DE102004010177B4 - Electrostatic fluidization apparatus and electrostatic fluidization method for coating substrates with coating powder - Google Patents

Abstract

Electrostatic fluidizing device with
a fluidizing container (1),
an air feed (4) opening into the fluidizing tank (1) for introducing fluidizing air into the fluidising tank (1),
and a fluidizing tray (2) arranged above the mouth of the air feed (4) within the fluidising container (1), through which the fluidising air can be supplied to a volume (5) located above the fluidising tray (2) within the fluidising container (1) for fluidizing coating powder
characterized in that
above the fluidization tray (2) in the volume (5) within the fluidization container (1) as high-voltage electrodes at least two thin electrode wires are arranged as wire electrodes (3) for the ionization of the fluidizing air exposed to each other,
in that in each case a high-voltage resistor (3a) is connected in front of the at least two wire electrodes (3),
and that the at least two wire electrodes (3) have an average distance of more than 2 mm and / or less than 80 mm.

Description

• • Stahl- und Aluminium-Bandmaterial (Coil),
• • Blech-Platinen,
• • Holz- und Holzwerkstoffplatten, z.B. MDF (mitteldichte Faserplatten) oder HDF (hochdichte Faserplatten),
• • Akustik-Dämmplatten,
• • Kunststoffplatten,
• • Metall- und Kunststoff-Folien,
• • Papierbahnen, z.B. Tapeten, Schleifkorn auf Schleifpapier,
• • Strangpressmaterialien (Profile, Rohre), Beispiel: Lötpulverapplikation
• • Kabel (Bepuderung),
• • Drähte, sowie
• • Kleinteile wie Rotor und Statorpakete für Elektromotoren,
• • Bepuderung von Lebensmitteln.

The present invention relates to an electrostatic fluidization device and a corresponding fluidization process for powder coating substrates in particular with uniform surface geometry and in particular in connection with high demands on the constancy of the layer thickness of the applied powder coating. The fluidization device or the fluidization method can be used in particular for powder coating of small parts. The use of the method according to the invention is not limited to special geometries of the parts to be coated. Examples of the use of the fluidization device or the fluidization process are

• Steel and aluminum strip material (coil),
• • sheet metal blanks,
• • wood and wood-based panels, eg MDF (medium-density fiberboard) or HDF (high-density fiberboard),
• • acoustic insulation boards,
• • plastic sheets,
• • metal and plastic films,
• • paper webs, eg wallpapers, abrasive grain on sandpaper,
• • Extruded materials (profiles, tubes), example: soldering powder application
• • cable (powdering),
• • Wires, as well
• • small parts such as rotor and stator packs for electric motors,
• • Powdering of food.

method and electrostatic powder coating apparatus already known from the prior art. Here are essentially Two process groups distinguished: The electrostatic powder spray process as well as the electrostatic vortex bath process. Furthermore You can also use techniques from the field of electrophotography deploy.

• • die mit dem Einsatz von Sprühorganen verbundene Notwendigkeit des Einsatzes lüftungstechnischer Anlagen und Kabinentechnik sowie der damit verbundene hohe Platzbedarf und die hohen Investitionskosten,
• • die hohen Luftvolumenströme bzw. Luftströmungsgeschwindigkeiten beim Aufsprühen des Pulvers auf die Substrate und die dadurch auftretenden Turbulenzen, verbunden mit Schichtdickenschwankungen und Partikelgrößenseparierungen, die zu Verschiebungen des Partikelgrößenspektrums im Pulverkreislauf und damit zu Beschichtungsstörungen führen,
• • die bei hohen Substrat-Fördergeschwindigkeiten erforderlichen hohen Hubgeschwindigkeiten der Sprühaggregate, die zu zusätzlichen Luftströmungsturbulenzen im Sprühstrahlbereich und dadurch zu zusätzlichen Schichtdickenschwankungen führen sowie
• • der hohe anlagen- und verfahrenstechnische Aufwand für die Rückgewinnung und Kreislaufführung des nicht auf den Substraten abgeschiedenen Pulvers, insbesondere beim Einsatz verschieden far biger Pulver.

In the electrostatic powder spray (EPS) process, the powder is fluidized by air and transported via a hose to the sprayer where it is electrostatically charged and sprayed onto the substrate via nozzles. The deposition of the charged powder particles on the grounded substrate is done by electrostatic attraction forces. Since only a part of the sprayed powder reaches the substrate, the non-deposited powder (overspray) is removed from the coating booth by suction and returned to the powder container. In general, the spray units are moved up and down (vertical substrate arrangement) or reciprocated (horizontal substrate arrangement) by means of an automatic lifting device in order to be able to coat all areas of the substrates moved past the spray elements by means of overlapping of the coating strips. The EPS process is suitable for substrate conveying speeds of up to approx. 15 m / min. Disadvantages of the EPS process are,

• • the need for the use of ventilation systems and cabin technology, as well as the associated high space requirements and the high investment costs associated with the use of spray devices,
• The high air volume flows or air flow rates during the spraying of the powder onto the substrates and the resulting turbulences, combined with layer thickness fluctuations and particle size separations, which lead to shifts in the particle size spectrum in the powder circulation and thus to coating defects,
• The high lifting speeds of the spray units required for high substrate conveying speeds, which lead to additional turbulence in the air stream in the spray jet area and thus to additional layer thickness fluctuations, and
• • The high investment and process engineering effort for the recovery and recycling of not deposited on the substrates powder, especially when using different color biger powder.

The Applicable layer thickness is in the EPS process in the range of about 30 to 200 μm. thin film applications with layer thicknesses <30 microns are with This technique is generally not possible because of the usual Layer thickness variations undercoated areas unavoidable are.

At the Electrostatic fluidizing process, the substrates are not directly sprayed, but within a chamber or over a fluidizing tank coated in a cloud of charged powder. The deposition The powder particles on the substrates do not take place here as in the case of EPS process through the combination of spraying with air and electrostatic Attraction, but mostly by electrostatic forces. The principal advantages of this method are in particular the compactness of the system engineering (small space requirement) as well as in relation to EPS technology low required air volume flows per transferred Amount of powder. For uniform layer thicknesses achieve, are not complex Lifting movements for spray jet overlap as in the EPS process (e.g., by hoisting machines, 6-axis robots) required.

• • der Fluidisierbehälter sowie der Fluidisierboden ist aus (elektrisch isolierendem) Kunststoff gefertigt, um dort keine elektrischen Entladungen zu erhalten, der Fluidisierboden besteht in der Regel aus Polyethylen-Sintermaterial,
• • die Elektrode befindet sich im Bereich der Luftzuführung unterhalb des Fluidisierbodens, der abstand zwischen Elektrode und Fluidisierboden beträgt mindestens 200 mm, so dass der Abstand Elektrode/Werkstück in der Regel mindestens ca. 300 mm beträgt,
• • die an der Elektrode erzeugten Luftionen bewegen sich durch den Fluidisierboden, der sich z.T. elektrisch auflädt, und weiter zu den Pulverpartikeln, die durch die Luftionen aufgeladen und durch das elektrische Feld zum Werkstück transportiert werden.

By far the most common technique of the electrostatic fluidized bath is constructed as follows (Patent US 6,558,752 B2 ):

• The fluidising tank and the fluidising floor are made of (electrically insulating) plastic in order to prevent electrical discharges there, the fluidising floor generally being made of polyethylene sintered material,
• • the electrode is located in the area of the air supply below the fluidising floor, the distance between the electrode and the fluidising floor is at least 200 mm, so that the electrode / workpiece distance is generally at least approx. 300 mm,
• • The air ions generated at the electrode move through the fluidising floor, which in part becomes electrically charged, and on to the powder particles, which are charged by the air ions and transported by the electric field to the workpiece.

• • die große Bauhöhe der Fluidisierbehälter, hervorgerufen durch den erforderlichen großen Abstand Elektrode/Werkstück, da bei geringeren Abständen durch die hohe Kapazität der Elektroden Zündgefahren durch hohe Zündenergie entstehen: W = 0,5·C·U2 [J] W ist die in der Kapazität C gespeicherte Energie C = Kapazität [F] U = Spannung [V] C = ε0·l·2π/lπ (S/r) [F]ε₀ = Influenzkonstante [As/Vm] l = Länge S = Sprühabstand (Abstand Drahtmitte zu Substratoberfläche) [m] r = Radius Drahtelektrode [m]
• • die damit verbundenen geringen Feldstärken und geringen Transportkräfte der Partikel, wenn nicht sehr hohe Hochspannungswerte angelegt werden,
• • an der einfach aufgebauten Elektrode (z.B. Schleifaufsatz für Bohrmaschinen mit vielen Korona-Spitzen) örtlich erhebliche Schwankungen des Korona-Stromes und damit verbunden Inhomoge nitäten der Aufladung der Partikel und des elektrischen Feldes,
• • die hohen Raumladungsdichten die durch die Aufladung des Fluidisierbodens eine Erhöhung der Korona-Einsatzspannung und damit eine Erhöhung der erforderlichen angelegten Hochspannung bewirken (Erhöhung der Zündenergie siehe Gleichung oben), in der Regel müssen Hochspannungswerte > 60 KV eingesetzt werden,
• • die chemische Veränderung des Kunststoff-Fluidisierbodens beim Betrieb durch die Einwirkung der Koronaentladung, die zu undefinierten Raumladungsdichten und damit zu Prozessunsicherheiten durch unkontrollierbare Änderungen der örtlichen Feldstärken führt.

