EP3936236B1 - Method for coating objects and installation for coating objects - Google Patents

Description

The invention relates to a method for coating objects by applying, drying, curing and after-treating moisture-curing paint systems to the object according to the preamble of claim 1.

The invention also relates to a system for painting objects according to the preamble of claim 9.

Through the targeted non-contact effect of electromagnetic radiation, e.g. infrared radiation on conventional paint systems, drying and/or curing can be accelerated and the object carrying the coating, e.g. a body part of a motor vehicle, itself can be protected. The disadvantage here is that the radiation-generating systems for process safety must always be used within a paint booth or a closed room, which, due to the thermal effect in connection with the materials used, poses a risk in terms of occupational safety, fire protection and represents the explosion protection. The use of specially secured systems for this generates high costs when installing such systems.

Another disadvantage is that with such methods, the objects have to remain in the closed space, in particular the respective paint booth, after coating until they have reached a dust-dry and/or handleable state, and thus the space, in particular the paint booth, during the curing of the block coating. During this time no further objects can be in be coated in the closed space, especially in the paint booth, and this is therefore not optimally utilized.

Methods for coating objects are known from the prior art which, due to specific binders, supplements, additives or the like, cure as moisture-curing paint systems without oven drying or oven energy. In such coating processes, appropriate amounts of moisture that react directly with the paint system are used in order to reduce the drying and/or curing time of the paint system. These moisture-curing paint systems are reliably processed by supplying moisture and/or additives via the atomizer compressed air or the atomizer gas with subsequent air drying.

The JP 2016 019940 A discloses an apparatus and method in which moisture-curing silicone is sprayed with heated and humidified compressed air.

Also disclosed DE 10 2018 118206 A1 a similar device and method in which moisture-curing paint system is sprayed with heated and humidified compressed air. In addition, a hose heater within the device is also disclosed.

U.S. 2,498,339 A deals with the safety aspect, in which the curing takes place by means of infrared radiation outside the paint booth. The bodywork shown in the illustrations is lifted out of the paint booth into a curing chamber with infrared elements using a lifting platform. Disclosed for the purpose of easy and faster painting of very long and large rotor blades U.S. 2013/095248 A1 each mobile, independently movable painting and infrared drying chambers.

Also U.S. 2016/084573 A1 deals with the safety aspect, in which the curing takes place by means of infrared radiation outside the paint booth. In addition, ignition-free chambers are set up between the paint booth and the drying ovens.

DE 10 2006 045642 A1 discloses a system with a number of parallel painting chambers and work stations in a clocked painting system in order to be able to use the clocked system more efficiently for different painting jobs that require different times.

Also in the U.S. 5,060,594A a painting line is disclosed in which the painting chambers and the infrared chamber are separated from one another. In a specific step, the body to be coated is first coated irradiated with long-wave IR radiation and then cooled to prevent the body from overheating.

A major disadvantage of these paint systems is that although after the drying phase has taken place up to so-called dust dryness, an accelerated process-reliable drying takes place, but then in a hardening phase the chemical reactions, after which post-processing, in particular a polishability of the painted object and / or stackability of the painted object and/or further processing of the painted object is reached, is slower and much more time is required compared to the drying phase. Here, the chemical reactions lead to further drying of the paint system in the sense of thorough drying and hardening of the paint system in the sense of curing.

In practice, it has been shown that the drying of the paint system is reliably completed in about 12 minutes, but it is also evident that, for example, it can only be polished or painted over after 40-60 minutes process-reliable is given. In production, corresponding waiting times in a painting booth are therefore necessary before a polishing process or before painting can be carried out after intermediate drying, and the painted objects can therefore only be processed further with a delay. The coating system can, for example, consist of a base coat and a clear coat.

In order to enable objects to be coated with high quality, the coating is carried out in closed rooms with supply air ducting and/or exhaust air ducting, in particular in paint booths. This prevents the coating from being exposed to negative external influences, such as dirt, additional heat, or additional moisture.

A major disadvantage of the prior art is that the infrared technology used has always had to be installed inside the paint booth in order to dry the freshly applied paint application with infrared so that the dry parts, e.g. an automobile or individual parts of a car, can be removed from the paint booth can be removed and/or brought out. As a result, expensive and complex equipment has to be installed inside each painting booth and is therefore exposed to overspray (spray mist next to the object to be painted) and other dirt. This expensive equipment has to be regularly cleaned, serviced and protected. At the same time, a corresponding technical installation within the paint booth also acts as a dirt trap and is therefore the cause of soiling of the paint surface.

