体流路には、該リップを冷却させるために、水やオイル等の冷却媒体を連続的に流通させており、この冷却媒体をリップの冷却媒体流路内に供給する時の温度を、金型のリップ先端温度とする。
【００３９】
そして、上記冷却媒体を金型のリップの冷却媒体流路内に流通させる流量は、冷却媒体流路内に流入する時の冷却媒体の温度と、冷却媒体流路から流出する時の冷却媒体の温度との差が、好ましくは５℃未満、より好ましくは３℃未満となるように調整する。
【００４０】
又、押出機 樹脂出口部に配設したブレーカプレートの中心部温度を熱電対を用いて測定し、この測定された温度を、押出機から吐出された樹脂温度とする。
【００４１】
これは、金型のリップ先端温度が、押出機から吐出された樹脂温度よりも４０℃を超えて低いと、金型のリップでスチレン系樹脂が固化して押出発泡することができない一方、金型のリップ先端温度と、押出機から吐出された樹脂温度との差が１５℃未満であると、表面層の気泡径が大きくなって、スチレン系樹脂発泡板の厚み方向における気泡の数が少なくなり気泡壁による熱の遮断回数が減少してスチレン系樹脂発泡板の断熱性が低下したり、或いは、突沸が発生して良好なスチレン系樹脂発泡板を得ることができないからである。
【００４２】
ここで、本発明のスチレン系樹脂発泡板の製造方法では、合成雲母及び水を所定割合でスチレン系樹脂に供給すると共に、金型のリップ部分によって所定温度に冷却することによって、難燃剤であるヘキサブロモシクロドデカンの存在にもかかわらず、表面層及び中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径を上述のように制御してなるスチレン系樹脂発泡板を得ることができる。
【００４３】
この理由は明確に解明されていないが、合成雲母は層状に形成され、押出機内における剪断応力によって各層が互いに剥離して微細な形状となった上で溶融状態のスチレン系樹脂中に均一に分散すると共に、合成雲母はその表面に水を吸着すればする程、核剤効果を発揮して気泡をより多く発生させる。
【００４４】
しかも、本発明のスチレン系樹脂発泡板の製造方法では、スチレン系樹脂との相溶性が低い水をスチレン系樹脂１００重量部に対して０．７〜１．５重量部と若干、過剰に添加していることから、水は、金型内部の樹脂流路を流通する間に外側（金型壁面側、表面側）に移行し、発泡適性温度に冷却された溶融状態のスチレン系樹脂の表面近傍部における水の濃度が残余のスチレン系樹脂部分よりも高くなっている。
【００４５】
その結果、スチレン系樹脂の表面近傍部に分散した合成雲母は、スチレン系樹脂の内面側（中心部）に分散した合成雲母に比して、水を充分に吸着した状態となっており、この合成雲母の作用によって溶融状態のスチレン系樹脂の表面近傍部に、残余のスチレン系部分に比して、より多くの微細な気泡が発生する。
【００４６】
その上、スチレン系樹脂を金型から押出発泡する際、金型のリップ先端温度を押出機から吐出されたスチレン系樹脂の温度から所定温度だけ低い温度範囲に調整していることも相まって、得られるスチレン系樹脂発泡板は、その表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が小さく形成されている一方、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径よりも所定倍だけ大きく形成されており、その結果、ＪＩＳ Ａ９５１１で規定されたＢ類３種を満たす優れた断熱性を有すると共に、押出発泡時におけるスウェル減少の抑制によって厚みの厚いものとすることができる。
【００４７】
そして、上記の如くして得られたスチレン系樹脂発泡板の密度は、低いと、断熱性が低下することがあり、又、高いと、厚みの厚いスチレン系樹脂発泡板とすることが困難となることがあるので、３０〜４５ｋｇ／ｍ3 が好ましい。なお、スチレン系樹脂発泡板の密度は、ＪＩＳ Ｋ７２２２に準拠して測定されたものをいう。
【００４８】
更に、スチレン系樹脂発泡板の熱伝導率は、０．０２８０Ｗ／ｍＫ以下が好ましい。なお、スチレン系樹脂発泡板の熱伝導率は以下の要領で測定されたものをいう。
【００４９】
即ち、押出発泡後３０日が経過したスチレン系樹脂発泡板から、押出方向（ＭＤ方向）に２００ｍｍ、押出方向に直交し且つスチレン系樹脂発泡板の表面に沿った方向（ＴＤ方向）に１５０ｍｍ、厚み方向（ＶＤ方向）に２５ｍｍの寸法でもって試験片を切り出す。なお、試験片の一面全面がスチレン系樹脂発泡板の表面層となるようにする。
【００５０】
しかる後、上記試験片の熱伝導率を、ＪＩＳ Ａ１４１２：１９９４の「熱絶縁材の熱伝導率及び熱抵抗の測定方法」にて規定された平板熱流計法に基づいて測定する。
【００５１】
又、押出発泡後３０日経過したスチレン系樹脂発泡板に含まれるブタン量は、少ないと、スチレン系樹脂発泡板の断熱性が低下する一方、多いと、スチレン系樹脂発泡板の難燃性が低下するので、１．５重量％以上で且つ３．０重量％未満が好ましく、２重量％以上で且つ２．５重量％未満がより好ましい。
【００５２】
なお、押出発泡後３０日経過したスチレン系樹脂発泡板に含まれるブタン量は、下記の要領で測定されたものをいう。即ち、押出発泡後３０日経過したスチレン系樹脂発泡板から、該スチレン系樹脂発泡板の両面と、この両面のそれぞれから厚み方向に内側に４ｍｍだけ入った部分との間にある表層部分を除外し、この表層部分が除外されたスチレン系樹脂発泡板から、押出方向（ＭＤ方向）に３５ｍｍ、スチレン系樹脂発泡板の表面に沿い且つ押出方向に直交する方向（ＴＤ方向）に５ｍｍ、厚み方向（ＶＤ方向）に５ｍｍの大きさを有する直方体形状の試験片を切り出し、この試験片の重量を測定する。
【００５３】
そして、上記試験片を１５０℃の熱分解炉に供給してガスクロマトグラフィーからチャートを得、予め測定しておいたブタンの検量線に基づいて上記チャートから試験片中のブタン量を算出し、以下の式に基づいて求める。
