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

Patent metadata

Field	Value
Publication number	US-11427703-B2
Application number	US-201916363221-A
Country	US
Kind code	B2
Filing date	Mar 25, 2019
Priority date	Mar 25, 2019
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

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. A film comprising an ethylene polymer composition, the composition comprising:
(i) a homogeneously-branched first ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25; 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 ratio of HLMI/MI in a range from about 12 to about 25;
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 3;
a melt index 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 film of claim 1 , wherein the film has:
a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.25:1 to about 0.8:1; and
a MD Elmendorf tear strength in a range from about 100 to about 500 g/mil.

3. The film of claim 1 , wherein the film is a blown film having an average thickness in a range from about 0.5 to about 8 mils.

4. The film of claim 1 , wherein the film has:
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.

5. The film of claim 1 , wherein the film has:
a MD Elmendorf tear strength in a range from about 125 to about 425 g/mil; and
a TD Elmendorf tear strength in a range from about 200 to about 800 g/mil.

6. The film of claim 1 , wherein:
the composition has a Mw in a range from about 100 to about 200 kg/mol;
the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof; and
the composition contains no measurable amount of hafnium or titanium.

7. The film of claim 1 , wherein:
the density is in a range from about 0.915 to about 0.925 g/cm 3 ;
the ratio of Mw/Mn is in a range from about 2.2 to 3;
the melt index is in a range from about 0.5 to about 1.8 g/10 min; and
the CY-a parameter is in a range from about 0.4 to about 0.65.

8. The film of claim 1 , wherein the amount of the second ethylene polymer component is in a range from about 20 to about 30 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component.

9. The film of claim 1 , wherein a ratio of the Mw of the first ethylene polymer component to the Mw of the second ethylene polymer component is in a range from about 0.8:1 to about 1.2:1.

10. The film of claim 1 , wherein 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.

11. The film of claim 1 , wherein the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

12. An ethylene polymer composition comprising:
(i) a homogeneously-branched first ethylene polymer component having a ratio of HLMI/MI in a range from about 12 to about 25; 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 ratio of HLMI/MI in a range from about 12 to about 25;
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 3;
a melt index 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.

13. The composition of claim 12 , wherein the composition:
has a Mw in a range from about 100 to about 200 kg/mol;
has a unimodal molecular weight distribution;
contains no measurable amount of hafnium or titanium; and
contains less than 10 long chain branches (LCB) per million total carbon atoms.

14. The composition of claim 12 , wherein:
the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof;
the composition is a single reactor product; 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.

15. The composition of claim 12 , 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;
the composition is a post-reactor blend; and
the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

16. The composition of claim 12 , wherein:
the ratio of Mw/Mn is in a range from about 2.2 to 3;
the melt index is in a range from about 0.5 to about 1.8 g/10 min; and
the CY-a parameter is in a range from about 0.4 to about 0.65; and
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.

17. The composition of claim 16 , wherein the first peak is at a temperature in a range from about 63 to about 69° C., and the second peak is at a temperature in a range from about 94 to about 102° C.

18. The composition of claim 16 , wherein the composition contains:
no measurable amount of hafnium or titanium; and
less than 10 long chain branches (LCB) per million total carbon atoms.

19. The composition of claim 16 , wherein the composition has a Mw in a range from about 100 to about 200 kg/mol.

20. The composition of claim 16 , wherein 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.

21. The composition of claim 16 , wherein the composition has:
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 2.2.

22. 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 0.965 g/cm 3 and a component melt index 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

Assignees

• Chevron Phillips Chemical Co Lp
• Chevran Phillips Chemical Company LP

Inventors

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

Classifications

• C08L23/06 Primary

  Polyethylene · CPC title

• C08L2203/16

  used for films · CPC title

• C08J2323/06

  Polyethene · CPC title

• B29C48/08

  flexible, e.g. films · CPC title

• B29K2023/06

  PE, i.e. polyethylene · CPC title