Abstract:
A coated plastic container provides for low permeability to gases and vapors. A method and system for coating plastic containers includes applying a thin inorganic oxide layer to the external surface of the containers with plasma-assisted vacuum vapor deposition. For example, the coating can include silica which is bonded to the external surface of the container. This coating is flexible and can be applied regardless of the container&#39;s internal pressure or lack thereof. The coating firmly adheres to the container and possess an enhanced gas barrier effect after pressurization even when the coating is scratched, fractured, flexed and/or stretched. Moreover, this gas barrier enhancement will be substantially unaffected by filling of the container. A method of recycling coated plastic containers and a method and system for packaging a beverage using the coated containers are also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 09/380,904 filed on Sep. 10, 1999 now U.S. Pat. No. 6,279,505 which is a 371 claims priority based on International Patent Application PCT/US98/05293 filed on Mar. 13, 1998 and is a continuation-in-part of U.S. patent application Ser. No. 08/818,342 filed on Mar. 14, 1997 now U.S. Pat. No. 6,223,683. The disclosures of U.S. patent application Ser. No. 09/380,904, International PCT/US98/05293, and U.S. patent application No. 08/818,342 are expressly incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     This invention relates to pressurized plastic containers that have enhanced barrier performance and methods to provide said containers and to the coatings. The enhanced barrier performance is obtained by application of inorganic coatings to the external surface of the container. The coatings exhibit enhanced adhesion relative to prior art coatings. In addition, this invention also relates to recycling of coated plastic containers and the packaging of beverages in said container. 
     BACKGROUND OF THE INVENTION 
     Plastic containers currently comprise a large and growing segment of the food and beverage industry. Plastic containers offer a number of advantages over traditional metal and glass containers. They are lightweight, inexpensive, nonbreakable, transparent and easily manufactured and handled. However, plastic containers have at least one significant drawback that has limited their universal acceptance, especially in the more demanding food applications. That drawback is that all plastic containers are more or less permeable to water, oxygen, carbon dioxide, and other gases and vapors. In a number of applications, the permeation rates of affordable plastics are great enough to significantly limit the shelf-life of the contained food or beverage, or prevent the use of plastic containers altogether. 
     It has been recognized for some time that a container structure that combines the best features of plastic containers and more traditional containers could be obtained by applying a glass-like or metal-like layer to a plastic container, and metallized plastic containers. For example, metallized potato chip bags have been commercially available for some time. However, in a number of applications, the clarity of the package is of significant importance, and for those applications metallized coatings are not acceptable. Obtaining durable glass-like coatings on plastic containers without changing the appearance of the container has proven to be much more difficult. 
     A number of processes have been developed for the purpose of applying glass-like coatings onto plastic films, where the films are then subsequently formed into flexible plastic containers. However, relatively few processes have been developed that allow the application of a glass-like coating onto a preformed, relatively rigid plastic container such as the PET bottles commonly used in the U.S. for carbonated beverages, and heretofore no process has been developed that allows the application of a glass-like coating onto the external surface of a plastic container that is sufficiently durable to withstand the effect of pressurization of the container, retain an enhanced barrier to gases and vapors subsequent to said pressurization, and not affect the recyclability of the containers. Pressurized beverage containers currently comprise a very large market world-wide, and currently affordable plastics have sufficiently high permeation rates to limit the use of plastic containers in a number of the markets served. 
     Such pressurized containers include plastic bottles for both carbonated and noncarbonated beverages. Plastic bottles have been constructed from various polymers, predominant among them being polyethylene terephthalate (PET), particularly for carbonated beverages, but all of these polymers have exhibited various degrees of permeability to gases and vapors which have limited the shelf life of the beverages placed within them. For example, carbonated beverage bottles have a shelf-life which is limited by loss of CO 2 . (Shelf-life is typically defined as the time needed for a loss of seventeen percent of the initial carbonation of a beverage.) Because of the effect of surface to volume ratio, the rate of loss becomes greater as the size of the bottle is reduced. Small containers are needed for many market applications, and this severely limits the use of plastic bottles in such cases. Therefore, it is desirable to have a container with improved carbonation retention properties. 
     For non-carbonated beverages, similar limitations apply, again with increasing importance as the bottle size is reduced, on account of oxygen and/or water-vapor diffusion. It should be appreciated that diffusion means both ingress and egress (diffusion and infusion) to and from the bottle or container. The degree of impermeability (described herein as “gas barrier”) to CO 2  diffusion and to the diffusion of oxygen, water vapor and other gases, grows in importance in conditions of high ambient temperature. An outer coating with high gas barrier can improve the quality of beverages packed in plastic bottles and increase the shelf life of such bottles, making small bottles a more feasible alternative, and this in turn presents many advantages in reduced distribution costs and a more flexible marketing mix. 
     Some polymers, for example PET, are also susceptible to stress cracking when they come in contact with bottle-conveyor lubricants used in bottle filling plants, or detergents, solvents and other materials. Such cracking is often described as “environmental stress cracking” and can limit the life of the bottle by causing leaks, which can cause damage to adjacent property. An impermeable outer surface for plastic bottles which surface resists stress-cracking inducing chemicals, prevents damage to adjacent property and will extend the shelf life of plastic bottles in some markets is highly desirable. 
     Another limitation to shelf life and beverage quality is often UV radiation which can affect the taste, color and other beverage properties. This is particularly important in conditions of prolonged sunshine. An outer coating with UV absorbing properties can improve the quality of such beverages and make plastic bottles much more usable under such conditions. 
     It is also desirable that plastic containers such as PET bottles be recyclable. Prior art barrier enhanced coatings, however, are often organic and relatively thick and therefore can contaminate a recycled plastic product. Organic coating materials incorporated into recycled plastic make unsuitable containers for beverage or food items because the beverage or food items can contact the organic coating material and become contaminated. In addition, relatively thick coatings form relatively large particles during recycling of plastic material and can damage the appearance and properties of a resulting recycled plastic product. In particular, relatively large coating particles in recycled plastic can make otherwise clear plastic hazy. Hazy plastic is often undesirable for containers such as beverage and food containers. 
     Finally, the cost of applying a coating to the outside of a bottle, which has a gas barrier which significantly increases the shelf-life of beverage container in that bottle, and/or which significantly reduces product spoilage of beverage container in that bottle, and/or which significantly reduces product spoilage due to UV radiation, and/or virtually eliminates environmental stress cracking, and/or provides a specific color, must not add significant cost to the basic package. This is a criterion which eliminates many processes for high gas barrier coatings, because plastic bottles are themselves a very low cost, mass produced article. Affordability implies in practice that the cost of the coating must add minimal or no increase to the cost of the whole package and in fact, the cost can be less. 
     A coating on the outside of plastic bottles must be capable of flexing. When bottles are used for pressurized containers, the coating preferably should be able to biaxially stretch whenever the plastic substrate stretches. In addition it is preferable that the coating be continuous over the majority of the container surface. Adhesion is particularly important in the case of carbonated beverages, since the CO 2  within the bottle exerts some or all of its in-bottle pressure on the coating. This pressure can rise to above 6 bar, exerting considerable forces on the coating/plastic interface. The coating must also resist scuffing, normal handling, weathering (rain, sun climate, etc.), and the coating must maintain its gas barrier throughout the bottle&#39;s useful life. 
     There are several plasma-enhanced processes which apply an external, inorganic coating to a range of articles, which in some cases includes bottles. Many of the processes are targeted to provide coating properties which are quite different, and far less onerous than high gas barrier bottle coatings. Such processes target, for example, abrasion resistance, where the coating continuity is not a major factor, since the coating can protect the microscopic interstices. Other processes target cosmetic or light-reflection properties and some processes have a pure handling protection role. Often the substrate does not flex nor stretch and the article itself is higher priced than plastic bottles so that cost is not a benefit of the design. In some cases, the substrate allows far higher coating temperatures than those allowed by PET, the most common plastic-bottle material. Such processes do not, in general, provide the coating continuity, adhesion, flexibility needed for high gas barrier coatings, nor do they provide a solution to the other problems relating to high gas barrier coatings, described above. 
     Prior art also exists for gas barrier processes for bottles, but the lack of commercially available, coated bottles for pressurized application is due to the fact that these processes lack the desirable attributes described above and fail to provide a coating with adequate adhesion, continuity and/or flexibility under high in-bottle pressure or a coating which avoids recycling problems, or the low cost necessary to make the coating affordable. 
     U.S. Pat. No. 5,565,248 to Plester and Ehrich describes a method for coating containers internally. However, external coatings require far greater adhesion than internal coatings, because in-bottle pressure acts against external coatings, and internal coatings are not subject to the same handling and/or abrasion in use. For these, and other reasons, coating bottles externally differs from coating them internally and the present invention is therefore substantially different. 
     For plastic containers such as PET bottles to be economically feasible containers for commercial products such as beverages and food, the bottles must be manufactured relatively inexpensively at a high speed and high volume. Accordingly, a process and system for coating plastic containers must be economical and capable of functioning at a high speed and high volume. Many prior art systems for coating objects with a gas barrier coating are batch processes or otherwise slow and inefficient. 
     Accordingly, there is a need for plastic containers which are coated with an effective gas barrier coating, can be efficiently recycled, and can be economically produced for use as containers for mass produced items such as beverages and food. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an outer coating or layer for a container such as a heat sensitive plastic bottle, and particularly for the non-refillable bottles used for carbonated beverages. 
     It is a further object of the present invention to provide a coating and a system and method for coating which can provide an external glass-like coating that is flexible, durable and possess sufficient adhesion to withstand the effects of pressurization, such as flexing and stretching of the container, and to withstand denting of the container, without significant loss of enhanced barrier properties. 
     An additional object of the present invention is to provide an externally coated container which will avoid environmental stress cracking such as when the container comes into contact with conveyor lubricants during filling and detergent, cleaners or solvents or similar substances during its life cycle. Such lubricants can include 409™, Mean Green™ or other commercially available cleansers or lubricants, etc. 
     Yet another object of the present invention is to provide a lighter container and a system and method for making the container whereby an amount of plastic utilized in making the container as compared to a conventional container can be reduced without adversely affecting or while improving the gas barrier effectiveness of the container. 
     It is another object of the present invention to provide a coating that comprises an inorganic oxide layer on the external surface of a plastic container, the inorganic oxide layer being further distinguished by being comprised of greater than or equal to 50 and up to but less than 100% SiO x  (x=1.7 to 2.0). 
     Another object is to provide a coating which possesses sufficient adhesion to the external surface of the plastic container so that the barrier enhancement provided by the inorganic oxide layer is not substantially reduced upon pressurization of the container to a pressure between 1 and 100 psig. 
     A further object of the present invention is to provide a method for applying an inorganic layer as described above, the method resulting in a robust inorganic oxide layer that provides an effective level of barrier enhancement to the plastic container and does not result in significant physical distortion of the container. 
     It is a further object of the present invention to provide a system and method for manufacturing a container whereby the aesthetic appeal of the container will be enhanced by applying a colored inorganic layer that further contains visible-light absorbing species. 
     Yet another object of the present invention is to provide a coating for a container with UV absorbing capabilities. 
     Still another object of the present invention is to provide a container with a colored or clear coating which can easily be recycled without significant or abnormal complications to existing recycling systems. 
     Another object of the present invention is to provide a system and method for inexpensively manufacturing an externally coated container at high speed and high volume. 
     Yet another object of the present invention is to provide a method in which the thickness and composition of the applied coating on a container can be rapidly and easily determined and whereby process control and insurance of enhanced barrier performance can be obtained. 
