Ziegler-Natta catalyst for high temperature polymerization

1. A procatalyst for polymerization of ethylene and α-olefins on a delta form MgCl 2 support comprising a Ti 3+ complex of the formula TiCl 3 *[[R 4 ] a [R 5 O] b AlX 3-c ] d

wherein

a is 0 to 1;

b is 0 to 1;

c=a+b;

d is from about 0.33 to about 1.0;

each R 4 and R 5 is independently selected from C 1-8 alkyl radicals;

each X is independently selected from the halogen radicals;

the Mg/Ti molar ratio is from about 5 to about 10;

and further wherein at least 60% of the total Ti present is in the Ti 3+ oxidation state.

2. The procatalyst of claim 1 , wherein X is Cl.

3. The procatalyst of claim 1 , wherein a is 0 and b is 0.

4. The procatalyst of claim 1 , wherein a is 0 and b is 1.

5. The procatalyst of claim 1 , wherein a is 1 and b is 0.

6. The procatalyst of claim 1 , wherein each R 5 is ethyl.

7. The procatalyst of claim 1 , wherein the Mg/Ti ratio is from about 5 to about 8.

8. The procatalyst of claim 1 , wherein the Ti 3+ complex is TiCl 3 *[OEtAlCl 2 ] d , and the Mg/Ti molar ratio is from about 5 to about 8.

9. The procatalyst of claim 1 , wherein the Ti 3+ complex is TiCl 3 *[ClAlCl 2 ] d , and the Mg/Ti molar ratio is from about 5 to about 8.

10. The procatalyst of claim 1 , wherein the EPR spectrum and its simulation of the procatalyst has a characteristic g value of 1.950.

11. The procatalyst of claim 1 , wherein electron paramagnetic resonance (EPR) indicates the presence of a species C, wherein the species C is associated with a tetrahedral Ti 3+ species and wherein species C is about 0.2% or more of the Ti 3+ species detected in the EPR spectra.

12. The procatalyst of claim 1 , wherein electron paramagnetic resonance (EPR) indicates the presence of a species C, wherein the species C is associated with a tetrahedral Ti 3+ species and wherein species C is about 0.3% to about 1% of the Ti 3+ species detected in the EPR spectra.

13. A process to prepare an olefin polymerization procatalyst comprising a Ti 3+ complex, said process comprising:

a) forming a delta form MgCl 2 species by combining

i) R 2 Mg in a solvent selected from C 5-12 alkanes, and

ii) reactive organic chloride or HCl;

wherein each R is independently selected from C 2-8 alkyl radicals,

and wherein the mole ratio of added Cl and Mg is from about 2.0 to about 3.0;

b) adding to said delta form MgCl 2 species prepared in step a) either

i) R 1 x AlX 3-x and a tetravalent titanium compound in any order or at the same time,

wherein the AIM molar ratio is from about 3 to about 10;

or

ii) an aluminum alkyl halide of the formula R 1 x AlX 3-x first, a tetravalent titanium compound second, followed by an alkyl aluminum alkoxide of the formula R 4 y AlOR 5 3-y , wherein the Al/Ti molar ratio when measuring Al supplied from R 1 x AlX 3-x only is from about 0.7 to about 2 and the Al/Ti molar ratio when measuring Al supplied from R 4 y AlOR 5 3-y is from about 1 to about 2;

and further wherein

the Mg/Ti molar ratio is from about 5 to about 10;

x is 1 or 2;

y is 1 or 2;

each R 1 is independently selected from C 1-8 alkyl radicals;

the tetravalent titanium compound is selected from TiR 2 X 3 , Ti(OR 3 )X 3 , TiX 4 , and mixtures thereof;

each X is independently selected from the halogen radicals;

each R 2 is independently selected from C 1-8 alkyl radicals and benzyl; and

each R 3 , R 4 and R 5 are independently selected from C 1-8 alkyl radicals.

14. The process of claim 13 , wherein the reactive organic chloride is tertiary-butylchloride (tBuCl).

15. The process of claim 13 , wherein step a) is performed at a temperature between about 20° C. and about 160° C.

16. The process of claim 13 , wherein step b) or c) is performed at a temperature between about 40° C. and 90° C.

17. The process of claim 13 , wherein R 2 Mg is selected from butylethyl magnesium (BEM), dibutyl magnesium, and butyloctyl magnesium (BOM).

18. The process of claim 13 , wherein the solvent is decane.

19. The process of claim 13 , wherein the Cl/Mg mole ratio is from about 2.15 to about 2.5.

20. The process of claim 13 , wherein R 1 x AlX 3-x is selected from isobutylaluminum dichloride (IBADC), ethylaluminumdichloride.

21. The process of claim 13 , wherein the tetravalent titanium compound is TiCl 4 .

22. The process of claim 13 , wherein R 4 y AlOR 5 3-y is diethylaluminumethoxide.

23. A procatalyst product comprising a Ti 3+ complex prepared by the process of claim 13 .

24. A solution olefin polymerization process comprising

i) adding to one or more continuous stirred tank reactor (CSTR), optionally followed by a tubular reactor, either in series or parallel, a solvent selected from C 5-12 alkanes, or mixtures thereof, and a procatalyst for polymerization on a delta form MgCl 2 support comprising a Ti 3+ complex of the formula TiCl 3 *[[R 4 ] a [R 5 O] b AlX 3-c ] d

wherein

a is 0 to 1;

b is 0 to 1;

c=a+b;

d is from 0.33 to 1.0;

each R 4 and R 5 is independently selected from C 1-8 alkyl radicals;

each X is independently selected from the halogen radicals;

wherein at least 60% of the total Ti present is in the Ti 3+ oxidation state;

ii) adding ethylene, hydrogen and optionally one or more comonomers selected from C 3-8 comonomers to the reactor; and

iii) adding an aluminum alkyl activator to the reactor in a molar ratio of about 1 to about 10 relative to the amount of procatalyst.

25. The polymerization process of claim 24 , wherein the activator is an aluminum alkyl activator selected from diethylaluminumethoxide and trialkyl aluminum compounds, and MAO.

26. The polymerization process of claim 24 , wherein the solvent is isohexane or decane.

27. The polymerization process of claim 24 , wherein the polymerization temperature is at least about 240° C.

28. The polymerization process of claim 24 , wherein the polymerization results in a polymer having the same density but where the process uses at least about 10% less comonomer feed compared to a polymerization process using a procatalyst for polymerization that contains substantially no tetrahedral Ti 3+ species.

29. The polymerization process of claim 24 , wherein the polymerization results in a polymer with the same density but with a higher Mw at any polymerization temperature than the Mw obtained for a polymer prepared using a procatalyst for polymerization that contains substantially no tetrahedral Ti 3+ species.

30. The polymerization process of claim 24 , wherein the reactor hold-up time is from about 30 seconds to about 5 minutes.