JP2004175862A - Styrenic resin foamed board and its manufacturing method - Google Patents
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Abstract
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塩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、発泡剤として、ジメチルエーテル等のエーテル類と、ブタンやプロパン等の炭化水素とを併用して製造された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、その気泡が比較的大径なものであることから断熱性に劣り、ＪＩＳ Ａ９５１１で規定されたＢ類２種程度の断熱性しか有しないと共に、可燃性を有する炭化水素を用いていることから難燃性にも劣るものであった。
【０００７】
【特許文献１】
ＷＯ９９／５４３９０（特許請求の範囲、第１５頁第１５〜１７頁）
【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を提供する。
【０００９】
【課題を解決する手段】
本発明のスチレン系樹脂発泡板は、押出機から押出発泡させてなるスチレン系樹脂発泡板であって、気泡が、主として厚み方向の気泡径が０．１０ｍｍ以下の小径気泡と、厚み方向の気泡径が０．１５ｍｍ以上で且つ０．３０ｍｍ未満の大径気泡とから構成され、押出方向に垂直な面で切断した切断面において、小径気泡及び大径気泡の占める総面積の比率が８５％以上であり且つ小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率が３０〜８０％であり、更に、押出発泡後３０日経過した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。
【００１０】
上記スチレン系樹脂発泡板は、従来から汎用されている押出発泡方法を用いて製造されたものであり、その気泡は、主として厚み方向の気泡径が０．１０ｍｍ以下の小径気泡と、厚み方向の気泡径が０．１５ｍｍ以上で且つ０．３０ｍｍ未満の大径気泡とから構成されている。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。
【００１１】
このように、スチレン系樹脂発泡板の気泡を小径気泡と大径気泡とから構成しているのは以下の理由による。即ち、厚み方向の気泡径が０．１０ｍｍ以下という微細な小径気泡を存在させることによって、スチレン系樹脂発泡板の厚み方向の気泡壁の数を増やし、気泡壁による熱の遮断回数を増加させることにより断熱性を向上させている。
【００１２】
一方、スチレン系樹脂発泡板の気泡の全てが小径気泡であるとすると、スチレン系樹脂発泡板中における気泡壁の数、即ち、気泡壁の表面積が多くなり過ぎて各気泡壁の厚さが薄くなり、気泡壁の数は多くなって熱の遮断回数は多くなるものの、気泡壁による熱の遮断効果の低下度合いの方が大きくなってしまい、結果として、スチレン系樹脂発泡板の断熱性が低下してしまう。
【００１３】
そこで、本発明のスチレン系樹脂発泡板では、上記小径気泡に加えて、厚み方向の気泡径が０．１５ｍｍ以上で且つ０．３０ｍｍ未満である大径気泡を所定割合で併存させることによって、小径気泡の数、即ち、気泡壁の数を減少させ、小径気泡を形成する気泡壁の厚みを厚くして熱の遮断効果が充分となるように構成している。
【００１４】
即ち、本発明のスチレン系樹脂発泡板は、小径気泡と大径気泡とを所定割合で併存させることによって、小径気泡の気泡壁の厚み及びスチレン系樹脂発泡板の厚み方向における小径気泡の気泡壁の数を調整し、優れた断熱性が発揮されるようにしていると共に、曲げ強さや圧縮強さ等の物理的強度の向上も図っている。
【００１５】
更に、スチレン系樹脂発泡板を詳細に説明する。先ず、スチレン系樹脂発泡板の気泡のうち、厚み方向の気泡径が０．１０ｍｍ以下の小径気泡について着目した理由は、厚み方向の気泡径が０．１０ｍｍを越えた気泡では、その数をたとえ調整したとしても、スチレン系樹脂発泡板の厚み方向における気泡壁による熱の遮断回数が減少してしまい、スチレン系樹脂発泡板の断熱性が低下してしまうためである。
【００１６】
又、スチレン系樹脂発泡板の気泡のうち、厚み方向の気泡径が０．１５ｍｍ以上で且つ０．３０ｍｍ未満の大径気泡について着目した理由は下記の通りである。
【００１７】
つまり、スチレン系樹脂発泡板における厚み方向の気泡径が０．１０ｍｍを越え且つ０．１５ｍｍ未満の気泡では、その径が上記小径気泡に近くなってしまい、このような径を有する気泡をいくら制御したとしても、小径気泡の気泡壁の厚み及び気泡壁の数をスチレン系樹脂発泡板の断熱性が効果的に向上するように調整することができないからである。
【００１８】
そして、スチレン系樹脂発泡板の厚み方向における気泡径が０．３０ｍｍ以上の気泡では、その径が大きくなりすぎてしまって、スチレン系樹脂発泡板の厚み方向における全体の気泡数が減少し、その結果、気泡壁による熱の遮断回数が減少し、スチレン系樹脂発泡板の断熱性が低下してしまうからである。
【００１９】
ここで、上記スチレン系樹脂発泡板の厚み方向における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部分において押出方向に垂直な面で切断する。そして、スチレン系樹脂発泡板の切断面を走査型電子顕微鏡を用いて５０倍にて拡大、撮影し、拡大写真を得、この拡大写真を乾式複写機にてコピーをとる。なお、拡大写真において、スチレン系樹脂発泡板の厚み方向が上下方向となるように撮影する。
【００２０】
次に、コピー上に表れた気泡のうち測定しようとする気泡を特定し、この特定した気泡の気泡壁の上端に接し且つスチレン系樹脂発泡板の厚み方向に直交する上側基準直線を引き、同様に、この特定した気泡の気泡壁の下端に接し且つ厚み方向に直交する下側基準直線を引く。
【００２１】
そして、スチレン系樹脂発泡板の厚み方向における上側基準直線と下側基準直線との間の距離を測定し、この距離を５０で除したものを、スチレン系樹脂発泡板の厚み方向における気泡の径とする。
【００２２】
更に、スチレン系樹脂発泡板を押出方向に垂直な面で切断した際の切断面において、小径気泡及び大径気泡の占める総面積の比率は、小さいと、スチレン系樹脂発泡板の断熱性が低下したり或いは物理的強度が低下したりするので、８５％以上に限定され、９０％以上が好ましく、９３％以上がより好ましい。
【００２３】
又、スチレン系樹脂発泡板を押出方向に垂直な面で切断した際の切断面において、小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率は、小さいと、スチレン系樹脂発泡板の断熱性が低下し、又、大きいと、相対的に大径気泡の数が少なくなって、小径気泡の気泡壁の厚みが薄くなり、スチレン系樹脂発泡板の断熱性が低下するので、３０〜８０％に限定され、４０〜８０％が好ましく、５０〜８０％がより好ましい。
【００２４】
更に、スチレン系樹脂発泡板を押出方向に垂直な面で切断した際の切断面において、スチレン系樹脂発泡板の厚み方向の気泡径が０．３ｍｍ以上である気泡の占める総面積の比率は、大きいと、相対的に小径気泡の数が少なくなって、スチレン系樹脂発泡板の厚み方向の気泡壁の数が少なくなり、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、５％未満が好ましく、３％未満がより好ましく、２％未満が特に好ましい。
【００２５】
ここで、スチレン系樹脂発泡板を押出方向に垂直な面で切断した際の切断面において、測定対象となる気泡の占める総面積は下記の要領で測定されたものをいう。
【００２６】
即ち、スチレン系樹脂発泡板を任意の３箇所において押出方向に垂直な面で切断する。そして、スチレン系樹脂発泡板の各切断面を走査型電子顕微鏡を用いて５０倍にて拡大、撮影し、拡大写真をそれぞれ得、これら拡大写真を乾式複写機にてコピーをとる。なお、拡大写真において、スチレン系樹脂発泡板の厚み方向が上下方向となるように撮影する。但し、スチレン系樹脂発泡板の切断面の撮影対象としては、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２ｍｍだけ入った部分との間にある表層部分を除外した部分とする。これは、表層部分は、成形具との接触や外気による冷却等によって、その他の部分と気泡の状態が異なることが多いためである。
【００２７】
各コピーから縦２．５ｍｍ×横１．７ｍｍの長方形と同一或いはこの長方形よりも大きな大きさを有する長方形状の測定部分を任意に特定し、この測定部分内において、測定対象となる気泡を黒く塗りつぶし、この黒く塗りつぶした面積の総和、即ち、測定対象となる気泡の占める総面積を求め、これら総面積の平均を測定対象となる気泡の占める総面積とする。なお、測定対象となる気泡が、測定部分と測定部分でない部分とを区画する線（区画線）によって分断されている場合には、気泡を分断した区画線が気泡の気泡壁であるとみなして算出された気泡径に基づいて測定対象となる気泡を特定する。ここで、上記黒く塗りつぶした面積の総和は、例えば、タマヤ計測システム社から商品名「ＰＬＡＮＩＸ５０００」にて市販されている測定機器を用いて算出することができる。
【００２８】
そして、小径気泡及び大径気泡の占める総面積の比率は、下記式により算出される。
