EP2198975A1 - Curtain application unit - Google Patents

Abstract

The unit has an edge guide element (6) provided with a cover plate (7), a base plate (8) and separate chambers (9, 10) arranged on top of each other. The former chamber is located above the latter chamber. The former chamber is provided with a fluid or liquid inlet (11), and the latter chamber is provided with an outlet (12). A suction opening (17) is provided between a lower edge (16) of a wall (13) and a base plate (8). The wall has an outlet surface (19) for a fluid or liquid film (18) at a side pointed to curtain-edges. An independent claim is also included for a method for coating continuous paper and cardboard with liquid- and pasty coating medium.

Description

The invention relates to a curtain applicator for coating a running paper, cardboard or other fibrous web, comprising a disposed above the fibrous web and at least the width of the fibrous web corresponding curtain applicator for dispensing at least one liquid to pasty application medium in the form of a on or multi-layer curtain, which falls substantially to gravity following the fibrous web, wherein for guiding the curtain across its fall away, ie between a spoiler edge of the applicator head and the surface of the fibrous web is provided at its two edges depending an edge guide element, wherein the edge guide element in the width direction the curtain is adjustable.
The invention also relates to a process for curtain coating.

A generic device and a method is for example from the DE 197 35 588 known. In this document it is disclosed that for spreading the curtain at each edge a separate partial stream of coating color of the inner surface of an immediately adjacent to the outlet slit of the slot nozzle of the curtain guide element is supplied. Below the guide element, a separating element is still arranged, which separates the respective edge of the curtain and discharges to the outside.

Also an apparatus and a method are known from DE -A1 102 32 949 known. It has been proposed that, in a curtain application process, the curtain delivered by the curtain application unit is guided by edge guiding elements and corresponding emitted rays of an operating medium, as a lubricant for the curtain edges.

With the known curtain applicators several application media or multiple layers of a job medium deliverable. An embodiment of a curtain commissioned work is among others from the EP-A1- 1 255 615 known and is referred to in professional circles as "Slide Die", ie Gleitschichtdüse. This so-called Sliding layer nozzle contains at least two application medium chambers, from which the medium passes in each case via a feed gap, which in turn merges into a slot-shaped discharge nozzle, onto a sliding surface of the sliding layer nozzle. The application medium emerging from the discharge nozzles arranged in parallel one behind the other overlaps one another. At a trailing edge or as a detachment line to be designated edge of the nozzle, this multilayer separates and falls down as a multilayer curtain either initially on an intermediate guide plate or directly on the substrate to be coated or the surface of the moving fibrous web.

But there are also other versions of applicator heads are known in which one or more slot nozzles point down towards the underlying fibrous web. For this purpose, for example, on the DE-A1 10012344 for single-layer order and the DE-A1 10359117 directed for multi-layer order.

When painting - both single-layer and multi-layer application - with the Curtain Coater (curtain coater), the coating width can be equal to or less than the width of the fibrous web, which is referred to as "inboard" -Fahrweise.

In the case of the so-called "overboard" approach, on the other hand, the curtain width is greater than the width of the fibrous web.

In particular, in the inboard-driving edge management elements, as disclosed in the first two publications, necessary. These edge guide elements bring the curtain, which is about 200m long, close to the fibrous web.

In practice, columnar edge guide elements of porous material are currently used. The fluid or liquid or water serving as lubricant is still undefined in its quantity. The fluid or fluid used must run constantly, otherwise there is a risk of clogging. The required fluid or

The amount of liquid is thus enormously high and is about 10 to 15l / h

In addition, the structures of the edge guide elements (including the solutions shown in the cited documents) are complicated. They are subject to high wear and can also be poorly cleaned.

It is therefore an object of the invention to provide a device and a method in which the disadvantages of the prior art no longer occur.

The object of the invention is achieved with a curtain applicator with the features of claim 1.

