DE102016124209A1 - Coating device and coating method for plastic containers - Google Patents

Abstract

The invention relates to a coating device for containers made of a dielectric material, in particular for plastic containers, having at least one first electrode and at least one second electrode, which are arranged opposite one another, and a Medienzuführeinrichtung, wherein the first electrode and the second electrode each have a surface conformal electrode surface and the electrode surfaces each face one of two opposing surfaces of a container wall of a plastic container to be coated and each extend over at least one planar portion of the associated surface, at least one first electrode held with its electrode surface at a vertical distance to the associated surface and at a constant distance is movable relative to this surface, and located between the electrode surface of the first electrode and the associated surface volume Entla forms training space in which forms a dielectric barrier discharge surface during operation of the coating apparatus, and a coating method for plasma-assisted deposition of permeation-reducing or other functional layers

Description

The invention relates to a coating apparatus and a coating method for producing permeation-reducing layers on plastic containers.

For plastic packaging materials must be used for the long-term storage of perishable goods (food, pharmaceuticals, medical and biological products), for volatile goods (carbonated drinks, fuels, colors, aromatic products) and for items susceptible to corrosion (eg electronic components) Measures are taken to reduce permeation, which act as possible against the delivery of plastic components to the packaged.

Depending on the application, this relates to the permeation of oxygen, water vapor, carbon dioxide, hydrocarbons and / or aromas. Sophisticated solutions for coating with permeation-reducing materials (aluminum, SiO ₂ , Al ₂ O ₃ , amorphous carbon, etc.) in high vacuum (PVD, physical vapor deposition, sputtering, sputtering) are particularly suitable for film-type packaging materials, see HC Langowski in G. Blasek, G. Bräuer (ed.): Vacuum Plasma Technologies, Bad Saulgau: Leuze Verlag, 2010.

In particular, the growing demand for plastic containers, which limit the use of heavy and expensive metallic or glass packaging, makes a permeation-reducing equipment of three-dimensional plastic packaging such as cans, buckets, trays and tanks more and more interesting.

Are known technical solutions (eg., Plastic pipes for hot water supply) with multi-layer shell structure with z. As an internal aluminum foil or EVOH layer, which is rather unsuitable for massively required container for cost reasons. For small volume polyethylene terephthalate (PET) beverage bottles, the inner and / or outer surface will be thick with a low pressure PCVD (Low Pressure Plasma Chemical Vapor Deposition, LP-PCVD) to reduce oxygen and / or carbon dioxide permeation about 20 nm thick SiO ₂ -like layer provided ( DE 3 632 748 A1 , see also H. Grünwald in the publication cited above). For this purpose, the bottle is evacuated to low pressure (1 to 100 Pa), an SiO _2- supplying vaporous precursor material (precursor) is added and briefly ignited a microwave gas discharge, which fills the container volume. The precursor is fragmented and a (plasma polymer) layer separates out.

The above-mentioned high vacuum methods are for large volume plastic containers (eg 1000 cm ³ and much larger) and - especially in the case of an inner coating - for plastic containers with a large ratio of depth or height to the smallest width expansion (aspect ratio) and one with the Floor area comparable large Einfüllöffnungsfläche consuming and too expensive for highly productive inline systems for low-cost mass products, however, because they require vacuum chambers, locks, valves, high vacuum generator, movement and transport devices, inter alia

By means of LP-PCVD, large vessels can be relatively easily coated on the outside, but they also require productive and thus expensive inline systems with a similarly complex vacuum technology. However, these are even more complex, although or preferably the interior of large volume, usually thin-walled container (wall thickness usually less than 1 mm) with a large Einfüllöffnungsfläche and with a large aspect ratio (greater than 1) to be coated. The LP-PCVD technology with a productive in-line system is therefore limited to rather small-volume containers with a large Einfüllöffnungsfläche, but a small aspect ratio (shallow bowls, bowls, cups, etc.) and on small-volume bottles (usually up to 500 ml) ,

The main disadvantage of high-vacuum and low-pressure inline systems for the permeation-reducing coating large-volume container with a large Einfüllöffnungsfläche and rather large aspect ratio is thus in the considerable investment costs that prevent massive, cost-effective production of such plastic containers. Added to this is their poor integrability in the production process of the plastic containers, especially in the case of the predominantly applied injection molding process with its short cycle times. But there is a great need in the packaging sector here.

