Abstract: A unitary cap of two dissimilar materials for sealing containers such as bottles or jars comprising a rigid outer closure member and a substantially resilient inner sealing member formed together as a unitary cap wherein the substantially rigid outer closure member includes a top wall and a depending annular side wall which extends over and is adapted to be secured to the neck of a container, serrations are provided on the exterior surface of the substantially rigid outer closure member for gripping purposes, and a reinforcement shoulder is located on the outer perimeter of the depending annular side wall adjacent the lower edge thereof to prevent excessive cap expansion upon application to a container and the substantially resilient inner closure member includes a base sealing element bonded or anchored to the substantially rigid closure member disposed to engage the inner and outer rim edges and/or top surface of the container to which the unitary cap is applied.

Abstract: A closure cap for capping a fluid container comprising a top having a substantially annular skirt depending downwardly from the periphery thereof and a resilient interference structure formed on the inner surface of the substantially annular skirt to engage threads formed on the fluid container to form a locking seal therebetween.

Abstract: A plastic cap for vacuum sealing glass containers such as bottles or jars is disclosed. The cap includes a top wall and a depending annular side wall which extends over and is adapted to be threadedly secured to the neck of a container. The depending side wall has at its lower edge a lead-in chamfer and suitable threads adapted to engage corresponding threads formed on the exterior of the container to which it is to be secured. In a preferred form, serrations are provided on the exterior surface of the cap for gripping purposes, and a reinforcement shoulder is located on the outer perimeter of the side wall adjacent the lower edge thereof to prevent excessive cap expansion upon application to a container. Vacuum sealing is attained by means of two annular flanges depending from and integrally formed with the top wall of the cap.