（小径気泡及び大径気泡の占める総面積の比率〔％〕）
＝１００×（小径気泡の占める総面積＋大径気泡の占める総面積）／測定部分の面積
【００２９】
同様に、小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率は、下記式により算出される。
（小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率〔％〕）
＝１００×小径気泡の占める総面積／（小径気泡の占める総面積＋大径気泡の占める総面積）
【００３０】
更に、スチレン系樹脂発泡板の厚み方向の気泡径が０．３ｍｍ以上である気泡の占める総面積の比率は、下記式により算出される。
（スチレン系樹脂発泡板の厚み方向の気泡径が０．３ｍｍ以上である気泡の占める総面積の比率〔％〕）
＝１００×スチレン系樹脂発泡板の厚み方向の気泡径が０．３ｍｍ以上である気泡の占める総面積／測定部分の面積
【００３１】
又、上記スチレン系樹脂発泡板における押出発泡後３０日経過した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し、又、多いと、スチレン系樹脂発泡板の難燃性が低下したり或いは回収再利用のためリペレット化する際の粉砕工程で発火する危険性が大きくなるので、１．５重量％以上で且つ３．０重量％未満に限定され、１．８重量％以上で且つ２．５重量％未満が好ましい。
【００３２】
なお、上記スチレン系樹脂発泡板における押出後３０日経過した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２ｍｍ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に５ｍｍ、厚み方向に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。
【００３３】
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。
【００３４】
（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
【００３５】
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、酸化チタン等の無機化合物；フェノール系抗酸化剤；耐光性安定剤；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。
【００３６】
そして、上記タルクの添加量は、多いと、スチレン系樹脂発泡板の気泡中における小径気泡の占める割合が低下することがあるので、スチレン系樹脂１００重量部に対して１．５重量部以下が好ましく、１．０重量部以下がより好ましく、０．５重量部以下が特に好ましい。
【００３７】
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、難燃剤と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０．３〜２．０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、水０．５〜１．５重量部及び二酸化炭素０．３〜２．０重量部を圧入した後に押出機から押出発泡させることによって製造することができる。
【００３８】
上記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。
【００３９】
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、小径気泡と大径気泡とを上述のような割合で併存させ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したり或いはスチレン系樹脂発泡板のリサイクル化の際に支障をきたすことがあるので、スチレン系樹脂１００重量部に対して２．０〜４．０重量部に限定され、２．５〜３．５重量部が好ましい。
【００４０】
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。
【００４１】
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に小径気泡ができにくくなることがあり、又、大きいと、気泡核の数が減少して小径気泡ができにく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。
【００４２】
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。
【００４３】
そして、合成雲母の添加量は、少ないと、小径気泡と大径気泡とを上記した特定割合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し、又、多くても、合成雲母同士が凝集し、小径気泡と大径気泡とを上記した特定割合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０．３〜２．０重量部に限定され、０．５〜１．８重量部がより好ましく、０．８〜１．５重量部が特に好ましい。
【００４４】
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。
【００４５】
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。
【００４６】
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％に限定される。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％に限定される。
【００４７】
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重量部に限定される。
【００４８】
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、少ないと、スチレン系樹脂発泡板の小径気泡の割合が少なくなって、スチレン系樹脂発泡板の断熱性が低下し、又、多くても、スチレン系樹脂発泡板の小径気泡の割合が少なくなって、スチレン系樹脂発泡板の断熱性が低下し、或いは、押出機からスチレン系樹脂を押出発泡する際に吐出変動が発生して良好なスチレン系樹脂発泡板が得られないので、スチレン系樹脂１００重量部に対して０．５〜１．５重量部に限定され、０．６〜１．０重量部がより好ましい。
【００４９】
又、二酸化炭素の添加量は、少ないと、スチレン系樹脂発泡板の大小径気泡の占める割合が少なくなったり或いは小径気泡の占める割合が少なくなったりして、スチレン系樹脂発泡板の断熱性が低下し、又、多いと、発泡時に内部発泡や突沸が発生して良好なスチレン系樹脂発泡板が得られないので、スチレン系樹脂１００重量部に対して０．３〜２．０重量部に限定され、０．５〜１．５重量部が好ましい。
【００５０】
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、水及び二酸化炭素を所定割合でスチレン系樹脂に供給することによって、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、主な気泡の径を０．３０ｍｍ未満とすることができると共に、スチレン系樹脂発泡板の厚み方向の気泡径が０．１０ｍｍ以下の気泡も安定的に多数、形成することができ、上述のような、小径気泡と大径気泡とが所定割合で併存する全体的に気泡径の微細なスチレン系樹脂発泡板を得ることができるものである。
【００５１】
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る。その結果、小径気泡を形成させる気泡核になると考えられる合成雲母と水との共存点の数が多くなる。
【００５２】
更に、二酸化炭素は、スチレン系樹脂に溶解すると共に水にも溶解し易い性質を有していると共に、蒸気圧が高いために気泡核からの実際の微小気泡の発生効率を高める作用がある。
【００５３】
以上のような複合作用の結果、小径気泡を発生させる能力の高い合成雲母、水及び二酸化炭素の共存点が多数でき、スチレン系樹脂発泡板の厚み方向の気泡径が０．１ｍｍ以下という小径気泡を多数、安定的に形成することができるものと思われる。
【００５４】
又、大径気泡は、気泡の形成過程において、水の吸着の少ない合成雲母、二酸化炭素単独の気泡核からの成長気泡や、上記小径気泡の気泡壁の一部が破断して隣接する気泡同士が結合することによって形成されるものと思われる。
【００５５】
スチレン系樹脂発泡板の主な気泡をその厚み方向の径が０．３ｍｍ未満のものとするには、二酸化炭素の効果が特に大きく、従来から行われているタルクの増量では０．１ｍｍ以下の小径気泡が消失してしまうといった問題点を生じる。
【００５６】
以上の如く、上記有機系発泡剤の他に、合成雲母、水及び二酸化炭素をスチレン系樹脂に所定割合でもって添加することによって、小径気泡と大径気泡とを所定割合でもって安定的に形成することができる。
【００５７】
なお、有機系発泡剤、水及び二酸化炭素は、溶融状態のスチレン系樹脂中に同時に圧入してもよいが、水は、難燃剤であるヘキサブロモシクロドデカンを分解する作用があるため、有機系発泡剤及び二酸化炭素を溶融状態のスチレン系樹脂中に圧入した後、水を溶融状態のスチレン系樹脂中に圧入することにより、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することが好ましい。
