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[Chemical Knowledge]：Production and manufacturing methods and processes of PE

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Polyethylene (PE) is a widely used chemical production raw material, mainly used in the manufacture of plastic bags, pipes, containers and other plastic products. The following is the manufacturing method of PE:

1. high pressure method

high pressure method is the main method of producing low density polyethylene (LDPE), the production process is carried out under high temperature and high pressure conditions. The specific steps are as follows:

1. preparation of catalyst: the catalyst, cocatalyst and other additives are mixed according to a certain proportion to prepare a catalyst system.
2. Polymerization: The catalyst system is added into a high-pressure polymerization kettle, ethylene gas is introduced, and the polymerization reaction is carried out under high pressure and high temperature conditions to generate polyethylene.
3. Separation and drying: The polymerization product is taken out from the polymerization kettle, and the low-density polyethylene product is obtained through separation, drying and other processes.
LDPE produced
high-pressure method has the characteristics of low molecular weight, many branches and small density, and is mainly used in the manufacture of films and packaging bags.

2. low-pressure method

low-pressure method is the main method for producing high-density polyethylene (HDPE), and its production process is carried out under lower pressure and temperature. The specific steps are as follows:

1. Preparation of catalyst: The catalyst, cocatalyst and other additives are mixed in a certain proportion to prepare a catalyst system.
2. Polymerization: The catalyst system is added to a low-pressure polymerization kettle, ethylene gas is introduced, and the polymerization reaction is carried out at a lower pressure and temperature to produce polyethylene.
3. Separation and drying: The polymerization product is taken out from the polymerization kettle, and is subjected to separation, drying and other processes to obtain a high-density polyethylene product.
HDPE produced
low pressure method has the characteristics of high molecular weight, less branched chain and high density, which is mainly used in the manufacture of pipes, containers and so on.

3. copolymerization

copolymerization is a method of introducing other olefin monomers into the polyethylene production process and copolymerizing with ethylene to produce copolymers. By changing the type and proportion of comonomers, polyethylene products with different properties and uses can be produced. The specific steps are as follows:

1. Preparation of catalyst: The catalyst, cocatalyst and other additives are mixed in a certain proportion to prepare a catalyst system.
2. Copolymerization: The catalyst system is added to a polymerization kettle, ethylene and comonomer gas are introduced, and the copolymerization reaction is carried out under appropriate pressure and temperature to produce a copolymer.
3. Separation and drying: The copolymerization product is taken out from the polymerization kettle and subjected to separation, drying and other processes to obtain the copolymerization polyethylene product.

copolymerization can produce polyethylene products with special properties and uses, such as low temperature resistance, impact resistance, flame retardant, etc.

In short, the manufacturing methods of PE mainly include high pressure method, low pressure method and copolymerization method. PE products produced by different methods have different properties and uses. In the production process, factors such as reaction conditions, catalyst system and raw material quality need to be strictly controlled to ensure product quality and production efficiency.

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