CN111684128A

CN111684128A - Method and device for producing a multi-layered fibrous web

Info

Publication number: CN111684128A
Application number: CN201880088753.9A
Authority: CN
Inventors: L.弗里德里希; W.曼内斯
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2018-02-09
Filing date: 2018-11-30
Publication date: 2020-09-18
Anticipated expiration: 2038-11-30
Also published as: WO2019154540A1; EP3749801A1; CN111684128B

Abstract

The invention relates to a method for producing a multi-layered fibrous web (38), comprising at least one stock preparation section (4), two headboxes (24, 29, 34) and a forming section (20) of a paper machine for producing the multi-layered fibrous web (38), wherein a fibrous raw material (2), which at least partially contains old paper with fillers and fines, in particular OCC, and/or waste paper (3) produced in the method for producing the multi-layered fibrous web (38), is fed to a disintegration device (11) of the stock preparation section (4) and forms at least one suspension flow (12) there, and is fed to a washing stage (13) for separating fillers and fines in order to form a filler fines flow (14) and a fibrous suspension flow (15), wherein the fibrous suspension flow (15) is fed to at least one headbox (24, 29, 34) and the filler fines flow (14) is separated in the separation stage (17) into a filler flow (18) and a fines flow (15) (19) And a filler flow (18) is applied in the forming section (20) between the two plies (25, 30, 35) of the multilayer fibrous web (38) being formed at a feed point (40). The invention also relates to a device for carrying out the invention.

Description

Method and device for producing a multi-layered fibrous web

The invention relates to a method and a device for producing a multi-layered fibrous web.

Methods of this type are known. Thus, patent document WO12041392a1 describes the production of an at least three-layer fibrous web in the forming section of a paper machine. The forming section comprises a plurality of fourdrinier wire units each for forming a single layer of the fibrous web. The individual plies are couch-pressed or pressed together to form a multi-layered fibrous web. As a raw material for the intermediate layer, waste cardboard (OCC, old corrugated cardboard pulp) mixed with used paper, newspaper, waste paper, and the like are generally used. Deinked material, cellulosic material, CTMP as well as OCC and waste paper were used for the back layer.

With increasing use of old paper and increasing recovery rates, the proportion of fillers and fines in the raw material resulting from the recycling of fibre-containing products is increasing. This results in a reduction in the strength of the paper product produced, particularly in paperboard and wrapping paper. This disadvantage is eliminated by a higher weight per unit area or by increasing the use of higher quality raw materials, such as pulp. This leads to increased production costs, especially in the production of paperboard and packaging.

The object of the present invention is therefore to propose a method and a device for producing a multi-layered fibrous web, with which it is possible to reduce the production costs on the one hand and to obtain or increase the strength potential of the fibrous web on the other hand.

This object is achieved by the features of claim 1. There is provided a method for manufacturing a multi-layered fibrous web, the method comprising at least a stock preparation section, two headboxes and a forming section of a paper machine for constructing the multi-layered fibrous web, wherein a fiber-containing raw material at least partially containing old paper with filler and fines, in particular OCC, and/or paper waste produced in the method for producing a multi-layered fibrous web is fed to a disintegration device of a pulp preparation section, and there forming at least one suspension flow and feeding said at least one suspension flow to a washing stage for separating the filler and fines, to construct a filler fines stream and a fibre suspension stream, wherein the fibre suspension flow is fed into at least one headbox and the filler fines flow is separated in a separation stage into a filler flow and fines flow, and the filler stream is introduced in the forming section between two layers of the fibrous web of the multilayer being formed.

The filler contained in the old paper-based raw material reduces the potential for mechanical properties, in particular the strength potential, for example the breaking length, of the produced fibrous web. By separating the filler from the suspension flow, the filler content of the layers of the fibrous web, which are produced at least partially from the remaining fibrous suspension flow, is reduced, thus increasing the strength of the fibrous web. Thus, in practice, the negative consequences with increasing filler content in old paper can be compensated for. Depending on how much filler is separated from the fibre-containing raw material, it is also possible to achieve higher strengths than with the methods customary today. This also enables a reduction in the use of high-quality fibrous material or a reduction in the weight per unit area of the individual plies or of each ply of the multi-layered fibrous web. The cost per ton of paper web can be significantly reduced. On the other hand, the method also enables the production of a multi-layered fibrous web for the purpose of use with high demands on mechanical stress without reducing the weight per unit area. A further advantage is that the separated filler does not need to be disposed of expensively, but can be used for producing a fibrous web without adversely affecting the quality of the multilayered fibrous web. This is achieved in that the filling material is arranged in a suitable manner between two adjacent layers of the multi-layer fibrous web in the region of the forming section.

