JP4530609B2 - Recycling method of thermoplastic resin composition waste, manufacturing method of thermoplastic resin composition molded body, and thermoplastic resin composition molded body - Google Patents

Description

【００５７】
ここで、表１における主要な樹脂組成物の特性は、下記の基準に従って評価されたものである。
○：優れている。
△：どちらともいえない。
×：劣る。
【００５８】
＜熱可塑性樹脂組成物廃材の酸化劣化特性＞
まず、図１に熱可塑性樹脂組成物成形体の一般的な特性低下の傾向を表わす概念図を示す。図１に示すように、熱可塑性樹脂組成物成形体は、一般的にその熱可塑性樹脂に固有の劣化誘導期間を経た後、急激にその特性が低下する傾向を有する。劣化誘導期間は熱可塑性樹脂組成物成形体の寿命に相当し、該熱可塑性樹脂組成物成形体の寿命は概ね酸化劣化特性で決定される。
【００５９】
図１から理解できるように、市場から回収された熱可塑性樹脂組成物廃材は、たとえば引張強度の測定などの物性試験によっては特性の低下が確認できない場合においても、長期間の使用によってその余寿命が短くなっており、酸化劣化特性が低下していることが多い。
【００６０】
すなわち、市場から回収された熱可塑性樹脂組成物廃材は、熱や光などにより余寿命が製造時に比べて短くなっているものがある。これらの熱可塑性樹脂組成物廃材はそのまま低品位の熱可塑性樹脂組成物成形体からなる部品へ再利用することも可能であるが、より多くの用途展開を行なうためには、再生品樹脂原料の品質を向上させ、かつ安定化することによって、中品位、または高品位の熱可塑性樹脂組成物成形体からなる部品への応用を可能とすることがリサイクル効率を向上させる上では好ましい。
【００６１】
たとえば、熱可塑性樹脂組成物廃材が図１のＡで示される時点で市場から回収された場合、この熱可塑性樹脂組成物廃材をリサイクル材料として再資源化すると、余寿命はＢ期間に示す長さとなり、耐久性あるいは高機能を必要する熱可塑性樹脂組成物成形体として使用することは不可能である。
【００６２】
なお、熱可塑性樹脂組成物成形体の酸化劣化特性の評価は、一般的には１５０℃前後のギヤー式オーブンで熱酸化劣化試験を実施し、成形品の特性の低下、たとえばクラックが発生するまでの時間を測定することなどにより行なっている。しかし、この試験方法では、評価結果を得るまでに数百時間が必要であり、熱可塑性樹脂組成物廃材の再資源化方法に適用した場合、その再資源化方法の生産性が低くならざるを得ないという問題点がある。
【００６３】
さらに、図１に示すように、回収時における熱可塑性樹脂組成物廃材の特性（たとえば引張強度などの物性）の低下は非常に小さいものであり、余寿命の低下を特定の物性の測定により評価することは困難である。
【００６４】
ここで、本発明者らは、本発明を完成する課程において、後述するように、該熱可塑性樹脂組成物廃材の酸化誘導期の値と、熱酸化劣化試験における寿命の値とが一定の関係を有することを見出した。すなわち、該熱可塑性樹脂組成物廃材の酸化誘導期を測定することにより、該熱可塑性樹脂組成物廃材の寿命を評価することができることを見出した。
【００６５】
そこで、本発明においては、熱酸化劣化試験を行なう代わりに、該熱可塑性樹脂組成物廃材の酸化誘導期を測定することにより、市場から回収された熱可塑性樹脂組成物廃材の寿命を簡易的かつ迅速に評価することとした。
【００６６】
ここで、家電製品や事務用機器などの使用済み製品は、厳しい環境で長期間使用されることが多いため、熱可塑性樹脂組成物廃材には水のスケールや錆などの異物が付着している。これらの異物が再生品樹脂ペレットに混入すると、本発明において初めて明らかになったように、再生成形体の酸化劣化特性は異物が起点となって大きく低下する。
【００６７】
表２は使用済み洗濯機の水槽に付着する異物をＸ線マイクロアナライザおよびフーリエ変換赤外分光分析計で分析したものである。
【００６８】
【表２】

