DE102019130996A1 - Surface coating method and surface coating device for coating a structural unit and a vehicle - Google Patents

Abstract

The invention relates to a surface coating method for coating a structural unit, a surface coating device for carrying out a surface coating method, and a vehicle. The surface coating method according to the invention for coating a structural unit, in particular a structural unit for a motor vehicle, in which a structural unit to be coated is provided, onto the surface of the to coating structural unit, a conversion layer, in particular a conversion layer comprising metal phosphates, is applied at least in certain areas and a liquid coating material is deposited at least in certain areas electrophoretically, in particular by means of a cathodic dip painting process, on a surface of the structural unit and / or the conversion layer. Furthermore, a filler is applied to the liquid coating material at least in certain areas and the layer composite comprising the conversion layer, the layer resulting from the electrophoretic deposition (30) and the filler layer for the purpose of curing, in particular by crosslinking non-volatile components of the means with the electrophoretic deposition (30 ) applied coating material and / or the filler, heated by means of a curing device (73).

Description

The invention relates to a surface coating method for coating a structural unit, a surface coating device for carrying out the surface coating method, and a vehicle which comprises at least one structural unit coated according to the surface coating method.

Typically, when painting components, in particular body parts, in a first step in a cathodic dip painting, a dip paint is applied which is completely cured before the component is further coated with a filler. This process is also known as burn-in. Then, in a second step, and after the component has been sealed, the filler is applied, which also undergoes heat treatment before the component is provided with colored and clear lacquer in further process steps.

In order to save process times and costs, it is possible to dispense with baking the dipping varnish immediately after its application and without applying a filler. In this case, the dip lacquer undergoes its first heat treatment after the seal has been applied in a so-called gel dryer.

The DE 100 52 438 A1 shows a process for producing a multicoat paint system. In this case, an electrodeposition coating film deposited on a substrate is predried for a specified time at 0 ° C. to 35 ° C. and then a filler is applied. Electrocoating film and filler are baked in together.

The DE 195 12 017 C1 shows another process for producing a multicoat paint system. The document discloses a method in which a second coating layer of a basecoat material is applied wet-on-wet to a first electrophoretically deposited coating layer and these two coating layers are baked together. Further layers are then applied, with two layers being baked together at a time. That in the DE 195 12 017 C1 The method shown dispenses with filler and / or intermediate layers.

The EP 3 004 257 B1 shows a method for dip coating in which a component provided with an electrophoretically deposited dip lacquer is brought into contact with an aqueous sol-gel composition in a second step before the dip lacquer is cured.

1 Figure 12 shows an embodiment of a typical prior art surface coating process in which no filler is applied. The material flow of the unit in the process is shown as a basic flow diagram. Such a process is common, for example, in the surface treatment of bodies and body components in motor vehicle construction. As a rule, the entire surface of the body is treated with the method shown, although it is not excluded that only areas of the surface of the structural unit are treated with the method explained below. The unit is initially in a deployment 10 provided. Then it goes through a pre-treatment 20th . At least one sub-step in the pretreatment is usually a phosphating of the surface of the structural unit. Subsequent to the pretreatment 20th a liquid coating agent is applied to the surface of the structural unit by means of electrophoretic deposition 30th deposited. Typically, this process step in vehicle construction involves cathodic dip painting. Subsequent to the electrophoretic deposition 30th and a first quality control 32 is a sealing of the unit by means of a first seal 41 and a second seal 42 performed. Typically in the first seal 41 an underbody protection applied while in the second sealant 42 Window and door areas are sealed. In both cases, the seal can optionally include both a coarse seal or seal and a fine seal or seal. Subsequently, the structural unit undergoes a sealing pre-drying 50 fed, in which the sealing materials are typically predried at temperatures between 100 ° C and 150 ° C for 5 min to 15 min.

Following the pre-drying of the sealing 50 the structural unit goes through a generally multi-stage painting process in which the final top coat is applied to the structural unit and cured. After top coat preparation 61 and a cleaning 62 the unit becomes over a pre-zone 63 the paint application 64 fed. The one in the paint application 64 applied color varnish is in an intermediate drying 65 at least partially dried before in the clearcoat application 66 a clear lacquer is applied to the colored lacquer. After that, the final drying of all applied layers takes place in the top coat drying 67 . Typically, in such a process according to the prior art, the topcoat is applied several times, in particular twice. The top coat drying 67 typically takes place at 60 ° C to 75 ° C, with the heat acting on the paint layer for a maximum of two minutes.

