JP4346363B2 - Polystyrene resin extruded foam and method for producing the same - Google Patents
Polystyrene resin extruded foam and method for producing the same Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、押出発泡法によるポリスチレン系樹脂発泡体及びその製法に関する。更に詳しくは、環境適合性に優れ、押出成形性及びスキン品質が良好で、低密度で断熱特性に優れたポリスチレン系樹脂押出発泡体及びその製法に関する。
【０００２】
【従来の技術】
ポリスチレン系樹脂押出発泡体は樹脂を高温・高圧下の押出機中で溶融し、続いて発泡ガスを注入し、樹脂中に分散溶解して流動性のゲルを形成し、これを押出機のダイスから低圧域に押出して急速に発泡させ冷却することにより均質な板状の押出発泡製品が得られる。
【０００３】
近年、押出発泡法により得られる発泡体についても、従来から使用されてきた代表的な発泡剤であるフロン類はオゾン層破壊作用や地球温暖化作用を有するため地球環境上好ましくない。また、その他の代表的な発泡剤である塩化メチル、塩化エチル等の塩化アルキルについても、その毒性から環境上規制されることが検討されている。
【０００４】
そこで、特開平１１−１５８３１５号公報及び特開平１１−１５８３１７号公報には、発泡剤としてフロン類及び塩化メチル等の塩化アルキルを発泡剤として使用せずに、その代替としてジメチルエーテル等をエーテル系の発泡剤として使用することが開示されている。
【０００５】
しかしながら、ジメチルエーテル等をエーテル系の発泡剤は、ポリスチレン樹脂に対するガス透過性が速いため、経時とともに大気中に拡散し、長時間での発泡体の熱伝導率低下に寄与しないという問題がある。そのため、良好な熱伝導率とするためには、気泡径を非常に小さくし、密度を上げて対処しなければならず、非常なコスト高となる。
【０００６】
また、二酸化炭素等の無機系の発泡剤を用いた場合にも、スチレン樹脂に対するガス透過速度が速いため熱伝導率に省る。
【０００７】
ここで、エーテル系発泡剤及び無機系発泡剤は、どちらもスチレン樹脂に対する溶解度が小さいため、装置内でのゲル圧力が高くなり、耐圧力の大きな装置が必要となる。
【０００８】
このため、特表平９−５０３８１３号公報には、無機発泡剤を５０％以上使用した場合に、無機発泡剤のアルケニル芳香族ポリマーに対する溶解度が比較的低いためシステム圧力（装置内でのゲル圧力）が高くなり、耐圧力の大きな装置が必要となるため、その解決手段として低分子量ポリマーを用いることが開示されている。
【０００９】
しかし、特表平９−５０３８１３号公報に開示されているような低分子量ポリマーを使用した場合に、製品の種類毎に発泡剤組成が異なるため、ある特定の１種類の低分子量ポリマーだけでは、特に無機発泡剤が５０％未満で、有機系発泡剤が５０％を超える発泡剤組成においては、システム圧力（装置内でのゲル圧力）が低くなりすぎて、発泡に必要な所定のダイでの圧力を得るためにダイの開度を狭くしなければならず、このため１００mm等の厚い製品が取りにくく、発泡体を押さえ込んで無理に厚みを取ろうとすると波打ちが発生し、成形が困難となる。結果的に得られた発泡体の圧縮強度バランスであるＣｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）も高くなりすぎて熱伝導率の劣ったものとなり、またスキン品質も劣ったものとなる。この現象は、特に無機発泡剤が５０％未満で、有機系発泡剤が５０％を超える発泡剤組成においては、顕著である。
【００１０】
【特許文献１】
特開平１１−１５８３１５号公報
【特許文献２】
特開平１１−１５８３１７号公報
【特許文献３】
特表平９−５０３８１３号公報
【００１１】
【発明が解決しようとする課題】
そこで、本発明は上記のような従来技術の問題点に鑑みてなされたものであり、その課題は環境適合性に優れ、押出成形性及びスキン品質が良好、低密度で断熱性能に優れたポリスチレン系樹脂押出発泡体を現行装置で製造し、提供することにある。
【００１２】
【課題を解決するための手段】
本発明者は、発泡剤として環境上好ましくないフロン類や塩化アルキル等のハロゲン系化合物を使用しないで環境適合性に優れ、押出成形性及びスキン品質が良好で、低密度で熱伝導率をはじめとして優れた物性を有するスチレン系押出発泡体が得られることを見出した。こうして、本発明によれば、下記が提供される。
【００１３】
