EP3999674A1 - Method for cleaning electrophoretic coating baths, and device therefor - Google Patents

Method for cleaning electrophoretic coating baths, and device therefor

Info

Publication number
EP3999674A1
EP3999674A1 EP20737502.3A EP20737502A EP3999674A1 EP 3999674 A1 EP3999674 A1 EP 3999674A1 EP 20737502 A EP20737502 A EP 20737502A EP 3999674 A1 EP3999674 A1 EP 3999674A1
Authority
EP
European Patent Office
Prior art keywords
skid
filter medium
bath
filter
electrodeposition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20737502.3A
Other languages
German (de)
French (fr)
Inventor
Dominik PABST
Rolf Schulte
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF Coatings GmbH
Original Assignee
BASF Coatings GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF Coatings GmbH filed Critical BASF Coatings GmbH
Publication of EP3999674A1 publication Critical patent/EP3999674A1/en
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/05—Floating filters
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • C25D13/24—Regeneration of process liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/01—Filters with filtering elements which move during the filtering operation with translationally moving filtering elements, e.g. pistons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/35—Filters with filtering elements which move during the filtering operation with multiple filtering elements characterised by their mutual disposition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/802—Device for changing the inclination of the filtering element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D33/00—Filters with filtering elements which move during the filtering operation
    • B01D33/80—Accessories
    • B01D33/804—Accessories integrally combined with devices for controlling the filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/12—Devices for taking out of action one or more units of multi- unit filters, e.g. for regeneration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
    • B01D35/16—Cleaning-out devices, e.g. for removing the cake from the filter casing or for evacuating the last remnants of liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D36/00—Filter circuits or combinations of filters with other separating devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/26—Transport systems for filtering devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2201/00—Details relating to filtering apparatus
    • B01D2201/64—Filters having floating elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0407—Additives and treatments of the filtering material comprising particulate additives, e.g. adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0414—Surface modifiers, e.g. comprising ion exchange groups
    • B01D2239/0428—Rendering the filter material hydrophobic

