EP1770209B1 - Method and device for producing a tissue web - Google Patents

Method and device for producing a tissue web Download PDF

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Publication number
EP1770209B1
EP1770209B1 EP06114192A EP06114192A EP1770209B1 EP 1770209 B1 EP1770209 B1 EP 1770209B1 EP 06114192 A EP06114192 A EP 06114192A EP 06114192 A EP06114192 A EP 06114192A EP 1770209 B1 EP1770209 B1 EP 1770209B1
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EP
European Patent Office
Prior art keywords
belt
fibrous web
structured
yankee cylinder
process according
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Not-in-force
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EP06114192A
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German (de)
French (fr)
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EP1770209A1 (en
Inventor
Luiz Carlos Silva
Thomas Scherb
Davilo Oyakawa
Rogerio Berardi
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Voith Patent GmbH
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Voith Patent GmbH
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Publication of EP1770209A1 publication Critical patent/EP1770209A1/en
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/14—Making cellulose wadding, filter or blotting paper
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S162/00—Paper making and fiber liberation
    • Y10S162/90—Papermaking press felts

Definitions

  • the invention relates to a method and an apparatus for producing a fibrous web, in particular tissue web.
  • Tissue paper ideally has a high absorbency or a high water absorption capacity in conjunction with a high tear resistance.
  • the absorbency and the water absorption capacity are essentially determined by the volume and porosity of the tissue paper.
  • tissue web 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. While the tissue web is passed over the Yankee drying cylinder, it is held by a string.
  • TAD Through-Air-Drying
  • the following table contains the usual values for some known parameters: ⁇ u> Table 1 ⁇ / u> Amount of roll coating material mg / m 2 ; mL / min Blade or scraper load kN / m conventional 1 - 3; 15 - 25 ⁇ 2.5 Tissue machine 2 - 3 TAD machines 5 - 15; 80 - 100 ⁇ 7.0 6-7
  • the invention has for its object to provide an improved method and an improved device of the type mentioned.
  • the aim is to ensure the highest possible quality of the tissue paper and at the same time to ensure that this high product quality can also be achieved with a smaller amount of coating material for the Yankee cylinder and a lower blade or scraper load.
  • the tissue web After the fibrous web is pressed in the press zone between the structural band and a circulating, unstructured, ie relatively smooth permeable support band, the tissue web can be brought into contact with the Yankee dryer cylinder with a relatively smooth side, while on the other hand due to the other railway side lying structural band only a part the fibrous or tissue web is pressed. 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.
  • the fibrous web When pressing the fibrous web in the press zone between the structural band and the circulating, unstructured, i. relatively smooth permeable support band, the fibrous web is preferably dewatered in the direction of the permeable support band.
  • the pressing pressure is preferably 1.5 bar or less.
  • the fibers are urged in the direction of the relatively flat or smooth surface of the supporting band, in particular formed 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 relevant gas stream first flows through the permeable structural band, and then the fibrous web and then the preferably permeable support band.
  • the gas stream in question first flows through the fibrous web and then through the structured web.
  • the fibrous web thus does not receive a smooth surface in such a conventional TAD method.
  • the differential pressure generated in the conventional TAD method is relatively small.
  • the coating of the Yankee cylinder also ensures an improved transfer of the fibrous web from the structural band to the surface of the Yankee cylinder. Furthermore, by the coating the heat transfer from the Yankee cylinder to the fibrous web significantly improved. In addition, a blistering, a lifting of the web, etc. counteracted. After at least a portion of the coating is removed again by means of the scraper in question, no dirt can accumulate.
  • an adhesive coating material is preferably applied to the surface of the Yankee cylinder.
  • the amount of coating material continuously applied to the surface of the Yankee cylinder is in a range from about 3 to about 9 mg / m 2 .
  • a scraper or the like is advantageously loaded so as to give a line force in a range of about 3 to about 7 kN / m, preferably in a range of about 5 to about 6 kN / m.
  • the scrape load in question can thus be significantly reduced without any loss of quality.
  • the fibrous web is formed on a circumferential permeable structured band, thereby filling the recesses of the structured band with fibers instead of sucking the fibers of an already formed web into the recesses of the structure band as in a conventional TAD method.
  • a voluminous fibrous web is produced in comparison with the method in which a smoothly formed fibrous web is pressed into the depressions of a structural band.
  • the effect caused by the dewatering of the fibrous web in the press zone in the direction of the support band continues reinforced that almost 100% surface of the relevant side of the fibrous web can come into contact with the Yankee cylinder.
  • the pressing zone on the side adjacent to the support band is expediently delimited by an at least substantially smooth surface.
  • this smooth surface can be formed in particular by a rotating roller.
  • a gas stream is generated, which flows through the structural band, the fibrous web and the support band, wherein the gas stream preferably first flows through the structural band, then the fibrous web and finally the support band.
  • an air flow and / or vapor flow can be generated as gas flow.
  • the gas stream is generated at least partially by means of a suction zone of a rotating suction roll, which limits the pressing zone on the side adjacent to the support band.
  • the gas flow can be generated, at least partially, but also by means of a flat or curved suction box or the like, which limits the pressing zone on the side adjacent to the support belt.
  • an overpressure hood arranged on the side of the permeable structural band.
  • the overpressure hood may, for example, be a steam blower box.
  • the structural band, the fibrous web and the support band can advantageously also be pressed against an at least substantially smooth surface by means of a press belt under tension.
  • the smooth surface can in particular be formed again by a rotating roller.
  • a structured sieve is expediently used as a structural band.
  • a TAD sieve As a structural band, for example, a TAD sieve can be used.
  • the fibrous web is formed as previously described. In principle, however, it may also be expedient in certain cases to form the fibrous web in that the pulp suspension is sucked into the structure of the permeable structured strip by means of a suction device.
  • the support band may in particular be a drainage band.
  • 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 Yankee press nip is a shoe press nip. If the fibrous web to be produced does not require bulkiness but should preferably achieve a high dry content with high production output, the press nip formed on the Yankee cylinder may alternatively be formed with a suction press roll or a press roll.
  • only one scraper is assigned to the Yankee cylinder, by which on the one hand at least a part of the coating is removed and on the other hand the fibrous web is creped and lifted off the cylinder surface.
  • the Yankee cylinder is assigned a first scraper for removing at least part of the coating and a second scraper, by means of which the fibrous web is creped and lifted off the cylinder surface.
  • the fibrous web removed again from the Yankee cylinder is then wound up.
  • a device for producing a fibrous web, in particular tissue web with a forming zone in which the fibrous web is formed on a circumferential permeable structured band, a press zone through which the fibrous web between the structural band and a circulating, not structured permeable support belt is passed lying, a tensioned press belt by means of which the structural band, the fibrous web and the support band are pressed against an at least substantially smooth surface, provided on a Yankee press nip, passed through the fibrous web together with the structural band With the fibrous web in the region of this press nip being transferred from the structural band to the surface of the Yankee cylinder, at least one scraper continuously scrape off the surface of the Yankee cylinder and a coating device, by which the Yankee cylinder is subsequently recoated so that in the press nip is always a renewed roller coating.
  • the coating device is controlled or regulated such that the amount of accelerating material continuously applied to the surface of the Yankee cylinder is in a range from about 3 to about 9 mg / m 2 .
  • a scraper is provided for continuously scraping the surface of the Yankee cylinder and for creping the fibrous web, which scraper is loaded so that a line force in a range of about 3 to about 7 kN / m, preferably in a range of about 5 to about 6 kN / m.
  • FIG. 1 shows a schematic representation of an exemplary embodiment of an apparatus 10 for producing a fibrous web, which in the present case is a tissue web.
  • a headbox 12 delivers a stock suspension jet into an inlet gap 14 which is formed in the region of a forming roller 16 between an inner circumferential permeable structured band 18 and an outer peripheral Formiersieb 20 which converge in the region of the forming roller 16 and are then guided 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 relative to the respective side of the structural band 18 relative smooth side.
  • 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 elevated areas of the structural band 18.
  • the structural band 18 may be formed, for example, by a TAD screen.
  • 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.
  • 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.
  • the tissue web 22 in the press zone 26 is dewatered in the direction of the permeable support belt 28 and the structural band 18 passed through this press zone 26 is identical to the structural band on which the tissue web 22 has been formed, the bulky portions of the tissue web 22 are less compressed than the less bulky sections, so that, as a result, the voluminous structure of the respective bulkier sections is preserved.
  • 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.
  • the gas flow is generated in the present case by a suction zone 30 of a suction roll 32.
  • the alternatively or additionally applied mechanical force is generated 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.
  • the tissue web 22 In the area 40, through which the tissue web 22 is guided together with the structural band 18, the tissue web 22 can be subjected to at least one further drying step.
  • the tissue web 22 is guided together with the structural band 18 by a press nip 44 formed on a drying cylinder, namely a Yankee cylinder 42.
  • a press nip 44 formed on a drying cylinder, namely a Yankee cylinder 42.
  • 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.
  • a shoe press roll 46 for forming the press nip 44.
  • the Yankee cylinder 42 may be associated with a hood 6262.
  • the tissue web 22 formed between the structural band 18 and the relatively smooth forming fabric 20 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.
  • the structural band 18 passed through the press nip 44 is identical to the structural band on which the tissue web 22 has been formed, it is 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.
  • the structure band 18 is separated from the tissue web 22, which is guided on the Yankee cylinder 42 as far as a scraper 48, whereby the tissue web 22 is creped and lifted off the Yankee cylinder 42. Subsequently, the tissue web 22 is fed to a take-up unit 50, in which it is wound up by means of a pressure roller 52 into a winding 54.
  • 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.
  • 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 renewed coating is always present in the press nip 44.
  • an adhesive coating material can be applied to the surface of the Yankee cylinder 42.
  • the amount of coating material continuously applied to the surface of the Yankee cylinder 42 is suitably in a range of about 3 to about 9 mg / m 2 .
  • a scraper or the like, here, for example, the tissue web creping scrapers 48 may be loaded so that a line force in a range from about 3 to about 7 kN / m, preferably in one Range of about 5 to about 6 kN / m.
  • an air stream and / or vapor stream can be generated in particular.
  • the gas stream can also be generated at least partially by means of an overpressure hood 58 arranged on the side of the permeable structure strip 18.
  • a structured sieve for example a TAD sieve, can be used in particular as a structural band 18.
  • 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.
  • FIG. 2 shows an enlarged view of a portion of the Yankee cylinder 42, which is associated with the coating device 56 and a scraper 48 through continuously removed at least a portion of the applied coating 60 again.
  • FIG. 3 shows one with the FIG. 2 Comparable partial schematic representation of the Yankee cylinder 42 with a single associated scraper 48, scraped by the one hand, the surface of the Yankee cylinder 42 and at least a portion of the applied coating is removed again, and by the other hand, the tissue web 22 creped and the Yankee Cylinder 42 is lifted.
  • FIG. 4 shows one with the FIG. 3 However, in the present case, two scrapers 48 ', 48 "are associated with the Yankee cylinder 42.
  • a first scraper 48' serves to crepe the fibrous web 22 and from the cylinder surface
  • the second scraper 48 " at least a portion of the coating 60, including dirt accumulated on the cylinder surface, is removed.