This implies the need for a process and associated equipment for a low cost, high productivity, permeation reducing coating of plastic containers of any cross sectional shape having a fill opening area equal to or greater than the bottom area, and especially large volume plastic containers having an aspect ratio greater than one.

It is therefore obvious, instead of the low-pressure PCVD (LP-PCVD), to use the increasingly widespread atmospheric-pressure PCVD (Atmospheric Pressure PCVD, AP-PCVD) methods, which by their nature require no complex and expensive vacuum systems and moreover simply can be integrated into a continuous production process.

The AP-PCVD methods utilize plasma sources that produce a plasma at or near atmospheric pressure in a working gas and to which a film-forming precursor material is added directly or by means of a carrier gas. Typical representatives are the atmospheric pressure plasma jets (APPJ), see z. BBSE Babayan et al., Plasma Sources Sci. Technol. 10 (2001), pp. 573-578; U. Lommatzsch, J. Ihde, Plasma Sources Sci. Technol. 6 (2009) 10, p. 642-648; and the patents WO 1999 0 20809 A1 . WO 0 132 949 A1 . US 6,194,036 A1 . WO 20 080 082 A1 and DE 60 101 747 A1 , They generate a non-thermal plasma in a plasma nozzle by pulsed arc discharges or by high frequency or microwave discharge or by dielectric barrier discharges (DBE), whereby the plasma together with the added precursor through the plasma gas to the surface to be coated (substrate) is moved (remote plasma). Since the areas acted upon by the plasma are small, usually about 1 cm ² or less, large areas can only be coated by a bidirectional relative movement between the source and the substrate, which is the case for large areas of large-volume plastic containers for integration into highly productive injection molding processes with long coating times connected is. Although this can be reduced in principle by using arrays of such Plasmajets and multi-line operation, but the effort in the voltage, gas and Precursorversorgungen and in the realization of relative movements increases significantly and in particular the economic internal coating of such large plastic containers is thus problematic for cost reasons until impossible.

The activation and coating of large-area, but even substrates such as plastic plates and plastic or textile fabric webs is known and widespread using a dielectric barrier discharge, in which a plasma between a grounded electrode and a small distance (usually less than 2 mm) planar barrier electrode is generated, wherein at least one of the electrodes is rod, bar or roller-shaped and one or both electrodes are provided with a dielectric (usually ceramic) coating and the excitation of the plasma is usually by a sinusoidal low or high frequency high voltage. The precursor for the deposition of a layer is introduced into the discharge space between the electrodes. SA Starostin et al., Plasma Process. Polym. 4 (2007), p. 440-444, describe the coil coating with a SiO ₂ -like layer.

In the DE 37 05 428 A1 are a method and an arrangement for surface pretreatment and coating of plastic containers with a comparatively small filling opening area by means of a corona discharge (the terms "corona discharge" and "barrier discharge" are often not clearly distinguished and often used synonymously) described in which a bottle-like plastic container to be coated is arranged in a special molding as a counter electrode to the corona electrode. This is brush-like, adapted to the container shape and arranged movable in the container. The working gas and the precursor are supplied to the entire container volume via the electrode. With the help of the corona discharge, a layer is applied to the interior of a bottle-like plastic body. Under the conditions described in this application, the discharge is naturally streamer-like and very heavily filamentated. The result is an inhomogeneous to porous layer morphology that is not suitable for effective permeation reduction. This arrangement has a high volume use of working gas and precursor material.

The invention is based on the object, a novel, suitable for mass production, flexible and cost-effective method for producing a permeationsmindernden layer on plastic containers of any cross-sectional shape with a Einfüllöffnungsfläche that is equal to the floor area or greater than this, and in particular large-volume container with an aspect ratio greater than 1 to develop and to provide an associated structurally simple and integrable in an injection molding process coating system, which operates at atmospheric pressure and avoids the significant disadvantages of the vacuum process.

The object is achieved by the device side by the features of independent claim 1 and the method side by the features of independent claim 9. Further expedient embodiments of the invention are the subject of the dependent claims.