【００５４】
（押出発泡後３０日経過したスチレン系樹脂発泡板に含まれるブタン量）
＝１００×試験片中のブタン量／試験片の重量
【００５５】
更に、上記では、発泡剤として、有機系発泡剤及び水をスチレン系樹脂中に圧入しているが、得られるスチレン系樹脂発泡板の物性を損なわない範囲内において、有機系発泡剤及び水以外の発泡剤を添加してもよいが、ハロゲン原子を含む発泡剤は用いないのが好ましい。
【００５６】
このような発泡剤としては、例えば、窒素、塩化メチル、１，１−ジフルオロエタン、１，１，１−トリフルオロエタン、１，１，１，２−テトラフルオロエタン、１，１，１，２，２−ペンタフルオロエタン、二酸化炭素等が挙げられる。
【００５７】
【実施例】
（実施例１〜２、比較例１〜４）
押出機として、第一押出機の先端部に第二押出機を連結させてなるタンデム型押出機を用い、この第一押出機に、表１に示した所定量のポリスチレン（東洋スチレン社製 商品名「ＨＲＭ−１８」）、ヘキサブロモシクロドデカン（ＨＢＣＤ）、合成雲母（コープケミカル社製 商品名「ＭＥ１００」、平均粒径：３μｍ）及びタルクを供給して溶融、混練した。
【００５８】
そして、上記第一押出機の先端部分に一体的に設けた一の注入口から、表１に示した所定量のジメチルエーテル及びブタン（イソブタン：６０重量％、ノルマルブタン：４０重量％）からなる有機系発泡剤を溶融状態のポリスチレンに圧入した後、第一押出機の他の注入口から表１に示した所定量の水を溶融状態のポリスチレンに圧入して、ポリスチレンと、有機系発泡剤及び水とを混合した。
【００５９】
しかる後、溶融状態のポリスチレンを第一押出機から第二押出機に連続的に供給して、第二押出機にてポリスチレンを発泡に適した樹脂温度に冷却した上で、第二押出機の先端に取り付けた金型から押出発泡した。なお、押出機からのポリスチレンの吐出量を３５ｋｇ／時間とした。
【００６０】
続いて、第二押出機の金型から押出発泡された直後の溶融状態の押出発泡板を、第二押出機の先端部に取り付けられた金型に密接させて配設された、上下方向に３０ｍｍの間隔を存して平行に配設され且つ約３０℃に維持された上下一対の板状体（サイジングプレート）の対向面間に連続的に供給して押出発泡板の両面を冷却してスチレン系樹脂発泡板を得た。なお、金型のリップ先端温度及び押出機から吐出された樹脂温度は表１の通りであった。
【００６１】
なお、比較例３については、押出発泡板の表面に突沸が発生して良好なスチレン系樹脂発泡板を得ることができず、又、比較例４については、全体的に気泡径が小さくなりすぎてスチレン系樹脂発泡板を得ることができなかった。
【００６２】
以上の如くして得られたスチレン系樹脂発泡板の表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径（表面層気泡径）、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径（中心層気泡径）、密度、熱伝導率、押出発泡後３０日経過したスチレン系樹脂発泡板に含まれるブタン量（残ブタン量）、難燃性について測定し、その結果を表２に示した。
【００６３】
（難燃性）
ＪＩＳ Ａ９５１１：１９９５に規定された測定方法Ａの燃焼性試験に基づいて測定した際の消炎時間の平均値を燃焼性とした。なお、押出発泡後１週間経過したスチレン系樹脂発泡板から、該スチレン系樹脂発泡板の両面と、この両面から厚み方向に２ｍｍ以上、内側に入った部分との間にある部分を除去し、このスチレン系樹脂発泡板の残余部分から、押出方向（ＭＤ方向）に２００ｍｍ、押出方向に直交し且つスチレン系樹脂発泡板の表面に沿った方向（ＴＤ方向）に２５ｍｍ、厚み方向（ＶＤ方向）に１０ｍｍの寸法でもって試験片を５個、切り出し、各試験片の消炎時間の平均時間を難燃性とした。
【００６４】
【表１】
【表２】
なお、実施例１で得られたスチレン系樹脂発泡板について、押出方向（ＭＤ方向）に２００ｍｍ、押出方向に直交し且つスチレン系樹脂発泡板の表面に沿った方向（ＴＤ方向）に１５０ｍｍ、厚み方向（ＶＤ方向）に全厚み寸法（２８ｍｍ）でもって試験片を切り出し、この試験片について上述と同様の要領で熱伝導率を測定したところ、０．０２６３Ｗ／ｍＫであった。
【００６７】
【発明の効果】
請求項１に記載のスチレン系樹脂発泡板は、ジメチルエーテル、ブタン及び水からなる発泡剤を用いて押出発泡により製造されたスチレン系樹脂発泡板であって、スチレン系樹脂１００重量部に対してヘキサブロモシクロドデカン２．０〜４．０重量部及び合成雲母０．３〜３．０重量部を含有し、且つ、少なくとも一つの表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が０．０５〜０．２０ｍｍであると共に、中心層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径が、上記表面層の気泡におけるスチレン系樹脂発泡板の厚み方向の平均気泡径の１．４５〜２．５０倍であることを特徴とするので、ノンフロンの発泡剤を用いて製造されたものであるにもかからず優れた断熱性及び難燃性を有し、特に、断熱性は、ＪＩＳ Ａ９５１１で規定されたＢ類３種を満たす優れた断熱性を有している。
【００６８】
しかも、上記スチレン系樹脂発泡板は、その断熱性及び難燃性を損ねることなく、厚みを厚くすることができ、種々の用途、特に、建築用断熱材等の建築用途に好適に用いることができる。
【００６９】
そして、請求項２に記載のスチレン系樹脂発泡板は、請求項１に記載のスチレン系樹脂発泡板において、密度が３０〜４５ｋｇ／ｍ3 であると共に、熱伝導率が０．０２８０Ｗ／ｍＫ以下であることを特徴とするので、軽量性及び断熱性に優れており、建築用断熱材等の建築用途に用いた場合、優れた取り扱い性を発揮する。
