JP3935849B2 - Self-extinguishing styrene resin foam particles and self-extinguishing foam - Google Patents

Self-extinguishing styrene resin foam particles and self-extinguishing foam Download PDF

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JP3935849B2
JP3935849B2 JP2003009974A JP2003009974A JP3935849B2 JP 3935849 B2 JP3935849 B2 JP 3935849B2 JP 2003009974 A JP2003009974 A JP 2003009974A JP 2003009974 A JP2003009974 A JP 2003009974A JP 3935849 B2 JP3935849 B2 JP 3935849B2
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self
extinguishing
flame retardant
particles
styrene
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JP2004217875A (en
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克典 西嶋
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Sekisui Kasei Co Ltd
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Description

【0001】
【発明の属する技術分野】
本発明は、自己消火型スチレン系樹脂発泡粒子及び自己消火型発泡成形体に関する。更に詳しくは、本発明は、スチレン系樹脂粒子に特定の複合難燃剤を含ませることにより、少量の難燃剤で自己消火性に優れ、高発泡性や高断熱性を有し、並びに残留スチレン系モノマーの少ない自己消火型スチレン系樹脂発泡粒子及び自己消火型発泡成形体に関する。本発明の自己消火型発泡成形体は、建物の壁材、床材、天井材等の建築用断熱材、EPS土木工法のような土木用緩衝材、包装材等として好適に使用できる。
【0002】
【従来の技術】
スチレン系樹脂に自己消火性を付与するために、難燃剤又は、難燃剤と難燃助剤とを組合せた複合難燃剤を使用することが知られている。一般的な難燃剤として、テトラブロモシクロオクタン、ヘキサブロモシクロドデカン、テトラブロモビスフェノールAジアリルエーテル、トリス(2,3−ジブロモプロピル)イソシアヌレート等のハロゲン系難燃剤が挙げられ、難燃助剤として、ジクミルパーオキサイド、クメンヒドロパーオキサイドや2,3−ジメチル−2,3−ジフェニルブタン等が挙げられる。
【0003】
具体的には、特開昭60−206845号公報(特許文献1)には、難燃剤としてヘキサブロモシクロドデカンを、難燃助剤として2,3−ジメチル−2,3−ジフェニルブタンを使用した発泡性スチレン系樹脂粒子が記載されている。
また、特開平9−255879号公報(特許文献2)には、難燃剤としてトリス(2,3−ジブロモプロピル)イソシアヌレートを使用したスチレン系難燃性樹脂組成物が記載されている。
更に、特開平11−130898号公報(特許文献3)には、難燃剤としてテトラブロモビスフェノールAジアリルエーテルを、難燃助剤としてジクミルパーオキサイドやクメンヒドロパーオキサイドを使用した発泡ポリスチレン樹脂粒子が記載されている。
【0004】
【特許文献1】
特開昭60−206845号公報
【特許文献2】
特開平9−255879号公報
【特許文献3】
特開平11−130898号公報
【0005】
【発明が解決しようとする課題】
発泡性スチレン系樹脂粒子、それから得られた予備発泡粒子及び発泡成形体に自己消火性を付与するために難燃剤は、それら粒子や成形体中に均一に分散していることが望まれる。
上記観点から見ると、ヘキサブロモシクロドデカンのような比較的高融点で分子量の大きい難燃剤であっても、懸濁重合時に添加するとスチレン系モノマーの重合を阻害するため目的とする分子量の重合物を得ることが難しくなり、樹脂の強度低下を招く。一方、重合後に粒子に含浸させる方法が考えられるが、この方法では上記難燃剤はスチレン系樹脂粒子に比べ融点が高いためにほとんど含浸させることができず、この方法では、自己消火性を付与することが困難となる。従って、押出法のように溶融させた樹脂と難燃剤とを混合して分散させる方法に限定され、その結果、製造工程が複雑となる。
また、トリス(2,3−ジブロモプロピル)イソシアヌレートは、融点が低く含浸法でも発泡性スチレン系樹脂粒子に比較的均一に含浸させることができるが、これ単独では上記テトラブロモシクロオクタン等に比べて難燃性が低く、自己消火性を発揮することができない。
【0006】
そのために難燃助剤としてジクミルパーオキサイドやクメンヒドロパーオキサイドのような有機過酸化物を添加することが行われる。その作用として、燃焼時にラジカルを発生させることで、より少量で効率よく自己消火性を難燃剤に付与していると考えられる。しかし、このような有機過酸化物は、リサイクル時に溶融混練されると、ラジカルが発生し、そのラジカルがスチレン系樹脂を分解して分子量の低下を招くので、リサイクルされた樹脂の強度等の品質を悪化させるという課題がある。
また、従来スチレン系樹脂には、炭化水素系のガスが発泡剤として使用されることが多く、この発泡剤は、発泡後の発泡粒子や成形体に残存し易いので、発泡粒子や成形体の寸法安定性を低下させていた。
そのため、スチレン系樹脂発泡成形体のもつ本来の特性、例えば断熱性、機械的強度を保持し、自己消火性に優れかつ寸法安定性に優れたスチレン系樹脂発泡粒子と発泡成形体を提供することが望まれていた。
【0007】
【課題を解決するための手段】
本発明の発明者は、前記課題を解決するために種々の難燃剤と難燃助剤との組み合わせを検討した結果、下記種類の難燃剤と難燃助剤とを特定の比率で含む複合難燃剤が、リサイクル時にスチレン系樹脂の分子量低下を起こしにくく、スチレン系樹脂のもつ本来の特性(例えば断熱性、機械的強度)を保持し、優れた自己消火性を発揮し、かつスチレン系樹脂への分散方法が限定されないことを意外にも見い出した。更に、発泡剤として無機ガスを使用することで寸法安定性を改善できることを見い出し本発明に至った。
かくして本発明によれば、複合難燃剤を含むスチレン系樹脂を発泡剤としての無機ガスで発泡させて得られ、複合難燃剤が、トリス(2,3−ジブロモプロピル)イソシアヌレートである難燃剤90〜40重量%と、下記一般式
【0008】
【化2】

Figure 0003935849
【0009】
(式中、R1〜R4は、同一又は異なって、メチル又はエチル基である)で表わされる難燃助剤10〜60重量%から構成され、スチレン系樹脂粒子100重量部に対して1〜7重量部含まれる
ことを特徴とする自己消火型スチレン系樹脂発泡粒子が提供される。
更に、本発明によれば、上記自己消火型スチレン系樹脂発泡粒子を型内成形法にて成形して得られた自己消火型発泡成形体が提供される。
【0010】
【発明の実施の形態】
本発明で使用される複合難燃剤は、トリス(2,3−ジブロモプロピル)イソシアヌレート(以下TDICとも称する。融点115℃、分解温度285℃)である難燃剤と、下記一般式
【0011】
【化3】
Figure 0003935849
【0012】
(式中、Rは同一又は異なって、メチル又はエチル基である)で表わされる難燃助剤から構成される。
難燃助剤の具体例としては、2,3−ジメチル−2,3−ジフェニルブタン(ビスクミルと呼ばれることから、以下BCとも称する。融点113℃、分解温度205℃)、3,4−ジメチル−3,4−ジフェニルヘキサン(融点142℃、分解温度230℃)等が挙げられる。
上記難燃剤と難燃助剤は、融点が比較的近いため、それらを混合した複合難燃剤は、融点がほぼ一つのピークを形成する(この温度を融点ピーク温度と称する)。また、複合難燃剤の融点ピーク温度は、融点降下により難燃剤及び難燃助剤単独の融点より低いことを発明者らは見出している。例えば、横軸に複合難燃剤中の難燃助剤BCの割合を、縦軸に複合難燃剤の融点ピーク温度を表す図1に示すように、TDIC70重量%とBC30重量%とから構成される複合難燃剤の場合、示差熱分析(DTA)にて測定した融点ピーク温度は約101℃であり、TDICとBC単独の融点より15℃程度低くなっている。複合難燃剤の融点ピーク温度は、含浸温度又は混練温度をより低くすることができるので好ましい。
なお、融点ピーク温度は、80〜140℃の範囲にあることが好ましい。融点ピーク温度が80℃より低いと、含浸時に樹脂粒子同士の合着や混練時に難燃剤がブリードし、予備発泡時に発泡粒子同士の合着を起こすため好ましくない。一方、140℃を超えると含浸効率や混練時の分散性が劣る場合があるので好ましくない。より好ましい融点ピーク温度は90〜130℃である。
【0013】
本発明において難燃剤と難燃助剤は、90〜40重量%と10〜60重量%割合で使用される。難燃助剤の割合が10重量%未満の場合、自己消火性の発現には複合難燃剤を多量に使用する必要が生じ、その結果リサイクル性が阻害される。また、融点ピーク温度があまり低下せず、含浸温度又は混練温度を高くしなければならない。一方、60重量%を超える場合、難燃剤の割合が減るため、自己消火性が劣ることとなる。また、融点ピーク温度があまり低下せず、含浸温度又は混練温度を高くしなければならない。より好ましい難燃剤と難燃助剤の割合は、90〜60重量%と10〜40重量%である。
なお、本発明において、より好ましい難燃剤と難燃助剤の組み合わせは、TDICとBCの組み合わせである。
複合難燃剤の含有割合は、スチレン系樹脂粒子100重量部に対して、1〜7重量部である。1重量部未満では十分な自己消火性は得られない。一方、7重量部を超える場合、自己消火性効果は飽和し、経済的でない。通常、1〜5重量部で十分である。
【0014】
本発明のスチレン系樹脂は、スチレンの単独重合体でもよく、スチレンと共重合可能な他のモノマー、例えば、α−メチルスチレン、ビニルトルエン、アクリロニトリル、メチルメタクリレート、グリシジルメタクリレート、ブチルアクリレート、メタクリル酸、ジビニルベンゼン、アルキレングリコールジメタクリレート等とスチレンとの共重合体でもよい。なお、本発明では、スチレン及びスチレンと共重合と可能なモノマーもスチレン系モノマーと称している。
更に、本発明におけるスチレン系樹脂は、他樹脂との混合樹脂であってもよい。他樹脂の例としては、ポリエチレン、ポリプロピレン、ポリフェニレンエーテル及びゴム変性スチレン系樹脂等が挙げられる。
また、スチレン系樹脂中には適当な添加剤が含まれていてもよい。添加剤の例としては、高級脂肪酸アマイド、芳香族ビスアマイド、エチレンビスステアリルアマイド、高級脂肪酸、パラフィン、ワックス、動植物硬化油、ジイソブチルアジペート等が挙げられる。この他にも従来からスチレン系樹脂粒子の製造に使用される添加剤、例えば滑剤、可塑剤、気泡調整剤、気泡安定化剤、充填剤、着色剤、酸化防止剤、紫外線吸収剤等を必要に応じて適宜使用してもよい。
これら添加剤は前もってスチレン系樹脂粒子の重合時に添加されるか、難燃剤の含浸又は混練時に樹脂粒子に含ませることができる。
【0015】
また、スチレン系モノマーのスチレン系樹脂に対する含有量は、発泡成形体の品質及び低VOCの観点から500ppm以下とすることが好ましく、更に300ppm以下とすることが好ましい(下限は0ppmである)。スチレン系モノマーを含む揮発性有機溶剤のスチレン系樹脂に対する含有量は、発泡成形体の品質及び低VOCの観点から1000ppm以下とすることが好ましく、更に500ppm以下が好ましい(下限は0ppmである)。
スチレン系樹脂は粒子の形で用いられるが、その粒子の大きさは0.3〜3.0mmであるのが好ましく、更に0.5〜2.0mmであることが好ましい。
自己消火型スチレン系樹脂粒子の製造方法としては、懸濁重合法やシード重合法、押出機でスチレン系樹脂と複合難燃剤とを溶融混練した後、押し出したストランドをペレタイズする方法が挙げられる。この内、生産効率の観点から懸濁重合又はシード重合法が好ましい。懸濁重合又はシード重合法において、複合難燃剤を樹脂粒子に含浸させる方法としては、重合転化率が99.8%以上の段階又は、重合完了後の水性媒体中に添加して含浸させる方法が挙げられる。重合転化率が99.8%以上のときに含浸させることで、所定の分子量のスチレン系樹脂粒子を簡便に得ることができるので好ましい。
重合転化率が99.8%未満の時点で難燃剤が含浸されると、それ以降のスチレン系モノマーの重合が阻害されて、最終的に得られる発泡成形体中にモノマーが多量に残る場合があるので好ましくない。また、該発泡成形体の気泡径が微細化するために熱伝導率が高くなり、断熱性能は低下する場合があるので好ましくない。含浸は、通常、攪拌機を具備した反応器で行われる。
【0016】
