PROCESS FOR INCREASING ETHYLENE INCORPORATION INTO RANDOM COPOLYMERS

摘要

Random copolymers may be prepared using a process that includes polymerizing a mixture of monomers including at least propylene and ethylene monomer, in the presence of a catalyst system including a metallocene catalyst having the general structure: racemic-X(2-R<SUP>1</SUP>-4-R<SUP>2</SUP>-lnd)<SUB>2</SUB>MCI<SUB>2</SUB> wherein M is a Group 4, 5 or 6 transition metal, or a lanthanide or actinide series metal; X is a structural bridge imparting stereorigidity; R1 is hydrogen or an alkyl, aryl or a substitution moiety; R<SUP>2</SUP> is hydrogen, or a C1-C4 alkyl; and lnd is an indenyl group. The copolymers are prepared under reaction conditions suitable to form a copolymer, wherein the copolymer has a higher level of ethylene incorporation than a corresponding polymer formed under otherwise identical reaction conditions except that a different bisindeny metallocene catalyst having a 4-indenyl substitution larger than 4 carbons is used. The copolymers may have a lower melt temperature than the corresponding polymers. The resulting copolymers may be used to prepare articles of manufacture including, but not limited to films, fibers and injection molded articles.