1. Field of the Invention
The present invention relates to a foldable cold box which can maintain low temperature for a certain period, and a delivery method using the cold box.
2. Description of Related Art
A thermally insulating cold box is used for storing and transporting goods such as frozen foods or refrigerated foods that are required to maintain its frozen or refrigerated state.
As a related art cold box, an integrally molded foamed polystyrene box is generally known. Because this foamed polystyrene box is integrally molded, it provides excellent sealing property and thermal insulation. However, since the integrally molded foamed polystyrene box cannot be folded, it becomes bulky when it is empty.
As another related art cold box, JP-A-2004-189242 describes a foldable cold box. This cold box has a structure in which a plurality of thermal insulation boards are combined such that, when there are no goods to be placed therein, the cold box is folded in a compact form so as to facilitate its handling. However, because a gap is created between the adjacent thermal insulation boards in order to obtain the foldable structure, a high thermal insulation cannot be expected.
Further, in many cases, cold boxes are roughly handled. Therefore, high strength is required for repetitive use. However, the foamed polystyrene boards may not have sufficient strength. As for the cold box described in JP-A-2004-189242, the strength is sacrificed due to the foldable structure.
Further, when delivering goods using the cold box described in JP-A-2004-189242, a vehicle having a refrigerating function is essential in order to compensate for deteriorated thermal insulation performance resulting from its foldable structure. Moreover, in a delivery center, goods are generally placed inside the cold box on top of one another. However, a flap lid of the cold box described in JP-A-2004-189242 is provided on a lateral side of the cold box, which may not fit for efficient packing work.