Patent ID: 7838071

Claim:
A method for treating at least one container ( 12 ) aimed at depositing an internal coating forming a barrier by means of a microwave plasma, in particular with a view to enabling oxido-sensitive liquids to be packaged in the container ( 12 ), comprising: disposing the container ( 12 ) inside a hermetically sealed treatment chamber ( 16 ) which delimits a cavity ( 18 ) outside the container ( 12 ) and which is connected to a vacuum pumping circuit ( 50 ) by an external vacuum line ( 20 ), an interior of the container ( 12 ) being connected to the pumping circuit ( 50 ) by an internal vacuum line ( 34 ); performing a preliminary step (El) during which the pumping circuit ( 50 ) produces a pressure reduction inside the cavity ( 18 ) to a set value called the final external value (pFext), and a pressure reduction inside the container ( 12 ) to a set value called the final internal value (pFint), which is lower than the final external value (pFext); and the preliminary step (El) being followed by a treatment step (E 2 ) during which the final values (pFext, pFint) are maintained inside the cavity ( 18 ) and inside the container ( 12 ) so as to enable the internal coating to be deposited inside the container ( 12 ), wherein the preliminary step (El) comprises successively: an external pumping phase (P 1 ), during which the internal vacuum line ( 34 ) is closed and the external vacuum line ( 20 ) is open, the pumping circuit ( 50 ) producing a pressure reduction only inside the cavity ( 18 ), until an intermediate value (pMext) which is greater than to the final external value (pFext), an intermediate pumping phase (Pm), between the external pumping phase (P 1 ) and an internal pumping phase (P 2 ), during which the external vacuum line ( 20 ) and the internal vacuum line ( 34 ) are opened simultaneously so that the pumping circuit ( 50 ) reduces the pressure simultaneously inside the cavity ( 18 ) and inside the container ( 12 ), until the pressure inside the cavity ( 18 ) reaches the final external value (pFext), and an internal pumping phase (P 2 ), during which the external vacuum line ( 20 ) is closed and the internal vacuum line ( 34 ) is open, the pumping circuit ( 50 ) producing a pressure reduction only inside the container ( 12 ), to the final internal value (pFint).