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EP0440076B1 - Press felt - Google Patents

Press felt Download PDF

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Publication number
EP0440076B1
EP0440076B1 EP91100783A EP91100783A EP0440076B1 EP 0440076 B1 EP0440076 B1 EP 0440076B1 EP 91100783 A EP91100783 A EP 91100783A EP 91100783 A EP91100783 A EP 91100783A EP 0440076 B1 EP0440076 B1 EP 0440076B1
Authority
EP
European Patent Office
Prior art keywords
press felt
paper
barrier layer
material web
layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91100783A
Other languages
German (de)
French (fr)
Other versions
EP0440076A3 (en
EP0440076A2 (en
Inventor
Sylvester Eschmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heimbach GmbH and Co KG
Original Assignee
Thomas Josef Heimbach and Co GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomas Josef Heimbach and Co GmbH filed Critical Thomas Josef Heimbach and Co GmbH
Publication of EP0440076A2 publication Critical patent/EP0440076A2/en
Publication of EP0440076A3 publication Critical patent/EP0440076A3/en
Application granted granted Critical
Publication of EP0440076B1 publication Critical patent/EP0440076B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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

Definitions

  • the invention relates to a press felt for the press area of a paper machine with a carrier material web made of one or more woven or knitted fabrics and a fiber layer applied at least on the paper side and connected to the carrier material web, the surface of which forms the paper contact side.
  • Press felts are known from numerous publications, for example from US Pat. No. 4,283,454 and US Pat. No. 4,564,985. Both publications show a press felt which, on the side facing away from the paper contact side, has a carrier material web which consists of two superimposed fabrics. These two tissues are connected to each other by a needled fiber layer, in that the fibers have been needled deep into both tissues. The top of the fiber layer then forms the soft paper contact side.
  • press felts are known, the backing material webs of which are formed from thread layers (EP-A-0 ⁇ 0 ⁇ 38 276), a fiber layer also being able to be provided between the individual thread layers (US Pat. No. 4,781,967).
  • the top thread laid in each case runs in the longitudinal direction.
  • the individual layers of thread are not integrated with each other.
  • a press felt is known from US Pat. No. 1,651,476, in which a web of carrier material is formed onto a web Fiber layer is glued, the gluing being carried out by means of an adhesive layer applied to the carrier material web.
  • This adhesive layer is porous and therefore permeable to the liquid squeezed out of the paper web.
  • press felts there is the problem of rewetting the paper web after leaving the press nip.
  • the previously compressed press felt then increases its cross section. This causes a delay in the water flow.
  • the water follows the higher capillarity and is distributed over the entire press felt cross section up to the paper contact side. In this way, part of the water already removed from the paper web is returned to it.
  • a press felt is proposed in US Pat. No. 4,772,50 774, in which the paper contact side is formed by a surface layer applied to the felt layer.
  • This surface layer consists of plastic, for example a plastic foam, the pores of which are to be almost completely filled by a sealing material. Accordingly, the maximum values given for the permeability of the surface layer are extremely low and tend towards zero.
  • the surface layer is intended to have a greater resistance to the water in the felt towards the paper contact side than towards the other side, thereby preventing rewetting of the paper web.
  • the invention has for its object to form a press felt of the type mentioned so that its drainage performance is improved, in particular by reducing the rewetting of the paper web.
  • the permeable layer is designed as a barrier layer with a surface coverage of 45% to 85%, the barrier layer having elongated passage openings oriented in the transverse direction.
  • the layer serving as an adhesive layer in the generic press felt is designed as a barrier layer which reduces the flow cross-section to 15% to 55% of the area of the press felt.
  • the result of this is that the water flowing through the press felt is accelerated in the area of the barrier layer due to the nozzle effect of the passage openings.
  • This creates a pressure gradient that propagates up to the paper web in the area between the paper contact side and the barrier position, which sucks the water out of the paper web as it were.
  • the passage openings are elongated and oriented in the transverse direction. They then act like foils, which are used in the forming area of paper machines, and thus support the aforementioned suction effect. Despite the area coverage caused by the blocked location, the drainage is even improved.
