JP4011379B2 - Recycling method of waste thermoplastic resin composition - Google Patents

Description

【００６３】
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
＜酸化防止剤＞
本発明に用いる酸化防止剤は、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余寿命を有する熱可塑性樹脂組成物成形体をえ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。
【００６４】
また、これらの酸化防止剤の中でも、フェノール系酸化防止剤は、自動酸化劣化反応の連鎖担体ラジカル（ＲＯ・，ＲＯ₂・）を補足するのに有効であることから特に好ましい。さらに、フェノール系酸化防止剤の中でも、熱可塑性樹脂組成物廃材の再資源化方法をさらに効果的にする観点からは、ヒンダードフェノール系酸化防止剤がとりわけ好ましい。
【００６５】
＜測定工程＞
本発明における測定工程においては、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、特に該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て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。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。
【００６６】
すなわち、本発明における測定工程においては、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の所定の保持温度では酸化しにくく、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。
【００６７】
また、本発明における測定工程においては、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。
【００６８】
したがって、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。
【００６９】
また、同様に、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。
【００７０】
また、後述の実施例において図３および図４を用いて示すように、熱可塑性樹脂組成物廃材の余寿命と、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廃材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。
【００７１】
そのため、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、熱可塑性樹脂組成物廃材の余寿命と、熱可塑性樹脂組成物廃材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。
【００７２】
なお、本発明における測定工程において、酸化誘導期を測定される熱可塑性樹脂組成物廃材は、回収された状態のままであってもよいが、正確な酸化誘導期を測定するためには、解体、破砕、洗浄などの処理を受けた粉状体であることが好ましい。また、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。
【００７３】
ここで、本発明における測定工程において、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。
【００７４】
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。
【００７５】
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す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すぎると、酸化誘導期が長くなりす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。
【００７６】
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。
【００７７】
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。
【００７８】
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。
【００７９】
＜決定工程＞
本発明におけ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が、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、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、前記必要量と前記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。
【００８０】
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。
【００８１】
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。
【００８２】
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。
【００８３】
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。
【００８４】
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、かつ本発明における決定工程において、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、図４に示すグラフより導かれる関係式：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。
【００８５】
また、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、図３および図４に示すグラフより導かれる関係式：ｃ＝０．０６６ｌｏｇ（ｅ／ｄ）の式に基づいて決定されることが好ましい。
【００８６】
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。
【００８７】
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。
【００８８】
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。
【００８９】
すなわち、本発明における決定工程において、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。
【００９０】
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。
【００９１】
＜添加工程＞
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に、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る。
【００９２】
ここで、本発明におけ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。
【００９３】
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。
【００９４】
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。
【００９５】
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。
【００９６】
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。
【００９７】
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。
【００９８】
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、余り多す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。
【００９９】
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。
【０１００】
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。
【０１０１】
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。
【０１０２】
＜成形工程＞
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。
【０１０３】
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。
【０１０４】
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。
【０１０５】
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。
【０１０６】
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。
【０１０７】
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。
【０１０８】
＜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。
【０１０９】
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、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、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、洗浄されて汚れや不純物を取除かれる。そして、洗浄された熱可塑性樹脂組成物廃材の粉状体は、加熱溶融、混練され、押出成形により、一定の形状に成形される。
【０１１０】
こうして一定の形状に成形された熱可塑性樹脂組成物廃材は、測定工程において、酸化誘導期を測定され、決定工程において、酸化防止剤の添加量を決定される。そして、添加工程において、決定された量の酸化防止剤を添加されて、加熱溶融、混練され、成形工程において、押出成形されて一定の形状の熱可塑性樹脂組成物成形体に成形される。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。
【０１１１】
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。
【０１１２】
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酸化誘導期の測定は、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酸化誘導期の測定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。
【０１１３】
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、直ぐに酸化誘導期を測定してもよい。
【０１１４】
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、上述の測定工程、決定工程、添加工程、成形工程を具備していれば、一部の工程は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。
【０１１５】
【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。
【０１１６】
＜実施例＞
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、および脱水槽、上蓋をそれぞれ個別に取り出し、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、それぞれ個別に均一に混合した。
【０１１７】
そして、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、２３０℃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、ペレット状の熱可塑性樹脂組成物廃材の粉体をそれぞれ個別に作製した。
【０１１８】
その後、これらのペレット状の熱可塑性樹脂組成物廃材の粉体を、１０トン押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℃の押出成形条件で、それぞれの熱可塑性樹脂組成物廃材からなるＡＳＴＭ準拠の物性測定用試験片を個別に作製し、それぞれの物性および酸化誘導期、クラック発生時間を個別に測定した。測定結果を表２に示す。
【０１１９】
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廃材からなる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」、脱水槽由来の試験片を「Ｒ−Ｄ」、上蓋由来の試験片を「Ｒ−Ｕ」とも記載することとする。
【０１２０】
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誘導期、クラック発生時間を測定した。測定結果を表２に示す。
【０１２１】
【表２】

【０１２２】
表２に示すように、「Ｒ−Ｓ」、「Ｒ−Ｄ」、「Ｒ−Ｕ」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は、それぞれ「Ｖ−０」と概略同等であった。
【０１２３】
しかし、「Ｒ−Ｓ」、「Ｒ−Ｄ」、「Ｒ−Ｕ」は、「Ｖ−０」に比べて、酸化誘導期が短く、クラック発生時間もその酸化誘導期に対応する形で短い。そのことから、これらの熱可塑性樹脂組成物廃材を再資源化するには、再資源化して得られる熱可塑性樹脂組成物成形体からなる部材の要求特性に応じて、これらの熱可塑性樹脂組成物廃材の余寿命を延長する必要があることがわかる。
【０１２４】
次に、「Ｒ−Ｓ」、「Ｒ−Ｄ」、「Ｒ−Ｕ」、「Ｖ−０」を含む５つの熱可塑性樹脂組成物廃材からなる試験片の酸化誘導期とクラック発生時間を測定した。測定結果を図３に示す。
【０１２５】
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組成物廃材の余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」はその余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。
【０１２６】
その結果、図３から理解されるように、これらの熱可塑性樹脂組成物廃材において、酸化誘導期と余寿命との間には、一定の相関関係が認められた。
【０１２７】
よって、このようにして熱可塑性樹脂組成物廃材の酸化誘導期を測定することで、その熱可塑性樹脂組成物廃材の余寿命を簡易に把握できる。それゆえ、再資源化して得られる熱可塑性樹脂組成物成形体の要求特性に応じて熱可塑性樹脂組成物廃材を改質することにより、熱可塑性樹脂組成物廃材を多様な用途へマテリアルリサイクルにより再資源化することが可能となる。
【０１２８】
ここで、一般的に、ポリプロピレン−ポリエチレンブロック共重合体樹脂組成物などの熱可塑性樹脂組成物には、フェノール系酸化防止剤およびリン系酸化防止剤が添加されており、ベースポリマーとなる熱可塑性樹脂の余寿命の安定化が図られている。また、耐熱性のグレードを向上させるために、熱安定性を強化する機能を有するイオウ系酸化防止剤が添加されていることも多い。
【０１２９】
これらの酸化防止剤は、熱可塑性樹脂組成物成形体の使用時に徐々に消費され、ベースポリマーを安定化する機能を有する。したがって、熱可塑性樹脂組成物廃材に含有される酸化防止剤の量は、当初の添加量よりもかなり減少しているものと思われる。
【０１３０】
この点を確認するために、実施例１において作成した「Ｒ−Ｓ」、「Ｒ−Ｄ」、「Ｒ−Ｕ」、「Ｖ−０」にそれぞれ含有される酸化防止剤量を測定した。測定結果を表３に示す。
【０１３１】
【表３】

【０１３２】
表３から理解されるように、フェノール系酸化防止剤は、熱可塑性樹脂組成物廃材の使用環境によって消費量が異なり、リン系酸化防止剤およびイオウ系酸化防止剤は、使用環境に関係なくほぼ全量が消費されていた。したがって、熱可塑性樹脂組成物廃材の組成を把握しておけば、酸化誘導期を測定することによって、フェノール系酸化防止剤の残存量を、簡易に把握することが可能である。
【０１３３】
