EP3443161B1 - Method and forming belt for producing a fibre material web - Google Patents

Method and forming belt for producing a fibre material web Download PDF

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Publication number
EP3443161B1
EP3443161B1 EP17718855.4A EP17718855A EP3443161B1 EP 3443161 B1 EP3443161 B1 EP 3443161B1 EP 17718855 A EP17718855 A EP 17718855A EP 3443161 B1 EP3443161 B1 EP 3443161B1
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EP
European Patent Office
Prior art keywords
polymer foam
tier
forming belt
structured
fibrous web
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EP17718855.4A
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German (de)
French (fr)
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EP3443161A1 (en
Inventor
Robert Eberhardt
Matthias Schmitt
Frank Opletal
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Voith Patent GmbH
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Voith Patent GmbH
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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
    • D21F11/006—Making patterned paper
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/0027—Screen-cloths
    • D21F1/0036—Multi-layer screen-cloths
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
    • D21F1/80—Pulp catching, de-watering, or recovering; Re-use of pulp-water using endless screening belts
    • 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
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/08—Felts
    • D21F7/083—Multi-layer felts
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/002—Tissue paper; Absorbent paper
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/02—Patterned paper

Definitions

  • the invention relates to a method for producing a structured fibrous web according to the preamble of claim 1 and a forming belt for producing a structured fibrous web according to the preamble of claim 3
  • the invention also relates to a machine for producing a fibrous web according to the preamble of claim 12.
  • an aqueous fibrous suspension is usually dewatered in the so-called former on a forming fabric or else between two forming fabrics in a first process step. This dewatering is usually supported by suction elements or by blowing elements.
  • the fibrous web is formed largely flat.
  • the volume of a tissue web is an essential quality characteristic. It is therefore desirable if the tissue web is already formed, ie formed, in the former with as high a bulk as possible.
  • the so-called ATMOS TM system was developed in the past by the applicant, for example. See, for example, the patent application WO 2012/013773 and the literature cited therein, in particular the European patent application EP0 708 857 .
  • the fibrous web is formed in the former on a structured screen, the so-called 'molding fabric'.
  • This structured screen has a supporting structure, which is suitable for absorbing the resulting tensile load, and a structuring layer, the 'sculpting layer'.
  • the structuring layer is designed with its weaving pattern in such a way that pocket-like structures are created between the highest points of the covering and the supporting structure layer. These pocket-like structures are transferred to the fibrous web by fibers being deposited there during sheet formation, resulting in a tissue web with a noticeably higher volume.
  • the object of the invention is to provide a method and a forming belt which completely or partially overcome the problems of the prior art.
  • the object is completely achieved with regard to the method by a method for producing a structured fibrous web according to the characterizing part of claim 1, and with regard to the forming belt by a forming belt for a machine for producing a fibrous web according to the characterizing part of claim 3.
  • a method for producing a structured fibrous web, in particular a tissue web is proposed.
  • a fiber suspension is brought into contact with at least one structured forming belt. This can be done, for example, by applying the suspension to a structured forming belt. Alternatively, it can also be provided that the suspension is introduced between two forming belts. Either one of the two forming belts or both forming belts can be a structured forming belt.
  • the fibrous stock suspension is dewatered by means of at least one dewatering element, in particular a suction element or also a blowing element.
  • the at least one structured forming belt comprises a layer of polymer foam, which provides the side of the structured forming belt that comes into contact with paper and during the forming process the structure of the foam layer is at least partially transferred to the fibrous web.
  • At least part of the structure of the layer made of polymer foam, which is transferred to the fibrous web is a pore structure of the layer made of polymer foam.
  • the pores of the layer of polymer foam which are open to the paper-contacting side of the layer, form the pocket-like structures in which the pulp fibers are deposited during sheet formation, resulting in a tissue web with appreciably higher volume.
  • the volume-increasing effect is therefore the same as with the woven structures in the prior art.
  • commercially available foams, in particular flexible foams can be used for the polymer foam layer. The time-consuming weaving process is no longer necessary.
  • the structures created in this way in the web are irregular, since the pores in the foam are largely randomly distributed. This can be advantageous insofar as the human eye perceives regular structures more easily and evaluates them as disturbing markings.
  • the polymeric foam layer has a pore density of less than 30 PPI. In such a case, the pores are often of a size that is very advantageous for transferring the structure to the paper web.
  • an external structure is introduced into the layer of polymer foam in addition to the pore structure.
  • This structure can be introduced into the layer of polymer foam, for example, by embossing, firing, etching, cutting or punching. These structures can also be transferred to the sheet during the forming process. This can either be done in addition to transferring the pore structure to the sheet.
  • the structures in the fibrous web can emerge as raised structures.
  • the fabric By means of such a transfer of structures to the foam layer, it is possible, in contrast to classic watermarks, for example, for the fabric to continue to have relevant permeability at the points of structural features. Depending on the configuration of the structure, this can optionally be slightly larger or smaller than the permeability of the rest of the fabric. This can be advantageous, inter alia, when the structures or structural elements cover a significant part, in particular more than 10%, of the surface of the material web. The web of material is also dewatered through these regions of the covering. Thus, the dewatering of the material web is much more uniform in comparison with classic watermarks for forming fabrics, where there is usually no dewatering in regions with an applied structure.
  • the support structure is often formed by a fabric or includes this. However, it can also be provided that the supporting structure is formed by other structures, for example by knitted fabrics, scrims, film or membrane structures, or includes them.
  • the external structure is a regular or irregular structure.
  • the polymeric foam layer has a pore density of less than 30 PPI.
  • the pores are often of a size that is very advantageous for transferring the structure to the paper web.
  • the layer of polymer foam can be provided with an external structure by means of embossing, firing, etching, cutting or stamping.
  • the structured forming belt can be provided with an external structure by compacting the layer of polymeric foam and using a hot roller in contact with the layer of polymeric foam during the compaction.
  • This roller can advantageously be equipped in such a way that a structure to be transferred to the foam is worked into the roller surface as a negative.
  • This structure can be made of a thermally conductive material (eg, metal) or of a non-thermally conductive material such as a polymer (eg, a silicone).
  • the structure is then embossed into the surface of the foam layer.
  • the layer of polymeric foam consists of or comprises an elastomer, in particular a polyurethane.
  • the layer of polymer foam consists of or comprises a polyamide, polyester, polyethylene or a silicone.
  • the layer of polymer foam has an anisotropic pore structure.
  • anisotropic structure the shape of at least a large part (often more than 50%, or even more than 80%) of the individual pores deviates from the isotropic spherical shape.
  • the pores have a greater extent in the machine direction of the clothing and in the transverse direction of the clothing than in the thickness direction.
  • Such a pore structure can be achieved, for example, by compressing a foam layer with an isotropic pore structure.
  • Such an anisotropic pore structure can often lead the water away from the paper web in the direction of the supporting structure.
  • the foam layer also usually provides less storage volume as a result.
  • connection of the layer made of polymer foam to the supporting structure can advantageously be realized by means of gluing or welding, in particular by means of NIR transmission welding.
  • the invention comprises a machine for producing a fibrous web, in particular a tissue web, characterized in that the machine has at least one forming belt according to one of Claims 3-8.
  • a machine is suitable for carrying out the method according to one of Claims 1-2 according to the invention and for producing a structured fibrous web.
  • the structured forming belt 1 includes a fabric 3 that provides the support structure 3 .
  • a layer of polymer foam 2 is attached to this supporting structure 3 .
  • This layer of polymer foam 2 also makes the paper-contacting side 5 of the structured forming belt 1 available.
  • the pores 4 of the layer of polymer foam 2 are in figure 1 shown covering anisotropic. This can be realized, for example, by compacting a standard polymer foam, which usually has isotropic pores, in a compacting step using pressure and/or temperature. This changes not only the thickness of the foam layer 2 but also the shape of the pores 4.
  • a woven support structure 3 is first made available. This is woven from polyester filaments.
  • a foam is provided, for example in the form of a reticulated flexible polyurethane foam. In the example, this has a thickness of 4mm and a pore density of 45 PPI. According to the invention, foams with a pore density of less than 30 PPI are used.
  • a suitable method for connecting the layers of polymer foam 2 to the support structure 3 is laser transmission welding.
  • an NIR Laser used with a wavelength of 940 nm. This was pressed on with a joining pressure of approx. 20N/cm. It is particularly advantageous for laser transmission welding if the polymer foam 2 completely or partially absorbs the laser light, while the supporting structure 3 is completely or largely transparent to the laser light. This was realized in the example by coloring the polymer foam, where an anthracite-colored foam was used. By choosing a base fabric made of polyester, the laser light could first penetrate the supporting structure 3 and was then absorbed by the polymer foam. In this way, the heat required for welding was generated at the connection point between the support structure 3 and the foam layer 2 . This is a common principle in laser transmission welding.
  • the laminate connected in this way was then compacted under pressure at a temperature of approx. 190°.
  • the resulting fabric 1 had a permeability of 400CFM at a thickness (measured under 6kPa pressure) of 1.07mm.
  • the proportion of the support structure 3 was 0.49mm
  • the proportion of the foam layer 2 was 0.58mm. With an initial foam thickness of 4 mm, the process compacted it to 14.5% of its initial thickness.
  • the laminate 1 was compressed to 0.91 mm under a pressure of 50 kPa, the thickness of the foam layer 2 being 0.42 mm.
  • the foam layer was thus compressed an additional 27% at this pressure.
  • the pressure was reduced to 6 kPa, the foam layer expanded again to its original thickness within the scope of measurement accuracy.
  • FIG 2 is a schematic of the formation of the fibrous web on the forming belt figure 1 shown.
  • the process is intended to explain the emergence of a structured fibrous web as an example.
  • a suspension with fibers 6 in particular cellulose fibers 6
  • Drainage takes place in figure 2 From top to bottom, that is, the water first passes through the layer of polymer foam 2 and then the supporting structure 3.
  • the drainage process can be carried out by an in the figure 2 dewatering element, not shown, for example a suction box, which is arranged on the side of the forming belt 1 facing away from the paper.
  • the fibers 6 are deposited on the side 5 of the forming belt 1 that comes into contact with the paper.
  • This paper-contacting side 5 is provided by the layer of polymer foam 2. Due to the pore structure of the polymer foam 2 , some of the fibers 6 can penetrate through larger pores 4 into the layer of polymer foam 2 and are deposited in these pores 4 . In this way, the structure of the forming belt 1, in particular the pore structure of the layer of polymer foam 2, is at least partially transferred to the fibrous web. This effect of depositing fibers in the pore structure can be supported by a suitable choice of polymer foam.
  • a structured fibrous web which has been produced using a method according to the invention can have major advantages over a comparable non-structured fibrous web, for example with regard to thickness and porosity. Due to the greater thickness, fiber webs with a lower basis weight can also be produced, which nevertheless have all the desired product properties. Due to the savings in fiber material that can be achieved in this way, the process is also very advantageous from an economic point of view.
  • the increased thickness with a lower basis weight and the significantly increased porosity of the structured product are particularly noticeable here.
  • figure 3 shows a section of the surface of a roller for transferring an external structure to a layer of polymer foam 2.
  • the roller has both raised structural elements 11a, 11b, which are embossed into a layer of polymer foam 2.
  • the section in figure 3 a multiplicity of structural elements 10, which are designed as round depressions in the roll surface. These structural elements are transferred to the foam layer 2 as raised elements.
  • both the roller surface and the raised structural elements 11a, 11b are made of metal.
  • these raised structural elements 11a, 11b consist entirely or partially of a non-thermally conductive material, for example a polymer.
  • the structural elements 10, 11a, 11b can in principle be transferred to the polymer foam 2 by means of such a roller or a similar roller in a separate work step before or after the production of the covering, the transfer will often advantageously take place together with the compacting of the foam layer . In this way, a process step in the production of the covering can be omitted. In addition, no additional devices are required for this transmission.
  • FIG. 1 shows a greatly enlarged view of a structured forming belt 1 according to the invention.
  • the view is on the side of the forming belt 1 that comes into contact with the paper.
  • fibers 6 are deposited both on the webs 7 made of polymer material and penetrate completely or partially into the pores 4 of the layer made of polymer foam.
  • the diameter "d" of such a pore is in figure 4 about 1mm.
  • smaller pores for example with diameters of 750 ⁇ m, 500 ⁇ m or less, or also larger pores with diameters of 1.5 mm, 2 mm or more can also be used in other advantageous forming belts.
  • the pore sizes in a structured forming belt will usually have a certain distribution.

