DE102006060397A1 - Fluid coating e.g. finish paint, applying device for surface of body of e.g. passenger car, has nozzle applying fluid on surface by air flow, and unit producing air flow, which deflects fluid between nozzle and surface - Google Patents

Abstract

The device (1) has a nozzle (2) and a surface that are moved relatively to each other, where the nozzle applies a fluid (3) on the surface by an air flow (5). A unit produces the air flow, which deflects the fluid between the nozzle and the surface. A collecting unit is provided for collecting the fluid, where the air flow deflects the fluid in the collecting unit. The nozzle distributes a coating composition perpendicular to an application direction over an application breadth. An independent claim is also included for a method for applying a fluid coating on a surface.

Description

The The invention relates to a method of making a removable one Surface protection through Application of a liquid, curable Coating composition (liquid film) on painted surfaces, where the liquid Coating composition through an application nozzle, via a predetermined, to be protected surface area relatively moved in one application direction and the liquid coating composition fed under pressure is, across the application direction over an application width spread on the surface is sprayed, the application by starting and stopping the delivery of coating composition to the application nozzle in coordination with their relative movement in the direction of application to the given surface area limited in application direction becomes. The movement of the application nozzle is referred to here as relative, because with stationary application nozzle also the surface to be coated can be moved.

Such a procedure is over DE 198 54 760 A1 which describes a method for producing a removable surface protection (liquid film) on a painted motor vehicle body. Here, a liquid is sprayed onto the painted body surface. This liquid solidifies into a peelable film. The liquid is applied via an application nozzle in the form of a fan nozzle in order to avoid so-called overspray and to achieve an edge-sharp application. The application nozzle is moved by a robot arm over the predetermined surface area to be protected in an application direction. The application is limited by starting and terminating the supply of coating composition to the application nozzle in coordination with their movement in the application direction to the given surface area in the application direction, so that only the predefined surface areas are coated.

One Disadvantage of the method described is the uneven layer thickness of the applied liquid film. Such is the layer thickness at the edges the applied fluid path higher than in the middle of the track. The width of the liquid path applied with a fan nozzle varies depending on from the material pressure under which the liquid discharged from the nozzle becomes. To use larger areas a closed liquid film to prove the discharged from the fan nozzle Liquid paths overlapping be applied. In this case, the layer thickness of the applied film in the overlapping areas additionally elevated.

Uneven layer thicknesses of the applied film to uneven drying behavior of the liquid film. In order to have a completely through-dried in all places of the coated surface It is necessary to obtain the drying conditions at the film largest occurring Orientate layer thickness. This leads either to high drying temperatures or for longer Drying times.

DE 10 2004 018 597 B3 describes the application of a liquid film along a web direction with an application head, which consists of a plurality of chambers, which are arranged one behind the other in the flow direction, and one or more in the application direction arranged behind one another rows of adjacent round jet nozzles has (multi-jet). The use of the multi-jet nozzle in the liquid film application has the following advantages: At the same time a large number of liquid beads are discharged side by side. These liquid beads flow into each other immediately after application and form a fluid path. The layer thicknesses of the caterpillars deposited within the liquid web and the caterpillars deposited at the edge of the liquid web are the same. Ie. the layer thickness of the liquid web thus applied is more uniform across the width of the web than when using a fan nozzle.

at Use of a multi-jet nozzle The width of the applied fluid path is less strong dependent on the material pressure than when using a fan nozzle. Therefore It is suitable for coating larger surfaces a closed film not necessarily overlapping the individual fluid paths apply. The layer thickness distribution is therefore more uniform than when using a fan nozzle.

One common disadvantage of both previously described methods is the following: Before starting the application process, the application nozzle is through a closed valve of the liquid coating composition afferent Line disconnected. In the line the material is already under for the application necessary pressure. The dead volumes of the nozzle are either not yet filled with material or at that time contain material that is under lower pressure than that for application selected Pressure is.

At the beginning of the application, the valve is opened. The liquid coating composition flows into the nozzle of the application head and there is an increase in the material pressure within the dead volume of the nozzle. Depending on the shape of the flow paths within the nozzle structure, this can lead to an abrupt increase in material pressure in the dead volume of the nozzle. Only in the course of Application adjusts itself under constant flow conditions a constant material pressure.

