JP2004161906A - Method of recycling thermoplastic resin composition waste material, method for producing thermoplastic resin composition molding and the resultant molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently recycling thermoplastic resin composition waste materials, enabling to give thermoplastic resin composition molding with quality and service life coping with various applications to be obtained therefrom as the main feedstock. <P>SOLUTION: The method of recycling the thermoplastic resin composition waste materials comprises the steps of heating and melting the waste materials, controlling the amounts of contamination of the molten waste materials with foreign matter based on foreign matter particle size, obtaining a thermoplastic resin composition molding by molding the molten waste materials, and evaluating the oxidative deterioration characteristics of the molding. <P>COPYRIGHT: (C)2004,JPO

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）０．３ｍｍ^２以上の異物がないことが好ましく、さらに大きさ（表面積）０．２〜０．３ｍｍ^２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・，ＲＯ_２・）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、０．３ｍｍ^２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０．３ｍｍ^２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０．３ｍｍ^２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]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for recycling thermoplastic resin composition waste. More specifically, the present invention manages the quality of the thermoplastic resin composition molded product of the thermoplastic resin composition waste material by evaluating the oxidative deterioration characteristics and reducing the amount of foreign matter mixed therein. About the method.
[0002]
The present invention also relates to a method for producing a thermoplastic resin molded article by the above-mentioned recycling method. Further, the present invention also relates to a molded article of the thermoplastic resin composition obtained by the above-mentioned recycling method.
[0003]
[Prior art]
In recent years, in Japan, with the increase in income level, home appliances such as air conditioners (also referred to as air conditioners in this specification), television receivers (also referred to as televisions in this specification), refrigerators, washing machines, and the like. Information devices such as personal computers and word processors, office equipment such as printers and fax machines, and various other furniture, stationery, and toys have become increasingly popular in ordinary households. Sex is improving dramatically.
[0004]
On the other hand, as a result, the amount of disposal of these home appliances and other products tends to increase year by year. Heretofore, the recycling of waste materials of these home appliances and other products has often been carried out through iron scrap collection routes.
[0005]
However, in recent years, constituent materials of members of various products such as home appliances have changed, and members made of metal such as iron have been decreasing, and the proportion of members made of a plastic composition has tended to increase. Plastic compositions have more design freedom than metals such as iron, and can provide various properties that are difficult to achieve with metals by preparing constituent components and using additives, and are lightweight and durable. This is because it has many advantages such as high performance.
[0006]
And, in recent years, waste materials of various products including home appliances, the material composition of various constituent members is complicated, the ratio of members made of valuable metals such as iron and copper is small, and the value is low, In addition, in the conventional processing method, the ratio of the member made of the plastic composition, which requires a great deal of labor and cost, is large, and it is not profitable to recycle such waste materials in the conventional iron scrap collection route. It is becoming a difficult situation to deal with.
[0007]
Many members made of these plastic compositions are synthesized using buried fossil fuels such as crude oil as basic raw materials. From the viewpoint of effective use of resources, products having members made of these plastic compositions are often 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 emission of carbon dioxide and sulfur oxides due to the burning of buried fossil fuels such as crude oil, and environmental pollution such as dioxin generation and scattering due to the incineration of plastic compositions containing chlorine compounds In addition, from the viewpoint of suppressing the problem of shortage of garbage landfills due to an increase in waste materials containing a bulky plastic composition, the recycling of waste materials of products provided with members made of these plastic compositions has been promoted. It is becoming an important and urgent issue.
[0009]
In this specification, a member made of a plastic composition is also referred to as a plastic member. Further, in this specification, a product provided with a plastic member is also referred to as a plastic product. Furthermore, in this specification, waste plastic products are also referred to as plastic waste.
[0010]
Here, 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, four types of home appliances such as air conditioners, televisions, refrigerators, and washing machines must be recycled. %, Television 55% or more, refrigerator 50% or more, and washing machine 50% or more.
[0011]
In response to the enforcement of the above-mentioned Home Appliance Recycling Law, the collection of plastic waste has been progressing, but as a method of recycling the collected plastic waste, the so-called plastic waste as fuel is used. Methods related to thermal recycling have been widely used. However, such a method can recycle plastic waste materials by thermal recycling, but it has problems such as the generation of carbon dioxide gas due to combustion. I can't say.
[0012]
Therefore, from the collected plastic waste material, plastic members are separated for each system of the plastic composition by a method such as manual dismantling, and the plastic members are again processed into product members or raw materials for use. A method of recycling plastic waste materials 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 waste material in this specification) is heated and melted. Then, the material can be recycled relatively easily by molding again.
[0014]
Therefore, in order to increase the ratio of material recycling of plastic waste material, research and development of a method of recycling thermoplastic resin composition waste material by material recycling are being carried out with great efforts in various fields.
[0015]
However, waste thermoplastic resin compositions, especially those used in home appliances and office equipment, are often used in harsh environments for long periods of time. In many cases, the material is poor in durability because not only the appearance quality such as discoloration or fading, but also the physical properties such as strength and flexibility are deteriorated.
[0016]
Therefore, the thermoplastic resin composition waste is not used as a substitute for the virgin material of the thermoplastic resin composition used for a plastic member having high required characteristics, but is often used as a raw material for a plastic member having low required characteristics.
[0017]
At present, such cascade recycling is the mainstream as material recycling of waste thermoplastic resin compositions. For this reason, there is a problem that the use of the molded article of the thermoplastic resin composition regenerated from the waste thermoplastic resin composition is limited.
[0018]
Here, in this specification, the virgin material means an unused resin composition. Further, in the present specification, the waste plastic material having deteriorated quality is not used as a substitute for a virgin material of a thermoplastic resin composition used for a plastic member having high required characteristics, but as a raw material of a plastic member having low required characteristics. , Cascade recycling.
[0019]
In order to overcome such a problem, the quality of the thermoplastic resin composition molded article obtained by material recycling from the above-described thermoplastic resin composition waste material has been improved to a level that can be used as a plastic member having high required characteristics. Many research and development efforts are being made to reach them.
[0020]
For example, many methods have been proposed for maintaining quality by mixing a virgin material with a thermoplastic resin composition waste material (material recycled material) (for example, see Patent Document 1).
[0021]
However, in such a material recycling method, although the physical properties are improved with the mixing of the virgin material, as long as the thermoplastic resin composition waste material whose physical properties have been reduced is mixed, the physical properties equivalent to the virgin material can be restored. Impossible. In addition, in order to approximate the physical properties of the virgin material, it is often necessary to mix a larger amount of virgin material than the thermoplastic resin composition waste material, and it is difficult to say that it is compatible with a resource recycling society. is there. Further, even if the thermoplastic resin composition waste material does not deteriorate in physical properties, its life is greatly reduced by long-term use, and there is a problem in long-term reliability when reused.
[0022]
On the other hand, there is also disclosed a technology of a recycling system in which a recycling measure is determined based on the components and the degree of deterioration of a used product and the resource is repeatedly recycled (for example, see Patent Document 2).
[0023]
However, in this recycling system, the degree of deterioration, which is a criterion for determining a measure, is based on physical properties that can be determined by comparison with a virgin material, and only when the initial characteristics of the recovered waste material are known. Becomes effective. However, the amount of waste material actually collected is enormous, and it takes enormous amount of time and processing capacity to grasp the initial characteristics of each and to compare the characteristics of waste materials with their initial characteristics one by one. Actually, there is a problem that realization of such a recycling system involves difficulty and is disadvantageous in terms of cost.
[0024]
Also, parts used inside waste products are less susceptible to light, etc. than parts used for appearance, so the degree of apparent deterioration is low, and the difference in physical property values is significant. In some cases, the progress of the game may not appear. Therefore, in such a recycling system, there is a problem that even though the material composition of the waste material can be identified, it is difficult to sort the materials according to the degree of deterioration.
