Resources Recycling (자원리싸이클링)

The Korean Institute of Resources Recycling (한국자원리싸이클링학회)
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Production of Liquid Polyester Polyol through the Glycolysis for Low Molecular Degradation of Waste Poly (1,4-Cyclohexylene Dimethylene Terephthalate)

폐Poly(1,4-cyclohexylene dimethylene terephthalate)의 저분자화 글리콜리시스를 통한 액상 폴리에스테르 폴리올 제조

  • Dieu Minh Ngo (Department of Applied Chemistry, Kumoh National Institute of Technology) ;
  • Wonseok Jo (Department of Applied Chemistry, Kumoh National Institute of Technology) ;
  • Hyun Min Jung (Department of Applied Chemistry, Kumoh National Institute of Technology)
  • ;
  • 조원석 (금오공과대학교 응용화학과) ;
  • 정현민 (금오공과대학교 응용화학과)
  • Received : 2023.06.19
  • Accepted : 2023.08.04
  • Published : 2023.08.31
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Abstract

The demand for poly(1,4-cyclohexylenedimethylene terephthalate) (PCT), a polyester with enhanced thermal and mechanical properties owing to the ring structure, is growing, necessitating advancing recycling technologies. However, challenges including preventing of increasing molecular weight and viscosity in the diol removal and concentration process, arise post-depolymerization during the chemical recycling of PCT. This study presents an innovative method to prepare liquid dihydroxyl group-terminated oligomers directly from PCT depolymerization using the metal chelate ethylenediaminetetraacetic acid (EDTA). Initially, PCT was depolymerized using an excess diethylene glycol and a Zn2+ catalyst to form an intermediate. Subsequently, the chelating agent was added, and the residual glycol was distilled and recovered under reduced pressure. EDTA was used to block the activity of the catalyst during high-temperature distillation to afford maximum trimer chain length and low-viscosity liquid polyols. 1H and 13C nuclear magnetic resonance, gel permeation chromatography, and a viscometer were used to confirm the structure, molecular weight distribution, and viscosity of the prepared polyol, respectively. The as-prepared polyols were used as soft segments with 4,4'-methylene-bis(phenyl isocyanate) and 1,4-butanediol during the manufacturing of thermoplastic polyurethanes. The resulting polyurethane was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, and mechanical testing.

고분자 사슬내에 고리 구조 탄소골격의 영향으로 열적, 기계적 물성을 개선한 폴리에스터인 poly(1,4-cyclohexylenedimethylene terephthalate)(PCT)는 뛰어난 내열성, 기계적 강도와 투명성으로 그 사용량이 증가되고 있으며, 이에 따라 폴리에스터계 고분자 재활용의 일환으로서 폐PCT의 화학적 재활용 기술개발이 새롭게 요구되고 있다. 폐PCT 재활용을 위한 저분자화 해중합에서는 반응후 디올의 제거와 농축과정에서 분자량과 점도 상승의 문제가 있어 저점도 폴리올 제조의 문제점이 나타난다. 본 연구에서는 금속 킬레이트 에틸렌디아민테트라아세트산(EDTA)을 사용하여 PCT 해중합 과정에서 액체 디하이드록실 그룹 말단 올리고머를 직접 제조하는 실용적인 접근 방식을 제시하고자 한다. 우선 PCT를 과량의 디에틸렌 글리콜과 Zn2+ 촉매를 사용하여 해중합시키고 중간체를 형성하였다. 그리고 킬레이트제를 첨가한 후, 잔류 글리콜을 증류하고 감압 하에 회수하였다. 고온 증류 중에 촉매의 활성을 차단하기 위해 EDTA를 사용하여 최대 트라이머 사슬 크기 및 저점도 액체 폴리올을 효율적으로 생성했다. 1H 및 13C 핵 자기 공명, 겔 투과 크로마토그래피 및 점도계를 사용하여 제조된 폴리올의 구조 및 분자량 분포와 점도를 확인하였다. 폴리올은 열가소성 폴리우레탄 제조에서 4,4'-메틸렌-비스(페닐 이소시아네이트) 및 1,4-부탄디올과 함께 유연 세그먼트로 사용되었다. 최종 폴리우레탄은 푸리에 변환 적외선 분광법, 열중량 분석 및 기계적 테스트를 사용하여 특성을 확인하였다.

Keywords

Acknowledgement

이 연구는 금오공과대학교 대학 학술연구비로 지원되었음(2021).

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