次に、フェノール系酸化防止剤の残存量と酸化誘導期との関係をより明確にするために、図２のミキシング工程で、「Ｒ−Ｄ」と同一組成の熱可塑性樹脂組成物廃材の粉体に、ヒンダードフェノール系酸化防止剤であるテトラキス［メチレン−３−（３’，５’−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネ−ト］メタン（旭電化工業（株）製、アデカスタブＡＯ６０）を所定量添加して試験片を作成し、酸化誘導期を測定した。測定結果を図４に示す。
【０１３４】
図４から理解されるように、フェノール系酸化防止剤の添加量（ほぼ残存量に等しい）と酸化誘導期との間には一定の相関関係があり、さらにフェノール系酸化防止剤の添加量を変えることによって、酸化誘導期、すなわち熱可塑性樹脂組成物廃材の余寿命を改善することが可能である。
【０１３５】
次いで、フェノール系酸化防止剤の添加量を可変させて、３種類の処方に基づいて「Ｒ−Ｄ」と同一組成の熱可塑性樹脂組成物廃材の粉体を改質し、同一組成の熱可塑性樹脂組成物廃材の粉体から、要求特性の異なる複数の種類の熱可塑性樹脂組成物成形体へ再資源化し、ＡＳＴＭ準拠の物性測定用試験片を作成して、それぞれの試験片の物性および酸化誘導期、クラック発生時間を個別に測定した。測定結果を表４に示す。
【０１３６】
なお、熱可塑性樹脂組成物におけるリン系酸化防止剤の添加量は、フェノール系酸化防止剤の１〜３倍量であることが一般的であるため、本実施例では、フェノール系酸化防止剤の残存量と添加量の合計値の２倍量のリン系酸化防止剤を添加することとした。
【０１３７】
すなわち、この実験において、処方１では、熱可塑性樹脂組成物廃材の粉体１００質量部に対して、０．０７質量部のフェノール系酸化防止剤と、０．２質量部のリン系酸化防止剤を添加した。
【０１３８】
また、この実験において、処方２では、熱可塑性樹脂組成物廃材の粉体１００質量部に対して、０．１１質量部のフェノール系酸化防止剤と、０．２５質量部のリン系酸化防止剤を添加した。
【０１３９】
そして、この実験において、処方３では、熱可塑性樹脂組成物廃材の粉体１００質量部に対して、０．１１質量部のフェノール系酸化防止剤と、０．２５質量部のリン系酸化防止剤、さらに耐熱性を向上させるために０．０８質量部のイオウ系酸化防止剤を添加した。
【０１４０】
なお、処方１〜３においては、フェノール系酸化防止剤（旭電化工業（株）製、アデカスタブＡＯ６０）とリン系酸化防止剤（旭電化工業（株）製、アデカスタブ２１１２）、イオウ系酸化防止剤（吉富ファインケミカル（株）製、ヨシノックスＤＭＴＰ）とを用いた。
【０１４１】
さらに、比較のために、「Ｖ−０」、「Ｖ−１」についても、それぞれの試験片の物性および酸化誘導期、クラック発生時間を個別に測定した。
【０１４２】
ここで、「Ｖ−１」は、Ｖ−０とはメーカーの異なる一般グレードのポリプロピレン樹脂である。
【０１４３】
【表４】

【０１４４】
表４から理解されるように、処方１〜３を施すことにより、熱可塑性樹脂組成物廃材の酸化誘導期およびクラック発生時間の改善が著しい。
【０１４５】
そのため、処方１を施した熱可塑性樹脂組成物廃材は、「Ｖ−０」と同一組成からなる熱可塑性樹脂組成物成形体の代替材として、処方２を施した熱可塑性樹脂組成物廃材は、「Ｖ−１」と同一組成からなる熱可塑性樹脂組成物成形体の代替材として再資源化することが可能となる。
【０１４６】
なお、上記の引張強度などの物性値は、熱可塑性樹脂組成物廃材に処方１〜３を施しても、「Ｖ−０」および「Ｖ−１」に比べてわずかに劣るが、この程度であれば、酸化防止剤に加えて、さらにバージン材料を適量混合することにより改質が可能な範囲である。
【０１４７】
よって、このように、改質の処方を適宜可変し、酸化防止剤および／またはバージン材を適当量加えることにより、単一の組成の熱可塑性樹脂組成物廃材から数通り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。
【０１４８】
＜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。
【０１４９】
（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。
【０１５０】
（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。
【０１５１】
（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。
【０１５２】
（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。
【０１５３】
（ｖ）クラック発生時間の測定方法
余寿命を評価するための加速試験として、１４０℃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を測定した。そして、このクラック発生時間を余寿命の評価に用いた。
【０１５４】
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。
【０１５５】
【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余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、効率的かつ低コスト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。
【０１５６】
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余寿命を有する熱可塑性樹脂組成物成形体を製造することのできる方法であるといえる。
【０１５７】
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余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。
【図４】 本発明の実施例における酸化防止剤の添加量と酸化誘導期との相関関係の一例を示すグラフを記載した図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for recycling a thermoplastic resin composition waste material. More specifically, the present invention relates to a method for recycling a thermoplastic resin composition waste material that determines a policy for recycling according to the deterioration state of the thermoplastic resin composition waste material.
[0002]
Moreover, this invention relates also to the manufacturing method of the thermoplastic resin composition molded object by said recycling method. Furthermore, this invention relates also to the thermoplastic resin composition molded object obtained by said recycling method.
[0003]
[Prior art]
In recent years, with the improvement in income levels in Japan, home appliances such as air conditioners (also referred to as air conditioners in this specification), television receivers (also referred to as TVs in this specification), refrigerators, and washing machines. Information devices such as personal computers and word processors, office equipment such as printers and fax machines, and various other furniture, stationery, and toys are now being provided at a high penetration rate in general households. Sex is improving dramatically.
[0004]
On the other hand, as a result, the amount of discarded products such as home appliances tends to increase year by year. Here, conventionally, recycling of waste materials of products including these home appliances has been often performed through a recovery route of iron scrap.
[0005]
However, in recent years, the constituent materials of members of various products such as home appliances have changed, and the number of members made of metal such as iron has decreased, and the proportion of members made of a plastic composition tends to increase. Plastic compositions have a greater degree of design freedom than metals such as iron, and can be imparted with various properties that are difficult to achieve with metals by preparing components and using additives, and are lightweight and durable. This is because it has many advantages such as high performance.
[0006]
And the waste material of various products including recent home appliances, the material composition of various components is complicated, the ratio of members made of valuable metals such as iron and copper is small, the value is low, In addition, the proportion of members made of a plastic composition, which requires a lot of labor and cost in the conventional treatment method, is large, and it is not profitable even if such waste materials are recycled in the conventional iron scrap recovery route. The situation is becoming difficult to deal with.
[0007]
And, many of these plastic composition members are synthesized using crude fossil and other embedded fossil fuel as the basic raw material. From the viewpoint of effective use of resources, products with these plastic composition members are used. In recent years, the promotion of recycling has been strongly demanded.
[0008]
In addition, environmental pollution such as global warming and acid rain due to the release of carbon dioxide and sulfur oxides from combustion of buried fossil fuels such as crude oil, and environmental pollution such as dioxin generation and scattering due to incineration of plastic compositions containing chlorine compounds. Furthermore, from the viewpoint of suppressing problems such as a shortage of landfill disposal sites due to an increase in waste materials containing bulky plastic compositions, it is possible to recycle waste materials from products having members made of these plastic compositions. It is becoming an important and urgent issue.
[0009]
In the present specification, a member made of a plastic composition is also referred to as a plastic member. Moreover, in this specification, the product provided with the plastic member is also described as a plastic product. Furthermore, in this specification, the waste material of a plastic product is also described as a plastic waste material.
[0010]
In response to the above situation, the Home Appliance Recycling Law was enforced in April 2001. Here, in the Home Appliance Recycling Law, as of January 2002, it is obliged to recycle four items of home appliances such as air conditioners, televisions, refrigerators, and washing machines. Legal reference values are set for% or more, television 55% or more, refrigerator 50% or more, washing machine 50% or more.
[0011]
And, following the enforcement of the Home Appliance Recycling Law, the recovery of plastic waste materials is progressing. As a method of recycling plastic waste materials recovered in this way, the so-called plastic waste materials are used as fuel. Many methods related to thermal recycling have been used in the past. However, according to such a method, it is possible to recycle plastic waste by thermal recycling, but there is a problem such as the generation of carbon dioxide gas by combustion, so it is a method that fully meets social demands. I can't say that.
