1. Field of the Invention
This invention relates generally to the field of packaging, and more specifically to the field of hot fill type plastic containers.
2. Description of the Related Technology
Hot fill containers are designed to be used with the conventional hot fill process in which a liquid product such as fruit juice is introduced into the container while warm or hot, as appropriate, for sanitary packaging of the product.
Most hot fill type containers are fabricated from polyethylene terephthalate, which is otherwise known as PET. PET possesses excellent characteristics for such containers, but PET resin is relatively expensive. Accordingly, a PET container design that reduces the amount of material that is used without sacrificing performance will provide a significant competitive advantage within the packaging industry.
After filling, such containers undergo significant volumetric shrinkage as a result of the cooling of the product within the sealed container. Hot fill type containers accordingly must be designed to have the capability of accommodating such shrinkage. Typically this has been done by incorporating one or more recessed, concave vacuum panels into the side wall of the container that are designed to flex inwardly as the volume of the product within the container decreases as a result of cooling. In other containers, vacuum uptake is achieved by flat, non-recessed panels that are designed to flex in order to accommodate the volumetric shrinkage.
Ribs or grooves are sometimes provided in order to control the flexure of the side wall during the hot fill process, as well as for imparting rigidity to the container when it is being gripped by a consumer. In certain containers that have flat vacuum panels, the presence of horizontal ribs has been found to contribute to creasing of the vacuum panel during vacuum uptake conditions.
A need has existed for an improved hot fill container design that provides adequate vacuum uptake during the hot fill process, is resistant to creasing during vacuum uptake conditions and that imparts sufficient rigidity to permit a consumer to grip the container without excessive sidewall deflection.