Disadvantages of this technique are

• • The large height of the fluidizing, caused by the required large distance electrode / workpiece, since at shorter distances due to the high capacity of the electrodes ignition hazards caused by high ignition energy: W = 0.5 × C × U 2 [J] W is the energy stored in the capacitance C = capacitance [F] U = voltage [V] C = ε 0 · L · 2π / lπ (S / r) [F] ε ₀ = Influence constant [As / Vm] l = length S = spray distance (distance between wire center and substrate surface) [m] r = radius of wire electrode [m]
• The associated low field strengths and low transport forces of the particles, if not very high high voltage values are applied,
• • On the simply constructed electrode (eg grinding attachment for drilling machines with many corona tips) locally significant fluctuations of the corona current and associated inhomogenities of the charging of the particles and the electric field,
• • the high space charge densities which cause an increase in the corona threshold voltage due to the charging of the fluidising floor and thus an increase in the required high voltage (increase of the ignition energy see equation above), as a rule high voltage values> 60 kV must be used,
• • The chemical change of the plastic fluidising floor during operation due to corona discharge, which leads to undefined space charge densities and thus to process uncertainties due to uncontrollable changes in the local field strengths.

The achievable layer thicknesses are the electrostatic Wirbelbadverfahren in the same range as the EPS method, i. at about 30 to 200 microns. by virtue of has the known disturbances it only for few areas, e.g. when coating tapes and wires as well in particular for coating rotors and stators from the electric motor sector enforced.

• • werden bewegliche Elektroden eingesetzt, so neigen diese beim Eintauchen in das Fluid zu Verschmutzungen und sind sicherheitstechnisch für die Übertragung größerer Pulvermengen pro Zeiteinheit kritisch; das elektrische Feld ist zu inhomogen für einen einheitlichen, großflächigen Pulverauftrag,
• • ebenfalls zu inhomogen ist die Feldstärke beim Einsatz von einzelnen Korona-Spitzen innerhalb des Fluidisierbetts (ein solcher Einsatz führt zudem zu erheblichen Zündgefahren im Fluid),
• • wird eine einzelne Korona-Spitze zur Pulveraufladung eingesetzt, so ist die Pulverübertragungsrate pro Zeiteinheit gering,
• • im elektrofotografischen Bereich ist der Abstand Elektrode/"Werkstück" (letzteres ist in der Regel eine Walze) definiert gering, da die Walze in das Fluid eintaucht; hohe Feldstärken sind bei geringen Abständen von Walze und Elektrode mit sehr niedrigen eingesetzten Hochspannungswerten, z. T. < 10 KV erreichbar; bei der elektrostatischen Pulverbeschichtung im Wirbelbad lassen sich solch geringe Abstände jedoch nicht erzielen aufgrund: – der Dreidimensionalität der Substrate, – der Tatsache, dass Werkstücke nur für wenige Anwendungen in das Fluidisierbett eingetaucht werden, da die erzielbare visuelle Verlaufsqualität der applizierten Pulverschicht dabei in der Regel gering ist (häufiger wird das Substrat über die Fluidisierwolke gefahren).

Other techniques ( EP 0 494 454 B1 ) from the field of electrophotography are due to the low transfer rate per unit time usually unsuitable for electrostatic powder coatings. They also have the following disadvantages:

• • If movable electrodes are used, they tend to become soiled when immersed in the fluid and are critical in terms of safety for the transmission of larger amounts of powder per unit time; the electric field is too inhomogeneous for a uniform, large-area powder application,
• • too inhomogeneous is the field strength when using individual corona tips within the fluidization bed (such use also leads to significant ignition hazards in the fluid),
• If a single corona tip is used for powder charging, the powder transfer rate per unit time is low,
• In the electrophotographic field, the electrode / "workpiece" distance (the latter is usually a roller) is defined as low as the roller is immersed in the fluid; high field strengths are at low distances from the roller and electrode with very low high voltage values used, eg. T. <10 KV reachable; in the electrostatic powder coating in a fluidized bath, such small distances can not be achieved due to: - the three-dimensionality of the substrates, - the fact that workpieces are immersed in the fluidization bed only for a few applications, since the achievable visual grading quality of the applied powder layer usually is low (more often, the substrate is driven over the fluidizing cloud).

The DE 27 04 714 A1 discloses an electrostatic fluidizing apparatus in which a wire grid is disposed above the fluidizing tray to which a high voltage is applied to produce a corona discharge at its wire tips. Also the US 3,336,903 discloses a fluidizing bed which generates a corona discharge via a grid having wire tips above the fluidizing floor. This is also from the US 3,985,297 known.

The US 4,332,835 discloses fluidization tion device, wherein the charging of the powder to be fluidized takes place in a conventional manner below the Fluidisierbodens. The fluidising floor is grounded to prevent electrostatic charging of the fluidising floor. Between the fluidizing floor and ground a series resistor is interposed.

Also the DE 24 44 645 B2 discloses an arrangement in which the powder is charged below the fluidizing tray. Here the electrode is located in the air supply area. The US 3,402,814 as well as the US 3,828,729 disclose coating devices in which the electrode for charging the coating powder above the fluidization be found.

Another possibility of coating objects is the use of spray guns in which the paint powder is accelerated to the object to be coated. Such spray guns are eg in the US 3,985,297 , of the DE 197 01 995 A1 as well as the DE 34 29 075 A1 and the US 5,044,564 described.

A measuring device with which the powder level in a powder reservoir can be measured with the aid of an ultrasonic sensor is shown in US Pat DE 197 36 331 A1 described.

outgoing It is the object of the present invention to an electrostatic fluidizing device and a corresponding Fluidization process available with which substrates with low and high throughput speeds, with high process reliability and with thin layers, in particular also with thicknesses of less than 30 μm, reliable and can be reproducibly coated.

These Task is by an electrostatic fluidization device according to claim 1 and an electrostatic fluidization method according to claim 49 solved. Advantageous developments of the electrostatic fluidizing device according to the invention and the corresponding fluidization method are described in the dependent claims.

A electrostatic according to the invention Fluidizing device comprises a fluidizing container, a in the fluidizing tank opens air supply (For introducing fluidizing air into the fluidizing tank), a above the confluence the air supply within the fluidizing tank arranged fluidizing, through which the fluidizing air a volume above the fluidising floor (internal volume) within the fluidizing tank supplied is (in the volume or inner volume of coating powder too fluidize) and at least two above the fluidization tray arranged in the volume within the fluidizing high voltage electrodes for ionizing the fluidizing air. The above the fluidizing floor in volume arranged high-voltage electrodes are thin wire electrodes. In the fluidization device according to the invention each of the wire electrodes is a high voltage resistor (preferred in the range of 1 MΩ to 1000 TΩ) upstream of each of the wire electrodes individually in their performance to limit.

The at least two wire electrodes have a middle distance from each other from above 2 mm and / or less than 80 mm.

Of the Diameter of the thin Wire electrodes amounts this advantageously over 20 microns and / or below 1000 μm, in particular between 60 microns and 100 μm.

In In a first advantageous embodiment, the wire electrodes in the immediate vicinity of Fluidizing arranged or have a mean distance from the fluidizing bottom of up to 50 mm, advantageously from to up to 20 mm.

In In another advantageous embodiment, the wire electrodes their longitudinal direction arranged substantially parallel to the surface of the Fluidisierbodens or positively arranged the fluidization bottom. The wire electrodes run in this case in terms of their longitudinal direction advantageously parallel to each other and preferably have a mean distance from each other over 10 mm and / or less than 30 mm.

In a further advantageous embodiment can for Power limitation the individual wire electrodes also from one semiconducting material, such as semiconducting material ceramic fibers or glass fibers (these then also have prefers a resistance in the range of 1 MΩ to 1000 TΩ).

In further advantageous embodiments, not only the fluidization bottom can be covered with wire electrodes, but these can also be arranged on the side walls of the fluidization: For a possible advantageous embodiment, the wire electrodes are each arranged longitudinally partially parallel to the surface of the Fluidisierbodens or positively on the Fluidizing arranged and arranged partially parallel to at least one side wall of the fluidizing or arranged form-fitting manner on at least one side wall of the fluidizing. The wire electrodes can in a further advantageous embodiment along its longitudinal axis partially in the immediate vicinity of the fluidization or at a mean distance of up to 50 mm, advantageously up to 20 mm, from the fluidising floor and partly in the immediate vicinity of the at least one side wall or at an average distance of up to 50 mm, advantageously up to 20 mm, of be arranged at least one side wall of this. Alternatively, in a first subset of wire electrodes each wire electrode in the immediate vicinity of the fluidization or in an average distance of up to 50 mm, advantageously up to 20 mm, be arranged by the fluidization and in a second subset of wire electrodes each wire electrode in the immediate Be arranged near a side wall of the fluidizing or in an average distance of up to 50 mm, advantageously up to 20 mm, from a side wall of the fluidizing. The first subset of the wire electrodes may in this case be arranged parallel to the surface of the fluidization base or be arranged in a form-fitting manner on the fluidization base and the second subset of the wire electrodes may be arranged parallel to the surface of the side wall or in a form-fitting manner on this side wall.

Around even with complicated workpiece geometries to achieve a homogeneous distribution of field forces are in one further advantageous embodiment of the fluidization device according to the invention the wire electrodes are not over her entire length on the fluidizing floor or on a side wall of the fluidising floor attached or the wire electrodes are only at one of their ends attached and otherwise freely movable in the fluid. advantageously, In this case, the wire electrodes are at least in the unattached area partially provided with an insulating coating or wise in this area an electrically insulating plastic cap. Alternatively, you can the wire electrodes also consist of semiconducting material or ceramic Be fibers or glass fibers.

To the Protection of the wire electrodes is in a further advantageous embodiment another fluidizing bottom within the fluidizing tank above the wire electrodes arranged. This is preferably thinner than the first fluidization tray (below the wire electrodes). The second Fluidizing bottom preferably has a thickness of more than 1 mm and / or less than 10 mm, in particular of over 2 mm and / or less than 5 mm. In another variant, the Wire electrodes also above a portion of the first Fluidisierbodens arranged in the first fluidization or incorporated into the first fluidization or integrated (arranging, introducing or integrating happens preferably during of the sintering process, the electrodes can then meander in the ground or wavy be arranged).