     A further object of the present invention is to provide a method to determine the condition of the surface of a plastic container at least with regards to its suitability for applying glass-like coatings. 
     Another object of the present invention is to provide a high gas barrier which considerably increases the shelf life of the containers such as plastic bottles and to provide the containers with good transparency so as not to affect the appearance of a clear plastic bottle. 
     Still another object of the present invention is to provide a container with adequate durability and adhesion during working life, when the outer surface of the container is subjected to environmental conditions such as severe weather, rubbing, scuffing, or abrasions (for example, during transportation). 
     Also, another object of the present invention includes the ability to enable coating to heat sensitive plastic containers with coating materials, which can only be vaporized at very high temperatures without an acceptable increase in the plastic&#39;s temperature and which must remain in many cases below 60° C. 
     The foregoing and other objects of this invention are fulfilled by providing a coated plastic container comprising a plastic container body having an external surface and a coating on the external surface of the container body comprising an inorganic oxide and a glass-forming metal additive, wherein the coated plastic container, when containing a pressurized fluid sealed in the interior space of the container body at a pressure of 60 psig, possesses a gas barrier of at least 1.25× the gas barrier of the container without the coating, when the container without the coating contains a pressurized fluid sealed in the interior space at a pressure of 60 psig. This invention also encompasses a method and system for making a coated plastic container possessing a gas barrier, a method fop recycling coated plastic containers, and a method and system for packaging beverages sealed in plastic containers including a gas barrier coating. 
     More particularly, the coated plastic container of this invention is made by depositing the coating on the exterior surface of the container body using vacuum vapor deposition, desirably plasma-enhanced vacuum vapor deposition. The resulting coating is desirably substantially homogeneous and amorphous and bonded either chemically or physically, or both, to the exterior surface of the container. As used herein, the term homogeneous means there is no substantial variation in atomic composition through the coating and the term amorphous means there is no substantial crystallinity in the coating as measured by standard x-ray diffraction techniques. In addition, the inorganic oxide and glass-forming metal additive are preferably present in the coating in concentrations which are substantially constant through the thickness of the coating. The resulting coating is therefore very durable. 
     Because of the high level of adhesion of the inorganic coating to the surface of the plastic container of the present invention, a continuous coating is not essential. In other words, even though the coating of the present invention may be non-continuous because of scratches or fractures therein, for example, the coating will continue to effectively adhere to the substrate such as an underlying plastic bottle. The present invention can therefore provide an effective gas barrier even if the surface is highly fractured. A high gas barrier of 1.25× greater than the uncoated container can be obtained with the present invention and this barrier can even be 1.5× or preferably 2× greater than the uncoated container even when the coated container contains a pressurized fluid such as a carbonated beverage. In addition, the coated container of this invention has enhanced environmental stress crack resistance even when the container contains a pressurized fluid. 
     Furthermore, the coated container of the present invention can be made to have an equivalent gas barrier and reduced weight compared to a plastic container of similar surface area and volume and without said exterior inorganic coating. 
     The system of the present invention for making the coated plastic container comprises a vacuum cell, a container feeder, a conveyor and at least one source disposed in the vacuum cell for supplying a coating vapor. The vacuum cell is capable of maintaining a vacuum within the vacuum cell and the container feeder supplies plastic container bodies into and withdraws coated plastic containers out from the vacuum cell. The plastic container bodies each have an external surface and an interior surface defining an interior space. The conveyor conveys the plastic container bodies through the vacuum cell and the at least one source of coating vapor supplies 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 and the conveyor are structured and arranged within the vacuum cell such that the coating vapor from the at least one source deposits a thin coating on the external surface of the containers, the thin coating comprises an inorganic oxide and a glass forming metal additive and bonds to the external surface of the container bodies and the resulting coated plastic containers, when containing a pressurized fluid sealed in the interior space at a pressure of 60 psig, possess a gas barrier of at least 1.25× 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. This invention also encompasses the corresponding method of making coated plastic containers. 
     Desirably, the system and method for making coated plastic containers of this invention are continuous and can operate at a high speed and high volume to economically mass produce the coated containers. More particularly, in the system and method for making a coated plastic container of this invention, 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 passed the at least one source, and the container feeder continuously feeds the coated containers from the conveyors and withdraws the coated containers from the vacuum cell. Preferably, this system and method are automatic. The container feeder in the system and method of this invention is desirably a rotary feeder system capable of continuously and automatically feeding container bodies into and out of the vacuum cell at a high speed and a high volume while the vacuum cell maintains its vacuum. This high speed process allows the system and method of coating plastic containers to be placed in a high speed mass production process such as a beverage packaging line. 
     The coating vapor produced in the vacuum cell is desirably in the form of a plasma. A suitable device for producing the plasma is a cold cathode, also known as an electron gun. The plasma can optionally be energized with one or more antennas disposed in the vacuum cell using RF (radio frequency) or HF (high frequency) energy to form a high energy plasma. 
     Although a variety of vaporizable materials can be used to form the inorganic oxide coating in accordance with this invention as explained in more detail below, the inorganic oxide coating desirably comprises silica and glass forming metal additives such as zinc, copper, or magnesium. 
     The coating method and system of this invention also enables heat sensitive containers to be coated without significant temperature rise, and at all times maintaining a bottle temperature well below 60° C. In addition, the coating method and system of this invention enables mixtures and layers of substances to be applied which can be chosen for their color, or UV-absorbing properties, or additional gas barrier properties. Further, the method and system of this invention enables coatings, such as silica, which are fully transparent and clear, and would therefore not affect the appearance of an otherwise clear bottle. The coating materials are inert and remain solid when the plastic bottle is melted for recycling. 
     Additional functionality can be incorporated into the inorganic coating of this invention by incorporating visible light absorbing species, rendering the plastic container cosmetically more appealing. 
     The method of this invention for producing recycled content plastic comprises the steps of providing a batch plastic, at least a portion of the batch plastic comprising coated plastic containers, and converting the batch of plastic to a form suitable for melt extrusion. Each coated plastic container comprises a container body having an external surface and a coating on the external surface comprising an inorganic oxide. The coated plastic containers can be made by the method described above and desirably have a very thin inorganic oxide coating. The coating preferably has a thickness from about 1 to about 100 nm. 
     Suitable methods of converting the batch of plastic to a form suitable for melt extrusion include grinding the batch plastic to produce flakes and melting the flakes to form a melt extrudable recycled plastic. Alternatively, the batch of plastic can be depolymerized and repolymerized to form a melt extrudable recycled plastic. The recycled plastic can be melt extruded into plastic articles such as recycled content plastic containers. 
     Because of the inert nature and thinness of the coatings of the present invention, the coated containers can be processed in any conventional recycling system without modification of the process. In addition, haziness in the resulting recycled articles is avoided in the present invention because the coating forms relatively small particles during recycling. Furthermore, the coating particles in the recycled plastic are acceptable for food contact and therefore do not adversely affect the recycling effort when ground or depolymerized in the recycling process. 
     The recycling method of the present invention provides for a method of recycling coated plastic which has results heretofore unattainable. In particular, separation of coated and uncoated plastics is unnecessary whereby modifications to existing recycling systems are unnecessary or whereby extra process steps (separating coated bottles from uncoated bottles) can be avoided. Moreover, it is possible to produce a transparent plastic from coated plastic while avoiding the above-noted problem of haziness in the final recycled product. While the present invention can be used in recycling many types of plastic, it is contemplated that this invention can be used with plastic articles, such as containers or bottles and more particularly, with plastic beverage bottles. Bottle-to-bottle recycling remains unaffected with the present invention. The coating of the present invention does not interfere with the downstream injection molding or blow molding of recycled plastic. 
     The method of packaging a beverage in accordance with this invention comprises the steps of providing a coated plastic container, filling the plastic container with the beverage and sealing the plastic container after the step of filling. The coated plastic container comprises a plastic container body having an external surface and a coating on the external surface comprising an inorganic oxide. This coating provides a gas barrier and desirably is the coating described hereinabove. The gas barrier coating inhibits the flow of gas into and out of the container. For example, the gas barrier coating can protect the beverage from the flow of oxygen into the container from the outside or can inhibit the flow of carbon dioxide out of the beverage container. The method and system of packaging a beverage according to this invention is particularly useful in producing carbonated beverages. Such a method further comprises the steps of carbonating the beverage before the filling step and then sealing the beverage under pressure in the coated container. The resulting carbonated beverage has a longer shelf life because the coating on the container better holds the carbon dioxide within the container. 
     The method and system of packaging a beverage according to this invention is desirably a high speed, high volume process wherein the coated plastic containers are continuously provided, the plurality of plastic containers are continuously filled with the beverage, and the filled containers are continuously sealed. Accordingly, the method and system for packaging a beverage can form a single continuous processing line including the plastic container body production, the process for coating the plastic container, and the steps of filling the plastic containers with a beverage and sealing the plastic container after the step of filling, although such a single continuous processing line is not necessary. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The present invention will be more readily understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a partial schematic illustration of a system for coating plastic containers according to a first embodiment of this invention wherein biasing energy is used; 
     FIG. 1A is a partial schematic illustration showing the receptacle  3  and a supplemental receptacle positioned on a support  19  useful in the embodiment illustrated in FIG. 1; 
     FIG. 1B is a partial schematic illustration of a coating system similar to FIG. 1, but showing a modified form of the coating chamber in accordance with another embodiment of this invention; 
     FIG. 2A is an elevation view of an in-bottle antenna and bottle-capping arrangement before insertion of the antenna; 
     FIG. 2B is a cross-sectional view of the in-bottle antenna and bottle-capping arrangement of FIG. 2A after insertion of the antenna; 
     FIG. 2C is a cross-sectional view showing a modified form of an in-bottle antenna prior to insertion; 
     FIG. 2D is a cross-sectional view similar to FIG. 2C after insertion of the in-bottle antenna; 
     FIG. 3 is a schematic illustration of a coating system in accordance with another embodiment of the present invention using biasing energy; 
     FIG. 4 is a schematic illustration of the handling of bottles, holder, caps, antennas, air-displacing collars of the present invention; 
     FIG. 5A is a partial elevation view of a system for conveying bottles first vertically, then horizontally while bottles are continuously rotated; 
     FIG. 5B is a sectional view of the bottle bar taken along line V—V of FIG. 5A; 
     FIG. 6A is a schematic illustration of bottles moving past plasma-making and coating sources; 
     FIG. 6B is a side sectional view taken along line VI—VI of FIG. 6A; 
     FIG. 7 is a graph showing improvements in gas barrier factor with increasing content of Zn or Cu; 
     FIGS. 8A and 8B are a partial plan view of a high speed, high volume plastic container coating system in accordance with still another embodiment of this invention with the interior of the container feeder and vacuum cell exposed; 
     FIGS. 9A and 9B are a partial side elevation view of the coating system illustrated in FIGS. 8A and 8B with the evaporators and interior of the container body feeder exposed. The conveyor is not shown in FIGS. 9A and 9B; 
     FIG. 10 is a partial end elevation view exposing the interior of the vacuum cell; 
     FIG. 11 is a partial plan view of the vacuum cell housing port and feed wheel of the coating system illustrated in FIGS. 8A and 8B; 
     FIG. 12 is a partial sectional elevation view of the vacuum cell housing port and feed wheel is illustrated in FIG. 11; 
     FIG. 13 is a partial sectional elevation view of a container body feeder which forms part of the coating system illustrated in FIGS. 8A and 8B; 
     FIG. 14 is a partial plan view of the container body feeder illustrated in FIG. 13; 
     FIG. 15 is a flow chart illustrating the steps of physical recycling; and 
     FIG. 16 is a flow chart illustrating the steps of chemical recycling. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Coatings with good adhesion to a surface of a container, good gas barriers, and providing the necessary stretchability and flexibility can be produced by the methods and systems of the present invention. Throughout the present specification, a container or bottle will be described. An uncoated container is referred to as a container body. While this container body will generally be described with reference to a plastic bottle, any suitable container can be treated by the method and system of the present invention. Accordingly, soft drink bottles of various sizes, other food containers or any other suitable container can be treated using the disclosed method and system. 
