Bi-injected cap, and method for manufacturing such a cap

A method for molding a cap including at least one bottom, a side wall and an annular seal, the method comprising:

• two parts of the mold, movable relative to one another, are placed so as to form an annular cavity with an injection orifice;
• a first of these parts having an annular protuberance, the annular protuberance defining an upper wall of the annular cavity, the other part having an annular groove defining a lower wall of the annular cavity, the annular protuberance penetrating the annular groove so as to close the annular cavity;
• a flexible material is injected into the annular cavity so as to fill the annular cavity;
• and
• the two parts of the mold are separated from each other so as to form a primary cavity having a first portion intended to form the bottom of the cap, extended by a second, generally cylindrical portion intended to form the side wall of the cap, the first portion having an inner wall defining the inner face of the bottom of the cap, the annular cavity containing the flexible material emerging in the first portion of the primary cavity.