Container with vacuum accommodating end

DETAILED DESCRIPTION The present invention proposes a system for the accommodation of an internally generated vacuum in a tubular container having a body, preferably of composite construction to take advantage of the particular economies associated therewith, and metal end closures of conventional material, thickness and weight.
Composite containers, well known as an economical substitute for the more expensive metal and glass containers, have generally been considered less than completely satisfactory for accommodating hot fillings, such as juices or the like wherein, upon the cooling of the product within the sealed container, substantial internal negative pressures are generated.
Such pressures, in turn, give rise to problems with regard to the integrity of the container.
Attempts to overcome these problems have included the use of thin readily flexed caps, the provision of expansion seams within the inner liner of the container, and reliance on external mechanical means to inwardly flex a cap subsequent to the filling of the container and prior to cooling.
However, all of these known methods also incorporate inherent problems.
The system of the present invention is unique in providing for the utilization of a composite container, with opposed metal end caps, wherein the container body can be of conventional multi-ply paperboard construction, and wherein the closure ends are metal and of conventional thickness and weight.
In this manner, all of the desirable features normally arising from the use of conventional metal ends, such as a rigidification and strengthening of the composite container and the like, are achieved.
Further, inasmuch as a closure of conventional thickness is utilized, a proper and positive hermetic sealing of the end of the composite body is easily affected.
A metal end of conventional thickness and weight, while incorporating substantial advantages, will not, under normal circumstances, properly flex under an internally generated negative pressure.
To the contrary, it is much more likely that the composite body, or liner thereof, will, at some point, destruct prior to an effective flexing of the metal end