【００６９】
表２に示すように、使用済み洗濯機の水槽には、洗剤、セッケンカス、タンパク質などの汚れ成分、水のスケール、錆、ゴム系接着剤などが付着している。
【００７０】
ここで、本発明者らは、本発明を完成する課程において、後述するように、該熱可塑性樹脂組成物廃材の異物混入量が、物性および酸化劣化特性におよぼす影響を検討した。その結果、該熱可塑性樹脂組成物廃材の酸化誘導期の値がほぼ一定の場合には、該熱可塑性樹脂組成物廃材の異物混入量と、熱酸化劣化試験における余寿命の値とが一定の関係を有することを見出した。すなわち、該熱可塑性樹脂組成物廃材の酸化誘導期の値がほぼ一定の場合には、該熱可塑性樹脂組成物廃材の異物混入量を制御することにより、該熱可塑性樹脂組成物廃材の余寿命を制御することができることを見出した。
【００７１】
すなわち、本発明においては、特定の目開きの大きさを有する異物除去フィルタを用いて、該熱可塑性樹脂組成物廃材の異物混入量を異物の大きさにより制御することにより、市場から回収された熱可塑性樹脂組成物廃材の余寿命を簡易かつ正確に制御することができる。
【００７２】
すなわち、本発明においては、異物の除去方法、さらには熱可塑性樹脂組成物廃材から得られる原料ペレット状の熱可塑性樹脂組成物成形体の品質を管理するロット管理方法を見出し、熱可塑性樹脂組成物成形体の品質の向上および安定性を得ることとした。
【００７３】
そして、本発明においては、必要であれば、酸化誘導期の測定結果に基づいて該熱可塑性樹脂組成物廃材に添加すべき酸化防止剤の量を決定し、その所定の量の酸化防止剤を添加した該熱可塑性樹脂組成物廃材を加熱溶融して成形することに加えて、特定の目開きの大きさを有する異物除去フィルタを用いて、該熱可塑性樹脂組成物廃材の異物混入量を異物の大きさにより制御することにより、バージン材を主要な原料とする熱可塑性樹脂組成物成形体と同等の余寿命を有する熱可塑性樹脂組成物成形体を得てもよい。
【００７４】
この場合には、本発明の熱可塑性樹脂組成物廃材の再資源化方法には、熱可塑性樹脂組成物廃材の酸化劣化特性を評価する工程と、この評価結果に基づいてこの熱可塑性樹脂組成物廃材に添加する酸化防止剤の添加量を決定する工程と、この熱可塑性樹脂組成物廃材にこの決定された添加量のこの酸化防止剤を添加して加熱溶融する工程と、この加熱溶融された熱可塑性樹脂組成物廃材の異物混入量を異物の大きさにより制御する工程と、この加熱溶融された熱可塑性樹脂組成物廃材を成形して熱可塑性樹脂組成物成形体を得る工程とが備わっていることが好ましい。
【００７５】
＜工程の流れ＞
本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの一例を、図２に示す工程図を用いて説明する。なお、図２は、本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの一例を示す工程図である。
【００７６】
ここで、従来の一般的な熱可塑性樹脂組成物廃材の再資源化方法においては、回収された熱可塑性樹脂組成物廃材を破砕、洗浄、乾燥した後、押出成形機による溶融押出成形でペレット状に成形し、再生原料として使用する場合が多い。
【００７７】
この際、一般にバージン材料では物性測定のみを行った上でペレット状に成形するが、本発明の熱可塑性樹脂組成物廃材の再資源化方法では、物性のほか、酸化劣化特性の評価および異物混入量の測定を行ない、品質の向上さらには安定化を図っている。なお、酸化劣化特性の評価は、酸化誘導期の測定で行なう。
【００７８】
詳しくは、上記の酸化誘導期の測定は、熱可塑性樹脂組成物廃材の試験試料を窒素雰囲気中に設置して、次いで、該窒素雰囲気温度を一定の速度で所定の保持温度まで昇温させた後、該窒素雰囲気を酸素雰囲気に置換した上で、該保持温度で等温保持して、該熱可塑性樹脂組成物廃材の発熱ピークが現れるまでの酸化誘導期を測定することにより行なうことが好ましい。
【００７９】
図２に示す工程の流れにおいては、まず、市場から熱可塑性樹脂組成物廃材を備えた製品が回収され（ステップ１０１）、次いで、その熱可塑性樹脂組成物廃材を備えた製品が手解体などにより解体され（ステップ１０２）、熱可塑性樹脂組成物廃材が分離される。そして、分離された熱可塑性樹脂組成物廃材は、細断、破砕されて粉状体となり（ステップ１０３）、洗浄されて汚れや不純物を概略取除かれ（ステップ１０４）、脱水、乾燥される（ステップ１０５）。そして、洗浄された熱可塑性樹脂組成物廃材の粉状体は、所定量の添加剤（酸化防止剤など）を加えて均一混合された後（ステップ１０６）、加熱溶融、混練され、押出成形により（ステップ１０７）、一定の形状のペレットに加工される（ステップ１０８）。
【００８０】
こうして、一旦、一定の形状に成形された熱可塑性樹脂組成物廃材は、酸化劣化特性および異物混入量を評価する工程（本明細書において、ロット管理工程とも記載する）において、酸化劣化特性および異物混入量を評価され（ステップ１０９）、一定の形状の熱可塑性樹脂組成物成形体に成形される（ステップ１１０）。なお、上記のロット管理工程においては、酸化劣化特性および異物混入量以外にも、一般的な物性の評価を行なってもよい。以上が、図２に示す本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの一例である。
【００８１】
なお、図２は、本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの一例を示す図ではあるが、本発明の熱可塑性樹脂組成物廃材の再資源化方法をこの工程の流れに限定するものではない。
【００８２】
すなわち、図２に示す工程の流れでは、熱可塑性樹脂組成物廃材の物性、酸化劣化特性および異物混入量の評価は、熱可塑性樹脂組成物廃材を一旦加熱溶融して一定の形状に押出成形してから実施しているが、熱可塑性樹脂組成物廃材の物性、酸化劣化特性および異物混入量の評価のタイミングは特に限定されず、本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの中において、異なるタイミングで実施してもよい。
【００８３】
たとえば、回収した熱可塑性樹脂組成物廃材を一旦加熱溶融して一定の形状に押出成形することをせずに、回収した熱可塑性樹脂組成物廃材を、解体、細断、破砕、洗浄した後、直ぐに物性、酸化劣化特性および異物混入量を評価してもよい。
【００８４】
また、本発明の熱可塑性樹脂組成物廃材の再資源化方法は、図２に示す全ての工程を備える必要はなく、一部の工程が省略されていてもよく、また、図２に示す工程以外の工程が付加されていても構わない。
【００８５】
＜熱可塑性樹脂組成物廃材の異物除去＞
本発明の熱可塑性樹脂組成物廃材の再資源化方法においては、異物を除去する工程（異物混入量を異物の大きさにより制御する工程）は、加熱溶融された熱可塑性樹脂組成物廃材を目開きが０．２ｍｍ以下の異物除去用フィルタに通す工程を含むことが好ましい。
【００８６】
また、本発明の熱可塑性樹脂組成物廃材の再資源化方法においては、熱可塑性樹脂組成物廃材の異物混入量の除去を、主に、熱可塑性樹脂組成物廃材を水洗する工程および、熱可塑性樹脂組成物廃材を加熱溶融させた上で押出成形する工程において行なうことが好ましい。すなわち、この水洗する工程で水溶性の異物が取除かれた後、この押出成形する工程で押出機に配設された異物除去用のメッシュフィルタで付着異物がさらに除去されることが望ましい。
【００８７】
ここで、この異物混入量の測定は、熱可塑性樹脂組成物廃材を加熱溶融させた上で押出成形して得られる、熱可塑性樹脂組成物を材質とする原料ペレット状の熱可塑性樹脂組成物成形体を加熱溶融してプレスシートを作成し、塵埃計測図表などを参考に、目視観察することにより、混入する異物を大きさ毎に分類することにより行なうことが好ましい。
【００８８】
本発明の熱可塑性樹脂組成物廃材の再資源化方法においては、異物除去用フィルタなどを用いた異物の大きさによる異物混入量の制御の結果、得られる熱可塑性樹脂組成物成形体に含まれる異物混入量は、大きさ（表面積）０．３ｍｍ²以上の異物がないことが好ましく、さらに大きさ（表面積）０．２〜０．３ｍｍ²の異物が１０個／１シート（２２０ｍｍ×２２０ｍｍ×１ｍｍ）以下であることが好ましい。この異物混入量がこの範囲より大きい場合は、異物のノッチ効果による物性低下や、異物による局所劣化が引きおこす寿命低下という傾向がある。
【００８９】
この際、この押出成形機には、加熱溶融された熱可塑性樹脂組成物廃材を通す異物除去用フィルタが備えられていることが好ましい。しかし、この異物除去用フィルタが備えられる箇所は、押出成形機に限られず、加熱溶融された熱可塑性樹脂組成物廃材を通して異物混入量を異物の大きさにより制御することのできる箇所であれば、どのような箇所に備えられてもよい。
【００９０】
そして、この異物除去フィルタの目開きは、０．１ｍｍ以上であることが好ましい。また、この異物除去フィルタの目開きは、０．２ｍｍ以下であることが好ましい。この目開きがこれより小さい場合には、微細な異物による目詰まりが頻繁に生じ、生産性が低下するという傾向があり、この目開きがこれより大きい場合には、熱可塑性樹脂組成物成形体の局所劣化の箇所が大きく増加するという傾向がある。
【００９１】
ここで、本発明における押出成形機は、異物を除去するためのメッシュフィルタを設置することができ、さらに加熱溶融、押出成形ができる装置であれば、特に限定されず、任意の従来公知の装置を好適に用いることができる。なお、生産性および熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の品質の面からは、単軸押出成形機、二軸押出成形機あるいは多軸式押出成形機のいずれかの押出成形機を用いて行なうことが特に好ましい。
【００９２】
また、本発明における押出成形する工程においては、汎用性を考えると、加熱溶融された熱可塑性樹脂組成物廃材から一定の形状を有する熱可塑性樹脂原料を成形するのが好ましいが、加熱溶融された熱可塑性樹脂組成物廃材から直接、一定の形状を有する熱可塑性樹脂組成物成形体を成形しても構わない。
【００９３】
さらに、本発明における成形する工程においては、得られる熱可塑性樹脂原料の形状は、樹脂組成物原料の一般的な形状であるペレット状であることが好ましいが、特にペレット状に限られず、たとえばシート状、フィルム状、パイプ状などの形態であってもよく、押出成形機の種類などから適宜決定すればよい。
【００９４】
そして、本発明における押出成形工程において、加熱溶融された熱可塑性樹脂組成物廃材がペレット状の熱可塑性樹脂原料に成形される場合には、ペレット状の熱可塑性樹脂原料を製造するには、上記の押出成形機に加えて、シートカット、ストランドカット、ホットエアカット、アンダーウォーターカットなどのいずれの切断機を用いてもよい。なお、後工程にさらに押出成形工程を設ける場合には、熱可塑性樹脂原料の供給が円滑におこなえ、大量処理にも対応できるアンダーウォーターカットが特に好ましい。
【００９５】
＜酸化劣化特性の評価＞
本発明の前記酸化劣化特性を評価する工程は、この熱可塑性樹脂組成物廃材の酸化劣化特性を、この熱可塑性樹脂組成物廃材の酸化誘導期の測定により評価する工程を含むことが好ましい。
【００９６】
ここで、熱可塑性樹脂組成物成形体の酸化劣化特性は、一般的には１５０℃前後のギヤー式オーブンで熱酸化劣化試験を実施し、成形品の特性の低下、たとえばクラックが発生するまでの時間を測定することなどによりおこなわれている。ここで、本明細書においては、このクラック発生までの時間を「クラック発生時間」とも記載する。なお、本発明の属する技術分野においては、上記の熱酸化劣化試験は、これらの熱可塑性樹脂の寿命を調べるための加速試験の１つであるとされており、この「クラック発生時間」はその寿命に対応する値を示すものであることは技術常識である。
【００９７】
しかし、熱酸化劣化試験では、評価結果を得るまでに数百時間が必要であり、熱可塑性樹脂組成物廃材の再資源化方法に適用した場合、その再資源化方法の生産性が低くならざるを得ないという問題点がある。
【００９８】
ここで、本発明における熱可塑性樹脂組成物廃材の酸化誘導期の測定は、特に限定されず、正確に酸化誘導期を測定することのできる方法であれば任意の測定方法により測定することができるが、簡便かつ正確な測定方法であることから、特に熱可塑性樹脂組成物廃材を窒素雰囲気中に設置し、次いで窒素雰囲気温度を一定の速度で所定の保持温度まで昇温させた後、窒素雰囲気を酸素雰囲気に置換して保持温度で等温保持して、熱可塑性樹脂組成物廃材の発熱ピークが現れるまでの酸化誘導期を測定することにより行なうことが好ましい。本明細書においては、このような酸化誘導期の測定方法を、ＯＩＴ（Ｏｘｙｇｅｎ Ｉｎｄｕｃｅｄ Ｔｉｍｅ）法と記載することとする。
【００９９】
ここで、本発明における熱可塑性樹脂組成物廃材の再資源化方法においては、熱可塑性樹脂組成物廃材から得られた熱可塑性樹脂組成物成形体の酸化劣化特性が十分である場合には、熱可塑性樹脂組成物成形体中の酸化防止剤量が十分であるため、酸化防止効果が大きく、酸素雰囲気中での所定の保持温度では酸化しにくくなり、発熱ピークが現れるまでの時間、すなわち酸化誘導期は長くなる傾向がある。
【０１００】
そして、本発明における熱可塑性樹脂組成物廃材の再資源化方法においては、熱可塑性樹脂組成物廃材から得られた熱可塑性樹脂組成物成形体の酸化劣化特性が十分でない場合には、熱可塑性樹脂組成物成形体中の酸化防止剤が少ないため、酸化防止効果が小さく、酸素雰囲気中での所定の保持温度で容易に酸化してしまい、発熱ピークが現れるまでの時間、すなわち酸化誘導期は短くなる傾向がある。
【０１０１】
したがって、熱可塑性樹脂組成物廃材から得られた熱可塑性樹脂組成物成形体の酸化劣化特性が十分の場合には酸化誘導期も長くなり、熱可塑性樹脂組成物廃材から得られた熱可塑性樹脂組成物成形体の酸化劣化特性が不十分の場合には酸化誘導期も短くなる傾向があるといえる。
【０１０２】
ここで、本発明に酸化誘導期の測定工程を設けた場合には、熱可塑性樹脂組成物廃材の余寿命がまだ十分に残っている場合には、該熱可塑性樹脂組成物廃材中の酸化防止剤の残存量がまだ十分に多いので、酸化防止効果が大きいために酸素雰囲気中で酸化誘導期は長くなる傾向がある。
【０１０３】
また、本発明に酸化誘導期の測定工程を設けた場合には、熱可塑性樹脂組成物廃材の余寿命があまり残っていない場合には、該熱可塑性樹脂組成物廃材中の酸化防止剤の残存量が少なくなっているので、酸化防止効果が小さいために酸素雰囲気中での所定の保持温度で容易に酸化してしまい、発熱ピークが現れるまでの時間、すなわち酸化誘導期は短くなる傾向がある。
【０１０４】
したがって、この場合において、熱可塑性樹脂組成物廃材の余寿命が長い場合には酸化誘導期も長くなり、熱可塑性樹脂組成物廃材の余寿命が短い場合には酸化誘導期も短くなる傾向があるといえる。
【０１０５】
また、同様に、この場合において、熱可塑性樹脂組成物廃材中の酸化防止剤の残存量が多い場合には酸化誘導期も長くなり、熱可塑性樹脂組成物廃材中の酸化防止剤の残存量が少ない場合には酸化誘導期も短くなる傾向があるといえる。
【０１０６】
ここで、本発明においては、熱可塑性樹脂組成物廃材から得られた熱可塑性成形体の酸化誘導期が所定の値を維持するように、図２の均一に混合する工程で、熱可塑性樹脂組成物廃材に添加剤（酸化防止剤など）を適量添加し、該熱可塑性樹脂組成物成形体の酸化劣化特性を改善し、バージン材料と同等の寿命を確保することが好ましい。
【０１０７】
また、後述の実施例において図３を用いて示すように、熱可塑性樹脂組成物成形体の寿命と、酸化誘導期との間には一定の関係が成立し、熱可塑性樹脂組成物成形体中の酸化防止剤の残存量と、酸化誘導期との間にも一定の関係が成立する。
【０１０８】
そのため、熱可塑性樹脂組成物成形体の酸化誘導期を測定することにより、熱可塑性樹脂組成物成形体の寿命と、熱可塑性樹脂組成物成形体中の酸化防止剤の残存量とを、高い信頼度でもって知ることができるといえる。
【０１０９】
なお、本発明において、測定される酸化誘導期は、回収された熱可塑性樹脂組成物廃材を一旦加熱溶融して一定の形状に押出成形したものを測定の対象として用いてもよいが、正確な酸化誘導期を測定するためには、プラスチック製品の部材として使用可能な形状を有する熱可塑性樹脂組成物成形体を測定の対象として用いてもよい。
【０１１０】
ここで、本発明における酸化誘導期の測定において、所定の保持温度は、熱可塑性樹脂組成物廃材の分類に応じて決定されることが望ましい。
【０１１１】
そして、この熱可塑性樹脂組成物廃材の分類は、熱可塑性樹脂組成物廃材に含まれる主要な熱可塑性樹脂の系統に基づいて分類されることが好ましい。主要な熱可塑性樹脂の系統に基づいて、熱可塑性樹脂組成物廃材の酸化誘導期を含む種々の特性が変化するためである。
【０１１２】
また、この所定の保持温度が高過ぎると、酸化誘導期が短くなり過ぎて有意差が出にくくなる傾向があり、この所定の保持温度が低過ぎると、酸化誘導期が長くなり過ぎて測定に時間がかかり過ぎるようになる。したがって、熱可塑性樹脂組成物廃材の分類に応じて、酸化誘導期が１〜３０分の範囲になるようにこの所定の保持温度を定めることが好ましい。
【０１１３】
そのために、熱可塑性樹脂組成物廃材の分類に応じて、この所定の保持温度を定めたデータベースをあらかじめ作成しておき、このデータベースに記録された情報を参照してこの所定の保持温度を決定することが好ましい。
【０１１４】
すなわち、本発明の測定工程において、所定の保持温度は、データベースに記録された情報に基づいて、熱可塑性樹脂組成物廃材の分類に応じて決定されることが望ましい。
【０１１５】
なお、この所定の保持温度は、酸化誘導期の測定を行なう際に、測定者がこのデータベースに記録された情報を参照しながら手動で調整してもよいが、生産性の観点からは、電子計算機の記憶装置内にこのデータベースを記録しておき、一定の手段により上記の熱可塑性樹脂組成物廃材の分類が電子計算機に入力されることにより、電子計算機内のプログラムがこのデータベースに記録された情報を参照して、自動的にこの所定の保持温度を調整することが好ましい。
【０１１６】
＜酸化防止剤＞
本発明において、必要な場合に用いる酸化防止剤としては、本発明の熱可塑性樹脂組成物廃材の再資源化方法において、熱可塑性樹脂組成物廃材に添加することにより、バージン材と同等の寿命を有する熱可塑性樹脂組成物成形体を得ることができるものであれば、任意の従来公知の酸化防止剤を用いることができ、たとえば、フェノール系酸化防止剤、リン系酸化防止剤、イオウ系酸化防止剤などを好適に用いることができる。
【０１１７】
また、これらの酸化防止剤の中でも、フェノール系酸化防止剤は、自動酸化劣化反応の連鎖担体ラジカル（ＲＯ・，ＲＯ₂・）を補足するのに有効であることから特に好ましい。さらに、フェノール系酸化防止剤の中でも、熱可塑性樹脂組成物廃材の再資源化方法をさらに効果的にする観点からは、ヒンダードフェノール系酸化防止剤がとりわけ好ましい。
【０１１８】
＜酸化防止剤の添加量の決定＞
そして、本発明においては、必要であれば、その酸化誘導期の測定結果に基づいて該熱可塑性樹脂組成物廃材に添加すべき酸化防止剤の量を決定し、その所定の量の酸化防止剤を添加した該熱可塑性樹脂組成物廃材を加熱溶融して成形することにより、バージン材を主要な原料とする熱可塑性樹脂組成物成形体と同等の余寿命を有する熱可塑性樹脂組成物成形体を得ることも可能である。
【０１１９】
この場合には、本発明の熱可塑性樹脂組成物廃材の再資源化方法は、さらに熱可塑性樹脂組成物廃材の酸化劣化特性の評価結果に基づいてこの熱可塑性樹脂組成物廃材に添加する酸化防止剤の添加量を決定する工程と、この熱可塑性樹脂組成物廃材にこの決定された添加量のこの酸化防止剤を添加して加熱溶融する工程と、を備えていることが好ましい。
【０１２０】
なお、特開２０００−６５７７１号公報には、ポリプロピレン樹脂成形品の酸化誘導期を測定することにより、そのポリプロピレン樹脂成形品の劣化度を測定する方法が開示されている。
【０１２１】
しかし、この公報には、該熱可塑性樹脂組成物廃材の酸化誘導期の値と熱酸化劣化試験における余寿命の値とが一定の関係を有するとの記載はない。また、この公報には、老化槽により劣化させた時間の値と酸化誘導期の値とが一定の関係を有するとの記載はあるが、熱酸化劣化試験における余寿命の値と老化層により劣化させた時間の値と酸化誘導期の値とが一定の関係を有するとの記載はない。
【０１２２】
よって、この公報の記載からは、該熱可塑性樹脂組成物廃材の酸化誘導期の値と、熱酸化劣化試験における余寿命の値とが一定の関係を有することが直接導かれるわけではない。
【０１２３】
また、この公報においては、ポリプロピレン樹脂成形品の劣化度を測定する方法についての記載があるのみで、熱可塑性樹脂組成物廃材の再資源化方法については何らの記載もない。
【０１２４】
本発明において、必要に応じて設けられる決定工程においては、酸化防止剤の添加量は、上記の測定工程による酸化誘導期の測定結果に基づいて、熱可塑性樹脂組成物廃材に添加する酸化防止剤の添加量を決定することのできる方法であれば、任意の方法により決定することができる。なお、これらの方法の中でも、簡便で正確な方法であることから、特にデータベースに記録された情報に基づいて、熱可塑性樹脂組成物廃材の分類および用途に応じて必要とされる酸化防止剤の必要量を求め、さらにデータベースに記録された情報に基づいて、上記の測定工程において求められた測定値から、熱可塑性樹脂組成物廃材酸化誘導期の残存する酸化防止剤の残存量を求め、この必要量とこの残存量の差を求めることにより決定することが好ましい。
【０１２５】
この場合、この熱可塑性樹脂組成物廃材の分類は、熱可塑性樹脂組成物廃材に含まれる主要な熱可塑性樹脂の系統に基づいて分類されることが好ましい。主要な熱可塑性樹脂の系統に基づいて、用途に応じて含まれるべき酸化防止剤の含有量などが変化するためである。
【０１２６】
また、この場合、この熱可塑性樹脂組成物廃材の酸化防止剤の必要量は、熱可塑性樹脂組成物廃材の分類および再資源化することにより得られる熱可塑性樹脂組成物成形体の用途により要求される余寿命に応じて必要とされる、酸化防止剤の含有量であることが好ましい。すなわち、この要求される余寿命の値を、上記の熱可塑性樹脂組成物廃材中の酸化防止剤の含有量とこの余寿命との間に成立する一定の関係にあてはめて求められる含有量であることが好ましい。
【０１２７】
さらに、この場合、この熱可塑性樹脂組成物廃材の残存する酸化防止剤の残存量は、測定工程において求められた酸化誘導期の測定値を、上記の熱可塑性樹脂組成物廃材中の酸化防止剤の残存量と酸化誘導期との間に成立する一定の関係にあてはめて求められることが好ましい。
【０１２８】
そして、上記の必要量と残存量との差を求め、その差に対応した量の酸化防止剤を、添加工程において熱可塑性樹脂組成物廃材に添加して加熱溶融し、さらに加熱溶融された熱可塑性樹脂組成物廃材を成形することにより、必要とされる酸化防止剤の含有量を有する熱可塑性樹脂組成物成形体を得ることができる。
【０１２９】
また、具体例を挙げると、熱可塑性樹脂組成物廃材が、ポリオレフィン系樹脂を主成分とする樹脂組成物廃材であり、酸化防止剤が、フェノール系酸化防止剤であり、かつ上記の決定工程において、上記の測定工程において測定された酸化誘導期の測定値をａ（分）、熱可塑性樹脂組成物廃材における酸化防止剤の残存量をｂ（％（ｗ／ｗ））、酸化防止剤の必要量をｃ（％（ｗ／ｗ））とした場合には、関係式：ｂ＝０．０５５ｌｏｇａ−０．０１７の式に基づいてｂを求め、（ｃ−ｂ−０．０５）以上の範囲で前記酸化防止剤の添加量を決定することが好ましい。
【０１３０】
さらに、上記の必要量ｃは、前記熱可塑性樹脂組成物廃材の余寿命をｄ（時間）、前記再資源化して得られる熱可塑性樹脂組成物成形体に要求される余寿命をｅ（時間）とした場合に、関係式：ｃ＝０．０６６ｌｏｇ（ｅ／ｄ）の式に基づいて決定されることが好ましい。
【０１３１】
これらの関係式に基づいて決定された量の酸化防止剤を熱可塑性樹脂組成物廃材に添加することにより、用途に応じて必要とされる余寿命を有する熱可塑性樹脂組成物成形体を得ることができる。
【０１３２】
また、熱可塑性樹脂組成物廃材および酸化防止剤の分類が異なる場合についても、あらかじめ上記のような関係式を求めておくことが好ましい。さらに、それらの関係式を記録したデータベースを作成しておくことが好ましい。
【０１３３】
そして、このようなデータベースに記録された情報を参照して、熱可塑性樹脂組成物廃材の分類および用途に応じて必要とされる酸化防止剤の含有量（必要量）と、熱可塑性樹脂組成物廃材酸化誘導期の残存する酸化防止剤の含有量（残存量）とを決定することが好ましい。
【０１３４】
すなわち、本発明にいて必要に応じて設けられる決定工程においては、酸化防止剤の添加量は、データベースに記録された情報に基づいて、熱可塑性樹脂組成物廃材の分類および再資源化して得られる熱可塑性樹脂組成物成形体の用途に応じて必要とされる酸化防止剤の必要量を求め、さらにデータベースに記録された情報に基づいて、測定工程において求められた測定値から、熱可塑性樹脂組成物廃材酸化誘導期の残存する酸化防止剤の残存量を求め、該必要量と該残存量の差を求めることにより決定することが好ましい。
【０１３５】
なお、この酸化防止剤の添加量は、酸化防止剤の添加を行なう前に、作業者がこのデータベースに記録された情報を参照しながら自ら計算して決定してもよいが、生産性の観点からは、電子計算機の記憶装置内にこのデータベースを記録しておき、一定の手段により上記の熱可塑性樹脂組成物廃材の分類、再資源化して得られる熱可塑性樹脂組成物成形体の用途および上記の測定工程における酸化誘導期の測定値が電子計算機に入力されることにより、電子計算機内のプログラムがこのデータベースに記録された情報を参照して、自動的にこの酸化防止剤の添加量を決定することが好ましい。
【０１３６】
＜酸化防止剤の添加＞
本発明の熱可塑性樹脂組成物廃材の再資源化方法は、必要な場合には、熱可塑性樹脂組成物廃材に、必要に応じて設けられる上記の決定工程において決定された添加量の酸化防止剤を添加して加熱溶融する工程を備えていてもよい。
【０１３７】
ここで、本発明に必要に応じて設けられる添加工程においては、この酸化防止剤の添加は、作業者が決定された添加量の酸化防止剤を手動で計量して手動で添加してもよいが、生産性の面からは、この酸化防止剤の添加量の決定を行なうことのできる電子計算機に接続された自動計量装置により計量して、さらに自動添加装置により添加することが好ましい。
【０１３８】
また、本発明に必要に応じて設けられる添加工程においては、熱可塑性樹脂組成物廃材と、酸化防止剤とに加えて、さらに未使用の熱可塑性樹脂組成物（本明細書において、バージン材とも記載する）を添加して加熱溶融してもよい。
【０１３９】
このように、本発明に用いる熱可塑性樹脂組成物廃材にさらに未使用の熱可塑性樹脂組成物を添加することにより、該熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の品質をさらに向上させることができるからである。
【０１４０】
ここで、この未使用の熱可塑性樹脂組成物は、この熱可塑性樹脂組成物廃材の主要成分である熱可塑性樹脂組成物と同系統の熱可塑性樹脂組成物であることが好ましい。
【０１４１】
つまり、具体例を挙げると、この熱可塑性樹脂組成物廃材の主要成分がポリオレフィン系樹脂組成物である場合に、未使用の熱可塑性樹脂組成物としては、ポリオレフィン系樹脂組成物を加えることが望ましい。
【０１４２】
なお、この際、添加される未使用の熱可塑性樹脂組成物は、この熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の用途や要求される特性に合わせて、適当な種類のものを選択することが好ましい。
【０１４３】
また、添加される未使用の熱可塑性樹脂組成物の配合量は、多ければ多いほどこの熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の品質の面からは好ましいが、あまり多過ぎると製造コストの面およびリサイクル率の面からは好ましくない。
【０１４４】
それゆえ、添加される未使用の熱可塑性樹脂組成物の配合量は、適宜、再資源化する成形体の要求特性に応じて熱可塑性樹脂組成物廃材と未使用の熱可塑性樹脂組成物を調整することが望ましい。
【０１４５】
また、本発明における添加工程においては、熱可塑性樹脂組成物廃材に、上記の成分に加えて、さらに熱安定剤、光安定剤、帯電防止剤、滑剤、フィラー、銅害防止剤、抗菌剤、着色剤などの従来公知の添加剤を、該熱可塑性樹脂組成物廃材から再資源化により得られる熱可塑性樹脂組成物成形体の特性を妨げない範囲で、必要に応じて添加してもよい。これらの添加剤を添加するタイミングとしては、後述する押出成形機への原料投入時がよい。
【０１４６】
また、本発明における添加工程においては、加熱溶融された熱可塑性樹脂組成物廃材は、他の成分を添加された後、その組成が均一になるように撹拌混合されることが好ましい。
【０１４７】
＜熱可塑性樹脂組成物成形体の成形＞
本発明の熱可塑性樹脂組成物廃材の再資源化方法は、上記の必要に応じて設けられる添加工程において加熱溶融された熱可塑性樹脂組成物廃材を成形して熱可塑性樹脂組成物成形体を得る工程を備えることが好ましい。
【０１４８】
ここで、本明細書において、熱可塑性樹脂組成物成形体と記載する際には、通常の製品またはその部品としての熱可塑性樹脂組成物成形体だけでなく、一定の形状に成形された熱可塑性樹脂組成物原料をも含むものとする。
【０１４９】
そして、本発明における添加工程における加熱溶融、および本発明における成形工程における押出成形は、加熱溶融および押出成形ができる装置であれば、特に限定されず、任意の従来公知の装置を用いて行なうことができるが、生産性および熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の品質の面からは、単軸押出成形機、二軸押出成形機あるいは多軸式押出成形機のいずれかの押出成形機を用いて行なうことが特に好ましい。
【０１５０】
また、本発明における成形工程においては、汎用性を考えると、加熱溶融された熱可塑性樹脂組成物廃材から一定の形状を熱可塑性樹脂組成物原料を成形するのが好ましいが、加熱溶融された熱可塑性樹脂組成物廃材から直接、一定の形状を有する熱可塑性樹脂組成物成形体を作製しても構わない。
【０１５１】
さらに、本発明における成形工程においては、得られる熱可塑性樹脂組成物原料の形状は、樹脂組成物原料の一般的な形状であるペレット状であることが好ましいが、特にペレット状に限られず、たとえばシート状、フィルム状、パイプ状などの形態であってもよく、押出成形機の種類などから適宜決定すればよい。
【０１５２】
そして、本発明における成形工程において、加熱溶融された熱可塑性樹脂組成物廃材がペレット状の熱可塑性樹脂組成物原料に成形される場合には、ペレット状の熱可塑性樹脂組成物原料を製造するには、上記の押出成形機に加えて、シートカット、ストランドカット、ホットエアカット、アンダーウォーターカットなどのいずれの切断機を用いてもよいが、後工程にさらに押出成形工程を設ける場合には、熱可塑性樹脂組成物原料の供給が円滑におこなえ、大量処理にも対応できるアンダーウォーターカットが特に好ましい。
【０１５３】
【実施例】
以下、実施例を挙げて本発明をより詳細に説明するが、本発明はこれらに限定されるものではない。
【０１５４】
＜実施例１＞
市場から回収した使用済みの洗濯機を解体して、代表的な結晶性熱可塑性樹脂であるポリプロピレン−ポリエチレンブロック共重合体樹脂を含む樹脂組成物の成形品である水槽を取り出し、微破砕した。次いで、微破砕された熱可塑性樹脂組成物廃材の粉体を洗浄して汚れを除去し、脱水、乾燥した後、酸化防止剤などをはじめとする所定量の添加剤を加え均一に混合した。
【０１５５】
なお、上記の酸化防止剤の添加量は、熱可塑性樹脂組成物廃材の酸化誘導期を測定し、その測定値から熱可塑性樹脂組成物成形体に要求される余寿命を実現するために必要となる酸化防止剤の添加量を計算して求めた。
【０１５６】
そして、均一に混合した熱可塑性樹脂組成物廃材の粉体を、スクリュー系４５ｍｍの二軸溶融混練押出機を用いて、１９０℃の温度で加熱溶融、混練、押出成形して、アンダーウォーターカット装置で切断し、再生品樹脂組成物原料ペレットを作製した。
【０１５７】
その後、この再生品樹脂組成物原料ペレットを、１０トン射出成形機のホッパーに投入し、加熱溶融温度２３０℃、金型温度４０℃の射出成形条件で、熱可塑性樹脂組成物成形体からなるＡＳＴＭ準拠の物性測定用試験片を作製し、物性および酸化劣化特性（酸化誘導期、クラック発生時間）を測定した。
【０１５８】
ここで、本明細書において、それぞれの部位から得られた熱可塑性樹脂組成物成形体からなるＡＳＴＭ準拠の物性測定用試験片のうち、水槽由来の試験片を「Ｒ−Ｓ」とも記載することとする。
【０１５９】
また、比較のために、ポリプロピレン−ポリエチレンブロック共重合体樹脂を含む樹脂組成物の一般グレードのバージン材料を用いてさらに別にＡＳＴＭ準拠の物性測定用試験片（本明細書において、「Ｖ−０」とも記載する）を作製し、その物性および酸化劣化特性（酸化誘導期、クラック発生時間）を測定した。測定結果を表３に示す。
【０１６０】
一方、熱可塑性樹脂の寿命と、酸化誘導期の関係を調査した。図３は、熱可塑性樹脂組成物廃材に酸化防止剤を添加し、その種類と量を変化させて再生品樹脂組成物原料ペレットを作成し、酸化誘導期と熱酸化劣化試験の関係を調べたものである。ここで、熱酸化劣化試験は１５０℃のギヤー式オーブンで実施し、クラック発生時間で評価した。
【０１６１】
図３から理解されるように、熱可塑性樹脂において、酸化誘導期と寿命との間には、一定の相関関係が認められた。よって、熱可塑性樹脂組成物廃材による再生成形体の酸化劣化特性、すなわち寿命は、酸化誘導期で概ね評価できる。
【０１６２】
なお、上記の「Ｒ−Ｓ」、「Ｖ−０」の物性および酸化劣化特性（酸化誘導期、クラック発生時間）の測定結果を表３に示す。
【０１６３】
【表３】

