Divided into high-pressure ( by high pressure process from ethylene synthesis, Gaosuibuyou Thailand poly bags the synthesis pressure is 100 ~ 300MPa, the temperature of 150 ~ 275, 0.05% ~ 0.1% oxygen or peroxidase as catalyst; synthesis or in the mixing tank for intermittent occurrence, or in a tubular reactor in continuous ), low pressure, middle pressure method three.
High pressure method used in the production of low density polyethylene, this method development early, the polyethylene production has accounted for about 2 of total production of polyethylene / 3, but with the production technology and development of catalysts, its growth rate has significantly lagged behind the low voltage method. Low pressure method. Its implementation method, a slurry method, solution method and gas chromatography.
Slurry method is mainly used for the production of high density polyethylene, and the solution method and gas phase method not only can produce high density polyethylene, but also through the addition of comonomer, production, low density polyethylene polyethylene ethylene, also known as linear low density polyethylene. In recent years, a variety of low-voltage technology develops very fast. MV only Philip is still in use, the main production is high density polyethylene.
Polyethylene characteristics
Polyethylene odorless, non-toxic, feel like wax, has excellent low temperature properties ( lowest service temperature up to - 70 to - 100 degrees C), good chemical stability, resistance to most acid-base corrosion ( intolerance with oxidation properties of acid ), room temperature, soluble in common solvents, water absorption of small, but because of the linear molecule can be slowly soluble in some organic solvents, and no swelling, electric insulation performance; but the polyethylene for environmental stress ( chemical and mechanical action ) is very sensitive, heat aging resistance difference.
Polyethylene properties varied with varieties, mainly depends on the molecular structure and density.
( 1) LDPE: low density polyethylene, high density polyethylene
( 2) LLDPE: linear low density polyethylene
( 3) MDPE: medium density polyethylene resin, Shuangfeng
( 4) HDPE: high density polyethylene, low pressure polyethylene
( 5) UHMWPE: ultra high molecular weight polyethylene
( 6): CPE modified polyethylene,plastic bags supplier cross-linked polyethylene ( PEX )
( 7): ethylene copolymer of ethylene propylene copolymer ( plastic ), EVA, copolymer, ethylene - other olefin ( such as POE, octene copolymer of cyclic olefin ), ethylene unsaturated ester copolymer ( EAA, EMAA, EEA, EMA, EMMA, EMAH )
The molecular weight of 3000000-6000000 linear polyethylene called ultra high molecular weight polyethylene ( UHMWPE ). Ultra high molecular weight polyethylene intensity is very high, can be used to make the body armor.
Main methods: Polyethylene liquid chromatography (also divided into solution and slurry method ) and gas phase method ( material in the reactor of phase type ). Our country mainly used Ziegler catalyst slurry method.
Conditions and process description: more than 99% purity ethylene in catalyst of titanium tetrachloride and two ethyl aluminum chloride in the presence of pressure and temperature, in 0.1-0.5MPa 65-75 C HDPE slurry polymerization in gasoline. The alcoholysis destroys residual catalyst,solar module cell neutralization, washing, and recovery of gasoline and unpolymerized vinyl, after drying, granulation product.
