EP0906789A1 - Process and apparatus for curtain coating of a travelling support - Google Patents

Process and apparatus for curtain coating of a travelling support Download PDF

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Publication number
EP0906789A1
EP0906789A1 EP97810732A EP97810732A EP0906789A1 EP 0906789 A1 EP0906789 A1 EP 0906789A1 EP 97810732 A EP97810732 A EP 97810732A EP 97810732 A EP97810732 A EP 97810732A EP 0906789 A1 EP0906789 A1 EP 0906789A1
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EP
European Patent Office
Prior art keywords
air
carrier
gap
curtain
cavity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97810732A
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German (de)
French (fr)
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EP0906789B1 (en
Inventor
Peter M. Schweizer
Urs Troller
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Vestincoat AG
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Troller Schweizer Engineering AG
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Publication date
Application filed by Troller Schweizer Engineering AG filed Critical Troller Schweizer Engineering AG
Priority to EP97810732A priority Critical patent/EP0906789B1/en
Priority to DE59704675T priority patent/DE59704675D1/en
Priority to US09/165,688 priority patent/US6162502A/en
Priority to JP10282504A priority patent/JPH11188298A/en
Publication of EP0906789A1 publication Critical patent/EP0906789A1/en
Application granted granted Critical
Publication of EP0906789B1 publication Critical patent/EP0906789B1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/30—Processes for applying liquids or other fluent materials performed by gravity only, i.e. flow coating
    • B05D1/305—Curtain coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C5/00—Apparatus in which liquid or other fluent material is projected, poured or allowed to flow on to the surface of the work
    • B05C5/005—Curtain coaters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C1/00—Photosensitive materials
    • G03C1/74—Applying photosensitive compositions to the base; Drying processes therefor

Definitions

  • the present invention relates to a method and a device according to the preamble of claim 1 or 3. It can be any coating material act.
  • the pour point denotes the place where the liquid to be poured for the first time with the carrier in Touch comes. With many coating processes, too when casting curtains, this place is designed as a line and is called the dynamic wetting line. The area near the carrier, in which the air is moving due to friction is called the boundary layer.
  • Watering means that the air on the carrier is To replace liquid. If that doesn't work out what to do can be the case especially at higher casting speeds, there is air between the carrier and the liquid film pulled, and then a coherent coating is no longer possible.
  • EP-B-0 489 978 is also a concentric around the Casting roller arranged shield used to To mechanically block the boundary layer. In addition, the Air flowing through the concentric gap in the Sucked off middle of the body.
  • the suction device is particularly not due to their slot-like design designed efficiently.
  • EP-B-0 489 978 there is also one relatively large chamber between the suction slot and concentric gap arranged. In this chamber the Air swirled strongly, so that the residual air with in the direction transverse to the carrier movement of non-uniform force on the Curtain hits, and therefore quality loss can cause.
  • the one placed in the middle of the body Extraction device also causes air from the room between body and curtain in the concentric gap is sucked against the carrier movement. This pull creates in front of the curtain and especially near the dynamic Wetting line an additional air flow that is transverse to the Carrier movement is non-uniform, and therefore one Quality loss on the coated film can cause.
  • the following description refers to a Consideration in the direction of the carrier movement, which is shown in FIG is indicated by an arrow U.
  • the inventive The device contains a body 1 which is in front of the curtain 2 is arranged concentrically around the casting roll 3, and thereby a uniform gap 4 between the carrier surface 5 and the body 1 from 0.1 to 1.0 mm, preferably 0.3 to 0.6 mm Height H forms.
  • suction channel Suction device There is a known one on the suction channel Suction device connected.
  • a first layer 8 of porous material is arranged in a first cavity 6, through which the air is drawn off.
  • the cavity remaining behind the porous layer helps to ensure that the air is sucked off efficiently and uniformly over the entire length L 2 and width of the porous layer.
  • the length L 2 is, for example, 15 mm.
  • a second cavity 9 which likewise has a layer 10 of porous material on the carrier side and is connected to an air supply duct 11, air not being drawn off through this second porous layer, but being fed in uniformly.
  • the air feed which is uniform across the carrier movement and has a length L 4 of, for example, 10 mm, is also brought about by the cavity located behind the porous layer.
  • the air supply duct is connected to an air supply device, not shown, so that the pressure and thus the volume flow of the air fed in can be set precisely.
  • the lengths L 1 and L 3 of the body before and after the first porous layer 8 are dimensioned such that a fully developed flow occurs in the concentric gap 4.
  • the minimum lengths for L 1 and L 3 depend primarily on the carrier speed and the gap width and are approximately 3 to 15 mm at a speed of 5 m / s and a gap height of 0.5 mm.
  • the layer thickness of the porous layers depends, among other things on the porosity and specific surface area of the porous medium.
  • the layer thickness must be dimensioned in this way be that the pressure drop in the air flow through the porous Layer essential, i.e. for example by a factor of 100, is greater than the pressure drop across the air flow Carrier movement in the channel behind the porous layer.
  • a porosity of 0.4 and a beam width of 1 m this results in a layer thickness of approx. 8 mm.
  • the distance d normalized with the gap height H is in FIG 3 as a function of the pressure difference ⁇ p and one receives the location of the zero speed.
  • the two volume flows are in Figure 4 as a function of Pressure difference ⁇ p shown.
  • the amount of air hitting the curtain and the amount of air that needs to be drawn off can be regulated as desired by setting the negative pressure p 0 .
  • it can be set as small as desired, thus minimizing the quality-reducing influences on the curtain. It is important that the amount of air that has to be extracted is not excessively extracted from the space between the curtain and body and thus causes disturbing air flows in front of the curtain, but that the amount of air is fed in in the correct amount through the porous layer at the outlet of the gap , in such a way that there are no disturbing air currents, both in front of the curtain and in the gap. Only the amount of air Q 1 flowing through the gap in the direction of the moving support and striking the curtain may be drawn out of the space between the curtain and the body.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
  • Curtains And Furnishings For Windows Or Doors (AREA)

