The production process
There are two main methods: high pressure tube method and kettle method. From the current development status, to reduce the reaction temperature and pressure, pipe widely used method of low temperature highly active agent polymerization system, with high purity ethylene as main raw materials, such as propylene/propane as the density adjusting agent, the use of highly active initiator at about 200 ℃ ~ 330 ℃, 150-300 mpa under the conditions of polymerization reaction. Polymerization reactor of molten polymers, have to pass high voltage, medium voltage and low pressure cooling, separation, high pressure recycle gas after cooling, separation into extra-high voltage (300 MPa) compressor inlet, medium circulation gas after cooling, separation into high-voltage (30 MPa) compressor inlet, after cooling, separation and low pressure circulation gas into the low pressure (0.5 MPa) compressor recycling, and the molten polyethylene after high pressure and low pressure separation into granulator, water cut, the granulation, the enterprise can according to different application domains, adding appropriate additive, granule with packing factory.
Can use injection molding, extrusion, blow molding and other processing methods. Mainly used as agricultural film, industrial packaging film, pharmaceutical and food packaging film, machinery parts, daily necessities, building materials, wire, cable insulation, coating and synthetic paper.
Fold edit this section LLDPE
As the molecular structure of LLDPE and LDPE is obviously different, the performance is also different. Compared with LDPE, LLDPE has excellent resistance to environmental stress cracking and electrical insulation, high heat resistance, impact resistance and puncture resistance.
LLDPE resin is mainly produced by full-density polyethylene equipment, and the typical production process is Innovene process and UCC Unipol process.
Through injection molding, blister, extrusion, blow molding and other molding methods, film production, daily necessities, pipe, cable, and so on.
The particle size should be 2mm~5mm in any direction. No mechanical impurity, thermoplastic. The powder is white powder. The qualified product is allowed to be slightly yellow. Room temperature does not dissolve in solvents, but in the fat hydrocarbon, aromatic hydrocarbon and halogenated hydrocarbon can long time contact with swelling, in more than 70 ℃ when slightly soluble in toluene, acetic acid. Heat is added to the air and oxidized under the influence of sunlight. It is resistant to the erosion of most acids and bases. Small water absorption, at low temperature can still maintain softness, high electrical insulation.
The two production processes are gas phase method and slurry method. The slurry annular pipe production process is represented by phillips, Basell and northern star annular process in northern Europe. The cauldron slurry law is represented by the CX process of mitsui company of Japan.
It adopts injection molding, suction molding, blow molding, extrusion molding, roll molding and other molding methods to produce film products, daily necessities and industrial hollow containers of various sizes, pipe, packaging calendering and ligation bands, thick film products, rope, fishing net and knitting fiber, wire and cable, etc.
[- ch2-ch2 -] n is a kind of thermoplastic resin made by polymerization of ethylene. In industry, too, the copolymers of ethylene with a small number of pene-olefin are included. Polyethylene odourless, non-toxic, feel like wax, has good low temperature resistance (the lowest temperature can reach 70 ~ 100 ℃), chemical stability is good, most of acid and alkali erosion (acid) with characteristics of oxidation resistance, temperature does not dissolve in solvents, small water imbibition, excellent electrical insulation properties; However, polyethylene is sensitive to environmental stresses (chemical and mechanical effects) and has poor thermal aging. The properties of polyethylene vary from species to species, mainly depending on molecular structure and density. Products of different densities (0.91~0.96g/cm3) can be obtained by different production methods. Polyethylene can be processed by general thermoplastic molding (see plastic processing). Widely used, mainly used for making thin film, container, pipe, single wire, wire and cable, daily necessities, and can be used as TV, radar and other high-frequency insulation materials. With the development of petrochemical industry, the production of polyethylene has developed rapidly, accounting for about 1/4 of the total plastic output. In 1983, the total production capacity of polyethylene in the world was 24.65Mt, and the installed capacity under construction was 3.16Mt.