EP1770210A1 - Method and device for manufacturing a tissue web - Google Patents

Abstract

Apparatus for producing a web of fibrous material comprises a press zone (26) through which the web (22) is passed between a permeable structured belt (18) and a permeable unstructured support belt (28), a drying cylinder (42) with a press nip (44) through which the web is passed together with the structured belt, and a calender (64) through which the web is passed after leaving the drying cylinder. Independent claims are also included for: (1) producing a tissue paper web by pressing the web between a permeable structured belt and a permeable unstructured support belt, drying the web on a heated surface and calendering the web; (2) hygiene paper, e.g. toilet paper, cosmetic tissue paper or paper handkerchief paper, produced as above.

Description

The invention relates to a device for producing a fibrous web, in particular tissue web. Furthermore, the invention relates to a method for producing a tissue web. The tissue paper in question may in particular be tissue paper such as toilet paper or facial tissue.

Toilets and facial tissue ideally have a high softness, so-called "structural softness", a high softness of the surface, so-called "surface softness" in conjunction with a high tear resistance. Softness is essentially determined by the volume and porosity of the tissue paper.

To increase the volume has already been proposed to press the tissue paper web during their production only zonal, in addition to the pressed tear-resistant areas to obtain even slightly pressed or ungepresste voluminösere areas.

In the production of tissue paper, the tissue web is passed in a final drying step over the surface of a heated Yankee drying cylinder before the finished product is creped from this. If this tissue web is passed over the Yankee drying cylinder, it is held by a covering.

The invention has for its object to provide an improved device of the type mentioned egg n-gangs. It should be created with the device in particular the possibility of tissue paper very high volume to produce with a high softness. In addition, the tissue paper should be produced with as soft a surface as possible, without having to sacrifice any of the other properties of the tissue paper.

This object is achieved according to the invention by a device for producing a fibrous web, in particular a tissue web, having a press zone through which the fibrous web, together with a circulating permeable structured tape and an unstructured, i. smooth, permeable support belt between the structural belt and the support belt is guided horizontally, and provided on a drying cylinder press nip, through which the fibrous web is passed together with the structural band between the structural band and drying cylinder, wherein the fibrous web is passed to the drying cylinder through a calender.

In this case, the task of transferring the fibrous web from the structural strip to the drying cylinder is essentially the task of the press nip provided on the drying cylinder.

During the dewatering of the fibrous web guided between the permeable structured belt and the non-structured permeable support belt, it is preferably dewatered in the direction of the support belt.

The calender preferably comprises a calender nip formed between two hard rolls, through which the fibrous web is passed. Preferably, the two calender rolls are not heated.

Due to this training results tissue paper very high volume with correspondingly great softness. By using a corresponding calender following the drying cylinder, a soft surface of the Tissue paper while maintaining the other properties of the tissue paper. In addition, the tissue paper gets the desired grip.

Preferably, the two calender rolls are each formed by a chill roll. Advantageously, the two rolls are each uncoated.

In a practical practical embodiment of the device according to the invention, the calender comprises only two rollers.

Between the two calender rolls, a small open calender nip or a calender nip with a low nip load is formed. In this case, the line load generated in the calendering nip is preferably <10 kN / m.

Following the calender, the fibrous web is expediently fed to a winding device, which expediently comprises a winding core and a pressure roller which can be applied or pressed against the winding forming on the winding core.

To ensure that the previously achieved high volume of the tissue web is maintained, the line force in the winding nip between the pressure roller and the roll is preferably ≦ 0.2 kN / m. In contrast, in the usual rewinding devices, this line force is generally> 0.8 kN / m.

Conveniently, the winding core of the winding device is driven. Alternatively or additionally, however, the pressure roller can also be driven.

Since, in the case of a driven winding core, the forming roll does not have to be taken along by the pressure roll, the desired line forces as small as possible in the winding gap can be realized without difficulty. The desired as possible However, low line forces are also possible in the case of a driven pressure roller, since the fibrous web can be supplied from the scraper to the winding nip in such a case, for example by means of a screen belt, so that no train is required here.