This can be avoided by installing the invention outside the cabin. You have less pollution on the Parts and thus a better painting quality, less rework and less maintenance and cleaning effort.

Another major disadvantage is that infrared drying takes up a lot of space in existing paint booths, which in certain cases makes it impossible to use infrared drying at all or makes it impossible to retrofit infrared drying.

Another significant disadvantage of stationary infrared drying is that there is a risk of overheating of the plastic parts when drying them.

Another significant disadvantage is that infrared drying would have to be installed for each paint booth, which means a very high investment requirement.

Another significant disadvantage is that the subsequent curing time of up to 30 to 60 minutes causes delays in the process flow, or that more space is required in subsequent processes.

Another significant disadvantage is that with conventionally performed infrared drying steps, wet paints have to be dried with high energy input by means of infrared radiation, so that the surfaces such as plastics can be damaged.

The invention is therefore based on the object of developing a simpler, time-saving and energy-efficient method for coating objects, in which accelerated paint curing can take place. Furthermore, the object of the invention is a system for painting objects to propose a method for accelerated paint curing.

This object is achieved in conjunction with the features of claim 1 and independent claim 9. Advantageous and expedient developments are specified in the respective dependent claims.

1. a) Befeuchten einer Zerstäuberdruckluft bzw. eines Zerstäubergases;
2. b) wobei Wärme auf die Zerstäuberdruckluft bzw. das Zerstäubergas zugeführt, insbesodnere Wärme auf das Zerstäubergas über den das Zerstäubergas führenden Lackierschlauch zugeführt wird;
3. c) wobei das Objekt durch Versprühen des feuchtigkeitshärtenden Lacksystems mittels der Zerstäuberdruckluft bzw. des Zerstäubergases innerhalb einer Lackierkabine lackiert wird;
4. d) wobei das Objekt aus der Lackierkabine nach einer Trocknungszeit zu einem Trocknungszeitpunkt entnommen wird, wobei ab dem Trocknungszeitpunkt das Eintreten eines oberflächlich staubtrockenen Zustands und damit handhabbaren Zustands des Lacksystems vorliegt;
5. e) wobei das Lacksystems außerhalb der Lackierkabine durch Bestrahlung des Objekts mittels mindestens eines Infrarotstrahlers für eine Härtungszeit bis zu einem Härtungszeitpunkt getrocknet und/oder weiter ausgehärtet wird;

Das Lacksystem wird, soweit durch den Prozess erforderlich, außerhalb der Lackierkabine in einem Finalisierungsschritt, insbesondere mittels Polieren der lackierten Objektoberfläche nachbehandelt oder anderweitig weiterverarbeitet.The method according to the invention for coating objects by applying, drying, curing and after-treating moisture-curing or isocyanate-based or other coating systems on the object comprises in particular the following steps:

1. a) humidifying an atomizer compressed air or an atomizer gas;
2. b) heat being supplied to the atomizing compressed air or the atomizing gas, in particular heat being supplied to the atomizing gas via the painting hose carrying the atomizing gas;
3. c) the object being painted by spraying the moisture-curing paint system by means of the atomizer compressed air or the atomizer gas inside a paint booth;
4. d) wherein the object is removed from the paint booth after a drying time at a drying time, wherein from the drying time onwards the paint system is in a superficially dust-dry state and is therefore in a manageable state;
5. e) the paint system being dried and/or further cured outside the paint booth by irradiating the object by means of at least one infrared radiator for a curing time up to a curing point in time;

If required by the process, the paint system is post-treated or otherwise processed outside of the paint booth in a finalization step, in particular by polishing the painted surface of the object.

By moistening the atomizer compressed air or the atomizer gas, the chemical processes are chemically accelerated, particularly in the first phase, down to dust dryness, which are necessary for curing the respective coating, in particular moisture-curing paint systems. This enables these processes to be activated in a targeted manner, which can chemically accelerate the drying and curing time of the coating.

By using painting air humidification and thus accelerated drying, the energy required and to be used, such as gas or electricity consumption, can be reduced and more process reliability can be achieved with less energy consumption.

By supplying heat through the paint hose, chemical processes run faster, as a result of which drying and/or curing of the coating or paint system applied to the object can be accelerated thermally and activated in a targeted manner.

The coating of an object by spraying the moisture-curing paint system using the atomizing air or the atomizing gas inside a painting booth ensures that the object to be coated is protected from external influences such as dirt, heat and moisture inside a painting booth or similar and a process-reliable application of the moisture-curing paint system can be guaranteed.

