FOND NE SE RETOURNANT PAS POUR BOUTEILLES EN MATIERE THERMOPLASTIQUE

A generally cylindrical, biaxially oriented thermoplastic bottle for bottling liquids under pressure, such as beer, soda and aerosols, having a noneverting bottom under conditions of bottling and use. The bottom of the bottle in the unpressurized state comprises a shell of thermoplastic material having a configuration defined as a series of sequentially connected geometric shapes rotationally symmetrical about the central axis of the bottle starting with (a) about a 90 DEG portion of a circle connected to the generally cylindrical section of the bottle, forming the annular bottom edge, connected to (b) a straight line forming a flat section which is the bottom seating area of the bottle, connected to (c) about a 90 DEG portion of a circle forming an annular toroidal knuckle turning into (d) a straight line forming a re-entrant cylinder connected to (e) about a 180 DEG portion of a circle forming a recessed annular toroidal knuckle ending with (f) a straight line forming a recessed disc in the bottom center of the bottle. To further improve eversion resistance, the bottom of the bottle can include a reinforcing ring attached to the recessed annular toroidal knuckle. Under an autogenous pressure, the bottle dimensions remain practically the same except that the flat bottom seating area moves outward and the bottle now stands on the annular toroidal knuckle that turns upward into the re-entrant cylinder.