Patent EA-002321-B1 (EA)
Title: A polymer of ethylene, film and process therefor
Inventor: LUE CHING-TAI
IPC: C08F4/602
Filed: 1998-03-27
Abstract: 1. A polymer of ethylene and at least one alpha olefin having at least 5 carbon atoms, which polymer has a Melt index (MI) as herein defined of from 0.1 to 15 (as determined by ASTM D-1238-Condition E); a  Compositional Distribution Breadth index (CDBI) as defined herein of at least 70%, a density of from 0.910 to 0.930 g/ml (as determined by ASTM D-1505); a Haze value as herein defined of less than 20 % (as determined by ASTM D-1003-95); a Melt Index ration (MIR) as herein defined of from 35 to 80 (I21/I2 as determined by ASTM D-1238); an averaged Modulus (M) as herein defined of from 20,000 to 60,000 psi (pounds per square inch, 13790-41369 N/cm<2>) (as determined by ASTM D-882-91, sum of machine direction and transverse direction divided by two) and a relation between M and the Dart Impact Strength in g/25μm (g/mil) (DIS) complying with the formula:   DIS  2.The polymer according to claim 1 in which the relation between the averaged Modulus and the Dart Impact Strength (DIS) complies with the formula:   DIS  3. The polymer according any of the preceding claims in which the density is from 0.915 to 0.927 g/ml, the MI is from 0.3 to 10 and the CDBI is at least 75 %. 4. The polymer according any of the preceding claims in which the  DIS is from 120 tp 1000 g/25μm (g/mil). 5. The polymer according any of the preceding claims in which the levels of extractables as defined herein in less than 2.6 wt %. 6. A film comprising at least one layer of the polymer according to any of the preceding claims. 7. The film according to claim 6 in which the layer has a thickness of from 12.7 to 17.7 μm (0.5 to 7 mil) and is preferably a mono-layer. 8. A continuous gas phase process for the polymerization of a polymer according to any of the preceding claims 1 to 4, comprising: continuously circulating a feed gas stream containing monomer and inerts to thereby fluidize and agitate a bed of polymer particles, adding metallocene catalyst to the bed and removing said polymer particles of claims 1-4 in which: the catalyst comprises at least one bridged bis cyclopentadienyl transition metal and an alumoxane activator on a common or separate porous support; the feed gas is substantially devoid of a Lewis acidic scavenger and wherein the Lewis acidic scavenger is preferably present in an amount less than 100 ppm of the feed gas; the temperature in the bed is no more than 20 degree C less than the melting temperature of the polymer of claims 1-4, as determined by DSC, at an ethylene partial pressure in excess of 75 pounds per square inch absolute (517 kPaa) and wherein the removed polymer of claims 1-4 has an ash content of transition metal of less than 500 wt. ppm, and has substantially no detectable chain and unsaturation as determined by HNMR. 9. The process according to claim 8 in which the catalyst is substantially devoid of a metallocene having a pair of pi bonded ligands which are not connected through a covalent bridge. 10. The process according to claim 8 or 9 wherein there is used a substantially single metallocene species comprising a pair of pi bonded ligands at least one of which has a structure with at least two cyclic fused rings. 11. The process according to any of claims 8 to 10 wherein there is used a substantially single metallocene species comprising a mono-atom silicon bridge connecting two polynuclear ligands pi-bonded to the transition metal atom. 12. The process according to any of claims 8 to 10 wherein said removed polymer particles of claims 1-4 have a MI less than 10 a MIR of at least 40.