Container with thermally fused double-seamed or crimp-seamed metal end

Patent metadata

Field	Value
Publication number	US-9988179-B2
Application number	US-201715698143-A
Country	US
Kind code	B2
Filing date	Sep 7, 2017
Priority date	Sep 2, 2011
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A container includes a metal end applied and sealed to an all-thermoplastic container body by a crimp-seaming or double-seaming operation. The metal end has an outer curl joined to a chuck wall that extends down from the curl. One or both of the inner surface of the container side wall and the outer surface of the chuck wall has/have a heat-sealable material thereon. The metal end is crimp-seamed or double-seamed to the container body and the heat-sealable material(s) are heated to soften or melt such that the interface between the chuck wall and the side wall is fused. The interface is oriented along a direction relative to internal pressure exerted on the metal end such that stress on the interface caused by the internal pressure is predominantly shear stress.

First claim

What is claimed is:

1. A method for making a container, comprising the steps of:
providing a container body having a side wall extending about a container body axis, the side wall having a lower end and an upper end, the upper end defining an upper edge that extends about a top opening of the container body, the side wall having an inner surface and an outer surface;
providing a metal end for closing the top opening of the container body, the metal end having at least a metal layer and comprising a central portion and an outer peripheral portion extending generally radially outwardly from the central portion and extending circumferentially about the central portion, the peripheral portion having a radially outer part and a radially inner part, a first heat-sealable material being present on one of (a) a lower surface of at least the peripheral portion of the metal end and (b) the inner surface of the side wall adjacent the upper end thereof, the radially outer part of the peripheral portion defining a curl, the radially inner part of the peripheral portion defining a chuck wall that extends generally downward from the curl and has a radially outer surface;
applying the metal end to the container body such that the metal end closes the top opening and the radially outer surface of the chuck wall and the inner surface of the side wall have an intimately contacting interface therebetween;
forming a seam connecting the metal end to the upper end of the side wall, the seam being formed by interlocking the curl of the metal end with the upper end of the side wall via a folded peripheral edge of the curl and the side wall;
after formation of the seam is completed, heating the first heat-sealable material to a temperature sufficient to cause the first heat-sealable material in contact with the radially outer surface of the chuck wall and the inner surface of the side wall to be softened or melted; and
allowing the first heat-sealable material to cool and harden such that the interface between the chuck wall and the side wall is fused, the interface being oriented along a direction such that stress on the interface caused by internal pressure inside the container exerted on the metal end is predominantly shear stress.

2. The method of claim 1 , wherein the step of forming a seam comprises forming a crimp seam.

3. The method of claim 1 , further comprising providing a second heat-sealable material present on the other of (a) the lower surface of at least the peripheral portion of the metal end and (b) the inner surface of the side wall adjacent the upper end thereof, and wherein:
the second heat-sealable material and the first heat-sealable material are placed in contact with each other at the interface between the chuck wall and the side wall, and the first and second heat-sealable materials are heated to a temperature sufficient to cause the first and second heat-sealable materials to be softened or melted and to flow together, after which cooling of the first and second heat-sealable materials is allowed to occur so as to fuse the chuck wall to the inner surface of the side wall.

4. The method of claim 3 , wherein the second heat-sealable material and the first heat-sealable material are thermally fused together in the seam as well.

5. The method of claim 1 , further comprising the steps of:
filling the container with a food product prior to the step of applying the metal end to the container body; and
after the interface between the chuck wall and the side wall is fused, retorting the container.

6. The method of claim 5 , wherein during the retorting step the container body is radially unconstrained such that the container body is allowed to expand radially as internal pressure is exerted on the side wall, thereby reducing pressure build-up within the container and consequently the stress placed upon the side wall and metal end.

7. The method of claim 6 , wherein the container body is free of any special expansion panels, whereby the radial expansion of the container body occurs substantially uniformly about a circumference of the container body.

8. The method of claim 1 , wherein the chuck wall extends at a non-zero acute angle relative to a longitudinal axis of the container body and is configured such that a lower end of the chuck wall is smaller in diameter than the inner surface of the side wall, while an upper end of the chuck wall is larger in diameter than the inner surface of the side wall, and wherein the step of applying the metal end to the container body results in the side wall of the container body moving relatively upward from the lower end to the upper end of the chuck wall such that an interference fit is created between the chuck wall and the side wall, thereby creating said intimately contacting interface therebetween.

9. The method of claim 8 , wherein during the heating step there is a substantial absence of external pressure exerted on the chuck wall and side wall, pressure between the chuck wall and side wall coming rather from said interference fit.

10. A method for packaging and retort-processing a food product, comprising the steps of:
providing a container assembly that includes a container body having a side wall and further includes an end wall closing a lower end of the container body, an opposite upper end of the container body being open;
providing a metal end having at least a metal layer and comprising a central portion and an outer peripheral portion extending generally radially outwardly from the central portion and extending circumferentially about the central portion, the peripheral portion having a curl and a chuck wall that extends generally downward and radially inwardly from the curl;
providing at least one heat-sealable material on at least one of (a) a lower surface of the peripheral portion of the metal end and (b) an inner surface of the container body adjacent the upper end thereof;
placing the food product into the container assembly through the open end of the container body;
forming a crimp seam between the metal end onto the container body to close the open end thereof, the forming step causing the side wall of the container body to be compressed between the chuck wall on an inner side of the side wall and a permanently deformed portion of the metal end formed by deforming the curl on an outer side of the side wall;
thermally fusing the metal end to the container body by causing the heat-sealable material(s) to be melted where the metal end compresses the side wall and then allowing the melted heat-sealable material(s) to cool and harden, thereby completing a filled container; and
retort-processing the filled container to sterilize the food product and interior of the container.

11. The method of claim 10 , wherein during the retort-processing step the container body is radially unconstrained such that the container body is allowed to expand radially as internal pressure is exerted on the side wall, thereby reducing pressure build-up within the container and consequently the stress placed upon the side wall and metal end.

Assignees

• Sonoco Dev Inc

Inventors

• Price Trevor
• Morin Jeremy

Classifications

• B65B55/02

  Sterilising, e.g. of complete packages · CPC title

• A23B7/0056

  with packages · CPC title

• A23L3/02

  Human Necessities · mapped topic

• B65B7/285

  by deformation of the closure · CPC title

• B65B3/02

  Machines characterised by the incorporation of means for making the containers or receptacles · CPC title