  • the blocking position After leaving the press nip, the blocking position practically acts as a check valve.
  • the felt then wants to expand again, but due to the blocked position, there is little air or Draw moisture from the area below the barrier layer.
  • the press felt does not expand so quickly, which means that it lifts off the paper web earlier. The rewetting is thereby reduced to a minimum.
  • the press felt according to the invention thus has a significantly improved drainage performance.
  • the barrier layer can be applied directly to the carrier material web. If the fiber layer is then needled into the carrier material web, it is still located within the fiber layer. However, there is also the possibility that the barrier layer is arranged at a distance from the carrier material web, the spacing of the barrier layer from the paper contact side is expediently at most as large as the distance from the carrier material web, the barrier layer therefore preferably in the area adjacent to the paper contact side - but not in its surface - lies.
  • the passage openings are preferably designed as elongated slots which extend in the transverse direction and should be formed as continuously as possible.
  • the slots are then preferably formed by transverse threads arranged at a distance from one another, which represent the blocking position. It is particularly advantageous if the transverse threads are designed as flat wires, as are known for example from EP-PS 0 ⁇ 0 ⁇ 98 612. The foil effect mentioned above is then particularly pronounced.
  • the press felt can be produced by first forming a fabric from the said transverse threads and from dissolvable, in particular water-soluble, longitudinal threads, and after the production of the press felt, the longitudinal threads are detached by soaking with a solvent. The cross threads forming the blocking position then remain.
  • the press felt (1) shown in the figures has a carrier fabric (2) in the lower region, which consists of two layers of longitudinal threads - denoted by (3) for example - and transverse threads integrating the longitudinal threads of both layers - denoted by (4), for example .
  • the longitudinal threads (3) and the transverse threads (4) are designed as monofilaments. Suitable plastics, for example polyamides or polyesters, are used as the material for this.
  • the free side is the paper contact side (6).
  • a barrier layer (7) is inserted, which consists of a plurality of flat wires extending in the transverse direction - that is, transverse to the running direction of the press felt (1) - designated by (8) for example.
  • the blocking position (7) runs parallel to the paper contact side (6).
  • the flat wires (8) are also made of plastic and have an approximately rectangular cross section, the extent in the plane of the barrier layer (7) being considerably larger than perpendicular to it.
  • the flat wires (8) are kept at a distance such that slots are formed between them, for example designated (9). According to the invention, the total passage cross section of these slots (9) should make up between 15% and 55% of the total area of the press felt (1).
  • this press felt (1) can be carried out in the following way be performed. First the base fabric (2) is woven. A first nonwoven layer is then placed on the carrier fabric (2) and needled to the carrier fabrics (2). At the same time, the barrier layer (7) is first produced in the form of a fabric by binding the flat wires (8) with water-soluble longitudinal threads, for example made of polyvinyl alcohol. This barrier layer (7) in tissue form is placed on the first part of the fiber layer (5). Then another non-woven layer is placed on the barrier layer (7) and needled to the remaining part of the press felt (1). Finally, the press felt (1) is subjected to a water treatment which results in the longitudinal threads of the barrier layer (7) being detached. Only the flat wires (8) remain. The press felt (1) then has the structure shown in Figures (1) and (2).
  • the flat wires (8) in the area of the press nip cause the water on the flat wires (8) to be deflected and accelerated in the area of the slots (9). This creates a similar effect to that of foils in the forming area of paper machines.
  • the water moves faster than the press felt (1), which creates a suction effect in the area of the paper contact side (6).
  • the press felt (1) When leaving the press nip, a vacuum is created above the barrier layer (7) because the previously compressed press felt (1) wants to expand again, but hardly any air or moisture can be drawn in from below. Above the barrier layer (7), the press felt (1) is no longer filled with water. Since the press felt (1) expands only after a delay, it lifts off the paper web (1) earlier, so that the residual moisture that is not present above the barrier layer (7) is no longer released to the paper web.