After the fibrous web in the press zone between the structural band and a circulating, unstructured, i. The tissue web can be brought into contact with the drying cylinder, which is preferably designed as a Yankee cylinder, with a relatively smooth side while, on the other hand, only part of the fibrous or tissue web is pressed due to the structure band lying on the other side of the web becomes. In contrast to the conventional TAD machines, the tissue web can thus come into contact with the Yankee cylinder with approximately 100% surface area of the relevant side, while only a part of it is pressed.

Preferably, the fibrous web is formed in a forming zone on the structural band. Thus, the wells of the structured band are filled with fibers, instead of sucking the fibers of an already formed web as in a conventional TAD method in the wells of the structural band.

As the fibrous web is further dewatered towards the side facing away from the structural band by the supporting and / or dewatering band, the fibers are urged in the direction of the relatively flat or smooth surface of the support band formed in particular by a dewatering band. The drainage can be done for example by a correspondingly high vacuum and / or mechanically, for example by means of a tension band, through which the structural band, the fibrous web and the support band are pressed against a preferably smooth surface. The gas stream in question preferably flows first through the permeable structural band, then the fibrous web and then the preferably permeable support band. By contrast, flows through in a conventional TAD method, the gas stream concerned first the fibrous web and then the structural band. Unlike the solution according to the invention, the fibrous web thus does not receive a smooth surface in such a conventional TAD method. Besides, the differential pressure generated in the conventional TAD method is relatively small.

Advantageously, the pressing zone is delimited on the side adjacent to the support belt by an at least substantially smooth surface.

In an expedient practical embodiment of the device according to the invention, the preferably smooth surface defining the press zone on the side adjacent to the support belt is formed by a curved surface. In this case, this curved surface is preferably formed by a rotating roller.

It is particularly advantageous if means are provided for generating a gas flow in the region of the pressing zone, which flows through the structural band, the fibrous web and the support band. The gas stream preferably flows through first the structural band, then the fibrous web and finally the support band.

In particular, means for generating an air stream and / or means for generating a vapor stream may be provided.

According to an advantageous practical embodiment of the device, the means for generating a gas flow comprise a suction roller provided with a rotating suction roll, which limits the pressing zone on the side adjacent to the support belt. The curved, preferably smooth surface is thus formed in this case by the rotating suction roll.

In principle, the gas flow can also be generated at least in part by means of a flat or curved suction box or the like, which delimits the pressing zone on the side adjacent to the support belt.

In addition, it is also conceivable, for example, to generate the gas flow at least partially by means of an overpressure hood arranged on the side of the permeable structural band.

Alternatively or additionally, the structural band, the fibrous web and the support band can advantageously be pressed against the preferably smooth surface by means of a press belt under tension. In this case, the preferably smooth surface can in particular be formed again by a rotating roller.

As a structural band, a structured sieve is expediently provided.

According to a preferred practical embodiment of the device according to the invention, a TAD (through-air-drying) screen is provided as a structural band.

As already mentioned, the support band may in particular be a dewatering band, preferably a felt.

Preferably, the relatively recessed and the relatively elevated regions of the structural band are formed and arranged relative to each other that a maximum of 35% and preferably at most 25% of the structural band are pressed in the press nip.

An as gentle as possible pressing is achieved in that the provided on the dry or Yankee press nip is a shoe press nip.

As already mentioned, the fibrous web in the area of the press nip is preferably transferred from the structural band to the surface of the dry or Yankee cylinder. In this press nip, the fibrous web thus lies between the structural band and the drying cylinder, i. on the side of the drying cylinder.

The fibrous web removed again from the drying or Yankee cylinder is then fed to the take-up device, as already mentioned.

• Pressen der zwischen einem permeablen strukturierten Band und einem nicht strukturierten permeablen Stützband geführten Tissuepapierbahn,
• nachfolgendes Trocknen der Tissuepapierbahn an einer beheizten Fläche und
• nachfolgend Kalandrieren der Tissuepapierbahn.

In the method according to the invention for producing a tissue paper web, in particular a tissue paper web, the following steps are carried out:

• Pressing the tissue paper web between a permeable structured band and a non-structured permeable support band,
• subsequently drying the tissue paper web on a heated surface and
• subsequently calendering the tissue paper web.