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Abstract

The method involves pressing the fibre web (22) in a pressing zone (26) between a revolving permeable structured belt (18) and a revolving non-structured permeable support belt (28) and then supplying the fibre web and structured belt to a press nip (44) mounted on a Yankee cylinder (42). The fibre web is transferred in the press nip area from the structured belt to the surface of the cylinder, the surface of the cylinder is constantly scraped and then re-coated so that a renewed coating is always present in the press nip. Independent claim describes device for manufacturing tissue web which includes a revolving permeable structured belt , a pressing zone, a non-structured permeable support belt and a press nip on a Yankee cylinder which has a constantly replaced roller coating and a scraper (48).

Description

Die Erfindung betrifft ein Verfahren sowie eine Vorrichtung zur Herstellung einer Faserstoffbahn, insbesondere Tissuebahn.The invention relates to a method and an apparatus for producing a fibrous web, in particular tissue web.

Tissuepapier besitzt idealerweise eine hohe Saugfähigkeit bzw. ein hohes Wasseraufnahmevermögen in Verbindung mit einer hohen Reißfestigkeit. Dabei werden die Saugfähigkeit und das Wasseraufnahmevermögen wesentlich durch das Volumen und Porosität des Tissuepapiers bestimmt.Tissue paper ideally has a high absorbency or a high water absorption capacity in conjunction with a high tear resistance. The absorbency and the water absorption capacity are essentially determined by the volume and porosity of the tissue paper.

Zur Erhöhung des Volumens wurde bereits vorgeschlagen, die Tissuepapierbahn bei deren Herstellung nur zonal zu pressen, um neben den gepressten reißfesteren Bereichen auch lediglich leicht gepresste oder ungepresste voluminösere Bereiche zu erhalten.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.

Bei der Herstellung von Tissuepapier wird die Tissuebahn in einem letzten Trocknungsschritt über die Mantelfläche eines beheizten Yankee-Trockenzylinders geführt, bevor das fertige Produkt von diesem gekreppt wird. Während die Tissuebahn über den Yankee-Trockenzylinder geführt wird, wird sie von einer Bespannung gehalten.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. While the tissue web is passed over the Yankee drying cylinder, it is held by a string.

Insbesondere bei der Herstellung von Tissuepapier mit voluminösen Bereichen, die bei der Entwässerung nur geringfügig komprimiert wurden, besteht nun aber das Problem, dass das Tissuepapier mit zu geringem Trockengehalt mit der heißen Mantelfläche des Yankee-Trockenzylinders in Kontakt kommen. Dieses Problem tritt verstärkt bei hohen Maschinenlaufgeschwindigkeiten auf, da hier die Entwässerungszeiten weiter reduziert werden und die voluminösen Bereiche entsprechend noch mehr Feuchtigkeit mit sich tragen.In particular, in the production of tissue paper with voluminous areas, which were only slightly compressed during drainage, but now there is the problem that the tissue paper with too low dry content come into contact with the hot surface of the Yankee drying cylinder. This problem occurs increasingly at high machine speeds, since here the drainage times be further reduced and carry the voluminous areas according to even more moisture with it.

Aufgrund des zu geringen Trockengehalts entsteht beim Kontakt der Tissuebahn mit der beheizten Mantelfläche des Yankee-Trockenzylinders Wasserdampf zwischen der heißen Mantelfläche und der Tissuebahn, was dazu führen kann, dass die Bahn von der Walzenmanteffläche abhebt.Due to the too low dry content, water vapor forms between the hot jacket surface and the tissue web upon contact of the tissue web with the heated jacket surface of the Yankee dryer cylinder, which may cause the web to lift off the roll mantle surface.

Infolge des Abhebens der Tissuebahn von der Walzenmantelfläche kann es zu Problemen im Hinblick auf die Runnability bis zum Abriss der Tissuebahn kommen.As a result of the lifting off of the tissue web from the roll jacket surface, problems with regard to runnability can occur until the tissue web is torn off.

Des weiteren kann aufgrund der Bildung von Wasserdampf zwischen der Tissuebahn und der beheizten Mantelfläche des Yankee-Trockenzylinders- eine Blasen- und Lochbildung in der Tissuebahn auftreten.Furthermore, due to the formation of water vapor between the tissue web and the heated jacket surface of the Yankee dryer cylinder, bubble and hole formation can occur in the tissue web.

Es ist bereits bekannt, den Trocken- bzw. Yankee-Zylinder zu beschichten, um den bei einer Übertragung der Faserstoffbahn von einem TAD (Through-Air-Drying)-Sieb auf die Oberfläche des Yankee-Zylinders auftretenden Problemen zu begegnen. Es wurde auch bereits eine Schaberanordnung vorgeschlagen, bei der ein Schaber die Faserstoffbahn kreppt und vom Yankee-Zylinder abschabt, und zumindest ein weiterer Schaber dazu vorgesehen ist, eine Schmutz enthaltende Lage der Walzenbeschichtung abzutragen.It is already known to coat the dry or Yankee cylinder in order to counteract the problems which occur during transfer of the fibrous web from a TAD (Through-Air-Drying) screen to the surface of the Yankee cylinder. A scraper arrangement has also been proposed in which a scraper creps the fibrous web and scrapes off the Yankee cylinder, and at least one other scraper is provided to remove a soil-containing layer of the roll coating.

Aus dem Dokument US2004/0173333 A1 ist ein Verfahren zur Herstellung einer Tissuebahn mittels einer Luftpresse offenbart. Bei diesem Verfahren wird die Bahn nach deren Bildung und Entwässerung in die Oberflächenstruktur einer relativ groben Bespannung eingeformt, um der Bahn eine strukturierte Oberfläche zu verleihen. Durch die Anwendung einer Druckdifferenz in einer rundum abgedichteten Luftpresse wird die Bahn vor einem beheizten Trockenzylinder bis zu einer Konsistenz von 30 bis 40% entwässert und anschließend getrocknet.From the document US2004 / 0173333 A1 discloses a method of making a tissue web by means of an air press. In this process, the web, after being formed and dewatered, is molded into the surface structure of a relatively coarse fabric to impart a textured surface to the web. By applying a pressure difference in a completely sealed Air press is dewatered the web before a heated drying cylinder to a consistency of 30 to 40% and then dried.