含浸に用いられる水性媒体には、含浸時のスチレン系樹脂粒子同士の結合を防止するために、懸濁安定剤を添加することが好ましい。懸濁安定剤としては、従来から一般に使用されている公知のポリビニルアルコール、メチルセルロース、ポリアクリルアミド、ポリビニルピロリドン等の水溶性高分子や、第三リン酸カルシウム、ハイドロキシアパタイト、ピロリン酸マグネシウム等の難水溶性無機塩が挙げられる。難水溶性無機塩を用いる場合には、通常アニオン界面活性剤が併用される。アニオン界面活性剤としては、例えば脂肪酸石鹸、N−アシルアミノ酸又はその塩、アルキルエーテルカルボン酸塩等のカルボン酸塩、アルキルベンゼンスルホン酸塩、アルキルナフタレンスルホン酸塩、ジアルキルスルホコハク酸エステル塩、アルキルスルホ酢酸塩、α−オレフィンスルホン酸塩等のスルホン酸塩;高級アルコール硫酸エステル塩、アルキルエーテル硫酸塩、ポリオキシエチレンアルキルフェニルエーテル硫酸塩等の硫酸エステル塩;アルキルエーテルリン酸エステル塩、アルキルリン酸エステル塩等のリン酸エステル塩等がある。
【0017】
複合難燃剤の添加方法は、例えば、水性媒体中に難燃剤と難燃助剤を別々に又は同時に投入する方法、難燃剤と難燃助剤とをスーパーミキサー等で混合してから粉体状態のままで水性媒体中に投入する方法、攪拌装置を備えた予備分散槽内で均一に分散させた懸濁液を水性媒体に投入する方法が挙げられる。含浸をより円滑に行なうために、水性媒体を加温することが好ましい。具体的には70〜120℃の温度で、1〜6時間加温することが好ましい。
難燃剤及び難燃助剤が含浸されたスチレン系樹脂粒子は反応器から取り出された後、洗浄及び脱水乾燥することで自己消火型スチレン系樹脂粒子となる。
次に、これら自己消火型スチレン系樹脂粒子に、発泡剤である無機ガスを含浸させる。発泡剤の含浸前に、樹脂粒子表面には適当な表面処理がなされていてもよい。表面処理剤の例としては、発泡時の結合防止剤として炭酸カルシウム、タルク、コロイド状シリカ、アルミナ粉末等、帯電防止剤として高級脂肪酸モノグリセライド、ポリエチレングリコール等、この他にも融着促進剤、ハイサイクル剤、離型剤、防蟻剤、防黴剤、防錆剤等が挙げられる。表面処理法は、リボンブレンダー、ナウターミキサー、タンブラーミキサー、レディゲミキサー等を用いて混合する方法が挙げられる。
無機ガスとしては、炭酸ガス、空気、窒素、これらガスの混合ガス等が挙げられる。この内、炭酸ガスを主成分とすることが好ましく、できる限り炭酸ガス単独で用いることが発泡性の点からより好ましい。
【0018】
無機ガスの含浸は上記樹脂粒子を密閉できる圧力容器に入れ、この容器内に無機ガスを圧入して気相加圧下で行われる。無機ガス含浸を行なう温度は樹脂粒子が軟化して結合しない範囲内の温度、すなわち緩和温度とすることが望ましい。緩和温度は、スチレン系樹脂のビカット軟化点よりも少なくとも10℃低い温度を意味する。具体的な温度はスチレン系樹脂の組成と無機ガスの種類によって異なる。ガス含浸量と圧力容器の関係から一般的に言えば含浸温度は低いことが望ましく、40℃以下が好ましい。しかし0℃以下では工業的にエネルギー消費が大きいので好ましくない。工業的に安定して比較的高い倍率に発泡させる含浸温度は0〜40℃がより好ましく、特に好ましくは5〜30℃である。
樹脂粒子に無機ガスを含浸させる適当な圧力は1.5MPa以上が好ましく、より好ましくは2〜5MPaである。
かかる含浸処理により、自己消火型スチレン系樹脂粒子に無機ガスを均一に含浸できる。含浸時間は無機ガスの種類、圧力、樹脂粒子の組成、粒径によって異なるが、少なくとも無機ガスが0.05モル/kg(樹脂粒子)以上含浸されるまで行なうこと好ましく、この含浸は通常1〜10時間の含浸時間で達成できる。
【0019】
このようにして無機ガスが含浸された自己消火型スチレン系樹脂粒子は、次いで発泡に付される。無機ガスを含浸させた発泡性樹脂粒子は圧力容器から取り出した後、直ちにこれを加熱して発泡させる。この際重要なことは樹脂粒子中の無機ガス含有量の下限が0.1モル/kg(樹脂粒子)以上の条件で発泡を行なうことである。すなわち無機ガスを含浸した発泡性樹脂粒子は圧力容器から大気中へ取り出すと発泡剤である無機ガスが徐々に大気へ逸散してその含有量が低下し、上記の下限値未満になると発泡性の低下により目標発泡倍数まで発泡することが困難となる。また上限は2.3モル/kg(樹脂粒子)以下であり、これ以上の量になると発泡性が高過ぎるため均一な発泡倍数の発泡粒子を生産することが困難になる。
従って工業生産上は加圧状態から直接、予熱された発泡機に上記発泡性樹脂粒子を導入し発泡することが好ましい。あるいは除圧して圧力容器から取り出した後、直ちに予熱された発泡機に導入し発泡してもよい。ただし、除圧後に発泡する場合は除圧後30分以内、特に2分以内に発泡させることが好ましい。
【0020】
発泡は公知の方法で行うことが可能であるが、優れた発泡成形体を得る上で、より好ましい発泡方法として下記の方法が採用できる。すなわち、発泡工程において発泡性樹脂粒子は、蒸気導入ラインと排気ラインとを備えた発泡機内に投入される。次いで蒸気導入ラインから蒸気を0.05〜0.5MPaの導入圧力で発泡機内に供給すると共に、排気ラインから蒸気を含む雰囲気ガスを排気し、且つその間、発泡機内の圧力を蒸気の導入圧力より0.005〜0.2MPa低く維持しながら発泡される。発泡に要する時間は加圧蒸気の圧力、温度、樹脂粒子の組成、無機ガスの含有量等によって影響され、通常は10〜150秒、好ましくは20〜90秒である。
【0021】
なお、樹脂発泡粒子の製造に使用できる発泡機の一例を図2に示す。図中、2は撹拌モーター、3は撹拌翼、4は邪魔棒、5は発泡槽上面検出器、6は発泡性粒子輸送器、7は発泡性粒子計量槽、8は発泡性粒子投入器、9は蒸気吹込制御弁、10は蒸気チャンバー、11は凝縮水排出弁、12は排気制御弁、13は発泡粒子排出口、14は発泡粒子一時受器、15は空気輸送設備、16は内圧検出・制御装置、17は蒸気吹込孔、18は蒸気導入圧力計、19は減圧弁、20は蒸気元圧力計を意味する。
こうして得られた発泡粒子は光沢に優れ、発泡粒子をプレスして得られた発泡粒子板が30〜60の表面光沢度を有している。表面光沢度は35〜50であることが特に好ましい。この発泡粒子から得られる成形体は長期に渡って寸法が安定し、表面平滑性に優れ、美麗な外観を実現できる。なお、表面光沢度が30より小さいと、発泡成形体が黒ずんで見え、著しく商品価値が劣ることがある。また、60より大きいと成形体としたときの内部融着が悪く、十分な機械的強度が得られないことがある。表面光沢度の測定法は、実施例の欄に記載する。
【0022】
こうして得られた自己消火型スチレン系樹脂発泡粒子は、通常、これを大気中に放置し熟成させる。発泡粒子の熟成時間は発泡により生じた気泡内が発泡後冷却して減圧になるのを大気中の空気が補い常圧に戻ることを基準として定める。その時間はおよそ4時間程であり、これよりも短時間では発泡粒子の気泡内が減圧となっているため、型内成形時に発泡粒子が収縮を起こし良好な発泡成形体が得られない場合がある。また、本発明で得られた発泡粒子には放置時間の上限は特になく、基材樹脂自体が劣化しなければ発泡後1年を経過した発泡粒子でも何ら問題なく使用できる。
発泡粒子を型内成形するのに適した平均気泡径は50〜500μmであり、好ましくは100〜300μmである。平均気泡径が50μmよりも小さくなると、加熱により発泡体表面が融けて収縮し良好な発泡成形体が得られない場合があるので好ましくない。また、平均気泡径が500μmよりも大きくなると、強度に優れた成形品が得られなくなるので好ましくない。
このようにして得られた自己消火型スチレン系樹脂発泡粒子は公知手法により、いわゆる型内成形に付されて種々の発泡成形体(例えば、建物の壁材、床材、天井材等の建築用断熱材、EPS土木工法のような土木用緩衝材、包装材等)を得る材料として用いられる。
【0023】
【実施例】
以下、本発明を実施例を用いて説明するが、これにより本発明は限定されるものではない。
まず、スチレン系樹脂粒発泡子及び発泡成形体の評価方法を以下に示す。
[重量平均分子量]
重合体の重量平均分子量(Mw)は、GPC(Gel PermeationChromatography)によって、以下の条件で測定した。
測定装置:東ソー社製 高速GPC装置 HLC−8020
カラム:積水ファインケミカル社製 HSG−60S×2本、HSG−40H×1本、HSG−20H×1本
カラム温度:40℃、移動相:THF(テトラヒドロフラン)、
流量:1.0ml/分、注入量:500ml
検出器:東ソー社製 RID−6A
試料の分子量測定:試料の分子量測定に当たっては、該試料の有する分子量分布が、数種の単分散ポリスチレン標準試料により作成された検量線の分子量の対数とカウント数が直線となる範囲内に包含される測定条件を選択した。また、本発明においてポリスチレンの検量線は、重量平均分子量が2.74×103、1.91×104、1.02×105、3.55×105、2.89×106、4.48×106である東ソー社製の6個のポリスチレン標準試料(TSKスタンダードポリスチレン)を用いて作成した。
【0024】
[融着率]
長さ400mm、幅300mm、厚み30mmの板形状を有する発泡成形体の一方の表面に一対の長辺から長辺まで連続する300mm長さの切込みをカッターナイフで深さ約5mmに入れた後、この線に沿って発泡成形体を手で二分割し、その破断面における発泡粒子について、粒子内で破断している粒子の数(a)と粒子同士の界面で破断している粒子の数(b)とを数え、下式
融着率(%)=[(a)/{(a)+(b)}]×100
に代入して得られた値を融着率(%)とした。
【0025】
[燃焼性]
JIS A9511の燃焼試験A法にて燃焼性を測定した。このJIS規格では自己消火時間が3.0秒以内である必要がある。なお、2.0秒以内であればより好ましい。
[重合転化率と残存スチレン量の定量]
重合転化率は以下の式で算出した。
重合転化率(重量%)=100×(A−B)/A
また、残存スチレン量は以下の式で算出した。
残存スチレン量(重量%)=100×B/A
但し、Aは未反応スチレン系単量体を含むスチレン系樹脂粒子の重量(g)であり、Bは上記未反応のスチレン系単量体を含む樹脂粒子中の未反応単量体の重量(g)である。Bは、例えば、ガスクロマトグラフィー(GC)等により定量される。DCによるスチレン系単量体の定量は、スチレン系樹脂粒子をN,N−ジメチルホルムアミドに溶解し、内部標準液(シクロペンタノール)を加えて測定した。
GC:島津製作所社製 GC−14A
カラム:PEG−20M PT25% 60/80(2.5m)
カラム温度:105℃
検出器(FID)温度:220℃
【0026】
[揮発性有機化合物の含有量]
以下に示す三種類の測定法によって得られた値を合計して求める。
(炭素数5以下の炭化水素化合物の測定)
発泡樹脂粒子又は発泡成形体から切り出した所定量の試料を180℃の熱分解炉に入れ、揮発した炭化水素をガスクロマトグラフィーにて測定する。なお、発泡成形体については、実施例にて得られた発泡成形体の長辺及び短辺から100mm、上下面から5mm入った部位から試験片を切り出し測定試料とした。
ガスクロマトグラフィー(GC):島津製作所社製 GC−14B
熱分解炉:島津製作所社製 PYR−1A
カラム:ポラパックQ 80/100(3mmφ×1.5m)
カラム温度:100℃
検出器(FID)温度:120℃
(炭素数6以上の炭化水素であって、ガスクロマトグラムに現われるスチレンのピークまでの炭化水素の測定)
前記と同様に発泡樹脂粒子又は発泡成形体から切り出した所定量の試料をジメチルホルムアミドに溶解し、内部標準液(シクロペンタノール)を加えてGCにより測定する。ただし、特定できないピークについてはトルエンの検出量に換算して定量する。
GC:島津製作所社製 GC−14A
カラム:PEG−20M PT25% 60/80(2.5m)
カラム温度:105℃
検出器(FID)温度:220℃
(ガスクロマトグラムに現われるスチレンの次のピークから炭素数16(n−ヘキサデカン)までの炭化水素の測定)
【0027】
前記と同様に発泡樹脂粒子又は発泡成形体から切り出した所定量の試料をクロロホルムに溶解し、ガスクロマトグラフ質量分析計(GCMS)にて測定する。ただし、試験片を溶解しない溶剤のみの空試験を行い、空試験の検出物質量を差し引く。更に、特定できないピークについてはトルエンの検出量に換算して定量する。
GCMS:島津製作所社製 QP5000
カラム:J&W Scientific社製 DB−1
(1μm×60m 0.25mmφ)
測定条件:カラム温度
(60℃で1分保持した後、10℃/分で300℃まで昇温)
スプリット比:10
キャリアガス:He(1ml/分)
インターフェイス温度:260℃
【0028】
[表面光沢度]
表面光沢度はJIS K7105(プラスチックの光学的特性試験方法)に準拠し、次のように測定した値を意味する。但し、試験片は発泡粒子をプレスした発泡粒子板を作製し用いた。この平滑面に60度の角度で光を当てた時の正反射の割合(%)を表面光沢度とする。具体的には、ステンレス製円筒容器(内径76mm、深さ15mm)に発泡粒子を山盛りにならないように満杯に入れ、この容器の開口部をアルミ箔にて覆い、直径75mmのステンレス製円盤(表面鏡面仕上げ)を用いてプレス機にて15MPaの加圧状態で72時間放置することで、発泡粒子の平滑面を形成する。測定面は円盤側の平滑面を用いる。この平滑面を光沢度測定装置(グロスチェッカ IG−330:株式会社堀場製作所製)を用い、入射角60度−受光角60度(60度計)の光学系により測定することで表面光沢度を得ることができる。但し、測定は暗室で行なう等、外光の影響を受けない条件で行なう。
