Metallocene catalyst system for producing LLDPE copolymers with tear resistance and low haze

Patent metadata

Field	Value
Publication number	US-11028258-B2
Application number	US-201916543686-A
Country	US
Kind code	B2
Filing date	Aug 19, 2019
Priority date	Aug 19, 2019
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

Ethylene polymers having a density from 0.908 to 0.925 g/cm 3 , a melt index from 0.5 to 3 g/10 min, a ratio of Mw/Mn from 2 to 4, a ratio of Mz/Mw from 1.6 to 2.3, a CY-a parameter from 0.45 to 0.6, and an ATREF profile characterized by a single peak at a peak ATREF temperature from 76 to 88° C., and by less than 4.5 wt. % of the polymer eluting above a temperature of 91° C. These ethylene polymers can be used to produce various articles of manufacture, such as blown and cast films with a beneficial combination of high tear resistance and low haze.

First claim

We claim:

1. A film comprising an ethylene polymer, wherein the film has:
a haze in a range from about 2 to about 10%; and
a MD Elmendorf tear strength in a range from about 200 to about 500 g/mil; and wherein the ethylene polymer has:
a density in a range from about 0.908 to about 0.925 g/cm 3 ;
a melt index in a range from about 0.5 to about 3 g/10 min;
a ratio of Mw/Mn in a range from about 2 to about 4;
a ratio of Mz/Mw in a range from about 1.6 to about 2.3;
a CY-a parameter in a range from about 0.45 to about 0.6; and
an ATREF profile characterized by a single peak at a peak ATREF temperature in a range from about 76 to about 88° C., and by less than or equal to about 4.5 wt % of the polymer eluting above a temperature of 91° C.

2. The film of claim 1 , wherein:
the peak ATREF temperature is in a range from about 79 to about 86° C.; and
less than or equal to about 3.5 wt % of the polymer elutes above a temperature of 91° C.

3. The film of claim 1 , wherein:
the haze is in a range from about 2 to about 8%; and
the MD Elmendorf tear strength is in a range from about 250 to about 400 g/mil.

4. The film of claim 1 , wherein:
the ethylene polymer has a unimodal molecular weight distribution; and
the ethylene polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or a combination thereof.

5. The film of claim 4 , wherein the film is a blown film having an average thickness in a range from about 0.8 to about 5 mils.

6. The film of claim 4 , wherein:
the density is in a range from about 0.91 to about 0.922 g/cm 3 ;
the melt index is in a range from about 1 to about 2.5 g/10 min;
the ratio of Mw/Mn is in a range from about 2.2 to about 3.8;
the ratio of Mz/Mw is in a range from about 1.7 to about 2.2; and
the CY-a parameter is in a range from about 0.5 to about 0.6.

7. The film of claim 6 , wherein the film is a cast film having an average thickness in a range from about 0.5 to about 8 mils.

8. The film of claim 4 , wherein the film has:
a ratio of MD Elmendorf tear strength to TD Elmendorf tear strength (MD:TD) in a range from about 0.5:1 to about 0.9:1; and
a dart impact strength of greater than or equal to about 500 g/mil.

9. The film of claim 1 , wherein the ethylene polymer has:
a Mn in a range from about 25,000 to about 55,000 g/mol; and
a high load melt index (HLMI) in a range from about 18 to about 45 g/10 min.

10. The film of claim 1 , wherein the ethylene polymer has:
a Mz in a range from about 175,000 to about 275,000 g/mol; and
an IB parameter in a range from about 0.9 to about 1.05.

11. The film of claim 1 , wherein:
the haze is in a range from about 2 to about 7%; and
the MD Elmendorf tear strength is in a range from about 300 to about 400 g/mil.

12. An ethylene polymer having:
a density in a range from about 0.908 to about 0.925 g/cm 3 ;
a melt index in a range from about 0.5 to about 3 g/10 min;
a ratio of Mw/Mn in a range from about 2 to about 4;
a ratio of Mz/Mw in a range from about 1.6 to about 2.3;
a CY-a parameter in a range from about 0.45 to about 0.6; and
an ATREF profile characterized by a single peak at a peak ATREF temperature in a range from about 76 to about 88° C., and by less than or equal to about 4.5 wt % of the polymer eluting above a temperature of 91° C.

13. The polymer of claim 12 , wherein the ethylene polymer has:
a Mw in a range from about 80,000 to about 180,000 g/mol; and
a relaxation time (τ η ) in a range from about 4×10 −3 sec to about 2×10 −2 sec.

14. An article of manufacture comprising the ethylene polymer of claim 13 .

15. The polymer of claim 12 , wherein:
the density is in a range from about 0.91 to about 0.922 g/cm 3 ;
the melt index is in a range from about 1 to about 2.5 g/10 min;
the ratio of Mw/Mn is in a range from about 2.2 to about 3.8;
the ratio of Mz/Mw is in a range from about 1.7 to about 2.2;
the CY-a parameter is in a range from about 0.52 to about 0.59;
the peak ATREF temperature is in a range from about 79 to about 86° C.; and
less than or equal to about 3.5 wt % of the polymer elutes above a temperature of 91° C.

16. The polymer of claim 12 , wherein the ATREF profile is further characterized by from about 0.05 to about 5 wt % of the polymer eluting below a temperature of 40° C., from about 14 to about 45 wt % of the polymer eluting between 40 and 76° C., from about 35 to about 53 wt % of the polymer eluting between 76 and 86° C., and the remainder of the polymer eluting above a temperature of 86° C.

17. An ethylene polymer having:
a density in a range from about 0.908 to about 0.925 g/cm 3 ;
a melt index in a range from about 0.5 to about 3 g/10 min;
a ratio of Mw/Mn in a range from about 2 to about 4;
a ratio of Mz/Mw in a range from about 1.6 to about 2.3;
a CY-a parameter in a range from about 0.45 to about 0.6; and
an ATREF profile characterized by a single peak at a peak ATREF temperature in a range from about 76 to about 90° C., by less than or equal to about 12 wt % of the polymer eluting above a temperature of 91° C., and by less than or equal to about 0.1 wt % of the polymer eluting above a temperature of 100° C.

18. An article of manufacture comprising the ethylene polymer of claim 17 .

19. The polymer of claim 17 , wherein:
the peak ATREF temperature is in a range from about 77 to about 89° C.;
less than or equal to about 11 wt % of the polymer elutes above a temperature of 91° C.; and
less than or equal to about 0.07 wt % of the polymer elutes above a temperature of 100° C.

20. The polymer of claim 17 , wherein the ethylene polymer:
has a unimodal molecular weight distribution; and
contains less than 0.1 ppm, independently, of hafnium and titanium.

21. The polymer of claim 17 , wherein:
the ethylene polymer further comprises an additive selected from an antioxidant, an acid scavenger, an antiblock additive, a slip additive, a colorant, a filler, a polymer processing aid, a UV additive, or a combination thereof; and
the ethylene polymer comprises an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, an ethylene/1-octene copolymer, or a combination thereof.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Tso Chung Ching
• Ding Errun
• Muninger Randall S
• Blagg John T
• Inn Yongwoo
• Mcdaniel Max P
• Sukhadia Ashish M
• Eppinger Sarah

Classifications

• C08F210/16 Primary

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

• C08J2323/08

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

• C08J5/18

  Manufacture of films or sheets · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08F2500/37

  Elution or crystallisation fractionation, e.g. as determined by. TREF or Crystaf · CPC title