Preferably, the method according to the invention produces tissue paper, such as, for example, toilet paper, cosmetic paper or tissue paper.

The invention will be explained in more detail below with reference to an embodiment with reference to the drawing.

The single figure of the drawing shows a schematic representation of an exemplary embodiment of an apparatus 10 for producing a fibrous web, which in the present case is, for example, a tissue web 22.

A headbox 12 delivers a stock suspension jet into an inlet gap 14, which in the region of a forming roller 16 between an inner circumferential permeable structured band 18 and an outer circumferential Formierieb 20 is formed, which converge in the region of the forming roller 16 and are then performed together around this forming roller 16.

The structural band 18 may in particular be a three-dimensionally structured sieve.

The Formiersieb 20 has the tissue web 22 facing a relatively smooth compared to the respective side of the structural band 18 side.

In contrast, the tissue web 22 facing side of the structural band 18 has recessed areas and relatively elevated areas, wherein the tissue web 22 is formed in these recessed and raised areas of the structural band 18.

The structural band 18 may be formed, for example, by a TAD screen.

In the area of the forming roller 16, the tissue web 22 is substantially dewatered by the outer forming wire 20. Subsequently, the forming fabric 20 in the region of a deflection roller 24 is again separated from the tissue web 22, which is guided together with the structure band 18 on to a pressing zone 26, in which the tissue web 22 between the structural band 18 and a circumferential, non-structured permeable support band 28 lying is pressed.

The permeable support belt 28 may in particular be a felt. In the region of the press zone 26, pressure is exerted on the structure band 18, the tissue web 22 and the support band 28 in such a way that the tissue web 22 is dewatered in the direction of the support band 28 formed, for example, by a felt.

Since the tissue web 22 in the press zone 26 is dewatered in the direction of the permeable support belt 28, and the structural band passed through this press zone 26 in the present embodiment is identical to the structural belt on which the tissue web 22 has been formed, the bulky portions of the tissue web 22 become less strongly compressed than the less voluminous sections, so that as a result the voluminous structure of the voluminous sections concerned is retained.

In the present case, the dewatering pressure for the tissue web 22 in the press zone 26 is generated at least in sections simultaneously by a gas flow and by a mechanical pressing force.

The gas stream first flows through the structure band 18, then the tissue web 22 and finally the permeable support band 28.

As can be seen with reference to FIG. 1, the gas flow in the present case is generated by a suction zone 30 of a suction roll 32.

The alternative and additionally applied mechanical force is produced by guiding the structure band 18, the tissue web 22 and the support band 28 in the press zone 26 between a tensioned press belt 34 and a smooth surface, which is formed here by the roller 32, for example ,

The pressing zone 26 is at least substantially defined by the wrap area of the press belt 34 around the lateral surface of the suction roll 32, wherein this wrap is determined by the distance between the two guide rollers 36, 38.

Subsequent to the suction roller 32, the tissue web 22, together with the structural band 18, is first guided via a suction box 40 and then through a press nip 44 formed on a drying cylinder, namely a Yankee cylinder 42. In this case, the tissue web 22 lies in this press nip 44 between the structure band 18 and the smooth surface of the Yankee cylinder 42. The press nip 44 is formed in the present case by a shoe press nip. The Yankee cylinder 42 is thus assigned a shoe press unit, here a shoe press roll 46, for forming the press nip 44. As can be seen from FIG. 1, a hood 62 can be assigned to the Yankee cylinder 42.

Because the tissue web has been formed between the structural band 18 and the relatively smooth forming fabric 20, only the side of the tissue web 22 formed on the structure band 18 has a wavy surface. In contrast, the surface of the tissue web 22 formed on the smooth forming fabric 20 is relatively smooth. With this smooth side, the tissue web 22 in the press nip 44 now comes into contact with the surface of the Yankee cylinder 42. The tissue web 22 thus touches the Yankee cylinder with a relatively large area. After the structured strip 18 guided by the press nip 44 in the present exemplary embodiment is identical to the structure strip on which the tissue web 22 has been formed, it is also ensured that the voluminous regions of the tissue web 22 are practically not pressed in this press nip 44 either. In contrast, the less bulky areas of the tissue web 22 are pressed, whereby the strength of the tissue web 22 is further increased.