Derzeit existieren zwei unterschiedliche Verfahren zur Herstellung von Tissuepapier. Zum einen handelt es sich um das herkömmliche Tissue-Herstellungsverfahren, bei dem die Faserstoffbahn auf dem Yankee-Zylinder gebildet, gepresst und getrocknet wird. Zum anderen existiert das sogenannte TAD-Herstellungsverfahren (TAD = Through-Air-Drying), bei dem die Faserstoffbahn zwischen der Blattbildungszone und der Pressenpartie mittels einer Luftströmung getrocknet wird. Dieses Verfahren bringt eine hohe Papierqualität mit sich.There are currently two different methods of making tissue paper. First, it is the conventional tissue-making process in which the fibrous web is formed, pressed and dried on the Yankee cylinder. On the other hand, there is the so-called TAD manufacturing process (TAD = Through-Air-Drying), in which the fibrous web between the Sheet forming zone and the press section is dried by means of an air flow. This process brings a high paper quality with it.

Um die zuvor genannten Probleme in den Griff zu bekommen, müssen verschiedene Parameter, insbesondere solche, die den Bereich des Yankee-Zylinders betreffen, in geeigneter Weise gewählt werden.In order to deal with the above-mentioned problems, various parameters, particularly those concerning the area of the Yankee cylinder, must be suitably selected.

In der folgenden Tabelle sind für einige bekannte Parameter bisher übliche Werte eingetragen: Tabelle 1 Menge an Walzenbeschichtungsmaterial mg/m2; mL/Min Klingen- oder Schaberbelastung kN/m herkömmliche 1 - 3; 15 - 25 ∼ 2,5 Tissue-Maschine 2 - 3 TAD-Maschinen 5 - 15; 80 - 100 ∼ 7,0 6-7 The following table contains the usual values for some known parameters: <u> Table 1 </ u> Amount of roll coating material mg / m 2 ; mL / min Blade or scraper load kN / m conventional 1 - 3; 15 - 25 ~ 2.5 Tissue machine 2 - 3 TAD machines 5 - 15; 80 - 100 ~ 7.0 6-7

Die bisher erforderliche hohe Menge an Beschichtungsmaterial zur Beschichtung des Yankee-Zylinders bringt offensichtlich wirtschaftliche Nachteile mit sich. Dasselbe gilt für die bisher erforderliche relativ hohe Klingen- oder Schaberbelastung.The previously required high amount of coating material for coating the Yankee cylinder obviously brings economic disadvantages. The same applies to the previously required relatively high blade or scraper load.

Der Erfindung liegt die Aufgabe zugrunde, ein verbessertes Verfahren sowie eine verbesserte Vorrichtung der eingangs genannten Art zu schaffen. Dabei soll eine möglichst hohe Qualität des Tissuepapiers gewährleistet und gleichzeitig sichergestellt sein, dass diese hohe Produktqualität auch mit einer geringeren Menge an Beschichtungsmaterial für den Yankee-Zylinder und einer geringeren Klingen- bzw. Schaberbelastung erreicht werden kann.The invention has for its object to provide an improved method and an improved device of the type mentioned. The aim is to ensure the highest possible quality of the tissue paper and at the same time to ensure that this high product quality can also be achieved with a smaller amount of coating material for the Yankee cylinder and a lower blade or scraper load.

Diese Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren zur Herstellung einer Faserstoffbahn, insbesondere Tissuebahn, mit den folgenden Schritten:

  1. a) die Faserstoffbahn wird in einer Presszone zwischen dem Strukturband und einem umlaufenden, nicht strukturierten permeablen Stützband liegend gepresst,
  2. b) das Strukturband, die Faserstoffbahn und das Stützband werden mittels eines unter Spannung stehenden Pressbandes gegen eine Fläche gepresst.
  3. c) die Faserstoffbahn und das Strukturband werden einem an einem Yankee-Zylinder vorgesehenen Pressnip zugeführt,
  4. d) die Faserstoffbahn wird im Bereich des Pressnips von dem Strukturband auf die Oberfläche des Yankee-Zylinders übertragen,
  5. e) die Oberfläche des Yankee-Zylinders wird laufend abgeschabt und anschließend wieder neu beschichtet, so dass im Pressnip stets eine erneüerte Beschichtung vorliegt.
This object is achieved by a method for producing a fibrous web, in particular tissue web, with the following steps:
  1. a) the fibrous web is pressed in a press zone between the structural band and a circulating, non-structured, permeable support band,
  2. b) the structural band, the fibrous web and the support band are pressed against a surface by means of a press belt under tension.
  3. c) the fibrous web and the structural band are fed to a press nip provided on a Yankee cylinder,
  4. d) the fibrous web is transferred from the structural band to the surface of the Yankee cylinder in the region of the press nip,
  5. e) the surface of the Yankee cylinder is scraped off continuously and then recoated, so that there is always a renewed coating in the press nip.

Mit diesem erfindungsgemäßen Verfahren wird eine hohe Qualität des Tissuepapiers bei gleichzeitig reduzierter erforderlicher Menge an Beschichtungsmaterial für den Yankee-Trockenzylinder und reduzierter Klingen- bzw. Schaberbelastung erreicht. Dass optimale Ergebnisse insbesondere auch bei einer reduzierten Menge an Beschichtungsmaterial und reduzierter Schaberbelastung erreicht werden, ist unter anderem auf folgendes zurückzuführen:With this method according to the invention, a high quality of the tissue paper is achieved with simultaneously reduced required amount of coating material for the Yankee drying cylinder and reduced blade or scraper load. The fact that optimal results are achieved, in particular even with a reduced amount of coating material and reduced scraper load, can be attributed, inter alia, to the following:

Nachdem die Faserstoffbahn in der Presszone zwischen dem Strukturband und einem umlaufenden, nicht strukturierten, d.h. relativ glatten permeablen Stützband liegend gepresst wird, kann die Tissuebahn mit einer relativ glatten Seite mit dem Yankee-Trockenzylinder in Kontakt gebracht werden, während andererseits aufgrund des auf der anderen Bahnseite liegenden Strukturbandes lediglich ein Teil der Faserstoff- bzw. Tissuebahn gepresst wird. Anders als bei den herkömmlichen TAD-Maschinen kann die Tissuebahn also mit annähernd 100 % Oberfläche der betreffenden Seite mit dem Yankee-Zylinder in Kontakt kommen, während nur ein Teil davon gepresst wird.After the fibrous web is pressed in the press zone between the structural band and a circulating, unstructured, ie relatively smooth permeable support band, the tissue web can be brought into contact with the Yankee dryer cylinder with a relatively smooth side, while on the other hand due to the other Railway side lying structural band only a part the fibrous or tissue web is pressed. 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.

Bei der Pressung der Faserstoffbahn in der Presszone zwischen dem Strukturband und dem umlaufenden, nicht strukturierten, d.h. relativ glatten permeablen Stützband wird die Faserstoffbahn vorzugsweise in Richtung des permeablen Stützbandes entwässert. Der Pressdruck beträgt hierbei vorzugsweise 1,5 bar oder weniger.When pressing the fibrous web in the press zone between the structural band and the circulating, unstructured, i. relatively smooth permeable support band, the fibrous web is preferably dewatered in the direction of the permeable support band. The pressing pressure is preferably 1.5 bar or less.

Indem die Faserstoffbahn zur vom Strukturband abgewandten Seite hin durch das Stütz- und/oder Entwässerungsband hin weiter entwässert wird, werden die Fasern in Richtung der relativ ebenen oder glatten Oberfläche des insbesondere durch ein Entwässerungsband gebildeten Stützbandes gedrängt. Die Entwässerung kann beispielsweise durch ein entsprechend hohes Vakuum und/oder mechanisch, beispielsweise mittels eines Spannbandes erfolgen, durch das das Strukturband, die Faserstoffbahn und das Stützband gegen eine vorzugsweise glatte Fläche gepresst werden. Der betreffende Gasstrom durchströmt erfindungsgemäß also zunächst das permeable Strukturband, und dann die Faserstoffbahn und anschließend das vorzugsweise permeable Stützband. Demgegenüber durchströmt bei einem herkömmlichen TAD-Verfahren der betreffende Gasstrom zunächst die Faserstoffbahn und dann das Strukturband. Anders als bei der erfindungsgemäßen Lösung erhält die Faserstoffbahn bei einem solchen herkömmlichen TAD-Verfahren also keine glatte Fläche. Abgesehen davon ist der beim herkömmlichen TAD-Verfahren erzeugte Differenzdruck relativ gering.As the fibrous web is further dewatered towards the side 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 supporting band, in particular formed 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. According to the invention, the relevant gas stream first flows through the permeable structural band, and then the fibrous web and then the preferably permeable support band. In contrast, in a conventional TAD method, the gas stream in question first flows through the fibrous web and then through the structured web. 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.