【００５８】
更に、上記では、発泡剤として、有機系発泡剤、水及び二酸化炭素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、水及び二酸化炭素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。
【００５９】
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等が挙げられる。
【００６０】
【実施例】
（実施例１〜４ 比較例１〜６）
押出機として、第一押出機の先端に第二押出機が接続されてなるタンデム型押出機を用い、上記第一押出機に、表１に示した量のポリスチレン（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、合成雲母（コープケミカル社製 商品名「ＭＥ−１００」、平均粒径：３μｍ）及びタルクを供給して２１０℃で溶融、混練した。
【００６１】
更に、表１に示した量のジメチルエーテル及びブタンからなる有機系発泡剤並びに二酸化炭素を第一押出機の先端部分から同時に溶融状態のポリスチレン中に圧入した後、水を第一押出機の先端部分から溶融状態のポリスチレン中に圧入した。
【００６２】
そして、第一押出機内の溶融状態のポリスチレンを第二押出機内に連続的に供給し、第二押出機内においてポリスチレンを発泡に適した温度に冷却した上で、第二押出機の先端に装着したＴ型ダイの口金（リップ幅：７０ｍｍ、リップ厚み：１．２ｍｍ）から１２６℃にて押出発泡し、得られた溶融状態の発泡体を、上下方向に３０ｍｍの間隔を存して互いに平行に配設されてなる一対の板の間に供給して成形し、表２に示した寸法の断面横長長方形状のスチレン系樹脂発泡板を製造した。なお、第二押出機からのポリスチレンの吐出量は、３５ｋｇ／時間とした。
【００６３】
なお、比較例５では、第二押出機で吐出変動が発生して良好なスチレン系樹脂発泡板が得られず、比較例６では、突沸が発生して良好なスチレン系樹脂発泡板が得られなかった。
【００６４】
以上の如くして得られたスチレン系樹脂発泡板において、押出方向に垂直な面で切断した切断面での小径気泡及び大径気泡の占める総面積の比率（大小径気泡占有率）、小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率（小径気泡占有率）、並びに、厚み方向の気泡径が０．３ｍｍ以上である気泡の占める総面積の比率（０．３ｍｍ以上気泡占有率）、押出発泡後３０日経過した発泡板に含まれるブタン量（ブタン残ガス量）、燃焼性、熱伝導率及び密度を下記に示した方法で測定し、その結果を表２に示した。
【００６５】
（ブタン残ガス量）
押出発泡後３０日経過したスチレン系樹脂発泡板の両面から、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２ｍｍ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に５ｍｍ、厚み方向に５ｍｍの大きさを有する直方体形状の試験片を切り出し、その試験片の重量を測定した。
【００６６】
そして、上記試験片を１５０℃の熱分解炉（島津製作所社製 商品名「ＰＹＲ−１Ａ」）に供給してガスクロマトグラフィー（島津製作所社製 商品名「ＧＣ−１４Ｂ」）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た。
（ブタン残ガス量）＝１００×試験片中のブタン量／試験片の重量
【００６７】
（燃焼性）
ＪＩＳ Ａ９５１１−１９９５ に規定された測定方法Ａの燃焼性試験に準拠して測定し、ＪＩＳ Ａ９５１１−１９９５ に規定された難燃性を満足したものを○、満足しなかったものを×とした。
【００６８】
（熱伝導率）
押出発泡後３０日が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２ｍｍ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、押出方向に２００ｍｍ、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に１５ｍｍ、厚み方向に２５ｍｍの大きさを有する試験片を切り出した。
【００６９】
そして、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」において規定された平板熱流計法に準拠して測定した。
【００７０】
（密度）
スチレン系樹脂発泡板の密度をＪＩＳ Ｋ７２２２に準拠して測定した。
【００７１】
【表１】
【表２】
【発明の効果】
請求項１に記載のスチレン系樹脂発泡板は、押出機から押出発泡させてなるスチレン系樹脂発泡板であって、気泡が、主として厚み方向の気泡径が０．１０ｍｍ以下の小径気泡と、厚み方向の気泡径が０．１５ｍｍ以上で且つ０．３０ｍｍ未満の大径気泡とから構成され、押出方向に垂直な面で切断した切断面において、小径気泡及び大径気泡の占める総面積の比率が８５％以上であり且つ小径気泡及び大径気泡の占める総面積に対する小径気泡の占める総面積の比率が３０〜８０％であり、更に、押出発泡後３０日経過した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、断熱性及び難燃性の双方に優れていると共に厚みの厚いものとすることができる。
【００７４】
又、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、押出後３０日経過後の熱伝導率が０．０２８０Ｗ／ｍ・Ｋ以下であることを特徴とするので、断熱性が更に優れたものとなっている。
【００７５】
更に、請求項３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、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０．３〜２．０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、水０．５〜１．５重量部及び二酸化炭素０．３〜２．０重量部を圧入した後に押出機から押出発泡させることを特徴とするので、従来と同様の押出発泡要領でもって、小径気泡と大径気泡とが所定の割合で形成された断熱性に優れた厚さの厚いスチレン系樹脂発泡板を簡単に製造することができる。[0001]
TECHNICAL FIELD 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, styrene resin foam boards have been widely used as heat insulating materials for buildings.The styrene resin foam boards are supplied to an extruder, melted and kneaded, and then mixed with the molten styrene resin. It is manufactured by press-fitting a foaming agent and extruding foam from an extruder.
[0003]
As the foaming agent, a halogen atom-containing halogenated hydrocarbon (CFC) such as dichlorodifluoromethane (CFC-12) has been used. However, there is an environmental problem of destroying the ozone layer. , 1-monochloro-1,1-difluoroethane (Freon-142b) and the like have been improved to halogenated hydrocarbons (HCFC) containing chlorine atoms in which chlorine atoms have been partially hydrogenated. Conversion to fluorinated hydrocarbons (HFCs) such as 1,1,2-tetrafluoroethane (Freon-134a) has been performed.
[0004]
In addition, in order to make the blowing agent non-fluorocarbon, a blowing agent combining a halogenated hydrocarbon such as methyl chloride or ethyl chloride with a hydrocarbon such as butane or propane has been used. Since ethyl chloride and the like contain a chlorine atom, it is said that it is preferable to substitute it if possible in the environment.
[0005]