Proposed is a coating device for plastic containers of any cross-sectional shape, in particular with a Einfüllöffnungsfläche that is greater than or equal to a bottom surface, and in particular for large-volume plastic containers with an aspect ratio greater than or equal to 1, to reduce the gas permeation through the container wall, with at least one first electrode and at least a second electrode, which are arranged opposite one another, and a media supply for working gas, carrier gas and precursors including reactive gas (s) or mixtures thereof, the first electrode and the second electrode each having an electrode surface and the electrode surfaces each face one of two opposing surfaces of a container wall of a plastic container to be coated and each extending over at least a planar portion of the associated surface, at least one first electrode held with its electrode surface at a perpendicular distance to the associated surface and at a constant distance relative to this surface is movable, and a volume located between the electrode surface of the first electrode and the associated surface forms a discharge space in which a dielectric barrier discharge forms in a planar manner during operation of the coating device, whose plasma interacts with the container surface and out of the layer upon precursor supply he follows.

The container wall of the plastic container to be coated serves as a dielectric barrier between the electrodes. The flat design of the discharge ensures a uniform coating with high speed.

According to a first embodiment of the coating device, the electrode surface of a second electrode in the form of a plastic container receiving positive fit die or a plastic container positively filling core is executed and the second electrode and the plastic container on the one hand and the first electrode on the other hand are relatively movable.

According to a second embodiment of the coating apparatus, the electrode surface of a second electrode is also held at a perpendicular distance from the associated surface and the first electrode and the second electrode on the one hand and a plastic container inserted into the coating apparatus on the other hand are movable relative to each other. As a result, usable discharge spaces are formed on both sides of the container wall for plasma treatments and / or plasma-supported coating.

In a further embodiment of the coating device, the media supply device is integrated into the first and / or second electrode and has in the region of the first and / or second electrode surface an outlet opening or a plurality of outlet openings distributed over the electrode surface. This allows gases and precursors directly into the volume located between the electrode and the container wall, i. H. the discharge space of the dielectric barrier discharge, are introduced, so that the consumption of these media can be reduced to a minimum.

In addition, it may be provided in the proposed coating device that a dielectric cover element is arranged exchangeably on at least one electrode surface.

In an advantageous development of the proposed coating device, two or more electrodes are arranged on a common holding device, or at least one electrode has two or more electrode surfaces. This embodiment allows a coating with the highest efficiency and shortest cycle times.

Furthermore, the proposed coating device contains at least one drive device for generating the relative movement described above and / or at least one media distribution system for gases and Precursor / s and / or at least one device for controlling the temperature of the feeds for the media and / or at least one suction device for the extraction of gases and optionally resulting reaction products and / or at least one housing which accommodates at least the electrodes and the power supply required therefor, as well as the plastic vessel to be coated. Each of these devices can also be operatively connected to a control device, which controls the parameters of a running in the coating apparatus working method such as flow rates of the media used, temperatures, relative velocities u. a. controls.

With the proposed coating device, a coating process for plastic containers of any cross-sectional shape, in particular with a Einfüllöffnungsfläche that is greater than or equal to a bottom surface, and in particular for large volume plastic containers with an aspect ratio greater than or equal to 1, to reduce the gas permeation through a container wall, can be carried out advantageously in which at least one layer of a coating material is produced on at least one surface of the container wall by introducing a working gas and producing a dielectric barrier discharge at atmospheric pressure over at least one surface of the container wall, at least one precursor is introduced into the region of the discharge (discharge space) and into one Layer material is deposited, which is deposited on the surface of the container wall, wherein the two electrodes, a pulsed or sinusoidal low- or high-frequency High voltage applied, the electrical discharge generated as a uniformly over at least a partial surface of the surface extending dielectric barrier discharge and is guided over the surface to be coated.

In one embodiment of the proposed coating method, the at least one precursor passes through the first and / or second electrode into the region of the dielectrics Barrier discharge initiated. Separate media supply means in addition to the electrodes can thus be dispensed with, and the media are fed directly into the discharge space.

It can further be provided that the precursor is mixed before being admitted into the discharge space with the working gas and / or brought to a predeterminable temperature. Good mixing and tempering of the media involved in the plasma generation and the layer deposition contribute to a homogeneous coating and short reaction times.

