Today in 1964, US Patent 3147874 A was issued, an invention of Donald D. Hundt and Edward W. Merrill, for their “Seal For Crown Closures.” There’s no Abstract, although in the description it includes these claims:
This invention relates to seals for crown, screw, lug and similar caps or closures. It is more particularly concerned with a composite seal utilizing a molded rubber ring sealing element, to replace the cork and composition cork seals now used for caps.
A seal for crown closures needs to be impervious to prevent gas leakage, resilient to maintain a good seal for several months, mechanically strong enough to be adapted to existing bottling equipment and must present a surface to pack side that is sufficiently soft or deformable to conform to minor imperfections on the lip of the bottle or can. The seal should not impart odor or taste to the contents of the bottle and should be capable of withstanding relatively high temperatures after capping without failure.
The seal of this invention comprises a resilient molded elastomer ring carried on a gas impervious for -stable disc, with the ring in use being between the cap and disc, and generally positioned over or registering with the lip of the container. The elastomeric or rubber ring is not capable of undergoing any appreciable cold or plastic iiow and imparts the necessary compressive force or spring action to the seal.