（１）発泡剤としてハロゲン系化合物を使用しないスチレン系樹脂押出発泡体であって、ゲルパーミエイション・クロマトグラフィーで測定した質量平均分子量Ｍｗが１００，０００≦Ｍｗ≦１８０，０００以下であるポリスチレン系樹脂ＰＳＬに、同様に測定したＭｗが１９５，０００≦Ｍｗ≦３５０，０００であるポリスチレン系樹脂ＰＳＨがポリスチレン系樹脂全体基準に５質量％以上混合されてなり、厚さ方向の圧縮強度Ｃｖ、幅方向の圧縮強度Ｃｈ、長さ（押出方向）の圧縮強度Ｃｐとの間に、０．２≦Ｃｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）≦０．６の関係を満足し、押出発泡後２８日経過した時点で、ＪＩＳ Ａ９５１１−１９９５に規定されたＢ類保温板の測定方法において測定した熱伝導率が０．０２８Ｗ／ｍ・Ｋ未満であるスチレン系樹脂押出発泡体。
【００１５】
（２）スチレン系樹脂を加熱溶融させ、高温高圧下で、発泡剤を該溶融樹脂に注入し、冷却後、ダイを通じて低圧下に押出発泡して製造される押出発泡体の製造方法であって、発泡剤としてハロゲン系化合物を用いずに、基材樹脂としてゲルパーミエイション・クロマトグラフィーで測定した質量平均分子量Ｍｗが１００，０００≦Ｍｗ≦１８０，０００以下であるポリスチレン系樹脂ＰＳＬに、同様に測定したＭｗが１９５，０００≦Ｍｗ≦３５０，０００であるポリスチレン系樹脂ＰＳＨを全ポリスチレン系樹脂基準に５質量％以上添加し、厚さ方向の圧縮強度Ｃｖ、幅方向の圧縮強度Ｃｈ、長さ（押出方向）の圧縮強度Ｃｐとの間に、０．２≦Ｃｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）≦０．６の関係を満足し、押出発泡後２８日経過した時点で、ＪＩＳ Ａ９５１１−１９９５に規定されたＢ類保温板の測定方法において測定した熱伝導率が０．０２８Ｗ／ｍ・Ｋ未満であるスチレン系樹脂押出発泡体の製造方法。
【００１６】
【発明の実施の形態】
本発明によれば、発泡剤としてハロゲン系化合物を使用せずに、ゲルパーミエイション・クロマトグラフィーで測定した質量平均分子量Ｍｗが１００，０００≦Ｍｗ≦１８０，０００以下であるポリスチレン系樹脂ＰＳＬに、同様に測定したＭｗが１９５，０００≦Ｍｗ≦３５０，０００であるポリスチレン系樹脂ＰＳＨがポリスチレン系樹脂全体基準に５質量％以上混合されてなり、厚さ方向の圧縮強度Ｃｖ、幅方向の圧縮強度Ｃｈ、長さ（押出方向）の圧縮強度Ｃｐとの間に、０．２≦Ｃｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）≦０．６の関係を満足することにより、押出発泡後２８日経過した時点で、ＪＩＳ Ａ９５１１−１９９５に規定されたＢ類保温板の測定方法において測定した熱伝導率が０．０２８Ｗ／ｍ・Ｋ未満となり、環境適合性に優れながら、押出成形性及びスキン品質が良好で、低密度で熱伝導率をはじめとする各種物性に優れるスチレン系樹脂押出発泡体が得られる。
【００１７】
また、３方向の圧縮強度バランスＣｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）を０．２〜０．６にすることにより、良好な圧縮強度及び寸法安定性を有し、更に良好な熱伝導率を維持できることも見出した。このバランスが大きすぎると熱伝導率が悪くなり、小さすぎると圧縮強度及び寸法安定性に劣る。バランスは好ましくは０．２５〜０．５５、更に好ましくは０．３〜０．５である。このバランスの変更の方法としては、ダイ開度と製品厚みの比を操作、ダイから押出された直後にフォームを押える又は引っ張る操作を加える、ダイから押出された発泡体をガラス転移点以上の高温で加熱し延伸された気泡膜の応力を緩和する操作等がある。
【００１８】
更に寸法安定性の点から、厚さ方向の圧縮強度Ｃｖ、幅方向の圧縮強度Ｃｈ，長さ（押出方向）の圧縮強度Ｃｐとの間に、０．５≦Ｃｖ／Ｃｈ≦２．５の関係を満足することが好ましい。この値が小さすぎると、幅方向に配向延伸したものとなり、経時による応力緩和により幅方向に圧縮が大きくなる。また、この値が大きいと逆に長さ方向に配向延伸したものとなり、経時による応力緩和により長さ方向に圧縮が大きくなる。この値は好ましくは０．８≦Ｃｐ／Ｃｈ≦２、より好ましくは１≦Ｃｐ／Ｃｈ≦１．６である。
【００１９】
ゲルパーミエイション・クロマトグラフィーで測定した質量平均分子量Ｍｗが１００，０００≦Ｍｗ≦１８０，０００以下であるポリスチレン系樹脂ＰＳＬと、同様に測定したＭｗが１９５，０００以上であるポリスチレン系樹脂ＰＳＨを混合した樹脂を、高温・高圧下の押出機中で溶融し、続いて発泡ガスを注入し、樹脂中に分散溶解して流動性のゲルを形成し、これを押出機のダイスから低圧域に押出して急速に発泡させ冷却することにより、１）製品の種類の違いによる発泡剤組成毎の溶融ゲル粘度に応じて、ＰＳＬとＰＳＨのフィールド割合を変更することにより、ダイ開度を絞りすぎたりせずに最適なダイでの圧力を得ることができ、大きな製品断面が容易に取れる、このため圧縮強度バランスのコントロールが容易となる、２）ＰＳＬ等の低分子量ポリマー単独に対して、ＰＳＨ等の高分子量ポリマーをブレンドすることにより、スキン表面が良好となると同時に厚み精度も改善される、３）機械的強度及び寸法安定性等の物性も良好となる。