発泡粒子板の測定はプレス機の加圧状態を開放した後、30秒以内に測定を行なう。また、試験片には発泡粒子間の境界線が現われるが、測定の際にはこの境界線を含んでいても特に問題はない。
光学測定は、1試験片に対し測定面上の重複しない任意の7箇所で行い、最大値と最小値を除いた5点の平均をその試験片の光沢度とする。この一連の測定を発泡粒子1種類について3回行い、3回の平均値をその発泡粒子の光沢度とする。
【0029】
[寸法変化率]
長さ400mm、幅300mm、厚み30mmの板形状を有する発泡成形体を成形金型から取り出し、温度23℃、相対湿度50%の恒温恒湿室(JIS K7100の標準温湿度状態)に24時間放置した後、この発泡成形体の中央部から上下面が平行で正方形状の平板(長さ150mm、巾150mm、厚み30mm)を切り出し、その中央部に縦及び横方向にそれぞれ互いに平行に3本の直線を50mm間隔になるように記入してJIS K6767に従う試験片とする。この試験片を23℃に保った乾燥機の中に水平に置き、720時間後取り出し、再び恒温恒湿室に1時間放置した。寸法測定はJIS K6767に準拠して実施し、寸法変化率は次の式にしたがって求める。
寸法変化率(%)=(L2−L1)×100/L1
(ただし、L1は、型内成形後に23℃、相対湿度50%で24時間放置されたスチレン系樹脂発泡成形体から得られた試験片の寸法、L2は該スチレン系樹脂発泡成形体を23℃で720時間放置した後の試験片の寸法である)
なお、寸法とは、試験片に記入した縦横それぞれ3本の直線の長さの平均値である。
また、上記とは別の試験片を80℃に保った熱風循環式乾燥機の中に水平に置き、168時間加熱試験を行った後に取り出し、再び恒温恒湿室に1時間放置し寸法変化率を求める。この寸法変化率を加熱寸法変化率と称する。
【0030】
[メルトフローレート(MFR)の測定]
MFRの測定は、JIS K7210に基づき下記の条件で行った。
測定装置:東洋精機製作所製 メルトインデクサー
測定温度:200℃
測定荷重:5.0kgf
オリフィス径:2.09mm
【0031】
実施例1
ポリスチレン樹脂粒子は次のように重合したものを用いた。
攪拌機を具備した内容積100リットルの反応器に、脱イオン水36リットル、ピロリン酸マグネシウム75g、ドデシルベンゼンスルホン酸ナトリウム6gを入れた後に、重合開始剤としてベンゾイルパーオキサイド120gとt−ブチルパーオキシベンゾエート29gを溶解したスチレン46kgを反応器に入れ攪拌し、90℃に昇温してから6時間保持した後125℃に昇温し3時間保持して重合を行なった。重合終了時における重合転化率は99.98%であった。その後冷却して内容物を取り出し洗浄及び脱水乾燥した後に篩い機に掛け粒子径0.9〜1.2mmのポリスチレン樹脂粒子を得た。このポリスチレン樹脂粒子の重量平均分子量は280000であった。
【0032】
上記ポリスチレン樹脂粒子2kgと、ドデシルベンゼンスルホン酸ナトリウム0.5gと、ピロリン酸マグネシウム6gと、水2リットル、及びトリス(2,3−ジブロモプロピル)イソシアヌレート30.0g(1.5重量%)と2,3−ジメチル−2,3−ジフェニルブタン6.0g(0.3重量%)を混合した複合難燃剤を配合して、内容積5リットルの密閉容器内で攪拌しながら120℃まで昇温し3時間保持した後に25℃まで冷却し、密閉容器から樹脂粒子を取り出した後、樹脂粒子の洗浄及び脱水乾燥を行い自己消火型ポリスチレン樹脂粒子を得た。
【0033】
また、上記複合難燃剤(BC割合16.7%)の融点をDTAにて測定したところ、融点ピーク温度は一つであり103℃であった。なお、複合難燃剤の融点ピーク温度は、JIS K7121に準拠し、DTA測定を行うことで求めた。
熱分析装置:セイコーインスツルメンツ社製TG/DTA6200R
測定試料質量:10mg
昇温速度:10℃/分
この自己消火型ポリスチレン樹脂粒子1kgに対し、発泡時結合防止剤として炭酸カルシウム微粉末1.5gと、帯電気防止剤としてステアリン酸モノグリセライド0.5gを樹脂粒子表面に均一に付着させた後に圧力容器に入れ密閉し、次いで炭酸ガスを3.0MPaまで圧入し20℃の雰囲気下で6時間保持した。圧力容器内の内圧を抜いた後、直ちに予熱された発泡機内に投入し加圧蒸気(発泡機への導入圧力0.2MPa、発泡機内の圧力0.07MPa)を用いて加熱発泡し自己消火型ポリスチレン樹脂発泡粒子を得た。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。この発泡粒子を成形型内に充填し水蒸気にて加熱発泡成形し、長さ400mm、幅300mm、厚み30mmの板形状を有する自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観、燃焼性の測定結果を表1に示す。
【0034】
(実施例2)
トリス(2,3−ジブロモプロピル)イソシアヌレートを40.0g(2.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを8.0g(0.4重量%)としたこと以外は実施例1と同様にして、自己消火型ポリスチレン樹脂発泡粒子を得た。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり103℃であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0035】
(実施例3)
トリス(2,3−ジブロモプロピル)イソシアヌレートを60.0g(3.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを8.0g(0.4重量%)としたこと以外は実施例1と同様にして、自己消火型ポリスチレン樹脂発泡粒子を得た。また、複合難燃剤(BC割合11.8%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり104℃であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0036】
(実施例4)
2,3−ジメチル−2,3−ジフェニルブタンを3,4−ジメチル−3,4−ジフェニルヘキサン6.0g(0.3重量%)とした以外は実施例1と同様にして、自己消火型ポリスチレン樹脂発泡粒子を得た。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり131℃であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0037】
(実施例5)
実施例1と同じ方法を用いて、自己消火型ポリスチレン樹脂粒子を得た。この自己消火型ポリスチレン樹脂粒子1kgに対し、発泡時の結合防止剤として炭酸カルシウム微粉末1.5gと、帯電防止剤としてステアリン酸モノグリセライド0.5gを樹脂粒子表面に均一に付着させた後に圧力容器に入れて密閉し、次いで炭酸ガスを3.0MPaまで圧入し20℃の雰囲気下で6時間保持した。圧力容器内の内圧を抜いた後、直ちに予熱された発泡機(上記導入ラインと排気弁の開度を電気的に制御しうる排気ラインとを備えた発泡機)内に投入し、0.2MPaの上記を発泡機内に導入した。このときの発泡機内の圧力が0.07MPaになるように、排気ラインを使って過剰供給分の圧力を外部に逃がした。このように上記を発泡機内に連続的に導入しながら加熱発泡させて自己消火型ポリスチレン樹脂発泡粒子を得た。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり103℃であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。この発泡粒子を成形型内に充填し、水蒸気にて加熱発泡成形し自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観、燃焼性の測定結果を表1に示す。
【0038】
(比較例1)
実施例1と同じポリスチレン樹脂粒子1kgに対し、発泡時結合防止剤として炭酸カルシウム微粉末1.5gと、帯電気防止剤としてステアリン酸モノグリセライド0.5gを樹脂粒子表面に均一に付着させた後に圧力容器に入れ密閉し、次いで炭酸ガスを3.0MPaまで圧入し20℃の雰囲気下で6時間保持した。圧力容器の内圧を抜いた後、直ちに予熱された発泡機内に投入し加熱蒸気を用いて加熱発泡しポリスチレン樹脂発泡粒子を得た。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0039】
(比較例2)
トリス(2,3−ジブロモプロピル)イソシアヌレートを60g(3.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを使用しないこと以外は実施例1と全く同様にしてポリスチレン樹脂発泡粒子を得た。また、難燃剤の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり115℃であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0040】
(比較例3)
2,3−ジメチル−2,3−ジフェニルブタンをジクミルパーオキサイド6.0g(0.3重量%)としたこと以外は実施例1と同様にして、ポリスチレン樹脂発泡粒子を得た。しかしながら、発泡の際に投入した樹脂粒子1kgに対し180gの結合が発生した。また、複合難燃剤(DCP割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、測定途中でDCPが分解してしまい測定は不可能であった。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。この発泡粒子を成形型内に充填し水蒸気にて加熱発泡成形し発泡成形体を得た。得られた発泡成形体は融着が30%と悪く、外観は収縮し良好な成形体は得られなかった。この発泡成形体の燃焼性の測定結果を表1に併記する。
【0041】
(比較例4)
トリス(2,3−ジブロモプロピル)イソシアヌレートをテトラブロモシクロオクタン30.0g(1.5重量%)としたこと以外は実施例1と同様にして、ポリスチレン樹脂粒子を得た。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり88℃であった。このポリスチレン樹脂粒子1kgに対し、発泡時結合防止剤として炭酸カルシウム微粉末1.5gと、帯電気防止剤としてステアリン酸モノグリセライド0.5gを樹脂粒子表面に均一に付着させた後に圧力容器に入れ密閉し、次いで炭酸ガスを3.0MPaまで圧入し20℃の雰囲気下で6時間保持した。圧力容器内の内圧を抜いた後、直ちに予熱された発泡機内に投入し加圧蒸気を用いて加熱発泡したところ、発泡機内で発泡粒同士が結合し成形可能な発泡粒子を得られなかった。
【0042】
(比較例5)
トリス(2,3−ジブロモプロピル)イソシアヌレートをテトラブロモシクロオクタン40.0g(2.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを8.0g(0.4重量%)としたこと以外は実施例1と同様にして、ポリスチレン樹脂粒子を得た。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり88℃であった。このポリスチレン樹脂粒子1kgに対し、発泡時結合防止剤として炭酸カルシウム微粉末1.5gと、帯電気防止剤としてステアリン酸モノグリセライド0.5gを樹脂粒子表面に均一に付着させた後に圧力容器に入れ密閉し、次いで炭酸ガスを3.0MPaまで圧入し20℃の雰囲気下で6時間保持した。圧力容器内の内圧を抜いた後、直ちに予熱された発泡機内に投入し加圧蒸気を用いて加熱発泡したところ、発泡機内で発泡粒同士が結合し成形可能な発泡粒子を得られなかった。
【0043】
(比較例6)
トリス(2,3−ジブロモプロピル)イソシアヌレートをヘキサブロモシクロドデカン30.0g(1.5重量%)としたこと以外は実施例1と同様にしてポリスチレン樹脂粒子を得た。しかしながら、この含浸反応に用いた反応液中には難燃剤が残されており、ポリスチレン樹脂粒子に難燃剤がほとんど含浸されていないことを示していた。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は二つであり、BCの融点は106℃、HBCDの融点は190℃であった。次に、実施例1と同様にしてポリスチレン樹脂発泡粒子を得た。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0044】
(比較例7)
トリス(2,3−ジブロモプロピル)イソシアヌレートをヘキサブロモシクロドデカン40.0g(2.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを8.0g(0.4重量%)としたこと以外は実施例1と同様にしてポリスチレン樹脂粒子を得た。しかしながら、この含浸反応に用いた反応液中には難燃剤が残されており、ポリスチレン樹脂粒子に難燃剤がほとんど含浸されていないことを示していた。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は二つであり、BCの融点は105℃、HBCDの融点は190℃であった。また、実施例1と同様にしてポリスチレン樹脂発泡粒子を得た。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0045】
(比較例8)