【００７０】
請求項３に記載のスチレン系樹脂発泡板は、請求項１又は請求項２に記載のスチレン系樹脂発泡板において、押出発泡後３０日経過したスチレン系樹脂発泡板に含まれるブタン量が１．５重量％以上で且つ３．０重量％未満であることを特徴とするので、断熱性及び難燃性を両立させつつ両性能を効果的に発揮させることができる。
【００７１】
請求項４に記載のスチレン系樹脂発泡板の製造方法は、スチレン系樹脂１００重量部、ヘキサブロモシクロドデカン２．０〜４．０重量部及び合成雲母０．３〜３．０重量部を押出機に供給して溶融、混練し、この溶融状態のスチレン系樹脂中にジメチルエーテル６０〜８０重量％及びブタン２０〜４０重量％からなる有機系発泡剤３〜１５重量部及び水０．７〜１．５重量部を圧入した後、押出機に取り付けた金型のリップ先端温度を上述した関係を満たす温度に保持しつつ、上記金型から押出発泡することを特徴とするので、地球環境に与える影響を極めて小さくしつつ、断熱性、特に、ＪＩＳ Ａ９５１１に規定されたＢ類３種を満たす断熱性と、難燃性とに優れていると共に厚みの厚いスチレン系樹脂発泡板を円滑に且つ確実に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a styrene-based resin foam plate excellent in heat insulation and flame retardancy and a method for producing the same.
[0002]
[Prior art]
Conventionally, a styrene resin foam board has been widely used as a heat insulating material for buildings. After this styrene resin foam board is supplied to an extruder and melted and kneaded, the styrene resin foam board is converted into this molten styrene resin. It is manufactured by extruding and foaming from an extruder after press-fitting a foaming agent.
[0003]
And as said foaming agent, although chlorine atom containing halogenated hydrocarbons (CFC), such as dichlorodifluoromethane (Freon-12), were used, from the environmental problem of destroying an ozone layer. An attempt has been made to improve a hydrogen atom-containing halogenated hydrocarbon (HCFC) in which a chlorine atom is partially hydrogenated, such as 1-monochloro-1,1-difluoroethane (CFC-142b). , 1,2-tetrafluoroethane (Freon-134a) and other fluorinated hydrocarbons (HFC) are being converted.
[0004]
In addition, in order to make the blowing agent non-fluorocarbon, a blowing agent that combines halogenated hydrocarbons such as methyl chloride and ethyl chloride with hydrocarbons such as butane and propane is also used. Since ethyl chloride and the like contain chlorine atoms, it is considered preferable to be replaced if possible in the environment.
[0005]
Therefore, Patent Document 1 discloses a styrene-based resin foam having a cell structure in which large and small bubbles coexist, which is produced using a foaming agent composed of ethers such as dimethyl ether and hydrocarbons such as butane and propane, and water. Proposed.
[0006]
However, the styrenic resin foam has only about two kinds of B heat insulation as defined in JIS A9511 and is inferior in heat insulation, and is a heat insulation manufactured using a non-fluorocarbon foaming agent. A styrene resin foam board excellent in the above has been desired.
