JP3597260B2 - Laminate - Google Patents

Description

【０００１】
【発明の属する技術分野】
本発明は、特定の無架橋ポリオレフィン系樹脂発泡粒子の発泡成形体と不飽和ポリエステル樹脂との積層体に関するものである。
【０００２】
【従来の技術】
合成樹脂の発泡成形体を芯材とし、その表面に不飽和ポリエステル樹脂を被覆した積層体は良く知られている。このような積層体は、強度、軽量性、断熱性、遮音性等に優れており、板状や容器状等の形で浴槽、魚槽、建材等に広く利用されている。
従来、発泡成形体と不飽和ポリエステル樹脂との積層体を製造する方法として、芯材に使われる発泡成形体の表面を不飽和ポリエステル樹脂層で被覆し、硬化させる方法が知られている。この場合、芯材用の発泡成形体には接着性が良い硬質ポリウレタンフォームがよく使われる。しかし、このものは原料樹脂が高価な上に発泡成形作業が複雑かつ高コストであるし、ユニットバス等に該積層体を使うと芯材が加水分解し易い等の欠点もある。
【０００３】
ところで、前記の芯材用発泡成形体にポリスチレン樹脂発泡粒子の型内発泡成形体の使用も考えられるが、これは極めて困難である。その理由は、硬化前の不飽和ポリエステル樹脂に含まれている架橋用ビニルモノマー（スチレン、ビニルトルエン、メチルメタクリレート等）に、ポリスチレン樹脂発泡粒子の型内発泡成形体が溶けるためである。
前記ポリスチレン樹脂発泡粒子の型内発泡成形体を芯材とする際の欠点を直すために、ポリエチレン粒子５０〜４００重量部にスチレンモノマー１００重量部を含浸重合させた改質ポリスチレン樹脂からなる発泡粒子の型内発泡成形体を芯材にすることが、特公昭５９−４０６２２号公報に開示されている。しかし、該改質ポリスチレン樹脂発泡粒子の型内発泡成形体を芯材にすると、不飽和ポリエステル樹脂を積層する際の８０〜１２０℃の熱で界面に空隙が発生する。このほか、▲１▼表面層を形成する不飽和ポリエステル層にピンホールを生じる、▲２▼芯材の発泡成形体と不飽和ポリエステル樹脂との接着力が弱い、▲３▼発泡成形体の一部が溶ける、▲４▼製品の強制養生が困難等の欠点も認められる。
【０００４】
前記の諸問題を解決するために、抽出残渣率７０％以上の変性ポリオレフィン樹脂を原料にする芯材が提案されている（特開昭６２−１９０２３６号公報）。この芯材は、１０〜３０重量％のスチレンやメタクリル酸メチルでグラフト変性された架橋ポリオレフィン樹脂を原料にしており、１００℃でも熱収縮率が５％以下にすぎないために前記諸問題が解決されている。しかし、該芯材は架橋樹脂を原料にするためにコスト高であり、低価格とするために無架橋樹脂を使うと不飽和ポリエステル樹脂との積層界面の芯材側が収縮する等の問題が起る。
本発明者らは、前記の諸問題を解決するために、グラフト変性されたポリオレフィン系樹脂発泡粒子の型内発泡成形体を芯材とする方法を開発し、特許を出願した（特願平６−７２９１３号）。この芯材は、無水マレイン酸等の不飽和ジカルボン酸系グラフト化剤で変性されたポリオレフィン系樹脂の発泡粒子を型内成形した芯材であり、該グラフト化剤は少量しか使わなくても大きな効果を示すために、芯材と不飽和ポリエステル樹脂との接着性が高い上に芯材の機械的強度も大きく、不飽和ポリエステル樹脂と芯材との積層界面の芯材側が収縮する等の問題もない芯材である。しかし、この芯材は発泡粒子間の融着性に多少の問題を残しており、改良の余地を残すものであった。
【０００５】
【発明が解決しようとする課題】
本発明は、従来技術に見られる前記の諸問題を解決し、発泡粒子間の融着性が良い上に、接着性が高く、さらに積層時や積層後の収縮率も少ない発泡成形体と、不飽和ポリエステル樹脂との積層体を提供することをその課題とする。
【０００６】
【課題を解決するための手段】
本発明者らは、前記課題を解決すべく鋭意研究を重ねた結果、本発明を完成するに至った。
すなわち、本発明によれば、ポリオレフィンと、側鎖にビニル結合を持つポリエン重合体との混合樹脂を基材樹脂とする無架橋ポリオレフィン系樹脂発泡粒子を型内で成形してなる発泡成形体と、不飽和ポリエステル樹脂とを積層一体化してなることを特徴とする積層体が提供される。
【０００７】
本明細書において、「無架橋ポリオレフィン系樹脂発泡粒子」という用語の定義は以下の通りである。
ポリオレフィンとポリエン重合体との混合樹脂を基材としている発泡粒子を試料とし、これを沸騰キシレン中に８時間浸漬後、標準網フルイを規定しているＪＩＳ Ｚ ８８０１（１９６６年）に定められている７４μの金網で速やかに濾過し、該金網上に残った沸騰キシレン不溶分の重量を測定する。この不溶分の割合が試料の１重量％以下の場合を無架橋ポリオレフィン系樹脂発泡粒子と言う。不溶分の含有率ｐ（％）を式で表すと下式の通りである。
Ｐ（％）＝（Ｍ／Ｌ）×１００
Ｍ：不溶分の重量（ｇ） Ｌ：試料の重量（ｇ）
尚、上記不溶分は、発泡粒子の基材樹脂である発泡前の混合樹脂粒子を使用して同様に測定しても、或いは発泡粒子から得られる発泡成形体（ただし、他の素材との積層前）を同様に測定しても実質的に同一の値が得られる。また、他の素材との積層後の発泡成形体であっても、測定サンプル中に他の素材が混入することがなければ発泡粒子の測定値と実質的に同一の値が得られるし、また他の素材から充分離れた箇所を測定しても同じ結果が得られる。
【０００８】
【発明の実施の形態】
本発明者らは、前記特願平６−７２９１３号に示されているグラフト変性樹脂より優れた樹脂を得るために、無架橋ポリオレフィンに別の素材を添加・混練した混合樹脂を基材とする発泡粒子を作製し、その組成と発泡粒子性能との関係について試行錯誤的に研究を進めた。その結果、１，２−ポリブタジエン等の無架橋ポリエン重合体を含む混合樹脂を基材とする発泡粒子の型内発泡成形体は、発泡粒子間の融着性を低下させずに熱硬化性樹脂等との接着性（以下、単に接着性とも言う）が高くなることが分った。一方、この性質は無架橋ポリオレフィンと無架橋１，４−ポリブタジエンとの混合樹脂を基材とする発泡粒子では見られなかったから、この性質は１，２−ポリブタジエンの側鎖、すなわちビニル結合を持つ側鎖によるものと推定された。本発明は、この知見に基づいてなされたものである。なお、発泡粒子を構成する樹脂中にビニル結合性側鎖を持つポリエン重合体が含まれているか否かは、後記する示差走査熱量測定で容易に確認される。
【０００９】
本発明の発泡粒子製造に使われる基材樹脂としては、１種又は２種以上の無架橋ポリオレフィンと１種又は２種以上の無架橋ポリエン重合体との混合樹脂が使用される。混合樹脂中の無架橋ポリエン重合体の混合比は２〜５０重量％、好ましくは５〜４５重量％であり、混合比過少では発泡成形体と不飽和ポリエステル樹脂等の熱硬化性樹脂との接着性向上効果が認められず、混合比過大の場合は発泡粒子を型内成形する際の成形温度範囲が狭くなる等の問題がある。
前記の熱硬化性樹脂との接着性向上効果は側鎖の鎖長が短いほど大きいから、ここで使われる無架橋ポリエン重合体の側鎖としてはビニル基が好適である。そして、ビニル基を側鎖にすると該ポリエン重合体中で前記の接着性向上に効果を示す側鎖二重結合の密度が高くなるから、この点からもビニル基を側鎖に持つポリエン重合体を使うのが望ましい。
【００１０】
前記の無架橋ポリエン重合体は、分子内に２個以上の二重結合を持つ不飽和炭化水素を原料とし、側鎖にビニル結合が形成されるように重合させた重合体である。モノマーには炭素数４〜１２、好ましくは４〜６の低級炭化水素が使われ、ブタジエン、ペンタジエン、ヘキサジエン、ヘキサトリエン、シクロペンタジエン、シクロヘキサジエン等の使用が一般的であるが、特にブタジエンが好ましい。これらのモノマーを単独又は２種以上混合して、或いはエチレンやプロピレン等の低級オレフィンと混合して公知の方法で重合させれば良く、通常は単一重合体が使われる。従って、本発明の樹脂発泡粒子の基材に添加される無架橋ポリエン重合体としては無架橋１，２−ポリブタジエンが最適である。