【０１６４】
表３に示すように、「Ｒ−Ｓ」の引張強度、曲げ強度、曲げ弾性率、アイゾット衝撃強度の各物性、および酸化誘導期、クラック発生時間は、それぞれ「Ｖ−０」と概略同等、あるいはそれ以上の特性であった。
【０１６５】
＜実施例２＞
実施例１と同様に、市場から回収した使用済みの洗濯機を解体して、代表的な結晶性熱可塑性樹脂であるポリプロピレン−ポリエチレンブロック共重合体樹脂を含む樹脂組成物の成形品である水槽を取り出し、微破砕した。次いで、微破砕された熱可塑性樹脂組成物廃材の粉体を洗浄して汚れを除去し、脱水、乾燥した後、酸化防止剤などをはじめとする所定量の添加剤を加え均一に混合した。
【０１６６】
なお、上記の酸化防止剤の添加量は、熱可塑性樹脂組成物廃材の酸化誘導期を測定し、その測定値から熱可塑性樹脂組成物成形体に要求される余寿命を実現するために必要となる酸化防止剤の添加量を計算して求めた。
【０１６７】
そして、均一に混合した熱可塑性樹脂組成物廃材の粉体を、スクリュー系４５ｍｍの二軸溶融混練押出機を用いて、１９０℃の温度で加熱溶融、混練、押出成形して、アンダーウォーターカット装置で切断し、再生品樹脂組成物原料ペレットを作製した。
【０１６８】
ここで、再生樹脂組成物原料ペレットに混入する異物と、再生成形体の物性、および酸化劣化特性の関係を調査するため、上記の押出機に異物除去用のメッシュフィルタを配設し、メッシュフィルタの目開きと、再生品樹脂組成物原料ペレットに混入する異物量の関係を検討した。
【０１６９】
異物混入量の測定は、再生品樹脂組成物原料ペレットを加熱溶融して２２０ｍｍ×２２０ｍｍ×１ｍｍのプレスシートを作製し、塵埃計測図表などを参考に、目視観察することにより、混入する異物を大きさ毎に分類することにより行なった。
【０１７０】
表４に、押出機に配設されたメッシュフィルタの目開きと、再生品樹脂組成物原料ペレットに混入する異物量の関係を示す。
【０１７１】
【表４】

【０１７２】
表４のように、押出機に配設する異物除去フィルタの目開きを小さくするにしたがい、再生品樹脂組成物原料ペレットに混入する異物の量は減少し、０．２ｍｍ付近で大きな効果があった。
【０１７３】
＜実施例３＞
再生品樹脂組成物原料ペレットの異物混入量と、熱可塑性樹脂組成物廃材再生成形体の物性の関係について調査した。
【０１７４】
実施例１と同様の工程で微破砕された熱可塑性樹脂組成物廃材を調製した後、該熱可塑性樹脂組成物廃材の洗浄のレベルを変えて押出成形加工を行ない、洗浄レベル毎に個別に再生品樹脂組成物原料ペレットを作製し、異物混入量と物性の関係を検討した。なお、上記の押出機に配設するメッシュフィルタの目開きは０．２５ｍｍとした。
【０１７５】
洗浄レベルは、水洗浄（破砕品をネット袋に入れ洗濯機で水洗浄）、フルイ洗浄（線径０．８７ｍｍ、目開き３．３６ｍｍステンレス製のフルイを使用し、振動式フルイ装置で破砕品をフルイ処理）、洗浄なしの３区分とした。
【０１７６】
異物混入量の測定は、実施例２と同様に、再生品樹脂組成物原料ペレットを加熱溶融してプレスシート（２２０ｍｍ×２２０ｍｍ×１ｍｍ）を作製し、塵埃計測図表などを参考に、０．３ｍｍ²以上の異物を目視観察で計数した。
【０１７７】
表５に使用済み洗濯機の水槽から作製した再生品樹脂組成物原料ペレットに混入する異物量と、再生品樹脂組成物原料ペレットから作製したＡＳＴＭ準拠の物性測定用試験片の物性の関係を示す。
【０１７８】
【表５】