Therefore, Patent Literature 1 proposes a styrene-based resin foam produced by using an ether such as dimethyl ether and a hydrocarbon such as butane or propane as a foaming agent.
[0006]
However, the styrene-based resin foam is inferior in heat insulation because the cells have a relatively large diameter, and has only about two kinds of heat-insulating properties of Class B specified in JIS A9511, and also has flammability. Because of the use of hydrocarbons, the flame retardancy was poor.
[0007]
[Patent Document 1]
WO99 / 54390 (Claims, page 15, pages 15-17)
[0008]
[Problems to be solved by the invention]
INDUSTRIAL APPLICABILITY The present invention has excellent heat insulating properties and flame retardancy, and particularly, in terms of heat insulating properties, has excellent heat insulating properties satisfying three kinds of Class B specified in JIS A9511, and is suitable for architectural heat insulating materials and the like. Provided is a styrene-based resin foam plate that can be used.
[0009]
[Means to solve the problem]
The styrene-based resin foam plate of the present invention is a styrene-based resin foam plate obtained by extrusion foaming from an extruder, wherein the air bubbles mainly include small-diameter air bubbles having a cell diameter in the thickness direction of 0.10 mm or less, and air bubbles in the thickness direction. The ratio of the total area occupied by the small-diameter bubbles and the large-diameter bubbles is 85% or more in the cut surface which is composed of large-diameter bubbles having a diameter of 0.15 mm or more and less than 0.30 mm, and cut along a plane perpendicular to the extrusion direction. And the ratio of the total area occupied by the small-diameter bubbles to the total area occupied by the small-diameter bubbles and the large-diameter bubbles is 30 to 80%, and the amount of butane contained in the foamed plate 30 days after extrusion foaming is 1.5%. % By weight or more and less than 3.0% by weight.
[0010]
The styrene-based resin foam board is manufactured by using a conventionally used extrusion foaming method, and the bubbles are mainly made of small-diameter bubbles having a thickness of 0.10 mm or less in the thickness direction and small-diameter bubbles in the thickness direction. Large-diameter bubbles having a bubble diameter of 0.15 mm or more and less than 0.30 mm. In addition, the thickness direction of the styrene-based resin foam plate refers to a direction in which the thickness of the styrene-based resin foam plate is thin, and a normal direction to the surface of the styrene-based resin foam plate.
[0011]
The reason why the cells of the styrene-based resin foam plate are composed of small-diameter cells and large-diameter cells is as follows. In other words, the presence of fine small-diameter bubbles having a cell diameter in the thickness direction of 0.10 mm or less increases the number of cell walls in the thickness direction of the styrene-based resin foam plate, thereby increasing the number of times heat is shut off by the cell walls. The heat insulation is improved by this.
[0012]
On the other hand, if all the cells of the styrene-based resin foam plate are small-diameter bubbles, the number of cell walls in the styrene-based resin foam plate, that is, the surface area of the cell wall becomes too large, and the thickness of each cell wall becomes thin. Although the number of cell walls increases and the number of times of heat interruption increases, the degree of decrease in the heat interruption effect by the cell walls increases, and as a result, the heat insulation of the styrene resin foam plate decreases. Resulting in.
[0013]
Therefore, in the styrene-based resin foam plate of the present invention, in addition to the small-diameter bubbles, a large-diameter bubble having a thickness in the thickness direction of 0.15 mm or more and less than 0.30 mm is allowed to coexist at a predetermined ratio. The number of air bubbles, that is, the number of air bubble walls is reduced, and the thickness of the air bubble walls forming small-diameter air bubbles is increased so that the heat shielding effect is sufficient.