Following the application of the top coat and its drying, a top coat is typically checked 68 instead of before the assembly has a finishing 80 and a repair station 85 a cavity preservation 90 is supplied, to which then the structural unit to the feed for assembly 100 is passed.

The illustration shows that the process provides that the structural unit between the repair station 85 and cavity preservation 90 for rework 87 can be reintroduced into the process of topcoat application.

The present invention is based on the object of providing a surface coating method and a surface coating device with which a surface coating can be applied to a structural unit in a low-emission and cost-saving manner.

The object is achieved according to the invention by a surface coating method according to claim 1 and by a surface coating device for performing a surface coating method according to claim 8. Advantageous embodiments of the surface coating method are shown in subclaims 2-7. In addition, a motor vehicle according to claim 9 is made available.

A first aspect of the invention is a surface coating method for coating a structural unit, in particular a structural unit for a motor vehicle, in which a structural unit to be coated is provided and a conversion layer, in particular a conversion layer comprising metal phosphates, is applied to the surface of the structural unit to be coated at least in some areas.

Furthermore, a liquid coating material is deposited on a surface of the structural unit and / or the conversion layer at least in some areas electrophoretically, in particular by means of a cathodic dip painting process. In addition, a filler is applied to the liquid coating material at least in certain areas and which the conversion layer, the layer resulting from the electrophoretic deposition and the layer composite comprising the filler layer for the purpose of curing, in particular by crosslinking non-volatile components of the coating material applied by means of the electrophoretic deposition and / or the Filler, heated by means of a curing device.

The structural unit to be coated is in particular a body or a body component for a motor vehicle.

The structural unit comprises at least in sections, preferably essentially completely, at least one metallic material, in particular a steel and / or an aluminum or an aluminum alloy.

A conversion layer is typically to be understood as meaning a layer essentially comprising inorganic molecules on a metal surface of a structural unit. The conversion layer is applied or formed on the surface of the structural unit prior to the deposition of the liquid coating material. A conversion layer is preferably produced by phosphating, metal phosphates being produced on the surface of the structural unit through the reaction of a metallic surface with an aqueous phosphate solution.

The advantage of a conversion layer is an improvement in the adhesive properties of the surface of the structural unit. This leads in particular to improved deposition in the sense of better adhesion of the liquid coating material on the surface of the structural unit comprising a conversion layer.

After the conversion layer has been applied, a liquid coating material is electrophoretically deposited at least in some areas on the surface of the structural unit provided. The deposition typically takes place by means of a cathodic dip painting process, in which case the liquid coating material can also be referred to as an electrodeposition paint. However, other electrophoretic deposition processes for depositing a liquid coating material on a surface, such as anodic dip painting, are in principle not excluded.

In the case of electrophoretic deposition, the areas of the structural unit on whose surface the liquid coating material is to be deposited are introduced into an immersion bath filled with the liquid coating material, so that the surface to be coated is essentially completely surrounded by the liquid coating material and is wetted by it. In particular, the entire structural unit is introduced into an immersion bath filled with the liquid coating material.

The liquid coating material optionally comprises non-volatile components which, when hardening, on the surface of the structural unit remain and volatile components, which are at least partially removed from the liquid coating material or the layer formed by the liquid coating material at least during curing.

The coating material serves, among other things, for corrosion protection in the finally coated structural unit or in the finished motor vehicle.

By applying a voltage, in particular a direct voltage, between the structural unit and a counter electrode, an at least partial deposition of the liquid coating material is effected on the surface of the structural unit.

After the liquid coating material has been deposited, excess portions of the liquid coating material can typically be removed from the structural unit. This is usually done by means of a flushing process.

In particular after the deposition of the liquid coating material, a filler is applied to the liquid coating material or at least to areas of the structural unit on which the liquid coating material has been deposited. In other words, a filler layer is applied to the layer of liquid coating material resulting from the electrophoretic coating.

When the filler is applied, the liquid coating material is essentially uncured or uncrosslinked. In other words, the liquid coating material is not completely cured before the filler is applied.

The filler is applied to the coating material, which is essentially in the liquid phase. It is not excluded that the material composition of the coating material is changed between the deposition of the liquid coating material and the application of the filler, for example by at least partially removing components of the liquid coating material, in particular volatile components. It is also not excluded that material properties, such as the dynamic viscosity and / or the density, of the coating material are changed between the deposition of the liquid coating material and the application of the filler.

In time before the filler is applied, the structural unit is optionally prepared in such a way that impurities are removed from the structural unit.

