Preparation method of doublet or wide molecular weight distribution polyvinyl

Abstract

The invention relates to a preparation method of doublet or wide molecular weight distribution polyvinyl. In polymerization, ethylene is used as monomer, butene-1 or hexene-1 as comonomer and hydrogen as molecular weight modifier. Polymerization temperature is 70 DEG C to 110 DEG C, pressure is 0.7 MPa to 2.5 MPa, reaction time is 2 h to 4 h, and catalyst is vanadium catalyst with the structural formula of VMg.nAl, wherein the range of n is 0.1 to 10. Promoter is the mixture of one or two of triisobutyl aluminium and aluminium ethyl, and the molar ratio of aluminum of the promoter and vanadium of the main catalyst is 10 to 10000: 1. The molecular weight and the molecular weight distribution wide of polyethylene products are adjusted through the adjustment of the types and the dosage of the promoter. Polymerized products have the characteristics of high molecular weight and wide molecular weight distribution, and the morphology of the polymerized products is regular spheroidal particles, and has no fine powder and no oligomer. The production of high value-added doublet or wide molecular weight distribution polyvinyl products can be achieved in a single reactor of a slurry process and a gas phase method technology.

Description

technical field [0001] The invention relates to a bimodal or wide molecular weight distribution polyethylene and a preparation method thereof. Background technique [0002] The molecular weight and molecular weight distribution of polyethylene have an important influence on the rheological properties of its melt and the mechanical properties of the product. In many applications (such as polyethylene pressure-resistant pipes), high molecular weight polyethylene is required to provide good mechanical properties. At the same time, it needs to have a wide molecular weight distribution in order to have good processability. Therefore, in recent years, people have been keen on the synthesis research of high molecular weight bimodal or wide molecular weight distribution polyethylene. [0003] Existing preparation method of bimodal or wide molecular weight distribution polyethylene resin has following three kinds: (1) two kinds of polymers are blended, and this method is not only co...

AI Technical Summary

Problems solved by technology

[0003] Existing preparation method of bimodal or wide molecular weight distribution polyethylene resin has following three kinds: (1) two kinds of polymers are blended, and this method is not only cost high, and is difficult to reach the blending of resin completely evenly, influences product quality; Performance; (2) By staged polymerization in a graded reactor, uniform mixing in the reactor can be achieved, and the operation adjustment flexibility is large, but the production efficiency is low and the production cost is high; (3) Bimetallic or multimetallic in a single reactor Active component catalysts use their different polymerization behaviors to directly produce polyethylene products with a wide molecular weight distribution in a single reactor. In theory, this method is the most desirable, but in practice it is necessary to integrate multiple polymerization behaviors. more difficult