Abstract

The air carried by the film is sucked-off in front of the coating medium curtain, and controlled air is constantly supplied. The air supply is set as a function of the removed air, so that a parabolic speed profile is developed, with a point at a distance to the film, in which the air speed is zero. The speed profile is calculated according to the Hagen- Poiseuille formula. The appliance body (1) has a first hollow chamber (6) with connected air extraction channel (7) and a second hollow chamber (9) with connected air supply channel (11). Both chambers extend across the full width of the film and have a porous material coating (8, 10) of the side of the film, so that an even concentric or parallel gap (4) between film (5) and body is formed.

Description

Die vorliegende Erfindung bezieht sich auf ein Verfahren und eine Vorrichtung nach dem Oberbegriff von Anspruch 1 oder 3. Dabei kann es sich um ein beliebiges Beschichtungsmaterial handeln.The present invention relates to a method and a device according to the preamble of claim 1 or 3. It can be any coating material act.

Bei allen Giessverfahren, speziell aber beim Vorhang-Giessverfahren, bereitet die Luft, die infolge Reibung vom unbegossenen Träger gegen den Giesspunkt geführt wird, Probleme. Der Giesspunkt bezeichnet denjenigen Ort, wo die zu begiessende Flüssigkeit erstmals mit dem Träger in Berührung kommt. Bei vielen Beschichtungsverfahren, so auch beim Vorhangguss, ist dieser Ort als Linie ausgebildet und wird als dynamische Benetzungslinie bezeichnet. Das Gebiet in Trägernähe, in dem die Luft infolge Reibung in Bewegung ist, wird als Grenzschicht bezeichnet.With all casting processes, but especially with the curtain casting process, prepares the air due to friction from the unguided carrier is guided against the pour point, Problems. The pour point denotes the place where the liquid to be poured for the first time with the carrier in Touch comes. With many coating processes, too when casting curtains, this place is designed as a line and is called the dynamic wetting line. The area near the carrier, in which the air is moving due to friction is called the boundary layer.

Beim Vorhangguss sind folgende Probleme im Zusammenhang mit der Luftgrenzschicht bekannt:The following problems are associated with curtain casting known to the air boundary layer:

Begiessen heisst, die Luft auf dem Träger durch eine Flüssigkeit zu ersetzen. Falls das nicht gelingt, was vor allem bei höheren Giessgeschwindigkeiten der Fall sein kann, wird Luft zwischen den Träger und den Flüssigkeitsfilm gezogen, und eine kohärente Beschichtung ist dann nicht mehr möglich.Watering means that the air on the carrier is To replace liquid. If that doesn't work out what to do can be the case especially at higher casting speeds, there is air between the carrier and the liquid film pulled, and then a coherent coating is no longer possible.

Auch wenn die Luft nicht zwischen den Träger und den Flüssigkeitsfilm eingezogen wird, trifft sie, in Bewegungsrichtung des Trägers gesehen, vor allem bei hohen Giessgeschwindigkeiten, mit erheblicher Kraft auf die Rückseite des Vorhangs auf. Dies führt, vor allem im Bereich der dynamischen Benetzungslinie, zu Störungen, welche sich als diffuse Ungleichförmigkeiten im beschichteten Film bemerkbar machen.Even if the air is not between the carrier and the Liquid film is drawn in, hits it in Seen the direction of movement of the wearer, especially at high Pouring speeds, with considerable force on the Back of the curtain. This leads, especially in the area the dynamic wetting line, to disturbances that arise as diffuse non-uniformities in the coated film to make noticable.

