Crown cork for a vessel for holding beverages or foods that has a mouth to be closed with the crown cork, having a sealing insert arranged in the crown cork such that it sealingly closes the mouth when the crown cork is mounted on the vessel, where the crown cork including the sealing insert contains no halogen-containing materials, where the sheet metal used for the crown cork has a thickness of 0.10-0.19 mm, wherein the sealing insert contains at least twenty percent by weight, based on the total weight of the sealing insert, of at least one, preferably fully hydrogenated, styrene triblock copolymer, especially styrene-ethylene-butadiene-styrene copolymer (SEBS), SEEPS and/or SEPS, or a mixture of two or more of these copolymers.