【０１７９】
表５のように、異物混入量と物性の間には相関がみられ、異物混入量が増加すると、物性は変化し、特に引張伸びは大きく低下する。
よって、熱可塑製樹脂廃材による再生成形体の物性を安定化するには、再生品樹脂組成物原料ペレットの異物混入量を一定量以下に制御することが重要である。
【０１８０】
＜実施例４＞
再生品樹脂組成物原料ペレットの異物混入量と、熱可塑製樹脂廃材再生成形体の酸化劣化特性の関係について調査した。実験に使用した試料は、実施例３において作製した再生品樹脂組成物原料ペレットで調製した。
【０１８１】
異物混入量の測定は、再生品樹脂組成物原料ペレットを加熱溶融してプレスシート（２２０ｍｍ×２２０ｍｍ×１ｍｍ）を作製し、塵埃計測図表などを参考に、目視観察することにより、混入する異物を大きさ毎に分類することにより行った。
【０１８２】
酸化劣化特性の評価は、再生品樹脂組成物原料ペレットを、１０トン射出成形機のホッパーに投入し、加熱溶融温度２３０℃、金型温度４０℃の射出成形条件で、熱可塑性樹脂組成物廃材からなるＡＳＴＭ準拠の引張強度測定用試験片を作製した後、１５０℃のギヤー式オーブンで熱酸化劣化試験を実施し、クラックが発生するまでの時間の測定、および異物を起点とした局所的な劣化の個所数をすることにより行なった。
【０１８３】
表６に使用済み洗濯機の水槽から作製した再生品樹脂組成物原料ペレットに混入する異物量と、再生品樹脂組成物原料ペレットから作製したＡＳＴＭ準拠の物性測定用試験片の酸化劣化特性の関係を示す。
【０１８４】
【表６】

【０１８５】
表６のように、異物混入量と酸化劣化特性の間には相関がみられ、異物混入量が増加するに伴って、酸化劣化特性は低下し、特に、大きさ０．３ｍｍ²以上の異物の混入量が増加すると、熱可塑製樹脂廃材再生成形体の局所劣化の個所は大きく増加する傾向にあった。
【０１８６】
従来から、使用済み製品に付着している水のスケールや錆といった異物が、使用済み樹脂を原料とする成形体（以下、単に「再生品」と記すことがある）に混入し、物性の低下を起こす原因になっていることは知られていた。
【０１８７】
しかし、異物混入量と酸化劣化特性の間には相関がみられることは、本発明において初めて明らかになったものであり、異物混入量を制御することにより酸化劣化特性を制御するという技術的思想も、本発明において初めて提唱されたものである。
【０１８８】
しかしながら、本実施例においては、異物混入量が多い場合には、異物を起点とした局所的な劣化が顕著になるため１５０℃における熱酸化劣化が促進されたものと考察され、図３のような、１５０℃における熱酸化劣化と酸化誘導期との相関はみられなかった。
【０１８９】
よって、熱可塑性樹脂組成物廃材から得られる熱可塑性樹脂組成物の再生成形体の酸化劣化特性を安定化するには、再生品樹脂組成物原料ペレットの異物混入量を一定量以下に制御すること、特に大きさ０．３ｍｍ²以上の異物の混入量を一定量以下に制御することが重要となる。
【０１９０】
以上の実施例から理解されるように、再生品樹脂組成物原料ペレットのロット管理を、物性、異物混入量および酸化劣化特性で実施することにより、使用済み製品から回収した熱可塑性樹脂組成物廃材から高品質の特性を有する熱可塑性樹脂組成物成形体を再資源化により得ることが可能であり、熱可塑性樹脂組成物廃材から再資源化して得られる熱可塑性樹脂組成物成形体の用途を拡大展開することが可能になる。
【０１９１】
＜測定方法＞
上記の実施例で行なわれた各種物性（引張強度、曲げ強度、曲げ弾性率、アイゾット衝撃強度）、酸化誘導期、クラック発生時間の測定は、下記の測定方法に従って実施した。
【０１９２】
（ｉ）引張強度および引張弾性率の測定方法
ＡＳＴＭ準拠の物性測定用試験片を用いて、ＪＩＳ Ｋ７１１３に準じて、引張強度および引張弾性率を測定した。
【０１９３】
（ｉｉ）曲げ強度および曲げ弾性率の測定方法
ＡＳＴＭ準拠の物性測定用試験片を用いて、ＪＩＳ Ｋ７２０３に準じて、曲げ強度および曲げ弾性率を測定した。
【０１９４】
（ｉｉｉ）アイゾット衝撃強度の測定方法
ＡＳＴＭ準拠の物性測定用試験片を用いて、ＪＩＳ Ｋ７１１０に準じて、アイゾット衝撃強度を測定した。
【０１９５】
（ｉｖ）酸化誘導期の測定方法
φ４ｍｍ，厚み１ｍｍの形状を有する試験試料を用いて、熱分析装置（セイコー電子工業（株）製、ＴＧ／ＤＴＡ３２０Ｕ）を用いて測定した。まず、試験試料を窒素雰囲気中で２１０℃まで昇温し、１０分間保持した後、空気雰囲気に切替え、試験試料が発熱反応を開始するまでの時間を酸化誘導期として測定した。
【０１９６】
（ｖ）クラック発生時間の測定方法
酸化劣化特性を評価するための加速試験として、１５０℃のギヤー式オーブン内にＡＳＴＭ準拠の物性測定用試験片を静置して熱酸化劣化試験を行ない、クラックが発生するまでの時間の測定、あるいは局所的な劣化個所の計数を行なった。
【０１９７】
（ｖｉ）異物混入量の測定方法
再生品樹脂組成物原料ペレットを加熱溶融して２２０ｍｍ×２２０ｍｍ×１ｍｍのプレスシートを作製し、塵埃計測図表などを参考に、目視観察により、混入する異物を大きさ毎に分類し、計数した。
【０１９８】
今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。
【０１９９】
【発明の効果】
上記の結果より、本発明の熱可塑性樹脂組成物廃材の再資源化方法は、熱可塑性樹脂組成物廃材から、熱可塑性樹脂組成物廃材を主原料とするマテリアルリサイクルにより、多様な用途に応じた品質および寿命を有する熱可塑性樹脂組成物成形体を得ることのできる、効率的な熱可塑性樹脂組成物廃材の再資源化方法であるといえる。
【０２００】
また、本発明の熱可塑性樹脂組成物廃材の再資源化方法を用いた、本発明の熱可塑性樹脂組成物成形体の製造方法は、熱可塑性樹脂組成物廃材から、熱可塑性樹脂組成物廃材を主原料とするマテリアルリサイクルにより、多様な用途に応じた品質および寿命を有する熱可塑性樹脂組成物成形体を得ることのできる製造方法であるといえる。
【０２０１】
そして、本発明の熱可塑性樹脂組成物廃材の再資源化方法を用いて得られる、本発明の熱可塑性樹脂組成物成形体は、熱可塑性樹脂組成物廃材を主原料とするマテリアルリサイクルにより得られる、多様な用途に応じた品質および寿命を有する熱可塑性樹脂組成物成形体であるといえる。
【図面の簡単な説明】
【図１】 熱可塑性樹脂組成物成形体の一般的な特性低下の傾向の一例を示すグラフを記載した概念図である。
【図２】 本発明の熱可塑性樹脂組成物廃材の再資源化方法の工程の流れの一例を示す工程図である。
【図３】 本発明の実施例における酸化誘導期とクラック発生時間との相関関係の一例を示すグラフを記載した図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recycling a thermoplastic resin composition waste material. More specifically, the present invention relates to the recycling of thermoplastic resin composition waste, which manages the quality of the thermoplastic resin composition molded body of the thermoplastic resin composition waste by evaluating the oxidative degradation characteristics and reducing the amount of foreign matter mixed in. Regarding the method.
[0002]
The present invention also relates to a method for producing a thermoplastic resin molded article by the above recycling method. Furthermore, this invention relates also to the thermoplastic resin composition molded object obtained by said recycling method.
[0003]
[Prior art]
In recent years, with the improvement in income levels in Japan, home appliances such as air conditioners (also referred to as air conditioners in this specification), television receivers (also referred to as TVs in this specification), refrigerators, and washing machines. Information equipment such as personal computers and word processors, office equipment such as printers and fax machines, and various other furniture, stationery, and toys are now being installed at a high penetration rate in general households. Sex is improving dramatically.
[0004]
On the other hand, as a result, the amount of discarded products such as home appliances tends to increase year by year. Here, conventionally, recycling of waste materials of products including these home appliances has been often performed through a recovery route of iron scrap.
[0005]
However, in recent years, the constituent materials of members of various products such as home appliances have changed, and the number of members made of metal such as iron has decreased, and the proportion of members made of a plastic composition tends to increase. Plastic compositions have a greater degree of design freedom than metals such as iron, and can be imparted with various properties that are difficult to achieve with metals by preparing components and using additives, and are lightweight and durable. This is because it has many advantages such as high performance.
[0006]
And the waste material of various products including recent home appliances, the material composition of various components is complicated, the ratio of members made of valuable metals such as iron and copper is small, the value is low, In addition, the proportion of members made of a plastic composition, which requires a lot of labor and cost in the conventional treatment method, is large, and it is not profitable even if such waste materials are recycled in the conventional iron scrap recovery route. The situation is becoming difficult to deal with.
[0007]
And, many of these plastic composition members are synthesized using crude fossil and other embedded fossil fuel as the basic raw material. From the viewpoint of effective use of resources, products with these plastic composition members are used. In recent years, the promotion of recycling has been strongly demanded.
[0008]
In addition, environmental pollution such as global warming and acid rain due to the release of carbon dioxide and sulfur oxides from combustion of buried fossil fuels such as crude oil, and environmental pollution such as dioxin generation and scattering due to incineration of plastic compositions containing chlorine compounds. Furthermore, from the viewpoint of suppressing problems such as a shortage of landfill disposal sites due to an increase in waste materials containing bulky plastic compositions, it is possible to recycle waste materials from products having members made of these plastic compositions. It is becoming an important and urgent issue.
[0009]
In the present specification, a member made of a plastic composition is also referred to as a plastic member. Moreover, in this specification, the product provided with the plastic member is also described as a plastic product. Furthermore, in this specification, the waste material of a plastic product is also described as a plastic waste material.
[0010]
In response to the above situation, the Home Appliance Recycling Law was enforced in April 2001. Here, according to the Home Appliance Recycling Law, as of January 2002, it is obliged to recycle four items of home appliances such as air conditioners, televisions, refrigerators, and washing machines. Legal reference values are set for% or more, television 55% or more, refrigerator 50% or more, and washing machine 50% or more.
[0011]
And, following the enforcement of the Home Appliance Recycling Law, the recovery of plastic waste materials is progressing. As a method of recycling plastic waste materials recovered in this way, the so-called plastic waste materials are used as fuel. Many methods related to thermal recycling have been used in the past. However, according to such a method, it is possible to recycle plastic waste by thermal recycling, but there is a problem such as the generation of carbon dioxide gas by combustion, so it is a method that fully meets social demands. I can't say that.
[0012]
Therefore, from the plastic waste collected in this way, plastic members are separated for each system of the plastic composition by a method such as manual disassembly, and these plastic members are processed again into product members or raw materials for use. A method for recycling plastic waste has been proposed. Such a recycling method is described as material recycling in contrast to the thermal recycling described above.
[0013]
Among the plastic members separated for each system of the plastic composition as described above, a member made of a thermoplastic resin composition (also referred to as a thermoplastic resin composition waste material in this specification) is heated and melted. Then, it is possible to relatively easily recycle the material by molding again.
[0014]
Therefore, at present, in order to increase the material recycling ratio of plastic waste materials, research and development of a recycling method by material recycling of thermoplastic resin composition waste materials has been carried out with great efforts in various fields.
[0015]
However, when thermoplastic resin composition waste, especially thermoplastic resin composition waste used in home appliances and office equipment, is often used for a long time in harsh environments, In many cases, the material is poor in durability, not only in appearance quality such as discoloration or fading, but also in physical properties such as strength and flexibility.
[0016]
For this reason, the thermoplastic resin composition waste material is often used as a raw material for a plastic member having low required properties, not as a substitute for the virgin material of the thermoplastic resin composition used for a plastic member having high required properties.
[0017]
At present, such cascade recycling is the mainstream as material recycling of thermoplastic resin composition waste. Therefore, the use of the thermoplastic resin composition molded body regenerated from the thermoplastic resin composition waste is limited.
[0018]
Here, in the present specification, the virgin material means an unused resin composition. Further, in this specification, the plastic waste material with reduced quality is not used as a substitute for the virgin material of the thermoplastic resin composition used for the plastic member having high required characteristics, but as a raw material for the plastic member having low required characteristics. Shall be described as cascade recycling.
[0019]
In order to overcome such problems, the quality of the thermoplastic resin composition molded body obtained by material recycling from the above-mentioned thermoplastic resin composition waste material is improved, and it can be used as a plastic member having high required characteristics. Many research and development efforts have been made to achieve this.
[0020]
For example, many methods have been proposed for maintaining quality by mixing a virgin material with a thermoplastic resin composition waste material (material recycling material) (see, for example, Patent Document 1).
[0021]
However, in such a material recycling method, the physical properties are improved with mixing of the virgin material, but as long as the thermoplastic resin composition waste material whose physical properties are reduced is mixed, the physical properties equivalent to the virgin material are recovered. Impossible. In addition, in order to approximate the physical properties of virgin materials, it is often necessary to mix a larger amount of virgin material than waste thermoplastic resin composition, and it is difficult to say that it corresponds to a resource recycling society. is there. Moreover, even if it is a thermoplastic resin composition waste material in which the physical property has not fallen, the lifetime has fallen greatly by long-term use, and there exists a problem in long-term reliability, when it recycles.
[0022]
On the other hand, a technology regarding a recycling system that determines a recycling policy based on the component parts and the degree of deterioration of a used product and repeatedly recycles the same is also disclosed (for example, see Patent Document 2).
[0023]
However, in this recycling system, the degree of deterioration, which is a criterion for determining measures, is based on physical properties that can be determined by comparison with virgin materials, and only when the initial characteristics of recovered waste materials are known. It becomes effective. However, the amount of waste materials actually collected is enormous, and it takes a lot of time and processing capacity to grasp the initial characteristics of each of these and to compare the characteristics of the waste materials with each other. In reality, there is a problem that such a recycling system is difficult to realize and disadvantageous in cost.
[0024]
In addition, the parts used inside the products that become waste materials are less susceptible to light and the like than the parts used for appearance, so the degree of apparent deterioration is low, and it deteriorates as a significant difference in physical property values. In some cases, the progress of Therefore, in such a recycling system, there is also a problem that although it is possible to identify the material composition of the waste material, it is difficult to distribute the materials according to the degree of deterioration.
[0025]
[Patent Document 1]
JP 2000-159900 A
[0026]
[Patent Document 2]
Japanese Patent Laid-Open No. 7-24437
[0027]
[Problems to be solved by the invention]
As described above, from the thermoplastic resin composition waste material collected from the market, material recycling that uses the thermoplastic resin composition waste material as the main raw material has a quality that can be used as a highly demanded plastic member or its raw material. In addition, an efficient and low-cost thermoplastic resin composition capable of obtaining a molded product of a thermoplastic resin composition having a life equivalent to that of a virgin material (simply abbreviated as “lifetime” in the present specification). In spite of the strong demand for development of a method for recycling waste materials, such a method for recycling is not yet known.
[0028]
Based on the above-mentioned present situation, the object of the present invention is to produce a thermoplastic resin composition having a quality and a lifetime corresponding to various uses by recycling a thermoplastic resin composition waste material as a main raw material from a thermoplastic resin composition waste material. An object of the present invention is to provide an efficient method of recycling a thermoplastic resin composition waste material that can provide a molded article.
[0029]
Another object of the present invention is to form a thermoplastic resin composition having a quality and a life span according to various uses by material recycling using a thermoplastic resin composition waste material as a main raw material from a thermoplastic resin composition waste material. It is to provide a body manufacturing method.
[0030]
Furthermore, another object of the present invention is to provide a thermoplastic resin composition molded article having a quality and a lifetime according to various uses, which is obtained by material recycling using thermoplastic resin composition waste as a main raw material. It is to be.
[0031]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have obtained the idea that the quality of pellets made from waste thermoplastic resin composition should be improved and stabilized, and such a thermoplastic resin composition In order to develop a recycling method for waste materials, we prepared raw material pellets of thermoplastic resin composition moldings obtained from many types of thermoplastic resin composition waste materials, and many oxidation degradation characteristics and foreign matter contamination Experiments were conducted on a thermoplastic resin composition molded article having a combination of the above, and earnest studies were repeated.
[0032]
After the study, the present inventors heated and melted the thermoplastic resin composition waste material, and controlled the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material by the particle size of the foreign material. What is necessary is to obtain a thermoplastic resin composition molded body from the melted thermoplastic resin composition waste material and evaluate the oxidative deterioration characteristics of the raw material pellet-shaped thermoplastic resin composition molded body obtained from the thermoplastic resin composition waste material. I found out.
[0033]
In addition, the present inventors evaluated the oxidative deterioration characteristics of the thermoplastic resin composition waste material, heated and melted the thermoplastic resin composition waste material, and determined the amount of foreign matter mixed in the heated and melted thermoplastic resin composition waste material. It has been found that a thermoplastic resin composition molded article may be obtained from the thermoplastic resin composition waste material that is heated and melted by controlling the particle size of the foreign matter.
[0034]
Further, the present inventors have further studied and evaluated the oxidative deterioration characteristics of the thermoplastic resin composition waste material by measuring the oxidation induction period, and the amount of the foreign material contamination of the thermoplastic resin composition waste material is evaluated by the foreign matter removal filter. The inventors have found that the size of the opening may be controlled and completed the present invention.
[0035]
Here, if a large amount of foreign matter such as water scale or rust adhering to the plastic waste material is mixed into a plastic molded body made of plastic waste material (hereinafter sometimes simply referred to as “recycled product”), plastic molding is performed. It has been suggested by conventionally known empirical facts that it causes a decrease in physical properties of the body.
[0036]
However, in the thermoplastic resin composition waste material, it has not been known so far that a correlation is observed between the amount of foreign matter mixed and the oxidative degradation characteristic, and this has been revealed for the first time in the present invention. In addition, for the first time in the present invention, it is also possible to improve the oxidation deterioration characteristics of the thermoplastic resin composition waste material and extend the life by controlling the amount of the foreign matter mixed by the particle size of the foreign matter. is there.
[0037]
That is, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a step of heating and melting the thermoplastic resin composition waste material, and the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material as a particle of foreign matter. A step of controlling by diameter, a step of forming a thermoplastic resin composition waste by molding the heat-melted thermoplastic resin composition waste, and a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body And a method of recycling a thermoplastic resin composition waste material.
[0038]
Here, the step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body is performed by measuring the oxidative deterioration characteristics of the thermoplastic resin composition molded body by measuring the oxidation induction period of the thermoplastic resin composition molded body. It is preferable to include the process to evaluate.
[0039]
Further, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition waste material, a step of heating and melting the thermoplastic resin composition waste material, A step of controlling the amount of foreign matter mixed in the molten thermoplastic resin composition waste material by the particle size of the foreign material, a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body, and The recycling method of the thermoplastic resin composition waste material may be provided.
[0040]
Here, it is preferable that the step of evaluating the oxidation deterioration characteristic includes a step of evaluating the oxidation deterioration characteristic of the thermoplastic resin composition waste material by measuring the oxidation induction period of the thermoplastic resin composition waste material.
[0041]
In any of the above methods for recycling the thermoplastic resin composition waste material, the step of evaluating the oxidation degradation characteristics is performed by evaluating the oxidation degradation characteristics of the thermoplastic resin composition waste material. It is preferable to include a step of evaluating by measuring the oxidation induction period.
[0042]
Further, it is desirable that the step of controlling the amount of foreign matter mixed by the particle size of the foreign matter includes a step of passing the heat-melted thermoplastic resin composition waste material through a foreign matter removing filter having an opening of 0.2 mm or less.
[0043]
Furthermore, it is recommended that the thermoplastic resin composition waste material is a thermoplastic resin composition waste material mainly composed of a polyolefin resin. And this thermoplastic resin composition waste material may be a thermoplastic resin composition waste material collected from a washing machine.
[0044]
Moreover, this invention includes the manufacturing method of the thermoplastic resin composition molded object which obtains a thermoplastic resin composition molded object by the recycling method of said thermoplastic resin composition waste material. Here, the thermoplastic resin composition molded body may be a thermoplastic resin composition molded body having a pellet shape.
[0045]
And this invention contains the thermoplastic resin composition molded object obtained by the recycling method of said thermoplastic resin composition waste material. Here, the thermoplastic resin composition molded body may be a thermoplastic resin composition molded body having a pellet shape.
[0046]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0047]
<Outline of recycling method of thermoplastic resin composition waste>
The method for recycling the thermoplastic resin composition waste material according to the present invention includes a step of heating and melting the thermoplastic resin composition waste material, and the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material according to the particle size of the foreign material. A step of controlling, a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body, a step of evaluating the oxidative degradation characteristics of the thermoplastic resin composition molded body, A method for recycling a thermoplastic resin composition waste material.
[0048]
Alternatively, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition waste material, a step of heating and melting the thermoplastic resin composition waste material, and the heating A step of controlling the amount of foreign matter mixed in the molten thermoplastic resin composition waste material by the particle size of the foreign material, a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body, and The recycling method of the thermoplastic resin composition waste material may be provided.
[0049]
Here, if a large amount of foreign matter such as water scale or rust adhering to the plastic waste material is mixed into a plastic molded body made of plastic waste material (hereinafter sometimes simply referred to as “recycled product”), plastic molding is performed. It has been suggested by conventionally known empirical facts that it causes a decrease in physical properties of the body.
[0050]
However, in the thermoplastic resin composition waste material, it has not been known so far that a correlation is observed between the amount of foreign matter mixed and the oxidative degradation characteristic, and this has been revealed for the first time in the present invention. In addition, for the first time in the present invention, it is also possible to improve the oxidation deterioration characteristics of the thermoplastic resin composition waste material and extend the life by controlling the amount of the foreign matter mixed according to the size of the foreign matter. is there.
[0051]
Conventionally, when manufacturing plastic moldings using virgin materials, physical properties are measured, and necessary stabilization treatments such as adding antioxidants are performed according to the properties required for plastic moldings. Was normal.
[0052]
However, the method of recycling the thermoplastic resin composition waste material of the present invention is not only measuring the physical properties of the thermoplastic resin composition waste material, but also measuring the oxidative degradation characteristics and the amount of foreign material contamination. This is different from the conventionally known technology in that quality is improved and stabilized by extending the life by adding an antioxidant when necessary.
[0053]
<Waste thermoplastic resin composition>
The thermoplastic resin composition waste material used in the present invention is obtained by using the thermoplastic resin composition waste material recycling method of the present invention to obtain a thermoplastic resin composition molded article having the same physical properties and life as the virgin material. Any conventionally known thermoplastic resin composition waste material can be used as long as it can be used. For example, a thermoplastic resin composition mainly composed of a polypropylene resin, a polyethylene resin, a thermoplastic polyester resin, or the like. Waste materials can be suitably used.
[0054]
Among these thermoplastic resin composition waste materials, thermoplastic resin composition waste materials mainly composed of polyolefin resins such as polyethylene resins and polypropylene resins are shown in Table 1 below. Recycled thermoplastic resin composition moldings using other thermoplastic resin composition recycling methods from other types of thermoplastic resin composition waste materials in terms of processability and economy. Since it is superior to the recycled thermoplastic resin composition molded article, it can be suitably used as a raw material for recycling by material recycling in the method of recycling a thermoplastic resin composition waste material of the present invention. .
[0055]
In addition, for thermoplastic resin composition waste materials containing polyolefin resin as a main component, in the method of recycling thermoplastic resin composition waste materials according to the present invention, the properties can be improved by adding various additives such as antioxidants. Since it is easy to perform, there is also an advantage that a thermoplastic resin composition molded product having a stable life can be obtained with good reproducibility.
[0056]
[Table 1]

