Preparation method of polypropylene containing homoallylic end group

Abstract

The invention relates to a preparation method of polypropylene containing a homoallylic end group. The following catalysts are adopted: (1) a main catalyst is one or mixture of metallocenes with the following general formulas: R2Y[3-R'-Ind]2MC12, wherein Ris H or CH3; Y is C or Si; R' is H, CH3, CH(CH3)2 or C(CH3)3; and M is Zr or Hf; and (2) a cocatalyst is methylaluminoxane in which alkyl aluminium is removed; the allyl end group content in the obtained polypropylene is generally more than 80% and can reach 100%; and the cocatalyst has the characteristics of high isotacticity, narrow molecular weight distribution and the like. The polypropylene of an allyl end group with reactivity can be used for preparing branched polypropylene so that important application values and prospects are obtained.

Description

technical background [0001] Polypropylene is one of the most widely used general-purpose plastics. By improving the chain structure of polypropylene to improve its performance, its application range can be further expanded. It has been shown that the introduction of reactive groups at the chain ends of polymers can be used to prepare branched polymers, thereby improving the processing properties of the original polymers. Therefore, the preparation of polypropylene with reactive allyl end groups can also be used to prepare branched polypropylene, which will have important application value. [0002] In the field of polyolefins, there have been reports of preparing ethylene polymers with vinyl end groups and using them to obtain branched polymers, but there are not many examples of polypropylene in this regard. The reason is that the commonly used Ziegler-Natta catalyst catalyzes the chain transfer reaction in propylene polymerization, which is complicated and difficult to con...

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Problems solved by technology

Chinese patent CN1274367 discloses a method for preparing polypropylene macromonomers with vinyl end groups. However, this method requires polymerization at a high temperature above 95°C, or even 110°C. Excessively high reaction temperatures will reduce the polymer The stereoregularity of the polymer is also easy to make the polymer sticky and affect the application in industry

Although such a high polymerization temperature was used, the resulting polymer did not contain more than 80% vinyl end groups, and more importantly, the patent did not consider the effect of chain transfer to the alkylaluminum during the polymerization reaction , so in fact the vinyl end group content of the resulting polymer is even lower

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