トリス(2,3−ジブロモプロピル)イソシアヌレートをヘキサブロモシクロドデカン60.0g(3.0重量%)とし、2,3−ジメチル−2,3−ジフェニルブタンを12.0g(0.6重量%)としたこと以外は実施例1と同様にしてポリスチレン樹脂粒子を得た。しかしながら、この含浸反応に用いた反応液中には難燃剤が残されており、ポリスチレン樹脂粒子に難燃剤がほとんど含浸されていないことを示していた。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は二つであり、BCの融点は106℃、HBCDの融点は190℃であった。また、実施例1と同様にしてポリスチレン樹脂発泡粒子を得た。得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径、嵩発泡倍率、スチレン系モノマーの含有量及び揮発性有機化合物の含有量を表1に示す。更にこの発泡粒子を実施例1と同様にして発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表1に示す。
【0046】
【表1】
Figure 0003935849
【0047】
表1から実施例1〜5の発泡粒子は、発泡時の結合が少なく、取扱いが良好であった。更に、この発泡粒子から得られた発泡成形体は、融着率及び外観共に良好であり、加えて燃焼試験も3秒以下と優れた自己消火性を示した。
比較例1の発泡粒子及び発泡成形体は、発泡時結合量は少なく、また融着率及び外観は良好であるが、難燃剤及び難燃助剤を含まないため自己消火性が極めて劣っていた。
比較例2の発泡粒子は、発泡時結合量が多く、難燃助剤を含まないため自己消火性が劣っていた。
比較例3の発泡粒子及び発泡成形体は、発泡時の結合が比較例2よりも多く、得られた発泡成形体の融着率は悪く、外観は表面が融け、成形品全体が収縮して外観不良品となった。
比較例4及び5では、発泡時に発泡粒子全体が結合し、成形可能な発泡粒子が得られなかった。
比較例6〜8の発泡粒子及び発泡成形体は、発泡時結合量、融着率及び外観は良好であったが、難燃剤を実質的に含まないため自己消火性が極めて劣っていた。
実施例1〜5の光沢度と寸法変化率の測定結果を表2に示す。
【0048】
【表2】
Figure 0003935849
【0049】
表2から、実施例1〜5の発泡成形体の中でも、光沢度の高い実施例5の発泡成形体は特に寸法変化率が極めて小さく、寸法安定性に優れた成形体であった。
【0050】
(実施例6)
この実施例は、懸濁重合によりスチレン系樹脂の形成後、懸濁液中に難燃剤及び難燃助剤を添加した例である。
攪拌機を具備した内容積100リットルの反応器に、脱イオン水30リットル、ピロリン酸マグネシウム100g、ドデシルベンゼンスルホン酸ナトリウム15gを入れ、粒子径が0.63〜0.71mmで重量平均分子量が280000のポリスチレン樹脂粒子(スチレンをピロリン酸マグネシウム、ドデシルベンゼンスルホン酸ナトリウムを使用した水性媒体中で、通常の懸濁重合を行なって得たもの)11kgを加えて攪拌し懸濁させた。
【0051】
次いで、あらかじめ用意した脱イオン水6リットル、ドデシルベンゼンスルホン酸ナトリウム2g、ピロリン酸マグネシウム10gの懸濁液に、ベンゾイルパーオキサイド90g、t−ブチルパーオキシベンゾエート8g溶解したスチレン5kgを加え、ホモミキサーで攪拌して懸濁液とし、これを70℃に保持した反応器に添加した。その後ポリスチレン粒子中にスチレンと重合開始剤が十分に吸収されるように、1時間保持した後に、スチレンを連続的に10kg/時の速度で3時間供給しながら、スチレン供給終了時に105℃になるように反応器を昇温した後に、引き続き120℃に昇温し2時間保持した。重合終了時の重合転化率は99.98%であった。
【0052】
次いで90℃まで冷却し、あらかじめ用意した脱イオン水2リットル、ドデシルベンゼンスルホン酸ナトリウム2g及び、トリス(2、3−ジブロモプロピル)イソシアヌレート690gと2,3−ジメチル−2,3−ジフェニルブタン138gとからなる複合難燃剤の懸濁液を反応器に圧入し120℃に昇温し3時間保持した。また、複合難燃剤(BC割合16.7%)の融点をDTAにて実施例1と同様に測定したところ、融点ピーク温度は一つであり103℃であった。その後、常温まで冷却して内容物を取り出し洗浄及び脱水乾燥して、粒子径が0.9〜1.2mmの自己消火型ポリスチレン樹脂粒子を得た。この樹脂粒子の重量平均分子量は300000であった。この自己消火型ポリスチレン樹脂粒子から実施例1と同様にして自己消火型ポリスチレン樹脂発泡粒子を得た。
得られた発泡粒子を常温常圧下で1日放置し乾燥した後の平均気泡径と嵩発泡倍率を表3に示す。更にこの発泡粒子を実施例1と同様にして自己消火型発泡成形体を得た。得られた発泡成形体の融着、外観及び燃焼性の測定結果を表3に示す。
【0053】
【表3】
Figure 0003935849
【0054】
表3から実施例6の発泡粒子は、難燃剤及び難燃助剤を重合後の懸濁液に添加して得られたスチレン系樹脂粒子から得られていても、発泡時の結合が少なく、取扱いが良好であった。更にこの発泡粒子から得られた発泡成形体は、融着率及び外観共に良好であり、加えて燃焼試験も3秒以下と優れた自己消火性を示した。
【0055】
(実施例7)
この実施例は、上記実施例及び比較例の発泡成形体のリサイクル性を評価する例である。
実施例1と2及び比較例1、3と4で得られたポリスチレン樹脂粒子のメルトフローレート(MFR)を測定した。また、MFR測定前後の樹脂粒子の重量平均分子量も測定した。MFR及び重量平均分子量を表4に示す。
【0056】
【表4】
Figure 0003935849
【0057】
まず、押出機で溶融混練し、ストランド化することでリサイクルが可能なポリスチレン樹脂のMFRは、20g/10分以下、好ましくは15g/10分以下、特に難燃剤未添加の場合のMFRに近いことが好ましい。この観点から表4を見ると、実施例1と2の樹脂粒子はいずれも15g/10分以下であり、十分リサイクル可能である。これに対して、比較例3と4の樹脂粒子は、MFRが測定限界の200g/10分を超えており、リサイクル困難である。
更に、重量平均分子量は熱処理(MFR測定処理)の前後において、できるだけ変化しないことがリサイクルの観点から望まれる。大きく低下すると、押出機で溶融混練した後にストランドとして押し出せない又はストランドの切断が頻繁に起こり、リサイクルが困難である。この観点から表4を見ると、実施例1と2の樹脂粒子は、難燃剤未添加の場合に比べて重量平均分子量が低下は少なく、十分リサイクル可能である。これに対して、比較例3と4の樹脂粒子は、重量平均分子量が大きく低下しており、リサイクルしても強度低下が著しく再利用できない。
【0058】
【発明の効果】
本発明によれば、生産効率が良く、少量の難燃剤量で自己消火性に優れたスチレン系樹脂発泡成形体が得られる。この発泡成形体は発泡成形体中の残存スチレンモノマー分が少なく、発泡剤も無機ガスであるため低VOC材料としての性質を有し、建築用断熱材やEPS土木工法の用途に好適である。
また、押出機で溶融混練することでリサイクルしても分子量が大きく低下することなく、一般のスチレン系樹脂発泡成形体と共にリサイクル可能な、環境適合性に優れた自己消火型スチレン系樹脂発泡成形体が得られる。
【図面の簡単な説明】
【図1】複合難燃剤の融点を示すグラフである。
【図2】樹脂発泡粒子の製造に使用できる発泡機の一例を示す概略図である。
【符号の説明】
2 撹拌モーター
3 撹拌翼
4 邪魔棒
5 発泡槽上面検出器
6 発泡性粒子輸送器
7 発泡性粒子計量槽
8 発泡性粒子投入器
9 蒸気吹込制御弁
10 蒸気チャンバー
11 凝縮水排出弁
12 排気制御弁
13 発泡粒子排出口
14 発泡粒子一時受器
15 空気輸送設備
16 内圧検出・制御装置
17 蒸気吹込孔
18 蒸気導入圧力計
19 減圧弁
20 蒸気元圧力計[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a self-extinguishing styrene resin foamed particle and a self-extinguishing foam molded article. More specifically, the present invention includes a specific composite flame retardant in the styrene resin particles, so that it has excellent self-extinguishing properties with a small amount of flame retardant, has high foaming properties and high heat insulation properties, and residual styrene type. The present invention relates to a self-extinguishing styrene-based resin foam particle and a self-extinguishing foam-molded product with less monomer. The self-extinguishing type foamed molding of the present invention can be suitably used as a building heat insulating material such as a building wall material, a floor material, a ceiling material, a civil engineering buffer material such as an EPS civil engineering method, and a packaging material.
[0002]
[Prior art]
In order to impart self-extinguishing properties to styrene-based resins, it is known to use a flame retardant or a composite flame retardant in which a flame retardant and a flame retardant aid are combined. Common flame retardants include halogen-based flame retardants such as tetrabromocyclooctane, hexabromocyclododecane, tetrabromobisphenol A diallyl ether, tris (2,3-dibromopropyl) isocyanurate, and flame retardant aids , Dicumyl peroxide, cumene hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane, and the like.
[0003]
Specifically, JP-A-60-206845 (Patent Document 1) uses hexabromocyclododecane as a flame retardant and 2,3-dimethyl-2,3-diphenylbutane as a flame retardant aid. Expandable styrenic resin particles are described.
JP-A-9-255879 (Patent Document 2) describes a styrene-based flame retardant resin composition using tris (2,3-dibromopropyl) isocyanurate as a flame retardant.
Further, JP-A-11-130898 (Patent Document 3) discloses expanded polystyrene resin particles using tetrabromobisphenol A diallyl ether as a flame retardant and dicumyl peroxide or cumene hydroperoxide as a flame retardant aid. Are listed.
[0004]
[Patent Document 1]
JP 60-206845 A
[Patent Document 2]
JP-A-9-255879
[Patent Document 3]
JP-A-11-130898
[0005]
[Problems to be solved by the invention]
In order to impart self-extinguishing properties to the expandable styrenic resin particles, the pre-expanded particles obtained therefrom, and the foamed molded product, it is desirable that the flame retardant is uniformly dispersed in the particles and the molded product.
