Method for Cold Plasma Treatment of Plastic Bottles and Device for Implementing Same

Abstract

The present invention relates to a method for treating plastic bottles comprising an operation for cold plasma sterilization with non-germicidal gasses and/or an operation for the cold plasma deposition of a diffusion barrier layer, said method being characterized in that said cold plasma delivers adjustable nonthermal energy to the entire inside surface of the bottle, said cold plasma being generated either through a distributed propagation of microwaves having a maximum intensity in the vicinity of said surface or by a hollow cathode system adapted to the bottle and supplied with pulsed DC and/or RF voltage. The invention also relates to the devices for implementing the method.

What is claimed is: 
     
         1 . A device for generating a cold plasma that is operable to treat a polymer bottle in the absence of contact with liquid effluents, wherein the polymer bottle has an inner surface and an outer surface, the device comprising:
 a cold plasma generation device selected from the group consisting of an annular surface-wave launcher and a hollow cathode system, the annular surface-wave launcher being operable to distribute propagated non-pulsed microwaves having maximum intensity proximate the inner surface of the bottle, the hollow cathode system being adapted to the outer surface of the bottle, and the hollow cathode system being supplied with pulsed DC voltage or radiofrequency voltage;   a nongermicidal gas source configured to provide a nongermicidal gas to the inner surface of the bottle; and   a diffusion barrier gas source configured to provide a diffusion barrier gas to the inner surface of the bottle,   wherein the cold plasma generation device is configured to create a nonthermal energy flux within the bottle to energize the nongermicidal gas under conditions operable to create the cold plasma such that the inner surface of the polymer bottle is sterilized;   wherein the cold plasma generation device is configured to deposit a diffusion barrier layer on the inner surface of the polymer bottle under conditions operable to promote plasma-enhanced chemical vapor deposition (PECVD).   
     
     
         2 . The device as claimed in  claim 1 , wherein the cold plasma generating device is the hollow cathode. 
     
     
         3 . The device as claimed in  claim 2 , wherein the hollow cathode comprises two half-shells. 
     
     
         4 . The device as claimed in  claim 2 , wherein the hollow cathode comprises an extrusion blow mold. 
     
     
         5 . The device as claimed in  claim 1 , wherein the cold plasma generation device is the annular surface-wave launcher, and the cold plasma is generated by at least one surface wave microwave field applicator supplied by a microwave generator. 
     
     
         6 . The device as claimed in  claim 5 , wherein the cold plasma is generated by a plurality of surface wave applicators distributed and supplied by decorrelated phases 
     
     
         7 . The device as claimed in  claim 5 , wherein the microwaves are propagated in a distributed manner by microstrip applicators movably adjusted to the outer surface of the bottle. 
     
     
         8 . The device as claimed in  claim 5 , wherein the annular surface-wave launcher is configured to be placed around a median portion of a bottle to be treated. 
     
     
         9 . The device as claimed in  claim 5 , wherein the annular surface-wave launcher is configured to be placed around a median portion of a bottle to be treated at a position closer to a bottom of the bottle than to a neck of the bottle. 
     
     
         10 . The device as claimed in  claim 5 , further comprising a plurality of annular surface-wave launchers disposed about the bottle, wherein each surface-wave launcher is configured to emit waves which do not interfere with waves from other surface-wave launchers. 
     
     
         11 . The device as claimed in  claim 5 , further comprising a plurality of annular surface-wave launchers disposed about the bottle, wherein each annular surface-wave launcher is supplied by a different generator such that each annular surface-wave launcher is configured to produce a wave that is decorrelated from other produced waves such that wave intensities are additive. 
     
     
         12 . The device as claimed in  claim 1 , wherein the nongermicidal gas is selected from the group consisting of N 2 , O 2 , N 2 O, H 2 , H 2 O, Ar, He, Kr, Xe, and mixtures thereof. 
     
     
         13 . The device as claimed in  claim 1 , wherein the nongermicidal gas consists essentially of N 2  and O 2 . 
     
     
         14 . The device as claimed in  claim 1 , wherein device is configured to sterilize the bottle in a time between 0.05 to 5 seconds. 
     
     
         15 . The device as claimed in  claim 1 , wherein the diffusion barrier gas is selected from the group consisting of monomers, gaseous carbon vectors, gaseous silicon compounds, and mixtures thereof. 
     
     
         16 . The device as claimed in  claim 1 , further comprising means for applying a vacuum to the bottle such that the pressure within the bottle is between 0.1 and 10 mbar while the diffusion barrier is deposited. 
     
     
         17 . The device as claimed in  claim 1 , further comprising means for applying a UV protection layer to the diffusion barrier layer.