In addition, the proposed coating method can be designed such that at least one surface of the container wall or a layer already deposited on the surface of the container wall is activated before the inlet of the at least one precursor by the action of the plasma of the dielectric discharge. In this way, the adhesion of the subsequently deposited layer can be significantly improved.

Alternatively or additionally, the proposed coating method can be configured such that the speed of the process sequence is increased by simultaneously generating a dielectric barrier discharge over at least two partial surfaces of the container surface and at least one activation process and at least one coating process and / or at least two simultaneously generated dielectric barrier discharges and / or. or at least two different coating processes are performed.

For reasons of labor and environmental protection, the proposed coating method can be designed so that residues of precursors and gases as well as possibly formed reaction products are sucked in the area around the plastic container.

In the coating method according to the invention for coating surfaces of a plastic container of any cross-sectional shape with a Einfüllöffnungsfläche equal to the floor area or greater, and in particular large-volume container with an aspect ratio greater than 1, to reduce the gas permeation through the container wall by means of at least one planar atmospheric pressure plasma source At least one permeation-reducing layer or a permeation-reducing layer system of two or more layers is produced on one surface side or on both surface sides of the container wall and the container bottom of the plastic container. The layer (s) are / are prepared by means of one or more planar atmospheric pressure plasma sources with the aid of one or more gaseous or vapor or aerosol-like state liquid or solid precursor materials under controllable process conditions at atmospheric pressure preferably on the inner (inner coating) and / or outer, surface of the plastic container (outer coating) applied. Since the electrodes and thus the discharge between them are formed flat, in comparison to plasma nozzles (APPJ) a significant reduction of the coating time and thus a significantly improved manufacturing process compatibility is possible.

With the help of the novel flexible method, it is possible for the first time, a permeation-reducing layer on preferably large-volume plastic containers of any cross-sectional shape with a Einfüllöffnungsfläche equal to the floor area or larger, and in particular large-volume container with an aspect ratio equal to or greater than 1, cost in one To realize atmospheric pressure process and to use it in a highly productive mass production.

It should be noted that also plastic containers with an aspect ratio of 1 and well below can be coated. In addition, the coating of containers made of a different dielectric material is possible.

In the apparatus according to the invention for coating surfaces preferably large-volume plastic containers of any cross-sectional shape with a Einfüllöffnungsfläche equal to the floor area or greater, and in particular bulky containers with an aspect ratio greater than 1, to reduce the gas permeation through the container wall are one or more planar Atmospheric pressure plasma sources used, which use a Dielectric Barrier discharge at atmospheric pressure. In this case, the plastic container to be coated is arranged between a flat electrode (barrier electrode) carrying a high alternating voltage and a flat grounded counterelectrode. At least the discharge-relevant parts of the electrodes are assumed to be electrically conductive and therefore equipotential.

For the inner coating of the plastic container is positively arranged in a lying on ground, forming the counter electrode die, wherein the function-related distance of 0.5 to 10 mm, preferably 1.5 to 2 mm, is set to the barrier electrode.

For the outer coating, the plastic container is arranged in a form-fitting manner on a core lying at ground potential.

The barrier electrode for the inner or outer coating can either be of relatively small area (for example, round, diameter 3 to 5 cm) or be formed in the form of a beam (some 100 cm ² ) in conformity with the wall surface over the longitudinal extent of the plastic container. The wall to be coated or the bottom of the plastic container to be coated form in a particularly advantageous manner the dielectric barrier required for the discharge. The space between the barrier electrode surface and the opposite container wall is the discharge space of the dielectric barrier discharge, in which the plasma is generated.

A pulsed or sinusoidal AC voltage (a few kV up to a few 10 kV, frequency up to a few 10 kHz) is applied to the barrier electrode inside and / or outside the container, thereby igniting the dielectric barrier discharge. The height of the alternating voltage depends on the distance between the barrier electrode and the container wall, on the precursor material and flux, and on the gas type and flow through the discharge space. For polypropylene (1 mm thick), 2 mm distance and 3 to 5 l / min argon flow, it is according to experience at least 3 kV. In the coating method according to the invention, it is possible to replace the barrier electrode in a container contour conforming manner with a dielectric (eg a ceramic or a plastic having a dielectric constant preferably well above 1) as a further dielectric barrier (not shown in the following figures) to homogenize the barrier discharge.