In Another variant is the applied high voltage (DC voltage) an alternating voltage or a pulsating direct voltage superimposed: For this purpose, AC electrodes are above the wire electrodes in the volume of Fluidisierbehälters or arranged above the volume or the fluidization tank. Preferably, the AC voltage electrodes are coil springs, you can but also be constructed like the DC wire electrodes, as previously described. The AC voltage electrodes are preferably at a distance of more than 5 mm and / or less than 100 mm, in particular of over 30 mm and / or less than 70 mm above the fluidization tray or above the wire electrodes with respect to their longitudinal direction substantially parallel to the surface the Fluidiesierbodens arranged. The AC voltage electrodes can then with a 50 Hz AC generator or with a kHz AC generator be connected.

In a further advantageous embodiment, the side walls of the Fluidisierbehälters or the bottom of the fluidizing tank of electrically insulating Materials, especially plastic POM, polyimide-based Materials, glass or ceramic materials. The fluidising floor is preferably a polyethylene sintered bottom with pore widths of about 2 microns and / or below 100 microns, in particular from above 10 μm and / or below 50 μm or Alternatively, an inorganic sintered soil or a ceramic Sintered bottom or a glass sintered bottom.

In a further advantageous embodiment variant, the fluidization device above of the fluidizing tank an electrically conductive Deposit on, for example, a metal plate or a Electrode. For coating a substrate with a pattern can this conductive Deposit a structure or a pattern or in shape be designed a template.

In a further advantageous embodiment, the fluidizing device according to the invention has a metering device opening into the fluidizing container (this may, for example, include a further fluidizing container). This is an automatic or continuous metering of Be coating material in the fluidizing tank possible. Advantageously, the metering device has a storage container for storing coating material or powder and at least one of the storage container in the fluidizing leading feeder unit or a dense phase conveying device for the promotion of coating powder high density, low mobility or high viscosity, for example in the form of a Dichtestrompulverpumpe on. Such a dense phase powder pump can in this case have two operating in alternating cycle piston pumps; the preferably three to five plugs of coating powder material conveyed per second per piston pump then lead to a quasi-continuous promotion of coating powder. The storage container is preferably a further fluidizing container, wherein it may in particular have larger dimensions or a larger filling volume than the fluidizing container equipped with the wire electrodes. The supply unit preferably has a peristaltic pump, peristaltic pinch valves and, in the region of the junction with the storage container, a discharge opening or a pipeline. To prevent excessive coating powder or fluid movements in the region of the mouth of the metering device, the fluidizing container preferably has flow breaking devices or baffles, in particular walls, in this region. Advantageously, in this case no wire electrodes are arranged in the region of the junction of the metering device.

In a further advantageous embodiment variant, the fluidizing device one into the fluidizing tank integrated or arranged on it level measuring device, with the the coating powder height in the fluidizing tank can be determined. The level measuring device is in this case, an ultrasonic measuring probe preferably. In a preferred Variant are the level measuring device and the flow breaking devices or Baffling arranged so that a detection of the filling level in the by the flow breaking devices motion-calmed fluid region is feasible.

In a further advantageous variant, the fluidizing device one inside the fluidizing tank arranged or integrated in this separation device (for example a partition wall), which divides the fluidizing tank into at least two segments divided so that both segments are independent and unaffected separately be supplied with fluidizing air. In this case, preferably, each the segments have their own air supply. Advantageously the separation device openings for level compensation of the coating powder between the individual segments. In an advantageous variant is the level measuring device (for example the ultrasound probe) in the region of a first through the separation device generated segment on the fluidizing arranged or in this integrated, the wire electrodes are within the second segment arranged and the metering device opens in the region of the second Segments. Advantageously, the fluidization floor or its Part within the first segment on a smaller pore size as within the second segment. The pore size within the first segment amounts in this case, preferably between 2 and 20 μm, in particular between 5 and 15 μm, the pore size in the region of the second segment preferably between 20 and 70 μm, in particular between 25 and 50 μm.

In a further advantageous embodiment of the device according to the invention is the fluidizing tank divided into at least two segments, wherein the at least two Segments or their volumes so separated or against each other are completed, that in the volume of the one segment coating powder unaffected by the other segment, its volume or in its Volume introduced coating powder is fluidizable. Of the Completion or separation of the at least two segments takes place here advantageously arranged with the aid of in the fluidizing tank Between walls. In an advantageous embodiment, these intermediate walls are arranged or formed by an imaginary, to the fluidizing in the Essentially vertical plane of at least one of the segments in at least three separate subvolumes can be divided. Especially preferred have the partitions in a lying substantially parallel to the fluidization bottom Sectional plane a substantially M-shaped, wavy, sawtooth or meandering shape on. In a further advantageous embodiment variant are here two partitions arranged at a constant distance from each other. In a further advantageous embodiment variant are at least two partitions arranged substantially parallel to each other so that through this partitions the fluidizing tank in a direction substantially parallel to the Fluidisierboden in at least three consecutive, with respect to the coating material divided segments separated. Preferred are the wire electrodes of the individual segments can be controlled independently of each other or assignable with high voltage. The individual segments can also separate metering devices, as already described, have.

• • Mit der Erfindung können Pulverschichten definierter Dicke mit einer bisher nichtmöglichen Konstanz auch bei hohen Prozessgeschwindigkeiten vorzugsweise auf Substrate mit gleichmäßiger Oberflächengeometrie und Kleinteile aufgebracht werden. Durch die erhebliche Verbesserung der bisher marktüblichen elektrostatischen Fluidisierbehälter hinsichtlich der Prozesssicherheit kann die Anwendung dieser Technik zukünftig erheblich erweitert werden.
• • Durch die dünnen Drahtelektroden verringert sich deren Kapazität, wodurch eine deutlich reduzierte Bauhöhe (beispielsweise etwa 100 mm) des Fluidisierbehälters möglich wird. Durch diese verringerte Bauhöhe kann der Abstand Elektrode-Transferband einer Beschichtungsvorrichtung soweit reduziert werden (beispielsweise auf etwa 100 mm), dass ein direkter Übertrag des elektrostatisch aufgeladenen Pulvers vom Transferband zum Substrat möglich ist, ohne dass hierzu weitere Übertragungselemente (Walzen oder ähnliches) verwendet werden müssen.
• • Bei der erfindungsgemäßen Übertragung des Pulvers auf das Substrat treten die bei den elektrostatischen Pulverbeschichtungsverfahren nach dem Stand der Technik üblichen Schichtdickenschwankungen und Partikelgrößenseparierungen nicht auf. Die zu übertragende Pulvermenge kann in einem weiten Bereich reproduzierbar gesteuert werden, so dass konstante Schichtdicken sowohl bei geringen als auch bei hohen Fördergeschwindigkeiten des Substrats bis zu ca. 3 m/s erzeugt werden können. Insbesondere können auch sehr dünne Schichten bis herab zu wenigen μm Dicke reproduzierbar erzeugt werden.
• • Der Fluidisierbehälter kann einerseits zur herkömmlichen Stückgutbeschichtung insbesondere von Kleinteilen verwendet werden. Die Werkstücke können dabei in das Fluid eingetaucht werden, bevorzugt werden sie über die Fluidisierwolke gefahren, da sich dabei die visuelle Beschichtungsqualität verbessert, die applizierte Pulvermenge pro Zeiteinheit ist aber geringfügig reduziert. Andererseits kann der Fluidisierbehälter als Beladestation für ein aus DE 101 630 25 A1 bekanntes Transfer-Applikationsverfahren verwendet werden.
• • Das Verfahren eignet sich für niedrige und hohe Durchlaufgeschwindigkeiten des zu beschichtenden Substrates im Bereich bis zu ca. 3 m/s. Darüberhinaus ist das Verfahren aufgrund der Dosiergenauigkeit durch überwiegend elektrostatische Kräfte bei der Applikation des Pulvers auf dem Substrat auch für Anwendungen geeignet, bei denen nur eine geringe Pulvermenge bzw. eine dünne Pulverschicht appliziert wird:
• • die Pulverbeschichtung von Dämmplatten,
• • das elektrostatisch unterstützte Applizieren von Schleifkorn auf Papier und Kunststofffolie,
• • die Lötpulverapplikation auf Strangpressmaterialien,
• • die Klarpulverbeschichtung von Tapeten sowie
• • Bepuderungseinrichtungen z.B. für elektrische Kabel oder im Lebensmittelbereich.

The above-described electrostatic fluidizing device according to the invention has a number of significant advantages:

• With the invention, powder layers of defined thickness with a hitherto impossible constancy, even at high process speeds, can preferably be applied to substrates having a uniform surface geometry and small parts. Due to the considerable improvement of the previously customary electrostatic fluidizing container in terms of process reliability, the application of this technique in the future he considerably be extended.
• • The thin wire electrodes reduce their capacity, allowing a significantly reduced overall height (for example, about 100 mm) of the fluidizing tank. Due to this reduced overall height, the distance between the electrode transfer belt of a coating device can be reduced (for example to about 100 mm) so that a direct transfer of the electrostatically charged powder from the transfer belt to the substrate is possible without the need for further transfer elements (rollers or the like) have to.
• In the case of the inventive transfer of the powder to the substrate, the layer thickness fluctuations and particle size separations customary in the electrostatic powder coating methods according to the prior art do not occur. The amount of powder to be transferred can be reproducibly controlled in a wide range, so that constant layer thicknesses can be produced up to about 3 m / s both at low and at high conveying speeds of the substrate. In particular, very thin layers down to a few microns thickness can be generated reproducible.
• On the one hand, the fluidizing container can be used for conventional general cargo coating, in particular of small parts. The workpieces can be immersed in the fluid, they are preferably driven over the fluidizing cloud, as this improves the visual coating quality, but the applied powder amount per unit time is slightly reduced. On the other hand, the fluidizing can be used as a loading station for a DE 101 630 25 A1 known transfer application method can be used.
• • The process is suitable for low and high throughput speeds of the substrate to be coated in the range up to approx. 3 m / s. Moreover, the method is suitable due to the dosing accuracy by predominantly electrostatic forces in the application of the powder on the substrate for applications in which only a small amount of powder or a thin powder layer is applied:
• The powder coating of insulation boards,
• The electrostatically assisted application of abrasive grain to paper and plastic film,
• The solder powder application on extruded materials,
• • the clear powder coating of wallpaper as well
• • Powdering devices eg for electrical cables or in the food industry.

