JP3550184B2 - Flame retardant polyolefin resin foam - Google Patents

Description

（式中Ｒ^１ 〜Ｒ^３ は、それぞれ水素または炭素数１〜１６のヒドロキシアルキル基、ジヒドロキシアルキル基、ヒドロキシアリール基またはジヒドロキシアリール基を示す。）
【００１１】
請求項２記載の本発明は、示差走査熱量分析（ＤＳＣ）で示される結晶融解終了温度が１５５℃以下のポリプロピレン系樹脂５〜８５重量部とポリエチレン系樹脂９５〜１５重量部とからなるポリオレフィン系樹脂１００重量部に対し、請求項１記載の２成分混合難燃剤５〜２００重量部及び熱分解型有機発泡剤を含有させた樹脂組成物を架橋し、発泡させてなる難燃性ポリオレフィン系樹脂発泡体をその特徴とするものである。
【００１２】
請求項２記載の本発明で用いるポリオレフィン系樹脂は、ポリプロピレン系樹脂５〜８５重量部とポリエチレン系樹脂９５〜１５重量部からなる。
【００１３】
上記ポリプロピレン系樹脂は、特に限定されるものでなく、プロピレンの単独重合体又はプロピレンを主成分とする共重合体、これらの混合物のいずれでもよい。共重合体としては、例えばプロピレン成分を８５重量部％以上含むα−オレフィン共重合体を挙げることができる。α−オレフィンとしては、エチレン、１−ヘキセン、４−メチル−１−ペンテン、１−オクテン、１−ブテン、１−ペンテン等を挙げることができる。
【００１４】
上記ポリプロピレン系樹脂のメルトインデックス（ＭＩ）は、ＪＩＳ Ｋ７２１０に基づき、温度２３０℃、荷重２．１６ ｋｇｆ の通常の条件で測定されるもので、０．２〜２０のものが好適に使用される。そのＭＩが０．２未満では、シート化する際に外観上問題が生じ、ＭＩが２０を越えると、得られる発泡体の耐熱性が不十分となる。
【００１５】
請求項２記載の本発明で用いるポリプロピレン系樹脂は、ＤＳＣ（Defferential Scanninng Calorimetry）による結晶融解終了温度が１５５℃以下のものであれば請求項１記載の本発明において使用される上記ポリプロピレン系樹脂の中から適宜選択使用される。
猶、上記ＤＳＣによる結晶融解終了温度は、樹脂の融解ピーク温度とは全く趣を異にするものであり、熱可塑性樹脂の成形加工時の流れの難易度を的確に示す指標である。
又、上記結晶融解終了温度が１５５℃を超す場合、成形加工時の流れが悪くなり、発泡剤の初期分解を起こし易く、発泡工程の温度制御が難しくなるといった生産技術上の問題点を解消することができないのである。
【００１６】
請求項２記載の本発明のポリオレフィン系樹脂組成物における上記ポリプロピレン系樹脂が８５重量部を超えると、発泡体の柔軟性が不十分となる。又、請求項２記載の本発明のポリオレフィン系樹脂組成物中に含まれる上記ポリプロピレン系樹脂が５重量部未満であると、得られる発泡体の材料強度が不十分となる。
【００１７】
請求項１記載の本発明で用いるマレイン酸成分を持つポリエチレン系樹脂は、例えば、エチレン−酢酸ビニル共重合体またはエチレン−α−オレフィン共重合体にマレイン酸または無水マレイン酸をグラフト重合する等、マレイン酸誘導体または無水マレイン酸誘導体とするか、もしくは、エチレン−エチルアクリレート−無水マレイン酸共重合体、エチレン−メチルメタクリレート−無水マレイン酸共重合体等が挙げられる。
【００１８】
上記マレイン酸成分を持つポリエチレン系樹脂は、ポリオレフィン系樹脂の全量に対し５〜５０重量％を含有するが、その含有量がポリオレフィン系樹脂の全量に対し５重量％未満である場合、難燃剤のブリードアウトを抑制できず、長期の難燃性を確保することが難しく、５０重量％を超える場合、成形性が難しくなり、得られる発泡体の外観が悪くなる。
【００１９】
請求項１及び２記載の本発明で用いるポリエチレン系樹脂は、エチレンの単独重合体（低密度、中密度、高密度）、エチレンを主成分とする共重合体、これらの混合物のいずれでもよい。共重合体としては、例えばエチレン成分を８０重量％以上含むエチレン−αオレフィン共重合体（線状低密度ポリエチレン）、エチレン−酢酸ビニル共重合体等を挙げることができる。特に、線状低密度ポリエチレンが好ましい。
【００２０】
上記ポリエチレン系樹脂のメルトインデックス（ＭＩ） は、ＪＩＳ Ｋ７２１０に基づき、温度１９０℃、荷重２．１６ ｋｇｆ の通常の条件で測定されるもので、そのＭＩは、０．１〜４０のものが好ましく、そのＭＩが０．１未満であると、上記ポリオレフィン系樹脂組成物の発泡前の粗シートを成形する際に外観上問題を生じ、ＭＩが１０を越えると、発泡後、得られる発泡体の材料強度が不十分となる。
【００２１】
請求項１及び２記載の本発明で用いる上記ポリリン酸アンモニウム／窒素含有化合物２成分混合難燃剤において、ポリリン酸アンモニウムは、リン酸の重合度が２００〜１，０００であり、表面がメラミン−ホルムアルデヒド樹脂等で被覆された水に難溶性の易流動性粉末が好適に用いられる。
又、上記窒素含有化合物は下記構造式で表される。
【化３】

（式中Ｒ^１ 〜Ｒ^３ は、それぞれ水素または炭素数１〜１６のヒドロキシアルキル基、ジヒドロキシアルキル基、ヒドロキシアリール基またはジヒドロキシアリール基を示す。）
上記窒素含有化合物を具体的に例示すると、例えば、イソシアヌール酸、モノ（ヒドロキシメチル）イソシアヌレート、ビス（ヒドロキシメチル）イソシアヌレート、トリス（ヒドロキシメチル）イソシアヌレート、モノ（ジヒドロキシメチル）イソシアヌレート、ビス（ジヒドロキシメチル）イソシアヌレート、トリス（ジヒドロキシメチル）イソシアヌレート、モノ（２−ヒドロキシエチル）イソシアヌレート、ビス（２−ヒドロキシエチル）イソシアヌレート、トリス（２−ヒドロキシエチル）イソシアヌレート、トリス（１，２−ジヒドロキシエチル）イソシアヌレート、トリス（３−ヒドロキシプロピル）イソシアヌレート、トリス（２，３−ジヒドロキシプロピル）イソシアヌレート、トリス（４−ヒドロキシブチル）イソシアヌレート、トリス（３，４−ジヒドロキシブチル）イソシアヌレート、トリス（８−ヒドロキシオクチル）イソシアヌレート、トリス（４−ヒドロキシフェニル）イソシアヌレート、トリス（２，４−ジヒドロキシフェニル）イソシアヌレート、トリス（２，３−ジヒドロキシフェニル）イソシアヌレート等が挙げられる。
【００２２】
上記２成分混合難燃剤の混合比は、（ポリリン酸アンモニウム）：（上記窒素含有化合物）＝８０〜５０重量％：２０〜５０重量％の範囲で用いるのがよい。又、上記２成分混合難燃剤は、ポリオレフィン系樹脂１００重量部に対し、５〜２００重量部の割合で添加されるのが好ましく、添加量が５重量部未満の場合、得られる発泡体の難燃性が十分に得られず、添加量が２００重量部を超える場合、得られる発泡体の機械的強度の低下が大きく実用に供することが難しい。
【００２３】
請求項１及び２記載の本発明において、上記２成分混合難燃剤に加えて、水酸化アルミニウム、水酸化マグネシウム、塩基性炭酸マグネシウム等の水和金属酸化物、酸化アルミニウム、酸化マグネシウム、酸化チタン、酸化鉄等の金属酸化物、赤リン等の難燃助剤を使用することは、本発明の精神を逸脱せざる範囲において許される。
猶、上記難燃助剤の内、赤リンは耐湿性、安全性等から赤リン粒子を合成樹脂でコーティングしたものが好適に使用される。
【００２４】
上記難燃助剤の添加量は、本発明で使用される上記２成分混合難燃剤の量にもよるが、本発明で使用されるポリオレフィン系樹脂組成物全量１００重量部に対し、１００重量部以下が好ましい。添加量が１００重量部を超えると、発泡特性を損ない、微細にして均質な発泡構造が得られず、外観も機械的強度も悪くなる。
【００２５】
請求項１及び２記載の本発明におけるポリオレフィン系樹脂組成物は、発泡工程における発泡に耐えるに必要な粘度を得るため、更に、得られる発泡体の耐熱性向上のため、ポリオレフィン系樹脂に架橋を施す。
請求項１及び２記載の本発明においては、上記架橋の方法としては、いかなる方法が採られてもよいが、ポリオレフィン系樹脂樹脂に混合した過酸化物等のラジカル発生剤を加熱分解させて架橋する方法、電離性放射線の照射による架橋方法、シラン架橋による方法等が使用できる。
【００２６】
上記ラジカル発生剤としては、例えば、ベンゾイルペルオキシド、オクタノイルペルオキシド、デカノイルペルオキシド、アセチルペルオキシド、ｔ−ブチルペルオキシイソブチレート、クメンヒドロペルオキシド等が挙げられる。
又、シラン架橋剤としては、トリメトキシビニルシラン、トリエトキシビニルシラン等が挙げられる。
【００２７】
請求項１及び２記載の本発明において、上記架橋を施す場合、ポリオレフィン系樹脂組成物中、ポリエチレン系樹脂の割合が８０重量％以下である場合には、架橋助剤を用いる。
上記架橋助剤は、多官能性モノマーで、且つ、電離性放射線あるいは過酸化物による架橋反応を起こすものであればよく、これらのものを２種以上を混合して用いてもよい。上記架橋助剤の代表的なものは、ビニル基やアリル基を１分子中に１個かあるいは２個以上含有する芳香族または脂肪族の化合物及びアクリロイルオキシ基やメタクリロイルオキシ基を１分子中に１個かあるいは２個以上含有する化合物であって、具体的には、例えばジビニルベンゼン、ジアリルベンゼン、ジビニルナフタレン、トリメチロールプロパントリメタクリレート、エチルビニルベンゼン、１，９−ノナンジオールジメタクリレート、１−ノナンモノメタクリレート、１，６−ヘキサンジオールメタクリレート、２，２−ビス〔４−（アクリロキシジエトキシ）フェニル〕プロパン、１，２，４−ベンゼントリカルボン酸トリアリルエステル、１，２−ベンゼンジカルボン酸ジアリルエステル、１，３−ベンゼンジカルボン酸ジアリルエステル、１，４−ベンゼンジカルボン酸ジアリルエステル及びこれらの近縁同族体等が挙げられる。
【００２８】
上記架橋助剤の配合量は、上記樹脂組成物の全量１００重量部に対して、０．０５〜１０重量部、より好ましくは０．５〜１０重量部であり、発泡体の用途に応じて設定される。
上記架橋助剤の配合量が０．０５重量部未満では、架橋が不十分なため、微細にして均質な発泡構造が得られず、且つ、高温での十分な材料強度が得られない。配合量が１０重量部を超える場合、上記樹脂組成物の架橋密度が大きくなり過ぎるために、上記ポリオレフィン系樹脂組成物の発泡前の粗シートを成形することが難しくなる等の問題を生ずる。
【００２９】
又、上記ポリオレフィン系樹脂組成物に対するポリエチレン系樹脂の割合が８０重量％を超える場合には、上記架橋助剤はなくてもよい。これはポリエチレン系樹脂の自己架橋性によるためで、架橋助剤なしでも電離性放射線等の架橋手段を講ずることにより十分な架橋を施すことができるからである。
【００３０】
請求項１及び２記載の本発明で使用される熱分解型発泡剤は、上記ポリオレフィン系樹脂の熔融温度よりも高い分解温度を有し、その分解温度以上の温度に加熱したとき、ガスを発生するものであればよく、例えば、アゾジカルボンアミド、ベンゼンスルホニルヒドラジド、ジニトロソペンタメチレンテトラミン、トルエンスルホニルヒドラジド、４，４−オキシビス（ベンゼンスルホニルヒドラジド）等が挙げられ、好ましくは、アゾジカルボンアミド、ジニトロソペンタメチレンテトラミンである。