It is advantageous if, in the method for coating in the space between the container wall or the container bottom and a voltage-conducting barrier electrode conforming to this, a defined working gas or working gas mixture flows under atmospheric pressure, in which the dielectric barrier discharge produces a plasma. This plasma, the layer composition determining precursors are mixed directly or via a carrier gas or a carrier gas mixture. The precursors also include the reactive gases (for example oxygen, nitrogen, hydrocarbons or hydrogen) suitable for the deposition of a specific layer composition (oxides, nitrides, carbides and the like).

The gas-precursor mixture flows into the discharge space via openings in the surface of the barrier electrode facing the container wall or the container bottom. Volatile reaction products are discharged laterally and sucked off. The openings are arranged linearly or flat or formed as a sieve. They are the result of a media distribution system adapted to the requirements of a uniform coating.

In the coating process, for better layer uniformity on the plastic container to be coated, the barrier electrodes can be moved relative to each other at the same functional distance.

In particular, the relative movement in the method for producing a coating in rotationally symmetrical plastic containers can be carried out preferably by rotation of the die or of the core together with the plastic container, with flat or partially planar wall or bottom surfaces or with arbitrary container geometry (eg also an oval ) In addition, even a guided, translational relative movement of the barrier electrode can be realized.

The inner or outer coating can be carried out simultaneously by a combination of bar-shaped barrier electrodes for container wall and container bottom.

For the inner coating, the barrier electrode may be designed as a solid core electrode conforming to the container inner wall, expediently segmented for evacuation of residual gases and possibly volatile reaction products of the PCVD process, or designed with adapted openings and channels for gas conduction, or it may be used for external coating Container outer wall conforming die formed, which is structured analogous to the solid core electrode and how it has the function-related distance between 0.5 and 10 mm, preferably 1.5 to 2 mm, to the container wall.

The coating of the container base rotationally symmetrical plastic container can be done with a small-area barrier electrode, which is moved radially, or with a radially aligned beam electrode, wherein the plastic container is rotated and the media supply is controlled position-dependent. For non-rotationally symmetrical plastic containers, the barrier electrodes are moved over the bottom surface.

Furthermore, in the method for coating the container bottom, rotationally symmetrical plastic container having a small-area barrier electrode, the container as a whole can rotate, wherein the barrier electrode is preferably moved radially. In this case, the amount of precursor per time (flow) or the rotational frequency of the container or both can be controlled position-dependent.

The coating method can also be carried out in such a way that rotationally symmetrical plastic containers are rotated during the coating of the container bottom by means of a radially oriented bar-shaped barrier electrode and the plastic container is rotated the amount of precursor is supplied position-dependent per time (flow).

For a high-quality, defect-reduced coating, a homogeneous discharge is sought. As is known, by selecting the working gas or working gas mixture and the exciting pulsed or sinusoidal AC voltage (amplitude, frequency, power) a little filament discharge can be achieved.

In the novel coating device, the barrier electrode can also be repeatedly, z. B. wing or star-shaped, which can shorten the coating process.

It may also be of particular advantage if the cavity of the injection mold of the plastic container to be coated itself is used as an electrically conductive die for coating the plastic container.

In a special process training, metal-organic precursors or silicon-hydrogen compounds can be used together with reactive gases (oxygen, nitrogen, ammonia, hydrocarbons) for glass ceramic-like layers for the production of permeation-reducing layers. In a specific embodiment, organosilicon compounds are used as precursors to deposit SiO ₂ -like plasma polymer layers. From aliphatic and cyclic, in particular aromatic hydrocarbons, amorphous carbon layers (a: CH or DLC layers) can be deposited as permeation-reducing layers, smoothing and / or protective layers.

It is also possible that from p-xylene or di-para-xylylene plasma parylene layers as permeation-reducing layers, smoothing and / or protective layers are deposited. For the deposition of SiO ₂ -like layers can be used as working gases noble gases (for cost reasons, preferably argon), air or nitrogen and as a carrier gas for the precursor preferably argon or nitrogen and for the deposition of carbon or parylene preferably argon or nitrogen.