[0012]
Therefore, from the plastic waste collected in this way, plastic members are separated for each system of the plastic composition by a method such as manual disassembly, and these plastic members are processed again into product members or raw materials for use. A method for recycling plastic waste has been proposed. Such a recycling method is described as material recycling in contrast to the thermal recycling described above.
[0013]
Among the plastic members separated for each system of the plastic composition as described above, a member made of a thermoplastic resin composition (also referred to as a thermoplastic resin composition waste material in this specification) is heated and melted. Then, it is possible to relatively easily recycle the material by molding again.
[0014]
Therefore, at present, in order to increase the material recycling ratio of plastic waste materials, research and development of a recycling method by material recycling of thermoplastic resin composition waste materials has been carried out with great efforts in various fields.
[0015]
[Problems to be solved by the invention]
However, when thermoplastic resin composition waste, especially thermoplastic resin composition waste used in home appliances and office equipment, is often used for a long time in harsh environments, In many cases, the material is poor in durability, not only in appearance quality such as discoloration or fading, but also in physical properties such as strength and flexibility.
[0016]
For this reason, the thermoplastic resin composition waste material is often used as a raw material for a plastic member having low required properties, not as a substitute for the virgin material of the thermoplastic resin composition used for a plastic member having high required properties.
[0017]
At present, such cascade recycling is the mainstream as material recycling of thermoplastic resin composition waste. Therefore, the use of the thermoplastic resin composition molded body regenerated from the thermoplastic resin composition waste is limited.
[0018]
Here, in the present specification, the virgin material means an unused resin composition. Further, in this specification, the plastic waste material with reduced quality is not used as a substitute for the virgin material of the thermoplastic resin composition used for the plastic member having high required characteristics, but as a raw material for the plastic member having low required characteristics. Shall be described as cascade recycling.
[0019]
In order to overcome such problems, the quality of the thermoplastic resin composition molded body obtained by material recycling from the above-mentioned thermoplastic resin composition waste material is improved, and it can be used as a plastic member having high required characteristics. Many research and development efforts have been made to achieve this.
[0020]
For example, many methods have been proposed, including JP 2000-159900 A, in which quality is maintained by mixing a virgin material with a thermoplastic resin composition waste material (material recycled material).
[0021]
However, in such a material recycling method, the physical properties are improved with mixing of the virgin material, but as long as the thermoplastic resin composition waste material whose physical properties are reduced is mixed, the physical properties equivalent to the virgin material are recovered. Impossible. In addition, in order to approximate the physical properties of virgin materials, it is often necessary to mix a larger amount of virgin material than waste thermoplastic resin composition, and it is difficult to say that it corresponds to a resource recycling society. is there. Moreover, even if it is a thermoplastic resin composition waste material in which the physical property has not fallen, the lifetime has fallen greatly by long-term use, and there exists a problem in long-term reliability, when it recycles.
[0022]
On the other hand, Japanese Patent Laid-Open No. 7-24437 discloses a recycling system in which a recycling policy is determined based on component parts of a used product and the degree of deterioration and is repeatedly recycled.
[0023]
However, in this recycling system, the degree of deterioration, which is a criterion for determining measures, is based on physical properties that can be determined by comparison with virgin materials, and only when the initial characteristics of recovered waste materials are known. It becomes effective. However, the amount of waste materials actually collected is enormous, and it takes a lot of time and processing capacity to grasp the initial characteristics of each of these, and to compare the characteristics of the waste materials with each other. In reality, there is a problem that such a recycling system is difficult to realize and disadvantageous in cost.
[0024]
In addition, the parts used inside the products that become waste materials are less susceptible to light and the like than the parts used for appearance, so the degree of apparent deterioration is low, and it deteriorates as a significant difference in physical property values. In some cases, the progress of Therefore, in such a recycling system, there is also a problem that although it is possible to identify the material composition of the waste material, it is difficult to distribute the materials according to the degree of deterioration.
[0025]
As described above, from the thermoplastic resin composition waste material collected from the market, material recycling that uses the thermoplastic resin composition waste material as the main raw material has a quality that can be used as a highly demanded plastic member or its raw material. In addition, an efficient and low-cost thermoplastic resin composition capable of obtaining a molded product of a thermoplastic resin composition having a life as a product equivalent to that of a virgin material (in this specification, simply abbreviated as the remaining life) In spite of the strong demand for the development of a method for recycling waste materials, such a recycling method is not yet known.
[0026]
Based on the above-mentioned present situation, the object of the present invention is to provide a thermoplastic resin having a quality and a remaining life corresponding to various uses by material recycling from a thermoplastic resin composition waste material as a main raw material. An object of the present invention is to provide an efficient and low-cost method for recycling a thermoplastic resin composition waste material, from which a molded product can be obtained.
[0027]
Another object of the present invention is to provide a thermoplastic resin composition having a quality and a remaining life according to various applications by material recycling using a thermoplastic resin composition waste as a main raw material from a thermoplastic resin composition waste. It is providing the method of manufacturing a molded object.
[0028]
Furthermore, another object of the present invention is to provide a thermoplastic resin composition molded article having quality and remaining life corresponding to various uses, obtained by material recycling using thermoplastic resin composition waste as a main raw material. Is to provide.
[0029]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors evaluated the remaining life of the thermoplastic resin composition waste material, and further provided a stabilization prescription for the thermoplastic resin composition waste material to extend the remaining life. In order to develop a method for recycling such thermoplastic resin composition waste, we have received many ideas, many types of measurement methods, methods for determining stabilization measures, stabilization methods for extending the remaining life, etc. Experiments were carried out on the combination of these, and earnestly studied.
[0030]
And after the study, the present inventors evaluated the remaining life of the thermoplastic resin composition waste material by measuring the oxidation induction period of the thermoplastic resin composition waste material, and based on the database constructed in advance Determine the amount of antioxidant necessary to extend the estimated remaining life, and then add a predetermined amount of antioxidant to the thermoplastic resin composition waste based on the determination and heat melt The present inventors have found that a thermoplastic resin composition molded body may be obtained from the thermoplastic resin composition waste material that has been heated and melted.
[0031]
Furthermore, the present inventors have further studied, and based on the database construction method, the amount of the antioxidant necessary for extending the remaining life of the thermoplastic resin composition waste material based on the database. A determination method was established and the present invention was completed.
[0032]
That is, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a measurement step for measuring the oxidation induction period of the thermoplastic resin composition waste material, and the addition to the thermoplastic resin composition waste material based on the measurement result. A determination step of determining an addition amount of the antioxidant to be added, an addition step of adding the determined addition amount of the antioxidant to the thermoplastic resin composition waste and heating and melting, and the heat-melted heat A thermoplastic resin composition waste material recycling method comprising: a molding step of forming a thermoplastic resin composition waste material to obtain a thermoplastic resin composition molded body.
[0033]
Here, in the measurement step, the measurement of the oxidation induction period of the thermoplastic resin composition waste material is performed by placing the thermoplastic resin composition waste material in a nitrogen atmosphere and then setting the nitrogen atmosphere temperature at a predetermined rate. After the temperature is raised to the holding temperature, the nitrogen atmosphere is replaced with an oxygen atmosphere, and the temperature is kept isothermally at the holding temperature, and the oxidation induction period until the exothermic peak of the thermoplastic resin composition waste material appears is measured. It is preferable to carry out by.
[0034]
In the measuring step, the holding temperature is preferably determined according to the classification of the thermoplastic resin composition waste material based on information recorded in a database.
[0035]
Further, in the determining step, the amount of the antioxidant added is determined based on the information recorded in the database, and the thermoplastic resin composition molding obtained by classifying and recycling the thermoplastic resin composition waste material. Obtain the required amount of the antioxidant required according to the use of the body, and further, based on the information recorded in the database, from the measured value obtained in the measurement step, the thermoplastic resin composition waste material oxidation It is recommended to determine the residual amount of the antioxidant remaining during the induction period and determine the difference between the required amount and the residual amount.
