WO2011151234A1

WO2011151234A1 - Method for producing a coated multilayer fibrous web

Info

Publication number: WO2011151234A1
Application number: PCT/EP2011/058532
Authority: WO
Inventors: Guido Klaunzer; Stephan Hampe
Original assignee: Voith Patent Gmbh
Priority date: 2010-06-02
Filing date: 2011-05-25
Publication date: 2011-12-08
Also published as: EP2576900B2; CN103109018A; DE102010029617A1; EP2576900A1; EP2576900B1; CN103109018B

Abstract

The invention relates to a method for producing a coated multilayer fibrous web, in particular a packaging paper or cardboard web. First, a material flow (S) is produced which is then successively fed to at least one headbox (1), at least one wire section (I) for forming a multilayer fibrous web (B), a pressing section (II), a drying section (III) with drying groups (8a, 8b), and subsequently a roll-up device. The method is characterized in that the fibrous web (B) produced in a multilayer manner is precalendered with a belt calender (13). Afterwards, the top layer of the fibrous web (B) is coated with a white coating layer that contains a white pigment using a curtain application unit (14.1) and then dried.

Description

Process for producing a coated, multi-layer fibrous web

The invention relates to a method for producing a coated, multi-layer fibrous web, in particular packaging paper or board web, in which first a stream is produced, which then successively at least one headbox, at least one wire section to form a multi-ply fibrous web, a press section, a dryer section with dryer groups and then fed to a reel.

Cardboard and packaging papers are usually dried on their production in paper machines with drying cylinders of a single-row and / or double-row dryer section. In this case, optional suction elements, especially for web stabilization available. A disadvantage is the high space requirement for such dryer sections and also to view the limited drying capacity. Especially with regard to the demanded, ever-increasing machine speeds, the drying zones must be formed longer relative to the overall machine length.

The smoothness of the paperboard or packaging paper to be produced is usually produced in the production of paperboard using conventional calenders, such as hard-nip calenders with high maximum pressures and short residence times of the fibrous web in the nip. A disadvantage of this technology, the thickness loss of the web affects. Other conventional soft-nip calander smoothing processes use soft roll covers to increase the residence time in the nip. This is disadvantageous, the slight increase in smoothness and the volume loss. Other conventional smoothing methods, such as nip calendering or shoe straightening, use soft covers of the unheated roll. The disadvantage here is also a slight increase in smoothness with simultaneous loss of volume. In most cases, the fibrous web or packaging paper or board web is also painted with a pigment coating. This achieves whiteness, smoothness, gloss and opacity of the web. Also, the printability of the web material is thereby increased, whereby it can serve as an information and advertising medium.

The printing is done in addition to digital printing, especially in the form of offset printing and gravure printing.

The fibrous web is painted on the cover side at least once. The reverse side may remain uncoated, or will also be painted at least once. In this case, coating amounts per side of up to 80g / m ^{2 are} applied. The application has hitherto been carried out with conventional coating units, such as film presses, coaters with roller application (LDTA applicators with long exposure time of the coating medium), coater with free-jet nozzles, or with commissioned work with a short residence time of the medium on the web (so-called Short Dwell Time Applicators or SDTA ).

The disadvantage is that only a limited application capacity and thus poor coverage and opacity of the fibrous web or packaging paper and board web can be achieved with these mentioned conventional order types. It is therefore an object of the invention to provide a method for producing a coated, multi-layer fibrous web, in particular packaging paper or board web, which does not have the disadvantages of the prior art.

The object of the invention is achieved by a method according to the features of claim 1.

According to the invention it is provided that the multi-layer fibrous web is preformed with a belt calender and then coated the cover layer of the fibrous web by means of a curtain applicator with a white pigment-containing coating layer and then dried

The inventors have found that with the specified pre-smoothing method, ie with a belt calender a smoother paper is produced than before, so what was done either without pre-smoothing or with other calenders.

Strip smoothing according to the invention leads to better coverage of the white line layer subsequently applied with the curtain applicator. Due to the high smoothness of the web there is a much lower risk of demolition of the curtain during coating, even with low coating weights or low viscosity of the application medium used in curtain coating and high web speeds. This is considered a particular advantage of the invention. Incidentally, the smoothness of the web need only be present on one side before the coating, because the product resulting from the fibrous web produced is preferably only printed on one side.

