Dual component LLDPE copolymers with improved impact and tear resistance

Patent metadata

Field	Value
Publication number	US-11352471-B2
Application number	US-201916706949-A
Country	US
Kind code	B2
Filing date	Dec 9, 2019
Priority date	Sep 26, 2017
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

Disclosed are ethylene polymer compositions containing a homogeneously-branched first ethylene polymer component and 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 melt index less than 3.5 g/10 min, and a CY-a parameter at 190° C. from 0.25 to 0.65. 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.

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 of higher density than the first ethylene polymer component, the second ethylene polymer component having a density in a range from about 0.945 to about 0.968 g/cm 3 ;
wherein the amount of the second ethylene polymer component is in a range from about 10 to about 25 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 Mw in a range from about 85 to about 200 kg/mol;
a ratio of Mw/Mn in a range from about 2 to about 3;
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 0.4 to about 0.65; and
an ATREF curve containing at least two peaks, with a first peak at a temperature in a range from about 67 to about 82° C., and a second peak at a temperature in a range from about 95 to about 105° C.

2. An article of manufacture comprising the composition of claim 1 .

3. The composition of claim 1 , wherein the difference between the temperatures (ΔT) of the first peak and the second peak is in a range from about 17 to about 32° C.

4. 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.

5. The composition of claim 4 , wherein the composition is further characterized by:
a ratio of Mz/Mw in a range from about 1.7 to about 2.3; and
a ratio of HLMI/MI in a range from about 15 to about 35.

6. The composition of claim 4 , wherein the composition is a single reactor product.

7. The composition of claim 4 , wherein the composition is a post-reactor blend.

8. A blown film comprising the composition of claim 4 .

9. The blown film of claim 8 , wherein the blown film has:
a haze of less than or equal to about 10%;
a dart impact strength of greater than or equal to about 500 g/mil; and
a MD Elmendorf tear strength in a range from about 100 to about 450 g/mil.

10. The blown film of claim 9 , wherein:
the haze is in a range from about 3 to about 8%;
the MD Elmendorf tear strength is in a range from about 125 to about 425 g/mil;
the blown film has a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.3:1 to about 0.8:1; and
the blown film has an average thickness in a range from about 0.5 to about 8 mils.

11. The composition of claim 1 , wherein:
the melt index is in a range from about 0.5 to about 1.8 g/10 min; and
the composition comprises an ethylene homopolymer, an ethylene/l-butene copolymer, an ethylene/l-hexene copolymer, an ethylene/l-octene copolymer, or any combination thereof.

12. The composition of claim 11 , wherein the first ethylene polymer component has a ratio of HLMI/MI in a range from about 12 to about 22.

13. The composition of claim 11 , wherein the first ethylene polymer component has a CY-a parameter in a range from about 0.45 to about 0.65.

14. The composition of claim 11 , wherein the second ethylene polymer component has a ratio of HLMI/MI in a range from about 12 to about 22.

15. The composition of claim 11 , wherein the second ethylene polymer component has a CY-a parameter in a range from about 0.45 to about 0.65.

16. The composition of claim 11 , wherein the second ethylene polymer component has a melt index in a range from about 0.5 to about 40 g/10 min.

17. The composition of claim 11 , wherein the composition is further characterized by:
a ratio of Mz/Mw in a range from about 1.7 to about 2.3; and
a ratio of HLMI/MI in a range from about 15 to about 35.

18. The composition of claim 17 , wherein the second ethylene polymer component has a melt index in a range from about 0.5 to about 40 g/10 min.

19. The composition of claim 18 , wherein the first ethylene polymer component has a density in a range from about 0.905 to about 0.918 g/cm 3 .

20. An article of manufacture comprising the composition of claim 19 .

21. The composition of claim 11 , wherein the composition contains less than 0.05 ppm, independently, of hafnium and titanium.

22. The composition of claim 11 , wherein the composition has a unimodal molecular weight distribution.

23. The composition of claim 11 , wherein the first ethylene polymer component has a density in a range from about 0.905 to about 0.918 g/cm 3 .

24. The composition of claim 23 , wherein the difference between the temperatures (AT) of the first peak and the second peak is in a range from about 18 to about 30° C.

25. The composition of claim 23 , wherein the first peak is at a temperature in a range from about 68 to about 80° C.

26. The composition of claim 11 , wherein the first ethylene polymer component has a density in a range from about 0.91 to about 0.918 g/cm 3 .

27. The composition of claim 26 , wherein the melt index is in a range from about 0.7 to about 1.7 g/10 min.

28. An article of manufacture comprising the composition of claim 27 .

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

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

Classifications

• C08J2323/08

  Copolymers of ethene (C08J2323/16 takes precedence) · CPC title

• C08L2201/10

  Transparent films; Clear coatings; Transparent materials · CPC title

• C08L2207/066

  LDPE (radical process) · CPC title

• C08L23/06

  Polyethylene · CPC title

• C08F210/16

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title