The present invention relates to an ultra-high molecular weight polyethylene and a process for preparing the same, said ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 150-1000?10.sup.4 g/mol, a metal element content of 0-50 ppm, a bulk density of 0.30-0.55 g/cm.sup.3, a true density of 0.900-0.940 g/cm.sup.3, a melting point of 140-152? C., and a crystallinity of 40-75%, and said polyethylene satisfies at least one of condition (1) and condition (2): Condition (1): tensile elasticity modulus is greater than 250 MPa, preferably greater than 280 MPa, more preferably greater than 300 MPa, Condition (2): Young's modulus is greater than 300 MPa, preferably greater than 350 MPa.

The ultra-high molecular weight polyethylene has high mechanical properties, high melting point, low metal element content and ash content, and the preparation process is simple, flexible and adjustable, and the ultra-high molecular weight ethylene copolymer has a high tensile elasticity module.

The present invention relates to an ultra-high molecular weight polyethylene and a process for preparing the same, said ultra-high molecular weight polyethylene has a viscosity-average molecular weight of 150-1000?10.sup.4 g/mol, a metal element content of 0-50 ppm, a bulk density of 0.30-0.55 g/cm.sup.3, a true density of 0.900-0.940 g/cm.sup.3, a melting point of 140-152? C., and a crystallinity of 40-75%, and said polyethylene satisfies at least one of condition (1) and condition (2): Condition (1): tensile elasticity modulus is greater than 250 MPa, preferably greater than 280 MPa, more preferably greater than 300 MPa, Condition (2): Young's modulus is greater than 300 MPa, preferably greater than 350 MPa.

The ultra-high molecular weight polyethylene has high mechanical properties, high melting point, low metal element content and ash content, and the preparation process is simple, flexible and adjustable, and the ultra-high molecular weight ethylene copolymer has a high tensile elasticity module.

The present invention relates to an ethylene polymer and a process for preparing the same, wherein the ethylene polymer has an average particle size of 50-3000 ?m, a bulk density of 0.28-0.55 g/cm.sup.3, a true density of 0.930-0.980 g/cm.sup.3, a melt index at a load of 2.16 Kg at 190? C. of 0.01-2500 g/10 min, a crystallinity of 30-90%, a melting point of 105-147? C., a comonomer molar insertion rate of 0.01-5 mol %, a weight-average molecular weight of 2?10.sup.4 g/mol-40?10.sup.4 g/mol, and a molecular weight distribution of 1.8-10. In the preparation process, raw materials containing ethylene, hydrogen gas and a comonomer are subjected to a tank-type slurry polymerization with an alkane solvent having a boiling point of 5-55? C. or a mixed alkane solvent having a saturated vapor pressure of 20-150 KPa at 20? C. as the polymerization solvent in the presence of a polyethylene catalytic system, at the molar ratio of hydrogen gas to ethylene of 0.01-20:1, preferably 0.015-10:1, at the molar ratio of hydrogen gas to the comonomer of 0.1-30:1, preferably 0.15-25:1 to prepare the ethylene polymer.

The present invention relates to an ethylene polymer and a process for preparing the same, wherein the ethylene polymer has an average particle size of 50-3000 ?m, a bulk density of 0.28-0.55 g/cm.sup.3, a true density of 0.930-0.980 g/cm.sup.3, a melt index at a load of 2.16 Kg at 190? C. of 0.01-2500 g/10 min, a crystallinity of 30-90%, a melting point of 105-147? C., a comonomer molar insertion rate of 0.01-5 mol %, a weight-average molecular weight of 2?10.sup.4 g/mol-40?10.sup.4 g/mol, and a molecular weight distribution of 1.8-10. In the preparation process, raw materials containing ethylene, hydrogen gas and a comonomer are subjected to a tank-type slurry polymerization with an alkane solvent having a boiling point of 5-55? C. or a mixed alkane solvent having a saturated vapor pressure of 20-150 KPa at 20? C. as the polymerization solvent in the presence of a polyethylene catalytic system, at the molar ratio of hydrogen gas to ethylene of 0.01-20:1, preferably 0.015-10:1, at the molar ratio of hydrogen gas to the comonomer of 0.1-30:1, preferably 0.15-25:1 to prepare the ethylene polymer.