EP2379807A1

EP2379807A1 - Method for the multiple coating of a fibrous web, in particular a movable cardboard web, and apparatus for treating and/or converting fibrous webs, in particular for the multiple-layer application of liquid or pasty application media

Info

Publication number: EP2379807A1
Application number: EP09768034A
Authority: EP
Inventors: Michael Trefz; Benjamin Mendez-Gallon; Stefan Reich
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2008-12-18
Filing date: 2009-12-07
Publication date: 2011-10-26
Also published as: WO2010069803A1; DE102008054908A1; CN102257217A

Abstract

The invention relates to a method for the multiple coating of a fibrous web (F), in which method a first application medium, in a following method step (B) at least one further application medium with a replenishing application device (17) and, in one of the further method steps (C, C1, C2), at least one further third application medium are applied by way of a curtain applicator (20). The invention is characterized in that starch is applied as first application medium. The apparatus (12) for treating and/or converting the surface of a fibrous web, in particular for the multiple-layer application of liquid or pasty application media onto a paper or cardboard web, comprises a first and second replenishing application device (13, 17) and a third application device (19) in the form of a curtain applicator (20), wherein each of the individual application devices (13, 17, 19) has a drying device (15, 18, 21) arranged behind it. The apparatus (12) is characterized in that the second application device (17) has a calendering device (16) arranged in front of it.

Description

Method for multiple coating of a fibrous web, in particular a movable board web and device for the treatment and / or

Finishing of fibrous webs, in particular for multilayered

Application of liquid or pasty application media

The invention relates to a method for multiple coating of a fibrous web, in particular a movable board web with liquid or pasty application media, wherein in a step, a first application medium for producing a first layer and in a subsequent process step at least one further application medium for generating at least one further layer with at least applied to a post-dosing applicator and applied in one of the further process steps, at least one further third application medium for generating at least one further third layer with a curtain applicator, wherein after each job, the fibrous web is dried.

The invention further relates to a device for the treatment and / or finishing of the surface of a fibrous web, in particular for the multi-layer application of liquid or pasty application media on a paper or board web, comprising a first application device for applying a first application medium, at least one postdosing applicator for applying a another second application medium in a further second layer and a further third application device for applying a third application medium in a third layer in the form of a curtain application device, wherein each of the individual application devices is arranged downstream of a drying device.

Fiber webs in the form of cardboard webs consist of several layers that are produced on waste paper basis. As a rule, these include at least three differently formed layers of waste paper, the top, which is also used for marking or as a visible side, is formed by a thin layer of waste paper. The middle layer consists of mixed waste paper of low quality and the back preferably again of waste paper with higher quality than the middle layer. To ensure the surface requirements at the top of such a board web is usually coated at least with two layers. In this case, the surface of the board web is impregnated with starch in a first process step, whereby it is solidified. This is followed by a first application in the form of a primer, which has the task of leveling out any existing unevenness in the surface topography and to fill the wells with coating color. The subsequent top coat has the task to coat the surface with a uniformly thick layer and to achieve a homogeneous coverage. For the top coat, in particular for metering, a so-called air knife is usually used. The coating medium is applied with excess and the excess is blown off with the help of a sharp jet of air and the coated surface is evened out. Since this very large amounts of air must be generated with high jet speeds, such a method is very energy intensive. Furthermore, by blowing away a paint mist that contaminates system parts in the vicinity of the coated cardboard web. The cleaning of the exhaust air from the paint mist is very expensive. In order to achieve a uniform bleeding of the application medium in such processes, also the usable solids contents limits are set, otherwise the fluidity is not given. Normally, application media with a solids content of 40 to 50% can be applied, so that in retrospect, a great deal of energy has to be used for the required drying.

A generic method for applying application medium to a movable fibrous web, in particular in the form of a paper or board web, is previously known from the document EP 1 516 960 A1, further the priority document DE 103 43 120 A1. In this process the individual layers are produced in succession by means of a film coater, a blade coater and another layer with a curtain applicator, the curtain applicator being downstream of the blade coater so as to increase the quality of the layer produced therewith by covering the doctor strips produced by the blade coater; so that they no longer have any influence on the fibrous web. Furthermore, with the blade coater, the layer thickness can be regulated very accurately and reliably, with the applied layer conforming to the contour of the underlying layer. However, it has been shown that a corresponding coverage depends very much on the roughness of the surface of the board web and, in the case of very high roughnesses, the multiple layers are not necessarily suitable for achieving complete coverage.