【００３１】
上記熱分解型発泡剤の配合量は、上記樹脂組成物１００重量部に対して、一般に１〜４０重量部程度であり、所望の発泡倍率に応じて設定される。
【００３２】
猶、請求項１乃至４記載の本発明において、上記ポリオレフィン系樹脂組成物には、必要に応じて、発泡剤の分解促進剤、気泡核調整剤、酸化防止剤、熱安定剤、金属害防止剤、着色剤、帯電防止剤、無機充填剤等の各種添加剤を配合することができる。
【００３３】
請求項１及び２記載の本発明において、上記ポリオレフィン系樹脂組成物の各成分を単軸押出機、多軸押出機、バンバリーミキサー、ニーダーミキサー、２本ロール等の混練装置を用いて、熱分解型発泡剤が分解しない温度、例えば１５０〜１７０℃程度の温度で溶融混練し、次いで、適宜形状、例えばシート状に成形する。得られたシート状成形体に電離性放射線を照射して樹脂を架橋させた後、例えば、熱風、赤外線、メタルバス、オイルバス等により、熱分解型発泡剤の分解温度以上で且つ樹脂の融点以上の温度、例えば１９０〜２９０℃に加熱し、発泡剤の分解ガスによって樹脂を発泡させ、架橋オレフィン系樹脂発泡シートを得る。
これらの照射及び発泡工程は連続的に行ってもよく、又、バッチ式で行ってもよい。
【００３４】
電離性放射線としては、電子線、Ｘ線、β線、γ線等が使用される。照射線量は、一般に１〜１０Ｍｒａｄ程度であり、所望のゲル分率に応じて線量が設定される。
【００３５】
【作用】
請求項１記載の本発明は、叙上の如く、マレイン酸成分を有するポリエチレン系樹脂５〜５０重量％を含むポリオレフィン系樹脂組成物が使用されているので、マレイン酸、無水マレイン酸の各成分の水素結合力、化学反応力によって該樹脂組成物中にポリリン酸アンモニウムと前記構造式で表される窒素含有化合物との２成分混合難燃剤が長期に保持され、ノンハロゲン難燃化による自己消火性の優れた難燃性ポリオレフィン系樹脂発泡体を提供できるのである。加えて、上記樹脂組成物とすることによって、発泡性シートの成形時の発泡剤の初期分解が阻止されるので、上記樹脂組成物の架橋反応等と相まって、微細にして、且つ、均質な発泡構造を有する難燃性ポリオレフィン系樹脂発泡体を提供できるのである。
【００３６】
請求項２記載の本発明は、叙上の如く、ＤＳＣで示される結晶融解終了温度が１５５℃以下のポリプロピレン系樹脂５〜８５重量部とポリエチレン系樹脂９５〜１５重量部とからなるポリオレフィン系樹脂を使用することによって、該樹脂組成物から発泡性シート等の成形に際して、混練装置、成形装置における材料の均一な分散と、良好な練和、流動性により、発泡剤の初期分解が阻止され、上記樹脂組成物の架橋反応等と相まって、微細にして、且つ、均質な発泡構造を有し、表面の美麗な難燃性ポリオレフィン系樹脂発泡体を提供できるのである。
【００３７】
【実施例】
以下、本発明の実施例及び比較例を説明する。猶、実施例において、燃焼試験、ブリード性、発泡状態、初期分解、外観の各試験は以下に示した方法で測定、評価した。
猶、本発明において、示差走査熱量分析（ＤＳＣ）による結晶融解終了温度を示しているが、その測定方法を以下に示す。
【００３８】
１．燃焼試験
ＪＩＳ Ｄ１２０１（自動車室内用有機資材の燃焼性試験方法）に準拠して測定し、その燃焼性区分によって評価した。
２．ブリード性
得られた発泡シートから１６０ｍｍ×１６０ｍｍの試料を採取し、オーブン中に８０℃、４８時間放置し、常温に冷却後、上記シート表面への添加物のブリードアウトの有無を目視により観察し、○：ブリードアウト無し、×：ブリードアウト有りの２段階で評価した。
【００３９】
３．発泡状態
得られた発泡シートの横断面、縦断面をランダムに各５視野を設定し、気泡の径が微細で均質であるか否か、その発泡の状態によってシートの外観に悪影響があるか否かを目視により観察し、○：良好、×：不良の２段階で評価した。
【００４０】
４．初期分解
得られた発泡性シートの横断面、縦断面をランダムに各５視野を設定し、発泡剤の初期分解の有無を目視により観察し、○：初期分解無し、×：初期分解有りの２段階で評価した。
【００４１】
５．外観
得られた発泡シートの表面状態を表面の平滑度、変色の度合等を総合的に目視により観察し、○：良好、×：不良の２段階で評価した。
【００４２】
６．結晶融解終了温度
約１０ｍｇのポリエチレン系樹脂の試料を、アルミパンに入れ、示差走査熱量計（セイコー電子社製、ＳＳＣ５２００型）にて、試料を一度溶融させた後、５℃／分の速度で−５０℃まで冷却し、それから５℃／分の速度で昇温して測定した。
【００４３】
（実施例１＝請求項１記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．５）７０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）１５重量部、マレイン酸グラフトポリオレフィン樹脂（三井石油化学社製、商品名：アドマーＮＦ３００、ＭＩ＝１．３、密度０．９４ｇ／ｃｍ^３ ）１５重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）１５０重量部、ジビニルベンゼン（和光純薬社製）１重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１．５重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１７０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００４４】
この樹脂組成物を、温度１７０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。この発泡性シートに電子線加速機を用いて吸収線量が３．０Ｍｒａｄに相当する線量を照射して樹脂を架橋させ、これを２４０℃の熱風式発泡炉で加熱して発泡させて、表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００４５】
（実施例２＝請求項１記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．５）５０重量部と、ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）４７．５重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）２．５重量部、ポリリン酸アンモニウム（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ４６２）とイソシアヌール酸（和光純薬社製）の等重量２成分混合系難燃剤４０重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１．５重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００４６】
（実施例３＝請求項１記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．５）４０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）５４重量部、マレイン酸グラフトポリオレフィン樹脂（三井石油化学社製、商品名：アドマーＮＦ３００、ＭＩ＝１．３、密度０．９４ｇ／ｃｍ^３ ）３重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）３重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）５重量部、水酸化アルミニウム（日本軽金属社製、商品名：Ｂ７０３Ｓ）３０重量部、赤リン（燐化学社製、商品名：ノーバレッド１２０）５重量部、ジビニルベンゼン（和光純薬社製）１重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００４７】
（実施例４＝請求項１記載の発明）
ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）８０重量部と、マレイン酸グラフトポリオレフィン樹脂（三井石油化学社製、商品名：アドマーＮＦ３００、ＭＩ＝１．３、密度０．９４ｇ／ｃｍ^３ ）１５重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）５重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）３０重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００４８】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００４９】
（実施例５＝請求項１記載の発明）
ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）７０重量部と、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）２０重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）１０重量部、ポリリン酸アンモニウム（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ４６２）とイソシアヌール酸（和光純薬社製）の等重量２成分混合系難燃剤５０重量部、赤リン（燐化学社製、商品名：ノーバレッド１２０）１０重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００５０】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５１】
（実施例６＝請求項１記載の発明）
ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）１０重量部と、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）８０重量部、マレイン酸グラフトポリオレフィン樹脂（三井石油化学社製、商品名：アドマーＮＦ３００、ＭＩ＝１．３、密度０．９４ｇ／ｃｍ^３ ）１０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）８０重量部、水酸化アルミニウム（日本軽金属社製、商品名：Ｂ７０３Ｓ）８０重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００５２】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５３】
（比較例１）