The band used in the pre-smoothing of the fibrous web consists of more than 70% of plastic. There is a temperature of more than 80 ° C. at the strip surface in contact with the fibrous web.

Another advantage is that due to the white pigment-containing curtain coat, which is indeed very uniform and good coverage, only a low basis weight of white and expensive fiber layer (top layer) is needed, so you save expensive raw materials, without the lower fiber layers shine through and without that the print quality deteriorates.

The method according to the invention makes it possible to produce the fibrous web in at least two layers, preferably at least three layers, namely backsheet, middle layer, top layer, depending on the desired application. For the top layer white or bleached and / or deinked and / or wood-free fibers are provided, which are expensive. It is therefore all the more advantageous to be able to save these substances to a large extent because the described white coating layer is applied to the cover layer with the aid of a curtain coating. In certain cases (eg with white multiple lines) even the white top layer can be completely replaced with the white line layer. A curtain coater applies the application medium in the ratio 1: 1, that is, without excess to the running fibrous web in its production process. On the web so only the amount of coating material or pigment-containing application medium is applied, which should also remain there. This saves the doctoring and the corresponding squeegee devices. The at least one coating layer can be applied with a single- or multi-layered curtain applicator in the form of a slot die or a so-called slide die. It is expedient if a condensation press drying is provided within the pre-drying section. This could also be done after the drainage in the press section and / or in a post-dryer section. This offers the advantage of an increased evaporation rate of greater than 40 kg / m ² h and the smoothing of the fibrous web. This type of drying, with which conventional drying cylinders can be partially saved, should take place in a range in which the web has a solids content of more than 50% to about 90%, preferably more than 55%. At least such drying should therefore, as stated, preferably be carried out within the pre-drying section, and it is also conceivable to provide this also in the after-dryer section. The mentioned high rate of evaporation and smoothness is due to the fact that the fibrous web is guided with its one side over a preferably steam-heated cylinder and with its other side over a sieve and an overlying impermeable clothing. In this case, in this section, a contact pressure with respect to the cylinder is exerted with a pressure hood covering part of the outer circumference of the cylinder. A particular advantage is to be considered an improved heat transfer from the steam room of the drying cylinder to the fibrous web. In addition, one achieves an increase in the drying speed, without machine extensions are necessary. The paper strength and the surface properties are increased despite the possible savings of raw fibers. Also the order of strength can be reduced, in some cases even completely saved. The production method according to the invention can be formed even more advantageously by feeding a fines into the head box at the beginning of the production process for the formation of the top layer of the multi-ply fibrous web. This achieves a very smooth cover layer, which forms a particularly good foundation for subsequent coating layer and which achieves a very even coverage of the fibrous web.

Incidentally, the head box can be designed as a perforated roller headbox or as a hydraulic headbox. Optionally, at least one headbox is equipped with dilution water control. The advantage of this is that a surface weight profiling without adjustment of the lip and thus the fiber orientation is achieved. Preferably, the central layer is equipped with a dilution water control with the advantage that the basis weight cross profile of the entire board web can be influenced by the position with the largest proportion of the total weight (center layer) the strongest. Also conceivable is a multi-layer casserole which is fed with different material flows.

In the wire section all known form combinations can be used. Preference is given to the use of wire mesh screens, but also combinations of long and seven hybrid formers, for example, the marketed by the company of the applicant Duo D or Duo DK as combinations of at least one Gapformern and at least one long screen use. It is advantageous if the said former is equipped with a Siebschütteleinrichtung, for example, with the marketed by the company of the Applicant Duo Shake. In the case of multi-layer concepts, this should preferably be provided for the layer with the highest bearing area weight, such as the middle ply.

For example, a tandem NipcoFlex press (TNFP) with offset press, which is quadruple felted and / or a press unit, consisting for example of a suction press roll in the first nip, a NipcoFlex press in the second nip and find an offset press in the third nip use. The press concepts can be designed with closed or open web guide. The stiffening, ie the support frames for the presses can be performed as so-called cantilevers. It is also possible to use stitched or even seamless felts in the press section. Dry contents of up to 57% can be achieved with the mentioned press concepts.