From the document DE 10 2005 021 983 A1 a process for coating a moving board web is known in which a liquid to pasty application medium is applied in a multi-layered manner to at least one of the surfaces of the board web, the strike weight of the pre-coat in the range between 10 to 100 g / m ² and the strike weight of the cover layer forming the cover layer is between 3 to 20 g / m ² . The precoat is applied with a single curtain applicator in several films or layers. Subsequently, the cover layer is produced, which can be applied to the precoat without or with intermediate drying. However, the cover layer is applied here by means of a postdosing device, so that first an excess is applied, which is then doctored off again or scraped off. The resulting disadvantages of the generated surface are characterized by an absence of uniformity and markings by the metering devices.

A further embodiment for coating a board web with at least two sequentially arranged application devices is previously known from DE 102 28 117 A1. In this will help prevent the irregularities Use of a post-dosing applicator proposed to use as an application device at least one contactless applicator, which is designed to deliver the application medium in at least one free Auftragmediumstrahl or Auftragmediumvorhang or Auftragmediumschleier or in Auftragmediensprühtropfen and on the web based on the application medium impressed forces and / or Motion impulses and / or applied on the basis of a gravitational movement of the application medium, wherein along the treatment path before and / or after the applicator a smoothing device is provided. The smoothing device produces a high degree of smoothness and possibly gloss of the surface on the coated side of the material web. It is thereby exploited that the layers which can be generated via the non-contacting metering application device can be set more accurately while at the same time providing a higher throughput of the coating device.

Japanese Patent Application No. 2006-166289 already discloses an application device and a process for the production of heat-sensitive paper, in which the application of a first layer on a web is carried out by means of a postdosing applicator, such as a squeegee device, and by means of a subsequent process Curtain applicator job of applying a cover layer in the form of a heat-sensitive layer with a prescribed residence time takes place. Subordinate to both processes is a dry process. In order to avoid bleeding between the lower layer and the outer layer, the coating color must have corresponding properties, since no separate drying between these two process steps is provided here.

The invention is therefore based on the object of further developing a method and an apparatus for treating and / or finishing a fibrous web, in particular a board web, in such a way that the stated disadvantages are avoided at simultaneous increase and improvement of the quality of a coating of a board web, even with very rough board web surfaces, off.

The solution according to the invention is characterized by the features of claims 1 and 19. Advantageous embodiments are described in the subclaims.

The method according to the invention for multiple coating of a fibrous web, in particular a movable board web with liquid or pasty application media, wherein in a method step a first application medium for producing a first layer and in a subsequent process step at least one further application medium for generating at least one further layer with at least one postdosing Applicator be applied and in one of the further process steps, at least one further third application medium for generating at least one further third layer is applied with a curtain applicator, wherein after each job, the fibrous web is dried, characterized in that as the first application medium thickness is applied.

Due to the application of starch as the first layer to the surface of the board web to be coated, the solution according to the invention makes possible a particularly advantageous solidification and leveling of the upper side as base area for the further layers to be applied.

Since drying is preferably arranged downstream of all individual application process steps, very high coating weights can be applied here, and there are no restrictions with regard to the viscosity of the application medium to be applied and the composition used. By using a curtain application device for the last layer to be applied in the form of a cover layer, on the one hand, a very homogeneous uniform cover layer is achieved, which ensures a very high surface quality even with very uneven priming. Due to the possibility of applying application media with a high solids content by means of the curtain application device, the drying performance for drying the cover layer can be considerably reduced.

Another significant advantage when applying by means of a curtain application device is that on the one hand, the application method is contactless, wherein the applied medium as a contour layer on the

Fibrous web stores and above all, that the specific volume of the carton is not changed. The coverage is almost completely within the scope of the selected coating width and there are different coating weights and application media even at higher throughput speeds than previously applicable. Furthermore, this makes the entire device easy to set up, since only so much medium is applied, as will remain on the board web. This is also called a 1: 1 order and takes place in

Contrary to the previous exclusively applied excess application method with the film press or a roller applicator or blade coater. A preparation of the excess medium can be omitted.