     Coating System Using Biasing Energy 
     Coating System 
     FIG. 1 shows a source  1  used as typical evaporation and plasma-making system for this present invention. A conventional, water-cooled cold cathode or electron gun  2  is used to convey energy to a conventional receptacle  3 , which holds the coating material  4 . This receptacle  3  is constructed of a material suitable for melting and evaporating the particular coating material chosen, and must be both inert and resistant to the temperature necessary for generating the quantities of vapor needed. For example, for evaporating silicon, carbon has been found to be a suitable material. The receptacle  3  is supported from a receptacle holder  5 , which is water cooled or cooled by other methods. 
     A potential is connected across the cold cathode  2  and the receptacle  3 , with the cold cathode being at the negative (cathodic) pole and receptacle being at the positive (anodic) pole, so that energy in the form of a stream of electrons can flow between the cold cathode and the receptacle. By using these conventional components (i.e., cold cathode or electron gun  2  and receptacle  3 ), and by varying the position of the cold cathode  2  relative to the horizontal surface of the receptacle  3 , the proportion of energy available for plasma-making and evaporation can be adjusted. For example, in position A, a large portion of the energy is available for plasma-making, while in position B, almost all energy is used for evaporation and hardly any plasma is formed. The degree of energy to the source  1  is adjusted by the voltage V to give the particular deposition rate on the external bottle surface  6  which enables coating material  4 , after evaporation, to deposit and react completely (i.e., stoichiometrically) with the gaseous substance  7  (or mixture of substances) introduced into the coating chamber  8 , thus ensuring that no significant amounts of unreacted gas can be occluded within the coating  9 . For example, in one of the preferred embodiments, which uses silicon as coating solid  4  and oxygen as gaseous substance  7 , deposition rates onto the coating surface of 1 to 50 nm/s can give fully transparent coatings, with virtually x=2 in SiO X , while avoiding surplus oxygen (or air) and maintaining high vacuum in the coating cell (in region of 10 −5  mbar to 10 −2  mbar). 
     For producing good gas barrier results, it is beneficial to ensure that an on surface reaction between coating material  4  and gaseous substance  7  takes place after the coating material  4  has been deposited and formed a solid lattice, since the gaseous substance  7  then densifies the coating  9  by reacting into the solid lattice. The distance H between a surface  6  of a container body  10  and the receptacle  3  is important when avoiding the coating material  4  which reacts with the gaseous substance  7  before the coating material  4  is deposited onto the container surface  6 . Equally, the condition of the coating material  4  is important in securing maximum on-surface reaction. A distance H is chosen so as to give optimal use of source  1  (thus enabling it to coat as many bottles  10  as possible. Distance H is dependent on vacuum and deposition rate, but generally in region 0.50 m to 2 m. Also, increasing distance H, within the limitations described, enables high-energy plasmas to be created at source  1  without heat-damaging the container body  10 . 
     The plasma generated in the vacuum cell can be a high-energy plasma, determined by position of cold cathode  2 , voltage V, the distance between cold cathode and receptacle  3 , and the coating angle a which is desirably in the range from 0 to 70°. Optionally, biasing energy, provided by locating an antenna  11  inside the bottle or container body  10  and connecting it to an RF or HF source, can be used to energize the plasma. Depending on the material of bottle  10 , biasing energies of up to 2000 V can be used. Excessive bias voltage can be detrimental by overheating and damaging the bottle surface  6 . 
     Rotation of bottle  10  enables the bottle  10  to be coated over its entire surface at a high rate of deposition of coating material  4  while allowing time for reaction with gaseous substance(s)  7 . When coating the sidewall, the rate of deposition of coating material  4  onto the part of the surface of bottle  10 , which is directly opposite source  1  and which is the only surface receiving significant deposition of coating material  4 , can be adjusted by rotating bottle  10  at an adequate rate, so that this deposition comprises only a few molecular layers. These molecular layers can be easily reacted with gaseous substance(s)  7 , thus achieving the desired criterion of on-surface reaction with a solidified deposit, since this helps provide the required dense, continuous coating which gives good gas barrier. Also, since that part of the surface of bottle  10 , which is not opposite source  1 , can continue to react while not receiving deposition of coating material  4 , this procedure brings the whole 360° circumference of bottle  10  into the deposition/reaction cycle and reduces coating time. Therefore, correct setting of rotation rate (R) helps secure full reaction at optimal coating rate conditions. 
     Small or trace additions of certain metals in silicon dioxide and other coatings can increase gas barrier. Such metals can be described as glass-forming metal additives because they are known as additives for use in making glass. Suitable glass-forming metal additives include Ag, Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Sn, Ti, and Zn. These metals are added to form a proportion of metal-in coating  9  of 0.01 to 50%. For example, such additions to a coating  9  mainly composed of SiO 2  increase the gas barrier by a factor of 2, or more. Such metals are added either to receptacle  3 , or are provided by the sacrificial erosion of the electron emitting plate or shield  12  of the cold cathode  2 , this being constructed out of the desired metal, or mixture of metals. 
     Alternatively, as shown in FIG. 1A, a separate receptacle  16  can be provided for holding a source  16 ′ of metals. The receptacles  3  and  16  can be supported on the floor of the coating chamber  8  as shown in FIG. 1, or on a support  19  as shown in FIG. 1A or at any suitable location. The cold cathode  2  can act on the materials  3 ′,  16 ′ in both respective receptacles  3 ,  16  or two separate cold cathodes can be provided. Also, the spacing between the receptacles  3 ,  16  can be relative close as shown in FIG. 1A or they can be further apart or the spacing can be varied. 
     In FIG. 1B, an alternative embodiment of the coating chamber  8  is used. Instead of using in-bottle antennas  11  or coating cell antenna  14  or in addition to these antenna  11 ,  14 , an external biasing antenna  28  is used. This antenna  28  is for biasing during coating. Of course, this is separate to the already shown out-of-bottle antenna  14  for pretreatment. While not indicated in FIG. 1B, appropriate means are provided for holding and/or transporting the container bodies  10 . While a continuous or semi-continuous process for treating the bottles or container bodies  10  is discussed below, it should be evident that the present invention is also applicable to batch processing. 
     While not shown in FIGS. 1,  1 A or  1 B, an automatic source for supplying the material to receptacle  3  and/or  16  can be provided. These materials can be supplied as a rod or other solid structure or in any other form. It is contemplated that material in the receptacle  3  will be provided to receptacle  3  in solid form and in particular will be in a chunky or nonpowder form. By minimizing the surface area of this material, detrimental effects of oxidization can be avoided. The material in the receptacle  3  (and  16 , if present) will be a source of vapor in the coating chamber when acted upon by the cold cathode  2 . This vapor will be deposited on the bottles or container bodies  10  as will be described below. It should be noted that wiring  17  is indicated in FIG. 1A attached to the receptacle  16 . This wiring  17  can be used to supply current to the receptacle  3  and/or  16  as described in U.S. Pat. No. 5,565,248, if so desired. Of course, such wiring can be omitted. 
     When the shield or plate  12  is used as a source, the degree of erosion can be approximately controlled by adjusting distance D between receptacle  3  and cold cathode  2 , and by the degree of cooling applied to plate or shield  12  by the means for cooling  15 . This means for cooling  15  can cool one or both of the cold cathode and the plate or shield  12 . Water cooling or any other suitable cooling can be provided by this means for cooling  15 . The other main variable affecting erosion of plate  12  is the voltage V applied to the cold cathode  2 , but this is normally adjusted independently according to the plasma generation and evaporation rate requirements. 
     Coating Materials 
     The choice of coating material  4  and gaseous substance  7  depends on the process criteria (cost, coating color, degree of gas barrier necessary size of bottle and particularly the type of plastic used in the bottle). Good gas barriers have been obtained by procedures described above by means of on-surface reaction of silicon with oxygen, giving SiO x  where x is normally greater than 1.7, and normally insignificantly less than 2 and thus, glass-like transparent coatings. It is contemplated that the coating contains 0.01 to 50% of one or more of the glass-forming metal additives selected from the group consisting of Li, Na, K, Rb, Cr, Mg, Ca, Sr, Ba, Ti, Al, Mn, V, Cr, Fe, Co, Ni, Zn, Cu, Sn, Ge and In. 
     Use of metals and other gaseous substances also enables colored coatings, or UV-absorbent coatings (by choosing the reactants appropriately). More than one layer, each layer comprising a different composition, can also be beneficial, particularly when producing colored coatings, since combining colored and transparent layers enables a good gas barrier to be obtained with minimum thickness of colored coating, thus enhancing recyclability. When more than one type of substance is used as coating solid  4  it is often necessary to provide more than one source  1 , since differences in vapor pressure between substances can result in fractionation and uncontrolled proportions of each substance in the coating  9 . Furthermore, it is possible, using the systems and methods disclosed herein, to coat plastic container bodies with metals which are not oxides, but rather, are elemental metals. For example, plastic container bodies can be coated with elemental aluminum or silicon by eliminating the use of reactant gas from the vacuum cell. 
     Container Pretreatment 
     For certain plastic surfaces, surface pretreatment, for lightly activating bottle surface  6  by forming free radicals on the surface, is useful. Such pretreatment is possible using a gaseous pretreatment substance  13 , which can often be the same as the gaseous substance  7 , and at same cell pressure conditions. For some plastic substrates, it can be useful to degas the bottle surface  6  to remove absorbed moisture and low molecular weight materials. This is achieved by holding the bottle  10  in a vacuum for a period of 5-180 s. Bottles or container bodies  10  blown immediately after blow molding can be degassed relatively quickly, and location of coating process beside a blow molder is desirable. Such pretreatments can be carried out either by using the inbottle antenna  11  with RF or HF energy to create a gas-plasma on bottle surface  6 , or by connecting a coating cell antenna  14  to a DC or HF or RF source and creating a plasma within the entire cell. 
     For certain compositions of coating  9 , it is desirable to apply the coating on a bottle  10 , which during the coating process has an internal pressure significantly higher than the cell pressure. This gives improved gas barrier by enabling coating  9  to relax/contract when bottle  10  is not under pressure while also enabling coating  9  to resist cracking due to stretching when bottle  10  comes under pressure in normal use. 
     Some plastic surfaces, particularly those of PET, which is a polymer most commonly used in plastic bottles, deteriorate after blow molding due to the migration to the surface of low molecular weight components. It is important to determine the quality of the bottle surface  6  prior to coating. Under scanning electron microscope, these migrating components can be observed on bottle surface  6 , and an important quality control can thus be applied. 
     For quality control, it has also been demonstrated that Rutherford-Back-Scatter (RBS) is able to determine the thickness of very thin coatings (e.g. 50 nm) and also their composition, the latter being important when coating with more than one solid component. X-ray fluorescence also can be used to measure coating thickness, and, because this is a relatively simple process, X-ray fluorescence can be applied as an in-line quality control system after a coating machine. Finally, observing the surface of coated bottles  10  under a scanning electron microscope after these bottles  10  have been subjected to gas pressure, enables a first indicator of coating performance, since coatings  9 , with poor gas barrier performance, have tendency to crack/peel. 