[0057]
Here, the characteristics of the main resin compositions in Table 1 were evaluated according to the following criteria.
○: Excellent.
Δ: Neither can be said.
X: Inferior.
[0058]
<Oxidative degradation characteristics of thermoplastic resin composition waste>
First, FIG. 1 is a conceptual diagram showing a general tendency of characteristic deterioration of a thermoplastic resin composition molded article. As shown in FIG. 1, a thermoplastic resin composition molded article generally has a tendency that its characteristics rapidly decrease after a deterioration induction period specific to the thermoplastic resin. The deterioration induction period corresponds to the lifetime of the thermoplastic resin composition molded article, and the lifetime of the thermoplastic resin composition molded article is generally determined by oxidation degradation characteristics.
[0059]
As can be understood from FIG. 1, the thermoplastic resin composition waste material collected from the market has a remaining life due to long-term use even when deterioration in properties cannot be confirmed by physical property tests such as measurement of tensile strength. In many cases, the oxidative degradation characteristics are reduced.
[0060]
In other words, some thermoplastic resin composition wastes collected from the market have a shorter remaining life than that at the time of manufacture due to heat or light. These thermoplastic resin composition waste materials can be reused as they are for parts made of low-quality thermoplastic resin composition molded bodies, but in order to develop more applications, In order to improve the recycling efficiency, it is preferable to improve the quality and stabilize the quality so that it can be applied to a part made of a molded article of medium or high quality thermoplastic resin composition.
[0061]
For example, if the thermoplastic resin composition waste material is recovered from the market at the time indicated by A in FIG. 1, when this thermoplastic resin composition waste material is recycled as a recycled material, the remaining life is the length indicated by the period B. Therefore, it cannot be used as a molded article of a thermoplastic resin composition that requires durability or high functionality.
[0062]
The evaluation of the oxidative degradation characteristics of the molded thermoplastic resin composition is generally conducted by performing a thermal oxidative degradation test in a gear-type oven at around 150 ° C. until the degradation of the molded product characteristics, for example, cracks occur. This is done by measuring the time. However, this test method requires several hundred hours to obtain an evaluation result, and when applied to a method for recycling thermoplastic resin composition waste, the productivity of the recycling method must be low. There is a problem that you can not get.
[0063]
Furthermore, as shown in FIG. 1, the decrease in properties (for example, physical properties such as tensile strength) of the thermoplastic resin composition waste during recovery is very small, and the decrease in remaining life is evaluated by measuring specific physical properties. It is difficult to do.
[0064]
Here, in the course of completing the present invention, the present inventors have a fixed relationship between the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the lifetime in the thermal oxidation degradation test, as will be described later. It was found to have That is, it has been found that the lifetime of the thermoplastic resin composition waste material can be evaluated by measuring the oxidation induction period of the thermoplastic resin composition waste material.
[0065]
Therefore, in the present invention, instead of performing a thermal oxidative degradation test, by measuring the oxidation induction period of the thermoplastic resin composition waste material, the life of the thermoplastic resin composition waste material collected from the market can be simplified and We decided to evaluate quickly.
[0066]
Here, used products such as home appliances and office equipment are often used for a long time in a harsh environment, so the thermoplastic resin composition waste material has foreign matters such as water scale and rust on it. . When these foreign substances are mixed into the recycled product resin pellets, the oxidation deterioration characteristics of the recycled molded product are greatly reduced starting from the foreign substances, as has been clarified for the first time in the present invention.
[0067]
Table 2 shows an analysis of foreign matter adhering to the water tank of a used washing machine with an X-ray microanalyzer and a Fourier transform infrared spectrometer.
[0068]
[Table 2]