Definitions

  • the present invention relates to a method for purifying
  • Electrocoating baths in particular a method for removing
  • Continuous systems have the advantage that higher throughput rates can be achieved, there is usually less susceptibility to failure and lower investment costs are associated with this.
  • Continuous systems are operated continuously and the items to be painted are transported on racks, so-called skids, through the immersion paint basin filled with the electrodeposition paint.
  • craters are “small, round depressions in the coating that remain after drying” (DIN EN ISO 4618-2).
  • the term “crater” is understood to mean film defects that are characterized by a bead-like elevation on the edge and a plate-like depression that often extends almost to the ground. Such disturbances can have a diameter of up to several millimeters. Even after the topcoat has been applied, they are often still recognizable on the substrate surface, for example the surface of the automobile body, and therefore require complex and cost-intensive rework.
  • the tendency to crater formation increases with the gradient of the surface tension in the area of the fault.
  • the difference between the surface tension of the paint and the interfering substance serves as a measure for this quantity.
  • Fats or oils, silicone and organic fluorine compounds in particular occur as interfering substances.
  • Cathodic electrodeposition paint binders are usually based on epoxy resins, so that a surface tension of around 46 mN / m can be assumed.
  • Organic fluorine compounds and silicones especially polydialkylsiloxanes have much lower surface tensions of around 20 mN / m. Fats and oils are significantly higher, but at around 30 mN / m, they are still significantly below the electrodeposition paint binders.
  • the difference between the surface tension of the paint film and the interfering substance is one of the causes of the crater sensitivity of electrodeposition paints. In practice, however, it is hardly possible to completely exclude the introduction of interfering substances into the electrocoating bath.
  • fluorine-containing compounds are used as lubricants in conveyor technology.
  • Silicones can be introduced in various ways. For example, fats or oils that contain small amounts of silicone-containing auxiliaries are often used in forming technology. Usually, it is not possible to do without fats or oils themselves in the production of the shell components.
  • WO 87/03016 describes a method for removing impurities that cause surface disturbances from electrodeposition baths, the electrodeposition paint being filtered through an adsorption material without pressure in addition to the cleaning operations that are already common, so that hydrophobic substances with a surface tension of ⁇ 35 mN / m are adsorbed.
  • the hydrophobic substances are preferably homopolymers or copolymers of ethylene, propylene, butene-1 or butene-2, which optionally contain further non-polar copolymers. Fibrous polypropylene in the form is particularly preferred a flake material is used as an adsorbent.
  • filter bags filled with absorbent are installed in the paint circuit of the electrocoating system in such a way that the additional filtration can be easily switched on or off as required.
  • a filter with a filter cartridge arranged in a filter housing is proposed for the same purpose, the filter cartridge comprising a fiber packing as an adsorption fleece web.
  • the filter devices are accommodated in the paint cycle system and the bulk phase of the paint flows through them. Due to the sluggish absorption kinetics, installing these special filters in the filter housing is not very effective, as the flow velocity of the paint is very high here and the contact time between the interfering substance and the fiber fleece is very short. In addition, reducing the effectiveness is that due to the low density and increased hydrophobicity of the interfering substances compared to the aqueous immersion bath, an accumulation of the interfering substances takes place at the interface between the immersion bath and air. Since the pumps for circulating the bath and for circulating the system suck in the paint at the bottom of the pool, the paint volume flow contains only inadequate quantities of the interfering substances, which is why the efficiency of such filter processes is also inadequate.
  • a fiber fleece made of polypropylene is therefore placed on the surface of the electrocoating bath with appropriate holders. This is usually done in front of the overflow pocket of the dip paint tank so that the bodies conveyed through the system do not collide with the filter barrier.
  • the advantage of this procedure is that the contact time between interfering substances and the filter fleece is maximum and that the filter is brought to where the interfering substances are usually located for cleaning.
  • the floating filter barrier is activated by two people, for example, who sit on opposite immersion paint basins. edges are drawn several times over the bath surface.
  • the disadvantage of this procedure is that production has to be interrupted, since the personnel have to work directly at the edge of the dip pool and the dip painting process has to be interrupted for safety reasons.
  • the conveyor technology - shuttle conveying or overhead conveying or combined processes makes it difficult to skim the surface.
  • the work area is mostly inaccessible and contaminated with paint.
  • the dip painting process must also be interrupted again to replace the filter.
  • the method should enable the removal of interfering substances, in particular those that accumulate on the surface of the electrodeposition paint bath, without stopping the paint shop and thus effectively during operation.
  • the movable connecting element (3) allows the filter medium (2) to be aligned at the interface between the electrodeposition bath and air, and (d) the filter medium (2) after immersion of the skid (1) in the electrodeposition bath during the conveyance of the skid (1) through the electrodeposition bath is aligned at the interface between the electrodeposition bath and air and is drawn along the surface of the electrodeposition bath.
  • This method is referred to below as the method according to the invention.
  • Step (d) is used here to contact the filter medium with interfering substances present on the surface of the electrodeposition paint bath, these being absorbed in the process.
  • electrocoat bath stands for the electrocoat located in an electrocoat basin, i.e. an aqueous coating material that is suitable for electrocoating (DIN 55655-1: 2014-11).
  • interfering substances are understood to mean in particular those substances which accumulate on the surface of the electrodeposition paint bath and / or have a surface tension of less than 35 mN / m, both conditions preferably being met.
  • the surface tension of a substance can be determined according to DIN EN 14370: 2004-11 using the Du Noüy ring method or the Wilhelmy patten method. Due to the movement of the ring during the measurement process, the ring method is only a quasi-static method. In the case of liquids that develop the equilibrium value of surface tension only slowly, the static plate method according to Wilhelmy is preferred. However, this does not mean that the interfering substances are only located on the surface of the electrodeposition paint bath.
  • interfering substances can get from the surface of the electrodeposition paint bath into the bulk phase of the electrodeposition paint bath, in particular when the skids (1) are immersed, or only detach from the item to be painted in the bulk phase of the electrodeposition paint bath.
  • film defects also referred to as film damage or film defects
  • coating defects are defined as coating defects which are characterized by defects in the coating and which are usually based on their Shape or its appearance. Interfering substances as they are often contained in electrocoating baths, in turn, often lead to crater-shaped film defects, so-called craters as defined above.
  • a “continuous system” is understood to mean an electrocoating system in which, in contrast to batch-wise loading, as is done in cycle systems, the goods to be coated are continuously passed through.
  • skid stands for a frame which usually serves to hold the item to be painted, but within the scope of the present invention preferably instead of the item to be painted, or less preferably in addition to it, is connected to the filter medium (2).
  • a further frame can be attached to the skid (1), which - if present - is regarded as belonging to the skid (1). If another frame is attached to the skid (1), the connecting element (3) and filter medium (2) can also be located on this. Preferably, no further frame is attached to the skid.
  • filter medium (2) as it is used here is a common term from filtration technology and represents the material used for filtering.
  • the term “item to be painted” is understood to mean all parts intended for coating in the electrodeposition bath.
  • the goods to be painted are electrically conductive, preferably metallic. These can be simply shaped parts such as sheet metal, but also complex three-dimensional parts such as motor vehicle bodies.
  • the “surface of the electrocoat bath” is the area of the electrocoat that is in contact with the ambient air.
  • “Pulling the filter medium (2) along the surface of the electrodeposition bath” is understood to mean that the filter medium (2) protrudes into both the ambient air and the electrodeposition bath volume and with the conveyance of the skid (1) through the electrodeposition bath along the surface of the Electrocoat bath is drawn and in this way comes into contact with the interfering substances located on the surface of the electrocoat bath.
  • a “connecting element” (3) is understood to mean a component that connects the filter medium (2) to the skid (3).
  • the connecting element (3) is movable. This means that the connecting element (3) is variable in the distance between the skid (1) and the filter medium (2), so that the filter medium (2) is conveyed through the electrodeposition bath even when the skid (1) is immersed in the electrodeposition bath at different depths can be drawn along the surface of the electrodeposition bath in the conveying direction.
  • the length of the connecting element (3) must accordingly be dimensioned in such a way that the filter medium (2) connected to the connecting element (3) can be drawn along the surface of the electrodeposition bath when the skid (1) is immersed to a maximum depth in the electrodeposition bath.
  • the connecting element (3) preferably has a folding mechanism.
  • the method according to the invention is characterized in that the skids (1) that are already present - as they are used for painting the items to be painted - can now also be used as a transport frame for the filter medium (2) and are therefore complex Adjustments to the continuous electrodeposition system for carrying out the process according to the invention are not necessary. Rather, skids (1) equipped according to the invention can be kept in stand-by so that they can be used immediately if necessary and to replace a skid (1) equipped with paint items during operation.
  • the skid (1) passes through the electrodeposition paint basin in the usual manner, as is the case when the skid (1) is loaded with the item to be painted.
  • the filter medium (2) is arranged on the skid (1) in such a way that the connecting element (3) or the connecting elements (3) of the filter medium (2) with the skid (1) or the frame separately attached to the skid enable that the filter medium (2) aligns itself at the interface between the electrocoating bath and air.
  • the filter medium (2) is therefore preferably connected to the side of the skid (1) via the connecting element (s) (3) which, when carrying out the method according to the invention, points in the direction of said interface.
  • connection between the skid (1) on the one hand and the filter medium (2) on the other hand is preferably made via one or more hinged connecting elements (3) which open when the device is in operation.
  • the opening of the preferably foldable connecting element (s) (3) between the skid (1) on the one hand and the filter medium (2) on the other hand can preferably be done by one or more buoyancy bodies (4) (or floats) preferably attached to the filter medium (2) and / or connecting element (3) (4)).
  • the buoyancy body (s) (4) are preferably arranged in such a way that they lie behind the filter medium (2) when the skid (1) is being conveyed, and the flow can thus flow against the filter medium (2) without hindrance.
  • the floating bodies (4) hold the filter medium (2) on the surface of the electrocoating bath and align the filter medium (2).
  • the filter medium (2) and preferably also the float (4) are connected to the skid in such a way that the filter medium (2) covers the entire width or almost occupy the entire width, for example at least 80%, preferably at least 90% and particularly preferably at least 95% of the width of the dip lacquer basin.
  • the filter medium (2) preferably protrudes laterally beyond the skid (1).
  • the connecting element (3) between the filter medium (2) and the skid (1) or a frame attached separately to the skid (1) can drive the filter medium (2) the surface of the electrocoating bath promotes.
  • the filter medium (2) itself already functions as a float (4) due to its density or enclosed flea spaces and thus takes on the combined function of a filter medium (2) and float (4).
  • the filter medium (2) is preferably elongated and, when the method is carried out, is arranged essentially perpendicular to the conveying direction of the skid (1) on the surface of the electrocoating bath. In principle, however, other geometries of the filter medium (2) are also possible.
  • the filter medium (2) can also be designed, for example, V-shaped, U-shaped or zigzag-shaped, for example in order to enlarge the available adsorbing surface of the filter medium (2).
  • the filter medium (2) enables the electrodeposition bath to be cleaned, in particular the absorption of the interfering substances on the surface of the electrodeposition bath.
  • the filter medium (2) therefore consists of a material that has an affinity for the typical interfering substances. In principle, adsorption can take place chemically (chemisorption) or physically (physisorption). This is preferably done physically.
  • Water-repellent polymers also known as hydrophobic polymers, have a particularly good affinity for the interfering substances that are typically present in electrocoating baths.
  • These include preferably polyalkylenes, such as in particular polyethylenes, polypropylenes, polybutylenes and the copolymers of at least two monomers selected from the group consisting of ethylene, propylene, 1-butylene and 2-butylene.
  • the aforementioned polymers can contain other non-polar co-monomers. Since the various polymers and copolymers have different polarities, they can also be combined with one another in a preferred embodiment in order to cover an affinity for the broadest possible spectrum of interfering substances.
  • the configuration of the filter medium (2) in the form of a textile flat product preferably selected from the group of woven, knitted, knitted fabrics, felts or nonwovens is particularly suitable.
  • the design of the filter medium (2) in the form of a non-woven fabric is particularly suitable.
  • the flat textile products, in particular the nonwovens, are preferably rolled here and the rolls are preferably used in the form of the geometries mentioned above.
  • water-repellent polymers for example in the form of a fibrous flake material, in preferably tubular nets or tubular bags permeable to the electrodeposition paint, and to use them as filter medium (2) in the same way as the aforementioned roles.
  • the invention also relates to a skid (1) for continuous electrodeposition paint systems, the skid (1) having a filter medium (2) which is connected to the skid (1) via one or more connecting elements (3) in such a way that the filter medium can align itself at the interface between the electrocoat bath and air when the continuous electrodeposition system is in operation.
  • the connecting elements (3) are movable, as already described above for the method according to the invention, in which the skid can be used.
  • This skid (1) equipped in this way is referred to below as the skid (1) according to the invention.
  • one or more additional filter inserts (5) are attached to the skid (1).
  • These filter inserts (5) preferably have an elongated design and are in contrast to the above described filter medium (2) preferably arranged parallel to the conveying direction of the skid (1).
  • These additional filter inserts (5) are located during the cleaning process - also in contrast to the filter media (2) described above - mainly in the bulk phase of the electrocoating bath. Only during immersion and emergence are parts of the additional filter insert (s) (5) not completely in the bulk phase of the electrocoating bath.
  • Immersion into the electrodeposition bath typically takes place with the opening of the filter insert (5) first, whereby surface contamination can already be absorbed in the immersion zone of the electrodeposition bath as it passes through the surface of the electrodeposition bath. The same thing happens when surfacing in the surface area of the electrocoating tank. After complete immersion and before surfacing, the additional filter inserts (5) are preferably located exclusively in the bulk phase of the electrodeposition bath and can pick up contamination here.
  • the filter materials that can be used for the additional filter inserts (5) are also preferably selected from the group of materials described above for the filter medium (2).
  • the additional filter inserts (5) comprise the filter materials and preferably dimensionally stable housings which are permeable to the electrodeposition paint and which accommodate the filter materials without being permeable to them.
  • housings that are permeable to the electrocoat meshes and / or bags that are permeable to the electrocoat can also be used, which hold the filter materials without being permeable to them.
  • the skid (1) according to the invention which can be used in the method according to the invention, very particularly preferably also comprises one or more measuring devices (6) which are suitable for determining parameters of the electrocoating bath.
  • the measuring devices can preferably serve to analyze the nature of the electrocoating bath and / or check its quality with regard to the effectiveness of the cleaning method according to the invention. For For the latter purpose, these are preferably spatially arranged downstream of the additional filter units (5) - if they are present.
  • Fig. 1 shows the sketch of a continuous electrodeposition system in pendulum mode.
  • the skids (1) in the immersion zone (E) and the immersion zone (A) of the electrodeposition bath include the filter medium (2) in the folded-in state, the optional additional filter units (5) and an optional measuring device (6).
  • the middle skid (1), completely immersed in the electrodeposition bath shows the filter medium (2) in the unfolded state, and the optional additional filter units (5) and an optional measuring device (6) in the completely immersed state.
  • the arrow indicates the conveying direction.
  • Fig. 2 shows the sketch of a continuous electrodeposition system in overhead conveying mode.
  • the skids (1) in the immersion zone (E) and the immersion zone (A) of the electrodeposition bath include the filter medium (2) in the folded-in state, the optional additional filter units (5) and an optional measuring device (6).
  • the two middle skids (1) completely immersed in the electrodeposition bath show the filter medium (2) in the unfolded state, and the optional additional filter units (5) and an optional measuring device (6) in the completely immersed state.
  • the arrow indicates the conveying direction.
  • FIG. 3A shows in a side view the sketch of a skid (1) according to the invention equipped with a folded-in filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6).
  • FIG. 3B shows a side view of the sketch of a skid (1) according to the invention equipped with an unfolded filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6).
  • Fig. 4 shows the sketch of a skid (1) according to the invention from above, equipped with a filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6).
  • the method according to the invention has proven to be extremely effective and a cleaning or decontamination of the electrodeposition bath by binding interfering substances to the filter medium (2), which goes far beyond cleaning the bulk phase of the electrodeposition bath, was observed.
  • the metal sheets coated in the electrocoating process had a significantly lower number of surface defects, in particular a lower number of craters, after a contaminated electrocoating bath had been cleaned. In this way, it was also possible to avoid the premature replacement of the electrodeposition paint bath and the inevitably associated longer interruption of the painting process.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Electrochemistry (AREA)
  • Water Supply & Treatment (AREA)
  • Filtering Materials (AREA)
  • Treatment Of Liquids With Adsorbents In General (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

The present invention relates to a method for cleaning an electrophoretic coating bath in a throughflow system, wherein a skid (1) connected to a conveying apparatus is conveyed through the electrophoretic coating bath, characterized in that the skid (1) has a filter medium (2); the filter medium (2) is fastened to the skid (1) by means of at least one movable connecting element (3); the movable connecting element (3) allows the filter medium (2) to be aligned with the interface between the electrophoretic coating bath and air; and, after the skid (1) has been immersed into the electrophoretic coating bath, the filter medium (2) is aligned with the interface between the electrophoretic coating bath and air and pulled along the surface of the electrophoretic coating bath as the skid (1) is conveyed through the electrophoretic coating bath. The invention further relates to a skid for use in the cleaning method.