When the filler is applied to the liquid coating material, however, there is typically not necessarily an at least regional mixing of the filler and the liquid coating material at least in the contact area between the filler and the coating material. In other words, it is possible for a transition layer which comprises both filler and coating material to be formed between a layer essentially comprising filler and a layer essentially comprising coating material.

When the coating of the structural unit is fully developed, the filler serves to protect the layer resulting from the electrophoretic coating.

The layer resulting from the electrophoretic coating and the filler layer together form a layer composite. For the purpose of curing the layer composite, the layer composite is heated in a curing device, in particular non-volatile components or constituents of the coating material applied by means of the electrophoretic deposition and / or of the filler being crosslinked. In particular, during the curing process, volatile, in particular highly volatile, components of the coating material and / or the filler applied by means of the electrophoretic deposition are at least partially removed.

In the context of the invention, a non-volatile component is to be understood as meaning a component whose evaporation number is higher than the evaporation number of water. In this sense, non-volatile components are also to be understood as meaning non-volatile components.

The curing device is typically an oven. In the context of the invention, curing is to be understood as the transition from an essentially liquid state to an essentially solid state. During the curing process, components or constituents of the material to be cured are typically crosslinked at the molecular level.

In one embodiment of the method, at least one topcoat, in particular a colored and / or clearcoat, is applied to the cured layer composite, comprising the coating material and the filler. Before the topcoat is applied to the cured layer composite, the structural unit is checked for damage and contamination and prepared for the topcoat application. In particular, residues from previous processing steps, dirt and metal particles are removed from the structural unit. After that, will at least one top coat is applied, which is dried and / or cured in a top coat drying device by the action of heat. The top coat is exposed to a _{top coat drying temperature T D} of at least 120 ° C. and at most 150 ° C. _{for a duration t D} of at least 1200 s and at most 2100 s by means of the top coat drying device. Typically, a first lacquer layer, here a colored lacquer layer, and then a second lacquer layer, here a clear lacquer layer, is applied first, with intermediate drying in an intermediate dryer taking place before the application of the second lacquer layer. In the intermediate dryer, heat is applied to the first lacquer layer, the colored lacquer layer. However, the first layer of lacquer is not necessarily completely cured in this case.

The advantage of the surface coating method according to the invention is the saving of energy by dispensing with complete curing of the liquid coating material before application of the filler and consequently the reduction of emissions, in particular CO2 emissions from the process of providing the heat required for curing. Furthermore, because the liquid coating material is not hardened before the filler is applied, the time required to produce a coated structural unit is reduced.

In one embodiment of the surface coating process, the filler is applied in the liquid phase.

In other words, the filler is applied to the liquid coating material as a liquid. The application of the filler can therefore also be referred to as wet-on-wet application.

Typically, when the filler is applied in the liquid phase to the coating material, which is also in the liquid phase, the two liquid phases mix at least partially, so that a mixture of filler and coating material is formed at least in the contact area between the filler and the coating material.

One advantage of this embodiment is that intensive contact is formed between the layers of the layer composite.

In one embodiment of the surface coating process, the layer composite is _{heated to a curing temperature T A} by means of the curing device, where T _A > 150 ° C.

In other words, the curing temperature T _A , at which at least the layer composite, but preferably the entire structural unit coated with the coating material and the filler, is acted upon in the curing device, is at least 150.degree. The curing temperature T _{A is} dependent on the material properties, in particular the thermal conductivity, of the material from which the structural unit is essentially formed. _{The curing temperature T A is} preferably at least 175.degree. C. for a structural unit essentially comprising a steel typical for body construction. For a structural unit comprising essentially aluminum, the curing temperature T _{A is} preferably at least 185 ° C.

The action of heat at the curing _{temperature T A} on the layer composite causes the layer composite or the materials forming the layer composite to harden. Typically, components or constituents of the liquid coating material and / or the filler with a comparatively high volatility, i.e. volatile or easily volatile components, are converted into the gas phase by the action of heat and thus removed from the layer composite, while components with comparatively low volatility, that is, heavy or non-volatile components, remain in the layer composite and form a solid phase.

The advantage of this embodiment is that, by means of the curing _{temperature T A} of at least 150 ° C., both the liquid coating material and the filler are cured essentially simultaneously.

In one embodiment of the surface coating process, the layer composite is exposed to the temperature T _A for a duration of t _A by means of the curing device, where t _A > 900 s.