[0069]
As shown in Table 2, dirt components such as detergents, soaps and proteins, water scales, rust, and rubber adhesives are attached to the water tank of the used washing machine.
[0070]
Here, in the course of completing the present invention, the present inventors examined the influence of the amount of foreign matter mixed in the thermoplastic resin composition waste material on physical properties and oxidative deterioration characteristics, as will be described later. As a result, when the value of the oxidation induction period of the thermoplastic resin composition waste material is almost constant, the amount of foreign matter mixed in the thermoplastic resin composition waste material and the remaining life value in the thermal oxidation degradation test are constant. Found to have a relationship. That is, when the oxidation induction period value of the thermoplastic resin composition waste material is substantially constant, the remaining life of the thermoplastic resin composition waste material is controlled by controlling the amount of foreign matter mixed in the thermoplastic resin composition waste material. Found that can be controlled.
[0071]
That is, in the present invention, by using a foreign matter removal filter having a specific opening size, the amount of foreign matter mixed in the thermoplastic resin composition waste material is controlled by the size of the foreign matter, and the filter was recovered from the market. The remaining life of the thermoplastic resin composition waste can be controlled easily and accurately.
[0072]
That is, in the present invention, a method for removing foreign matters, and further a lot management method for managing the quality of a raw material pellet-shaped thermoplastic resin composition obtained from a thermoplastic resin composition waste material, have been found, and a thermoplastic resin composition It was decided to improve the quality and stability of the compact.
[0073]
In the present invention, if necessary, the amount of the antioxidant to be added to the thermoplastic resin composition waste material is determined based on the measurement result of the oxidation induction period, and the predetermined amount of the antioxidant is added. In addition to heating and melting the added thermoplastic resin composition waste material, using a foreign matter removal filter having a specific mesh size, the amount of foreign matter mixed in the thermoplastic resin composition waste material is determined as a foreign matter. By controlling the size of the thermoplastic resin composition, a thermoplastic resin composition molded body having a remaining life equivalent to that of a thermoplastic resin composition molded body using a virgin material as a main raw material may be obtained.
[0074]
In this case, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition waste material, and the thermoplastic resin composition based on the evaluation result. A step of determining an addition amount of the antioxidant to be added to the waste material, a step of adding the determined addition amount of the antioxidant to the waste material of the thermoplastic resin composition and heat-melting, and the heat-melting step. A step of controlling the amount of foreign matter mixed in the thermoplastic resin composition waste material according to the size of the foreign matter, and a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body. Preferably it is.
[0075]
<Process flow>
An example of the process flow of the method for recycling a thermoplastic resin composition waste material of the present invention will be described with reference to the process diagram shown in FIG. FIG. 2 is a process diagram showing an example of a process flow of the method for recycling a thermoplastic resin composition waste material according to the present invention.
[0076]
Here, in the conventional method of recycling the thermoplastic resin composition waste material, the recovered thermoplastic resin composition waste material is crushed, washed, dried, and then pelletized by melt extrusion using an extruder. In many cases, it is used as a recycled raw material.
[0077]
At this time, in general, the virgin material is formed into pellets after only measuring the physical properties. However, in the method for recycling the thermoplastic resin composition waste material according to the present invention, in addition to the physical properties, the evaluation of the oxidation deterioration characteristics and the contamination The quantity is measured to improve and stabilize the quality. Note that the evaluation of the oxidative deterioration characteristic is made by measuring the oxidation induction period.
[0078]
Specifically, in the measurement of the oxidation induction period, a test sample of the thermoplastic resin composition waste material was placed in a nitrogen atmosphere, and then the temperature of the nitrogen atmosphere was increased to a predetermined holding temperature at a constant rate. Thereafter, the nitrogen atmosphere is preferably replaced with an oxygen atmosphere, and kept at the holding temperature isothermally, and the oxidation induction period until the exothermic peak of the thermoplastic resin composition waste material appears is preferably measured.
[0079]
In the process flow shown in FIG. 2, first, a product including the thermoplastic resin composition waste material is collected from the market (step 101), and then the product including the thermoplastic resin composition waste material is manually disassembled or the like. The material is disassembled (step 102), and the thermoplastic resin composition waste material is separated. The separated thermoplastic resin composition waste is shredded and crushed into a powdery body (step 103), washed to roughly remove dirt and impurities (step 104), dehydrated and dried (step 104). Step 105). The washed thermoplastic resin composition waste material is uniformly mixed by adding a predetermined amount of an additive (such as an antioxidant) (step 106), heated and melted, kneaded, and extruded. (Step 107), the pellets are processed into a fixed shape (Step 108).
[0080]
Thus, the thermoplastic resin composition waste material once molded into a certain shape is subjected to oxidation deterioration characteristics and foreign matters in a process of evaluating the oxidation deterioration characteristics and the amount of foreign matters mixed (also referred to as a lot management step in this specification). The mixing amount is evaluated (step 109), and is molded into a thermoplastic resin composition molded body having a fixed shape (step 110). In the lot management process described above, general physical properties may be evaluated in addition to the oxidation deterioration characteristics and the amount of contamination. The above is an example of the process flow of the method for recycling the thermoplastic resin composition waste material of the present invention shown in FIG.
[0081]
FIG. 2 is a diagram showing an example of the process flow of the method for recycling the thermoplastic resin composition waste material of the present invention, but the method for recycling the thermoplastic resin composition waste material of the present invention is shown in FIG. It is not limited to this flow.
[0082]
That is, in the process flow shown in FIG. 2, the properties of the thermoplastic resin composition waste, the oxidative deterioration characteristics, and the amount of foreign matter mixed are evaluated by once melting the thermoplastic resin composition waste and extruding it into a certain shape. However, there are no particular limitations on the timing of evaluating the physical properties, oxidative deterioration characteristics, and the amount of foreign matter mixed in the thermoplastic resin composition waste, and the process of the method for recycling the thermoplastic resin composition waste of the present invention You may implement at a different timing in the flow of this.
[0083]
For example, after the recovered thermoplastic resin composition waste material is disassembled, shredded, crushed, washed without first melting the recovered thermoplastic resin composition waste material and extruding it into a certain shape, You may immediately evaluate the physical properties, oxidation deterioration characteristics, and the amount of contamination.
[0084]
In addition, the method for recycling the thermoplastic resin composition waste material according to the present invention does not have to include all the steps shown in FIG. 2, and some of the steps may be omitted, and the steps shown in FIG. Other steps may be added.
[0085]
<Removal of foreign matter from waste thermoplastic resin composition>
In the method for recycling the thermoplastic resin composition waste material according to the present invention, the step of removing the foreign matter (the step of controlling the amount of foreign matter mixed according to the size of the foreign matter) is performed on the thermoplastic resin composition waste material that has been heated and melted. It is preferable to include a step of passing through a foreign matter removing filter having an opening of 0.2 mm or less.
[0086]
Further, in the method for recycling the thermoplastic resin composition waste material according to the present invention, the removal of the amount of foreign matter mixed in the thermoplastic resin composition waste material is mainly performed by washing the thermoplastic resin composition waste material with water, It is preferably performed in a step of extruding after melting and melting the resin composition waste material. That is, it is desirable that after the water-soluble foreign matter is removed in the washing step, the adhered foreign matter is further removed by the foreign matter removing mesh filter disposed in the extruder in the extrusion step.
[0087]
Here, the measurement of the amount of foreign matter mixed is obtained by molding a thermoplastic resin composition in the form of a raw material pellet made of a thermoplastic resin composition obtained by extrusion molding after heating and melting a thermoplastic resin composition waste material. It is preferable to create a press sheet by heating and melting the body, and visually observing with reference to a dust measurement chart and the like, and classifying foreign matters to be mixed according to size.
[0088]
In the method for recycling the thermoplastic resin composition waste material according to the present invention, as a result of controlling the amount of foreign matter mixed by the size of the foreign matter using a foreign matter removing filter or the like, it is included in the resulting thermoplastic resin composition molded article The amount of contamination is 0.3mm (surface area) ² It is preferable that there is no foreign material, and the size (surface area) is 0.2 to 0.3 mm. ² The number of foreign matters is preferably 10 pieces / sheet (220 mm × 220 mm × 1 mm) or less. When this amount of foreign matter is larger than this range, there is a tendency that the physical properties are reduced due to the notch effect of the foreign matter and the life is reduced due to local deterioration caused by the foreign matter.
[0089]
At this time, it is preferable that the extrusion molding machine is provided with a foreign matter removing filter through which the thermoplastic resin composition waste material heated and melted passes. However, the place where the filter for removing foreign matter is provided is not limited to the extrusion molding machine, as long as the amount of foreign matter can be controlled by the size of the foreign matter through the heat-melted thermoplastic resin composition waste, It may be provided at any location.
[0090]
And it is preferable that the opening of this foreign material removal filter is 0.1 mm or more. Moreover, it is preferable that the opening of this foreign matter removal filter is 0.2 mm or less. If this opening is smaller than this, clogging with fine foreign matters frequently occurs and the productivity tends to decrease. If this opening is larger than this, a molded thermoplastic resin composition is obtained. There is a tendency for the number of local degradation points to greatly increase.
[0091]
Here, the extrusion molding machine in the present invention is not particularly limited as long as it can install a mesh filter for removing foreign substances, and can perform heat melting and extrusion molding. Can be suitably used. In terms of productivity and the quality of the thermoplastic resin composition molded body obtained by recycling the thermoplastic resin composition waste material, a single-screw extruder, a twin-screw extruder or a multi-screw extruder is used. It is particularly preferable to carry out using any of the extruders.
[0092]
In the extrusion molding step of the present invention, considering versatility, it is preferable to mold a thermoplastic resin raw material having a certain shape from a thermoplastic resin composition waste material that has been heated and melted. You may shape | mold the thermoplastic resin composition molded object which has a fixed shape directly from a thermoplastic resin composition waste material.
[0093]
Furthermore, in the molding step in the present invention, the shape of the obtained thermoplastic resin raw material is preferably a pellet shape which is a general shape of the resin composition raw material, but is not particularly limited to a pellet shape, for example, a sheet The shape may be a shape such as a shape, a film, or a pipe, and may be determined as appropriate from the type of the extruder.
[0094]
And, in the extrusion molding step in the present invention, when the thermoplastic resin composition waste material heated and melted is formed into a pellet-shaped thermoplastic resin material, In addition to the above extrusion molding machine, any cutting machine such as sheet cutting, strand cutting, hot air cutting, underwater cutting, etc. may be used. In addition, when providing an extrusion molding process further in a post process, the underwater cut which can supply a thermoplastic resin raw material smoothly and can respond also to a mass treatment is especially preferable.
[0095]
<Evaluation of oxidation degradation characteristics>
The step of evaluating the oxidation deterioration characteristic of the present invention preferably includes a step of evaluating the oxidation deterioration characteristic of the thermoplastic resin composition waste material by measuring the oxidation induction period of the thermoplastic resin composition waste material.
[0096]
Here, the oxidative degradation characteristics of the molded thermoplastic resin composition are generally determined by conducting a thermal oxidative degradation test in a gear oven at around 150 ° C. until the degradation of the molded product characteristics, for example, cracks occur. This is done by measuring time. Here, in this specification, the time until the occurrence of a crack is also referred to as a “crack occurrence time”. In the technical field to which the present invention belongs, the thermal oxidation deterioration test is considered to be one of the accelerated tests for examining the life of these thermoplastic resins. It is common technical knowledge to indicate a value corresponding to the lifetime.
[0097]
However, in the thermal oxidative degradation test, several hundred hours are required to obtain an evaluation result, and when applied to a method of recycling a thermoplastic resin composition waste material, the productivity of the method of recycling must not be lowered. There is a problem of not getting.
[0098]
Here, the measurement of the oxidation induction period of the thermoplastic resin composition waste material in the present invention is not particularly limited, and any measurement method can be used as long as it can accurately measure the oxidation induction period. However, since it is a simple and accurate measurement method, in particular, the thermoplastic resin composition waste material is placed in a nitrogen atmosphere, and then the nitrogen atmosphere temperature is raised to a predetermined holding temperature at a constant rate, and then the nitrogen atmosphere It is preferable to perform the measurement by measuring the oxidation induction period until the exothermic peak of the thermoplastic resin composition waste material appears by substituting with an oxygen atmosphere and isothermally holding at the holding temperature. In this specification, such a method for measuring the oxidation induction period is referred to as an OIT (Oxygen Induced Time) method.
[0099]
Here, in the method for recycling the thermoplastic resin composition waste material according to the present invention, when the oxidative deterioration characteristics of the thermoplastic resin composition molded body obtained from the thermoplastic resin composition waste material are sufficient, Since the amount of antioxidant in the plastic resin composition molded article is sufficient, the antioxidant effect is large, it becomes difficult to oxidize at a predetermined holding temperature in an oxygen atmosphere, and the time until an exothermic peak appears, that is, oxidation induction The period tends to be longer.
[0100]
In the method for recycling the thermoplastic resin composition waste material according to the present invention, when the oxidative deterioration characteristics of the thermoplastic resin composition molded body obtained from the thermoplastic resin composition waste material are not sufficient, the thermoplastic resin Since there are few antioxidants in the molded product of the composition, the antioxidant effect is small, it is easily oxidized at a predetermined holding temperature in an oxygen atmosphere, and the time until the exothermic peak appears, that is, the oxidation induction period is short. Tend to be.
[0101]
Therefore, when the oxidative deterioration characteristics of the thermoplastic resin composition molded body obtained from the thermoplastic resin composition waste material are sufficient, the oxidation induction period also becomes longer, and the thermoplastic resin composition obtained from the thermoplastic resin composition waste material becomes longer. It can be said that the oxidation induction period tends to be short when the molded article has insufficient oxidation deterioration characteristics.
[0102]
Here, in the case where the measurement step of the oxidation induction period is provided in the present invention, when the remaining life of the thermoplastic resin composition waste material still remains, the antioxidant in the thermoplastic resin composition waste material is prevented. Since the remaining amount of the agent is still sufficiently large, the oxidation-inducing period tends to be long in an oxygen atmosphere due to the large antioxidant effect.
[0103]
In addition, in the case where the oxidation induction period measuring step is provided in the present invention, when the remaining life of the thermoplastic resin composition waste material does not remain so much, the remaining antioxidant in the thermoplastic resin composition waste material Since the amount is small, the oxidation prevention effect is small, so that it easily oxidizes at a predetermined holding temperature in an oxygen atmosphere, and the time until the exothermic peak appears, that is, the oxidation induction period tends to be short. .
[0104]
Therefore, in this case, when the remaining life of the thermoplastic resin composition waste material is long, the oxidation induction period is long, and when the remaining life of the thermoplastic resin composition waste material is short, the oxidation induction period tends to be short. It can be said.
[0105]
Similarly, in this case, if the remaining amount of the antioxidant in the thermoplastic resin composition waste is large, the oxidation induction period becomes longer, and the remaining amount of the antioxidant in the thermoplastic resin composition waste is increased. When the amount is small, the oxidation induction period tends to be shortened.
[0106]
Here, in the present invention, the thermoplastic resin composition in the step of uniformly mixing in FIG. 2 so that the oxidation induction period of the thermoplastic molded body obtained from the thermoplastic resin composition waste material maintains a predetermined value. It is preferable to add an appropriate amount of an additive (such as an antioxidant) to the waste material to improve the oxidative deterioration characteristics of the molded thermoplastic resin composition and to ensure the same life as the virgin material.
[0107]
Further, as shown in FIG. 3 in the examples described later, a certain relationship is established between the lifetime of the thermoplastic resin composition molded body and the oxidation induction period, and in the thermoplastic resin composition molded body. A certain relationship is also established between the remaining amount of the antioxidant and the oxidation induction period.
[0108]
Therefore, by measuring the oxidation induction period of the thermoplastic resin composition molded body, the lifetime of the thermoplastic resin composition molded body and the remaining amount of the antioxidant in the thermoplastic resin composition molded body are highly reliable. It can be said that it can be known with a degree.
[0109]
In the present invention, the measured oxidation induction period may be obtained by subjecting the recovered thermoplastic resin composition waste material once heated and melted and extruded into a certain shape as an object of measurement. In order to measure the oxidation induction period, a thermoplastic resin composition molded body having a shape that can be used as a member of a plastic product may be used as a measurement target.
[0110]
Here, in the measurement of the oxidation induction period in the present invention, it is desirable that the predetermined holding temperature is determined according to the classification of the thermoplastic resin composition waste material.
[0111]
And it is preferable to classify | categorize this thermoplastic resin composition waste material based on the system | strain of the main thermoplastic resins contained in a thermoplastic resin composition waste material. This is because various properties including the oxidation induction period of the thermoplastic resin composition waste material change based on the main thermoplastic resin system.
[0112]
In addition, if the predetermined holding temperature is too high, the oxidation induction period tends to be too short and it is difficult to make a significant difference. It takes too much time. Therefore, it is preferable to set the predetermined holding temperature so that the oxidation induction period is in the range of 1 to 30 minutes according to the classification of the thermoplastic resin composition waste.
[0113]
Therefore, in accordance with the classification of the thermoplastic resin composition waste material, a database in which the predetermined holding temperature is determined is created in advance, and the predetermined holding temperature is determined with reference to information recorded in the database. It is preferable.
[0114]
That is, in the measurement process of the present invention, it is desirable that the predetermined holding temperature is determined according to the classification of the thermoplastic resin composition waste material based on the information recorded in the database.
[0115]
The predetermined holding temperature may be manually adjusted by the measurer while referring to the information recorded in this database when performing the measurement of the oxidation induction period. The database is recorded in the storage device of the computer, and the classification of the thermoplastic resin composition waste material is input to the electronic computer by a certain means, so that the program in the electronic computer is recorded in the database. It is preferable to automatically adjust the predetermined holding temperature with reference to the information.
[0116]
<Antioxidant>
In the present invention, as an antioxidant used when necessary, in the method for recycling thermoplastic resin composition waste material according to the present invention, by adding to the thermoplastic resin composition waste material, the same life as the virgin material can be obtained. Any conventionally known antioxidant can be used as long as the molded thermoplastic resin composition can be obtained. For example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants can be used. An agent or the like can be preferably used.
[0117]
Among these antioxidants, phenolic antioxidants are chain carrier radicals (RO ·, RO for auto-oxidation degradation reaction). ₂ It is particularly preferable because it is effective for supplementing. Further, among the phenolic antioxidants, hindered phenolic antioxidants are particularly preferable from the viewpoint of making the method for recycling the thermoplastic resin composition waste material more effective.
[0118]
<Determination of the amount of antioxidant added>
In the present invention, if necessary, the amount of the antioxidant to be added to the thermoplastic resin composition waste material is determined based on the measurement result of the oxidation induction period, and the predetermined amount of the antioxidant is determined. A thermoplastic resin composition molded article having a remaining life equivalent to that of a thermoplastic resin composition molded article using a virgin material as a main raw material is formed by heating and melting the thermoplastic resin composition waste material added with It is also possible to obtain.
[0119]
In this case, the method for recycling the thermoplastic resin composition waste material according to the present invention further includes the antioxidant added to the thermoplastic resin composition waste material based on the evaluation result of the oxidative deterioration characteristics of the thermoplastic resin composition waste material. It is preferable to include a step of determining the addition amount of the agent, and a step of adding the determined addition amount of the antioxidant to the thermoplastic resin composition waste and heating and melting it.
[0120]
Japanese Patent Laid-Open No. 2000-65771 discloses a method of measuring the degree of deterioration of a polypropylene resin molded product by measuring the oxidation induction period of the polypropylene resin molded product.
[0121]
However, this publication does not describe that the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the remaining life in the thermal oxidation deterioration test have a certain relationship. In addition, this publication describes that the value of time deteriorated by the aging tank and the value of the oxidation induction period have a certain relationship, but the deterioration is caused by the remaining life value and the aging layer in the thermal oxidation deterioration test. There is no description that the value of the allowed time and the value of the oxidation induction period have a certain relationship.
[0122]
Therefore, from the description of this publication, it is not directly derived that the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the remaining life in the thermal oxidation deterioration test have a certain relationship.
[0123]
In addition, this publication only describes a method for measuring the degree of deterioration of a polypropylene resin molded article, and does not describe any method for recycling a thermoplastic resin composition waste material.
[0124]
In the present invention, in the determination step provided as necessary, the addition amount of the antioxidant is an antioxidant added to the thermoplastic resin composition waste material based on the measurement result of the oxidation induction period by the measurement step. Any method can be used as long as it is a method that can determine the amount of addition. Among these methods, since it is a simple and accurate method, particularly based on the information recorded in the database, the antioxidants required depending on the classification and use of the thermoplastic resin composition waste material. Obtain the required amount, and further, based on the information recorded in the database, from the measured value obtained in the above measurement step, obtain the remaining amount of antioxidant remaining in the thermoplastic resin composition waste material oxidation induction period, this It is preferable to determine the difference between the required amount and this remaining amount.
[0125]
In this case, the thermoplastic resin composition waste material is preferably classified based on the main thermoplastic resin system contained in the thermoplastic resin composition waste material. This is because, based on the main thermoplastic resin system, the content of the antioxidant to be included varies depending on the application.
[0126]
In this case, the necessary amount of the antioxidant for the thermoplastic resin composition waste material is required depending on the use of the thermoplastic resin composition molded article obtained by classification and recycling of the thermoplastic resin composition waste material. It is preferable that the content of the antioxidant is required according to the remaining life. That is, the required remaining life value is obtained by applying a certain relationship established between the content of the antioxidant in the thermoplastic resin composition waste and the remaining life. It is preferable.
[0127]
Furthermore, in this case, the remaining amount of the antioxidant remaining in the thermoplastic resin composition waste material is determined by using the measured value of the oxidation induction period obtained in the measurement step as the antioxidant in the thermoplastic resin composition waste material. It is preferable to be obtained by applying a certain relationship established between the residual amount of cis and the oxidation induction period.
[0128]
Then, the difference between the above required amount and the remaining amount is obtained, and an amount of antioxidant corresponding to the difference is added to the thermoplastic resin composition waste material in the addition step, and is heated and melted. By molding the plastic resin composition waste material, a thermoplastic resin composition molded body having the required antioxidant content can be obtained.
[0129]
As a specific example, the thermoplastic resin composition waste material is a resin composition waste material containing a polyolefin resin as a main component, the antioxidant is a phenolic antioxidant, and in the above determination step The measurement value of the oxidation induction period measured in the above measurement step is a (minute), the remaining amount of antioxidant in the thermoplastic resin composition waste is b (% (w / w)), and the necessity of the antioxidant When the amount is c (% (w / w)), b is obtained on the basis of the relational expression: b = 0.055loga−0.017, and a range of (c−b−0.05) or more. It is preferable to determine the addition amount of the antioxidant.
[0130]
Furthermore, the above-mentioned required amount c is d (hour) for the remaining life of the thermoplastic resin composition waste material, and e (hour) for the remaining life required for the thermoplastic resin composition molded product obtained by recycling. In this case, it is preferably determined based on the relational expression: c = 0.066 log (e / d).
[0131]
By adding an amount of an antioxidant determined based on these relational expressions to the thermoplastic resin composition waste, a thermoplastic resin composition molded article having a remaining life required depending on the application is obtained. Can do.
[0132]
Moreover, even when the thermoplastic resin composition waste material and the antioxidant are different in classification, it is preferable to obtain the above relational expression in advance. Furthermore, it is preferable to create a database in which those relational expressions are recorded.
[0133]
And by referring to the information recorded in such a database, the content (required amount) of the antioxidant required according to the classification and use of the thermoplastic resin composition waste material, and the thermoplastic resin composition It is preferable to determine the content (residual amount) of the remaining antioxidant in the waste material oxidation induction period.
[0134]
That is, in the determination step provided as necessary in the present invention, the addition amount of the antioxidant is obtained by classifying and recycling the thermoplastic resin composition waste material based on the information recorded in the database. The required amount of the antioxidant required depending on the use of the molded thermoplastic resin composition is obtained, and further, the thermoplastic resin composition is obtained from the measured values obtained in the measurement process based on the information recorded in the database. It is preferable to determine by determining the residual amount of the remaining antioxidant in the waste material oxidation induction period and determining the difference between the required amount and the residual amount.
[0135]
The amount of the antioxidant added may be determined by the operator himself / herself while referring to the information recorded in the database before adding the antioxidant. From this, the database is recorded in a storage device of an electronic computer, the thermoplastic resin composition waste obtained by classifying and recycling the above thermoplastic resin composition waste by a certain means, and the above-mentioned When the measured value of the oxidation induction period in the measurement process is input to the computer, the program in the computer refers to the information recorded in this database and automatically determines the addition amount of this antioxidant. It is preferable to do.
[0136]
<Addition of antioxidant>
The recycling method of the thermoplastic resin composition waste material of the present invention is, when necessary, an addition amount of the antioxidant determined in the determination step provided as necessary to the thermoplastic resin composition waste material. May be added and heated and melted.
[0137]
Here, in the addition step provided as necessary in the present invention, the addition of the antioxidant may be performed manually by manually measuring the addition amount of the antioxidant determined by the operator. However, from the viewpoint of productivity, it is preferable to measure by an automatic metering device connected to an electronic computer capable of determining the addition amount of the antioxidant, and to add by an automatic addition device.
[0138]
In addition to the thermoplastic resin composition waste material and the antioxidant, in the addition step provided as necessary in the present invention, an unused thermoplastic resin composition (in this specification, a virgin material is also used). May be added and melted by heating.
[0139]
In this way, by adding an unused thermoplastic resin composition to the thermoplastic resin composition waste material used in the present invention, molding a thermoplastic resin composition obtained by recycling from the thermoplastic resin composition waste material This is because the quality of the body can be further improved.
[0140]
Here, it is preferable that the unused thermoplastic resin composition is a thermoplastic resin composition of the same system as the thermoplastic resin composition which is a main component of the thermoplastic resin composition waste material.
[0141]
That is, as a specific example, when the main component of the thermoplastic resin composition waste is a polyolefin resin composition, it is desirable to add a polyolefin resin composition as an unused thermoplastic resin composition. .
[0142]
In this case, the unused thermoplastic resin composition to be added is adapted to the use and required characteristics of the thermoplastic resin composition molded body obtained by recycling from the thermoplastic resin composition waste material, It is preferable to select an appropriate type.
[0143]
In addition, the amount of the unused thermoplastic resin composition to be added is preferably from the aspect of the quality of the molded thermoplastic resin composition obtained by recycling from the thermoplastic resin composition waste material as the amount is larger. However, if it is too much, it is not preferable from the viewpoint of production cost and recycling rate.
[0144]
Therefore, the amount of the unused thermoplastic resin composition to be added is appropriately adjusted according to the required characteristics of the molded product to be recycled, and the thermoplastic resin composition waste material and the unused thermoplastic resin composition are adjusted. It is desirable to do.
[0145]
In addition, in the addition step in the present invention, in addition to the above-described components, the thermoplastic resin composition waste material further includes a heat stabilizer, a light stabilizer, an antistatic agent, a lubricant, a filler, a copper damage inhibitor, an antibacterial agent, You may add conventionally well-known additives, such as a coloring agent, as needed in the range which does not disturb the characteristic of the thermoplastic resin composition molded object obtained by recycling from this thermoplastic resin composition waste material. The timing for adding these additives is preferably when the raw materials are charged into an extrusion molding machine to be described later.
[0146]
Moreover, in the addition process in this invention, it is preferable to stir and mix the thermoplastic resin composition waste material heat-melted, after adding another component, so that the composition may become uniform.
[0147]
<Molding of molded thermoplastic resin composition>
The thermoplastic resin composition waste recycling method of the present invention is a thermoplastic resin composition molded article obtained by molding the thermoplastic resin composition waste material heated and melted in the addition step provided as necessary. It is preferable to provide a process.
[0148]
Here, in this specification, when it is described as a thermoplastic resin composition molded article, not only a thermoplastic resin composition molded article as a normal product or its parts, but also a thermoplastic molded into a certain shape. The resin composition raw material is also included.
[0149]
The heating and melting in the addition step in the present invention and the extrusion molding in the molding step in the present invention are not particularly limited as long as they are devices capable of heating and melting and extrusion molding, and are performed using any conventionally known device. However, in terms of productivity and the quality of the thermoplastic resin composition molded product obtained by recycling the thermoplastic resin composition waste, single-screw extruder, twin-screw extruder or multi-screw extruder It is particularly preferable to carry out using any extrusion molding machine.
[0150]
Further, in the molding step of the present invention, considering versatility, it is preferable to mold the thermoplastic resin composition raw material with a certain shape from the thermoplastic resin composition waste material that has been heated and melted. You may produce the thermoplastic resin composition molded object which has a fixed shape directly from a plastic resin composition waste material.
[0151]
Further, in the molding step of the present invention, the shape of the thermoplastic resin composition raw material obtained is preferably a pellet shape that is a general shape of the resin composition raw material, but is not particularly limited to a pellet shape, for example, It may be in the form of a sheet, a film, a pipe, etc., and may be determined as appropriate from the type of the extruder.
[0152]
In the molding step of the present invention, when the thermoplastic resin composition waste material that has been heated and melted is molded into a pellet-shaped thermoplastic resin composition material, a pellet-shaped thermoplastic resin composition material is produced. In addition to the above extruder, any cutting machine such as sheet cut, strand cut, hot air cut, underwater cut, etc. may be used. An underwater cut that can smoothly supply the raw material of the plastic resin composition and can cope with a large amount of processing is particularly preferable.
[0153]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.
[0154]
<Example 1>
A used washing machine collected from the market was dismantled, and a water tank, which is a molded product of a resin composition containing a polypropylene-polyethylene block copolymer resin, which is a typical crystalline thermoplastic resin, was taken out and pulverized. Next, the finely pulverized thermoplastic resin composition waste material was washed to remove dirt, dehydrated and dried, and then a predetermined amount of additives such as an antioxidant was added and mixed uniformly.
[0155]
Note that the amount of the antioxidant added is necessary to measure the oxidation induction period of the thermoplastic resin composition waste material and to realize the remaining life required for the molded thermoplastic resin composition from the measured value. It calculated | required by calculating the addition amount of antioxidant which becomes.
[0156]
Then, uniformly mixed thermoplastic resin composition waste powder is heated and melted, kneaded and extruded at a temperature of 190 ° C. using a screw system 45 mm biaxial melt kneading extruder, and an underwater cut device To produce recycled resin composition raw material pellets.
[0157]
Thereafter, the recycled resin composition raw material pellets are put into a hopper of a 10-ton injection molding machine, and are formed of a thermoplastic resin composition molded body under injection molding conditions of a heat melting temperature of 230 ° C. and a mold temperature of 40 ° C. A compliant physical property measurement specimen was prepared, and the physical properties and oxidative deterioration characteristics (oxidation induction period, crack generation time) were measured.
[0158]
Here, in this specification, among the test pieces for measuring physical properties in conformity with ASTM made of the thermoplastic resin composition molded body obtained from each part, the test piece derived from the water tank is also referred to as “RS”. And
[0159]
Further, for comparison, a test piece for measuring physical properties in accordance with ASTM (hereinafter referred to as “V-0”) using a general grade virgin material of a resin composition containing a polypropylene-polyethylene block copolymer resin. And the physical properties and oxidative deterioration characteristics (oxidation induction period, crack generation time) were measured. Table 3 shows the measurement results.
[0160]
On the other hand, the relationship between the lifetime of the thermoplastic resin and the oxidation induction period was investigated. FIG. 3 shows the relationship between the oxidation induction period and the thermal oxidative degradation test by adding an antioxidant to the thermoplastic resin composition waste and changing the type and amount of the resin composition raw material pellets. Is. Here, the thermal oxidative deterioration test was carried out in a gear type oven at 150 ° C., and the crack generation time was evaluated.
[0161]
As understood from FIG. 3, in the thermoplastic resin, a certain correlation was observed between the oxidation induction period and the lifetime. Therefore, the oxidative deterioration characteristic, that is, the life of the regenerated molded product due to the thermoplastic resin composition waste can be generally evaluated in the oxidation induction period.
[0162]
Table 3 shows the measurement results of the physical properties and oxidation deterioration characteristics (oxidation induction period, crack generation time) of the above-mentioned “RS” and “V-0”.
[0163]
[Table 3]