The filler is a mineral material, such as kaolin, titanium dioxide, calcium carbonate. In contrast, fines include organic materials, such as organic materials formed from organic fibrous materials.

In order to determine the mass fraction of fines and fillers of the fiber suspension, a sample of the fiber suspension is fractionated in a pall-macnit fiber sieve (standard: TAPPI T233) and the D100 fraction (sieve plate ASTM 100) is used for the determination. The quality of the filler in the D100 fraction is determined by treating the D100 fraction in a burning furnace and determining the quality of the so-called burning residue in accordance with DIN ISO 1762. The mass of the ignition residue is referred to the total mass of solids in the sample of the fiber suspension to give the mass fraction of filler in the fiber suspension. The fine fraction is determined by the difference between the total mass of solids in the D100 fraction and the mass of the burned residue of the D100 fraction, with reference to the total mass of solids in a sample of the fiber suspension.

The method can be used not only for the filler-containing raw materials that are put into use, but also for the recycling of filler-containing waste paper produced in the manufacturing method. For example, waste paper may be produced in the case of a paper web tear in the paper machine during production, or also by edge cutting of the fibrous web. Since the filler separated according to the method of the invention is fed into the multi-layered fibrous web, this waste paper also inevitably contains filler and fines and can therefore be reused in an advantageous manner.

Waste paper, which is produced in particular when producing a pigment-coated multi-layer fibrous web, can be treated particularly advantageously by the method according to the invention. The filler added with the pigmented coating is substantially separated from the fibre-containing part of the waste paper after disintegration in the washing stage.

In an advantageous embodiment, the waste paper and the fiber-containing raw material can be shredded in a common shredding device.

It is also conceivable to disintegrate the waste paper in a separate disintegration device.

Furthermore, it is possible to use a common washing stage and/or a common separation stage for the treatment of waste paper and fiber-containing raw materials.

In a possible embodiment, separate washing stages and/or separate separation stages are used in order to dispose of waste paper and fiber-containing raw material.

Furthermore, waste paper can also be treated according to the method according to the invention in a separate stock preparation. This separate slurry preparation section may also be part of the sizing system of the slurry preparation section.

The separation in the washing stage is preferably carried out such that in the filler fines stream the filler mass fraction is greater than 50%, preferably from 50% to 70%, and the fines mass fraction is less than 50%, preferably from 30% to 50%. The filler mass fraction is calculated from the filler mass with reference to the total mass of solids in the filler fines stream. This also applies correspondingly to the fines mass fraction.

In practical terms, the separation in the separation stage is carried out such that in the filler stream the filler mass fraction is greater than 50%, preferably greater than 60%, particularly preferably greater than 70%, in particular greater than 80%, and in the fines stream the filler mass fraction is less than 50%.

The fines stream can be fed again into the disintegrating device or into the fibre suspension stream. The advantage of feeding the fibre suspension flow is that especially when the amount of fines is higher, the enrichment of fines in the breaker device is thus suppressed, so that operational malfunctions can be avoided. The input to the disintegrating device can be a cost-effective solution when the amount of fines is low.

In some cases, it may be advantageous to concentrate the filler stream. This can be advantageous when a filler flow is introduced in the forming section between two plies of the multi-ply fibrous web to be formed.

The filler flow is preferably applied along the entire width of the plies of the multi-layered fibrous web to be built up.

However, it is also conceivable to apply the filler flow in the multilayered fibrous web to be formed in regions along the width of the material layer. In this case, it may be advantageous to be able to control or regulate the application quantity in different regions.

In a possible embodiment, the filler flow is applied directly to the already formed layers of the multi-layer fibrous web to be formed. This can be carried out by spraying or by means of a Curtain Coater (Curtain Coater) by means of a feed device, for example a secondary flow headbox or a spray bar with nozzles arranged along the width of the layer. The average consistency of the structured bed at the feed point is preferably in the range from 2.0% to 6%, in particular between 3% and 5%, advantageously greater than 4%.