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Description

Die Erfindung betrifft ein Verfahren zum Herstellen einer strukturierten Faserstoffbahn gemäß dem Oberbegriff des Anspruchs 1 sowie ein Formierband zum Herstellen einer strukturierten Faserstoffbahn gemäß dem Oberbegriff des Anspruchs 3The invention relates to a method for producing a structured fibrous web according to the preamble of claim 1 and a forming belt for producing a structured fibrous web according to the preamble of claim 3

Schließlich betrifft die Erfindung auch noch eine Maschine zur Herstellung einer Faserstoffbahn gemäß dem Oberbegriff des Anspruchs 12.Finally, the invention also relates to a machine for producing a fibrous web according to the preamble of claim 12.

Bei der Herstellung einer Faserstoffbahn, insbesondere einer Tissuebahn, wird üblicherweise in einem ersten Prozessschritt eine wässrige Faserstoffsuspension im sogenannten Former auf einem Formiersieb oder auch zwischen zwei Formiersieben entwässert. Diese Entwässerung wird in der Regel durch Saugelemente oder auch durch Blaselemente unterstützt.In the production of a fibrous web, in particular a tissue web, an aqueous fibrous suspension is usually dewatered in the so-called former on a forming fabric or else between two forming fabrics in a first process step. This dewatering is usually supported by suction elements or by blowing elements.

