Preform and container comprising reinforcing elements

A plastic perform for a container, comprising at least one elongated structure selected from the group consisting of an elongated protrusion and an elongated groove, the elongated structure extending in a direction parallel to the longitudinal axis of the preform and provided on the inner side of a side wall of the preform, the thickness of the side wall of the preform constantly varies along the horizontal direction of the side wall of the preform and is constant along the longitudinal axis of the preform, at the elongated protrusions the side wall of the preform has a maximum wall thickness d1 in the horizontal direction, in the elongated grooves the side wall of the preform has a minimum wall thickness d0 in the horizontal direction, and the thickness of the side wall in the horizontal direction is constantly increasing or decreasing between the minimum wall thickness d0 and the maximum wall thickness d1.