It is also possible for at least one headbox to be constructed with a plurality of flow layers in layers and for a layer to be pressed against a further layer of material by at least one of the flow layers to be produced and for the filler flow to be directed into the flow layer adjacent to the at least one flow layer and facing the further layer of material. In this solution, no additional feeding device is required, since the feeding device is formed by an existing headbox which is only of a multi-layer type. This embodiment is therefore characterized by lower costs and an increased interlaminar strength of the produced multi-layered fibrous web.

In a possible embodiment, at least one strength-increasing additive can be added to the filler flow in order to increase the interlaminar strength of the finished multi-layered fibrous web.

For example, at least one strength-enhancing additive can be added to the filler flow before it is applied between the two layers of the multi-layered fibrous web to be formed.

It is also conceivable to add at least one strength-enhancing additive to the filler flow after it has been applied between the two layers of the multi-layered fibrous web to be formed.

The at least one strength-enhancing additive may be selected from the group consisting of starch, synthetic polymers, nanocellulose, microfibrillated cellulose, fibrous materials, especially highly ground fibrous materials, such as Pulp, TMP (Thermomechanical Pulp), CTMP (chemithermomechanical Pulp).

It is conceivable that at least one strength-enhancing additive is added to the filler flow by means of a secondary headbox or a spraying device.

In an expanded possibility, a substream is branched off from the fiber suspension stream and this fiber suspension substream is ground and added to the filler stream.

In order to meet the special requirements for a multi-layered fibrous web, in addition to raw material and/or waste paper, pulp can be mixed into the disintegrating device.

The invention also relates to a device for carrying out the method according to claim 1, wherein the device for producing a multi-layer fibrous web comprises at least a stock preparation section, two headboxes and a forming section of a paper machine for constructing a multi-layer fibrous web, the device further comprising a disintegrating device in the stock preparation section for feeding a fibrous stock at least partially containing old paper with fillers and fines, in particular OCC, and/or for feeding to waste paper produced in the production of a multi-layer fibrous web and for forming at least one suspension flow, the device further comprising a cleaning stage for separating fillers and fines from the suspension flow for constructing a filler fines flow and a fibrous suspension flow, wherein the fibrous suspension flow is guided into a line connected to the at least one headbox, the device further comprising a separation stage, for separating a filler fine stream into a filler stream and a fine stream, the device further comprising a feeding device for applying the filler stream in the forming section between two layers of the fibrous web of layers being formed.

The forming section may comprise, for example, a fourdrinier former with a supporting wire and a fourdrinier unit with a dewatering wire for constituting the material layers of the multi-layered fibrous web, such as the backing layer and the cover layer, respectively. A support wire headbox or headbox for applying the fibre suspension flows respectively in order to form the respective stock layer is assigned to the support wire and fourdrinier unit. The two layers are pressed together by the couch roll at the couch roll position. The two-layered fibrous web thus formed is transported further to a discharge point (Abnahmestelle) via a supporting wire.

In other practical cases, the forming section may comprise, in addition to the fourdrinier former, fourdrinier unit, an additional fourdrinier unit with an additional headbox. They are arranged relative to one another in such a way that the further material layers formed on the further fourdrinier wire unit form a lining-in layer and are pressed against one another at the couch roll in each case at the couch roll position, first with the material layer formed on the fourdrinier wire unit and then with the material layer formed on the supporting wire.

The cover layer and/or backing layer and/or the liner layer may itself be of a multi-layer construction. In this case, each respective headbox is designed in a multi-layer manner for forming at least one further flow layer.

The support wire may be assigned an upper wire unit for improved dewatering. The upper wire unit dewaters a part of the fibre suspension in the opposite direction to the support wire. The layer thus structured is pressed by the couch roll at the couch roll position with the layer constituted by the fourdrinier wire units in a further process seen in the production direction.

The feeding device can be assigned to the layer built up by the fourdrinier wire unit and be arranged before the couch roll position.

However, it is also conceivable for the feed device to be assigned to the material layer formed by the fourdrinier wire former and to be arranged before the couch roll position.

