Polyolefin and preparation method thereof

Abstract

The invention provides a preparation method of polyolefin. According to the preparation method, polyolefin is prepared through two-segment polymerization, and external electron donors are respectivelyadded in the two-segment polymerization process. By optimizing a catalyst feeding process in the polyolefin preparation process, particularly an external electron donor feeding process, an overall synthesis process of the polyolefin can be affected, catalysis activity of a catalyst and stereoregularity of an obtained polyolefin product can be improved, and furthermore macro-properties such as mechanical properties and thermal resistance of the obtained polyolefin product can be improved. Due to adoption of the external electron donor feeding process provided by the invention, and on the basisthat the polyolefin can be easily processed and molded and has the advantage of high modulus, the defect that polyolefin is poor in low-temperature brittleness is alleviated, and meanwhile the thermal resistance of the polyolefin is improved; in addition, the situation that the thermal resistance of the polyolefin is remarkably degraded because of introduction of a second monomer component in thepolyolefin is avoided.

Description

technical field [0001] The invention relates to the technical field of high molecular polymers, in particular to a polyolefin and a preparation method thereof. Background technique [0002] Polyolefin is the largest variety among the three major synthetic materials. However, polyolefin products obtained by homopolymerization of olefins have their own defects. For example, the most prominent shortcomings of polypropylene are cold resistance, low temperature brittleness, poor weather resistance, insufficient rigidity, and poor dyeability. In order to overcome the deficiencies in certain properties of polyolefin products, improve the comprehensive performance of polyolefin products, and broaden its application fields, the concept of polyolefin alloying is proposed. Polyolefin alloys refer to polyolefin heterogeneous mixtures containing various olefin homopolymer or copolymer components. The reactor polyolefin alloy refers to the polyolefin heterogeneous copolymer produced by d...

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Problems solved by technology

[0003] Studies have shown that although polyolefin alloys have effectively improved the phase interface and two-phase dispersion problems between different polyolefin products in polyolefin alloys to a certain extent, thereby improving the performance of the products, due to the introduction of the second monomer, especially for For high-isotactic polyolefin alloy products, the differences in molecular chains of different polyolefins will lead to a significant decrease in one or some properties of the product, especially the significant decrease in heat resistance

For example, in the polymerization of 1-butene, the introduction of propylene as a polymerization monomer increases the modulus of polybutene-1 and improves the processing cycle, but the Vicat softening point of polybutene alloy products is significantly reduced due to the introduction of polypropylene , restricting the development and application of high isotactic polyolefin alloys

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