EP2409781B1 - Curtain coating apparatus - Google Patents

Description

The invention relates to a curtain applicator for coating a by a machine for producing and / or processing moving paper, cardboard or other fibrous web with at least one liquid to pasty application medium, comprising a above the fibrous web arranged machine-width curtain application head with a coating medium distribution chamber and an outlet opening for discharging the at least one application medium in the form of a single-layer or multi-layer curtain falling substantially downwards onto the fibrous web, and comprising at least one gutter located at least below the edge of the fibrous web for collecting application medium or over the edge of the fibrous web Sharing (MS) of it.

A generic curtain applicator (Curtain Coater) is for example from the DE-A1 10012344 for a single-level order or the DE-A1 103 59 117 known for multi-layer order. In these commissioned work, the applicator heads have slit nozzles which point down towards the fibrous web to be coated and from which the curtain falls predominantly under the influence of gravity. In addition to gutters or trays for collecting application medium, which falls over the edge of the web are also catcher devices for the startup process and the termination of the coating process, as well as air boundary layer control devices available. From the EP-A1- 1 255 615 Another embodiment of the curtain applicator is known, which is referred to in professional circles as "Slide Die", ie sliding layer or cascade nozzle. This commissioned work 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 outlet opening, onto a sliding surface of the nozzle. The application medium emerging from the outlet openings arranged parallel to one another in succession overlaps one another. At a trailing edge or as a detachment line to be designated edge of the nozzle, this multi-layer dissolves and falls down as a multilayer curtain either initially on one intermediate guide plate or directly to the substrate to be coated or the surface of the moving fibrous web.

The aforementioned containment and air boundary layer control devices are also present here.

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 driving.

• Beschädigung der Walzen von nachfolgenden Kalandern,
• ungleichmäßige Ränder und dadurch Ungleichmäßigkeit an der aufgewickelten Faserstoffbahnrolle
• starke Verschmutzung von nachfolgenden Leitwalzen, weil sich die Verdickungen nicht wegtrocknen lassen.

In contrast, with so-called overboard driving, the curtain width is greater than the fibrous web width. In particular, in this driving style and especially at today's high machine speeds, which are greater than 1000m / min, it may be due to Randabspritzungen to contamination of the fibrous web with very great impairment of the order quality and also to contamination of the fibrous web leading components, in turn affect the running fibrous web and therefore need to be cleaned consuming at short intervals. In addition, it comes to color overshoots. Generally, the thickness of the curtain coated coating layers is between 5 and 50 microns. It can lead to edge thickening reaching a height of up to 100 microns or higher. These local inequalities lead to various other problems, such as:

• Damaging the rolls of subsequent calenders,
• uneven edges and thereby unevenness on the wound fibrous web roll
• Heavy contamination of subsequent guide rollers because the thickening can not be dried.

It is therefore an object of the invention to provide a curtain applicator, in which the disadvantages of the prior art do not occur.

The object of the invention is with a curtain applicator with the features of claim 1. According to the invention it is provided that each collecting channel is assigned a collecting plate, wherein the collecting plate is acted upon by a cooling fluid. The cooling fluid is colder than the ambient temperature to maintain the surface temperature of the collection plate below the temperature of the environment. Preferably, the cooling medium should flow through the collecting plate.

Because of this design, it is possible that the falling or undesirably spray-off application medium parts first create the cooled collecting plate and get into the collecting channel from there. As a result of the cooling, condensation liquid forms on the surface of the collecting plate, so that the application medium or the paint splashes do not dry there. From the substantially vertical or inclined walls of the catch plate slip off the splashes and fall into the underlying gutter. Here they are collected and deducted in a simple manner.

For cooling the collecting plate, this is preferably hollow and filled with the cooling fluid, for example water, oil, alcohol or special mixtures. Also conceivable are cooling channels incorporated in the collecting plate, through which the selected cooling fluid flows.

If desired, the drip pan can be cooled.