Inventive electrostatic Fluidizing devices can as described in one of the following examples or used. In the figures associated with the various examples be for the same or for corresponding components or components of the fluidization devices identical reference numerals used.

It shows 1 an electrostatic Wirbelbadverfahren according to the prior art.

It shows 2 the basic configuration of an electrostatic fluidizing device according to the invention.

It shows 3 an electrostatic fluidizing device with wire electrodes between two sintered floors and with a stencil as an electrostatic deposit.

It shows 4 an electrostatic fluidizing device including a conveyor for dipping a workpiece.

It shows 5 the power limitation in an electrostatic fluidizing device by means of ballast resistors.

It shows 6 Wire electrodes in an electrostatic fluidizing device, which are partially free to move in the fluid.

It shows 7 an electrostatic fluidizing device having an AC voltage electrode.

It shows 8th the subdivision of a Fluidisierbehälters into several segments to achieve multi-colored designs in the coating.

It shows 9 a first dosing system.

It shows 10 a second dosing system.

It shows 11 the use of an electrostatic fluidizing device according to the invention in the context of a transfer application method.

It shows 12 a further possible use of a fluidization device according to the invention.

1 shows a fluidizing device according to the prior art. This has a fluidizing tank 1 (with b ₁ = 250 mm) with side walls 1a and soil 1b on. Above the bottom opens a Fluidisierluftzuführung 4 in the container 1 , Above the air supply 4 is in the container 1 an electrode A (a wire mesh) is arranged. At the upper end of the fluidizing tank is in the fluidizing tank 1 a fluidising floor 2 arranged. Above that is located in the fluidizing tank 1 a volume 5 to Absorption of fluidized or fluidized powder 5a , Above the electrode A of the fluidizing floor 2 and the fluidizing tank 1 there are air ions (-). In the area 6 (above the volume 5 ) is coated with coating particles by the air ions 7 a workpiece 8th , which via the fluidizing device 1 can be driven (horizontal arrow) coatable. Through the air supply 4 is the fluidizing tank 1 Fluidizing supplied. This is at least partially ionized by means of the electrode A. The electrode A or the wire mesh thus generates air ions for charging the powder particles. The air or the corresponding ions pass through the pores of the fluidising floor at an air speed of about 0.01 m / s and under an air pressure of several bar 2 in the volume 5 above the fluidising floor 2 therethrough. In this volume 5 There is a coating powder (fluidized by the air supply) 5a , which is at least partially charged by the air ions. The fluidising floor 2 consists of polyethylene sintered material. By the influx of air ions into the fluidized powder 5a forms above the volume 5 or above the fluidizing tank 1 in the coating area 6 a fluidizing cloud, ie a cloud of charged particles 7 and air ions 7 , By this fluidizing cloud, the substrate or the workpiece 8th coated. For coating or during the coating, the workpiece 8th via the fluidizing cloud or via the fluidizing tank 1 hazards.

2 shows the basic configuration of a fluidization device according to the invention in side view (ie in a viewing direction in the plane of the fluidization 2 ). The 1 corresponding components bear the same reference numerals. The fluidizing tank 1 (Side walls 1a , Ground 1b ) has in its interior a glass sintered bottom 2 as fluidizing soil. Below the Fluidisierbodens is fluidizing air through the air supply 4 fed. The height of the fluidizing tank 1 is contrary to the in 1 shown container only b ₂ = 100 mm. Essential feature of Fluidisierbehälters invention 1 is that just above the Fluidisierbodens 2 thin wire electrodes 3 with a diameter <0.1 mm (here: 60 microns) are arranged.

These run parallel to the ground in the longitudinal direction 2 and into the drawing plane so that they are represented as dots. The wire electrodes 3 have a current limited high voltage supply (see 5 ) and are supplied with high voltages> about 6 kV, preferably between 10 and 30 kV. In volume 5 of the fluidizing tank 1 above the fluidising floor 2 is to be fluidized coating powder 5a , The filling quantity of the coating powder 5a in the fluidizing this is as low as possible. The through the air supply 4 supplied air passes through the pores of the glass sinter 2 and is caused by the high field strengths at the wire electrodes 3 at least partially ionized. The air supply turns the coating powder 5a fluidized, by the ionized air fractions is the coating powder 5a at least partially electrostatically charged. This creates a fluidizing cloud within the range 6 above the volume 5 in which charged coating material particles 7 and air ions 7 are located. The workpiece 8th (grounded) is above the fluidizing cloud in the area 6 driven and thereby coated.

The electrostatic fluidizing tank 1 is made of electrically insulating material (plastic, preferably POM or polyimide-based materials, glass, ceramic materials). In particular, polyimide-based materials, glass and ceramics do not change in terms of their electrical properties in corona discharges of the wire electrodes 3 ,

f

= Rauheitsfaktor der Elektrode (0,5 < f < 1)

s

= relative Dichte der Luft, s ≅ 1

r

= Elektrodenradius [m]

S

= Abstand Koronaelektrods – geerdete Gegenelektrode [m]

The minimization of the stored electrical energy in the electrostatic fluidizing tank 1 can on the one hand by the reduction of the corona threshold voltage, so the voltage from the electrodes with the wire 3 a corona discharge and thus an air ionization is possible (previously about 70 kV), on the other hand by reducing the capacity of the electrodes 3 respectively. Peek describes the correlations at the corona threshold voltage (U _C0 ) with the equation: U C0 = 3 · 10 6 · R · f · s · (1 + 0.3 · (s · 10 -2 / R) 0.5 ) Ln (S / r) [V]

f

= Roughness factor of the electrode (0.5 <f <1)

s

= relative density of air, s ≅ 1

r

= Electrode radius [m]

S

= Distance corona electrode - grounded counter electrode [m]

U_C0

= Korona-Einsatzspannung ohne Raumladung (nach Peek) [V]

U_ρP

= Spannung durch Raumladungseinfluss aufgeladener Pulverpartikel [V]

L

= Länge des Bereiches, indem sich die Raumladung befindet [m]

ρ

= Raumladungsdichte [C/m³]

ε₀

= elektrische Feldkonstante/Permittivität des Vakuums (8,86·10^–12) [As/Vm]

In the illustrated Fluidisierbehälterkonzept the corona threshold voltage is considerably reduced by the choice of very small wire electrode diameter r (60-100 microns). While in the prior art about 70 kV high voltage are common, the corona threshold voltage of these electrodes 3 is about 6 kV, typical work areas are about 15-30 kV. The thinner electrode 3 in comparison with the prior art also reduces the capacitance of the electrodes 3 or of the arrangement, as a result of which the distance from electrode to transfer belt (not shown) and thus the overall height can be reduced to approximately 100 mm (ignition energy <100) mJ, in previous concepts about 300 mJ). Since the space charge created by charged particles increases the corona threshold voltage, the minimization of the gap may result in electrode 3 to workpiece 8th and the filling level of the powder 5a in the fluidizing tank 1 the Koro na-use voltage can be reduced. The function used by Wu for spray guns can also be used in a first approximation to estimate the influence of the space charge effects on the fluidization tank: U C = U C0 + U ρP [V] U ρP = φL 2 / 4 ε0 [V]

U _C0

= Corona threshold voltage without space charge (according to Peek) [V]

U _ρP

= Voltage due to space charge influence of charged powder particles [V]

L

= Length of the area where the space charge is located [m]

ρ

= Space charge density [C / m ³ ]

ε ₀

= electric field constant / permittivity of the vacuum (8.86 × 10 ^-12 ) [As / Vm]

With a fluidization bottom area of 1 m ² and a typical transfer rate of about 100 g of powder / s and a particle velocity of about 1 m / s and with a powder coating typical charge of 1 uC / g, this leads to a space charge density of 10 ^-4 C / m ³ .

U_C0

= Korona-Einsatzspannung ohne Raumladung (nach Peek) [V]

U_ρP

= Spannung durch den Raumladungseinfluss aufgeladener Pulverpartikel [V]

U_P

= Spannung durch die applizierte Lackschicht (vernachlässigbar gering) [V]

U_B

= Spannung durch den aufgeladenen Sinterboden [V]

In the case of an electrostatic fluidizing container, in addition to the space charges by particles, space charges are also added due to the charging of the fluidising floor, which must be taken into account. Depending on the pore size of the sintered floors, these have a surface area of up to approx. 50,000 m ² / m ³ . By measuring surface charge densities of polyethylene film by means of a field mill (about 0.4 .mu.C / m ^2), the space charge density be estimated when polyethylene Interboden in electrostatic Whirlpool according to the prior art to approximately 0.02 C / m ^3. The corona threshold voltage for electrostatic fluidizing vessels is therefore composed as follows: U C = U C0 + U ρP + (U P ) + U B

U _C0

= Corona threshold voltage without space charge (according to Peek) [V]

U _ρP

= Voltage due to the space charge influence of charged powder particles [V]

U _P

= Stress due to the applied lacquer layer (negligible) [V]

U _B

= Voltage through the charged sinter bottom [V]

With U _C0 = 6 kV and a fluidizing floor thickness of 10 mm, this means in the current state of the art: U C = 6000 + (10 -4 · 0.05 2 ) / (8.86 x 10 -12 ) + (0.02 · 0.01 2 ) / (8.86 x 10 -12 ) = 6000 + 7000 + 56000 = 69 kV

Despite high transmission rates / time unit, the influence of the space charge density on the corona threshold voltage is relatively low, as is usually carried out with low spray distances (L) (about 7 kV, see above). However, in the prior art, it is additionally increased by more than 50 kV by the fluidising floor (see above). Due to chemical changes in the plastic of the soil as well as the effect of the corona discharge, this space charge effect can fluctuate considerably (estimated approx. +/- 20%). This leads to considerable process uncertainties due to uncontrollable changes in the local field strengths. Such disturbing effects are achieved with the electrostatic fluidizing container according to the invention 1 thereby minimizing the electrodes 3 above the sinter bottom 2 are located and the sinter bottom 2 barely electrostatically charged. Favor is at the wire electrodes 3 worked with unipolar negative charge, it can be used in principle also positive high voltage.