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  • Paper (AREA)
  • Presses And Accessory Devices Thereof (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

A press felt for the press area of a paper machine has a supporting material web made of one or more woven fabrics or knitted fabrics and a fibre layer applied at least to the paper side and associated with the supporting material web, the surface of which forms the paper contact side and in which a permeable layer is arranged between the paper contact side and supporting material web. To improve the dewatering power, the permeable layer is designed as a barrier layer (7) having a surface covering of 45% to 85%, the barrier layer (7) having elongated passage openings (9) aligned in the transverse direction. <IMAGE>

Description

Die Erfindung betrifft einen Preßfilz für den Pressenbereich einer Papiermaschine mit einer Trägermaterialbahn aus einem oder mehreren Geweben oder Gewirken und einer wenigstens auf der Papierseite aufgebrachten und mit der Trägermaterialbahn verbundenen Faserschicht, deren Oberfläche die Papierberührungsseite bildet.The invention relates to a press felt for the press area of a paper machine with a carrier material web made of one or more woven or knitted fabrics and a fiber layer applied at least on the paper side and connected to the carrier material web, the surface of which forms the paper contact side.

Preßfilze sind aus zahlreichen Veröffentlichungen bekannt, beispielsweise aus der US-PS 4 283 454 und der US-PS 4 564 985. Beide Druckschriften zeigen einen Preßfilz, welcher auf der der Papierberührungsseite abgewandten Seite eine Trägermaterialbahn aufweist, die aus zwei übereinandergelegten Geweben besteht. Diese beiden Gewebe sind durch eine aufgenadelte Faserschicht miteinander verbunden, indem die Fasern tief in beide Gewebe eingenadelt worden sind. Die Oberseite der Faserschicht bildet dann die weiche Papierberührungsseite.Press felts are known from numerous publications, for example from US Pat. No. 4,283,454 and US Pat. No. 4,564,985. Both publications show a press felt which, on the side facing away from the paper contact side, has a carrier material web which consists of two superimposed fabrics. These two tissues are connected to each other by a needled fiber layer, in that the fibers have been needled deep into both tissues. The top of the fiber layer then forms the soft paper contact side.

Daneben sind Preßfilze bekannt, deren Trägermaterialbahnen aus Fadengelegen gebildet sind (EP-A-0̸ 0̸38 276), wobei zwischen die einzelnen Fadengelege zusätzlich auch eine Faserschicht vorgesehen sein kann (US-PS 4 781 967). Das jeweils oberste Fadengelege verläuft in Längsrichtung. Im Unterschied zu den Trägermaterialien aus Geweben oder Gewirken sind hier die einzelnen Fadenlagen nicht miteinander eingebunden.In addition, press felts are known, the backing material webs of which are formed from thread layers (EP-A-0̸0̸38 276), a fiber layer also being able to be provided between the individual thread layers (US Pat. No. 4,781,967). The top thread laid in each case runs in the longitudinal direction. In contrast to the base materials made from woven or knitted fabrics, the individual layers of thread are not integrated with each other.

Aus der US-PS 1 651 476 ist ein Preßfilz bekannt, bei dem auf eine als Gewebe ausgebildete Trägermaterialbahn eine Faserschicht aufgeklebt ist, wobei die Verklebung mittels einer auf die Trägermaterialbahn aufgebrachten Klebelage erfolgt. Dabei ist diese Klebelage porös ausgebildet und demnach für die aus der Papierbahn ausgepreßte Flüssigkeit durchlässig.A press felt is known from US Pat. No. 1,651,476, in which a web of carrier material is formed onto a web Fiber layer is glued, the gluing being carried out by means of an adhesive layer applied to the carrier material web. This adhesive layer is porous and therefore permeable to the liquid squeezed out of the paper web.