The feeding device for applying the filler flow can be assigned to the material layer built up by the further fourdrinier wire unit and be arranged before the couch roll position.

The feeding device for applying the filler flow can be configured as a support-wire headbox of a multi-layer construction and/or as a headbox of a further multi-layer construction.

It is basically conceivable to provide several feed devices at different feed points for applying a filler flow between two layers of the multilayered fibrous web being formed in the forming section.

The feeding device is preferably designed as a multi-layer headbox and/or as a secondary headbox and/or as a spray bar with nozzles and/or as a curtain coater. The use of curtain coaters, which are also known in the paper industry as curtain coating devices in coating technology, is particularly advantageous for applying thin layers of filler flow between the layers of a multi-layered fibrous web.

In practical terms, the weight per unit area of the filler flow applied to the material layer by the feed device is in the range of 3% to 25%, in particular between 5% and 20%, of the weight per unit area of the multilayer fibrous web, depending on the filler input of the raw material or waste paper.

Furthermore, the layer thickness of the applied filler flow lies in the range from 1% to 12%, preferably in the range from 1.5% to 10%, of the thickness of the multilayer fibrous web.

Further embodiments are described in the examples according to the invention.

The invention also extends explicitly to embodiments which are not given by the combination of features which is formed by explicit reference of the claims, and the features disclosed in the invention can be combined with one another as desired in this embodiment, as long as the technical justification is achieved.

Further features and advantages of the invention will appear from the following description of a preferred embodiment, with reference to the accompanying drawings. In the drawings:

fig. 1 shows in a schematic view an exemplary embodiment of a slurry preparation section for carrying out the method according to the invention;

fig. 2 shows a further exemplary embodiment of a slurry preparation section for carrying out the method according to the invention in a schematic view;

fig. 3 shows an exemplary embodiment of a forming section for carrying out the method according to the invention in a simplified view; and

fig. 4 shows a further exemplary embodiment of a forming section for carrying out the method according to the invention in a simplified view.

Fig. 1 shows in a schematic view an exemplary embodiment of a stock preparation for carrying out the method according to the invention for manufacturing paperboard and packaging paper. The fibre-containing raw material 2 at least partly contains a filler-containing OCC (old corrugated containers), said fibre-containing raw material 2 being fed into a disintegrating device 11, such as a pulper. The suspension flow 12 formed after comminution and impurity separation is fed to the treatment stage 5. The treatment stage may comprise a plurality of cleaning stages known per se, for example a high consistency cleaning stage, a HW cleaning stage(heavies cleaning stage) or slot sorting stage. The suspension is then fed to a washing stage 13 for separating off the filler and fines to form a filler fines stream 14 and a fibre suspension stream 15. The separation in the washing stage is carried out such that in the filler fines stream 14 the filler mass fraction is greater than 50%, preferably from 50% to 70%, and the fines mass fraction is less than 50%, in particular from 30% to 50%. Cleaning stage 13 may be by known product name

Or

The scrubber of (1). The fibre suspension flow 15 is led to a further treatment stage 6, in which treatment stage 6 the fibre suspension flow is concentrated and dewatered and, if necessary, dispersed and re-diluted and ground in the grinding stage 9. The fibre suspension flow 15 is then fed, preferably via a sizing system 8', to the

respective headbox

24, 29, 34 of the forming section 20 in order to form in each case a layer of a multi-layered fibre web 38.

The filler fines stream 14 formed in the washing stage 13 is separated in a separation stage 17 into a filler stream 18 and a fines stream 19. The separation process of the separation stage 17 is carried out such that in the filler stream 18 the filler mass fraction is greater than 80%, preferably greater than 85%, and in the fines stream 19 the fines mass fraction is less than 50%. The fines stream 19 is then preferably fed into the fibre suspension stream 15 after the washing stage 13. The fines stream 19 can also be fed back into the comminution apparatus 11, in particular when the feedstock 2 has a low filler content. It is however also possible to lead a part of the fines stream 19 to the destructuring unit 11 and the remaining part to the fibre suspension flow 15. The filler flow 18 is concentrated in the concentration stage 7 and optionally fed via the sizing system 8 into the forming section 20 for forming the multi-layered fibrous web 38 and is applied there between the two