[0025]
[Patent Document 1]
JP 2000-159900 A
[0026]
[Patent Document 2]
JP-A-7-24437
[0027]
[Problems to be solved by the invention]
As described above, from the thermoplastic resin composition waste recovered from the market, material recycling using the thermoplastic resin composition waste as a main raw material has a quality that can be used as a plastic member with high required properties or its raw material. Efficient and low-cost thermoplastic resin composition capable of obtaining a molded article of a thermoplastic resin composition having a life as a product equivalent to a virgin material (hereinafter simply referred to as life). Despite the strong demand for the development of a method for recycling waste materials, such a recycling method has not yet been publicly known.
[0028]
Based on the above current situation, an object of the present invention is to provide a thermoplastic resin composition having a quality and a life corresponding to various uses by recycling the thermoplastic resin composition waste material as a main material from the thermoplastic resin waste material. An object of the present invention is to provide a method for efficiently recycling waste thermoplastic resin composition, which can obtain a molded article.
[0029]
Another object of the present invention is to form a thermoplastic resin composition having a quality and a life corresponding to various uses by recycling the thermoplastic resin composition waste material as a main material from the thermoplastic resin waste material. The object is to provide a method for producing the body.
[0030]
Still another object of the present invention is to provide a molded article of a thermoplastic resin composition having quality and life corresponding to various uses, which is obtained by material recycling using waste thermoplastic resin composition as a main raw material. It is to be.
[0031]
[Means for Solving the Problems]
The present inventors have obtained the idea that in order to solve the above-mentioned problems, it is only necessary to improve and stabilize the quality of pellets made of waste thermoplastic resin composition and to stabilize such pellets. In order to develop a method of recycling waste materials, we prepare thermoplastic resin composition molded products in the form of raw pellets obtained from many types of thermoplastic resin composition waste materials, and have many oxidation deterioration characteristics and foreign material contamination An experiment was conducted on a thermoplastic resin composition molded article having a combination of the above, and intensive studies were repeated.
[0032]
After the examination, 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 diameter of the foreign matter. A thermoplastic resin composition molded article may be obtained from the molten thermoplastic resin composition waste material, and the oxidative deterioration characteristics of the raw material pellet-shaped thermoplastic resin composition molded article obtained from the thermoplastic resin composition waste material may be evaluated. I found that.
[0033]
Further, the present inventors evaluated the oxidative deterioration characteristics of the thermoplastic resin composition waste material, heat-melt the thermoplastic resin composition waste material, and determine the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material. The present inventors have found that a molded article of a thermoplastic resin composition may be obtained from the waste thermoplastic resin composition melted by heating by controlling the particle diameter 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 determined the amount of foreign materials mixed in the thermoplastic resin composition waste material with an eye of the foreign matter removal filter. The inventor has found that it is only necessary to control the aperture size, and completed the present invention.
[0035]
Here, when a large amount of foreign matter such as water scale and rust attached to the plastic waste material is mixed into a plastic molded body made of the plastic waste material (hereinafter, sometimes simply referred to as “recycled product”), the plastic molding is performed. It has been suggested by a conventionally known empirical fact that it causes a decrease in physical properties of the body.
[0036]
However, it is not known heretofore that there is a correlation between the amount of contaminants and the oxidative deterioration characteristics in the waste thermoplastic resin composition, and it has been first clarified in the present invention. The present invention has also revealed for the first time that it is possible to improve the oxidative deterioration characteristics of the thermoplastic resin composition waste material and extend the life thereof by controlling the amount of the foreign material mixed in accordance with the particle size of the foreign material. is there.
[0037]
In other words, the method for recycling thermoplastic resin composition waste material of the present invention comprises the steps of heating and melting the thermoplastic resin composition waste material, and determining the amount of foreign matter mixed in the heat-melted thermoplastic resin composition waste material by the particle size of the foreign matter. A step of controlling the diameter, a step of forming the thermoplastic resin composition waste material heated and melted to obtain a thermoplastic resin composition molded article, and a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded article And a method of recycling thermoplastic resin composition waste.
[0038]
Here, the step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body includes 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 a step of evaluating.
[0039]
Further, the method for recycling thermoplastic resin composition waste material of 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 a heating step. A step of controlling the amount of foreign matter mixed in the melted thermoplastic resin composition waste material by 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 And a method for recycling thermoplastic resin composition waste.
[0040]
Here, it is preferable that the step of evaluating the oxidative deterioration characteristics includes a step of evaluating the oxidative deterioration characteristics of the waste thermoplastic resin composition by measuring the oxidation induction period of the waste thermoplastic resin composition.
[0041]
And in any of the above-mentioned methods for recycling thermoplastic resin composition waste material, the step of evaluating the oxidative deterioration characteristic includes the step of evaluating the oxidative deterioration characteristic of this thermoplastic resin composition waste material by using the thermoplastic resin composition waste material. It is preferable to include a step of evaluating by measuring the oxidation induction period.
[0042]
In addition, the step of controlling the amount of foreign matter mixed based on the particle diameter of the foreign matter desirably includes a step of passing the heat-melted thermoplastic resin composition waste material through a foreign matter removing filter having a mesh size of 0.2 mm or less.
[0043]
Further, it is recommended that the waste thermoplastic resin composition is a waste thermoplastic resin composition containing a polyolefin-based resin as a main component. And this thermoplastic resin composition waste material may be the thermoplastic resin composition waste material collected from the washing machine.
[0044]
In addition, the present invention includes a method for producing a molded article of a thermoplastic resin composition, wherein the molded article of a thermoplastic resin composition is obtained by the above-mentioned method for recycling waste thermoplastic resin composition. Here, the molded article of the thermoplastic resin composition may be a molded article of the thermoplastic resin composition having a pellet-like shape.
[0045]
Further, the present invention includes a molded article of the thermoplastic resin composition obtained by the above-described method for recycling waste thermoplastic resin composition. Here, the molded article of the thermoplastic resin composition may be a molded article of the thermoplastic resin composition having a pellet-like shape.
[0046]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0047]
<Summary of recycling method of waste thermoplastic resin composition>
The thermoplastic resin composition waste material recycling method of the present invention is 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 is determined by the particle size of the foreign matter. Controlling, and a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body, and a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body, It is a method of recycling thermoplastic resin composition waste materials, comprising:
[0048]
Alternatively, the method for recycling thermoplastic resin composition waste material of 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 step. 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 matter, and a step of molding the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body; And a method for recycling thermoplastic resin composition waste.
[0049]
Here, when a large amount of foreign matter such as water scale and rust attached to the plastic waste material is mixed into a plastic molded body made of the plastic waste material (hereinafter, sometimes simply referred to as “recycled product”), the plastic molding is performed. It has been suggested by a conventionally known empirical fact that it causes a decrease in physical properties of the body.
[0050]
However, it is not known heretofore that there is a correlation between the amount of contaminants and the oxidative deterioration characteristics in the waste thermoplastic resin composition, and it has been first clarified in the present invention. In addition, the present invention has also revealed for the first time that it is possible to improve the oxidative deterioration characteristics of the thermoplastic resin composition waste material and extend the life thereof by controlling the amount of the foreign material mixed according to the size of the foreign material. is there.
[0051]
In addition, conventionally, when manufacturing a plastic molded body using a virgin material, physical properties are measured, and necessary stabilization processing such as adding an antioxidant is performed according to characteristics required for the plastic molded body. Was normal.