[0007]
[Patent Document 1]
WO99 / 54390 (Claims)
[0008]
[Problems to be solved by the invention]
The present invention is excellent in heat insulation and flame retardancy, and in particular, in heat insulation, it has excellent heat insulation satisfying Class B Class 3 defined in JIS A9511, and is suitable for heat insulating materials for buildings, etc. A styrenic resin foam plate that can be used and a method for producing the same are provided.
[0009]
[Means for Solving the Problems]
The styrene resin foam board of the present invention is a styrene resin foam board produced by extrusion foaming using a foaming agent comprising dimethyl ether, butane and water, Containing 2.0 to 4.0 parts by weight of hexabromocyclododecane and 0.3 to 3.0 parts by weight of synthetic mica with respect to 100 parts by weight of styrenic resin, and The average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in at least one surface layer is 0.05 to 0.20 mm, and the average cell diameter in the thickness direction of the styrene resin foam plate in the cells in the center layer is The average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer is 1.45 to 2.50 times.
[0010]
If the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in at least one surface layer of the styrene resin foam plate is small, the average cell diameter in the thickness direction in the cells in the center layer is small and thick. If it is not possible to make a styrene resin foam plate, and if it is large, the number of times of heat blocking by the cell walls will decrease, and the heat insulation of the styrene resin foam plate will decrease, so 0.05 to 0.20 mm It is limited to 0.08 to 0.15 m. Note that the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles on the two surfaces of the styrene resin foam plate is limited to 0.05 to 0.20 mm, and is 0.08 to 0.15 m. Is preferred.
[0011]
The average cell diameter in the thickness direction of the styrene resin foam plate in the cells in the center layer of the styrene resin foam plate is 1.45 of the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer. It is limited to ˜2.50 times, preferably 1.50 to 2.30 times, and more preferably 1.50 to 2.00 times.
[0012]
This is because the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the center layer of the styrene resin foam plate is 1.45 of the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer. If the ratio is less than twice, the difference between the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the center layer and the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer becomes small, and styrene When the bubble diameter of the styrene resin foam plate is reduced overall, and a thick styrene resin foam plate is obtained, the bubbles form a spindle shape that is long in the thickness direction of the styrene resin foam plate, and the heat is blocked by the bubble walls. This is because the number of times decreases and the heat insulation property of the styrene resin foam plate decreases, or the styrene resin foam plate contracts in the extrusion direction.
[0013]
On the other hand, the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the center layer of the styrene resin foam plate is 2.50 times the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer. This is because the bubble diameter of the center layer increases, the number of times of heat blocking by the bubble walls decreases, and the heat insulating property of the styrene resin foam plate decreases.
[0014]
In addition, the thickness direction of a styrene resin foam board is a thin direction of a styrene resin foam board, Comprising: The normal line direction with respect to the surface of a styrene resin foam board is said. The surface layer of the styrene resin foam plate refers to a portion between the surface of the styrene resin foam plate and a portion which is 4 mm inward from the surface in the thickness direction. The central layer of the plate refers to the remaining portion of the styrene resin foam plate excluding the portion between the surface of the styrene resin foam plate and the portion that is 10 mm inside from the surface in the thickness direction.
[0015]
Here, the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles of the surface layer or the center layer of the styrene resin foam plate is measured in the following manner. That is, the styrenic resin foam plate is cut at an arbitrary position on a plane orthogonal to the extrusion direction. Then, three points are arbitrarily selected from the target layer on the cut surface of the styrene-based resin foam plate, that is, the surface layer or the center layer, and each of the selected three points is 20 times larger using an electron microscope. Take a magnified picture.
[0016]
Three straight lines with a length of 80 mm on the obtained enlarged photograph, arbitrarily drawn in the thickness direction of the styrene-based resin foam plate, counting the number of bubbles on each straight line, based on the following formula for each straight line, The bubble diameter in the thickness direction of the styrene resin foam plate is calculated.
[0017]
Then, the average cell diameter in the thickness direction of the styrene resin foam plate calculated from each of the nine straight lines is defined as the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles of the surface layer or the center layer. . When counting the number of bubbles on a straight line, if a part of the bubbles was on a straight line, it was counted as one.
[0018]
Bubble diameter (mm) in the thickness direction of styrene resin foam board
= 80/20 × n (n: number of bubbles on a straight line)
[0019]
As the cell structure in the surface layer and the center layer of the styrene resin foam plate, even if the cell structure has a uniform cell diameter in each layer, a large cell size bubble (large cell) and a small cell size bubble (Small bubbles) may exist in the same layer, and large bubble may be irregularly present in the small bubbles, but the styrene obtained has a high heat blocking effect by the bubble wall Since the heat insulation of the resin-based resin foam plate is high, a bubble structure in which large and small diameter bubbles are present in the same layer and the large diameter bubbles are irregularly present in the small diameter bubbles is preferable.
[0020]
The styrene resin constituting the styrene resin foam plate is not particularly limited, and for example, a styrene monomer such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, chlorostyrene, bromo styrene, or the like. A polymer or a copolymer obtained by combining two or more of these styrenic monomers; monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, butadiene, and the styrenic monomer And a copolymer with a monomer. The copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. Further, if the styrene resin is contained in an amount of 50% by weight or more, a thermoplastic resin other than the styrene resin may be added.