layers

25, 30, 35 of the multi-layered fibrous web 38 being formed at the feed point. In order to further improve the mechanical strength, in particular the interlaminar strength, of the multi-layered fibrous web 38, at least one strength-enhancing additive 39 can be added to the concentrated filler stream 18, said additive being selected in particular from the group of materials: starch, synthetic polymers, nanocellulose, microfibrillated cellulose, fibre materials, in particular highly ground fibre materials, such as Pulp, TMP (Thermomechanical Pulp), CTMP (Chemithermomechanical Pulp). Additives are preferably added to the sizing system 8.

The pulp preparation 4 described here for the use of a fibrous raw material 2 which at least partially contains a filler-containing occ (old coated paper) is also suitable for the case in which filler-containing waste paper 3 produced by the production of a multi-layered fibrous web 38 is incorporated into the raw material 2 in the shredding device 11. The filler content in the waste paper 3 can be significant, in particular, when the multi-layered fibrous web 38 is coated with a pigmented coating color during production, for example, when white-coated linerboard. It can therefore also be advantageous to provide a separate stock preparation for carrying out the method according to the invention in order to dispose of the waste paper 3. The separate pulp preparation section may also be part of the sizing system 8, 8' of the pulp preparation section 4.

The solution of the stock preparation 4 shown in fig. 2 differs from the embodiment shown in fig. 1 only in that, after the grinding stage 9, a fiber suspension substream 16 is branched off from the fiber suspension stream 15 and fed to a further grinding stage 10. In this further grinding stage 10, the fibers are intensively ground to a highly fibrillated fiber fraction and fed as an additive to the filler stream 18 before or preferably in the sizing system 8.

Fig. 3 shows an exemplary embodiment of a forming section 20 for producing a two-layer fibrous web 38 for carrying out the method according to the invention in a simplified view. The forming section 20 comprises a fourdrinier former 21 with a support wire 22 and comprises a support wire headbox 24 and a fourdrinier unit 26 with a dewatering wire 27 and a headbox 29, which fourdrinier former 21 and fourdrinier unit 26 are used to construct

layers

25, 30, respectively, a backing layer 25 and a cover layer 30, for example a two-layered fibrous web 38. The fibre suspension flow 15 is fed into the headbox and applied to the

respective dewatering wire

22, 27. Additionally, the fourdrinier wire former 21 is assigned an upper wire unit 23 for improved dewatering. The upper wire unit 23 dewaters a part of the fibre suspension in the opposite direction to the support wire 22. In the further course of the process, viewed in the production direction 37, at a couch position 36, the bed 30 built up by the fourdrinier wire unit 26 is couch-pressed onto the bed 25 thus built up. The two-layered fibrous web thus formed is transported further to a discharge point via a supporting wire 22. A feed device 41 for applying the filling flow 18 at a feed point 40 is associated with the material layer 30 formed by the fourdrinier wire unit 26 in the region of the dewatering section 28 and is arranged before the couch roll position 36. It is also conceivable, however, for the feed device 41 and the feed point 40 to be associated with the material layer 25 formed by the fourdrinier former 21 and to be arranged before the couch roll position 36. It is also possible to provide two feed devices 41 correspondingly. The feed device 41 for applying the filler flow 18 can also be configured as a flow layer of the multiply designed support-wire headbox 24 and/or as a flow layer of the multiply designed headbox 29. In this case, the fibre suspension flow 15 is introduced into the lower flow layer, i.e. into the flow layer of the respective

multi-layer headbox

24, 29, which is directed toward the respective dewatering wire, in order to form the backing layer 25 or cover layer 30. The filler flow 18 is introduced into the upper stock layer, i.e. into the stock layer of the

multi-layered headbox

24, 29 facing the stock layer to be couch-pressed, and is applied to the correspondingly configured

stock layer

25, 30. Thus, better interlayer strength can be achieved.

