Cups for holding ingredients for drinks

Claim 1

A double-walled container capable of nesting and interlocking with another identically formed container with a space for storage of a concentrate between the bottom walls of the containers when nested and interlocked, said double-walled container comprising an inner member secured within an outer member, each member being formed of a seamless thin-walled plastics-material and each member comprising a bottom wall and an integral side wall extending generally upwardly and outwardly to the upper end thereof, the inner member including an upper sealing surface spaced from the bottom wall thereof a distance sufficient to provide a space therebelow for storage of a concentrate, the outer member including a lower sealing surface at the junction of the bottom wall and side wall of said outer member, said upper and lower sealing surfaces being inclined to the axis of said container in a direction upwardly and outwardly of said container in a frusto-conical shape and cooperating to make a seal when two such containers are nested, a downwardly facing holDing surface formed on said inner member to extend radially inwardly thereof, an upwardly facing holding surface formed in said outer member to extend radially inwardly thereof, said downwardly and upwardly facing holding surfaces formed in the side walls of said inner and outer members above the midheight of said container and with the vertical distance between said downwardly facing holding surface and said upwardly facing sealing surface of said inner member being sufficiently less than the distance between said upwardly facing holding surface and said lower sealing surface of said outer member to produce axial and hoop stresses in the side wall of an inner member between the holding and sealing surfaces thereof of one container and in the side wall of the outer member between the holding and sealing surfaces thereof of another of said containers when nested in said one container with said holding surfaces overlapping each other to interlock said another and said one containers.