In the context of the invention, it is advantageous if at least one smooth roller is used in the press section, which acts at least on the cover layer, which can by means of a known tandem press with three felts and a smooth roller, which is usually arranged below or with a so-called offset press, in which a nip is carried out without clothing, done. This measure also contributes to a smoother cover layer, which in turn can be coated more uniformly.

To increase the efficiency of the process, it is expedient to carry out a per se known impingement drying directly after the press section and before the first heated drying cylinder of the dryer section. This can increase the dry content of the web and reduce the risk of demolition in the dry section. Thus, a speed of greater than 1000m / min, in particular greater than 1200m / min is possible.

With regard to the quality of the packaging paper or board web, it may also be advantageous if, instead of the strip smoothing described above-but also in addition to strip smoothing-the web after the predrying and before a later coating with the at least one white coating layer of a condensation press smoothing is subjected. This smoothing process leads to even higher smoothness values. Is that correct ?? The condensation press smoothing works in a similar way to condensation press drying, whereby the fibrous web is passed over a heated cylinder and directly brought into contact with a metal belt running over the cylinder, above which a pressure hood is located. A sieve or a clothing is hereby not available.

In condensation press drying and also in condensation press smoothing, preferably the cylinder (drying cylinder or smoothing cylinder) is preferably heated with steam, the cylinder surface reaching a temperature between 60 and 250 ° C., preferably 130 to 190 ° C.

The method according to the invention can be further expedient if, following the curtain coating, the same side of the web is coated a second time with a conventional coating unit, such as a directly applied blade coater, and then the other side also coated with a conventional coater and then dried with dryers becomes.

With regard to the quality of the fibrous web produced, it is when it is smoothed before reeling, so within a final group of the manufacturing machine.

This calender has a heating roller, which is provided with a plastic jacket having a metallic coating with a thickness of <200μηη. This achieves an enormous increase in smoothness and an even better gloss.

Subsequently, the fibrous web of a cooling group and then the reeling can be supplied.

With the method according to the invention it is possible a coated board, in particular (FBB or folded box board or chromo or Chromoersatzkarton) or LPB (liquid packaging board or liquid carton) or coated packaging paper, in particular CWTTL (coated white top testliner) or CWTKL (coated white top kraft liner) with at least two layers produce.

According to a first variant, it is possible that the cardboard or the paper three Layers, which consist of a fiber cover layer of bleached pulp, a middle layer of wood-containing raw material and / or recycled paper and a supine layer of bleached pulp or a mixture of bleached pulp with shares of wood-containing raw material, which also shares in waste paper material are added ,

According to a second variant, it is possible that the cardboard or the paper has four layers. In addition, there is a protective layer between the top and middle layers. This protective layer consists either of waste paper pulp or a mixture of waste paper pulp and wood-containing raw material.

The blanket is made of 100% bleached pulp, depending on the quality of the box, and is painted at least once. The insert, i. the middle days are light and consist of either 100% wood-containing raw material or shares of waste paper pulp are added.

The back is bright and consists of either 100% bleached pulp or a blend of bleached pulp with levels of wood-containing raw material. It can also be added to the back shares of waste paper pulp. The reverse side can optionally be painted with at least one stroke. If used paper pulp can be optionally deinked in stock preparation. But there are also machines with four-layer concepts possible. Here, in addition to the three layers described, there is still a protective layer between the in or middle layer and the blanket. This protective layer consists either of waste paper pulp or of a mixture of waste paper pulp and wood-containing raw material.

Depending on the quality of the raw material used and the application rate, a distinction is made between qualities with the following abbreviation, with the number 1 indicating the variety with the highest quality. With the grades GG the coating is enriched with plastics. Type of line weight

GC1 Stripped> 18 g / m ² Better raw material than

GC2 and GC3

GC2 coated> 12 g / m ²

GG1 cast-brushed back wood-free

GG2 Cast brushed back bright

The following table provides an example of an overview of which combinations of raw materials are possible. In proportion, all mixtures are possible.