Fig. 4 shows a further exemplary embodiment of a forming section 20 for carrying out the method according to the invention in a simplified view. This embodiment is an extension of the embodiment shown in fig. 3, which is used to produce a three-layer fibrous web 38. The description of the technical features provided with the same reference numbers refers to fig. 3. Instead of the upper wire unit 23, a further fourdrinier wire unit 31 with a further dewatering wire 32 is arranged, and a further headbox 34 assigned to the further dewatering wire 32 is arranged, which further dewatering wire 32 forms the dewatering section 33. Additional layers are built on the additional fourdrinier wire units 31: lining layer 35. The liner 35 is couch-pressed together with the cover sheet 30 at a couch roll position 36 and transported flat with the cover sheet 30 over the dewatering wire 27 to the next couch roll position 36 where it is pressed against the backing sheet 25. The three-layer fibrous web 38 thus constructed is transported via the support wire 22 to a discharge point and is discharged for further processing. In addition to the feed point 41 for the filling flow 18 described in the embodiment according to fig. 3, further possible feed points 41 are provided in this variant. The filler flow 18 can be applied directly to the already built material layer, the lining layer 35, only at the feed point 41 or additionally at a further feed point 41 in the region of a further dewatering section 33 before the next couch roll position 36. The filler is in this case located between the cap layer 30 and the liner layer 35. This further embodiment provides a further feed device 41 for applying the filler flow 18. The feed device 41 can also be configured as an additional layer of the headbox 34 of a multi-layer design. In this case, the fibre suspension flow 15 is introduced into the lower flow layer, i.e. into the flow layer of the multi-layer headbox 34 facing the further dewatering wire 32, for the formation of the liner layer 35. The filler flow 18 is introduced into the upper stock layer, i.e. into the stock layer of the additional headbox 34 facing the cover layer 30 to be couch-pressed, and applied to the structured stock layer 35. Better interlayer strength can also be achieved.

In the embodiment depicted in fig. 3 and 4, the material layers can be constructed as fiber layers in a multi-layer manner. The headbox used for producing the multi-layer fiber layer is constructed in multiple layers. In this case, the respective associated

headbox

24, 29, 34 is designed in a multi-layer manner for forming at least one further layer, that is to say a further fibre layer. It is basically conceivable to provide several feed devices 41 at different feed points 40 for applying a filler flow between two layers of the multilayered fibrous web 38 being formed in the forming section 20. The feed device 41 for applying the filler flow 18 can be designed as a

multi-layer headbox

24, 29, 34 and/or as a secondary headbox and/or as a spray bar with nozzles and/or as a curtain coater.

Corresponding elements of the embodiments are provided with the same reference numerals in the figures. The functions of the described elements are equivalent to each other in each figure, unless otherwise described and contradicted. And thus the detailed description is omitted. It is also pointed out that different features of the embodiments shown can be interchanged and combined with one another. The invention is therefore not limited to the combinations of the features shown in the exemplary embodiments.

List of reference numerals

1 apparatus

2 raw materials

3 waste paper

4 slurry preparation section

5 treatment stage

6 additional processing stages

7 thickener

8 starching system

8' sizing system

9 grinding stage

10 additional grinding stages

11 disintegrating device

12 flow of suspension

13 cleaning stage

14 Filler fines stream

15 fibre suspension flow

16 sub-flows of the fibre suspension

17 separation stage

18 stream of filler

19 flow of fines

20 forming part

21 fourdrinier former

22 support net

23 upper net unit

24 support wire headbox

25 backing layer

26 fourdrinier unit

27 dewatering net

28 dewatering section

29 headbox

30 cover layer

31 additional fourdrinier wire units

32 additional dewatering wire

33 additional dewatering section

34 additional headbox

35 liner layer

36 couch roll position

37 direction of production

38 multi-layer fibrous web

39 additive

40 feeding point

41 feeding device

Claims

1. A method for manufacturing a multilayered fibrous web (38) comprising at least a stock preparation section (4), two headboxes (24, 29, 34) and a forming section (20) of a paper machine for constructing the multilayered fibrous web (38), wherein,

a fibrous raw material (2) at least partially containing old paper with filler and fines, in particular OCC, and/or a waste paper (3) produced in the method for producing a multi-layered fibrous web (38) is fed into a disintegration device (11) of a stock preparation (4), and at least one suspension flow (12) is formed in the disintegration device (11), and the at least one suspension flow (12) is fed into a washing stage (13) for separating out the filler and fines, in order to form a filler fines flow (14) and a fibrous suspension flow (15), and wherein the fibrous suspension flow (15) is fed into at least one headbox (24, 29, 34), and the filler fines flow (14) is separated in a separation stage (17) into a filler flow (18) and a fines flow (19), and the filler flow (18) is applied in a forming section (20) at a feed point (40) to the multi-layered fibrous web being formed 38) Between the two material layers (25, 30, 35).

