Importance

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Abstract

A method of making a one-way gas release valve for releasing gas pressure from within a coffee container comprises pre-oiling a relatively narrow dry strap of flexible material and laminating the pre-oiled dry strap between relatively wide ribbons of base and cover material with the dry strap overlying spaced vent patterns in the base material. Alternatively, the base material may be pre-oiled or both the base material and the dry strap may be pre-oiled. The dry strap and base may be made of PET and the cover may be made of mPET. Gas release valves are then die cut from the resulting web with each valve containing a vent pattern. Pre-oiling of the dry strap and/or the base can be accomplished through a roll metered process to insure that the oil is applied in precise amounts and with consistent thickness and coverage. Since the oil is applied during fabrication of the gas release valves, the vent patterns in the base can be configured to function also as a filter to prevent coffee grinds from migrating into the valve.

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First Claim