Abstract: A plastic screw cap for the closure of a plastic container is provided for the closure of a container made of plastics. The screw cap has a simple configuration similar to corresponding closures for metal containers, but nevertheless ensures stable and sealed seating of the closure on the container opening. The screw cap is provided with an extension, extending radially over the side of the screw cap, which is made from a material which can be welded to the material from which the container lid is made.

Abstract: The present invention relates to a plastics screw cap for container closures which is child-proof, with an inner cap (1) with an internal thread (13) which can be screwed onto a neck or a connecting piece of a container for receiving a closure, and an outer cap (2) which is freely rotatable with respect to the inner cap (1) at least in the direction of opening, wherein between the inner and outer caps (1, 2) engaging elements (7, 8, 9, 10) are provided which can only be engaged in an interference fit when a not exclusively tangential force is applied in the direction of opening, in addition to the tangential force effecting the opening moment.

Abstract: A plastic closure for a plastic container and a method of making it. The closure is made of a plastic material of different hardness or melting temperature from the container and its sealing edge is fitted into the container neck. An edge surface of the sealing edge extends substantially immediately adjacent an edge surface of the neck and is welded to the neck by simultaneous heating of the adjacent edge surfaces.