JP2005023252A - Reclaimed foaming styrenic resin particle, reclaimed foaming bead, and reclaimed foaming styrenic resin moulding - Google Patents
Reclaimed foaming styrenic resin particle, reclaimed foaming bead, and reclaimed foaming styrenic resin moulding Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
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- Y02W30/62—Plastics recycling; Rubber recycling
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Abstract
Description
【0001】
【発明の属する技術分野】
本発明は、発泡スチレン系樹脂成形品を再生して得られる再生発泡性スチレン系樹脂粒子、再生発泡ビーズ及び再生発泡スチレン系樹脂成形品に関する。
【0002】
【従来の技術】
従来、発泡スチレン系樹脂成形品は、一度使用された後、焼却処分されるか、又は熱収縮されポリスチレンとして回収し再利用されているが、再利用の比率は不十分であり、今後、再利用率を上げていくことが、社会的課題とされている。
【0003】
発泡スチレン系樹脂成形品を収縮塊として回収する技術は、既に完成されており、1999年には日本国内での発泡スチレン系樹脂成形品流通量の約33%が熱収縮塊等として回収されており、主に、射出成形による雑貨品、押出成形による建材等の用途に利用されている。このように、現在、発泡スチレン系樹脂成形品の再生利用法は限定されたものであり、その用途の拡大が急がれている。
【0004】
一方、リサイクルという定義からは、発泡性スチレン系樹脂粒子を発泡成形し、最終的に発泡スチレン系樹脂成形品として使用されたスチレン系樹脂を、ポリスチレンとして他の用途に利用するのではなく、発泡性スチレン系樹脂粒子として再利用することが好ましいと考えられるが、現在のところ、発泡スチレン系樹脂成形品から回収されたスチレン系樹脂を発泡性スチレン系樹脂粒子として工業的に再生されている例は少ない。
【0005】
発泡スチレン系樹脂成形品の収縮物等から発泡性スチレン系樹脂粒子を再生する方法としては、上記収縮物を押出機でペレット化しこれに発泡剤を含浸する方法が最も技術的には容易であるが、最も一般的に使用されているストランド式の押出機では、延伸方向に歪が残るため、発泡剤を含浸した再生発泡性スチレン系樹脂粒子は延伸方向に収縮し、扁平状や卵形の形状となる。このため、これを発泡させた発泡ビーズを金型に充填する際、形状が球形でないため充填性が劣り、充填不足による不良が多くなったり、得られた成形品の外観が劣る問題があった。
【0006】
発泡スチレン系樹脂成形品の収縮物等から発泡性スチレン系樹脂粒子を再生する方法としては、粉砕された発泡スチレン系樹脂成形体を押出機中で加熱溶融して得られたペレットを水中に分散させ、次いで触媒を含むスチレン単量体溶液を添加・重合させる方法が提案されている。(例えば、特許文献1参照)
しかし、この方法は、成形時に発生する不良品等の比較的奇麗な成形品については有効であるが、実際に市場で使用され汚れ、異物が付着した成形品を原料とした場合は、押出機のダイスが短時間で目詰まりを起こす問題があり、量産性からダイス径を大きくする必要があり、得られたペレットサイズが大きくなる。ペレットサイズが大きい場合、提案の方法では粒子が球形化しづらく扁平や卵形等の形状となるため、金型への充填性や成形品外観が劣る問題があった。
【0007】
また、発泡スチレン系樹脂成形品の収縮物等から球形の発泡性スチレン系樹脂粒子を再生する方法として、発泡スチレン系樹脂成形品の収縮物を無延伸溶融及び粉砕して得られるスチレン系樹脂粒子を、有機系分散剤を含む水性媒体中に分散し、易揮発性発泡剤を含浸して再生発泡性スチレン系樹脂粒子を製造する方法が提案されている(例えば、特許文献2参照。)。
しかし、この方法においては、発泡スチレン系樹脂成形品の収縮物を押出機等で無延伸ペレットとする必要があるが、無延伸ペレットを作製できる押出機は一般的ではないため、生産できる設備が限定されるため生産量が限定されたり、ペレットサイズが一般的なストランド式押出機で得られたペレットに比べて大きいため、微粉砕して所望の大きさにする必要があり、微粉砕工程が必要な分コスト的に不利であった。
【0008】
【特許文献1】
特開平5−98062号
【特許文献2】
特開平6−87973号公報
【0009】
【発明が解決しようとする課題】
そこで本発明は、発泡スチレン系樹脂成形品から、最も広く採用されているストランド式押出機を使用して得られる再生スチレン系樹脂ペレット(延伸ペレット)から、球形の再生発泡性スチレン系樹脂粒子を製造する方法を提供するものである。
【0010】
【課題点を解決するための手段】
本発明によれば、長さが5.0mm以下、径が3.0mm以下の円柱状で、かつ長さ方向の寸法収縮率が50%以下の、再生スチレン系樹脂ペレットを、核として、水性媒体中に懸濁させ、重合開始剤とスチレン系単量体を、再生スチレン系樹脂ペレットに含浸させ、引き続きスチレン系単量体を加えて重合を行い、その後、含浸温度100℃以上において、発泡剤を含浸させる再生発泡性スチレン系樹脂粒子の製造方法であって、再生発泡性スチレン系樹脂粒子に対する再生スチレン系樹脂ペレットの比率が、70重量%以下である再生発泡性スチレン系樹脂粒子の製造方法が提供される。
【0011】
本発明によれば、上記の再生発泡性スチレン系樹脂粒子の製造方法により得られる再生発泡性スチレン系樹脂粒子が提供される。
【0012】
本発明によれば、上記の再生発泡性樹脂粒子を発泡して得られる再生スチレン系発泡ビーズが提供される。
【0013】
本発明によれば、上記の再生スチレン系発泡ビーズを発泡成形して得られる再生発泡スチレン系樹脂成形品が提供される。
【0014】
本発明によれば、長さが5.0mm以下、径が3.0mm以下の円柱状で、かつ長さ方向の寸法収縮率が50%以下の、再生スチレン系樹脂ペレットからなる、再生発泡性スチレン系樹脂粒子の製造に用いる核が提供される。
【0015】
【発明の実施の形態】
以下、本発明の再生発泡性スチレン系樹脂粒子の製造方法及びこれを発泡成形して得られる発泡成形品について詳しく説明する。