This means, for example in the case of a configuration of the curing device as a continuous furnace, that the dwell time of the structural unit comprising the layer composite in the curing device is at least 900 s, preferably at least 1200 min.

The advantage of this embodiment is that a sufficient amount of heat for curing acts on the layer composite.

In one embodiment, the curing device is designed as a continuous furnace, the structural unit being introduced into the continuous furnace in an entrance area, traversing it and being led out of the continuous furnace in an exit area. Alternatively, there is also one Curing device possible in which the furnace is set up for batch operation.

The advantage of this configuration is that a sufficient amount of heat for curing acts on the layer composite or that there is sufficient heat exposure time for curing.

In one embodiment of the surface coating process, the liquid coating material is heated in a predrying device after it has been deposited on the surface of the structural unit to be coated and before the filler is applied to the liquid coating material, for the purpose of at least partial removal of at least one volatile component from the liquid coating material.

In other words, the liquid coating material is predried in a predrying device before the filler is applied.

The liquid coating material comprises at least one volatile, preferably at least slightly or moderately volatile, first component, preferably water, and at least one second component which is less volatile than the first component and which forms the cured surface coating after curing.

For the purposes of the invention, a volatile component is a component with an evaporation number of at most 160, preferably at most 120, the evaporation number being identical, in particular, to the evaporation time of a fixed amount of the component in relation to the evaporation time of the same amount of diethyl ether standardized environmental conditions. The evaporation rate is typically determined in accordance with DIN 53170. The evaporation rate of water is 80.

A mass fraction of at most 0.8, but at least 0.2 of at least one volatile first component, in particular water, is removed from the liquid coating material by means of the predrying unit. It is possible here for physical properties of the coating material, in particular density and / or viscosity, to be changed. It is also not ruled out that there may be partial crosslinking of the second components of the coating material, which are less volatile than the first component.

The advantage of this configuration is that volatile fractions of the liquid coating material are removed before the layer composite is finally cured.

In a further embodiment of the surface coating method, the deposited liquid coating material is _{heated to a predrying temperature T v} by means of the predrying device, where T _v <100.degree.

In other words, the pre-drying temperature T _v , at which at least the electrophoretically deposited layer of the liquid coating material, but preferably the entire structural unit coated with the coating material, is exposed in the pre-drying device, is at most 100 ° C. The predrying temperature T _{v is} dependent on the material composition of the liquid coating material. The predrying temperature T _v is to be chosen so that it is below the crosslinking temperature, in other words below the minimum temperature required for crosslinking, of the liquid coating material, in particular below the crosslinking temperature of the less volatile components of the liquid coating material, so that only the more volatile components Components, especially water, escape.

The advantage of this embodiment is that, in particular, only water escapes during the pre-drying as an emission during the pre-drying process, which is why cleaning of the process exhaust air, in particular thermal exhaust air purification by post-combustion of the exhaust air, is not necessary. By dispensing with post-combustion, energy and CO ₂ emissions can be saved.

In a further embodiment, the predrying time t _v , or the residence time of the structural unit in the predrying device, is at least 60 s, but not more than 1800 s, preferably at least 120 s, but not more than 1200 s. The predrying time t _{v is} dependent on the mass and / or the volume of the unit.

The predrying device is typically an oven, preferably a continuous oven.

In a further embodiment of the surface coating method according to the invention, at least one sealing material is applied in some areas to the liquid coating material before the filler is applied, for the purpose of sealing the structural unit at least in sections.

In other words, after the first liquid coating material has been deposited, but before the filler is applied to the liquid coating material, at least one sealing material is applied. It is not excluded that the liquid coating material is predried before applying the sealing material.

The sealing material can also be referred to as sealing material. In particular, it is possible for different and / or multiple sealing materials to be applied in areas. In the case of a structural unit for a motor vehicle, in particular a motor vehicle body, a multi-stage sealing or sealing of various areas of the structural unit is typically carried out. In a first sealing process, the areas that form the underbody in the finished vehicle are sealed. In a second sealing process, the areas that form window and door openings in the finished vehicle, for example, are sealed.

Sealing materials in the sense of the invention are sealing materials which are suitable for preventing liquids in particular, such as water, from getting in the sealed areas of the structural unit from an outside of the structural unit to an inner side of the structural unit. In other words, a protective layer is applied by the sealing.