In einem konventionellen Tissue Former wird die Faserstoffbahn weitgehend flach gebildet. Jedoch ist das Volumen einer Tissuebahn, der sogenannte Bulk, eine wesentliche Qualitätseigenschaft. Daher ist es wünschenswert, wenn die Tissuebahn bereits im Former mit einem möglichst hohen Bulk formiert, d.h. gebildet wird. Hierzu wurde in der Vergangenheit z.B. von der Anmelderin das sogenannte ATMOS™ System entwickelt. Siehe hierzu beispielsweise die Patentanmeldung WO 2012/013773 sowie die darin zitiere Literatur, insbesondere die Europäische Patentanmeldung EP0 708 857 . Hierbei wird die Faserstoffbahn im Former auf einem strukturierten Sieb, dem sogenannten 'molding fabric' gebildet.In a conventional tissue former, the fibrous web is formed largely flat. However, the volume of a tissue web, the so-called bulk, is an essential quality characteristic. It is therefore desirable if the tissue web is already formed, ie formed, in the former with as high a bulk as possible. For this purpose, the so-called ATMOS ™ system was developed in the past by the applicant, for example. See, for example, the patent application WO 2012/013773 and the literature cited therein, in particular the European patent application EP0 708 857 . The fibrous web is formed in the former on a structured screen, the so-called 'molding fabric'.

Dieses strukturierte Sieb weist eine Tragstruktur auf, welche zur Aufnahme der entstehenden Zugbelastung geeignet ist, sowie eine strukturierende Lage, der 'sculpturing layer'. Die strukturierende Lage ist durch ihr Webmuster so ausgestaltet, dass zwischen den höchsten Punkten der Bespannung und der Tragstrukturlage taschenartige Strukturen entstehen. Diese taschenartigen Strukturen werden auf die Faserstoffbahn übertragen, indem sich bei der Blattbildung dort Fasern ablegen, wodurch eine Tissuebahn mit merklich höherem Volumen entsteht.This structured screen has a supporting structure, which is suitable for absorbing the resulting tensile load, and a structuring layer, the 'sculpting layer'. The structuring layer is designed with its weaving pattern in such a way that pocket-like structures are created between the highest points of the covering and the supporting structure layer. These pocket-like structures are transferred to the fibrous web by fibers being deposited there during sheet formation, resulting in a tissue web with a noticeably higher volume.

Weitere Bespannungen sind in der US 2004/118546 , US 2001/032712 , EP 2 128 334 und DE 10 2006 055828 sowie der nachveröffentlichten WO2016/058972 beschrieben.More coverings are in the U.S. 2004/118546 , US2001/032712 , EP 2 128 334 and DE 10 2006 055828 as well as the subsequently published WO2016/058972 described.

Nachteilig an dem Stand der Technik ist jedoch, dass das Weben dieser strukturierten Siebe sehr aufwändig ist. Zudem ist man auch in der Wahl der Strukturen, die auf die Faserstoffbahn übertragen werden können, beschränkt. So können aufgrund des regelmäßigen Webprozesses nur regelmäßige Strukturen erzeugt werden.A disadvantage of the prior art, however, is that weaving these structured screens is very complex. In addition, one is also limited in the choice of structures that can be transferred to the fibrous web. Due to the regular weaving process, only regular structures can be produced.

Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren sowie ein Formierband zur Verfügung zu stellen, das die Probleme des Standes der Technik ganz oder teilweise überwindet.The object of the invention is to provide a method and a forming belt which completely or partially overcome the problems of the prior art.

Die Aufgabe wird vollständig gelöst hinsichtlich des Verfahrens durch ein Verfahren zuer Herstellung einer strukturiereten Faserstoffbahn gemäß dem Kennzeichen des Anspruchs 1, sowie hinsichtlich des Formierbands durch ein Formierband für eine Maschine zur Herstellung einer Faserstoffbahn gemäß dem Kennzeichen des Anspruchs 3.The object is completely achieved with regard to the method by a method for producing a structured fibrous web according to the characterizing part of claim 1, and with regard to the forming belt by a forming belt for a machine for producing a fibrous web according to the characterizing part of claim 3.

Es wird ein Verfahren zum Herstellen einer strukturierten Faserstoffbahn insbesondere einer Tissuebahn vorgeschlagen. Hierbei wird eine Faserstoffsuspension mit mindestens einem strukturierten Formierband in Kontakt gebracht. Dies kann beispielsweise dadurch geschehen, dass die Suspension auf ein strukturiertes Formierband aufgetragen wird. Alternativ kann auch vorgesehen sein, dass die Suspension zwischen zwei Formierbänder eingebracht wird. Dabei kann entweder eines der beiden Formierbänder oder aber auch beide Formierbänder ein strukturiertes Formierband sein. Mittels zumindest eines Entwässerungselements, insbesondere eines Saugelements oder auch eine Blaselements wird die Faserstoffsuspension entwässert. Erfindungsgemäß ist vorgesehen, dass das zumindest einen strukturierten Formierband eine Lage aus Polymerschaum umfasst, welche die papierberührende Seite des strukturierten Formierbands bereitstellt und während des Formierprozesses die Struktur der Schaumlage zumindest teilweise auf die Faserstoffbahn übertragen wird.A method for producing a structured fibrous web, in particular a tissue web, is proposed. Here, a fiber suspension is brought into contact with at least one structured forming belt. This can be done, for example, by applying the suspension to a structured forming belt. Alternatively, it can also be provided that the suspension is introduced between two forming belts. Either one of the two forming belts or both forming belts can be a structured forming belt. The fibrous stock suspension is dewatered by means of at least one dewatering element, in particular a suction element or also a blowing element. According to the invention, the at least one structured forming belt comprises a layer of polymer foam, which provides the side of the structured forming belt that comes into contact with paper and during the forming process the structure of the foam layer is at least partially transferred to the fibrous web.

Vorteilhafte Ausführungen des Verfahrens werden in den Unteransprüchen beschrieben.Advantageous embodiments of the method are described in the dependent claims.

