Peroxide treated metallocene-based polyolefins with improved melt strength

Patent metadata

Field	Value
Publication number	US-10017617-B2
Application number	US-201715643527-A
Country	US
Kind code	B2
Filing date	Jul 7, 2017
Priority date	May 14, 2013
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

Disclosed herein are ethylene-based polymers having low densities and narrow molecular weight distributions, but high melt strengths for blown film processing. Such polymers can be produced by peroxide-treating a metallocene-catalyzed resin.

First claim

The invention claimed is:

1. A method of making a film comprising an ethylene polymer, the method comprising:
(i) providing an ethylene polymer having a ratio of Mw/Mn of less than or equal to about 5, a ratio of Mz/Mw of less than or equal to about 2.3, and a zero-shear viscosity at 190° C. of greater than or equal to about 1×10 5 Pa-sec;
wherein the ethylene polymer is further characterized by a peak melting point in a range from about 100 to about 120° C., a vicat softening temperature in a range from about 95 to about 110° C., and a difference between the peak melting point and the vicat softening temperature of less than or equal to about 16° C.; and
(ii) melt processing the ethylene polymer through a film die to form the film.

2. The method of claim 1 , wherein:
the method comprises melt processing the ethylene polymer and at least one additive through the die; and
the ethylene polymer is an ethylene/α-olefin copolymer.

3. The method of claim 2 , wherein the film is a blown film.

4. The method of claim 3 , wherein the ethylene/α-olefin copolymer is produced by a process comprising melt processing a mixture of a base resin and a peroxide compound in a twin screw extrusion system at a temperature in a range from about 120 to about 300° C. to generate peroxide groups at about 10-50 ppm of peroxide groups based on the weight of the base resin.

5. The method of claim 1 , wherein the ethylene polymer is further characterized by:
a melt index in a range from about 0.05 to about 2;
a ratio of HLMI/MI in a range from about 15 to about 50; and
a density in a range from about 0.895 to about 0.928 g/cm 3 .

6. The method of claim 1 , wherein:
the ratio of Mw/Mn is in a range from about 2 to about 5; and
the ratio of Mz/Mw is in a range from about 1.5 to about 2.3.

7. The method of claim 6 , wherein the zero-shear viscosity at 190° C. is in a range from about 1×10 5 to about 2×10 6 Pa-sec.

8. The method of claim 7 , wherein the film is a blown film or a cast film, and is characterized by a thickness in a range from about 0.5 to about 250 mils.

9. The blown film or cast film prepared by the method of claim 8 .

10. A method of making a film comprising an ethylene/α-olefin copolymer, the method comprising:
(i) providing an ethylene/α-olefin copolymer having:
a ratio of Mw/Mn in a range from about 2 to about 4;
a ratio of Mz/Mw in a range from about 1.5 to about 2.2;
a melt index in a range from 0 to about 1;
a zero-shear viscosity at 190° C. of greater than or equal to about 1×10 5 Pa-sec;
a density in a range from about 0.91 to about 0.92 g/cm 3 ; and
from about 0.008 to about 0.04 long chain branches (LCB) per 1000 total carbon atoms; and

(ii) melt processing the ethylene/α-olefin copolymer through a film die to form the film.

11. The method of claim 10 , wherein the copolymer is further characterized by:
a peak melting point in a range from about 105 to about 120° C.; and
a vicat softening temperature in a range from about 95 to about 110° C.

12. The method of claim 10 , wherein the copolymer is further characterized by a CY-a parameter at 190° C. in a range from about 0.08 to about 0.28.

13. The method of claim 10 , wherein:
the ethylene/α-olefin copolymer is produced by a process comprising melt processing a mixture of a base resin and a peroxide compound at a weight ratio of peroxide groups of the peroxide compound in a range from about 10 to about 60 ppm, based on the weight of the base resin; and
step (ii) comprises melt processing the ethylene/α-olefin copolymer and at least one additive through the film die to form the film.

14. The method of claim 10 , wherein the film is a blown film or a cast film, and is characterized by a thickness in a range from about 0.5 to about 250 mils.

15. The blown film or cast film prepared by the method of claim 14 .

16. A method of making a film comprising an ethylene/1-hexene copolymer, the method comprising:
(i) providing an ethylene/1-hexene copolymer having:
a ratio of Mw/Mn of less than or equal to about 5;
a ratio of Mz/Mw of less than or equal to about 2.3;
a zero-shear viscosity at 190° C. of greater than or equal to about 1×10 5 Pa-sec;
a CY-a parameter at 190° C. in a range from about 0.08 to about 0.28; and
a density in a range from about 0.905 to about 0.925 g/cm 3 ; and

(ii) melt processing the ethylene/1-hexene copolymer through a film die to form the film.

17. The method of claim 16 , wherein:
the ratio of Mw/Mn is in a range from about 2 to about 3.5; and
the ratio of Mz/Mw is in a range from about 1.5 to about 2.2.

18. The method of claim 17 , wherein:
the CY-a parameter at 190° C. is in a range from about 0.08 to about 0.18; or
the zero-shear viscosity at 190° C. is in a range from about 1×10 5 to about 2×10 6 Pa-sec; or
both.

19. The method of claim 17 , wherein the film is a blown film or a cast film, and is characterized by a thickness in a range from about 0.5 to about 250 mils.

20. The blown film or cast film prepared by the method of claim 19 .

21. A method of making a film comprising an ethylene/α-olefin copolymer, the method comprising:
(i) providing an ethylene/α-olefin copolymer having a ratio of Mw/Mn of less than or equal to about 5, a ratio of Mz/Mw of less than or equal to about 2.3, and a zero-shear viscosity at 190° C. of greater than or equal to about 1×10 5 Pa-sec;
wherein the ethylene/α-olefin copolymer is further characterized by a CY-a parameter at 190° C. in a range from about 0.08 to about 0.28, or from about 0.008 to about 0.04 long chain branches (LCB) per 1000 total carbon atoms, or both, and a density in a range from about 0.895 to about 0.928 g/cm 3 , and
(ii) melt processing the ethylene/α-olefin copolymer through a film die to form the film.

22. The method of claim 21 , wherein:
the ratio of Mw/Mn is in a range from about 2 to about 5;
the ratio of Mz/Mw is in a range from about 1.5 to about 2.3; and
the zero-shear viscosity at 190° C. is in a range from about 1×10 5 to about 2×10 6 Pa-sec.

23. The method of claim 22 , wherein the ethylene/α-olefin copolymer is further characterized by:
a melt index in a range from about 0.05 to about 2; and
a ratio of HLMI/MI in a range from about 15 to about 50.

24. The method of claim 22 , wherein the film is a blown film or a cast film, and is characterized by a thickness in a range from about 0.5 to about 250 mils.

25. The blown film or cast film prepared by the method of claim 24 .

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Cui Lili
• Sukhadia Ashish M
• Rohatgi Vivek

Classifications

• C08F10/02

  Ethene · CPC title

• B29C48/022

  characterised by the choice of material · CPC title

• B29C48/10

  flexible, e.g. blown foils · CPC title

• B29C39/003

  characterised by the choice of material · CPC title

• C08F8/00

  Chemical modification by after-treatment (graft polymers, block polymers, crosslinking with unsaturated monomers or with polymers C08F251/00 - C08F299/00; of conjugated diene rubbers C08C) · CPC title