Bei Preßfilzen besteht das Problem der Rückbefeuchtung der Papierbahn nach Verlassen des Preßenspaltes. Der zuvor komprimierte Preßfilz vergrößert dann seinen Querschnitt. Hierdurch tritt eine Verzögerung des Wasserdurchflusses ein. Das Wasser folgt der höheren Kapillarität und verteilt sich über den ganzen Preßfilzquerschnitt bis hin zur Papierberührungsseite. Auf diese Weise wird ein Teil des schon aus der Papierbahn entfernten Wassers wieder an diese zurückgegeben.With press felts, there is the problem of rewetting the paper web after leaving the press nip. The previously compressed press felt then increases its cross section. This causes a delay in the water flow. The water follows the higher capillarity and is distributed over the entire press felt cross section up to the paper contact side. In this way, part of the water already removed from the paper web is returned to it.

Zur Vermeidung dieses Problems ist in der US-PS 4 772 50̸4 ein Preßfilz vorgeschlagen, bei dem die Papierberührungsseite von einer auf die Filzschicht aufgebrachten Oberflächenschicht gebildet wird. Diese Oberflächenschicht besteht aus Kunststoff, beispielsweise aus einem Kunststoffschaum, dessen Poren durch ein Dichtmaterial nahezu vollständig gefüllt sein sollen. Entsprechend sind die angegebenen Maximalwerte für die Durchlässigkeit der Oberflächenschicht äußerst gering und tendieren gegen Null. Die Oberflächenschicht soll bewirken, daß dem im Filz befindlichen Wasser zur Papierberührungsseite hin ein größerer Widerstand entgegengesetzt wird als zur anderen Seite, wodurch eine Rückbefeuchtung der Papierbahn verhindert werden soll.To avoid this problem, a press felt is proposed in US Pat. No. 4,772,50 774, in which the paper contact side is formed by a surface layer applied to the felt layer. This surface layer consists of plastic, for example a plastic foam, the pores of which are to be almost completely filled by a sealing material. Accordingly, the maximum values given for the permeability of the surface layer are extremely low and tend towards zero. The surface layer is intended to have a greater resistance to the water in the felt towards the paper contact side than towards the other side, thereby preventing rewetting of the paper web.

Bei dieser Ausbildung des Preßfilzes ist nicht beachtet worden, daß die Hauptaufgabe eines Preßfilzes darin besteht, die ausgepreßte Flüssigkeit durch den Preßfilz hindurch zu transportieren und daß der Preßfilz hierfür entsprechend durchlässig sein muß. Mit der nahezu vollständigen Abdichtung der Papierberührungsseite muß deshalb ein entsprechender Abfall bei der Entwässerungsleistung in Kauf genommen werden, die auch nicht durch die behauptete Verringerung der Rückbefeuchtung kompensiert werden kann. Insgesamt wird die Entwässerungsleistung durch einen solchen Preßfilz gegenüber den konventionellen Preßfilzen nicht verbessert, der Aufwand für deren Herstellung aber vergrößert.In this design of the press felt it was not taken into account that the main task of a press felt is to transport the squeezed liquid through the press felt and that the press felt must be permeable for this purpose. With the almost complete sealing of the paper contact side, a corresponding drop in the drainage capacity must therefore be accepted cannot be compensated for by the alleged reduction in rewetting. Overall, the dewatering performance is not improved by such a press felt compared to conventional press felts, but the effort for their production is increased.

Der Erfindung liegt die Aufgabe zugrunde, einen Preßfilz der eingangs genannten Art so auszubilden, daß seine Entwässerungsleistung verbessert wird, insbesondere durch Verringerung der Rückbefeuchtung der Papierbahn.The invention has for its object to form a press felt of the type mentioned so that its drainage performance is improved, in particular by reducing the rewetting of the paper web.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die durchlässige Lage als Sperrlage mit einer Flächenabdeckung von 45% bis 85% ausgebildet ist, wobei die Sperrlage in Querrichtung orientierte, längliche Durchlaßöffnungen aufweist.This object is achieved in that the permeable layer is designed as a barrier layer with a surface coverage of 45% to 85%, the barrier layer having elongated passage openings oriented in the transverse direction.