[0036]
And in the said addition process, heating melting temperature is based on the information recorded on the database with respect to melting temperature T degreeC of this thermoplastic resin composition waste material according to the classification of said thermoplastic resin composition waste material. , T to (T + 120) ° C. is preferably determined.
[0037]
In addition, in the addition step, it is desirable to add an unused thermoplastic resin composition and melt by heating in addition to the thermoplastic resin composition waste material and the antioxidant.
[0038]
Furthermore, in the molding step, it is recommended that the thermoplastic resin composition waste material melted by heating is molded by extrusion molding. And in the said formation process, it is preferable to shape | mold the said thermoplastic resin composition waste material fuse | melted by heating to a pellet-shaped thermoplastic resin composition raw material.
[0039]
The thermoplastic resin composition waste material is preferably a resin composition waste material containing a polyolefin resin as a main component. Furthermore, it is recommended that the antioxidant is a phenolic antioxidant.
[0040]
When the thermoplastic resin composition waste material is a resin composition waste material having a polyolefin resin as a main component and the antioxidant is a phenolic antioxidant, in the determination step, the measurement is performed. When the measured value of the oxidation induction period measured in the process is a (minute), the remaining amount is b (% (w / w)), and the required amount is c (% (w / w)), b It is preferable to determine b based on the formula = 0.055loga-0.017 and to determine the addition amount of the antioxidant in a range of (cb-0.05) or more.
[0041]
Here, the required amount c is d (hour) the remaining life of the thermoplastic resin composition waste, and e (hour) is the remaining life required for the thermoplastic resin composition molded body obtained by recycling. In this case, it is desirable to determine based on c = 0.066 log (e / d).
[0042]
Moreover, this invention includes the manufacturing method of a thermoplastic resin composition molded object characterized by obtaining a thermoplastic resin composition molded object by the recycling method of the thermoplastic resin composition waste material of this invention. Furthermore, this invention contains the thermoplastic resin composition molded object obtained by the recycling method of the thermoplastic resin composition waste material of this invention.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to embodiments.
[0044]
The method for recycling a thermoplastic resin composition waste material according to the present invention includes a measurement step of measuring an oxidation induction period of a thermoplastic resin composition waste material, and an oxidation added to the thermoplastic resin composition waste material based on the measurement result. A determining step for determining an addition amount of the inhibitor; an addition step for adding the determined addition amount of the antioxidant to the thermoplastic resin composition waste material and heating and melting; and the heat-melted thermoplastic resin A thermoplastic resin composition waste material recycling method comprising a molding step of molding a composition waste material to obtain a thermoplastic resin composition molded body.
[0045]
<Evaluation method of remaining life>
First, FIG. 1 is a conceptual diagram showing a general tendency of characteristic deterioration of a thermoplastic resin composition molded article. As shown in FIG. 1, a thermoplastic resin composition molded article generally has a tendency that its characteristics rapidly decrease after a deterioration induction period inherent to the thermoplastic resin composition.
[0046]
Therefore, the thermoplastic resin composition waste recovered from the market has a short remaining life due to long-term use, even when deterioration in properties cannot be confirmed by physical property tests such as measurement of tensile strength. Thermal stability is often reduced.
[0047]
In other words, some thermoplastic resin composition wastes collected from the market have a shorter remaining life than that at the time of manufacture due to heat or light. These thermoplastic resin composition wastes can be reused as they are for parts made of low-grade thermoplastic resin composition molded bodies. However, in order to develop more applications, thermoplastic resin compositions By accurately evaluating the remaining life of the waste material, it is possible to improve the quality according to the remaining life and enable application to parts made of a medium-quality or high-quality molded thermoplastic resin composition. It is preferable for improving the recycling efficiency.
[0048]
For example, if the thermoplastic resin composition waste material is recovered from the market at the time indicated by A in FIG. 1, when this thermoplastic resin composition waste material is recycled as a recycled material, the remaining life is the length indicated by the period B. Therefore, it cannot be used as a molded product of a thermoplastic resin composition that requires durability or high functionality.
[0049]
In addition, the evaluation of the remaining life of the molded thermoplastic resin composition is generally performed by performing a thermal oxidation deterioration test in a gear oven at around 150 ° C. until the deterioration of the properties of the molded product, for example, cracking occurs. This is done by measuring time. However, this test method requires several hundred hours to obtain an evaluation result, and when applied to a method for recycling thermoplastic resin composition waste, the productivity of the recycling method must be low. There is a problem that you can not get.
[0050]
Furthermore, as shown in FIG. 1, the decrease in properties (for example, physical properties such as tensile strength) of the thermoplastic resin composition waste during recovery is very small, and the decrease in remaining life is evaluated by measuring specific physical properties. It is difficult to do.
[0051]
Here, in the course of completing the present invention, the present inventors, as will be described later, 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 degradation test are constant. Found to have a relationship. That is, it was found that the remaining life of the thermoplastic resin composition waste material can be evaluated by measuring the oxidation induction period of the thermoplastic resin composition waste material.
[0052]
Therefore, in the present invention, instead of performing the thermal oxidative degradation test, the remaining life of the thermoplastic resin composition waste recovered from the market can be simplified by measuring the oxidation induction period of the thermoplastic resin composition waste. And we decided to evaluate quickly.
[0053]
In the present invention, the amount of the antioxidant to be added to the thermoplastic resin composition waste is determined based on the measurement result of the oxidation induction period, and the heat to which the predetermined amount of the antioxidant is added is determined. The thermoplastic resin composition waste was molded by heating and melting to obtain a thermoplastic resin composition molded body having a remaining life equivalent to that of a thermoplastic resin composition molded body using a virgin material as a main raw material.
[0054]
Therefore, the method for recycling the thermoplastic resin composition waste material according to the present invention includes a measurement step of measuring the oxidation induction period of the thermoplastic resin composition waste material, and the thermoplastic resin composition waste material based on the measurement result. A determination step of determining an addition amount of the antioxidant to be added, an addition step of adding the determined addition amount of the antioxidant to the thermoplastic resin composition waste material and heating and melting, and the heating and melting step And a molding step of molding a thermoplastic resin composition waste material to obtain a molded thermoplastic resin composition.
[0055]
Japanese Patent Application Laid-Open No. 2000-65771 discloses a method of measuring the degree of deterioration of a polypropylene resin molded product by measuring the oxidation induction period of the polypropylene resin molded product.
[0056]
However, this publication does not describe that the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the remaining life in the thermal oxidation deterioration test have a certain relationship. Moreover, although this publication states that the value of time deteriorated by the aging tank and the value of the oxidation induction period have a certain relationship, the value of the remaining life in the thermal oxidation deterioration test and the deterioration by the aging tank There is no description that the value of the allowed time and the value of the oxidation induction period have a certain relationship.
[0057]
Therefore, from the description of this publication, it is not directly derived that the value of the oxidation induction period of the thermoplastic resin composition waste material and the value of the remaining life in the thermal oxidation deterioration test have a certain relationship.
[0058]
In addition, this publication only describes a method for measuring the degree of deterioration of a polypropylene resin molded article, and does not describe any method for recycling a thermoplastic resin composition waste material. Therefore, it can be said that the method of recycling the thermoplastic resin composition waste material of the present invention cannot be directly derived from the description of this publication.
[0059]
<Waste thermoplastic resin composition>
The thermoplastic resin composition waste material used in the present invention is a thermoplastic resin composition molded article having the same physical properties and remaining life as the virgin material by using the thermoplastic resin composition waste material recycling method of the present invention. As long as it can be used, any conventionally known thermoplastic resin composition waste material can be used. For example, a thermoplastic resin composition mainly composed of a polypropylene resin, a polyethylene resin, a thermoplastic polyester resin, or the like. Waste materials can be suitably used.
[0060]
Among these thermoplastic resin composition waste materials, thermoplastic resin composition waste materials mainly composed of polyolefin resins such as polyethylene resins and polypropylene resins are shown in Table 1 below. Recycled thermoplastic resin composition moldings using other thermoplastic resin composition recycling methods from other types of thermoplastic resin composition waste materials in terms of processability and economy. Since it is superior to the recycled thermoplastic resin composition molded article, it can be suitably used as a raw material for recycling by material recycling in the method of recycling a thermoplastic resin composition waste material of the present invention. .