Die Luft, die durch den Träger gegen die Vorhangvorderseite geführt wird, muss irgendwie abgeführt werden. Und zwar seitlich, aufwärts, rückwärts, aber nicht in Richtung der Trägerbewegung. Diese Abführung der Luft bereitet vor allem bei breiten Trägern Schwierigkeiten, was dazu führt, dass der Vorhang in Richtung Trägerbewegung wie ein Ballon aufgeblasen wird. Dies bewirkt einerseits eine Deformation des Vorhangs, was eine Qualitätsverminderung des begossenen Films zur Folge haben kann, und andererseits eine Deformation der dynamischen Benetzungslinie. Dadurch wird das Giessverhalten des Vorhangs quer zur Giessrichtung ungleichförmig, was wiederum zu Qualitätseinbussen im beschichteten Film führen kann, z.B. in Form von Lufteinschlüssen in den Vorhangrandzonen.The air flowing through the carrier against the front of the curtain has to be led away somehow. In fact sideways, upwards, backwards, but not in the direction of Carrier motion. Above all, this removal of air prepares difficulties with wide straps, which leads to the fact that the curtain towards the carrier movement like a balloon is inflated. On the one hand, this causes a deformation of the curtain, which is a deterioration in the quality of the cast Films can result, and on the other hand one Deformation of the dynamic wetting line. This will the pouring behavior of the curtain across the pouring direction non-uniform, which in turn leads to loss of quality in the coated film, e.g. in the form of Air pockets in the curtain edge zones.

Es wurden verschiedene Verfahren und.Vorrichtungen entwickelt, um die oben beschriebenen nachteiligen Effekte zu beseitigen oder mindestens zu vermindern. Beim Verfahren und der Vorrichtung nach Oberbegriff der Ansprüche 1 und 3, gemäss US-A-5 624 715, wird die Grenzschicht einerseits durch einen Körper, der in Bewegungsrichtung des Trägers vor dem Vorhang konzentrisch und in kleinem Abstand gegen die Giesswalze angeordnet ist, gesperrt und andererseits wird die Luft, die durch den so entstehenden Spalt zwischen Körper und Träger strömt, durch eine Schlitzdüse abgesogen und es wird diesem Ort Luft kontrolliert zugeführt.Various methods and devices have been developed designed to have the adverse effects described above to eliminate or at least reduce. In the process and the device according to the preamble of claims 1 and 3, according to US-A-5 624 715, the boundary layer is on the one hand through a body facing in the direction of movement of the wearer the curtain concentric and close to the Casting roller is arranged, locked and on the other hand is the air passing through the gap between them Body and carrier flows, sucked through a slot nozzle and air is supplied to this place in a controlled manner.

In EP-B-0 489 978 wird ebenfalls ein konzentrisch um die Giesswalze angeordnetes Schild verwendet, um die Grenzschicht mechanisch zu sperren. Zusätzlich wird hier die Luft, die durch den konzentrischen Spalt fliesst, in der Mitte des Körpers abgesogen. In EP-B-0 489 978 is also a concentric around the Casting roller arranged shield used to To mechanically block the boundary layer. In addition, the Air flowing through the concentric gap in the Sucked off middle of the body.

Die Hauptwirkung beider oben beschriebenen Verfahren beruht auf der mechanischen Absperrung der Luftgrenzschicht. Obwohl bei beiden Vorrichtungen zusätzlich Luft abgesogen wird, trifft trotzdem noch eine beträchtliche Menge Luft auf die Rückseite des Vorhangs, so dass Qualitätseinbussen, wie sie oben beschrieben sind, immer noch auftreten können.The main effect of both methods described above is based on the mechanical barrier of the air boundary layer. Although air is additionally drawn off in both devices, still hits a significant amount of air on the Back of the curtain, so that quality loss like them described above can still occur.