The dielectric barrier discharge in the coating device can be used in a particularly advantageous manner for the activation of the plastic container surfaces prior to coating or already deposited layers. For this purpose, argon is usually used without or with a reactive gas additive (oxygen, nitrogen and the like).

In general, the coating process can then be carried out in such a way that an activation of the plastic container surface takes place before a coating or after a first activation of the plastic container surface a functional intermediate layer (eg for adhesion, smoothing, tension compensation) is applied before a barrier layer is deposited becomes. As options but also one or more further, possibly also graduated intermediate and barrier layers can be applied. Thereafter, if necessary, after a renewed activation - a cover layer with special application-relevant properties such. As a cover layer for scratch and wear reduction or one with a special chemical resistance, eg. As against water, neutral, basic or acidic substances or organic solvents, or a cover layer with improved or reduced wettability or other functionalities are deposited.

Furthermore, in a particular embodiment of the method according to the invention and taking into account specially adapted process parameters, it is possible to position the plastic container to be coated between the barrier electrode and counterelectrode in a function-dependent distance for the barrier discharge in such a way that dielectric barrier discharges are generated in both discharge spaces thus created which plasma-assisted processes (activation, coating) on the inside and on the outside of the plastic container can be realized, which allows in a particularly time-effective manner both an inner and outer coating in one process step. In a process step so the outside of the plastic container can also be coated or activated for subsequent gluing, painting or printing, while the inside is coated.

The invention will be described below with reference to the 1 to 8th explained.

The 1 schematically shows a coating device 1 for the surface of the container wall 3 of a plastic container 2 with a round cross-section with a small-area, surface-conforming barrier electrode 5, as in 1A and also an embodiment of the coating device 1 with a bar-shaped, surface-conforming barrier electrode 6 according to FIG 1B with a simultaneously enclosed media distribution system 16 with views belonging to the individual views.

The plastic container 2 is positively inserted in a die 8, which is at ground potential 15. This is a rotationally symmetrical plastic container 2, which during the Coating process about the rotation axis 14 rotates. The actual discharge space 10 is formed between the surface defined by the dimension of the respective barrier electrode 5 or 6 and the opposite surface of the container wall 3. On the small-area, surface-conforming barrier electrode 5 or on the bar-shaped, surface-conforming barrier electrode 6 there is a voltage supply 11 via which the high pulsed or sinusoidal AC voltage is applied. The barrier electrode 5 or 6 is positioned and moved via a guide arm 12. At the same time, in this embodiment, the gas-precursor mixture is supplied via a channel formed in the interior of the guide arm from a media supply device 13.

By rotation of the die 8 about the axis of rotation 14, the surface of the container wall 3 to be coated is moved past the barrier electrode 5 or 6 and coated (or activated). In the execution according to 1B the surface of the container wall 3 is coated simultaneously over its entire height, ie the barrier electrode 6 can be fixed during the entire coating process, while the plastic container 2 rotates with the die 8. In contrast, according to the 1A the barrier electrode 5 controlled by the guide arm 12 height method. In the side view of 1B which shows a sectional view, the formation of a media distribution system 16 for the gas-precursor mixture which is possible in the interior of the bar-shaped surface-conforming barrier electrode 6 is merely indicated.

In the 2 is a device for bottom coating of the container bottom 4 by means of a small-area, surface-conforming barrier electrode ( 2A ) and a bar-shaped surface-conforming barrier electrode 6 with a simultaneously enclosed media distribution system shown schematically ( 2 B ). In the execution according to the 2A the barrier electrode 5 must be moved radially controlled for coating. In the second embodiment, the coating takes place over the entire radius of the container bottom 4. In 2 B is indicated inside the bar-shaped conformal barrier electrode 6, the media distribution system 16 for the gas-precursor mixture.

How out 3 can be carried out in a particularly effective embodiment, the bar-shaped, surface conformal barrier electrode for coating rotationally symmetrical plastic container 2 as a combined barrier electrode 7. Here, during the rotation of the die 8 about the axis of rotation 14, the coating of both the surface of the container wall 3 and the container bottom 4 takes place at the same time. The barrier electrode may optionally be in one piece (as shown) or else consist of two or more parts.