An expedient embodiment of the commissioned work is that the collecting plate with its top to the fibrous web has a gap or distance of 0 to 20mm, preferably 3 to 5 mm. With its underside, however, the catch plate protrudes at least partially into the gutter. Although said gap or distance is desirable so that the high-speed fibrous web (which are speeds of greater than about 1500 m / min) can not affect the catch plate and thus is not damaged or even torn off. For slow running or even narrow webs, a distance of 0 mm, ie a direct contact to the fibrous web can be accepted.

Through this narrow gap fly the spray or paint mist. Therefore, it is expedient if a blowing nozzle is still arranged, which is acted upon by a pressurized fluid, such as compressed air or a liquid. With the tuyere these particles are directed downwards into the gutter predominantly contactless, which is why they can not fly around and cause impurities or quality impairments in the application layer.

It should be said at this point that the gutter can have any cross-section, which may for example be cone-shaped or extended like a trough. The term gutter is not restrictive, but stands for any cross-sectional shapes. This gutter can be acted as the collecting plate with a cooling fluid.

The gutter can be arranged as a separate component. However, a design in which the collecting plate is an integral part of the gutter assigned to it is simpler to interchangeably or expandable and removable. The catch plate is not machine-width and is located only on at least one edge of the application zone, whereas the gutter can also be machine-wide.

In connection with the said distance of the collecting plate to the fibrous web, it should be noted that the abovementioned smaller dimension must be selected if no tuyere is present.

It is further provided that the collecting plate downstream of the curtain applicator head or a line of impact of the curtain on the fibrous web at a distance between 40 and 100.mm downstream.

However, this distance should not be greater than 500 mm, because otherwise the splashes or particles of the application medium at unwanted sites but create and dry.

Moreover, it is advantageous if the collecting plate to the fibrous web at an angle between 5 ° and 90 °, but preferably 5 ° and 40 °. Due to the inclination, the medium parts to be collected can be better absorbed by the collecting surface.

It should be added that the tuyere preferably has a slot-like outlet opening and thus produces a flat jet. This forms a relatively sharply limited Blasstrahls, which is directed to the edge of the fibrous web, which splashes and paint mist are discharged from the curtain edge in the direction of the gutter.

Incidentally, it is provided that the tuyere is set against the fibrous web in such a way that its blowing jet also acts on the rear side of the collecting plate facing away from the curtain.

This ensures that the delivered curtain can fall unaffected by the blow jet, so neither tears nor constricted. The known from the prior art means for guiding the edges of the curtain and also arranged in front of the curtain air boundary layer control means are of course applicable to the curtain applicator according to the invention.

It is advantageous if the collecting plate and the blowing nozzle are arranged under an existing start / stop channel. This prevents soiling of the tuyere and the cooled catcher plate when starting or interrupting the coating process.

This collector plate can be easily installed in existing coating machines. Preferably, the catcher is suitable for newly designed, but also existing curtain applicators.

The collecting plate can be assigned to both an edge side, as well as at both web edges, so leader and drive side. The two-sided arrangement is preferred because the Abspritzungen the application medium or paint mist equally occur on both sides of today often with more than 1500m / min quickly through the manufacturing or finishing machine fibrous web and therefore should be collected there.

Figur 1:

ein erfindungsgemäßes in der Seitenansicht schematisch dargestelltes Vorhang-Auftragwerk;

Figur 2:

das erfindungsgemäße Vorhangauftragswerk gemäß Figur 1 in schematischer, perspektivischer Darstellung;

Figur 3:

das erfindungsgemäße Vorhangauftragswerk gemäß Figur 1 in Maschinenlängsrichtung dargestellt;

The invention will be explained in more detail with reference to an embodiment. In a schematic representation:

FIG. 1 :

an inventive curtain in the side view schematically illustrated applicator;

FIG. 2:

the curtain applicator according to the invention according to FIG. 1 in a schematic, perspective view;

FIG. 3 :

the curtain applicator according to the invention according to FIG. 1 shown in the machine longitudinal direction;

It should be noted that in the examples according to the FIGS. 1 to 3 only a single-layer order is shown. But it could also be a multi-layered curtain delivered or a multiple-application layer can be generated.

In the figures, the same components or designations are provided with the same reference numerals.

In the Figures 2 and 3 only one half of the width of the commissioned work and the fibrous web is shown, the second half is identical.