Bei beiden Apparaturen ist insbesondere die Absaug-Vorrichtung infolge ihrer schlitzförmigen Ausführung nicht effizient gestaltet. In EP-B-0 489 978 ist zudem noch eine relativ grosse Kammer zwischen Saugschlitz und konzentrischem Spalt angeordnet. In dieser Kammer wird die Luft stark verwirbelt, so dass die Restluft mit in Richtung quer zur Trägerbewegung ungleichförmiger Kraft auf den Vorhang auftrifft, und deshalb Qualitätseinbussen verursachen kann. Die in der Mitte des Körpers angeordnete Absaug-Vorrichtung bewirkt zudem, dass Luft vom Raum zwischen Körper und Vorhang in den konzentrischen Spalt entgegen der Trägerbewegung gesogen wird. Dieser Sog erzeugt vor dem Vorhang und vor allem in der Nähe der dynamischen Benetzungslinie eine zusätzliche Luftströmung, die quer zur Trägerbewegung ungleichförmig ist, und deshalb eine Qualitätseinbusse auf dem beschichteten Film bewirken kann.In both devices, the suction device is particularly not due to their slot-like design designed efficiently. In EP-B-0 489 978 there is also one relatively large chamber between the suction slot and concentric gap arranged. In this chamber the Air swirled strongly, so that the residual air with in the direction transverse to the carrier movement of non-uniform force on the Curtain hits, and therefore quality loss can cause. The one placed in the middle of the body Extraction device also causes air from the room between body and curtain in the concentric gap is sucked against the carrier movement. This pull creates in front of the curtain and especially near the dynamic Wetting line an additional air flow that is transverse to the Carrier movement is non-uniform, and therefore one Quality loss on the coated film can cause.

Es ist von diesem Stand der Technik ausgehend Aufgabe der vorliegenden Erfindung ein Verfahren und eine Vorrichtung anzugeben, die eine verbesserte Gleichförmigkeit des beschichteten Filmes erzeugen. Diese Aufgabe wird mit dem Verfahren und der Vorrichtung gemäss den unabhängigen Ansprüchen gelöst. Weitere Verbesserungen und Vorteile ergeben sich aus den abhängigen Ansprüchen.Starting from this prior art, it is the task of present invention a method and an apparatus to indicate the improved uniformity of the generate coated film. This task is accomplished with the Method and device according to the independent Claims solved. Further improvements and advantages result from the dependent claims.

Die Erfindung wird im folgenden anhand einer Zeichnung eines Ausführungsbeispiels näher erläutert.

Figur 1
zeigt im Schnitt einen Teil der erfindungsgemässen Vorrichtung,
Figur 2
zeigt das Geschwindigkeitsprofil im Spalt,
Figur 3
zeigt den Ort der Nullgeschwindigkeit der Spaltströmung, und
Figur 4
zeigt die Volumenströme für die Spaltströmung.
The invention is explained below with reference to a drawing of an embodiment.
Figure 1
shows in section a part of the device according to the invention,
Figure 2
shows the speed profile in the gap,
Figure 3
shows the location of the zero velocity of the gap flow, and
Figure 4
shows the volume flows for the gap flow.

Die nachfolgende Beschreibung bezieht sich auf eine Betrachtung in Richtung der Trägerbewegung, die in Figur 1 mit einem Pfeil U angedeutet ist. Die erfindungsgemässe Vorrichtung enthält einen Körper 1, der vor dem Vorhang 2 konzentrisch um die Giesswalze 3 angeordnet ist, und dadurch einen gleichförmigen Spalt 4 zwischen der Trägeroberfläche 5 und dem Körper 1 von 0.1 - 1.0 mm, vorzugsweise 0.3 - 0.6 mm Höhe H bildet. In der ersten Hälfte des Körpers ist ein erster Hohlraum 6 angeordnet, der sich über die ganze Breite der Trägeroberfläche hinzieht und in einen Absaugkanal 7 mündet. Am Absaugkanal ist eine an sich bekannte Absaugeinrichtung angeschlossen.The following description refers to a Consideration in the direction of the carrier movement, which is shown in FIG is indicated by an arrow U. The inventive The device contains a body 1 which is in front of the curtain 2 is arranged concentrically around the casting roll 3, and thereby a uniform gap 4 between the carrier surface 5 and the body 1 from 0.1 to 1.0 mm, preferably 0.3 to 0.6 mm Height H forms. In the first half of the body is a arranged first cavity 6, which extends over the entire width of the carrier surface and into a suction channel 7 flows. There is a known one on the suction channel Suction device connected.

Trägerseitig ist in einem ersten Hohlraum 6 eine erste Schicht 8 aus porösem Material angeordnet, durch die hindurch die Luft abgesogen wird. Der hinter der porösen Schicht verbleibende Hohlraum hilft mit, dass die Luft auf der ganzen Länge L2 und Breite der porösen Schicht effizient und gleichförmig abgesogen wird. Die Länge L2 beträgt beispielsweise 15 mm.On the carrier side, a first layer 8 of porous material is arranged in a first cavity 6, through which the air is drawn off. The cavity remaining behind the porous layer helps to ensure that the air is sucked off efficiently and uniformly over the entire length L 2 and width of the porous layer. The length L 2 is, for example, 15 mm.