As fluidising floors 2 come in addition to the typical standard polyethylene sintered bottom with a pore size of 10 microns to a pore size of about 50 microns inorganic or ceramic sintered floors or glass sintered floors used. Glass sinter bottoms no longer change due to corona discharges, space charge densities settle after a short switch-on time to defined values and lead to a defined electric field. This considerably increases the process reliability of the electrostatic application.

In the fluidizing container according to the invention 1 is due to a dense arrangement of the individual wire electrodes (these are just above the Fluidisierbodens 2 and arranged with respect to their longitudinal axis parallel to the fluidizing floor plane and parallel to each other at a distance of about 10 to 30 mm) in the area of the powder transfer a nearly homogeneous electric field similar to the plate capacitor (E = U / S) produced. At an applied high voltage of 25 kV at 50 mm distance (S) a homogeneous field strength of about 0.45 kV per mm is measured by means of a field mill. This corresponds to about 90% of the value achieved with the plate / plate model. The individual electrodes 3 However, they must not be too close to each other, because then there is no longer a corona discharge (missing field peaks).

3A shows a fluidizing device according to the invention, which is constructed as in 2 shown. Unlike the in 2 However, the arrangement shown is located above the fluidizing floor (here 2 B ) and the wire electrodes 3 a second thin fluidising floor 2a , The wire electrodes 3 are between the two fluidising floors 2a and 2 B laid. The upper fluidising floor 2a is only about 2 to 5 mm thick (a Fluidisierboden after the state The technique is usually about 1 cm thick, this thickness also indicates the ground 2 B on). By this arrangement, only a small charge of the upper sinter bottom occurs 2a or through the upper sintered bottom 2a there are only minimal space charge effects above the electrodes 3 , so that the electric field and the threshold voltage (corona threshold voltage) are only slightly affected. The advantage of this embodiment lies in the lower sensitivity of the fluidizing tank 1 during cleaning and color change, as exposed thin electrode wires 3 of how here 80 microns diameter are very sensitive to mechanical damage. Preference is also here with unipolar negative charging of the electrodes 3 worked, it can be used in principle also positive high voltage. Above the grounded workpiece 8th is a grounded deposit in the present embodiment 10 arranged in the form of a metal plate. The grounded deposit 10 is especially at electrically low conductive, flat workpiece 8th or substrate necessary. Such a grounded deposit 10 If necessary, the electrostatic application can be improved or made possible first. In the present case, the deposit indicates 10 a pattern on or is designed as a template (see 3B ie with the deposit can special designs 10a respectively. 10b be realized. When applying such simple images, for example on glass or plastic plates, the process is usually run clocked: In this case, the conveyor (not shown) stops when the workpiece 8th (or the area to be coated 8th in continuous materials) above the fluidizing tank ( 1 ) and only then is the high voltage switched on. The high voltage is then switched off before driving on again.

4 shows a side view of a further embodiment of the fluidizing device according to the invention. The viewing direction (still in one direction in the Fluidisierbodenebene) is here by 90 ° to that in the 2 and 3 rotated viewing direction. The thin wire electrodes 3 or in 4 the part of which, immediately above the Fluidisierbodens 2 is arranged, so do not appear here as a point, but as a thin line, as is perpendicular to the wire electrode longitudinal axis. In the present example, the wire electrodes 3 so on both sides have been extended that part 3d the wire electrodes 3 along the left and right sidewall 1a of the fluidizing tank 1 to be led. Thus, in the present case, the side walls 1a above the fluidising floor 2 with electrode parts 3d busy. Also shown is a conveyor system or a conveyor 16 with which the substrate or workpiece (grounded) 8 in the fluidization 1 or the volume 5 of the fluidizing tank 1 above the fluidising floor 2 can be dipped. The fluidizing tank volume 5 is greater in the present case than in 2 and 3 illustrated examples, so that not only flat, but also really three-dimensional substrates 8th can be dipped. The walls 1a of the Fluidisierbehälters are here additionally inside with electrodes 3 equipped to avoid over-coating of the workpiece 8th to get at the bottom, ie to ensure a uniform coating from all sides. The enlarged volume 5 in the present case is complete with coating powder 5a filled.

5 shows in plan view (from above or in a viewing direction perpendicular to Fluidisierbodenebene) the power or power limitation of the individual wire electrodes 3 as they are in the 2 to 4 ge showed fluidizing devices is used. Each individual wire electrode 3 is each a high voltage resistor 3a (in the MΩ to TΩ range) upstream of the power and power limitation. The high voltage supply takes place via the high voltage generator 17 , The used wire electrodes 3 and the high voltages used correspond to those of 2 to 4 , To avoid ignition hazards, the wire electrodes 3 in each case individually by the pre-connection of the high-voltage resistors 3a Electricity and thus power limited. In the example, high-voltage resistors of 1 GΩ are connected upstream at an applied high voltage of 20 kV. This results in: I = U / R = 20 μA; P = 20 μA x 20 kV = 0.4 W maximum power. In contrast to the power limitation of the entire electrode mimic, with the shown power limitation of each individual electrode 3 no locally higher ignition powers occur. Instead of wiring with high voltage resistors 3a can also use semiconductive wire electrodes 3 (For example, ceramic fibers or glass fibers) are used. In the 6 shown fluidizing device according to the invention is constructed as that in 4 , Instead of partially along the wall 1a and partially along the fluidizing tray 2 extending over its entire length on the wall 1a or the ground 2 attached wire electrodes 3 however, become wire electrodes 3 used (again with a diameter <0.1 mm, here 40 microns), which only partially on the wall 1a or on the sinter bottom 2 are attached so that they are at least partially free in the fluid 5a are movable. At the freely movable end are the wire electrodes 3 each with an insulating cap 3b Mistake. The high voltage power supply is power limited, as in 5 as well as in the 2 to 4 shown (high voltage as there larger about 6 kV, preferably between 10 and 30 kV). In the present case is a larger number of high-voltage wire electrodes 3 So only at one end on the container edge 1a or fluidising floor 2 attached. The other end of the electrodes 3 moves freely in the fluid 5a , When the high voltage is switched on, the electrode wires are oriented 3 or their free ends in the direction of the workpiece 8th (immersed here with the help of the conveyor 16 ). To avoid short circuits, either semiconductive wire electrodes are used 3 twisted or the wires will end up as shown in the example 3b with an insulating coating or an electrically insulating plastic cap 3b Mistake. Due to the possible "looping" of the workpiece with this configuration 8th through the corona wires 3 Even with complicated workpiece geometries a homogeneous distribution of the through the corona wires 3 generated field forces. The free ends of the electrodes 3 pulls it through the grounding of the workpiece 8th to the workpiece 8th ,

In 7 an electrostatic fluidising device is shown which, like that in FIG 2 shown is constructed and operated. (also: same view, side view). In addition to the in 2 shown basic configuration has the configuration shown above the volume 5 or of the fluidizing tank 1 AC voltage electrodes 9 in the form of coil springs. These AC voltage electrodes 9 can be provided with an AC voltage in the kHz range or with a 50 Hz AC voltage or connected to such. 7a shows the side view of the described configuration. 7b shows the described configuration in supervision. The wire electrodes are power limited as already described. In the variant described, the DC voltage is thus superimposed with an AC voltage or with a pulsating DC voltage. The AC voltage electrodes 9 are located above the fluid 5a or above the volume 5 of the fluidizing tank 1 , In the present case, they are 50 mm above the unipolar negatively charged wire electrodes 3 , As alternating voltage electrodes 9 coil springs are used in the present case, but it can also be analogous to the electrodes 3 constructed thin wires are used. Through the through the AC voltage electrodes 9 generated pulsating field forces can coating particles 7 travel longer distances and the distance of the electrodes 3 to the workpiece 8th can be enlarged. In the present case, a cost-effective alternating voltage generator is used, which is the unipolar high voltage of the wire electrode 3 superimposed with 50 Hz alternating voltage (socket AC voltage). Instead of the cost-effective AC voltage generator in the 50 Hz range, however, there is also the possibility of using a generator in the kHz range (this variant is more expensive, at higher conveying speeds, for example, of> 0.5 m / s, higher-frequency AC voltage advantages in terms of homogeneity bring the deposition).