[0052]
However, the method for recycling thermoplastic resin composition waste material of the present invention, in addition to measuring the physical properties of the thermoplastic resin composition waste material, measures the oxidative deterioration characteristics and the amount of foreign material mixed, and determines the amount of foreign material mixed according to the particle size of the foreign material. This is different from the conventionally known technology in that the quality is improved and the stability is improved, including the extension of the life by adding an antioxidant when necessary, by performing the above control.
[0053]
<Waste of thermoplastic resin composition>
The thermoplastic resin composition waste used in the present invention is obtained by using the thermoplastic resin waste recycling method of the present invention to obtain a thermoplastic resin composition molded article having the same physical properties and life as a virgin material. Can be used any conventionally known thermoplastic resin composition waste material, for example, a polypropylene resin, a polyethylene resin, a thermoplastic resin composition mainly containing a thermoplastic polyester resin and the like Waste materials can be suitably used.
[0054]
Also, among these thermoplastic resin composition waste materials, the thermoplastic resin composition waste materials containing a polyolefin resin such as a polyethylene resin or a polypropylene resin as a main component, as shown in Table 1 below, are used in the present invention. Thermoplastic resin composition molded articles that have been recycled using the method of recycling thermoplastic resin waste materials of the above, in terms of processability, economical efficiency, etc., from thermoplastic resin composition waste materials of other classifications 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 thermoplastic resin composition waste material recycling method of the present invention. .
[0055]
In addition, in the method for recycling thermoplastic resin composition waste material of the present invention, the properties of the thermoplastic resin composition waste material containing a polyolefin resin as a main component are improved by adding various additives such as an antioxidant. Since it is easy to carry out, there is also an advantage that a molded article of a thermoplastic resin composition 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.
×: Poor.
[0058]
<Oxidative degradation characteristics of waste thermoplastic resin composition>
First, FIG. 1 is a conceptual diagram showing a general tendency of characteristic deterioration of a molded article of a thermoplastic resin composition. As shown in FIG. 1, the thermoplastic resin composition molded article generally has a tendency to rapidly deteriorate in properties after a deterioration induction period inherent to the thermoplastic resin. The deterioration induction period corresponds to the life of the molded article of the thermoplastic resin composition, and the life of the molded article of the thermoplastic resin composition is generally determined by the oxidative deterioration characteristics.
[0059]
As can be understood from FIG. 1, the waste thermoplastic resin composition recovered from the market has a long service life due to long-term use, even if its properties cannot be confirmed by a physical property test such as measurement of tensile strength. In many cases, and the oxidative deterioration characteristics are often reduced.
[0060]
That is, some thermoplastic resin composition waste recovered from the market has a shorter remaining life due to heat, light, or the like than in manufacturing. These thermoplastic resin composition waste materials can be reused as they are for parts made of a low-grade molded article of the thermoplastic resin composition, but in order to develop more applications, the recycled resin raw material must be used. From the viewpoint of improving the recycling efficiency, it is preferable to improve the quality and stabilize the product so that it can be applied to a part made of a molded product of a medium-grade or high-grade thermoplastic resin composition.
[0061]
For example, when the waste thermoplastic resin composition is recovered from the market at the time indicated by A in FIG. 1, when this waste thermoplastic resin composition is recycled as a recycled material, the remaining life becomes the length shown in period B. Therefore, it cannot be used as a molded article of a thermoplastic resin composition requiring durability or high performance.
[0062]
The evaluation of the oxidative deterioration characteristics of the molded article of the thermoplastic resin composition is generally performed by performing a thermal oxidative deterioration test in a gear oven at about 150 ° C. until the characteristics of the molded product are reduced, for example, until cracks occur. By measuring the time. However, in this test method, it takes several hundred hours to obtain an evaluation result, and when applied to a method for recycling thermoplastic resin composition waste material, the productivity of the recycling method must be reduced. There is a problem that it cannot be obtained.
[0063]
Further, as shown in FIG. 1, the deterioration of the properties (for example, physical properties such as tensile strength) of the thermoplastic resin composition waste material at the time of recovery is very small, and the reduction of the remaining life is evaluated by measuring specific physical properties. It is difficult to do.
[0064]
Here, in the process of completing the present invention, as described later, the present inventors have found that the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the life in the thermal oxidation deterioration test have a constant relationship. Was found to have. That is, it has been found that the lifetime of the waste thermoplastic resin composition can be evaluated by measuring the oxidation induction period of the waste thermoplastic resin composition.
[0065]
Therefore, in the present invention, instead of performing a thermo-oxidative deterioration test, by measuring the oxidation induction period of the thermoplastic resin composition waste material, the life of the thermoplastic resin composition waste material recovered from the market can be simplified and We decided to evaluate it quickly.
[0066]
Here, used products such as home appliances and office equipment are often used for a long time in a harsh environment, and foreign materials such as water scale and rust adhere to the waste thermoplastic resin composition. . When these foreign substances are mixed in the recycled resin pellets, the oxidation deterioration characteristic of the recycled molded article is greatly reduced starting from the foreign substances, as has become clear for the first time in the present invention.
[0067]
Table 2 shows the results of analyzing foreign substances adhering to the water tub 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, detergent, soap scum, dirt components such as proteins, water scale, rust, a rubber-based adhesive, etc. adhere 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 waste thermoplastic resin composition on the physical properties and oxidative deterioration characteristics, as described later. As a result, when the value of the oxidation induction period of the thermoplastic resin composition waste material is substantially constant, the amount of foreign matter mixed in the thermoplastic resin composition waste material and the value of the remaining life in the thermooxidative deterioration test are constant. I found that they had a relationship. That is, when the value of the oxidation induction period 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. Can be controlled.
[0071]
That is, in the present invention, a foreign matter removing filter having a specific opening size is used, and the amount of foreign matter mixed in the thermoplastic resin composition waste material is controlled by the size of the foreign matter, thereby being recovered from the market. The remaining life of the thermoplastic resin composition waste material can be easily and accurately controlled.
[0072]
That is, in the present invention, a foreign matter removal method, and further, a lot management method for managing the quality of a raw material pellet-shaped thermoplastic resin composition molded article obtained from the thermoplastic resin composition waste material, and found a thermoplastic resin composition. It was decided to improve the quality of the molded body and obtain stability.
[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 used. In addition to heat-melting and molding the added thermoplastic resin composition waste material, the amount of foreign material mixed in the thermoplastic resin composition waste material is determined by using a foreign material removal filter having a specific opening size. By controlling the size of the thermoplastic resin composition, a molded article of a thermoplastic resin composition having a remaining life equivalent to that of a molded article of a thermoplastic resin composition using a virgin material as a main raw material may be obtained.
[0074]
In this case, the method for recycling thermoplastic resin composition waste material of 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 the amount of the antioxidant to be added to the waste material; a step of adding the determined amount of the antioxidant to the thermoplastic resin composition waste material to heat and melt; and A step of controlling the amount of foreign matter mixed in the thermoplastic resin composition waste according to the size of the foreign matter; and a step of molding the heated and melted thermoplastic resin composition waste to obtain a thermoplastic resin composition molded body. Is preferred.
[0075]
<Process flow>
An example of the process flow of the method for recycling thermoplastic resin composition waste according to the present invention will be described with reference to the process diagram shown in FIG. FIG. 2 is a process chart showing an example of a process flow of the method for recycling thermoplastic resin composition waste according to the present invention.
[0076]
Here, in a conventional general method of recycling 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 often used as a recycled material.
[0077]
At this time, in general, the virgin material is formed into pellets after measuring only the physical properties. However, in the method for recycling the thermoplastic resin composition waste material of the present invention, in addition to the physical properties, evaluation of oxidative deterioration characteristics and contamination of foreign materials are performed. The quantity is measured to improve and stabilize the quality. The evaluation of the oxidative deterioration characteristics is performed by measuring the oxidation induction period.
