METHOD FOR COATING PLASTIC RECEPTACLES

Abstract

A method for coating an inside of a polyethylene terephthalate bottle with an oxide of silicon includes cooling the bottle within a covered cooling segment while transporting it toward a coating chamber, immediately after having cooled and transported said PET bottle to said coating chamber, forming a plasma, creating an under-pressure, and coating an inner surface of said bottle with an oxide of silicon.

Claims

1-18. (canceled)

19. A method comprising cooling a bottle within a covered cooling segment while transporting said bottle toward a coating chamber, immediately after having cooled and transported said PET bottle to said coating chamber, forming a plasma, creating an under-pressure, and coating an inner surface of said bottle with an oxide of silicon, wherein said bottle comprises polyethylene terephthalate.

20. The method of claim 19, wherein cooling said bottle within said cooling segment comprises cooling said bottle to a temperature that is below 30 C.

21. The method of claim 19, wherein cooling said bottle within said cooling segment comprises exposing said bottle to air that has been cooled by a cooling system.

22. The method of claim 21, further comprising extracting moisture from said cooled air and, after having extracted said moisture, exposing said bottle to said cooled air.

23. The method of claim 19, wherein cooling said bottle within said cooling segment comprises causing a lance to project into said bottle and, after having done so, passing cooling gas into an interior of said container through said lance.

24. The method of claim 19, wherein cooling said bottle within said cooling segment comprises exposing an exterior surface of said bottle to a gas that has been cooled by a cooling system.

25. The method of claim 19, further using a measurement of a surface temperature of said bottle for controlling said cooling of said bottle within said cooling segment.

26. The method of claim 19, further obtaining a measurement of a moisture content of said bottle prior to coating said inner surface of said bottle and using said measurement of moisture content of cooled gas that is to be used for cooling said container.

27. The method of claim 19, wherein transporting said bottle within said cooling segment toward a coating chamber comprises transporting using a conveying air-flow that comprises air that has been cooled in a cooling system.

28. An apparatus comprising a coating chamber, a cooling system, and a feed, wherein said coating chamber comprises a plasma-generating system and a first lance, wherein said first lance introduces material into said container and introduces energy into said material to cause a reaction that results in coating of an oxide of silicon on an interior wall of a bottle that is in said coating chamber, wherein said cooling system is connected to said coating chamber, and wherein said cooling system passes cooled gas through said feed.

29. The apparatus of claim 28, further comprising a second lance, wherein said second lance is connected to said feed for introducing cooled gas into said bottle.

30. The apparatus of claim 28, further comprising a housing, wherein said cooling system comprises a cooling segment, wherein said housing surrounds said coating chamber and said cooling segment, and wherein said housing connects said coating chamber and said cooling segment.

31. The apparatus of claim 30, further comprising an air-transport element that propels said bottles through said cooling segment towards said coating chamber.

32. The apparatus of claim 30, wherein said cooling system is configured to maintain pressure of cooling gas within a housing that contains said coating chamber at a pressure above ambient pressure.

33. The apparatus of claim 28, wherein said cooling system comprises a climate-control system that reduces moisture content of gas used for cooling containers.

34. The apparatus of claim 28, further comprising a controller and a temperature sensor, wherein said controller is configured to control said cooling system in response to a signal provided by said temperature sensor, said signal being indicative of a temperature of said bottle.

35. The apparatus of claim 28, further comprising a receiver wheel in said coating chamber, wherein said receiver wheel supports said container in said coating chamber.

36. The apparatus of claim 28, further comprising an air-conveyor system for causing an air flow that propels containers toward said coating chamber, said air flow comprising air that has been cooled by said cooling system.

37. The apparatus of claim 34, wherein said air-conveyor comprises neck-ring guides.

38. The apparatus of claim 28, further comprising a coating wheel that rotates during production, wherein said coating chamber is disposed on said coating wheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention is now described on the basis of the schematic drawings. These show:

[0041] FIG. 1 A coating system with a container cooling system, with conveyor belt, and

[0042] FIG. 2 a coating system in accordance with FIG. 1, but with an air conveyor for the containers in the container cooling system.

