Preparation method of polypropylene

A polypropylene and propylene technology, applied in the field of olefin polymerization, can solve the problems of limited rubber phase content, easy breakage of catalyst particles, attenuation of catalyst activity, etc., so as to reduce the problem of block and wall sticking, reduce local overheating, and improve catalyst performance. active effect
CN112625155AActive Publication Date: 2021-04-09PETROCHINA CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
PETROCHINA CO LTD
Publication Date
2021-04-09

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Abstract

The invention relates to a preparation method of polypropylene. The method comprises the following steps: cooling first liquid-phase propylene, mixing the cooled first liquid-phase propylene with a polypropylene catalyst, and carrying out low-temperature prepolymerization reaction, feeding an obtained slurry containing the low-molecular-weight polypropylene prepolymer into a double-loop reactor, carrying out liquid-phase bulk slurry polymerization on the slurry and supplemented second liquid-phase propylene, hydrogen and ethylene monomers, and feeding part or all of polypropylene slurry flowing out of the first loop reactor into a second loop reactor, carrying out directflash evaporation on the polypropylene slurry flowing out of the second loop reactor to remove non-condensable gas and most of propylene monomers, and carrying out purification and granulationan obtained polypropylene intermediate to obtain the product; or carrying out copolymerization reaction on the polypropylene intermediate, and then carrying out powder purification and granulation to obtain the product. According to the preparation method disclosed by the invention, high-melt-index / high-rigidity and high-rubber-content impact-resistant co-polypropylene can be produced through flexible switching of devices, and meanwhile, high-isotacticity homo-polypropylene and random co-polypropylene can also be produced.
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Description

technical field

[0001] The invention belongs to the field of olefin polymerization in petrochemical industry, and in particular relates to a preparation method of polypropylene obtained by multi-stage polymerization of propylene. Background technique

[0002] Polypropylene has excellent comprehensive properties, rich sources of raw materials, easy processing and application, and has become one of the main forces in the plastics industry. With the continuous increase of polypropylene production, the polypropylene market competition is becoming increasingly fierce. How to use a set of equipment to produce more grades of polypropylene products with higher performance is a problem that major manufacturers are currently studying and solving.

[0003] The current industrialized polypropylene production process in the world basically adopts liquid-phase bulk method, gas-phase method or a combination of the two processes, and different process technologies use different types of rea...

Claims

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