ETHYLENE AND ALPHA-OLEFIN COPOLYMERS AND POLYMERISATION METHODS FOR OBTAINING SAID COPOLYMERS Russian patent published in 2011 - IPC C08F210/16 C08F2/34 C08L23/08 

FIELD: chemistry.

SUBSTANCE: described is a method of obtaining an ethylene and alpha-olefin copolymer, where the method involves: bringing ethylene and at least one alpha-olefin into contact with a metallocene catalyst in at least one gas-phase reactor with pressure in the reactor ranging from 0.7 to 70 bars and at temperature in the reactor ranging from 20°C to 150°C, to obtain an ethylene and alpha-olefin copolymer during polymerisation, where the ethylene and alpha-olefin copolymer satisfies the following conditions: density equal to or greater than 0.927 g/cm³, melt flow index (I₂) from 1 dg/min to 200 dg/min, (I₂₁/I₂) ratio from 15 to 40, molecular weight distribution M_w/M_n 2-4, ESCR of 500 hours or more if measurement is carried out in accordance with ASTM 1693/B in 10% Igepal solution, T₇₅-T₂₅ equal to or greater than 4, where T₂₅ is temperature at which 25% eluted polymer is obtained, and T₇₅ is temperature at which 75% eluted polymer is obtained, in an experiment with temperature rising elution fractionation (TREF) and F₈₀ equal to or greater than 10%, where F₈₀ is a polymer fraction which elutes below 80°C, where the metallocene catalyst is selected from a group consisting of: bis(n-propylcyclopentadienyl)hafnium X_n, bis(n-butylcyclopentadienyl)hafnium X_n, bis(n-pentylcyclopentadienyl)hafnium X_n, (n-propylcyclopentadienyl)(n-butylcyclopentadienyl)hafnium X_n, bis[(2-trimethylsilylethyl)cyclopentadienyl]hafnium X_n, bis(trimethylsilylcyclopentadienyl)hafnium X_n, dimethylsilylbis (n-propylcyclopentadienyl)hafnium X_n, dimethylsilylbis(n-butylcyclopentadienyl)hafnium X_n, bis(1-n-propyl-2-methylcyclopentadienyl)hafnium X_n, (n-propylcyclopentadienyl)(1-n-propyl-3-n-butylcyclopentadienyl)hafnium X_n; and where X_n is selected from a group consisting of halogen ions, hydrides, C_1-12 alkyls, C_2-12 alkenyls, C_6-12 aryls, C_7-20 alkylaryls, C_1-12 alkoxy groups, C_6-16 aryloxy groups, C_7-18 alkylaryloxy groups, C_1-12 fluoroalkyls, C_6-12 fluoroaryls, and C_1-12 heteroatom-containing hydrocarbons and substituted derivatives thereof. Described also is an ethylene and alpha-olefin copolymer, a composition containing said copolymer and an article obtained via rotational moulding, containing said composition.

EFFECT: obtaining an ethylene and alpha-olefin copolymer, having wide orthogonal distribution and high resistance to environmental stress cracking.

11 cl, 7 dwg, 4 tbl