Following the press nip 44, the structure band 18 is separated from the tissue web 22, while the tissue web 22 on the Yankee cylinder 42 is guided to a scraper 48, whereby the tissue web 22 is creped and lifted off the Yankee cylinder 42.

The tissue web 22 is then fed to a calender 64 and subsequently to a reeling or unwinding device 50 in which it is wound up into a reel 54 with the aid of a pressure roller 52.

The tissue web 22 is therefore transferred in the region of the press nip 44 from the structure band 18 onto the surface of the Yankee cylinder 42. In this case, the surface of the Yankee cylinder 42 is scraped off continuously, for example by means of the scraper 48, and subsequently coated again by means of a coating device 56, so that a new coating is always present in the press nip 44. Via another scraper 70, the surface of the Yankee cylinder 42 is cleaned.

The calender 64 comprises a calender nip 66 formed between two hard rolls 64 ', 64 "through which the fibrous web 22 passes, and the two calender rolls 66', 66" are not heated. They are each formed by a chill roll and uncoated.

As can be seen from FIG. 1, the calender 64 comprises only these two hard rollers 64 ', 64 ".

The line load generated in the calendering nip 66 is preferably <10 kN / m.

Subsequent to the calender 64, the tissue web 22 is fed to the take-up device 50, which comprises a winding core 68 and a pressure roller 52 which can be applied or pressed against the winding 54 forming on the winding core 68. In order to maintain the previously achieved relatively high volume of the tissue web 22, the line force in the winding nip between the pressure roller 52 and the winding 54 is preferably selected to be ≦ 0.2 kN / m.

As can be seen from Figure 1, the winding core 68 is driven in the present embodiment.

As a gas stream, which in the press zone 26 first the structural band 18, then the tissue web 22 and finally the support belt 28 can flow through, in particular an air flow and / or vapor flow are generated.

As an alternative or in addition to the suction roll 32, the gas flow can also be generated at least partially by means of an overpressure hood or steam blower box 58 arranged on the side of the permeable structure strip 18.

As already mentioned, a three-dimensionally structured sieve, for example a TAD sieve, can be used in particular as a structural band 18.

As support band 28, as already mentioned, in particular a drainage band can be provided.

The relatively recessed regions and the relatively elevated regions of the structure band 18 are preferably designed and arranged relative to one another such that a maximum of 35% and preferably not more than 25% of the structural band 18 is pressed in the press nip 44 formed with the Yankee cylinder 42.

LIST OF REFERENCE NUMBERS

10

contraption

12

headbox

14

inlet gap

16

forming roll

18

structured band

20

forming fabric

22

tissue web

24

deflecting

26

press zone

28

support band

30

suction zone

34

press belt

36

deflecting

38

deflecting

40

suction box

42

Yankee cylinder

44

press nip

46

Shoe press roll

48

scraper

50

takeup

52

pressure roller

54

reel

56

coater

58

Overpressure hood, steam box

62

Hood

64

calender

64 '

Calender roll, hard roll

64 "

Calender roll, hard roll

66

calender nip

68

winding core

70

scraper

Claims (34)