[0014]
That is, the styrene-based resin foam plate of the present invention is characterized in that small-diameter air bubbles and large-diameter air bubbles coexist at a predetermined ratio, thereby reducing the thickness of the cell wall of the small-diameter air bubbles and the cell wall of the small-diameter air bubbles in the thickness direction of the styrene-based resin foam plate. Are adjusted so that excellent heat insulating properties are exhibited, and the physical strength such as bending strength and compressive strength is also improved.
[0015]
Further, the styrene resin foam plate will be described in detail. First, among the bubbles in the styrene-based resin foam plate, the reason for focusing on small-diameter bubbles having a bubble diameter in the thickness direction of 0.10 mm or less is as follows. This is because even if it is adjusted, the number of times of heat interruption by the cell walls in the thickness direction of the styrene-based resin foam plate is reduced, and the heat insulation of the styrene-based resin foam plate is reduced.
[0016]
Further, among the bubbles of the styrene-based resin foam plate, the reason why attention was paid to large-diameter bubbles whose bubble diameter in the thickness direction is 0.15 mm or more and less than 0.30 mm is as follows.
[0017]
In other words, in the case where the cell diameter in the thickness direction of the styrene-based resin foam plate exceeds 0.10 mm and is smaller than 0.15 mm, the diameter becomes close to the small-sized cell, and the amount of the cell having such a diameter is controlled. Even if it does, the thickness and the number of cell walls of the small-diameter cells cannot be adjusted so that the heat insulation of the styrene-based resin foam plate is effectively improved.
[0018]
In the case of bubbles having a cell diameter of 0.30 mm or more in the thickness direction of the styrene resin foam board, the diameter becomes too large, and the total number of bubbles in the thickness direction of the styrene resin foam board decreases, As a result, the number of times the heat is cut off by the cell wall is reduced, and the heat insulating property of the styrene-based resin foam plate is reduced.
[0019]
Here, the cell diameter in the thickness direction of the styrene-based resin foam plate refers to a value measured in the following manner. That is, the styrene-based resin foam plate is cut at an arbitrary portion along a plane perpendicular to the extrusion direction. Then, the cut surface of the styrene resin foam plate is magnified and photographed at a magnification of 50 using a scanning electron microscope to obtain an enlarged photograph, and the enlarged photograph is copied by a dry copying machine. In the enlarged photograph, the photograph is taken so that the thickness direction of the styrene-based resin foam plate is the vertical direction.
[0020]
Next, among the bubbles appearing on the copy, the bubble to be measured is specified, and an upper reference straight line that is in contact with the upper end of the bubble wall of the specified bubble and is orthogonal to the thickness direction of the styrene resin foam plate is drawn. Next, a lower reference straight line which is in contact with the lower end of the bubble wall of the specified bubble and is orthogonal to the thickness direction is drawn.
[0021]
Then, the distance between the upper reference straight line and the lower reference straight line in the thickness direction of the styrene-based resin foam board is measured, and this distance divided by 50 is the diameter of the bubbles in the thickness direction of the styrene-based resin foam board. And
[0022]
Furthermore, if the ratio of the total area occupied by the small-diameter bubbles and the large-diameter bubbles in the cut surface when the styrene-based resin foam plate is cut along a plane perpendicular to the extrusion direction is small, the heat insulation of the styrene-based resin foam plate is reduced. Therefore, it is limited to 85% or more, preferably 90% or more, and more preferably 93% or more.
[0023]
Also, when the styrene resin foam plate is cut along a plane perpendicular to the extrusion direction, the ratio of the total area occupied by the small-diameter bubbles to the total area occupied by the small-diameter bubbles and the large-diameter bubbles is small. Since the heat insulation of the foamed board is reduced, and if it is large, the number of large-diameter bubbles is relatively reduced, the thickness of the cell wall of the small-diameter bubbles is reduced, and the heat insulation of the styrene-based resin foamed board is reduced. , 30-80%, preferably 40-80%, more preferably 50-80%.
[0024]
Furthermore, on the cut surface when the styrene-based resin foam plate is cut along a plane perpendicular to the extrusion direction, the ratio of the total area occupied by bubbles having a cell diameter of 0.3 mm or more in the thickness direction of the styrene-based resin foam plate is: If it is large, the number of small-diameter bubbles relatively decreases, the number of cell walls in the thickness direction of the styrene resin foam plate decreases, and the heat insulation of the styrene resin foam plate may decrease. Is preferably less than 3%, more preferably less than 3%.
[0025]
Here, the total area occupied by the air bubbles to be measured on the cut surface when the styrene-based resin foam plate is cut along a plane perpendicular to the extrusion direction is measured in the following manner.
[0026]
That is, the styrene-based resin foam plate is cut at any three points on a plane perpendicular to the extrusion direction. Then, each cut surface of the styrene-based resin foam plate is magnified and photographed at a magnification of 50 using a scanning electron microscope to obtain enlarged photographs, and these enlarged photographs are copied by a dry copying machine. In the enlarged photograph, the photograph is taken so that the thickness direction of the styrene-based resin foam plate is the vertical direction. However, as an object to be photographed of the cut surface of the styrene-based resin foam plate, a surface layer portion between both surfaces of the styrene-based resin foam plate and a portion inwardly inserted by 2 mm in the thickness direction from each of the both surfaces was excluded. Part. This is because the surface layer portion often has a different bubble state from other portions due to contact with the molding tool, cooling by outside air, and the like.
[0027]
From each copy, a rectangular measurement portion having the same size or a size larger than the rectangle of 2.5 mm × 1.7 mm in width or larger than this rectangle is arbitrarily specified, and the bubbles to be measured are blackened in this measurement portion. The sum of the areas painted and blacked out, that is, the total area occupied by the air bubbles to be measured is obtained, and the average of these total areas is defined as the total area occupied by the air bubbles to be measured. When the bubble to be measured is divided by a line (compartment line) that separates the measurement portion from the non-measurement portion, the division line dividing the bubble is regarded as the bubble wall of the bubble. A bubble to be measured is specified based on the calculated bubble diameter. Here, the total sum of the areas painted black can be calculated using, for example, a measuring device marketed by Tamaya Measurement System Co., Ltd. under the trade name “PLANIX5000”.
