Patent EA-001023-B1 (EA)
Title: Plastic containers with an external gas barrier coating
Inventor: PLESTER GEORGE
IPC: C23C16/00
Filed: 1998-03-13
Abstract: 1. A system for making a coated plastic container possessing a gas barrier, the system comprising: a vacuum cell capable of maintaining a vacuum within the vacuum cell; a container feeder for supplying plastic container bodies into and withdrawing coated plastic containers out from the vacuum cell, the plastic container bodies each having an external surface and an interior surface defining an interior space; a conveyor within the vacuum cell for conveying the plastic container bodies through the vacuum cell; and at least one source disposed in the vacuum cell for supplying a coating vapor to the external surface of the container bodies as the container bodies are conveyed through the vacuum cell, the at least one source of coating vapor including an evaporator for heating and evaporating an inorganic coating material to form the coating vapor; a gas feed for supplying at least one reactive gas to an interior of the vacuum cell; the at least one source of coating vapor and the conveyor structured and arranged within the vacuum cell such that (a) the coating vapor from the at least one source reacts with the reactive gas and deposits a thin coating on the external surface of the containers, (b) the thin coating comprises an inorganic compound and bonds to the external surface of the container bodies, and (c) the resulting coated plastic containers, when containing a pressurized fluid sealed in the interior space at a pressure of 60 psig (4.1 bars), possess a gas barrier of at least 1.25x the gas barrier of the containers without the coating, when the containers without the coating contain a pressurized fluid sealed in the interior space at a pressure of 60 psig (4.1 bars). 2. The system for making a coated plastic container as in claim 1, wherein the reactive gas is selected from the group consisting of oxygen, nitrogen, sulfur and halogens. 3. The system for making a coated plastic container as in claim 1, wherein the reactive gas is oxygen and the inorganic compound is an inorganic oxide. 4. The system for making a coated plastic container as in claim 1, wherein, while the vacuum cell maintains a vacuum within the vacuum cell, the container feeder continuously feeds the container bodies from outside the vacuum cell into the vacuum cell to the conveyor, the conveyor continuously conveys the container bodies through the vacuum cell past the at least one source, and the container feeder continuously retrieves the coated containers from the conveyor and withdraws the coated containers from the vacuum cell. 5. The system for making a coated plastic container as in claim 1, further comprising means for rotating the container bodies while the container bodies are conveyed through the vacuum cell. 6. The system for making a coated plastic container as in claim 4, wherein the container bodies each have a bottom and sides and the conveyor is capable of orienting the plastic container bodies relative to the at least one source of coating vapor to coat both the bottom and sides of the container with the coating vapor. 7. The system for making a coated plastic container as in claim 1, further comprising a capper for sealing each container body with a cap before the container body is fed to the conveyor, wherein the conveyor comprises a plurality of arms for engaging the caps while the caps are on the container bodies and carrying the container bodies while the conveyor transports the container bodies through the vacuum cell. 8. The system for making a coated plastic container as in claim 1, further including means for forming the coating vapor into a high-energy plasma. 9. The system for making a coated plastic container as in claim 1, wherein the at least one source of coating vapor comprises a receptacle electrically connected as an anode for containing at least a portion of the coating material and a cathode directed at the portion of the coating material in the receptacle for at least partially vaporizing the coating material and forming the coating vapor into plasma. 10. The system for making a coated plastic container as in claim 9, wherein the cathode is vaporizable to form a portion of the coating vapor. 11. The system for making a coated plastic container as in claim 10, wherein the cathode comprises brass. 12. The system for making a coated plastic container as in claim 10, wherein the cathode comprises magnesium. 13. The system for making a coated plastic container as in claim 1, wherein the conveyor and the at least one source of coating vapor are structured and arranged so that the coating vapor reacts on the external surfaces of the container bodies with the reactive gas supplied by the gas feed to form the coating. 14. The system for making a coated plastic container as in claim 3, wherein the thin coating further comprises a glass-forming metal additive. 