After a drying time, the object is removed from the paint booth at a drying time, with the occurrence of a superficially dust-dry state and therefore a manageable state of the paint system occurring from the drying time. From this point on, the moisture-curing paint system is no longer susceptible to external influences such as dirt, heat or moisture in the way it was when it was applied inside the paint booth. The coated object can therefore now be exposed to external influences without affecting the coating result. This means that the paint booth can continue to be used to coat another object with a moisture-curing paint system.

The paint system can dry and/or further harden outside of the paint booth by irradiating the object with at least one infrared radiator for a curing time up to a curing time. The effect of the radiation from the infrared radiator promotes the hardening process of the paint system. Because the infrared radiator is used outside the paint booth, the safety requirements, such as occupational safety, fire protection and/or explosion protection, can be guaranteed inside the paint booth and the use of cost-intensive systems that could be operated inside the paint booth can be avoided.

By using the infrared heater on an object that is already superficially dust-dry it is possible to ensure more process reliability with reduced energy consumption.

While the paint system is curing outside of the paint booth, the paint booth can be used to coat another object. Furthermore, when using gas-catalytic or electric infrared radiators, the radiation energy released can be specifically absorbed by the paint system and the coated object can be spared from this through the targeted use of their radiation frequency.

A finalization step outside of the paint booth, in particular the post-treatment of the painted object surface, ensures a final state of the paint system, in particular for a desired shine through polishing or preferably a surface seal. This can be used to upgrade the optical quality of the paint system and make it more resistant to external influences such as dirt or mechanical influences.

Provision is also made for at least one additive to be added to the atomizer compressed air or the atomizer gas, in particular to be supplied in a dosed manner. Additives can be specially tailored to the paint system used and the given environmental conditions, such as humidity or temperature, and thus enable targeted drying and curing of the paint system, in particular to optimize the drying time.

In addition, it is provided that the supply of heat to a paint hose carrying the atomizing compressed air or the atomizing gas should be distributed along at least 50% of the hose length, preferably along at least 70% of the hose length, in particular along at least 90% of the total hose length. The uniform heating of the painting hose ensures that the temperature of the atomizing compressed air or the atomizing gas remains the same and cooling through unheated areas of the painting hose can be avoided. In particular, this ensures controlled humidification of the atomizer compressed air or the atomizer gas, since condensation is avoided.

Furthermore, it is provided that the infrared radiator is moved past the object during the irradiation and/or that the object is moved past the infrared radiator during the irradiation, in particular that the infrared radiator and the object are moved during the irradiation in such a way that they are moved relative to one another. This ensures that the coated object is evenly irradiated, which can help ensure that the paint system dries and hardens evenly. In the case of smaller touch-ups or the painting of small areas, such as spot repair work or individual small parts, the infrared heater and the object can also be stationary during the irradiation.

It is also provided that the hardening time in method step e) is less than 10 minutes, preferably between 30 seconds and 5 minutes, in particular between 1 minute and 2 minutes. A short curing time reduces the duration of exposure of the paint system to external influences in a state of high vulnerability to them. A higher quality of the coating, in particular of the paint system, can thus be achieved through a shortened curing time. Thus, a significant shortening of the entire process can be achieved and an increase in capacity can be achieved.

Furthermore, it is provided that the drying time in method steps a) to e) is between 1 minute and 60 minutes, in particular between 10 minutes and 40 minutes, preferably between 15 minutes and 25 minutes, particularly preferably between 15 minutes and 20 minutes. A short drying time enables the paint system to be post-treated in a timely manner. This ensures time savings in the entire painting process up to the completion of the object to be coated.

It is also provided that the drying and/or curing in method step e) is carried out in a non-ATEX area (no explosion protection regulations). This enables the process to be used more flexibly and saves costs when installing the system. It can also be used in one place for several paint booths. The clear coat hardens outside the booth.

Furthermore, it is provided that the painting booth is again loaded with a new object for painting during the curing time in method step e). This increases the utilization rate of the paint booth and more objects can be painted in less time.

Furthermore, it is provided that the at least one infrared emitter is operated with reduced energy in order to obtain more process reliability with less energy consumption.

The invention also provides a system for painting objects using a method of the type and embodiments described above, the system comprising a plurality of painting booths and/or painting workstations and/or other surface processing workstations, these booths or workstations being in a closed room , have to work in particular under defined atmospheric conditions, and where the system comprises at least one drying and/or hardening station, and the drying and/or hardening station comprises at least one infrared radiator, and the drying and/or hardening station outside the cabins or workstations, is arranged in a free atmosphere, with at least one cabin and/or workstations being assigned to a drying and/or hardening station in the process. The drying and/or hardening station is therefore available for more than one cabin and/or workstations and can therefore be used with a higher degree of utilization. This enables time and cost savings when coating objects.