前記の無架橋ポリエン重合体が融点を示す場合は、その融点が混合樹脂中の無架橋ポリオレフィン重合体の融点以下であるのが望ましい。また、無架橋ポリエン重合体のメルトフローインデックス（以下、ＭＦＩと略記する）は０．１〜１３ｇ／１０分が好ましく、０．５〜５ｇ／１０分であればより好ましい。
【００１１】
前記樹脂発泡粒子の基材となる混合樹脂に含まれる無架橋ポリオレフィンの融点は、１００〜１８０℃、好ましくは１１０〜１６０℃で、ＭＦＩは０．１〜１００ｇ／１０分、好ましくは１〜５０ｇ／１０分である。融点が低すぎると、不飽和ポリエステル樹脂等を積層させる際の熱に耐えられず、得られた積層体の耐熱性も低下する。また、融点が高すぎると発泡体製造コストの上昇や発泡倍率低下等の問題を生じる。そして、ＭＦＩが低すぎると良好な発泡倍率で発泡粒子を得るのが困難になり、高すぎると発泡自体が困難になる。
前記の無架橋ポリオレフィンを具体的に示すと、▲１▼高密度ポリエチレン▲２▼直鎖状低密度ポリエチレン▲３▼ポリプロピレン▲４▼プロピレン−オレフィンランダム共重合体▲５▼プロピレン−オレフィンブロック共重合体等が挙げられる。なお、前記の▲２▼はα−オレフィン含有率０．５〜１０重量％程度のエチレン−α−オレフィンランダム共重合体、▲４▼はα−オレフィン含有率０．５〜１０重量％程度のランダム共重合体、▲５▼はα−オレフィン含有率０．５〜３０重量％程度のブロック共重合体であり、これら共重合体中のα−オレフィンの炭素数は１０以下である。
【００１２】
前記の発泡粒子基材に使われる無架橋ポリオレフィンのうち、特に好ましい重合体はプロピレン系ランダム共重合体である。この理由は、該共重合体と無架橋ポリエン重合体とを混合して得られる混合樹脂を基材にすると、生成した発泡粒子が高発泡状態でも不飽和ポリエステル樹脂と良く接着するからである。
以上のほか、発泡粒子の基材となる混合樹脂中には第３の重合体が添加されていても良い。この場合、第３の重合体の添加量は混合樹脂の３０重量％以下、好ましくは１０重量％程度とするのが良い。ただし、第３の重合体が添加されていても、混合樹脂中の無架橋ポリオレフィン含有率を５０重量％以上にすることが必要である。なお、第３の重合体としては、合成ゴム、ポリエステル、１又は２個のハロゲン原子を繰り返し構造単位に含むハロゲン化ビニル重合体、セルロース誘導体系重合体、アクリル酸誘導体系重合体等が例示される。
【００１３】
発泡粒子の基材用混合樹脂は、その混合比で得られる発泡粒子の機械的強度や接着性及び融着性を制御することができる。また、接着性と機械的強度とは二律背反の関係にあり、一方を充分大きくすると他方が低下するから発泡粒子の使用目的によって樹脂の混合比を変えるのが良い。しかし、本発明の発泡粒子を発泡成形体とした場合は、従来のポリオレフィン系樹脂発泡粒子より接着性を高めた場合の機械的強度（発泡粒子間の融着性に起因する強度を含む）低下率が低いから、この発泡粒子は積層体形成用発泡粒子として従来品より好ましいと言える。前記の混合樹脂は押し出し機内に入れて溶融・混練し、該溶融・混練物をストランド状に押し出してから冷却後に切断してペレット状とし、これに発泡粒子製造用密閉容器内で発泡剤を含浸後に低圧部に放出し、得られた発泡粒子を金型内で加熱成形すれば成形体が得られる。なお、自明のことであるが、押し出し成形物（ストランド）の切断は混合樹脂が冷える前でも後でも良いし、ペレットの大きさは通常の樹脂発泡体製造時に行なわれている範囲であれば限定されない。
【００１４】
混合樹脂の発泡は、水等の分散媒に分散させた前記ペレットと発泡剤を密閉容器内に入れ、該ペレットの軟化温度以上に加熱して混合樹脂内に発泡剤を含浸させてから、密閉容器の一端を開けてペレットと水を低圧部に放出させる常法で行えば良い。なお、前記の樹脂軟化温度はＡＳＴＭ−Ｄ−６４８に規定されている軟化温度であり、荷重４．６Ｋｇ／ｃｍ^２の条件で測定される軟化温度である。発泡剤には、プロパン、ブタン、ペンタン、ヘキサン、シクロブタン、シクロヘキサン、トリクロルフロルメタン、ジクロルジフロルメタン、クロルフロルメタン、トリフロルメタン、１，１−ジフロルエタン、１−クロル−１，１−ジフロルエタン、１，２，２，２−テトラフロルエタン、１−クロル−１，２，２，２−テトラフロルエタン等の揮発性発泡剤、又は窒素、空気、二酸化炭素、アルゴン等の無機ガス系発泡剤が使われるが、環境面で問題がなく安価な空気等の無機ガス系発泡剤が好ましい。また、発泡剤使用量は一般に樹脂使用量の２〜５０重量％であり、発泡倍率や発泡温度を考慮して前記範囲内で適宜定めれば良い。
【００１５】
混合樹脂ペレットの分散媒は、該混合樹脂を溶解しない水、エチレングリコール、グリセリン、メタノール、エタノール等の液体であり、その使用量は一般に混合樹脂ペレット重量の１．５〜１０倍、好ましくは２〜５倍である。また、通常は分散媒として水が使われる。
混合樹脂ペレットを分散媒に分散させ、加熱下に発泡剤を該樹脂ペレットに含浸させる際には、混合樹脂ペレットの相互融着を防ぐために融着防止剤が使われる。融着防止剤は分散媒に不溶な無機系又は有機系の高融点物であり、平均粒径０．００１〜７０μｍ、好ましくは０．００１〜３０μｍの微粉体である。そして、通常の発泡体製造時には、カオリン、タルク、マイカ、アルミナ、チタニア、水酸化アルミニウム等の無機系融着防止剤が使われる。また、融着防止剤の添加量は混合樹脂ペレット使用量の０．０１〜１０重量％程度が望ましい。
前記の融着防止剤添加の際は、ドデシルベンゼンスルホン酸ナトリウムやオレイン酸ナトリウム等のアニオン系界面活性剤を分散助剤とするのが好ましく、その添加量は混合樹脂ペレット使用量の０．００１〜５重量％程度が望ましい。
【００１６】
本発明では、無架橋ポリオレフィンと特定の無架橋ポリエン重合体との混合樹脂を基材として発泡粒子を得ており、無架橋樹脂を原料にして樹脂発泡体を製造する場合には、該樹脂に二次結晶があると型内成形性に優れた発泡粒子が得られることが知られている。そして、樹脂中に二次結晶が存在するか否かは、該樹脂から得られる発泡粒子のＤＳＣ曲線に現れる高温ピークの有無で判定され、該ピークがあれば二次結晶が存在し、無ければ二次結晶が存在しない。ここで高温ピークとは、樹脂の融解に伴う吸熱ピーク（固有ピーク）より高温側に出現する吸熱ピークである。また、前記のように、ビニル結合性側鎖を持つ無架橋ポリエン重合体の存在は、ＤＳＣ曲線の高温ピークより高温側に発熱ピークが存在するか否かで判定される。これらの判定に使われるＤＳＣ曲線は、以下のようにして求めることができる。
【００１７】
１〜５ｍｇの発泡粒子を、１０℃／分の速度で室温から２２０℃まで昇温させてＤＳＣ曲線を得、同速度で４０℃付近まで降温後に前記と同じ条件で２回目のＤＳＣ曲線を求めれば、固有ピークは１回目と２回目で５℃未満、通常は２℃未満の頂点温度差で出現し、二次結晶がある場合には１回目のＤＳＣ曲線に高温ピークが現れ、２回目のＤＳＣ曲線にはこれが現れない。一方、二次結晶がない場合には１回目のＤＳＣ曲線に高温ピークが現れないから、高温ピークの有無が分かる。なお、２回目のＤＳＣ曲線に現れる固有ピークの頂点温度と１回目の高温ピークのそれとの温度差は５℃以上、好ましくは１０℃以上が良い。
ビニル結合性側鎖を持つ無架橋ポリエン重合体が存在すると、１回目のＤＳＣ曲線（但し、前記のようにして５００℃まで昇温させて得られるＤＳＣ曲線）には高温ピークより高温側に発熱ピークが現れ、２回目のＤＳＣ曲線には該ピークが出現しないか、或いは発熱量が大きく減少したピークが現れる。従って、この１回目のＤＳＣ曲線（５００℃昇温）に現れる発熱ピークは無架橋ポリエン重合体中の側鎖ビニル結合が反応する際の反応熱によって出現するものと推定される。