According to the invention, the edge guide element has a cover plate and a bottom plate and consists of two superposed, separate chambers, each having a U-shaped cross section, wherein the first chamber is above the second chamber, the first chamber a fluid or Liquid inlet and the second chamber has a fluid or liquid drain and both chambers are closed at their respective edge of the curtain facing open side of the U-section with a continuous wall such that on the one between the cover plate and the upper edge of the wall in the first Chamber located overflow gap remains. It serves to produce a fluid or liquid film which contacts the respective curtain edge and thereby runs down a drainage surface of the wall. On the other hand, there is also between the lower edge of the outer wall and the bottom plate arranged in the lower, second chamber, central suction opening, which is in communication with the fluid or liquid drain.

The edge guide element according to the invention and thus also the curtain applicator are characterized by a simple construction. To guide the curtain only a small amount of fluid or liquid is needed. The unwanted color beads at the edges of the surface of the fibrous web are caused by the proper guidance of the curtain and without the curtain is constricted, avoided.

The edge guide element, in particular its drainage surface contacting the relevant curtain edge, can be easily cleaned due to its simple construction.

Simplified is the cleaning work, but also the drainage behavior, if the drainage surface made of stainless steel or aluminum. It is advantageous if this surface is polished or has a roughness value Ra of 0.8 to 1.0. However, the drainage surface may also be made of plastic, in particular Teflon, which shows a good flow behavior.

With regard to a variable amount of flow to be used for guiding or better lubricity of the Auftragmediumsvorhangs fluid or liquid film, it is advantageous if the located in the first chamber overflow gap and / or arranged in the lower, second chamber suction respectively adjusted in size to let.

It is advantageous if the suction opening is arranged centrally in the drain wall and parallel to the fluid or liquid withdrawal faces. The deduction of the fluid or liquid, which is associated with coating color particles and possibly abrasion particles, can be done without residue.

As fluid or liquid for the running fluid or liquid film preferably water is provided. Alternatively, however, it is also possible to use a water / coating mixture or, with regard to keeping the drainage surface clean, a mixture which contains surface-active substances, such as commercially available surfactants.

The suction opening for the discharged fluid or liquid is about 1 x 5mm in size. This suction opening can be incorporated both vertically and horizontally in the drain wall. Conceivable, however, would be other opening geometries, for example, circular openings. Alternately, in the bottom plate, a lateral slot for a suction or in addition still a paragraph be incorporated.

The said overflow gap in the upper chamber is about 10 to 20 mm wide.

It is also advantageous if the bottom plate of the edge guide element is formed obliquely, so that the slope is adapted to the course of a likewise obliquely running fibrous web. It is conceivable that the bottom plate can be adjusted at a desired angle. This gives you the opportunity to use the edge guiding element, which is supposed to be very close to the fibrous web running underneath, both for horizontal, as well as obliquely in upwardly or downwardly running fibrous webs. Conceivable, of course, are also made on stock edge guide elements with differently shaped or slanted at different angles floor panels.

The object of the invention is also achieved by a method according to claim 11. The method is used to coat a running paper, board or other fibrous web during its coating within a manufacturing or finishing process of the fibrous web with at least one liquid to pasty application medium, which in the form of a single or multilayer curtain, which is substantially gravity following freely falling from the top of the fibrous web is applied. In this case, the curtain is guided over its fall path between a tear-off edge and the surface of the fibrous web, in each case at its lateral edge, each with an edge guide element. The width of the curtain can be adjusted by shifting the edge guide element in the transverse direction.

It is preferably provided that a curtain width is set which is smaller than the width of the fibrous web. As a result, the curtain coating is operated in so-called "inboard" mode of operation, which allows for a better-than-previously-executed curtain and, at the same time, increases the quality of the order. whereby the printing properties of the paper or cardboard produced, for example, increase.

It is provided according to the invention that a fluid or a liquid is supplied to the edge guide element for guiding the curtain. This supplied fluid is guided in the first chamber of the edge guide element upwards and passed through a narrow overflow gap. Thereafter, the fluid or the liquid flows down over a drain surface of the edge guide element and from there to the outside.