[0021]
The above-mentioned styrene resin foamed plate has an air conditioner such as talc, calcium carbonate, calcium silicate, titanium oxide, graphite, bentonite, phenolic antioxidant, and light-resistant stabilizer, as long as the physical properties are not impaired. Contains flame retardants such as hexabromocyclododecane, flame retardants such as phosphorus flame retardants, antistatic agents such as stearic acid monoglyceride, colorants such as pigments, additives such as higher fatty acid metal salts such as magnesium stearate May be. In addition, when adding hexabromocyclododecane as a flame retardant, 2.0-4.0 weight part is preferable with respect to 100 weight part of styrene resin.
[0022]
Next, the manufacturing method of a styrene resin foam board is demonstrated. This styrene resin foamed plate is melted and kneaded by supplying 100 parts by weight of styrene resin, 2.0 to 4.0 parts by weight of hexabromocyclododecane and 0.3 to 3.0 parts by weight of synthetic mica to an extruder. Then, 3-15 parts by weight of an organic foaming agent composed of 60 to 80% by weight of dimethyl ether and 20 to 40% by weight of butane and 0.7 to 1.5 parts by weight of water are pressed into the molten styrene-based resin. The mold can be manufactured by extrusion foaming from the mold while maintaining the lip tip temperature of the mold attached to the extruder at a temperature satisfying the following formula.
Resin temperature discharged from the extruder −40 ° C. ≦
Mold lip tip temperature ≤ Resin temperature discharged from extruder-15 ° C
[0023]
If the amount of hexabromocyclododecane added is small, the flame retardancy of the styrene-based resin foam plate is reduced, and if it is large, the bubbles in the surface layer and the center layer can be controlled to a predetermined size. However, since the mechanical strength of the styrene resin foam plate and the foamability of the styrene resin are lowered, 2.0 to 4.0 parts by weight is preferable with respect to 100 parts by weight of the styrene resin, and 2.5 to 3 More preferably, 5 parts by weight.
[0024]
Further, the synthetic mica is an artificially produced mica having a composition in which all —OH groups in the crystal structure of natural mica are substituted with —F groups, unlike natural mica, and KMg Three AlSi Three O Ten F 2 Is an ideal composition.
[0025]
When the average particle size of the synthetic mica is small, the bulk specific gravity is small, and when the synthetic mica is supplied to the extruder, it aggregates and becomes insufficiently dispersed in the resin. Agglomerates may be generated or the open cell ratio may be high, and if it is large, the number of bubbles in the styrene resin foam plate may be reduced and the average cell diameter may be increased. Preferably, 1-20 micrometers is more preferable, and 1-10 micrometers is especially preferable.
[0026]
The average particle size of the synthetic mica is measured by a laser scattering method. Specifically, the product name is “SALD-2100” from Shimadzu Corporation, and the product name is “Microtrack 9320HRA” from Nikkiso. It can be measured by a wet method using a commercially available measuring apparatus.
[0027]
If the amount of synthetic mica added is small, the water injected into the molten styrene resin is not absorbed by the synthetic mica, but separated from the molten styrene resin and adheres to the cylinder inner surface of the extruder. The propulsion force of the extruder with respect to the resin is reduced, the extrusion foaming becomes unstable, and if it is large, the synthetic mica aggregates and it is difficult to form the cell layer and the cell diameter of the center layer with a specific size Since the heat insulation property of the styrene resin foam plate is reduced, 0.3 to 3.0 parts by weight is preferable with respect to 100 parts by weight of the styrene resin, and 0.5 to 2.0 parts by weight is more preferable. 0.8 to 1.5 parts by weight are particularly preferred.
[0028]
Moreover, what consists of dimethyl ether and butane is used as an organic type foaming agent. Examples of the butane include isobutane and normal butane, which may be used alone or in combination.
[0029]
And when isobutane and normal butane are used together as butane, if the content of isobutane in butane is small, the heat insulation property of the styrene-based resin foamed plate may be lowered, so 30% by weight or more is preferable. More preferably, it is more than wt%.
[0030]
In addition, if the content of dimethyl ether in the organic foaming agent is small, the amount of butane is relatively large and the flame retardancy of the styrene resin foamed plate is lowered. Since it decreases and the heat insulation of a styrene resin foam board falls, 60 to 80 weight% is preferable. For the same reason, the content of butane in the organic foaming agent is preferably 20 to 40% by weight.
[0031]
If the amount of the organic foaming agent added is small, the expansion ratio of the styrene resin foam plate is reduced, resulting in a decrease in heat insulation and light weight. 3-15 parts by weight is preferable with respect to 100 parts by weight of the styrenic resin.
[0032]
Furthermore, the water to be pressed into the molten styrene resin is not particularly limited, but it is preferable to use water with few impurities, for example, pure water. The amount of water added is preferably 0.7 to 1.5 parts by weight and more preferably 0.9 to 1.3 parts by weight with respect to 100 parts by weight of the styrene resin.
