Cap liner

Abstract

A venting cap liner has a bottom surface facing an annular bottle lip surrounding an open top end of a bottle neck, and a top surface facing an inner top wall of a closure cap, the liner being configured to provide a gas-permeable but liquid-impervious seal that is resistant to rupture when a downwardly directed torque is applied in a thickness direction of the liner body to compression seal the liner body between the annular bottle lip and the inner top wall of the cap. In one embodiment, a two-layer liner body includes a bottom layer of a mineral-filler based polyolefin (MFP) material that is substantially liquid-impervious while allowing release of gas evolving from a liquid product in the bottle, and a top layer comprising a polyolefin (PO) foam material having a grooved upper surface with channels facing the inner top wall of the cap, and a plurality of through-holes extending in a thickness direction, wherein the layers of the liner body allow gas, evolving from a product in the sealed bottle, to permeate out the open top end of the bottle neck, through the MFP material, the through-holes of the PO foam material and along the channels to flow out of an area between an exterior surface of the bottle neck and a peripheral cap flange.