In a particularly advantageous manner, in order to improve the surface quality, the first layer, in particular the impregnation layer, is already subjected to smoothing, with values in the range from 5 to 7 μm Parker-Print-Surf being set.

The application medium for the second layer applied with the postdosing applicator is preferably applied at a coating weight in the range from 16 to 24 g / m ² . In an advantageous embodiment, to reduce the required drying capacity application media are applied with the curtain applicator, which are characterized by a solids content in the range of 60 to 65 percent by mass. The viscosity of the coating medium for the cover layer can be in the range from 400 to 1000 mPas, particularly preferably from 400 to 800 m Pas.

In a particularly advantageous further development, the cover layer is not applied by means of the curtain application device as a layer, but preferably at least as a two-layer cover layer. This offers the advantage that different partial layers can be produced with an application device within the cover layer, whereby these can differ with respect to their composition. In a particularly advantageous manner, the sub-layer forming the final upper side of the board web is formed with higher-value constituents than the lower sub-layer applied to the precoat. As a result, higher-quality application medium can be applied only in the areas where this is actually required. The other non-surface-relevant layer regions can be formed by application media of other, even inferior qualities.

For further surface refinement, in a particularly advantageous embodiment, following the production of the cover layer, a further smoothing process is provided, which adjusts the required smoothness.

The method according to the invention can be carried out with a device for coating cardboard webs, which can be arranged downstream of a machine for producing such fibrous webs, in particular board webs, online or offline. The online solution offers the advantage that processing takes place here immediately after production of the corresponding board web. Due to the application methods used are high Throughput speeds conceivable, so that there are no problems in terms of performance of the machine for the production of fibrous webs.

The device according to the invention for the treatment or refinement of the surface of a fibrous web, in particular a paper or board web, comprising a first metering applicator for applying a first

Application medium, at least one postdosing applicator for

Applying another second layer and another third

Applicator for applying a third layer in the form of a curtain applicator, each of the individual applicators is arranged downstream of a drying device is characterized in that after the first application means a smoothing device is arranged.

The additional smoothing process, the surface between the impregnating precoat and the other layers can be improved again and thus the order for the top layer, which due to a solid surface better bleeding and a very homogeneous job is already guaranteed during the application.

The solution according to the invention is explained below with reference to figures. It details the following:

FIG. 1 illustrates in an axial section the structure of a board web coated in accordance with the invention;

Figures 2a to 2d illustrate possible based on a signal flow diagram

Embodiment variants of a method for coating a movable paperboard web;

FIG. 3 illustrates in schematically simplified representation the FIG

Basic structure of a device according to the invention for coating a fibrous web, in particular a board web; FIG. 4 shows, in a schematically simplified illustration with reference to a view from the right, a particularly advantageous construction of a device according to the invention according to FIG. 3;

Figure 5 illustrates a particularly advantageous embodiment of the

Curtain applicator according to FIG. 4.

FIG. 1 shows, in a simplified schematized representation in an axial section, an inventive multi-coated, in particular coated, fibrous web F in the form of a multi-ply cardboard web 1 on an old paper basis. The axial section was laid through the YZ plane of a coordinate system assigned to the fibrous web F. The X direction corresponds to the length direction and the Y direction to the width direction of the fibrous web F. When passing through an apparatus for treating and / or finishing fibrous webs F, the X direction corresponds to the continuous or machine direction. The structure of such a board web 1 is exemplified by three different layers 2.1, 2.2 and 2.3 characterized, with the largest proportion in the middle, here the situation 2.2, consists of mixed waste paper of lesser quality. The upper side 3 is formed by the layer 2.1 and is denoted by 3, while the back 4 and underside of a waste paper predefined quality, preferably higher quality than the center layer 2.2 exists. Such a board web 1 with the individual layers 2.1 to 2.3 is coated with at least two layers 5 as a pre-layer and 6 as a cover layer on its upper side 3. The method for treating the fibrous web F, in particular multiple coating, is reproduced on the basis of a signal flow diagram in FIG. 2a. The construction of the layers according to FIG. 1 and the method in FIG. 2a are explained below in connection with them.