ポリプロピレン系樹脂（ＭＩ＝１．５）６０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）４０重量部、ジビニルベンゼン（和光純薬社製）１重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）０．５重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例１と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５４】
（比較例２）
ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）１００重量部とアゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００５５】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５６】
（比較例３）
ポリプロピレン系樹脂（ＭＩ＝１．５）３０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）７０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）３重量部、ジビニルベンゼン（和光純薬社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１．５重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例１と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５７】
（比較例４）
ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）２５重量部と、マレイン酸グラフトポリオレフィン樹脂（三井石油化学社製、商品名：アドマーＮＦ３００、ＭＩ＝１．３、密度０．９４ｇ／ｃｍ^３ ）５０重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）２５重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）３０重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００５８】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００５９】
（比較例５）
ポリプロピレン系樹脂（ＭＩ＝１．５）７０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）２９重量部、エチレン−メチルメタクリレート−無水マレイン酸共重合体（住友化学社製、商品名：ボンダインＴＸ８０３０、ＭＩ＝３、密度０．９４ｇ／ｃｍ^３ ）１重量部、ポリリン酸アンモニウム（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ４６２）とイソシアヌール酸（和光純薬社製）の等重量２成分混合系難燃剤５０重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１．５重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例１と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００６０】
（比較例６）
ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）３０重量部と、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）７０重量部、ポリリン酸アンモニウム（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ４６２）とイソシアヌール酸（和光純薬社製）の等重量２成分混合系難燃剤３００重量部、水酸化アルミニウム（日本軽金属社製、商品名：Ｂ７０３Ｓ）１２０重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１４０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
【００６１】
この樹脂組成物を、温度１４０℃でプレスし、厚さ１．０ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表１に示す。
【００６２】
【表１】

【００６３】
（実施例７＝請求項２記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．２、ＤＳＣでの結晶融解終了温度１５２℃）７０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）３０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）１５０重量部、ジビニルベンゼン（和光純薬社製）１重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１．５重量部、アゾジカルボンアミド（大塚化学社製）１０重量部、トリメリット酸（和光純薬社製）１０重量部とを混合し、２軸押出機を用いて、１６０℃の温度で熔融混練押出して該樹脂組成物シートの厚さ０．８ｍｍの発泡性シートを得た。以下実施例１と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６４】
（実施例８＝請求項２記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．２、ＤＳＣでの結晶融解終了温度１５２℃）８０重量部と、ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）１０重量部、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）１０重量部、ポリリン酸アンモニウム（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ４６２）とイソシアヌール酸（和光純薬社製）の等重量２成分混合系難燃剤４０重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１．５重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例７と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６５】
（実施例９＝請求項２記載の発明）
ポリプロピレン系樹脂（ＭＩ＝１．２、ＤＳＣでの結晶融解終了温度１５２℃）１０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）９０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）５重量部、水酸化アルミニウム（日本軽金属社製、商品名：Ｂ７０３Ｓ）３０重量部、赤リン（燐化学社製、商品名：ノーバレッド１２０）５重量部、ジビニルベンゼン（和光純薬社製）１重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）１重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例７と同様にして表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６６】
（比較例７）
ポリプロピレン系樹脂（ＭＩ＝１．５、ＤＳＣでの結晶融解終了温度１６５℃）１００重量部と、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）３０重量部、ジビニルベンゼン（和光純薬社製）１重量部、１，９−ノナンジオールジメタクリレート（新中村化学社製）２重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例７と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６７】
（比較例８）
ポリプロピレン系樹脂（ＭＩ＝１．５、ＤＳＣでの結晶融解終了温度１６５℃）４０重量部と、ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）１０重量部、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）５０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）２２０重量部、水酸化アルミニウム（日本軽金属社製、商品名：Ｂ７０３Ｓ）１２０重量部、ジビニルベンゼン（和光純薬社製）１．５重量部、トリメチロールプロパントリメタクリレート（新中村化学社製）１重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、以下実施例７と同様にして架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６８】
（比較例９）
ポリプロピレン系樹脂（ＭＩ＝１．５、ＤＳＣでの結晶融解終了温度１６５℃）６０重量部と、ポリエチレン系樹脂（ＭＩ＝７．０、密度０．９２ｇ／ｃｍ^３ の線状低密度ポリエチレン）１０重量部、ポリエチレン系樹脂（ＭＩ＝３．４、密度０．９２ｇ／ｃｍ^３ の低密度ポリエチレン）１０重量部、エチレン−酢酸ビニル共重合体（酢酸ビニル含量１９％、ＭＩ＝２．５、密度０．９２ｇ／ｃｍ^３ ）２０重量部、ポリリン酸アンモニウム／トリス（２−ヒドロキシエチル）イソシアヌレート２成分混合系難燃剤（ヘキスト社製、商品名：ＨｏｓｔａｆｌａｍＡＰ７４５）４重量部、アゾジカルボンアミド（大塚化学社製）１０重量部とを混合し、ラボプラストミルを用いて温度１９０℃、回転数６０ｒｐｍにて５分間熔融混練しポリオレフィン系樹脂組成物を調製した。
この樹脂組成物を、温度１９０℃でプレスし、厚さ１．０ ｍｍ の発泡性シートを得た。この発泡性シートに電子線加速機を用いて吸収線量が３．０Ｍｒａｄに相当する線量を照射して樹脂を架橋させ、これを２４０℃の熱風式発泡炉で加熱して発泡させて、表面平滑な架橋樹脂発泡シートを得た。得られた発泡シートの性能は表２に示す。
【００６９】
【表２】

【００７０】
【発明の効果】
請求項１記載の本発明は、叙上の如く、マレイン酸成分を有するポリエチレン系樹脂５〜５０重量％を含むポリオレフィン系樹脂組成物が使用されているので、マレイン酸、無水マレイン酸の各成分の水素結合力、化学反応力によって該樹脂組成物中にポリリン酸アンモニウムと前記構造式で表される窒素含有化合物との２成分混合難燃剤が長期に保持され、ノンハロゲン難燃化による自己消火性の優れた難燃性ポリオレフィン系樹脂発泡体を提供できるのである。加えて、上記樹脂組成物とすることによって、発泡性シートの成形時の発泡剤の初期分解が阻止されるので、上記樹脂組成物の架橋反応と相まって、微細にして、且つ、均質な発泡構造を有する難燃性ポリオレフィン系樹脂発泡体を提供できるのである。
