Dual component LLDPE copolymers with improved impact and tear resistance

Patent metadata

Field	Value
Publication number	US-10435527-B2
Application number	US-201715715215-A
Country	US
Kind code	B2
Filing date	Sep 26, 2017
Priority date	Sep 26, 2017
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

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. A film comprising an ethylene polymer composition, the 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;
wherein the amount of the second ethylene polymer component is in a range from about 4 to about 50 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 1.8 to about 4.5;
a melt index less than or equal to about 3.5 g/10 min;
a CY-a parameter in a range from about 0.25 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 92 to about 105° C.

2. The film of claim 1 , wherein the film has a MD Elmendorf tear strength in a range from about 100 to about 450 g/mil.

3. 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 0.3:1 to about 0.8:1.

4. 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.

5. The film of claim 1 , wherein the film is a cast film having an average thickness in a range from about 0.7 to about 2 mils.

6. 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 500 g/mil.

7. 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.

8. The film of claim 1 , wherein:
the composition has a Mw in a range from about 100 to about 200 kg/mol; and
the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof.

9. The film of claim 1 , wherein the composition contains no measurable amount of hafnium or titanium.

10. The film of claim 1 , wherein:
the density is in a range from about 0.912 to about 0.922 g/cm 3 ;
the ratio of Mw/Mn is in a range from about 2.2 to about 3.8;
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 0.35 to about 0.65.

11. The film of claim 1 , wherein the amount of the second ethylene polymer component is in a range from about 4 to about 25 wt. %, based on the total weight of the first ethylene polymer component and the second ethylene polymer component.

12. 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 1.1:1 to about 2.5:1.

13. 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 0.5:1 to about 0.9:1.

14. The film 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.

15. The film of claim 1 , wherein the first peak is at a temperature in a range from about 68 to about 80° C., and the second peak is at a temperature in a range from about 94 to about 105° C.

16. 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;
wherein the amount of the second ethylene polymer component is in a range from about 4 to about 50 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 1.8 to about 4.5;
a melt index less than or equal to about 3.5 g/10 min;
a CY-a parameter in a range from about 0.25 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 92 to about 105° C.

17. The composition of claim 16 , 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.

18. The composition of claim 16 , wherein:
the composition comprises an ethylene homopolymer, an ethylene/α-olefin copolymer, or a combination thereof;
the composition is a single reactor product; and
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.

19. The composition of claim 16 , 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 68 to about 80° C., and the second peak is at a temperature in a range from about 94 to about 105° C.

20. An article of manufacture comprising the composition of claim 16 .

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

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

Classifications

• C08J2323/06

  Polyethene · CPC title

• C08L2201/10

  Transparent films; Clear coatings; Transparent materials · CPC title

• C08J2423/06

  Polyethene · CPC title

• C08J2423/08

  Copolymers of ethene (C08J2423/16 takes precedence) · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title