Multi-segment polymerization method and device for propylene

Abstract

The invention relates to a multi-segment polymerization method and device for propylene. The method comprises the steps that firstly, a pre-polymerization reaction is conducted, then a liquid-phase polymerization reaction and a gas-phase polymerization reaction are conducted, a two-step reaction is set at the liquid-phase polymerization reaction, the reaction time is prolonged, a polymer can havewider molecular weight distribution, and the processing performance and mechanical performance of the polymer are improved; in the gas-phase polymerization reaction, a horizontal reactor and a vertical reactor are used for conducting the two-step reaction, and the molecular weight distribution is further widened. By means of the multi-segment polymerization method and device for propylene, homo-polypropylene, binary polypropylene random copolymer, ternary polypropylene random copolymer or impact copolymer polypropylene with high flow and high rubber content can be produced, and the prepared polymer is even in particle diameter distribution, low in volatile matter and organic content, wide in molecular weight distribution and excellent in processing performance and mechanical performance.

Description

technical field [0001] The invention belongs to the field of polymer material preparation, and in particular relates to a multi-stage polymerization method and device for propylene. Background technique [0002] In the existing propylene polymerization process, the difference in the composition of the intermediate monomers in each reaction section is small, and even if a single reactor is used, only a single system of catalyst can be used, the control difference of the reaction system is not obvious, and the mechanical properties of the obtained polymer are better than Processing performance is limited. [0003] In the prior art, when adopting the polymerization process of the double-horizontal gas phase reactor in series to produce the impact-resistant copolymerized polypropylene, although the particle size of the polymer particles is uniform, the condensation is limited, the hydrogen and ethylene contents in the reactor are not high, and the polymerization Physical impact...

AI Technical Summary

Problems solved by technology

[0002] In the existing propylene polymerization process, there is little difference in the composition of intermediate monomers in each reaction stage, and even a single reactor is used, and only a single system of catalyst can be used. The difference in the control of the reaction system is not obvious, and the obtained polymer mechanical properties and Limited improvement in processing performance

[0003] In the prior art, when the polymerization process of double-horizontal gas-phase reactors in series is used to produce impact copolymerized polypropylene, although the particle size of the polymer particles is uniform, the condensation is limited, the hydrogen and ethylene content in the reactor is not high, and the polymerization Physical impact performance is not outstanding

Or use a polymerization process with two gas-phase fluidized bed reactors connected in series, however, due to the uneven particle size distribution, the impact copolymer polypropylene produced has poor impact performance

[0004] In addition, if a pure gas phase polymerization reactor is used to directly add the catalyst, due to the high initial activity of the catalyst, it is prone to breakage and local overheating due to uneven dispersion, which not only affects the long-term operation of the device, but also limits the performance of the catalyst.

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