8th shows the fluidizing tank 1 a fluidizing device according to the invention, which is designed for multi-colored designs. The 8A to 8C show in each case the supervision of different design variants. variant 1 ( 8A ) Is an embodiment variant in which the fluidizing tank 1 by two substantially perpendicular to the Fluidisierbodenebene in the container 1 arranged partitions 12a and 12b in a total of three segments (A to C or 11a to 11c ) is divided. About the powder dosing 13a to 13c can different colored Beschich powder in the different segments 11a to 11c or A to C are filled. Seen in supervision, the two walls run 12a and 12b parallel to each other and with a constant distance meandering respectively double-M-shaped so that their arrangement three color areas arise so that one from left to right on the fluidizing 1 guided workpiece 8th every color area happens several times. 8B shows a corresponding two-tone variant, in which by an intermediate wall 12a the fluidizing tank 1 so in two segments 11a and 11b is divided, that when driving over the workpiece 8th (Transfer direction from left to right) each segment or a corresponding portion of it happens several times. The wall 12a runs meandering or wave-shaped so that by one on the longitudinal axis of the container (in the drawing plane: axis in the direction of the horizontal, which the container 1 divided into two equal parts) built, straight partition wall of each of the segments 11a and 11b into several subsegments (for example 11aI . 11aII . 11aIII ) would be divided. In the in 8C shown, designed for five colors variant four partitions 12a to 12d in the fluidizing tank 1 pulled so that five substantially cuboid and arranged in a row segments 11a to 11e arise. When driving over the container 1 happens the workpiece 8th then the individual segments 11a to 11e one after the other and can be coated in succession with different colors. With the in the 8A to 8C Variations can be avoided or even special designs can be made possible. The individual segments of the fluidizing tank 1 are filled with different shades (for example black, white, red, blue and yellow). This can be realized by color blends each hue by the individual segments 11 independent of each other active (high voltage on the segment electrodes turned on) are switched. The electrodes 3 the individual segments 11 are thus independently controllable. The high voltage can be varied so that any mixed color tone can be realized. Example: It becomes a segment 11a with a yellow and a segment 11b filled with a red powder. Only these two segments are active, ie to them is a high voltage created. If, for example, 20 kV is applied to the yellow segment and 10 kV to the red segment, then a yellow-orange is generated. Conversely, a red-orange is generated at 20 kV at the red segment and at 10 kV at the yellow segment. Since the mixed shades are best mixed, when the individual colors are driven several times alternately, are structures with meandering, wave-shaped or M-shaped wall arrangements 12 advantageous (see 8A and 8B , The individual segments of the fluidization container 1 can thereby separate Pulverzudosierungsvorrichtungen 13 have (these are advantageously provided laterally). Due to the meandering, M-shaped or wavy design of the segments 11 or the walls 12 Each segment needs only one dosing device 13 can be assigned because each area of the segment can be filled by them. Three dosing units are enough for three shades 13a -c, so for two shades two dosage units. For more than three shades, multiple blocks of segments or multiple fluidization tanks are preferred 1 (Such a block or such a container is in 8C shown) connected in series. Each block or container is then fed with five dosing units.

9 shows a metering system with an electrostatic fluidizing device according to the invention. 9a in this case shows a side view in a first direction in the plane of the Fluidisierbodens 2 (Wire electrodes 3 visible in the longitudinal axis direction and thus drawn as dots). 9b shows the front view, ie the view in a direction in the plane of the Fluidisierbodens perpendicular to in 9a shown viewing direction. 9c shows the top view in the direction perpendicular to the in 9a and 9b shown directions. As in 9a is shown are the wire electrodes 3 above the fluidising floor 2 in the fluidizing tank 1 arranged, but not in an area where a supply unit 13b for supplying fluidized coating powder 5a in the fluidizing tank 1 opens. The feed unit 13b has a peristaltic pump for powder dosing (control variable), which is the supply of coating powder 5a from one in relation to the container 1 higher reservoir 13a (Also a fluidizing tank with a fluidization B) allowed. The coating powder 5a for this purpose leaves the storage container 13a through a trickle opening 13c and is via the pneumatically controlled peristaltic pump of the supply unit 13b the fluidizing tank 1 fed. The system also has an ultrasonic probe 14 for level measurement on (controlled variable). This is so on the fluidizing tank 1 arranged that the level measurement in not with wire electrodes 3 provided area or in the junction area of the feed unit 13b he follows. Like the front view of the 9b as well as the top view in 9c are in the non-wire electrode equipped area of the fluidizing tank 1 by two partitions or flow breaking devices 16a and 16b divided into three parts. Im (in 9b ) left portion opens a first feeder unit 13b in the container 1 , im (in 9b ) right portion opens a second feeder unit 13b in the container 1 , Against these introduction areas is the (in 9b ) middle portion, above which the ultrasonic probe 14 is arranged through the two walls or harassment 16a and 16b separated. As the level of Fluidisierbehälters 1 To avoid parasitic effects (for example, parasitic space charge effects of the coating powder to be processed) is kept as low as possible, an automatic, continuous metering of powder as shown in the case shown required. The filling level is determined with the help of the ultrasonic measuring probe 14 supervised. The metered addition can, as in the case shown via the second fluidizing 13a However, it can also be done via Dichtestromförderprinzipien according to the prior art. With the fluidizing tank shown 13a the metering takes place via pinch valves of the feed unit 13b , As already described, the container 1 no electrodes in the dosing area 3 on. To the measuring accuracy of the ultrasonic measuring probe 14 or to improve the level measurement, are the flow breaking devices 16a . 16b in the fluidizing tank 1 introduced in the metering. These flow breakers calm the surface of the fluid 5a and thus avoid excessive shaft movements in the measuring range. The device shown is operated in the fluid at high air velocities (about 0.025 to 0.05 m / s compared to conventional flutation devices, about 0.01 m / s in the conventional fluidizing device). Such high air velocities are required, otherwise excess air ions will reduce coating quality due to reionization effects. The turbulent surface of the fluid due to the high air velocities 5a can significantly reduce the measurement accuracy of the ultrasonic probe 14 to lead. To avoid this, said flow breaking devices 16 brought in. A continuous measurement of the level is particularly necessary because of the fluidizing 1 the fluidizing device according to the invention may have a low overall height, so that it only with a small volume of fluid 5a can be filled. For this reason, a quick and accurate response of the measuring device 14 necessary to decide with sufficient accuracy and speed, whether coating powder in the container 1 must be tracked. To agglomerate the fluid 5a it is also possible to avoid the fluidizing tank 1 and / or the reservoir 13a to be provided with a vibration device (not shown).

10a shows a further dosing system using a fluidization device according to the invention in side view ( 10a ) Front view ( 10b ) and plan view ( 10c ). In the 10 The device shown initially has the same components as those in 9 shown device. In contrast to 9 however, it is a separation device 15 (in the form of a vertical wall with respect to the fluidizing floor plane) into the fluidising tank 1 introduced, so that the internal volume of the fluidizing tank 1 in two segments 15a and 15b is divided. The segment 15a here covers about 20% of Fluidisierbehältervolumens. The separating device 15 has two holes 15c on, which are arranged at a height, which is a level balance between the two segments 15a and 15b allowed. In the segment 15a are not wire electrodes 3 above the fluidising floor 2 arranged. The segment 15b corresponds in its construction to the in 9 shown Fluidisierbehälterinnenaufbau. The ultrasonic probe is above the segment 15a arranged and thus detects the level in the segment ment 15a , The separation 15 allows a separate air supply of the two segments 15a and 15b , The segment 15a represents a measuring range with lower air volume flow, the segment 15b a powder transfer and metering with higher air flow. The different airflow velocities in the segments 15a and 15b be realized by separate air supply and thereby that in the area 15a the fluidising floor 2 has a smaller pore size. In the area 15b Accordingly, the segment bottom has a higher pore size. Thus, a fluidizing floor with a different pore width is used in segments. In segment 15a the pore width of the fluidization tray is 10 μm, in the segment 15b the pore size is 30 μm. This results in a significant reduction in airspeed and more than 50% in the range 15a , The measurement of the filling level by the measuring probe 14 This can be done with an accuracy in the millimeter range. By the segmentation of the fluidizing tank 1 In the field of ultrasonic measurement, the air speed can therefore be considerably reduced by separate air supply. Through the separation device 15 or the corresponding wall becomes a wave motion in the area 15a (caused by the addition of powder 5a via the metering unit 13b ) reliably avoided. Nevertheless, with the help of the openings 15c for the coating powder 5a a level compensation possible.

11 shows the use of the fluidizing device according to the invention together with the DE 101 630 25 A1 known transfer application method. 11a shows first a three-dimensional view of a corresponding coating device. 11b shows a fluidizing device according to the invention with fluidizing tank 1 , Fluidising floor 2 and wire electrodes 3 and with a volume 5 within the fluidizing tank 1 in which is the fluid 5a located. Not shown is the air supply 4 of the container 1 , Shown are also air ions and electrically charged coating powder particles 7 , Above the fluidizing tank 1 with a height of about b ₂ = 100 mm is a transfer device 17 with a metering roller 17c , a transfer ribbon 17b and a roller 17a , The transfer band 17b gets through the two rollers 17a and 17c emotional. In the lower transfer belt area is located above the Fluidisierbehälters 1 and immediately above the transfer belt 17b an electrically conductive deposit 10 in the form of a metal plate. Immediately above the underlying Transferbandteils is located to the left of the fluidization 1 between fluidizing tank 1 and roller 17a a transfer electrode 18a , Below the fluidizing tank 1 becomes the grounded substrate 8th moved past. By fluidizing device according to the invention including electrostatic deposit 10 becomes electrostatically charged coating powder 7 on the transfer belt 17b transfer. The transfer belt areas loaded with coating powder become due to movement of the rollers 17a and 17c to the transfer electrode 18a emotional. With the help of this transfer electrode 18a (electrostatic repulsion), the charged coating powder on the substrate 8th transfer. Crucial here is that due to the low height b ₂ a direct transfer of the coating material from the transfer belt 17b on the substrate 8th is possible because only a small distance has to be overcome. 11c shows a metering device including fluidizing device according to the invention as in 11b shown is constructed. In contrast to 11b however, it does not become a transfer electrode 18a but an electrically conductive, connected to a high voltage source roller brush 18b used with which an angled spray can be generated to the substrate 8th to coat. As in 11b is (due to the low height b ₂ conditionally) of the coating material only a small distance between the transfer belt 17b and substrate 8th to overcome, so that the coating material transfer can be done without additional devices (such as additional rollers, transfer belts or the like). The already coated area of the substrate 8th is in the 11b and 11c by the reference numeral 8a characterized. Due to the high voltage set transfer electrode 18a or roller brush 18b the coating powder is charged again in the case presented, so that in combination with the low height b _2, the powder part Chen the transfer distance between the lower band area and the substrate 8th can overcome without additional devices.