Bei der erfindungsgemäßen Lösung sorgt die Beschichtung des Yankee-Zylinders zudem für eine verbesserte Übertragung der Faserstoffbahn vom Strukturband auf die Oberfläche des Yankee-Zylinders. Des weiteren wird durch die Beschichtung der Wärmeübertrag vom Yankee-Zylinder zur Faserstoffbahn deutlich verbessert. Zudem wird einer Blasenbildung, einem Abheben der Bahn usw. entgegengewirkt. Nachdem mittels des betreffenden Schabers zumindest ein Teil der Beschichtung laufend wieder abgetragen wird, kann sich kein Schmutz anhäufen.In the solution according to the invention, the coating of the Yankee cylinder also ensures an improved transfer of the fibrous web from the structural band to the surface of the Yankee cylinder. Furthermore, by the coating the heat transfer from the Yankee cylinder to the fibrous web significantly improved. In addition, a blistering, a lifting of the web, etc. counteracted. After at least a portion of the coating is removed again by means of the scraper in question, no dirt can accumulate.

Zur optimalen Unterstützung der zuvor genannten Überführung der Faserstoffbahn vom Stützband auf die Oberfläche des Tissue-Zylinders wird bevorzugt ein adhäsives Beschichtungsmaterial auf die Oberfläche des Yankee-Zylinders aufgebracht.For optimum support of the aforementioned transfer of the fibrous web from the support belt to the surface of the tissue cylinder, an adhesive coating material is preferably applied to the surface of the Yankee cylinder.

Gemäß einer vorteilhaften Ausgestaltung des erfindungsgemäßen Verfahrens liegt die kontinuierlich auf die Oberfläche des Yankee-Zylinders aufgebrachte Menge an Beschichtungsmaterial in einem Bereich von etwa 3 bis etwa 9 mg/m2.According to an advantageous embodiment of the method according to the invention, the amount of coating material continuously applied to the surface of the Yankee cylinder is in a range from about 3 to about 9 mg / m 2 .

Zum kontinuierlichen Abschaben der Oberfläche des Yankee-Zylinders wird ein Schaber oder dergleichen vorteilhafterweise so belastet, dass sich eine Linienkraft in einem Bereich von etwa 3 bis etwa 7 kN/m, vorzugsweise in einem Bereich von etwa 5 bis etwa 6 kN/m ergibt. Die betreffende Schaberbelastung kann somit ohne irgendwelche Qualitätseinbußen deutlich reduziert werden.For continuously scraping off the surface of the Yankee cylinder, a scraper or the like is advantageously loaded so as to give a line force in a range of about 3 to about 7 kN / m, preferably in a range of about 5 to about 6 kN / m. The scrape load in question can thus be significantly reduced without any loss of quality.

Vorzugsweise wird die Faserstoffbahn auf einem umlaufenden permeablen strukturierten Band gebildet, wodurch die Vertiefungen des strukturierten Bandes mit Fasern aufgefüllt werden, anstatt dass die Fasern einer bereits gebildeten Bahn wie bei einem herkömmlichen TAD-Verfahren in die Vertiefungen des Strukturbandes gesaugt werden. Hierdurch wird eine im Vergleich zum Verfahren bei dem eine glatt gebildete Faserstoffbahn in die Vertiefungen eines Strukturbandes gepresst wird, voluminöse Faserstoffbahn erzeugt. Des weiteren wird durch die Bildung der Faserstoffbahn zwischen dem permeablen strukturierten Band und einem glatten nicht strukturierten Formiersieb der durch die Entwässerung der Faserstoffbahn in der Presszone in Richtung des Stützbandes bewirkte Effekt weiter verstärkt, dass annähernd 100 % Oberfläche der betreffenden Seite der Faserstoffbahn mit dem Yankee-Zylinder in Kontakt kommen können.Preferably, the fibrous web is formed on a circumferential permeable structured band, thereby filling the recesses of the structured band with fibers instead of sucking the fibers of an already formed web into the recesses of the structure band as in a conventional TAD method. As a result, a voluminous fibrous web is produced in comparison with the method in which a smoothly formed fibrous web is pressed into the depressions of a structural band. Furthermore, by the formation of the fibrous web between the permeable structured band and a smooth non-textured forming fabric, the effect caused by the dewatering of the fibrous web in the press zone in the direction of the support band continues reinforced that almost 100% surface of the relevant side of the fibrous web can come into contact with the Yankee cylinder.

Wie bereits erwähnt, wird die Presszone auf der dem Stützband benachbarten Seite zweckmäßigerweise durch eine zumindest im Wesentlichen glatte Oberfläche begrenzt. Dabei kann diese glatte Oberfläche insbesondere durch eine rotierende Walze gebildet werden.As already mentioned, the pressing zone on the side adjacent to the support band is expediently delimited by an at least substantially smooth surface. In this case, this smooth surface can be formed in particular by a rotating roller.

Von Vorteil ist insbesondere auch, wenn im Bereich der Presszone ein Gasstrom erzeugt wird, der das Strukturband, die Faserstoffbahn und das Stützband durchströmt, wobei der Gasstrom bevorzugt zunächst das Strukturband, dann die Faserstoffbahn und schließlich das Stützband durchströmt.It is particularly advantageous if in the region of the pressing zone, a gas stream is generated, which flows through the structural band, the fibrous web and the support band, wherein the gas stream preferably first flows through the structural band, then the fibrous web and finally the support band.

Als Gasstrom kann insbesondere ein Luftstrom und/oder Dampfstrom erzeugt werden.In particular, an air flow and / or vapor flow can be generated as gas flow.

Gemäß einer zweckmäßigen praktischen Ausgestaltung des erfindungsgemäßen Verfahrens wird der Gasstrom zumindest teilweise mittels einer Saugzone einer rotierenden Saugwalze erzeugt, die die Presszone auf der dem Stützband benachbarten Seite begrenzt.According to an expedient practical embodiment of the method according to the invention, the gas stream is generated at least partially by means of a suction zone of a rotating suction roll, which limits the pressing zone on the side adjacent to the support band.

Der Gasstrom kann zumindest teilweise aber auch mittels eines ebenen oder gekrümmten Saugkastens oder dergleichen erzeugt werden, der die Presszone auf der dem Stützband benachbarten Seite begrenzt.The gas flow can be generated, at least partially, but also by means of a flat or curved suction box or the like, which limits the pressing zone on the side adjacent to the support belt.

Darüber hinaus ist beispielsweise auch denkbar, den Gasstrom zumindest teilweise mittels einer auf der Seite des permeablen Strukturbandes angeordneten Überdruckhaube zu erzeugen. Bei der Überdruckhaube kann es sich bspw. um einen Dampfblaskasten handeln.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. The overpressure hood may, for example, be a steam blower box.

Alternativ oder zusätzlich können das Strukturband, die Faserstoffbahn und das Stützband vorteilhafterweise auch mittels eines unter Spannung stehenden Pressbandes gegen eine zumindest im Wesentlichen glatte Oberfläche gepresst werden. Dabei kann die glatte Oberfläche insbesondere wieder durch eine rotierende Walze gebildet sein.Alternatively or additionally, the structural band, the fibrous web and the support band can advantageously also be pressed against an at least substantially smooth surface by means of a press belt under tension. In this case, the smooth surface can in particular be formed again by a rotating roller.

Als Strukturband wird zweckmäßigerweise ein strukturiertes Sieb eingesetzt.As a structural band, a structured sieve is expediently used.

Als Strukturband kann beispielsweise auch ein TAD-Sieb verwendet werden.As a structural band, for example, a TAD sieve can be used.

Bevorzugt wird die Faserstoffbahn so gebildet, wie dies zuvor beschrieben wurde. Grundsätzlich kann es in bestimmten Fällen jedoch auch zweckmäßig sein, die Faserstoffbahn dadurch zu bilden, dass die Faserstoffsuspension mittels einer Saugeinrichtung in die Struktur des permeablen strukturierten Bandes gesaugt wird.Preferably, the fibrous web is formed as previously described. In principle, however, it may also be expedient in certain cases to form the fibrous web in that the pulp suspension is sucked into the structure of the permeable structured strip by means of a suction device.

Bei dem Stützband kann es sich, wie bereits erwähnt, insbesondere um ein Entwässerungsband handeln.As already mentioned, the support band may in particular be a drainage band.