【００２０】
ここで、ＰＳＨのＭｗは最大でも３５０，０００以下である。ＰＳＨのＭｗが３５０，０００を超えるとＰＳＬとの溶融粘度の差が大きくなりすぎて、低密度で独立気泡率の高い発泡体が得にくい。これは、ＰＳＬの粘度に合わせて発泡温度を決めると、ＰＳＨに対しては粘度が高くなりすぎて発泡効率が低下するため高密度化となり、逆にＰＳＨに合わせた発泡温度であると、ＰＳＬの粘度が低くなり気泡膜が破泡しやすくなるためである。
【００２１】
ＰＳＨの全体樹脂に対する割合は、少なくとも５質量％以上である。５質量％未満であると、上記記載の物性等への効果は殆ど現れない。より好ましいＰＳＨの全体樹脂に対する割合は１０〜９０質量％、さらに好ましくは３０〜７０質量％である。
【００２２】
発泡体の熱伝導率を高めるために、カーボンブラック又はグラファイト等の輻射低減剤を添加することにより、更に熱伝導率が改善されることも見出された。
【００２３】
一次気泡と二次気泡を組み合わせることにより、熱伝導率の改善され、同じ熱伝導率では密度が低下できることも見出した。
【００２４】
本発明で使用されるポリスチレン系樹脂は、例えばスチレン、α−メチルスチレン、クロルスチレン、ジクロルスチレン、ジメチルスチレン、ｔ−ブチルスチレン、ビニルトルエンなどのスチレン誘導体、またはこれらの２種以上の組み合わせからなる共重合体、あるいはそれらとアクリル酸、アクリル酸エステル、メタクリル酸、無水マレイン酸、またはブタジエンのような他と容易に重合し得る化合物との共重合体をいう。
【００２５】
本発明において使用される発泡剤としては、物理発泡剤及び熱分解型化学発泡剤がある。物理発泡剤としては、二酸化炭素、窒素、アルゴン、ヘリウム、空気、水等の無機ガス；メタン、エタン、プロパン、ブタン（ノルマルブタン、イソブタン）、ペンタン（ノルマルペンタン、イソペンタン、ネオペンタン、シクロペンタン）、ヘキサン等の脂肪族炭化水素；メタノール、エタノール、プロパノール等の脂肪族アルコール；エーテル系炭化水素等が挙げられる。
【００２６】
中でも、プロパン、ノルマルブタン、イソブタン・ノルマルペンタン、イソペンタン、ネオペンタン、シクロペンタンの炭化水素のいずれか１種以上と二酸化炭素の組み合わせが好ましい。更にはイソブタン、シクロペンタン、二酸化炭素の組み合わせが好ましい。
【００２７】
発泡剤は、一般的に、ポリスチレン樹脂１００質量部当たり約３〜３０質量部の量で注入する。
【００２８】
また、本発明の発泡性樹脂混合物には、必要に応じて気泡の大きさを調整するためタルク、ケイ酸カルシウム等の気泡調整剤、難燃性を付与するためヘキサブロモシクロドデカン、モノクロロペンタブロモシクロヘキサンの如き難燃剤、ステアリン酸バリウム、ステアリン酸カルシウム等の押出助剤、酸化マグネシウム、ピロリン酸テトラナトリウム等の脱酸剤等を添加することが望ましい。
【００２９】
本発明のスチレン系樹脂押出発泡体の製造方法は、スチレン系樹脂を加熱溶融させ、高温高圧下で、発泡剤を該溶融樹脂に注入し、押出発泡に適する温度に冷却し、ダイを通じて低圧下に押出発泡して製造するが、発泡剤としてハロゲン系化合物を用いずに上記記載の発泡剤を用いること、ゲルパーミエイション・クロマトグラフィーで測定した質量平均分子量Ｍｗが１００，０００≦Ｍｗ≦１８０，０００以下であるポリスチレン系樹脂ＰＳＬに、同様に測定したＭｗが１９５，０００≦Ｍｗ≦３５０，０００であるポリスチレン系樹脂ＰＳＨがポリスチレン系樹脂全体基準に５質量％以上混合されていること、０．２≦Ｃｖ／（Ｃｖ＋Ｃｈ＋Ｃｐ）≦０．６の関係を満足させること以外は、公知の方法と同様であることができ、それによって押出発泡後２８日経過した時点で、ＪＩＳ Ａ９５１１−１９９５に規定されたＢ類保温板の測定方法において測定した熱伝導率が０．０２８Ｗ／ｍ・Ｋ未満であるスチレン系樹脂押出発泡体の製造が可能にされる。
【００３０】
【実施例】
以下において、「部」は質量部を表わす。
実施例１
質量平均分子量１４０，０００のスチレン樹脂９０部と質量平均分子量２１０，０００のスチレン樹脂７０部とを混合した原料に対して、ステアリン酸バリウム０．０５質量部、ヘキサブロモシクロドデカン３質量部を押出機ホッパーより投入し、発泡剤としてイソブタン２質量部、シクロペンタン２質量部、二酸化炭素２．５質量部を圧入し混練した後、冷却機でゲルを均一に冷却し、ダイから大気圧下に押出発泡した。押出機出口からダイ入口までのゲル系内の圧力は、現行設備の耐圧以内であり問題はなかった。得られた発泡体を常温で１週間（ただし、熱伝導率は常温で２８日間）保持した後に物性測定した結果を第１表に示した。