本発明においては、上記発熱ピークの発熱量は、混合樹脂中のポリエン重合体の種類と量を総括的に示す指標となる。その発熱量は、発泡粒子（他の素材を積層する前の発泡成形体でも構わない）１ｇ当り１５〜４２０Ｊ（ジュール）が望ましい。その発熱量が１５Ｊ未満の場合には、発泡成形体と不飽和ポリエステル樹脂等の熱硬化性樹脂との接着性向上効果に劣り、また４２０Ｊを越える場合には、発泡粒子を型内成形する際の成形温度幅が狭くなる（この幅が狭くなると、発泡粒子間の融着性が不十分となったり、あるいは得られる発泡成形体が収縮しやすくなる。）等の問題が発生しやすくなる。従って、前記〔０００９〕で説明した混合樹脂中のポリエン重合体の混合比は、ポリエン重合体の種類に応じて、上記発熱量を考慮に入れて選択することが望ましいといえる。
尚、上記発熱量は、発泡粒子の基材樹脂である発泡前の混合樹脂粒子を使用して同様に測定しても、或いは発泡粒子から得られる発泡成形体（ただし、他の素材との積層前）を同様に使用しても実質的に同一の値が得られる。また、他の素材との積層後の発泡成形体であっても、測定サンプル中に他の素材が混入することがなければ発泡粒子の測定値と実質的に同一の値が得られるし、また他の素材から充分離れた箇所を測定しても同じ結果が得られる。
【００１８】
発泡粒子の基材となる混合樹脂は、使用する発泡剤とその量によっても異なるが、その融点（上記２回目のＤＳＣ曲線に現れる固有ピークの頂点温度）より約２０℃低い温度とその融解終了温度との間の温度に５〜９０分間、好ましくは１５〜６０分間保つと混合樹脂内に二次結晶を形成させることができる。例えば、無機ガス系発泡剤を使う場合には、分散媒中に混合樹脂ペレットが分散されている密閉容器に無機ガス系発泡剤を加え、これを混合樹脂の融点とその補外融解終了温度（ＪＩＳ Ｋ７１２１に規定されている温度）との間の温度に保てば、混合樹脂ペレットに二次結晶を形成させることができる。そして、該密閉容器内容物を低圧部に放出すれば二次結晶を持つ発泡粒子が得られる。また、放出前の混合樹脂ペレット中に充分大量の二次結晶があれば、放出時の温度（発泡温度）が混合樹脂ペレットの補外融解終了温度以上であっても、前記高温ピークの頂点温度以下の場合には二次結晶の存在する型内成形性の良い発泡粒子が得られる。
【００１９】
最適発泡温度は、基材樹脂の種類並びに発泡剤の種類及び使用量で異なる。例えば、原料の無架橋ポリオレフィンに無架橋ポリプロピレン系樹脂を使って、無機ガス系発泡剤で発泡させる場合は、発泡温度を混合樹脂ペレットの融点より約５℃低温から約１５℃高温の範囲、好ましくは約３℃低温から約１０℃高温の範囲にするのが望ましい。そして、分散媒中の混合樹脂ペレットを発泡温度まで昇温させる際の昇温速度は１〜１０℃／分、好ましくは２〜５／℃分とするのが望ましい。なお、発泡させるために容器内容物を放出する際の低圧部は大気圧以下でも良いが、通常はコスト的に有利な大気圧下に放出される。
前記の方法で製造された発泡粒子は、平均気泡径が１０〜５００μｍ程度である。また、発泡粒子の嵩比重は発泡剤使用量等で異なるが０．００９〜０．３ｇ／ｃｍ^３程度である。
【００２０】
発泡粒子は、発泡体成形用金型内で基材樹脂の種類によって定まる適温に加熱して成形体にするが、本発明の発泡粒子のように無架橋樹脂を基材樹脂とする場合は、一般に発泡前の混合樹脂ペレット融点より１５℃低温の温度と該融点より１５℃高温の温度との間の任意の温度に加熱して成形体にする。そして、本発明の発泡粒子は粒子間の相互融着性が高いから、前記温度で丈夫な発泡成形体が得られる。また、該方法で成形された発泡成形体表面は薄い表皮に覆われて気泡が閉じているが、発泡成形体の不飽和ポリエステル樹脂との積層面の気泡が開放されていると、該部分に不飽和ポリエステル樹脂が浸入して発泡成形体と一体化するために、接着強度が大幅に上がる。従って、発泡成形体の樹脂積層面にある表皮をスライス等の方法で除けば、接着強度を大幅に上げることができる。この方法によれば、同一接着強度を得るのに必要なビニル結合性側鎖の量を減らすことができるから、基材樹脂中の無架橋ポリエン重合体の含有率低下が可能になり、コスト的に有利である。
【００２１】
ポリオレフィン系樹脂発泡粒子の型内発泡成形体を芯材とし、その表面に不飽和ポリエステル樹脂層を設けた樹脂発泡体／不飽和ポリエステル樹脂積層体は、従来公知の方法で製造することができる。例えば、レジンインジェクションモールディング法（レジントランスファーモールディング法）に従って所望形状の金型内に形状対応の発泡成形体を挿入後、金型の液注入口から液状の不飽和ポリエステル樹脂を注入し、発泡成形体の表面と金型内表面間の空隙部に不飽和ポリエステル樹脂液を充満させ、これを硬化させる方法で製造することができる。
前記の積層体製造時に、発泡成形体の表面と金型内表面間の空隙部にガラス繊維や炭素繊維等の補強材を入れて樹脂層を補強することもできる。また、積層用の不飽和ポリエステル樹脂液にはこの種の積層に使われる公知樹脂液を使えば良く、通常は硬化用触媒と不飽和ポリエステル樹脂を架橋用ビニルモノマーに溶解した液が使われる。なお、不飽和ポリエステルの硬化反応は発熱反応なので加熱は不要であるが、硬化反応終了後に金型を６０〜１００℃に５〜６０分間保持して硬化物を強制養生させても良く、強制養生で積層体の強度を更に高めることができる。そして、硬化終了後は積層体を金型から取出して製品とすれば良い。
以上のほか、本発明の積層体はハンドレイアップ法やスプレイアップ法で製造しても良い。これらの場合は、板状に成形された発泡成形体の片面又は両面に補強材を含む不飽和ポリエステル樹脂層を設け、これを硬化させれば良い。
【００２２】
本発明の発泡成形体は、熱融着法によって金属と積層させることもできる。ここで使われる金属は、鉄、アルミニウム、クロム、ニッケル、金、銀、銅、マグネシウム、亜鉛、錫、鉛、ステンレス、ブリキ等であるが、特に鉄、ステンレス、アルミニウム及び銅が好ましい。
金属との積層体を製造する場合は、前記のようにして得られた発泡成形体の両面又は片面に、厚さ０．０１〜５０ｍｍ、好ましくは０．０１〜１０ｍｍの金属箔又は金属板を重ね合せ、１００〜２００℃、好ましくは１２０〜１７０℃の温度及び３ｋｇ／ｃｍ^２以下、好ましくは０．５ｋｇ／ｃｍ^２以下の圧力下に、０．５〜５分間、好ましくは１〜３分間保持して熱融着させれば良い。なお、厚さ２０ｍｍ以下の金属板と積層させる場合には、金属板を発泡成形体を構成する混合樹脂の軟化点以上の温度に加熱し、これを直ちに発泡成形体の積層面に重ね合せて３０秒以上静置すれば、金属と発泡成形体との良好な積層体が得られる。
【００２３】
【実施例】
次に、本発明を実施例及び比較例によって更に具体的に説明するが、本発明はこの実施例によって限定されるものではない。なお、以下に示す部及び％はいずれも重量基準のものである。
【００２４】
実施例１〜６、比較例１〜３
（発泡粒子の原料に使う樹脂）
実施例及び比較例で発泡粒子の原料に使われる無架橋ポリオレフィン及び無架橋ポリエン重合体と、その記号を表１に示す。また、該樹脂の物性及び該樹脂をグラフト変性した樹脂（比較例で使用する）の物性、並びに変性剤の種類と変性度を表２に示すが、変性度は原料樹脂に対する変性剤使用比率として重量％で示してある。なお、表２に記載されているＭＦＩを測定する際の荷重は２．１６ｋｇｆ／ｃｍ^２で、温度は樹脂の種類がＰの場合は２３０℃、樹脂の種類がＲの場合は１９０℃、樹脂の種類がＳの場合は１５０℃である。
【表１】