Bevorzugt sind die relativ vertieften und die relativ erhöhten Bereiche des Strukturbandes derart ausgebildet und relativ zueinander angeordnet, dass maximal 35 % und vorzugsweise maximal 25 % des Strukturbandes im Pressnip gepresst werden. Eine möglichst schonende Pressung wird dadurch erreicht, dass der an dem Yankee-Zylinder vorgesehene Pressnip ein Schuhpressnip ist. Erfordert die herzustellende Faserstoffbahn keine Voluminosität sondern soll bevorzugt ein hoher Trockengehalt bei hoher Produktionsleistung erreicht werden, kann alternativ dazu der am Yankee-Zylinder gebildete Pressnip mit einer Saugpresswalze oder einer Presswalze gebildet werden.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 Yankee press nip is a shoe press nip. If the fibrous web to be produced does not require bulkiness but should preferably achieve a high dry content with high production output, the press nip formed on the Yankee cylinder may alternatively be formed with a suction press roll or a press roll.

Gemäß einer zweckmäßigen praktischen Ausgestaltung des erfindungsgemäßen Verfahrens wird dem Yankee-Zylinder nur ein Schaber zugeordnet, durch den einerseits zumindest ein Teil der Beschichtung abgetragen und andererseits die Faserstoffbahn gekreppt und von der Zylinderoberfläche abgehoben wird.According to an expedient practical embodiment of the method according to the invention, only one scraper is assigned to the Yankee cylinder, by which on the one hand at least a part of the coating is removed and on the other hand the fibrous web is creped and lifted off the cylinder surface.

Nach einer alternativen vorteilhaften Ausgestaltung wird dem Yankee-Zylinder ein erster Schaber zum Abtragen zumindest eines Teils der Beschichtung und ein zweiter Schaber zugeordnet, durch den die Faserstoffbahn gekreppt und von der Zylinderoberfläche abgehoben wird.According to an alternative advantageous embodiment, the Yankee cylinder is assigned a first scraper for removing at least part of the coating and a second scraper, by means of which the fibrous web is creped and lifted off the cylinder surface.

Vorteilhafterweise wird der am Auslauf des Pressnips auftretende Auslaufzwickel zwischen Faserstoffbahn und Strukturband mittels eines Luftmessers beaufschlagt.Advantageously, occurring at the outlet of the press nip Auslaufzwickel between fibrous web and structural band is acted upon by means of an air knife.

Es ist insbesondere auch eine solche Ausgestaltung denkbar, bei der in dem Bereich, in dem das Strukturband von einer mit dem Yankee-Zylinder den Pressnip bildenden Gegenwalze abläuft, der Auslaufzwickel zwischen dem Strukturband und der Gegenwalze mittels eines Luftmessers beaufschlagt wird. Dadurch werden in den Vertiefungen des Strukturbandes sitzende Fasern gelöst, wodurch die Übertragung des Faserstoffbandes auf dem Yankee-Zylinder unterstützt wird. Zudem wird einer Blasenbildung auf der Faserstoffbahn entgegengewirkt.In particular, such a configuration is also conceivable in which, in the area in which the structural strip runs from a counter-roller forming the press nip with the Yankee cylinder, the outlet gusset between the structural band and the counter-roller is acted upon by means of an air knife. As a result, fibers sitting in the depressions of the structural strip are released, which promotes the transfer of the fibrous web on the Yankee cylinder. In addition, a blistering on the fibrous web is counteracted.

Die vom Yankee-Zylinder wieder abgenommene Faserstoffbahn wird anschließend aufgewickelt.The fibrous web removed again from the Yankee cylinder is then wound up.

Die weiter oben angegebene Aufgabe wird nach der Erfindung überdies gelöst durch eine Vorrichtung zur Herstellung einer Faserstoffbahn, insbesondere Tissuebahn, mit einer Blattbildungszone, in der die Faserstoffbahn auf einem umlaufenden permeablen strukturierten Band gebildet wird, einer Presszone, durch die die Faserstoffbahn zwischen dem Strukturband und einem umlaufenden, nicht strukturierten permeablen Stützband liegend hindurchgeführt wird, einem unter Spannung stehenden Pressband mittels dem das Strukturband, die Faserstoffbahn und das Stützband gegen eine zumindest im Wesentlichen glatte Oberfläche pressbar sind, einem an einem Yankee-Zylinder vorgesehenen Pressnip, durch den die Faserstoffbahn zusammen mit dem Strukturband hindurchgeführt wird, wobei die Faserstoffbahn im Bereich dieses Pressnips von dem Strukturband auf die Oberfläche des Yankee-Zylinders übertragen wird, wenigstens einem Schaber, der die Oberfläche des Yankee-Zylinders laufend abschabt, und einer Beschichtungseinrichtung, durch die der Yankee-Zylinder anschließend wieder neu beschichtet wird, so dass im Pressnip stets eine erneuerte Walzenbeschichtung vorliegt.The above-mentioned object is also achieved according to the invention by a device for producing a fibrous web, in particular tissue web, with a forming zone in which the fibrous web is formed on a circumferential permeable structured band, a press zone through which the fibrous web between the structural band and a circulating, not structured permeable support belt is passed lying, a tensioned press belt by means of which the structural band, the fibrous web and the support band are pressed against an at least substantially smooth surface, provided on a Yankee press nip, passed through the fibrous web together with the structural band With the fibrous web in the region of this press nip being transferred from the structural band to the surface of the Yankee cylinder, at least one scraper continuously scrape off the surface of the Yankee cylinder and a coating device, by which the Yankee cylinder is subsequently recoated so that in the press nip is always a renewed roller coating.

Bevorzugt ist die Beschichtungseinrichtung so angesteuert oder geregelt, dass die kontinuierlich auf die Oberfläche des Yankee-Zylinders aufgebrachte Menge an Beschleunigungsmaterial in einem Bereich von etwa 3 bis etwa 9 mg/m2 liegt.Preferably, the coating device is controlled or regulated such that the amount of accelerating material continuously applied to the surface of the Yankee cylinder is in a range from about 3 to about 9 mg / m 2 .

Vorteilhafterweise ist ein Schaber zum kontinuierlichen Abschaben der Oberfläche des Yankee-Zylinders und zum Kreppen der Faserstoffbahn vorgesehen, wobei dieser Schaber so belastet ist, dass sich eine Linienkraft in einem Bereich von etwa 3 bis etwa 7 kN/m, vorzugsweise in einem Bereich von etwa 5 bis etwa 6 kN/m ergibt.Advantageously, a scraper is provided for continuously scraping the surface of the Yankee cylinder and for creping the fibrous web, which scraper is loaded so that a line force in a range of about 3 to about 7 kN / m, preferably in a range of about 5 to about 6 kN / m.

In den Unteransprüchen sind weitere vorteilhafte Ausführungsformen der erfindungsgemäßen Vorrichtung angegeben.In the subclaims further advantageous embodiments of the device according to the invention are given.

Die Erfindung wird im Folgenden anhand von Ausführungsbeispielen unter Bezugnahme auf die Zeichnung näher erläutert; in dieser zeigen:

Figur 1
eine schematische Darstellung einer beispielhaften Ausfüh- rungsform einer Vorrichtung zur Herstellung einer Faserstoff- bahn, insbesondere Tissuebahn,
Figur 2
eine vergrößerte Darstellung eines Abschnitts des Yankee-Zylinders mit einer zugeordneten Beschichtungseinrichtung und einem Schaber, durch den kontinuierlich zumindest ein Teil der aufgebrachten Beschichtung wieder abgetragen wird,
Figur 3
eine mit der Figur 2 vergleichbare schematische Teildarstellung des Yankee-Zylinders mit einem einzigen zugeordneten Schaber, durch den einerseits die Oberfläche des Yankee-Zylinders abgeschabt bzw. zumindest ein Teil der aufgebrachten Beschichtung wieder abgetragen wird, und durch den andererseits die Tissuebahn gekreppt und vom Yankee-Zylinder abgehoben wird, und
Figur 4
eine mit der Figur 3 vergleichbare schematische Teildarstellung des Yankee-Zylinders, wobei dem Yankee-Zylinder jedoch zwei Schaber zugeordnet sind.
The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing; in this show:
FIG. 1
1 is a schematic representation of an exemplary embodiment of a device for producing a fibrous web, in particular a tissue web,
FIG. 2
an enlarged view of a portion of the Yankee cylinder with an associated coating device and a scraper through which continuously at least a portion of the applied coating is removed again,
FIG. 3
one with the FIG. 2 Comparable partial schematic representation of the Yankee cylinder with a single associated scraper, scraped by the one hand, the surface of the Yankee cylinder or at least a portion of the applied coating is removed again, and by the other hand, the tissue web is creped and lifted from the Yankee cylinder, and
FIG. 4
one with the FIG. 3 Comparable partial schematic representation of the Yankee cylinder, wherein the Yankee cylinder, however, are associated with two scrapers.

Figur 1 zeigt in schematischer Darstellung eine beispielhafte Ausführungsform einer Vorrichtung 10 zur Herstellung einer Faserstoffbahn, bei der es sich im vorliegenden Fall um eine Tissuebahn handelt. FIG. 1 shows a schematic representation of an exemplary embodiment of an apparatus 10 for producing a fibrous web, which in the present case is a tissue web.