Im zweiten Abschnitt des Körpers befindet sich ein zweiter Hohlraum 9, der trägerseitig ebenfalls eine Schicht 10 aus porösem Material aufweist und an einen Luftzuführkanal 11 angeschlossen ist, wobei durch diese zweite poröse Schicht nicht Luft abgesogen, sondern gleichförmig eingespiesen wird. Die quer zur Trägerbewegung gleichförmige Luft-Einspeisung über die Länge L4 von beispielsweise 10 mm wird auch durch den sich hinter der porösen Schicht befindenden Hohlraum bewirkt. Der Luftzuführkanal ist mit einer nicht dargestellten Luftspeisevorrichtung verbunden, damit der Druck und dadurch der Volumenstrom der eingespiesenen Luft genau eingestellt werden kann.In the second section of the body there is a second cavity 9, which likewise has a layer 10 of porous material on the carrier side and is connected to an air supply duct 11, air not being drawn off through this second porous layer, but being fed in uniformly. The air feed, which is uniform across the carrier movement and has a length L 4 of, for example, 10 mm, is also brought about by the cavity located behind the porous layer. The air supply duct is connected to an air supply device, not shown, so that the pressure and thus the volume flow of the air fed in can be set precisely.

Die Längen L1 und L3 des Körpers vor und nach der ersten porösen Schicht 8 sind so dimensioniert, dass im konzentrischen Spalt 4 eine voll ausgebildete Strömung entsteht. Die Mindestlängen für L1 und L3 hängen vor allem von der Trägergeschwindigkeit und der Spaltbreite ab und betragen bei einer Geschwindigkeit von 5 m/s und einer Spalthöhe von 0.5 mm etwa 3 bis 15 mm.The lengths L 1 and L 3 of the body before and after the first porous layer 8 are dimensioned such that a fully developed flow occurs in the concentric gap 4. The minimum lengths for L 1 and L 3 depend primarily on the carrier speed and the gap width and are approximately 3 to 15 mm at a speed of 5 m / s and a gap height of 0.5 mm.

Die eingespiesene Luft bewirkt, dass sich im Spalt zwischen der ersten porösen Schicht und dem Spaltende gegen den Vorhang hin eine geregelte Luftströmung entwickelt, die durch ein parabolisches Geschwindigkeitsprofil derart gekennzeichnet ist, dass die Luft im oberen Teil des Spaltes entlang des Körpers vom Vorhang gegen die erste poröse Schicht und im unteren Teil des Spaltes entlang der Trägerbahn in Richtung Vorhang strömt, siehe Figur 2.The air fed in causes the gap between the first porous layer and the gap end against the Developed a regulated air flow towards the curtain through a parabolic velocity profile like this is marked that the air in the upper part of the gap along the body from the curtain against the first porous Layer and in the lower part of the gap along the Carrier web flows in the direction of the curtain, see Figure 2.

Die Schichtdicke der porösen Schichten hängt unter anderem von der Porosität und der spezifischen Oberfläche des porösen Mediums ab. Die Schichtdicke muss so dimensioniert sein, dass der Druckabfall der Luftströmung durch die poröse Schicht wesentlich, d.h. beispielsweise um einen Faktor 100, grösser ist als der Druckabfall der Luftströmung quer zur Trägerbewegung im Kanal hinter der porösen Schicht. Bei einer Porosität von 0,4 und einer Trägerbreite von 1 m ergibt sich eine Schichtdicke von ca. 8 mm.The layer thickness of the porous layers depends, among other things on the porosity and specific surface area of the porous medium. The layer thickness must be dimensioned in this way be that the pressure drop in the air flow through the porous Layer essential, i.e. for example by a factor of 100, is greater than the pressure drop across the air flow Carrier movement in the channel behind the porous layer. At a porosity of 0.4 and a beam width of 1 m this results in a layer thickness of approx. 8 mm.