In a first method step, the top side 3 of the board web 1 according to the invention with a first application medium in the form of starch with a post-dosing Aufragseinrichtung, in particular glue or film press coated. This first layer 7 is shown in FIG. 1 on the upper side 3 formed by the layer 2.1. This serves to impregnate the surface of this upper side 3, whereby it is solidified. At least one further application medium with at least one postdosing application unit is applied to the pre-impregnated upper side 3 in method step B. With this layer 5 is applied in the form of a primer. The application device is preferably a squeegee or blade application device, with which the liquid or pasty application medium is applied with excess to the board web 1 and subsequently metered with a metering device. With such an application device, the liquid or pasty application medium is applied with a coating weight in the range between 16 and 24 g / m ² inclusive. In a further method step C, the layer 6 is applied in the form of the cover layer by means of a so-called curtain application device, in particular curtain coater. The coating weight of the covering layer-forming layer 6 is between 8 to 32 g / m ² , preferably 8 to 24 g / m ² , more preferably 8 to 16 g / m ² , most preferably 10 to 16 g / m ² . Between each of the individual application steps A to C, a drying step is provided following the application to dry the respective coating, in this case T1 after the application of the first layer 7, T2 acting as impregnation layer after application of the precursor-forming layer (s) 5, and T3 after application of the cover layer forming layers 6. The surface created by the first layer 7 is denoted by 8 and the surface after the top coat is denoted by 9.

With the method according to the invention, coatings of board webs 1, in particular board webs 1 with high surface roughness can be achieved, which are characterized in that they have a uniform thickness, the cover of the upper side 3 of the board web 1 is as homogeneous as possible. The advantage of producing the at least three layers is that on the one hand via the first layer 7, in particular starch impregnation layer, the surface 8 for the subsequently applied Layers 5 and 6 is prepared as much as possible, the application of the starch takes place with at least one film coater. The applicator used is characterized in that the order takes place in excess indirectly on the surface of a metering gap forming rolls or directly on the surface before passing through the fibrous web F through the press. As a result, the thickness of the impregnating layer can be regulated very precisely and the applicator 13 used is adapted to precisely adjust the layer 7 of the application medium to be applied to the contour of the underlying layer, in particular the upper side 3, of the board web 1, in which case also upper sides 3 of cardboard sheets 1 with high roughness can be coated very homogeneously. On the basis of the surface 8 thus present, the individual further layers, in particular at least 5 and 6, can be applied, wherein in order an application by means of a curtain application device 20 according to process step C on at least one order by means of a Nachdosierenden application device according to B, in particular one Doctor blade or bar or a blade applicator follows. As a result, irregularities generated by the elements used for replenishment, such as doctor blade, rod or blade, can be covered so that they no longer have any influence on the quality of the finished coated board web 1. By applying with a curtain applicator, the order quantity and thus the layer thickness can be regulated very accurately and reliably, since the layer 6 applied by means of this adjusts exactly to the contour of the underlying layer. The possibility of applying the cover layer by means of a curtain application device after the application of the layer 5 by means of a postdosing application device also improves the running properties for the board web 1, so that breaks can be considerably reduced. By the intermediate drying steps T1 to T3 or each of the individual orders of the layers downstream drying steps a simple guidance of the board web 1 is possible because facilities for non-contact deflection of the fibrous web F can be omitted. The method illustrated in FIG. 2a on the basis of a signal flow diagram represents a basic method which can be advantageously extended by further method steps. Thus, it is provided in a particularly advantageous embodiment according to FIG. 2 b, between the application of the layer 7 and the layer 5 after the first drying step T1, to provide a method step G1 which pre-smooths the layer 7 and the surface generated thereby to values in the range between 5 and 7 μm Parker print surf for the upper side 8 formed by this first layer 7. As a device, a calender can be used, preferably at least a two-roll calender. As a result, possibly further roughness can be eliminated and also unwanted air boundary layers on the surface 8 of the coated with the first layer 7 cardboard web 1 are excluded, so that the following layer is applied as homogeneously as possible free of air inclusions. The further method with the application of the layer 5 in method step B then follows the method step G1 in accordance with the explanations in FIG. 2a. With regard to the further method, reference is therefore made to FIG. 2a.