本発明の再生発泡性スチレン系樹脂粒子の製造方法は、核となる再生スチレン系樹脂ペレットを水性媒体中に懸濁させ、重合開始剤とスチレン系単量体を、再生スチレン系樹脂ペレットに含浸させ、引き続きスチレン系単量体を加えて重合を行った後、発泡剤を含浸させる。
【0016】
本発明に用いる再生スチレン系樹脂ペレットは、使用済みの発泡スチレン系樹脂の収縮物又は溶融物を、必要に応じて適当な大きさに粗粉砕した粉砕物を押出成形して作製できる。
使用済みの発泡スチレン系樹脂の収縮物又は溶融物は、予め染料等により着色された使用済みの発泡スチレン系樹脂成形品を除外して作製することが好ましい。着色された成形品が混入すると、それから得られる再生発泡性スチレン系樹脂粒子、発泡成形品が着色し製品価値を損ねるため好ましくない。
【0017】
尚、使用済みの発泡スチレン系樹脂の収縮物又は溶融物の粉砕物に、オレイン酸アミド、ステアリン酸アミド等の脂肪酸モノアミド、メチレンビスステアリン酸アミド、エチレンビスステアリン酸アミド等の脂肪酸ビスアミド、タルク等の無機物を気泡調整剤として混合することができる。この場合、予め粉砕物と気泡調整剤を混合させた後に押出成形する。気泡調整剤の量は適宜配合できるが、例えば、0.01〜2.0重量%である。
粉砕物と気泡調整剤の混合は、従来既知の手段で行うことができる。例えば、リボンブレンダー、Vブレンダー、ヘンシェルミキサー、レディゲーミキサー等の混合機が使用できる。
【0018】
このような粉砕物を、公知の押出機、例えば、単軸押出機、二軸押出機等にストランドダイを取り付けたもの(ストランド式押出機)を使用して、押出成形して、再生スチレン系樹脂ペレットを作製できる。
具体的には、使用済みの発泡スチレン系樹脂の収縮物或は溶融物の粉砕物、又はこれと気泡調整剤の混合物を、押出機に投入し溶融混練させる。押出機先端のダイから、ストランド状に押出された溶融物は、冷却されながらペレタイザーに導入され、適当な長さに切断され、ほぼ円柱形の再生スチレン系樹脂ペレットとする。
【0019】
再生スチレン系樹脂ペレットの延伸方向の長さは、好ましくは5.0mm以下、より好ましくは3.0mm以下である。延伸方向の長さが5.0mmを越えると粒子が球形化し難くなる。また、再生発泡性スチレン系樹脂粒子が小さすぎると需要がないため、ペレットの長さは、0.3mm以上が好ましい。
【0020】
ペレットの径は、好ましくは3.0mm以下、より好ましくは2.0mm以下である。ペレットの径が3.0mmを越えると粒子が球形化し難くなる。また、再生発泡性スチレン系樹脂粒子が小さすぎると需要がないため、ペレットの径は、0.3mm以上が好ましい。
ペレットの長さと径の比率は、好ましくは4:1〜1:2であり、より好ましくは2:1〜1:1である。
【0021】
ペレットの、200℃雰囲気下で10分加熱した後の延伸方向の寸法収縮率は、50%以下、好ましくは30%以下である。寸法収縮率が50%を越えると、得られた粒子が球形化し難くなる。
尚、「延伸されている」とは、押出成形するとき、引き出しながら成形することであり、例えば、寸法収縮率が10%以上である。
【0022】
再生スチレン系樹脂ペレットの、延伸方向の長さは、切断速度を調整すること、例えば、ペレタイザーの回転速度を調整することによって制御できる。
また、ペレットの径及び寸法収縮率は、押出機の吐出量や切断速度(引き取り速度)を調整することによって制御できる。
【0023】
得られる再生スチレン系樹脂ペレットの重量平均分子量は、10万〜25万とすることが好ましい。重量平均分子量が10万未満では、十分な強度が得られない傾向があり、25万を越えると、粒子が球状化し難い傾向がある。より好ましくは15万〜23万である。
【0024】
尚、再生スチレン系樹脂ペレットには、前述した使用済みの発泡スチレン系樹脂の収縮物又は溶融物の粉砕物と同様の添加剤が配合されていてもよい。
【0025】
上記により作製した再生スチレン系樹脂ペレットを、水性媒体中に懸濁させて懸濁液とする。水性媒体中への分散は、通常、攪拌翼を備えた装置を用いて行われ、その条件等に制限はない。
【0026】
再生スチレン系樹脂ペレットは、分散剤と共に分散することが好ましい。本発明に用いる分散剤は、一般的に、懸濁重合に用いられるものであればよく、例えば、ポリビニルアルコール、ポリビニルピロリドン、メチルセルロース等の有機系分散剤、リン酸マグネシウム、リン酸三カルシウム等の難溶性無機塩が挙げられる。
さらに、界面活性剤も用いることができ、例えば、オレイン酸ナトリウム、ドデシルベンゼンスルホン酸ナトリウム、その他懸濁重合で一般的に使用されるアニオン系界面活性剤、ノニオン系界面活性剤のいずれでも使用できる。
これらの分散剤の中では、スチレン系単量体の油滴の安定性から、有機系分散剤を使用することが好ましい。
【0027】
次に、上記懸濁液に、予め重合開始剤を溶解したスチレン系単量体を加え、核となる再生スチレン系樹脂ペレットに含浸させる。
本発明で使用するスチレン系単量体は、スチレン、α−メチルスチレン、及びビニルトルエン等のスチレン誘導体の1種又は2種以上、又はこれらと、メチルメタクリレート、エチルメタクリレート等のメタクリル酸エステル、対応するアクリル酸エステル、アクリロニトリル、メタクリロニトリル等のシアン化ビニル、塩化ビニル等その他の重合可能な単量体との組み合わせ等である。
また、ジビニルベンゼン、ジアリルフタレート等の架橋剤を使用しても差し支えない。
【0028】
重合反応に用いる重合開始剤としては、懸濁重合法に用いられるものであればよく、例えば、t−ブチルパーオキサイド、ベンゾイルパーオキサイド、t−ブチルパーオキシ−2−エチルヘキシルカーボネート、t−ブチルパーベンゾエート等の有機過酸化物、アゾビスイソブチロニトリル等のアゾ化合物の1種又は2種以上を使用することができる。
【0029】
重合開始剤は、溶剤に溶解して加え、再生スチレン系樹脂ペレットに含浸させてもよい。この場合、溶剤としては、エチルベンゼン、トルエン等の芳香族炭化水素、ヘプタン、オクタン等の脂肪族炭化水素等が用いられ、これらを用いる場合は、通常、スチレン系単量体に対して3重量%以下で使用される。
重合開始剤の使用量は、重合開始剤の種類により異なるが、一般的に単量体に対して0.1〜0.5重量%の範囲が好ましい。
【0030】
尚、本発明では、オレイン酸アミド、ステアリン酸アミド等の脂肪酸モノアミド、メチレンビスステアリン酸アミド、エチレンビスステアリン酸アミド等の脂肪酸ビスアミド等を気泡調整剤として、スチレン系単量体又は前記溶剤に溶解して用いてもよい。
【0031】
水性媒体中に分散させた再生スチレン系樹脂ペレットからなる核に、スチレン系単量体を含浸させる方法としては、スチレン系単量体を単独で添加する方法と、水性媒体中にスチレン単量体、分散剤等を添加し微細に分散させた分散液として添加する方法がある。また、これらの方法を組み合わせてもよい。