[0078]
Specifically, in the measurement of the oxidation induction period, the test sample of the waste thermoplastic resin composition was placed in a nitrogen atmosphere, and then the temperature of the nitrogen atmosphere was raised to a predetermined holding temperature at a constant rate. Thereafter, it is preferable that the nitrogen atmosphere is replaced with an oxygen atmosphere, and then the isothermal holding is performed at the holding temperature, and the oxidation induction period until the heat generation peak of the waste thermoplastic resin composition appears is measured.
[0079]
In the process flow shown in FIG. 2, first, a product including the thermoplastic resin composition waste material is recovered from the market (Step 101), and then the product including the thermoplastic resin composition waste material is manually dismantled or the like. It is disassembled (step 102), and the thermoplastic resin composition waste is separated. Then, the separated thermoplastic resin composition waste material is shredded and crushed into a powdery material (Step 103), washed to substantially remove dirt and impurities (Step 104), dehydrated, and dried (Step 104). Step 105). Then, the washed powdery material of the thermoplastic resin composition waste material is uniformly mixed by adding a predetermined amount of an additive (such as an antioxidant) (Step 106), and then heated and melted, kneaded, and extruded. (Step 107), it is processed into pellets of a fixed shape (Step 108).
[0080]
In this way, the thermoplastic resin composition waste once molded into a certain shape is subjected to the oxidative deterioration property and the foreign matter in a step of evaluating the oxidative deterioration property and the amount of foreign matter mixed (hereinafter also referred to as a lot management step). The mixing amount is evaluated (Step 109), and the mixture is molded into a thermoplastic resin composition molded article having a predetermined shape (Step 110). In the above lot management process, general physical properties may be evaluated in addition to the oxidative deterioration characteristics and the amount of contaminants. The above is an example of the process flow of the thermoplastic resin composition waste material recycling method of the present invention shown in FIG.
[0081]
FIG. 2 is a view showing an example of a process flow of the method for recycling thermoplastic resin composition waste according to the present invention. The method for recycling thermoplastic resin composition waste according to the present invention is shown in FIG. It is not limited to the flow.
[0082]
In other words, in the flow of the process shown in FIG. 2, the evaluation of the physical properties, oxidative deterioration characteristics and the amount of foreign substances mixed in the thermoplastic resin composition waste material is performed by temporarily heating and melting the thermoplastic resin composition waste material and extruding it into a predetermined shape. The timing of the evaluation of the physical properties of the thermoplastic resin composition waste material, the oxidative deterioration characteristics and the amount of contaminants mixed therein is not particularly limited, and the process of the method for recycling the thermoplastic resin composition waste material of the present invention is not particularly limited. May be performed at different timings in the flow.
[0083]
For example, without heating and melting the recovered thermoplastic resin composition waste material once and extruding it into a predetermined shape, the recovered thermoplastic resin composition waste material is disassembled, shredded, crushed, washed, Immediately, the physical properties, the oxidative deterioration characteristics, and the amount of contaminants may be evaluated.
[0084]
Further, the method for recycling waste thermoplastic resin composition of the present invention does not need to include all the steps shown in FIG. 2, and may omit some of the steps, or may include the steps shown in FIG. 2. Steps other than the above may be added.
[0085]
<Removal of foreign matter from thermoplastic resin composition waste>
In the method for recycling thermoplastic resin composition waste according to the present invention, the step of removing foreign matter (the step of controlling the amount of foreign matter mixed according to the size of the foreign matter) is performed using the heat-melted thermoplastic resin composition waste. It is preferable to include a step of passing through a filter for removing foreign substances having an opening of 0.2 mm or less.
[0086]
Further, in the method of recycling the thermoplastic resin composition waste material of the present invention, the removal of foreign material mixed amount of the thermoplastic resin composition waste material, mainly, a step of washing the thermoplastic resin composition waste material with water, It is preferably performed in a step of extruding the resin composition waste material after heating and melting the waste material. That is, it is desirable that after the water-soluble foreign matter is removed in the washing step, the attached foreign matter is further removed by a foreign matter removing mesh filter provided in the extruder in the extrusion molding step.
[0087]
Here, the measurement of the amount of foreign matter mixed is performed by molding a thermoplastic resin composition in the form of a raw material pellet made of the thermoplastic resin composition obtained by extruding the thermoplastic resin composition waste material after heating and melting the waste material. It is preferable that the pressing is performed by heating and melting the body to prepare a press sheet, and visually observing with reference to a dust measurement chart or the like to classify the foreign substances to be mixed according to size.
[0088]
In the method for recycling the thermoplastic resin composition waste material of the present invention, as a result of controlling the amount of foreign matter mixed according to the size of foreign matter using a foreign matter removing filter or the like, it is included in the obtained thermoplastic resin composition molded body. The amount of foreign matter mixed is 0.3 mm in size (surface area) ² It is preferable that there is no such foreign matter, and the size (surface area) is 0.2 to 0.3 mm. ² Is preferably 10 pieces / sheet (220 mm × 220 mm × 1 mm) or less. If the amount of foreign matter mixed 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 shortened due to local deterioration caused by the foreign matter.
[0089]
At this time, it is preferable that the extruder is provided with a filter for removing foreign matters through which the thermoplastic resin composition waste material that has been heated and melted is passed. However, the portion provided with the filter for removing foreign matter is not limited to the extruder, as long as it is a place where the amount of foreign matter mixed can be controlled by the size of the foreign matter through the heat-melted thermoplastic resin composition waste material. It may be provided at any place.
[0090]
The opening of the foreign matter removing filter is preferably 0.1 mm or more. Further, the opening of the foreign matter removing filter is preferably 0.2 mm or less. If the opening is smaller than this, clogging by fine foreign matter frequently occurs, and the productivity tends to decrease. If the opening is larger than this, the thermoplastic resin composition molded body There is a tendency that the location of local deterioration greatly increases.
[0091]
Here, the extrusion molding machine in the present invention is not particularly limited as long as it can be provided with a mesh filter for removing foreign substances, and can be further heated and melted, and can be extrusion molded, and any conventionally known apparatus can be used. Can be suitably used. In addition, from the viewpoint of productivity and the quality of the molded thermoplastic resin composition obtained by recycling the waste thermoplastic resin composition, a single-screw extruder, a twin-screw extruder, or a multi-screw extruder may be used. It is particularly preferable to use any one of the extruders.
[0092]
In addition, in the step of extrusion molding in the present invention, in consideration of 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, A thermoplastic resin composition molded article having a certain shape may be directly formed from the thermoplastic resin composition waste material.
[0093]
Further, in the molding step of 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 the pellet shape, for example, a sheet Shape, film shape, pipe shape, and the like, and may be appropriately determined from the type of the extruder.
[0094]
And, in the extrusion molding step in the present invention, when the thermoplastic resin composition waste material that is heated and melted is formed into a pellet-shaped thermoplastic resin raw material, the pellet-shaped thermoplastic resin raw material is produced by the above-described method. In addition to the extruder, any cutting machine such as a sheet cut, a strand cut, a hot air cut, and an underwater cut may be used. In the case where an extrusion molding step is further provided in the subsequent step, underwater cutting which can smoothly supply the thermoplastic resin material and can cope with a large amount of processing is particularly preferable.
[0095]
<Evaluation of oxidation deterioration characteristics>
The step of evaluating the oxidative deterioration characteristics of the present invention preferably includes a step of evaluating the oxidative deterioration characteristics of the waste thermoplastic resin composition by measuring the oxidation induction period of the waste thermoplastic resin composition.