[0061]
In addition, for thermoplastic resin composition waste materials containing polyolefin resin as a main component, in the method of recycling thermoplastic resin composition waste materials according to the present invention, the properties can be improved by adding various additives such as antioxidants. Since it is easy to perform, there is also an advantage that a thermoplastic resin composition molded article having a stable remaining life can be obtained with good reproducibility.
[0062]
[Table 1]

[0063]
Here, the characteristics of the main resin compositions in Table 1 were evaluated according to the following criteria.
○: Excellent
Δ: Neither
×: Inferior
<Antioxidant>
The antioxidant used in the present invention is a thermoplastic resin composition having a remaining life equivalent to that of a virgin material when added to the thermoplastic resin composition waste material in the method of recycling the thermoplastic resin composition waste material of the present invention. Any conventionally known antioxidant can be used as long as it can obtain a molded article. For example, a phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant and the like are preferably used. Can be used.
[0064]
Among these antioxidants, phenolic antioxidants are chain carrier radicals (RO ·, RO for auto-oxidation degradation reaction). ₂ It is particularly preferable because it is effective for supplementing. Further, among the phenolic antioxidants, hindered phenolic antioxidants are particularly preferable from the viewpoint of making the method for recycling the thermoplastic resin composition waste material more effective.
[0065]
<Measurement process>
In the measurement step of the present invention, the measurement of the oxidation induction period of the thermoplastic resin composition waste is not particularly limited, and any measurement method can be used as long as it can accurately measure the oxidation induction period. However, since it is a simple and accurate measurement method, the thermoplastic resin composition waste material was installed in a nitrogen atmosphere, and then the nitrogen atmosphere temperature was raised to a predetermined holding temperature at a constant rate. Thereafter, the nitrogen atmosphere is preferably replaced with an oxygen atmosphere and held at the holding temperature isothermally, and the oxidation induction period until the exothermic peak of the thermoplastic resin composition waste material appears is preferably measured. In this specification, such a method for measuring the oxidation induction period is referred to as an OIT (Oxygen Induced Time) method.
[0066]
That is, in the measurement step according to the present invention, when the remaining life of the thermoplastic resin composition waste material still remains, the remaining amount of the antioxidant in the thermoplastic resin composition waste material is still sufficiently large. Therefore, since the antioxidant effect is large, it is difficult to oxidize at a predetermined holding temperature in an oxygen atmosphere, and the time until the exothermic peak appears, that is, the oxidation induction period tends to be long.
[0067]
Further, in the measurement step in the present invention, when the remaining life of the thermoplastic resin composition waste does not remain so much, the remaining amount of the antioxidant in the thermoplastic resin composition waste is reduced, Since the antioxidant effect is small, it is easily oxidized at a predetermined holding temperature in an oxygen atmosphere, and the time until the exothermic peak appears, that is, the oxidation induction period tends to be short.
[0068]
Therefore, it can be said that when the remaining life of the thermoplastic resin composition waste material is long, the oxidation induction period also becomes long, and when the remaining life of the thermoplastic resin composition waste material is short, the oxidation induction period tends to be short.
[0069]
Similarly, when there is a large amount of remaining antioxidant in the thermoplastic resin composition waste, the oxidation induction period is lengthened, and when there is a small amount of antioxidant remaining in the thermoplastic resin composition waste. It can be said that the oxidation induction period also tends to be shortened.
[0070]
Further, as shown in FIG. 3 and FIG. 4 in Examples described later, a certain relationship is established between the remaining life of the thermoplastic resin composition waste and the oxidation induction period, and the thermoplastic resin composition A certain relationship is also established between the remaining amount of the antioxidant in the waste material and the oxidation induction period.
[0071]
Therefore, by measuring the oxidation induction period of the thermoplastic resin composition waste material, the remaining life of the thermoplastic resin composition waste material and the remaining amount of the antioxidant in the thermoplastic resin composition waste material are highly reliable. It can be said that it can be known.
[0072]
In the measurement step of the present invention, the thermoplastic resin composition waste material for which the oxidation induction period is measured may remain in the recovered state, but in order to accurately measure the oxidation induction period, disassembly It is preferably a powdery body that has undergone treatment such as crushing and washing. Further, the recovered thermoplastic resin composition waste material may be heated and melted once and extruded into a certain shape as a measurement target.
[0073]
Here, in the measurement step in the present invention, the predetermined holding temperature is desirably determined according to the classification of the thermoplastic resin composition waste material.
[0074]
And it is preferable to classify | categorize this thermoplastic resin composition waste material based on the system | strain of the main thermoplastic resins contained in a thermoplastic resin composition waste material. This is because various properties including the oxidation induction period of the thermoplastic resin composition waste material change based on the main thermoplastic resin system.
[0075]
In addition, if this predetermined holding temperature is too high, the oxidation induction period tends to be too short and it is difficult to make a significant difference. If this predetermined holding temperature is too low, the oxidation induction period becomes too long for measurement. It takes too much time. Therefore, it is preferable to set the predetermined holding temperature so that the oxidation induction period is in the range of 1 to 30 minutes according to the classification of the thermoplastic resin composition waste material.
[0076]
Therefore, in accordance with the classification of the thermoplastic resin composition waste material, a database in which the predetermined holding temperature is determined is created in advance, and the predetermined holding temperature is determined with reference to information recorded in the database. It is preferable.
[0077]
That is, in the measurement process of the present invention, the predetermined holding temperature is desirably determined according to the classification of the thermoplastic resin composition waste material based on the information recorded in the database.
[0078]
The predetermined holding temperature may be adjusted manually by the measurer while referring to the information recorded in this database when performing the measurement of the oxidation induction period. This database is recorded in the storage device of the computer, and the classification of the thermoplastic resin composition waste material is input to the electronic computer by a certain means, whereby the program in the electronic computer is recorded in this database. It is preferable to automatically adjust the predetermined holding temperature with reference to the information.
[0079]
<Decision process>
In the determination step in the present invention, the addition amount of the antioxidant is determined based on the measurement result of the oxidation induction period by the measurement step described above, and the addition amount of the antioxidant added to the thermoplastic resin composition waste material. Can be determined by any method, but since it is a simple and accurate method, it is particularly useful for classifying and using thermoplastic resin composition waste materials based on information recorded in a database. Obtain the required amount of antioxidants as required, and based on the information recorded in the database, from the measured values obtained in the measurement process, the remaining antioxidant in the thermoplastic resin composition waste material oxidation induction period It is preferable to determine the residual amount of the agent by determining the difference between the necessary amount and the residual amount.
[0080]
In this case, the thermoplastic resin composition waste material is preferably classified based on the main thermoplastic resin system contained in the thermoplastic resin composition waste material. This is because, based on the main thermoplastic resin system, the content of the antioxidant to be included varies depending on the application.
[0081]
In this case, the necessary amount of the antioxidant for the thermoplastic resin composition waste material is required depending on the use of the thermoplastic resin composition molded article obtained by classification and recycling of the thermoplastic resin composition waste material. It is preferable that the content of the antioxidant is required according to the remaining life. That is, the required remaining life value is obtained by applying a certain relationship established between the antioxidant content in the thermoplastic resin composition waste and the remaining life. It is preferable.
[0082]
Furthermore, in this case, the remaining amount of the antioxidant remaining in the thermoplastic resin composition waste material is determined by using the measured value of the oxidation induction period obtained in the measurement step as the antioxidant in the thermoplastic resin composition waste material. It is preferable to be obtained by applying a certain relationship established between the residual amount of cis and the oxidation induction period.
[0083]
Then, the difference between the above required amount and the remaining amount is obtained, and an amount of antioxidant corresponding to the difference is added to the thermoplastic resin composition waste material in the addition step, and is heated and melted. By molding the plastic resin composition waste material, a thermoplastic resin composition molded body having the required antioxidant content can be obtained.
[0084]
As a specific example, the thermoplastic resin composition waste material is a resin composition waste material containing a polyolefin resin as a main component, the antioxidant is a phenolic antioxidant, and in the determination step in the present invention, The measured value of the oxidation induction period measured in the measurement step is a (minute), the remaining amount of antioxidant in the thermoplastic resin composition waste is b (% (w / w)), and the required amount of antioxidant is c. In the case of (% (w / w)), b is obtained based on the relational expression derived from the graph shown in FIG. 4: b = 0.055loga−0.017, and (c−b−0. 05) It is preferable to determine the addition amount of the antioxidant within the above range.