In a particularly advantageous further development of the embodiments according to FIGS. 2 a and 2 b, it is further provided according to FIG. 2 c to smooth the upper side or surface 9 resulting in the form of the cover layer after the applied third layer 6 likewise in a smoothing step G 3. This

Method step G3 is used to further optimize the surface of

Cardboard web 1 is provided. The smoothing step G3 follows the drying step T3.

In all embodiments according to FIGS. 2 a to 2 c, a coating of the back side 4 of the board web 1 can follow the completion of the top coat in the form of the layer 6. This can be realized differently and is shown by way of example in FIG. 2d. According to FIG. 2d, a starch impregnation in the form of a first layer 10 shown by means of a broken line in FIG Furthermore, a layer 11 can be applied, which is metered for example with a doctor blade. The application of the starch layer can already take place as A1 in FIG. 2d simultaneously with the application A of the starch layer onto the upper side 3 or alternatively as A1 following G3. The order of the layer 11 takes place in any case downstream of G3.

Also shown in FIG. 2d is the possibility of producing the cover layer from a plurality of partial layers through the individual jobs C1 and C2.

The method according to the invention according to FIGS. 2 a to 2 d can be executed with a device 12 exemplified in FIG. 3 for the treatment and / or refinement of a board web 1, in particular for the multilayer coating of a movable board web 1. The device 12 is in terms of their structure in a simplified schematic representation in Figure 3 by a first application device 13 for the postdosed order of application medium, in particular in the form of a film or size press, formed. This is followed by a first drying device 15, from which the board layer 1 provided with the first layer 7 is guided to a smoothing device 16, wherein the smoothing device 16 is followed by at least one further, second application device 17, which follows the application of the second layer 5 in the form of the precursor. The second application device serves for the subsequent metering application of the liquid or pasty application medium, in particular coating color. Downstream of this is a further drying device 18, from which the movable board web 1 is guided to at least one third application device 19 in the form of a curtain application device 20 and subsequently to a drying device 21 to which a further application device 22 for the coating of the back side 4 closes the cardboard web 1 at.

FIG. 4 illustrates a concrete embodiment of a device 12 for treating and / or finishing fibrous webs F, in particular for multiple coating of a movable board web 1 according to FIG first applicator 13 is formed in the illustrated case as a film press 14. This is characterized in that the application medium is introduced into the gap between two rollers forming a gap with one another and the application medium is metered in through the allocation of the rollers to the cardboard web 1 guided in the gap. The surface 3 on the layer 2.1 can be made very rough, since the coating medium 14, the application medium is homogeneously and in large thickness to cover the entire surface of the layer 2.1 can be applied. Following this, the first drying device 15 is arranged. The coated with the first applicator 13 top 3 of the layer 2.1 in the form of the surface 8 is here fed to a contact drying. For this purpose, the first drying device 15 consists of a plurality of drying cylinders, around the surface of which the fibrous web F with the coated surface 3 is guided meandering and is exposed to drying in cooperation with the surface of the individual drying cylinders. Downstream of the drying device 15 is the smoothing device 16, which is executed in the illustrated case in the simplest case as a two-roll calender, comprising two smoothing rollers 16.2 and 16.3 forming a smoothing gap 16.1 with each other. After passing through the smoothing device 16, the coated board web 1 is now guided to the other application device 17. This is a postdosing application device, in which the application medium is applied in an excess to the now to be coated surface 8 at the top 3 and then metered by a metering device 23 in the form of a doctor blade or a blade. The second applicator 17 downstream drying device 18 is preferably designed as air drying device 18.1, in particular hot air drying device or infrared drying device. In this, the movable board web 1 is guided along a drying unit and dried by preferably applied to the surface of hot air. Downstream of the drying device 18 is the further, third applicator 19 in the form of a curtain applicator 20. This in turn is subordinate to the further drying device 21, which a first air-drying device 21.1 and this downstream another Contact drying device 21.2 comprises, which is also characterized by an arrangement of individual drying cylinders, around which the cardboard web 1 is meandered with the now to be dried surface 9. The downstream application device 22 for the coating of the rear side 4 is preferably also a postdosing device in the form of a doctor applicator, by means of which the liquid or pasty application medium is applied to the back 4 or the already prepreg 4 with excess and through a metering device 24 is metered to the desired thickness.