Das Geschwindigkeitsprofil im konzentrischen Spalt zwischen den porösen Schichten, entlang L3, ist durch den Punkt P ausgezeichnet, der sich im Abstand d von der Trägeroberfläche befindet. Die Luftgeschwindigkeit im Punkt P ist null, d.h. der Punkt P trennt die Vorwärtsströmung, in Richtung Trägerbewegung, von der Rückwärtsströmung. Das Geschwindigkeitsprofil u(y) für eine so ausgebildete Strömung berechnet sich gemäss der Hagen-Poiseuille-Formel zu u(y) = (p 1-p 0)2µL y 2 - (p 1-p 0)H 2µL + U H y + U

u(y)
= Geschwindigkeit der Luft im Spalt
p1
= Umgebungsdruck hinter dem Vorhang
p0
= Unterdruck bei der Saugvorrichtung
Δp
= Druckdifferenz = (p1-p0)
µ
= Viskosität der Luft
L
= Länge des Spaltes
H
= Höhe des Spaltes
U
= Geschwindigkeit des Trägers
y
= Koordinate senkrecht zur Trägeroberfläche
The velocity profile in the concentric gap between the porous layers, along L 3 , is characterized by the point P, which is located at a distance d from the carrier surface. The air speed at point P is zero, ie point P separates the forward flow in the direction of the carrier movement from the backward flow. The velocity profile u (y) for such a flow is calculated according to the Hagen-Poiseuille formula u (y) = ( p 1 - p 0 ) 2µ L y 2nd - ( p 1 - p 0 ) H 2µ L + U H y + U
u (y)
= Speed of air in the gap
p 1
= Ambient pressure behind the curtain
p 0
= Vacuum at the suction device
Δp
= Pressure difference = (p 1 -p 0 )
µ
= Viscosity of the air
L
= Length of the gap
H
= Height of the gap
U
= Speed of the carrier
y
= Coordinate perpendicular to the support surface

Der Abstand d berechnet sich gemäss d = - a 2 - a 2 2 - b wobei a = - H + 2µLU ΔpH und b = 2µLU Δp The distance d is calculated according to d = - a 2nd - a 2nd 2nd - b in which a = - H + 2µ LU Δ pH and b = 2µ LU Δ p

Der mit der Spalthöhe H normalisierte Abstand d ist in Figur 3 als Funktion der Druckdifferenz Δp dargestellt und man erhält so den Ort der Null-Geschwindigkeit.The distance d normalized with the gap height H is in FIG 3 as a function of the pressure difference Δp and one receives the location of the zero speed.

Durch Integration des Geschwindigkeitsprofils über die Spalthöhe H erhält man den Luftvolumenstrom pro Spaltbreite Q1, welcher auf den Vorhang auftrifft, und den Luftvolumenstrom pro Spaltbreite Q2, welcher abgesogen werden muss: Q1 = Δp 2µL d 3 3 - ΔpH 2µL + U H d 2 2 + Ud Q2 = Δp 2µL H 3 3 - d 3 3 - ΔpH 2µL + U H H 2-d 2 2 + U(H-d) By integrating the speed profile over the gap height H, you get the air volume flow per gap width Q 1 , which strikes the curtain, and the air volume flow per gap width Q 2 , which has to be extracted: Q 1 = Δ p 2µ L d 3rd 3rd - Δ pH 2µ L + U H d 2nd 2nd + Ud Q 2nd = Δ p 2µ L H 3rd 3rd - d 3rd 3rd - Δ pH 2µ L + U H H 2nd - d 2nd 2nd + U ( Hd )

Die beiden Volumenströme sind in Figur 4 als Funktion der Druckdifferenz Δp dargestellt.The two volume flows are in Figure 4 as a function of Pressure difference Δp shown.

Für eine gegebene Spalthöhe kann die Luftmenge, die auf den Vorhang auftrifft und die Luftmenge, die entsprechend abgesogenwerden muss, durch Einstellen des Unterdruckes p0 beliebig geregelt werden. Insbesondere kann sie beliebig klein eingestellt werden, womit die qualitätsvermindernden Einflüsse auf den Vorhang minimiert werden. Wichtig ist dabei, dass die Luftmenge, die abgesaugt werden muss, nicht übermässig dem Raum zwischen Vorhang und Körper entzogen wird und dadurch störende Luftströmungen vor dem Vorhang bewirkt, sondern dass die Luftmenge durch die poröse Schicht am Austritt des Spaltes in der richtigen Menge eingespiesen wird, und zwar derart, dass keine störenden Luftströmungen, sowohl vor dem Vorhang als auch im Spalt entstehen. Dabei darf nur gerade die Luftmenge Q1, die durch den Spalt in Richtung des bewegten Trägers fliesst und auf den Vorhang auftrifft, aus dem Raum zwischen Vorhang und Körper abgesogen werden.For a given gap height, the amount of air hitting the curtain and the amount of air that needs to be drawn off can be regulated as desired by setting the negative pressure p 0 . In particular, it can be set as small as desired, thus minimizing the quality-reducing influences on the curtain. It is important that the amount of air that has to be extracted is not excessively extracted from the space between the curtain and body and thus causes disturbing air flows in front of the curtain, but that the amount of air is fed in in the correct amount through the porous layer at the outlet of the gap , in such a way that there are no disturbing air currents, both in front of the curtain and in the gap. Only the amount of air Q 1 flowing through the gap in the direction of the moving support and striking the curtain may be drawn out of the space between the curtain and the body.