15. A method for making a coated plastic container possessing a gas barrier, the method comprising the steps of: feeding plastic container bodies into a vacuum cell while the vacuum cell maintains a vacuum in the vacuum cell, the plastic container bodies each having an external surface and an interior surface defining an interior space; conveying the plastic container bodies through the vacuum cell; feeding a reactive gas into the vacuum cell; heating and evaporating an inorganic coating material with an evaporator disposed in the vacuum cell to form a coating vapor; and withdrawing the coated plastic containers out from the vacuum cell, the steps of conveying the container bodies and forming the coating vapor conducted such that, as the container bodies are conveyed through the vacuum cell, the coating vapor reacts with the reactive gas and deposits a thin coating on the external surface of the containers, (b) the thin coating comprises an inorganic compound and bonds to the external surface of the container bodies, and (c) the resulting coated plastic containers, when containing a pressurized fluid sealed in the interior space at a pressure of 60 psig (4.1 bars), possess a gas barrier of at least 1.25x the gas barrier of the containers without the coating, when the containers without the coating contain a pressurized fluid sealed in the interior space at a pressure of 60 psig (4.1 bars). 16. The method for making a coated plastic container as in claim 15, wherein the reactive gas is selected from the group consisting of oxygen, nitrogen, sulfur and halogens. 17. The method for making a coated plastic container as in claim 15, wherein the reactive gas is oxygen and the inorganic compound is an inorganic oxide. 18. The method as in claim 15, wherein, while the vacuum cell maintains a vacuum within the vacuum cell, the step of feeding includes continuously feeding the container bodies from outside the vacuum cell into the vacuum cell to the conveyor, the step of conveying includes continuously conveying the container bodies through the vacuum cell past the at least one source, and the feeding step further includes continuously retrieving the coated containers from the conveyor and withdrawing the coated containers from the vacuum cell. 19. The method as in claim 15, wherein the step of conveying comprises rotating the container bodies while the container bodies are conveyed through the vacuum cell. 20. The method as in claim 18, wherein the step or feeding comprises automatically and continuously feeding the container bodies with a rotary feeder into the vacuum cell to the conveyor from a source of container bodies outside the vacuum cell and automatically and continuously retrieving the coated containers from the conveyor and transporting the coated containers to a location outside the vacuum cell. 21. The method as in claim 20, wherein the rotary container feeder includes a feed wheel rotatably mounted in a port of the vacuum cell. 22. The method as in claim 21 wherein clamps are disposed in each of the feed wheel ports for grasping the necks of the container bodies while the container bodies are transported by the feed wheel. 23. The method as in claim 20, wherein the rotary container feeder includes a first exterior rotary feeder for automatically and continuously feeding the uncoated plastic container bodies to the feed wheel and a first interior rotary feeder for automatically and continuously feeding the uncoated plastic container bodies from the feed wheel to the conveyor, a second interior rotary feeder for automatically and continuously feeding the coated plastic container bodies from the conveyor to the feed wheel and a second exterior rotary feeder for automatically and continuously taking over the coated plastic container bodies from the feed wheel 24. The method as in claim 23 wherein clamps for grasping the neck of the container bodies are disposed on the interior and exterior rotary feeders. 25. The method as in claim 15, further comprising the step of forming the coating vapor into a high-energy plasma. 26. The method as in claim 15, further comprising the step of sealing the container bodies so that the container bodies are sealed when in the vacuum cell to thereby prevent air within the interior space of the container bodies from escaping. 27. The method as in claim 26, wherein the container bodies are sealed with a pressure in the interior space of the containers greater than the pressure in the vacuum cell. 28. The method as in claim 15, wherein the step of supplying coating vapor further comprises at least one of chemically and physically bonding the inorganic compound to the external surface of the container bodies. 29. The method as in claim 15, wherein the evaporator comprises a receptacle electrically connected as an anode for containing at least a portion of the coating material and a cathode, and the step of forming the coating vapor comprises directing the cathode at the portion of the coating material in the receptacle for at least partially vaporizing the coating material and forming the coating vapor into plasma. 30. The met