Breathable rupturable closure for a flexible container

Abstract

A rupturable closure for use with a flexible container that is especially suited for pouring viscous fluids such as motor oil. The closure is secured to the pouring spout or other dispensing opening of the container and retains the viscous fluid in the container as the container is brought into inverted position for pouring. Notwithstanding the ability of the closure to hold in the viscous fluid, the closure also allows the closure to breathe when the cap is removed so as to relieve small variations in pressure as the flexible container is first grasped for pouring and thereby prevent premature rupture of the closure before or as the container is inverted for pouring. Such a closure includes a membrane secured over the dispensing opening of the container. The membrane has a small primary vent orifice in the region over the dispensing opening that is sized to permit the membrane to breathe. The membrane also has three or more part lines terminating in the primary vent orifice along which the membrane parts when the flexible bottle is squeezed. The part lines extend outward from the vent orifice substantially to the periphery of the dispensing opening. Each of the part lines is interrupted by a small connecting element across the line proximate to the primary vent orifice. The primary vent orifice and the connecting elements are of a size, and the connecting elements are positioned sufficiently close to the primary vent orifice, such that the membrane will contain the viscous fluid within the container when the container is brought into inverted position for pouring, yet the connecting elements will break away and the membrane will separate along the part lines when the flexible container is squeezed, thereby enabling the viscous fluid to flow through the dispensing opening.