Ein Stoffauflauf 12 liefert einen Stoffsuspensionsstrahl in einen Einlaufspalt 14, der im Bereich einer Formierwalze 16 zwischen einem innenliegenden umlaufenden permeablen strukturierten Band 18 und einem außenliegenden umlaufenden Formiersieb 20 gebildet ist, die im Bereich der Formierwalze 16 zusammenlaufen und anschließend gemeinsam um diese Formierwalze 16 geführt sind.A headbox 12 delivers a stock suspension jet into an inlet gap 14 which is formed in the region of a forming roller 16 between an inner circumferential permeable structured band 18 and an outer peripheral Formiersieb 20 which converge in the region of the forming roller 16 and are then guided together around this forming roller 16 ,

Bei dem Strukturband 18 kann es sich insbesondere um ein dreidimensional strukturiertes Sieb handeln.The structural band 18 may in particular be a three-dimensionally structured sieve.

Das Formiersieb 20 weist der Tissuebahn 22 zugewandt eine im Vergleich zur betreffenden Seite des Strukturbandes 18 relative glatte Seite auf.The Formiersieb 20 has the tissue web 22 facing a relative to the respective side of the structural band 18 relative smooth side.

Demgegenüber besitzt die der Tissuebahn 22 zugewandte Seite des Strukturbandes 18 vertiefte Bereiche und relativ dazu erhöhte Bereiche auf, wobei die Tissuebahn 22 in diesen vertieften und erhöhten Bereichen des Strukturbandes 18 gebildet wird.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 elevated areas of the structural band 18.

Das Strukturband 18 kann beispielsweise durch ein TAD-Sieb gebildet sein.The structural band 18 may be formed, for example, by a TAD screen.

Im Bereich der Formierwalze 16 wird die Tissuebahn 22 im Wesentlichen durch das außenliegende Formiersieb 20 entwässert. Anschließend wird das Formiersieb 20 im Bereich einer Umlenkwalze 24 wieder von der Tissuebahn 22 getrennt, die zusammen mit dem Strukturband 18 weiter zu einer Presszone 26 geführt wird, in der die Tissuebahn 22 zwischen dem Strukturband 18 und einem umlaufenden, nicht strukturierten permeablen Stützband 28 liegend gepresst wird.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.

Bei dem permeablen Stützband 28 kann es sich insbesondere um einen Filz handeln. Im Bereich der Presszone 26 wird derart Druck auf das Strukturband 18, die Tissuebahn 22 und das Stützband 28 ausgeübt, dass die Tissuebahn 22 in Richtung des beispielsweise durch einen Filz gebildeten Stützbandes 28 entwässert wird.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.

Da die Tissuebahn 22 in der Presszone 26 in Richtung des permeablen Stützbandes 28 entwässert wird und das mit durch diese Presszone 26 geführte Strukturband 18 identisch mit dem Strukturband ist, auf dem die Tissuebahn 22 gebildet wurde, werden die voluminöseren Abschnitte der Tissuebahn 22 weniger stark komprimiert als die weniger voluminösen Abschnitte, so dass im Ergebnis die voluminöse Struktur der betreffenden voluminöseren Abschnitte erhalten bleibt.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 18 passed through this press zone 26 is identical to the structural band on which the tissue web 22 has been formed, the bulky portions of the tissue web 22 are less compressed than the less bulky sections, so that, as a result, the voluminous structure of the respective bulkier sections is preserved.

Im vorliegenden Fall wird der Entwässerungsdruck für die Tissuebahn 22 in der Presszone 26 zumindest abschnittsweise gleichzeitig durch einen Gasstrom und durch eine mechanische Presskraft erzeugt.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.

Der Gasstrom durchströmt zunächst das Strukturband 18, dann die Tissuebahn 22 und schließlich das permeable Stützband 28.The gas stream first flows through the structure band 18, then the tissue web 22 and finally the permeable support band 28.

Wie anhand der Figur 1 zu erkennen ist, wird die Gasströmung im vorliegenden Fall durch eine Saugzone 30 einer Saugwalze 32 erzeugt.As based on the FIG. 1 can be seen, the gas flow is generated in the present case by a suction zone 30 of a suction roll 32.

Die alternativ oder zusätzlich aufgebrachte mechanische Kraft wird dadurch erzeugt, dass das Strukturband 18, die Tissuebahn 22 und das Stützband 28 in der Presszone 26 zwischen einem unter Spannung stehenden Pressband 34 und einer glatten Oberfläche geführt wird, die hier beispielsweise durch die Walze 32 gebildet wird.The alternatively or additionally applied mechanical force is generated 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 ,

Die Presszone 26 ist zumindest im Wesentlichen durch den Umschlingungsbereich des Pressbandes 34 um die Mantelfläche der Saugwalze 32 festgelegt, wobei dieser Umschlingungsbereich durch den Abstand der beiden Umlenkwalzen 36, 38 festgelegt ist.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.

In dem Bereich 40, durch den die Tissuebahn 22 zusammen mit dem Strukturband 18 geführt wird, kann die Tissuebahn 22 wenigstens einem weiteren Trocknungsschritt unterzogen werden.In the area 40, through which the tissue web 22 is guided together with the structural band 18, the tissue web 22 can be subjected to at least one further drying step.

Im Anschluss daran wird die Tissuebahn 22 zusammen mit dem Strukturband 18 durch einen an einem Trockenzylinder, nämlich einem Yankee-Zylinder 42 gebildeten Pressnip 44 geführt. Dabei liegt die Tissuebahn 22 in diesem Pressnip 44 zwischen dem Strukturband 18 und der glatten Oberfläche des Yankee-Zylinders 42. Der Pressnip 44 ist im vorliegenden Fall durch einen Schuhpressnip gebildet.Subsequently, the tissue web 22 is guided together with the structural band 18 by 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.

Dem Yankee-Zylinder 42 ist zur Bildung des Pressnips 44 also eine Schuhpresseinheit, hier eine Schuhpresswalze 46 zugeordnet. Wie anhand der Figur 1 zu erkennen ist, kann dem Yankee-Zylinder 42 eine Haube62 zugeordnet sein.The Yankee cylinder 42 is thus assigned a shoe press unit, here a shoe press roll 46, for forming the press nip 44. As based on the FIG. 1 can be seen, the Yankee cylinder 42 may be associated with a hood 6262.

Dadurch, dass die Tissuebahn zwischen dem Strukturband 18 und dem dazu relativ glatten Formiersieb 20 gebildet wurde, weist nur die auf dem Strukturband 18 gebildete Seite der Tissuebahn 22 eine wellige Oberfläche auf. Demgegenüber ist die auf dem glatten Formiersieb 20 gebildete Oberfläche der Tissuebahn 22 relativ glatt. Mit dieser glatten Seite kommt die Tissuebahn 22 im Pressnip 44 nun in Kontakt mit der Oberfläche des Yankee-Zylinders 42. Die Tissuebahn 22 berührt den Yankee-Zylinder also mit einer relativ großen Fläche. Nachdem das durch den Pressnip 44 geführte Strukturband 18 identisch ist mit dem Strukturband, auf dem die Tissuebahn 22 gebildet wurde, ist überdies sichergestellt, dass die voluminöseren Bereiche der Tissuebahn 22 auch in diesem Pressnip 44 praktisch nicht gepresst werden. Dagegen werden die weniger voluminösen Bereiche der Tissuebahn 22 gepresst, wodurch die Festigkeit der Tissuebahn 22 weiter erhöht wird.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. In addition, after the structural band 18 passed through the press nip 44 is identical to the structural band on which the tissue web 22 has been formed, it is 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.

Im Anschluss an den Pressnip 44 wird das Strukturband 18 von der Tissuebahn 22 getrennt, die auf dem Yankee-Zylinder 42 bis zu einem Schaber 48 geführt wird, wodurch die Tissuebahn 22 gekreppt und vom Yankee-Zylinder 42 abgehoben wird. Anschließend wird die Tissuebahn 22 einer Aufrolleinheit 50 zugeführt, in der sie mit Hilfe einer Anpresswalze 52 zu einem Wickel 54 aufgewickelt wird.Subsequent to the press nip 44, the structure band 18 is separated from the tissue web 22, which is guided on the Yankee cylinder 42 as far as a scraper 48, whereby the tissue web 22 is creped and lifted off the Yankee cylinder 42. Subsequently, the tissue web 22 is fed to a take-up unit 50, in which it is wound up by means of a pressure roller 52 into a winding 54.