スチレン系単量体、分散剤等を水性媒体に添加し微細に分散する方法は、通常、撹拌翼を備えた装置を用いて行なわれる。その条件等に制限はないが、より微細に分散する方法としては、ホモミキサーを用いるのが好ましい。このとき、スチレン系単量体を分散した分散液の油滴径が、核の粒子径以下になるまで分散するのが好ましい。油滴径が核の粒子径よりも大きい状態で水性媒体中に添加されると、スチレン系単量体を分散した分散液の油滴に複数の樹脂粒子が取り込まれ、樹脂粒子の粘着、可塑化、合一が生じ、過大粒子が発生しやすいためである。
【0032】
懸濁液に、重合開始剤を溶解したスチレン系単量体を加え、核となる再生スチレン系樹脂ペレットに含浸させた後、引き続きスチレン系単量体を加えて重合を行う。
スチレン系単量体の添加は、分割して行っても連続的に行ってもよい。また、添加速度は、重合装置の容量、形状、重合温度等によって異なり適宜選択される。また、重合温度は、60〜105℃の範囲が好ましい。
【0033】
全体の分子量は、重合開始剤の濃度を調整するか、連鎖移動剤を併用するか、又はこれら両方により調整できる。連鎖移動剤としては、オクチルメルカプタン、ドデシルメルカプタン、α−メチルスチレンダイマー等の従来公知のものが使用できる。
【0034】
続いて、重合中又は重合後の、核となるペレットにスチレン系単量体が重合した樹脂粒子に、発泡剤を含浸させる。
発泡剤の含浸は、発泡剤を容器内に圧入し、通常、再生スチレン系樹脂粒子の軟化点以上の温度に上げ、樹脂粒子中に含浸させる。
発泡剤としては、樹脂粒子を溶かさないか、又は僅かに膨潤させるものが好ましく、具体的にはプロパン、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、ノルマルヘキサン等の脂肪族炭化水素、シクロヘキサン、シクロペンタン等の脂環式炭化水素が用いられる。これらは単独で使用してもよく、2種以上を混合して使用してもよい。
これらの発泡剤は、通常再生スチレン樹脂粒子に対して3〜15重量%使用される。
【0035】
発泡剤の含浸温度は、好ましくは100℃以上であり、より好ましくは110℃以上である。発泡剤の含浸温度が100℃未満では、粒子が球形化し難くなる。また、温度が高すぎると粒子同士が合一し易くなるため、140℃以下が好ましく、130℃以下がより好ましい。
発泡剤の含浸が完了した後、重合系内より排出することによって、再生発泡性スチレン系樹脂粒子を得ることができる。
【0036】
再生発泡性スチレン系樹脂粒子を脱水乾燥した後、必要に応じて表面被覆剤を被覆することができる。かかる被覆剤は、従来公知である発泡性スチレン系樹脂粒子に用いられるものが適用できる。例えば、ジンクステアレート、ステアリン酸トリグリセライド、ステアリン酸モノグリセライド、ひまし硬化油、牛脂硬化油、シリコーン類、静電気防止剤等である。
【0037】
得られる再生発泡性スチレン系樹脂粒子(発泡剤含浸前)に対する再生スチレン系樹脂ペレットの比率は、好ましくは70重量%以下であり、より好ましくは60重量%以下である。70重量%を越えると粒子が球形化し難くなる。また、比率が少なすぎると重合過程で粒子同士が合一し易くなるため、20重量%以上が好ましい。
【0038】
本発明の方法で製造した再生発泡性スチレン系樹脂粒子は、長さ方向に収縮する再生スチレン系樹脂ペレットを重合の核として使用しているにもかかわらず、球形の粒子として得ることができる。
従って、無延伸の再生スチレン系樹脂ペレットを製造するための特殊な方法によらず、一般的な成形方法によって得られる再生ペレットを使用して再生発泡性スチレン系樹脂粒子を製造できる。
【0039】
続いて、本発明の再生発泡成形品について説明する。
本発明の再生発泡成形品は、再生発泡性スチレン系樹脂粒子を発泡成形して製造する。
一般には、再生発泡性スチレン系樹脂粒子を、スチーム等により加熱して所定の嵩密度まで予備発泡し、熟成工程を経た発泡ビーズを成形金型に充填し再度スチーム等で加熱発泡成形して、発泡成形品を製造する。
【0040】
【実施例】
次に実施例により、本発明をさらに詳細に説明する。
尚、再生発泡性スチレン系樹脂粒子は、以下の方法により評価した。
1.ペレット寸法
ノギスにより測定した。
2.ペレット収縮率
200℃に設定した恒温槽にペレットを入れ、10分間加熱後恒温槽から取り出し、加熱前と加熱後の長さ(ペレット延伸方向)の寸法を測定し、以下の計算式により求めた。
ペレット収縮率=(加熱前の寸法−加熱後の寸法)/(加熱前の寸法)×100
【0041】
3.ペレット比率
使用した再生スチレン系樹脂ペレットの重量(W1)と、得られた再生発泡性スチレン系樹脂粒子の重量(W2)から、以下の計算式により求めた。
ペレット比率=W1/W2×100
4.発泡剤含有後の樹脂粒子の形状
再生発泡性スチレン系樹脂粒子の最も長い部分の寸法Aと、最も短い部分の寸法Bを、ノギスで測定し、A/B=0.8〜1.3の場合は球形と判定し、A/Bが0.8未満又は1.3を超える場合は扁平と判定した。
尚、計測した粒子の数は、任意に選択した100個であり、その平均値をとった。
5.成形品の表面平滑率
成形品の表面平滑率は、まず成形品の表面に印刷用インクをローラーで薄く塗り、この表面部分を画像処理装置にかけ、全面積に対する黒色部分の面積を求め、表面平滑率とした。
【0042】
実施例1
[再生スチレン系樹脂ペレットの作製]
発泡スチレン系樹脂成形品を220℃の熱風で収縮させ、見かけ比重0.75、大きさ500mm×400mm×100mm及び重さ15kgの収縮物を得た。この収縮物を10mmのスクリーンをとりつけた粉砕機(株式会社ホーライ製、ZA−560型粉砕機)で粗粉砕した。このとき得られた粗粉砕物の最大長さは、おおよそ10mm、かさ比重0.5であった。
ついで、ヘンシェルミキサー(三井三池化工製、FM10B)にこの粗粉砕物2000g及び平均粒子径が10μmのタルク(林化成株式会社製、ホワイトミクロン#5000)20g、及びエチレンビスステアリルアミド0.6gを入れ、2000rpmで2分間混合した。
【0043】
このタルク及びエチレンビスステアリルアミドで表面被覆された粗粉砕物を、ベント付き2軸押出機(ダイス穴径2mm、(株)池貝製 PCM−30)の材料フィード部に投入し、シリンダー温度230℃、材料フィードモーター回転数8rpm、スクリュー回転数100rpmの条件にてストランド状に押出した。
このストランドを、ペレタイザー回転数400rpmで切断することによって、再生スチレン系樹脂ペレットを作製した。このペレットの延伸方向の長さは、2.5〜3.0mmであり、径は、1.8〜2.0mmであった。また、ペレットを200℃雰囲気下で10分間加熱した後の延伸方向の寸法収縮率は12〜17%であった。