[0164]
As shown in Table 3, the tensile strength, bending strength, flexural modulus, Izod impact strength physical properties, oxidation induction period, and crack generation time of “RS” are approximately equivalent to “V-0”, respectively. Or more than that.
[0165]
<Example 2>
Similar to Example 1, a used washing machine recovered from the market is disassembled, and a water tank that is a molded product of a resin composition containing a polypropylene-polyethylene block copolymer resin, which is a typical crystalline thermoplastic resin Was taken out and pulverized. Next, the finely pulverized thermoplastic resin composition waste material was washed to remove dirt, dehydrated and dried, and then a predetermined amount of additives such as antioxidants were added and mixed uniformly.
[0166]
Note that the amount of the antioxidant added is necessary to measure the oxidation induction period of the thermoplastic resin composition waste material and to realize the remaining life required for the molded thermoplastic resin composition from the measured value. It calculated | required by calculating the addition amount of antioxidant which becomes.
[0167]
Then, uniformly mixed thermoplastic resin composition waste powder is heated and melted, kneaded and extruded at a temperature of 190 ° C. using a screw system 45 mm biaxial melt kneading extruder, and an underwater cut device To produce recycled resin composition raw material pellets.
[0168]
Here, in order to investigate the relationship between the foreign matters mixed in the recycled resin composition raw material pellets, the physical properties of the recycled molded body, and the oxidation deterioration characteristics, a mesh filter for removing foreign matters is disposed in the extruder, and the mesh filter And the amount of foreign matter mixed in the recycled resin composition raw material pellets was examined.
[0169]
The amount of foreign matter mixed in is measured by heating and melting recycled resin composition raw material pellets to produce a 220 mm x 220 mm x 1 mm press sheet, and visually observing it with reference to a dust measurement chart, etc. This was done by classifying it.
[0170]
Table 4 shows the relationship between the mesh filter openings provided in the extruder and the amount of foreign matter mixed in the recycled resin composition raw material pellets.
[0171]
[Table 4]