So kann in einer vorteilhaften Ausführung des Verfahrens vorgesehen sein, dass es sich bei zumindest bei einem Teil der Struktur der Lage aus Polymerschaum, welche auf die Faserstoffbahn übertragen wird, um eine Porenstruktur der Lage aus Polymerschaum handelt. In diesem Fall bilden die Poren der Lage aus Polymerschaum, welche zur papierberührenden Seite der Lage hin offen sind, jene taschenartigen Strukturen, in denen sich bei der Blattbildung die Zellstofffasern ablegen, wodurch eine Tissuebahn mit merklich höherem Volumen entsteht. Der volumenerhöhende Effekt ist also derselbe, wie bei den gewebten Strukturen im Stand der Technik. Jedoch können für die Lage aus Polymerschaum handelsübliche Schäume, insbesondere Weichschäume verwendet werden. Das aufwändige Webverfahren entfällt. Zudem sind die so in der Bahn entstehenden Strukturen unregelmäßig, da die Poren im Schaum weitgehend statistisch verteilt sind. Dies kann insofern vorteilhaft sein, da das menschliche Auge regelmäßige Strukturen leichter wahrnimmt, und diese als störende Markierungen bewertet. Die Lage aus Polymerschaum weist eine Porendichte von weniger als 30 PPI auf. In einem solchen Fall weisen die Poren häufig eine Größe auf, die für die Übertragung der Struktur auf die Papierbahn sehr vorteilhaft ist.Thus, in an advantageous embodiment of the method, it can be provided that at least part of the structure of the layer made of polymer foam, which is transferred to the fibrous web, is a pore structure of the layer made of polymer foam. In this case, the pores of the layer of polymer foam, which are open to the paper-contacting side of the layer, form the pocket-like structures in which the pulp fibers are deposited during sheet formation, resulting in a tissue web with appreciably higher volume. The volume-increasing effect is therefore the same as with the woven structures in the prior art. However, commercially available foams, in particular flexible foams, can be used for the polymer foam layer. The time-consuming weaving process is no longer necessary. In addition, the structures created in this way in the web are irregular, since the pores in the foam are largely randomly distributed. This can be advantageous insofar as the human eye perceives regular structures more easily and evaluates them as disturbing markings. The polymeric foam layer has a pore density of less than 30 PPI. In such a case, the pores are often of a size that is very advantageous for transferring the structure to the paper web.

In einer weiteren vorteilhaften Ausführung des Verfahrens kann vorgesehen sein, dass in die Lage aus Polymerschaum zusätzlich zu der Porenstruktur eine externe Struktur eingebracht ist. Diese Struktur kann beispielsweise durch Prägen, Einbrennen, Ätzen, Schneiden oder Stanzen in die Lage aus Polymerschaum eingebracht werden. Auch diese Strukturen können während des Formierprozesses auf das Blatt übertragen werden. Dies kann entweder zusätzlich zur Übertragung der Porenstruktur auf das Blatt geschehen.In a further advantageous embodiment of the method, it can be provided that an external structure is introduced into the layer of polymer foam in addition to the pore structure. This structure can be introduced into the layer of polymer foam, for example, by embossing, firing, etching, cutting or punching. These structures can also be transferred to the sheet during the forming process. This can either be done in addition to transferring the pore structure to the sheet.

Mittels der eingebrachten externen Struktur ist es möglich, mittels des beschriebenen Verfahrens eine Vielzahl von Strukturen auf die Faserstoffbahn zu übertragen. So ist es möglich, in einem fertigen Papier spezielle Strukturen oder Symbole zu übertragen. Beispiele hierfür sind Wasserzeichen oder gewisse dekorative Strukturen in Tissuepapieren. Durch solche Zeichen oder Strukturen in der Schaumlage, insbesondere durch eingeprägte Strukturen in der Schaumlage ist es möglich, auf die produzierte Faserstoffbahn eine Vielzahl von Strukturen zu übertragen.By means of the external structure introduced, it is possible to transfer a large number of structures to the fibrous web by means of the method described. So is it is possible to transfer special structures or symbols to a finished paper. Examples of this are watermarks or certain decorative structures in tissue paper. Such signs or structures in the foam layer, in particular embossed structures in the foam layer, make it possible to transfer a large number of structures to the fibrous web produced.

Je nach Einsatz einer solchen Bespannung können die Strukturen in der Faserstoffbahn als erhabene Strukturen hervortreten.Depending on how such a covering is used, the structures in the fibrous web can emerge as raised structures.

Mittels einer derartigen Übertragung von Strukturen auf die Schaumlage ist es im Gegensatz z.B. zu klassischen Wasserzeichen möglich, dass die Bespannung an den Stellen der Strukturmerkmale weiterhin eine relevante Permeabilität aufweist. Je nach Ausgestaltung der Struktur kann diese gegebenenfalls etwas größer oder kleiner sein, als die Permeabilität der übrigen Bespannung. Dies kann unter anderem dann von Vorteil sein, wenn die Strukturen bzw. Strukturelemente Elemente einen signifikanten Teil, insbesondere mehr als 10% der Oberfläche der Materialbahn bedecken. Auch durch diese Regionen der Bespannung erfolgt eine Entwässerung der Materialbahn. Somit ist die Entwässerung der Materialbahn wesentlich gleichmäßiger im Vergleich mit klassischen Wasserzeichen für Formiersiebe, bei denen in Regionen mit aufgebrachter Struktur üblicherweise keine Entwässerung stattfindet.By means of such a transfer of structures to the foam layer, it is possible, in contrast to classic watermarks, for example, for the fabric to continue to have relevant permeability at the points of structural features. Depending on the configuration of the structure, this can optionally be slightly larger or smaller than the permeability of the rest of the fabric. This can be advantageous, inter alia, when the structures or structural elements cover a significant part, in particular more than 10%, of the surface of the material web. The web of material is also dewatered through these regions of the covering. Thus, the dewatering of the material web is much more uniform in comparison with classic watermarks for forming fabrics, where there is usually no dewatering in regions with an applied structure.

Hinsichtlich des Formierbands wird die Aufgabe gelöst durch die Merkmale des Anspruchs 3 gelöst.With regard to the forming belt, the object is achieved by the features of claim 3.

Vorteilhafte Ausführungen des strukturierten Formierbands werden in den Unteransprüchen beschrieben.Advantageous designs of the structured forming belt are described in the dependent claims.

Häufig wird die Tragstruktur durch ein Gewebe gebildet oder umfasst dieses. Es kann jedoch auch vorgesehen sein, dass die Tragstruktur durch andere Gebilde, beispielsweise durch Gewirke, Gelege, Folien- oder Membranstrukturen gebildet wird, oder diese umfasst.The support structure is often formed by a fabric or includes this. However, it can also be provided that the supporting structure is formed by other structures, for example by knitted fabrics, scrims, film or membrane structures, or includes them.

Weiterhin kann vorgesehen sein, dass die externe Struktur eine regelmäßige oder unregelmäßige Struktur ist.Furthermore, it can be provided that the external structure is a regular or irregular structure.

Die die Lage aus Polymerschaum weist eine Porendichte von weniger als 30 PPI auf. In einem solchen Fall weisen die Poren häufig eine Größe auf, die für die Übertragung der Struktur auf die Papierbahn sehr vorteilhaft ist.The polymeric foam layer has a pore density of less than 30 PPI. In such a case, the pores are often of a size that is very advantageous for transferring the structure to the paper web.