【0044】
[含浸・重合工程]
5Lの耐圧攪拌容器に、上記の再生スチレン系樹脂ペレット1100g、脱イオン水1500g、リン酸三カルシウム12.0g、ドデシルベンゼンスルホン酸ナトリウム0.09gを仕込み、攪拌しながら70℃に昇温した。
次いで、単量体分散容器に脱イオン水350gとポリビニルアルコール0.36gを入れ混合し、これにt−ブチルパーオキサイド3.2gを溶解したスチレン単量体200gを加え、ホモミキサー(特殊機化工業製)を用いて5800rpmで120秒攪拌しスチレン単量体を微細(単量体油滴の平均径10〜100μm)に分散させた。
このスチレン単量体分散液を容器内に添加し、90分保温したのち、90℃に昇温した。その後、スチレン単量体900gを連続的に3時間かけて等速度(3.3g/分)で添加した。
次いで、リン酸三カルシウム2.4g、ドデシルベンゼンスルホン酸ナトリウム0.05gを添加した後、115℃に昇温し、2時間保温した。
【0045】
その後、100℃まで冷却し、発泡剤としてブタン(イソブタン/n−ブタンの重量比=4/6)を160gづつ2回に分けて圧入し、2時間保持した後、120℃に昇温し、8時間保持して発泡剤の含浸を行った。
室温まで冷却した後、発泡剤が含浸されたスチレン系樹脂粒子を取り出し、脱水乾燥した。次いでこの重合体粒子を目開き2.8mm及び1.2mmの篩で分級し、2080gの樹脂粒子を得た。得られた樹脂粒子に対し、ステアリン酸亜鉛1.1g、次いで硬化ひまし油2.2gを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。得られた再生発泡性スチレン系樹脂粒子は球形であった。
【0046】
[再生発泡スチレン系樹脂成形品]
得られた再生発泡性スチレン系樹脂粒子を、発泡スチレン系樹脂用発泡機(日立化成テクノプラント製 HBP−500LW)を用い、スチームで加熱することによって、50ml/gの発泡ビーズに予備発泡した。
その後、約18時間熟成した後、発泡スチレン系樹脂用成型機(ダイセン工業製 VS−300)を用い、成形圧力0.08MPaで成形し、再生発泡スチレン系樹脂成形品(以下、発泡成形品という)を得た。
実施例1及び後述する実施例2並びに比較例1〜4で作製した再生スチレン系樹脂ペレット、再生発泡性スチレン系樹脂粒子及び発泡成形品の評価結果を表1に示す。
【0047】
【表1】
【0048】
実施例2
実施例1において、押出機の材料フィードモーター回転数を1.5rpm、ペレタイザーの回転数を550rpmとした以外は、実施例1と同様な操作を行い、再生スチレン系樹脂ペレットを得た。このペレットの延伸方向の長さは、2.5〜3.0mmであり、径は、0.8〜1.1mmであった。また、ペレットを200℃雰囲気下で10分加熱後の延伸方向の寸法収縮率は33〜39%であった。
この再生スチレン系樹脂ペレットを用い、実施例1と同様な操作を行い、再生発泡性スチレン系樹脂粒子、及び発泡成形品を得た。
【0049】
比較例1
実施例1において、押出機の材料フィードモーター回転数を1.2rpm、ペレタイザーの回転数を700rpmとした以外は、実施例1と同様な操作を行い、再生スチレン系樹脂ペレット得た。このペレットの延伸方向の長さは、2.8〜3.3mmであり、径は、0.6〜0.9mmであった。また、ペレットを200℃雰囲気下で10分加熱後の延伸方向の寸法収縮率は65〜72%であった。
この再生スチレン系樹脂ペレットを用い、実施例1と同様な操作を行い、再生発泡性スチレン系樹脂粒子、及び発泡成形品を得た。
【0050】
比較例2
実施例1において、発泡剤の圧入を90℃で行い、10時間保持して発泡剤の含浸を行った以外は、実施例1と同様な操作を行い、再生発泡性スチレン系樹脂粒子、及び発泡成形品を得た。
【0051】
比較例3
5リットルの耐圧撹拌容器に脱イオン水2000g、実施例1と同様の方法で作製した再生スチレン系樹脂ペレット1760g、リン酸三カルシウム17.6g、ドデシルベンゼンスルホン酸ナトリウム0.04gを仕込み、撹拌しながら75℃に昇温した。
次いで、単量体分散容器に脱イオン水300gとポリビニルアルコール0.1gを入れ混合し、これにt−ブチルパーオキサイド0.1g、ベンゾイルパーオキサイド0.9gを溶解したスチレン単量体300gを加え、ホモミキサー(特殊機化工業製)を用いて5800rpmで120秒撹拌しスチレン単量体を微細(単量体油滴の平均径10〜100μm)に分散させた。このスチレン単量体分散液を容器内に添加し、60分保温したのち、90℃に昇温した。ついで、スチレン単量体140gを連続的に1時間かけて等速度(2.3g/分)で添加した。
次いで、リン酸三カルシウム2.2g、ドデシルベンゼンスルホン酸ナトリウム0.05gを添加した後、115℃に昇温し、2時間保温した。ついで、100℃まで冷却し、発泡剤としてブタン(i/n比=4/6、重量比以下同じ)180gを2回に分けて圧入し、2時間保持した後、120℃に昇温し発泡剤の含浸を行った。
室温まで冷却後、発泡剤が含浸された再生発泡性スチレン系樹脂粒子を取り出し、脱水乾燥した。
次いでこの重合体粒子を目開き2.8mm及び1.2mmの篩で分級し、
1520gの樹脂粒子を得た。得られた樹脂粒子に対し、ステアリン酸亜鉛1.1g、次いで硬化ひまし油2.2gを順次加えて混合し、再生発泡性スチレン系樹脂粒子を得た。
この再生発泡性スチレン系樹脂粒子を用い、実施例1と同様な操作を行い、発泡成形品を得た。
【0052】
比較例4
実施例1において、押出機の材料フィードモーター回転数を8.5rpm、ペレタイザーの回転数を350rpmとした以外は、実施例1と同様な操作を行い、再生スチレン系樹脂ペレット得た。このペレットの延伸方向の長さは、6.5〜7.8mmであり、径は、2.6〜3.4mmであった。また、ペレットを200℃雰囲気下で10分加熱後の延伸方向の寸法収縮率は15〜18%であった。
この再生スチレン系樹脂ペレットを用い、実施例1と同様な操作を行い、再生発泡性スチレン系樹脂粒子、及び発泡成形品を得た。
【0053】
【発明の効果】
本発明によれば、発泡スチレン系樹脂成形品の再利用において、延伸ペレットから、球形の再生発泡性スチレン系樹脂粒子を製造する方法を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to regenerated foamable styrene resin particles, regenerated foam beads, and regenerated foamed styrene resin molded articles obtained by regenerating foamed styrene resin molded articles.