In the FIG. 1 is a curtain applicator 1 for coating a running paper, cardboard or other fibrous web 2 with a liquid to pasty application medium M shown. It includes, in addition to some other units not shown here, such as start / stop gutters, air boundary layer control equipment, Measuring devices, feed lines, etc. one above the fibrous web 2 and spaced therefrom arranged curtain application head. 3

This application head 3 is provided with a slot nozzle directed toward the substrate to be coated or the continuous fibrous web. The device is marketed by the applicant's company as DF Coater (Direct Fountain Coater) and is also machine-wide. The application head 3 has a Auftragmediumsverteilkammer 4 with feed gap, which merges into a slot-shaped outlet opening 5 with a trailing edge 6 and from which the application medium M in the form of a falling curtain 7 on the running in the direction of arrow L fibrous web 2 passes.

On the surface of the fibrous web 2, the curtain 7 sets as a coating layer AS.

How out FIG. 1 can be seen, the curtain applicator unit 1 at least one located below the edge 2a of the fibrous web 2 collecting channel 8 for collecting on the edge 2a of the fibrous web 2 exiting or squirting application medium M or parts thereof.

Thus, the leaking or ejecting media parts of the fibrous web 2 and / or the fibrous web leading rollers 9 and 10 or other components not shown here pollute, one of the gutter 8 associated, also arranged below the fibrous web 2 collecting plate 11 is provided. This collecting plate 11 is rectangular and hollow in the example. In the cavity, it is filled with a cooling fluid. Thus, a cooling of the same is achieved, which forms on the surface of the collecting plate 11 condensate. This has the consequence that the collected order medium or color splashes MS do not dry there, but slip down into the gutter located underneath 8. There they are collected and withdrawn. Incidentally, the collecting plate 11 is preferably arranged at an angle α between 5 ° and 40 ° with respect to the fibrous web 2.

This cooled collecting plate 11 is assigned in the example a tuyere 12, which directs the excess application medium parts or casters or paint mist MS to the collecting plate 11. The tuyere 12 is located above the edge 2a of the fibrous web 2 with an outflow direction on the region 2a of the fibrous web, up to said collecting plate 11. The tuyere is pressurized with compressed air and emits a blowing jet 12b. The blowing zone, which widened with increasing distance, is shown in dashed lines. The outlet opening of the blowing nozzle 12 is designed as a flat jet nozzle, so that the blowing jet 12b generates a flattened cross-section.

In FIG. 1 It can be seen clearly that the collecting plate 11 is located above its associated collecting channel 8, wherein the collecting plate 11 with its top 11a to the fibrous web 2 has a distance a of about 5 mm and protrudes with its bottom 11 b in the gutter 8.

The collecting plate 11 is arranged at a distance b in the downstream direction L of the fibrous web 2 after the curtain 7. The distance b extends from the extended line of the trailing edge 6 of the outlet opening 5 of the applicator head 3 to the front wall 11a of the erected collecting plate 11. This distance b is here about 70mm mm.

In the FIG. 1 one also sees that the blowing nozzle 12 is set against the fibrous web 2 in such a way that its blowing jet 12b acts down to the rear side 11d of the collecting plate 11 facing away from the curtain 7.

To avoid contamination of the tuyere 12 and the cooled collecting plate 11 at the start or interrupting the coating process, the collecting plate 11 and the tuyere should be located under an existing start / stop channel 17.

FIG. 2 is intended to show a possible embodiment in which the tuyere 12 is attached via a holder 13 to the collecting plate 11 and thereby jointly and expandable or at their distance b is adjustable to the curtain, as indicated by the double arrow. The holder has an incision or notch 13a for the fibrous web 2.

This embodiment is a simple retrofitted catcher 14, which is easily installed in existing production machines or coaters nightly.

The tuyere 12 has, moreover, in the FIG. 2 not visible slit-shaped outlet opening 12a, whereby one generates a sharply demarcated flat jet, which in turn generates a clean spatter-free edge 2a on the fibrous web 2.