[0096]
Here, the oxidative deterioration characteristics of the thermoplastic resin composition molded body are generally measured by performing a thermal oxidative deterioration test in a gear oven at about 150 ° C. until the characteristics of the molded product decrease, for example, until cracks occur. This is done by measuring time. Here, in this specification, the time up to the occurrence of the crack is also referred to as “crack occurrence time”. In the technical field to which the present invention belongs, the above-described thermal oxidation deterioration test is considered to be one of accelerated tests for examining the life of these thermoplastic resins, and this “crack generation time” is It is common technical knowledge to indicate a value corresponding to the life.
[0097]
However, in the thermal oxidation deterioration test, several hundred hours are required to obtain an evaluation result, and when applied to a method for recycling thermoplastic resin composition waste material, the productivity of the recycling method cannot be reduced. There is a problem that it is not obtained.
[0098]
Here, the measurement of the oxidation induction period of the waste thermoplastic resin composition in the present invention is not particularly limited, and can be measured by any measurement method as long as the method can accurately measure the oxidation induction period. However, since it is a simple and accurate measurement method, in particular, the waste thermoplastic resin composition is placed in a nitrogen atmosphere, and then the temperature of the nitrogen atmosphere is raised to a predetermined holding temperature at a constant speed, and then the nitrogen atmosphere is removed. Is preferably replaced by an oxygen atmosphere, and the temperature is kept isothermally at the holding temperature, and the oxidation induction period until the exothermic peak of the waste thermoplastic resin composition appears is measured. 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 of recycling the thermoplastic resin composition waste material of 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 the antioxidant in the molded article of the plastic resin composition is sufficient, the antioxidant effect is large, it is difficult to oxidize at a predetermined holding temperature in an oxygen atmosphere, and the time until an exothermic peak appears, that is, oxidation induction Periods tend to be long.
[0100]
In the method for recycling thermoplastic resin composition waste material according to the present invention, the thermoplastic resin composition molded body obtained from the thermoplastic resin composition waste material does not have sufficient oxidative deterioration characteristics. The amount of the antioxidant in the molded product of the composition is small, so that the antioxidant effect is small, and it is easily oxidized at a predetermined holding temperature in an oxygen atmosphere. Tend to be.
[0101]
Therefore, when the oxidative deterioration characteristics of the thermoplastic resin composition molded article obtained from the thermoplastic resin composition waste material are sufficient, the oxidation induction period becomes longer, and the thermoplastic resin composition obtained from the thermoplastic resin composition waste material becomes longer. It can be said that when the oxidation deterioration characteristics of the molded article are insufficient, the oxidation induction period tends to be short.
[0102]
Here, when the measurement step of the oxidation induction period is provided in the present invention, if the remaining life of the thermoplastic resin composition waste material still remains sufficiently, the oxidation prevention in the thermoplastic resin composition waste material is prevented. Since the residual amount of the agent is still large enough, the oxidation induction period tends to be long in an oxygen atmosphere due to a large antioxidant effect.
[0103]
Further, when 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 does not remain much, the remaining amount of the antioxidant in the thermoplastic resin composition waste material is reduced. Since the amount is small, the antioxidant effect is small, so it is easily oxidized at a predetermined holding temperature in an oxygen atmosphere, and the time until an 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 also 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 that.
[0105]
Similarly, in this case, when the residual amount of the antioxidant in the thermoplastic resin composition waste material is large, the oxidation induction period also becomes longer, and the residual amount of the antioxidant in the thermoplastic resin composition waste material is reduced. If the amount is small, it can be said that the oxidation induction period tends to be short.
[0106]
Here, in the present invention, the thermoplastic resin composition is mixed uniformly in the step of uniformly mixing in FIG. 2 so that the oxidation induction period of the thermoplastic molded article 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 article of the thermoplastic resin composition and to secure the same life as the virgin material.
[0107]
Further, as shown in FIG. 3 in the examples described below, a certain relationship is established between the life of the thermoplastic resin composition molded body and the oxidation induction period, and 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 molded article of the thermoplastic resin composition, the life of the molded article of the thermoplastic resin composition and the remaining amount of the antioxidant in the molded article of the thermoplastic resin composition are highly reliable. It can be said that it can be known at all times.
[0109]
In the present invention, the oxidation induction period to be measured may be used as a target of measurement, which is obtained by temporarily heating and melting the recovered thermoplastic resin composition waste material and extruding it into a predetermined shape. In order to measure the oxidation induction period, a molded article of a thermoplastic resin composition having a shape usable 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 waste thermoplastic resin composition.
[0111]
It is preferable that the classification of this thermoplastic resin composition waste material is based on the system of the main thermoplastic resin contained in the 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]
Also, if the predetermined holding temperature is too high, the oxidation induction period tends to be too short to make a significant difference, and if the predetermined holding temperature is too low, the oxidation induction period becomes too long to measure. It takes too long. Therefore, it is preferable that the predetermined holding temperature is determined so that the oxidation induction period is in the range of 1 to 30 minutes in accordance with the classification of the thermoplastic resin composition waste material.
[0113]
For this purpose, 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. Is preferred.
[0114]
That is, in the measuring step of the present invention, it is desirable that the predetermined holding temperature is determined according to the classification of the waste thermoplastic resin composition based on the information recorded in the database.
[0115]
Note that the predetermined holding temperature may be manually adjusted by a measurer while referring to information recorded in the database when measuring the oxidation induction period, but from the viewpoint of productivity, the measurement is performed electronically. This database was recorded in the storage device of the computer, and the classification of the thermoplastic resin composition waste material was input to the computer by a certain means, so that the program in the computer was recorded in this database. Preferably, the predetermined holding temperature is automatically adjusted with reference to the information.
[0116]
<Antioxidant>
In the present invention, as the antioxidant used when necessary, in the method for recycling waste thermoplastic resin composition of the present invention, by adding to the waste thermoplastic resin composition, the same life as virgin material Any conventionally known antioxidant can be used as long as a thermoplastic resin composition molded article having the same can be obtained. For example, a phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant can be used. Agents and the like can be suitably used.
[0117]
Among these antioxidants, a phenolic antioxidant is a chain carrier radical (RO., RO) of an autoxidative deterioration reaction. ₂ It is particularly preferable because it is effective for supplementing (). Further, among the phenolic antioxidants, a hindered phenolic antioxidant is particularly preferable from the viewpoint of further improving the method of recycling the waste thermoplastic resin composition.
[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. By heating and melting the thermoplastic resin composition waste material to which is added, a thermoplastic resin composition molded article having the same remaining life as a thermoplastic resin molded article using a virgin material as a main raw material is obtained. It is also possible to get.
[0119]
In this case, the method for recycling the thermoplastic resin composition waste according to the present invention further includes the step of preventing oxidation by adding the thermoplastic resin composition waste to the thermoplastic resin composition waste based on the evaluation result of the oxidative deterioration characteristics of the thermoplastic resin composition waste. It is preferable that the method further comprises a step of determining the amount of the agent to be added, and a step of adding the determined amount of the antioxidant to the waste thermoplastic resin composition and heating and melting the same.
[0120]
JP-A-2000-65771 discloses a method for 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 disclose that the value of the thermoplastic resin composition waste material in the oxidation induction period and the value of the remaining life in the thermal oxidation deterioration test have a certain relationship. This publication also states that the value of the time deteriorated by the aging tank and the value of the oxidation induction period have a fixed relationship, but the value of the remaining life in the thermal oxidation deterioration test and the deterioration due to the aging layer are described. There is no description that the value of the time period and the value of the oxidation induction period have a certain relationship.
[0122]
Therefore, the description in this publication does not directly lead to the fact 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 this publication, only a method for measuring the degree of deterioration of a polypropylene resin molded product is described, but there is no description about a method for recycling waste thermoplastic resin composition.