【００２５】
【表２】

【００２６】
（発泡粒子の原料となる樹脂ペレットの製造）
表２に示した樹脂を単独又は混合して表３に示す組成の樹脂とし、これを押し出し機に入れて溶融・混練してからストランド状に押し出し、急冷後に切断して円柱状の樹脂ペレットを作製した。樹脂ペレットの大きさは、該ペレットが樹脂Ｐを主成分としている場合は平均重量が２ｍｇ／個、該ペレットが樹脂Ｒを主成分としている場合は平均重量が４ｍｇ／個となるようにした。実施例及び比較例で使用した樹脂ペレットの樹脂組成を表３に示す。
【００２７】
【表３】

【００２８】
（発泡粒子の製造）
樹脂ペレット１００部、水３００部、カオリン０．３部、ドデシルベンゼンスルホン酸ソーダ０．００４部、及び表４に示す量の二酸化炭素を密閉容器に仕込み、撹拌下に表４に示す温度で表４に示す時間だけ保持した。保持時間終了後、保持温度のまま容器の一端を解放して容器内容物を大気圧下に放出し、発泡粒子を得た。この放出時には、容器内圧力を維持するために高圧の二酸化炭素ガスを容器内に供給した。得られた発泡粒子の平均嵩倍率は表４に示した通りである。なお、表４の実施例１、２、７及び比較例１、２、３では保持時間と温度が二段で示されているが、これは上段の温度・時間に保持してから下段の温度・時間に保持したことを意味している。また、表４に示した発泡粒子のＤＳＣ曲線から求められた固有ピーク、高温ピーク及び発熱ピークの頂点温度を表５に示す。
【００２９】
【表４】

【００３０】
【表５】

【００３１】
（型内成形）
前記の発泡粒子を常温・常圧下に２４時間放置後、金型内に入れて表４に示す高圧水蒸気で加熱し、３００ｍｍ×３００ｍｍ×４０ｍｍの発泡成形体を作製した。該発泡成形体は、それを構成している樹脂の主成分がＰの場合には６０℃、Ｒの場合には８０℃のオーブン内で２４時間乾燥後に積層工程に送った。なお、型内成形後の成形体の発泡倍率及び該成形体内での発泡粒子の融着性は表４に併記した通りであり、融着性の評価は下記の方法で行った。
幅方向の垂直断面が、厚さ１０ｍｍ×幅５０ｍｍ×長さ１００ｍｍとなるように発泡成形体を切断し、ここに得られたスライス板を破断するまで長手方向に引張り、破断面を目視で観察して破断面における発泡粒子の融着部での破断個数の割合が４０％以下の場合を○、当該割合が４０％を超え６０％以下の場合を△、当該割合が６０％を超える場合を×で表した。
【００３２】
不飽和ポリエステル樹脂との積層）
前記の発泡成形体を５０ｍｍ×５０ｍｍ×１０ｍｍの大きさにカットし、片側の表面に表皮が形成され他の表面には開放気泡が露出しているサンプルを作製した。このサンプルの一方の表面（表６に示されている面）にガラス繊維製のチョップドストランドマットをのせ、その上から硬化触媒としてメチルエチルケトンパーオキサイドを含む不飽和ポリエステルをハンドレイアップ法によって積層・硬化させて積層体を作製した。なお、チョップドストランドマットは坪量４５０ｇ／ｍ^２で厚み２〜２．５ｍｍのものであり、不飽和ポリエステル樹脂は日本ユピカ（株）製のユピカ４００７Ａである。
【００３３】
発泡成形体の評価）
１．接着性
繊維強化不飽和ポリエステル樹脂硬化体（ＦＲＰ）が発泡成形体に積層されている前記サンプルを、ＦＲＰ側と発泡成形体側が破断するように引っ張り速度１０ｍｍ／分で破断させ、破断後のＦＲＰ側接着面に発泡成形体がどの程度付着しているかを観察した。すなわち、発泡成形体とＦＲＰの界面が破断するか発泡成形体の内部で破断が起るかを調べたのであり、該試験は引っ張り試験機で行った。そして、ＦＲＰ側に発泡成形体が大量に付着しているほどＦＲＰと発泡成形体の接着性が良いことになるから、ＦＲＰの接着面側表面の全面積の８０％以上に発泡成形体が付着している場合を◎、７０％以上で８０％未満に付着している場合を○、１０％以上で７０％未満に付着している場合を△、付着の割合が１０％未満の場合を×として評価結果を表６に示した。
２．発泡成形体にＦＲＰを積層させる際の収縮状況
前記のＦＲＰが積層されている積層体について、積層界面を真横から観察して積層時に発泡成形体が収縮する程度を調べた。そして、収縮が認められないものを○、わずかに収縮が認められるものを△、大きな収縮が認められるものを×として評価結果を表６に示した。
【００３４】
【表６】