[0085]
Further, the required amount c is d (hour) for the remaining life of the thermoplastic resin composition waste material, and e (hour) for the remaining life required for the thermoplastic resin composition molded body obtained by recycling. In this case, it is preferably determined based on the relational expression derived from the graphs shown in FIGS. 3 and 4: c = 0.066 log (e / d).
[0086]
By adding an amount of an antioxidant determined based on these relational expressions to the thermoplastic resin composition waste, a thermoplastic resin composition molded article having a remaining life required depending on the application is obtained. Can do.
[0087]
Moreover, even when the thermoplastic resin composition waste material and the antioxidant are different in classification, it is preferable to obtain the above relational expression in advance. Furthermore, it is preferable to create a database in which those relational expressions are recorded.
[0088]
And by referring to the information recorded in such a database, the content (required amount) of the antioxidant required according to the classification and use of the thermoplastic resin composition waste material, and the thermoplastic resin composition It is preferable to determine the content (residual amount) of the remaining antioxidant in the waste material oxidation induction period.
[0089]
That is, in the determination step of the present invention, the amount of antioxidant added is determined based on the information recorded in the database, based on the thermoplastic resin composition waste obtained by classification and recycling of the thermoplastic resin composition waste material. Obtain the required amount of antioxidant required according to the application, and based on the information recorded in the database, from the measured value obtained in the measurement process, the remaining thermoplastic resin composition waste material oxidation induction period It is preferable to determine by determining the residual amount of the antioxidant and determining the difference between the required amount and the residual amount.
[0090]
The amount of the antioxidant added may be determined by the operator himself / herself while referring to the information recorded in the database before adding the antioxidant. From this, the database is recorded in a storage device of an electronic computer, the thermoplastic resin composition waste obtained by classifying and recycling the above thermoplastic resin composition waste by a certain means, and the above-mentioned When the measured value of the oxidation induction period in the measurement process is input to the computer, the program in the computer refers to the information recorded in this database and automatically determines the addition amount of this antioxidant. It is preferable to do.
[0091]
<Addition process>
The method for recycling a thermoplastic resin composition waste material according to the present invention includes a step of adding and heating and melting the thermoplastic resin composition waste material with an addition amount of the antioxidant determined in the above determination step.
[0092]
Here, in the addition step in the present invention, the addition of the antioxidant may be performed by manually measuring the addition amount of the antioxidant determined by the operator and adding it manually. From the above, it is preferable to measure by an automatic metering device connected to an electronic computer capable of determining the amount of addition of the antioxidant and to add the antioxidant by an automatic adding device.
[0093]
Further, in the addition step 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 this specification) is added. It may be heated and melted.
[0094]
In this way, by adding an unused thermoplastic resin composition to the thermoplastic resin composition waste material used in the present invention, molding a thermoplastic resin composition obtained by recycling from the thermoplastic resin composition waste material This is because the quality of the body can be further improved.
[0095]
Here, it is preferable that the unused thermoplastic resin composition is a thermoplastic resin composition of the same system as the thermoplastic resin composition which is a main component of the thermoplastic resin composition waste material.
[0096]
That is, as a specific example, when the main component of the thermoplastic resin composition waste is a polyolefin resin composition, it is desirable to add a polyolefin resin composition as an unused thermoplastic resin composition. .
[0097]
In this case, the unused thermoplastic resin composition to be added is adapted to the use and required characteristics of the thermoplastic resin composition molded body obtained by recycling from the thermoplastic resin composition waste material, It is preferable to select an appropriate type.
[0098]
In addition, the amount of the unused thermoplastic resin composition to be added is preferably from the aspect of the quality of the molded thermoplastic resin composition obtained by recycling from the thermoplastic resin composition waste material as the amount is larger. However, too much is not preferable from the viewpoint of production cost and recycling rate.
[0099]
Therefore, the amount of the unused thermoplastic resin composition to be added is appropriately adjusted according to the required characteristics of the molded product to be recycled, and the thermoplastic resin composition waste material and the unused thermoplastic resin composition are adjusted. It is desirable to do.
[0100]
In addition, in the addition step in the present invention, in addition to the above-described components, the thermoplastic resin composition waste material further includes a heat stabilizer, a light stabilizer, an antistatic agent, a lubricant, a filler, a copper damage inhibitor, an antibacterial agent, You may add conventionally well-known additives, such as a coloring agent, as needed in the range which does not interfere with the characteristic of the thermoplastic resin composition molded object obtained by recycling this thermoplastic resin composition waste material. The timing for adding these additives is preferably when the raw materials are charged into an extrusion molding machine to be described later.
[0101]
Moreover, in the addition process in this invention, it is preferable to stir and mix the thermoplastic resin composition waste material heat-melted, after adding other components, so that the composition may become uniform.
[0102]
<Molding process>
The method for recycling a thermoplastic resin composition waste material according to the present invention includes a step of molding the thermoplastic resin composition waste material heated and melted in the addition step to obtain a thermoplastic resin composition molded body.
[0103]
Here, in this specification, when it is described as a thermoplastic resin composition molded article, not only a thermoplastic resin composition molded article as a normal product or its parts, but also a thermoplastic molded into a certain shape. The resin composition raw material is also included.
[0104]
The heating and melting in the addition step in the present invention and the extrusion molding in the molding step in the present invention are not particularly limited as long as they are devices capable of heating and melting and extrusion molding, and are performed using any conventionally known device. However, in terms of productivity and the quality of the thermoplastic resin composition molded product obtained by recycling the thermoplastic resin composition waste, single-screw extruder, twin-screw extruder or multi-screw extruder It is particularly preferable to carry out using any extrusion molding machine.
[0105]
Further, in the molding step of the present invention, considering versatility, it is preferable to mold the thermoplastic resin composition raw material with a certain shape from the thermoplastic resin composition waste material that has been heated and melted. You may produce the thermoplastic resin composition molded object which has a fixed shape directly from a plastic resin composition waste material.
[0106]
Furthermore, in the molding step of the present invention, the shape of the thermoplastic resin composition raw material obtained is preferably a pellet shape that is a general shape of the resin composition raw material, but is not particularly limited to a pellet shape, for example, It may be in the form of a sheet, a film, a pipe, etc., and may be determined as appropriate from the type of the extruder.
[0107]
In the molding step of the present invention, when the thermoplastic resin composition waste material that has been heated and melted is molded into a pellet-shaped thermoplastic resin composition material, a pellet-shaped thermoplastic resin composition material is produced. In addition to the above-described extrusion molding machine, any cutting machine such as sheet cutting, strand cutting, hot air cutting, underwater cutting, etc. may be used. An underwater cut that can smoothly supply the raw material of the plastic resin composition and can cope with a large amount of processing is particularly preferable.
[0108]
<Process flow>
An example of the flow of the process for recycling the thermoplastic resin composition waste material of the present invention will be described with reference to the process chart shown in FIG.
[0109]
In the process flow shown in FIG. 2, first, a product including the thermoplastic resin composition waste material is collected from the market, and then the product including the thermoplastic resin composition waste material is disassembled by manual dismantling or the like. The plastic resin composition waste is separated. And the separated thermoplastic resin composition waste material is shredded and crushed into a powdery body, and washed to remove dirt and impurities. Then, the washed powdery thermoplastic resin composition waste is heated and melted and kneaded, and formed into a fixed shape by extrusion.
[0110]
The thermoplastic resin composition waste material thus molded into a certain shape is measured in the oxidation induction period in the measurement step, and the addition amount of the antioxidant is determined in the determination step. Then, the determined amount of antioxidant is added in the addition step, and the mixture is heated and melted and kneaded. In the molding step, it is extruded and formed into a thermoplastic resin composition molded body having a certain shape. The above is an example of the process flow of the method for recycling the thermoplastic resin composition waste material of the present invention shown in FIG.
[0111]
FIG. 2 is a diagram showing an example of the process flow of the method for recycling the thermoplastic resin composition waste material of the present invention, but the method for recycling the thermoplastic resin composition waste material of the present invention is shown in FIG. It is not limited to this flow.