Description

Verfahren zur Reinigung von Elektrotauchlackbädern und Vorrichtung hierzu Process for cleaning electrocoating baths and device for this
Die vorliegende Erfindung betrifft ein Verfahren zur Reinigung vonThe present invention relates to a method for purifying
Elektrotauchlackbädern, insbesondere ein Verfahren zur Entfernung vonElectrocoating baths, in particular a method for removing
Störsubstanzen aus Elektrotauchlackbädern und eine Vorrichtung hierzu. Interfering substances from electrodeposition baths and a device for this.
Auf dem Gebiet der Elektrotauchlackierung unterscheidet man in Bezug auf die Bauform der Elektrotauchlackanlagen zwischen Durchlauf- oder Taktanlagen. Durchlaufanlagen besitzen den Vorteil, dass höhere Durchsatzleistungen erreicht werden, üblicherweise eine geringere Störanfälligkeit vorliegt und geringere Investitionskosten hiermit verbunden sind. Durchlaufanlagen werden kontinuierlich betrieben und das zu lackierende Gut wird auf Gestellen, sogenannten Skids durch das mit dem Elektrotauchlack befüllte Tauchlackbecken transportiert. In the field of electrocoating, a distinction is made between continuous or cyclic systems with regard to the design of the electrocoating systems. Continuous systems have the advantage that higher throughput rates can be achieved, there is usually less susceptibility to failure and lower investment costs are associated with this. Continuous systems are operated continuously and the items to be painted are transported on racks, so-called skids, through the immersion paint basin filled with the electrodeposition paint.
Vor dem Einbringen des zu lackieren Guts in das Elektrotauchlackbad wird das zu lackierende Gut gründlich gereinigt, um Beschichtungsfehler wie beispielsweise Krater zu vermeiden. Im Allgemeinen sind Krater„kleine, runde Vertiefungen in der Beschichtung, die nach dem Trocknen bestehen bleiben“ (DIN EN ISO 4618-2). Im engeren, hierin verwendeten Sinne, werden unter dem Begriff „Krater“ solche Filmdefekte verstanden, die sich durch eine wulstartige Erhebung am Rand sowie eine tellerartige, oft bis fast an den Untergrund reichende Vertiefung auszeichnen. Derartige Störungen können Durchmesser von bis zu mehreren Millimetern besitzen. Sie sind auch nach erfolgter Decklackierung auf der Substratoberfläche, beispielsweise der Automobilkarosserieoberfläche oft noch erkennbar und bedingen daher aufwändige und kostenintensive Nacharbeit. Before the item to be coated is introduced into the electrocoating bath, the item to be coated is thoroughly cleaned in order to avoid coating defects such as craters. In general, craters are “small, round depressions in the coating that remain after drying” (DIN EN ISO 4618-2). In the narrower sense used here, the term “crater” is understood to mean film defects that are characterized by a bead-like elevation on the edge and a plate-like depression that often extends almost to the ground. Such disturbances can have a diameter of up to several millimeters. Even after the topcoat has been applied, they are often still recognizable on the substrate surface, for example the surface of the automobile body, and therefore require complex and cost-intensive rework.
Die Tendenz zur Kraterbildung nimmt mit dem Gradienten der Oberflächenspannung im Bereich der Störung zu. Für diese Größe dient näherungsweise die Differenz der Oberflächenspannung von Lack und Störsubstanz als Maß. Als Störsubstanzen treten insbesondere Fette oder Öle, Silikon und organische Fluorverbindungen auf. The tendency to crater formation increases with the gradient of the surface tension in the area of the fault. The difference between the surface tension of the paint and the interfering substance serves as a measure for this quantity. Fats or oils, silicone and organic fluorine compounds in particular occur as interfering substances.
Kathodische Elektrotauchlackbindemittel basieren in der Regel auf Epoxidharzen, sodass von einer Oberflächenspannung von etwa 46 mN/m ausgegangen werden kann. Organische Fluorverbindungen und Silikone (insbesondere Polydialkylsiloxane) weisen sehr viel niedrigere Oberflächenspannungen von etwa 20 mN/m auf. Fette und Öle liegen deutlich höher, aber mit etwa 30 mN/m immer noch deutlich unter den Elektrotauchlackbindemitteln. Cathodic electrodeposition paint binders are usually based on epoxy resins, so that a surface tension of around 46 mN / m can be assumed. Organic fluorine compounds and silicones (especially polydialkylsiloxanes) have much lower surface tensions of around 20 mN / m. Fats and oils are significantly higher, but at around 30 mN / m, they are still significantly below the electrodeposition paint binders.
Die Differenz zwischen der Oberflächenspannung des Lackfilms und der Störsubstanz ist eine der Ursache der Kraterempfindlichkeit von Elektrotauchlacken. In der Praxis ist es jedoch kaum realisierbar die Einbringung von Störsubstanzen in das Elektrotauchlackbad völlig auszuschließen. The difference between the surface tension of the paint film and the interfering substance is one of the causes of the crater sensitivity of electrodeposition paints. In practice, however, it is hardly possible to completely exclude the introduction of interfering substances into the electrocoating bath.
So werden beispielsweise fluorhaltige Verbindungen als Schmiermittel in der Fördertechnik verwendet. Silikone können auf verschiedenste Weise eingeschleppt werden. So werden in der Umformtechnik häufig auch Fette oder Öle eingesetzt, die geringe Mengen silikonhaltiger Hilfsstoffe enthalten. Auf Fette oder Öle selbst kann bei der Produktion der Rohbauteile üblicherweise nicht verzichtet werden. For example, fluorine-containing compounds are used as lubricants in conveyor technology. Silicones can be introduced in various ways. For example, fats or oils that contain small amounts of silicone-containing auxiliaries are often used in forming technology. Usually, it is not possible to do without fats or oils themselves in the production of the shell components.
Von entscheidender Bedeutung ist daher eine gründliche Entfettung des zu lackieren Guts, bevor dieses in das Elektrotauchlackbad eingeführt wird. In der Praxis hat sich gezeigt, dass die Entfettung geometrisch einfacher Bauteile relativ unproblematisch ist, wohingegen die vollständige Entfettung von komplizierten Bauteilen wie beispielsweise Automobil-Rohbaukarossen sehr schwierig erscheint. Hierbei kommt es vielfach zu Verschleppungen der Störsubstanzen in das Elektrotauchlackbad. Diese Probleme verursachenden Substanzen können sowohl in der Lackphase dispergiert sein als auch auf der Lackoberfläche eines Elektrotauchlackbades schwimmen. Es müssen also Vorkehrungen getroffen werden, diese Störsubstanzen zu entfernen. It is therefore of crucial importance to thoroughly degrease the item to be painted before it is introduced into the electrocoating bath. In practice it has been shown that the degreasing of geometrically simple components is relatively unproblematic, whereas the complete degreasing of complex components such as automobile body shells appears to be very difficult. In this case, the interfering substances are often carried over into the electrocoating bath. Substances that cause these problems can both be dispersed in the paint phase and also float on the paint surface of an electrocoating bath. Precautions must therefore be taken to remove these interfering substances.
Die WO 87/03016 beschreibt ein Verfahren zur Entfernung von Oberflächen störungen verursachenden Verunreinigungen aus Elektrotauchlackbädern, wobei der Elektrotauchlack zusätzlich zu den bereits üblichen Reinigungsoperationen drucklos über ein Adsorptionsmaterial filtriert wird, dass hydrophobe Substanzen, deren Oberflächenspannung < 35 mN/m beträgt, adsorbiert. Bei den hydrophoben Substanzen handelt es sich vorzugsweise um Homo- oder Copolymere aus Ethylen, Propylen, Buten-1 oder Buten-2, die gegebenenfalls noch weitere unpolare Copolymere enthalten. Besonders bevorzugt wird faseriges Polypropylen in Form eines Flockenmaterials als Adsorptionsmittel eingesetzt. In einer besonders vorteilhaften Ausgestaltung der Erfindung der WO 87/03016 werden mit Absorbens gefüllte Filterbeutel so in den Lackkreislauf der Elektrotauchlackieranlage eingebaut, dass die Zusatzfiltration je nach Bedarf problemlos zu- bzw. abgeschaltet werden kann. WO 87/03016 describes a method for removing impurities that cause surface disturbances from electrodeposition baths, the electrodeposition paint being filtered through an adsorption material without pressure in addition to the cleaning operations that are already common, so that hydrophobic substances with a surface tension of <35 mN / m are adsorbed. The hydrophobic substances are preferably homopolymers or copolymers of ethylene, propylene, butene-1 or butene-2, which optionally contain further non-polar copolymers. Fibrous polypropylene in the form is particularly preferred a flake material is used as an adsorbent. In a particularly advantageous embodiment of the invention of WO 87/03016, filter bags filled with absorbent are installed in the paint circuit of the electrocoating system in such a way that the additional filtration can be easily switched on or off as required.
In der WO 90/05012 wird für den gleichen Zweck ein Filter mit einer in einem Filtergehäuse angeordneten Filterpatrone vorgeschlagen, wobei die Filterpatrone eine Faserpackung als Adsorptionsvliesbahn umfasst. In WO 90/05012, a filter with a filter cartridge arranged in a filter housing is proposed for the same purpose, the filter cartridge comprising a fiber packing as an adsorption fleece web.