12 shows another example of a coating apparatus using a fluidizing device according to the invention. Shown is a fluidizing device with a fluidizing tank 1 , which is divided into two segments 1c and 1d with separate air supply 4a and 4b is divided. The fluidizing tank 1 is tilted from the horizontal by about 45 °. Above the range 1c of the fluidizing tank 1 there is another fluidizing tank 13a , In this opens a device for continuous powder metering to maintain a constant Pulverfüllhe (arrow top left in the container 13a ). The fluidizing powder 5a trickles out of the container 13a through the Ausrieselöffnung 13c by gravity on the fluidising floor 2 above the range 1d of the fluidizing tank 1 , Only in this area 1d or above this range 1d is the fluidising floor 2 with thin wire electrodes 3 Mistake. Using the wire electrodes 3 will be above the range 1d as described in the preceding examples in a coating area 6 a charged powder cloud 7 generated with charged particles and air ions. From the container 1 if necessary trickling powder is through a collecting container 19 collected. In the left area of the coating device shown is a transfer device 17 arranged according to the in 11 constructed a transfer device: An electrically conductive loading or metering roller 17c and a second roller 17a move the transfer belt by turning it around its axis 17b (electrically semiconducting to insulating). The ribbon 17b will be in the area 6 coated by the powder cloud. The coated area of the band 17b goes in the direction of the powder application area 8b emotional. An electrically conductive deposit 10 (metal plate) prevents the coating powder from the belt 17b drops. The transfer of the coating powder to the substrate 8th done in the area 8b with the help of the roller 17a to which a potential of about 10 kV is applied. Alternatively, a wire electrode as already sufficiently disclosed in the invention may also be used for the transmission. The coating on the substrate is indicated by the reference numeral 8a characterized. The coated transfer belt area (between powder cloud area 6 and application area 8b ) is denoted by the reference numeral 17d characterized.

Claims (70)