[0112]
That is, in the process flow shown in FIG. 2, the measurement of the oxidation induction period of the thermoplastic resin composition waste material is carried out after the thermoplastic resin composition waste material is once heated and melted and extruded into a certain shape. However, the timing of the measurement of the oxidation induction period of the thermoplastic resin composition waste material is not particularly limited, and it is performed at different timings in the process flow of the method of recycling the thermoplastic resin composition waste material of the present invention. Also good.
[0113]
For example, the recovered thermoplastic resin composition waste material is disassembled, shredded, crushed, washed without first melting the recovered thermoplastic resin composition waste material and extruding it into a certain shape. The oxidation induction period may be measured immediately.
[0114]
Moreover, the recycling method of the thermoplastic resin composition waste material of this invention does not need to provide all the processes shown in FIG. 2, and if it has the above-mentioned measurement process, determination process, addition process, and molding process. Some steps may be omitted, and steps other than the steps shown in FIG. 2 may be added.
[0115]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.
[0116]
<Example>
A used washing machine collected from the market is dismantled, and a water tank, a dehydration tank, and an upper lid, which are molded products of a resin composition containing a polypropylene-polyethylene block copolymer resin, which is a typical crystalline thermoplastic resin, Each was individually removed and pulverized. Next, the finely crushed thermoplastic resin composition waste material was washed to remove dirt, and each was uniformly mixed.
[0117]
Then, the mixed thermoplastic resin composition waste powder is heated, melted, kneaded and extruded at a temperature of 230 ° C. using a screw-type 45 mm biaxial melt-kneading extruder and cut with an underwater cutting device. Then, pelletized thermoplastic resin composition waste powders were individually prepared.
[0118]
Thereafter, these pellet-like thermoplastic resin composition waste powders are put into a hopper of a 10-ton extrusion molding machine, and the respective thermoplastic properties are obtained under the extrusion molding conditions of a heating and melting temperature of 230 ° C. and a mold temperature of 40 ° C. Test specimens for measuring physical properties based on ASTM made of resin composition waste were individually prepared, and the physical properties, oxidation induction period, and crack generation time were individually measured. The measurement results are shown in Table 2.
[0119]
Here, in this specification, among the test pieces for measuring physical properties in accordance with ASTM composed of the thermoplastic resin composition waste material obtained from each part, the test piece derived from the water tank is “RS”, derived from the dehydration tank. The test piece is also referred to as “RD”, and the test piece derived from the upper lid is also referred to as “RU”.
[0120]
Further, for comparison, a test piece for measuring physical properties in accordance with ASTM (hereinafter referred to as “V-0”) using a general grade virgin material of a resin composition containing a polypropylene-polyethylene block copolymer resin. And the physical properties, oxidation induction period, and crack generation time were measured. The measurement results are shown in Table 2.
[0121]
[Table 2]

[0122]
As shown in Table 2, the tensile strength, bending strength, bending elastic modulus, and Izod impact strength of “RS”, “RD”, and “RU” are respectively “V-0”. It was roughly equivalent.
[0123]
However, “RS”, “RD”, and “RU” have a shorter oxidation induction period and a shorter crack generation time corresponding to the oxidation induction period than “V-0”. . Therefore, in order to recycle these thermoplastic resin composition waste materials, these thermoplastic resin compositions are used according to the required characteristics of the members made of the thermoplastic resin composition molded body obtained by recycling. It can be seen that it is necessary to extend the remaining life of the waste.
[0124]
Next, the oxidation induction period and crack generation time of a test piece made of five thermoplastic resin composition waste materials including “RS”, “RD”, “RU”, and “V-0” were measured. did. The measurement results are shown in FIG.
[0125]
Here, in this specification, the time until the occurrence of a crack is also referred to as a “crack occurrence time”. In the technical field to which the present invention belongs, the thermal oxidation deterioration test is considered to be one of accelerated tests for examining the remaining life of these thermoplastic resin composition waste materials. It is common technical knowledge that “time” indicates a value corresponding to the remaining life.
[0126]
As a result, as understood from FIG. 3, in these thermoplastic resin composition wastes, a certain correlation was recognized between the oxidation induction period and the remaining life.
[0127]
Therefore, by measuring the oxidation induction period of the thermoplastic resin composition waste material in this way, the remaining life of the thermoplastic resin composition waste material can be easily grasped. Therefore, by modifying the thermoplastic resin composition waste material according to the required characteristics of the thermoplastic resin composition molded product obtained by recycling, the thermoplastic resin composition waste material can be recycled to various uses through material recycling. It becomes possible to recycle.
[0128]
Here, in general, a thermoplastic antioxidant such as a polypropylene-polyethylene block copolymer resin composition is added with a phenol-based antioxidant and a phosphorus-based antioxidant, and becomes a base polymer thermoplastic. The remaining life of the resin is stabilized. Further, in order to improve the heat resistance grade, a sulfur-based antioxidant having a function of enhancing thermal stability is often added.
[0129]
These antioxidants are gradually consumed when the thermoplastic resin composition molded article is used, and have a function of stabilizing the base polymer. Therefore, it is considered that the amount of the antioxidant contained in the thermoplastic resin composition waste material is considerably reduced from the initial addition amount.
[0130]
In order to confirm this point, the amount of antioxidant contained in each of “RS”, “RD”, “RU”, and “V-0” prepared in Example 1 was measured. Table 3 shows the measurement results.
[0131]
[Table 3]

[0132]
As understood from Table 3, the consumption amount of the phenolic antioxidant varies depending on the usage environment of the thermoplastic resin composition waste material, and the phosphorus antioxidant and the sulfurous antioxidant are almost the same regardless of the usage environment. The whole amount was consumed. Therefore, if the composition of the thermoplastic resin composition waste material is grasped, it is possible to easily grasp the residual amount of the phenolic antioxidant by measuring the oxidation induction period.
[0133]
Next, in order to clarify the relationship between the residual amount of the phenolic antioxidant and the oxidation induction period, the powder of the thermoplastic resin composition waste material having the same composition as “RD” in the mixing step of FIG. In the body, tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane (made by Asahi Denka Kogyo Co., Ltd.), which is a hindered phenol antioxidant, A predetermined amount of ADK STAB AO60) was added to prepare a test piece, and the oxidation induction period was measured. The measurement results are shown in FIG.
[0134]
As can be seen from FIG. 4, there is a certain correlation between the amount of phenolic antioxidant added (approximately equal to the remaining amount) and the oxidation induction period, and the amount of phenolic antioxidant added By changing it, it is possible to improve the oxidation induction period, that is, the remaining life of the thermoplastic resin composition waste material.
[0135]
Next, the amount of the phenolic antioxidant added is varied to modify the powder of the thermoplastic resin composition waste material having the same composition as “RD” based on the three types of formulation, and the thermoplastic having the same composition Recycled resin composition waste powder into multiple types of molded thermoplastic resin compositions with different required properties, and created test specimens for measuring physical properties in accordance with ASTM. Physical properties and oxidation of each specimen The induction period and crack generation time were measured individually. Table 4 shows the measurement results.
[0136]
In addition, since it is common that the addition amount of the phosphorus antioxidant in a thermoplastic resin composition is 1-3 times the amount of a phenolic antioxidant, in a present Example, it is a phenolic antioxidant. It was decided to add a phosphorus-based antioxidant twice as much as the sum of the remaining amount and the added amount.
[0137]
That is, in this experiment, in Formulation 1, 0.07 parts by mass of phenol-based antioxidant and 0.2 parts by mass of phosphorus-based antioxidant with respect to 100 parts by mass of the thermoplastic resin composition waste material. Was added.
[0138]
Moreover, in this experiment, in the prescription 2, with respect to 100 parts by mass of the powder of the thermoplastic resin composition waste material, 0.11 parts by mass of phenol-based antioxidant and 0.25 parts by mass of phosphorus-based antioxidant Was added.
[0139]
In this experiment, in Formulation 3, 0.11 parts by mass of a phenol-based antioxidant and 0.25 parts by mass of a phosphorus-based antioxidant with respect to 100 parts by mass of the thermoplastic resin composition waste material. In order to further improve the heat resistance, 0.08 parts by mass of a sulfur-based antioxidant was added.
[0140]
In Formulas 1 to 3, phenolic antioxidants (Asahi Denka Kogyo Co., Ltd., Adeka Stub AO60) and phosphorus antioxidants (Asahi Denka Kogyo Co., Ltd., Adekastab 2112), sulfur antioxidants (Yoshinox DMTP manufactured by Yoshitomi Fine Chemical Co., Ltd.) was used.