【００７１】
請求項２記載の本発明は、叙上の如く、ＤＳＣで示される結晶融解終了温度が１５５℃以下のポリプロピレン系樹脂５〜８５重量部とポリエチレン系樹脂９５〜１５重量部とからなるポリオレフィン系樹脂を使用することによって、該樹脂組成物から発泡性シート等の成形に際して、混練装置、成形装置における材料の均一な分散と、良好な練和、流動性により、発泡剤の初期分解が阻止され、上記樹脂組成物の架橋反応等と相まって、微細にして、且つ、均質な発泡構造を有し、表面の美麗な難燃性ポリオレフィン系樹脂発泡体を提供できるのである。[0001]
[Industrial applications]
The present invention relates to a flame-retardant polyolefin resin foam.
[0002]
[Prior art]
BACKGROUND ART Resin foams have excellent heat insulation properties and are used for building materials, transportation equipment such as automobiles, packaging materials, household goods, and a wide variety of other uses.
Above all, the demand for polyolefin-based resin foams is extremely large because of its excellent chemical stability and excellent properties such as heat insulation, electrical insulation, and light weight. However, with the expansion of uses of polyolefin resin foam, it is strongly required that the material be a flame retardant material, and a flame retarding treatment is performed by various methods.
[0003]
In recent years, as a method for making a polyolefin resin flame-retardant, a method of adding a halogen-containing compound has been generally used. These flame retardant treatments do have a flame retardant effect, and relatively little decrease in moldability and mechanical strength of molded products.However, a large amount of gas is generated during processing and combustion, causing corrosion of equipment. In addition, there is a strong demand for non-halogen flame retardant treatment from the viewpoint of safety.
[0004]
[Problems to be solved by the invention]
Under such circumstances, studies on resin flame retardation by adding hydrated metal oxides such as aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate that do not generate harmful gases during combustion are being actively conducted. Became.
However, in order to impart sufficient flame retardancy to a polyolefin resin that is flammable only with these hydrated metal oxides, a large amount of the hydrated metal oxides must be added, and as a result, The physical properties of the obtained foam are remarkably reduced, and the state of the foam is also affected, so that it is difficult to form a fine and uniform closed cell structure.
[0005]
Further, the flame retarding treatment disclosed in JP-A-63-61055 uses a two-component mixed flame retardant of ammonium polyphosphate and tris (2-hydroxyethyl) isocyanurate for a polyolefin resin. However, there is a short-term flame-retardant effect of the described resin composition, but there is a problem in the persistence of the effect, that is, a foam obtained from the resin composition is lined with a dew-prevention lining of a folded-plate roof. When the material is used under particularly high-temperature conditions, such as a material, the above-mentioned flame retardant bleeds out and cannot maintain a long-term flame-retardant effect.
[0006]
Furthermore, when the above-mentioned flame retardant is kneaded with a polyolefin-based resin, the foaming agent tends to undergo initial decomposition and has a problem in production technology that temperature control in the foaming step becomes difficult.
[0007]
JP-B-62-5788, JP-B-62-9135, and the like disclose that a polar group of maleic acid is introduced into a non-polar resin to increase affinity with a filler and improve mechanical strength. However, there is no suggestion to solve the above problems of the foaming agent.
[0008]
The present invention has been made in view of the above facts, and it is an object of the present invention to prevent the bleed out of a flame retardant when used under high temperature conditions, and to provide a long-term flame retardant. An object of the present invention is to provide a polyolefin-based resin foam having a fine and uniform foam structure and a beautiful appearance, which can maintain the activating effect.
[0009]
Claim2. The present invention described in 2.The purpose of this is to prevent the initial decomposition of the foaming agent when producing polyolefin resin foam, secure various production processes, and maintain the long-term flame-retardant effect. An object of the present invention is to provide a polyolefin resin foam having a uniform appearance and a beautiful appearance.
[0010]
[Means for Solving the Problems]
The present invention according to claim 1 is a method for preparing a polyolefin resin containing 5 to 50% by weight of a polyethylene resin having a maleic acid component, based on 100 parts by weight of a polyolefin resin. A flame-retardant polyolefin-based resin foam obtained by crosslinking and foaming a resin composition containing 5-200 parts by weight of a component-mixed flame retardant and a pyrolytic organic foaming agent.CharacteristicIt is assumed that.
