EPM plastic is a block copolymer obtained by polymerizing ethylene and propylene under Ziegler-Natta catalyst. Its chemical structure is equivalent to polyethylene with several methyl branches on the main chain of the macromolecule, with high crystallinity, and has the characteristics of high-density polyethylene and polypropylene.

Basic Overview

EPM plastic is made by intermittent or continuous slurry polymerization of ethylene and propylene under Ziegler-Natta catalyst. Its chemical structure is equivalent to polyethylene with several methyl branches on the main chain of the macromolecule, with high crystallinity. It has the characteristics of high-density polyethylene and polypropylene. Compared with high-density polyethylene, it has higher heat resistance, excellent stress cracking resistance, higher surface hardness, lower shrinkage during molding, greater shape stability, and better low temperature resistance and impact resistance than polypropylene.

Composition

EPM plastic is a block copolymer obtained by polymerizing ethylene and propylene under Ziegler-Natta catalyst. The chemical structure is equivalent to polyethylene with several methyl branches on the main chain of the macromolecule. It has high crystallinity and the characteristics of high-density polyethylene and polypropylene. Compared with high-density polyethylene, it has a higher heat resistance temperature. It has excellent resistance to stress cracking, high surface hardness, low shrinkage during molding, and good dimensional stability. It is mainly used for blow molding, molding and extrusion products, and can be used for bottles, containers, wires and cables. The ring can be used as a film.

Batch production and continuous production

The raw material propylene is first slurry polymerized in the presence of TiCl+EtAlCl, TiCl+AlCl+EtAlCl or TiCl+EtAlCl+EtAl catalysts at 50-90буC, normal pressure to more than ten atmospheres, in the presence of an inert solvent (such as heptane) and hydrogen to obtain a prepolymer-propylene homopolymer. Then, in the same reactor, unreacted propylene is driven out with N, and then TiCl+EtAlCl catalyst is added or no catalyst is added, and ethylene or ethylene-propylene mixed gas is introduced to continue slurry polymerization to obtain ethylene-propylene copolymer containing a certain polyethylene segment on the polypropylene straight chain.

Using TiCl+EtAlCl as catalyst, a polymerization process with two or more reactors in series is used to continuously polymerize ethylene-propylene copolymer. Propylene and catalyst are first added to the first reactor for polymerization, and the obtained polypropylene slurry is pumped into the second reactor together with the solvent for flash evaporation to discharge unreacted propylene, and then ethylene or ethylene-propylene mixed gas is introduced to continue polymerization. The obtained copolymer can be pumped into the next reactor by pump, and ethylene is continued to be introduced for block copolymerization to finally obtain the desired copolymer.

Use

Industrialization began in 1962 by Eastman Company in the United States. Shanghai Gaoqiao Chemical Plant and Shanghai Synthetic Resin Institute carried out small-scale trials in 1969. Beijing Institute of Chemical Industry is also conducting trial production. Compared with high-density polyethylene, it has higher heat resistance, excellent stress cracking resistance, higher surface hardness, lower shrinkage during molding, and better dimensional stability. Compared with polypropylene, it has excellent low temperature resistance and good impact resistance. It is mainly used for blow molding, molding and extrusion products. It can be used in bottles, containers, wires and cables, and can also be used as films.

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