Electrostatic fluidizing device with a fluidizing container ( 1 ), one into the fluidizing tank ( 1 ) opening air supply ( 4 ) for introducing fluidizing air into the fluidising container ( 1 ), and one above the mouth of the air supply ( 4 ) within the fluidizing tank ( 1 ) arranged fluidizing bottom ( 2 ), through which the fluidizing air above the fluidizing floor ( 2 ) ( 5 ) within the fluidizing tank ( 1 ) can be fed to the fluidization of coating powder, characterized in that above the Fluidisierbodens ( 2 ) in volume ( 5 ) within the fluidizing tank ( 1 ) as high voltage electrodes at least two thin electrode wires as wire electrodes ( 3 ) are arranged for the ionization of the fluidizing air exposed from each other, that the at least two wire electrodes ( 3 ) in each case a high-voltage resistor ( 3a ) and that the at least two wire electrodes ( 3 ) have a mean distance from each other of more than 2 mm and / or less than 80 mm. Fluidizing device according to the preceding claim, characterized in that the average diameter of at least one of the wire electrodes ( 3 ) is more than 20 μm and / or less than 1000 μm or more than 60 μm and / or less than 100 μm. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) in the immediate vicinity of the fluidizing floor ( 2 ) or on the fluidising floor ( 2 ) is arranged adjacent and / or that the average distance of at least one of the wire electrodes ( 3 ) from the fluidising floor ( 2 ) up to 50 mm or up to 20 mm. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) substantially parallel to the surface of the Fluidisierbodens ( 2 ) is arranged and / or that at least one of the wire electrodes ( 3 ) in a form-fitting manner on the fluidising floor ( 2 ) is arranged. Fluidising device according to one of the preceding claims, characterized in that at least two of the wire electrodes ( 3 ) are substantially parallel to each other. Fluidising device according to one of the preceding claims, characterized in that at least two of the wire electrodes ( 3 ) have an average distance of more than 10 mm and / or less than 30 mm. Fluidising device according to one of the preceding claims, characterized in that the high-voltage resistors ( 3a ) has a resistance value in the range of 1 MΩ to 1000 TΩ point. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) partially substantially parallel to the surface of the Fluidisierbodens ( 2 ) is arranged and / or positively on the fluidization ( 2 ) is arranged and partially substantially parallel to at least one side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged and / or positively on at least one side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) partly in the immediate vicinity of the fluidizing floor ( 2 ) or on the fluidising floor ( 2 ) adjacent and / or at an average distance of up to 50 mm or up to 20 mm from the fluidising floor ( 2 ) and partially in the immediate vicinity of at least one side wall ( 1a ) of the fluidizing tank ( 1 ) or at least one side wall ( 1a ) of the fluidizing tank ( 1 ) adjacent and / or at an average distance of up to 50 mm or of up to 20 mm from at least one side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged. Fluidizing device according to one of the preceding claims, characterized in that at least one wire electrode ( 3 ) in the immediate vicinity of the fluidizing floor ( 2 ) or on the fluidising floor ( 2 ) adjacent and / or at an average distance of up to 50 mm or up to 20 mm from the fluidising floor ( 2 ) and wherein at least one wire electrode ( 3 ) in the immediate vicinity of a side wall ( 1a ) of the fluidizing tank ( 1 ) or on a side wall ( 1a ) of the fluidizing tank ( 1 ) adjacent and / or at an average distance of up to 50 mm or of up to 20 mm from a side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) substantially parallel to the surface of the Fluidisierbodens ( 2 ) is arranged and / or positively on the fluidization ( 2 ) and at least one of the wire electrodes ( 3 ) substantially parallel to the surface of a side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged and / or positively on a side wall ( 1a ) of the fluidizing tank ( 1 ) is arranged. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) not over its entire length at the fluidising floor ( 2 ) and / or on a side wall ( 1a ) of the fluidizing tank ( 1 ) and / or that at least one of the wire electrodes ( 3 ) only at one of its ends on the fluidising floor ( 2 ) and / or on a side wall ( 1a ) of the fluidizing tank ( 1 ) is attached. Fluidizing device according to the preceding claim, characterized in that at least one of the wire electrodes (not fastened over its entire length) is ( 3 ) is provided in the non-attached area at least partially with an insulating coating or an electrically insulating plastic cap ( 3b ) having. Fluidising device according to one of the preceding claims, characterized in that at least one of the wire electrodes ( 3 ) contains or consists of a semiconducting material, a semiconducting ceramic fiber or a glass fiber. Fluidizing device according to the preceding Claim, characterized in that the resistance at least one of the wire electrodes has a value of 1 MΩ to 1000 TΩ. Fluidising device according to one of the preceding claims, characterized in that a further fluidizing bottom is provided inside the fluidising container ( 1 ) and above at least one of the wire electrodes ( 3 ) or that at least one of the wire electrodes ( 3 ) into the fluidising floor ( 2 ) is incorporated, sewn or integrated or in the fluidized bed ( 2 ) is arranged. Fluidizing device according to the preceding claim, characterized in that the further fluidising bottom is thinner than the fluidising bottom ( 2 ) and / or that the further fluidising floor has a thickness of more than 1 mm and / or less than 10 mm or more than 2 mm and / or less than 5 mm. Fluidizing device according to one of the preceding claims, characterized in that above at least one of the wire electrodes ( 3 ) at least one AC voltage electrode ( 9 ) in volume ( 5 ) of the fluidizing tank or above the volume ( 5 ) and / or of the fluidizing tank ( 1 ) is arranged. Fluidising device according to the preceding claim, characterized in that at least one of the alternating voltage electrodes ( 9 ) has a coil spring or that at least one of the AC voltage electrodes ( 9 ) is constructed as one of the wire electrodes of one of claims 2 or 8 or that at least two AC voltage electrodes ( 9 ) are arranged or constructed like the two wire electrodes of one of Claims 5, 6 or 7. Fluidising device according to one of claims 18 or 19, characterized in that at least one of the alternating voltage electrodes ( 9 ) above 5 mm and / or below 100 mm or above 30 mm and / or below 70 mm above the fluidising tray ( 2 ) and / or above one in the immediate vicinity of the fluidizing floor ( 2 ) arranged wire electrode ( 3 ) is arranged. Fluidising device according to one of claims 18 to 20, characterized by a with at least one of the alternating voltage electrodes ( 9 ) or 50 Hz alternating voltage generator or at least one of the alternating voltage electrodes ( 9 ) connected AC voltage generator in the kHz range. Fluidising device according to one of the preceding claims, characterized by side walls ( 1a ) of the fluidizing tank ( 1 ) and / or a floor ( 1b ) of the fluidizing tank ( 1 ), which comprise electrically insulating materials and / or plastic, POM, polymide-based materials, glass and / or ceramic materials. Fluidising device according to one of the preceding claims, characterized by a fluidising floor ( 2 ) which contains or consists of a polyethylene sintered bottom with pore widths of more than 2 μm and / or less than 100 μm or more than 10 μm and / or less than 50 μm and / or an inorganic sintered bottom and / or a ceramic sintered bottom and / or a glass sintered bottom , Fluidising device according to one of the preceding claims, characterized by an above the fluidizing container ( 1 ) arranged electrically conductive deposit ( 10 ) or a metal plate or an electrode. Fluidising device according to the preceding claim, characterized in that the electrically conductive deposit ( 10 ) has a structure and / or a pattern or is designed in the form of a template. Fluidising device according to one of the preceding claims, characterized by a fluidizing container (in 1 ) opening metering device ( 13 ) for the automatic and / or continuous metering of coating material into the fluidizing container ( 1 ). Fluidizing device according to the preceding claim, characterized in that the metering device ( 13 ) a storage container ( 13a ) for storing coating material and at least one in the fluidizing ( 1 ) and the storage container ( 13a ) infeed unit ( 13b ) and / or a density flow conveying device. Fluidizing device according to the preceding claim, characterized in that the storage container ( 13a ) has a further fluidizing container, which preferably has larger dimensions and / or a larger filling volume than the fluidizing container ( 1 ), and / or that at least one of the feed units ( 13b ) a peristaltic pump, pinch valves, in the region of the mouth to the storage container ( 13a ) has a trickle opening and / or a pipe. Fluidizing device according to one of claims 26 to 28, characterized in that in the region of the mouth of the metering device ( 13 ) in the fluidizing tank ( 1 ) at least one flow breaking device ( 16 ) is arranged. Fluidizing device according to the preceding Claim, characterized in that the flow breaking device a Wall is. Fluidizing device according to one of claims 26 to 30, characterized in that in the region of the mouth of the metering device ( 13 ) no wire electrodes ( 3 ) are arranged. Fluidising device according to one of the preceding claims, characterized by a fluidizing container (in 1 ) integrated or arranged on it level measuring device ( 14 ) for determining the coating powder filling height in the fluidizing container ( 1 ). Fluidizing device according to the preceding claim, characterized in that the level measuring device ( 14 ) has an ultrasonic probe. Fluidizing device according to claim 29 and one of claims 32 to 33, characterized in that the level measuring device ( 14 ) and at least one of the flow breaking devices ( 16 ), and / or at least one of the flow breaking devices which has two walls, are arranged so that a detection of the filling level in a through the flow breaking device ( 16 ) motion-calmed area and / or between the two walls, is feasible. Fluidising device according to one of the preceding claims, characterized in that one within the fluidizing container ( 1 ) or in this integrated separation contraption ( 15 ) the fluidizing tank ( 1 ) into at least two segments ( 15a . 15b ) divided that both segments ( 15a . 15b ) are independent and unaffected from each other separately supplied with fluidizing air. Fluidising device according to the preceding claim, characterized in that each of the segments ( 15a . 15b ) own air supply ( 4 ) having. Fluidizing device according to one of claims 35 or 36, characterized in that the separation device ( 15 ) at least one opening ( 15c ) for filling level compensation of the coating powder. Fluidizing device according to one of claims 26 to 31, according to one of claims 32 to 34 or according to one of claims 35 to 37, characterized in that the level measuring device ( 14 ) in the area of the first segment ( 15a ) to the fluidizing tank ( 1 ) is arranged or integrated in that the wire electrodes ( 3 ) within the second segment ( 15b ) are arranged and that the metering device ( 13 ) in the region of the second segment. Fluidising device according to one of claims 35 to 38, characterized in that the fluidising floor ( 2 ) and / or its part within the first segment ( 15a ) has a smaller pore size than the fluidization bottom ( 2 ) or its part within the second segment ( 15b ). Fluidizing device according to the preceding claim, characterized in that the fluidising floor ( 2 ) and / or its part within the first segment ( 15a ) has a pore width in the range of more than 2 microns and / or less than 20 microns or more than 5 microns and / or less than 15 microns and that the fluidized bed ( 2 ) and / or its part within the second segment ( 15b ) has a pore size in the range of about 20 microns and / or less than 70 microns or more than 25 microns and / or less than 50 microns. Fluidizing device according to one of the preceding claims, characterized in that the fluidizing container ( 1 ) into at least two segments ( 11 ), wherein at least two of the segments ( 11a . 11b ) and / or their volumes are so separated from each other and / or closed off from each other, that in the volume of the one segment ( 11a ) Coating powder unaffected by the other segment ( 11b ), its volume, or into the volume of the other segment ( 11b ) is fluidizable introduced coating powder. Fluidising device according to the preceding claim, characterized in that the termination and / or the separation of the at least two segments ( 11a . 11b ) with the aid of at least one in the fluidization tank ( 1 ) arranged intermediate wall ( 12 ) he follows. Fluidising device according to the preceding claim, characterized in that at least one of the intermediate walls ( 12 ) is arranged and / or shaped so that by a to the fluidization ( 2 ) in the substantially vertical plane of at least one of the segments ( 11 ) into at least three separate sub-volumes ( 11I . 11II . 11III ) is divided. Fluidising device according to one of claims 42 to 43, characterized in that at least one of the intermediate walls ( 12 ) in a substantially parallel to the fluidization ( 2 ) level has a substantially M-shaped, wavy, sawtooth or meandering shape. Fluidizing device according to one of claims 43 or 44, characterized by two substantially constant spaced apart partitions (Fig. 12a . 12b ). Fluidizing device according to one of claims 42 to 45, characterized in that at least two partitions ( 12 ) are arranged substantially parallel to each other so that through this the fluidizing container ( 1 ) in a fluidizing floor ( 2 ) in substantially parallel direction in at least three consecutive segments ( 11a . 11b . 11c ) is divided. Fluidising device according to one of claims 41 to 46, characterized in that at least two of the segments ( 11 ) at least one wire electrode ( 3 ), these at least two wire electrodes ( 3 ) are independently controllable and / or assignable with high voltage. Fluidising device according to one of claims 41 to 47, characterized in that at least two of the segments ( 11 ) each having a separate Zudosiervorrichtung according to any one of claims 26 to 31. Electrostatic fluidizing method, wherein a fluidizing container ( 1 ) Fluidizing air is supplied, wherein the fluidizing air through a within the fluidizing ( 1 ) arranged fluidizing bottom ( 2 ) through one above the Fluidisierbodens ( 2 ) within the fluidizing tank ( 1 ) volume ( 5 ), wherein the fluidizing air by means of at least two, above the fluidising floor ( 2 ) in volume ( 5 ) within the fluidizing tank ( 1 ) spaced apart as high voltage electrodes, thin electrode wires as thin wire electrodes ( 3 ) is at least partially ionized, and wherein in the volume ( 5 ) Coating powder ( 5a ) is fluidized by the at least partially ionized fluidizing air and at least partially charged electrostatically, characterized in that the high voltage to the at least two wire electrodes via one of the respective wire electrode upstream high-voltage resistor ( 3a ) and that the at least two wire electrodes ( 3 ) have a mean distance from each other of more than 2 mm and / or less than 80 mm. Fluidization method according to the preceding Claim, characterized in that an electrostatic fluidizing device according to one of the claims 1 to 48 is used. Fluidizing method according to one of claims 49 or 50, characterized in that the average diameter of at least one of the wire electrodes ( 3 ) is more than 20 μm and / or less than 1000 μm. Fluidizing method according to one of claims 49 to 51, characterized in that the average diameter of at least one of the wire electrodes ( 3 ) is above 60 μm and / or below 100 μm. Fluidizing method according to one of claims 49 to 52, characterized in that for fluidization and ionization of the coating powder ( 5a ) within the fluidizing tank ( 1 ) Fluidizing air speeds of above 0.01 and / or below 0.2 m / s or above 0.025 and / or below 0.05 m / s are used. Fluidizing method according to one of claims 49 to 52, characterized in that the filling level of the coating powder ( 5a ) in the fluidizing tank ( 1 ) is kept as low as possible in order to prevent and / or minimize disturbing effects and / or disturbing effects due to space charge effects. Fluidizing method according to one of claims 49 to 54, characterized in that a workpiece ( 8th ) via a fluidizing cloud ( 6 ) of at least partially electrostatically charged coating powder ( 7 ) is guided for at least partial coating of the workpiece ( 8th ) with coating powder. Fluidization method according to the preceding Claim, characterized in that the workpiece grounded is. Fluidizing method according to the preceding claim, characterized in that the workpiece ( 8th ) in the fluidizing tank ( 1 ) and / or into the fluidizing tank ( 1 ) fluidized coating powder ( 5a ) is immersed. Fluidizing method according to one of Claims 49 to 57, characterized in that at least one of the wire electrodes ( 3 ) a DC voltage of more than 3 kV and / or below 50 kV is applied. Fluidizing method according to one of Claims 49 to 58, characterized in that at least one of the wire electrodes ( 3 ) a DC voltage of more than 5 kV and / or 30 kV is applied. Fluidizing method according to the preceding claim, characterized in that the DC voltage with the aid of at least one AC voltage electrode ( 9 ) a 50 Hz AC voltage or an AC voltage in the kHz range is superimposed. Fluidizing method according to one of claims 49 to 60, characterized in that to improve the electrostatic application of coating powder ( 7 ) on a workpiece ( 8th ) an electrically conductive deposit ( 10 ) and / or a metal plate or an electrode is used. Fluidising method according to the preceding claim, characterized in that the electrically conductive deposit ( 10 ) has a structure and / or a pattern or is designed in the form of a template and that images, patterns or structures on the workpiece ( 8th ) are coated. Fluidization method according to the preceding Claim, characterized in that when applying the structures, Patterns or pictures are driven clocked. Fluidization method according to one of the claims 49 to 63 , characterized in that automatically and / or continuously coating material into the fluidizing container ( 1 ) is metered. Fluidizing method according to one of claims 49 to 64, characterized in that the level of the coating powder in the fluidizing container ( 1 ) is measured or determined. Fluidizing method according to the preceding claim, characterized in that in Range of measurement and / or determination of the level of the coating powder, the Fluidisierluftgeschwindigkeit in the fluid is reduced compared to the Fluidisierluftgeschwindigkeit in the fluid outside the range of determination and / or measurement. Fluidisation method according to one of claims 65 or 66, characterized in that the measurement and / or determination the level of the Coating powder by means of ultrasound. Fluidizing method according to one of claims 49 to 67, characterized in that the fluidising container ( 1 ) into at least two segments ( 11 ), wherein at least two of the segments ( 11a . 11b ) and / or their volumes are separated from one another and / or closed off from one another in such a way that one enters the volume of the one segment ( 11a ) introduced coating powder unaffected by a in the volume of the other segment ( 11b ) is fluidized coating powder introduced. Fluidizing method according to the preceding claim, characterized in that a workpiece ( 8th ) by a mixture of coating powder from different segments ( 11a . 11b ) is coated by applying to the different segments ( 11a . 11b ) alternately, one after the other or simultaneously the same high or different high voltages (DC voltages) in the range of about 3 kV and / or below 50 kV are applied. Fluidizing method according to the preceding claim, characterized in that a workpiece ( 8th ) by a mixture of coating powder from different segments ( 11a . 11b ) is coated by applying to the different segments ( 11a . 11b ) alternately, one after the other or simultaneously high or different high voltages (DC voltages) in the range of about 5 kV and / or below 30 kV are applied.