Foldable carton

A collapsible carton which is formed from a blank which when formed from the blank is capable of being folded between a folded flat condition and an erect condition whereby when in the erect condition the carton has a floor, two opposed end panels and two opposed side panels to define a liquid tight generally rectangular closed prismatic shaped space, the end panels and the side panels having substantially the same height, wherein the floor panel is formed of a single panel and the junction between the floor and each of the end panels and each of the side panel is defined by a closed fold line therebetween, the end panels each having a pair of first diagonal fold lines extending from the junction between the sides of the floor and the sides of the respective end panel and converging to terminate at a transverse central axis of the end panel, said first diagonal fold lines being substantially perpendicular to each other, said end panels have a height being equal to or greater than the termination of the diagonals, wherein the floor is provided with a first central fold line which is substantially centrally located and which extends between the end panels and is adapted to permit the floor to fold inwardly into the space about the first central fold line while the first diagonal fold lines fold, said end panels being provided with a second central fold line extending centrally from the floor to an opposed edge of the end panel, each end panel and each side panel formed with an extension panel, said extension panels being of substantially the same height and being hingedly supported from their respective end or side panel, wherein in the erected carton the abutting edges of adjacent extension panels are defined by a closed fold line, the extension panel of each end panel being formed with a pair of second diagonal fold lines extending between the junction between the end panel and the extension panel at the sides thereof and converging to terminate at the junction of the second fold line with the outer edge of the extension panel, whereby on the erection of the carton the extension panels of each end panel fold about the second diagonal fold lines and the junction with the end panels to an intermediate position where the extension panels of the side panels fold over the space to close the space and lie parallel to said floor panel, the extension panels of the end panels being fiber foldable about their junction with their respective end panels to lie a self locked position parallel to and adjacent their respective end panels on an outside of said space at which self locked position a biasing force is applied to the extension panels of the end panels in a direction of their respective end panels.