Abstract: Composite material for seals of plastic caps, especially of screw caps, ensuring leakproofing against liquids and imperviousness to gases at the same time, characterized in that it comprises, combined in a coherent multilayer structure, at least one middle layer (4) made of a plastic substance with a gas barrier effect, with a high modulus of rigidity, two outer layers (7) arranged on either side of the middle layer and consisting of a plastic substance with a low modulus of rigidity, each of the outer layers having a thickness greater than the thickness of the middle layer, and between the middle layer (4) and each outer layer (7) an intermediate layer (5) made of a substance of the same class as the outer layer, but with a high modulus of rigidity.

Abstract: Leaktight screw cap composed of two cup-shaped shells rendered integral by fitting one into the other, the lowest shell being made from a flexible plastic having a female thread and a sealing device and the outer shell being made from a hard plastic. A disk made from a material having a gas-barrier effect is inserted between the bottoms of the outer shell of the inner shell. This screw cap is especially applicable to beverages and other products that are sensitive to gas exchanges with the outside.

Abstract: This is a combination pouring spout and closure cap which straddles the same. The closure cap has two annular dependent spaced skirts. The inner of these skirts fits tightly the inner space of the pouring spout and is held in position by coaction of circumferentially spaced helicoidal ridges on the inner face of the outer skirt with an interrupted ridge on the outer face of the pouring spout.