[0028]
Then, the ratio of the total area occupied by the small-diameter bubbles and the large-diameter bubbles is calculated by the following equation.
(Ratio of total area occupied by small- and large-diameter bubbles [%])
= 100 x (total area occupied by small-diameter bubbles + total area occupied by large-diameter bubbles) / area of measurement part
[0029]
Similarly, the ratio of the total area occupied by the small-diameter bubbles to the total area occupied by the small-diameter bubbles and the large-diameter bubbles is calculated by the following equation.
(Ratio of total area occupied by small-diameter bubbles to total area occupied by small-diameter bubbles and large-diameter bubbles [%])
= 100 × total area occupied by small-diameter bubbles / (total area occupied by small-diameter bubbles + total area occupied by large-diameter bubbles)
[0030]
Furthermore, the ratio of the total area occupied by cells having a cell diameter of 0.3 mm or more in the thickness direction of the styrene resin foam board is calculated by the following equation.
(Ratio [%] of the total area occupied by cells having a cell diameter of 0.3 mm or more in the thickness direction of the styrene resin foam plate)
= 100 × total area occupied by bubbles having a cell diameter of 0.3 mm or more in the thickness direction of the styrene resin foam board / area of the measurement portion
[0031]
When the amount of butane contained in the foamed board 30 days after the extrusion foaming in the styrene-based resin foamed board is small, the heat insulating property of the styrene-based resin foamed board is reduced. Is reduced to 1.5% by weight or more and less than 3.0% by weight. It is preferably at least 0.8% by weight and less than 2.5% by weight.
[0032]
The amount of butane contained in the foamed styrene resin foam board 30 days after the extrusion is measured in the following manner. That is, from the styrene resin foam plate 30 days after the extrusion foaming, the surface layer portion between the both surfaces of the styrene resin foam plate and the portion 2 mm inward in the thickness direction from each of both surfaces is excluded. A rectangular parallelepiped having a size of 35 mm in the extrusion direction, 5 mm in a direction along the surface of the styrene resin foam plate and perpendicular to the extrusion direction, and 5 mm in the thickness direction from the styrene resin foam plate from which the surface layer is excluded. A test piece having a shape is cut out, and the weight of the test piece is measured.
[0033]
Then, the test piece is supplied to a pyrolysis furnace at 150 ° C. to obtain a chart from gas chromatography, and the amount of butane in the test piece is calculated from the chart based on a calibration curve of butane measured in advance, It is calculated based on the following equation.
[0034]
(Amount of butane contained in the styrene resin foam plate 30 days after extrusion foaming)
= 100 x amount of butane in test piece / weight of test piece
[0035]
The styrene-based resin foam board may include an inorganic compound such as talc, calcium carbonate, calcium silicate, or titanium oxide, a phenolic antioxidant; a light-resistant stabilizer; a flame retardant; An antistatic agent such as acid monoglyceride; a coloring agent such as a pigment; and an additive such as a higher fatty acid metal salt such as magnesium stearate may be contained.
[0036]
If the amount of the talc added is large, the proportion of small-diameter bubbles in the cells of the styrene-based resin foam plate may decrease, so that 1.5 parts by weight or less based on 100 parts by weight of the styrene-based resin is used. Preferably, it is 1.0 part by weight or less, more preferably 0.5 part by weight or less.
[0037]
Next, a method for producing a styrene resin foam board will be described. This styrene-based resin foam board supplies 100 parts by weight of a styrene-based resin, 2.0 to 4.0 parts by weight of hexabromocyclododecane as a flame retardant, and 0.3 to 2.0 parts by weight of synthetic mica to an extruder. 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, 0.5 to 1.5 parts by weight of water, It can be produced by extruding foam from an extruder after press-fitting 0.3 to 2.0 parts by weight of carbon dioxide.
[0038]
The styrene-based resin is not particularly limited, and examples thereof include homopolymers of styrene-based monomers such as styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, chlorostyrene, and bromostyrene, and styrene-based monomers. Copolymers of two or more kinds of copolymers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, butadiene, and other styrene monomers Is mentioned. In addition, the copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. 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.
[0039]
When the amount of the hexabromocyclododecane is small, the flame retardancy of the styrene-based resin foam plate is reduced. When the amount is large, small-diameter bubbles and large-diameter bubbles are caused to coexist at the above ratio. Styrene-based resin foam board may be deteriorated, or the heat-insulating property of the styrene-based resin foam board may be reduced, or a problem may occur when recycling the styrene-based resin foam board. It is limited to 4.0 parts by weight, and preferably 2.5 to 3.5 parts by weight.
[0040]
Further, the synthetic mica is an artificially produced mica having a composition in which all the —OH groups in the crystal structure of the natural mica are substituted with —F, unlike the natural mica, and 3 AlSi 3 O 10 F 2 Is an ideal composition.
[0041]
And, when the average particle size of the synthetic mica is small, the bulk specific gravity becomes small, and when supplied to the extruder, it aggregates and the dispersion in the resin becomes insufficient, so that small-diameter bubbles are generated in the styrene-based resin foam plate. In some cases, it is difficult to form, and when it is large, the number of bubble nuclei is reduced and small-diameter bubbles may be difficult to be formed. Therefore, 1 to 50 μm is preferable, 1 to 20 μm is more preferable, and 1 to 10 μm is particularly preferable. .
[0042]
The average particle size of the synthetic mica refers to that measured by a laser scattering method. Specifically, Shimadzu Corporation has a trade name of “SALD-2100”, and Nikkiso Co., Ltd. has a trade name of “Microtrack 9320HRA”. It can be measured by a wet method using a commercially available measuring device.
[0043]
If the amount of synthetic mica is small, it is difficult to form small-diameter bubbles and large-diameter bubbles at the above-described specific ratio, and the heat insulating property of the styrene-based resin foam plate is reduced. Since the synthetic mica aggregates, it is difficult to form small-diameter bubbles and large-diameter bubbles at the above-described specific ratio, and the heat insulating property of the styrene-based resin foam plate is reduced. Is limited to 0.3 to 2.0 parts by weight, more preferably 0.5 to 1.8 parts by weight, and particularly preferably 0.8 to 1.5 parts by weight.
[0044]
Further, as the organic foaming agent, one composed of dimethyl ether and butane is used. Examples of the butane include isobutane and normal butane, which may be used alone or in combination.