[0172]
As Table 4 shows, the amount of foreign matter mixed into the recycled resin composition raw material pellets decreases as the opening size of the foreign matter removal filter disposed in the extruder is reduced, and there is a significant effect around 0.2 mm. It was.
[0173]
<Example 3>
The relationship between the amount of foreign matter mixed in the recycled resin composition raw material pellets and the physical properties of the thermoplastic resin composition waste recycled material was investigated.
[0174]
After preparing the thermoplastic resin composition waste material finely pulverized in the same process as in Example 1, the thermoplastic resin composition waste material is subjected to extrusion molding by changing the cleaning level of the thermoplastic resin composition waste material, and individually regenerated for each cleaning level. Resin composition raw material pellets were prepared, and the relationship between the amount of foreign matter mixed in and physical properties was examined. The mesh filter provided in the extruder was set to 0.25 mm.
[0175]
The cleaning level is water washing (crushing the product into a net bag and washing with a washing machine), sieve washing (wire diameter 0.87 mm, mesh opening 3.36 mm, stainless steel sieve, and crushing product with a vibration type sieve. Was classified into three categories without washing.
[0176]
In the same manner as in Example 2, the measurement of the amount of foreign matter mixed was performed by heating and melting the recycled resin composition raw material pellets to produce a press sheet (220 mm × 220 mm × 1 mm), and referring to a dust measurement chart, etc. ² The above foreign materials were counted by visual observation.
[0177]
Table 5 shows the relationship between the amount of foreign matter mixed in recycled resin composition raw material pellets produced from a used washing machine water tank and the physical properties of ASTM-compliant physical property measurement test pieces produced from recycled resin composition raw material pellets. .
[0178]
[Table 5]

[0179]
As shown in Table 5, there is a correlation between the amount of foreign matter mixed in and the physical properties. When the amount of foreign matter mixed in increases, the physical properties change, and in particular, the tensile elongation decreases greatly.
Therefore, in order to stabilize the physical properties of the recycled molded body made of the thermoplastic resin waste material, it is important to control the amount of foreign matter mixed in the recycled product resin composition raw material pellet to a certain amount or less.
[0180]
<Example 4>
The relationship between the amount of foreign matter mixed in the recycled resin composition raw material pellets and the oxidative degradation characteristics of the recycled thermoplastic resin waste material was investigated. The sample used in the experiment was prepared with the recycled resin composition raw material pellets produced in Example 3.
[0181]
The amount of foreign matter mixed in is measured by heating and melting the recycled resin composition raw material pellets to produce a press sheet (220 mm x 220 mm x 1 mm), and visually observing it with reference to a dust measurement chart. This was done by classifying by size.
[0182]
Oxidation degradation characteristics were evaluated by putting recycled resin composition raw material pellets into a hopper of a 10-ton injection molding machine, and using thermoplastic resin composition waste material under injection molding conditions of a heating and melting temperature of 230 ° C and a mold temperature of 40 ° C After preparing an ASTM-compliant test piece for measuring tensile strength, a thermal oxidative deterioration test was carried out in a gear oven at 150 ° C., measuring the time until cracking occurred, and starting from a foreign material. This was done by determining the number of points of deterioration.
[0183]
Table 6 shows the relationship between the amount of foreign matter mixed in recycled resin composition raw material pellets prepared from a used washing machine water tank and the oxidative deterioration characteristics of ASTM-compliant physical property measurement specimens prepared from recycled resin composition raw material pellets. Indicates.
[0184]
[Table 6]

[0185]
As shown in Table 6, there is a correlation between the amount of foreign matter mixed in and the oxidation deterioration characteristics, and as the amount of foreign matter increases, the oxidation deterioration characteristics decrease. ² When the amount of the foreign matter mixed in increases, the local deterioration portion of the recycled thermoplastic resin waste material tends to greatly increase.
[0186]
Conventionally, foreign matters such as water scale and rust adhering to used products are mixed into a molded product made of used resin (hereinafter sometimes simply referred to as “recycled product”), resulting in deterioration of physical properties. It was known that it was causing
[0187]
However, the fact that there is a correlation between the amount of foreign matter mixed in and the oxidation degradation characteristics is the first clear in the present invention, and the technical idea of controlling the oxidation degradation characteristics by controlling the amount of foreign matter contamination. Is also proposed for the first time in the present invention.
[0188]
However, in this example, when the amount of foreign matter mixed in is large, local deterioration starting from the foreign matter becomes remarkable, so it is considered that the thermal oxidation deterioration at 150 ° C. was promoted, as shown in FIG. There was no correlation between thermal oxidative degradation at 150 ° C. and the oxidation induction period.
[0189]
Therefore, in order to stabilize the oxidative deterioration characteristics of the recycled molded body of the thermoplastic resin composition obtained from the thermoplastic resin composition waste material, it is necessary to control the amount of foreign matter mixed in the recycled resin composition raw material pellet to a certain amount or less. , Especially 0.3mm in size ² It is important to control the amount of foreign substances mixed to a certain amount or less.
[0190]
As can be understood from the above examples, the thermoplastic resin composition waste material recovered from the used product by performing lot management of the recycled resin composition raw material pellets with physical properties, the amount of foreign matter mixed and oxidation deterioration characteristics It is possible to obtain a thermoplastic resin composition molded product with high-quality characteristics from recycling, and expand the applications of thermoplastic resin composition molded products obtained by recycling from thermoplastic resin composition waste It becomes possible to expand.
[0191]
<Measurement method>
Various physical properties (tensile strength, bending strength, flexural modulus, Izod impact strength), oxidation induction period, and crack generation time measured in the above examples were measured according to the following measurement methods.
[0192]
(I) Measuring method of tensile strength and tensile modulus
Tensile strength and tensile elastic modulus were measured in accordance with JIS K7113 using ASTM-compliant physical property measurement test pieces.
[0193]
(Ii) Measuring method of bending strength and bending elastic modulus
Bending strength and bending elastic modulus were measured according to JIS K7203 using ASTM-compliant test pieces for measuring physical properties.
[0194]
(Iii) Measuring method of Izod impact strength
Izod impact strength was measured according to JIS K7110 using ASTM-compliant test specimens for measuring physical properties.
[0195]
(Iv) Method for measuring oxidation induction period
Using a test sample having a shape of φ4 mm and a thickness of 1 mm, measurement was performed using a thermal analyzer (manufactured by Seiko Denshi Kogyo Co., Ltd., TG / DTA320U). First, the test sample was heated to 210 ° C. in a nitrogen atmosphere, held for 10 minutes, then switched to an air atmosphere, and the time until the test sample started an exothermic reaction was measured as an oxidation induction period.
[0196]
(V) Method for measuring crack occurrence time
As an accelerated test for evaluating the oxidative deterioration characteristics, a thermal oxidative deterioration test is performed by leaving a test piece for measuring physical properties in accordance with ASTM in a gear-type oven at 150 ° C., measuring the time until a crack is generated, Alternatively, local degradation points were counted.
[0197]
(Vi) Measuring method of amount of foreign matter
Recycled resin composition raw material pellets were heated and melted to prepare a 220 mm × 220 mm × 1 mm press sheet, and the foreign substances to be mixed were classified and counted for each size by visual observation with reference to a dust measurement chart and the like.
[0198]
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0199]
【The invention's effect】
From the above results, the method for recycling the thermoplastic resin composition waste material according to the present invention was adapted to various uses by recycling the thermoplastic resin composition waste material from the thermoplastic resin composition waste material as a main raw material. It can be said that this is an efficient method of recycling a thermoplastic resin composition waste material that can obtain a molded product of a thermoplastic resin composition having quality and life.
[0200]
In addition, the method for producing the thermoplastic resin composition molded body of the present invention using the method for recycling the thermoplastic resin composition waste material of the present invention is a method for producing a thermoplastic resin composition waste material from a thermoplastic resin composition waste material. It can be said that this is a production method capable of obtaining a thermoplastic resin composition molded article having quality and longevity according to various uses by material recycling as a main raw material.
[0201]
The thermoplastic resin composition molded article of the present invention obtained by using the method for recycling the thermoplastic resin composition waste of the present invention is obtained by material recycling using the thermoplastic resin composition waste as the main raw material. It can be said that it is a thermoplastic resin composition molded article having quality and life according to various uses.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a conceptual diagram describing a graph showing an example of a general tendency of characteristic deterioration of a thermoplastic resin composition molded article.
FIG. 2 is a process diagram showing an example of a process flow of a method for recycling a thermoplastic resin composition waste material according to the present invention.
FIG. 3 is a graph showing an example of a correlation between an oxidation induction period and a crack generation time in an example of the present invention.

Claims (9)

A step of heat-melting the thermoplastic resin composition waste material, a step of controlling the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material by the particle size of the foreign material, and the heat-melted thermoplastic resin composition waste material And a step of obtaining a molded thermoplastic resin composition, and a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body,
In the step of heating and melting the thermoplastic resin composition waste material, an addition amount of an antioxidant to be added to the thermoplastic resin composition waste material is determined based on an evaluation result of oxidation deterioration characteristics of the thermoplastic resin composition waste material. The addition amount of the antioxidant determined to the thermoplastic resin composition waste material to be melted by heating is added,
The step of evaluating the oxidative degradation characteristics of the thermoplastic resin composition molded body is a process of evaluating the oxidative degradation characteristics of the thermoplastic resin composition molded body by measuring the oxidation induction period of the thermoplastic resin composition molded body. Including
The thermoplastic resin composition waste material is a resin composition waste material mainly composed of a polyolefin resin, and the antioxidant is a phenolic antioxidant,
The amount of the antioxidant added is
The measured value of the oxidation induction period is a (minute),
The residual amount of antioxidant in the thermoplastic resin composition waste material is b (% (w / w)),
C (% (w / w)) the required amount of the antioxidant,
D (hour) for the remaining life of the thermoplastic resin composition waste material,
E (time) is the remaining life required for the molded thermoplastic resin composition obtained by recycling.
As
Relational expression: b is obtained based on the formula of b = 0.55loga−0.017,
Relational expression: c is obtained based on the expression of c = 0.066 log (e / d),
(C-b-0.05) Ru determined by the above range, recycling a thermoplastic resin composition waste. The step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition waste material, the step of heating and melting the thermoplastic resin composition waste material, and the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material is determined as the particle size of the foreign matter. And a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body,
In the step of heating and melting the thermoplastic resin composition waste material, an addition amount of an antioxidant to be added to the thermoplastic resin composition waste material is determined based on an evaluation result of oxidation deterioration characteristics of the thermoplastic resin composition waste material. The addition amount of the antioxidant determined to the thermoplastic resin composition waste material to be melted by heating is added,
The thermoplastic resin composition waste material is a resin composition waste material mainly composed of a polyolefin resin, and the antioxidant is a phenolic antioxidant,
The step of evaluating the oxidative degradation characteristic includes a step of evaluating the oxidative degradation characteristic of the thermoplastic resin composition waste material by measuring an oxidation induction period of the thermoplastic resin composition waste material,
The amount of the antioxidant added is
The measured value of the oxidation induction period is a (minute),
The residual amount of antioxidant in the thermoplastic resin composition waste material is b (% (w / w)),
C (% (w / w)) the required amount of the antioxidant,
D (hour) for the remaining life of the thermoplastic resin composition waste material,
E (time) is the remaining life required for the molded thermoplastic resin composition obtained by recycling.
As
Relational expression: b is obtained based on the formula of b = 0.55loga−0.017,
Relational expression: c is obtained based on the expression of c = 0.066 log (e / d),
(C-b-0.05) Ru determined by the above range, recycling a thermoplastic resin composition waste.   The step of controlling the amount of foreign matter mixed by the particle size of the foreign matter includes a step of passing the heat-melted thermoplastic resin composition waste material through a foreign matter removing filter having an opening of 0.2 mm or less. The recycling method of the thermoplastic resin composition waste material as described in 1 above.   The method for recycling a thermoplastic resin composition waste material according to any one of claims 1 to 3, wherein the thermoplastic resin composition waste material is a thermoplastic resin composition waste material containing a polyolefin resin as a main component.   The thermoplastic resin composition waste material according to any one of claims 1 to 4, wherein the thermoplastic resin composition waste material is a thermoplastic resin composition waste material collected from a washing machine.   The manufacturing method of the thermoplastic resin composition molded object which obtains a thermoplastic resin composition molded object by the recycling method of the thermoplastic resin composition waste material in any one of Claims 1-5.   The method for producing a thermoplastic resin composition molded body according to claim 6, wherein the thermoplastic resin composition molded body is a thermoplastic resin composition molded body having a pellet shape.   A thermoplastic resin composition molded article obtained by the method for recycling a thermoplastic resin composition waste material according to any one of claims 1 to 5.   The thermoplastic resin composition molded body according to claim 8, wherein the thermoplastic resin composition molded body is a thermoplastic resin composition molded body having a pellet shape.

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