Processes for collation shrink packaging with a thermally insulating film

Patent metadata

Field	Value
Publication number	US-10273029-B2
Application number	US-201615566154-A
Country	US
Kind code	B2
Filing date	Apr 28, 2016
Priority date	May 4, 2015
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

This invention relates to processes for collation shrink packaging of one or more items with a thermally insulating film, to films for such processes, to packages so made, and to methods for extruding such films. The one or more items packaged may be cans, bottles, pouches and other carriers of liquid or solids.

First claim

What is claimed is:

1. Process for collation shrink packaging of one or more items including:
i) wrapping one or more items to be packaged in a coextruded multi-layer collation shrink film which comprises:
A) a layer A with density reducing bubbles formed in LDPE or optionally in a blend of LDPE with a linear polyethylene, said blend of LDPE comprising at least 50 wt % of LDPE, said LDPE or blend of LDPE blend having an MI as determined according to ASTM-D-1238 at 190° C. of from 0.1 to 2 g/10 min;
B) a polyethylene shrink layer B comprising at least 75 wt % of an LLDPE, said LLDPE having an MSF of more than 0.003 Newton, a density of from 0.915 g/cm 3 to 0.940 g/cm 3 and an MI of from 0.05 to 10 g/10 min; and
ii) heating the one or more wrapped items so that the film grips the one or more wrapped items by shrinkage while increasing in thickness to form a thermally insulating wrap around the items packaged.

2. Process according to claim 1 , wherein the LLDPE in shrink layer B has a relaxation time as calculated from determinations of shear rate and viscosity at 190° C., using the Cross model of at least 0.1 second.

3. Process according to claim 1 , wherein the LDPE in the reduced density layer A has a relaxation time as calculated from determinations of shear rate and viscosity at 190° C., using the Cross model, of at least 10 seconds.

4. Process according to claim 1 , wherein the MSF measured as described herein of the LDPE in the reduced density layer A and the LLDPE in shrink layer B differ by at least 0.01 Newton.

5. Process according to claim 1 , wherein the LLDPE in shrink layer B has been produced by a polymerization process using a metallocene catalyst.

6. Process according to claim 1 , wherein the MI of shrink layer B is at least 0.2 g/10 min and/or 1 g/10 min or less.

7. Process according to claim 1 , wherein the coextruded multi-layer film is biaxially oriented and upon heating in step (ii), shrinks by at least 20% in both machine and transverse directions when submitted to a temperature of 190° C. for 10 seconds.

8. Process according to claim 1 , wherein, after step ii), layer A has a density of from 0.6 to 0.2 g/cm 3 .

9. Process according to claim 1 , wherein the layer A comprises at least 70 wt % LDPE and optionally no more than to 10 wt % of linear polyethylene having a relaxation time of less than 1 second.

10. Process according claim 1 , wherein the layers A and B are adjacent, without any intervening film layer and preferably form a B/A/B structure.

11. Process according to claim 1 , wherein the film used in step (i) is made using a blown film extruder by:
I) admixing a chemical blowing agent, preferably an endothermic chemical blowing agent, into the polymer used to form layer A;
II) extruding layers A and B;
III) stretching the extruded film at a draw down ratio of from 2 to 20 and a blow up ratio of from 2.0 to 4.5 by inflation; and
IV) taking up the film.

12. Process according to claim 1 , wherein the one or more items is a single item.

13. Process according to claim 1 , wherein the layer B comprises at least 90 wt % of the LLDPE having an MSF of more than 0.003 Newton.

14. Process according to claim 1 , wherein a layer C lies adjacent to both sides of the reduced density layer A.

15. Process according to claim 14 , wherein the film has a C/A/B/A/C structure and layers C form the film surface and comprise linear low density polyethylene having a relaxation time as calculated from determinations of shear rate and viscosity at 190° C. of less than 1 second and/or an MSF of less than 0.003 Newton.

16. Process according to claim 1 , wherein the film is printed with text or graphics after step ii).

17. Process according to claim 16 , wherein the printed film is a packaging label for the one or more items.

18. A collation pack comprising one or more articles and a film bundling the one or more articles, said film having been heat shrunk into position by the process according to claim 1 .

Assignees

• Exxonmobil Chemical Patents Inc

Inventors

• Vinck Michael J
• Timol Mohamed

Classifications

• B65B21/245

  in flexible wrappers, e.g. foils (B65B21/26 takes precedence) · CPC title

• B29C48/0018

  combined with shaping by orienting, stretching or shrinking, e.g. film blowing (B29C48/0017 takes precedence) · CPC title

• B29C63/40

  using sheet or web-like material · CPC title

• B32B2307/54

  Yield strength; Tensile strength · CPC title

• B65D81/3897

  formed of different materials, e.g. laminated or foam filling between walls · CPC title