[0045]
When isobutane and normal butane are used in combination as butane, if the content of isobutane in butane is small, the heat insulating property of the styrene-based resin foam plate may be reduced. % By weight or more is more preferable.
[0046]
Also, when the content of dimethyl ether in the organic foaming agent is small, the butane content is relatively large and the flame retardancy of the styrene-based resin foam board is reduced, and when the content is large, the butane content is relatively large. Since the heat-insulating properties of the foamed styrene-based resin board decrease, the content is limited to 60 to 80% by weight. For the same reason, the content of butane in the organic blowing agent is limited to 20 to 40% by weight.
[0047]
If the amount of the organic foaming agent is small, the expansion ratio of the styrene-based resin foam plate is reduced, and the heat insulating property and the lightness are reduced. Therefore, the amount is limited to 3 to 15 parts by weight based on 100 parts by weight of the styrene resin.
[0048]
Further, the water injected into the molten styrene-based resin is not particularly limited, but it is preferable to use water having a small amount of impurities, for example, pure water. When the amount of water added is small, the proportion of small-diameter bubbles in the styrene-based resin foam board is reduced, and the heat insulation of the styrene-based resin foam board is reduced. The ratio of small-diameter bubbles is reduced, and the heat insulating property of the styrene-based resin foam board is reduced, or a good styrene-based resin foam board is obtained due to discharge fluctuation when extruding and foaming the styrene-based resin from an extruder. Therefore, the amount is limited to 0.5 to 1.5 parts by weight, more preferably 0.6 to 1.0 part by weight, based on 100 parts by weight of the styrene resin.
[0049]
Also, when the amount of carbon dioxide added is small, the proportion of large and small-diameter bubbles occupied by the styrene-based resin foam board or the proportion of small-diameter bubbles occupied is reduced, and the heat insulation of the styrene-based resin foam board is reduced. If the amount is too low or too large, internal foaming or bumping occurs at the time of foaming and a good styrene-based resin foam board cannot be obtained. It is limited and preferably 0.5 to 1.5 parts by weight.
[0050]
Here, in the method for producing a styrene-based resin foam plate of the present invention, by supplying synthetic mica, water and carbon dioxide to the styrene-based resin at a predetermined ratio, despite the presence of hexabromocyclododecane as a flame retardant. The diameter of the main cell can be less than 0.30 mm, and the cell diameter in the thickness direction of the styrene-based resin foam plate can be stably formed in a large number of cells having a diameter of 0.10 mm or less. It is possible to obtain a styrene-based resin foam plate in which small-diameter bubbles and large-diameter bubbles coexist at a predetermined ratio and have a fine overall cell diameter.
[0051]
Although the reason for this has not been clearly elucidated, the synthetic mica is formed in layers, and the layers are exfoliated from each other by the shear stress in the extruder to form a fine shape, and then uniformly dispersed in the molten styrene resin. At the same time, synthetic mica adsorbs water on its surface. As a result, the number of coexistence points of synthetic mica and water, which are considered to be bubble nuclei for forming small-diameter bubbles, increases.
[0052]
Further, carbon dioxide has a property of being easily dissolved in water as well as being dissolved in a styrenic resin, and has an action of increasing the generation efficiency of actual microbubbles from bubble nuclei due to a high vapor pressure.
[0053]
As a result of the above combined action, a large number of coexistence points of synthetic mica, water and carbon dioxide having a high ability to generate small-diameter bubbles, and a small-diameter bubble having a cell diameter of 0.1 mm or less in the thickness direction of the styrene resin foam plate. Are likely to be stably formed.
[0054]
In the process of forming bubbles, large-diameter bubbles are formed by synthetic mica with little water adsorption, growth bubbles from a bubble nucleus of carbon dioxide alone, and bubbles adjacent to each other when a part of the bubble wall of the small-diameter bubbles is broken. Are thought to be formed by bonding.
[0055]
In order to make the main cells of the styrene-based resin foam plate have a diameter of less than 0.3 mm in the thickness direction, the effect of carbon dioxide is particularly large, and the conventional talc increase in the amount of talc is 0.1 mm or less. There is a problem that small-diameter bubbles disappear.
[0056]
As described above, in addition to the organic foaming agent, by adding synthetic mica, water and carbon dioxide at a predetermined ratio to the styrene-based resin, small- and large-diameter bubbles are stably formed at a predetermined ratio. can do.
[0057]
The organic blowing agent, water and carbon dioxide may be simultaneously injected into the styrene resin in a molten state. However, since water has an action of decomposing hexabromocyclododecane as a flame retardant, the organic After press-fitting the blowing agent and carbon dioxide into the molten styrene resin, it is preferable to minimize the contact time between water and hexabromocyclododecane by pressing water into the molten styrene resin. .
[0058]
Further, in the above, an organic foaming agent, water and carbon dioxide are pressed into the styrene resin as the foaming agent, but the organic foaming agent may be used as long as the physical properties of the obtained styrene resin foam board are not impaired. A blowing agent other than water, carbon dioxide and water may be added, but it is preferable not to use a blowing agent containing a halogen atom.
[0059]
Examples of such a foaming agent include nitrogen, methyl chloride, 1,1-difluoroethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane, 1,1,1,2. , 2-pentafluoroethane and the like.
[0060]
【Example】
(Examples 1-4 Comparative Examples 1-6)
As an extruder, a tandem type extruder in which a second extruder was connected to the tip of a first extruder was used. The amount of polystyrene (trade name "Toyo Styrene Co., Ltd." HRM-18 ”), hexabromocyclododecane, synthetic mica (trade name“ ME-100 ”manufactured by Corp Chemical Co., average particle size: 3 μm) and talc were melted and kneaded at 210 ° C.
[0061]
Further, after the amounts of the organic blowing agent comprising dimethyl ether and butane shown in Table 1 and carbon dioxide were simultaneously injected into the molten polystyrene from the tip of the first extruder, water was added to the tip of the first extruder. From above into a molten polystyrene.