In beiden Fällen werden die Filtriervorrichtungen im Lackkreislaufsystem untergebracht und von der Bulkphase des Lacks durchströmt. Durch die träge Absorptionskinetik ist ein Einbau dieser speziellen Filter in die Filtergehäuse nur wenig effektiv, da hier die Strömungsgeschwindigkeit des Lacks sehr hoch ist und damit die Kontaktzeit von Störsubstanz und Faservlies nur sehr kurz ist. Effektivitätsvermindernd kommt hinzu, dass durch die geringe Dichte und erhöhte Hydrophobizität der Störsubstanzen im Vergleich zum wässrigen Tauchlackbad eine Anreicherung der Störsubstanzen an der Grenzfläche zwischen Tauchlackbad und Luft stattfindet. Da die Pumpen für die Badumwälzung und Kreislaufführung den Lack am Beckenboden ansaugen, enthält der Lackvolumenstrom nur unzureichende Mengen der Störsubstanzen, weshalb der Wirkungsgrad derartiger Filterverfahren ebenfalls unzureichend ist. In both cases, the filter devices are accommodated in the paint cycle system and the bulk phase of the paint flows through them. Due to the sluggish absorption kinetics, installing these special filters in the filter housing is not very effective, as the flow velocity of the paint is very high here and the contact time between the interfering substance and the fiber fleece is very short. In addition, reducing the effectiveness is that due to the low density and increased hydrophobicity of the interfering substances compared to the aqueous immersion bath, an accumulation of the interfering substances takes place at the interface between the immersion bath and air. Since the pumps for circulating the bath and for circulating the system suck in the paint at the bottom of the pool, the paint volume flow contains only inadequate quantities of the interfering substances, which is why the efficiency of such filter processes is also inadequate.
In der Praxis wird daher ein Faservlies aus Polypropylen mit entsprechenden Halterungen auf die Elektrotauchlackbadoberfläche gelegt. Dies erfolgt in der Regel vor der Überlauftasche des Tauchlackbeckens, damit die durch die Anlage beförderten Karossen nicht mit der Filterbarriere kollidieren. Der Vorteil dieses Vorgehens besteht darin, dass die Kontaktzeit zwischen Störsubstanzen und Filtervlies maximal ist und man das Filter für die Reinigung dahin bringt, wo sich die Störsubstanzen in der Regel aufhalten. In practice, a fiber fleece made of polypropylene is therefore placed on the surface of the electrocoating bath with appropriate holders. This is usually done in front of the overflow pocket of the dip paint tank so that the bodies conveyed through the system do not collide with the filter barrier. The advantage of this procedure is that the contact time between interfering substances and the filter fleece is maximum and that the filter is brought to where the interfering substances are usually located for cleaning.
Zusätzlich ist es möglich die Oberfläche des Elektrotauchlackbades mit dem Filtervlies abzuskimmen. Hierzu wird die schwimmende Filterbarriere von beispielsweise zwei Personen, die sich an gegenüberliegenden Tauchlackbecken- rändern befinden mehrfach über die Badoberfläche gezogen. Der Nachteil dieser Verfahrensweise besteht darin, dass die Produktion unterbrochen werden muss, da das Personal direkt am Tauchbeckenrand arbeiten muss und bereits aus Sicherheitsgründen der Tauchlackierprozess unterbrochen werden muss. Zudem erschwert die Fördertechnik - Pendelförderung oder Überkopfförderung oder kombinierte Verfahren - das Abskimmen der Oberfläche. Des Weiteren ist der Arbeitsbereich meist unzugänglich eng und lackkontaminiert. Auch für einen Austausch des Filters muss der Tauchlackierprozess wieder unterbrochen werden. It is also possible to skim the surface of the electrocoat bath with the filter fleece. For this purpose, the floating filter barrier is activated by two people, for example, who sit on opposite immersion paint basins. edges are drawn several times over the bath surface. The disadvantage of this procedure is that production has to be interrupted, since the personnel have to work directly at the edge of the dip pool and the dip painting process has to be interrupted for safety reasons. In addition, the conveyor technology - shuttle conveying or overhead conveying or combined processes - makes it difficult to skim the surface. Furthermore, the work area is mostly inaccessible and contaminated with paint. The dip painting process must also be interrupted again to replace the filter.
Die mit dem Einsatz von Durchlaufanlagen in der Elektrotauchlackierung verbundenen Vorteile höherer Durchsatzleistungen werden somit aufgrund des Reinigungsbedarfs bei konventioneller Verfahrensweise stark eingeschränkt. The advantages of higher throughput rates associated with the use of continuous systems in electrodeposition painting are therefore severely limited due to the cleaning requirements in the conventional process.
Es besteht daher Bedarf an einem sicheren Verfahren zur Reinigung von Elektro- tauchlackbädern, insbesondere zur Entfernung von Störsubstanzen aus Elektro- tauchlackbädern, welches die vorgenannten Nachteile nicht aufweist. There is therefore a need for a safe method for cleaning electro-dip lacquer baths, in particular for removing interfering substances from electro-dip lacquer baths, which does not have the aforementioned disadvantages.
Insbesondere sollte es das Verfahren ermöglichen die Entfernung von Störsubstanzen, insbesondere solchen, die sich auf der Oberfläche des Elektrotauchlackbades anreichern, ohne einen Stopp der Lackieranlage und somit im laufenden Betrieb in effektiver Weise vorzunehmen. In particular, the method should enable the removal of interfering substances, in particular those that accumulate on the surface of the electrodeposition paint bath, without stopping the paint shop and thus effectively during operation.
Dieser Bedarf konnte gedeckt werden durch Bereitstellen eines Verfahrens zur Reinigung eines Elektrotauchlackbades in einer Durchlaufanlage, insbesondere zur Entfernung von Störsubstanzen aus einem Elektrotauchlackbad in einer Durchlauf anlagen, indem ein mit einer Fördereinrichtung verbundenes Skid (1 ) durch das Elektrotauchlackbad befördert wird, wobei This need could be met by providing a method for cleaning an electrocoating bath in a continuous system, in particular for removing interfering substances from an electrocoating bath in a continuous system by conveying a skid (1) connected to a conveyor device through the electrocoating bath, whereby
(a) das Skid (1 ) ein Filtermedium (2) aufweist, (a) the skid (1) has a filter medium (2),
(b) das Filtermedium (2) am Skid (1 ) über mindestens ein bewegliches Verbindungselement (3) befestigt ist, (b) the filter medium (2) is attached to the skid (1) via at least one movable connecting element (3),
(c) das bewegliche Verbindungselement (3) die Ausrichtung des Filtermediums (2) an der Grenzfläche zwischen Elektrotauchlackbad und Luft erlaubt, und (d) das Filtermedium (2) nach Eintauchen des Skids (1 ) in das Elektrotauchlackbad während der Förderung des Skids (1 ) durch das Elektrotauchlackbad an der Grenzfläche zwischen Elektrotauchlackbad und Luft ausgerichtet ist und entlang der Oberfläche des Elektrotauchlackbades gezogen wird. (c) the movable connecting element (3) allows the filter medium (2) to be aligned at the interface between the electrodeposition bath and air, and (d) the filter medium (2) after immersion of the skid (1) in the electrodeposition bath during the conveyance of the skid (1) through the electrodeposition bath is aligned at the interface between the electrodeposition bath and air and is drawn along the surface of the electrodeposition bath.
Dieses Verfahren wird im Folgenden als erfindungsgemäßes Verfahren bezeichnet. This method is referred to below as the method according to the invention.
Schritt (d) dient hierin der Kontaktierung des Filtermediums mit an der Oberfläche des Elektrotauchlackbades vorhandenen Störsubstanzen, wobei diese dabei aufgenommen werden. Step (d) is used here to contact the filter medium with interfering substances present on the surface of the electrodeposition paint bath, these being absorbed in the process.
Der Begriff „Elektrotauchlackbad“ steht für den in einem Elektrotauchlackbecken befindlichen Elektrotauchlack, das heißt einen wässrigen Beschichtungsstoff, der zum Elektrotauchlackieren geeignet ist (DIN 55655-1 :2014-11 ). The term “electrocoat bath” stands for the electrocoat located in an electrocoat basin, i.e. an aqueous coating material that is suitable for electrocoating (DIN 55655-1: 2014-11).
Als„Störsubstanzen“ werden hierin insbesondere solche Substanzen verstanden, die sich an der Oberfläche des Elektrotauchlackbades anreichern und/oder eine Oberflächenspannung kleiner als 35 mN/m besitzen, wobei vorzugsweise beide Bedingungen zutreffen. Die Oberflächenspannung einer Substanz kann gemäß DIN EN 14370:2004-11 nach der Du-Noüy-Ringmethode oder der Wilhelmy- Pattenmethode bestimmt werden. Aufgrund der Bewegung des Ringes während des Messvorgangs ist die Ringmethode nur eine quasi-statische Methode. Bei Flüssigkeiten, die den Gleichgewichtswert der Oberflächenspannung nur langsam ausbilden, wird die statische Plattenmethode nach Wilhelmy bevorzugt angewendet. Dies bedeutet jedoch nicht, dass die Störsubstanzen ausschließlich an der Oberfläche des Elektrotauchlackbades befindlich sind. Ein Teil der Störsubstanzen kann insbesondere beim Eintauchen der Skids (1 ) aus der Oberfläche des Elektrotauchlackbades in die Bulkphase des Elektrotauchlackbades gelangen oder sich erst vom zu lackierenden Gut in der Bulkphase des Elektrotauchlackbades lösen. Störsubstanzen sind wie oben bereits beschrieben eine häufige Ursache von Filmfehlern. Unter „Filmfehlern“ (auch als Filmschäden oder Filmstörungen bezeichnet) werden nach DIN 55945:2007-03 Beschichtungsfehler verstanden, die durch Störungen in der Beschichtung gekennzeichnet sind und die meist nach ihrer Form oder ihrem Aussehen benannt werden. Störsubstanzen wie sie häufig in Elektrotauchlackbädern enthalten sind, führen wiederum häufig zu kraterförmigen Filmfehlern, sogenannten Kratern wie sie oben definiert sind. In this context, “interfering substances” are understood to mean in particular those substances which accumulate on the surface of the electrodeposition paint bath and / or have a surface tension of less than 35 mN / m, both conditions preferably being met. The surface tension of a substance can be determined according to DIN EN 14370: 2004-11 using the Du Noüy ring method or the Wilhelmy patten method. Due to the movement of the ring during the measurement process, the ring method is only a quasi-static method. In the case of liquids that develop the equilibrium value of surface tension only slowly, the static plate method according to Wilhelmy is preferred. However, this does not mean that the interfering substances are only located on the surface of the electrodeposition paint bath. Some of the interfering substances can get from the surface of the electrodeposition paint bath into the bulk phase of the electrodeposition paint bath, in particular when the skids (1) are immersed, or only detach from the item to be painted in the bulk phase of the electrodeposition paint bath. As already described above, interfering substances are a frequent cause of film defects. According to DIN 55945: 2007-03, “film defects” (also referred to as film damage or film defects) are defined as coating defects which are characterized by defects in the coating and which are usually based on their Shape or its appearance. Interfering substances as they are often contained in electrocoating baths, in turn, often lead to crater-shaped film defects, so-called craters as defined above.