Erfindungsgemäß ist die bei dem gattungsbildenden Preßfilz als Klebeschicht dienende Lage als eine Sperrlage ausgebildet, die den Durchflußquerschnitt auf 15% bis 55% der Fläche des Preßfilzes verringert. Dies hat zur Folge, daß das durch den Preßfilz hindurchfließende Wasser im Bereich der Sperrlage wegen der Düsenwirkung der Durchlaßöffnungen beschleunigt wird. Hierdurch entsteht im Bereich zwischen Papierberührungsseite und Sperrlage ein bis zur Papierbahn sich fortpflanzendes Druckgefälle, das das Wasser aus der Papierbahn gleichsam heraussaugt. Dabei ist von besonderer Bedeutung, daß die Durchlaßöffnungen länglich ausgebildet und in Querrichtung orientiert sind. Sie wirken dann wie Foils, welche im Formierbereich von Papiermaschinen eingesetzt werden, und unterstützen damit die vorerwähnte Sogwirkung. Trotz der von der Sperrlage bewirkten Flächenabdeckung wird demnach die Entwässerung sogar verbessert.According to the invention, the layer serving as an adhesive layer in the generic press felt is designed as a barrier layer which reduces the flow cross-section to 15% to 55% of the area of the press felt. The result of this is that the water flowing through the press felt is accelerated in the area of the barrier layer due to the nozzle effect of the passage openings. This creates a pressure gradient that propagates up to the paper web in the area between the paper contact side and the barrier position, which sucks the water out of the paper web as it were. It is particularly important that the passage openings are elongated and oriented in the transverse direction. They then act like foils, which are used in the forming area of paper machines, and thus support the aforementioned suction effect. Despite the area coverage caused by the blocked location, the drainage is even improved.

Nach Verlassen des Preßspaltes hat die Sperrlage praktisch die Wirkung eines Rückschlagventils. Der Filz will sich dann wieder ausdehnen, kann jedoch wegen der Sperrlage nur wenig Luft oder Feuchtigkeit aus dem Bereich unterhalb der Sperrlage nachziehen. Der Preßfilz dehnt sich deshalb nicht so schnell aus, was zur Folge hat, daß er sich früher von der Papierbahn abhebt. Die Rückbefeuchtung wird hierdurch auf ein Minimum herabgesetzt. Insgesamt hat also der erfindungsgemäße Preßfilz eine wesentlich verbesserte Entwässerungsleistung.After leaving the press nip, the blocking position practically acts as a check valve. The felt then wants to expand again, but due to the blocked position, there is little air or Draw moisture from the area below the barrier layer. The press felt does not expand so quickly, which means that it lifts off the paper web earlier. The rewetting is thereby reduced to a minimum. Overall, the press felt according to the invention thus has a significantly improved drainage performance.

Die Sperrlage kann unmittelbar auf die Trägermaterialbahn aufgebracht sein. Wenn die Faserschicht dann in die Trägermaterialbahn eingenadelt ist, befindet sie sich dann immer noch innerhalb der Faserschicht. Es besteht jedoch auch die Möglichkeit, daß die Sperrlage im Abstand zur Trägermaterialbahn angeordnet ist, wobei der Abstand der Sperrlage zur Papierberührungsseite zweckmäßigerweise maximal so groß wie der Abstand zur Trägermaterialbahn ist, die Sperrlage also vorzugsweise im der Papierberührungsseite benachbarten Bereich - nicht jedoch in deren Oberfläche - liegt.The barrier layer can be applied directly to the carrier material web. If the fiber layer is then needled into the carrier material web, it is still located within the fiber layer. However, there is also the possibility that the barrier layer is arranged at a distance from the carrier material web, the spacing of the barrier layer from the paper contact side is expediently at most as large as the distance from the carrier material web, the barrier layer therefore preferably in the area adjacent to the paper contact side - but not in its surface - lies.