In a further embodiment, after its application, the sealing material is heated in a heat treatment device for the purpose of predrying the sealing material. The heating in the heat treatment device can take place before the filler is applied. A corresponding heat treatment device is also referred to as a gelation dryer. The residence time of the structural unit in the heat treatment device is typically between 180 s and 1200 s, in particular between 300 s and 900 s. The heat treatment temperature is typically between 90 ° C and 160 ° C, in particular between 100 ° C and 150 ° C.

In this way, relevant areas of the structural unit can be reliably sealed.

A second aspect of the invention is a surface coating device for carrying out the surface coating method according to the invention for coating a structural unit, in particular for coating a structural unit for a motor vehicle, which includes a device for applying a conversion layer, a deposition device for the electrophoretic deposition of a liquid coating material on a surface of the structural unit, a Application device for at least regionally applying a filler to the liquid coating material and a curing device for heating the conversion layer, the layer resulting from the electrophoretic coating and the filler layer for the purpose of curing, in particular by crosslinking non-volatile components of the coating material applied with the electrophoretic deposition and / or the filler.

The surface coating device is used to carry out the surface coating method according to the invention and thus an energy-saving and low-emission production of a coated structural unit. The surface coating device can furthermore comprise devices for predrying the liquid coating material before application of the filler, as well as devices for applying seals and / or topcoats.

Furthermore, the surface coating device can comprise a transport device, by means of which the structural units can be moved between the devices and / or within the devices.

A third aspect of the invention is a vehicle, in particular a motor vehicle, which comprises at least one structural unit coated according to the surface coating method according to the invention, which can in particular be a body.

The invention is explained below with reference to the exemplary embodiments shown in the accompanying drawings.

• 1: ein exemplarisches Oberflächenbeschichtungsverfahren gemäß dem Stand der Technik ohne Aufbringung eines Füllers als Grundfließschema;
• 2: eine schematische Darstellung einer Ausgestaltungsform des erfindungsgemäßen Oberflächenbeschichtungsverfahrens als Grundfließschema; sowie
• 2: eine zweite Ausgestaltungsform des erfindungsgemäßen Oberflächenbeschichtungsverfahrens als Grundfließschema.

Show it

• 1 : an exemplary prior art surface coating process without the application of a filler as a basic flow sheet;
• 2 : a schematic representation of an embodiment of the surface coating method according to the invention as a basic flow diagram; as
• 2 : a second embodiment of the surface coating process according to the invention as a basic flow diagram.

On the 1 was already addressed in the course of the assessment of the state of the art.

2 shows a first embodiment of the surface coating method according to the invention for coating a structural unit in a schematic manner as a basic flow diagram. The material flow of the structural unit in the surface coating method according to the invention is shown.

After deployment 10 A conversion layer is applied to the structural unit. This step is not shown separately in the present scheme. After the conversion layer has been applied, electrophoretic deposition takes place 30th , for example in the form of a cathodic dip painting, of the liquid coating material. This is followed by the application of the filler 72 . Between the electrophoretic deposition 30th and the application of the filler 72 there are essentially no further method steps that change the structural unit or the surface of the structural unit, in particular no method steps that cause the liquid coating material to harden. Thus the filler is applied to a wet layer of liquid coating material. The liquid coating material and / or the filler are hardened in the hardening device 73 that timed after the filler was applied 72 is arranged. In the embodiment shown here, the supply for assembly takes place after hardening 100 , whereby it is not excluded that between curing in the curing device 73 and the feed to the assembly 100 further coating materials are applied to the structural unit.

3 shows a second embodiment of the surface coating method according to the invention for coating a structural unit. Analogous to the 1 and 2 the material flow is also shown here.

The assembly is analogous to that in 1 method shown initially in a deployment 10 provided and then goes through a pre-treatment 20th , which typically includes the application of a conversion layer by phosphating the surface of the structural unit. Subsequent to the pretreatment 20th a liquid coating agent is applied to the surface of the structural unit by means of electrophoretic deposition 30th , typically with the process of cathodic dip painting applied.

Subsequent to the electrophoretic deposition 30th In this exemplary embodiment of the method according to the invention, the liquid coating material is predried in a predrying device 31 instead of. The water is partially removed from the usually water-based liquid coating material. This is followed by an initial quality control 32 instead of.

After the filler preparation 71 takes place in a manner analogous to that in 1 a seal for the purpose of sealing the structural unit instead of typically a first seal 41 and a second seal 42 . In the process step of applying the filler 72 the filler is applied to the sealing material. Optionally, between sealing 41 , 42 and the application of the filler 72 a further intermediate drying can be arranged for the purpose of at least partial drying of the sealing material.

