A method for continuous production of polyethylene wax by thermal cracking in an externally rotating self-stirring reactor

Abstract

The invention discloses a method for preparing polyethylene wax through an external rotation self-stirring reaction kettle by a thermal cracking method, and belongs to the field of a high molecular material. According to the method, pretreated waste PE (polyethylene) is fed into a feeding opening by a fully automatic feeder, and is uniformly fed into an external rotation self-stirring centrifugal mass transfer reaction kettle together with a catalyst Al-MCM-48; the temperature is raised to cracking temperature; polyethylene wax with uniform molecular weight is generated through a self-stirring device in the reaction kettle; the polyethylene wax enters a discharging opening through a separator arranged in the reaction kettle; the PE which is not completely reacted is separated by the separator and continuously takes a reaction in the reaction kettle; a small number of low-boiling-point substances generated in the reaction process are subjected to temperature reduction recovery through a low-boiling-point substance condensation recovery system; the polyethylene wax flowing out from the discharging opening enters a material distributor through a continuous discharging filtering system; after the cooling, spherical or flaky polyethylene wax is obtained. The method has the advantages that the heat conduction speed is high; the cracking period is short; the heat utilization rate is high; the energy consumption is low; no smoke gas and no odor are generated in the cracking reaction process; environment pollution is avoided; the safety is high.

Description

technical field [0001] The invention relates to a method for preparing polyethylene wax by catalytic cracking of polyethylene waste plastics, in particular to a new method for continuously producing polyethylene wax by thermal cracking of an externally rotating self-stirring reactor, which belongs to the field of polymer materials. technical background [0002] Polyethylene wax is a polyolefin synthetic wax. Its appearance is white or light yellow block, flake or powder solid. The relative molecular mass is 1000-4000. It has low toxicity, non-corrosiveness, high hardness and high softening point. , low melt viscosity, wear resistance, heat resistance, good lubricity, dispersion and fluidity, etc., can effectively improve the processing efficiency of PVC pipes, profiled materials, films, cables and other plastics and rubbers, and have broad prospects for development and utilization. At present, the production of polyethylene wax is mainly obtained through three methods: ethyl...

AI Technical Summary

Problems solved by technology

[0004] In the traditional production of polyethylene wax, reactor heating cracking process and extrusion cracking process are usually used. This process has the following disadvantages: (1) Due to the fact that the raw material is mechanically stirred during the cracking reaction and the torque of the screw extrusion is very large , not only requires a lot of energy consumption, but also causes the stirring device or extrusion device to be easily damaged. The output of 100kg / h requires a motor of more than 50kW to drive

(2) The heating device is around the pipe wall, so the heat utilization rate is low and the loss is large

(3) Reactor pyrolysis process is intermittent and cannot be produced continuously

(4) The extrusion cracking process has strict requirements on the geometric shape of the raw materials, which must be broken evenly before they can be used, and the cost of each ton of raw materials needs to be increased by 200 yuan

And energy consumption is big, output is low, (5) safety is poor, wax production rate is low, the rate of wax formation is below 85%, labor intensity of workers is high, environmental protection is poor etc.

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