In einer weiteren vorteilhaften Ausführung kann die Lage aus Polymerschaum mittels Prägen, Einbrennen, Ätzen, Schneiden oder Stanzen mit einer externen Struktur versehen sein. Beispielsweise kann das strukturierte Formierband dadurch mit einer externen Struktur versehen werden, dass die Lage aus Polymerschaum kompaktiert wird und beim Kompaktieren eine heiße Walze zum Einsatz kommt, die mit der Lage aus Polymerschaum in Kontakt gebracht wird. Diese Walze kann vorteilhafterweise so ausgerüstet sein, dass eine auf den Schaum zu übertragende Struktur als Negativ in die Walzenoberfläche eingearbeitet ist. Diese Struktur kann aus einem wärmeleitenden Material sein (z.B. Metall) oder aus einem nichtwärmeleitenden Material wie einem Polymer (z.B. ein Silikon). Während des Kompaktierens wird die Struktur dann in die Oberfläche der Schaumlage eingeprägt. Alternativ oder zusätzlich ist auch möglich, Strukturelemente in die Walzenoberfläche einzuarbeiten; z.B. einzugravieren. Diese Strukturelemente verbleiben dann nach dem Kompaktieren als erhabene Elemente in der Schaumlage.In a further advantageous embodiment, the layer of polymer foam can be provided with an external structure by means of embossing, firing, etching, cutting or stamping. For example, the structured forming belt can be provided with an external structure by compacting the layer of polymeric foam and using a hot roller in contact with the layer of polymeric foam during the compaction. This roller can advantageously be equipped in such a way that a structure to be transferred to the foam is worked into the roller surface as a negative. This structure can be made of a thermally conductive material (eg, metal) or of a non-thermally conductive material such as a polymer (eg, a silicone). During compaction, the structure is then embossed into the surface of the foam layer. Alternatively or additionally, it is also possible to incorporate structural elements into the roller surface; eg to engrave. After compacting, these structural elements then remain as raised elements in the foam layer.

Für die Lage aus Polymerschaum kann eine Vielzahl geeigneter Polymermaterialien zum Einsatz kommen. So kann vorteilhafterweise vorgesehen sein, dass die Lage aus Polymerschaum aus einem Elastomer, insbesondere aus einem Polyurethan besteht, oder dieses umfasst. In einer anderen vorteilhaften Ausführung kann vorgesehen sein, dass die Lage aus Polymerschaum aus einem Polyamid, Polyester, Polyethylen oder einem Silikon besteht, oder dieses umfasst. Diese Materialien sind für das Formierband vorteilhaft, jedoch ist die Erfindung nicht auf diese Materialien beschränkt.A variety of suitable polymeric materials can be used for the layer of polymeric foam. It can thus advantageously be provided that the layer of polymer foam consists of or comprises an elastomer, in particular a polyurethane. In another advantageous embodiment, it can be provided that the layer of polymer foam consists of or comprises a polyamide, polyester, polyethylene or a silicone. These materials are advantageous for the forming belt, but the invention is not limited to these materials.

In einer weiteren vorteilhaften Ausführung kann vorgesehen sein, dass die Lage aus Polymerschaum eine anisotrope Porenstruktur aufweist. Bei einer solchen anisotropen Struktur weicht die Form zumindest eines Großteils (häufig mehr als 50%, oder auch mehr als 80%) der einzelnen Poren von der isotropen Kugelform ab. So kann in einer vorteilhaften Ausführungsform vorgesehen sein, dass die Poren in Maschinenrichtung der Bespannung und in Querrichtung der Bespannung eine größere Ausdehnung aufweisen, als in der Dickenrichtung. Eine derartige Porenstruktur kann beispielsweise durch eine Komprimierung einer Schaumlage mit isotroper Porenstruktur erreicht werden. Häufig kann durch eine solche anisotrope Porenstruktur das Wasser schnell von der Papierbahn weg Richtung Tragstruktur geleitet werden. Auch stellt die Schaumlage dadurch üblicherweise weniger Speichervolumen zur Verfügung.In a further advantageous embodiment it can be provided that the layer of polymer foam has an anisotropic pore structure. With such an anisotropic structure, the shape of at least a large part (often more than 50%, or even more than 80%) of the individual pores deviates from the isotropic spherical shape. Thus, in an advantageous embodiment, it can be provided that the pores have a greater extent in the machine direction of the clothing and in the transverse direction of the clothing than in the thickness direction. Such a pore structure can be achieved, for example, by compressing a foam layer with an isotropic pore structure. Such an anisotropic pore structure can often lead the water away from the paper web in the direction of the supporting structure. The foam layer also usually provides less storage volume as a result.

Die Verbindung der Lage aus Polymerschaum mit der Tragstruktur die Lage aus Polymerschaum mit der Tragstruktur kann vorteilhafterweise mittels Verkleben oder Verschweißen, insbesondere mittels NIR Transmissionsschweißen realisiert sein.The connection of the layer made of polymer foam to the supporting structure can advantageously be realized by means of gluing or welding, in particular by means of NIR transmission welding.

Weiterhin umfasst die Erfindung eine Maschine zur Herstellung einer Faserstoffbahn, insbesondere einer Tissuebahn, dadurch gekennzeichnet, dass die Maschine zumindest ein Formierband gemäß einem der Ansprüche 3-8 aufweist. Eine solche Maschine ist geeignet, das erfindungsgemäße Verfahren nach einem der Ansprüche 1-2 durchzuführen und eine strukturierte Faserstoffbahn zu erzeugen.Furthermore, the invention comprises a machine for producing a fibrous web, in particular a tissue web, characterized in that the machine has at least one forming belt according to one of Claims 3-8. Such a machine is suitable for carrying out the method according to one of Claims 1-2 according to the invention and for producing a structured fibrous web.

Im Folgenden wird die Erfindung anhand von schematischen, nicht maßstäblichen Zeichnungen weiter erläutert.

  • Figur 1 zeigt eine Ausführung eines strukturierten Formierbands gemäß der Erfindung.
  • Figur 2 zeigt schematisch die Bildung der Faserstoffbahn auf dem Formierband
  • Figur 3 zeigt einen Ausschnitt aus der Oberfläche eine Walze zur Übertragung einer externen Struktur auf eine Lage aus Polymerschaum.
  • Figur 4 zeigt eine Ansicht eines erfindungsgemäßen strukturierten Formierbands.
The invention is explained in more detail below with the aid of schematic drawings that are not to scale.
  • figure 1 Figure 12 shows an embodiment of a structured forming belt according to the invention.
  • figure 2 shows schematically the formation of the fibrous web on the forming belt
  • figure 3 shows a section of the surface of a roller for transferring an external structure to a layer of polymer foam.
  • figure 4 shows a view of a structured forming belt according to the invention.