The At the beginning of the application occurring pressure surges could cause the material with undesirably high Speed discharged from the nozzle is injected back and after striking the surface to be coated.

The flying material droplets contaminate the vehicle surface outside of the given, to be protected Surface area, which should be coated. These impurities must be after the drying of the liquid film consuming manually be removed.

Furthermore Is it possible, that at Impact of the material on the surface to be coated air is included in the applied film, and film defects such as As foam and bubbles leads.

During the Application generates in the dead volume of the nozzle compared to the ambient pressure prevailing overpressure the flow of material through the outlet openings of the nozzle. there the material pressure remains constant in the dead volume of the nozzle.

The Speed of the nozzle discharged material is proportional to the beam direction in the dead volume of the nozzle prevailing material overpressure.

The Speed of the nozzle discharged material is in the application direction, d. H. parallel to the plane of the surface to be coated (horizontal), proportional to the movement speed of the robot arm, the application head with the nozzle over the to be coated surface leads.

At the At the end of the application, the valve, which is the material supply of the The dead volume of the nozzle separates, closed. Thereafter, the material pressure in the dead volume of the nozzle decreases conditionally through the still ongoing material discharge from the nozzle up on Ambient pressure.

The leads to, that the vertical speed of the material discharged from the nozzle is lower is as while the application. The material flies longer through the air until it on the surface to be coated incident. The horizontal speed of the discharged material but it is unchanged given by the feed speed of the robot arm.

Therefore At the end of the application, the material discharged from the nozzle continues to fly in the feed direction of the robot arm as during the application. The leads especially at high application speed, i. H. high feed rate of the robot arm, to contaminants over the given surface area out on surfaces, which should not be coated.

These Although impurities predominantly occur when using multi-jet nozzles, but are also due the use of fan nozzles not Completely to avoid.

The Removing these impurities can only be done by hand after drying liquid film done, and is therefore very expensive.

It The object of the present invention is to counteract impurities, those at the robot-assisted Application of liquid foil with spray nozzles different construction so far at the beginning and at the end of the application could not be avoided.

Furthermore should be a possibility be found, the advantages of the application of liquid film with the multi-jet nozzle to be able to use without at the same time one opposite the application with the fan nozzle increased effort for cleaning the coated car body shop to have to.

In addition, should the application speed, when using the multi-jet nozzle so far by limits the occurrence of contaminants at high speeds has been raised become.

to solution This object is achieved by the characterizing features of the claim 1 in conjunction with its generic term. Advantageous embodiments The invention are set forth in the subclaims.

According to the invention, it is provided that nozzle devices in the direction of application in front of and behind the application nozzle are designed to, when starting the application a gas stream spread over the application width, in application direction from behind under at an angle to the spray jet of the application nozzle, and when closing the application a gas flow distributed over the Application width, in application direction from the front under one Angles should be directed to the spray jet of the application nozzle, in each case overspray Overspraying coating composition over the given surface area counteract and the spray jet in the specified surface area to steer.

By a respective nozzle device in the application direction (= feed direction of Robo terarmes, if the relative movement is effected by) is arranged in front of and behind the application nozzle and at the beginning of the application in the feed direction and at the end of the application against the feed direction produces a, preferably laminar, gas flow, impurities can be avoided. It is advantageous if the gas flow generated by the nozzle device is directed at an angle of 25 to 35 degrees to the spray jet.

To the Time of switching (open or closed) of the valve in the material supply to the application nozzle becomes the respective nozzle device with compressed gas, z. B. compressed air, applied. The from the nozzle openings outflowing Air forms an "air curtain", which comes from the nozzle leaking fluid blows on the surface to be coated or already coated. At the start The application is after reaching a constant flow of material through the application nozzles the supply of compressed air to the rear nozzle device ends. At the End of application will be at a pre-determined time in Terms of closing of the valve in the material supply the compressed air supply to front nozzle device started.

It has also been surprising pointed out that many benefits can be achieved by the to be coated surface with water or an aqueous one solution one or more surface-active Treated substances and then the coating composition is applied. By treating the surface, such as a painted Vehicle body, more surface active with water or aqueous solutions Substances and application of the liquid film on the pretreated surfaces receives Already at lower layer thicknesses a closed course Web and a corresponding film than when applying the liquid film on dry surfaces. This reduces the material consumption per unit area and still a closed film is created. In addition, the material pressure can be reduced so far that the backsplash of the coating material can be avoided.

