Polyethylene laminates for use in flexible packaging materials

Patent metadata

Field	Value
Publication number	US-11203193-B2
Application number	US-201816500003-A
Country	US
Kind code	B2
Filing date	Apr 4, 2018
Priority date	Apr 7, 2017
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

Embodiments of a laminate structure for use in flexible packaging comprise a sealant film comprising ethylene-based polymer, and a multilayer polyethylene print film laminated to the sealant film. The print film comprises at least 3 layers and has an overall thickness from 15 to 30 μm. The print film comprises a middle layer, an inner layer disposed between sealant film and the middle layer, and an outer layer, wherein the middle layer comprises at least 90% by weight high density polyethylene (HDPE) polymer having a density from 0.950 to 0.965 g/cc. The inner layer and the outer layer comprise linear low density polyethylene (LLDPE) having a density from 0.925 to 0.965 g/cc. The laminate structure yields desired optical and mechanical properties coupled with recyclability and improved printing efficiency, while maintaining these low thicknesses for the print film.

First claim

The invention claimed is:

1. A laminate structure comprising:
a sealant film comprising ethylene-based polymer;
a print film laminated to the sealant film, the print film comprising at least 3 layers and having an overall thickness from 15 to less than 25 μm, where the print film comprises a middle layer, an inner layer disposed between the sealant film and the middle layer, and an outer layer, wherein
the middle layer comprises at least 90% by weight high density polyethylene (HDPE) having a density from 0.950 to 0.965 g/cc and a melt index (I 2 ) from 0.1 to 20 g/10 min, wherein 12 is measured according to ASTM D1238 at 190° C. and 2.16 kg load;
the inner layer comprises linear low density polyethylene (LLDPE) having a density from 0.935 to 0.965 g/cc and a melt index (I 2 ) from 0.1 to 20 g/10 min; and
the outer layer comprises linear low density polyethylene (LLDPE) having a density from 0.935 to 0.965 g/cc and a melt index (I 2 ) from 0.1 to 20 g/10 min;

wherein the laminate structure exhibits a gloss value of at least 40%, wherein gloss is measured at 45° according to ASTM D2457.

2. The laminate structure of claim 1 , wherein the middle layer of the print film comprises 100% by wt. HDPE.

3. The laminate structure of claim 1 , wherein the density of the middle layer of the print film is from 0.960 to 0.965 g/cc and the melt index (I 2 ) from 0.5 to 1.0 g/10 min.

4. The laminate structure of claim 1 , wherein the inner layer, the outer layer, or both of the print film further comprise low density polyethylene (LDPE) having an MWD from 3 to 10 and a melt index (I 2 ) from 0.5 to 5 g/10 min, wherein the MWD is defined as Mw/Mn, wherein Mw is weight average molecular weight and Mn is number average molecular weight.

5. The laminate structure of claim 1 , wherein the inner layer, the outer layer, or both of the print film comprises at least 50 wt. % LLDPE.

6. The laminate structure of claim 1 , wherein the density of the LLDPE in the inner layer, the outer layer, or both of the print film is from 0.935 to 0.940 g/cc and the melt index (I 2 ) from 0.5 to 1.5 g/10 min.

7. The laminate structure of claim 4 , wherein the inner layer, the outer layer, or both of the print film include from 60 to 95% by wt. LLDPE and 5 to 40% by wt. LDPE.

8. The laminate structure of claim 1 , wherein the ethylene-based polymer of the sealant film is an ethylene-α-olefin interpolymer, where the α-olefin comprises one or more C 3 -C 12 olefins.

9. The laminate structure of claim 1 , wherein the ethylene-based polymer of the sealant film is an ethylene-α-olefin interpolymer having a density from 0.900 to 0.925 g/cc and a melt index (I 2 ) from 0.1 to 20 g/10 min.

10. The laminate structure of claim 1 , wherein the sealant film comprises a polyolefin plastomer, LDPE, or both.

11. The laminate structure of claim 1 , wherein the print film, the sealant film, or both are each independently blown films, or cast films.

12. The laminate structure of claim 1 , wherein the overall thickness of the print film is less than 20 μm.

13. The laminate structure of claim 1 , wherein the print film defines a ratio by layer thickness of 1:3:1 for the inner layer, middle layer, and outer layer, respectively.

14. An article comprising the laminate structure of claim 1 .

15. The article of claim 14 , wherein the article is a flexible packaging material.

Assignees

• Dow Global Technologies Llc
• Dow Global Tech

Inventors

• Mishra Shashibhushan
• Laddha Sachin

Classifications

• B32B7/02

  Physical, chemical or physicochemical properties · CPC title

• B32B2439/70

  Food packaging · CPC title

• B32B2553/026

  Bubble films · CPC title

• B32B2307/738

  Thermoformability · CPC title

• B32B27/08 Primary

  of synthetic resin · CPC title