Production of vinyl terminated polyethylene

1. A process to produce polyethylene comprising:

(a) contacting ethylene with a metallocene catalyst system;

wherein the catalyst system comprises:

(i) a stoichiometric activator;

(ii) a metallocene compound represented by the formula:

(b) obtaining a vinyl terminated polyethylene having:

(i) at least 50% allyl chain ends, based on total unsaturations;

(ii) a molecular weight distribution of less than or equal to 4.0;

(iii) a g′(vis) of 0.95 or less; and

(iv) a Mn (′H NMR) of at least 7,000 g/mol.

2. The process of claim 1 , wherein the vinyl terminated polyethylene is an ethylene polymer having less than 2 wt % of a C 3 to C 40 alphaolefin comonomer.

3. The process of claim 2 , wherein the vinyl terminated polyethylene has at least 60% allyl chain ends, based on total unsaturations.

4. The process of claim 2 , wherein the vinyl terminated polyethylene has a molecular weight distribution of less than or equal to 3.5.

5. The process of claim 1 , wherein the vinyl terminated polyethylene is an ethylene homopolymer having 0 wt % of a C 3 to C 40 alphaolefin comonomer and has greater than 85% allyl chain ends, based on total unsaturations.

6. The process of claim 1 , wherein the vinyl terminated polyethylene comprises 0 wt % of a C 3 to C 40 alphaolefin comonomer.

7. The process of claim 1 , wherein the vinyl terminated polyethylene comprises from about 2 wt % to about 20 wt % of a C 3 to C 40 alphaolefin comonomer.

8. The process of claim 7 , wherein the vinyl terminated polyethylene has at least 60% allyl chain ends, based on total unsaturations.

9. The process of claim 1 , wherein the vinyl terminated polyethylene has a Mn (GPC)/Mn NMR) in the range of from about 0.8 to about 1.2.

10. The process of claim 1 , wherein the vinyl terminated polyethylene has a Mn (GPC)/Mn NMR) in the range of from about 0.9 to about 1.1.

11. The process of claim 1 , wherein the activator is a bulky activator represented by the formula:

wherein

each R 1 is, independently, a halide;

each R 2 is, independently, a halide, a C 6 to C 20 substituted aromatic hydrocarbyl group or a siloxy group of the formula —O—Si—R a , where R a is a C 1 to C 20 substituted or unsubstituted hydrocarbyl or hydrocarbylsilyl group;

each R 3 is a halide, C 6 to C 20 substituted aromatic hydrocarbyl group or a siloxy group of the formula —O—Si—R a , where R a is a C 1 to C 20 substituted or unsubstituted hydrocarbyl or hydrocarbylsilyl group; wherein R 2 and R 3 can form one or more saturated or unsaturated, substituted or unsubstituted rings;

L is an neutral Lewis base;

(L-H) + is a Bronsted acid;

d is 1, 2, or 3;

wherein the anion has a molecular weight of greater than 1020 g/mol; and

wherein at least three of the substituents on the B atom each have a molecular volume of greater than 250 cubic A.

12. The process of claim 1 , wherein the activator is one or more of:

trimethylammonium tetrakis(perfluoronaphthyl)borate, tri ethyl ammonium tetrakis(perfluoronaphthyl)borate, tripropylammonium tetrakis(perfluoronaphthyl)borate, tri(n-butyl)ammonium tetrakis(perfluoronaphthyl)borate, tri(t-butyl)ammonium tetrakis(perfluoronaphthyl)borate, N,N-dimethylanilinium tetrakis(perfluoronaphthyl)borate, N,N-diethylanilinium tetrakis(perfluoronaphthyl)borate, N,N-dimethyl-(2,4,6-trimethylanilinium)tetrakis(perfluoronaphthyl)borate, tropillium tetrakis(perfluoronaphthyl)borate, triphenylcarbenium tetrakis(perfluoronaphthyl)borate, triphenylphosphonium tetrakis(perfluoronaphthyl)borate, triethylsilylium tetrakis(perfluoronaphthyl)borate, benzene(diazonium)tetrakis(perfluoronaphthyl)borate, trimethylammonium tetrakis(perfluorobiphenyl)borate, triethylammonium tetrakis(perfluorobiphenyl)borate, tripropylammonium tetrakis(perfluorobiphenyl)borate, tri(n-butyl)ammonium tetrakis(perfluorobiphenyl)borate, tri(t-butyl)ammonium tetrakis(perfluorobiphenyl)borate, N,N-dimethylanilinium tetrakis(perfluorobiphenyl)borate, N,N-diethylanilinium tetrakis(perfluorobiphenyl)borate, N,N-dimethyl-(2,4,6-trimethylanilinium)tetrakis(perfluorobiphenyl)borate, tropillium tetrakis(perfluorobiphenyl)borate, triphenylcarbenium tetrakis(perfluorobiphenyl)borate, triphenylphosphonium tetrakis(perfluorobiphenyl)borate, tri ethyl silylium tetrakis(perfluorobiphenyl)borate, benzene(diazonium)tetrakis(perfluorobiphenyl)borate, [4-t-butyl-PhNMe 2 H] [(m-C 6 F 5 -C 6 F 4 ) 4 B].

13. The process of claim 1 , wherein the contacting step (a) takes place at a temperature in the range of from about 40° C. to about 150° C.

14. The process of claim 1 , wherein the contacting step (a) takes place at a pressure in the range of from about 0.55 MPa to about 2.4 MPa.

15. The process of claim 1 , wherein the polyethylene has a g′(vis) of less than 0.90.

16. The process of claim 1 , wherein the polyethylene has a g′(vis) of less than 0.85.

17. The process of claim 1 , wherein the polyethylene has an Mn of less than 125,000 g/mol.