Where:

LUKP unbleached hardwood kraft pulp / unbleached short fiber kraft pulp

NUKP unbleached softwood kraft pulp / unbleached long fiber kraft pulp

LBKP bleached hardwood kraft pulp / bleached short fiber kraft pulp

NBKP bleached softwood kraft pulp / bleached long fiber kraft pulp

OCC old corrungated container / old corrugated paper packaging

GW g round wood / groundwood

TMP thermo mechanical pulp / thermo-mechanical pulp

CTMP chemical thermo mechanical pulp / chemically pretreated

Thermo-mechanical pulp

BCTMP bleached chemical thermo mechanical pulp / bleached chemical pretreated thermo-mechanical pulp ONP old news print / old newspapers

OMG old magazines / old magazines

Deduced / prepared so that inks and other contaminants are removed. White shavings, i. unprinted paper waste, for example

Edge trim from printers

MW mixed waste paper / mixed waste paper

Virgin fiber / fresh fiber

Recycled / waste paper

Top Ply / top layer or blanket

Undertop Ply / Schonschicht

Middle Ply / middle layer or insert

Back Ply / supine or back

As standard for recycled paper, the following are eligible:

Folding boxboard is cardboard with a grammage in the range of 160 - 500 g / m ² with the following characteristics

It has to be added that five layer concepts are also suitable, each with a protective layer between the insert and the outer layers.

The protective layer can consist of 100% recovered paper or optionally with shares of wood pulp. In principle, any mixing ratio is conceivable.

Depending on the quality of the box, the top layer may consist of 100% bleached pulp or 100% recycled paper pulp. But it is also possible the Make cover layer of a mixture of bleached pulp and waste paper pulp. The top layer can also be only slightly woody, although the wood pulp may be bleached or may be wood-free. The ceiling should always be painted.

The insert usually consists of mixed waste paper pulp or optionally with proportions of mechanical pulp. Each mixing ratio is conceivable.

The backside is made of recycled paper stock and may contain bleached and / or unbleached pulp. The back can either be painted or uncoated. Depending on the raw material used, a distinction is made between qualities with the following abbreviation, with the number 1 indicating the variety with the highest quality. The total proportion of mixed waste paper pulp can be found in the following table

By way of example, customary used paper pulp fractions based on the total product are indicated therein.

Sort of waste paper

GT1 80% - 100%

GT2 80% - 100%

GD1 15% - 65%

GD2 70% - 90%

GD3 80% - 100%

The following table gives an overview by way of example. In proportion, all mixtures are possible.

In any case, this multi-layer fibrous web or packaging paper or board web described above has a "white" fiber cover layer, which is subsequently provided with the white coating layer.

With the present inventive method it is possible for the first time to produce packaging paper and paperboard of particularly high quality and printing properties.

The benefits of the process also include energy and resource savings. The process itself is characterized by an improvement in runnability (running properties).

The invention will be explained with reference to an embodiment. Show it

Figure 1: a representation of a process scheme for producing a multi-layer, coated fibrous web

Figure 2: a schematic representation of the constant part for producing a

Mixture for the production of a fibrous web according to FIG. 1

FIG. 1 shows a process diagram of the production of a multilayer, coated paper or board web.

The originating from a stock preparation stream S is supplied from a headbox 1 with a dilution water control a wire section I. The wire section consists of three longitudinal wires 2, 5 and 6 to form a multi-ply web B. The wire 2 is used to form a central layer, the wire 4 of the cover layer and the wire 4 is the back formed. The centerline wire 2 is equipped with a former 3 (traded by the Applicant Company under the name DuoFormer D) and with a sieve shaker 4 (traded by the applicant's company under the name Duo Shake).

The substance of the individual layers is sprayed from the corresponding headboxes 1, 1 a onto the respective longitudinal sieves 2, 5, 6 and dewatered thereon. At the points of contact of the Langsiebe the layers are vergautscht together. The layer structure is from bottom to top as follows:

Supine position, middle position, top layer.

The web B is then successively dewatered by drainage elements in the wire section until it has a dry content of> 16% at the end of the wire section I.

From the wire section I from the web B is transferred via various acceptance elements presses 7 in the press section II. The press section II with presses 7 consists of a double-felted suction press roller 7.1 in the first nip and a double-felted suction press roller 7.1. Press Nipco Flex Press 7.2 in the second nip and an offset press 7.3 in the third nip. After press section II, web B reaches dry contents of up to 57%. This pressing concept can be carried out with closed or open web guide. The stasis can also be designed as a cantilever. It is possible to use seamed or seamless felts in the press section II

After leaving the press section II, or the presses 7, the further drying of the web B takes place by means of conventional drying cylinder groups 8a within a pre-drying section III, which here have two-row drying cylinder arrangements. Subsequent to the drying groups 8a, for example, a drying unit 9 with condensation press drying is installed. Here is a much more intense drying of the paper web and a significant increase in smoothness of the cylinder-contacted web page. Such a drying arrangement is known for example from EP 1586 698 A1 and EP 0988 417 B1.