On the drainage surface, a thin fluid or liquid film is formed with the help of the narrow overflow gap, thereby guiding the curtain edge very well. The dreaded color beads on the fibrous web and thereby further contamination on web-leading components or wet web edges do not arise.

The economy of the method can be increased if the drained via a drain liquid or the fluid or liquid film, fed to a separator and then fed by a vacuum pump in the circuit to the fluid or liquid feed of the edge guide element.

It is important that only about 2l / h of fluid or liquid film flow down the drainage surface of the edge guide element. This compared to the prior art very small amount is completely sufficient for the perfect guidance of the curtain in a surprising manner.

Moreover, the method can be made very effective if the amount of fluid film is controlled and / or regulated.

Figur 1:

ein erfindungsgemäßes Vorhang-Auftragwerk mit Randführungselementen in schematischer perspektivischer Darstellung

Figur 2:

einen Längsschnitt durch ein erfindungsgemäßes Randführungselement aus Figur 1, von der Seite ausgesehen,

Figur 3:

einen Längsschnitt durch ein erfindungsgemäßes Randführungselement aus Figur 1, von vorn gesehen,

Figur 4:

einen Querschnitt durch das Randführungselement gem. Figur 3,

Figur 5:

ein Flüssigkeitskreislauf-Schema für das Vorhang-Auftragswerk gem. Figur 1

The edge guide strips according to the invention can be easily retrofitted into existing curtain coating systems. In this case, the application of various embodiments of the curtain dispensing Curtain applicator head, such as sliding layer nozzle or slot nozzle as well as single-layered or multi-layered curtain possible.
The invention will be explained in more detail with reference to an embodiment. In a schematic representation:

FIG. 1:

an inventive curtain applicator with edge guide elements in a schematic perspective view

FIG. 2:

a longitudinal section through an inventive edge guide element FIG. 1 , viewed from the side,

FIG. 3:

a longitudinal section through an inventive edge guide element FIG. 1 , seen from the front,

FIG. 4:

a cross section through the edge guide element acc. FIG. 3 .

FIG. 5:

a liquid circulation scheme for the curtain applicator acc. FIG. 1

In the FIG. 1 is a curtain applicator 1 shown for coating a running paper, cardboard or other fibrous web 2 with a liquid to pasty application medium. It includes, in addition to some not shown here units, such as air boundary layer control devices, start-stop-Auffangeinrichtungen or tubs, measuring equipment, feed lines, etc. above the fibrous web 2 and spaced therefrom arranged and only slightly hinted curtain application head 3. This gun 3 may be formed as a so-called Gleitschichtdüse or slot nozzle and is machine width, so over the width of the fibrous web 2 reaching executed. The application head 3 can be designed both for a multi-layer application and for a single-layer application with which a single-layer or multi-layer curtain 4 can be produced. The curtain 4 drops from the tear-off edge 5 of the applicator head 3 substantially following the force of gravity down onto the fibrous web 2 and deposits on its surface as a coating layer AS.

How out FIG. 1 can be seen, the curtain applicator 1 has a lateral, columnar trained edge guide element 6 respectively on the leader side FS and Drive side TS on. This edge guide element 6 serves to guide and also limit the size of the approximately 200 mm long single-layer or multi-layer curtain 4 between the tear-off edge 6 and the surface of the fibrous web 2 at its lateral edges 4a and 4b.

The edge guide element 6 is adjustable in the width direction of the curtain 4, as the horizontal double arrows show. In the examples shown, the two edge guide elements 6 are within the width of the fibrous web 2, which is referred to as "inboard" -Fahrweise.

In FIG. 2 is the edge guide element 6 made FIG. 1 , seen from the side, shown in section. It can be seen that the edge guide element 6 has a cover plate 7 and a bottom plate 8. The edge guide element 6 consists of two superimposed, separate chambers 9 and 10, wherein the first chamber 9 is located above the second chamber 10.