【００３１】
得られた発泡体の物性は下記の方法で測定した。
（密度）
発泡体密度＝発泡体質量／発泡体体積
（気泡径）
ＡＳＴＭ Ｄ ３５６７に準じて測定
（スキン品質）
目視により判断
（寸法変化）
７０℃オーブンに１週間保管し、その前後での体積変化を測定。
【００３２】
○：変化率２％以下
△：変化率２％超５％以下
×：変化率５％超
（圧縮強度）
ＪＩＳ Ａ ９５１１に準じて３方向（厚さ、幅、長さ方向）を測定
（熱伝導率）
ＪＩＳ Ａ ９５１１に準じて測定
◎： λ＜０．０２７Ｗ／ｍ・Ｋ
○： ０．０２７≦λ＜０．０２７５Ｗ／ｍ・Ｋ
△： ０．０２７５≦λ＜０．０２８０Ｗ／ｍ・Ｋ
×： ０．０２８≦λ
実施例２
質量平均分子量１４０，０００のスチレン樹脂５０部と質量平均分子量２１０，０００のスチレン樹脂５０部とを混合した原料を用いた以外は、実施例１と同様に実施した。
実施例３
質量平均分子量１４０，０００のスチレン樹脂９０部と質量平均分子量２１０，０００のスチレン樹脂１０部とを混合した原料に対して、カーボンブラックを７ｐｐｈ添加した以外は、実施例１と同様に実施した。
実施例４
質量平均分子量１４０，０００のスチレン樹脂３０部と質量平均分子量２１０，０００のスチレン樹脂７０部とを混合した原料を用いた以外は、実施例１と同様に実施した。
実施例５
質量平均分子量１４０，０００のスチレン樹脂５０部と質量平均分子量２１０，０００のスチレン樹脂５０部とを混合した原料を用い、表１に示す発泡剤組成を使用した以外は、実施例１と同様に実施した。
実施例６
質量平均分子量１４０，０００のスチレン樹脂５０部と質量平均分子量２１０，０００のスチレン樹脂５０部とを混合した原料を用い、表１に示す発泡剤組成を使用した以外は、実施例１と同様に実施した。
実施例７
質量平均分子量１４０，０００のスチレン樹脂３０部と質量平均分子量２１０，０００のスチレン樹脂７０部とを混合した原料を用い、表１に示す発泡剤組成を使用した以外は、実施例１と同様に実施した。
実施例８
質量平均分子量２１０，０００のスチレン樹脂を原料として用い、表１に示す発泡剤組成を使用した以外は、実施例１と同様に実施した。
実施例９
質量平均分子量１４０，０００のスチレン樹脂５０部と質量平均分子量２１０，０００のスチレン樹脂５０部とを混合した原料を用い、表１に示す発泡剤組成を使用した以外は、実施例１と同様に実施した。
比較例１
質量平均分子量１４０，０００のスチレン樹脂１００部を樹脂原料として用いた以外は、実施例１と同様に実施した。
比較例２
質量平均分子量２１０，０００のスチレン樹脂１００部を樹脂原料として用い、ダイから押出された直後の発泡体に引張操作を加えた以外は、比較例１と同様に実施した。
【００３３】
押出機出口からダイ入口までのゲル系内の圧力が高く、本設備では、耐圧の高い高価な設備が必要となる。
比較例３，４
表１に示した発泡剤組成を用いた以外は、比較例１と同様に実施した。
【００３４】
【表１】
【発明の効果】
本発明によれば、塩化アルキル等の環境に影響を及ぼす発泡ガスを使用せずに、高価な設備を必要とせずに現有設備にて、スキン品質が良好で、優れた機械的特性及び寸法安定性を有するスチレン系樹脂押出発泡体を安定して生産できる。また、発泡剤の組成比に応じて、スチレン樹脂の配合比率を自由に変更できるので、オペレーションウインドーが広く安定生産ができる。
【００３６】
ゲル粘度を増大させる輻射低減剤等を含んでも、樹脂の組成比率を変更することにより、現行設備にての生産が可能である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polystyrene resin foam by an extrusion foaming method and a method for producing the same. More specifically, the present invention relates to a polystyrene resin extruded foam having excellent environmental compatibility, excellent extrudability and skin quality, low density and excellent heat insulating properties, and a method for producing the same.
