Multilayer films

Patent metadata

Field	Value
Publication number	US-9994004-B2
Application number	US-201414187671-A
Country	US
Kind code	B2
Filing date	Feb 24, 2014
Priority date	Mar 12, 2013
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A multilayer film is prepared from a high impact strength polyethylene (HI polyethylene); a Ziegler Natta catalyzed polyethylene (Z/N polyethylene) and a high pressure low density polyethylene (LD polyethylene) with i) at least one skin layer consists essentially of HI polyethylene and ii) at least one core layer comprises a blend of Z/N polyethylene and said LD polyethylene. The HI polyethylene has a density of from 0.915 to about 0.930 g/cc and a normalized impact strength of at least about 300 g/mil. The amount of HI polyethylene is from about 30 to about 55 weight % (based on the combined weights of the HI+Z/N+LD polyethylenes). The films described herein are readily prepared on blown film equipment and provide an excellent balance of mechanical properties.

First claim

What is claimed is:

1. A multilayer film having a normalized impact strength of at least about 300 grams, the film comprising an HI polyethylene that is prepared with a metallocene catalyst and has a density of from 0.915 to 0.930 g/cc and an SCBDI of from 70 to 100; a Z/N polyethylene; and an LD polyethylene, said film comprising
A) a skin layer consisting essentially of said HI polyethylene; and
B) a core layer consisting essentially of said Z/N polyethylene and said LD polyethylene,

with the provisos that
a) the amount of said HI polyethylene is from 30 to 55 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film; and
b) the amount of said LD polyethylene is from 5 to 20 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film.

2. The multilayer film of claim 1 wherein said HI polyethylene has a melt index, I 2 , of from about 0.5 to about 2.0 g/10 minutes.

3. The multilayer film of claim 1 wherein said Z/N polyethylene has a density of from about 0.910 to about 0.965 g/cc.

4. The multilayer film of claim 1 wherein said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc.

5. The multilayer film of claim 1 wherein said Z/N polyethylene has a melt index, I 2 , of from about 0.2 to about 10 g/10 minutes.

6. The multilayer film of claim 1 wherein said Z/N polyethylene has a melt index, I 2 , of from about 0.5 to about 5 g/10 minutes.

7. The multilayer film of claim 1 wherein said Z/N polyethylene has a density of from about 0.910 to about 0.965 g/cc and a melt index, I 2 , of from about 0.2 to about 10 g/10 minutes.

8. The multilayer film of claim 1 wherein said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc and a melt index, I 2 , of from about 0.5 to about 5 g/10 minutes.

9. The multilayer film of claim 1 wherein said HI polyethylene has a melt index, I 2 , of from about 0.5 to about 2.0 g/10 minutes and wherein said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc and a melt index, I 2 , of from about 0.5 to about 5 g/10 minutes.

10. The multilayer film of claim 1 wherein said LD polyethylene has a melt index, I 2 , of from about 0.2 to about 10 g/10 minutes.

11. The multilayer film of claim 1 wherein said LD polyethylene has a melt index, I 2 , of from about 0.3 to about 5 g/10 minutes.

12. The multilayer film of claim 1 wherein said LD polyethylene has a density of from about 0.915 to about 0.930 g/cc.

13. The multilayer film of claim 1 wherein said LD polyethylene has a melt index, I 2 , of from about 0.3 to about 5 g/10 minutes and a density of from about 0.915 to about 0.930 g/cc.

14. The multilayer film of claim 1 wherein said HI polyethylene has a melt index, I 2 , of from about 0.5 to about 2.0 g/10 minutes and wherein said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc and a melt index, I 2 , of from about 0.5 to about 5 g/10 minutes and wherein said LD polyethylene has a melt index, I 2 , of from about 0.3 to about 5 g/10 minutes and a density of from about 0.915 to about 0.930 g/cc.

15. A multilayer film from about 1 to about 6 mils in total thickness and having a normalized impact strength of at least about 300 grams, the film comprising an HI polyethylene; and a Z/N polyethylene; and an LD polyethylene; said film comprising
A) a skin layer consisting essentially of said HI polyethylene; and
B) a core layer consisting essentially of a blend of said Z/N polyethylene and said LD polyethylene,

wherein
i) said HI polyethylene is prepared with a metallocene catalyst and has a density in the range of from 0.915 to about 0.930 g/cc, a melt index, I 2 , of from about 0.5 to about 2.0 g/10 minutes, an SCBDI of from about 70 to about 100 and is present in the range from about 30 to about 55 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film; and
ii) said LD polyethylene has a melt index, I 2 , of from about 0.3 to about 5 g/10 minutes and a density of from about 0.915 to about 0.930 g/cc and is present in the range from about 5 to about 20 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film; and
iii) said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc and a melt index, I 2 , of from about 0.5 to about 5 g/10 minutes.

16. The multilayer film of claim 15 , wherein the total film thickness is less than about 2 mils and wherein the core layer is at least about 0.5 mils thick.

17. The multilayer film of claim 15 , wherein the core layer contains from about 40 to about 70 weight % of the total amount of polyethylene based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene.

18. A polyethylene package comprising a multilayer film having a normalized impact strength of at least about 300 grams, the film comprising an HI polyethylene; and a Z/N polyethylene; and an LD polyethylene; said film comprising
A) a skin layer consisting essentially of said HI polyethylene; and
B) a core layer consisting essentially of a blend of said Z/N polyethylene and said LD polyethylene,

wherein
i) said HI polyethylene is prepared with a metallocene catalyst and has a density in the range of from 0.915 to about 0.930 g/cc, a melt index, I 2 , of from about 0.5 to about 2.0 g/10 minutes, an SCBDI of from about 70 to about 100 and is present in the range from about 30 to about 55 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film; and
ii) said LD polyethylene has a melt index, I 2 , of from about 0.3 to about 5 g/10 minutes and a density of from about 0.915 to about 0.930 g/cc and is present in the range from about 5 to about 20 weight %, based on the combined weight of said HI polyethylene plus said Z/N polyethylene plus said LD polyethylene that is contained in said multilayer film; and
iii) said Z/N polyethylene has a density of from about 0.915 to about 0.960 g/cc and a melt index, I2, of from about 0.5 to about 5 g/10 minutes.

Assignees

• Nova Chem Int Sa

Inventors

• Borse Nitin
• Aubee Norman Dorien Joseph
• Chisholm P Scott
• Goyal Shivendra Kumar
• Marler Jamie Michael

Classifications

• B32B2307/72

  Density · CPC title

• B32B2439/70

  Food packaging · CPC title

• B29C2948/92647

  Thickness · CPC title

• B32B2307/558

  Impact strength, toughness · CPC title

• B29C48/10

  flexible, e.g. blown foils · CPC title