In Figur 1 ist grob schematisch der Aufbau einer möglichen Ausführung des strukturierten Formierbands 1 gezeigt. In der hier gezeigten Ausführung umfasst das das strukturierte Formierband 1 ein Gewebe 3, das die Tragstruktur 3 zur Verfügung stellt. Auf dieser Tragstruktur 3 ist eine Lage aus Polymerschaum 2 befestigt. Diese kann beispielsweise aus einem Polyurethan Weichschaum bestehen. Diese Lage aus Polymerschaum 2 stellt auch die papierberührende Seite 5 des strukturierten Formierbands 1 zur Verfügung. Die Poren 4 der Lage aus Polymerschaum 2 sind in der in Figur 1 gezeigten Bespannung anisotrop. Die kann beispielsweise dadurch realisiert werden, dass ein standard Polymerschaum, welcher üblicherweise isotrope Poren aufweist, durch einen Kompaktierungsschritt mittels Druck und/oder Temperatur kompaktiert worden ist. Dadurch ändert sich neben der Dicke der Schaumlage 2 auch die Form der Poren 4. Sie werden in Dickenrichtung deformiert. An einem exemplarischen Beispiel soll ein mögliches Herstellungsverfahren für ein des strukturiertes Formierband wie in Figur 1 gezeigt erläutert werden. In dem Beispiel wird zuerst eine gewebte Tragstruktur 3 zur Verfügung gestellt wird. Diese ist aus Polyesterfilamenten gewebt sein. Zudem wird ein Schaum beispielsweise in Form eines retikulierten Polyurethan Weichschaums zur Verfügung gestellt. Dieser weist im Beispiel eine Dicke von 4mm und eine Porendichte von 45 PPI auf. Erfindungsgemäß werden Schäume mit einer Porendichte von weniger als 30 PPI eingesetzt.In figure 1 the structure of a possible embodiment of the structured forming belt 1 is shown in a roughly schematic manner. In the embodiment shown here, the structured forming belt 1 includes a fabric 3 that provides the support structure 3 . A layer of polymer foam 2 is attached to this supporting structure 3 . This can consist, for example, of a flexible polyurethane foam. This layer of polymer foam 2 also makes the paper-contacting side 5 of the structured forming belt 1 available. The pores 4 of the layer of polymer foam 2 are in figure 1 shown covering anisotropic. This can be realized, for example, by compacting a standard polymer foam, which usually has isotropic pores, in a compacting step using pressure and/or temperature. This changes not only the thickness of the foam layer 2 but also the shape of the pores 4. They are deformed in the direction of thickness. A possible manufacturing process for a structured forming belt as in figure 1 shown are explained. In the example, a woven support structure 3 is first made available. This is woven from polyester filaments. In addition, a foam is provided, for example in the form of a reticulated flexible polyurethane foam. In the example, this has a thickness of 4mm and a pore density of 45 PPI. According to the invention, foams with a pore density of less than 30 PPI are used.

Ein geeignetes Verfahren zum Verbinden der Lagen aus Polymerschaum 2 mit der Tragstruktur 3 stellt das Lasertransmisionsschweißen dar. Im Beispiel wird ein NIR Laser mit einer Wellenlänge von 940 nm eingesetzt. Dieser wurde mit einem Fügedruck von ca. 20N/cm angepresst. Besonders vorteilhaft ist es für das Lasertransmissionsschweißen, wenn der Polymerschaum 2 das Laserlicht ganz oder teilweise absorbiert, während die Tragstruktur 3 für das Laserlicht ganz oder weitgehend transparent ist. Dies wurde im Beispiel durch Färben des Polymerschaums realisiert, wo ein anthrazitfarbenener Schaum zum Einsatz kam. Durch die Wahl eines Grundgewebes aus Polyester konnte das Laserlicht zuerst die Tragstruktur 3 durchdringen, und wurde danach durch den Polymerschaum absorbiert wird. So wurde die zum Verschweißen notwendige Hitze an der Verbindungsstelle zwischen Tragstruktur 3 und Schaumlage 2 erzeugt. Dies ist ein übliches Prinzip im Lasertransmissionschwei ßen.A suitable method for connecting the layers of polymer foam 2 to the support structure 3 is laser transmission welding. In the example, an NIR Laser used with a wavelength of 940 nm. This was pressed on with a joining pressure of approx. 20N/cm. It is particularly advantageous for laser transmission welding if the polymer foam 2 completely or partially absorbs the laser light, while the supporting structure 3 is completely or largely transparent to the laser light. This was realized in the example by coloring the polymer foam, where an anthracite-colored foam was used. By choosing a base fabric made of polyester, the laser light could first penetrate the supporting structure 3 and was then absorbed by the polymer foam. In this way, the heat required for welding was generated at the connection point between the support structure 3 and the foam layer 2 . This is a common principle in laser transmission welding.

Das so verbundene Laminat wurde dann bei einer Temperatur von ca. 190° unter Druck kompaktiert. Die resultierende Bespannung 1, wies eine Permeabilität von 400CFM bei einer Dicke (gemessen unter 6kPa Druck) von 1.07 mm auf. Dabei betrug in dem Beispiel der Anteil der Tragstruktur 3 0.49mm, der Anteil der Schaumlage 2 0.58mm. Bei einer Ausgangsdicke des Schaums von 4mm wurde dieser durch das Verfahren auf 14.5% seiner Ausgangsdicke kompaktiert.The laminate connected in this way was then compacted under pressure at a temperature of approx. 190°. The resulting fabric 1 had a permeability of 400CFM at a thickness (measured under 6kPa pressure) of 1.07mm. In the example, the proportion of the support structure 3 was 0.49mm, the proportion of the foam layer 2 was 0.58mm. With an initial foam thickness of 4 mm, the process compacted it to 14.5% of its initial thickness.

Unter einem Druck von 50 kPa wurde das Laminat 1 auf 0.91 mm komprimiert, wobei die Dicke der Schaumlage 2 0.42mm betrug. Die Schaumlage wurde also bei diesem Druck um weitere 27% komprimiert. Beim Rücknahme des Drucks auf 6 kPa expandierte die Schaumlage wieder auf -im Rahmen der Messgenauigkeit- ihre Ausgangsdicke.The laminate 1 was compressed to 0.91 mm under a pressure of 50 kPa, the thickness of the foam layer 2 being 0.42 mm. The foam layer was thus compressed an additional 27% at this pressure. When the pressure was reduced to 6 kPa, the foam layer expanded again to its original thickness within the scope of measurement accuracy.

In Figur 2 ist schematisch die Bildung der Faserstoffbahn auf dem Formierband aus Figur 1 dargestellt. Der Prozess soll beispielhaft das Entstehen einer strukturierten Faserstoffbahn erläutern. Hierbei wird eine Suspension mit Fasern 6, insbesondere Zellstofffasern 6 auf das strukturierte Formierband 1 aufgegeben. Die Entwässerung erfolgt in Figur 2 von oben nach unten, das heißt das Wasser durchläuft zuerst due Lage aus Polymerschaum 2 und danach die Tragstruktur 3. Der Entwässerungsprozess kann durch ein in der Figur 2 nicht dargestelltes Entwässerungselement, z.B. einen Saugkasten unterstützt werden, welcher an der papierabgewandten Seite des Formierbands 1 angeordnet ist. Die Fasern 6 lagern sich bei diesem Prozess an der papierberührenden Seite 5 des Formierbandes 1 ab.In figure 2 is a schematic of the formation of the fibrous web on the forming belt figure 1 shown. The process is intended to explain the emergence of a structured fibrous web as an example. In this case, a suspension with fibers 6 , in particular cellulose fibers 6 , is applied to the structured forming belt 1 . Drainage takes place in figure 2 From top to bottom, that is, the water first passes through the layer of polymer foam 2 and then the supporting structure 3. The drainage process can be carried out by an in the figure 2 dewatering element, not shown, for example a suction box, which is arranged on the side of the forming belt 1 facing away from the paper. During this process, the fibers 6 are deposited on the side 5 of the forming belt 1 that comes into contact with the paper.