[0002]
[Prior art]
Polystyrene resin extruded foam melts the resin in an extruder under high temperature and high pressure, then injects foaming gas, disperses and dissolves in the resin to form a flowable gel, which is formed in the die of the extruder. A homogeneous plate-like extruded foamed product is obtained by extruding from a low pressure region to a low pressure region and rapidly foaming and cooling.
[0003]
In recent years, as for foams obtained by the extrusion foaming method, chlorofluorocarbons, which are typical foaming agents that have been used in the past, are not preferable in terms of the global environment because they have an ozone layer destroying action and a global warming action. In addition, other typical blowing agents such as methyl chloride and ethyl chloride such as ethyl chloride are also being considered for environmental restrictions due to their toxicity.
[0004]
Therefore, in JP-A-11-158315 and JP-A-11-158317, chlorofluorocarbons and alkyl chlorides such as methyl chloride are not used as a blowing agent as a foaming agent, but dimethyl ether or the like is used instead of an ether type as a foaming agent. It is disclosed for use as a blowing agent.
[0005]
However, an ether-based foaming agent such as dimethyl ether has a problem in that it has a high gas permeability to polystyrene resin, so that it diffuses into the atmosphere over time and does not contribute to a decrease in the thermal conductivity of the foam over a long period of time. Therefore, in order to obtain a good thermal conductivity, the bubble diameter must be made very small, the density must be increased, and the cost becomes very high.
[0006]
Also, when an inorganic foaming agent such as carbon dioxide is used, the gas permeation rate with respect to the styrene resin is high, so that the thermal conductivity is omitted.
[0007]
Here, since both ether type foaming agents and inorganic type foaming agents have low solubility in styrene resin, the gel pressure in the apparatus becomes high, and an apparatus with high pressure resistance is required.
[0008]
For this reason, in Japanese National Publication No. 9-503813, when an inorganic blowing agent is used in an amount of 50% or more, since the solubility of the inorganic blowing agent in the alkenyl aromatic polymer is relatively low, the system pressure (gel pressure in the apparatus) ) And a device with a high pressure resistance is required, and it is disclosed that a low molecular weight polymer is used as a solution.
[0009]
However, when a low molecular weight polymer as disclosed in JP-A-9-50381 is used, the composition of the foaming agent is different for each type of product, so with only one specific low molecular weight polymer, In particular, in a foaming agent composition having an inorganic foaming agent of less than 50% and an organic foaming agent of more than 50%, the system pressure (gel pressure in the apparatus) becomes too low, and the predetermined die required for foaming In order to obtain pressure, the opening of the die has to be narrowed. For this reason, it is difficult to obtain a thick product such as 100 mm, and if the foam is pressed down and the thickness is forced, undulation occurs and molding becomes difficult. . As a result, Cv / (Cv + Ch + Cp), which is the compressive strength balance of the foam obtained, is too high, resulting in poor thermal conductivity, and poor skin quality. This phenomenon is remarkable particularly in a foaming agent composition in which the inorganic foaming agent is less than 50% and the organic foaming agent exceeds 50%.
[0010]
[Patent Document 1]
JP-A-11-158315 [Patent Document 2]
JP 11-158317 A [Patent Document 3]
Japanese National Patent Publication No. 9-503813
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and the problem is that polystyrene has excellent environmental compatibility, good extrudability and skin quality, low density and excellent heat insulation performance. It is to manufacture and provide a resin-based extruded foam with current equipment.
[0012]
[Means for Solving the Problems]
The present inventor does not use environmentally undesirable halogenated compounds such as chlorofluorocarbons and alkyl chloride as a foaming agent, has excellent environmental compatibility, good extrudability and skin quality, low density, and high thermal conductivity. It was found that a styrene-based extruded foam having excellent physical properties can be obtained. Thus, according to the present invention, the following is provided.
[0013]
(1) A polystyrene-extruded styrene resin foam that does not use a halogen compound as a foaming agent and has a mass average molecular weight Mw measured by gel permeation chromatography of 100,000 ≦ Mw ≦ 180,000 or less. The polystyrene resin PSH having a Mw of 195,000 ≦ Mw ≦ 350,000 measured in the same manner is mixed with the resin PSL in an amount of 5% by mass or more based on the entire polystyrene resin, and the compressive strength Cv in the thickness direction is When the compressive strength Ch in the width direction and the compressive strength Cp in the length (extrusion direction) satisfy the relationship of 0.2 ≦ Cv / (Cv + Ch + Cp) ≦ 0.6, and 28 days have passed after extrusion foaming. , styrene thermal conductivity was measured at a defined measuring method B class insulation board in JIS A9511 -1995 is less than 0.028 W / m · K System resin extruded foam.