【００３５】
表６から、実施例及び比較例の全部の積層体が発泡成形体とＦＲＰとの接着性は合格範囲にあると云える。これは、発泡成形体を構成している基材樹脂に、実施例では無架橋ポリオレフィンと無架橋ポリエン重合体との混合樹脂を使い、比較例ではグラフト変性された無架橋ポリオレフィン系樹脂を使っているためである。また、実施例６の積層体は表皮側への積層の場合には他の積層体より発泡成形体とＦＲＰとの接着性が多少悪いが、これは無架橋ポリエン重合体の含有率が少ないためである。しかし、開放気泡側への積層の場合にはその接着性は合格といえる。
実施例１と４及び２と５では、同じ発泡成形体に同じＦＲＰを積層させているが、発泡成形体とＦＲＰとの接着性は実施例４及び５の方が実施例１，２より明らかに高い。この理由は、実施例１，２の積層体では発泡成形体の表皮部分とＦＲＰとが接着しているのに、実施例４，５の積層体では発泡成形体の開泡気泡部分とＦＲＰとが接着しているためであり、開泡気泡部分にＦＲＰを積層させると接着性が向上することがはっきり認められる。
【００３６】
発泡成形体の収縮状況は、実施例の場合にはいずれも積層による収縮が全く認められないのに、比較例１、２の発泡成形体では大きな収縮が認められる。しかし、無水マレイン酸をグラフト化剤としている比較例３の発泡成形体ではＦＲＰ積層時の収縮もなく、極めて好ましいように見える。しかしながら、表４からも分るように該発泡成形体では発泡粒子間の融着性が悪く、そのために発泡成形体が脆くなる等の問題がある。
以上に詳記したように、実施例の積層体では発泡成形体とＦＲＰとの接着性が良い上に、積層時に収縮したり成形体内での発泡粒子間の融着性が悪い等の問題もなく、従来品より利点の多い積層体である。一方、比較例の積層体では、比較例３の積層体のように実施例の積層体とほとんど差がないように見える場合もあるが、この場合でも発泡粒子間の融着性に問題があり、総合的に見るとどこかに欠点を持っていることが分る。
【００３７】
【発明の効果】
請求項１の積層体は、不飽和ポリエステル樹脂と積層一体化する発泡成形体を、基材樹脂中にビニル結合性側鎖を持つ無架橋ポリエン重合体を含有する無架橋ポリオレフィン系樹脂発泡粒子を型内で成形してなる発泡成形体としているために、該発泡成形体は、発泡粒子間の融着性が高く、接着性も高い上に積層時の収縮率も少ないものとなり、該発泡成形体を芯材とし、これに不飽和ポリエステル樹脂を接着・積層して形成された積層体であり、従来の同種の積層体より低価格で機械的強度が大きい積層体である。従って、広範囲の用途に使うことができる積層体である。
【００３８】
請求項２の積層体では、上記不飽和ポリエステル樹脂と積層一体化する発泡成形体が、基材樹脂中に二次結晶を含む無架橋ポリオレフィン系樹脂発泡粒子からなるものであるために、型内成形性の良いものである。
【００３９】
請求項３の積層体は、上記不飽和ポリエステル樹脂と積層一体化する発泡成形体が、無架橋ポリオレフィンと無架橋１，２−ポリブタジエンとの混合樹脂としており、そのために請求項１及び２の発泡成形体と同等又はそれ以上の性能を持つ上に、低価格である。 [0001]
TECHNICAL FIELD OF THE INVENTION
The present inventionspecificNon-crosslinked polyolefin resin foam particlesFoamMolded body andUnsaturated polyester resinWith respect to the laminate.
[0002]
[Prior art]
A laminate in which a synthetic resin foam molded body is used as a core material and the surface thereof is coated with an unsaturated polyester resin is well known. Such a laminate is excellent in strength, lightness, heat insulation, sound insulation and the like, and is widely used in the form of a plate, a container, or the like for a bathtub, a fish tank, a building material, and the like.
Conventionally, as a method for producing a laminate of a foamed molded article and an unsaturated polyester resin, there is known a method in which the surface of a foamed molded article used as a core material is covered with an unsaturated polyester resin layer and cured. In this case, a rigid polyurethane foam having good adhesiveness is often used as the foamed molded product for the core material. However, this method has the drawbacks that the raw material resin is expensive, the foam molding operation is complicated and expensive, and that the core material is easily hydrolyzed when the laminate is used in a unit bath or the like.
[0003]
By the way, the use of an in-mold foamed molded article of polystyrene resin foamed particles as the core foamed article is conceivable, but this is extremely difficult. The reason is that the in-mold foam molded article of the polystyrene resin foam particles is dissolved in the vinyl monomer for crosslinking (styrene, vinyl toluene, methyl methacrylate, etc.) contained in the unsaturated polyester resin before curing.
In order to correct the drawbacks when the in-mold foam molded article of the polystyrene resin foam particles is used as a core material, foamed particles composed of a modified polystyrene resin obtained by impregnating and polymerizing 50 to 400 parts by weight of polyethylene particles with 100 parts by weight of a styrene monomer The use of an in-mold foam molded article as a core material is disclosed in Japanese Patent Publication No. 59-40622. However, when the in-mold foamed molded article of the modified polystyrene resin foam particles is used as a core material, voids are generated at the interface due to heat of 80 to 120 ° C. when the unsaturated polyester resin is laminated. In addition, (1) pinholes are generated in the unsaturated polyester layer forming the surface layer, (2) the adhesive strength between the core foamed article and the unsaturated polyester resin is weak, and (3) one of the foamed molded articles. Disadvantages such as melting of the part, and difficulty in forced curing of the product are also observed.
[0004]
In order to solve the above-mentioned problems, a core material using a modified polyolefin resin having an extraction residue ratio of 70% or more as a raw material has been proposed (JP-A-62-190236). This core material is made from a crosslinked polyolefin resin graft-modified with 10 to 30% by weight of styrene or methyl methacrylate, and the above-mentioned problems are solved because the heat shrinkage is only 5% or less even at 100 ° C. Have been. However, the core material is expensive because of using a cross-linked resin as a raw material, and if a non-cross-linked resin is used to reduce the cost, problems such as shrinkage of the core material side at the lamination interface with the unsaturated polyester resin occur. You.
In order to solve the above-mentioned problems, the present inventors have developed a method using an in-mold expanded molded article of graft-modified polyolefin-based resin expanded particles as a core material, and have applied for a patent (Japanese Patent Application No. Hei 6 (1994) -107,197). -72913). This core material is a core material obtained by molding in-mold foamed particles of a polyolefin resin modified with an unsaturated dicarboxylic acid-based grafting agent such as maleic anhydride. In order to show the effect, the adhesion between the core material and the unsaturated polyester resin is high, the mechanical strength of the core material is also large, and the core material side of the laminated interface between the unsaturated polyester resin and the core material shrinks etc. There is no core material. However, this core material has some problems in the fusing property between the foamed particles, and leaves room for improvement.
[0005]
[Problems to be solved by the invention]
The present invention solves the above problems found in the prior art,In addition to good adhesion between expanded particles, high adhesiveness, and a low shrinkage ratio during lamination and after lamination, a foamed molded product and an unsaturated polyester resinIt is an object to provide a laminate.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, completed the present invention.
That is, according to the present invention, polyolefin,Non-crosslinked polyolefin resin foam particles using a base resin as a resin mixture with a polyene polymer having a vinyl bond in the side chainMolded product formed in a mold and an unsaturated polyester resinAre laminated and integrated, thereby providing a laminate.
[0007]
In this specification, the definition of the term "non-crosslinked polyolefin resin foamed particles" is as follows.
As a sample, a foamed particle based on a mixed resin of a polyolefin and a polyene polymer is used as a sample, immersed in boiling xylene for 8 hours, and then stipulated in JIS Z 8801 (1966) which defines a standard mesh screen. The mixture is quickly filtered through a 74 μm wire mesh, and the weight of the boiling xylene-insoluble matter remaining on the wire mesh is measured. The case where the proportion of the insoluble matter is 1% by weight or less of the sample is referred to as non-crosslinked expanded polyolefin resin particles. The insoluble content p (%) is represented by the following equation.
P (%) = (M / L) × 100
M: Weight of insoluble matter (g) L: Weight of sample (g)
The insoluble content can be measured in the same manner using mixed resin particles before foaming, which is the base resin of the foamed particles, or a foamed molded product obtained from the foamed particles (however, a laminate with other materials). The same value can be obtained by the same measurement in the above. In addition, even if the foamed molded product after lamination with another material, if the other material is not mixed in the measurement sample, a value substantially the same as the measured value of the expanded particles can be obtained, and The same result can be obtained by measuring a point sufficiently distant from other materials.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors use a mixed resin obtained by adding and kneading another material to a non-crosslinked polyolefin in order to obtain a resin superior to the graft-modified resin disclosed in Japanese Patent Application No. 6-72913. Expanded particles were prepared, and the relationship between the composition and expanded particle performance was studied by trial and error. As a result, an in-mold foam molded article of foamed particles based on a mixed resin containing a non-crosslinked polyene polymer such as 1,2-polybutadiene can be used as a thermosetting resin without reducing the fusion property between the foamed particles. It has been found that the adhesiveness (hereinafter, also simply referred to as adhesiveness) with the like becomes high. On the other hand, since this property was not observed in the foamed particles based on the mixed resin of non-crosslinked polyolefin and non-crosslinked 1,4-polybutadiene, this property has a side chain of 1,2-polybutadiene, that is, a vinyl bond. It was presumed to be due to side chains. The present invention has been made based on this finding. Whether or not the resin constituting the foamed particles contains a polyene polymer having a vinyl-binding side chain is easily confirmed by differential scanning calorimetry described later.
[0009]
As the base resin used in the production of the expanded particles of the present invention, a mixed resin of one or more non-crosslinked polyolefins and one or more non-crosslinked polyene polymers is used. The mixing ratio of the non-crosslinked polyene polymer in the mixed resin is from 2 to 50% by weight, preferably from 5 to 45% by weight. If the mixing ratio is too small, adhesion between the foamed molded article and a thermosetting resin such as an unsaturated polyester resin is caused. When the mixing ratio is excessively high, there is a problem that the molding temperature range when molding the expanded particles in the mold becomes narrow.
Since the effect of improving the adhesiveness with the thermosetting resin is greater as the side chain length is shorter, a vinyl group is preferred as the side chain of the non-crosslinked polyene polymer used here. When the vinyl group is used as the side chain, the density of the side chain double bond which has the effect of improving the adhesiveness in the polyene polymer increases, so that the polyene polymer having the vinyl group in the side chain also from this point. It is desirable to use