Diese papierberührende Seite 5 wird durch die Lage aus Polymerschaum 2 zur Verfügung gestellt. Durch die Porenstruktur des Polymerschaum 2 werden können einige der Fasern 6 durch größere Poren 4 in die Lage aus Polymerschaum 2 eindringen und lagern sich in diesen Poren 4 ab. Auf dieser Weise wird die Struktur des Formierbands 1, insbesondere die Porenstruktur der Lage aus Polymerschaum 2 zumindest teilweise auf die Faserstoffbahn übertragen. Dieser Effekt des Ablagerns von Fasern in der Porenstruktur kann durch eine passende Wahl des Polymerschaums unterstützt werden.This paper-contacting side 5 is provided by the layer of polymer foam 2. Due to the pore structure of the polymer foam 2 , some of the fibers 6 can penetrate through larger pores 4 into the layer of polymer foam 2 and are deposited in these pores 4 . In this way, the structure of the forming belt 1, in particular the pore structure of the layer of polymer foam 2, is at least partially transferred to the fibrous web. This effect of depositing fibers in the pore structure can be supported by a suitable choice of polymer foam.

Eine strukturierte Faserstoffbahn, welche mittels eines erfindungsgemäßen Verfahrens hergestellt worden ist, kann gegenüber einer vergleichbaren nichtstrukturierten Faserstoffbahn beispielsweise bzgl. Dicke und Porosität große Vorteile aufweisen. Durch die größere Dicke können auch Faserbahnen mit niedrigerer Flächenmasse hergestellt werden, welche trotzdem alle gewünschten Produkteigenschaften aufweisen. Durch die so erzielbare Einsparung an Fasermaterial ist das Verfahren auch ökonomisch sehr vorteilhaft.A structured fibrous web which has been produced using a method according to the invention can have major advantages over a comparable non-structured fibrous web, for example with regard to thickness and porosity. Due to the greater thickness, fiber webs with a lower basis weight can also be produced, which nevertheless have all the desired product properties. Due to the savings in fiber material that can be achieved in this way, the process is also very advantageous from an economic point of view.

Beispielhaft soll an dem folgenden Versuchsergebnis dargestellt werden, welche Effekte durch eine erfindungsgemäß hergestellte strukturierte Faserstoffbahn im Vergleich zu einer auf einem herkömmlichen SSB Sieb gebildeten Bahn erzielt werden können: Formierband Flächenmasse Dicke Dichte Porosität (Bendtsen) 1. SSB Sieb 86.2 [g/m2] 132 [µm] 0.653 [g/cm3] 421 [ml/min] 2. strukturiertes Formierband 81.5 [g/m2] 149 [µm] 0.547 [g/cm3] 955 [ml/min] The following test result should be used as an example to show what effects can be achieved by a structured fibrous web produced according to the invention compared to a web formed on a conventional SSB wire: forming belt basis weight thickness density porosity (Bendtsen) 1. SSB screen 86.2 [g/m 2 ] 132 [µm] 0.653 [g/cm 3 ] 421 [ml/min] 2. structured forming belt 81.5 [g/m 2 ] 149 [µm] 0.547 [g/cm 3 ] 955 [ml/min]

Hierbei ist insbesondere die erhöhte Dicke bei niedrigerer Flächenmasse, sowie die deutlich erhöhte Porosität des strukturierten Produkts auffällig.The increased thickness with a lower basis weight and the significantly increased porosity of the structured product are particularly noticeable here.

Figur 3 zeigt einen Ausschnitt aus der Oberfläche einer Walze zur Übertragung einer externen Struktur auf eine Lage aus Polymerschaum 2. In dem hier gezeigten Beispiel weist die Walze sowohl erhabene Strukturelemente 11a, 11b auf, welche in eine Lage aus Polymerschaum 2 eingeprägt werden. Außerdem weist der Ausschnitt in Figur 3 eine Vielzahl von Strukturelementen 10 auf, welche als runde Vertiefungen in der Walzenoberfläche ausgeführt sind. Diese Strukturelemente werden als erhabene Elemente auf die Schaumlage 2 übertragen. figure 3 shows a section of the surface of a roller for transferring an external structure to a layer of polymer foam 2. In the example shown here, the roller has both raised structural elements 11a, 11b, which are embossed into a layer of polymer foam 2. In addition, the section in figure 3 a multiplicity of structural elements 10, which are designed as round depressions in the roll surface. These structural elements are transferred to the foam layer 2 as raised elements.

Bei dem in Figur 3 gezeigten Beispiel sind sowohl die Walzenoberfläche als auch die erhabenen Strukturelemente 11a, 11b aus Metall ausgeführt. Es kann jedoch auch vorgesehen sein, dass diese erhabenen Strukturelemente 11a, 11b ganz oder Teilweise aus einem nichtwärmeleitenden Material, z.B. einem Polymer bestehen. Obwohl das Übertragen der Strukturelemente 10, 11a, 11b auf den Polymerschaum 2 mittels einer solchen oder ähnlichen Walze prinzipiell in einem gesonderten Arbeitsschritt im Vorfeld oder im Anschluss der Herstellung der Bespannung erfolgen kann, wird die Übertragung jedoch häufig vorteilhafterweise zusammen mit dem Kompaktieren der Schaumlage erfolgen. Auf diese Weise kann ein Prozessschritt bei der Herstellung der Bespannung entfallen. Zudem ist keine zusätzliche Geräte für diese Übertragung notwendig.At the in figure 3 In the example shown, both the roller surface and the raised structural elements 11a, 11b are made of metal. However, it can also be provided that these raised structural elements 11a, 11b consist entirely or partially of a non-thermally conductive material, for example a polymer. Although the structural elements 10, 11a, 11b can in principle be transferred to the polymer foam 2 by means of such a roller or a similar roller in a separate work step before or after the production of the covering, the transfer will often advantageously take place together with the compacting of the foam layer . In this way, a process step in the production of the covering can be omitted. In addition, no additional devices are required for this transmission.