     Antenna and Bottle Capping Arrangement 
     FIG. 2 shows an antenna and bottle capping arrangement, as an example. 
     Other similar arrangements achieving the same result are possible. A cap  20  incorporates a sealing ring  21 , a threaded portion  22 , a snap-in, quick-release connector  23  and a contact ring  24  for the biasing voltage which can be applied either by RF (radio frequency) or HF (high frequency). The contact ring  24  has an electrical connection  25  which has a sliding contact with the antenna stem  26 . The antenna stem  26  is mounted in a bearing  27 , which is in turn mounted inside the cap  20 , and is free to rotate within the cap. The antenna  30  has the antenna stem  26 , hinged arms  31   a ,  31   b , light antenna segments  32   a ,  32   b  and a heavy antenna segment  33 . Hinged arm  31   b  also acts as antenna for the base of bottle  10  when extended. At the base of the  30  antenna stem  26  is a ball bearing  34 , which can rotate freely, and is pressed downward by a spring  35  and a pin  36 . When antenna  30  is outside the bottle  10 , the antenna segments  32 ,  33  are folded against the antenna stem  26 , due to the action of the spring  35 , as shown in FIG.  2 A. Pin  36  has a base stop  37  and a swivel  38  to which the hinged arm  31   b  and the antenna segment  32   b  are connected. As pin  36  moves up/down, hinged arm  31   b  and antenna segment  32   b  extend outward or fold against antenna stem  26 . When the antenna  30  is inserted into the bottle  10 , the ball bearing  34  is forced to compress the spring  35  and this extends the hinged arm  31   b  outwardly from the antenna stem  36 , which erects the antenna  30  so that all its segments  32   a ,  32   b  and  33  approach the walls of bottle  10 . A gap between walls of walls of bottle  10  and antenna  30  is maintained which is as close to the walls of bottle  10  as possible, but eithout touching, and is in practice between 3 and about 15 mm. 
     Cap  20  is screwed onto the threaded finish (mouth) of bottle  10  and the gaseous content of bottle  10  is thereby sealed by sealing ring  21 . A tool (not shown), enters the connector  23  in cap  20  and provides the screw driver action for turning the cap  20  to screw it onto bottle  10 . The same tool holds the bottle  10  (until released by connector  23 ) and makes contact with the RF/HF biasing voltage on contact ring  24 . Of course, a snap-in, quick-release connector or other known connections for cap  20  instead of a screw connection could also be used. When the bottle  10  is held and turned horizontally, the heavy antenna segment  33  ensures that the antenna  30 , which has no contact with the walls of bottle  10 , is able to maintain a position facing vertically downwards and therefore acts as means for orienting the antenna to generally face the at least one source during coating. When antenna  30  is oriented while bottle  10  is rotated in vertical position, use of a magnetic material in antenna segment  33  and an external magnet, appropriately positioned, enable the antenna  30  to face in the correct direction. Accordingly, this magnet will act as magnetic orienting means for orienting the antenna when the longitudinal axis of the container is generally vertically oriented. 
     The principle demonstrated by FIGS. 2A and 2B can also be applied to a multi-segment design. In such a multi-segment design, where a plurality of antenna segments  32   a ,  32   b ,  33  and hinged arms  31   a ,  31   b  enable a folding arrangement which can pass through the finish of bottle  10  and can be erected within bottle  10  giving a 360° C. antenna-coverage of its walls. In such a case, the need for antenna orientation is eliminated and a greater portion of the bottle is subject to biasing energy, enabling shorter coating times in certain applications. 
     Moreover, apart from using the antenna  11  or  30  a back plate  18  in the vacuum cell can be provided as indicated in FIG.  1 . The bottles or container bodies  10  are positionable between this back plate  18  and the source  1 . When used, this back plate can result in the insertion of an antenna  11  or  30  into bottles  10  being unnecessary. This can speed the overall process, reduce the need to have an inventory of antennas and can provide other benefits. 
     Alternatively, a portion or all of the vacuum cell  50  or coating chamber  8  can be used as an antenna. For example, the back plate  18  can be omitted and the ceiling alone or the ceiling and some of the walls or the entire chamber  8  can be used as the antenna. Other arrangements are also possible. 
     Another potential for avoiding the antennas  11  or  30  comprises providing a magnetic source within the vacuum cell  50  as generally indicated by numeral  58  in FIG.  3 . The number of magnetic sources  58  and there location within vacuum cell  50  can readily be varied. This magnetic source  58  acts as a means for generating a magnetic field within the vacuum cell  50  wherein the field directs the coating vapor. 
     This magnetic source could alternatively be used to selectively direct the coating vapor going to the bottle surface, thereby avoiding some or all of the need to mechanically rotate or translate the bottles. This magnetic source will therefore act as means for generating a field to direct the coating vapor. 
     While still using an in-bottle antenna, FIGS. 2C and 2D show another possible type of antenna  69 . This antenna  69  is straight and therefore is more easily inserted into and removed from the bottle or container body  10 . This antenna  69  simply runs as a straight “peg” from the cap to within a few millimeters of the base of the bottle or container body  10 . This antenna  69  also simplifies the operation because no pivoting, orientation, folding-out to fit the walls of the bottle or container body  10 , etc. are needed. While antenna  69  is shown as being generally coextensive with the longitudinal axis of the respective bottle or container body  10 , it is contemplated that a skewed orientation is also possible. In other words, antenna  69  would be angled relative to the longitudinal axis of the bottle or container body  10 . In such an angled position, the antenna  69  may or may not intersect the longitudinal axis of the bottle or container body  10 . 
     Alternatively, a corkscrew antenna could also be used. This antenna would be screwed into the bottle or container body  10 , yet would be closer to the sidewalls than the straight antenna  69  without touching these sidewalls. Other possible antennas are, of course, also possible. 
     It is normally desirable to avoid coating the threaded finish of a beverage bottle, because this may affect the closure performance characteristics and because this can come in contact with the beverage and perhaps the mouth of the consumer. Although all of the coatings used in this invention are safe in contact with food, it is nonetheless desirable to restrict beverage contact to the main bottle material. Cap  20  covers the finish portion of bottle  10  and prevents the coating  9  from spreading to it. 
     Coating System and Operation 
     FIG. 3 shows one embodiment of a coating machine in accordance with this invention, which enables continuous, economic coating of the bottles. In view of the fact that bottles are inexpensive, mass produced, and often single use packages, it is important to arrive at an embodiment which provides a very low cost operation, is compact (because preferred location is beside a bottle blow molder), and is suitable for mass production (i.e. preferably continuous rather than batch processing). 
     In FIG. 3, the sequence of operation of the present invention is illustrated. Bottles or container bodies  10  will move through the various stages A through H. Initially, the bottles are supplied via conveyor  39  to a loading/unloading station  40 . The bottles or container bodies  10  can be fed immediately from a forming machine  29  to the coating system. This forming machine includes a blow molding machine, injection molding machine, extrusion molding machine or any other known machine for forming container bodies or bottles  10 . As will be described below with reference to FIGS. 7A-7C, the surface of a PET bottle, for example deteriorates over time. If the container bodies or bottles  10  are quickly coated after being formed, then potential obstructions to improved adhesion on the surface of the bottles or container bodies  10  are absent. 
     From conveyor  39 , an operator can manually move or other suitable equipment can automatically move the bottles or container bodies  10  to the loading/unloading station  40 . The conveyor  39  can feed bottles from a molding machine or any other upstream process. 
     At the loading/unloading station  40 , the bottles or container bodies  10  are placed into or removed from a holder  41 . This holder can have open interior or it can have segmented sections for receiving individual bottles  10 . The arrangement of the holder  41  will be discussed in more detail below. The holder  41  used in FIG. 3 has four bottles in two rows for a total of eight bottles. Of course, this configuration could be modified so as to meet the needs of the system. 
     The holder  41  with the loaded bottles or container bodies  10  can be manually or automatically moved from the loading/unloading station  40  at stage A to the tool station  42  at stage B as noted above. The operation of this tool station  42  will be explained in more detail below with reference to FIG.  4 . At this tool station  42 , an antenna  30 , cap  20  and an air-displacement collar  60  can be inserted into or removed from the bottles or container bodies  10 . 
     The cap  20 , antenna  30  and collar  60  will be collectively designated as “tools”. The tools as well as the holder  41  should be made of a non-gassing (low-absorbent) material whose surface cannot damage the surface of the coated or uncoated bottles or container body  10 . 
     From the tool station  42  at stage B, the holder  41  with the bottles or container bodies  10  can be manually or automatically moved into the evacuation cell  43  at stage C. Some door, air lock or other feature is provided for enabling a vacuum to be formed within the evacuation cell  43 . As will be explained in more detail below, the displacement collar  60  which had previously been applied to the bottles or container bodies  10  can be removed or reapplied in the evacuation cell  43 . Also, a vacuum is either created or released in this evacuation cell  43  as will be described below. 
     From the evacuation cell  43 , the holder  41  and bottles or container bodies  10  move into the loading/unloading table  44  at stage D. Loading of the bottles from holder  41  to bottle-carrying bars  51  is carried out on this table  44 . Also, the bottles or container bodies  10  are unloaded from the bottles carrying bars  51  back into the holder  41  as will be described in more detail below. 
     When the bottles or container bodies  10  are mounted on the bottle-carrying bars  51  at stage D, they are then passed to the degassing and pretreatment sections  45  and stage E. 
     The antenna  30  which can be within the interior of the bottles or container bodies  10  will be oriented by a magnet  46  in the degassing and pretreatment sections  45 . The bottles or container bodies  10  have their longitudinal axes generally vertically aligned when in the degassing and pretreatment sections  45  of stage E. 
     From the degassing and pretreatment sections  45 , the bottles or container bodies  10  on the bottles carrying bars  51  will move to the base coating section  47  at stage F. Then the bottles or container bodies  10  will move the sidewall coating section  48  at stage G. It should be noted that the bottles or container bodies  10  move from a generally vertical orientation in stage F to a generally horizontal orientation in stage G. This arrangement will be described in more detail below. From stage G, the bottles return to the loading/unloading table  44 . The bottles or container bodies  10  are removed from the bottle-carrying bars  51  and reinserted into the holders  41 . The holders  41  are then moved through the evacuation cell  43  at stage C to an intermediate holding position  49  at stage H. 
     Now after this general description, a more detailed description of the arrangement of FIG. 3 will now be given. First, the bottles or container bodies  10  are loaded into holder  41  at stage A as noted above. An operator can manually insert the tools, cap  20 , antenna  30  and collar  60 , onto the bottles or container bodies  10  or this step can be automatically carried out with appropriate equipment. This operation is carried out at the tool station  42  at stage B. 
     When the holders  41  and bottles or container bodies  10  are moved into the evacuation cell  43  at stage C, a vacuum will be created in this cell  43 . The collar  60  previously applied at tool station  42  during stage B will be used to evacuate the interior of the bottles or container bodies  10  prior to the evacuation of pressure from cell  43 . The purpose of collar  60  is reduce the amount of air brought into the evacuation cell  43 . Together with the holder  41  into which bottles or container bodies  10  tightly fit, the pre-evacuation of the containers or bottles  20  reduces the amount of air which must be evacuated from the cell  43 . In other words, the bottles or container bodies  10  tightly fit into the holder  41 . This holder  41  tightly fits within the walls of the evacuation cell  43  in order to minimize the amount of air exterior of the containers or bottles  10 . 
