Polyethylene films with improved physical properties
AssigneeUnivation Technologies, LLC
InventorsJames McLeod Farley, John F. Szul, Matthew Gary McKee
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Abstract
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.
Claims58
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.
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.
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.
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.
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.
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.
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.
The film of claim wherein the film properties are attainable at ≧10 pounds of polymer per hour per inch of die circumference.
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.
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%.
Dependencies are inferred from the claim text.