4A schematically shows a device for coating rotationally symmetrical plastic container 2 (top view) with a two-leaf, diametrically opposite arrangement of barrier electrodes 5 or 6, wherein the surface of the container wall 3 is coated in one operation in two places. This makes it possible in principle to realize two different processes in a die insert, z. B. sandwich layers or only to activate and subsequently coat immediately. 4B shows a mehrflügelige (here four-leaf) arrangement of the barrier electrodes 5 or 6 with common Mediazuführhre 13 or with a (not shown here) separate supply of gas / s and precursor / s.

In 5 Two variants of a coating device 1 according to the invention for the outer coating of the container wall 3 and the container bottom 4 of a rotationally symmetrical plastic container 2 are shown. On the right is shown an embodiment with two small-area surface-conforming, independently guided and charged barrier electrodes 5. On the left a bar-shaped barrier electrode 7 is shown, which consists of two surface-conforming individual bars, which can be coupled together as shown and are supplied via two media feeders 13. The plastic container 2 is placed here on a core 9, which is at ground potential 15 and rotates during the coating process about the rotation axis 14.

6 shows an apparatus for internal coating in a design for coating a plastic container 2 with a rectangular (in this case square) cross-section, which is arranged in a rectangular die 8, with a bar-shaped, surface-conforming barrier electrode 6 and an associated plan view. Here, the bar-shaped, surface-conforming barrier electrode 6 is moved exactly parallel along the container wall 3 by means of the guide arm 12, pivoted in the corners and repositioned, so that all four inner surfaces are uniformly coated. In an analogous manner, the container bottom 4 can be coated. The barrier electrode 6 can be designed such that the dielectric barrier discharge can also take place in the corner regions.

7 shows an arrangement analogous to 6 a plastic container 2 between two discharge spaces 10 for a simultaneous plasma treatment or coating of the inner and outer surface of the plastic container.

The 8th shows by way of example schematically a complex formed, structured solid core electrode 17 for simultaneous coating of the entire inner surface of a rotationally symmetrical plastic container 2, wherein the coating can be carried out with and without relative movement of plastic container 2 and solid core electrode 17. In this special embodiment of the barrier electrode, both the surface of the container wall 3 and the container bottom 4 can be coated in a single clamping within a very short time. The solid core electrode 17 contains the media distribution system 16 with channels and outflow openings for the gas-precursor mixture and segmenting gaps for the rinsing or suction of residual gases and possibly reaction products and the reduction of the environmental impact. A possible rotation of the plastic container 2 promotes the layer uniformity.

It should be noted that the segments also different plasma processes can be assigned.

Due to the exact positioning of the plastic container 2 to be coated in the die 8 or on the core 9, a precisely defined distance of the material surface to be coated from the active barrier electrode 5, 6, 7 or 17 exists at all times. Since the composition and supply of the gas Precursor mixture and the removal of reaction products can be controlled precisely, the same process conditions are everywhere achieved and minimized Schichtinhomogenitäten.

list of figures

• 1 : Device for coating the container jacket (schematic)
• 2 : Device for coating the container bottom (schematic)
• 3 : Apparatus for the simultaneous coating of container casing and container bottom (schematic)
• 4 : Device with a two-or multi-leaf arrangement of the barrier electrodes (schematic)
• 5 : Variants of a device for external coating of container casing and container bottom (schematic)
• 6 : Device for internal coating of a rectangular container (schematic)
• 7 : Arrangement for double-sided plasma treatment or coating with a bar-shaped barrier electrode (schematic)
• 8th : Structured solid core electrode (schematic)

LIST OF REFERENCE NUMBERS

1

coater

2

Plastic containers

3

Surface of the container jacket

4

Surface of the container bottom

5

Small-area surface-conforming barrier electrode

6

Bar-shaped surface-conforming barrier electrode

7

combined wall and floor barrier electrode

8th

die

9

core

10

discharge space

11

voltage supply

12

guide

13

Medienzuführeinrichtung

14

axis of rotation

15

ground

16

Media distribution system

17

Full core electrode

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3632748 A1 [0005]
• WO 1999020809 A1 [0011]
• WO 0132949 A1 [0011]
• US 6194036 A1 [0011]
• WO 20080082 A1 [0011]
• DE 60101747 A1 [0011]
• DE 3705428 A1 [0013]

