A system for molding plastics material, includes: at least one injection nozzle (2) with a cylindrical body; at least one hot chamber (24) on which the at least one injection nozzle is mounted; at least one penetrating ram rod (15) which extends coaxially with the injection nozzle; at least two passages (4, 5) for supplying the molding material to the injection nozzle; the injection nozzle (2) including: at least one containing collar (7); at least one injection valve (11) mounted coaxially with the containing collar (7) and having a supply end (13); the injection valve (11) including: at least a first supply channel (18) for a first molding material; at least a second supply channel (19) for a second molding material; the first and second injection channels remaining separate as far as the supply end.