Die Durchlassöffnungen sind bevorzugt als langgestreckte Schlitze ausgebildet, die sich in Querrichtung erstrecken und möglichst durchgehend ausgebildet sein sollen. Die Schlitze werden dann vorzugsweise durch im Abstand zueinander angeordnete Querfäden gebildet, die die Sperrlage darstellen. Von besonderem Vorteil ist, wenn die Querfäden als Flachdrähte ausgebildet sind, wie sie beispielsweise aus der EP-PS 0̸ 0̸98 612 bekannt sind. Die oben erwähnte Foilwirkung ist dann besonders ausgeprägt.The passage openings are preferably designed as elongated slots which extend in the transverse direction and should be formed as continuously as possible. The slots are then preferably formed by transverse threads arranged at a distance from one another, which represent the blocking position. It is particularly advantageous if the transverse threads are designed as flat wires, as are known for example from EP-PS 0̸0̸98 612. The foil effect mentioned above is then particularly pronounced.

Die Herstellung des Preßfilzes kann der Weise erfolgen, daß zunächst ein Gewebe aus den besagten Querfäden und aus auflösbaren, insbesondere wasserlöslichen Längsfäden gebildet wird und daß nach der Herstellung des Preßfilzes die Längsfäden durch Tränken mit einem Lösungsmittel herausgelöst werden. Übrig bleiben dann die die Sperrlage bildenden Querfäden.The press felt can be produced by first forming a fabric from the said transverse threads and from dissolvable, in particular water-soluble, longitudinal threads, and after the production of the press felt, the longitudinal threads are detached by soaking with a solvent. The cross threads forming the blocking position then remain.

In der Zeichnung ist die Erfindung an Hand eines Ausführungsbeispiels näher veranschaulicht. Es zeigen:

Figur (1)
einen Querschnitt durch einen Preßfilz und
Figur (2)
einen Längsschnitt durch den Preßfilz gemäß Figur (1).
In the drawing, the invention is illustrated in more detail using an exemplary embodiment. Show it:
Figure (1)
a cross section through a press felt and
Figure (2)
a longitudinal section through the press felt according to Figure (1).

Der in den Figuren dargestellte Preßfilz (1) weist im unteren Bereich ein Trägergewebe (2) auf, das aus zwei Lagen Längsfäden - beispielhaft mit (3) bezeichnet - und aus die Längsfäden beider Lagen einbindenden Querfäden - beispielhaft mit (4) bezeichnet - besteht. Die Längsfäden (3) und die Querfäden (4) sind als Monofilamente ausgebildet. Als Material hierfür werden geeignete Kunststoffe, beispielsweise Polyamide oder Polyester, verwendet.The press felt (1) shown in the figures has a carrier fabric (2) in the lower region, which consists of two layers of longitudinal threads - denoted by (3) for example - and transverse threads integrating the longitudinal threads of both layers - denoted by (4), for example . The longitudinal threads (3) and the transverse threads (4) are designed as monofilaments. Suitable plastics, for example polyamides or polyesters, are used as the material for this.

Auf der Oberseite des Trägergewebes (2) befindet sich eine Faserschicht (5) aus Kunststoffasern. Ihre freie Seite bildet die Papierberührungsseite (6). In die obere Hälfte der Faserschicht (5) ist eine Sperrlage (7) eingelegt, die aus einer Vielzahl von sich in Querrichtung - also quer zur Laufrichtung des Preßfilzes (1) - sich erstreckenden Flachdrähten - beispielhaft mit (8) bezeichnet - besteht. Die Sperrlage (7) verläuft parallel zur Papierberührungsseite (6). Die Flachdrähte (8) bestehen ebenfalls aus Kunststoff und haben in etwa rechteckigen Querschnitt, wobei die Erstreckung in der Ebene der Sperrlage (7) erheblich größer ist als senkrecht dazu. Die Flachdrähte (8) sind derart auf Abstand gehalten, daß zwischen Ihnen Schlitze - beispielhaft mit (9) bezeichnet - entstehen. Der Gesamtdurchtrittsquerschnitt dieser Schlitze (9) soll nach der Erfindung zwischen 15% und 55% der Gesamtfläche des Preßfilzes (1) ausmachen.There is a fiber layer (5) made of plastic fibers on the top of the carrier fabric (2). The free side is the paper contact side (6). In the upper half of the fiber layer (5) a barrier layer (7) is inserted, which consists of a plurality of flat wires extending in the transverse direction - that is, transverse to the running direction of the press felt (1) - designated by (8) for example. The blocking position (7) runs parallel to the paper contact side (6). The flat wires (8) are also made of plastic and have an approximately rectangular cross section, the extent in the plane of the barrier layer (7) being considerably larger than perpendicular to it. The flat wires (8) are kept at a distance such that slots are formed between them, for example designated (9). According to the invention, the total passage cross section of these slots (9) should make up between 15% and 55% of the total area of the press felt (1).