[0010]
The non-crosslinked polyene polymer is a polymer obtained by using an unsaturated hydrocarbon having two or more double bonds in a molecule as a raw material and polymerizing such that a vinyl bond is formed in a side chain. As the monomer, a lower hydrocarbon having 4 to 12 carbon atoms, preferably 4 to 6 carbon atoms is used, but butadiene, pentadiene, hexadiene, hexatriene, cyclopentadiene, cyclohexadiene and the like are generally used, but butadiene is particularly preferable. . These monomers may be used alone or as a mixture of two or more kinds, or may be mixed with a lower olefin such as ethylene or propylene and polymerized by a known method. Usually, a homopolymer is used. Therefore, as the non-crosslinked polyene polymer to be added to the base material of the resin foamed particles of the present invention, non-crosslinked 1,2-polybutadiene is optimal.
When the non-crosslinked polyene polymer has a melting point, the melting point is desirably equal to or lower than the melting point of the non-crosslinked polyolefin polymer in the mixed resin. Further, the melt flow index (hereinafter, abbreviated as MFI) of the non-crosslinked polyene polymer is preferably from 0.1 to 13 g / 10 minutes, more preferably from 0.5 to 5 g / 10 minutes.
[0011]
The melting point of the non-crosslinked polyolefin contained in the mixed resin serving as the base material of the resin expanded particles is 100 to 180 ° C, preferably 110 to 160 ° C, and the MFI is 0.1 to 100 g / 10 minutes, preferably 1 to 50 g. / 10 minutes. If the melting point is too low, it will not be able to withstand the heat of laminating the unsaturated polyester resin and the like, and the heat resistance of the obtained laminate will also decrease. On the other hand, if the melting point is too high, problems such as an increase in foam production cost and a decrease in the expansion ratio occur. If the MFI is too low, it becomes difficult to obtain expanded particles with a good expansion ratio, and if the MFI is too high, the expansion itself becomes difficult.
Specific examples of the non-crosslinked polyolefin include: (1) high-density polyethylene (2) linear low-density polyethylene (3) polypropylene (4) propylene-olefin random copolymer (5) propylene-olefin block copolymer Coalescence and the like. The above (2) is an ethylene-α-olefin random copolymer having an α-olefin content of about 0.5 to 10% by weight, and (4) is an α-olefin content of about 0.5 to 10% by weight. The random copolymer (5) is a block copolymer having an α-olefin content of about 0.5 to 30% by weight, and the α-olefin in these copolymers has 10 or less carbon atoms.
[0012]
Among the non-crosslinked polyolefins used for the expanded particle base material, a particularly preferred polymer is a propylene-based random copolymer. The reason is that when a mixed resin obtained by mixing the copolymer and the non-crosslinked polyene polymer is used as a base material, the formed expanded particles adhere well to the unsaturated polyester resin even in a high expanded state.
In addition to the above, the third polymer may be added to the mixed resin serving as the base material of the expanded particles. In this case, the amount of the third polymer to be added is 30% by weight or less, preferably about 10% by weight of the mixed resin. However, even if the third polymer is added, the content of the non-crosslinked polyolefin in the mixed resin needs to be 50% by weight or more. Examples of the third polymer include a synthetic rubber, a polyester, a halogenated vinyl polymer containing one or two halogen atoms in a repeating structural unit, a cellulose derivative polymer, and an acrylic acid derivative polymer. You.
[0013]
The mixed resin for the base material of the foamed particles can control the mechanical strength, adhesiveness, and fusing property of the foamed particles obtained at the mixing ratio. In addition, the adhesiveness and the mechanical strength are in a trade-off relationship, and if one is sufficiently increased, the other is reduced. Therefore, it is preferable to change the mixing ratio of the resin according to the purpose of use of the expanded particles. However, when the foamed particles of the present invention are formed into a foamed molded article, the mechanical strength (including the strength due to the fusion property between the foamed particles) decreases when the adhesiveness is increased compared to the conventional polyolefin resin foamed particles. Since the ratio is low, it can be said that these expanded particles are more preferable than conventional products as expanded particles for forming a laminate. The mixed resin is put into an extruder, melted and kneaded, the melted and kneaded material is extruded into a strand, cooled, cut into pellets, and impregnated with a foaming agent in a closed container for producing expanded particles. Later, the molded product is obtained by discharging the foamed particles to a low-pressure part and subjecting the obtained expanded particles to heat molding in a mold. It should be noted that the extruded product (strand) may be cut before or after the mixed resin is cooled, and the size of the pellet is limited as long as it is within a range that is usually used during the production of a resin foam. Not done.
[0014]
The foaming of the mixed resin is performed by placing the pellets and the foaming agent dispersed in a dispersion medium such as water in a closed container, heating the pellets at a softening temperature or higher to impregnate the mixed resin with the foaming agent, and then sealing the resin. It may be carried out by a conventional method in which one end of the container is opened and the pellets and water are discharged to the low pressure part. In addition, the said resin softening temperature is a softening temperature prescribed | regulated by ASTM-D-648, and a load of 4.6 kg / cm.²Is the softening temperature measured under the following conditions. The blowing agents include propane, butane, pentane, hexane, cyclobutane, cyclohexane, trichlorofluoromethane, dichlorodifluoromethane, chlorofluoromethane, trifluoromethane, 1,1-difluoroethane, 1-chloro-1,1-difluoroethane, Volatile blowing agents such as 1,2,2,2-tetrafluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, or inorganic gas-based blowing agents such as nitrogen, air, carbon dioxide, and argon However, an inorganic gas-based blowing agent such as air which is inexpensive and has no environmental problem is preferable. The amount of the foaming agent used is generally 2 to 50% by weight of the amount of the resin used, and may be appropriately determined within the above range in consideration of the expansion ratio and the expansion temperature.
[0015]
The dispersion medium of the mixed resin pellets is a liquid such as water, ethylene glycol, glycerin, methanol, ethanol or the like which does not dissolve the mixed resin, and its use amount is generally 1.5 to 10 times the weight of the mixed resin pellets, preferably 2 to 10 times. ~ 5 times. Usually, water is used as a dispersion medium.
When dispersing the mixed resin pellets in a dispersion medium and impregnating the resin pellets with a foaming agent under heating, an anti-fusion agent is used to prevent mutual fusion of the mixed resin pellets. The anti-fusing agent is an inorganic or organic high melting point material insoluble in the dispersion medium, and is a fine powder having an average particle size of 0.001 to 70 μm, preferably 0.001 to 30 μm. At the time of producing a normal foam, an inorganic anti-fusing agent such as kaolin, talc, mica, alumina, titania, and aluminum hydroxide is used. The addition amount of the anti-fusing agent is desirably about 0.01 to 10% by weight based on the amount of the mixed resin pellet used.
When adding the anti-fusing agent, it is preferable to use an anionic surfactant such as sodium dodecylbenzenesulfonate or sodium oleate as a dispersing aid, and the amount added is 0.001% of the mixed resin pellet used amount. About 5% by weight is desirable.
[0016]
In the present invention, foamed particles are obtained using a mixed resin of a non-crosslinked polyolefin and a specific non-crosslinked polyene polymer as a base material, and when a resin foam is produced using a non-crosslinked resin as a raw material, the resin It is known that the presence of secondary crystals can provide expanded particles having excellent in-mold moldability. Whether or not a secondary crystal is present in the resin is determined by the presence or absence of a high-temperature peak appearing in the DSC curve of the expanded particles obtained from the resin. If the peak is present, the secondary crystal is present. No secondary crystals are present. Here, the high temperature peak is an endothermic peak that appears on a higher temperature side than an endothermic peak (intrinsic peak) associated with melting of the resin. Further, as described above, the presence of the non-crosslinked polyene polymer having a vinyl-bonding side chain is determined based on whether or not an exothermic peak exists on the higher temperature side than the high temperature peak of the DSC curve. The DSC curve used for these determinations can be obtained as follows.
[0017]
The DSC curve was obtained by raising the temperature of 1 to 5 mg of the foamed particles from room temperature to 220 ° C. at a rate of 10 ° C./min, and after lowering the temperature to about 40 ° C. at the same rate, a second DSC curve was obtained under the same conditions as above. For example, a unique peak appears at a peak temperature difference of less than 5 ° C., usually less than 2 ° C. in the first and second times, and when a secondary crystal is present, a high-temperature peak appears in the first DSC curve and the second time. This does not appear in the DSC curve. On the other hand, when there is no secondary crystal, a high temperature peak does not appear in the first DSC curve, so that the presence or absence of a high temperature peak can be determined. The temperature difference between the peak temperature of the unique peak appearing in the second DSC curve and that of the first high-temperature peak is 5 ° C. or more, preferably 10 ° C. or more.
