Patent ID: 8497329

Claim:
A method for altering the composition distribution of an ethylene alpha olefin copolymer, the method comprising contacting a reaction mixture and a catalyst system comprising a hafnocene in a reactor, wherein the reaction mixture comprises ethylene, hydrogen, and one or more alpha olefins, and wherein the composition distribution of the copolymer is altered by altering at least one or more of the following: a. the molar ratio of hydrogen to ethylene by 1% or more; b. the molar ratio of comonomer to ethylene by 1% or more; c. the partial pressure of ethylene by 50 kPa or more; and d. the temperature by 1° C. or more; wherein the maximum change in the copolymer's density is less than (+/−) 0.004 g/cm 3 , and wherein the maximum change in the copolymer's melt index, I 2 , measured according to ASTM-D-1238-E (190° C., 2.16 kg), is no more than 20%; and wherein the hafnocene is selected from the group consisting of: bis(n-propylcyclopentadienyl)hafnium Xn, bis(n-butylcyclopentadienyl)hafnium Xn, bis(n-pentylcyclopentadienyl)hafnium Xn, (n-propyl cyclopentadienyl)(n-butylcyclopentadienyl)hafnium Xn, bis[(2-trimethylsilylethyl)cyclopentadienyl]hafnium Xn, bis(trimethylsilyl cyclopentadienyl)hafnium Xn, dimethylsilylbis(n-propylcyclopentadienyl)hafnium Xn, dimethylsilylbis(n-butylcyclopentadienyl)hafnium Xn, bis(1-n-propyl-2-methylcyclopentadienyl)hafnium Xn, and (n-propylcyclopentadienyl)(1-n-propyl-3-n-butylcyclopentadienyl)hafnium Xn; wherein Xn is selected from the group consisting of halogen ions, hydrides, C1-12 alkyls, C2-12 alkenyls, C6-12 aryls, C7-20 alkylaryls, C1-12 alkoxys, C6-16 aryloxys, C7-18 alkylaryloxys, C1-12 fluoroalkyls, C6-12 fluoroaryls, and C1-12 heteroatom-containing hydrocarbons and substituted derivatives thereof.