Synthesis method of polyethylene

Abstract

The invention provides a synthesis method of polyethylene. The method comprises the following steps: in a series polymerization reaction system composed of a slurry polymerization reactor and a gas-phase polymerization reactor, directly introducing slurry discharged from the slurry polymerization reactor into the gas-phase polymerization reactor, subjecting a material discharged from the gas-phasepolymerization reactor to degassing and exhaust gas recovery, enabling a recovery liquid to enter a solvent separation tower, returning the separated material flow mainly containing saturated inert components to the slurry polymerization reactor, and returning the rest material flow to the gas-phase polymerization reactor. The method has the advantages of simple process, low energy consumption, low material consumption and the like, and can flexibly regulate and control the composition in the two reactors and the molecular weight distribution and branched chain distribution of the polyolefinproduct.

Description

technical field [0001] The invention relates to the field of olefin polymerization, in particular to a method for synthesizing polyethylene. Background technique [0002] Polyethylene is polymerized from ethylene, which not only has high electrical insulation, but also performs well in corrosion resistance and cold resistance. Among them, bimodal polyethylene products with excellent mechanical properties and processing properties have attracted widespread attention from users, but the current bimodal polyethylene market is still in the stage of "structural shortage" and has a good development prospect. [0003] The relative molecular mass and crystallinity of a polymer affect its rigidity and toughness. As the relative molecular weight of the polymer increases, its crystallinity will decrease, its rigidity will decrease, and its processing performance will decrease, but its toughness will increase and its long-term mechanical properties will increase. The emergence of bimo...

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Problems solved by technology

Although this method can produce polyethylene products stably and continuously, the post-treatment process of the first reactor is complicated and cannot produce high-quality bimodal polyethylene

Chinese patent CN1325528C provides a method of manufacturing bimodal linear low density polyethylene material, first in the first reactor by copolymerization of ethylene and α-olefin comonomer to produce low molecular weight polymer, and then in the second Continue to react in the reactor to produce high-molecular-weight polymers. Although the produced polymer products have achieved a better molecular weight distribution; but this method has problems such as high requirements for the catalyst carrier, complicated reaction process, and high cost.

Non-in-situ prepared self-reinforced composite materials, especially all-polyethylene composites, generally have problems such as complicated processing technology, special modification of processing equipment, long processing and production cycle, difficult processing and low content of reinforcing components.

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