When a non-crosslinked polyene polymer having a vinyl-bonding side chain is present, the first DSC curve (however, the DSC curve obtained by raising the temperature to 500 ° C. as described above) generates a higher temperature than the high temperature peak. A peak appears, and the peak does not appear in the second DSC curve, or a peak in which the calorific value is greatly reduced appears. Therefore, it is presumed that the exothermic peak appearing in the first DSC curve (at a temperature rise of 500 ° C.) appears due to the heat of reaction when the side chain vinyl bond in the non-crosslinked polyene polymer reacts.
In the present invention, the calorific value of the above-mentioned exothermic peak is an index generally indicating the type and amount of the polyene polymer in the mixed resin. The calorific value is desirably 15 to 420 J (joule) per 1 g of the foamed particles (the foamed molded body before the other material is laminated). When the calorific value is less than 15 J, the effect of improving the adhesiveness between the foamed molded article and a thermosetting resin such as an unsaturated polyester resin is inferior. (A narrowing of the molding temperature width of the molded article (a narrowing of the molding temperature width causes insufficient fusion between the foamed particles, or the resulting foamed molded article is likely to shrink). Therefore, it can be said that it is desirable to select the mixing ratio of the polyene polymer in the mixed resin described in the above [0009] in consideration of the above-mentioned heat generation value according to the type of the polyene polymer.
The calorific value can be measured in the same manner using mixed resin particles before foaming, which is the base resin of the foamed particles, or a foamed molded article obtained from the foamed particles (however, a laminate with other materials). Substantially the same value can be obtained by using the above. In addition, even if the foamed molded product after lamination with another material, if the other material is not mixed in the measurement sample, a value substantially the same as the measured value of the expanded particles can be obtained, and The same result can be obtained by measuring a point sufficiently distant from other materials.
[0018]
The mixed resin serving as the base material of the foamed particles varies depending on the foaming agent used and the amount thereof. However, the temperature is about 20 ° C. lower than the melting point (the peak temperature of the intrinsic peak appearing in the second DSC curve) and the end of the melting. When the temperature is maintained at a temperature between the above and 5 to 90 minutes, preferably 15 to 60 minutes, a secondary crystal can be formed in the mixed resin. For example, when using an inorganic gas-based foaming agent, the inorganic gas-based foaming agent is added to a closed container in which the mixed resin pellets are dispersed in a dispersion medium, and this is mixed with the melting point of the mixed resin and its extrapolative melting end temperature ( (A temperature specified in JIS K7121), a secondary crystal can be formed in the mixed resin pellets. Then, when the contents of the closed container are discharged to the low-pressure portion, foamed particles having secondary crystals can be obtained. Also, if there is a sufficiently large amount of secondary crystals in the mixed resin pellet before release, even if the temperature at the time of release (foaming temperature) is equal to or higher than the extrapolated melting end temperature of the mixed resin pellet, the apex temperature of the high temperature peak In the following cases, foamed particles having a secondary crystal and having good in-mold moldability can be obtained.
[0019]
The optimum foaming temperature differs depending on the type of the base resin and the type and amount of the foaming agent. For example, when using a non-crosslinked polypropylene resin for the raw material non-crosslinked polyolefin and foaming with an inorganic gas-based blowing agent, the foaming temperature is in a range of about 5 ° C lower to about 15 ° C higher than the melting point of the mixed resin pellets, preferably. Is preferably in the range of about 3 ° C low to about 10 ° C high. It is desirable that the rate of temperature rise when the mixed resin pellets in the dispersion medium are heated to the foaming temperature is 1 to 10 ° C / minute, preferably 2 to 5 / ° C. In addition, the low-pressure part at the time of discharging the contents of the container for foaming may be at or below atmospheric pressure, but is usually discharged under atmospheric pressure, which is advantageous in terms of cost.
The foamed particles produced by the above method have an average cell diameter of about 10 to 500 μm. The bulk specific gravity of the foamed particles varies depending on the amount of the foaming agent used and the like, but is 0.009 to 0.3 g / cm.³It is about.
[0020]
The foamed particles are heated to an appropriate temperature determined by the type of the base resin in the foam molding die to form a molded body, but when a non-crosslinked resin is used as the base resin as the foamed particles of the present invention, Generally, the molded article is heated to an arbitrary temperature between 15 ° C. lower than the melting point of the mixed resin pellet before foaming and 15 ° C. higher than the melting point. Since the expanded particles of the present invention have a high mutual fusion property between the particles, a strong foamed molded article can be obtained at the above temperature. In addition, the surface of the foamed molded article formed by the method is covered with a thin skin and air bubbles are closed, but when the air bubbles on the laminated surface of the foamed molded article with the unsaturated polyester resin are opened, this portion is Since the unsaturated polyester resin penetrates and integrates with the foamed molded article, the adhesive strength is greatly increased. Therefore, if the skin on the resin lamination surface of the foamed molded article is removed by a method such as slicing, the adhesive strength can be greatly increased. According to this method, the amount of the vinyl-bonding side chain required to obtain the same adhesive strength can be reduced, so that the content of the non-crosslinked polyene polymer in the base resin can be reduced, and the cost can be reduced. Is advantageous.
[0021]
A resin foam / unsaturated polyester resin laminate in which an in-mold foam molded article of polyolefin-based resin foam particles is used as a core material and an unsaturated polyester resin layer is provided on the surface thereof can be produced by a conventionally known method. For example, according to a resin injection molding method (resin transfer molding method), after inserting a foamed article corresponding to a shape into a mold having a desired shape, a liquid unsaturated polyester resin is injected from a liquid injection port of the mold, and the foamed molded article is injected. The space between the surface of the mold and the inner surface of the mold is filled with an unsaturated polyester resin liquid, and the liquid is cured.
During the production of the laminate, the resin layer can be reinforced by inserting a reinforcing material such as glass fiber or carbon fiber into a gap between the surface of the foamed molded product and the inner surface of the mold. As the unsaturated polyester resin liquid for lamination, a known resin liquid used for this kind of lamination may be used, and usually a liquid obtained by dissolving a curing catalyst and an unsaturated polyester resin in a vinyl monomer for crosslinking is used. Since the curing reaction of the unsaturated polyester is an exothermic reaction, heating is unnecessary, but after the curing reaction is completed, the mold may be held at 60 to 100 ° C. for 5 to 60 minutes to forcibly cure the cured product. Thus, the strength of the laminate can be further increased. Then, after the curing is completed, the laminate may be taken out of the mold to form a product.
In addition to the above, the laminate of the present invention may be manufactured by a hand lay-up method or a spray-up method. In these cases, an unsaturated polyester resin layer containing a reinforcing material may be provided on one or both sides of a foam molded article formed in a plate shape, and this may be cured.
[0022]
The foam molded article of the present invention can be laminated with a metal by a heat fusion method. The metals used here are iron, aluminum, chromium, nickel, gold, silver, copper, magnesium, zinc, tin, lead, stainless steel, tinplate, etc., with iron, stainless steel, aluminum and copper being particularly preferred.
When manufacturing a laminate with a metal, a metal foil or metal plate having a thickness of 0.01 to 50 mm, preferably 0.01 to 10 mm, on both surfaces or one surface of the foam molded product obtained as described above. Superposition, temperature of 100-200 ° C, preferably 120-170 ° C and 3 kg / cm²Or less, preferably 0.5 kg / cm²Heat fusion may be carried out under the following pressure for 0.5 to 5 minutes, preferably 1 to 3 minutes. In addition, when laminating with a metal plate having a thickness of 20 mm or less, the metal plate is heated to a temperature equal to or higher than the softening point of the mixed resin constituting the foam molded body, and this is immediately superimposed on the lamination surface of the foam molded body. If left still for 30 seconds or more, a good laminate of the metal and the foam molded article can be obtained.
[0023]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The parts and percentages shown below are based on weight.
[0024]
Examples 1 to 6, Comparative Examples 1 to 3
(Resin used as raw material for expanded particles)
Table 1 shows the non-crosslinked polyolefin and non-crosslinked polyene polymers used as raw materials of the expanded particles in Examples and Comparative Examples, and their symbols. Table 2 shows the physical properties of the resin, the properties of the resin obtained by graft-modifying the resin (used in Comparative Examples), and the type and degree of modification of the modifying agent. It is shown in% by weight. The load at the time of measuring the MFI described in Table 2 was 2.16 kgf / cm.²The temperature is 230 ° C. when the resin type is P, 190 ° C. when the resin type is R, and 150 ° C. when the resin type is S.
[Table 1]