Embedded image

(Where R¹~ R³Represents hydrogen or a hydroxyalkyl group having 1 to 16 carbon atoms, a dihydroxyalkyl group, a hydroxyaryl group or a dihydroxyaryl group, respectively. )
[0011]
Claim2. The present invention described in 2.Is based on 100 parts by weight of a polyolefin-based resin composed of 5-85 parts by weight of a polypropylene-based resin having a crystal melting end temperature of 155 ° C. or less and 95 to 15 parts by weight of a polyethylene-based resin as indicated by differential scanning calorimetry (DSC). A flame-retardant polyolefin-based resin foam obtained by crosslinking and foaming a resin composition containing 5 to 200 parts by weight of the two-component mixed flame retardant according to claim 1 and a pyrolytic organic foaming agent.CharacteristicIt is assumed that.
[0012]
Claim2. The present invention described in 2.Is 5 to 85 parts by weight of a polypropylene resin and 95 to 15 parts by weight of a polyethylene resin.
[0013]
The polypropylene resin is not particularly limited, and may be a propylene homopolymer or a copolymer containing propylene as a main component, or a mixture thereof. Examples of the copolymer include an α-olefin copolymer containing a propylene component at 85% by weight or more. Examples of the α-olefin include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1-pentene and the like.
[0014]
The melt index (MI) of the polypropylene-based resin is measured under normal conditions of a temperature of 230 ° C. and a load of 2.16 kgf based on JIS K7210, and a value of 0.2 to 20 is preferably used. . If the MI is less than 0.2, there is a problem in appearance when forming a sheet, and if the MI exceeds 20, the heat resistance of the obtained foam becomes insufficient.
[0015]
Claim 2The polypropylene resin used in the present invention is appropriately selected from the polypropylene resins used in the present invention according to claim 1, as long as the crystal melting end temperature by DSC (Definitive Scanning Calorimetry) is 155 ° C. or less. used.
At this time, the crystal melting end temperature by DSC is completely different from the melting peak temperature of the resin, and is an index that accurately indicates the difficulty of the flow during molding of the thermoplastic resin.
Further, when the crystal melting end temperature exceeds 155 ° C., the problems in the production technology, such as the poor flow during the molding process, the initial decomposition of the foaming agent, and the difficulty in controlling the temperature in the foaming step are solved. You cannot do it.
[0016]
Claim 2When the polypropylene resin in the polyolefin resin composition of the present invention exceeds 85 parts by weight, the flexibility of the foam becomes insufficient. If the amount of the polypropylene-based resin contained in the polyolefin-based resin composition of the present invention is less than 5 parts by weight, the resulting foam has insufficient material strength.
[0017]
The polyethylene resin having a maleic acid component used in the present invention according to claim 1 is, for example, graft polymerization of maleic acid or maleic anhydride onto an ethylene-vinyl acetate copolymer or an ethylene-α-olefin copolymer. It may be a maleic acid derivative or a maleic anhydride derivative, or an ethylene-ethyl acrylate-maleic anhydride copolymer, an ethylene-methyl methacrylate-maleic anhydride copolymer, or the like.
[0018]
The polyethylene resin having the maleic acid component,Polyolefin resinContaining 5 to 50% by weight based on the total amount ofPolyolefin resinIf the amount is less than 5% by weight, the bleed out of the flame retardant cannot be suppressed, and it is difficult to secure long-term flame retardancy. If the amount exceeds 50% by weight, the moldability becomes difficult and the resulting foam Body appearance worsens.
[0019]
ClaimThe present invention as described in 1 and 2 aboveThe polyethylene resin used in (1) may be any of a homopolymer of ethylene (low density, medium density, high density), a copolymer containing ethylene as a main component, and a mixture thereof. Examples of the copolymer include an ethylene-α-olefin copolymer (linear low-density polyethylene) containing 80% by weight or more of an ethylene component, and an ethylene-vinyl acetate copolymer. In particular, linear low density polyethylene is preferred.
[0020]
The melt index (MI) of the polyethylene-based resin is measured under ordinary conditions of a temperature of 190 ° C. and a load of 2.16 kgf based on JIS K7210, and the MI is preferably 0.1 to 40. If the MI is less than 0.1, there is a problem in appearance when forming a coarse sheet of the polyolefin resin composition before foaming, and if the MI exceeds 10, the foam obtained after foaming has Material strength becomes insufficient.
[0021]
ClaimThe present invention as described in 1 and 2 aboveIn the above-mentioned two-component mixed flame retardant of ammonium polyphosphate / nitrogen-containing compound used in the above, ammonium polyphosphate has a degree of polymerization of phosphoric acid of 200 to 1,000, and its surface is difficult to water coated with a melamine-formaldehyde resin or the like. A soluble free-flowing powder is preferably used.
The nitrogen-containing compound is represented by the following structural formula.
Embedded image

(Where R¹~ R³Represents hydrogen or a hydroxyalkyl group having 1 to 16 carbon atoms, a dihydroxyalkyl group, a hydroxyaryl group or a dihydroxyaryl group, respectively. )
Specific examples of the nitrogen-containing compound include, for example, isocyanuric acid, mono (hydroxymethyl) isocyanurate, bis (hydroxymethyl) isocyanurate, tris (hydroxymethyl) isocyanurate, mono (dihydroxymethyl) isocyanurate, and bis (hydroxymethyl) isocyanurate. (Dihydroxymethyl) isocyanurate, tris (dihydroxymethyl) isocyanurate, mono (2-hydroxyethyl) isocyanurate, bis (2-hydroxyethyl) isocyanurate, tris (2-hydroxyethyl) isocyanurate, tris (1,2 -Dihydroxyethyl) isocyanurate, tris (3-hydroxypropyl) isocyanurate, tris (2,3-dihydroxypropyl) isocyanurate, tris (4-hydroxybutyl) isocyanate Rate, tris (3,4-dihydroxybutyl) isocyanurate, tris (8-hydroxyoctyl) isocyanurate, tris (4-hydroxyphenyl) isocyanurate, tris (2,4-dihydroxyphenyl) isocyanurate, tris (2 (3-dihydroxyphenyl) isocyanurate and the like.
[0022]
The mixing ratio of the two-component mixed flame retardant is preferably in a range of (ammonium polyphosphate) :( the nitrogen-containing compound) = 80 to 50% by weight: 20 to 50% by weight. The two-component mixed flame retardant is preferably added at a ratio of 5 to 200 parts by weight based on 100 parts by weight of the polyolefin resin. When the flammability is not sufficiently obtained and the added amount exceeds 200 parts by weight, the mechanical strength of the obtained foam is greatly reduced, and it is difficult to put it to practical use.
[0023]
ClaimThe present invention as described in 1 and 2 aboveIn addition to the above two-component mixed flame retardant, hydrated metal oxides such as aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate; metal oxides such as aluminum oxide, magnesium oxide, titanium oxide, and iron oxide; The use of a flame retardant aid such as phosphorus is permissible without departing from the spirit of the invention.
Of the flame retardant assistants, red phosphorus particles coated with a synthetic resin are preferably used from the viewpoint of moisture resistance, safety and the like.
[0024]
Although the amount of the flame retardant aid depends on the amount of the two-component mixed flame retardant used in the present invention, it is 100 parts by weight based on 100 parts by weight of the total amount of the polyolefin resin composition used in the present invention. The following is preferred. If the amount exceeds 100 parts by weight, the foaming properties are impaired, a fine and uniform foamed structure cannot be obtained, and the appearance and the mechanical strength deteriorate.
[0025]
ClaimThe present invention as described in 1 and 2 aboveThe polyolefin-based resin composition is cross-linked to obtain a viscosity necessary for withstanding foaming in a foaming step, and to improve the heat resistance of the obtained foam.
ClaimThe present invention as described in 1 and 2 aboveIn the above, as the method of crosslinking, any method may be employed, but a method of crosslinking by thermally decomposing a radical generator such as a peroxide mixed with a polyolefin resin, irradiation with ionizing radiation A crosslinking method, a method using silane crosslinking, and the like can be used.
