Method for treating an elastomer packaging element, and packaging element thus treated

A method of treating an elastomer packaging element, said packaging element having a bottom portion configured to penetrate into a neck of a container and a top portion configured to remain external to the container and having a top surface, the packaging element is configured to co-operate with a distal end surface of said neck of the container so as to seal the container, said method comprising a stage of atmospheric plasma- assisted surface activation of the top surface and a subsequent stage of atmospheric plasma- assisted deposition on the top surface,

• wherein said atmospheric plasma-assisted surface activation stage comprises, at atmospheric pressure, passing a first plasma flame over said top surface, wherein:
• a gas used for generating the first plasma flame is nitrogen,
• a speed at which the first plasma flame passes over said top surface is 100 mm/s to 500 mm/s,
• a number of passes over said top surface to perform the activation is one cycle,
• a flow rate of the gas for generating the first plasma flame is 10 L/min to 100 L/min, and
• a distance between the nozzle where the first plasma flame is generated and said top surface is in the range of 5 mm to 35 mm, and
• wherein said atmospheric plasma-assisted deposition stage comprises passing, at atmospheric pressure, a second plasma flame over said top surface, wherein:
• a gas used for generating the second plasma flame is air,
• a speed at which the second plasma flame passes over said top surface is 100 mm/s to 500 mm/s,
• a number of passes over said top surface to perform the deposition is two cycles,
• a gas flow rate of the gas for generating the second plasma flame is 10 L/min to 100 L/min,
• a distance between the nozzle where the second plasma flame is generated and said top surface is in the range of 5 mm to 35 mm;
• and
• a monomer is injected into said second plasma flame, said monomer polymerizing on the top surface to form a coating.