From the above viewpoint, even if a flame retardant having a relatively high melting point and a large molecular weight such as hexabromocyclododecane is added during suspension polymerization, it inhibits the polymerization of the styrenic monomer, and thus a polymer having a target molecular weight. It becomes difficult to obtain the strength of the resin. On the other hand, a method of impregnating the particles after polymerization is conceivable. However, in this method, the flame retardant can hardly be impregnated because the melting point is higher than that of the styrene resin particles, and this method provides self-extinguishing properties. It becomes difficult. Therefore, it is limited to the method of mixing and dispersing the melted resin and the flame retardant as in the extrusion method, and as a result, the manufacturing process becomes complicated.
Tris (2,3-dibromopropyl) isocyanurate has a low melting point and can be impregnated into the expandable styrene resin particles relatively uniformly even by the impregnation method. It is low in flame retardancy and cannot exhibit self-extinguishing properties.
[0006]
For this purpose, an organic peroxide such as dicumyl peroxide or cumene hydroperoxide is added as a flame retardant aid. As an effect, it is considered that a self-extinguishing property is efficiently imparted to the flame retardant with a smaller amount by generating radicals during combustion. However, when such organic peroxides are melt-kneaded at the time of recycling, radicals are generated and the radicals decompose the styrenic resin, resulting in a decrease in molecular weight. There is a problem of making it worse.
In addition, in the conventional styrenic resin, a hydrocarbon-based gas is often used as a foaming agent, and this foaming agent tends to remain in the foamed particles and molded product after foaming. Dimensional stability was reduced.
Therefore, to provide a styrene resin foamed particle and a foamed molded product that retain the original characteristics of the styrene resin foamed molded product, such as heat insulation and mechanical strength, and have excellent self-extinguishing properties and excellent dimensional stability. Was desired.
[0007]
[Means for Solving the Problems]
As a result of studying combinations of various flame retardants and flame retardant aids in order to solve the above problems, the inventor of the present invention has found that composite flames containing the following types of flame retardants and flame retardant aids in specific ratios. The flame retardant is unlikely to cause a decrease in the molecular weight of the styrene resin during recycling, retains the original characteristics of the styrene resin (for example, heat insulation and mechanical strength), exhibits excellent self-extinguishing properties, and provides a styrene resin. Surprisingly, it was found that the dispersion method is not limited. Furthermore, the present inventors have found that dimensional stability can be improved by using an inorganic gas as a foaming agent, and have reached the present invention.
Thus, according to the present invention, the flame retardant 90 is obtained by foaming a styrene resin containing a composite flame retardant with an inorganic gas as a foaming agent, and the composite flame retardant is tris (2,3-dibromopropyl) isocyanurate. ~ 40 wt% and the following general formula
[0008]
[Chemical 2]
Figure 0003935849
[0009]
(Wherein R1 to R4 are the same or different and are methyl or ethyl groups) and are composed of 10 to 60% by weight of a flame retardant aid represented by 1 to 7 with respect to 100 parts by weight of styrene resin particles. Part by weight included
A self-extinguishing styrene resin expanded particle is provided.
Furthermore, according to the present invention, there is provided a self-extinguishing type foamed molding obtained by molding the above self-extinguishing type styrene resin foamed particles by an in-mold molding method.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The composite flame retardant used in the present invention is a flame retardant which is tris (2,3-dibromopropyl) isocyanurate (hereinafter also referred to as TDIC, melting point 115 ° C., decomposition temperature 285 ° C.), and the following general formula:
[0011]
[Chemical 3]
Figure 0003935849
[0012]
(Wherein R is the same or different and is a methyl or ethyl group).
Specific examples of the flame retardant aid include 2,3-dimethyl-2,3-diphenylbutane (hereinafter referred to as BC because it is called biscumyl, melting point 113 ° C., decomposition temperature 205 ° C.), 3,4-dimethyl- 3,4-diphenylhexane (melting point 142 ° C., decomposition temperature 230 ° C.) and the like.
Since the flame retardant and the flame retardant aid have a relatively close melting point, the composite flame retardant mixed with them forms a peak having almost one melting point (this temperature is referred to as a melting point peak temperature). Further, the inventors have found that the melting point peak temperature of the composite flame retardant is lower than the melting point of the flame retardant and the flame retardant auxiliary alone due to the melting point drop. For example, the horizontal axis represents the ratio of the flame retardant auxiliary BC in the composite flame retardant, and the vertical axis represents the melting point peak temperature of the composite flame retardant. As shown in FIG. 1, it is composed of 70% by weight of TDIC and 30% by weight of BC. In the case of a composite flame retardant, the melting point peak temperature measured by differential thermal analysis (DTA) is about 101 ° C., which is about 15 ° C. lower than the melting points of TDIC and BC alone. The melting point peak temperature of the composite flame retardant is preferable because the impregnation temperature or the kneading temperature can be further lowered.
In addition, it is preferable that melting | fusing point peak temperature exists in the range of 80-140 degreeC. When the melting point peak temperature is lower than 80 ° C., the flame retardant bleeds during resin impregnation or kneading at the time of impregnation, and the foam particles adjoin at the time of preliminary foaming. On the other hand, if it exceeds 140 ° C., the impregnation efficiency and the dispersibility during kneading may be inferior. A more preferable melting point peak temperature is 90 to 130 ° C.
[0013]
In the present invention, the flame retardant and the flame retardant aid are used in a proportion of 90 to 40% by weight and 10 to 60% by weight. When the ratio of the flame retardant aid is less than 10% by weight, it is necessary to use a large amount of the composite flame retardant for the self-extinguishing property, and as a result, the recyclability is hindered. In addition, the melting point peak temperature does not decrease so much and the impregnation temperature or kneading temperature must be increased. On the other hand, when it exceeds 60% by weight, the ratio of the flame retardant is reduced, so that the self-extinguishing property is inferior. In addition, the melting point peak temperature does not decrease so much and the impregnation temperature or kneading temperature must be increased. The ratio of a more preferable flame retardant and a flame retardant adjuvant is 90 to 60 weight% and 10 to 40 weight%.
In the present invention, a more preferable combination of the flame retardant and the flame retardant aid is a combination of TDIC and BC.
The content rate of a composite flame retardant is 1-7 weight part with respect to 100 weight part of styrene resin particles. If it is less than 1 part by weight, sufficient self-extinguishing properties cannot be obtained. On the other hand, when it exceeds 7 parts by weight, the self-extinguishing effect is saturated and is not economical. Usually 1 to 5 parts by weight is sufficient.
[0014]
The styrene resin of the present invention may be a homopolymer of styrene, and other monomers copolymerizable with styrene, such as α-methylstyrene, vinyltoluene, acrylonitrile, methyl methacrylate, glycidyl methacrylate, butyl acrylate, methacrylic acid, A copolymer of styrene with divinylbenzene, alkylene glycol dimethacrylate, or the like may be used. In the present invention, styrene and monomers capable of copolymerization with styrene are also referred to as styrene monomers.
Furthermore, the styrenic resin in the present invention may be a mixed resin with other resins. Examples of other resins include polyethylene, polypropylene, polyphenylene ether, rubber-modified styrene resin, and the like.
The styrene resin may contain an appropriate additive. Examples of additives include higher fatty acid amides, aromatic bisamides, ethylene bisstearyl amides, higher fatty acids, paraffins, waxes, hardened animal and vegetable oils, diisobutyl adipate, and the like. In addition to these, additives conventionally used for the production of styrene resin particles, such as lubricants, plasticizers, bubble regulators, bubble stabilizers, fillers, colorants, antioxidants, UV absorbers, etc. are necessary. You may use suitably according to.
These additives may be added in advance during the polymerization of the styrene resin particles, or may be included in the resin particles during the impregnation or kneading of the flame retardant.
[0015]
In addition, the content of the styrene monomer with respect to the styrene resin is preferably 500 ppm or less, and more preferably 300 ppm or less (lower limit is 0 ppm) from the viewpoint of the quality of the foamed molded product and low VOC. The content of the volatile organic solvent containing the styrene monomer with respect to the styrene resin is preferably 1000 ppm or less, more preferably 500 ppm or less (lower limit is 0 ppm) from the viewpoint of the quality of the foamed molded product and low VOC.
The styrene resin is used in the form of particles, and the size of the particles is preferably 0.3 to 3.0 mm, and more preferably 0.5 to 2.0 mm.
Examples of the method for producing self-extinguishing styrene resin particles include a suspension polymerization method, a seed polymerization method, and a method of melt-kneading a styrene resin and a composite flame retardant with an extruder and then pelletizing the extruded strand. Of these, suspension polymerization or seed polymerization is preferred from the viewpoint of production efficiency. In the suspension polymerization or seed polymerization method, as a method of impregnating the resin particles with the composite flame retardant, a method in which the polymerization conversion rate is 99.8% or more, or a method of adding and impregnating into the aqueous medium after the polymerization is completed. Can be mentioned. It is preferable to impregnate when the polymerization conversion rate is 99.8% or more because styrene resin particles having a predetermined molecular weight can be easily obtained.
If the flame retardant is impregnated when the polymerization conversion rate is less than 99.8%, the subsequent polymerization of the styrenic monomer is inhibited, and a large amount of monomer may remain in the finally obtained foamed molded article. This is not preferable. Moreover, since the bubble diameter of the foamed molded article is made finer, the thermal conductivity is increased, and the heat insulation performance may be deteriorated. Impregnation is usually performed in a reactor equipped with a stirrer.
[0016]
It is preferable to add a suspension stabilizer to the aqueous medium used for impregnation in order to prevent bonding of styrene resin particles during impregnation. Suspension stabilizers include conventionally known water-soluble polymers such as polyvinyl alcohol, methylcellulose, polyacrylamide, and polyvinylpyrrolidone, and poorly water-soluble inorganic materials such as tricalcium phosphate, hydroxyapatite, and magnesium pyrophosphate. Salt. When using a hardly water-soluble inorganic salt, an anionic surfactant is usually used in combination. Examples of anionic surfactants include fatty acid soaps, N-acyl amino acids or salts thereof, carboxylates such as alkyl ether carboxylates, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinate esters, alkyl sulfoacetic acids. Salts, sulfonates such as α-olefin sulfonates; sulfates such as higher alcohol sulfates, alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates; alkyl ether phosphates, alkyl phosphates There are phosphate ester salts such as salts.
[0017]
The method of adding the composite flame retardant is, for example, a method in which the flame retardant and the flame retardant aid are separately or simultaneously added to the aqueous medium, and the powder state after mixing the flame retardant and the flame retardant aid with a super mixer or the like. Examples thereof include a method of charging into an aqueous medium as it is, and a method of charging a suspension dispersed uniformly in a pre-dispersion tank equipped with a stirrer into the aqueous medium. In order to perform the impregnation more smoothly, it is preferable to warm the aqueous medium. Specifically, it is preferable to heat at a temperature of 70 to 120 ° C. for 1 to 6 hours.
The styrene resin particles impregnated with the flame retardant and the flame retardant assistant are taken out of the reactor, and then washed and dehydrated to form self-extinguishing styrene resin particles.
Next, these self-extinguishing styrene resin particles are impregnated with an inorganic gas which is a foaming agent. Prior to impregnation with the foaming agent, the surface of the resin particles may be subjected to an appropriate surface treatment. Examples of surface treatment agents include calcium carbonate, talc, colloidal silica, alumina powder, etc. as anti-binding agents during foaming, higher fatty acid monoglycerides, polyethylene glycol, etc. as antistatic agents, other fusion accelerators, high Cycle agents, mold release agents, antproofing agents, antifungal agents, rustproofing agents, and the like. Examples of the surface treatment method include a method of mixing using a ribbon blender, a Nauter mixer, a tumbler mixer, a Redige mixer and the like.
Examples of the inorganic gas include carbon dioxide gas, air, nitrogen, a mixed gas of these gases, and the like. Of these, carbon dioxide gas is preferred as the main component, and carbon dioxide gas alone is preferably used as much as possible from the viewpoint of foamability.