Indicated in FIG. 2 is with arrows and the supply of the cooling fluid 15 for the collecting plate 11 and the supply of the blowing air 16 in the tuyere 12th

In FIG. 3 the lower part of the curtain applicator 1 is shown more clearly, wherein the web running direction is perpendicular to the image plane. It can be seen that the collecting plate 11, which is arranged at a distance from the fibrous web, for the most part projects even beyond the lateral edge 2a of the web. The blown with the nozzle 12 by Blasstrahl 12b medium generates a spatter-free edge, which is indicated in dashed lines. In addition, it can be seen that the collected at the edge of the medium from the gutter 8 is withdrawn via a drain 18, as shown by arrows. The collected medium can be disposed of or alternatively fed back to the media preparation.

LIST OF REFERENCE NUMBERS

1

Curtain applicator

2

Fibrous web

2a

Edge of the fibrous web

3

gun

4

Auftragsmediumsverteilkammer

5

outlet opening

6

tear-off edge

7

curtain

8th

collecting channel

9

roller

10

roller

11

collection plate

11a

top

11b

bottom

11c

front

11d

back

12

blow nozzle

12a

outlet opening

12b

blowing jet

13

bracket

13a

notch

14

catcher

15

cooling fluid

16

blowing air

17

start channel

18

procedure

α

angle

a

Gap or distance

b

distance

AS

application layer

L

Movement or running direction

M

application medium

MS

medium portion

Claims (13)

1. Curtain applicator unit (1) for coating a paper, cardboard or other fibrous web (2) which moves through a machine for producing and/or finishing with at least one liquid to pasty application medium (M), having a machine-width wide curtain applicator head (3) which is arranged above the fibrous web (2) with an application medium distribution chamber (4) and an outlet opening (5) for discharging the at least one application medium in the form of a single-layer or multiple-layer curtain (7) which falls onto the fibrous web (2) in a manner which substantially follows gravity, and having at least one collection groove (8) which is situated at least below the edge (2a) of the fibrous web (2) for collecting application medium which escapes beyond the edge (2a) of the fibrous web (2), or parts (MS) of the said application medium, characterized in that the collection groove (8) is assigned a collection plate (11) which is likewise situated below the fibrous web (2), the collection plate (11) being loaded with a cooling fluid (15).
2. Curtain applicator unit according to Claim 1, characterized in that the collection plate (11) is situated substantially only below the edge (2a) of the fibrous web (2).
3. Curtain applicator unit according to Claim 1 or 2, characterized in that the collection plate (11) is of hollow configuration and is filled with the cooling fluid (15).
4. Curtain applicator unit according to Claim 1 or 2, characterized in that the collection plate (11) contains channels, through which the cooling fluid (15) flows.
5. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) is arranged as a separate component or is an integral constituent part of the collection groove (8).
6. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) is assigned a blowing nozzle (12) which can be loaded with a pressure fluid and blows in the direction of the collection plate (11).
7. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) is situated above the collection groove (8) which is assigned to it, the collection plate (11) being at a spacing (a) with its upper side (11a) from the fibrous web (2) of from 0 to 20 mm, preferably of from 3 to 5 mm, and protrudes at least partially with its underside (11b) into the collection groove (8).
8. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) is arranged downstream of the curtain (7) or a curtain breakaway edge (6) at the outlet opening (5) of the applicator head (3) at a spacing (b) in the downstream direction of the fibrous web (2).
9. Curtain applicator unit according to Claim 8, characterized in that the spacing (b) is approximately from 40 to 100 mm.
10. Curtain applicator unit according to at least one of the preceding claims, characterized in that the blowing nozzle (12) has a preferably slot-shaped outflow cross section and, by way of this, generates a blown jet (12b) with a flattened cross section.
11. Curtain applicator unit according to Claim 10, characterized in that the blowing nozzle (12) is set against the fibrous web (2) in such a way that its blown jet (12b) acts as far as the rear side (11d) of the collection plate (11), which rear side (11d) faces away from the curtain (7).
12. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) and the blowing nozzle (12) are arranged under an existing start/stop groove (17).
13. Curtain applicator unit according to at least one of the preceding claims, characterized in that the collection plate (11) is arranged with respect to the fibrous web 2 at an angle α of between 5° and 90°, preferably of from 5° to 40°.

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