Die Tissuebahn 22 wird also im Bereich des Pressnips 44 von dem Strukturband 18 auf die Oberfläche des Yankee-Zylinders 42 übertragen. Dabei wird die Oberfläche des Yankee-Zylinders 42 beispielsweise mittels des Schabers 48 laufend abgeschabt und mittels einer Beschichtungseinrichtung 56 anschließend wieder neu beschichtet, so dass im Pressnip 44 stets eine erneuerte Beschichtung vorliegt. Dabei kann insbesondere ein adhäsives Beschichtungsmaterial auf die Oberfläche des Yankee-Zylinders 42 aufgebracht werden.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 renewed coating is always present in the press nip 44. In this case, in particular, an adhesive coating material can be applied to the surface of the Yankee cylinder 42.

Die kontinuierlich auf die Oberfläche des Yankee-Zylinders 42 aufgebrachte Menge an Beschichtungsmaterial liegt zweckmäßigerweise in einem Bereich von etwa 3 bis etwa 9 mg/m2. Zum kontinuierlichen Abschaben der Oberfläche des Yankee-Zylinders 42 kann ein Schaber oder dergleichen, hier beispielsweise der gleichzeitig die Tissuebahn kreppende Schaber 48, so belastet werden, dass sich eine Linienkraft in einem Bereich von etwa 3 bis etwa 7 kN/m, vorzugsweise in einem Bereich von etwa 5 bis etwa 6 kN/m ergibt.The amount of coating material continuously applied to the surface of the Yankee cylinder 42 is suitably in a range of about 3 to about 9 mg / m 2 . For scraping off the surface of the Yankee cylinder 42, a scraper or the like, here, for example, the tissue web creping scrapers 48, may be loaded so that a line force in a range from about 3 to about 7 kN / m, preferably in one Range of about 5 to about 6 kN / m.

Als Gasstrom, der in der Presszone 26 zunächst das Strukturband 18, dann die Tissuebahn 22 und schließlich das Stützband 28 durchströmt, kann insbesondere ein Luftstrom und/oder Dampfstrom erzeugt werden.As the gas stream, which first flows through the structure band 18 in the press zone 26, then the tissue web 22 and finally the support band 28, an air stream and / or vapor stream can be generated in particular.

Alternativ oder zusätzlich zur Saugwalze 32 kann der Gasstrom zumindest teilweise auch mittels einer auf der Seite des permeablen Strukturbandes 18 angeordneten Überdruckhaube 58 erzeugt werden.As an alternative or in addition to the suction roll 32, the gas stream can also be generated at least partially by means of an overpressure hood 58 arranged on the side of the permeable structure strip 18.

Wie bereits erwähnt, kann als Strukturband 18 insbesondere ein strukturiertes Sieb, beispielsweise ein TAD-Sieb eingesetzt werden.As already mentioned, a structured sieve, for example a TAD sieve, can be used in particular as a structural band 18.

Als Stützband 28 kann, wie bereits erwähnt, insbesondere ein Entwässerungsband vorgesehen sein.As support band 28, as already mentioned, in particular a drainage band can be provided.

Die relativ vertieften und die relativ erhöhten Bereiche des Strukturbandes 18 sind bevorzugt so ausgebildet und relativ zueinander angeordnet, dass maximal 35 % und vorzugsweise maximal 25 % des Strukturbandes 18 im mit dem Yankee-Zylinder 42 gebildeten Pressnip 44 gepresst werden.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.

Figur 2 zeigt in vergrößerter Darstellung einen Abschnitt des Yankee-Zylinders 42, dem die Beschichtungseinrichtung 56 sowie ein Schaber 48 zugeordnet ist, durch den kontinuierlich zumindest ein Teil der aufgebrachten Beschichtung 60 wieder abgetragen wird. FIG. 2 shows an enlarged view of a portion of the Yankee cylinder 42, which is associated with the coating device 56 and a scraper 48 through continuously removed at least a portion of the applied coating 60 again.

Figur 3 zeigt eine mit der Figur 2 vergleichbare schematische Teildarstellung des Yankee-Zylinders 42 mit einem einzigen zugeordneten Schaber 48, durch den einerseits die Oberfläche des Yankee-Zylinders 42 abgeschabt bzw. zumindest ein Teil der aufgebrachten Beschichtung wieder abgetragen wird, und durch den andererseits die Tissuebahn 22 gekreppt und vom Yankee-Zylinder 42 abgehoben wird. FIG. 3 shows one with the FIG. 2 Comparable partial schematic representation of the Yankee cylinder 42 with a single associated scraper 48, scraped by the one hand, the surface of the Yankee cylinder 42 and at least a portion of the applied coating is removed again, and by the other hand, the tissue web 22 creped and the Yankee Cylinder 42 is lifted.

In dieser Figur 3 ist auch wieder die dem Yankee-Zylinder 42 zugeordnete Beschichtungseinheit 56 zu erkennen.In this FIG. 3 is again the Yankee cylinder 42 associated coating unit 56 can be seen.

Figur 4 zeigt eine mit der Figur 3 vergleichbare schematische Teildarstellung des Yankee-Zylinders 42 mit zugeordneter Beschichtungseinheit 56. Im vorliegenden Fall sind dem Yankee-Zylinder 42 jedoch zwei Schaber 48', 48" zugeordnet. Dabei dient ein erster Schaber 48' dazu, die Faserstoffbahn 22 zu kreppen und von der Zylinderoberfläche abzuheben. Mittels des zweiten Schabers 48" wird zumindest ein Teil der Beschichtung 60 einschließlich Schmutz, der sich auf der Zylinderoberfläche angesammelt hat, abgetragen. FIG. 4 shows one with the FIG. 3 However, in the present case, two scrapers 48 ', 48 "are associated with the Yankee cylinder 42. A first scraper 48' serves to crepe the fibrous web 22 and from the cylinder surface By means of the second scraper 48 ", at least a portion of the coating 60, including dirt accumulated on the cylinder surface, is removed.

BezugszeichenlisteLIST OF REFERENCE NUMBERS

1010
Vorrichtungcontraption
1212
Stoffauflaufheadbox
1414
Einlaufspaltinlet gap
1616
Formierwalzeforming roll
1818
Strukturbandstructured band
2020
Formiersiebforming fabric
2222
Tissuebahntissue web
2424
Umlenkwalzedeflecting
2626
Presszonepress zone
2828
Stützbandsupport band
3030
Saugzonesuction zone
3232
Saugwalzesuction roll
3434
Pressbandpress belt
3636
Umlenkwalzedeflecting
3838
Umlenkwalzedeflecting
4040
BereichArea
4242
Yankee-ZylinderYankee cylinder
4444
Pressnippress nip
4646
SchuhpresswalzeShoe press roll
4848
Schaberscraper
48'48 '
Schaberscraper
48"48 "
Schaberscraper
5050
Aufwickeleinheitrewinder
5252
Anpresswalzepressure roller
5454
Wickelreel
5656
Beschichtungseinrichtungcoater
5858
ÜberdruckhaubePressure hood
6060
Beschichtungcoating
6262
HaubeHood

Claims (45)