[0018]
The impregnation with the inorganic gas is performed under a gas phase pressure by placing the resin particles in a pressure vessel capable of sealing and injecting the inorganic gas into the vessel. The temperature at which the inorganic gas is impregnated is desirably a temperature within a range where the resin particles are not softened and bonded, that is, a relaxation temperature. The relaxation temperature means a temperature that is at least 10 ° C. lower than the Vicat softening point of the styrene resin. The specific temperature varies depending on the composition of the styrenic resin and the type of inorganic gas. Generally speaking, it is desirable that the impregnation temperature is low from the relationship between the amount of gas impregnation and the pressure vessel, and 40 ° C. or less is preferable. However, if the temperature is 0 ° C. or lower, energy consumption is industrially large, which is not preferable. The impregnation temperature for industrially stable foaming at a relatively high magnification is more preferably from 0 to 40 ° C, particularly preferably from 5 to 30 ° C.
The suitable pressure for impregnating the resin particles with the inorganic gas is preferably 1.5 MPa or more, more preferably 2 to 5 MPa.
By such impregnation treatment, the self-extinguishing styrene resin particles can be uniformly impregnated with inorganic gas. The impregnation time varies depending on the kind of inorganic gas, pressure, composition of resin particles, and particle diameter, but is preferably carried out until at least 0.05 mol / kg (resin particles) of the inorganic gas is impregnated. It can be achieved with an impregnation time of 10 hours.
[0019]
The self-extinguishing styrene resin particles impregnated with the inorganic gas in this way are then subjected to foaming. The expandable resin particles impregnated with the inorganic gas are taken out of the pressure vessel and immediately heated to be foamed. In this case, it is important to perform foaming under the condition that the lower limit of the inorganic gas content in the resin particles is 0.1 mol / kg (resin particles) or more. That is, when the expandable resin particles impregnated with the inorganic gas are taken out from the pressure vessel to the atmosphere, the inorganic gas as the foaming agent gradually dissipates into the atmosphere and its content decreases, and when the content becomes less than the above lower limit value, the expandability It becomes difficult to foam up to the target expansion ratio due to the decrease in. Further, the upper limit is 2.3 mol / kg (resin particles) or less, and if it exceeds this amount, the foamability is too high, and it becomes difficult to produce expanded particles having a uniform expansion ratio.
Therefore, in industrial production, it is preferable to introduce the foamable resin particles into a preheated foaming machine directly from a pressurized state for foaming. Alternatively, the pressure may be removed and taken out from the pressure vessel, and then introduced into a preheated foaming machine and foamed. However, when foaming is performed after decompression, foaming is preferably performed within 30 minutes, particularly within 2 minutes after decompression.
[0020]
Foaming can be performed by a known method, but the following method can be adopted as a more preferable foaming method for obtaining an excellent foamed molded article. That is, in the foaming process, the expandable resin particles are put into a foaming machine equipped with a steam introduction line and an exhaust line. Next, steam is supplied from the steam introduction line into the foaming machine at an introduction pressure of 0.05 to 0.5 MPa, and atmospheric gas containing steam is exhausted from the exhaust line, and during that time, the pressure in the foaming machine is determined from the steam introduction pressure. Foaming is performed while maintaining a low pressure of 0.005 to 0.2 MPa. The time required for foaming is affected by the pressure of pressurized steam, temperature, resin particle composition, inorganic gas content, etc., and is usually 10 to 150 seconds, preferably 20 to 90 seconds.
[0021]
An example of a foaming machine that can be used for the production of resin foam particles is shown in FIG. In the figure, 2 is a stirring motor, 3 is a stirring blade, 4 is a baffle bar, 5 is a foam tank top detector, 6 is a foam particle transporter, 7 is a foam particle metering tank, 8 is a foam particle feeder, 9 is a steam injection control valve, 10 is a steam chamber, 11 is a condensed water discharge valve, 12 is an exhaust control valve, 13 is a foam particle discharge port, 14 is a foam particle temporary receiver, 15 is an air transport facility, 16 is an internal pressure detection A control device, 17 is a steam injection hole, 18 is a steam introduction pressure gauge, 19 is a pressure reducing valve, and 20 is a steam source pressure gauge.
The foamed particles thus obtained are excellent in gloss, and the foamed particle plate obtained by pressing the foamed particles has a surface glossiness of 30 to 60. The surface glossiness is particularly preferably from 35 to 50. The molded body obtained from the expanded particles has a stable dimension over a long period of time, is excellent in surface smoothness, and can realize a beautiful appearance. When the surface glossiness is less than 30, the foamed molded product looks dark and the product value may be remarkably inferior. On the other hand, if it is larger than 60, the internal fusion of the molded article is poor, and sufficient mechanical strength may not be obtained. The method for measuring the surface glossiness is described in the column of Examples.
[0022]
The self-extinguishing styrenic resin foamed particles thus obtained are usually left in the atmosphere for aging. The aging time of the expanded particles is determined on the basis that air in the atmosphere supplements that the bubbles generated by the expansion are cooled after being expanded and reduced in pressure to return to normal pressure. The time is about 4 hours, and in a shorter time, the inside of the bubbles of the foamed particles is depressurized. Therefore, the foamed particles may shrink during in-mold molding, and a good foam molded product may not be obtained. is there. In addition, the foamed particles obtained in the present invention have no particular upper limit on the standing time, and if the base resin itself does not deteriorate, even foamed particles that have passed one year after foaming can be used without any problems.
The average cell diameter suitable for molding the expanded particles in the mold is 50 to 500 μm, preferably 100 to 300 μm. If the average cell diameter is smaller than 50 μm, the foam surface is melted and contracted by heating, and a good foamed molded product may not be obtained. On the other hand, if the average cell diameter is larger than 500 μm, a molded product having excellent strength cannot be obtained.
The self-extinguishing styrene resin foam particles obtained in this way are subjected to so-called in-mold molding by a known method to form various foam molded products (for example, building wall materials, floor materials, ceiling materials, etc.). It is used as a material for obtaining a heat insulating material, a buffer material for civil engineering such as an EPS civil engineering method, and a packaging material.
[0023]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited by this.
First, the evaluation method of a styrene resin particle foam and a foaming molding is shown below.
[Weight average molecular weight]
The weight average molecular weight (Mw) of the polymer was measured by GPC (Gel Permeation Chromatography) under the following conditions.
Measuring device: Tosoh Corporation high-speed GPC device HLC-8020
Column: manufactured by Sekisui Fine Chemical Co., Ltd. HSG-60S × 2, HSG-40H × 1, HSG-20H × 1
Column temperature: 40 ° C., mobile phase: THF (tetrahydrofuran),
Flow rate: 1.0 ml / min, injection volume: 500 ml
Detector: RID-6A manufactured by Tosoh Corporation
Measurement of the molecular weight of a sample: When measuring the molecular weight of a sample, the molecular weight distribution of the sample is included in a range in which the logarithm of the molecular weight and the number of counts of a calibration curve created by several monodisperse polystyrene standard samples are linear. Measurement conditions were selected. In the present invention, the polystyrene calibration curve has a weight average molecular weight of 2.74 × 10. Three 1.91 × 10 Four 1.02 × 10 Five 3.55 × 10 Five 2.89 × 10 6 4.48 × 10 6 These were prepared using 6 polystyrene standard samples (TSK standard polystyrene) manufactured by Tosoh Corporation.
[0024]
[Fusion rate]
After a 300 mm long cut from a pair of long sides to a long side is put into a depth of about 5 mm with a cutter knife on one surface of a foam molded body having a plate shape of length 400 mm, width 300 mm, and thickness 30 mm, The foamed molded product is divided into two by hand along this line, and the number of particles broken at the interface between the particles (a) and the number of particles broken at the interface between the particles (a) b) and the following formula
Fusing rate (%) = [(a) / {(a) + (b)}] × 100
The value obtained by substituting for is the fusion rate (%).
[0025]
[Combustion quality]
The flammability was measured by the combustion test A method of JIS A9511. In this JIS standard, the self-extinguishing time needs to be within 3.0 seconds. In addition, it is more preferable if it is within 2.0 seconds.
[Quantification of polymerization conversion and residual styrene content]
The polymerization conversion rate was calculated by the following formula.
Polymerization conversion rate (% by weight) = 100 × (A−B) / A
The amount of residual styrene was calculated by the following formula.
Residual styrene content (% by weight) = 100 × B / A
However, A is the weight (g) of the styrene resin particle containing the unreacted styrene monomer, and B is the weight of the unreacted monomer in the resin particle containing the unreacted styrene monomer ( g). B is quantified by, for example, gas chromatography (GC). Quantification of styrene monomer by DC was measured by dissolving styrene resin particles in N, N-dimethylformamide and adding an internal standard solution (cyclopentanol).
GC: Shimadzu Corporation GC-14A
Column: PEG-20M PT25% 60/80 (2.5 m)
Column temperature: 105 ° C
Detector (FID) temperature: 220 ° C
[0026]
[Content of volatile organic compounds]
The values obtained by the following three measurement methods are summed up.
(Measurement of hydrocarbon compounds having 5 or less carbon atoms)
A predetermined amount of sample cut out from the expanded resin particles or the expanded molded article is placed in a 180 ° C. pyrolysis furnace, and the volatilized hydrocarbon is measured by gas chromatography. In addition, about the foaming molding, the test piece was cut out from the site | part which entered 100 mm from the long side and the short side of the foaming molding obtained in the Example, and 5 mm from the upper and lower surfaces, and it was set as the measurement sample.
Gas chromatography (GC): GC-14B manufactured by Shimadzu Corporation
Pyrolysis furnace: Shimadzu PYR-1A
Column: Polapack Q 80/100 (3mmφ × 1.5m)
Column temperature: 100 ° C
Detector (FID) temperature: 120 ° C
(Measurement of hydrocarbons with 6 or more carbon atoms up to the styrene peak appearing in the gas chromatogram)
In the same manner as described above, a predetermined amount of sample cut out from the expanded resin particles or the expanded molded article is dissolved in dimethylformamide, an internal standard solution (cyclopentanol) is added, and measurement is performed by GC. However, the peaks that cannot be identified are quantified in terms of the detected amount of toluene.
GC: Shimadzu Corporation GC-14A
Column: PEG-20M PT25% 60/80 (2.5 m)
Column temperature: 105 ° C
Detector (FID) temperature: 220 ° C
(Measurement of hydrocarbons from the next peak of styrene appearing in the gas chromatogram to 16 carbon atoms (n-hexadecane))
[0027]
In the same manner as described above, a predetermined amount of sample cut out from the expanded resin particles or the expanded molded article is dissolved in chloroform and measured with a gas chromatograph mass spectrometer (GCMS). However, perform a blank test only for solvents that do not dissolve the test piece, and subtract the amount of substance detected in the blank test. Furthermore, about the peak which cannot be specified, it converts into the detected amount of toluene, and quantifies it.
GCMS: QP5000 manufactured by Shimadzu Corporation
Column: DB-1 manufactured by J & W Scientific
(1μm × 60m 0.25mmφ)
Measurement conditions: Column temperature
(After holding at 60 ° C for 1 minute, the temperature is raised to 300 ° C at 10 ° C / min)
Split ratio: 10
Carrier gas: He (1 ml / min)
Interface temperature: 260 ° C
[0028]
[Glossiness of surface]
The surface glossiness refers to a value measured as follows in accordance with JIS K7105 (plastic optical property test method). However, as the test piece, a foamed particle plate obtained by pressing foamed particles was prepared and used. The ratio (%) of regular reflection when light is applied to this smooth surface at an angle of 60 degrees is defined as surface glossiness. Specifically, a stainless steel cylindrical container (inner diameter: 76 mm, depth: 15 mm) is filled with foamed particles so as not to pile up, and the opening of this container is covered with aluminum foil, and a stainless steel disk with a diameter of 75 mm (surface The smooth surface of the foamed particles is formed by leaving for 72 hours under a pressure of 15 MPa in a press using a mirror finish). The measuring surface is a smooth surface on the disk side. The surface glossiness is measured by measuring the smooth surface with an optical system having an incident angle of 60 degrees and a light receiving angle of 60 degrees (60-degree meter) using a glossiness measuring device (Gloss Checker IG-330: manufactured by HORIBA, Ltd.). Obtainable. However, measurement is performed under conditions that are not affected by external light, such as in a dark room.
The measurement of the expanded particle plate is performed within 30 seconds after releasing the pressurization state of the press. In addition, a boundary line between the expanded particles appears on the test piece, but there is no particular problem even if this boundary line is included in the measurement.
