Propylene Polymerization with Alcohol-activated MgCl2-supported TiCl4 Catalysts; Coditions of Polymerization
Lee DH, Lee JH, Noh SK, Jeong YT
알코올-활성화된 MgCl2 담지 TiCl4촉매에 의한 프로필렌의 중합; 중합 조건
이동호, 이주홍, 노석균, 정영태
Abstract
With the supported TiCl4 catalysts for which MgCl2 was dissolved in ethanol(EtOH) or 2-ethyl-1-hexanol (EHA) and reacted with TiCl4 as solution or after reprecipitation, the effect of polymerization conditions and Lewis bases as internal and external donors on catalyst behaviors have been studied for propylene polymerization. Maximum catalyst activity was obtained for 40℃, [TEA]/[Ti] = 50. Addition of Lewis bases increases catalyst stereoregularity but decreases catalyst activity. The catalyst prepared by reprecipitation method, in which diisobutylphthalate (DIBP) was added in MgCl2 solution, had no Lewis base effect because DIBP was removed in reprecipitation and washing procedures. For external donor, cyclohexyldimethoxymethylsilane gave higher activity, higher isospecificity, lower molecular weight and wider molecular weight distribution than pheny1triethoxysilane.
MgCl2를 ethanol (EtOH), 2-ethyl-1-hexanol (EHA) 등에 녹여 용액상 또는 재침전상으로 담지 TiC14 중합촉매를 제조하여 프로필렌을 중합할 때에, 공촉매인 triethylaluminum(TEA)의 농도, 중합온도 등의 중합조건과 내부염기 (ID)인 diisobutylphthalate (DIBP), 외부염기 (ED)인 phenyltriethoxysilane (PTES) 및 cyclohexyldimethoxymethylsilane (CHDMS) 등이 촉매의 활성과 입체규칙성, 촉매의 구조, 생성된 폴리프로필렌 (PP)의 분자량 및 분자량분포등에 미치는 영 향을 조사하였다. 40℃, [TEA]/[Ti]=50 부근에서 최대의 촉매활성을 나타내었다. 그리고 ID인 DIBP가 담지체인 MgC12와 결합함을 FT-IR로 재확인하였으며, Lewis 염기의 첨가시 활성은 감소하지만 입체 규칙성은 크게 증가하였다. 그러나 EtOH에 녹인 MgCl2용액에 DIBP를 첨가하여 재침전법으로 제조한 촉매에 있어서는, 재침전과 세척과정에서 DIBP가 제거됨에 따라 Lewis 염기의 효과를 볼 수 없었다. ED로 CHDMS를 사용한 경우에 PTES보다 큰 활성과 입체규칙성을 얻었다. CHDMS보다 PTES를 사용한 경우에 PP의 분자량은 높았으나, 분자량분포는 좁게 나타났다.
Keywords: MgCl2-supported TiCl4 catalyst; alcohol-activation; propylene polymerization; Lewis base effect
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