Claims (14)

Coating device for plastic containers of any cross-sectional shape, in particular with a Einfüllöffnungsfläche that is greater than or equal to a bottom surface, and in particular for large-volume plastic containers with an aspect ratio greater than or equal to 1, to reduce gas permeation through a container wall, with • At least one first electrode and at least one second electrode, which are arranged opposite to each other, and a Medienzuführeinrichtung, wherein The first electrode and the second electrode each have an electrode surface and the electrode surfaces each face one of two opposite surfaces of a container wall of a plastic container to be coated and each extend over at least one planar portion of the associated surface, • at least one first electrode is held with its electrode surface at a perpendicular distance to the associated surface and is movable at a constant distance relative to this surface, and A volume located between the electrode surface of the first electrode and the associated surface forms a discharge space in which a planar dielectric barrier discharge is formed during operation of the coating device. Coating device according to Claim 1 in which the electrode surface of a second electrode in the form of a plastic container receiving positive fit die or a plastic container positively filling core is executed and the second electrode and the plastic container on the one hand and the first electrode on the other hand with a constant distance relative to each other. Coating device according to Claim 1 in which also the electrode surface of a second electrode is held at a perpendicular distance to the associated surface and the first electrode and the second electrode on the one hand and a plastic container inserted into the coating device on the other hand are movable relative to each other at a constant distance. Coating device according to one of Claims 1 to 3 in which a media distribution system is integrated into the first and / or second electrode and has an outlet opening or a plurality of outlet openings distributed over the electrode surface in the region of the first and / or second electrode surface. Coating device according to one of Claims 1 to 4 in which a dielectric cover element is interchangeably arranged on at least one electrode surface. Coating device according to one of Claims 1 to 5 in which two or more electrodes are arranged on a common holding device or at least one electrode has two or more electrode surfaces. Coating device according to one of Claims 1 to 6 , which has at least one drive device and / or at least one media mixing device and / or at least one temperature-controlled media supply device and / or at least one suction device and / or at least one housing. Coating device according to one of Claims 1 to 7 , which has at least one control device which is operatively connected to at least one drive device and / or at least one temperature-controlled media supply device and / or at least one media supply device and / or at least one media mixing device and / or with at least one suction device and / or at least one power supply , Coating method for plastic containers of any cross-sectional shape, in particular with a Einfüllöffnungsfläche that is greater than or equal to a bottom surface, and in particular for large-volume plastic containers with an aspect ratio greater than or equal to 1, to reduce gas permeation through a container wall, In that at atmospheric pressure over at least one surface of the container wall a working gas is present or introduced and an electrical discharge is generated, At least one precursor material is introduced into the region of the electrical discharge, In which at least one layer of organic or inorganic precursor material is produced on at least one surface of the container wall, • precursor material is converted into layer material, and Layer material is deposited on the surface of the container wall, A pulsed or sinusoidal low or high frequency high voltage is applied to the two electrodes, The electrical discharge is generated as a dielectric barrier discharge extending uniformly over at least a partial area of the surface, and • the dielectric barrier discharge is led over the surface to be coated. Coating process according to Claim 9 in which the at least one precursor material passes through the first and / or second electrode is introduced into the region of the dielectric barrier discharge. Coating process according to Claim 9 or 10 in which the precursor material is mixed with the working gas before being admitted into the region of the dielectric barrier discharge and / or is tempered to a predeterminable temperature. Coating method according to one of Claims 9 to 11 in which at least one surface of the container wall or a layer already deposited on the surface of the container wall is activated before the inlet of the at least one precursor material by the action of the dielectric barrier discharge. Coating method according to one of Claims 9 to 12 in which a dielectric barrier discharge is simultaneously generated over at least two partial surfaces of the surface and at least one activation process and at least one coating process and / or at least two different coating processes are carried out in the at least two simultaneously generated dielectric barrier discharges. Coating method according to one of Claims 9 to 13 , are sucked at the remains of precursor material, gases and any resulting reaction products in the area around the plastic container.

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