[0026]
Examples of the radical generator include benzoyl peroxide, octanoyl peroxide, decanoyl peroxide, acetyl peroxide, t-butylperoxyisobutyrate, cumene hydroperoxide and the like.
Examples of the silane crosslinking agent include trimethoxyvinylsilane and triethoxyvinylsilane.
[0027]
ClaimThe present invention as described in 1 and 2 aboveIn the above, when the crosslinking is performed, a crosslinking aid is used when the proportion of the polyethylene resin in the polyolefin resin composition is 80% by weight or less.
The crosslinking assistant may be a polyfunctional monomer that causes a crosslinking reaction by ionizing radiation or a peroxide, and two or more of these may be used as a mixture. Representative examples of the crosslinking aid include aromatic or aliphatic compounds containing one or more vinyl groups or allyl groups in one molecule, and acryloyloxy or methacryloyloxy groups in one molecule. Compounds containing one or two or more compounds, specifically, for example, divinylbenzene, diallylbenzene, divinylnaphthalene, trimethylolpropane trimethacrylate, ethylvinylbenzene, 1,9-nonanediol dimethacrylate, 1- Nonane monomethacrylate, 1,6-hexanediol methacrylate, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,2-benzenedicarboxylic acid Diallyl ester, 1,3-benzenedicarboxylic acid dia Glycol ester, 1,4-benzene dicarboxylic acid diallyl esters and closely related homologs thereof and the like.
[0028]
The compounding amount of the crosslinking aid is 0.05 to 10 parts by weight, more preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the total amount of the resin composition, and depends on the use of the foam. Is set.
If the amount of the crosslinking aid is less than 0.05 part by weight, crosslinking is insufficient, so that a fine and uniform foamed structure cannot be obtained, and sufficient material strength at high temperatures cannot be obtained. If the compounding amount exceeds 10 parts by weight, the crosslink density of the resin composition becomes too large, which causes problems such as difficulty in molding a coarse sheet of the polyolefin resin composition before foaming.
[0029]
When the ratio of the polyethylene resin to the polyolefin resin composition exceeds 80% by weight, the crosslinking aid may not be used. This is due to the self-crosslinking property of the polyethylene-based resin, and sufficient crosslinking can be performed by using a crosslinking means such as ionizing radiation without a crosslinking aid.
[0030]
ClaimThe present invention as described in 1 and 2 aboveThe thermal decomposition type foaming agent used in the above has a decomposition temperature higher than the melting temperature of the polyolefin-based resin, as long as it generates a gas when heated to a temperature higher than the decomposition temperature, for example, Examples include azodicarbonamide, benzenesulfonylhydrazide, dinitrosopentamethylenetetramine, toluenesulfonylhydrazide, and 4,4-oxybis (benzenesulfonylhydrazide), and preferably azodicarbonamide and dinitrosopentamethylenetetramine.
[0031]
The amount of the thermal decomposition type foaming agent is generally about 1 to 40 parts by weight based on 100 parts by weight of the resin composition, and is set according to a desired expansion ratio.
[0032]
In the present invention according to claims 1 to 4, the polyolefin-based resin composition may contain, as necessary, a decomposition promoter for a foaming agent, a cell nucleus modifier, an antioxidant, a heat stabilizer, and metal damage prevention. Various additives such as a coloring agent, a coloring agent, an antistatic agent, and an inorganic filler can be blended.
[0033]
ClaimThe present invention as described in 1 and 2 aboveAt a temperature at which the pyrolytic foaming agent does not decompose, using a kneading device such as a single-screw extruder, a multi-screw extruder, a Banbury mixer, a kneader mixer, or two rolls, for each component of the polyolefin-based resin composition. The mixture is melt-kneaded at a temperature of about 150 to 170 ° C., and then formed into an appropriate shape, for example, a sheet. After the obtained sheet-like molded body is irradiated with ionizing radiation to crosslink the resin, for example, hot air, infrared rays, a metal bath, an oil bath, or the like, the melting temperature of the resin is equal to or higher than the decomposition temperature of the pyrolytic foaming agent. By heating to the above temperature, for example, 190 to 290 ° C., the resin is foamed by the decomposition gas of the foaming agent to obtain a crosslinked olefin resin foam sheet.
These irradiation and foaming steps may be performed continuously, or may be performed in a batch system.
[0034]
As the ionizing radiation, electron beams, X-rays, β-rays, γ-rays and the like are used. The irradiation dose is generally about 1 to 10 Mrad, and the dose is set according to a desired gel fraction.
[0035]
[Action]
As described above, in the present invention, since a polyolefin resin composition containing 5 to 50% by weight of a polyethylene resin having a maleic acid component is used, each component of maleic acid and maleic anhydride is used. A two-component mixed flame retardant of ammonium polyphosphate and a nitrogen-containing compound represented by the above structural formula is retained in the resin composition for a long time by the hydrogen bonding force and the chemical reaction force of the resin composition, and the self-extinguishing property by non-halogen flame retardant Thus, it is possible to provide a flame-retardant polyolefin resin foam excellent in the above. In addition, since the resin composition is used, the initial decomposition of the foaming agent at the time of molding the foamable sheet is prevented. It is possible to provide a flame-retardant polyolefin resin foam having a structure.
[0036]
Claim2. The present invention described in 2.As described above, by using a polyolefin-based resin comprising 5-85 parts by weight of a polypropylene-based resin having a crystal melting end temperature represented by DSC of 155 ° C. or less and 95 to 15 parts by weight of a polyethylene-based resin, In molding a foamable sheet or the like from the resin composition, the kneading device, uniform dispersion of the material in the molding device, good kneading and fluidity prevent the initial decomposition of the foaming agent, and a crosslinking reaction of the resin composition. Together with the above, it is possible to provide a flame-retardant polyolefin resin foam having a fine and homogeneous foam structure and a beautiful surface.
[0037]
【Example】
Hereinafter, Examples and Comparative Examples of the present invention will be described. In the examples, each test of combustion test, bleeding property, foaming state, initial decomposition, and appearance was measured and evaluated by the following methods.
In the present invention, the crystal melting end temperature by differential scanning calorimetry (DSC) is shown, and the measuring method is described below.
[0038]
1. Combustion test
It was measured in accordance with JIS D1201 (Test method for flammability of organic materials for automobile interior), and evaluated by its flammability classification.
2. Bleedability
A sample of 160 mm × 160 mm was collected from the obtained foamed sheet, left in an oven at 80 ° C. for 48 hours, cooled to room temperature, and visually inspected for bleed-out of the additive on the sheet surface. : No bleed-out, x: bleed-out.
[0039]
3. Foaming state
The cross section and the vertical section of the obtained foamed sheet are randomly set to 5 fields of view, and it is determined whether or not the bubble diameter is fine and uniform, and whether or not the state of the foam has an adverse effect on the appearance of the sheet. Observation was made by visual observation, and the evaluation was made in two stages: ○: good, ×: bad.
[0040]
4. Initial decomposition
The cross-section and the vertical cross-section of the obtained foamable sheet were randomly set at five fields of view, and the presence or absence of initial decomposition of the foaming agent was visually observed. evaluated.
[0041]
5. appearance
The surface state of the obtained foamed sheet was visually observed comprehensively on the surface smoothness, the degree of discoloration, and the like, and evaluated on a two-point scale of 、: good and ×: poor.
[0042]
6. Crystal melting end temperature
About 10 mg of a polyethylene-based resin sample was placed in an aluminum pan, and the sample was once melted with a differential scanning calorimeter (manufactured by Seiko Instruments Inc., Model SSC5200). After cooling, the temperature was measured at a rate of 5 ° C./min.
