Method for preparing high-fluidity wide-distribution polypropylene and product thereof

Abstract

The invention discloses a method for preparing high-fluidity wide-distribution polypropylene and a product thereof. The method uses propylene for homopolymerization or copolymerization. A catalyst system consists of a component A, a component B and a component C, wherein the component A is a supported solid Ziegler-Natta catalyst taking magnesium, titanium, halogen and an internal electron donor as main components; the component B is an alkyl aluminum cocatalyst; and the component C is an external electron donor, and is a mixture of tetraethoxy silane and dicyclopentyl dimethoxy silane or diisobutyldimethoxysilane, wherein the dicyclopentyl dimethoxy silane or the diisobutyldimethoxysilane accounts for 0.1 to 10 percent of the total molar weight of the mixture; the component A, the component B and the component C are expressed by the content of Ti, the content of Al and the content of Si, and the molar ratio of Si to Ti is 1 to 100, and the molar ratio of Al to Si is 1 to 100 respectively; the polydispersity index of the product is between 6 and 20; and the melt index of the product with the mass of 2.16kg at the temperature of 230 DEG C is between 20 and 200g / 10min.

Description

technical field [0001] The invention relates to a method and product for preparing high flow and wide distribution polypropylene by applying a Ziegler-Natta catalytic system containing a specific composite electron donor pair to propylene polymerization or propylene and ethylene copolymerization. Background technique [0002] High-flow polypropylene PP is obtained by polymerizing propylene under the action of a catalytic system. In the polymerization system, hydrogen is introduced as a chain transfer agent to adjust the molecular weight, thereby regulating the melt index of PP. For conventional catalytic systems, due to the insensitivity of hydrogen adjustment, to improve the fluidity of PP, it is necessary to increase the amount of hydrogen introduced, which will greatly increase the operational difficulty of the production process, so the adjustable range is limited. The catalytic system of propylene polymerization is commonly used Ziegler-Natta catalytic system, the expre...

AI Technical Summary

Problems solved by technology

Hoechst company's patent US5100981 proposes compounding with phenyltriethoxysilane (PTES) and cyclohexylmethyldimethoxysilane (CHMDMS) in a ratio of 1:1 to prepare highly isotactic, narrowly distributed poly Propylene, and the catalyst has high activity. Obviously, this compound electron donor cannot be used to prepare high-flow, wide-distribution PP

In the patent EP0385765, Mitsui Oil & Chemical Company uses dicyclopentyldimethoxysilane (DCPDMS) and propyltriethoxysilane (PTES) in an equimolar ratio to compound the electron donor pair, which can prepare poly Propylene, and in its patent EP0601496, discussed how to apply the composite electron donor pair in the industrial device, and proposed to use a single electron donor in the two polymerization tanks, and then combine the electron donors in the two tanks Polypropylene is placed in a larger tank for polymerization, and high flow and wide distribution of polypropylene can be obtained in industrial devices, but it is inconvenient to add the two electron donors separately.

BPAmoco, in the patent US2003 / 0149196A1, proposed the compounding technology of TEOS and DCPDMS in gas phase polymerization to prepare high-flow polypropylene materials. Here, the researchers still believe that the results obtained by compounding DCPDMS and TEOS are similar to DCPDMS alone. , so it is necessary to add different types of electron donors in different cascaded polymerizers to obtain high-flow, wide-distributed polypropylene, which brings troubles to the feeding of electrons in industrial applications.

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