Ethylene-propylene copolymer

Claim 2

An ethylene-propylene copolymer comprising from 57 to 85 mole % bound propylene units, and correspondingly to 100 mole %, from 43 to 15 mole % bound ethylene units, said copolymer being characterized by having both of i) a reactivity ratio product r₁r₂ as determined from carbon 13 nuclear magnetic resonance spectral analysis of between 0.5 and 1.5 and ii) an isotactic index as determined from infra red spectral analysis of greater than 0%.

Claim 3

Ethylene-propylene copolymer of claim 1 having an isotactic index between 3 and 50 percent.

Claim 4

Ethylene-propylene copolymer of claim 1 having an isotactic index between 10 and 25 percent.

Claim 5

Ethylene-propylene copolymer of claim 3 having a weight average molecular weight greater than 50,000.

Claim 6

Ethylene-propylene copolymer of claim 4 having a polydispersity index between 1.5 and 2.0.

Claim 7

A blend of a thermoplastic alpha-olefin polymer and the ethylene-propylene copolymer of claim 1.

Claim 8

The blend of claim 6 wherein said thermoplastic alpha-olefin polymer is polypropylene.

Claim 9

A process for polymerizing an ethylene-propylene copolymer comprising from 57 to 85 mole % bound propylene units, and correspondingly to a total of 100 mole %, from 43 to 15 mole % bound ethylene units, said ethylene-propylene copolymer being characterized by having both of i) a reactivity ratio product r₁r₂ between 0.5 and 1.5, and ii) an isotactic index greater than 0%,said process comprising polymerizing ethylene and propylene in the presence of (a) a homogenous chiral catalyst of the formula where M is a group IVb metal selected from Ti, Hf and Zr, X₁ and X₂ are the same or different and are selected from bromine, chlorine and methyl, L₁ and L₂ are the same or different and each of said L₁ and said L₂ is a cyclopentadienyl ligand, and R¹ is a C₁₋₂₀ hydrocarbon which is bonded to said L₁ and said L₂, and (b) an alumoxane co-catalyst, at a temperature between -60 and 110°C.

Claim 10

A process for polymerizing an ethylene-propylene copolymer comprising from 57 to 85 mole % bound propylene units, and correspondingly to a total of 100 mole %, from 43 to 15 mole % bound ethylene units, said ethylene-propylene copolymer being characterized by having both of i) a reactivity ratio product r₁r₂ between 0.5 and 1.5, and ii) an isotactic index greater than 0%,said process comprising polymerizing ethylene and propylene in the presence of (a) a homogenous chiral catalyst of the formula where M is a group IVb metal selected from Ti, Hf and Zr, X₁ and X₂ are the same or different and are selected from bromine, chlorine and methyl, L₁ and L₂ are the same or different and each of said L₁ and said L₂ is a cyclopentadienyl ligand, and R¹ is a C₁₋₂₀ hydrocarbon which is bonded to said L₁ and said L₂, and (b) an alumoxane co-catalyst, at a temperature between -60 and 110°C.

Claim 11

The process of claim 8 wherein said L₁ and said L₂ are both tetrahydroindenyl ligand.

Claim 12

The process of claim 9 wherein said R is ethane.

Claim 13

The process of claim 10 wherein the polymerization temperature is from -10 to 40°C.