     Before or during insertion of the holder  41  with the bottles or container bodies  10  into the evacuation cell  43 , the collar  60  is utilized to remove air from the interior of the bottles or container bodies  10 . Therefore, the vacuum system for evacuating cell  43  need only evacuate the little amount of air existing in the cells exteriorly of the containers or bottles  10 . Therefore, the vacuum system capacity can be reduced. This is an important economic consideration in view of the low operating pressure of the vacuum cell  50 . This also helps to prolong the life of the vacuum system and helps to minimize the amount of energy consumed with the instant system. 
     From the evacuation cell  43  at stage C, the holder  41  with the bottles or container bodies  10  is moved to the loading/unloading table  44  at stage D. This loading/unloading table  44  is within the vacuum cell  50 . The vacuum cell  50  and the evacuated cell  43  are both connected to a conventional vacuum system (not shown). When the evacuation cell  43  reaches the appropriate pressure, various steps are undertaken including opening of door  55  to permit entry of the holder  41  with the bottles or container bodies  10 . 
     Within the vacuum cell  50 , the bottles or container bodies  10  are degassed and pretreated in section  45  at stage E. This degassing at stage E can take up to sixty seconds, for example. It should be noted that degassing of the containers or bottles  10  actually starts in the evacuation cell  43  at stage C. The degassing is completed during the pretreatment in section  45  of stage E. The bottles or container bodies  10  are moved out of the holder  41  at the loading/unloading table  44  and onto bottle-carrying bars  51  which will be described in more detail below. The bottles are moved from the loading/unloading table  44  area in stage D to the subsequent stages within the vacuum cell  10  by movement of the bottle-carrying bars  51 . 
     While a conveyor arrangement will described below for moving these bottle-carrying bars  51 , it should be appreciated that many different arrangements could be used in order to convey the bottles or container bodies  10  through the vacuum cell  50 . 
     In the degassing and pretreatment sections  45 , orienting magnets  46  can be used to orient the antennas  11  or  30  as desired, if present. The antennas could be stationary relative to a certain point on the container bodies or bottles  10  or can be movable relative to the bottles or container bodies  10 . In the degassing and pretreatment section  45  at stage E as well as in the downstream base coating section  47  of the stage F, the bottles or container bodies  10  have their longitudinal axes vertically oriented. 
     In the pretreatment loading/unloading table  44  area at stage D or in the degassing and pretreatment section  45  of stage E, heating of the bottles or container bodies  10  can be carried out if appropriate. At these stages D or E or throughout the vacuum cell  50 , radiant or infrared heaters (not shown) could be provided such that the bottles or container bodies  10  would be at an appropriate temperature. For example, this temperature could be ambient to 60° C. 
     Apart from the bottles or container bodies  10  being at an appropriate temperature to facilitate degassing, the antennas  11  or  30  with the container bodies can be used to accelerate the degassing as has previously been noted. In particular, either RF or HR energy is applied to the internal antenna  11  or  30 . Alternatively, as noted with regard to FIG. 1, a coating cell antenna  14  can be provided. DC/RF/HF energy can be applied to this coating cell antenna  14  or from an infrared source located near the bottle surface  6 . All of these features can accelerate degassing. 
     The coating process is carried out in two parts. First, there was the previously noted base coating section  47  at stage F. Then the sidewall coating section  48  at stage G completes coating of the bottles or container bodies  10 . In this base coating section  47 , the bottom or base of the bottles or container bodies  10  are coated. Then as will be described in more detail below, the longitudinal axes of the bottles are changed from the vertical to a horizontal orientation. This is achieved by increasing space between bottle bars  51 . As will be described below with reference to a fast-moving chain  53  and a slow-moving chain  52 , this reorientation of the bottles or container body  10  can take place. Throughout their vertical and horizontal orientations, the bottles or container bodies  10  are close to each other to give best utilization to the evaporators or source  1 , but they do not touch. The bottles in the horizontal orientation are then moved through a sidewall coating section  48  at stage G. As the bottles move through the section, they can be rotated about their longitudinal axis. 
     The bottles or container bodies  10  can be coated throughout movement in the sidewall coating section  48  or only in a portion thereof. The distance of the coating section  48  over which the bottles are coated can be influenced by the amount of coating desired to be deposited on the bottles. For example, various sources I can be provided in the vacuum cell  50  for supplying the coating vapor to the bottles or container bodies  10 . If a thicker external coating is desired, then more of the sources  1  could be activated as opposed to when a thinner coating is desired. Of course, other criteria can be modified in order to influence the thickness of the coating on the exterior of the bottles or container bodies  10 . 
     Similarly to the pressure in the degassing and pretreatment section  45  of stage E, the pressure in both the base coating section  47  and the sidewall coating section  48  of stages F and G can be 2×10 −4  mbar and can be in the range of 1 to 5×10 −4  mbar. It is contemplated that the base coating in stage F will take 1-15 seconds but can be in the range of up to  30  seconds. 
     The sidewall coating in stage G can take less than 30 seconds but be in the range of 2-120 seconds. The bottles can rotate from 1-300 revolutions per minute, but the upper limit depends only on practical mechanics. Typically, the bottles would rotate from 1 to 100 revolutions per minute. 
     Within the coating cell  50 , an evaporator system can be provided. This evaporator system was described with reference to FIG.  1  and will also be described in more detail with reference to FIGS. 6A and 6B. In particular, evaporators or source  1  are provided in order to provide the coating which will be deposited on the exterior of the bottles or container bodies  10 . 
     The evaporators can be arranged in rows so that the evaporator fluxes overlap their paths, giving an even longitudinal deposition rate R. This rate can be 3 nm/s and be in the range of 1-50 nm/s. The angle of contact a which was previously discussed therefore only applies to row ends and to the row cross sections where there is no overlap. This angle of contact a is indicated in FIGS. 6A and 6B and can be 30° or at least in the range of 30-60°, for example. However, as previously noted this angle should not normally be greater than 70°. 
     It is desired that the evaporators layout must result in a minimum number of evaporators or sources I with the most effective use thereof. In other words, material loss should be minimized. The presentation of bottle rows to the evaporator or source  1  can be four in a row as indicated in FIG. 3 but this number can be varied as desired. It is merely desired that the evaporator or source  1  utilization will be optimized. 
     As will be described below for FIGS. 6A and 6B, dust screens or shields  93  can be provided. These shields or dust screens should be removable and easily cleaned. They will catch particles from the evaporator or source  1  which are not adhering to the bottle surface. 
     In order to avoid the need for switching off the evaporators or sources  1  during short cycle pauses, provision can be made for swing covers or similar covers to collect coating vapors during non-coating periods of the cycle. This will reduce the dust coating of the internal coating cell. Automatic function controls and automatic detection of malfunctioning evaporators or sources  1  can also be provided. It is estimated that the parameters specified will result in a coating thickness of about 50 nm. On this basis, the evaporation rate is estimated as follows. With the weight of the bottle being 30 grams and the PET thickness being 0.35 mm, the coating thickness can be 50 nm. Therefore, the proportion coating to PET (V/V) will equal 0.00014. The Si proportion of SiO 2  (W/W) will equal 0.467. The density of the SiO 2  will be 2.5 with the density of PET being 1.3. Therefore, the weight of Si of coating will be 0.004 g/bottle. At about 3,000 bottles per hour, the Si evaporated for bottle coating only (not including losses) will be about 11.5 g with about 30 g/h including the total losses. 
     As has been described with reference to FIG. 1, the distance between the evaporator or source  1  and the bottle surface (H) can be 0.5 and be in the range of 0.1 to 2 m. It should also be possible to remove sources  1  from the vacuum cell  15  for inspection and/or maintenance without releasing the coating or vacuum. A tandem evaporator system operating through vacuum locks is one possibility. In view of this, no automatic material feed to the evaporators would be needed. Of course, such an automatic material feed could be used, if so desired. The evaporating function must be monitored by instruments and can be visible from outside of the vacuum cell  50  by means of sight glasses, for example. 
     After moving through the sidewall coating section  48  at stage G, the bottles  10  will reenter the holder  41  at the loading/unloading table  44 . This arrangement will be described in more detail with regard to FIG.  4 . From the loading/unloading table  44  at stage D, the holders  41  with the reinserted bottles or container bodies  10  will back into the evacuation cell  43  at stage C. Prior to moving into this evacuation cell  43 , the collars  60  will be placed on the containers at stage D. 
     When the holder  41  and bottles or container bodies  10  are reintroduced into the evacuation cell  43 , the vacuum can be released. Then, the holder  41  containing the coated bottles or container bodies  10  will exit the evacuation cell  43 . The holder  41  with the bottles  10  can then be slid to the intermediate holding position  49 . At this position, the entry to the evacuation cell  43  will be clear such that another loaded holder  41  with uncoated bottles or container bodies  10  can be quickly reinserted into the evacuation cell  43 . This helps to keep the continuous operation of the coating system. After evacuation cell  43  is reloaded, the holder  41  can return to stage B where the tools are automatically or manually removed. In other words, the cap  20 , antenna  30  and collar  60  will be removed from the bottles or container bodies  10 . 
     Then, at the loading/unloading station  40  at stage A, the coated bottles or container bodies  10  can be removed from the holder  41  and returned to the conveyor  39  for subsequent processing. 
     New uncoated bottles or container bodies  10  can be placed into the emptied holder  41  enabling the described cycle of operation to repeat. 
     When bottles  10  and holder  41  are viewed separately, bottles  10  first pass through stages A to G, and then return through stages C to H to A. There are two holders  41 , and these first pass through stages A to G, and return by passing through stages C to H to A. There are sufficient sets of tools to cover all bottles in stages B through H. The tools are applied at stage B and return to stage B having passed through all the stages B to H. 
     Stages D, E, F, G are housed in a vacuum cell  50 . Bottles  10  are gripped by bottle bars  51  and processed through the vacuum cell  50  by conveyor chains, one slow moving chain  52  and one fast moving chain  53 . The slow moving chain  52  pushes the bottle bars  51  in a closely packed arrangement, during the cycle of operations when the bottles  10  are held in vertical position (for degassing and pretreatment at stage E and base coating at stage F) and the fast moving chain  53  pushes the bottle bars  51  with greater bar-to-bar spacing while the bottles  20  are in a horizontal position (for sidewall coating at stage G). The bottle bars  51  run in carrier rails  54  which firmly locate and carry the bottle bars  51  as will be described in more detail with reference to FIG.  5 A. 
     The evacuation cell  53  is equipped with conventional mechanized doors  55  which open/close to enable holder  41  to enter/exit. A ceiling door  55   a  in FIG. 5 allows the collar  60  to be removed and/or reapplied) by conventional means prior to the holder  41  moving into the main section of vacuum cell  50 . The compartment above the evacuation cell  53 , where the collar  60  is held after removal, is part of vacuum cell  50 , and both this compartment and the main part of vacuum cell  50  are permanently under vacuum. Evacuation cell  43  is evacuated to enable holder  41  to enter vacuum cell  50  and is returned to normal pressure to allow holders  41  to exit the coating system. 
     Bottles  10  are conveyed conventionally along conveyor  39  to the coating machine (preferably directly from the blow molder), and to the bottle palletizing system after coating. 