Claims (6)

Verfahren zur Vorhangbeschichtung eines bewegten Trägers mit einem Beschichtungsmaterial, wobei in einem parallel, bzw. konzentrisch zum Träger ausgebildeten Spalt, in Laufrichtung des Trägers gesehen, die vom bewegten Träger mitgeführte Luft vor dem Vorhang abgesaugt wird und kontrolliert Luft stetig zugeführt wird, dadurch gekennzeichnet, dass die zugeführte Luft in Funktion der abgesaugten Luft derart eingestellt wird, dass sich ein parabolisches Geschwindigkeitsprofil entwickelt mit einem Punkt (P) in einem Abstand (d) vom Träger, in dem die Luftgeschwindigkeit gleich Null ist.Process for coating a moving curtain Carrier with a coating material, wherein in one gap formed parallel or concentric to the support, seen in the direction of travel of the carrier by the moving carrier entrained air is extracted in front of the curtain and controlled air is supplied continuously, thereby characterized that the air supplied as a function of extracted air is adjusted so that a parabolic speed profile developed with a Point (P) at a distance (d) from the carrier at which the Air speed is zero. Verfahren nach Anspruch 2, dadurch gekennzeichnet, dass das Geschwindigkeitsprofil gemäss der Hagen-PoiseuilleFormel (1) berechnet wird.A method according to claim 2, characterized in that the speed profile according to the Hagen-Poiseuille formula (1) is calculated. Vorrichtung zur Durchführung des Verfahrens nach Anspruch 1 mit einer Giesswalze (3) zur Führung eines Trägers (5) und einer in Bewegungsrichtung des Trägers vor dem Vorhang (2) angeordneten Absaug- (7) und LuftzuführEinrichtung (11), die an einem, einen Spalt (4) bildenden und parallel oder konzentrisch zum Träger angeordneten Körper (1) vorgesehen sind, dadurch gekennzeichnet, dass der Körper (1), in der Laufrichtung (U) des Trägers gesehen, einen mit anschliessendem Luftabsaugkanal (7) versehenen ersten Hohlraum (6) und vor dem Körper-Ende einen zweiten Hohlraum (9) mit sich daran anschliessendem Luftzuführkanal (11) aufweist, wobei sich beide Hohlräume (6, 9) über die ganze Breite des Trägers erstrecken und trägerseitig mit einer Schicht (8, 10) aus porösem Material versehen sind derart, dass sich ein gleichförmiger, konzentrischer oder parallele, Spalt (4) zwischen dem Träger (5) und dem Körper (1) erstreckt. Device for performing the method according to Claim 1 with a casting roller (3) for guiding a Carrier (5) and one in the direction of movement of the carrier the suction (7) and air supply device arranged on the curtain (2) (11) on one, forming a gap (4) and arranged parallel or concentric to the carrier Body (1) are provided, characterized in that the Body (1), seen in the direction of travel (U) of the wearer, one with a subsequent air extraction duct (7) first cavity (6) and a second in front of the body end Cavity (9) with adjoining air supply duct (11), both cavities (6, 9) over the extend the entire width of the carrier and with the carrier side a layer (8, 10) made of porous material such that a uniform, concentric or parallel, gap (4) between the carrier (5) and the body (1) extends. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, dass der erste Hohlraum (6) trägerseitig mit einer Schicht (8) aus porösem Material versehen ist.Device according to claim 3, characterized in that the first cavity (6) on the carrier side with a layer (8) is made of porous material. Vorrichtung nach Anspruch 3 oder 4, dadurch gekennzeichnet, dass die Höhe (H) des Spaltes 0.1 - 1.0 mm, insbesondere 0.3 - 0.6 mm beträgt.Device according to claim 3 or 4, characterized characterized that the height (H) of the gap 0.1 - 1.0 mm, in particular 0.3 - 0.6 mm. Vorrichtung nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, dass die Mindestlänge (L1)zwischen Körperanfang und Anfang des ersten Hohlraums (6) und (L3) zwischen Ende des ersten Hohlraums und Anfang des zweiten Hohlraums (9) 3 - 15 mm betragen.Device according to one of claims 3 to 5, characterized in that the minimum length (L 1 ) between the beginning of the body and the beginning of the first cavity (6) and (L 3 ) between the end of the first cavity and the beginning of the second cavity (9) 3-15 mm.
EP97810732A 1997-10-03 1997-10-03 Process and apparatus for curtain coating of a travelling support Expired - Lifetime EP0906789B1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP97810732A EP0906789B1 (en) 1997-10-03 1997-10-03 Process and apparatus for curtain coating of a travelling support
DE59704675T DE59704675D1 (en) 1997-10-03 1997-10-03 Method and device for curtain coating of a moving support
US09/165,688 US6162502A (en) 1997-10-03 1998-10-02 Method and device for curtain coating a moving support
JP10282504A JPH11188298A (en) 1997-10-03 1998-10-05 Method and device for subjecting mobile supporting body to curtain coating

