Bis phenolate transition metal complexes are disclosed for use in alkene polymerization, with optional chain transfer agent, to produce polyolefins.

Bis phenolate transition metal complexes are disclosed for use in alkene polymerization, with optional chain transfer agent, to produce polyolefins.

The present invention relates to a process for continuously producing an ultra-high molecular weight polyethylene by the ethylene slurry polymerization, wherein raw materials containing ethylene and optionally at least one comonomer are subjected to a continuous slurry polymerization in a hydrogen free atmosphere in the ethylene slurry polymerization condition by using 2-6 ethylene slurry polymerization reaction tanks connected in series, and the deviations of the polymerization temperatures, the polymerization pressures, and the gas phase compositions between the tanks each other are controlled to certain ranges. The ultra-high molecular weight polyethylene having the viscosity-average molecular weight of 150-800?10.sup.4 g/mol can be continuously produced. This process has flexible polymerization manner, large room for adjusting and controlling, and stable polymer performance. Moreover, the obtained ultra-high molecular weight polyethylene has low metal content, low ash content, and excellent mechanical properties.

The present invention relates to a process for continuously producing an ultra-high molecular weight polyethylene by the ethylene slurry polymerization, wherein raw materials containing ethylene and optionally at least one comonomer are subjected to a continuous slurry polymerization in a hydrogen free atmosphere in the ethylene slurry polymerization condition by using 2-6 ethylene slurry polymerization reaction tanks connected in series, and the deviations of the polymerization temperatures, the polymerization pressures, and the gas phase compositions between the tanks each other are controlled to certain ranges. The ultra-high molecular weight polyethylene having the viscosity-average molecular weight of 150-800?10.sup.4 g/mol can be continuously produced. This process has flexible polymerization manner, large room for adjusting and controlling, and stable polymer performance. Moreover, the obtained ultra-high molecular weight polyethylene has low metal content, low ash content, and excellent mechanical properties.

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.