This technology used here is particularly energy-efficient, since in addition to the high specific evaporation of more than 40 kg / m ² h and a significant increase in smoothness of the packaging paper or cardboard takes place within the dryer section hood. Preferred installation position of this condensation press dryer is in a range above 50% to about 90% dry content, but mainly above 55% dry content. The integration of one or more such drying units is preferably carried out in the pre-drying section III, but it is also conceivable to provide such units in a subsequent after-dryer section. Again, the condensation press dryer 9 offers the advantage of increased evaporation rates and paper smoothing.

These drying units 9 can be installed in "line", ie at the level of the conventional dryer section as well as in the machine cellar Advantage of the installation in the machine cellar is that the drying unit 9 can be taken out of line and the drying process only with a conventional dryer section Moreover, it is possible for existing machines which are drying-limited to increase production by installing one or more drying units 9. by replacing conventional drying cylinders.

After this drying unit 9, a further conventional drying cylinder group 8b are present in the example shown.

After the end of the pre-drying section III follows an application of starch. This is done with a film press 10. With the help of this film press in the example, the strength is applied simultaneously on both sides of the web indiekter way. This means that the starch is applied in each case to the circumference of an applicator roll and delivered to the surface of the two web sides in the nip between the two rolls. The advantage of this starch order is that an inferior raw material can be used for the middle ply, while still achieving a high strength of the paper or cardboard. It is also conceivable, instead of the said film press, to use a so-called size press which is equipped as described in EP 1 198643 A1. Specially designed feed nozzles protrude into the application rollers between two gussets and nipples forming a gusset and nip the gusset into it. This arrangement is referred to by experts as "SizeWings" and offers the advantage that a higher contact time of the application medium (Leikmittels) results on the fibrous web and at the same time the formation of turbulence in the sump is avoided This is followed by an after-dryer section IV with a conventional drying cylinder group 11, which in the example has a double-breasted configuration, and at the end of the after-dryer section IV is a cooling group 12 consisting of two cooling cylinders with the upper cylinder being felted, with the help of these cooling cylinders the fibrous web B is lowered to below 70 ° C.

This is followed by a pre-smoothing of the raw board or fibrous web B This can also be arranged within the after-dryer section IV, as already described in the explanation of the condensation press drying. In this case, however, no cooling group is provided in front of the unit 13.

In the example, a band calender is used as calender 13. This belt calender has a single-layer or multi-layer belt or belt with coating on the facing fibrous web side. The band consists predominantly, i. more than 70% plastic. The temperature of the calender is more than 80 ° C at the belt surface when the belt is in contact with the fibrous web. This achieves a very volume-saving and excellent smoothness.

In contrast to conventional calenders (Hardnip calender or H NC, Softnip calender or SNC, wide-nip calender, shoe caliper), a version using a so-called CeraSoft calender technology and / or Valzone technology is also conceivable. All the above-described calendering technologies offer, in contrast to conventional calenders (HNC, SNC, wide nip, shoe caliper), the advantage of particularly high increases in turgidity with very low volume loss. In addition, by using these technologies inferior, cheaper raw material can be used with at the same time very low volume loss and excellent smoothness increase without loss of strength of uncoated board web. Especially with regard to calendering errors, e.g. mottling, with this technology, optimal results can be achieved without risk. It is also conceivable to use the calender 13 for after-smoothing the coated web B. Preferred mounting position of a calender for pre-smoothing is in a range of about 55% to about 90% dry content, but mainly about 60% dry content of the web.

In a coating section V, which follows the pre-smoothing, a white line is first applied to the white cover layer of the fibrous web B. This is done with a non-contact coating unit 14 in the form of a curtain applicator 14.1 (curtain coater), which is a slot (slot) or Gleitschichtdüse (slide the) has. With the curtain coating, coating composition containing particularly high amounts of even very uniformly white pigments is applied even at elevated speeds and a particularly good coverage and thus surface quality are achieved. An embodiment of such a curtain applicator with a slot die extending over the width of the fibrous web, from which the curtain is discharged downwards essentially in accordance with gravity, is described in WO-A1-006 / 0973676. Another possible embodiment of a curtain applicator work is known from EP A1 - 1 255 615 and is referred to in professional circles as "slide the", ie Gleitschichtdüse.