     FIG. 4 shows the handling of bottles  10  and tools. Bottles  10  enter a holder  41  at stage A. Bottles  10  fit tightly into cavities within the holder  41  to reduce the air gaps as much as possible, as this in turn reduces vacuum pump duty. At stage B, a collar  60  is applied to reduce the air gaps around the necks of bottles  10  and the antenna  30  and cap  20  are fitted onto bottle  10 . The caps  20  are screwed onto the bottles  10  by a series of screw drivers which are part of a tool applicator  61 . At stage C, the holder  41  enters the evacuation cell through door  55 . Overhead door  55   a  opens to allow collar  60  to be lifted off and stored in a storage compartment  62 , within the vacuum cell  50 . At stage D, the holder  41  is elevated to the bottle bars  51  which pick up the bottles  10  by means of the snap-in connector  23  on the caps  20 . The bottle bars  51  now progress through the coating stages D to G. 
     After coating, the holder  41  is elevated at stage D to the bottle bars  51  and the bottles  10  are released into holder  41 . The holder  51  returns to the evacuation cell  43 , where the collar  60  is reapplied, and vacuum is released. Holder  41  exits to stage B, where the tool-applicator  61  descends, grips caps  20  by the snap-in connector  23 , unscrews caps  20  and lifts caps  20 , antennas  30  and collar  60  as a single unit, the collar  60  being lifted off by the caps  20 , which lock in its underside. The tool-applicator  61  and the quick release, screw driver devices, comprise conventional technology and will not be described further. 
     FIG. 5A shows details of the bottle bars, bottle turning and bottle conveying. Bottle bars  51  hold a plurality of bottles  10  in a row. In FIG. 5A, four bottles  10  are shown, as an example only. A bottle drive shaft  70  on which worm gears  71  are fitted, runs inside the bottle bars  51 , and is suspended by bearings  72  at each end of bottle bar  51 . The cap  20  acts as means for gripping the neck of the bottle or container body  10  to help hold it on bottle bar  51 . As seen in FIG. 5B, this cap  20  also covers the neck and/or threads of the container body or bottle  10  whereby coating of this area of the container body can be prevented. The bottle drive shaft  70 , also shown in FIG. 5B, is driven by bevel gears  13 , and rotates by rotating the snap-in connectors  23  which are fitted with a screw driver end piece (not shown) to thereby act as means for rotating the container bodies or bottles  10  during transport through the vacuum cell  50 . The bottle bar  51  is fitted at each end with carrier bars  74  in which it is free to swivel, due to bush bearings  75 . The carrier bars  74  are fitted with carrier wheels  76  which run in a pair of carrier rails  54 . The bottle bars  51  are conveyed by means of a drive chain  77 , to which a pall-finger  78  is attached which in turn impinges upon an extension arm  79  on carrier bars  74 . The drive chain  77  is attached to a main shaft  80  which is driven by conveyor motor  81 . A bottle rotation motor  82  drives a bottle rotation sprocket  83  which is free to slide up/down main shaft  80  by means of bearing bushes  84 . Bottle rotation sprocket  83  drives bottle rotation chain  85  which in turn drives the bevel gears  73 . 
     The bottle bars  51  are attached to a guide wheel  90  which runs in a guide rail  91 . This guide rail  91  is able to turn the bottle bar  51  from a position holding bottles  10  vertically (as shown) to a position holding bottles horizontally by means of guiding the guide wheel up a ramp  92  at the appropriate part of the conveying cycle. This switch from a vertical orientation to a horizontal orientation occurs between stages F and G. When the bottles or container bodies  10  are horizontally oriented, the bottles or container bodies  10  continue to rotate without interruption by means of bevel gears  73  while the bottle rotation sprocket  83  moves up the main shaft  80  to accommodate the new position of the bevel gears  73 . Dust screens  93  previously noted protect the main parts of the drive system. 
     FIG. 6A is a view of bottle motion past source  1 , both for base coating and sidewall coating. Bottles  10  and caps  20  are held vertically in the base coating section  47  by bottle bars  51  which continuously rotate both the bottles  10  and caps  20 . After base coating the bottles  10  are turned to horizontal position for sidewall coatings as quickly as possible (i.e. with minimum gap between base coating section  47  and sidewall coating section  48 ). The bottles are continuously rotating throughout the conveying cycle. Bottle bars  51  are designed compactly to minimize spacing between bottle rows in horizontal position. Sources  1  are positioned so as to minimize the number of sources  1  needed and according to the criteria discussed in conjunction with FIG. 1, but with some overlap as shown in FIG. 6B to ensure full coating coverage. Dust screens  93 , which are easily removable for cleaning, protect the machine parts from those deposits from source  1  which do not impinge on bottle  10 . Strip brushes with dust screens are used to separate, whenever possible, the main coating cell of vacuum cell  50  from the chains, motors, etc. used for transporting the bottle bars  51 . 
     FIG. 9 is a graph showing improved barrier effect showing the importance of coating composition to gas barrier. A small change in Zn, Cu or Mg composition can have a large effect on the barrier enhancement. 
     High Speed, High Volume System for Coating Plastic Container Bodies Overview 
     A high speed, high volume system  200  for coating plastic container bodies with an inorganic oxide barrier coating is illustrated in FIGS. 8A-16. This high speed, high volume system  200  does not incorporate a source of bias energy such as from an RF or HF source in the previously described embodiments, or utilize in-bottle antennas. This high speed, high volume system  200  is useful, however to apply the same coatings with the same materials to the same type of plastic containers as with the system previously described and illustrated in FIG.  1 . In addition, this high speed, high volume system  200  operates under substantially the same parameters as the previously described system with the exception of the use of bias energy in that system. 
     Generally described, the high speed, high volume coating system  200  comprises a continuous and automatic container feeder  203  for delivering plastic container bodies  204 , such as PET bottles, to a vacuum cell  206  which houses a continuous and automatic conveyor  209  and a source  212  of coating vapor  215 . The source of  212  of coating vapor is also referred to as an evaporator system. These basic components are described in more detail below. 
     Container Feeder 
     The vacuum cell  206  includes a housing  218  which is capable of maintaining a vacuum therein and the container feeder  203  is at least partially rotatably engaged in a port  221  at one end of the vacuum cell housing. The container feeder  203  is a rotary system which continuously and automatically supplies uncoated plastic container bodies from a source  224  of plastic container bodies through the port  221  in the vacuum cell housing  218  to the conveyor  209  inside the vacuum cell  206  while the vacuum cell maintains a vacuum inside the vacuum cell housing. The container feeder  203  supplies the plastic container bodies  204  to the vacuum cell  206  at a high speed and a high volume. The container feeder  203  supplies and the coating system  200  can coat plastic container bodies at a rate up to 60,000 containers per hour, but would normally coat at a rate necessitated by a link-up to the bottle-making system, currently in the range of 20,000 to 40,000 bottles per hour. In addition, the container feeder  203  automatically and continuously retrieves coated plastic container bodies  204  from the conveyor  209  inside the vacuum cell  206  and transports the coated plastic container bodies to a location outside of the vacuum cell such as a beverage packaging line  227 . 
     A first screw conveyor  230  continuously and automatically transports the uncoated plastic container bodies  204  from the source  224  of container bodies into the container feeder  203  and a second screw conveyor  233  automatically and continuously transports the resulting coated plastic bodies from the container feeder toward the beverage packaging line  227 . This is best illustrated in FIGS. 8A and 8B. The container feeder  203  includes a feed wheel  236  rotatably mounted in the vacuum cell port  221  for automatically and continuously feeding the uncoated plastic container bodies  204  into the vacuum cell  206  and automatically and continuously transporting the coated plastic container bodies out of the vacuum cell. In addition, the container feeder  203  includes a first exterior rotary feeder  239  for automatically and continuously feeding the uncoated plastic container bodies  204  from the first screw conveyor  230  to the feed wheel  236  and a first interior rotary feeder  242  for automatically and continuously feeding the uncoated plastic container bodies from the feed wheel to the conveyor  209 . Likewise, the container feeder  203  also includes a second interior rotary feeder  245  for automatically and continuously feeding the coated plastic container bodies  204  from the conveyor  209  to the feed wheel  236  and a second exterior rotary feeder  248  for automatically and continuously feeding the coated plastic container bodies from the feed wheel to the second screw conveyor. 
     As best shown in FIGS. 8A,  8 B,  9 A and  9 B, the container feeder  203  is mounted to a feeder frame  250  which comprises a large support plate  252  supported by four legs  254  secured to a hard surface  256  such as concrete. The support plate  252  of the feeder frame  250  forms the bottom of a feed wheel housing  260  which forms part of the vacuum cell port  221 . The feed wheel housing  260  also includes a circular top plate  262  and a cylindrical side wall  264  extending between the feeder frame support plate  252  and the top plate. The feed wheel  236  is rotatably and sealingly disposed in the feed wheel housing  260 . 
     As best shown in FIGS. 11 and 12, the feed wheel  236  includes a central hub  268  mounted to a shaft  271  with bolts  273 . The shaft  271  extends vertically through a lower guide frame  274  beneath the feeder frame  250  and through a first bearing  276  in the feeder frame plate  252  to a second bearing  277  in the top plate  262  of the feed wheel housing  260 . An electric motor, not shown, drives the feed wheel shaft  271  and rotates the feed wheel  236  in a clockwise direction as shown in FIG.  11 . The feed wheel shaft  271  rotates in the first and second bearings  276  and  277 . 
     The feed wheel  236  also includes a peripheral cylindrical structure  282  connected to the central hub  268  with spokes  285 . The feed wheel  236  has a plurality of ports  288  spaced about the periphery  282  and opening transversely outwardly from the feed wheel. Each of the ports  288  in the peripheral structure  282  of the feed wheel  236  extends from an upper annular edge  290  of the peripheral structure to a lower annular edge  289  of the peripheral structure. The feed wheel  236 , though rotatably mounted in the feed wheel housing, forms an tight seal between the peripheral structure  282  of the feed wheel and the interior of the cylindrical side wall  264  of the feed wheel housing  260 . This seal prevents air from leaking into the vacuum cell  206  even while the feed wheel  236  is rotating and feeding plastic container bodies  204  into and out of the vacuum cell. This seal is formed by an endless gasket  294  extending slightly radially outwardly from a channel running along the upper annular edge of the peripheral structure  282 , an endless gasket  296  extending radially outwardly from a channel running along the lower edge  291  of the peripheral structure, and a plurality of gaskets  298  extending from the upper endless gasket to the lower endless gasket between each port  288  in the peripheral structure. The vertical gaskets  298  extend radially outwardly from vertical channels in the peripheral structure  288  of the feed wheel  236  between the feed wheel ports  288 . Each of the gaskets  294 ,  296 , and  298  comprise strips of rubbery packing material which fit tightly against the interior of the cylindrical side wall  254  of the feed wheel housing  260 . Suitable packing material is hard wearing material with low frictional characteristics, an example being a suitable grade of polytetrafluoroethylene. 
     The ports  288  of the feed wheel  236  receive uncoated plastic container bodies  204  from the first exterior rotary feeder  239  and feed coated plastic container bodies to the second exterior rotary feeder  248  through an exterior opening  300  in the feed wheel housing  260  as shown in FIG.  9 B. The ports  288  of the feed wheel  236  feed uncoated plastic container bodies  204  to the first interior rotary feeder  242  inside the vacuum cell  203  and receive coated plastic container bodies from the second interior rotary feeder  245  through another opening  303  in the feed wheel housing  260  facing the interior of the vacuum cell  206 . This is best shown in FIG.  12 . Clamps  305  are disposed in each of the feed wheel ports  288  for grasping the necks of the container bodies  204  while the container bodies are transported by the feed wheel  236 . 
