Process for the oligomerization of alpha-olefins having low unsaturation, the resulting polymers, and lubricants containing same

A poly(α-olefin) copolymer obtained from the polymerization of at least one α-olefin having from 2 to about 20 carbon atoms and at least one bulky olefin, the process comprising polymerizing the monomers in the presence of hydrogen and a catalytically effective amount of a catalyst comprising the product obtained by combining a metallocene procatalyst with a cocatalyst, the metallocene procatalyst being at least one compound of general formula:

• (Cp1R1m)R3(Cp2R2p)MXq
• wherein Cp1 of ligand (Cp1R1m) and Cp2 of ligand (Cp2R2p) are the same or different cyclopentadienyl rings, R1 and R2 each is, independently, hydrogen or a hydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, m is 0 to 5, p is 0 to 5 and two R1 and/or R2 substituents on adjacent carbon atoms of the cyclopentadienyl ring associated therewith can be joined together to form a ring fused to the cyclopentadienyl ring, the fused ring containing from 4 to about 20 carbon atoms, R3 is a bridging group bridging Cp1 and Cp2, M is a transition metal having a valence of from 3 to 6, each X is a non-cyclopentadienyl ligand and is, independently, halogen or a hydrocarbyl, oxyhydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid, oxyhydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, q is equal to the valence of M minus 2, the cocatalyst being an aluminoxane and it being provided that ligand (CP1R1m) is different from ligand (Cp2R2p) and bridging group R3 contains at least two bulky groups.

A lubricant composition comprising a lubricant and a viscosity-modifying amount of a poly(α-olefin) copolymer obtained from the polymerization of at least one α-olefin having from 2 to about 20 carbon atoms and at least one bulky olefin, the process comprising polymerizing the monomers in the presence of hydrogen and a catalytically effective amount of a catalyst comprising the product obtained by combining a metallocene procatalyst with a cocatalyst, the metallocene procatalyst being at least one compound of general formula:

• (Cp1R1m)R3(Cp2R2p)MXq
• wherein Cp1 of ligand (Cp1R1m) and Cp2 of ligand (Cp2R2p) are the same or different cyclopentadienyl rings, R1 and R2 each is, independently, hydrogen or a hydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, m is 0 to 5, p is 0 to 5 and two R1 and/or R2 substituents on adjacent carbon atoms of the cyclopentadienyl ring associated therewith can be joined together to form a ring fused to the cyclopentadienyl ring, the fused ring containing from 4 to about 20 carbon atoms, R3 is a bridging group bridging Cp1 and Cp2, M is a transition metal having a valence of from 3 to 6, each X is a non-cyclopentadienyl ligand and is, independently, halogen or a hydrocarbyl, oxyhydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid, oxyhydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, q is equal to the valence of M minus 2, the cocatalyst being an aluminoxane and it being provided that ligand (Cp1R1m) is different from ligand (Cp2R2p) and bridging group R3 contains at least two bulky groups.

A method for improving the viscosity index of a lubricant composition comprising adding to the composition a viscosity-modifying amount of a poly(α-olefin) copolymer obtained from the polymerization of at least one α-olefin having from 2 to about 20 carbon atoms and at least one bulky olefin, the process comprising polymerizing the monomers in the presence of hydrogen and a catalytically effective amount of a catalyst comprising the product obtained by combining a metallocene procatalyst with a cocatalyst, the metallocene procatalyst being at least one compound of general formula:

• (Cp1R1m)R3(Cp2R2p)MXq
• wherein Cp1 of ligand (Cp1R1m) and Cp2 of ligand (Cp2R2p) are the same or different cyclopentadienyl rings, R1 and R2 each is, independently, hydrogen or a hydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, m is 0 to 5, p is 0 to 5 and two R1 and/or R2 substituents on adjacent carbon atoms of the cyclopentadienyl ring associated therewith can be joined together to form a ring fused to the cyclopentadienyl ring, the fused ring containing from 4 to about 20 carbon atoms, R3 is a bridging group bridging Cp1 and Cp2, M is a transition metal having a valence of from 3 to 6, each X is a non-cyclopentadienyl ligand and is, independently, halogen or a hydrocarbyl, oxyhydrocarbyl, halocarbyl, hydrocarbyl-substituted organometalloid, oxyhydrocarbyl-substituted organometalloid or halocarbyl-substituted organometalloid group containing up to about 20 carbon atoms, q is equal to the valence of M minus 2, the cocatalyst being an aluminoxane and it being provided that ligand (Cp1R1m) is different from ligand (Cp2R2p) and bridging group R3 contains at least two bulky groups.