  1. Process for producing a fibrous web (22), in particular a tissue web, having the following steps:
    a) in a pressing zone (26), the fibrous web (22) is pressed lying between a circulating permeable structured belt (18) and a circulating unstructured permeable supporting belt (28),
    b) the structured belt (18), the fibrous web (22) and the supporting belt (28) are pressed against a surface by means of a press belt (34) under tension,
    c) the fibrous web (22) and the structured belt (18) are fed to a press nip (44) provided on a Yankee cylinder (42),
    d) the fibrous web (22) is transferred from the structured belt (18) to the surface of the Yankee cylinder (42) in the region of the press nip (44),
    e) the surface of the Yankee cylinder (42) is doctored off continuously and then recoated again, so that a renewed coating is always present in the press nip (44).
  2. Process according to Claim 1, characterized in that an adhesive coating material is applied to the surface of the Yankees cylinder (42).
  3. Process according to Claim 1 or 2, characterized in that the quantity of coating material applied continuously to the surface of the Yankee cylinder (42) lies in a range from about 3 to about 9 mg/m2.
  4. Process according to one of the preceding claims, characterized in that, in order to doctor off the surface of the Yankee cylinder (42) continuously and to crepe the tissue web (22), a doctor (48, 48") or the like is loaded in such a way that the result is a line force in a range from about 3 to about 7 kN/m.
  5. Process according to Claim 4, characterized in that, in order to doctor off the surface of the Yankee cylinder (42) continuously, a doctor (48, 48") or the like is loaded in such a way that the result is a line force in a range from about 5 to about 6 kN/m.
  6. Process according to one of the preceding claims, characterized in that the fibrous web (22) is formed on a circulating permeable structured belt (18).
  7. Process according to one of the preceding claims, characterized in that, in the region of the pressing zone (26), a gas stream is produced which flows through the structured belt (18), the fibrous web (22) and the supporting belt (28).
  8. Process according to Claim 7, characterized in that the gas stream flows firstly through the structured belt (18), then the fibrous web (22) and finally the supporting belt (28).
  9. Process according to Claim 7 or 8, characterized in that the gas stream that is produced is an air stream and/or steam stream.
  10. Process according to one of Claims 7 to 9, characterized in that the gas stream is produced at least partly by means of a suction zone (30) of a rotating suction roll (32), which delimits the pressing zone (26) on the side adjacent to the supporting belt (28).
  11. Process according to one of Claims 7 to 10, characterized in that the gas stream is produced at least partly by means of a flat or curved suction box, which delimits the pressing zone (26) on the side adjacent to the supporting belt (28).
  12. Process according to one of Claims 7 to 11, characterized in that the gas stream is produced at least partly by means of a positive pressure hood (58) arranged on the side of the permeable structured belt.
  13. Process according to one of the preceding claims, characterized in that the structured belt (18) used is a structured fabric.
  14. Process according to one of the preceding claims, characterized in that the structured belt (18) used is a TAD fabric.
  15. Process according to one of the preceding claims, characterized in that the fibrous web (22) is formed by the fibrous stock suspension being sucked into the structure of the permeable structured belt (18) by means of a vacuum device.
  16. Process according to one of the preceding claims, characterized in that the supporting belt (28) used is a dewatering belt.
  17. Process according to one of the preceding claims, characterized in that the relatively depressed and the relatively elevated regions of the structured belt (18) are formed and arranged relative to one another in such a way that at most 35% and preferably at most 25% of the structured belt (18) is pressed in the press nip (44).
  18. Process according to one of the preceding claims, characterized in that the press nip (44) provided on the Yankee cylinder (42) is a shoe press nip.
  19. Process according to one of the preceding claims, characterized in that the Yankee cylinder is assigned only one doctor (48), by means of which, firstly, part of the coating (60) is removed and, secondly, the fibrous web (22) is creped and lifted off the cylinder surface.
  20. Process according to one of Claims 1 to 18, characterized in that the Yankee cylinder (42) is assigned a first doctor (48'), by means of which the fibrous web (22) is creped and lifted off the cylinder surface, and a second doctor (48") for removing at least part of the coating (60).
  21. Process according to one of the preceding claims, characterized in that the outlet pocket between fibrous web (22) and structured belt (18), occurring at the outlet from the press nip (44), is acted on by means of an air knife.
  22. Process according to one of the preceding claims, characterized in that, in the region in which the structured belt (18) runs off a mating roll (46) forming the press nip (44) with the Yankee cylinder (42), the outlet pocket between the structured belt (18) and the mating roll (46) is acted on by means of an air knife.
  23. Process according to one of the preceding claims, characterized in that the fibrous web (22) removed from the Yankee cylinder (42) again is then wound up.
  24. Apparatus (10) for producing a fibrous web (22), in particular a tissue web, having a sheet forming zone, in which the fibrous web (22) is formed on a circulating permeable structured belt (18), a pressing zone (26), through which the fibrous web (22) is led lying between the structured belt (18) and a circulating unstructured permeable supporting belt (28), a press belt (34) under tension, by means of which the structured belt (18), the fibrous web (22) and the supporting belt (28) can be pressed against a surface and a press nip (44) provided on a Yankee cylinder (42), through which nip the fibrous web is led together with the structured belt (18), the fibrous web (22) in the region of this press nip (44) being transferred from the structured belt (18) to the surface of the Yankee cylinder (42), at least one doctor (48, 48"), which doctors off the surface of the Yankee cylinder (42) continuously, and a coating device (56), by means of which the Yankee cylinder (42) is subsequently recoated again, so that a renewed roll coating is always present in the press nip (44).
  25. Apparatus according to Claim 24, characterized in that, by means of the coating device (56), adhesive coating material (60) can be applied to the surface of the Yankee cylinder (42).
  26. Apparatus according to Claim 24 or 25, characterized in that the coating device (56) is driven or regulated in such a way that the quantity of coating material (60) applied continuously to the surface of the Yankee cylinder (42) lies in the range from about 3 to about 9 mg/m2.
  27. Apparatus according to one of the preceding claims, characterized in that a doctor (48, 48") is provided in order to scrape off the surface of the Yankee cylinder (42) continuously, and this doctor (48, 48") is loaded in such a way that the result is a line force in a range from about 3 to about 7 kN/m.
  28. Apparatus according to Claim 27, characterized in that the doctor (48, 48") is loaded in such a way that the result is a line force in a range from about 5 to about 6 kN/m.
  29. Apparatus according to one of the preceding claims, characterized in that means (30, 32, 58) are provided to produce a gas stream in the region of the pressing zone (26) said gas stream flowing through the structured belt (18), the fibrous web (22) and the supporting belt (28).
  30. Apparatus according to Claim 29, characterized in that the gas stream flows firstly through the structured belt (18), then the fibrous web (22) and finally the supporting belt (28).
  31. Apparatus according to Claim 29 or 30, characterized in that means (30, 32, 58) for producing an air stream and/or means for producing a steam stream are provided.
  32. Apparatus according to one of Claims 29 to 31, characterized in that the means for producing a gas stream comprise a rotating suction roll (32) which is provided with a suction zone (30) and which delimit the pressing zone (26) on the side adjacent to the supporting belt (28).
  33. Apparatus according to one of Claims 29 to 31, characterized in that the means for producing a gas stream comprise at least flat or curved suction box, which delimits the pressing zone (26) on the side adjacent to the supporting belt (18).
  34. Apparatus according to one of Claims 29 to 33, characterized in that the means for producing a gas stream comprise a positive pressure hood (58) arranged on the side of the permeable structured belt (18).
  35. Apparatus according to one of the preceding claims, characterized in that the structured belt (18) provided is a structured fabric.
  36. Apparatus according to one of the preceding claims, characterized in that the structured belt (18) provided is a TAD fabric.
  37. Apparatus according to one of the preceding claims, characterized in that it comprises a sheet forming device having a suction device, in which the fibrous stock suspension for forming the fibrous web (22) can be sucked into the structure of the permeable structured belt (18) by means of a vacuum device.
  38. Apparatus according to one of the preceding claims, characterized in that the supporting belt (28) provided is a dewatering belt.
  39. Apparatus according to one of the preceding claims, characterized in that the relatively depressed and the relatively elevated regions of the structured belt (18) are formed and arranged relative to one another in such a way that at most 35% and preferably at most 25% of the structured belt (18) is pressed in the press nip (44).
  40. Apparatus according to one of the preceding claims, characterized in that the press nip (44) provided on the Yankee cylinder (42) is a shoe press nip.
  41. Apparatus according to one of the preceding claims, characterized in that the Yankee cylinder is assigned only one doctor (48), by means of which, firstly, part of the coating (60) is removed and, secondly, the fibrous web (22) is creped and lifted off the cylinder surface.
  42. Apparatus according to one of Claims 24 to 40, characterized in that the Yankee cylinder (42) is assigned a first doctor (48'), by means of which the fibrous web (22) is creped and lifted off the cylinder surface, and a second doctor (48") for removing at least part of the coating (60).
  43. Apparatus according to one of the preceding claims, characterized in that an air knife is provided in order to act on the outlet pocket between fibrous web (22) and structured belt (18), occurring at the outlet from the press nip (44).
  44. Apparatus according to one of the preceding claims, characterized in that an air knife is provided in order, in the region in which the structured belt (18) runs off a mating roll (46) forming the press nip (44) with the Yankee cylinder (42), to act on the outlet pocket between the structured belt (18) and the mating roll (46).
  45. Apparatus according to one of the preceding claims, characterized in that the fibrous web (22) removed from the Yankee cylinder (42) again is fed to a reeler.
EP06114192A 2005-09-30 2006-05-19 Method and device for producing a tissue web Not-in-force EP1770209B1 (en)

Applications Claiming Priority (1)

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DE102005046903A DE102005046903A1 (en) 2005-09-30 2005-09-30 Method and device for producing a tissue web

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EP1770209A1 EP1770209A1 (en) 2007-04-04
EP1770209B1 true EP1770209B1 (en) 2011-12-14

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EP (1) EP1770209B1 (en)
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US11952721B2 (en) 2022-06-16 2024-04-09 First Quality Tissue, Llc Wet laid disposable absorbent structures with high wet strength and method of making the same

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US20090242158A1 (en) 2009-10-01
ATE537297T1 (en) 2011-12-15
EP1770209A1 (en) 2007-04-04
US7582187B2 (en) 2009-09-01
DE102005046903A1 (en) 2007-04-05
US7905989B2 (en) 2011-03-15
US20070074835A1 (en) 2007-04-05

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