The application generally relates to containers capable of maintaining a vacuum within the container after the container is sealed. The application relates more specifically to food containers capable of maintaining a vacuum with features to protect the integrity of the sealed container and/or to provide improved container structure.
Containers are used to store a variety of materials and objects. Some types of containers are used to store perishable material such as organic material, solid food, food having a liquid component, and liquids. These containers must often meet a variety of requirements depending on their intended use. For example, some containers must be able to withstand acidity of certain levels such that the container's intended contents do not compromise the container. Other containers must be able to successfully store liquid such that manipulation of the container during shipping and typical use do not cause the container to deform, break an airtight seal, and/or leak the container's contents. Yet other containers must be able to withstand food cooking processes involving the container. Some containers must meet all of the aforementioned requirements.
One type of food and beverage container is provided with a closure that is affixed to the container primarily by the pressure differential between external atmospheric pressure and a lower internal pressure. Other types of closures (e.g., twist on/off closures, snap on/twist off closures, etc.) are affixed to the container mechanically. Another type of food and beverage container is provided with a can end affixed to the container by folding or crimping the material of the can end to the container body. Containers that maintain a vacuum after the container is sealed are vulnerable to impacts during processing, labeling, and transport. Such impacts may break the hermetic vacuum seal of the container which may cause leakage and may expose contents of the container to spoilage.
In addition, food and beverage storage containers are subjected to a variety of forces during manufacture, filling and processing, sales, and transport. Containers must be strong enough to resist these forces without deformation. Further, containers with an internal vacuum must be strong enough to resist compressive deformation by the external atmospheric pressure. One solution is to make the container material thicker. However, this approach increases the container weight and the cost of raw materials.
Some containers are filled with hot, pre-cooked food then sealed for later consumption, commonly referred to as a “hot fill process.” As the contents of the container cool, a vacuum develops inside the container. The resulting vacuum may partially or completely secure the closure to the body of the container. Foods packed with a hot fill process often have certain advantages. For example, end-users often appreciate pre-cooked food contents as preparation times are often shorter and more convenient.
Other containers are filled with uncooked food, the container is sealed, and the food is cooked to the point of being commercially sterilized or “shelf stable” while sealed within the container. This process is commonly called a thermal process. Also commonly, the required heat for the process is delivered by a pressurized device, or retort. Thermal processes also have certain advantages. First, the resulting shelf-stable package offers long-term storage of food in a hermetically sealed container. Second, cooking the food inside the container commercially sterilizes the food and the container at the same time.
Containers used with thermal processes often use can ends that require the use of a tool to open. For example, some containers suitable for use with thermal processes are metal cans having an end designed for use with a can-opener. Other containers suitable for use with thermal retort processes are containers having “pop-tops”, “pull tops”, convenience ends, or convenience lids having a tab or ring that aids in removal of the can end. Thermal retort processes present challenges to the design and manufacture of vacuum containing containers. For example, the pressure and temperature rigors of the thermal retort process may compromise the seal. In addition, differences in internal container pressure and external pressure during the thermal retort process may cause an unsecured vacuum sealable lid to separate from the container body.
Therefore, it would be desirable to provide a container capable of maintaining a vacuum having one or more protective features. Further, it would be desirable to provide a vacuumized container with protective features that is suitable for use with hot fill and/or thermal processes.