초록 ▼

Metallocene catalyzed polyethylenes are found to have improved physical properties, improved processability and improved balance of properties. Surprisingly, there is a direct relationship between MD shrinkage, and MD tear. Additionally, MD tear is greater than TD tear, and MD tear is also greater t

Metallocene catalyzed polyethylenes are found to have improved physical properties, improved processability and improved balance of properties. Surprisingly, there is a direct relationship between MD shrinkage, and MD tear. Additionally, MD tear is greater than TD tear, and MD tear is also greater than intrinsic tear. MD tear to TD tear ratios are above 0.9, and dart drop impact is above 500 g/mil. The polyethylenes have a relatively broad composition distribution and relatively broad molecular weight distribution.

대표청구항 ▼

1. A film comprising a LLDPE, wherein LLDPE is produced in a gas phase process utilizing a hafnium transition metal metallocene-type catalyst system; wherein the film has a ratio of MD tear to TD tear, both determined by ASTM D-1922, of ?0.9; wherein the MD tear of the film increases with increasing

1. A film comprising a LLDPE, wherein LLDPE is produced in a gas phase process utilizing a hafnium transition metal metallocene-type catalyst system; wherein the film has a ratio of MD tear to TD tear, both determined by ASTM D-1922, of ?0.9; wherein the MD tear of the film increases with increasing MD shrinkage.2. The film of claim 1, wherein the film properties are attainable at ?10 pounds of polymer composition output per hour per inch of die circumference.3. The film of claim 1, wherein the film properties are attainable at ?12 pounds of polymer composition output per hour per inch of die circumference.4. The film of claim 1, wherein said ratio is ?1.0.5. The film of claim 1, wherein said ratio is ?1.1.6. The film of claim 1, wherein said ratio is ?1.2.7. The film of claim 1, wherein the film possesses a dart drop impact, as determined by ASTM D-1709, ?500 g/mil.8. The film of claims 1, 4, 5, 6, or 7, wherein said film has an MD tear ?350 g/mil, and a dart drop impact, as determined by ASTM D-1709, ?500 g/mil.9. The film of claim 8, wherein said film has an MD tear ?400 g/mil.10. The film of claim 8, wherein said film has an MD tear ?450 g/mil.11. The film of claim 8, wherein said film has an MD tear ?500 g/mil.12. A film comprising a linear low density ethylene (LLDPE), wherein said film has a ratio of MD tear to TD tear, both determined by ASTM D 1922, of ?9; and wherein the LLDPE is produced in a gas phase process by contacting ethylene, at least one comonomer having from 4 to 8 carbon atoms, and a hafnium transition metal metallocene-type catalyst system; wherein the MD tear of the film increases with increasing MD shrinkage.13. The film of claim 1, wherein said ratio is ?1.0.14. The film of claim 1, wherein said ratio is ?1.1.15. The film of claim 1, wherein said ratio is 1.2.16. The film of claim 1, wherein said ratio is 1.3.17. The film of claims 12, 13, 14. 15, or 16, wherein said film has an MD tear ?350 g/mil, and a dart drop impact, as determined by ASTM D-1709, ?500 g/mil.18. The film of claim 17, wherein said film has an MD tear ?450 g/mil.19. The film of claim 17, wherein said film has an MD tear ?500 g/mil.20. A process for producing the film of claims 12, 13, 14, 15, or 16, comprising extruding an LLDPE at a temperature effective to produce a film having an MD tear ?350 g/mil.21. The process of claim 20, wherein said film has an MD tear ?400 g/mil.22. The process of claim 20, wherein said film has an MD tear ?450 g/mil.23. The process of claim 20, wherein said film has an MD tear ?500 g/mil.24. A process for producing the film of claims 12, 13, 14, 15, or 16, comprising extruding said film of an LLDPE at a draw down ratio effective to produce a film having an MD tear ?350 g/mil.25. The process of claim 24, wherein said film has an MD tear ?400 g/mil.26. The process of claim 24, wherein said film has an MD tear ?450 g/mil.27. The process of claim 24, wherein said film has an MD tear ?500 g/mil.28. A process for producing the film of claims 12, 13, 14, 15, or 16, comprising extruding said film of an LLDPE at one or more of a temperature, or a draw down ratio effective to produce a film having an MD tear ?400 g/mil.29. A film made from a polymer composition possessing a density in the range of 0.910 to 0.940 g/cc, and a MW/Mn value of 2.5 to 7; wherein the polymer composition is produced in a gas phase process utilizing a hafnium transition metal metallocene-type catalyst system; wherein the film has a MD/TD tear ratio ?9 and wherein the MD tear of the film increases with increasing MD shrinkage.30. A polyolefin film comprising a linear low density ethylene extruded at a temperature or a draw down ratio effective to form a film having a MD tear to TD tear ratio of ?1.0; wherein said film has a MD tear ?450 g/mil and a dart drop impact ?500 