Figur 4 zeigt schließlich eine stark vergrößerte Ansicht eines erfindungsgemäßen strukturierten Formierbandes 1. Der Blick erfolgt auf die papierberührende Seite des Formierbandes 1. Man erkennt die Lage aus Polymerschaum 2, und durch die Poren 4 ist das darunterliegende Gewebe 3 der Tragstruktur 3 zu erkennen. Beim Prozess der Blattbildung werden sich Fasern 6 sowohl auf den Stegen 7 aus Polymermaterial ablegen, als auch ganz oder teilweise in die Poren 4 der Lage aus Polymerschaum eindringen. Der Durchmesser "d" einer solchen Pore beträgt in Figur 4 ca. 1 mm. In anderen vorteilhaften Formierbändern können aber auch kleinere Poren z.B. mit Durchmessern 750 µm, 500µm oder darunter oder auch größere Poren mit Durchmesssern von 1.5 mm, 2 mm oder darüber verwendet werden. Üblicherweise werden die Porengrößen in eine, strukturierten Formierband eine gewisse Verteilung aufweisen. figure 4 Finally, FIG. 1 shows a greatly enlarged view of a structured forming belt 1 according to the invention. The view is on the side of the forming belt 1 that comes into contact with the paper. During the sheet formation process, fibers 6 are deposited both on the webs 7 made of polymer material and penetrate completely or partially into the pores 4 of the layer made of polymer foam. The diameter "d" of such a pore is in figure 4 about 1mm. However, smaller pores, for example with diameters of 750 μm, 500 μm or less, or also larger pores with diameters of 1.5 mm, 2 mm or more can also be used in other advantageous forming belts. The pore sizes in a structured forming belt will usually have a certain distribution.

Claims (9)

  1. Method for producing a structured fibrous web, in particular a tissue web, in which method a fibrous suspension is brought into contact with at least one structured forming belt (1) and is dewatered by means of at least one dewatering element, in particular a suction element, wherein the at least one structured forming belt (1) comprises a tier of polymer foam (2) which provides the paper-contacting side (5) of the structured forming belt (1), wherein the structure of the foam tier (2) at least in part is transferred to the fibrous web;
    wherein at least part of the structure of the tier of polymer foam (2) that is transferred to the fibrous web is a pore structure of the tier of polymer foam (2); and
    the tier of polymer foam (2) has a pore density of less than 30 PPI.
  2. Method according to Claim 12, wherein at least part of the structure of the tier of polymer foam (2) that is transferred to the fibrous web is an external structure (10, 11a, 11b) which has been incorporated in the tier of polymer foam (2) in particular by embossing, branding, etching, cutting, or punching.
  3. Structured forming belt (1) for a machine for producing a fibrous web, in particular a tissue web, wherein the structured forming belt (1) has a paper-contacting side (5) and a running side, comprising a support structure (3) and at least one tier of polymer foam (2), wherein the tier of polymer foam (2) provides the paper-contacting side (5) of the covering (1), and the paper-contacting side (5) of the covering is suitable for transferring a structure to the fibrous web, wherein the structure is or comprises a non-uniform structure in the form of the pore structure of the tier of polymer foam (2), characterized in that the tier of polymer foam (2) has a pore density of less than 30 PPI.
  4. Structured forming belt (1) according to Claim 3, characterized in that the tier of polymer foam (2) by means of embossing, branding, etching, cutting, or punching is provided with an external structure (10, 11a, 11b).
  5. Structured forming belt (1) according to one of Claims 3 to 4, characterized in that the tier of polymer foam (2) is composed of or comprises an elastomer, in particular is composed of or comprises a polyurethane.
  6. Structured forming belt (1) according to one of Claims 3 to 5, characterized in that the tier of polymer foam (2) is composed of or comprises a polyamide, polyester, or polyethylene.
  7. Structured forming belt (1) according to one of claims 3 to 6, characterized in that the tier of polymer foam (2) has an anisotropic pore structure, wherein more than 50% of the pores in the machine direction and in the cross direction of the structured forming belt (1) have a larger extent than in the thickness direction.
  8. Structured forming belt (1) according to one of Claims 3 to 7 characterized in that the tier of polymer foam (2) by means of adhesive bonding or welding, in particular by means of NIR transmission welding, is connected to the support structure (3).
  9. Machine for producing a fibrous web, in particular a tissue web, characterized in that the machine has at least one structured forming belt (1) according to one of Claims 3 to 8.
EP17718855.4A 2016-04-15 2017-04-10 Method and forming belt for producing a fibre material web Active EP3443161B1 (en)

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DE102016206387.1A DE102016206387A1 (en) 2016-04-15 2016-04-15 Method and forming belt for producing a fibrous web
PCT/EP2017/058512 WO2017178414A1 (en) 2016-04-15 2017-04-10 Method and forming belt for producing a fibre material web

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EP3443161A1 EP3443161A1 (en) 2019-02-20
EP3443161B1 true EP3443161B1 (en) 2022-07-06

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EP17718855.4A Active EP3443161B1 (en) 2016-04-15 2017-04-10 Method and forming belt for producing a fibre material web

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US (1) US10934664B2 (en)
EP (1) EP3443161B1 (en)
DE (1) DE102016206387A1 (en)
WO (1) WO2017178414A1 (en)

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Publication number Priority date Publication date Assignee Title
WO2021170361A1 (en) * 2020-02-27 2021-09-02 Voith Patent Gmbh Paper machine covering
US20230140783A1 (en) * 2021-11-04 2023-05-04 The Procter & Gamble Company Web material structuring belt, method for making and method for using
WO2023081744A1 (en) * 2021-11-04 2023-05-11 The Procter & Gamble Company Web material structuring belt, method for making structured web material and structured web material made by the method

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Publication number Priority date Publication date Assignee Title
US3617442A (en) * 1968-09-30 1971-11-02 Alfred A Hurschman Paper-making means and method
US5429686A (en) 1994-04-12 1995-07-04 Lindsay Wire, Inc. Apparatus for making soft tissue products
US6610619B2 (en) * 1999-12-29 2003-08-26 Kimberly-Clark Worldwide, Inc. Patterned felts for bulk and visual aesthetic development of a tissue basesheet
US6878238B2 (en) * 2002-12-19 2005-04-12 Kimberly-Clark Worldwide, Inc. Non-woven through air dryer and transfer fabrics for tissue making
DE102006055828A1 (en) * 2006-11-27 2008-05-29 Voith Patent Gmbh Band for use in course material e.g. paper, production machine, has machine contact side, and course material contact side including auxetic material that provides openings at course material contact surface
DE102008001854A1 (en) 2008-05-19 2009-11-26 Voith Patent Gmbh Press Felt
ES2660688T3 (en) * 2008-09-11 2018-03-23 Albany International Corp. Permeable band for the manufacture of fabrics, towels and nonwovens
US20120024489A1 (en) 2010-07-30 2012-02-02 Scott Quigley Structured fabric
WO2015090797A1 (en) * 2013-12-20 2015-06-25 Voith Patent Gmbh Fabric and method for producing same
DE102014220828B4 (en) * 2014-10-15 2019-05-23 Voith Patent Gmbh Functional band, process for its preparation and its use

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US20190112763A1 (en) 2019-04-18
DE102016206387A1 (en) 2017-10-19
US10934664B2 (en) 2021-03-02
WO2017178414A1 (en) 2017-10-19
EP3443161A1 (en) 2019-02-20

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