[0033]
If the amount of water added is less than 0.7 parts by weight with respect to 100 parts by weight of the styrene resin, the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer and the bubbles in the center layer When the difference from the average cell diameter in the thickness direction of the styrene resin foam plate is reduced, the cell diameter of the styrene resin foam plate is reduced overall, and when trying to obtain a thick styrene resin foam plate, Becomes a spindle shape that is long in the thickness direction of the styrene resin foam plate, the number of bubbles in the thickness direction decreases, the number of times of heat blocking by the cell walls decreases, and the heat insulation of the styrene resin foam plate decreases, or styrene On the other hand, when the amount of water added exceeds 1.5 parts by weight with respect to 100 parts by weight of the styrene resin, extrusion fluctuation occurs during extrusion foaming. It is not possible to obtain a good styrene resin foam plate.
[0034]
Moreover, as the timing of press-fitting the organic foaming agent and water into the molten styrene resin, the organic foaming agent and water may be pressed into the styrene resin simultaneously or separately. It is preferable that the organic foaming agent is first press-fitted into the styrene resin and then water is press-fitted into the styrene resin.
[0035]
This is because water has the effect of decomposing hexabromocyclododecane and impairing the effect of the flame retardant. Therefore, the contact time between water and hexabromocyclododecane in the extruder is made as short as possible so This is to minimize the decomposition of cyclododecane and improve the flame retardancy of the styrene resin foam plate.
[0036]
Then, extrusion foaming is performed from the mold while maintaining the lip tip temperature of the mold attached to the extruder so as to satisfy the following formula.
Resin temperature discharged from the extruder −40 ° C. ≦
Mold lip tip temperature ≤ Resin temperature discharged from extruder-15 ° C
[0037]
Furthermore, it is preferable to perform extrusion foaming from the mold while maintaining the lip tip temperature of the mold attached to the extruder so as to satisfy the following formula.
Resin temperature discharged from the extruder −35 ° C. ≦
Die lip tip temperature ≦ Resin temperature discharged from the extruder−20 ° C.
[0038]
In order to cool the lip, a cooling medium such as water or oil is continuously circulated in the cooling medium flow path formed in the lip of the mold, and this cooling medium is used as the cooling medium for the lip. The temperature at the time of supplying into the flow path is the die lip tip temperature.
[0039]
The flow rate at which the cooling medium flows through the cooling medium flow path of the lip of the mold depends on the temperature of the cooling medium when flowing into the cooling medium flow path and the cooling medium when flowing out of the cooling medium flow path. The difference from the temperature is preferably adjusted to be less than 5 ° C, more preferably less than 3 ° C.
[0040]
Further, the temperature at the center of the breaker plate disposed at the resin outlet of the extruder is measured using a thermocouple, and this measured temperature is taken as the resin temperature discharged from the extruder.
[0041]
This is because when the lip tip temperature of the mold is lower than the resin temperature discharged from the extruder by more than 40 ° C., the styrenic resin cannot be solidified by the lip of the mold and cannot be extruded and foamed. When the difference between the lip tip temperature of the mold and the resin temperature discharged from the extruder is less than 15 ° C., the bubble diameter of the surface layer becomes large and the number of bubbles in the thickness direction of the styrene resin foam plate is small. This is because the heat insulation property of the styrene resin foam plate is reduced due to a decrease in the number of times the heat is blocked by the bubble wall, or bumping occurs and a good styrene resin foam plate cannot be obtained.
[0042]
Here, in the method for producing a styrene resin foam plate of the present invention, the synthetic mica and water are supplied to the styrene resin at a predetermined ratio and cooled to a predetermined temperature by the lip portion of the mold, thereby being a flame retardant. Despite the presence of hexabromocyclododecane, it is possible to obtain a styrene resin foam plate in which the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer and the central layer is controlled as described above. .
[0043]
The reason for this is not clearly understood, but synthetic mica is formed in layers, and the layers are separated from each other by shear stress in the extruder to form a fine shape, and then uniformly dispersed in the molten styrene resin. At the same time, the more adsorbed water on the surface of the synthetic mica, the more effective the nucleating agent effect and the more bubbles are generated.
[0044]
Moreover, in the method for producing a styrene resin foamed plate of the present invention, water having a low compatibility with the styrene resin is added in an excessive amount of 0.7 to 1.5 parts by weight with respect to 100 parts by weight of the styrene resin. Therefore, water moves to the outside (mold wall surface side, surface side) while flowing through the resin flow path inside the mold, and the surface of the molten styrene resin cooled to the foaming suitable temperature The concentration of water in the vicinity is higher than that of the remaining styrene resin.
[0045]
As a result, the synthetic mica dispersed in the vicinity of the surface of the styrene resin is in a state of sufficiently adsorbing water compared to the synthetic mica dispersed on the inner surface side (center portion) of the styrene resin. As a result of the action of the synthetic mica, more fine bubbles are generated in the vicinity of the surface of the molten styrene resin as compared with the remaining styrene resin.
[0046]
In addition, when extruding and foaming styrene resin from the mold, the lip tip temperature of the mold is adjusted to a temperature range lower than the temperature of the styrene resin discharged from the extruder by a predetermined temperature. The styrene resin foam plate is formed with a small average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in the surface layer, while the average cell in the thickness direction of the styrene resin foam plate in the bubbles in the center layer. The diameter is larger than the average cell diameter in the thickness direction of the styrene-based resin foam plate in the air bubbles in the surface layer, and as a result, excellent heat insulating properties satisfying the B class 3 specified in JIS A9511 In addition, the thickness can be increased by suppressing swell reduction during extrusion foaming.
