Polyethylene is a thermoplastic resin made by polymerizing ethylene. In industry, it also includes copolymers of ethylene and a small amount of α-olefin. Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (the minimum use temperature can reach -100~-70°C), has good chemical stability, and can withstand most acids and alkalis (not resistant to oxidation) Nature of acid). It is insoluble in general solvents at room temperature, has low water absorption and excellent electrical insulation.
Properties: tasteless, odorless, non-toxic, matt surface, milky white waxy particles, density about 0.920 g/cm3, melting point 130℃～145℃. Insoluble in water, slightly soluble in hydrocarbons, toluene, etc. It can withstand the erosion of most acids and alkalis, has low water absorption, maintains flexibility at low temperatures, and has high electrical insulation.
Production process: There are two main types: high-pressure tube method and kettle method. In order to reduce the reaction temperature and pressure, the tubular process generally uses low-temperature and high-activity primers to initiate the polymerization system, using high-purity ethylene as the main raw material, propylene/propane, etc. as density regulators, and using high-activity initiators at about 200℃～ The polymerization reaction is carried out at 330°C and 150-300MPa. The molten polymer that initiates polymerization in the reactor must be cooled and separated by high pressure, medium pressure and low pressure. The high pressure circulating gas is cooled and separated and then sent to the inlet of the ultra-high pressure (300 MPa) compressor. The medium pressure circulating gas is cooled and separated. After separation, it is sent to the inlet of the high-pressure (30 MPa) compressor, and the low-pressure circulating gas is cooled and separated and then sent to the low-pressure (0.5 MPa) compressor for recycling. The molten polyethylene is sent to the pelletizer after high-pressure and low-pressure separation. During the granulation process, the company can add suitable additives according to different application fields, and the granules are packaged and shipped.
Uses: Injection molding, extrusion molding, blow molding and other processing methods can be used. Mainly used as agricultural film, industrial packaging film, pharmaceutical and food packaging film, machinery parts, daily necessities, building materials, wire, cable insulation, coating, synthetic paper, etc.
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