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP97810732A EP0906789B1 (en) 1997-10-03 1997-10-03 Process and apparatus for curtain coating of a travelling support

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EP0906789A1 true EP0906789A1 (en) 1999-04-07
EP0906789B1 EP0906789B1 (en) 2001-09-19

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EP (1) EP0906789B1 (en)
JP (1) JPH11188298A (en)
DE (1) DE59704675D1 (en)

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WO2001091917A1 (en) 2000-06-02 2001-12-06 Mitsubishi Hitec Paper Flensburg Gmbh Method and device for curtain coating
WO2006056386A1 (en) 2004-11-22 2006-06-01 Basf Aktiengesellschaft Arrangement and method for curtain coating moving substrates
WO2006134052A1 (en) 2005-06-15 2006-12-21 Basf Aktiengesellschaft Curtain coater with boundary layer detachment device
WO2008000507A1 (en) * 2006-06-30 2008-01-03 Polytype Converting S.A. Curtain coating device with porous curtain guide structure, curtain guide structure for a curtain coating device, and method for producing the curtain guide structure

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Publication number Priority date Publication date Assignee Title
DE10117667A1 (en) * 2001-04-09 2002-10-10 Bachofen & Meier Ag Buelach Device for extracting an air boundary layer from a running material web
CA2469292C (en) * 2001-12-13 2011-06-07 Dow Global Technologies Inc. Method and apparatus for curtain coating
DE60209434T2 (en) 2002-12-12 2006-10-19 Metso Paper, Inc. Method and apparatus for curtain coating
DE602005017805D1 (en) * 2004-09-09 2009-12-31 Avery Dennison Corp CURTAIN COATING PROCESS
ATE430217T1 (en) * 2006-09-01 2009-05-15 Mitsubishi Hitec Paper Bielfel CURTAIN COATING METHOD AND DEVICE USED THEREFOR

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US4842900A (en) * 1986-02-12 1989-06-27 Fuji Photo Film Co., Ltd. Method and apparatus for coating
EP0440279A1 (en) * 1990-01-29 1991-08-07 Agfa-Gevaert N.V. Curtain coater for photographic elements
EP0489978A1 (en) * 1990-12-12 1992-06-17 Agfa-Gevaert N.V. Curtain coater
EP0704752A1 (en) * 1994-09-27 1996-04-03 Ilford Ag Curtain coating method and device for coating onto a running web

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US4842900A (en) * 1986-02-12 1989-06-27 Fuji Photo Film Co., Ltd. Method and apparatus for coating
EP0440279A1 (en) * 1990-01-29 1991-08-07 Agfa-Gevaert N.V. Curtain coater for photographic elements
EP0489978A1 (en) * 1990-12-12 1992-06-17 Agfa-Gevaert N.V. Curtain coater
EP0704752A1 (en) * 1994-09-27 1996-04-03 Ilford Ag Curtain coating method and device for coating onto a running web

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001091917A1 (en) 2000-06-02 2001-12-06 Mitsubishi Hitec Paper Flensburg Gmbh Method and device for curtain coating
WO2006056386A1 (en) 2004-11-22 2006-06-01 Basf Aktiengesellschaft Arrangement and method for curtain coating moving substrates
WO2006134052A1 (en) 2005-06-15 2006-12-21 Basf Aktiengesellschaft Curtain coater with boundary layer detachment device
WO2008000507A1 (en) * 2006-06-30 2008-01-03 Polytype Converting S.A. Curtain coating device with porous curtain guide structure, curtain guide structure for a curtain coating device, and method for producing the curtain guide structure

Also Published As

Publication number Publication date
DE59704675D1 (en) 2001-10-25
EP0906789B1 (en) 2001-09-19
JPH11188298A (en) 1999-07-13
US6162502A (en) 2000-12-19

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