Furthermore, it is provided that the system comprises displaceable and/or fixed drying and/or hardening stations with at least one infrared portal and/or at least one infrared arc and/or at least one mobile infrared dryer. By using several infrared heaters, a larger area can be irradiated and a more homogeneous irradiation can be made possible. The use of different infrared heaters enables flexible use on objects of different shapes. This increases the quality of drying and/or curing and allows different objects to be processed.

For the purposes of the invention, the moisture-curing paint systems described, such as those based on aspartan technology, also include other paint systems based on 2K. In particular, the paint systems based on isocyanate, as well as other moisture-reacting or moisture-curing paint systems are meant. In other words, this means: all paint systems that contain an isocyanate-based hardener or other additives that react in the same way are also possible here, i.e. clear paint systems, but also normal ones Industrial paint systems, such as colored paints and also paint systems in the automotive and aerospace sectors and all other paint systems.

For the purposes of the invention, post-treatment of the paint system is to be understood as meaning polishing of the painted object surface and/or assembly of the painted object and/or packaging of the painted object.

Further details of the invention are described in the drawing with reference to exemplary embodiments shown schematically.

Figur 1

eine schematische Darstellung des erfindungsgemäßen Verfahrens anhand einer erfindungsgemäßen Anlage.

This shows:

figure 1

a schematic representation of the method according to the invention using a system according to the invention.

figure 1 shows the method according to the invention for coating objects by applying, drying, curing and after-treating moisture-curing paint systems on the object, using a system for painting objects according to the invention shown schematically.

The system includes a plurality of painting booths and/or painting workstations and/or other surface processing stations, such as large-part painting booths 1, workstations for individual parts and/or repairs 2 and workstations for preparation and/or touch-up coatings 3, or the like. Here an object is painted by spraying the moisture-curing paint system by means of the atomizer compressed air or the atomizer gas inside a paint booth. These cabins 1 or jobs 2.3 work in a closed room, especially under defined atmospheric conditions. Here, an atomizer compressed air or an atomizer gas is humidified. An admixture, in particular a dosed addition of at least one additive, is also provided, as a result of which the curing process can be influenced precisely. The atomizing compressed air or the atomizing gas is heated by a paint hose carrying the atomizing compressed air or the atomizing gas in order to promote drying and/or curing. This also prevents condensation. It is also provided that X times more of these large-scale painting booths 1, these jobs for individual parts and/or repairs 2, jobs for preparation and/or touch-up paint jobs 3, or the like can be present.

The object is then removed from the painting booth 1 or the workplace 2, 3 after a hardening time t1 at a drying time, with the occurrence of a superficially dust-dry state and thus a manageable state of the paint system from the drying time. The advantage here is that the drying and/or further curing does not take place inside the paint booth and this can be used directly for coating another object. This increases the utilization rate of the paint booth. The hardening time is less than 10 minutes, it is preferably between 30 seconds and 5 minutes, in particular between 1 minute and 2 minutes. Another advantage of drying and/or further curing outside the booth is that this means that smaller booths can be used, it can be used with systems that cannot be retrofitted and a better surface of the object to be painted is made possible due to less dust.

The paint system is dried and/or further cured outside of the paint booth in an infrared drying system 4, for example by an infrared portal 5, an infrared arc 6, or a mobile infrared dryer 7, for example an electric and/or gas-catalytic dryer Infrared dryer 7. Due to its open environment, this can be designed as a non-ATEX area, which results in a significant cost reduction.

Another advantage is that one infrared station can be used for several painting booths, which enables a considerable reduction in costs.

It is also provided that the at least one infrared radiator 7 is moved past the object and/or that the object is moved past the infrared radiator 5.6, in particular that the infrared radiator and the object are moved in such a way that they are relatively be moved to each other. A homogeneous drying and/or curing is relevant for a high quality of the coating, which can be generated by moving the infrared emitters. The drying time in this process step is between 1 minute and 60 minutes, in particular between 1 minute and 40 minutes, preferably between 15 minutes and 25 minutes, particularly preferably between 1 minute and 20 minutes. It also envisages installing fixed systems and building them outside the cabin for multiple uses.

The system includes at least one drying and/or curing station, such as an infrared drying system 4. The system can include several painting stations. The drying and/or curing station comprises at least one infrared radiator, for example infrared portals 5, infrared arcs 6, mobile infrared dryers 7 or the like. Important is moreover that the drying and/or hardening station is arranged outside the cabins or workstations, in an open atmosphere, with at least one cabin 1 and/or workstations 2,3 being assigned to a single drying and/or hardening station in the process.