DETAILED DESCRIPTION

[0043] Referring to FIG. 1, a coating system 10 for coating containers 18 includes a housing 20 that houses both a coating chamber 12 and a cooling system 13 that is next to the coating chamber 12. The cooling system's inlet 22 forms the only opening into or out of the housing 20. In a typical embodiment, the containers 18 are polyethylene terephthalate bottles.

[0044] The cooling system 13 includes a cooling segment 14 along which containers 18 travel on a conveyor belt 16 driven by a drive motor 44. In some embodiments, a cooling device 42 within the conveyor belt 16 cools the containers' bases. A controller 40 controls both the cooling device 42 and the drive motor 44.

[0045] In the illustrated embodiment, a gas-nozzle arrangement 25 at the inlet 22 forms a gas screen 26 that separates the cooling segment 14 from ambient air 28. In those cases in which the pressure within the coating chamber 12 or the cooling segment 14 exceeds the pressure in the ambient air 28, no gas-nozzle arrangement 24 is needed.

[0046] Within the coating chamber 12, a plasma generator 30 connects to a plasma lance 32 that is introduced into a container 18 held at a container-receiver 33, such as a receiver wheel that supports a container in the coating chamber 12. In some embodiments, the container-receiver 33 is one that can be cooled separately.

[0047] The coating system 10 also includes air feeds 34 that connect to a cooling device. These air feeds 34 direct cooled air to the coating chamber 12 and to the cooling segment 14. In some embodiments, the cooling device is a climate-control device that draws moisture from the cooled air as well.

[0048] The controller 40 also connects to a temperature sensor 36 at the inlet of the coating chamber 12. The temperature sensor 36 determines the container's temperature immediately before that container 18 is to be coated and provides that temperature to the controller 40. A suitable temperature sensor 36 is an infrared sensor.

[0049] The controller 40 also connects to the feeds 34 and to the plasma generator 30. As a result, it is possible to regulate the cooling air's temperature in response to signals from the temperature sensor 36.

[0050] In some embodiments, the controller 40 also receives signals from a moisture sensor 38 that determines the container's moisture content immediately before coating that container 18. As a result, in those cases that use a climate-control device, is also possible for the controller 40 to also regulate the moisture content of incoming cooling air to achieve a pre-determined humidity.

[0051] Movable lances 46 connected to the cooling device can be lowered into containers 18. These lances 46 deliver cooled air at a particular temperature and humidity into the container 18. As a result, the cooling system 13 cools the containers 18 from both the inside and the outside. This ensures that, at the beginning of the coating process, the container 18 has the correct temperature.

[0052] The control unit 40 actuates the feeds 34 to raise pressure in the cooling segment 14 higher than pressure in the ambient air 28. Due in part to the gas screen 26, this causes cooler air to escape from the cooling segment 14, as indicated by the arrow, through the cooling segment's inlet 22 and into the ambient air 28. This also suppresses entry of ambient air 28, which may bring with it incorrect temperature or humidity, into the cooling segment 14. As a result, the coating system 10 results in a high-quality coating that is largely independent of conditions prevailing in the ambient air 28. This means that the coating system 10 can be used effectively in areas with high humidity and temperature.

[0053] In an alternative embodiment, shown in FIG. 2, neck-ring guides 48, which suspend containers 18 from their neck rings, replace the conveyor belt 16. Additionally, an air-conveyor system 50 uses a flow of cooled air to convey the containers 18 towards the coating chamber 12. The air-conveyor system 50 blows air against the entire container 18.

[0054] Some embodiments that rely on the air-conveyor system 50 also includes feeds 34 as shown in FIG. 1 to create a slight overpressure in the cooling segment 14. Other embodiments that rely on the air-conveyor system 50 also rely on lances 46 as shown in FIG. 1 to cool containers' interiors.

[0055] The controller 40 connects to the air-conveying system 50 and thus provides control over it in response to a signal from a temperature sensor 48 and in some cases, a moisture sensor 38.

[0056] In some embodiments, the air-conveyor 50 includes decentralized components of a cohesive air-guidance device that extends along the cooling segment 14 and that is connected to a common cooling system 13, such as a climate-control system or air-conditioner.

[0057] In some embodiments, the coating chamber 12 is closed so that a vacuum can be formed within. In other embodiments, the coating chamber 12 is on a coating-wheel that rotates during production.

[0058] The invention is not restricted to the exemplary embodiment described heretofore, but can be varied within the scope of protection of the claims hereinafter.