[0015]
( 2 ) A process for producing an extruded foam produced by heating and melting a styrene-based resin, injecting a foaming agent into the molten resin under high temperature and high pressure, and cooling and then extruding and foaming under low pressure through a die. In the same manner as polystyrene resin PSL having a mass average molecular weight Mw measured by gel permeation chromatography as a base resin and not more than 100,000 ≦ Mw ≦ 180,000, without using a halogen compound as a foaming agent. A polystyrene resin PSH having a measured Mw of 195,000 ≦ Mw ≦ 350,000 was added in an amount of 5% by mass or more based on the total polystyrene resin, and the compressive strength Cv in the thickness direction, the compressive strength Ch in the width direction, and the length When the relationship of 0.2 ≦ Cv / (Cv + Ch + Cp) ≦ 0.6 is satisfied with the compressive strength Cp of the length (extrusion direction), and 28 days have passed after extrusion foaming. JIS A9511 -1995 defined Class B heat insulating board manufacturing method of the measured thermal conductivity of less than 0.028 W / m · K styrene resin extruded foam in the measurement method of the.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention , the polystyrene-based resin PSL whose mass average molecular weight Mw measured by gel permeation chromatography is 100,000 ≦ Mw ≦ 180,000 or less is used without using a halogen-based compound as a foaming agent . Similarly, a polystyrene resin PSH having a measured Mw of 195,000 ≦ Mw ≦ 350,000 is mixed in an amount of 5% by mass or more based on the whole polystyrene resin , and compressive strength Cv in the thickness direction and compression in the width direction. By satisfying the relationship of 0.2 ≦ Cv / (Cv + Ch + Cp) ≦ 0.6 between the strength Ch and the compressive strength Cp of the length (extrusion direction), when 28 days have passed after extrusion foaming, JIS A9511 -1995 a defined class B insulation board measured thermal conductivity of 0.028 W / m · K than next in the measurement method, excellent in environmental compatibility While, good extrusion moldability and skin quality, a styrene resin extruded foam which is excellent in various properties including thermal conductivity at low density.
[0017]
In addition, it has also been found that by setting the compressive strength balance Cv / (Cv + Ch + Cp) in three directions to 0.2 to 0.6, it has good compressive strength and dimensional stability and can further maintain good thermal conductivity. . If this balance is too large, the thermal conductivity will be poor, and if it is too small, the compressive strength and dimensional stability will be poor. The balance is preferably 0.25 to 0.55, more preferably 0.3 to 0.5. As a method of changing the balance, the ratio of the die opening to the product thickness is manipulated, and the foam is pushed or pulled immediately after being extruded from the die, and the foam extruded from the die is heated to a temperature higher than the glass transition point. There is an operation to relieve the stress of the bubble film heated by heating.
[0018]
Further, from the viewpoint of dimensional stability, 0.5 ≦ Cv / Ch ≦ 2.5 between the compressive strength Cv in the thickness direction, the compressive strength Ch in the width direction, and the compressive strength Cp in the length (extrusion direction). It is preferable to satisfy the relationship. If this value is too small, the film is oriented and stretched in the width direction, and compression in the width direction increases due to stress relaxation over time. On the other hand, when this value is large, the film is oriented and stretched in the length direction, and the compression increases in the length direction due to stress relaxation over time. This value is preferably 0.8 ≦ Cp / Ch ≦ 2, more preferably 1 ≦ Cp / Ch ≦ 1.6.
[0019]
A polystyrene resin PSL whose mass average molecular weight Mw measured by gel permeation chromatography is 100,000 ≦ Mw ≦ 180,000 and a polystyrene resin PSH whose Mw measured similarly is 195,000 or more are used. The mixed resin is melted in an extruder under high temperature and high pressure, and then a foaming gas is injected, and dispersed and dissolved in the resin to form a fluid gel, which is transferred from the die of the extruder to the low pressure region. By extruding and rapidly foaming and cooling 1) Changing the field ratio of PSL and PSH according to the melt gel viscosity for each foaming agent composition due to the difference in product type, too much die opening The pressure at the optimum die can be obtained without the need for it, and a large cross section of the product can be taken easily, which makes it easy to control the compressive strength balance 2) Blending a high molecular weight polymer such as PSH with a low molecular weight polymer such as SL alone improves the skin surface and also improves the thickness accuracy. 3) Physical properties such as mechanical strength and dimensional stability It becomes good.
[0020]
Here, the Mw of PSH is 350,000 or less at the maximum. When the Mw of PSH exceeds 350,000, the difference in melt viscosity from PSL becomes too large, and it is difficult to obtain a foam having a low density and a high closed cell ratio. This is because when the foaming temperature is determined in accordance with the viscosity of PSL, the viscosity becomes too high for PSH and the foaming efficiency is lowered, resulting in higher density. Conversely, if the foaming temperature is matched with PSH, PSL This is because the viscosity of the film becomes low and the bubble film easily breaks.
[0021]
The ratio of PSH to the total resin is at least 5% by mass or more . If it is less than 5% by mass, the above-described effects on the physical properties and the like hardly appear. A more preferable ratio of PSH to the total resin is 10 to 90% by mass, and further preferably 30 to 70% by mass.