FIG. 5 illustrates a particularly advantageous embodiment of a curtain application device 20 for producing the cover layer 6 from two layers 6.1 and 6.2 according to FIG. 2d, in which the application of the cover layer takes place in the form of the layer 6 in the process steps C1 and C2, which take place simultaneously. In this, the curtain application device 20 is characterized by an over the width of the applicator 19 extending nozzle 25, which has two immediately successively arranged exit column viewed in the direction of travel of the movable board web 1, which are designated here with 26.1 and 26.2, wherein the two metering a two-ply layer 6 in the form of layers 6.1 and 6.2 can be generated, which are generated as a common curtain falling on the surface 8. This has the advantage that in particular the second layer 6.2, which is applied as the uppermost layer of the cover layer 6, which is applied to the precursor-forming layer 5 and which is printed later, can be made with particularly high-quality and expensive components, including those in the lower layer lying layer 6.1 are not needed. As a result, a targeted surface improvement is possible.

The layer 6 is characterized according to the invention by a coating weight of 8 to 32 g / m ² , more preferably 8 and 24 g / m ² and most preferably 8 and 16 g / m ² . The solids content of the liquid or pasty application medium, in particular the color, is in the range between 60 to 70%, in particular mass percent. The order medium consists of about 80% mineral constituents, such as calcium carbonate, kaolin or mixtures of calcium carbonate and kaolin. Preferably, the application medium further contains a proportion of synthetic binders and starch for thickening. The viscosity of the coating medium is in the range between 400 and 1000 mPas, measured by the Brookfield method, very particularly preferably 400 and 800 mPas.

LIST OF REFERENCE NUMBERS

1 board web

2.1, 2.2, 2.3 location

3 surface

4 back side

5 layer, primer

6 layer, top coat

6.1, 6.2 partial layer

7 first layer, impregnation layer

8 surface

9 surface

10 first shift

11 shift

12 Apparatus for treating and / or refining a

Fiber web, in particular device for multiple coating

13 first application device

14 film press

15 first drying device

16 smoothness device

16.1 smoothing gap

16.2, 16.3 smoothing roll

17 second application device

18 drying device

18.1 impingement drying device,

Air drying device

19 third order device

20 curtain applicator

21 drying device

21.1 impingement drying device,

Air drying device 21.2 contact drying device

22 application device

23 metering device

24 Dosing device 25 nozzle

26.1, 26.2 exit slit, dosing gap

A process step, first order

B process step, second order

C process step, third job C1, C2 job steps for the third job

T1, T2, T3 process step drying

G1, G3 Smoothing process step

F fibrous web

Claims

claims

1. A process for the multiple coating of a fibrous web (F), in particular movable board web (1) with liquid or pasty application media, wherein in a process step (A) a first application medium for producing a first layer (7) and in a subsequent process step (B ) at least one further application medium for generating at least one further layer (5) with at least one postdosing applicator (17) are applied and in one of the further process steps (C, C1, C2) at least one further third application medium for producing at least one further third layer ( 6) is applied with a curtain application device (20), wherein after each application (A, B, C, C1, C2) the fibrous web (F) is dried (T1, T2, T3); characterized in that as the first application medium thickness is applied.

2. The method according to claim 1, characterized in that the fibrous web (F) after application (A) of the first application medium and the drying (T1) is smoothed (G1), preferably a smoothness in the range of 5 to 7 microns Parker Print surf is set.

3. The method according to any one of claims 1 or 2, characterized in that the starch is applied by means of a size press.

4. The method according to any one of claims 1 or 2, characterized in that the starch is applied by means of a film press (14).

5. The method according to any one of claims 1 to 4, characterized in that the with the post-dosing applicator (17) applied application medium is replenished by means of a metering device (23), in particular blade or squeegee.

6. The method according to any one of claims 1 to 5, characterized in that the with the postdosing applicator (17) applied application medium for the second layer (5) with a coating weight in the range of 16 to 24 g / m ^{2 is} applied.

7. The method according to any one of claims 1 to 6, characterized in that with the at least one curtain application device (20) applied application medium with a coating weight in the range between 8 and 32 g / m ² , preferably 8 and 24 g / m ² , especially preferably 8 and 16 g / m ² , very particularly preferably 8 to 16 g / m ^{2 is} applied.