2. The method of claim 1,

the separation in the washing stage (13) is carried out in such a way that in the filler fines stream (14) the filler mass fraction is greater than 50%, preferably from 50% to 70%, and the fines mass fraction is less than 50%, in particular from 30% to 50%.

3. The method according to claim 1 or 2,

the separation in the separation stage (17) is carried out such that in the filler stream (18) the filler mass fraction is greater than 50%, preferably greater than 60%, particularly preferably greater than 70%, in particular greater than 80%, and in the fines stream (19) the fines mass fraction is less than 50%.

4. Method according to one of the preceding claims,

the fines stream (19) is fed into the disintegration apparatus (11) or into the fibre suspension stream (15).

5. Method according to one of the preceding claims,

the filler stream (18) is concentrated.

6. Method according to one of the preceding claims,

the filler flow (18) is applied along the entire width of the layers (25, 30, 35) of the fibrous web (38) of the multiple layers being formed.

7. Method according to one of the preceding claims,

the filler flow (18) is applied directly to the layers (25, 30, 35) of the multilayered fibrous web (38) being formed.

8. Method according to one of the preceding claims,

at least one headbox (24, 29, 34) is designed in a multi-layer manner with a plurality of flow layers, and a layer (25, 30, 35) to be couch-pressed with a further layer (25, 30, 35) is formed by the at least one flow layer, and a filler flow (18) is guided into the flow layer adjacent to the at least one flow layer and directed toward the further layer (25, 30, 35).

9. Method according to one of the preceding claims,

in order to increase the interlaminar strength, at least one strength-increasing additive (39) is added to the filler stream (18).

10. The method of claim 9,

the strength-enhancing additive (39) is selected from the group consisting of:

starch, synthetic polymers, nanocellulose, high-fibrillated cellulose, fibrous materials, in particular highly ground fibrous materials, such as pulp, TMP (thermomechanical pulp), CTMP (chemical thermomechanical pulp).

11. The method according to claim 9 or 10,

before and/or after the application of the filler flow (18) between the two layers (25, 30, 35), strength-enhancing additives (39) are added by means of a secondary headbox or a spraying device.

12. Method according to one of the preceding claims,

a fiber suspension partial flow (16) branches off from the fiber suspension flow (15), and the fiber suspension partial flow (16) is ground in a further grinding stage (10) and added to the filler flow (18).

13. Method according to one of the preceding claims,

the pulp is mixed in the disintegrating device (11) in addition to the raw material (2) and/or the waste paper (3).

14. An apparatus for producing a multilayered fibrous web (38) for carrying out the method according to claim 1, comprising at least a stock preparation section (4) of a paper machine for constructing the multilayered fibrous web (38), two headboxes (24, 29, 34) and a forming section (20), the apparatus further comprising a shredding device (11) in the stock preparation section (4), the shredding device (11) being used for feeding fibrous raw material (2) at least partially containing old paper with filler and fines, in particular OCC, and/or for feeding waste paper (3) produced in the production of the multilayered fibrous web (38) to form at least one suspension flow (12), the apparatus further comprising a washing stage (13), the washing stage (13) being used for separating filler and fines from the suspension flow (12) to form a filler fines flow (14) and a fibrous suspension flow (15), wherein a fibre suspension flow (15) is conducted into a line connected to at least one headbox (24, 29, 34), the device further comprising a separation stage (17) for separating a filler fines flow (14) into a filler flow (18) and a fines flow (19), the device further comprising a feeding device (41), the feeding device (41) being used to apply the filler flow (18) between two layers (25, 30, 35) of the multi-layered fibre web (38) being formed in the forming section (20) at a feeding point (40).

15. The apparatus of claim 14,

the feeding device (41) is designed as a multi-layer headbox (24, 29, 34) and/or as a secondary headbox and/or as a spray bar with nozzles and/or as a curtain coater.