     Vacuum ports  308  are connected to the cylindrical side wall  264  of the feed wheel housing  260  between the openings  300  and  303  in the feed wheel housing  260  and are connected to vacuum pumps  310  which evacuate air from the feed wheel ports  288  as the feed wheel carries uncoated plastic containers  204  from the first exterior rotary feeder  239  into the vacuum cell  206 . Therefore, when the feed wheel ports  288  are exposed to the vacuum inside in the vacuum cell  206 , the feed wheel ports are substantially evacuated. Air feed ports  311  are connected to the feed wheel housing  260  between the second interior rotary feeder  245  and the second exterior rotary feeder  248  for supplying air to the ports  288  and the feed wheel  236  to repressurize the ports and coated containers  204  with air as the coated container bodies are transported from the second interior rotary feeder to the second exterior rotary feeder. 
     The uncoated plastic container bodies  204  are capped and sealed with caps  312  by a capper or capping device (not shown) and then partially evacuated as the feed wheel  236  transports the uncoated plastic container bodies from the first exterior rotary feeder  239  into the vacuum cell  206 . The caps  312  have a structure similar to those described with regard to the embodiment illustrated in FIG.  1  and function to seal the threaded finish of the container body  204  from the coating vapors, to provide a method for attaching the container bodies to the conveyor  209 , and to control the pressure inside the container body. The caps  312  fit tightly over the threaded opening or fitment of the plastic container bodies  204  and contain a ferrous metal element so that the plastic container bodies can be magnetically carried by the conveyor  209 . Desirably, the plastic container bodies  204  contain enough air while traveling through the vacuum cell  206  so that the container bodies are pressurized compared to the surrounding environment inside the vacuum cell. 
     The first exterior rotary feeder  239  is rotatably mounted to the feeder frame  250  outside of the vacuum cell  206  between the first screw conveyor  230  and feed wheel  236 . As best shown in FIGS. 13 and 14, the first exterior rotary feeder  239  comprises a rotatable hub  350  mounted on a shaft  353  driven by a motor synchronously with the feed wheel  236 . The first exterior rotary feeder  239  also includes a stationary bearing  356  in which the hub  350  rotates. The shaft  353  connected to the hub  350  extends to the stationary bearing  356  through the lower frame guide  274  and support plate  252  of the feeder frame  250 , through a cylinder  359  which mounts the stationary bearing to the support plate  252  of the feeder frame. A bolt  362  attaches a flange to the upper end of the shaft  353  and a cap  365  is secured to the flange above the stationary bearing  356 . The stationary bearing  356  is mounted to the cylinder mount  359  with bolts  368 . 
     The stationary bearing  356  includes a lower plate  271  mounted to the support cylinder  359  and an upper plate  374  spaced from the lower plate and mounted to the feed wheel housing  260 . This is best shown in FIGS. 9B and 13. The hub  350  rotates between the lower plate  371  and the upper plate  374  of the stationary bearing  356  and has a radially facing annular channel  377 . A plurality of pivot pins  380  are mounted vertically in the annular channel  377  and are spaced about the circumference of the hub  350 . Container body handling arms  383  are pivotedly mounted to the pivot pins  380  and extend radially outwardly from the hub  350 . 
     Each of the container body handling arms  383  includes a handle  386  pivotedly mounted to the pivot pins  380  and a reciprocable extension  389  slidably engaged with the handle  380  so that the reciprocable extension can extend radially outwardly and alternatively inwardly as the hub  350  rotates. Each of the arms  383  also includes a clamp  392  mounted to the distal end of the reciprocable extension  389  with a bolt  393 . The clamps  392  are useful for grasping the neck of the container bodies and holding the container bodies while the arms carry the container bodies. Each reciprocable extension  389  includes a guide pins  396  mounted to the extension and extending upwardly engaging grooves or tracks  403  in the underside of the upper plate  374  of the stationary bearing  356 . The tracks  403 , through the guide pins  396 , cause the extensions  389  of the arms  383  to reciprocate and move laterally. The tracks  403  are designed to direct the arms  383  as the feeder hub  350  rotates so that the arms reach out and grasp the plastic container bodies  204  from the first screw conveyor  230  and then insert the container bodies into the feed wheel ports  288 . The clamps  305  extending from the feed wheel  236  hold the necks of the container bodies  204  more tightly than the clamps  392  of the first exterior feeder  239  and pull the container bodies away from the first exterior feeder as the arms of the first exterior feeder rotate past the feed wheel. The extensions  389  of the first extension feeder arms  383  reciprocate inwardly and shift laterally as necessary to avoid undesirable collisions. 
     The first interior rotary feeder  242 , the second interior rotary feeder  245 , and the second exterior rotary feeder  248  have the same structure and function as the first exterior rotary feeder  239 . The second exterior rotary feeder  248  is also mounted to the feeder frame  250  and the feed wheel housing  260  and is positioned between the feed wheel  236  and the second screw conveyor  233 . The first interior rotary feeder  242  is mounted to the feeder frame  250  in a portion  406  of the vacuum cell housing  218 , referred to as the interior feeder housing, extending between the feed wheel housing  260  and the conveyor  209 . The first interior rotary feeder  242  is also mounted to the feed wheel housing  260 . The first interior rotary feeder  242  is positioned so that the arms  383  of the first interior rotary feeder grasp the container bodies  204  from the ports  288  and feed wheel  236  as the container bodies enter the interior feeder housing  406 . The arms of the first interior feeder  242  transport the uncoated container bodies  204  to the conveyor  209 . The second interior rotary feeder  245  is positioned adjacent the first interior rotary feeder  242  in the interior feeder housing  406  and is mounted to the feeder frame  250  and the feed wheel housing  260 . The arms  383  of the second interior rotary housing  245  grasp the coated container bodies  204  from the conveyor  209  and insert the coated container bodies into the ports  288  of the feed wheel  236 . 
     Vacuum Cell 
     The vacuum cell  206  includes the vacuum cell housing  218  and is capable of maintaining a very high vacuum in the vacuum cell housing  218 . Desirably, the coating process is run inside the vacuum cell housing  218  at a pressure within the range from about 1×10 −4  mbar to about 50×10 −4  mbar, and more preferably from bout about 2×10 −   4  mbar to about 10×10 −4  mbar. The vacuum cell housing  218  includes the feed wheel housing  260  and the interior feeder housing  406 , both of which form the vacuum cell port  221 , and also includes a coating housing  409  which forms the remainder of the vacuum cell housing. The vacuum cell housing  218  is made of a material such as stainless steel which can withstand the high vacuums produced inside the housing. The coating housing  409  includes an elongate cylinder  410  extending between a forward end plate  412  and a rearward end plate  415 . Each of the components of the vacuum cell housing  218  are joined with an air tight seal that can withstand the high vacuum inside the housing. The interior feeder housing  406  is removably attached to the forward end plate  412  of the coating housing  409 . 
     The coating housing  409  is mounted on a frame  418  disposed beneath the coating housing. The coating housing frame  418 , in turn, is mounted on wheels  421  on a track  424  fixed to the hard surface  256 . The coating housing  409  can therefore be separated from the port  221  by disconnecting the port from the coating housing and sliding the coating housing along the track  424 . This provides access to the equipment inside the vacuum cell  206  for maintenance and repair. A motor  425  moves the coating housing  409  along the track  424 . 
     A housing  427  containing apparatus for removal of the internal equipment from the coating housing  409  and is attached to the rearward end plate  412  of the coating housing. A pair of diffusion pumps  430  connected to the coating housing  409  are connected in series with a vacuum pump  433  for maintaining the vacuum inside the vacuum cell  206 . A cryogenic cooler  436  positioned outside the vacuum cell  206  cools a condenser  437 , shown in FIG. 10, inside the vacuum cell  206 . The condenser  437  condenses and freezes any water inside the vacuum cell  206  to reduce the amount of water that has to be removed by the vacuum pumps. 
     Conveyor 
     The conveyor  209 , best shown in FIG. 10, includes a generally A-shaped frame  439  slidably mounted along rails  442  extending longitudinally along opposite inner sides of the coating housing cylinder  410 . The conveyor frame  439  is mounted above the coating vapor source  212  so that the conveyor  209  carries the plastic container bodies  204  above the coating vapor source. The conveyor frame  439  forms an endless double loop track  445  which reassembles a clothespin configuration. The endless double loop track  445  of the conveyor includes an outer, lower loop  448  and an inner, upper loop  451 . An endless rail  454  runs along the lower and upper loops  448  and  451 . Container holders  457  travel along the endless rail  454  to carry the container bodies over the coating vapor source  212  four times, twice with the sides of the container bodies facing the coating vapor source and twice with the bottoms of the container bodies facing the coating vapor source. The sides of the container bodies  204  face the coating vapor source when traveling along outer lower loop  448  and the bottoms of the container bodies face the coating vapor source when the container bodies are transported along the inner, upper loop  451 . FIGS. 8A and 8B do not show all of the container holders  457  for illustrative purposes. The container holders  457  desirably extend completely around the endless double loop track  445 . FIGS. 9A and 9B do not show the container holders  457  or the container bodies  204 . 
     The conveyor frame  439 , shown in FIG. 10, includes a top plate  460 , which extends substantially the length of the coating housing  409 , and opposing side walls  463  extending downwardly from opposite longitudinal edges of the top plate and then outwardly to distal lower edges  466 . The rail  454  runs along the lower edge of  466  of the side walls  463  to form the outer loop  448 . Along the outer loop  448 , the rail  454  is angled upwardly and inwardly to orient the container bodies to slightly upwardly and inwardly so that the sides of the container bodies face the coating vapor source  212 . A pair of supports  469  extend horizontally and inwardly toward one another from opposite side walls  463  of the conveyor frame  439  proximate the top plate  460  of the conveyor frame. The conveyor rail  454  runs along these horizontal supports  469  to form the inner loop  451  of the endless double loop track  445 . Along the inner loop  451 , the rail  454  is oriented vertically so that the container bodies  204  are oriented substantially vertically with the bottoms of the container bodies facing the coating vapor source  212 . A pair of plates  472  extend substantially horizontally between the top plate  460  and the supports  469  and have grooves  479  running longitudinally for providing stability to the container holders  457  as the holders ride along the inner loop  451 . 
     A dust shield  478  is mounted to the conveyor frame  439  and extends from the conveyor frame along the side walls  463  of the conveyor frame, downwardly and outwardly to the side walls of the coating housing cylinder  410 . This shielding  478  thus separates the container housing  409  into an upper compartment  482  and a lower compartment  483 , the coating vapor  215  from the coating vapor source  212  being confined substantially to the lower compartment. The container holders  457  pass through a groove in the shielding as the container holders travel along the conveyor  209 . 
     Each container holder  457  comprises an arm  484 , a projection  487  extending from one end of the arm, a pair of spaced wheels  490  mounted to the arm adjacent the projection, and a magnetic container holder and container rotating mechanism  493  at an opposite end of the arm. The projection  487  travels through the grooves  475  in the horizontal support plates  472  of the conveyor frame  439 . The spaced wheels  490  engage the endless rail  454  of the conveyor track  445 . The magnetic container holder  493  includes a magnet which draws and holds the caps  312  placed on the threaded ends or fitments of the plastic container bodies  204 . This magnetic force holds the container bodies  204  to the container holders  457  throughout the coating process. The holder  457  rotates the container bodies  204  constantly while conveying the container bodies through the container housing  409 . 
