Ethylene copolymers and their use for the manufacture of films

Claim 2

A copolymer of ethylene containing from 94.5 to 99.5 weight % of ethylene units and from 0.5 to 5.5 weight % of 1-olefin units of the formula R--CH═CH 2 ,in which R is an alkyl radical having from 1 to 6 carbon atoms, said copolymer having a density of from 0.935 to 0.945 g/cm 3 , a melt index MFI 190/5 of from 0.05 to 0.2 g/10 min., a melt index ratio ##EQU1## a shear viscosity of from 4 . 10 5 to 4 . 10 6 Pa . s, at 200° C. and at a shear stress of 10 2 N/m 2 , a shear viscosity of from 6 . 10 3 to 1 . 10 5 Pa . s at 200° C. and at a shear stress of 10 5 N/m 2 , a tear strength above 25 N/mm 2 , an elongation at break above 600%, a tear initiation resistance above 150 N/mm, a tear propagation resistance above 100 N/mm, and an impact strength above 2500 mJ/mm 2 .

Claim 3

An ethylene copolymer film consisting essentially of an ethylene copolymer containing from 94.5 to 99.5 weight % of ethylene units and from 0.5 to 5.5 weight % of 1-olein units of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, said copolymer having a density of from 0.935 to 0.945 g/cm 3 , a melt index MFI 190/5 of from 0.05 to 0.2 g/10 min, a melt index ratio ##EQU2## a shear viscosity of from 4 . 10 5 to 4 . 10 6 Pa . s, at 200° C. and at a shear stress of 10 2 N/m 2 , a shear viscosity of from 6 . 10 3 to 1 . 10 5 Pa . s at 200° C. and at a shear stress of 10 5 N/m 2 , a thickness of from 0.05 to 0.25 mm, a tear strength in longitudinal and transverse direction above 25 N/mm 2 , an elongation at break above 600%, a tear initiation resistance above 150 N/mm, a tear propagation resistance above 100 N/mm, and an impact strength above 2500 mJ/mm 2 .

Claim 4

An ethylene copolymer film consisting essentially of an ethylene copolymer containing from 94.5 to 99.5 weight % of ethylene units and from 0.5 to 5.5 weight % of 1-olein units of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, said copolymer having a density of from 0.935 to 0.945 g/cm 3 , a melt index MFI 190/5 of from 0.05 to 0.2 g/10 min, a melt index ratio ##EQU2## a shear viscosity of from 4 . 10 5 to 4 . 10 6 Pa . s, at 200° C. and at a shear stress of 10 2 N/m 2 , a shear viscosity of from 6 . 10 3 to 1 . 10 5 Pa . s at 200° C. and at a shear stress of 10 5 N/m 2 , a thickness of from 0.05 to 0.25 mm, a tear strength in longitudinal and transverse direction above 25 N/mm 2 , an elongation at break above 600%, a tear initiation resistance above 150 N/mm, a tear propagation resistance above 100 N/mm, and an impact strength above 2500 mJ/mm 2 .

Claim 5

A process for the preparation of an ethylene copolymer containing from 94.5 to 99.5 weight % of ethylene units and from 0.5 to 5.5 weight % of 1-olefin units of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, said copolymer having a density of from 0.935 to 0.945 g/cm 3 , a melt index MFI 190/5 of from 0.05 to 0.2 g/10 min, a melt index ratio ##EQU3## and a shear viscosity of from 6 . 10 3 to 1 . 10 5 Pa . s at 200° C. and at a shear stress of 10 5 N/m 2 , and a shear viscosity of from 4 . 10 5 to 4 . 10 6 Pa . s at 200° C. and at a shear stress of 10 2 N/m 2 said process comprising copolymerizing in two steps ethylene and a 1-olefin of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, in suspension or in gaseous phase, at a temperature of from 20° to 150° C., under a pressure of from 0.5 to 50 bars, in the presence of a mixed catalyst consisting of a titanium-containing compound and an organo-aluminum compound, adjusting the molecular weight of the copolymer by means of hydrogen, maintaining the hydrogen concentration in the first step at a value to produce from 45 to 70 weight % of a high molecular weight copolymer having a RSV of from 5 to 15 dl/g and maintaining the hydrogen concentration in the second step at a value to produce from 30 to 55 weight % of a low molecular weight copolymer having a RSV of from 0.5 to 3 dl/g.

Claim 6

A process for the preparation of an ethylene copolymer containing from 94.5 to 99.5 weight % of ethylene units and from 0.5 to 5.5 weight % of 1-olefin units of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, said copolymer having a density of from 0.935 to 0.945 g/cm 3 , a melt index MFI 190/5 of from 0.05 to 0.2 g/10 min, a melt index ratio ##EQU3## and a shear viscosity of from 6 . 10 3 to 1 . 10 5 Pa . s at 200° C. and at a shear stress of 10 5 N/m 2 , and a shear viscosity of from 4 . 10 5 to 4 . 10 6 Pa . s at 200° C. and at a shear stress of 10 2 N/m 2 said process comprising copolymerizing in two steps ethylene and a 1-olefin of the formula R--CH═CH 2 , in which R is an alkyl radical having from 1 to 6 carbon atoms, in suspension or in gaseous phase, at a temperature of from 20° to 150° C., under a pressure of from 0.5 to 50 bars, in the presence of a mixed catalyst consisting of a titanium-containing compound and an organo-aluminum compound, adjusting the molecular weight of the copolymer by means of hydrogen, maintaining the hydrogen concentration in the first step at a value to produce from 45 to 70 weight % of a high molecular weight copolymer having a RSV of from 5 to 15 dl/g and maintaining the hydrogen concentration in the second step at a value to produce from 30 to 55 weight % of a low molecular weight copolymer having a RSV of from 0.5 to 3 dl/g.