It can be applied with a coating aggregate amounts up to 60g / m ² , which could otherwise be achieved only with several conventional coating units. Single-layered as well as multi-layer curtain coating units come into consideration, which reduces the space requirement in the machine. In the example shown in FIG. 1, a single-layer applicator is provided.

In the example shown in FIG. 1, the cover layer is painted a second time with a conventional coating unit 15. Subsequently, the back of the fibrous web is also coated with a conventional coating unit 16. Conventional coating units 15 and 16 are e.g. a free-jet nozzle assembly, which is followed by a doctor blade element or a coating unit with a short residence time (SDTA) or otherwise known doctor blade applicator in question. Each of a coater close unspecified contactless dryer, i. Air dryer and infrared dryer on.

In a subsequent correction group 17, the top side and the bottom side of the web B-ie the top layer and the back-are heated to different degrees, which reduces the curl of the web (curl). This correction group 17 consists of a conventional one or two-row drying group (in the example, the drying cylinders are arranged in two rows), which are equipped with or without dryer fabrics at the top and bottom. Preferably, the correction group 17 However, equipped with 2 drying screens one for the upper and one for the lower row of drying cylinders. The upper and lower drying cylinders within the correction group are heated so that the cylinder surface temperatures differ by at least 10 ° C.

Subsequently, the web is nachkalandriert in a calender 18. In the example, a Softnipkalander is used to create a particularly high gloss effect of the finished paper or cardboard and the micro-roughness is reduced.

Instead of this Softnipkalanders could also be distributed by the company of the Applicant so-called Terra X calender use. Such a calender has a heated roll with a plastic jacket which is provided with a metallic layer on. The thickness of the plastic sheath is about 5 to 50mm and the metallic layer is about 5 to 100 μιτι thick.

A cover layer on an elastic roller is disclosed, for example, in DE 10 2008 037 999 A1.

Before the reeling 20 on a scooter without center drive the web B is still cooled with a cooling group 19 to temperatures below 70 ° C.

The cooling group 19 is felted in the example shown below. The advantage of this is that the upper surface of the web B smoothed in the SoftnipKalander 18 no longer comes into contact with the wire and, as a result, the gloss effect is retained.

The arrangement of the cooling group 19 before the reeling 20 - as shown in Figure 1 - has the advantage that the thermal change in length of the web is reduced to the scooter, whereby better winding properties are achieved. For reeling 20 is to be added that also configurations of scooters with center drive are conceivable. Compared to scooters without center drive Finer settings of the winding properties can be achieved.

FIG. 2 schematically shows the production of the substance mixture for producing the fibrous web.

The above example sketch refers to a constant part of a web-making machine or system in which the top ply, the middle ply and the back ply consist of 100% virgin fiber. Therefore, a cleaner stage is provided in the respective material strand, since this is not provided in the stock preparation.

The material stream S coming from the stock preparation is premixed in a mixer 30 (ComMix) together with the white water, if appropriate also with additives, for example retention agents. The scrap is preferably mixed into the machine chest of the Middle Ply. It is also conceivable that the committee in the ComMix of Top Ply or Back Ply is led. For further dilution of the amounts of substance, the suspension is mixed with white water in a further mixer 31, a so-called Hydromix. The concentration of the stock suspension after the Hydromix is higher than the concentration of the headbox, with the advantage that a smaller number of assemblies can be selected for the subsequent cleaner 32 (Cleaner or EcoMizer). Small impurities, eg fine sand, are removed in this cleaning device 32. Subsequently, in the mixer 33, a further dilution with white water to the desired headbox concentration and optionally a mixture with additives. Through a headbox 34, the suspension for the destruction of fiber flakes and for final cleaning through a cleaning screen 35 (HB Screen, MSA, MST, MSS) out. In addition, here a reduction of Stoffpulsa- tions whereby substance fluctuations in the headbox 36 are avoided in the machine direction. Before the headbox 36 of the stock suspension, the necessary amount of retention agent 37 can be added. The water required for the dilution water control at the headbox 36a of the middle layer (midde ply) is taken from a white water channel and after being processed in a device 38 in FIG a sifter led to the headbox.