For the purpose of curing the liquid coating material and / or the filler, the structural unit is then applied to the filler 72 the curing device 73 fed. Optionally, there is a second quality control after curing 74 instead of.

Analogous to the in 1 According to the prior art process shown here, painting is also provided in the surface coating method according to the invention shown here. After top coat preparation 61 and a cleaning 62 becomes the unit of paint application 64 fed. The one in the paint application 64 applied color varnish is in an intermediate drying 65 at least partially dried before in the clearcoat application 66 a clear lacquer is applied to the colored lacquer. After that, the final drying of all applied layers takes place in the top coat drying 67 .

Following the application of the top coat and its drying, a top coat is typically checked 68 instead of before the assembly has a finishing 80 and a repair station 85 a cavity preservation 90 is fed, and then the unit to the feed for assembly 100 is passed.

Analogous to 1 the method shown provides that the structural unit between the repair station 85 and cavity preservation 90 for rework 87 can be reintroduced into the process of topcoat application.

List of reference symbols

10

Provision

20th

Pretreatment

30th

electrophoretic deposition

31

Pre-drying device

32

first quality control

41

first seal

42

second seal

50

Sealing pre-drying

61

Top coat preparation

62

cleaning

63

Pre-zone

64

Color lacquer application

65

Intermediate drying

66

Clear coat application

67

Top coat drying

68

Top coat inspection

71

Filler preparation

72

Application of filler

73

Curing device

74

second quality control

80

Finishing

85

Mending place

87

post processing

90

Cavity preservation

100

Feed assembly

QUOTES INCLUDED IN THE DESCRIPTION

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

Patent literature cited

• DE 10052438 A1 [0004]
• DE 19512017 C1 [0005]
• EP 3004257 B1 [0006]

Claims (9)

Surface coating method for coating a structural unit, in particular a structural unit for a motor vehicle, in which i) a structural unit to be coated is provided, ii) a conversion layer, in particular a conversion layer comprising metal phosphates, is applied to the surface of the structural unit to be coated, at least in some areas, iii) at least in some areas, electrophoretically, in particular by means of a cathodic dip painting process, a liquid coating material is deposited on a surface of the structural unit and / or the conversion layer, iv) a filler is applied to the liquid coating material at least in some areas and v) the layer composite comprising the conversion layer, the layer resulting from the electrophoretic deposition (30) and the filler layer for the purpose of curing, in particular by crosslinking non-volatile components of the coating material and / or the filler applied by means of the electrophoretic deposition (30), by means of a Curing device (73) is heated. Surface coating process for coating a structural unit according to Claim 1 , characterized in that the filler is applied in the liquid phase. Surface coating method for coating a structural unit according to one of the preceding claims, characterized _{in that the layer composite is heated to a curing temperature T A} by means of the curing device (73), T _A > 150 ° C. Surface coating process for coating a structural unit according to Claim 3 , characterized in that the layer composite is acted upon by the curing device (73) with the temperature T _A for a duration of t _A , where t _A > 900 s. Surface coating method for coating a structural unit according to one of the preceding claims, characterized in that the liquid coating material in a predrying device (30) after its electrophoretic deposition (30) on the surface of the structural unit to be coated and before the filler (72) is applied to the liquid coating material ( 31) is heated for the purpose of at least partial removal of at least one volatile component from the liquid coating material. Surface coating process for coating a structural unit according to Claim 5 , characterized in that the deposited liquid coating material is heated by means of the predrying device (31) to a predrying _{temperature T v} , where T _v <100 ° C. Surface coating method for coating a structural unit according to one of the preceding claims, characterized in that at least one sealing material is applied to the liquid coating material in some areas prior to application of the filler (72) for the purpose of sealing the structural unit at least in sections. Surface coating device (1) for carrying out the surface coating method according to one of the Claims 1 - 7th for coating a structural unit, in particular for coating a structural unit for a motor vehicle, comprising a device for applying a conversion layer, a deposition device for the electrophoretic deposition (30) of a liquid coating material on a surface of the structural unit, an application device for at least regionally applying a filler (72) on the liquid coating material and a curing device (73) for heating the layer composite comprising the conversion layer, the layer resulting from the electrophoretic coating and the filler layer for the purpose of curing, in particular by crosslinking non-volatile components of the coating material applied with the electrophoretic deposition and / or the Filler. Vehicle, in particular motor vehicle, comprising at least one according to the surface coating method according to one of the Claims 1 to 7th coated structural unit.

Images