[0002]
[Prior art]
Conventionally, foamed styrene resin molded products have been used once and then incinerated, or they are heat-shrinked and recovered and reused as polystyrene. However, the reuse ratio is insufficient and will be reused in the future. Increasing the utilization rate is a social issue.
[0003]
The technology for recovering foamed styrene resin molded products as contracted lumps has already been completed. In 1999, about 33% of the amount of foamed styrene resin molded products distributed in Japan was recovered as heat contracted lumps. It is mainly used for miscellaneous goods by injection molding and building materials by extrusion molding. Thus, at present, the recycling method of the foamed styrene resin molded product is limited, and its application is urgently expanded.
[0004]
On the other hand, from the definition of recycling, foamable styrene resin particles are foam-molded, and the styrene resin finally used as the foamed styrene-resin molded product is not used for other purposes as polystyrene. It is considered that it is preferable to reuse as expandable styrenic resin particles, but at present, styrene resin recovered from expanded styrene resin molded products is industrially regenerated as expandable styrene resin particles. There are few.
[0005]
As a method for regenerating the expandable styrene resin particles from the shrinkage of the foamed styrene resin molded product, the method of pelletizing the shrinkage with an extruder and impregnating it with a foaming agent is the most technically easy. However, in the most commonly used strand type extruder, strain remains in the stretching direction, and thus the regenerated expandable styrenic resin particles impregnated with the foaming agent contract in the stretching direction, resulting in a flat or oval shape. It becomes a shape. For this reason, when filling the expanded beads with the foamed foam into the mold, the shape is not spherical, so that the filling property is inferior, there are many defects due to insufficient filling, and the appearance of the obtained molded product is inferior. .
[0006]
As a method of regenerating expandable styrene resin particles from shrinkage of expanded styrene resin molded products, etc., pellets obtained by heating and melting a pulverized expanded styrene resin molded product in an extruder are dispersed in water. Then, a method of adding and polymerizing a styrene monomer solution containing a catalyst has been proposed. (For example, see Patent Document 1)
However, this method is effective for relatively clean molded products such as defective products that occur during molding. However, when a molded product that is actually used in the market and is contaminated with foreign matter is used as a raw material, an extruder is used. However, it is necessary to increase the diameter of the die for mass production, and the resulting pellet size increases. When the pellet size is large, the proposed method has a problem of poor filling property to the mold and appearance of the molded product because the particles are difficult to spheroidize and have a flat or oval shape.
[0007]
In addition, as a method for regenerating spherical expandable styrene resin particles from shrinkage of foamed styrene resin molded products, etc., styrene resin particles obtained by non-stretching melting and pulverizing shrinkage of foamed styrene resin molded products Has been proposed in which re-expandable styrene resin particles are produced by dispersing in an aqueous medium containing an organic dispersant and impregnated with a readily volatile foaming agent (see, for example, Patent Document 2).
However, in this method, it is necessary to make the shrinkage of the foamed styrene resin molded product into an unstretched pellet with an extruder or the like, but since an extruder that can produce an unstretched pellet is not common, there is equipment that can be produced. Therefore, the production amount is limited, and the pellet size is larger than the pellets obtained by a general strand type extruder. Therefore, it is necessary to finely pulverize to the desired size. It was disadvantageous in terms of cost.
[0008]
[Patent Document 1]
JP-A-5-98062
[Patent Document 2]
JP-A-6-87973
[0009]
[Problems to be solved by the invention]
Accordingly, the present invention provides spherical regenerated foamable styrene resin particles from regenerated styrene resin pellets (stretched pellets) obtained from a foamed styrene resin molded product using the most widely adopted strand type extruder. A method of manufacturing is provided.
[0010]
[Means for Solving the Problems]
According to the present invention, a regenerated styrene resin pellet having a columnar shape with a length of 5.0 mm or less and a diameter of 3.0 mm or less and a dimensional shrinkage of 50% or less in the length direction is used as a core, and is aqueous. Suspended in a medium, impregnated with a polymerization initiator and a styrene monomer into a regenerated styrene resin pellet, subsequently added with a styrene monomer to perform polymerization, and then foamed at an impregnation temperature of 100 ° C. or higher. Of regenerated expandable styrene resin particles impregnated with an agent, wherein the ratio of regenerated styrene resin pellets to regenerated expandable styrene resin particles is 70% by weight or less A method is provided.
[0011]
According to the present invention, there is provided regenerated expandable styrene resin particles obtained by the method for producing regenerated expandable styrene resin particles.
[0012]
According to the present invention, there is provided a regenerated styrene-based expanded bead obtained by expanding the regenerated expandable resin particles.
[0013]
According to the present invention, there is provided a regenerated expanded styrene resin molded product obtained by foam molding of the above regenerated styrene expanded beads.
[0014]
According to the present invention, a regenerative foaming property comprising a regenerated styrene resin pellet having a columnar shape having a length of 5.0 mm or less and a diameter of 3.0 mm or less and a dimensional shrinkage in the length direction of 50% or less. Nuclei for use in the production of styrenic resin particles are provided.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the method for producing the regenerated expandable styrene resin particles of the present invention and the foam molded product obtained by foam molding thereof will be described in detail.
The method for producing regenerated expandable styrene resin particles of the present invention comprises suspending regenerated styrene resin pellets as a core in an aqueous medium and impregnating the regenerated styrene resin pellets with a polymerization initiator and a styrene monomer. Then, a styrene monomer is added and polymerized, and then impregnated with a foaming agent.
[0016]
The regenerated styrene resin pellets used in the present invention can be produced by extruding a pulverized product obtained by roughly pulverizing a shrinkage or melt of a used expanded styrene resin to an appropriate size as required.
The shrinkage or melt of the used expanded styrene resin is preferably prepared by excluding the used expanded styrene resin molded product previously colored with a dye or the like. If a colored molded product is mixed, the regenerated expandable styrene resin particles and foamed molded product obtained from the colored product are colored, which is not preferable.
[0017]
In addition, used styrene resin shrinkage or melted pulverized product, fatty acid monoamides such as oleic acid amide and stearic acid amide, fatty acid bisamides such as methylene bisstearic acid amide and ethylene bisstearic acid amide, talc, etc. The inorganic substance can be mixed as a bubble regulator. In this case, the pulverized material and the air bubble adjusting agent are mixed in advance and then extruded. Although the quantity of a bubble regulator can be mix | blended suitably, it is 0.01 to 2.0 weight%, for example.
Mixing of the pulverized product and the bubble adjusting agent can be performed by a conventionally known means. For example, a blender such as a ribbon blender, a V blender, a Henschel mixer, or a ready game mixer can be used.
[0018]
Such a pulverized product is extruded using a known extruder, for example, a single-screw extruder, a twin-screw extruder or the like with a strand die attached (strand-type extruder), and a regenerated styrene type Resin pellets can be produced.