[0047]
And if the density of the styrene resin foam plate obtained as described above is low, the heat insulating property may be lowered, and if it is high, it is difficult to obtain a thick styrene resin foam plate. 30-45kg / m Three Is preferred. In addition, the density of a styrene-type resin foam board says what was measured based on JISK7222.
[0048]
Furthermore, the thermal conductivity of the styrene resin foam plate is preferably 0.0280 W / mK or less. In addition, the thermal conductivity of a styrene resin foam board means what was measured in the following ways.
[0049]
That is, from the styrene resin foam plate 30 days after extrusion foaming, 200 mm in the extrusion direction (MD direction), 150 mm in the direction (TD direction) perpendicular to the extrusion direction and along the surface of the styrene resin foam plate, A test piece is cut out with a dimension of 25 mm in the thickness direction (VD direction). Note that the entire surface of the test piece is the surface layer of the styrene resin foam plate.
[0050]
Thereafter, the thermal conductivity of the test piece is measured based on a plate heat flow meter method defined in “Method for measuring thermal conductivity and thermal resistance of thermal insulation material” in JIS A1412: 1994.
[0051]
Also, if the amount of butane contained in the styrene resin foam plate that has passed 30 days after extrusion foaming is small, the heat insulation property of the styrene resin foam plate is reduced, whereas if it is large, the flame retardancy of the styrene resin foam plate is low. Therefore, it is preferably 1.5% by weight or more and less than 3.0% by weight, more preferably 2% by weight or more and less than 2.5% by weight.
[0052]
In addition, the amount of butane contained in the styrene resin foam board which passed 30 days after extrusion foaming means what was measured in the following way. That is, from the styrene resin foam plate that has passed 30 days after extrusion foaming, the surface layer portion between the both sides of the styrene resin foam plate and the portion that is 4 mm inward in the thickness direction from each of the both surfaces is excluded. From the styrene resin foam plate from which the surface layer portion is excluded, 35 mm in the extrusion direction (MD direction), 5 mm in the direction along the surface of the styrene resin foam plate and orthogonal to the extrusion direction (TD direction), the thickness direction A rectangular parallelepiped test piece having a size of 5 mm in the (VD direction) is cut out, and the weight of the test piece is measured.
[0053]
Then, the chart is supplied to a pyrolysis furnace at 150 ° C. to obtain a chart from gas chromatography, the amount of butane in the specimen is calculated from the chart based on a calibration curve of butane measured in advance, It calculates | requires based on the following formula | equation.
[0054]
(Amount of butane contained in styrene-based resin foam plate 30 days after extrusion foaming)
= 100 × butane amount in test piece / weight of test piece
[0055]
Furthermore, in the above, as the foaming agent, an organic foaming agent and water are press-fitted into the styrene resin, but within the range not impairing the physical properties of the resulting styrene resin foamed plate, other than the organic foaming agent and water However, it is preferable not to use a blowing agent containing a halogen atom.
[0056]
Examples of such foaming agents include nitrogen, methyl chloride, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2 , 2-pentafluoroethane, carbon dioxide and the like.
[0057]
【Example】
(Examples 1-2, Comparative Examples 1-4)
As the extruder, a tandem type extruder in which a second extruder is connected to the tip of the first extruder is used, and a predetermined amount of polystyrene shown in Table 1 (product made by Toyo Styrene Co., Ltd.) is used for the first extruder. Name “HRM-18”), hexabromocyclododecane (HBCD), synthetic mica (trade name “ME100” manufactured by Co-op Chemical Co., Ltd., average particle size: 3 μm) and talc were supplied and melted and kneaded.
[0058]
An organic material comprising a predetermined amount of dimethyl ether and butane (isobutane: 60% by weight, normal butane: 40% by weight) shown in Table 1 from one injection port provided integrally at the tip of the first extruder. After press-fitting the system foaming agent into the molten polystyrene, a predetermined amount of water shown in Table 1 is injected into the melted polystyrene from the other inlet of the first extruder, and polystyrene, an organic foaming agent, and Mixed with water.
[0059]
Thereafter, the molten polystyrene is continuously supplied from the first extruder to the second extruder, and after the polystyrene is cooled to a resin temperature suitable for foaming by the second extruder, Extrusion foaming was performed from a die attached to the tip. The amount of polystyrene discharged from the extruder was 35 kg / hour.
[0060]
Subsequently, the extruded foamed plate immediately after being extruded and foamed from the mold of the second extruder is disposed in close contact with the mold attached to the tip of the second extruder, in the vertical direction. Supply continuously between the opposed surfaces of a pair of upper and lower plate-like bodies (sizing plates) that are arranged in parallel with an interval of 30 mm and maintained at about 30 ° C. to cool both sides of the extruded foam plate A styrene resin foamed plate was obtained. The lip tip temperature of the mold and the resin temperature discharged from the extruder were as shown in Table 1.
[0061]
In Comparative Example 3, bumping occurs on the surface of the extruded foam plate, and a good styrene resin foam plate cannot be obtained. In Comparative Example 4, the cell diameter is too small as a whole. Thus, a styrene resin foam board could not be obtained.