One significant advantage of this embodiment with pre-wetting Application procedure without pre-wetting is the material saving of 15 to 20% per unit area, which is achieved in the preferred method.

Though is the washing to be coated surfaces with water or aqueous Cleaning agents known as pretreatment before a coating. This removes impurities that affect the adhesion of the coating could interfere on the surface. The Water or the watery Cleaning agent is but before the application of the coating material from the surface Completely away.

• a) die Oberfläche zunächst mit Wasser oder einer wässrigen Lösung einer oder mehrerer grenzflächenaktiver Substanzen behandelt,
• b) eine Beschichtungszusammensetzung auf die behandelte Oberfläche mit dem erfindungsgemäßen Verfahren aufgebracht, bevor das Wasser vollständig von der behandelten Oberfläche abgetrocknet ist, und
• c) die Beschichtungszusammensetzung gehärtet, um eine gehärtete Beschichtung mit einer Schichtdicke von höchstens 200 µm zu bilden.

Accordingly, in the preferred embodiment, a method of making a removable surface protection

• a) first treating the surface with water or an aqueous solution of one or more surface-active substances,
• b) a coating composition is applied to the treated surface by the method of the invention before the water has completely dried from the treated surface, and
• c) the coating composition is cured to form a cured coating having a layer thickness of at most 200 μm.

In a further preferred embodiment becomes the surface in step a) with water, optionally by condensation on the surface from more supersaturated with water Air can be condensed. The pretreatment by condensation has the advantage that the generated water layer thicknesses evenly and are low. About that In addition, application technique for the spraying of Water be waived. In a further preferred embodiment the treatment with water or the aqueous solution is surface-active Substances on the surface by spraying.

In a further preferred embodiment is the temperature of the surface at step a) 1 ° C up to 50 ° C, preferably 5 ° C to 40 ° C, more preferably 10 ° C to 30 ° C, in particular 15 ° C to 25 ° C.

Of the Coating structure on the vehicle surface is preferably a typical car body painting, the z. B. from a cathodic dip painting, optional one Ink pen, a basecoat and in addition a Clearcoat as a topcoat. But it is also possible that in place of basecoat and transparent clearcoat a pigmented topcoat is used. The used as a final topcoat transparent or pigmented lacquer may be a lacquer based on z. B. a one- or two-component polyurethane system, or a Melamine resin / polyol system. The for the formulation of the topcoat used polyols can polyester, polyacrylate or polycarbonate polyols.

Preferably, the coating composition is applied less than 25 minutes after step a), more preferably 0.1 second to 25 minutes, especially 0.1 second to 15 minutes, such as 0.1 second to 10 minutes, or 1 second to 1 minute, for example 1 second to 45 seconds customer, or 1 second to 30 seconds after step a).

The Coating composition is preferably a water reducible Coating material based on z. B. polymer dispersions, in particular Polyurethane dispersions and particularly preferably dispersions of Polyester urethanes.

at the application of the coating composition is preferred a multi-jet nozzle with 1 to 6 rows of 5 to 500 nozzles each, more preferably 10 to 320 nozzles, especially 20 to 160 nozzles, like 40 to 80 nozzles used.

at preferred methods with pre-wetting can, in comparison with the Procedure without pre-wetting, higher viscous coating compositions are used. preferred viscosity ranges are from 5 to 40, preferably 10 to 35, in particular 15 to 30 Pa · s.

The Layer thickness of the cured Coating composition is preferably 40 to 170 μm, more preferably 50 to 160 μm, in particular 60 to 130 μm, for example 70 to 120 μm, as 80 to 110 microns or 90 to 100 μm.

The hardening in step c) can at elevated temperature take place, for example at 10 ° C. up to 90 ° C, preferably 15 ° C up to 80 ° C, especially 15 ° C up to 60 ° C, like 20 ° C up to 50 ° C.

The Invention will now be described with reference to exemplary embodiments in the drawings described in more detail, in which:

1 an application nozzle with attached nozzle devices in a side view (in the illustration above) and in plan view from below (in the illustration below), and

2 a side view of the assembly of application nozzle and nozzle devices with indicated spray jet and gas flows shows.