[0022]
It has also been found that adding a radiation reducing agent such as carbon black or graphite to further improve the thermal conductivity of the foam further improves the thermal conductivity.
[0023]
It has also been found that by combining primary bubbles and secondary bubbles, the thermal conductivity is improved and the density can be lowered with the same thermal conductivity.
[0024]
Examples of the polystyrene resin used in the present invention include styrene derivatives such as styrene, α-methylstyrene, chlorostyrene, dichlorostyrene, dimethylstyrene, t-butylstyrene, and vinyltoluene, or combinations of two or more thereof. Or a copolymer of these with a compound that can be easily polymerized with others such as acrylic acid, acrylic ester, methacrylic acid, maleic anhydride, or butadiene.
[0025]
Examples of the foaming agent used in the present invention include physical foaming agents and pyrolytic chemical foaming agents. As the physical foaming agent, carbon dioxide, nitrogen, argon, helium, air, water and other inorganic gases; methane, ethane, propane, butane (normal butane, isobutane), pentane (normal pentane, isopentane, neopentane, cyclopentane), Examples thereof include aliphatic hydrocarbons such as hexane; aliphatic alcohols such as methanol, ethanol, and propanol; ether hydrocarbons.
[0026]
Among these, a combination of carbon dioxide with at least one of propane, normal butane, isobutane / normal pentane, isopentane, neopentane, and cyclopentane is preferable. Furthermore, a combination of isobutane, cyclopentane, and carbon dioxide is preferable.
[0027]
The blowing agent is generally injected in an amount of about 3 to 30 parts by mass per 100 parts by mass of polystyrene resin.
[0028]
Further, the foamable resin mixture of the present invention includes, as necessary, a foam regulator such as talc and calcium silicate for adjusting the size of the foam, hexabromocyclododecane and monochloropentabromo for imparting flame retardancy. It is desirable to add a flame retardant such as cyclohexane, an extrusion aid such as barium stearate and calcium stearate, and a deoxidizer such as magnesium oxide and tetrasodium pyrophosphate.
[0029]
In the method for producing a styrene resin extruded foam of the present invention, a styrene resin is heated and melted, a foaming agent is injected into the molten resin under high temperature and high pressure, cooled to a temperature suitable for extrusion foaming, and low pressure through a die. The above foaming agent is used as a foaming agent without using a halogen compound, and the mass average molecular weight Mw measured by gel permeation chromatography is 100,000 ≦ Mw ≦ 180. 0,000 or less of polystyrene resin PSL having a measured Mw of 195,000 ≦ Mw ≦ 350,000 is mixed in an amount of 5% by mass or more based on the entire polystyrene resin, .2 ≦ Cv / (Cv + Ch + Cp) ≦ 0.6, except that the relationship can be satisfied, and can be the same as the known method. Extrusion upon elapsed after foaming 28, JIS A9511 -1995 a defined Class B insulation board measured thermal conductivity in the measurement method is less than 0.028 W / m · K styrene resin extruded foam I Is made possible.
[0030]
【Example】
Hereinafter, “parts” represents parts by mass.
Example 1
Extruded 0.05 parts by weight of barium stearate and 3 parts by weight of hexabromocyclododecane to a raw material obtained by mixing 90 parts of styrene resin having a weight average molecular weight of 140,000 and 70 parts of styrene resin having a weight average molecular weight of 210,000. It is charged from the machine hopper, 2 parts by mass of isobutane, 2 parts by mass of cyclopentane, and 2.5 parts by mass of carbon dioxide are injected and kneaded as a foaming agent. Extrusion foamed. The pressure in the gel system from the extruder outlet to the die inlet was within the pressure resistance of the current equipment, and there was no problem. Table 1 shows the results of physical properties measured after the obtained foam was held at room temperature for 1 week (however, the thermal conductivity was 28 days at room temperature).
[0031]
The physical properties of the obtained foam were measured by the following methods.
(density)
Foam density = foam mass / foam volume (bubble diameter)
Measured according to ASTM D 3567 (skin quality)
Judgment by visual inspection (dimensional change)
Store in a 70 ° C oven for 1 week and measure the volume change before and after.
[0032]
○: Change rate 2% or less △: Change rate 2% or more 5% or less ×: Change rate 5% or more (compressive strength)
Measure in 3 directions (thickness, width, length direction) according to JIS A 9511 (thermal conductivity)
Measured according to JIS A 9511 ◎: λ <0.027 W / m · K
○: 0.027 ≦ λ <0.0275 W / m · K
Δ: 0.0275 ≦ λ <0.0280 W / m · K
×: 0.028 ≦ λ
Example 2
The same procedure as in Example 1 was performed except that a raw material obtained by mixing 50 parts of a styrene resin having a mass average molecular weight of 140,000 and 50 parts of a styrene resin having a mass average molecular weight of 210,000 was used.