Specifically, a used expanded styrene resin shrinkage or melted pulverized product, or a mixture of this and an air conditioner is charged into an extruder and melt kneaded. The melt extruded in the form of a strand from the die at the tip of the extruder is introduced into a pelletizer while being cooled, cut to an appropriate length, and made into a substantially cylindrical regenerated styrenic resin pellet.
[0019]
The length of the regenerated styrene resin pellets in the stretching direction is preferably 5.0 mm or less, more preferably 3.0 mm or less. If the length in the stretching direction exceeds 5.0 mm, the particles are difficult to spheroidize. Moreover, since there is no demand if the regenerated foamable styrene resin particles are too small, the length of the pellet is preferably 0.3 mm or more.
[0020]
The diameter of the pellet is preferably 3.0 mm or less, more preferably 2.0 mm or less. When the diameter of the pellet exceeds 3.0 mm, the particles are difficult to spheroidize. In addition, since there is no demand if the regenerated expandable styrene resin particles are too small, the diameter of the pellet is preferably 0.3 mm or more.
The ratio of the length and diameter of the pellets is preferably 4: 1 to 1: 2, more preferably 2: 1 to 1: 1.
[0021]
The dimensional shrinkage ratio in the stretching direction after heating the pellet in a 200 ° C. atmosphere for 10 minutes is 50% or less, preferably 30% or less. When the dimensional shrinkage rate exceeds 50%, the obtained particles are difficult to spheroidize.
Note that “stretched” means forming while pulling out, for example, having a dimensional shrinkage of 10% or more.
[0022]
The length of the regenerated styrene resin pellet in the stretching direction can be controlled by adjusting the cutting speed, for example, adjusting the rotation speed of the pelletizer.
Moreover, the diameter and dimensional shrinkage ratio of the pellet can be controlled by adjusting the discharge amount and cutting speed (take-off speed) of the extruder.
[0023]
The weight average molecular weight of the obtained regenerated styrene resin pellets is preferably 100,000 to 250,000. If the weight average molecular weight is less than 100,000, sufficient strength tends not to be obtained, and if it exceeds 250,000, the particles tend to be difficult to be spheroidized. More preferably, it is 150,000-230,000.
[0024]
The recycled styrene resin pellets may be blended with the same additive as the above-mentioned used expanded styrene resin shrinkage or crushed melt.
[0025]
The regenerated styrene resin pellets produced as described above are suspended in an aqueous medium to form a suspension. Dispersion in an aqueous medium is usually performed using an apparatus equipped with a stirring blade, and there are no restrictions on the conditions.
[0026]
The regenerated styrene resin pellet is preferably dispersed together with a dispersant. The dispersant used in the present invention is generally only required to be used for suspension polymerization. For example, organic dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and methyl cellulose, magnesium phosphate, tricalcium phosphate, etc. Examples include hardly soluble inorganic salts.
Furthermore, a surfactant can also be used. For example, sodium oleate, sodium dodecylbenzenesulfonate, other anionic surfactants commonly used in suspension polymerization, and nonionic surfactants can be used. .
Among these dispersants, it is preferable to use an organic dispersant from the viewpoint of the stability of the oil droplets of the styrene monomer.
[0027]
Next, a styrene monomer in which a polymerization initiator is dissolved in advance is added to the above suspension, and impregnated into regenerated styrene resin pellets serving as nuclei.
The styrenic monomer used in the present invention is one or more styrene derivatives such as styrene, α-methylstyrene, and vinyltoluene, or these and methacrylic acid esters such as methyl methacrylate and ethyl methacrylate. And combinations with other polymerizable monomers such as vinyl cyanide such as acrylate, acrylonitrile and methacrylonitrile, and vinyl chloride.
In addition, a crosslinking agent such as divinylbenzene or diallyl phthalate may be used.
[0028]
As the polymerization initiator used in the polymerization reaction, any polymerization initiator may be used, for example, t-butyl peroxide, benzoyl peroxide, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxide. One or more organic peroxides such as benzoate and azo compounds such as azobisisobutyronitrile can be used.
[0029]
The polymerization initiator may be added after being dissolved in a solvent and impregnated into regenerated styrene resin pellets. In this case, as the solvent, aromatic hydrocarbons such as ethylbenzene and toluene, aliphatic hydrocarbons such as heptane and octane, etc. are used. When these are used, usually 3% by weight based on the styrene monomer. Used in:
Although the usage-amount of a polymerization initiator changes with kinds of polymerization initiator, generally the range of 0.1 to 0.5 weight% is preferable with respect to a monomer.
[0030]
In the present invention, fatty acid monoamides such as oleic acid amide and stearic acid amide, fatty acid bisamides such as methylene bis stearic acid amide and ethylene bis stearic acid amide, etc. are dissolved in the styrenic monomer or the solvent as a bubble regulator. May be used.
[0031]
As a method of impregnating a styrene monomer into a core composed of regenerated styrene resin pellets dispersed in an aqueous medium, a method of adding a styrene monomer alone, or a styrene monomer in an aqueous medium Alternatively, there is a method of adding as a dispersion finely dispersed by adding a dispersant or the like. Moreover, you may combine these methods.
A method of adding a styrenic monomer, a dispersant, or the like to an aqueous medium to finely disperse is usually performed using an apparatus equipped with a stirring blade. The conditions are not limited, but it is preferable to use a homomixer as a method for finer dispersion. At this time, it is preferable to disperse until the oil droplet diameter of the dispersion liquid in which the styrene monomer is dispersed is equal to or smaller than the particle diameter of the core. When added to an aqueous medium in a state where the oil droplet size is larger than the core particle size, a plurality of resin particles are taken into the oil droplets of the dispersion liquid in which the styrenic monomer is dispersed, and the resin particles are adhered and plasticized. This is because crystallization and coalescence occur and excessive particles are likely to be generated.
[0032]
A styrene monomer in which a polymerization initiator is dissolved is added to the suspension and impregnated in a regenerated styrene resin pellet as a core, and then a styrene monomer is added to perform polymerization.
The addition of the styrenic monomer may be performed separately or continuously. Further, the addition rate varies depending on the capacity, shape, polymerization temperature, etc. of the polymerization apparatus and is appropriately selected. The polymerization temperature is preferably in the range of 60 to 105 ° C.
[0033]
The total molecular weight can be adjusted by adjusting the concentration of the polymerization initiator, using a chain transfer agent together, or both. As the chain transfer agent, conventionally known ones such as octyl mercaptan, dodecyl mercaptan, α-methylstyrene dimer can be used.
[0034]
Subsequently, the foaming agent is impregnated into the resin particles obtained by polymerizing the styrenic monomer in the pellets serving as nuclei during or after the polymerization.
In the impregnation with the foaming agent, the foaming agent is press-fitted into the container, and the temperature is usually raised to a temperature equal to or higher than the softening point of the regenerated styrene resin particles, and the resin particles are impregnated.
As the foaming agent, those that do not dissolve or slightly swell resin particles are preferable. Specifically, aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, cyclohexane, cyclopentane, and the like. An alicyclic hydrocarbon such as is used. These may be used alone or in combination of two or more.
These foaming agents are usually used in an amount of 3 to 15% by weight based on the regenerated styrene resin particles.
