Pressure container with differential vacuum panels

Abstract

A plastic container (1) has a first set of flex panels (2) and a second set of flex panels (3) at least one set being adapted to react to pressure changes within the container to a different degree which can be achieved by different curvature and/or size and/or different distance from a central longitudinal axis of the container. At least one of the panels has at least two different extents of curvature. In some embodiments one or more of the panels may be flat.

Description

FIELD OF THE INVENTION[0001]The present invention relates to hot-fillable containers. More particularly, the present invention relates to hot-fillable containers having collapse panels.BACKGROUND OF THE INVENTION[0002]‘Hot-Fill’ applications impose significant and complex mechanical stress on a container structure due to thermal stress, hydraulic pressure upon filling and immediately after capping, and vacuum pressure as the fluid cools.[0003]Thermal stress is applied to the walls of the container upon introduction of hot fluid. The hot fluid will cause the container walls to soften and then shrink unevenly, causing distortion of the container. The polyester must therefore be heat-treated to induce molecular changes resulting in a container that exhibits thermal stability.[0004]Pressure and stress act upon the side walls of a heat resistant container during the filling process, and for a significant period of time thereafter. When the container is filled with hot liquid and sealed, ...

AI Technical Summary

Benefits of technology

[0017]The present invention provides according to one aspect a plastic container, having a body portion including a sidewall, wherein said body portion includes; a first controlled deflection flex panel on one sidewall portion and a second controlled deflection flex panel on a second sidewall portion, at least one of said controlled deflection flex panels having at least two different extents of outward curvature, said first and second flex panels being adapted to react to pressure changes within the container to a different degree. By way of example, a container having four controlled deflection flex panels may be disposed in two pairs on symmetrically opposing sidewalls

Problems solved by technology

‘Hot-Fill’ applications impose significant and complex mechanical stress on a container structure due to thermal stress, hydraulic pressure upon filling and immediately after capping, and vacuum pressure as the fluid cools.

The hot fluid will cause the container walls to soften and then shrink unevenly, causing distortion of the container.

As the liquid, and the air headspace under the cap, subsequently cool, thermal contraction results in partial evacuation of the container.

The vacuum created by this cooling tends to mechanically deform the container walls.

The amount of ‘flex’ available in each panel is limited, however, and as the limit is approached there is an increased amount of force that is transferred to the side walls.

This causes stress to be placed on the container side wall.

There is a forced outward movement of the heat panels, which can result in a barrelling of the container.

With the panel being generally flat, however, the amount of movement is limited

Images