[0043]
(Example 1 = invention described in claim 1)
70 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³Of low-density polyethylene), 15 parts by weight of maleic acid-grafted polyolefin resin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Admer NF300, MI = 1.3, density 0.94 g / cm)³15 parts by weight, 150 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate binary flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), 1 part by weight of divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.) Was mixed with 1.5 parts by weight of trimethylolpropane trimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.). For 5 minutes to prepare a polyolefin-based resin composition.
[0044]
This resin composition was pressed at a temperature of 170 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. The foamed sheet is irradiated with a dose corresponding to an absorption dose of 3.0 Mrad using an electron beam accelerator to crosslink the resin, and this is heated in a hot-air foaming furnace at 240 ° C. to foam the resin, and the surface is smoothed. A crosslinked resin foam sheet was obtained. Table 1 shows the performance of the obtained foam sheet.
[0045]
(Example 2 = invention according to claim 1)
50 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 3.4, density 0.92 g / cm)³Low-density polyethylene) 47.5 parts by weight, ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³) 2.5 parts by weight, 40 parts by weight of a two-component mixed flame retardant of ammonium polyphosphate (manufactured by Hoechst, trade name: Hostaflam AP462) and isocyanuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), trimethylolpropane trimethacrylate ( 1 part by weight of Shin-Nakamura Chemical Co., Ltd., 1.5 parts by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co.), and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) A crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0046]
(Example 3 = Invention according to claim 1)
40 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³54 parts by weight of a linear low-density polyethylene), maleic acid-grafted polyolefin resin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Admer NF300, MI = 1.3, density 0.94 g / cm)³3) parts by weight, ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³), 3 parts by weight, 5 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate two-component mixed flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd., trade name: B703S) 30 parts by weight, red phosphorus (manufactured by Rin Kagaku Co., Ltd., trade name: Nova Red 120) 5 parts by weight, divinylbenzene (manufactured by Wako Pure Chemical Industries) 1 part by weight, trimethylolpropane trimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) One part by weight, 1 part by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) were mixed, and the surface was smoothed in the same manner as in Example 1. A crosslinked resin foam sheet was obtained. Table 1 shows the performance of the obtained foam sheet.
[0047]
(Example 4 = Invention according to claim 1)
Polyethylene resin (MI = 3.4, density 0.92 g / cm³Of low-density polyethylene) and maleic acid-grafted polyolefin resin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Admer NF300, MI = 1.3, density 0.94 g / cm)³) 15 parts by weight, ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³5 parts by weight, 30 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate binary flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) Were melt-kneaded for 5 minutes at a temperature of 140 ° C. and a rotation speed of 60 rpm using a Labo Plastomill to prepare a polyolefin-based resin composition.
[0048]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0049]
(Example 5 = Invention according to claim 1)
Polyethylene resin (MI = 3.4, density 0.92 g / cm³Low-density polyethylene) and 70 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³) 20 parts by weight, ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³10 parts by weight, 50 parts by weight of a two-component mixed flame retardant of ammonium polyphosphate (manufactured by Hoechst, trade name: Hostaflam AP462) and isocyanuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), red phosphorus (manufactured by Rin Chemical Co., Ltd.) Product name: Novaled 120) 10 parts by weight and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) are mixed and melt-kneaded using a Labo Plastomill at a temperature of 140 ° C. and a rotation speed of 60 rpm for 5 minutes to obtain a polyolefin-based product. A resin composition was prepared.
[0050]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0051]
(Example 6 = Invention according to claim 1)
Polyethylene resin (MI = 7.0, density 0.92 g / cm³Of low-density linear polyethylene) and an ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³), 80 parts by weight, maleic acid-grafted polyolefin resin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Admer NF300, MI = 1.3, density 0.94 g / cm)³) 10 parts by weight, 80 parts by weight of ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate two-component mixed flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd., trade name: B703S) 80 parts by weight and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) are mixed and melt-kneaded using a Labo Plastomill at a temperature of 140 ° C. and a rotation speed of 60 rpm for 5 minutes to prepare a polyolefin resin composition. did.
[0052]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0053]
(Comparative Example 1)
60 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³Of linear low density polyethylene), 1 part by weight of divinylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.), 0.5 part by weight of trimethylolpropane trimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), 1,9-nonanediol dimethacrylate 1 part by weight (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) were mixed, and a crosslinked resin foam sheet was obtained in the same manner as in Example 1 below. Table 1 shows the performance of the obtained foam sheet.
[0054]
(Comparative Example 2)
Polyethylene resin (MI = 3.4, density 0.92 g / cm³Of low-density polyethylene) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) and melt-kneaded using a Labo Plastomill at a temperature of 140 ° C. and a rotation speed of 60 rpm for 5 minutes to obtain a polyolefin resin composition. Was prepared.
[0055]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0056]
(Comparative Example 3)
30 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³Of low-density polyethylene), 3 parts by weight of ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate binary flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), divinylbenzene (Wako Pure Chemical Industries, Ltd.) 1 part by weight, 1.5 parts by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) Similarly, a crosslinked resin foam sheet was obtained. Table 1 shows the performance of the obtained foam sheet.
[0057]
(Comparative Example 4)
Polyethylene resin (MI = 3.4, density 0.92 g / cm³Of low density polyethylene) and maleic acid-grafted polyolefin resin (manufactured by Mitsui Petrochemical Co., Ltd., trade name: Admer NF300, MI = 1.3, density 0.94 g / cm)³) 50 parts by weight, ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³) 25 parts by weight, 30 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate two-component mixed flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) Were melt-kneaded for 5 minutes at a temperature of 140 ° C. and a rotation speed of 60 rpm using a Labo Plastomill to prepare a polyolefin-based resin composition.
[0058]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0059]
(Comparative Example 5)
70 parts by weight of a polypropylene resin (MI = 1.5) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³29 parts by weight of ethylene-methyl methacrylate-maleic anhydride copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondyne TX8030, MI = 3, density 0.94 g / cm)³) 1 part by weight, 50 parts by weight of a two-component mixed flame retardant of ammonium polyphosphate (manufactured by Hoechst, trade name: Hostaflam AP462) and isocyanuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), trimethylolpropane trimethacrylate (Shinnakamura) 1.5 parts by weight, manufactured by Chemical Co., Ltd., 1 part by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) were mixed. In the same manner as described above, a crosslinked resin foam sheet was obtained. Table 1 shows the performance of the obtained foam sheet.
[0060]
(Comparative Example 6)
Polyethylene resin (MI = 7.0, density 0.92 g / cm³30 parts by weight of a linear low-density polyethylene) and an ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³) 70 parts by weight, 300 parts by weight of an equal weight two-component mixed flame retardant of ammonium polyphosphate (manufactured by Hoechst, trade name: Hostaflam AP462) and isocyanuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd.) 120 parts by weight of B703S) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) are mixed and melt-kneaded using a Labo Plastomill at a temperature of 140 ° C. and a rotation speed of 60 rpm for 5 minutes to obtain a polyolefin resin. A composition was prepared.
[0061]
This resin composition was pressed at a temperature of 140 ° C. to obtain a foamable sheet having a thickness of 1.0 mm. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. Table 1 shows the performance of the obtained foam sheet.