[0141]
Furthermore, for comparison, with respect to “V-0” and “V-1”, the physical properties, oxidation induction period, and crack generation time of each test piece were individually measured.
[0142]
Here, “V-1” is a general grade polypropylene resin from a manufacturer different from V-0.
[0143]
[Table 4]

[0144]
As understood from Table 4, by applying the formulations 1 to 3, the improvement of the oxidation induction period and crack generation time of the thermoplastic resin composition waste material is remarkable.
[0145]
Therefore, the thermoplastic resin composition waste material subjected to the prescription 1 is an alternative material of the thermoplastic resin composition molded body having the same composition as “V-0”, and the thermoplastic resin composition waste material subjected to the prescription 2 is It becomes possible to recycle as an alternative material of the thermoplastic resin composition molded body having the same composition as “V-1”.
[0146]
The physical property values such as the tensile strength are slightly inferior to those of “V-0” and “V-1” even if the thermoplastic resin composition waste is subjected to the prescriptions 1 to 3. If it exists, in addition to the antioxidant, it can be modified by mixing an appropriate amount of a virgin material.
[0147]
Therefore, the thermoplastic resin having several characteristics from a single composition of the thermoplastic resin composition waste material can be obtained by appropriately changing the formulation of the modification and adding an appropriate amount of an antioxidant and / or a virgin material. The resin composition molded body can be obtained by recycling, and the use of the thermoplastic resin composition molded body obtained by recycling from the thermoplastic resin composition waste can be expanded.
[0148]
<Measurement method>
Various physical properties (tensile strength, bending strength, flexural modulus, Izod impact strength), oxidation induction period, and crack generation time measured in the above examples were measured according to the following measurement methods.
[0149]
(I) Measuring method of tensile strength and tensile modulus
Tensile strength and tensile elastic modulus were measured in accordance with JIS K7113 using ASTM-compliant physical property measurement test pieces.
[0150]
(Ii) Measuring method of bending strength and bending elastic modulus
Bending strength and bending elastic modulus were measured according to JIS K7203 using ASTM-compliant test pieces for measuring physical properties.
[0151]
(Iii) Measuring method of Izod impact strength
Izod impact strength was measured according to JIS K7110 using ASTM-compliant test specimens for measuring physical properties.
[0152]
(Iv) Method for measuring oxidation induction period
Using a test sample having a shape of φ4 mm and a thickness of 1 mm, measurement was performed using a thermal analyzer (manufactured by Seiko Denshi Kogyo Co., Ltd., TG / DTA320U). First, the test sample was heated to 210 ° C. in a nitrogen atmosphere, held for 10 minutes, then switched to an air atmosphere, and the time until the test sample started an exothermic reaction was measured as an oxidation induction period.
[0153]
(V) Method for measuring crack occurrence time
As an accelerated test for evaluating the remaining life, a test piece for measuring physical properties in accordance with ASTM was placed in a 140 ° C. gear-type oven, a thermal oxidation deterioration test was performed, and a time until a crack was generated was measured. And this crack generation time was used for evaluation of remaining life.
[0154]
It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[0155]
【The invention's effect】
From the above results, the method for recycling the thermoplastic resin composition waste material according to the present invention is suitable for various uses from the thermoplastic resin composition waste material by material recycling using the thermoplastic resin composition waste material as a main raw material. It can be said that this is an efficient and low-cost method for recycling a thermoplastic resin composition waste material, which can provide a thermoplastic resin composition molded article having quality and remaining life.
[0156]
In addition, the method for producing the thermoplastic resin composition molded body of the present invention using the method for recycling the thermoplastic resin composition waste material of the present invention is a method for producing a thermoplastic resin composition waste material from a thermoplastic resin composition waste material. It can be said that this is a method capable of producing a thermoplastic resin composition molded article having quality and remaining life corresponding to various uses by material recycling as a main raw material.
[0157]
The thermoplastic resin composition molded article of the present invention obtained by using the method for recycling the thermoplastic resin composition waste of the present invention is obtained by material recycling using the thermoplastic resin composition waste as the main raw material. It can be said that it is a thermoplastic resin composition molded article having quality and remaining life corresponding to various uses.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a conceptual diagram describing a graph showing an example of a general tendency of characteristic deterioration of a thermoplastic resin composition molded article.
FIG. 2 is a process diagram showing an example of a process flow of a method for recycling a thermoplastic resin composition waste material according to the present invention.
FIG. 3 is a graph showing an example of a correlation between an oxidation induction period and a crack generation time in an example of the present invention.
FIG. 4 is a graph showing an example of the correlation between the added amount of antioxidant and the oxidation induction period in the examples of the present invention.

Claims (11)

A measuring step for measuring the oxidation induction period of the thermoplastic resin composition waste material, a determining step for determining an addition amount of the antioxidant added to the thermoplastic resin composition waste material based on the measurement result, and the thermoplastic resin An addition step of adding the determined addition amount of the antioxidant to the composition waste material and heating and melting, and molding the heat-melted thermoplastic resin composition waste material to obtain a molded thermoplastic resin composition A method of recycling a waste thermoplastic resin composition comprising a molding step. In the measurement step, the holding temperature of the thermoplastic resin composition waste material when measuring the oxidation induction period is determined according to the classification of the thermoplastic resin composition waste material based on information recorded in a database. The method for recycling a waste material of a thermoplastic resin composition according to claim 1. In the determining step, the amount of the antioxidant added is determined based on the information recorded in the database. The use of the thermoplastic resin composition molded body obtained by classifying and recycling the thermoplastic resin composition waste material The necessary amount of the antioxidant required according to the above is obtained, and further, based on the information recorded in the database, from the measurement value obtained in the measurement step, it remains in the thermoplastic resin composition waste material The method for recycling a waste thermoplastic resin composition according to claim 1 or 2, wherein the residual amount of the antioxidant is determined and the difference between the required amount and the residual amount is determined. The said addition process WHEREIN: In addition to the said thermoplastic resin composition waste material and the said antioxidant, in addition, an unused thermoplastic resin composition is added, and it heat-melts. The recycling method of the thermoplastic resin composition waste material in any one. The thermoplastic resin according to any one of claims 1 to 4, wherein in the molding step, the heat-melted thermoplastic resin composition waste material is molded into a pellet-shaped thermoplastic resin composition raw material. A method for recycling composition waste. The method for recycling a thermoplastic resin composition waste material according to any one of claims 1 to 5, wherein the thermoplastic resin composition waste material is a resin composition waste material containing a polyolefin resin as a main component. . The said antioxidant is a phenolic antioxidant, The recycling method of the thermoplastic resin composition waste material in any one of Claims 1-6 characterized by the above-mentioned. 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 is measured in the measurement step in the determination step. When the measured value of the oxidation induction period is a (minute), the remaining amount is b (% (w / w)), and the required amount is c (% (w / w)), b = 0.05loga The amount of the antioxidant is determined in the range of (c-b-0.05) or more by obtaining b based on the equation of -0.017. The recycling method of the thermoplastic resin composition waste material as described. The required amount c is a case where the remaining life of the thermoplastic resin composition waste is d (hour) and the remaining life required for the thermoplastic resin composition molded body obtained by recycling is e (hour). 9. The method for recycling a thermoplastic resin composition waste material according to claim 8, wherein the thermoplastic resin composition waste material is determined based on an equation of c = 0.066 log (e / d). A method for producing a thermoplastic resin composition molded article, wherein a thermoplastic resin composition molded article is obtained by the method for recycling a thermoplastic resin composition waste material according to any one of claims 1 to 9. A thermoplastic resin composition molded article obtained by the method of recycling a thermoplastic resin composition waste material according to any one of claims 1 to 9 ,
The thermoplastic resin composition waste material is a resin composition waste material containing a polyolefin resin as a main component, and the antioxidant is a phenolic antioxidant,
When the remaining life of the thermoplastic resin composition waste material is d (hour) and the remaining life of the molded thermoplastic resin composition obtained by the recycling method is e (hour), c = 0.066 log ( A thermoplastic resin composition molded article comprising a necessary amount c (% (w / w)) of an antioxidant determined based on the equation of e / d) .

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