Die Herstellung dieses Preßfilzes (1) kann in folgender Weise durchgeführt werden. Zunächst wird das Trägergewebe (2) gewebt. Dann wird auf das Trägergewebe (2) eine erste Faservliesschicht aufgelegt und mit den Trägergeweben (2) vernadelt. Gleichzeitig wird die Sperrlage (7) zunächst in Form eines Gewebes hergestellt, indem die Flachdrähte (8) mit wasserlöslichen Längsfäden - beispielsweise aus Polyvinylalkohol - eingebunden werden. Diese Sperrlage (7) in Gewebeform wird auf den ersten Teil der Faserschicht (5) aufgelegt. Anschließend wird auf die Sperrlage (7) eine weitere Vliesschicht aufgelegt und mit dem übrigen Teil des Preßfilzes (1) vernadelt. Schließlich wird der Preßfilz (1) einer Wasserbehandlung ausgesetzt, die ein Herauslösen der Längsfäden der Sperrschicht (7) zur Folge hat. Übrig bleiben dann nur die Flachdrähte (8). Der Preßfilz (1) hat dann den in den Figuren (1) und (2) dargestellten Aufbau.The production of this press felt (1) can be carried out in the following way be performed. First the base fabric (2) is woven. A first nonwoven layer is then placed on the carrier fabric (2) and needled to the carrier fabrics (2). At the same time, the barrier layer (7) is first produced in the form of a fabric by binding the flat wires (8) with water-soluble longitudinal threads, for example made of polyvinyl alcohol. This barrier layer (7) in tissue form is placed on the first part of the fiber layer (5). Then another non-woven layer is placed on the barrier layer (7) and needled to the remaining part of the press felt (1). Finally, the press felt (1) is subjected to a water treatment which results in the longitudinal threads of the barrier layer (7) being detached. Only the flat wires (8) remain. The press felt (1) then has the structure shown in Figures (1) and (2).

Die Flachdrähte (8) bewirken im Bereich des Preßenspaltes, daß das Wasser an den Flachdrähten (8) abgelenkt und im Bereich der Schlitze (9) beschleunigt wird. Hierdurch entsteht eine ähnliche Wirkung wie bei Foils im Formierbereich von Papiermaschinen. Das Wasser bewegt sich schneller als der Preßfilz (1), wodurch praktisch eine Sogwirkung im Bereich der Papierberührungsseite (6) entsteht.The flat wires (8) in the area of the press nip cause the water on the flat wires (8) to be deflected and accelerated in the area of the slots (9). This creates a similar effect to that of foils in the forming area of paper machines. The water moves faster than the press felt (1), which creates a suction effect in the area of the paper contact side (6).