[0062]
[Table 1]

[0063]
(Example 7 = Invention according to claim 2)
70 parts by weight of a polypropylene-based resin (MI = 1.2, temperature at which crystal dissolution is completed by DSC at 152 ° C.) and a polyethylene-based resin (MI = 7.0, density 0.92 g / cm)³Of low-density polyethylene), 150 parts by weight of ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate binary flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), divinylbenzene (Wako Pure Chemical Industries, Ltd.) 1 part by weight), 1.5 parts by weight of trimethylolpropane trimethacrylate (manufactured by Shin-Nakamura Chemical), 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical), 10 parts by weight of trimellitic acid (manufactured by Wako Pure Chemical) The mixture was melt-kneaded and extruded at a temperature of 160 ° C. using a twin-screw extruder to obtain a foamable sheet having a thickness of 0.8 mm of the resin composition sheet. Thereafter, a crosslinked resin foam sheet having a smooth surface was obtained in the same manner as in Example 1. The performance of the obtained foam sheetTable 2Shown in
[0064]
(Example 8 = Invention according to claim 2)
80 parts by weight of a polypropylene-based resin (MI = 1.2, crystal melting end temperature in DSC: 152 ° C.) and a polyethylene-based resin (MI = 3.4, density: 0.92 g / cm)³Low-density polyethylene), 10 parts by weight, ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³10 parts by weight, 40 parts by weight of a 2-component mixed flame retardant of ammonium polyphosphate (manufactured by Hoechst, trade name: Hostaflam AP462) and isocyanuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), trimethylolpropane trimethacrylate (Shinnakamura) 1 part by weight, manufactured by Chemical Co., Ltd., 1.5 parts by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.)Example 7In the same manner as in the above, a crosslinked resin foam sheet having a smooth surface was obtained. The performance of the obtained foam sheetTable 2Shown in
[0065]
(Example 9 = Invention according to claim 2)
10 parts by weight of a polypropylene-based resin (MI = 1.2, temperature at which crystal dissolution is completed by DSC at 152 ° C.) and a polyethylene-based resin (MI = 7.0, density 0.92 g / cm)³90 parts by weight of a linear low-density polyethylene, 5 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate binary flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), aluminum hydroxide (Nippon Light Metal) (Product name: B703S) 30 parts by weight, red phosphorus (manufactured by Rin Kagaku Co., Ltd., product name: Nova Red 120) 5 parts by weight, divinylbenzene (manufactured by Wako Pure Chemical Industries) 1 part by weight, trimethylolpropane trimethacrylate ( 1 part by weight of Shin-Nakamura Chemical Co., 1 part by weight of 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.)Example 7In the same manner as in the above, a crosslinked resin foam sheet having a smooth surface was obtained. The performance of the obtained foam sheetTable 2Shown in
[0066]
(Comparative Example 7)
100 parts by weight of a polypropylene resin (MI = 1.5, 165 ° C. at the end of crystal melting by DSC) and a two-component mixed flame retardant of ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate (manufactured by Hoechst Co., Ltd.) Name: Hostaflam AP745) 30 parts by weight, divinylbenzene (manufactured by Wako Pure Chemical Industries) 1 part by weight, 1,9-nonanediol dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) 2 parts by weight, azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) 10 Parts by weight and mix belowExample 7In the same manner as described above, a crosslinked resin foam sheet was obtained. The performance of the obtained foam sheetTable 2Shown in
[0067]
(Comparative Example 8)
40 parts by weight of a polypropylene-based resin (MI = 1.5, crystal melting end temperature in DSC at 165 ° C.) and a polyethylene-based resin (MI = 3.4, density 0.92 g / cm)³Low-density polyethylene), 10 parts by weight, ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³) 50 parts by weight, 220 parts by weight of an ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate two-component mixed flame retardant (manufactured by Hoechst, trade name: Hostaflam AP745), aluminum hydroxide (manufactured by Nippon Light Metal Co., Ltd., trade name: B703S) 120 parts by weight, 1.5 parts by weight of divinylbenzene (manufactured by Wako Pure Chemical Industries), 1 part by weight of trimethylolpropane trimethacrylate (manufactured by Shin-Nakamura Chemical), 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical). Mix the followingExample 7In the same manner as described above, a crosslinked resin foam sheet was obtained. The performance of the obtained foam sheetTable 2Shown in
[0068]
(Comparative Example 9)
60 parts by weight of a polypropylene resin (MI = 1.5, 165 ° C. at the end of crystal melting by DSC) and a polyethylene resin (MI = 7.0, density 0.92 g / cm)³10 parts by weight of polyethylene low-density polyethylene, polyethylene resin (MI = 3.4, density 0.92 g / cm)³Low-density polyethylene), 10 parts by weight, ethylene-vinyl acetate copolymer (vinyl acetate content 19%, MI = 2.5, density 0.92 g / cm)³20 parts by weight, 4 parts by weight of ammonium polyphosphate / tris (2-hydroxyethyl) isocyanurate two-component mixed flame retardant (manufactured by Hoechst Co., Ltd., trade name: Hostaflam AP745), 10 parts by weight of azodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) Mixed withUsing a Labo Plastomill, the mixture was melt-kneaded at a temperature of 190 ° C. and a rotation speed of 60 rpm for 5 minutes to prepare a polyolefin resin composition.
This resin composition was pressed at a temperature of 190 ° C. to a thickness of 1.0 mm Was obtained. The foamed sheet is irradiated with a dose corresponding to an absorption dose of 3.0 Mrad using an electron beam accelerator to crosslink the resin, and this is heated in a hot-air foaming furnace at 240 ° C. to foam the resin, and the surface is smoothed. A crosslinked resin foam sheet was obtained.The performance of the obtained foam sheetTable 2Shown in
[0069]
[Table 2]

[0070]
【The invention's effect】
As described above, in the present invention, since a polyolefin resin composition containing 5 to 50% by weight of a polyethylene resin having a maleic acid component is used, each component of maleic acid and maleic anhydride is used. A two-component mixed flame retardant of ammonium polyphosphate and a nitrogen-containing compound represented by the above structural formula is retained in the resin composition for a long time by the hydrogen bonding force and the chemical reaction force of the resin composition, and the self-extinguishing property by non-halogen flame retardant Thus, it is possible to provide a flame-retardant polyolefin resin foam excellent in the above. In addition, the use of the above resin composition prevents the initial decomposition of the foaming agent at the time of molding the foamable sheet. Thus, it is possible to provide a flame-retardant polyolefin-based resin foam having:
[0071]
Claim2. The present invention described in 2.As described above, by using a polyolefin-based resin comprising 5-85 parts by weight of a polypropylene-based resin having a crystal melting end temperature represented by DSC of 155 ° C. or less and 95 to 15 parts by weight of a polyethylene-based resin, In molding a foamable sheet or the like from the resin composition, the kneading device, uniform dispersion of the material in the molding device, good kneading and fluidity prevent the initial decomposition of the foaming agent, and a crosslinking reaction of the resin composition. Together with the above, it is possible to provide a flame-retardant polyolefin resin foam having a fine and homogeneous foam structure and a beautiful surface.

Claims (2)

100 parts by weight of a polyolefin resin containing 5 to 50% by weight of a polyethylene resin having a maleic acid component, 5 to 200 parts by weight of a two-component mixed flame retardant of ammonium polyphosphate and a nitrogen-containing compound represented by the following structural formula And a flame-retardant polyolefin resin foam obtained by crosslinking and foaming a resin composition containing a thermal decomposition type organic foaming agent.

(In the formula, R ^{1 to} R ³ each represent hydrogen or a hydroxyalkyl group having 1 to 16 carbon atoms, a dihydroxyalkyl group, a hydroxyaryl group or a dihydroxyaryl group.) Claims are based on 100 parts by weight of a polyolefin-based resin comprising 5-85 parts by weight of a polypropylene-based resin having a crystal melting end temperature of 155 ° C. or less and 95 to 15 parts by weight of a polyethylene-based resin as indicated by differential scanning calorimetry (DSC). A flame-retardant polyolefin-based resin foam obtained by crosslinking and foaming a resin composition containing 5-200 parts by weight of the two-component mixed flame retardant according to 1 and a pyrolytic organic foaming agent.