1 shows the application nozzle 2 , on each of whose sides a nozzle device 10 and 20 is mounted. The application nozzle 2 may have a closed at one end, in cross-section substantially rectangular tube; alternatively, the tube may also be open on both sides and provided with a coating composition port. On the underside of the tubular body are in a row along the longitudinal axis of the tubular body, a plurality of holes. The diameter of the holes can be up to 2 mm.

The nozzle device 10 ( 20 ) also has an elongated tubular hollow body having on its underside a fan nozzle in the form of an elongated slot 12 ( 22 ), which runs parallel to the application nozzle row. The nozzle devices 10 . 20 are each so to the application nozzle 2 Inclined, that slipped out of the slots 12 . 22 the nozzle devices 10 . 20 escaping gas streams to the emerging from the application nozzle spray jet 4 are inclined, this inclination angle is preferably in the range of 25 to 35 °.

The nozzle devices 10 . 20 are supplied with compressed air by supply lines (not shown), which are connected to the hollow body at both ends.

Alternative to the slots 12 . 22 For dispensing the gas streams, it is also possible to provide rows of individual nozzles instead of the slots on the nozzle devices, these nozzle rows then being approximately the same overall size and arrangement as the blower slots 12 . 22 to have. In the case of such a design of the nozzle device with a series of individual nozzles, it may be useful to select the diameter of the individual nozzles in the row from the ends with air supply starting to the center of the tubular body progressively smaller, so as to obtain a very la minaren air flow. Accordingly, it may be useful in training the nozzle devices 10 . 20 with continuous slots 12 . 22 to decrease the width of the slots from the air feed ends to the center of the pipe body of the nozzle device to obtain a laminar and homogeneous air flow.

2 shows schematically the arrangement of the application nozzle 2 with the nozzle devices mounted thereon 10 . 20 in lateral view. The application direction, ie the direction in which the application nozzle is moved over the surface to be coated, is indicated by the horizontal arrow. The spray jet of the application nozzle 2 is with 4 designated. At the beginning of the application, the nozzle device 20 supplied with compressed air, so that the dashed lines indicated air flow to the spray jet 4 the application nozzle 2 meets and this in the beam 4 ' distracting. Conversely, just before the end of the material discharge from the application nozzle 2 the nozzle device 10 actuated and generates a dashed line indicated air flow at the angle b to the spray jet 4 the application nozzle 2 is discharged and the spray jet 4 in the spray jet 4 '' deflects, so as to avoid overspraying at the end of the material application on the coating surface.

The control of the movement of the application nozzle 2 in application direction, the Beschich material supply to the application nozzle 2 and thus the control of the compressed air supply to the nozzle devices is coordinated by a programmed control device, in which control parameters on the coating material supply, compressed air supply to the nozzle devices and information about the to be coated, predetermined surface can be entered.

Examples preferred embodiments with Prewetting the paint surface are in the patent application entitled "Ver go to the application a liquid foil after aqueous Pretreatment of the surface to be coated "by the same applicant (Attorney docket: P 71242).

Claims (21)