8. The method according to any one of claims 1 to 7, characterized in that with the at least one curtain application device (20) applied application medium is applied with a solids content of 60 to 70 percent by mass.

9. The method according to any one of claims 1 to 8, characterized in that a application medium having the following composition is used as the application medium to be applied with the at least one curtain application device (20):

- about 80% of mineral constituents, in particular calcium carbonate and kaolin,

synthetic binder, in particular latex dispersion,

- Strength.

10. The method according to any one of claims 1 to 9, characterized in that as the at least one curtain application device (20) to be applied application medium, a coating medium having a viscosity in the range between 400 and 1000 mPas is used.

11. The method according to any one of claims 1 to 10, characterized in that the third layer (6) of at least two partial layers (6.1, 6.2) is produced with different components by means of a combined nozzle (25) with at least two connected in series Dosing (26.1, 26.2) are generated, which are applied as a common curtain on the surface of the moving fibrous web (F).

12. The method according to any one of claims 1 to 11, characterized in that the movable fibrous web (F) in the region of

Curtain applicator (20) is guided in a horizontal plane or at an angle to the horizontal plane of <10 °.

13. The method according to any one of claims 1 to 12, characterized in that the drying (T1, T2, T3) of the fibrous web (F) to the individual orders (A, B, C, C1, C2) by means of contact drying.

14. The method according to any one of claims 1 to 13, characterized in that the drying (T1, 12, T3) of the fibrous web (F) after the individual orders (A, B, C, C1, C2) by an impingement drying, in particular hot air drying or infrared drying takes place.

15. The method according to any one of claims 1 to 14, characterized in that the fibrous web (F) after application of the third layer (6) successively an impingement drying device (21.1) and a contact drying device (21.2) is supplied.

16. The method according to any one of claims 1 to 15, characterized in that after drying (T3) of the third layer (6) the fibrous web (F) is smoothed (G3).

17. The method according to any one of claims 1 to 16, characterized in that after generation of the third layer (6), the fibrous web (F) on the back (4) coated (D) is.

18. The method according to any one of claims 1 to 17, characterized in that simultaneously with the application of starch (A) on the top (3) starch on the back (4) of the fibrous web (F) is applied.

19. Device (12) for the treatment and / or refinement of the surface of a fibrous web (F), in particular for the multi-layer application of liquid or pasty application media on a paper or board web (1), comprising a first post-dosing applicator (13) Applying a first application medium in a first layer (7), at least one further postdosing application device (17) for applying a further second layer (5) and a further third application device (19) for applying a third layer (6) in the form of a curtain application device ( 20), each of the individual

Applicants (13, 17, 19) a drying device (15, 18, 21) is arranged downstream, characterized in that the second applicator (17) is preceded by a smoothing device (16).

20. Device (12) according to claim 19, characterized in that the curtain application device (20) is arranged and constructed in such a way that it has at least two outlet gaps (26.1, 26) connected in series.

26.2), which can be loaded with application media of different properties and produce a common curtain.

21. Device (12) according to any one of claims 19 or 20, characterized in that the first application device (13) is designed as a size press or film press.

22. Device (12) according to one of claims 19 to 21, characterized in that the second application device (17) an application device for applying application medium with an excess on a movable fibrous web (F) a metering device (23) in the form of a doctor blade or includes a blade.

23. Device (12) according to one of claims 19 to 22, characterized in that the drying device (15) arranged downstream of the first application device (13) comprises at least one contact drying device comprising at least one, preferably a plurality of drying cylinders over which the fibrous web (F) can be guided meandering.

24. Device (12) according to any one of claims 19 to 23, characterized in that the second applicator (17) downstream drying device (18) at least one impingement drying device

(18.1).

25. Device (12) according to any one of claims 19 to 24, characterized in that the third application device (19) downstream

Drying device (21) comprises at least one impingement drying device (21.1).

26. Device (12) according to one of claims 19 to 25, characterized in that the third application device (19) downstream drying device (21) comprises at least one contact drying device (21.2).

27. Device (12) according to any one of claims 19 to 26, characterized in that, the third application device (19) downstream drying device (21) is arranged downstream of a smoothing device.

28. Device (12) according to any one of claims 19 to 27, characterized in that the third application device (19) is followed by a further application device (22) for application to the rear side (4) of the fibrous web (F) opposite the upper side (3).