Dual component LLDPE copolymers with improved impact and tear resistance, and methods of their preparation

Patent metadata

Field	Value
Publication number	US-11634567-B2
Application number	US-202217841803-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Mar 25, 2019
Publication date	Apr 25, 2023
Grant date	Apr 25, 2023

Abstract

Disclosed are ethylene polymer compositions containing a homogeneously-branched first ethylene polymer component and 15-35 wt. % of a homogeneously-branched second ethylene polymer component of higher density than the first ethylene polymer component. The ethylene polymer composition can be characterized by a density from 0.912 to 0.925 g/cm3, a ratio of Mw/Mn from 2 to 5, a melt index less than 2 g/10 min, and a CY-a parameter at 190° C. from 0.35 to 0.7. These polymer compositions have the excellent dart impact strength and optical properties of a metallocene-catalyzed LLDPE, but with improved machine direction tear resistance, and can be used in blown film and other end-use applications. Further, methods for improving film Elmendorf tear strength also are described.

First claim

We claim:

1. An ethylene polymer composition comprising:
(i) a homogeneously-branched first ethylene polymer component; and
(ii) a homogeneously-branched second ethylene polymer component having a second component density in a range from about 0.935 to about 0.972 g/cm 3 and a second component melt index in a range from about 0.5 to about 40 g/10 min;
wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component; and
wherein the composition is characterized by:
a density in a range from about 0.912 to about 0.925 g/cm 3 ;
a ratio of Mw/Mn in a range from about 2 to about 5;
a melt index in a range from about 0.3 to about 2 g/10 min;
a CY-a parameter in a range from about 0.35 to about 0.7; and
an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

2. The composition of claim 1 , wherein:
the second component density is from about 0.94 to about 0.96 g/cm 3 ; and
the second component melt index is from about 0.5 to about 8 g/10 min.

3. The composition of claim 2 , wherein the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof.

4. The composition of claim 3 , wherein the amount of the second ethylene polymer component is from about 15 to about 30 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component.

5. The composition of claim 3 , wherein the composition is a single reactor product.

6. The composition of claim 3 , wherein the composition is a post-reactor blend.

7. The composition of claim 3 , wherein the composition contains no measurable amount of hafnium or titanium.

8. The composition of claim 3 , wherein the composition is further characterized by:
a Mw in a range from about 100 to about 200 kg/mol; and
a ratio of Mz/Mw in a range from about 1.7 to about 2.2.

9. An article of manufacture comprising the composition of claim 8 .

10. A film comprising the composition of claim 8 , wherein the film has:
a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil;
a haze of less than or equal to about 10%; and
a dart impact strength of greater than or equal to about 250 g/mil.

11. The film of claim 10 , wherein the dart impact strength is greater than or equal to about 500 g/mil.

12. The composition of claim 1 , wherein the composition comprises an ethylene homopolymer, an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or any combination thereof.

13. The composition of claim 12 , wherein:
the CY-a parameter is from about 0.4 to about 0.6; and
the amount of the second ethylene polymer component is from about 15 to about 28 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component.

14. The composition of claim 12 , wherein the composition is further characterized by:
a ratio of HLMI/MI in a range from about 12 to about 25; and
a ratio of Mz/Mw in a range from about 1.7 to about 2.5.

15. The composition of claim 12 , wherein:
the second peak is at a temperature from about 94 to about 102° C.; and
a difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 26 to about 39° C.

16. The composition of claim 12 , wherein the composition, the first ethylene polymer component, and the second ethylene polymer component, independently, contain less than 10 long chain branches (LCB) per million total carbon atoms.

17. A film comprising the composition of claim 12 , wherein the film has:
a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil;
a haze of less than or equal to about 10%; and
a dart impact strength of greater than or equal to about 250 g/mil.

18. An ethylene polymer composition comprising:
(i) a homogeneously-branched first ethylene polymer component having a first component density in a range from about 0.905 to about 0.918 g/cm 3 ; and
(ii) a homogeneously-branched second ethylene polymer component having a second component density in a range from about 0.935 to about 0.972 g/cm 3 and a second component melt index in a range from about 0.5 to about 40 g/10 min;
wherein the amount of the second ethylene polymer component is in a range from about 15 to about 35 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component; and
wherein the composition is characterized by:
a density in a range from about 0.912 to about 0.925 g/cm 3 ;
a ratio of Mw/Mn in a range from about 2 to about 5;
a melt index in a range from about 0.3 to about 2 g/10 min;
a CY-a parameter in a range from about 0.35 to about 0.7; and
an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 60 to about 72° C., and a second peak at a temperature in a range from about 92 to about 104° C.

19. The composition of claim 18 , wherein first component density is from about 0.91 to about 0.918 g/cm 3 .

20. The composition of claim 18 , wherein the composition contain less than 5 long chain branches (LCB) per million total carbon atoms.

21. The composition of claim 18 , wherein first component is further characterized by a first component melt index in a range from about 0.5 to about 1.8 g/10 min.

22. A film comprising the composition of claim 18 , wherein the film has:
a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil;
a haze of less than or equal to about 10%; and
a dart impact strength of greater than or equal to about 250 g/mil.

23. The composition of claim 1 , wherein the ratio of Mw/Mn is in a range from about 2 to 3.

24. The film of claim 10 , wherein the ratio of Mw/Mn is in a range from about 2 to 3.

25. The composition of claim 18 , wherein the ratio of Mw/Mn is in a range from about 2 to 3.

26. The film of claim 22 , wherein the ratio of Mw/Mn is in a range from about 2 to 3.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Praetorius Jeremy M
• Tso Chung Ching
• Sukhadia Ashish M
• Inn Yongwoo
• Yang Qing
• Blagg John T

Classifications

• C08L2203/16

  used for films · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08L2207/066

  LDPE (radical process) · CPC title

• C08L23/06 Primary

  Polyethylene · CPC title

• B29C48/022

  characterised by the choice of material · CPC title