After the paint system has dried and/or cured outside of the paint booth by irradiation in the infrared drying system 4, the paint system can be treated outside of the paint booth in a finalization step, in particular by means of polishing and/or finalization 8 of the painted object surface, or processed further how to be assembled or packaged.

The main advantage is that this can be done within a few minutes, so that the entire drying process can take place in the shortest possible time and with the least possible loss of time.

It is particularly advantageous that this system with infrared drying outside the paint booth can also be installed for existing paint systems outside the paint booth, for example at existing pre-work places or post-work places in the non-ATEX area. Especially if the existing paint booth would be too small for this.

Reference list:

1

Large part paint booth

2

Workplace for individual parts and/or repairs

3

Workplace for preparation and/or blending

4

Infrared drying system

5

Infrared Portal

6

infrared arc

7

mobile infrared dryer

8th

Polishing and/or Finishing

Claims (16)

1. Method for coating objects by applying, drying, curing and finishing of moisture-curing paint systems to the object, comprising the following steps:

   a) humidifying compressed atomizer air or an atomizer gas;

   b) supplying heat to the compressed atomizer air or the atomizer gas;

   c) painting the object by spraying the moisture-curing paint system by means of the humidified compressed atomizer air or the atomizer gas within a painting booth;

   d) removing the object from the painting booth at a point in time of drying, wherein, from the point in time of drying, a state of the paint system in which the surface is dust dry, and thus in which it can be handled, arises;

   e) curing and/or further curing of the paint system outside the painting booth by irradiating the object by means of at least one infrared radiator for a curing time until at a point in time of curing.
2. Method according to Claim 1, wherein, after the curing and/or further curing operation according to method step e), the paint system is finished outside the painting booth in a finalizing step, in particular by means of polishing the painted surface of the object.
3. Method according to either of the preceding claims, characterized in that the supply of heat in method step b) to the compressed atomizer air or the atomizer gas is effected by a paint hose that conducts the compressed atomizer air or the atomizer gas.
4. Method according to one of the preceding claims, characterized in that at least one additive is admixed with, in particular supplied in metered fashion to, the compressed atomizer air or the atomizer gas.
5. Method according to one of the preceding claims, characterized in that at least one additive is admixed with, in particular supplied in metered fashion to, the paint system.
6. Method according to one of the preceding claims, characterized in that the supply of heat to a paint hose that conducts the compressed atomizer air or the atomizer gas is effected along at least 50% of the hose length, preferably along at least 70% of the hose length, in particular along at least 90% of the hose length.
7. Method according to one of the preceding claims, characterized in that the infrared radiator is moved past the component and/or in that the component is moved past the infrared radiator, in particular in that the infrared radiator and the component are moved in such a way that they are moved relative to one another and/or have not been moved relative to one another.
8. Method according to one of the preceding claims, characterized in that the drying time in method step d) is between 1 minute and 60 minutes, in particular between 2 minutes and 40 minutes, preferably between 5 minutes and 25 minutes, particularly preferably between 5 minutes and 15 minutes.
9. Method according to one of the preceding claims, characterized in that the curing time in method step e) is less than 20 minutes, preferably less than 15 minutes and particularly less than 10 minutes and in particular less than 5 minutes.
10. Method according to one of the preceding claims, characterized in that the drying and/or curing in method step e) is carried out in a non-ATEX area, that is to say without explosion protection regulations.
11. Method according to one of the preceding claims, characterized in that, while a first object is drying, in method step e), the painting booth is reloaded with a new object for painting.
12. Installation for painting objects by means of a method according to one or more of the preceding claims, wherein the installation comprises at least one painting booth and/or at least one painting workstation and/or at least one other surface treatment station, wherein this booth or this workstation must operate in a closed space, in particular under defined atmospheric conditions, characterized in that the installation comprises at least one drying and/or curing station, and the drying and/or curing station comprises at least one or more infrared radiators, and the drying and/or curing station is arranged outside the painting booths or workstations, in a free atmosphere and/or in a non-ATEX area.
13. Installation for painting objects according to Claim 12, characterized in that at least one booth and/or workstations are assigned to one drying and/or curing station in the sequence.
14. Installation according to Claim 12, characterized in that the drying and/or curing station comprises at least one IR portal, and/or one IR arc and/or one mobile IR dryer and/or at least one fixedly installed infrared dryer.
15. Installation according to Claim 12, characterized in that at least 2 booths and/or workstations are assigned to one drying and/or curing station in the sequence.
16. Installation according to Claim 12, characterized in that the infrared drying installation arranged outside the one or more painting booths can also be used for other drying processes.

Images