Optical measurement is performed at 7 arbitrary positions on the measurement surface that do not overlap with each other, and the average of 5 points excluding the maximum value and the minimum value is used as the glossiness of the test piece. This series of measurements is performed three times for one type of expanded particle, and the average of the three times is defined as the glossiness of the expanded particle.
[0029]
[Dimensional change rate]
A foam molded body having a plate shape of 400 mm in length, 300 mm in width, and 30 mm in thickness is taken out of the mold and left in a constant temperature and humidity chamber (standard temperature and humidity state of JIS K7100) at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours. After that, a square flat plate (length: 150 mm, width: 150 mm, thickness: 30 mm) is cut out from the center portion of the foamed molded body in parallel with each other in the vertical and horizontal directions. A straight line is entered at an interval of 50 mm to obtain a test piece according to JIS K6767. This test piece was placed horizontally in a dryer maintained at 23 ° C., taken out after 720 hours, and again left in a constant temperature and humidity room for 1 hour. The dimension measurement is performed in accordance with JIS K6767, and the dimensional change rate is obtained according to the following equation.
Dimensional change rate (%) = (L2-L1) × 100 / L1
(However, L1 is the size of a test piece obtained from a styrene resin foam molded article left at 23 ° C. and 50% relative humidity for 24 hours after in-mold molding, and L2 is 23 ° C. of the styrene resin foam molded article. The size of the test piece after standing for 720 hours at
In addition, a dimension is the average value of the length of 3 lines each written in the test piece.
In addition, a test piece different from the above was placed horizontally in a hot-air circulating drier kept at 80 ° C., taken out after performing a heating test for 168 hours, and left again in a constant temperature and humidity chamber for 1 hour to change the dimensional change rate. Ask for. This dimensional change rate is referred to as a heating dimensional change rate.
[0030]
[Measurement of melt flow rate (MFR)]
The measurement of MFR was performed under the following conditions based on JIS K7210.
Measuring device: Melt indexer manufactured by Toyo Seiki Seisakusho
Measurement temperature: 200 ° C
Measurement load: 5.0kgf
Orifice diameter: 2.09 mm
[0031]
Example 1
The polystyrene resin particles used were polymerized as follows.
A reactor having a volume of 100 liters equipped with a stirrer was charged with 36 liters of deionized water, 75 g of magnesium pyrophosphate and 6 g of sodium dodecylbenzenesulfonate, followed by 120 g of benzoyl peroxide and t-butylperoxybenzoate as polymerization initiators. 46 kg of styrene in which 29 g was dissolved was placed in a reactor, stirred, heated to 90 ° C., held for 6 hours, then heated to 125 ° C. and held for 3 hours for polymerization. The polymerization conversion rate at the end of the polymerization was 99.98%. After cooling, the contents were taken out, washed, dehydrated and dried, and then passed through a sieve to obtain polystyrene resin particles having a particle diameter of 0.9 to 1.2 mm. The polystyrene resin particles had a weight average molecular weight of 280000.
[0032]
2 kg of the above polystyrene resin particles, 0.5 g of sodium dodecylbenzenesulfonate, 6 g of magnesium pyrophosphate, 2 liters of water, and 30.0 g (1.5% by weight) of tris (2,3-dibromopropyl) isocyanurate A composite flame retardant mixed with 6.0 g (0.3 wt%) of 2,3-dimethyl-2,3-diphenylbutane was blended, and the temperature was raised to 120 ° C. while stirring in a closed vessel having an internal volume of 5 liters. After holding for 3 hours, the mixture was cooled to 25 ° C., and the resin particles were taken out from the sealed container. Then, the resin particles were washed and dehydrated and dried to obtain self-extinguishing polystyrene resin particles.
[0033]
Moreover, when the melting point of the said composite flame retardant (BC ratio 16.7%) was measured by DTA, the melting | fusing point peak temperature was one and was 103 degreeC. In addition, melting | fusing point peak temperature of the composite flame retardant was calculated | required by performing DTA measurement based on JISK7121.
Thermal analyzer: Seiko Instruments TG / DTA6200R
Measurement sample mass: 10 mg
Temperature increase rate: 10 ° C / min
After 1 kg of the self-extinguishing polystyrene resin particles, 1.5 g of calcium carbonate fine powder as an anti-bonding agent during foaming and 0.5 g of stearic acid monoglyceride as an antistatic agent were uniformly attached to the surface of the resin particle, and then the pressure vessel The carbon dioxide gas was press-fitted to 3.0 MPa and held at 20 ° C. for 6 hours. After releasing the internal pressure in the pressure vessel, it is immediately put into a preheated foaming machine and heated and foamed using pressurized steam (pressure introduced into the foaming machine: 0.2 MPa, pressure inside the foaming machine: 0.07 MPa). Polystyrene resin expanded particles were obtained. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. The foamed particles were filled in a mold and heated and foam-molded with water vapor to obtain a self-extinguishing foam molded body having a plate shape having a length of 400 mm, a width of 300 mm, and a thickness of 30 mm. Table 1 shows the measurement results of fusion, appearance, and flammability of the obtained foamed molded product.
[0034]
(Example 2)
40.0 g (2.0 wt%) of tris (2,3-dibromopropyl) isocyanurate and 8.0 g (0.4 wt%) of 2,3-dimethyl-2,3-diphenylbutane Except that, self-extinguishing polystyrene resin expanded particles were obtained in the same manner as Example 1. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 103 ° C. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, a self-extinguishing foamed molded article was obtained from the foamed particles in the same manner as in Example 1. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0035]
(Example 3)
Tris (2,3-dibromopropyl) isocyanurate was 60.0 g (3.0 wt%), and 2,3-dimethyl-2,3-diphenylbutane was 8.0 g (0.4 wt%). Except that, self-extinguishing polystyrene resin expanded particles were obtained in the same manner as Example 1. Further, the melting point of the composite flame retardant (BC ratio 11.8%) was measured by DTA in the same manner as in Example 1. As a result, the melting point peak temperature was 1, which was 104 ° C. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, a self-extinguishing foamed molded article was obtained from the foamed particles in the same manner as in Example 1. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0036]
Example 4
Self-extinguishing type in the same manner as in Example 1 except that 2,4-dimethyl-2,3-diphenylbutane was changed to 6.0 g (0.3 wt%) of 3,4-dimethyl-3,4-diphenylhexane. Polystyrene resin expanded particles were obtained. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 131 ° C. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, a self-extinguishing foamed molded article was obtained from the foamed particles in the same manner as in Example 1. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0037]
(Example 5)
Using the same method as Example 1, self-extinguishing polystyrene resin particles were obtained. After 1 kg of the self-extinguishing polystyrene resin particles, 1.5 g of calcium carbonate fine powder as an anti-binding agent at foaming and 0.5 g of stearic acid monoglyceride as an antistatic agent were uniformly attached to the resin particle surface, and then the pressure vessel The carbon dioxide gas was press-fitted to 3.0 MPa and held at 20 ° C. for 6 hours. After releasing the internal pressure in the pressure vessel, it is immediately put into a preheated foaming machine (a foaming machine equipped with the introduction line and an exhaust line capable of electrically controlling the opening degree of the exhaust valve), and 0.2 MPa The above was introduced into the foaming machine. At this time, the pressure of the excessive supply was released to the outside using an exhaust line so that the pressure in the foaming machine was 0.07 MPa. In this way, the above was continuously introduced into the foaming machine and foamed by heating to obtain self-extinguishing polystyrene resin foamed particles. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 103 ° C. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. The foamed particles were filled into a mold and heated and foamed with water vapor to obtain a self-extinguishing foamed molded body. Table 1 shows the measurement results of fusion, appearance, and flammability of the obtained foamed molded product.
[0038]
(Comparative Example 1)
For 1 kg of the same polystyrene resin particles as in Example 1, 1.5 g of calcium carbonate fine powder as a binding inhibitor at the time of foaming and 0.5 g of stearic acid monoglyceride as an antistatic agent were uniformly attached to the surface of the resin particles. The container was sealed in a container, and then carbon dioxide gas was injected to 3.0 MPa and held at 20 ° C. for 6 hours. After releasing the internal pressure of the pressure vessel, it was immediately put into a preheated foaming machine and heated and foamed using heated steam to obtain polystyrene resin expanded particles. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, the foamed particles were obtained in the same manner as in Example 1 to obtain foamed molded articles. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0039]
(Comparative Example 2)
Polystyrene resin exactly as in Example 1 except that 60 g (3.0 wt%) of tris (2,3-dibromopropyl) isocyanurate was used and 2,3-dimethyl-2,3-diphenylbutane was not used. Expanded particles were obtained. Moreover, when the melting point of the flame retardant was measured by DTA in the same manner as in Example 1, the melting point peak temperature was 1, which was 115 ° C. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, a self-extinguishing foamed molded article was obtained from the foamed particles in the same manner as in Example 1. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0040]
(Comparative Example 3)
Expanded polystyrene resin particles were obtained in the same manner as in Example 1 except that 2,3-dimethyl-2,3-diphenylbutane was changed to 6.0 g (0.3 wt%) of dicumyl peroxide. However, a bond of 180 g was generated with respect to 1 kg of the resin particles introduced at the time of foaming. Further, when the melting point of the composite flame retardant (DCP ratio 16.7%) was measured with DTA in the same manner as in Example 1, DCP was decomposed during the measurement and measurement was impossible. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. The foamed particles were filled into a mold and heated and foamed with water vapor to obtain a foamed molded product. The obtained foamed molded product was poorly fused at 30%, the appearance was shrunk, and a good molded product could not be obtained. The measurement results of the combustibility of this foamed molded product are also shown in Table 1.
[0041]
(Comparative Example 4)
Polystyrene resin particles were obtained in the same manner as in Example 1 except that tris (2,3-dibromopropyl) isocyanurate was changed to 30.0 g (1.5% by weight) of tetrabromocyclooctane. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 88 ° C. To 1 kg of polystyrene resin particles, 1.5 g of calcium carbonate fine powder as an anti-bonding agent during foaming and 0.5 g of stearic acid monoglyceride as an antistatic agent are uniformly attached to the surface of the resin particles, and then sealed in a pressure vessel. Then, carbon dioxide was injected under pressure up to 3.0 MPa and held at 20 ° C. for 6 hours. After releasing the internal pressure in the pressure vessel, it was immediately put into a preheated foaming machine and heated and foamed using pressurized steam. As a result, foamed particles were bonded together in the foaming machine, and moldable foamed particles could not be obtained.
[0042]
(Comparative Example 5)
Tris (2,3-dibromopropyl) isocyanurate was changed to 40.0 g (2.0% by weight) of tetrabromocyclooctane, and 8.0 g (0.4% by weight) of 2,3-dimethyl-2,3-diphenylbutane. Except for the above, polystyrene resin particles were obtained in the same manner as in Example 1. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 88 ° C. To 1 kg of polystyrene resin particles, 1.5 g of calcium carbonate fine powder as an anti-bonding agent during foaming and 0.5 g of stearic acid monoglyceride as an antistatic agent are uniformly attached to the surface of the resin particles, and then sealed in a pressure vessel. Then, carbon dioxide was injected under pressure up to 3.0 MPa and held at 20 ° C. for 6 hours. After releasing the internal pressure in the pressure vessel, it was immediately put into a preheated foaming machine and heated and foamed using pressurized steam. As a result, foamed particles were bonded together in the foaming machine, and moldable foamed particles could not be obtained.