g/mil; and wherein the LLDPE is produced in a gas phase process by contacting ethylene, at least one comonomer having from 4 to 8 carbon atoms, and a hafnium transition metal metallocene-type catalyst system; wherein the MD tear of the film increases with increasing MD shrinkage.31. The film of claim 30, wherein the temperature ranges from 350 to 550° F.32. The film of claim 30, wherein the temperature ranges from 390 to 450° F.33. The film of claim 30, wherein the draw down ratio ranges from 20 to 50.34. The film of claim 30, wherein the draw down ratio ranges from 30 to 40.35. A blown film having a balance of physical properties, comprising an LLDPE, wherein said film has a ratio of MD tear to TD tear, as measured by ASTM D 1922, of ?0 and a MD tear ?400 g/mil, and a dart drop impact, as measured by ASTM D-1709, ?500 g/mil; and wherein the LLDPE is produced in a gas phase process by contacting ethylene, at least one comonomer having from 4 to 8 carbon atoms and a hafnium transition metal metallocene-type catalyst system; wherein the MD tear of the film increases with increasing MD shrinkage.36. A polyethylene film comprising an LLDPE, said film having an MD tear ?500 g/mil, and a MD tear to TD tear ratio ?1.0, and a MD shrinkage of ?70%; wherein LLDPE is produced in a gas phase process utilizing a hafnium transition metal metallocene-type catalyst system and wherein the MD tear of the film increases with increasing MD shrinkage.37. The polyethylene film of claim 36, wherein said MD tear is ?550 g/mil.38. The polyethylene film of claim 37, wherein said shrinkage is ?75%, and wherein said film has a CDBI, as determined by CRYSTAF, ?50%, and wherein said LLDPE has an MD tear to intrinsic war ratio ?1.2.39. A film comprising a LLDPE having a MD/TD tear ratio ?0.9, wherein said LLDPE is substantially free of titanium and wherein said LLDPE has a CDBI, as determined by CRYSTAF, of ?45%; wherein LLDPE is produced in a gas phase process utilizing a hafnium transition metal metallocene-type catalyst system; wherein the MD tear of the film increases with increasing MD shrinkage.40. The film of any of claims 12, 30, 35, or 39, wherein the film properties are attainable at ?8 pounds of polymer per hour per inch of die circumference.41. The film of claim wherein the film properties are attainable at ?10 pounds of polymer per hour per inch of die circumference.42. The film of claim 40, wherein the film properties are attainable at ?12 pounds of polymer per hour per inch of die circumference.43. The film of claim 28, wherein the melt temperature of the polymer ranges from 350 to 550° F. and the die gaps range from 30 to 120 mils.44. A film made from a polymer composition possessing a density in the range of 0.910 to 0.940 g/cc, and a MW/Mn value of 2.5 to 7; and wherein the polymer composition is produced in a gas phase process by contacting ethylene, at least one comonomer having from 4 to 8 carbon atoms and a hafnium transition metal metallocene-type catalyst system; wherein the film has a MD/TD tear ratio ?0.9 and wherein the MD tear of the film increases with increasing MD shrinkage.45. The film of claim 44, further possessing a CDBI of ?55%.46. The film of claim 44, further possessing ?5 ppm titanium.47. The film of claim 44, the polymer composition comprising ethylene derived units, and 1 to 5 mole % comonomer derived units.48. The film of claim 47, wherein the comonomner derived units are hexene-1 or octene-1.49. The film of claim 44, wherein the hafnium component of the catalyst system comprises at least 95 mole % or greater of all the transition metal compounds of the catalyst system.50. The film of claim 44, wherein the film properties are attainable at ?8 pounds of polymer composition output per hour per inch of die circumference.51. The film of claim 44, wherein the film properties are attainable at ?10 pounds of polymer composition output per hour per inch of die circumference.52. The film of claim 44, wherein the film properties are attainable at ?12 pounds of polymer composition output per hour per inch of die circumference.53. The film of claim 51 or 52, wherein the melt temperature of the polymer composition ranges from 350 to 550° F. and the die gaps range from 30 to 120 mils.54. The film of claim 44, wherein the hafnium transition metal metallocene-type catalyst system is the product of the combination of a hafnium transition metal metallocene-type catalyst and a presupported activator in oil or a hydrocarbon.55. The film of claim 44, wherein the film possesses a draw down ratio ranging from 20 to 50.56. The film of claim 44, wherein the comonomer is hexene-l and the polymer composition possesses an MI of from 0.1 to 10 dg/min.57. The film of claims 12, 30, 35, 39, or 44, wherein the catalyst system consists of the hafnium metallocene, an activator and a support.58. The film of 12, 30, 35, 39, 44, 1, and 29, wherein the MD tear is ?500 g/mil and the MD shrinkage is ?70%.