High melt strength polyethylene compositions and methods for making the same
AssigneeDow Global Technologies LLC
InventorsMehmet Demirors, Teresa Karjala, Nicolas Mazzola
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Abstract
The present invention is a method for increasing the melt strength of a polyethylene resin comprising reacting the polyethylene resin with a free radical generator with a decomposition energy in between −50 kJoule/mole and −250 kJoules/mole and a peak decomposition temperature of less than 280 degree C. The resulting resin has increased melt strength with higher ratio of elongational viscosities at 0.1 to 100 rad/s when compared to substantially similar polyethylene resins which have not been reacted with a free radical generator such as an alkoxy amine derivative.
Claims16
A method for increasing the melt strength of a polyethylene resin comprising the steps of:
- a) selecting a first polyethylene resin selected from the group consisting of LLDPE, HDPE, LDPE and blends thereof, wherein said first polyethylene resin has a density, as determined according to ASTM D792, in the range of from 0.900 g/cm3 to 0.970 g/cm3, and a melt index, as determined according to ASTM D1238 (2.16 kg, 190° C.), in the range of from 0.01 g/10 min to 30 g/10 min, and wherein said first polyethylene resin has less than 2000 ppm antioxidant;
- b) reacting said first polyethylene resin with a free radical generator with a decomposition energy in the range of from −50 kJoules/mole to −250 kJoules/mole, with a peak decomposition temperature of no less than 150 degree C. and not more than 280 degree C., wherein the free radical generator is in a carrier resin selected from the group consisting of LDPE, HDPE and blends thereof, wherein the carrier resin comprises less than 1,000 ppm antioxidant and wherein the free radical generator is in an amount in the range of from 30 to 200 ppm and added under conditions sufficient to increase the melt strength of the polyethylene resin by at least 20% over and above a control not reacted with said free radical generators.
A blend comprising:
- a) less than 100 percent by weight of a polyethylene polymer which has been formed by first selecting a first polyethylene resin selected from the group consisting of LLDPE, HDPE, LDPE and blends thereof, wherein said first polyethylene resin has a density, as determined according to ASTM D792, in the range of from 0.900 g/cm3 to 0.970 g/cm3, and a melt index, as determined according to ASTM D1238 (2.16 kg, 190° C.), in the range of from 0.01 g/10min to 30 g/10 min;
- and then reacting said first polyethylene resin with a free radical generator with a decomposition energy in the range of from -50 kJoules/mole to -250 kJoules/mole, with a peak decomposition temperature of no less than 150 degree C. and not more than 280 degree C., wherein the free radical generator is in a carrier resin selected from the group consisting of LDPE, HDPE and blends thereof, wherein the carrier resin comprises less than 1,000 ppm antioxidant and wherein the free radical generator is in an amount in the range of from 30 to 200 ppm and added under conditions sufficient to increase the melt strength of the polyethylene resin by at least 20% over and above a control not reacted with said free radical generators;
- wherein the unmodified first polyethylene resin is further characterized by having less than 1,000 ppm antioxidant and
- b) another polyethylene resin selected from the group consisting of LLDPE, HDPE, LDPE and blends thereof.
Dependencies are inferred from the claim text.