Unter einer „Durchlaufanlage“ wird eine Elektrotauchlackanlage verstanden, bei welcher im Gegensatz zu einer chargenweisen Bestückung wie sie in Taktanlagen erfolgt, ein kontinuierlicher Durchlauf der zu lackierenden Güter erfolgt. A “continuous system” is understood to mean an electrocoating system in which, in contrast to batch-wise loading, as is done in cycle systems, the goods to be coated are continuously passed through.
Der Begriff „Skid“ (1 ), wie er hierin verwendet wird, steht für ein Gestell, welches üblicherweise der Aufnahme des zu lackierenden Gutes dient, im Rahmen der vorliegenden Erfindung jedoch vorzugsweise anstelle des zu lackierenden Gutes, oder weniger bevorzugt zusätzlich zu diesem, mit dem Filtermedium (2) verbunden ist. Am Skid (1 ) kann ein weiteres Gestell befestigt sein, was hierin - sofern vorhanden - als zum Skid (1 ) gehörig betrachtet wird. Ist am Skid (1 ) ein weiteres Gestell befestigt, so können sich folglich Verbindungselement (3) und Filtermedium (2) auch an diesem befinden. Vorzugsweise ist am Skid kein weiteres Gestell befestigt. The term “skid” (1), as used herein, stands for a frame which usually serves to hold the item to be painted, but within the scope of the present invention preferably instead of the item to be painted, or less preferably in addition to it, is connected to the filter medium (2). A further frame can be attached to the skid (1), which - if present - is regarded as belonging to the skid (1). If another frame is attached to the skid (1), the connecting element (3) and filter medium (2) can also be located on this. Preferably, no further frame is attached to the skid.
Der Begriff„Filtermedium“ (2) wie er hierin verwendet wird ist ein gängiger Begriff aus der Filtrationstechnik und stellt das zur Filterung benutzte Material dar. The term "filter medium" (2) as it is used here is a common term from filtration technology and represents the material used for filtering.
Unter dem Begriff „zu lackierendes Gut“ werden alle zur Beschichtung im Elektrotauchlackbad vorgesehenen Teile verstanden. Die zu lackierenden Güter sind elektrisch leitfähig, vorzugsweise metallisch. Es kann sich hierbei um einfach geformte Teile wie beispielsweise Bleche handeln, aber auch um komplexe dreidimensional ausgestaltete Teile wie beispielsweise Kfz-Karossen. The term “item to be painted” is understood to mean all parts intended for coating in the electrodeposition bath. The goods to be painted are electrically conductive, preferably metallic. These can be simply shaped parts such as sheet metal, but also complex three-dimensional parts such as motor vehicle bodies.
Die„Oberfläche des Elektrotauchlackbades“ ist der mit der Umgebungsluft in Kontakt stehende Bereich des Elektrotauchlacks. The “surface of the electrocoat bath” is the area of the electrocoat that is in contact with the ambient air.
Unter dem „Ziehen des Filtermediums (2) entlang der Oberfläche des Elektrotauchlackbades“ wird verstanden, dass das Filtermedium (2) hierbei sowohl in die Umgebungsluft als auch das Elektrotauchlackbadvolumen ragt und mit der Förderung des Skids (1 ) durch das Elektrotauchlackbad entlang der Oberfläche des Elektrotauchlackbades gezogen wird und auf diese Weise in Kontakt mit den an der Oberfläche des Elektrotauchlackbades befindlichen Störsubstanzen tritt. “Pulling the filter medium (2) along the surface of the electrodeposition bath” is understood to mean that the filter medium (2) protrudes into both the ambient air and the electrodeposition bath volume and with the conveyance of the skid (1) through the electrodeposition bath along the surface of the Electrocoat bath is drawn and in this way comes into contact with the interfering substances located on the surface of the electrocoat bath.
Unter einem „Verbindungselement“ (3) wird ein Bauteil verstanden, welches das Filtermedium (2) mit dem Skid (3) verbindet. Das Verbindungselement (3) ist beweglich. Hierunter wird verstanden, dass das Verbindungselement (3) im Abstand zwischen Skid (1 ) und Filtermedium (2) variabel ist, so dass das Filtermedium (2) bei der Förderung durch das Elektrotauchlackbad auch bei unterschiedlichen Eintauchtiefen des Skids (1 ) in das Elektrotauchlackbad entlang der Oberfläche des Elektrotauchlackbades in Förderrichtung gezogen werden kann. Die Länge des Verbindungselements (3) muss dementsprechend so bemessen sein, dass bei einer maximalen Eintauchtiefe des Skids (1 ) in das Elektrotauchlackbad, das mit dem Verbindungselement (3) verbundene Filtermedium (2) entlang der Oberfläche des Elektrotauchlackbades gezogen werden kann. Vorzugsweise weist das Verbindungselement (3) einen Klappmechanismus auf. A “connecting element” (3) is understood to mean a component that connects the filter medium (2) to the skid (3). The connecting element (3) is movable. This means that the connecting element (3) is variable in the distance between the skid (1) and the filter medium (2), so that the filter medium (2) is conveyed through the electrodeposition bath even when the skid (1) is immersed in the electrodeposition bath at different depths can be drawn along the surface of the electrodeposition bath in the conveying direction. The length of the connecting element (3) must accordingly be dimensioned in such a way that the filter medium (2) connected to the connecting element (3) can be drawn along the surface of the electrodeposition bath when the skid (1) is immersed to a maximum depth in the electrodeposition bath. The connecting element (3) preferably has a folding mechanism.
Neben den oben genannten Vorteilen des Verfahrens zeichnet sich das erfindungsgemäße Verfahren dadurch aus, dass die ohnehin vorhandenen Skids (1 ) - wie sie für die Lackierung des Lackierguts verwendet werden - nunmehr auch als Transportgestell für das Filtermedium (2) eingesetzt werden können und somit komplexe Anpassungen der Elektrotauchlack-Durchlaufanlage zur Durchführung des erfindungsgemäßen Verfahrens nicht notwendig sind. Es können vielmehr erfindungsgemäß ausgestattete Skids (1 ) im Stand-by vorgehalten werden, um bei Bedarf sofort einsetzbar zu sein und ein mit Lackiergut ausgestattetes Skid (1 ) im laufenden Betrieb zu ersetzen. In addition to the above-mentioned advantages of the method, the method according to the invention is characterized in that the skids (1) that are already present - as they are used for painting the items to be painted - can now also be used as a transport frame for the filter medium (2) and are therefore complex Adjustments to the continuous electrodeposition system for carrying out the process according to the invention are not necessary. Rather, skids (1) equipped according to the invention can be kept in stand-by so that they can be used immediately if necessary and to replace a skid (1) equipped with paint items during operation.
Bei der Durchführung des erfindungsgemäßen Verfahrens durchläuft das Skid (1 ) das Elektrotauchlackbecken in gewohnter Weise, so wie dies bei einer Bestückung des Skids (1 ) mit dem zu lackierenden Gut der Fall ist. When the method according to the invention is carried out, the skid (1) passes through the electrodeposition paint basin in the usual manner, as is the case when the skid (1) is loaded with the item to be painted.
Das Filtermedium (2) ist am Skid (1 ) so angeordnet, dass es das Verbindungselement (3) oder die Verbindungselemente (3) des Filtermediums (2) mit dem Skid (1 ) oder dem auf dem Skid separat angebrachten Gestell ermöglichen, dass sich das Filtermedium (2) an der Grenzfläche zwischen Elektrotauchlackbad und Luft ausrichtet. The filter medium (2) is arranged on the skid (1) in such a way that the connecting element (3) or the connecting elements (3) of the filter medium (2) with the skid (1) or the frame separately attached to the skid enable that the filter medium (2) aligns itself at the interface between the electrocoating bath and air.
Vorzugsweise ist das Filtermedium (2) daher mit der Seite des Skids (1 ) über das oder die Verbindungselemente (3) verbunden, die bei der Durchführung des erfindungsgemäßen Verfahrens in Richtung besagter Grenzfläche weist. So ermöglicht dies einen Betrieb der Elektrotauchlack-Durchlaufanlage sowohl in Pendelförderweise als auch in Überkopffahrweise oder beliebiger anderer Fahrweise. The filter medium (2) is therefore preferably connected to the side of the skid (1) via the connecting element (s) (3) which, when carrying out the method according to the invention, points in the direction of said interface. This enables the continuous electrodeposition coating system to be operated both in pendulum mode and in overhead mode or any other mode of operation.