     The entire conveyor  209  can be slid outwardly from the coating housing  409  by sliding the conveyor frame  439  along the rails  442  mounted to the coating housing after the coating housing has been retracted along the coating housing support track  424 . 
     Evaporator System for Producing Coating Vapor 
     The coating vapor source  212  comprises four evaporators  510  in series along the length of the coating housing  409  beneath the conveyor  209 . The evaporators  510  are mounted on an elongate hollow support beam  513 . The support beam  513  is, in turn, mounted on rollers  516  on a track  519  running along the bottom of the coating housing  409 . The evaporators  510  can thus be rolled out of the coating housing  409  when the coating housing is separated from the vacuum cell port  221 . This makes the evaporators  510  accessible for repair and maintenance. 
     The evaporators  510  are similar to the evaporator  1  used in the previously described embodiment and illustrated in FIG.  1 . The evaporators  510  in the high speed, high volume system  200  operate under substantially the same parameters as the evaporator  1  in the previously described embodiments. Each evaporator  510  includes a receptacle  524  containing a vaporizable material, said receptacle being constructed of a suitable material, for example carbon when evaporating silicon. Suitability of material for the receptacle  524  is primarily determined by ability to withstand the required temperature to melt and evaporate the coating material and by its inertness to the coating material. Each evaporator  510  includes a cold cathode  521  and the receptacle is electrically connected as an anode. The cathode  521  desirably comprises brass or magnesium, but also can be made of other components, preferably metals which are useful as the glass-forming metal additives which vaporize and form part of the inorganic oxide coating on the container bodies  204 . Suitable additives are described hereinabove. The receptacle  524  is separately heated by appropriate means, such as inductive or resistance heating. FIG. 10 illustrates a power line  530  to the anode. The power line to the cathode  521  is not shown. 
     Each evaporator  510  includes a housing  533  containing the anode  524  and the vaporizable solid receptacle  527 . In addition, the housing  533  contains a heater for heating the receptacle  527  to very high temperatures, 1200° to 1800° C. A suitable heater is a carbon felt resistance heater. Silicon, for example, is heated in a receptacle to a temperature of about 1500° C. The e gun or cold cathode  521  is positioned to further heat the vaporizable material in the receptacle  527  and create a plasma vapor which is emitted through an opening  538  in the housing. The resistance heater  536  is electrically powered through power lines  541  extending through the support beam  513 . 
     A pivotedly mounted dust shield  544  is selectively positionable above the evaporators  510  to protect the evaporators from coating particles which do not adhere to the container bodies  204 , and is alternatively positionable in a lower position exposing the evaporators. 
     The coating angle of the plasma vapor emitted by the evaporators  510  is desirably 30 to 60°, as described with the previous embodiment. The distance between the evaporators  510  and the container bodies  204  is desirably 0.5 to 2 m as with the previously described embodiment. 
     Operation of High Speed, High Volume Coating System 
     Generally described, the plastic container bodies  204  are coated with an inorganic oxide coating such as silica by feeding the container bodies automatically and continuously to the vacuum cell  206  with the container feeder  203 , conveying the container bodies through the vacuum cell with the conveyor  209  over the coating vapor source  212  and withdrawing the coated container bodies from the vacuum cell with the container feeder. 
     More particularly, before the plastic container bodies  204  are coated with the high speed, high volume system  200 , the evaporator receptacles  527  are loaded with a vaporizable material such as silicon and the air in the vacuum cell  206  is evacuated to a pressure of about 2×10 −4  mbar. Oxygen is fed into the vacuum cell  206  through appropriate gas inlets 
     Uncoated plastic container bodies  204  are supplied to the container feeder  203  from a source  224  of container bodies such as a plastic container blow molding line. The uncoated container bodies  204  are conveyed by the first screw conveyor  230  to the first exterior rotary feeder  239  which transports the uncoated container bodies into individual ports  288  in the feed wheel  236  through the exterior opening  203  in the vacuum cell port  221 . The ports  288  are evacuated as the uncoated container bodies  204  are transported by the feed wheel  236  to the first interior rotary feeder  242 . The first interior rotary feeder  242  grasps the uncoated container bodies  204  and transports them to the conveyor  209 . 
     The uncoated containers are capped with magnetic venting caps  312  with the capper  314 . The caps  312  allow the container bodies to remain slightly pressurized in the high vacuum environment of the vacuum cell  206 . 
     The container holders  457  carried by the conveyor  209  magnetically attach to the container body caps  312  and carry the container bodies back and forth four times through the coating housing  409  over the evaporators  510 . The container holders  457  are vertically oriented when initially picking up the container bodies. The container holders  457  and the connected container bodies  204  become reoriented as the container holders  457  travel along the endless conveyor rail  454 . 
     The silicon in the evaporator receptacles  527  is heated by the resistance heaters  536  and the evaporators  510  and the associated cold cathodes  521 . This creates a plasma vapor comprising evaporated silicon and small amounts of evaporated metal additives such as zinc, copper, or magnesium, which are evaporated from the cold cathodes  521  themselves. As the container bodies  204  pass over the evaporators  510 , the material in the plasma vapor deposits on the exterior surface of the container bodies and reacts with the oxygen in the coating housing  409  to form a thin, durable inorganic oxide coating on the exterior surface of the container bodies. The caps  312  on the threaded openings or fitments of the container bodies leave the threaded openings or fitments uncoated. 
     The conveyor rail  454  first carries the container bodies  204  on a first pass over the evaporators  510  with the sides of the container bodies facing the evaporators. The container holders  457  constantly rotate the container bodies  204  throughout the conveying and coating process. Next, the container holders  457  carry the container bodies  204  along one side of the inner loop  451  on the conveyor rail  454  on a second pass over the evaporators  510 . On the second pass, the container holders  457  and container bodies  204  are vertically oriented with the bottom of the container bodies facing the evaporators  510  to coat the bottom of the container bodies. Next, the container holders  457  follow the conveyor rail  454  along the other side of the inner loop  451  on a third pass over the evaporators  510 . Like the second pass, the container holders  457  and container bodies  204  are vertically oriented with the bottoms of the container bodies facing the evaporators  510 . On the fourth and last pass over the evaporators  510 , the container holders  457  follow the conveyor rail  454  along the other side of the outer loop  448 . On this fourth pass, the conveyor rail  454  reorients the container holders  457  and the container bodies  204  so that the sides of the container bodies face the evaporators  510 . 
     The coated container bodies  204  are then returned to the vertical position and grasped by. the arms  383  of the second interior rotary feeder  245 . The second interior rotary feeder  245  transports the coated container bodies  204  to the ports  288  in the rotating feed wheel  236 . The feed wheel  236  transports the coated container bodies  204  to the second exterior container feeder  248  while air feed ports  311  repressurize the feed wheel ports  288 . The second exterior rotary feeder  248  grasps the coated container bodies from the ports  288  of the feed wheel  236  through the exterior opening  300  and transport the coated container bodies  204  to the second screw conveyor  233  which conveys the coated container bodies towards the beverage packaging line  227 . 
     The beverage packaging line  227  can be a conventional beverage filling and sealing process. The coated container bodies are first filled with a beverage and then sealed. The containers can be filled with a variety of beverages including alcoholic beverages such as beer and non-alcoholic beverages such as carbonated beverages, water, juices, sports drinks, and the like. The beverages can be sealed under pressure in the container. Carbonated beverages, for example, are sealed under pressure. The containers made according to this invention provide a barrier to carbon dioxide and therefore hold carbon dioxide within the carbonated beverage container. 
     Recycling 
     The coated containers of this invention described above are particularly suitable for recycling. This invention therefor encompasses a method for producing recycled content plastic comprising the steps of providing a batch plastic, at least a portion of the batch plastic comprising coated plastic containers, and converting the batch plastic to a form suitable for melt extrusion. The coated plastic container&#39;s for recycling comprise a plastic container body having an external surface and a coating on the external surface comprising an inorganic oxide. Two suitable recycling processes are described in more detail below. 
     FIG. 15 is a flow chart illustrating a physical recycling process. In recycling, either physical recycling or chemical recycling are normally carried out for plastic containers. In physical recycling, a batch of plastic is provided as indicated in step  100 . While this plastic can include a single type of item, it is contemplated that both coated and uncoated plastics will be provided. In a conventional process indicated in step  102 , these coated and uncoated plastics must be separated. This can be a labor intensive step and will result in increased costs for recycling. 
     With the instant invention, this separating step  102  can be avoided. In particular, step  104  indicates mixing of coated and uncoated containers. While this step can certainly be done at the recycling station, it is contemplated that the actual mixing could take place prior to the arrival of the plastic at the recycling station. For example, when the plastic is picked-up by a refuse vehicle and taken to the recycling center, such mixing could then occur. An advantage of the instant invention is that when plastic to be recycled is mixed with coated plastic being with non-coated plastic, separation of these two plastics is unnecessary. In practice, this is, in fact, impracticable. Accordingly, when introducing coated containers into the recycling steam, the recycling process is unaffected. 
     As in a conventional process, the mixed plastics are ground into flakes in step  106 . An optional step of washing the flakes  108  can be carried out. In fact, a washing step could occur at many other times during the process. 
     After the step of washing  108 , if it is carried out, or after the step of grinding  106 , the ground flakes are melt extruded at step  110 . A step of forming  112  then occurs which merely indicates that something is done with the extrusion. For example, pellets, flakes or other configured plastics could be melt extruded and then blow molded or injection molded. Many other uses for the recycled plastic are possible. The blow molded or injection molded plastic can be reused for containers and in particular, can be used for beverage containers. In fact, the batch plastic initially provided in the method at step  100  can be plastic beverage containers whereby bottle-to-bottle recycling is possible. Of course, the type of plastic handle and the output of the recycling process is not limited. 
     Apart from the steps of physical recycling, the instant invention is also applicable to a chemical recycling process as shown in FIG.  16 . Again, plastics are provided in a step  114 . Conventionally, a separating step  116  was necessary. The instant invention avoids such a separating step  116 . Similarly to the above-described physical recycling, a mixing step  118  for coated and uncoated plastic is indicated. This mixing can take place at the recycling station or prior to the plastic&#39;s arrival at this station. 
     In chemical recycling, the plastic is depolymerized by conventional processes as indicated in step  120 . To indicate the flexibility of the instant invention, it is contemplated that separated coated and uncoated plastic could be provided in the step  114 . These separate plastics would be separately depolymerized in step  120  but would be mixed together in step  122 . This optional mixing step  122  is merely to indicate the flexibility of the instant invention. 
     After the plastic is depolymerized, it is repolymerized in step  124 . This plastic can then be formed into a desired article such as by blow molding or extrusion molding as indicated in step  126 . Similarly to the physical recycling process, the chemical recycling process can handle and produce many types of plastics. For example, bottle-to-bottle recycling is possible. 
     Another benefit to the recycling process of the instant invention is that haziness in the final recycled product is avoided. Because relatively small particles are used in the coating, a haze in the finally produced recycled product can be avoided. Moreover, the coating is acceptable for food contact and therefore will not adversely affect the recycling efforts when ground or depolymerized in the recycling processes. 
     The plastic produced in either recycling process can be injection molded or blow molded as noted above. Even if a coated plastic is initially introduced in the recycling process, the coating of the present invention will not interfere with the downstream injection molding or blow molding processes. 
     While the particular physical and chemical recycling have been discussed, it should be appreciated that the instant invention can also be applied in other types of recycling processes. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.