LIST OF REFERENCE NUMBERS

I wire section

II press section

III pre-drying section

IV night drying section

V bowstring

1 headbox

2 wire

3 shaper

4 sieve shaker

5 wire

6 wire

7 press

7.1 Suction press roller

7.2 Nipcoflex press

7.3 Offset press

8a drying group

8b drying group

9 Drying unit with condensation press drying

10 film press

1 1 drying cylinder

12 cooling group

13 calender with condensation - press smoothing

14 coating unit

14.1 Curtain commissioned work

15 coating unit

16 coater

17 correction group

18 calender 19 cooling group

20 reeling

30 mixers

31 mixers

32 cleaning device

33 headbox pump

34 mixers

35 cleaning sieve

36, 36a headbox

37 retention aids

38 Processing device

Claims

claims

1 . A process for the production of a coated, multilayer fibrous web, in particular packaging paper or board web, in which first a stream (S) is produced, which subsequently successively at least one headbox (1), at least one wire section (I) to form a multilayer fibrous web (B) , a press section (II), a dryer section (III) with dryer groups (8a, 8b) and then fed to a reel, characterized in that

the multi-layer fibrous web (B) is pre-smoothed with a belt calender (13) and then the top layer of the fibrous web (B) by means of a curtain applicator (14.1) coated with a white pigment-containing coating layer and then dried.

2. The method according to claim 1,

characterized in that

the fibrous web (B) is produced in at least two layers, preferably three layers, namely backsheet, middle layer, top layer, wherein the cover layer contains white or bleached and / or deinked and / or wood-free fibers.

3. The method according to claim 1 or 2,

characterized in that

a condensation press drying (9) is carried out after drying in the drying section (III) or between the individual dryers (8a) or following the dewatering in the press section (II).

4. The method according to at least one of the preceding claims,

characterized in that following the curtain coating (14.1), the same side of the web coated a second time with a conventional coating unit (15), such as a direct application blade coater (15.1), dried and then the other side also coated with a conventional coating unit (16) and then dried with dryers (17).

5. The method according to at least one of the preceding claims,

characterized in that

the coated web is fed to a correction group (17), a subsequent calender (18), a cooling group (19) and then to the reel (20).

6. The method according to claim 1 and 2,

characterized in that

for the formation of the cover layer of the multi-ply fibrous web (B) a fine material in the headbox (1) is guided.

7. The method according to claim 1,

characterized in that

the at least one white coating layer is applied with a single- or multi-layered curtain applicator (14.1) in the form of a slot die or slide die.

8. The method according to claim 5,

characterized in that

the calender used (18) in the final group of the manufacturing machine, a heated roll with a plastic sheath, which is provided with a metallic layer has.

9. The method according to claim 8, characterized in that

The thickness of the plastic sheath is about 5 to 50 mm and the metallic layer has a thickness of between 5 and 100 μιτι.

Method according to claim 1,

characterized in that

in the press section (II) at least one smooth roller is used, which acts at least on the cover layer.

1 1. Method according to at least one of the preceding claims,

characterized in that

directly after the press section (II) and before the first heated drying cylinder of the dryer section (II I) a per se known impingement drying is carried out.

12. The method according to claim 1,

characterized in that

in the pre-smoothing (13) of the fibrous web (B), a band is used which consists of more than 70% plastic and has a temperature of more than 80 ° C at the belt surface in contact with the fibrous web.

Method according to at least one of the preceding claims,

characterized in that

to produce a coated carton, in particular chromo or chromo replacement carton or liquid carton, or coated wrapping paper, coated white top test liner (CWTTL) or coated white top kraft liner (CWTKL)

Method according to claim 13, characterized in that

the cardboard or paper has three layers, which consist of a fiber cover layer of bleached pulp, a middle layer of wood-containing raw material and / or waste paper and a supine layer of bleached pulp or a mixture of bleached pulp with shares of wood-containing raw material, which also shares be added to waste paper pulp exist.

15. The method according to claim 13 and 14,

characterized in that

the cardboard or paper has four layers, which in addition to the three layers still has a protective layer between the cover and middle layer, said protective layer either consists of waste paper pulp or a mixture of waste paper pulp and wood-containing raw material.