In FIG. 3 It can be seen more clearly that the first, ie the upper chamber 9 has a fluid or liquid inlet 11 and the second, that is, the lower chamber 10 has a drain 12. Both nozzles or pipes for inlet 11 and outlet 12 point outwards. Both chambers 9 and 10 also have a wall 13 spanning them both. This wall 13 serves the actual guidance of the curtain and therefore contacted with their curtain side facing the respective curtain edge.

As in both FIGS. 2 and 3 to recognize, is the hollow edge guide element 6 and their chambers 9 and 10 are closed so that only between the cover plate 7 and the upper edge 14 of the wall 13, a located in the first chamber 9 overflow gap 15 remains. In addition, located between the lower edge 16 of the wall 13 and the bottom plate 8 so arranged in the lower, second chamber 10 suction opening 17. This suction is in communication with the drain 12. Due to the guided over the narrow overflow gap 15 fluid results in a very thin, but uniform fluid or liquid film 18, on the inside of the edge guide element 6 and better said flowing down on a run-off surface 19 of the wall 13 and the respective curtain edge, contacted and thereby leads, wherein the curtain 4 in the FIGS. 2 and 3 not shown with.

In FIG. 4 It is shown that the chambers 9 and 10 each have a U-shaped cross-section. It can also be seen that the wall 13 has been inserted with its drainage surface 18 in the open side of the U-section facing the curtain edge 4a bzw.4b.

The drainage surface 19 of the wall 13 consists in the example of stainless steel with a roughness value Ra = 0.8-1.0, which has a very positive effect on pollution of the drainage surface 19 and flow behavior of the film.

It should also be mentioned that the overflow gap 15 and / or the suction opening 17 are adjustable in size. The overflow gap is about 10 to 20mm wide. Equally wide is the drainage surface 19 and the wall 13.

In the example, the suction opening 17 is aligned dare and rectangular. It has a size of 1 x 5mm. In addition, this opening 17 is located directly above the bottom plate and is arranged centrally in the wall 13 parallel to the drain 12.

Both chambers 9 and 10 of the edge guide element 6 are otherwise separated from each other by a transverse wall 20.

As a fluid or liquid for the running fluid or liquid film 18, which is incidentally also controlled and regulated in its amount, water is preferably used. However, it is also a water / coating mixture or a mixture of water and surface-active substances, such as commercial surfactants used.

With the edge guide element 6 according to the invention a curtain width set, which is smaller than the width of the fibrous web 2.

In FIG. 5 a circuit diagram is shown. This illustrates that the liquid discharged via the outlet 12 of the edge guide element 6 or the fluid or liquid film 18 is sucked to the outside and is fed via a line 21 to a separator 22. The solid-particle-containing liquid is discharged via a drain 23, while the "clean" liquid is sucked out of the separator 22 by means of a vacuum pump 24. This liquid is available as a renewed liquid feed for the edge guide element 6. With a flow meter and control valve 25, the desired amount of fluid or liquid is fed via a line to the inlet 11 of the edge guide element.

LIST OF REFERENCE NUMBERS

1

Curtain applicator

2

Fibrous web

3

Curtain applicator head

4

curtain

4a, 4b

lateral curtain edge

5

tear-off edge

6

Edge guide element

7

cover plate

8th

baseplate

9

first chamber

10

second chamber

11

Fluid or liquid feed

12

procedure

13

wall

14

top edge

15

Overflow gap

16

lower edge

17

suction

18

Fluid or liquid film

19

drainage area

20

partition

21

management

22

separators

23

procedure

24

vacuum pump

25

control valve

L

longitudinal direction

M

application medium

FS

tender side

TS

drive side

Claims (15)