Apparatus (10) for producing a fibrous web (22), in particular tissue web, with a press zone (26) through which the fibrous web (22) together with a circumferential permeable structured band (18) and an unstructured permeable support band (28) between the structural band (18) and support belt (28) are guided lying, and one on a drying cylinder (42) provided by press nip (44) through which the fibrous web (22) together with the structural band (18) between the structural band (18) and drying cylinder (42) lying is passed, wherein the fibrous web is guided after the drying cylinder (42) by a calender (64). Device according to claim 1,
characterized,
that the calender (64) comprises a between two hard rolls (64 ', 64 ") formed calender nip (66) through which the fibrous web (22) is passed. Device according to claim 2,
characterized,
that the two calender rolls (64 ', 64 ") are not heated. Device according to claim 2 or 3,
characterized,
that the two calender rolls (64 ', 64 ") are each formed by a chill roll. Device according to one of the preceding claims,
characterized,
that the two calender rolls (64 ', 64 ") are each uncoated. Device according to one of the preceding claims,
characterized,
that the calender (64), only two rollers (64 ', 64 ") comprises. Device according to one of the preceding claims,
characterized,
that in the calender nip (66) generated line load <10 kN / m. Device according to one of the preceding claims,
characterized,
that the fibrous web (22) is fed to a winding device (50) following the calender (64). Device according to claim 8,
characterized,
in that the winding device (50) comprises a winding core (68) and a pressure roller (52) which can be applied to the winding (54) forming on the winding core (68). Device according to claim 9,
characterized,
that the line force in the winding nip between the pressing roller (52) and winding (54) is ≤ 0.2 kN / m. Device according to one of the preceding claims,
characterized,
that the winding core (68) is driven. Device according to one of the preceding claims,
characterized,
that the pressure roller (52) is driven. Device according to one of the preceding claims,
characterized,
in that the fibrous web (22) is fed to the take-up device (50) by means of a sieve belt. Device according to one of the preceding claims,
characterized,
in that the fibrous web (22) is formed in a foliation zone on the structural band (22). Device according to one of the preceding claims,
characterized,
that the drying cylinder is formed by a Yankee cylinder (42). Device according to one of the preceding claims,
characterized,
that the pressing zone (26) is on the supporting belt (28) adjacent side bounded by an at least substantially smooth surface. Device according to one of the preceding claims,
characterized,
that the press zone (26) on the support band (28) adjacent side bordering preferably smooth surface is formed by a curved surface. Device according to claim 17,
characterized,
in that the curved surface delimiting the pressing zone (26) on the side adjacent to the support belt (28) is formed by a rotating roller (32). Device according to one of the preceding claims,
characterized,
in that means (30, 32) for generating a gas stream in the region of the pressing zone (26) are provided, through which flows the structural band (18), the fibrous web (22) and the support band (28). Device according to claim 19,
characterized,
that the gas flow first flows through the structure band (18), then the fibrous web (22) and finally the support band (28). Device according to claim 19 or 20,
characterized,
in that means (30, 32) for generating an air stream and / or means for generating a vapor stream are provided. Device according to one of claims 19 to 21,
characterized,
in that the means for generating a gas stream comprise a rotating suction roll (32) provided with a suction zone (30) which delimits the pressing zone (26) on the side adjacent to the support band (28). Device according to one of claims 19 to 21,
characterized,
in that the means for generating a gas flow comprise a flat or curved suction box which delimits the pressing zone (26) on the side adjacent to the support belt (28). Device according to one of claims 19 to 23,
characterized,
that the means for generating a gas stream comprise one on the side of the permeable structured belt arranged (18) pressure hood (58). Device according to one of the preceding claims,
characterized,
that the structural band (18), the fibrous web (22) and the support band (28) can be pressed against the preferably smooth surface by means of a press belt (34) under tension. Device according to claim 25,
characterized,
in that the preferably smooth, curved surface is formed by a rotating roller (32). Device according to one of the preceding claims,
characterized,
in that a structured sieve is provided as the structural band (18). Device according to one of the preceding claims,
characterized,
in that a TAD sieve is provided as the structural band (18). Device according to one of the preceding claims,
characterized,
that is provided as the supporting belt (28) a dewatering belt, in particular felt. Device according to one of the preceding claims,
characterized,
in that the relatively recessed area and the relatively elevated area of the structural strip (18) are designed and arranged relative to one another such that a maximum of 35% and preferably at most 25% of the structural strip (18) is pressed in the press nip (44). Device according to one of the preceding claims,
characterized,
that the drying cylinder provided (42) press nip (44) is formed by a shoe press nip. Device according to one of the preceding claims,
characterized,
in that the fibrous web (22) in the region of the press nip (44) is transferred from the structural band (18) to the surface of the drying cylinder (42). Method for producing a tissue web (22), in particular a tissue paper web, comprising the following steps: - Pressing the between a permeable structured band (18) and a non-structured permeable support band (28) guided tissue web (22) - Subsequent drying of the tissue web (22) on a heated surface and - subsequently calendering the tissue web (22). Hygiene paper, such as toilet paper, cosmetic paper or tissue paper made by the method of claim 33.

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