Example 3
The same procedure as in Example 1 was performed except that 7 pph of carbon black was added to a raw material obtained by mixing 90 parts of a styrene resin having a mass average molecular weight of 140,000 and 10 parts of a styrene resin having a mass average molecular weight of 210,000.
Example 4
The same procedure as in Example 1 was performed except that a raw material obtained by mixing 30 parts of a styrene resin having a mass average molecular weight of 140,000 and 70 parts of a styrene resin having a mass average molecular weight of 210,000 was used.
Example 5
Example 1 was used except that a raw material obtained by mixing 50 parts of a styrene resin having a mass average molecular weight of 140,000 and 50 parts of a styrene resin having a mass average molecular weight of 210,000 was used and the foaming agent composition shown in Table 1 was used. Carried out.
Example 6
Example 1 was used except that a raw material obtained by mixing 50 parts of a styrene resin having a mass average molecular weight of 140,000 and 50 parts of a styrene resin having a mass average molecular weight of 210,000 was used and the foaming agent composition shown in Table 1 was used. Carried out.
Example 7
Example 1 was used except that a raw material obtained by mixing 30 parts of a styrene resin having a mass average molecular weight of 140,000 and 70 parts of a styrene resin having a mass average molecular weight of 210,000 was used and the foaming agent composition shown in Table 1 was used. Carried out.
Example 8
The same procedure as in Example 1 was performed except that a styrene resin having a mass average molecular weight of 210,000 was used as a raw material and the foaming agent composition shown in Table 1 was used.
Example 9
Example 1 was used except that a raw material obtained by mixing 50 parts of a styrene resin having a mass average molecular weight of 140,000 and 50 parts of a styrene resin having a mass average molecular weight of 210,000 was used and the foaming agent composition shown in Table 1 was used. Carried out.
Comparative Example 1
The same operation as in Example 1 was carried out except that 100 parts of a styrene resin having a mass average molecular weight of 140,000 was used as a resin raw material.
Comparative Example 2
The same procedure as in Comparative Example 1 was performed except that 100 parts of a styrene resin having a mass average molecular weight of 210,000 was used as a resin raw material and a tensile operation was applied to the foam immediately after being extruded from the die.
[0033]
The pressure in the gel system from the extruder outlet to the die inlet is high, and this equipment requires expensive equipment with high pressure resistance.
Comparative Examples 3 and 4
It carried out similarly to the comparative example 1 except having used the foaming agent composition shown in Table 1.
[0034]
[Table 1]
【The invention's effect】
According to the present invention, the use of foaming gas that affects the environment such as alkyl chloride does not require expensive equipment, and the existing equipment has good skin quality, excellent mechanical properties and dimensional stability. Stable styrene resin extruded foam can be produced stably. Moreover, since the blending ratio of the styrene resin can be freely changed according to the composition ratio of the foaming agent, the operation window can be widely and stably produced.
[0036]
Even if a radiation reducing agent or the like that increases the gel viscosity is included, it is possible to produce with current equipment by changing the composition ratio of the resin.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| JP2003191871A JP4346363B2 (en) | 2003-07-04 | 2003-07-04 | Polystyrene resin extruded foam and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
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| JP2003191871A JP4346363B2 (en) | 2003-07-04 | 2003-07-04 | Polystyrene resin extruded foam and method for producing the same |
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| Application Number | Title | Priority Date | Filing Date |
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| JP2009005224A Division JP2009074100A (en) | 2009-01-13 | 2009-01-13 | Polystyrene resin extruded foam |
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| JP4346363B2 true JP4346363B2 (en) | 2009-10-21 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2009074100A (en) * | 2009-01-13 | 2009-04-09 | Dow Kakoh Kk | Polystyrene resin extruded foam |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4227991B2 (en) | 2005-12-28 | 2009-02-18 | トヨタ自動車株式会社 | Exhaust gas analyzer and exhaust gas analysis method |
| JP4594277B2 (en) | 2006-05-31 | 2010-12-08 | トヨタ自動車株式会社 | Sensor unit in exhaust gas analyzer |
| JP4732277B2 (en) | 2006-08-23 | 2011-07-27 | トヨタ自動車株式会社 | Gas analyzer and gas analysis method |
| EP2240539B1 (en) * | 2008-02-06 | 2014-01-22 | Dow Global Technologies LLC | Article and method of producing a low density foam blend of styrenic polymer and polyolefin |
| AU2011252010A1 (en) * | 2010-05-10 | 2012-12-20 | Allergan, Inc. | Porous materials, methods of making and uses |
| JP5793386B2 (en) * | 2011-02-28 | 2015-10-14 | 積水化成品工業株式会社 | Polystyrene resin foam sheet and molded product |
| JP6188053B2 (en) * | 2013-03-14 | 2017-08-30 | ダウ化工株式会社 | Light weight embankment |
| JP7460476B2 (en) | 2020-07-31 | 2024-04-02 | 株式会社ジェイエスピー | Manufacturing method of polystyrene resin extruded foam board |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2009074100A (en) * | 2009-01-13 | 2009-04-09 | Dow Kakoh Kk | Polystyrene resin extruded foam |
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