[0035]
The impregnation temperature of the foaming agent is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. When the impregnation temperature of the foaming agent is less than 100 ° C., the particles are difficult to spheroidize. Further, when the temperature is too high, the particles are easily united with each other. Therefore, the temperature is preferably 140 ° C or lower, and more preferably 130 ° C or lower.
After the impregnation with the foaming agent is completed, regenerated foamable styrene resin particles can be obtained by discharging from the polymerization system.
[0036]
After the regenerated foaming styrene resin particles are dehydrated and dried, a surface coating agent can be coated as necessary. As this coating agent, those used for conventionally known expandable styrene resin particles can be applied. For example, zinc stearate, stearic acid triglyceride, stearic acid monoglyceride, castor hardened oil, beef tallow hardened oil, silicones, antistatic agent and the like.
[0037]
The ratio of the regenerated styrene resin pellets to the regenerated expandable styrene resin particles (before impregnation with the foaming agent) is preferably 70% by weight or less, more preferably 60% by weight or less. If it exceeds 70% by weight, the particles are difficult to spheroidize. Further, when the ratio is too small, the particles are easily united in the polymerization process, and therefore, 20% by weight or more is preferable.
[0038]
The regenerated expandable styrene resin particles produced by the method of the present invention can be obtained as spherical particles, although regenerated styrene resin pellets shrinking in the length direction are used as the core of polymerization.
Therefore, regenerated expandable styrene resin particles can be produced using regenerated pellets obtained by a general molding method, regardless of a special method for producing unstretched regenerated styrene resin pellets.
[0039]
Next, the recycled foam molded product of the present invention will be described.
The regenerated foam molded article of the present invention is produced by foam molding regenerated foamable styrene resin particles.
In general, regenerated expandable styrene resin particles are heated with steam or the like to be pre-foamed to a predetermined bulk density, filled with foam beads that have undergone an aging process, and again heated and foamed with steam or the like, Manufacture foam molded products.
[0040]
【Example】
Next, the present invention will be described in more detail by way of examples.
The regenerated expandable styrene resin particles were evaluated by the following methods.
1. Pellet dimensions
Measured with calipers.
2. Pellet shrinkage
Pellets were put into a thermostat set at 200 ° C., taken out of the thermostat after heating for 10 minutes, the dimensions of the length before heating and after heating (pellet stretching direction) were measured, and obtained by the following calculation formula.
Pellet shrinkage = (dimension before heating−dimension after heating) / (dimension before heating) × 100
[0041]
3. Pellet ratio
It calculated | required with the following formula from the weight (W1) of the used reproduction | regeneration styrene-type resin pellet and the weight (W2) of the obtained reproduction | regeneration foamable styrene-type resin particle.
Pellet ratio = W1 / W2 x 100
4). Shape of resin particles after containing foaming agent
The length A of the longest part and the dimension B of the shortest part of the regenerated expandable styrenic resin particles are measured with a caliper, and when A / B = 0.8 to 1.3, it is determined to be spherical. When B was less than 0.8 or more than 1.3, it was determined to be flat.
In addition, the number of the measured particle | grains was 100 selected arbitrarily, and took the average value.
5. Surface smoothness of molded products
For the surface smoothness of the molded product, first, the surface of the molded product was thinly coated with printing ink with a roller, and this surface portion was applied to an image processing apparatus, and the area of the black portion relative to the total area was obtained to obtain the surface smoothness.
[0042]
Example 1
[Preparation of recycled styrene resin pellets]
The foamed styrene resin molded product was shrunk with hot air at 220 ° C. to obtain a shrunk product having an apparent specific gravity of 0.75, a size of 500 mm × 400 mm × 100 mm, and a weight of 15 kg. The shrinkage was coarsely pulverized by a pulverizer (product of Horai Co., Ltd., ZA-560 type pulverizer) equipped with a 10 mm screen. The maximum length of the coarsely pulverized product obtained at this time was approximately 10 mm and the bulk specific gravity was 0.5.
Next, 2000 g of this coarsely pulverized product, 20 g of talc (Hayashi Kasei Co., Ltd., White Micron # 5000) having an average particle size of 10 μm, and 0.6 g of ethylene bisstearyl amide are placed in a Henschel mixer (Mitsui Miike Chemicals, FM10B). For 2 minutes at 2000 rpm.
[0043]
The coarsely pulverized material whose surface was coated with talc and ethylenebisstearylamide was charged into the material feed section of a vented twin screw extruder (die hole diameter 2 mm, Ikegai PCM-30), and the cylinder temperature was 230 ° C. The material feed motor was extruded into strands under the conditions of a rotational speed of 8 rpm and a screw rotational speed of 100 rpm.
The strand was cut at a pelletizer rotational speed of 400 rpm to produce a regenerated styrene resin pellet. The length of the pellet in the stretching direction was 2.5 to 3.0 mm, and the diameter was 1.8 to 2.0 mm. Further, the dimensional shrinkage in the stretching direction after heating the pellet for 10 minutes at 200 ° C. was 12 to 17%.
[0044]
[Impregnation / polymerization process]
A 5 L pressure-resistant stirring vessel was charged with 1100 g of the regenerated styrene resin pellets, 1500 g of deionized water, 12.0 g of tricalcium phosphate and 0.09 g of sodium dodecylbenzenesulfonate, and the temperature was raised to 70 ° C. while stirring.
Next, 350 g of deionized water and 0.36 g of polyvinyl alcohol were mixed in a monomer dispersion container, and 200 g of a styrene monomer in which 3.2 g of t-butyl peroxide was dissolved was added thereto. The styrene monomer was finely dispersed (average monomer oil droplet diameter of 10 to 100 μm) by stirring at 5800 rpm for 120 seconds using an industrial product.
This styrene monomer dispersion was added to the container, kept warm for 90 minutes, and then heated to 90 ° C. Thereafter, 900 g of styrene monomer was continuously added at a constant rate (3.3 g / min) over 3 hours.
Subsequently, after adding 2.4 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours.
[0045]
Thereafter, it was cooled to 100 ° C., butane (isobutane / n-butane weight ratio = 4/6) as a blowing agent was injected in 160 g portions in two portions, held for 2 hours, then heated to 120 ° C., The foaming agent was impregnated for 8 hours.
After cooling to room temperature, the styrene resin particles impregnated with the blowing agent were taken out and dehydrated and dried. Next, the polymer particles were classified with a sieve having an opening of 2.8 mm and 1.2 mm to obtain 2080 g of resin particles. To the obtained resin particles, 1.1 g of zinc stearate and then 2.2 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles. The regenerated expandable styrene resin particles obtained were spherical.
[0046]
[Recycled foamed styrene resin molded product]
The obtained regenerated expandable styrene resin particles were pre-expanded into 50 ml / g expanded beads by heating with steam using an expansion machine for expanded styrene resin (HBP-500LW manufactured by Hitachi Chemical Technoplant).