[0062]
The average cell diameter (surface layer cell diameter) in the thickness direction of the styrene resin foam plate in the bubbles of the surface layer of the styrene resin foam plate obtained as described above, the thickness of the styrene resin foam plate in the bubbles of the center layer The average cell diameter in the direction (center layer cell diameter), density, thermal conductivity, butane amount (residual butane amount) contained in the styrene resin foam plate after 30 days from extrusion foaming, and flame retardancy were measured. Are shown in Table 2.
[0063]
(Flame retardance)
The average value of the extinguishing time when measured based on the flammability test of Measurement Method A defined in JIS A9511: 1995 was defined as flammability. In addition, from the styrenic resin foam plate that has passed one week after extrusion foaming, the part between the both sides of the styrenic resin foam plate and the part that enters the thickness direction 2 mm or more from the both sides is removed, From the remaining portion of the styrene resin foam plate, 200 mm in the extrusion direction (MD direction), 25 mm in the direction orthogonal to the extrusion direction and along the surface of the styrene resin foam plate (TD direction), the thickness direction (VD direction) Five test pieces having a size of 10 mm were cut out, and the average time of the flame extinguishing time of each test piece was regarded as flame retardant.
[0064]
[Table 1]
[Table 2]
In addition, about the styrene resin foam plate obtained in Example 1, 200 mm in the extrusion direction (MD direction), 150 mm in the direction (TD direction) orthogonal to the extrusion direction and along the surface of the styrene resin foam plate (TD direction), thickness When a test piece was cut out in the direction (VD direction) with the entire thickness dimension (28 mm), and the thermal conductivity of this test piece was measured in the same manner as described above, it was 0.0263 W / mK.
[0067]
【The invention's effect】
The styrene resin foam board according to claim 1 is a styrene resin foam board produced by extrusion foaming using a foaming agent comprising dimethyl ether, butane and water, Containing 2.0 to 4.0 parts by weight of hexabromocyclododecane and 0.3 to 3.0 parts by weight of synthetic mica with respect to 100 parts by weight of styrenic resin, and The average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles in at least one surface layer is 0.05 to 0.20 mm, and the average cell diameter in the thickness direction of the styrene resin foam plate in the cells in the center layer is Since it is 1.45 to 2.50 times the average cell diameter in the thickness direction of the styrene resin foam plate in the bubbles of the surface layer, it is manufactured using a non-fluorocarbon foaming agent. Nevertheless, it has excellent heat insulating properties and flame retardancy, and in particular, the heat insulating properties have excellent heat insulating properties that satisfy the three types of Class B defined in JIS A9511.
[0068]
Moreover, the styrene-based resin foam plate can be thickened without impairing its heat insulation and flame retardancy, and can be suitably used for various applications, particularly for architectural applications such as architectural heat insulating materials. it can.
[0069]
And the styrene resin foam board of Claim 2 is a styrene resin foam board of Claim 1, A density is 30-45 kg / m. Three In addition, since it has a thermal conductivity of 0.0280 W / mK or less, it is excellent in lightness and heat insulation, and is excellent in handling properties when used for building applications such as heat insulating materials for buildings. Demonstrate.
[0070]
The styrene resin foam plate according to claim 3 is the styrene resin foam plate according to claim 1 or 2, wherein the amount of butane contained in the styrene resin foam plate after 30 days from extrusion foaming is 1. Since it is 5 weight% or more and less than 3.0 weight%, both performance can be exhibited effectively, making heat insulation and flame retardance compatible.
[0071]
The method for producing a styrene resin foamed plate according to claim 4 comprises extruding 100 parts by weight of a styrene resin, 2.0 to 4.0 parts by weight of hexabromocyclododecane and 0.3 to 3.0 parts by weight of synthetic mica. It is supplied to a machine and melted and kneaded. In this molten styrene resin, 3 to 15 parts by weight of an organic foaming agent composed of 60 to 80% by weight of dimethyl ether and 20 to 40% by weight of butane and 0.7 to 1 of water After press-fitting 5 parts by weight, it is characterized by extrusion foaming from the mold while maintaining the lip tip temperature of the mold attached to the extruder at a temperature satisfying the above-mentioned relationship, so that it is given to the global environment Smooth and reliable styrene-based resin foam plate with excellent heat insulation, especially heat insulation that satisfies the three types of B specified in JIS A9511, and flame retardancy, while minimizing the impact To manufacture Can.
Claims (4)
押出機から吐出された樹脂温度−４０℃≦
金型のリップ先端温度≦押出機から吐出された樹脂温度−１５℃100 parts by weight of styrene resin, 2.0 to 4.0 parts by weight of hexabromocyclododecane and 0.3 to 3.0 parts by weight of synthetic mica are supplied to an extruder and melted and kneaded. A mold attached to an extruder after press-fitting 3 to 15 parts by weight of an organic foaming agent comprising 60 to 80% by weight of dimethyl ether and 20 to 40% by weight of butane in the resin and 0.7 to 1.5 parts by weight of water A method for producing a styrene-based resin foam board, wherein extrusion foaming is performed from the mold while maintaining the lip tip temperature at a temperature satisfying the following formula.
Resin temperature discharged from the extruder −40 ° C. ≦
Mold lip tip temperature ≤ Resin temperature discharged from extruder-15 ° C
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