[0124]
In the present invention, in the determining step provided as needed, the amount of the antioxidant added is based on the measurement result of the oxidation induction period in the above measuring step, and the antioxidant added to the waste thermoplastic resin composition Can be determined by an arbitrary method as long as the method can determine the amount of addition. In addition, among these methods, since it is a simple and accurate method, based on the information recorded in the database, particularly, the antioxidant required according to the classification and use of the thermoplastic resin composition waste material. Determine the required amount, further based on the information recorded in the database, from the measured values determined in the above measurement step, determine the remaining amount of the antioxidant remaining in the thermoplastic resin composition waste material oxidation induction period, this It is preferable to determine the difference by calculating the difference between the required amount and the remaining amount.
[0125]
In this case, it is preferable that the classification of this thermoplastic resin composition waste material is based on the system of the main thermoplastic resin contained in the thermoplastic resin composition waste material. This is because the content of the antioxidant to be contained and the like vary depending on the application, based on the main thermoplastic resin system.
[0126]
In this case, the required amount of the antioxidant in the thermoplastic resin composition waste material is required depending on the use of the thermoplastic resin composition molded product obtained by classifying and recycling the thermoplastic resin composition waste material. It is preferable that the content of the antioxidant is required depending on the remaining life. That is, the value of the required remaining life is a content obtained by applying the value of the antioxidant in the thermoplastic resin composition waste material to a certain relationship established between the content of the antioxidant and the remaining life. Is preferred.
[0127]
Further, in this case, the remaining amount of the antioxidant remaining in the thermoplastic resin composition waste material is the measured value of the oxidation induction period determined in the measurement step, and the antioxidant in the thermoplastic resin composition waste material described above. Is preferably determined by applying a certain relationship established between the residual amount of the compound and the oxidation induction period.
[0128]
Then, the difference between the required amount and the remaining amount is determined, and an antioxidant in an amount corresponding to the difference is added to the thermoplastic resin composition waste material in the adding step, and the mixture is heated and melted. By molding the plastic resin composition waste material, a molded article of the thermoplastic resin composition having a required content of the antioxidant can be obtained.
[0129]
Further, to give 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 measured value of the oxidation induction period measured in the above measuring step is a (minute), the residual amount of the antioxidant in the waste thermoplastic resin composition is b (% (w / w)), When the amount is c (% (w / w)), b is obtained based on the equation of the relational expression: b = 0.555 log-0.017, and a range of (c-b-0.05) or more is obtained. It is preferable to determine the amount of the antioxidant to be added.
[0130]
Further, the above required amount c is d (hours) for the remaining life of the thermoplastic resin composition waste material, and e (hours) for the remaining life required for the thermoplastic resin composition molded article obtained by recycling. In this case, it is preferable to be determined based on the equation of the relational expression: c = 0.066 log (e / d).
[0131]
By adding an antioxidant in an amount determined based on these relational expressions to the waste thermoplastic resin composition, to obtain a thermoplastic resin composition molded body having a necessary remaining life depending on the application Can be.
[0132]
Also, when the classifications of the thermoplastic resin composition waste material and the antioxidant are different, it is preferable to obtain the above relational expression in advance. Further, it is preferable to create a database in which the relational expressions are recorded.
[0133]
Then, 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 needed in the present invention, the amount of the antioxidant added is obtained by classifying and recycling the thermoplastic resin composition waste based on information recorded in the database. The required amount of the antioxidant required according to the use of the thermoplastic resin composition molded body is determined, and based on the information recorded in the database, from the measured values determined in the measurement process, the thermoplastic resin composition It is preferable to determine the remaining amount of the antioxidant remaining in the waste material oxidation induction period, and determine the difference between the required amount and the remaining amount.
[0135]
The amount of the antioxidant to be added may be calculated and determined by an operator himself by referring to the information recorded in the database before the addition of the antioxidant. From, this database is recorded in the storage device of the computer, classification of the thermoplastic resin composition waste material by a certain means, the use of the thermoplastic resin composition molded article obtained by recycling and the above The measured value of the oxidation induction period in the measurement step is input to the computer, and the program in the computer refers to the information recorded in this database to automatically determine the amount of the antioxidant to be added. Is preferred.
[0136]
<Addition of antioxidant>
The method of recycling the thermoplastic resin composition waste material of the present invention, if necessary, the thermoplastic resin composition waste material, the antioxidant of the amount determined in the above-described determination step provided as needed , And a step of heating and melting the mixture.
[0137]
Here, in the addition step provided as needed in the present invention, the addition of the antioxidant may be performed by manually measuring and manually adding the determined amount of the antioxidant. However, from the viewpoint of productivity, it is preferable that the amount of the antioxidant is measured by an automatic measuring device connected to a computer capable of determining the amount of the antioxidant, and further added by the automatic adding device.
[0138]
In addition, in the addition step provided as needed in the present invention, in addition to the thermoplastic resin composition waste material and the antioxidant, an unused thermoplastic resin composition (also referred to as a virgin material in the present specification). (To be described) may be added and melted by heating.
[0139]
As described above, by further adding an unused thermoplastic resin composition to the waste thermoplastic resin composition used in the present invention, the thermoplastic resin composition formed by recycling from the waste thermoplastic resin composition is obtained. This is because the body quality can be further improved.
[0140]
Here, the unused thermoplastic resin composition is preferably a thermoplastic resin composition of the same type as the thermoplastic resin composition which is a main component of the waste thermoplastic resin composition.
[0141]
That is, to give a specific example, when the main component of the thermoplastic resin composition waste material is a polyolefin resin composition, it is desirable to add a polyolefin resin composition as an unused thermoplastic resin composition. .
[0142]
In addition, at this time, the unused thermoplastic resin composition to be added is adjusted according to the use and required characteristics of the thermoplastic resin composition molded article obtained by recycling the thermoplastic resin composition waste material. It is preferable to select an appropriate type.
[0143]
The amount of the unused thermoplastic resin composition to be added is preferably as large as possible from the viewpoint of the quality of the molded thermoplastic resin composition obtained by recycling the thermoplastic resin composition waste material. However, if it is too much, it is not preferable in terms of production cost and recycling rate.
[0144]
Therefore, the blending amount of the unused thermoplastic resin composition to be added is appropriately adjusted according to the required characteristics of the molded article to be recycled, in accordance with the required properties of the molded article to be recycled. It is desirable to do.
[0145]
In the addition step in the present invention, the thermoplastic resin composition waste material, in addition to the above components, further a heat stabilizer, a light stabilizer, an antistatic agent, a lubricant, a filler, a copper inhibitor, an antibacterial agent, A conventionally known additive such as a colorant may be added as needed, as long as the properties of the molded article of the thermoplastic resin composition obtained by recycling the thermoplastic resin composition waste material are not hindered. The timing for adding these additives is preferably at the time of charging the raw materials to an extruder described below.
[0146]
In addition, in the addition step in the present invention, it is preferable that, after the other components are added, the thermoplastic resin composition waste material heated and melted is stirred and mixed so that the composition becomes uniform.
[0147]
<Molding of molded article of thermoplastic resin composition>
The method for recycling a thermoplastic resin composition waste material of the present invention obtains a thermoplastic resin composition molded article by molding the thermoplastic resin composition waste material that has been heated and melted in the addition step provided as necessary. Preferably, the method includes a step.
[0148]
Here, in this specification, when describing 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 resin molded into a certain shape It shall include resin composition raw materials.
[0149]
The heating and melting in the adding step in the present invention and the extrusion in the forming step in the present invention are not particularly limited as long as the apparatus can perform the heating and melting and extrusion, and may be performed using any conventionally known apparatus. However, from the viewpoint of productivity and the quality of the thermoplastic resin composition molded product obtained by recycling from 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 use any one of the extruders.
