Abstract: The present invention relates to a sheetlike composite comprising, as mutually superposed layers, a) a carrier layer, b) a barrier layer, and c) an inner polymer layer, wherein the sheetlike composite has a multitude of groove lines arranged and configured such that, by folding the sheetlike composite along the groove lines and joining seam areas of the sheetlike composite thereby obtaining seams, a closed container is obtainable, wherein the closed container has a roof area, wherein a first portion of the groove lines of the multitude of groove lines at least partly forms a circumference of a first part-area of the roof area, wherein the groove lines of the first portion, relative to the first part-area of the roof area, have at least partly convex curvature, wherein the first part-area of the roof area has a first length in a longitudinal direction and has a second length in a circumferential direction at right angles to the longitudinal direction, wherein a ratio of the first length to the second lengt