Then, after aging for about 18 hours, it was molded at a molding pressure of 0.08 MPa using a foamed styrene resin molding machine (Daisen Kogyo VS-300), and a recycled foamed styrene resin molded product (hereinafter referred to as a foam molded product). )
Table 1 shows the evaluation results of the regenerated styrene resin pellets, regenerated foamable styrene resin particles, and foamed molded products prepared in Example 1, Example 2 described later, and Comparative Examples 1 to 4.
[0047]
[Table 1]
[0048]
Example 2
In Example 1, the same operation as in Example 1 was performed except that the material feed motor rotation speed of the extruder was 1.5 rpm and the rotation speed of the pelletizer was 550 rpm, to obtain regenerated styrene resin pellets. The length of the pellet in the stretching direction was 2.5 to 3.0 mm, and the diameter was 0.8 to 1.1 mm. Further, the dimensional shrinkage in the stretching direction after heating the pellet for 10 minutes in a 200 ° C. atmosphere was 33 to 39%.
Using the regenerated styrene resin pellets, the same operation as in Example 1 was performed to obtain regenerated expandable styrene resin particles and a foam molded product.
[0049]
Comparative Example 1
In Example 1, the same operation as in Example 1 was performed except that the material feed motor rotation speed of the extruder was 1.2 rpm and the rotation speed of the pelletizer was 700 rpm, to obtain regenerated styrene resin pellets. The length of the pellet in the stretching direction was 2.8 to 3.3 mm, and the diameter was 0.6 to 0.9 mm. In addition, the dimensional shrinkage in the stretching direction after heating the pellet in a 200 ° C. atmosphere for 10 minutes was 65 to 72%.
Using the regenerated styrene resin pellets, the same operation as in Example 1 was performed to obtain regenerated expandable styrene resin particles and a foam molded product.
[0050]
Comparative Example 2
In Example 1, the same procedure as in Example 1 was performed except that the foaming agent was injected at 90 ° C. and maintained for 10 hours to impregnate the foaming agent. A molded product was obtained.
[0051]
Comparative Example 3
A 5 liter pressure-resistant stirring vessel was charged with 2000 g of deionized water, 1760 g of regenerated styrene resin pellets prepared in the same manner as in Example 1, 17.6 g of tricalcium phosphate, and 0.04 g of sodium dodecylbenzenesulfonate, and stirred. The temperature was raised to 75 ° C.
Next, 300 g of deionized water and 0.1 g of polyvinyl alcohol are mixed in a monomer dispersion container, and then 0.1 g of t-butyl peroxide and 300 g of styrene monomer in which 0.9 g of benzoyl peroxide are dissolved are added thereto. Then, the mixture was stirred for 120 seconds at 5800 rpm using a homomixer (manufactured by Koki Kogyo Kogyo Co., Ltd.) to disperse the styrene monomer finely (average diameter of monomer oil droplets of 10 to 100 μm). This styrene monomer dispersion was added to the container, kept warm for 60 minutes, and then heated to 90 ° C. Subsequently, 140 g of styrene monomer was continuously added at an equal rate (2.3 g / min) over 1 hour.
Subsequently, after adding 2.2 g of tricalcium phosphate and 0.05 g of sodium dodecylbenzenesulfonate, the temperature was raised to 115 ° C. and kept for 2 hours. Next, it is cooled to 100 ° C., 180 g of butane (i / n ratio = 4/6, weight ratio is the same) as a foaming agent is injected in two portions, held for 2 hours, then heated to 120 ° C. and foamed The agent was impregnated.
After cooling to room temperature, the regenerated expandable styrene resin particles impregnated with the foaming agent were taken out and dehydrated and dried.
Next, the polymer particles are classified with a sieve having an opening of 2.8 mm and 1.2 mm,
1520 g of resin particles were obtained. To the obtained resin particles, 1.1 g of zinc stearate and then 2.2 g of hardened castor oil were sequentially added and mixed to obtain regenerated expandable styrene resin particles.
Using the regenerated expandable styrene resin particles, the same operation as in Example 1 was performed to obtain a foam molded product.
[0052]
Comparative Example 4
In Example 1, the same operation as in Example 1 was performed except that the material feed motor rotation speed of the extruder was 8.5 rpm and the rotation speed of the pelletizer was 350 rpm, to obtain regenerated styrene resin pellets. The length of this pellet in the stretching direction was 6.5 to 7.8 mm, and the diameter was 2.6 to 3.4 mm. Further, the dimensional shrinkage in the stretching direction after heating the pellet for 10 minutes in a 200 ° C. atmosphere was 15 to 18%.
Using the regenerated styrene resin pellets, the same operation as in Example 1 was performed to obtain regenerated expandable styrene resin particles and a foam molded product.
[0053]
【The invention's effect】
According to the present invention, it is possible to provide a method for producing spherical regenerated foamable styrene resin particles from stretched pellets in the reuse of a foamed styrene resin molded article.
Claims (5)
重合開始剤とスチレン系単量体を、前記再生スチレン系樹脂ペレットに含浸させ、引き続きスチレン系単量体を加えて重合を行い、
その後、含浸温度100℃以上において、発泡剤を含浸させる再生発泡性スチレン系樹脂粒子の製造方法であって、
前記再生発泡性スチレン系樹脂粒子に対する前記再生スチレン系樹脂ペレットの比率が、70重量%以下である再生発泡性スチレン系樹脂粒子の製造方法。Suspended in an aqueous medium with a regenerated styrene resin pellet having a columnar shape having a length of 5.0 mm or less and a diameter of 3.0 mm or less and a dimensional shrinkage in the length direction of 50% or less as a core. Let
The regenerated styrene resin pellets are impregnated with a polymerization initiator and a styrene monomer, and subsequently a styrene monomer is added to perform polymerization.
Thereafter, at the impregnation temperature of 100 ° C. or higher, a method for producing regenerated expandable styrene resin particles impregnated with a foaming agent,
The manufacturing method of the reproduction | regeneration foamable styrene resin particle whose ratio of the said reproduction | regeneration styrene resin pellet with respect to the said reproduction | regeneration foamable styrene resin particle is 70 weight% or less.
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JP2012161275A (en) * | 2011-02-07 | 2012-08-30 | Kitagawa Iron Works Co Ltd | Method for saccharization of lignocellulosic biomass |
WO2024071231A1 (en) * | 2022-09-28 | 2024-04-04 | 積水化成品工業株式会社 | Recycled foamable styrene-based resin particle manufacturing method, recycled foamable styrene-based resin particles, recycled pre-foamed styrene-based resin particles, and recycled styrene-based resin-foamed molded body |
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JP2012161275A (en) * | 2011-02-07 | 2012-08-30 | Kitagawa Iron Works Co Ltd | Method for saccharization of lignocellulosic biomass |
WO2024071231A1 (en) * | 2022-09-28 | 2024-04-04 | 積水化成品工業株式会社 | Recycled foamable styrene-based resin particle manufacturing method, recycled foamable styrene-based resin particles, recycled pre-foamed styrene-based resin particles, and recycled styrene-based resin-foamed molded body |
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