[0062]
Then, the polystyrene in a molten state in the first extruder was continuously supplied into the second extruder, and after the polystyrene was cooled to a temperature suitable for foaming in the second extruder, it was attached to the tip of the second extruder. It is extruded and foamed at 126 ° C. from a die of a T-type die (lip width: 70 mm, lip thickness: 1.2 mm), and the obtained molten foams are parallel to each other with a vertical interval of 30 mm. The styrene-based resin foam plate having a rectangular cross section with a dimension shown in Table 2 was manufactured by supplying the material between a pair of plates provided and molding. In addition, the discharge amount of polystyrene from the second extruder was 35 kg / hour.
[0063]
In Comparative Example 5, a good styrene-based resin foam plate was not obtained due to discharge fluctuations in the second extruder. In Comparative Example 6, bumping occurred and a good styrene-based resin foam plate was obtained. Did not.
[0064]
In the styrene-based resin foam board obtained as described above, the ratio of the total area occupied by small- and large-diameter bubbles on the cut surface cut along a plane perpendicular to the extrusion direction (large- and small-diameter bubble occupancy), small-diameter bubbles And the ratio of the total area occupied by the small-diameter bubbles to the total area occupied by the large-diameter bubbles (small-diameter bubble occupancy), and the ratio of the total area occupied by the bubbles having a bubble diameter in the thickness direction of 0.3 mm or more (0.3 mm or more) (Bubble occupancy), butane content (butane residual gas content), flammability, thermal conductivity and density contained in the foamed plate 30 days after extrusion foaming were measured by the following methods. The results are shown in Table 2. Indicated.
[0065]
(Butane residual gas amount)
From the both surfaces of the styrene resin foam plate 30 days after extrusion foaming, the surface layer portion between the both surfaces of the styrene resin foam plate and the portion which is located inside by 2 mm in the thickness direction from each of both surfaces is excluded. A rectangular parallelepiped having a size of 35 mm in the extrusion direction, 5 mm in a direction along the surface of the styrene resin foam plate and perpendicular to the extrusion direction, and 5 mm in the thickness direction from the styrene resin foam plate from which the surface layer is excluded. A test piece having a shape was cut out, and the weight of the test piece was measured.
[0066]
The test piece was supplied to a 150 ° C. pyrolysis furnace (trade name “PYR-1A” manufactured by Shimadzu Corporation) to obtain a chart from gas chromatography (trade name “GC-14B” manufactured by Shimadzu Corporation). The amount of butane in the test piece was calculated from the above chart based on the calibration curve of butane measured in advance, and was calculated based on the following equation.
(Butane residual gas amount) = 100 × Amount of butane in test piece / Weight of test piece
[0067]
(Combustion quality)
JIS A9511 -1995 Measured in accordance with the flammability test of measurement method A specified in JIS A9511. -1995 Were satisfied when the flame retardancy specified in was satisfied, and × when the flame retardancy was not satisfied.
[0068]
(Thermal conductivity)
From the styrene-based resin foam plate 30 days after the extrusion foaming, a surface layer portion between both sides of the styrene-based resin foam plate and a portion of each of the both surfaces, which is inside by 2 mm in the thickness direction, is excluded. A test piece having a size of 200 mm in the extrusion direction, 15 mm in a direction along the surface of the styrene resin foam plate and orthogonal to the extrusion direction, and 25 mm in the thickness direction from the styrene resin foam plate from which the surface layer is excluded. Was cut out.
[0069]
Then, the thermal conductivity of the test piece was measured according to JIS A1412. −1994 The measurement was performed in accordance with the flat plate heat flow meter method specified in “Method for measuring thermal conductivity and thermal resistance of thermal insulating material”.
[0070]
(density)
The density of the styrene resin foam plate was measured according to JIS K7222.
[0071]
[Table 1]
[Table 2]
【The invention's effect】
The styrene-based resin foam plate according to claim 1, which is a styrene-based resin foam plate obtained by extrusion-foaming from an extruder, wherein the bubbles mainly include small-diameter bubbles having a bubble diameter in the thickness direction of 0.10 mm or less, and In the cut surface cut in a plane perpendicular to the extrusion direction, the ratio of the total area occupied by the small-diameter bubbles and the large-diameter bubbles is made up of large-diameter bubbles having a bubble diameter in the direction of 0.15 mm or more and less than 0.30 mm. 85% or more, and the ratio of the total area occupied by the small-diameter bubbles to the total area occupied by the small-diameter bubbles and the large-diameter bubbles is 30 to 80%. Since the amount is not less than 1.5% by weight and less than 3.0% by weight, both the heat insulating property and the flame retardancy are excellent and the thickness can be increased.
[0074]
Further, the styrene-based resin foam board according to claim 2 is characterized in that the styrene-based resin foam board according to claim 1 has a thermal conductivity of not more than 0.0280 W / m · K after 30 days from the extrusion. Because of the characteristics, the heat insulation is further improved.
[0075]
Furthermore, the method for producing a styrene-based resin foam board according to claim 3 includes: 100 parts by weight of a styrene-based resin, 2.0 to 4.0 parts by weight of hexabromocyclododecane, and 0.3 to 2.0 parts by weight of synthetic mica. The mixture is supplied to an extruder, melted and kneaded, and 3 to 15 parts by weight of an organic blowing agent comprising 60 to 80% by weight of dimethyl ether and 20 to 40% by weight of butane in the styrene resin in a molten state; Since 1.5 parts by weight and 0.3 to 2.0 parts by weight of carbon dioxide are press-fitted and extruded and foamed from an extruder, small-diameter bubbles and large-diameter bubbles are produced in the same manner as in the conventional extrusion foaming procedure. This makes it possible to easily produce a thick styrene-based resin foam plate having excellent heat insulation properties and a thick styrene-based resin foam plate formed at a predetermined ratio.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2007308627A (en) * | 2006-05-19 | 2007-11-29 | Kaneka Corp | Styrenic resin extruded foam |
| WO2018062541A1 (en) * | 2016-09-30 | 2018-04-05 | 富士フイルム株式会社 | Laminate structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007308627A (en) * | 2006-05-19 | 2007-11-29 | Kaneka Corp | Styrenic resin extruded foam |
| WO2018062541A1 (en) * | 2016-09-30 | 2018-04-05 | 富士フイルム株式会社 | Laminate structure |
| JPWO2018062541A1 (en) * | 2016-09-30 | 2019-02-21 | 富士フイルム株式会社 | Laminated structure |
| CN109716009A (en) * | 2016-09-30 | 2019-05-03 | 富士胶片株式会社 | Stepped construction |
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