[0150]
Further, in the molding step of the present invention, in consideration of versatility, it is preferable to mold the thermoplastic resin composition raw material into a fixed shape from the thermoplastic resin composition waste material that has been heated and melted. A thermoplastic resin composition molded article having a certain shape may be produced directly from the plastic resin composition waste material.
[0151]
Furthermore, in the molding step in the present invention, the shape of the obtained thermoplastic resin composition 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. It may be in the form of a sheet, a film, a pipe, or the like, and may be appropriately determined based on the type of the extruder.
[0152]
Then, 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 raw material, the pellet-shaped thermoplastic resin composition raw 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. Underwater cutting is particularly preferable because the supply of the plastic resin composition raw material can be performed smoothly and large-scale processing can be performed.
[0153]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
[0154]
<Example 1>
The used washing machine collected from the market was disassembled, and a water tank as a molded product of a resin composition containing a typical crystalline thermoplastic resin, a polypropylene-polyethylene block copolymer resin, was taken out and finely crushed. Next, the finely crushed powder of the thermoplastic resin composition waste material was washed to remove dirt, dehydrated, and dried. Then, a predetermined amount of an additive such as an antioxidant was added and uniformly mixed.
[0155]
The amount of the antioxidant added is necessary to measure the oxidation induction period of the thermoplastic resin composition waste material, and to obtain the remaining life required for the molded article of the thermoplastic resin composition from the measured value. The amount of the added antioxidant was calculated and determined.
[0156]
Then, the powder of the thermoplastic resin composition waste material mixed uniformly is heated and melted at a temperature of 190 ° C. using a biaxial melt-kneading extruder having a screw system of 45 mm, kneaded, and extruded to form an underwater cutting device. To produce a recycled resin composition raw material pellet.
[0157]
Thereafter, the recycled resin composition raw material pellets are put into a hopper of a 10-ton injection molding machine, and are subjected to injection molding conditions of a heating / melting temperature of 230 ° C. and a mold temperature of 40 ° C., and are made of an ASTM made of a thermoplastic resin composition molded body. A compliant test piece for measuring physical properties was prepared, and the physical properties and oxidation deterioration characteristics (oxidation induction period, crack generation time) were measured.
[0158]
Here, in this specification, among the test specimens for measuring physical properties based on the ASTM composed of the molded article of the thermoplastic resin composition obtained from each part, the test specimen derived from the water tank is also described as “RS”. And
[0159]
For comparison, a test piece for measuring physical properties according to ASTM (herein, “V-0”) using a general-grade virgin material of a resin composition containing a polypropylene-polyethylene block copolymer resin was used. ) And their 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 that the antioxidant was added to the waste thermoplastic resin composition, and the type and amount of the antioxidant were changed to prepare recycled resin composition raw material pellets. Things. Here, the thermal oxidation deterioration test was carried out in a gear-type oven at 150 ° C., and the crack occurrence time was evaluated.
[0161]
As understood from FIG. 3, a certain correlation was observed between the oxidation induction period and the lifetime in the thermoplastic resin. Therefore, the oxidative deterioration characteristics of the recycled molded article due to the waste thermoplastic resin composition, that is, the life, 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, flexural strength, flexural modulus, and physical properties of Izod impact strength of “RS”, the oxidation induction period, and the crack generation time were approximately equivalent to “V-0”, respectively. Or even better.
[0165]
<Example 2>
In the same manner as in Example 1, the used washing machine collected from the market is disassembled to form a water tank which is a molded article of a resin composition containing a typical crystalline thermoplastic resin, a polypropylene-polyethylene block copolymer resin. Was taken out and finely crushed. Next, the finely crushed powder of the thermoplastic resin composition waste material was washed to remove dirt, dehydrated, and dried. Then, a predetermined amount of an additive such as an antioxidant was added and uniformly mixed.
[0166]
The amount of the antioxidant added is necessary to measure the oxidation induction period of the thermoplastic resin composition waste material, and to obtain the remaining life required for the molded article of the thermoplastic resin composition from the measured value. The amount of the antioxidant added was calculated and determined.
[0167]
Then, the uniformly mixed powder of the thermoplastic resin composition waste material is heated and melted at a temperature of 190 ° C. using a biaxial melt-kneading extruder with a screw system of 45 mm, kneaded, and extruded to form an underwater cutting device. To produce a recycled resin composition raw material pellet.
[0168]
Here, in order to investigate the relationship between the foreign matter mixed in the recycled resin composition raw material pellets, the physical properties of the recycled molded product, and the oxidative deterioration characteristics, a mesh filter for removing foreign matter was arranged in the extruder, and the mesh filter was used. And the amount of foreign matter mixed into the recycled resin composition raw material pellets was examined.
[0169]
The measurement of the amount of foreign matter mixed is performed by heating and melting the pellets of the recycled resin composition to produce a 220 mm × 220 mm × 1 mm press sheet, and visually observing the foreign matter by referring to a dust measurement chart or the like, so that the amount of foreign matter mixed in This was done by classifying each.
[0170]
Table 4 shows the relationship between the size of the mesh filter provided in the extruder and the amount of foreign matter mixed in the recycled resin composition raw material pellets.
[0171]
[Table 4]

[0172]
As shown in Table 4, as the opening of the foreign matter removing filter provided in the extruder is reduced, the amount of foreign matter mixed into the raw material resin composition raw material pellets decreases, and a large effect is obtained at around 0.2 mm. 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 material regenerated molded body was investigated.
[0174]
After preparing the finely crushed thermoplastic resin composition waste material in the same process as in Example 1, the cleaning level of the thermoplastic resin composition waste material was changed to perform extrusion molding, and each cleaning level was individually regenerated. The raw material resin composition raw material pellets were prepared, and the relationship between the amount of contaminants and physical properties was examined. The mesh filter provided in the extruder had an aperture of 0.25 mm.
[0175]
The washing level is water washing (put the crushed product in a net bag and water washing with a washing machine), and sieve washing (0.87 mm wire diameter, 3.36 mm mesh openings) Was treated with sieving) and no washing was performed.
[0176]
As in the case of Example 2, the measurement of the amount of contaminants mixed was carried out by heating and melting the raw material resin composition raw material pellets to prepare a press sheet (220 mm × 220 mm × 1 mm). ² The above foreign substances were counted by visual observation.
[0177]
Table 5 shows the relationship between the amount of foreign matter mixed in the recycled resin composition raw material pellets produced from the water tank of the used washing machine and the physical properties of the ASTM-compliant test specimen for physical properties produced from the recycled resin composition raw material pellets. .
[0178]
[Table 5]

[0179]
As shown in Table 5, there is a correlation between the amount of contaminants and the physical properties. When the amount of contaminants increases, the physical properties change, and in particular, the tensile elongation greatly decreases.
Therefore, in order to stabilize the physical properties of the recycled molded article made of the thermoplastic resin waste material, it is important to control the amount of foreign matter mixed in the recycled resin composition raw material pellets to a certain amount or less.
[0180]
<Example 4>
The relationship between the amount of foreign matter mixed in the raw material resin composition raw material pellets and the oxidative deterioration characteristics of the thermoplastic resin waste material recycled molded article was investigated. The sample used in the experiment was prepared from the recycled resin composition raw material pellets prepared in Example 3.
[0181]
The measurement of the amount of foreign matter mixed is performed by heating and melting the recycled resin composition raw material pellets to form a press sheet (220 mm × 220 mm × 1 mm), and visually observing the foreign matter by referring to a dust measurement chart and the like. The classification was performed by size.
