Plasma deposition equipment coats PET bottle with internal carbon layer from gaseous precursor in microwave field, overcoming numerous shortcomings of known barrier layer alternatives

摘要

The enclosure (2) has a removable, sealing cover (4) supporting an injector (7) connected to a source of gaseous precursor and an extraction orifice (5) connected to a pump. In addition the cover provides support (17) for the container (18). Preferred features: The injector discharges into the container when the latter is located in the enclosure. A pump reduces container internal pressure, for plasma generation. The container interior forms a reaction chamber, from which the barrier layer is deposited onto its internal surface. The pump also reduces enclosure pressure, and with it, pressure differential across the container walls. The support grips the container neck, applying its rim (23) to the internal face (22) of the cover. The rim surrounds the extraction- and injection openings. The support is moved axially (19) to position it in the cover prior to depositing the coating, or when opening the container complete with internal surface deposit. Gaseous precursor is delivered from the injector under very slight pressure. The polymer substrate is coated with barrier material. This is an amorphous carbon having polymeric tendency (structure is explained more completely in the text). The injector is connected to a gas generator. A microwave generator provides plasma excitation, operating at UHF frequencies. A waveguide (8) connects it to a cavity surrounding the enclosure. Short-circuiting provisions are made in the cavity and waveguide. The enclosure transverse dimension is close to that of the container profile.