A method of making a removable surface protection by applying a liquid, curable coating composition (liquid film) to painted surfaces wherein the liquid coating composition is pressurized through an application nozzle relatively moved over a predetermined surface area to be protected in an application direction and the liquid coating composition is distributed across the width of the application over an application width, is sprayed substantially perpendicular to the surface, wherein the application is limited by starting and stopping the supply of coating composition to the application nozzle in coordination with its relative movement in the application direction to the predetermined surface area in the application direction, characterized in that nozzle means ( 10 . 20 ) in the direction of application in front of and behind the application nozzle ( 2 ) are present and are prepared, when starting the application, a gas flow distributed over the application width, in the application direction from behind at an angle (c) on the spray jet of the application nozzle ( 2 ) and, when the application is ended, a gas flow distributed over the application width, in the direction of application from the front at an angle (b) to the spray jet of the application nozzle ( 2 ) in order to counteract any overspraying of coating composition beyond the given surface area. Method according to claim 1, characterized in that that the gas flow of the nozzle devices each at an angle (b, c) of 25 to 35 degrees from the Spray jet of the application nozzle is directed. Method according to one of the preceding claims, characterized in that the nozzle devices ( 10 . 20 ) are supplied with compressed air, so as to generate an air flow as a gas stream. Method according to claim 3, characterized in that the nozzle devices ( 10 . 20 ) are supplied with compressed air at an overpressure of 0.01 to 6 bar, preferably 2 bar to 4 bar. Method according to one of the preceding claims, characterized in that the nozzle devices ( 10 . 20 ) are designed to generate a laminar gas flow in the intended pressure range, with which the nozzle devices are acted upon. Method according to one of the preceding claims, characterized in that as a nozzle device ( 10 . 20 ) an elongate tubular body is used, which in addition to a gas supply connections an elongated, extending in the longitudinal direction of the tubular body slit-shaped nozzle outlet opening ( 12 . 22 ) for discharging the gas flow. Method according to one of claims 1 to 5, characterized that as a nozzle device respectively a longish one pipe body is used, in addition to a gas supply connection several, row-shaped in longitudinal direction of the tubular Body arranged individual nozzles which together output the gas flow. Method according to one of the preceding claims, characterized characterized in that a) the surface before applying the coating composition with water or an aqueous solution of a or more surface-active substances treated, b) then the coating composition with a method according to any one of the preceding claims the treated surface is applied before the water is completely dried off the treated surface is and c) the coating composition is cured, a hardened one Coating with a layer thickness of at most 200 microns to form. The method of claim 8, wherein the surface in step a) is treated with water. A method according to claim 8 or 9, wherein the water is condensed. A method according to claim 8, wherein the water or the watery solution surfactants Substances on the surface sprayed becomes. Method according to one of claims 8 to 11, characterized in that the temperature the surface at step a) is up to 50 ° C, for example 1 ° C to 50 ° C, preferably 5 ° C to 40 ° C, more preferably 10 ° C to 30 ° C, especially 15 ° C to 25 ° C. Method according to one of claims 8 to 12, characterized that the surface is a surface lacquered with topcoat of a motor vehicle. Method according to one of claims 8 to 13, characterized that step b) is carried out less than 25 minutes after step a), more preferably 0.1 second to 25 minutes, especially 0.1 seconds to 15 minutes, such as 0.1 second to 10 minutes, or 1 second to 1 minute, for example 1 second to 45 seconds, or 1 second to 30 seconds after step a). Method according to claim 13 or 14, characterized in that the topcoat is selected from topcoats Basis of a one- or two-component polyurethane system or a melamine resin / polyol system, with preferred polyols being polyester, Polyacrylate or polycarbonate polyols. Method according to one of claims 8 to 15, characterized the coating composition is selected from water-dilutable Coating materials based on, for example, polymer dispersions, in particular polyurethane dispersions and particularly preferably dispersions of polyester urethanes. Method according to one of claims 8 to 16, characterized the coating composition consists of a multijet nozzle with 1 to 6 rows of 5 to 500 nozzles each, more preferably 10 to 320 nozzles, especially 20 to 160 nozzles, like 40 to 80 nozzles, is applied. Method according to one of claims 8 to 17, characterized that the layer thickness of the hardened Coating 40 to 170 μm is, preferably 50 to 160 μm, more preferably 60 to 130 μm, in particular 70 to 120 μm, like 80 to 110 μm or 90 to 100 μm. Method according to one of claims 8 to 18, characterized that hardening in step c) at elevated Temperature takes place. Apparatus for carrying out a method according to one of the preceding claims. Apparatus according to claim 20, with an application nozzle ( 2 ), a robot adapted to move the application nozzle over a predetermined surface area to be protected in an application direction, to a feeder which supplies the liquid coating composition under pressure to the application nozzle, the application nozzle distributing the coating composition across the application direction across an application width , sprayed substantially perpendicular to the surface, wherein the controller of the robot is adapted to restrict the application by starting and stopping the supply of coating composition to the application nozzle in coordination with its movement in the application direction to the predetermined surface area in the application direction, nozzle devices ( 10 . 20 ) in the direction of application in front of and behind the application nozzle ( 2 ) and which are operated by the robot controller so that when starting the application a gas flow distributed over the application width, in the application direction from behind at an angle (c) on the spray jet of the application nozzle ( 2 ) and, when the application is terminated, directing a gas flow over the width of the application, in the direction of application from the front at an angle (b) to the spray jet of the application nozzle, in order to counteract any overspraying of coating composition beyond the given surface area.