[0182]
The evaluation of the oxidative deterioration characteristics was conducted by placing the recycled resin composition raw material pellets in a hopper of a 10-ton injection molding machine and subjecting the thermoplastic resin composition waste material to injection molding conditions of a heat melting temperature of 230 ° C. and a mold temperature of 40 ° C. After preparing a test piece for measuring tensile strength based on ASTM, a thermal oxidation deterioration test was carried out in a gear-type oven at 150 ° C. to measure the time until cracks occurred, This was performed by determining the number of points of deterioration.
[0183]
Table 6 shows the relationship between the amount of foreign substances mixed into the recycled resin composition raw material pellets prepared from the water tank of the used washing machine and the oxidative deterioration characteristics of the ASTM-compliant test specimens for physical properties prepared from the recycled resin composition raw material pellets. Is shown.
[0184]
[Table 6]

[0185]
As shown in Table 6, there is a correlation between the amount of contaminants and the oxidative deterioration characteristics, and as the amount of contaminants increases, the oxidative deterioration characteristics decrease. ² When the amount of the above-mentioned foreign substances mixed increases, the location of local deterioration of the recycled thermoplastic resin waste molded article tends to greatly increase.
[0186]
Conventionally, foreign substances such as water scale and rust adhering to used products have been mixed into molded products made from used resin (hereinafter sometimes simply referred to as “recycled products”), resulting in deterioration of physical properties. It was known to be causing this.
[0187]
However, the fact that there is a correlation between the amount of contaminants and the oxidative deterioration characteristics has been clarified for the first time in the present invention, and the technical idea of controlling the oxidative deterioration characteristics by controlling the amount of contaminants. Are also proposed for the first time in the present invention.
[0188]
However, in the present embodiment, when the amount of foreign matter mixed is large, local deterioration starting from the foreign matter becomes remarkable, and it is considered that thermal oxidation deterioration at 150 ° C. is promoted, as shown in FIG. No correlation was observed between the thermal oxidation deterioration at 150 ° C. and the oxidation induction period.
[0189]
Therefore, in order to stabilize the oxidative deterioration characteristics of the recycled molded product of the thermoplastic resin composition obtained from the thermoplastic resin composition waste material, the amount of foreign matter mixed in the recycled resin composition raw material pellets is controlled to a certain amount or less. , Especially 0.3mm ² It is important to control the amount of foreign matter mixed above 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 the lot management of the recycled resin composition raw material pellets based on the physical properties, the amount of foreign matter mixed in, and the oxidative deterioration characteristics. Can obtain thermoplastic resin composition molded products with high quality properties by recycling, and expand the applications of thermoplastic resin composition molded products obtained by recycling from waste thermoplastic resin composition It becomes possible to expand.
[0191]
<Measurement method>
The measurements of the various physical properties (tensile strength, bending strength, flexural modulus, Izod impact strength), oxidation induction period, and crack generation time performed in the above Examples were performed according to the following measurement methods.
[0192]
(I) Method of measuring tensile strength and tensile modulus
Using a test piece for measuring physical properties compliant with ASTM, the tensile strength and the tensile modulus were measured in accordance with JIS K7113.
[0193]
(Ii) Method for measuring flexural strength and flexural modulus
Flexural strength and flexural modulus were measured according to JIS K7203 using test specimens for measuring physical properties based on ASTM.
[0194]
(Iii) Method for measuring Izod impact strength
Izod impact strength was measured according to JIS K7110 using a test piece for physical property measurement in accordance with ASTM.
[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 (TG / DTA320U, manufactured by Seiko Instruments Inc.). First, the temperature of the test sample was raised to 210 ° C. in a nitrogen atmosphere, held for 10 minutes, then switched to an air atmosphere, and the time required for the test sample to start an exothermic reaction was measured as an oxidation induction period.
[0196]
(V) Method of measuring crack occurrence time
As an accelerated test for evaluating the oxidative deterioration characteristics, a test piece for measuring physical properties in accordance with ASTM was left standing in a gear oven at 150 ° C. to perform a thermal oxidative deterioration test, and measurement of the time until cracks occurred. Alternatively, a local deterioration point was counted.
[0197]
(Vi) Method for measuring the amount of foreign matter mixed
The recycled resin composition raw material pellets were heated and melted to produce a 220 mm × 220 mm × 1 mm press sheet, and the foreign substances to be mixed were classified by size and counted by visual observation with reference to a dust measurement chart and the like.
[0198]
The embodiments and examples disclosed this time are to be considered in all respects as illustrative and not restrictive. 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 thermoplastic resin composition waste material recycling method of the present invention, from the thermoplastic resin composition waste material, by recycling the thermoplastic resin composition waste material as a main raw material, according to various uses It can be said that this is an efficient method for recycling thermoplastic resin composition waste material, which can provide a thermoplastic resin composition molded article having quality and life.
[0200]
Further, the method for producing a molded article of the thermoplastic resin composition of the present invention using the method for recycling a waste thermoplastic resin composition of the present invention includes the steps of: producing a waste thermoplastic resin composition from the waste thermoplastic resin composition. It can be said that this is a production method capable of obtaining a molded article of a thermoplastic resin composition having quality and life corresponding to various uses by material recycling as a main raw material.
[0201]
And the thermoplastic resin composition molded article of the present invention obtained by using the method for recycling the thermoplastic resin composition waste material of the present invention is obtained by material recycling using the thermoplastic resin composition waste material as a main raw material. It can be said that it is a thermoplastic resin composition molded article having quality and life corresponding to various uses.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram describing a graph showing an example of a general tendency of characteristic deterioration of a molded article of a thermoplastic resin composition.
FIG. 2 is a process chart showing an example of a process flow of a method for recycling waste thermoplastic resin composition of 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 (11)

A step of heating and melting the thermoplastic resin composition waste material, a step of controlling the amount of foreign matter mixed in the heated and melted thermoplastic resin composition waste material by the particle size of the foreign matter, and a step of heating and melting the thermoplastic resin waste material A method for recycling thermoplastic resin composition waste material, comprising: a step of molding a thermoplastic resin composition molded article; and a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded article. The step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body includes the step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition molded body by measuring the oxidation induction period of the thermoplastic resin composition molded body. The method for recycling the thermoplastic resin composition waste material according to claim 1, comprising: 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 by the particle size of the foreign matter. And a step of shaping the heat-melted thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body. The method according to claim 3, wherein the step of evaluating the oxidative deterioration characteristics includes a step of evaluating the oxidative deterioration characteristics of the thermoplastic resin composition waste material by measuring an oxidation induction period of the thermoplastic resin composition waste material. A method of recycling plastic resin composition waste. The step of controlling the amount of foreign matter mixed by the particle diameter of the foreign matter includes a step of passing the heat-melted thermoplastic resin composition waste material through a foreign matter removing filter having a mesh size of 0.2 mm or less. The method for recycling thermoplastic resin composition waste according to any one of the above. The method for recycling thermoplastic resin composition waste according to any one of claims 1 to 5, wherein the thermoplastic resin composition waste is a thermoplastic resin composition waste containing a polyolefin-based resin as a main component. The method for recycling thermoplastic resin composition waste according to any one of claims 1 to 6, wherein the thermoplastic resin composition waste is a thermoplastic resin composition waste recovered from a washing machine. A method for producing a molded article of a thermoplastic resin composition, wherein the molded article of a thermoplastic resin composition is obtained by the method for recycling waste thermoplastic resin composition according to any one of claims 1 to 7. The method for producing a thermoplastic resin composition molded article according to claim 8, wherein the thermoplastic resin composition molded article is a thermoplastic resin composition molded article having a pellet-like shape. A molded thermoplastic resin composition obtained by the method for recycling waste thermoplastic resin composition according to any one of claims 1 to 7. The thermoplastic resin composition molded product according to claim 10, wherein the thermoplastic resin composition molded product is a thermoplastic resin composition molded product having a pellet shape.

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