Die Verbindung zwischen Skid (1 ) einerseits und Filtermedium (2) andererseits erfolgt vorzugsweise über eines oder mehrere klappbare Verbindungselemente (3) die sich beim Betrieb der Vorrichtung öffnen. Das Öffnen des oder der vorzugsweise klappbaren Verbindungselemente (3) zwischen Skid (1 ) einerseits und Filtermedium (2) andererseits kann vorzugsweise durch einen oder mehrere vorzugsweise am Filtermedium (2) und/oder Verbindungselement (3) befestigte Auftriebskörper (4) (beziehungsweise Schwimmkörper (4)) erfolgen. Vorzugsweise sind der oder die Auftriebskörper (4) so angeordnet, dass diese bei der Förderung des Skids (1 ) hinter dem Filtermedium (2) liegen und somit das Filtermedium (2) unbehindert angeströmt werden kann. Beim Eintauchen des Skids (1 ) in das Elektrotauchlackbad halten die Schwimmkörper (4) das Filtermedium (2) an der Oberfläche des Elektrotauchlackbads und richten das Filtermedium (2) aus. Mit zunehmender Eintauchtiefe klappen das oder die klappbaren Verbindungselemente (3) zwischen Skid (1 ) einerseits und Filtermedium (2) andererseits aus, während beim Auftauchen des Skids (1 ) am Ende des Elektrotauchlackbeckens der Klappmechanismus wieder schließt. The connection between the skid (1) on the one hand and the filter medium (2) on the other hand is preferably made via one or more hinged connecting elements (3) which open when the device is in operation. The opening of the preferably foldable connecting element (s) (3) between the skid (1) on the one hand and the filter medium (2) on the other hand can preferably be done by one or more buoyancy bodies (4) (or floats) preferably attached to the filter medium (2) and / or connecting element (3) (4)). The buoyancy body (s) (4) are preferably arranged in such a way that they lie behind the filter medium (2) when the skid (1) is being conveyed, and the flow can thus flow against the filter medium (2) without hindrance. When the skid (1) is immersed in the electrocoating bath, the floating bodies (4) hold the filter medium (2) on the surface of the electrocoating bath and align the filter medium (2). As the immersion depth increases, the hinged connecting element (s) (3) between the skid (1) on the one hand and the filter medium (2) on the other fold out, while the hinged mechanism closes again when the skid (1) emerges at the end of the electrocoating tank.
Um möglichst die gesamte Badbreite erfindungsgemäß abziehen, das heißt skimmen zu können, ist es vorteilhaft, wenn das Filtermedium (2) und vorzugsweise auch der Auftriebskörper (4) so mit dem Skid verbunden sind, dass das Filtermedium (2) die gesamte Breite oder nahezu die gesamte Breite wie beispielsweise mindestens 80 %, vorzugsweise mindestens 90 % und besonders bevorzugt mindestens 95 % der Breite des Tauchlackbeckens einnehmen. Vorzugsweise ragt das Filtermedium (2) seitlich über das Skid (1 ) hinaus. Selbstverständlich ist es auch möglich, dass anstelle eines oder mehrerer Auftriebskörper (4) das Verbindungselement (3) zwischen Filtermedium (2) und Skid (1 ) oder einem auf dem Skid (1 ) separat angebrachten Gestell durch einen Antrieb das Filtermedium (2) an die Oberfläche des Elektrotauchlackbades befördert. In order to be able to subtract the entire width of the bath as possible according to the invention, i.e. to be able to skim, it is advantageous if the filter medium (2) and preferably also the float (4) are connected to the skid in such a way that the filter medium (2) covers the entire width or almost occupy the entire width, for example at least 80%, preferably at least 90% and particularly preferably at least 95% of the width of the dip lacquer basin. The filter medium (2) preferably protrudes laterally beyond the skid (1). Of course, it is also possible that instead of one or more buoyancy bodies (4), the connecting element (3) between the filter medium (2) and the skid (1) or a frame attached separately to the skid (1) can drive the filter medium (2) the surface of the electrocoating bath promotes.
Schließlich ist es ebenfalls möglich, dass das Filtermedium (2) selbst aufgrund seiner Dichte oder eingeschlossener Flohlräume bereits als Auftriebskörper (4) fungiert und somit die kombinierte Funktion eines Filtermediums (2) und Auftriebskörpers (4) übernimmt. Finally, it is also possible that the filter medium (2) itself already functions as a float (4) due to its density or enclosed flea spaces and thus takes on the combined function of a filter medium (2) and float (4).
Das Filtermedium (2) ist makroskopisch betrachtet vorzugsweise länglich ausgestaltet und bei der Durchführung des Verfahrens im Wesentlichen senkrecht zur Förderrichtung des Skids (1 ) an der Oberfläche des Elektrotauchlackbades angeordnet. Prinzipiell sind jedoch auch andere Geometrien des Filtermediums (2) möglich. Das Filtermedium (2) kann beispielsweise auch V-förmig, U-förmig oder Zickzack-förmig gestaltet sein, um beispielsweise die verfügbare adsorbierende Oberfläche des Filtermediums (2) zu vergrößern. From a macroscopic point of view, the filter medium (2) is preferably elongated and, when the method is carried out, is arranged essentially perpendicular to the conveying direction of the skid (1) on the surface of the electrocoating bath. In principle, however, other geometries of the filter medium (2) are also possible. The filter medium (2) can also be designed, for example, V-shaped, U-shaped or zigzag-shaped, for example in order to enlarge the available adsorbing surface of the filter medium (2).
Das Filtermedium (2) ermöglicht die Reinigung des Elektrotauchlackbades, insbesondere die Aufnahme der an der Oberfläche des Elektrotauchlackbades befindlichen Störsubstanzen. Daher besteht das Filtermedium (2) aus einem Material, welches eine Affinität zu den typischen Störsubstanzen aufweist. Die Adsorption kann prinzipiell chemisch (Chemisorption) oder physikalisch (Physisorption) erfolgen. Vorzugsweise erfolgt diese physikalisch. The filter medium (2) enables the electrodeposition bath to be cleaned, in particular the absorption of the interfering substances on the surface of the electrodeposition bath. The filter medium (2) therefore consists of a material that has an affinity for the typical interfering substances. In principle, adsorption can take place chemically (chemisorption) or physically (physisorption). This is preferably done physically.
Eine besonders gute Affinität zu den typischerweise in Elektrotauchlackbädern vorhandenen Störsubstanzen besitzen wasserabweisende Polymere, auch als hydrophobe Polymere bezeichnet. Flierunter fallen vorzugsweise Polyalkylene, wie insbesondere Polyethylene, Polypropylene, Polybutylene sowie die Copolymere aus mindestens zwei Monomeren gewählt aus der Gruppe bestehend aus Ethylen, Propylen, 1-Butylen und 2-Butylen. Darüber hinaus können die vorgenannten Polymere weitere unpolare Co-Monomere enthalten. Da die verschiedenen Polymere und Copolymere unterschiedliche Polaritäten besitzen, können diese in einer bevorzugten Ausgestaltung auch miteinander kombiniert werden, um eine Affinität gegenüber einem möglichst breiten Spektrum an Störsubstanzen abzudecken. Water-repellent polymers, also known as hydrophobic polymers, have a particularly good affinity for the interfering substances that are typically present in electrocoating baths. These include preferably polyalkylenes, such as in particular polyethylenes, polypropylenes, polybutylenes and the copolymers of at least two monomers selected from the group consisting of ethylene, propylene, 1-butylene and 2-butylene. In addition, the aforementioned polymers can contain other non-polar co-monomers. Since the various polymers and copolymers have different polarities, they can also be combined with one another in a preferred embodiment in order to cover an affinity for the broadest possible spectrum of interfering substances.
Besonders geeignet ist die Ausgestaltung des Filtermediums (2) in Form eines textilen Flächenerzeugnisses, vorzugsweise gewählt aus der Gruppe der Gewebe, Gewirke, Gestricke, Filze oder Vliesstoffe. Ganz besonders geeignet ist die Ausgestaltung des Filtermediums (2) in Form eines Vliesstoffes. Die textilen Flächenerzeugnisse, insbesondere die Vliesstoffe werden hierbei vorzugsweise gerollt und die Rollen vorzugsweise in Form der oben genannten Geometrien eingesetzt. The configuration of the filter medium (2) in the form of a textile flat product, preferably selected from the group of woven, knitted, knitted fabrics, felts or nonwovens is particularly suitable. The design of the filter medium (2) in the form of a non-woven fabric is particularly suitable. The flat textile products, in particular the nonwovens, are preferably rolled here and the rolls are preferably used in the form of the geometries mentioned above.
Es ist jedoch auch möglich die oben beschriebenen wasserabweisenden Polymere beispielsweise in Form eines faserigen Flockenmaterials in vorzugsweise röhrenförmige Netze oder für den Elektrotauchlack durchlässige röhrenförmige Beutel zu füllen und diese in gleicher Weise wie die vorgenannten Rollen als Filtermedium (2) einzusetzen. However, it is also possible to fill the above-described water-repellent polymers, for example in the form of a fibrous flake material, in preferably tubular nets or tubular bags permeable to the electrodeposition paint, and to use them as filter medium (2) in the same way as the aforementioned roles.
Weiterer Gegenstand der Erfindung ist ein Skid (1 ) für Elektrotauchlack-Durchlauf- anlagen, wobei das Skid (1 ) ein Filtermedium (2) aufweist, welches mit dem Skid (1 ) über ein oder mehrere Verbindungselemente (3) so verbunden ist, dass sich das Filtermedium beim Betrieb der Elektrotauchlack-Durchlaufanlage an der Grenzfläche zwischen Elektrotauchlackbad und Luft ausrichten kann. Um dies zu gewährleisten sind die Verbindungselemente (3) beweglich, wie bereits oben zum erfindungsgemäßen Verfahren beschrieben, in welchem das Skid einsetzbar ist. The invention also relates to a skid (1) for continuous electrodeposition paint systems, the skid (1) having a filter medium (2) which is connected to the skid (1) via one or more connecting elements (3) in such a way that the filter medium can align itself at the interface between the electrocoat bath and air when the continuous electrodeposition system is in operation. To ensure this, the connecting elements (3) are movable, as already described above for the method according to the invention, in which the skid can be used.
Dieses so ausgerüstete Skid (1 ) wird im Folgenden als erfindungsgemäßes Skid (1 ) bezeichnet. This skid (1) equipped in this way is referred to below as the skid (1) according to the invention.