[0043]
(Comparative Example 6)
Polystyrene resin particles were obtained in the same manner as in Example 1 except that tris (2,3-dibromopropyl) isocyanurate was changed to 30.0 g (1.5% by weight) of hexabromocyclododecane. However, the flame retardant remains in the reaction solution used for this impregnation reaction, which indicates that the polystyrene resin particles are hardly impregnated with the flame retardant. Further, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was two, the melting point of BC was 106 ° C., and the melting point of HBCD was 190. ° C. Next, polystyrene resin expanded particles were obtained in the same manner as in Example 1. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, the foamed particles were obtained in the same manner as in Example 1 to obtain foamed molded articles. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0044]
(Comparative Example 7)
Tris (2,3-dibromopropyl) isocyanurate was changed to 40.0 g (2.0% by weight) of hexabromocyclododecane, and 8.0 g (0.4% by weight) of 2,3-dimethyl-2,3-diphenylbutane. Except for the above, polystyrene resin particles were obtained in the same manner as in Example 1. However, the flame retardant remains in the reaction solution used for this impregnation reaction, which indicates that the polystyrene resin particles are hardly impregnated with the flame retardant. Further, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was two, the melting point of BC was 105 ° C., and the melting point of HBCD was 190. ° C. Moreover, it carried out similarly to Example 1, and obtained the polystyrene resin expanded particle. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, the foamed particles were obtained in the same manner as in Example 1 to obtain foamed molded articles. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0045]
(Comparative Example 8)
Tris (2,3-dibromopropyl) isocyanurate was changed to 60.0 g (3.0% by weight) of hexabromocyclododecane, and 12.0 g (0.6% by weight) of 2,3-dimethyl-2,3-diphenylbutane. Except for the above, polystyrene resin particles were obtained in the same manner as in Example 1. However, the flame retardant remains in the reaction solution used for this impregnation reaction, which indicates that the polystyrene resin particles are hardly impregnated with the flame retardant. Further, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was two, the melting point of BC was 106 ° C., and the melting point of HBCD was 190. ° C. Moreover, it carried out similarly to Example 1, and obtained the polystyrene resin expanded particle. Table 1 shows the average cell diameter, bulk expansion ratio, styrene monomer content, and volatile organic compound content after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, the foamed particles were obtained in the same manner as in Example 1 to obtain foamed molded articles. Table 1 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded product.
[0046]
[Table 1]
Figure 0003935849
[0047]
From Table 1, the expanded particles of Examples 1 to 5 had few bonds at the time of expansion, and the handling was good. Furthermore, the foamed molded product obtained from the foamed particles had good fusion rate and appearance, and in addition, the combustion test showed excellent self-extinguishing properties of 3 seconds or less.
The foamed particles and foamed molded product of Comparative Example 1 had a low amount of bonding at the time of foaming and good fusion rate and appearance, but they did not contain flame retardants and flame retardant aids, so the self-extinguishing properties were extremely poor. .
The foamed particles of Comparative Example 2 had a low amount of self-extinguishing because they had a large amount of bonding during foaming and did not contain a flame retardant aid.
The foamed particles and foamed molded product of Comparative Example 3 have more bonds during foaming than Comparative Example 2, and the resulting foamed molded product has poor fusion rate, the appearance melts the surface, and the entire molded product shrinks. Appearance was defective.
In Comparative Examples 4 and 5, the entire foamed particles were bonded at the time of foaming, and moldable foamed particles were not obtained.
The foamed particles and foamed molded articles of Comparative Examples 6 to 8 had good bonding amount at the time of foaming, a fusion rate, and an appearance, but were substantially inferior in self-extinguishing properties because they did not substantially contain a flame retardant.
The measurement results of the glossiness and the dimensional change rate of Examples 1 to 5 are shown in Table 2.
[0048]
[Table 2]
Figure 0003935849
[0049]
From Table 2, among the foamed molded products of Examples 1 to 5, the foamed molded product of Example 5 having a high glossiness was a molded product having a particularly small dimensional change rate and excellent dimensional stability.
[0050]
(Example 6)
In this example, a styrene resin is formed by suspension polymerization, and then a flame retardant and a flame retardant aid are added to the suspension.
A reactor having an internal volume of 100 liters equipped with a stirrer was charged with 30 liters of deionized water, 100 g of magnesium pyrophosphate and 15 g of sodium dodecylbenzenesulfonate, and had a particle size of 0.63 to 0.71 mm and a weight average molecular weight of 280000. 11 kg of polystyrene resin particles (obtained by subjecting styrene to normal suspension polymerization in an aqueous medium using magnesium pyrophosphate and sodium dodecylbenzenesulfonate) were added and stirred for suspension.
[0051]
Next, 5 kg of styrene dissolved in 90 g of benzoyl peroxide and 8 g of t-butylperoxybenzoate was added to a suspension of 6 liters of deionized water, 2 g of sodium dodecylbenzenesulfonate, and 10 g of magnesium pyrophosphate. Stir to a suspension and add to the reactor maintained at 70 ° C. Then, after holding for 1 hour so that styrene and the polymerization initiator are sufficiently absorbed in the polystyrene particles, styrene is continuously supplied at a rate of 10 kg / hour for 3 hours, and reaches 105 ° C. at the end of the styrene supply. Thus, after raising the temperature of the reactor, the temperature was continuously raised to 120 ° C. and held for 2 hours. The polymerization conversion rate at the end of the polymerization was 99.98%.
[0052]
Next, it is cooled to 90 ° C., 2 liters of deionized water prepared in advance, 2 g of sodium dodecylbenzenesulfonate, 690 g of tris (2,3-dibromopropyl) isocyanurate and 138 g of 2,3-dimethyl-2,3-diphenylbutane A composite flame retardant suspension consisting of the above was pressed into a reactor, heated to 120 ° C. and held for 3 hours. Moreover, when the melting point of the composite flame retardant (BC ratio 16.7%) was measured by DTA in the same manner as in Example 1, the melting point peak temperature was one and was 103 ° C. Thereafter, the contents were taken out by cooling to room temperature, washed, dehydrated and dried to obtain self-extinguishing polystyrene resin particles having a particle size of 0.9 to 1.2 mm. The weight average molecular weight of the resin particles was 300000. Self-extinguishing polystyrene resin foam particles were obtained from the self-extinguishing polystyrene resin particles in the same manner as in Example 1.
Table 3 shows the average cell diameter and bulk expansion ratio after the obtained expanded particles were allowed to stand at room temperature and normal pressure for 1 day and dried. Further, a self-extinguishing foamed molded article was obtained from the foamed particles in the same manner as in Example 1. Table 3 shows the measurement results of fusion, appearance, and combustibility of the obtained foamed molded article.
[0053]
[Table 3]
Figure 0003935849
[0054]
Even if the foamed particles of Example 6 from Table 3 are obtained from styrene resin particles obtained by adding a flame retardant and a flame retardant aid to the suspension after polymerization, there are few bonds during foaming, Handling was good. Further, the foamed molded product obtained from the foamed particles had good fusion rate and appearance, and in addition, the combustion test showed excellent self-extinguishing properties of 3 seconds or less.
[0055]
(Example 7)
This example is an example for evaluating the recyclability of the foamed molded products of the above examples and comparative examples.
The melt flow rate (MFR) of the polystyrene resin particles obtained in Examples 1 and 2 and Comparative Examples 1, 3, and 4 was measured. Further, the weight average molecular weight of the resin particles before and after the MFR measurement was also measured. Table 4 shows the MFR and the weight average molecular weight.
[0056]
[Table 4]
Figure 0003935849
[0057]
First, the MFR of polystyrene resin that can be recycled by melting and kneading with an extruder and forming a strand is 20 g / 10 min or less, preferably 15 g / 10 min or less, particularly close to the MFR when no flame retardant is added. Is preferred. When Table 4 is seen from this viewpoint, the resin particles of Examples 1 and 2 are both 15 g / 10 min or less and can be sufficiently recycled. On the other hand, the resin particles of Comparative Examples 3 and 4 have an MFR exceeding the measurement limit of 200 g / 10 min, and are difficult to recycle.
Furthermore, it is desired from the viewpoint of recycling that the weight average molecular weight does not change as much as possible before and after the heat treatment (MFR measurement treatment). If greatly reduced, it cannot be extruded as a strand after being melt-kneaded by an extruder, or the strand is frequently cut and recycling is difficult. Looking at Table 4 from this point of view, the resin particles of Examples 1 and 2 have a lower weight average molecular weight than the case where no flame retardant is added, and can be sufficiently recycled. On the other hand, the resin particles of Comparative Examples 3 and 4 have a greatly reduced weight average molecular weight, and even after recycling, the strength is not significantly reduced and cannot be reused.
[0058]
【The invention's effect】
According to the present invention, it is possible to obtain a styrene resin foam molded article having good production efficiency and excellent self-extinguishing properties with a small amount of flame retardant. This foamed molded article has a low content of styrene monomer in the foamed molded article, and since the foaming agent is also an inorganic gas, it has properties as a low VOC material and is suitable for use as a heat insulating material for buildings and EPS civil engineering.
Self-extinguishing styrenic resin foam molded products with excellent environmental compatibility that can be recycled together with general styrenic resin foam molded products without significant decrease in molecular weight even when recycled by melt kneading with an extruder. Is obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing the melting point of a composite flame retardant.
FIG. 2 is a schematic view showing an example of a foaming machine that can be used for producing resin foam particles.
[Explanation of symbols]
2 Stirring motor
3 Stirring blade
4 baffle stick
5 Foam tank top detector
6 Expandable particle transporter
7 Expandable particle measuring tank
8 Expandable particle feeder
9 Steam injection control valve
10 Steam chamber
11 Condensate drain valve
12 Exhaust control valve
13 Foam particle outlet
14 Temporary receiver for expanded particles
15 Pneumatic transportation equipment
16 Internal pressure detection and control device
17 Steam blow hole
18 Steam pressure gauge
19 Pressure reducing valve
20 Steam source pressure gauge

Claims (7)

複合難燃剤を含むスチレン系樹脂を発泡剤としての無機ガスで発泡させて得られ、複合難燃剤が、トリス(2,3−ジブロモプロピル)イソシアヌレートである難燃剤90〜40重量%と、下記一般式
【0001】
Figure 0003935849
【0001】
(式中、R1〜R4は、同一又は異なって、メチル又はエチル基である)で表わされる難燃助剤10〜60重量%から構成され、スチレン系樹脂粒子100重量部に対して1〜7重量部含まれる
ことを特徴とする自己消火型スチレン系樹脂発泡粒子。
90-40% by weight of a flame retardant obtained by foaming a styrene resin containing a composite flame retardant with an inorganic gas as a foaming agent, and the composite flame retardant is tris (2,3-dibromopropyl) isocyanurate; General formula
Figure 0003935849
[0001]
(Wherein R1 to R4 are the same or different and are methyl or ethyl groups) and are composed of 10 to 60% by weight of a flame retardant aid represented by 1 to 7 with respect to 100 parts by weight of styrene resin particles. Self-extinguishing styrene-based resin expanded particles, characterized in that they are contained in parts by weight.
自己消火型スチレン系樹脂発泡粒子をプレスして得られた予備発泡粒子板が、30〜60の表面光沢度を有する請求項1に記載の自己消火型スチレン系樹脂発泡粒子。The self-extinguishing styrenic resin expanded particles according to claim 1, wherein the pre-expanded styrene resin expanded particles obtained by pressing the self-extinguishing styrenic resin expanded particles have a surface glossiness of 30 to 60. スチレン系モノマーの含有量が、スチレン系樹脂に対して500ppm以下である請求項1に記載の自己消火型スチレン系樹脂発泡粒子。The self-extinguishing styrene resin foamed particle according to claim 1, wherein the content of the styrene monomer is 500 ppm or less with respect to the styrene resin. 難燃助剤が、2,3−ジメチル−2,3−ジフェニルブタン又は3,4−ジメチル−3,4−ジフェニルヘキサンである請求項1に記載の自己消火型スチレン系樹脂発泡粒子。The self-extinguishing styrenic resin expanded particle according to claim 1, wherein the flame retardant aid is 2,3-dimethyl-2,3-diphenylbutane or 3,4-dimethyl-3,4-diphenylhexane. 無機ガスが、炭酸ガスである請求項1に記載の自己消火型スチレン系樹脂発泡粒子。The self-extinguishing styrene-based resin expanded particle according to claim 1, wherein the inorganic gas is carbon dioxide. 請求項1〜5のいずれか1つに記載の自己消火型スチレン系樹脂発泡粒子を型内成形法にて成形して得られた自己消火型発泡成形体。A self-extinguishing type foamed molded article obtained by molding the self-extinguishing type styrene resin foamed particles according to any one of claims 1 to 5 by an in-mold molding method. 揮発性有機化合物の含有量が、スチレン系樹脂に対して1000ppm以下である請求項6に記載の自己消火型発泡成形体。The self-extinguishing foam molded article according to claim 6, wherein the content of the volatile organic compound is 1000 ppm or less with respect to the styrene resin.
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JP5558038B2 (en) * 2009-03-30 2014-07-23 積水化成品工業株式会社 Expandable polystyrene resin particles and method for producing the same
CN103170299B (en) * 2013-03-27 2014-09-03 张家港市科华化工装备制造有限公司 Expandable polystyrene reaction kettle

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