Curtain coater (1) for coating a running paper, board or other fibrous web (2), comprising a curtain applicator head (3) disposed above the fibrous web (2) and at least the width of the fibrous web (2) for dispensing at least a liquid to pasty application medium (M) in the form of a single- or multi-layer curtain (4), which falls substantially to gravity following the fibrous web (2), wherein for guiding the curtain (4) across its fall away, ie between a Tear-off edge (5) of the application head (3) and the surface of the fibrous web (2) at its two edges (4a, 4b) per an edge guide element (6) is provided, wherein the edge guide element (6), if desired in the width direction of the curtain (4) adjustable is
characterized in that
the edge guide element (6) has a cover plate (7) and a bottom plate (8) and consists of two separate chambers (9, 10) arranged one above the other, the first chamber (9) being located above the second chamber (10) first chamber (9) has a fluid or liquid inlet (11) and the second chamber (10) has a drain (12) and both chambers (9, 10) are closed with a wall (13) such that only between cover plate ( 7) and upper edge (14) of the wall (13) to the first chamber (9) belonging overflow gap (15) for generating a fluid or liquid film (18) and between the lower edge (16) of the wall (13) and the bottom plate (8) a suction opening (17) arranged in the lower, second chamber (10) remains and the wall (13) at its side facing the respective curtain edge (4a, 4b) has a drainage surface (19) for the fluid or liquid film (FIG. 18). Curtain coater according to claim 1,
characterized in that
the first chamber (9) and the second chamber (10) each have a U-shaped Cross-section, wherein in the open side of the U-shaped cross section, the wall (13) is embedded. Curtain coater according to claim 1 or 2,
characterized in that
the first chamber (9) and the second chamber (10) are separated from each other by a transverse wall (20). Curtain coater according to one of claims 1 or 2,
characterized in that
the drainage surface (19) of the wall (13) is polished and made of a material such as stainless steel or aluminum or a plastic such as Teflon. Curtain coater according to claim 4,
characterized in that
the drainage surface (19) has a roughness Ra of approximately 0.8 to 1.0. Curtain coater according to one of claims 1 to 5,
characterized in that
the overflow gap (15) and / or the suction opening (17) are adjustable in size. Curtain coater according to one of claims 1 to 6,
characterized in that
the suction opening (17) is located centrally in the wall (13) and immediately above the bottom plate (8). Curtain coater according to one of claims 1 to 7,
characterized in that
as fluid or liquid for the running fluid or liquid film (18) preferably water, but also a water / coating mixture or a mixture of water and surface-active substances, such as commercial Surfactants, are usable. Curtain coater according to one of the preceding claims,
characterized in that
the suction opening (17) is about 1 x 5mm in size and is incorporated vertically or horizontally in the wall (13). Curtain coater according to one of the preceding claims,
characterized in that
the overflow gap (15) and the drainage surface (19) are 10 to 20mm wide. Process for coating a running paper, board or other fibrous web (2) during its coating within a manufacturing or finishing process of the fibrous web (2) with at least one liquid to pasty application medium, which in the form of a single or multilayer curtain (4 ), which is applied substantially free falling from above on the fibrous web (2) following the gravity, wherein the curtain (4) across its fall path between a trailing edge (5) and the surface of the fibrous web (2) each at its lateral Edge (4a, 4b) is guided with one edge guide element (6), wherein the width of the curtain (4) is adjusted by displacement of the edge guide element (6) in the transverse direction,
characterized in that
for guiding the curtain (4) to the edge guide element (6) a fluid or liquid is supplied, which is a fluid or liquid film (18) forming a discharge surface (19) of the edge guide element (6) passed and then discharged. Method according to claim 11,
characterized in that
the liquid or liquid or the fluid or liquid film (18) discharged via a fluid or liquid outlet (12) is sucked off Separator (22) is supplied and then withdrawn by means of a vacuum pump (24) and, if desired, the fluid or liquid inlet (11) of the edge guide element (6) is fed again. Method according to claim 11 or 12,
characterized in that
the fluid or liquid film (18) flows down the run-off surface (19) of the edge guide element (6) in an amount of approximately 2 l / h. Method according to one of claims 11 to 13,
characterized in that
the amount of fluid or liquid film (18) is controlled and / or regulated. Method according to one of claims 11 to 14,
characterized in that
a curtain width is set which is smaller than the width of the fibrous web (2).

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