In einer besonders bevorzugten Ausführungsform des erfindungsgemäßen Skids (1 ), das im erfindungsgemäßen Verfahren einsetzbar ist, sind am Skid (1 ) eines oder mehrere zusätzliche Filtereinsätze (5) angebracht. Diese Filtereinsätze (5) besitzen vorzugsweise eine längliche Ausgestaltung und sind im Gegensatz zum oben beschriebenen Filtermedium (2) vorzugsweise parallel zur Förderrichtung des Skids (1 ) angeordnet. Diese zusätzlichen Filtereinsätze (5) befinden sich während des Reinigungsvorgangs - ebenfalls im Gegensatz zu den oben beschriebenen Filtermedien (2) - hauptsächlich in die Bulk-Phase des Elektrotauchlackbades. Lediglich während des Ein- und Auftauchens befinden sich Teile des oder der zusätzlichen Filtereinsätze (5) nicht vollständig in der Bulk-Phase des Elektrotauchlackbades. Das Eintauchen in das Elektrotauchlackbad erfolgt typischerweise mit der Öffnung des Filtereinsatzes (5) voran, wobei in der Eintauchzone des Elektrotauchlackbeckens bereits Oberflächenverunreinigungen beim Durchlaufen der Oberfläche des Elektrotauchlackbades aufgenommen werden können. Gleiches geschieht beim Auftauchen in der Auftauchzone des Elektrotauchlackbeckens. Nach dem vollständigen Eintauchen und vor dem Auftauchen befinden sich die zusätzlichen Filtereinsätze (5) vorzugsweise ausschließlich in der Bulkphase des Elektrotauchlackbades und können hier Kontaminationen aufnehmen. In a particularly preferred embodiment of the skid (1) according to the invention, which can be used in the method according to the invention, one or more additional filter inserts (5) are attached to the skid (1). These filter inserts (5) preferably have an elongated design and are in contrast to the above described filter medium (2) preferably arranged parallel to the conveying direction of the skid (1). These additional filter inserts (5) are located during the cleaning process - also in contrast to the filter media (2) described above - mainly in the bulk phase of the electrocoating bath. Only during immersion and emergence are parts of the additional filter insert (s) (5) not completely in the bulk phase of the electrocoating bath. Immersion into the electrodeposition bath typically takes place with the opening of the filter insert (5) first, whereby surface contamination can already be absorbed in the immersion zone of the electrodeposition bath as it passes through the surface of the electrodeposition bath. The same thing happens when surfacing in the surface area of the electrocoating tank. After complete immersion and before surfacing, the additional filter inserts (5) are preferably located exclusively in the bulk phase of the electrodeposition bath and can pick up contamination here.
Die für die zusätzlichen Filtereinsätze (5) einsetzbaren Filtermaterialen werden ebenfalls vorzugsweise aus der der Gruppe der oben für das Filtermedium (2) beschriebenen Materialien gewählt. The filter materials that can be used for the additional filter inserts (5) are also preferably selected from the group of materials described above for the filter medium (2).
Die zusätzlichen Filtereinsätze (5) umfassen die Filtermaterialien und vorzugsweise formstabile, für den Elektrotauchlack durchlässige Gehäuse, welche die Filtermaterialien aufnehmen ohne für diese durchlässig zu sein. Alternativ oder zusätzlich zu den für den Elektrotauchlack durchlässigen Gehäusen lassen sich auch für den Elektrotauchlack durchlässige Netze und/oder Beutel verwenden, welche die Filtermaterialien aufnehmen ohne für diese durchlässig zu sein. The additional filter inserts (5) comprise the filter materials and preferably dimensionally stable housings which are permeable to the electrodeposition paint and which accommodate the filter materials without being permeable to them. Alternatively or in addition to the housings that are permeable to the electrocoat, meshes and / or bags that are permeable to the electrocoat can also be used, which hold the filter materials without being permeable to them.
Ganz besonders bevorzugt umfasst das erfindungsgemäße Skid (1 ), welches im erfindungsgemäßen Verfahren einsetzbar ist, noch eine oder mehrere Messvorrichtungen (6), die geeignet sind Parameter des Elektrotauchlackbads zu bestimmen. Die Messvorrichtungen können vorzugsweise zur Analyse der Beschaffenheit des Elektrotauchlackbades dienen und/oder dessen Güte in Bezug auf die Effektivität des erfindungsgemäßen Reinigungsverfahrens überprüfen. Für letzteren Zweck sind diese den zusätzlichen Filtereinheiten (5) - sofern diese vorhanden sind - vorzugsweise räumlich nachgeordnet. The skid (1) according to the invention, which can be used in the method according to the invention, very particularly preferably also comprises one or more measuring devices (6) which are suitable for determining parameters of the electrocoating bath. The measuring devices can preferably serve to analyze the nature of the electrocoating bath and / or check its quality with regard to the effectiveness of the cleaning method according to the invention. For For the latter purpose, these are preferably spatially arranged downstream of the additional filter units (5) - if they are present.
Das erfindungsgemäße Verfahren sowie das erfindungsgemäße Skid (1 ) und dessen Funktionsweise können exemplarisch anhand der beigefügten Figuren 1 bis 4 näher erläutert werden. The method according to the invention and the skid (1) according to the invention and its mode of operation can be explained in more detail by way of example with reference to the attached FIGS. 1 to 4.
Fig. 1 zeigt die Skizze einer Elektrotauchlack-Durchlaufanlage in Pendelförderweise. Die Skids (1 ) in der Eintauchzone (E) und der Auftauchzone (A) des Elektrotauchlackbads umfassen das Filtermedium (2) im eingeklappten Zustand, die fakultativen zusätzlichen Filtereinheiten (5) sowie eine fakultative Messvorrichtung (6). Das mittlere, im Elektrotauchlackbad vollständig eingetauchte Skid (1 ) zeigt das Filtermedium (2) im ausgeklappten Zustand, und die fakultativen zusätzlichen Filtereinheiten (5) sowie eine fakultative Messvorrichtung (6) in vollständig eingetauchtem Zustand. Der Pfeil zeigt die Förderrichtung an. Fig. 1 shows the sketch of a continuous electrodeposition system in pendulum mode. The skids (1) in the immersion zone (E) and the immersion zone (A) of the electrodeposition bath include the filter medium (2) in the folded-in state, the optional additional filter units (5) and an optional measuring device (6). The middle skid (1), completely immersed in the electrodeposition bath, shows the filter medium (2) in the unfolded state, and the optional additional filter units (5) and an optional measuring device (6) in the completely immersed state. The arrow indicates the conveying direction.
Fig. 2 zeigt die Skizze einer Elektrotauchlack-Durchlaufanlage in Überkopfförderweise. Die Skids (1 ) in der Eintauchzone (E) und der Auftauchzone (A) des Elektrotauchlackbads umfassen das Filtermedium (2) im eingeklappten Zustand, die fakultativen zusätzlichen Filtereinheiten (5) sowie eine fakultative Messvorrichtung (6). Die beiden mittleren, im Elektrotauchlackbad vollständig eingetauchten Skids (1 ) zeigen das Filtermedium (2) im ausgeklappten Zustand, und die fakultativen zusätzlichen Filtereinheiten (5) sowie eine fakultative Messvor richtung (6) in vollständig eingetauchtem Zustand. Der Pfeil zeigt die Förderrichtung an. Fig. 2 shows the sketch of a continuous electrodeposition system in overhead conveying mode. The skids (1) in the immersion zone (E) and the immersion zone (A) of the electrodeposition bath include the filter medium (2) in the folded-in state, the optional additional filter units (5) and an optional measuring device (6). The two middle skids (1) completely immersed in the electrodeposition bath show the filter medium (2) in the unfolded state, and the optional additional filter units (5) and an optional measuring device (6) in the completely immersed state. The arrow indicates the conveying direction.
Fig. 3A zeigt in einer Seitenansicht die Skizze eines erfindungsgemäßen Skids (1 ) ausgestattet mit einem eingeklappten Filtermedium (2), den fakultativen zusätzlichen Filtereinsätzen (5) sowie einer fakultativen Messvorrichtung (6). 3A shows in a side view the sketch of a skid (1) according to the invention equipped with a folded-in filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6).
Fig. 3B zeigt in einer Seitenansicht die Skizze eines erfindungsgemäßen Skids (1 ) ausgestattet mit einem ausgeklappten Filtermedium (2), den fakultativen zusätzlichen Filtereinsätzen (5) sowie einer fakultativen Messvorrichtung (6). Fig. 4 zeigt die Skizze eines erfindungsgemäßen Skids (1 ) von oben, ausgestattet mit einem Filtermedium (2), den fakultativen zusätzlichen Filtereinsätzen (5) sowie einer fakultativen Messvorrichtung (6). 3B shows a side view of the sketch of a skid (1) according to the invention equipped with an unfolded filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6). Fig. 4 shows the sketch of a skid (1) according to the invention from above, equipped with a filter medium (2), the optional additional filter inserts (5) and an optional measuring device (6).
Das erfindungsgemäße Verfahren hat sich als äußerst effektiv herausgestellt und es konnte eine weit über die Reinigung der Bulkphase des Elektrotauchlackbads hinausgehende Reinigung bzw. Dekontaminierung des Elektrotauchlackbades durch Bindung von Störsubstanzen an das Filtermedium (2) beobachtet werden. Insbesondere wiesen die im Elektrotauchlackierverfahren beschichteten Bleche nach der Durchführung der Reinigung eines kontaminierten Elektrotauchlackbades eine signifikant niedrigere Anzahl an Oberflächenstörungen, insbesondere eine niedrigere Anzahl an Kratern auf. Auf diese Weise konnte auch der frühzeitige Austausch des Elektrotauchlackbades sowie eine damit unweigerlich verbundene längere Unterbrechung des Lackierverfahrens vermieden werden. The method according to the invention has proven to be extremely effective and a cleaning or decontamination of the electrodeposition bath by binding interfering substances to the filter medium (2), which goes far beyond cleaning the bulk phase of the electrodeposition bath, was observed. In particular, the metal sheets coated in the electrocoating process had a significantly lower number of surface defects, in particular a lower number of craters, after a contaminated electrocoating bath had been cleaned. In this way, it was also possible to avoid the premature replacement of the electrodeposition paint bath and the inevitably associated longer interruption of the painting process.
Bezugszeichenliste List of reference symbols
(1 ) Skid (1) Skid
(2) Filtermedium (2) filter media
(3) Verbindungselement (3) connecting element
(4) Auftriebskörper (4) floats
(5) zusätzliche Filtereinsätze (5) additional filter elements
(6) fakultative Messvorrichtung (6) optional measuring device
(A) Auftauchzone (A) ascent zone
(E) Eintauchzone (E) immersion zone

