Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
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Effect of Cocatalyst Type on the Characteristics of Olefin Polymerization with In-situ Supported Metallocene Catalysts

In-situ 담지된 메탈로센 촉매들의 폴리올레핀 중합 특성에 미치는 조촉매 종류의 영향

Park, Yeung-Ho;Lee, Hyung-Woo
박융호;이형우

  • Published : 20021000
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Abstract

An in-situ supporting method was applied to a new metallocene catalyst with a bulky structure, $[(CH_2)_5(C_5H_4)_2][(C_9H_7)ZrCl_2]_2$, and other commercial metallocene catalysts; the polymerization characteristics of the supported catalysts were studied. Polyethylene obtained from the in-situ supported $[(CH_2)_5(C_5H_4)_2][(C_9H_7)ZrCl_2]_2/TMA$ catalyst showed a higher yield, a better morphology, a lower average molecular weight, and a broader molecular weight distribution than the catalyst supported by a traditional method. In-situ supported catalysts also showed that catalytic activities and polymer properties depended on the type of the cocatalyst used. When an alkyl aluminum was used as a cocatalyst, a lower activity was observed than the case of modified methylaluminoxan (MMAO), but it showed the characteristics similar to a heterogeneous catalyst. Trimethyl aluminum (TMA) showed the highest activity in polymerization among other alkyl aluminums, but excess addition of TMA resulted in a lower average molecular weight and activity by inducing deactivation of metallocenes of chain transfer. An in-situ supported $rac-Et(Ind)_2ZrCl_2$ catalyst produced the polypropylene with a higher melting temperature and a lower average molecular weight than a homogeneous system.

이핵메탈로센 $[(CH_2)_5(C_5H_4)_2][(C_9H_7)ZrCl_2]_2$ 촉매와 상용메탈로센 촉매들을 in-situ 담지법에 적용하여 폴리올레핀을 제조하였고, 조촉매인 알킬 알루미늄 종류의 변화에 따른 중합특성을 조사하였다. In-situ 담지된 $[(CH_2)_5(C_5H_4)_2][(C_9H_7)ZrCl_2]_2/TMA$ 촉매를 이용하여 제조된 폴리에틸렌은 균일계 촉매에 비해 구형의 좋은 입자 형상과 낮은 평균분자량 그리고 넓은 분자량분포를 나타내었고 전통적인 담지법에 비해 높은 촉매활성을 나타내었다. In-situ 담지시 조촉매의 종류에 따라 촉매별로 다른 촉매활성과 중합체의 물성이 나타났는데 알킬 알루미늄 사용시 개질된 methylaluminoxane (MMAO) 사용에 비해 낮은 활성을 나타내지만 불균일화 촉매의 효과를 나타내었다. 조촉매로 사용된 알킬 알루미늄들 중 trimethyl aluminum (TMA)가 가장 큰 촉매 활성을 나타내었으나 과량의 TMA는 사슬 전달을 유도하여 얻어진 중합체의 분자량을 감소시키고 활성의 저하를 유도하였다. In-situ 담지된 $rac-Et(Ind)_2ZrCl_2$촉매를 이용하여 폴리프로필렌 제조시 균일계 촉매에 비해 높은 용융점과 낮은 평균분자량을 갖는 중합체를 얻을 수 있었다.

Keywords

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