Patent ID: 8640928

Claim:
A self-closing valve adapted to be arranged in a closure of a container, said self-closing valve being made of a resilient material and comprising a dome shaped central portion having a peripheral surface and having in an unloaded state a concave outer side and a convex inner side, wherein the surface at the concave outer side of the dome shaped central portion has in the unloaded state a constant radius of curvature seen in cross section, and wherein the inner side of the central portion, has a flat central surface portion and a conical outer surface portion which surrounds the flat surface portion, said dome shaped central portion being provided with at least one through slit, said slit being closed in said unloaded state, and said dome shaped central portion being deformable by pressure to a shape in which the slit is open, said self-closing valve further comprising a skirt which extends from the peripheral surface of the central portion in line with said peripheral surface such that an outer surface of the skirt and said peripheral surface are flush, said skin having an outwardly extending flange at an end remote from said peripheral surface of the central portion, wherein an annular groove is present at a transition between said skirt and said conical surface portion, said groove extending from an outer edge of the conical surface portion of the dome shaped central portion to the skirt.