Claims

Ansprüche Expectations
1. Verfahren zur Reinigung eines Elektrotauchlackbades in einer Durchlaufanlage, wobei ein mit einer Fördereinrichtung verbundenes Skid (1 ) durch das Elektrotauchlackbad befördert wird, dadurch gekennzeichnet, dass1. A method for cleaning an electrocoating bath in a continuous system, wherein a skid (1) connected to a conveyor device is conveyed through the electrocoating bath, characterized in that
(a) das Skid (1 ) ein Filtermedium (2) aufweist, (a) the skid (1) has a filter medium (2),
(b) das Filtermedium (2) am Skid (1 ) über mindestens ein bewegliches Verbindungselement (3) befestigt ist, (b) the filter medium (2) is attached to the skid (1) via at least one movable connecting element (3),
(c) das bewegliche Verbindungselement (3) die Ausrichtung des Filtermediums (2) an der Grenzfläche zwischen Elektrotauchlackbad und Luft erlaubt, und (c) the movable connecting element (3) allows the filter medium (2) to be aligned at the interface between the electrodeposition bath and air, and
(d) das Filtermedium (2) nach Eintauchen des Skids (1 ) in das Elektro tauchlackbad während der Förderung des Skids (1 ) durch das Elektro tauchlackbad an der Grenzfläche zwischen Elektrotauchlackbad und Luft ausgerichtet ist und entlang der Oberfläche des Elektrotauchlackbades gezogen wird. (d) the filter medium (2) after immersion of the skid (1) in the electro dip paint bath is aligned during the promotion of the skid (1) through the electro dip paint bath at the interface between the electrodeposition paint bath and air and is drawn along the surface of the electrodeposition paint bath.
2. Verfahren gemäß Anspruch 1 , dadurch gekennzeichnet, dass das Skid (1 ) eines oder mehrere am Filtermedium (2) und/oder Verbindungselement (3) befestigte Auftriebskörper (4) umfasst; und/oder das Verbindungselement (3) zwischen Filtermedium (2) und Skid (1 ) durch einen Antrieb das Filtermedium (2) an die Oberfläche des Elektrotauchlackbades befördert; und/oder das Filtermedium (2) aufgrund seiner Dichte oder eingeschlossener Hohlräume als Auftriebskörper (4) fungiert. 2. The method according to claim 1, characterized in that the skid (1) comprises one or more buoyancy bodies (4) attached to the filter medium (2) and / or connecting element (3); and / or the connecting element (3) between the filter medium (2) and the skid (1) conveys the filter medium (2) to the surface of the electrocoating bath by a drive; and / or the filter medium (2) acts as a buoyancy body (4) due to its density or enclosed cavities.
3. Verfahren gemäß einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, dass das Skid (1 ), eines oder mehrere zusätzliche Filtereinsätze (5) und/oder eine Messvorrichtung (6) umfasst. 3. The method according to any one of claims 1 or 2, characterized in that the skid (1) comprises one or more additional filter inserts (5) and / or a measuring device (6).
4. Verfahren gemäß einen der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass das Filtermedium (2) eines oder mehrere wasserabweisende Polymere umfasst. 4. The method according to any one of claims 1 to 3, characterized in that the filter medium (2) comprises one or more water-repellent polymers.
5. Verfahren gemäß Anspruch 4, dadurch gekennzeichnet, dass das oder die wasserabweisenden Polymere aus der Gruppe der Polyalkylene gewählt sind. 5. The method according to claim 4, characterized in that the water-repellent polymer or polymers are selected from the group of polyalkylenes.
6. Verfahren gemäß einem oder mehreren der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass das Filtermedium (2) im Wesentlichen senkrecht zur Förderrichtung des Skids (1 ) an der Oberfläche des Elektrotauchlackbades angeordnet ist und/oder das Filtermedium mindestens 80 % der Breite des Tauchlackbeckens einnimmt. 6. The method according to one or more of claims 1 to 5, characterized in that the filter medium (2) is arranged essentially perpendicular to the conveying direction of the skid (1) on the surface of the electrodeposition paint bath and / or the filter medium is at least 80% of the width of the Immersion paint basin occupies.
7. Verfahren gemäß einem oder mehreren der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass das Filtermedium (2) in Form eines textilen Flächenerzeugnisses gewählt aus der Gruppe der Gewebe, Gewirke, Gestricke, Filze oder Vliesstoffe gewählt ist. 7. The method according to one or more of claims 1 to 6, characterized in that the filter medium (2) is selected in the form of a textile flat product selected from the group of woven, knitted, knitted, felt or nonwovens.
8. Verfahren gemäß einem oder mehreren der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass das Filtermedium solche Substanzen physisorbiert oder ehern isorbiert, die an der Oberfläche des Elektrotauchlackbades anreichert sind und/oder die eine Oberflächenspannung kleiner als 35 mN/m besitzen. 8. The method according to one or more of claims 1 to 7, characterized in that the filter medium physisorbs or isorsorbs those substances which are enriched on the surface of the electrocoating bath and / or which have a surface tension of less than 35 mN / m.
9. Verfahren gemäß einem oder mehreren der Ansprüche 3 bis 8, dadurch gekennzeichnet, dass der oder die zusätzlichen Filtereinsätze (5) Materialen umfassen, die aus der Gruppe der wasserabweisenden Polymere gewählt sind und wobei diese in für den Elektrotauchlack durchlässigen Gehäusen, Netzen und/oder Beuteln vorliegen, ohne dass die Gehäuse, Netze und/oder Beutel für die Filtermaterialien durchlässig sind. 9. The method according to one or more of claims 3 to 8, characterized in that the additional filter insert (s) (5) comprise materials selected from the group of water-repellent polymers and these in housings, nets and / or or bags are present without the housing, nets and / or bags being permeable to the filter materials.
10. Verfahren gemäß einem oder mehreren der Ansprüche 3 bis 9, dadurch gekennzeichnet, dass die Messvorrichtung (6) zur Analyse der Beschaffenheit des Elektrotauchlackbades dient und/oder die Effektivität des Reinigungsverfahrens überprüft. 10. The method according to one or more of claims 3 to 9, characterized in that the measuring device (6) is used to analyze the nature of the electrodeposition paint bath and / or checks the effectiveness of the cleaning process.
11. Skid (1 ) für Elektrotauchlack-Durchlaufanlagen, wobei das Skid (1 ) ein Filtermedium (2) aufweist, welches mit dem Skid (1 ) über ein oder mehrere bewegliche Verbindungselemente (3) so verbunden ist, dass sich das Filtermedium beim Betrieb der Elektrotauchlack-Durchlaufanlage an der Grenzfläche zwischen Elektrotauchlackbad und Luft ausrichten kann. 11. Skid (1) for continuous electrodeposition systems, the skid (1) having a filter medium (2) which is connected to the skid (1) via one or more movable connecting elements (3) in such a way that the Can align the filter medium when operating the electrodeposition paint system at the interface between the electrodeposition paint bath and air.
12. Skid (1 ) gemäß Anspruch 11 , dadurch gekennzeichnet, dass das Skid (1 ) eines oder mehrere am Filtermedium (2) und/oder Verbindungselement (3) befestigte Auftriebskörper (4) umfasst. 12. Skid (1) according to claim 11, characterized in that the skid (1) comprises one or more buoyancy bodies (4) attached to the filter medium (2) and / or connecting element (3).
13. Skid (1 ) gemäß einem der Ansprüche 11 oder 12, dadurch gekennzeichnet, dass das Skid (1 ), eines oder mehrere zusätzliche Filtereinsätze (5) und/oder eine Messvorrichtung (6) umfasst. 13. Skid (1) according to one of claims 11 or 12, characterized in that the skid (1) comprises one or more additional filter inserts (5) and / or a measuring device (6).
14. Skid (1 ) gemäß einer der Ansprüche 11 bis 13, dadurch gekennzeichnet, dass das Filtermedium (2), und sofern vorhanden die zusätzlichen Filtereinsätze (5), Materialen umfassen, die aus der Gruppe der wasserabweisenden Polymere gewählt sind. 14. Skid (1) according to one of claims 11 to 13, characterized in that the filter medium (2) and, if present, the additional filter inserts (5), comprise materials selected from the group of water-repellent polymers.
15. Skid (1 ), gemäß einem der Ansprüche 13 oder 14, dadurch gekennzeichnet, dass die Messvorrichtung (6) zur Analyse der Beschaffenheit des Elektrotauchlackbades dient und/oder die Effektivität des Reinigungsverfahrens überprüft. 15. Skid (1), according to one of claims 13 or 14, characterized in that the measuring device (6) is used to analyze the nature of the electrodeposition paint bath and / or checks the effectiveness of the cleaning process.
EP20737502.3A 2019-07-16 2020-07-15 Method for cleaning electrophoretic coating baths, and device therefor Pending EP3999674A1 (en)

Applications Claiming Priority (2)

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EP19186475 2019-07-16
PCT/EP2020/070040 WO2021009254A1 (en) 2019-07-16 2020-07-15 Method for cleaning electrophoretic coating baths, and device therefor

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US (1) US20220243354A1 (en)
EP (1) EP3999674A1 (en)
JP (1) JP7441300B2 (en)
CN (1) CN114222617B (en)
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WO (1) WO2021009254A1 (en)

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JP7441300B2 (en) 2024-02-29
JP2022540926A (en) 2022-09-20
MX2022000609A (en) 2022-03-11
CN114222617A (en) 2022-03-22
CN114222617B (en) 2024-07-05
US20220243354A1 (en) 2022-08-04

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