[0025]
[Table 2]

[0026]
(Manufacture of resin pellets used as raw materials for expanded particles)
The resin shown in Table 2 was used alone or mixed to obtain a resin having the composition shown in Table 3, and the resin was melted and kneaded in an extruder, extruded into strands, quenched, and then cut into columnar resin pellets. Produced. The size of the resin pellets was such that the average weight was 2 mg / piece when the pellets contained resin P as the main component, and 4 mg / piece when the pellets contained resin R as the main component. Table 3 shows the resin composition of the resin pellets used in Examples and Comparative Examples.
[0027]
[Table 3]

[0028]
(Production of expanded particles)
100 parts of resin pellets, 300 parts of water, 0.3 parts of kaolin, 0.004 parts of sodium dodecylbenzenesulfonate, and the amount of carbon dioxide shown in Table 4 were charged into a closed container, and the mixture was stirred and stirred at the temperature shown in Table 4. The time shown in FIG. After the end of the holding time, one end of the container was released at the holding temperature, and the contents of the container were released under atmospheric pressure to obtain expanded particles. During this discharge, high-pressure carbon dioxide gas was supplied into the container to maintain the pressure in the container. The average bulk ratio of the obtained expanded particles is as shown in Table 4. In Examples 1, 2, and 7 and Comparative Examples 1, 2, and 3 in Table 4, the holding time and the temperature are shown in two stages.・ It means that it was kept on time. In addition, Table 5 shows the peak temperatures of the intrinsic peak, the high-temperature peak, and the exothermic peak determined from the DSC curves of the expanded particles shown in Table 4.
[0029]
[Table 4]

[0030]
[Table 5]

[0031]
(In-mold molding)
After leaving the foamed particles at normal temperature and normal pressure for 24 hours, they were placed in a mold and heated with high-pressure steam shown in Table 4 to produce a foamed molded article of 300 mm × 300 mm × 40 mm. The foamed molded body was dried in an oven at 60 ° C. when the main component of the resin constituting the resin was P and at 80 ° C. when the main component of the resin was R for 24 hours, and then sent to the laminating step. The expansion ratio of the molded article after in-mold molding and the fusion property of the expanded particles in the molded article are as shown in Table 4, and the fusion property was evaluated by the following method.
The foamed molded body is cut so that the vertical cross section in the width direction is 10 mm thick x 50 mm wide x 100 mm long, and the sliced plate obtained here is pulled in the longitudinal direction until it is broken, and the cut surface is visually observed. When the ratio of the number of fractures at the fused portion of the expanded particles in the fracture surface is 40% or less, ○, when the ratio is more than 40% and 60% or less, △, and when the ratio exceeds 60% It was represented by x.
[0032]
Lamination with unsaturated polyester resin)
The foamed molded body was cut into a size of 50 mm × 50 mm × 10 mm to prepare a sample in which a skin was formed on one surface and open cells were exposed on the other surface. A chopped strand mat made of glass fiber was placed on one surface of the sample (the surface shown in Table 6), and an unsaturated polyester containing methyl ethyl ketone peroxide as a curing catalyst was laminated and cured by a hand lay-up method. Thus, a laminate was produced. The chopped strand mat has a basis weight of 450 g / m.²And a thickness of 2 to 2.5 mm, and the unsaturated polyester resin is Yupika 4007A manufactured by Nippon Yupika Co., Ltd.
[0033]
Evaluation of foam molding)
1. Adhesiveness
The sample in which the fiber-reinforced unsaturated polyester resin cured product (FRP) is laminated on the foamed molded body is broken at a pulling speed of 10 mm / min so that the FRP side and the foamed molded body are broken, and the FRP side adhesion after the fracture is performed. The extent to which the foamed molded article adhered to the surface was observed. That is, it was examined whether the interface between the foam molded article and the FRP broke or the internal fracture of the foam molded article occurred, and the test was performed using a tensile tester. The larger the amount of the foamed molded body adhered to the FRP side, the better the adhesion between the FRP and the foamed molded body. Therefore, the foamed molded body adheres to 80% or more of the entire area of the surface of the FRP on the bonding surface side.場合, 70% or more and less than 80%, ○: 10% or more, less than 70%, and X: less than 10% Table 6 shows the evaluation results.
2. Shrinkage condition when laminating FRP on foam molding
With respect to the laminate in which the above-described FRPs were laminated, the lamination interface was observed from the side, and the degree of shrinkage of the foam molded article during lamination was examined. The evaluation results are shown in Table 6 where ○ indicates no shrinkage, Δ indicates slight shrinkage, and × indicates significant shrinkage.
[0034]
[Table 6]

[0035]
From Table 6, it can be said that all the laminates of the examples and the comparative examples have an acceptable adhesiveness between the foam molded article and the FRP. This is because, in the examples, a mixed resin of a non-crosslinked polyolefin and a non-crosslinked polyene polymer is used as a base resin constituting the foamed molded article, and in a comparative example, a graft-modified non-crosslinked polyolefin resin is used. Because it is. In addition, the laminate of Example 6 has a somewhat poorer adhesion between the foamed molded article and the FRP than the other laminates when laminated on the skin side, but this is because the content of the non-crosslinked polyene polymer is small. It is. However, in the case of lamination on the open cell side, the adhesiveness can be said to be acceptable.
In Examples 1 and 4 and 2 and 5, the same FRP is laminated on the same foamed molded product, but the adhesiveness between the foamed molded product and the FRP is clearer in Examples 4 and 5 than in Examples 1 and 2. High. The reason for this is that, in the laminates of Examples 1 and 2, the skin portion of the foam molded article and the FRP are adhered to each other, whereas in the laminates of Examples 4 and 5, the foamed foam portion of the foam molded article and the FRP are bonded. It is clearly recognized that the adhesion is improved when the FRP is laminated on the open bubble portion.
[0036]
Regarding the state of shrinkage of the foamed molded articles, in the case of the examples, no shrinkage due to lamination was observed at all, but in the foamed molded articles of Comparative Examples 1 and 2, large shrinkage was observed. However, the foam molded article of Comparative Example 3 in which maleic anhydride was used as a grafting agent did not shrink during lamination of the FRP, and thus appeared to be extremely preferable. However, as can be seen from Table 4, there is a problem that the foamed molded article has poor fusion-bonding property between the foamed particles, and thus the foamed molded article becomes brittle.
As described in detail above, the laminate of the example has good adhesiveness between the foamed molded article and the FRP, and also has problems such as shrinkage during lamination and poor fusion bonding between foamed particles in the molded article. Thus, it is a laminate having many advantages over conventional products. On the other hand, in the laminate of the comparative example, it may appear that there is almost no difference from the laminate of the example like the laminate of the comparative example 3, but even in this case, there is a problem in the fusion property between the foamed particles. If you look at it comprehensively, you can see that it has some disadvantages.
[0037]
【The invention's effect】
Claim 1LaminateIsA foam molded body laminated and integrated with an unsaturated polyester resin,Non-crosslinked polyene polymer with vinyl-bonding side chain contained in base resinMolded products obtained by molding non-crosslinked polyolefin resin expanded particles in a moldBecauseThe foam molded article isHigh fusion property between expanded particles,High adhesion and low shrinkage during laminationIt is a laminated body formed by bonding and laminating an unsaturated polyester resin to the foam molded body as a core material, and having a lower mechanical strength and a larger mechanical strength than a conventional laminated body of the same type. is there. Therefore, it is a laminate that can be used for a wide range of applications.
[0038]
ClaimIn the laminate of No. 2, since the foamed molded article laminated and integrated with the unsaturated polyester resin is composed of foamed particles of a non-crosslinked polyolefin resin containing secondary crystals in the base resin, the in-mold moldability Is a good one.
[0039]
Claim3The laminate ofThe foam molded article laminated and integrated with the unsaturated polyester resin is a mixed resin of a non-crosslinked polyolefin and a non-crosslinked 1,2-polybutadiene. Therefore, the foam molded article is equal to or more than the foam molded article of claims 1 and 2. It has performance and is inexpensive.

Claims (3)

ポリオレフィンと、側鎖にビニル結合を持つポリエン重合体との混合樹脂を基材樹脂とする無架橋ポリオレフィン系樹脂発泡粒子を型内で成形してなる発泡成形体と、不飽和ポリエステル樹脂とを積層一体化してなることを特徴とする積層体。 A foamed molded product obtained by molding non-crosslinked polyolefin-based resin foamed particles in a mold using a mixed resin of a polyolefin and a polyene polymer having a vinyl bond in a side chain as a base resin, and an unsaturated polyester resin laminated. A laminate characterized by being integrated. 上記無架橋ポリオレフィン系樹脂発泡粒子の基材樹脂中に二次結晶が存在していることを特徴とする請求項１に記載した積層体。 The laminate according to claim 1, wherein secondary crystals are present in the base resin of the non-crosslinked polyolefin-based resin expanded particles . 上記無架橋ポリオレフィン系樹脂発泡粒子が、無架橋ポリオレフィン５５〜９５重量％と、無架橋１，２−ポリブタジエン４５〜５重量％より成る混合樹脂を基材とすることを特徴とする請求項１又は２に記載した積層体。 The foamed non-crosslinked polyolefin resin particles are based on a mixed resin comprising 55 to 95% by weight of a non-crosslinked polyolefin and 45 to 5% by weight of a non-crosslinked 1,2-polybutadiene. 3. The laminate according to 2.