Beim Verlassen des Preßspaltes entsteht oberhalb der Sperrlage (7) ein Vakuum, da der zuvor komprimierte Preßfilz (1) sich wieder ausdehnen will, von unten jedoch kaum Luft oder Feuchtigkeit nachziehen. Oberhalb der Sperrlage (7) füllt sich der Preßfilz (1) also nicht mehr mit Wasser auf. Da der Preßfilz (1) sich nur verzögert ausdehnt, hebt er früher von der Papierbahn (1) ab, so daß die oberhalb der Sperrlage (7) nicht vorhandene Restfeuchte nicht mehr an die Papierbahn abgegeben wird.When leaving the press nip, a vacuum is created above the barrier layer (7) because the previously compressed press felt (1) wants to expand again, but hardly any air or moisture can be drawn in from below. Above the barrier layer (7), the press felt (1) is no longer filled with water. Since the press felt (1) expands only after a delay, it lifts off the paper web (1) earlier, so that the residual moisture that is not present above the barrier layer (7) is no longer released to the paper web.

Claims (7)

  1. A press felt (1) for the pressing region of a paper-making machine, with a support material web (2) comprising one or more woven or knitted fabrics and a fibrous layer (5) which is provided at least on the paper side and is attached to the support material web (2), the surface of which fibrous layer forms the paper contact side (6) and in which a permeable layer (7) is disposed between the paper contact side (6) and the support material web (2), characterised in that the permeable layer is constructed as a barrier layer (7) with 45 % to 85 % of its surface masked, wherein the barrier layer (7) comprises oblong passageway openings (9) oriented in the transverse direction.
  2. A press felt according to claim 1, characterised in that the barrier layer (7) is disposed at a distance from the support material web (2).
  3. A press felt according to claim 2, characterised in that the maximum distance of the barrier layer (7) from the paper contact side (6) is the same as its distance from the support material web (2).
  4. A press felt according to any one of claims 1 to 3, characterised in that the passageway openings are constructed as elongated channels (9).
  5. A press felt according to claim 4, characterised in that the channels (9) are of continuous construction.
  6. A press felt according to claim 5, characterised in that the channels (7) are formed by transverse filaments (8) disposed at a distance from each other.
  7. A press felt according to claim 6, characterised in that the transverse filaments are constructed as flat filaments (8).
EP91100783A 1990-01-31 1991-01-23 Press felt Expired - Lifetime EP0440076B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4002761A DE4002761A1 (en) 1990-01-31 1990-01-31 PRESS FELT
DE4002761 1990-01-31

Publications (3)

Publication Number Publication Date
EP0440076A2 EP0440076A2 (en) 1991-08-07
EP0440076A3 EP0440076A3 (en) 1991-10-16
EP0440076B1 true EP0440076B1 (en) 1994-06-29

Family

ID=6399101

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91100783A Expired - Lifetime EP0440076B1 (en) 1990-01-31 1991-01-23 Press felt

Country Status (7)

Country Link
EP (1) EP0440076B1 (en)
AT (1) ATE107980T1 (en)
CA (1) CA2034956C (en)
DE (2) DE4002761A1 (en)
DK (1) DK0440076T3 (en)
ES (1) ES2058943T3 (en)
FI (1) FI93239C (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9125889D0 (en) * 1991-12-05 1992-02-05 Albany Research Uk Improvements in and relating to paper machine clothing
DE4232319A1 (en) * 1992-09-26 1994-03-31 Franz F Kufferath Multi-layer press screen for wet pressing of a paper machine
GB9713309D0 (en) * 1996-11-08 1997-08-27 Scapa Group Plc Papermachine clothing
US6592636B1 (en) * 2000-11-28 2003-07-15 Albany International Corp. Flow control within a press fabric using batt fiber fusion methods
US7297233B2 (en) 2004-01-30 2007-11-20 Voith Paper Patent Gmbh Dewatering apparatus in a paper machine

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4482601A (en) * 1983-05-31 1984-11-13 Albany International Corp. Wet press papermakers felt and method of fabrication
US4500588A (en) * 1982-10-08 1985-02-19 Tamfelt Oy Ab Conveyor felt for paper making and a method of manufacturing such a felt
US4529643A (en) * 1982-10-08 1985-07-16 Tamfelt Oy Ab Press felt for paper making and a method of manufacturing such a felt
US4657806A (en) * 1985-03-25 1987-04-14 Albany International Corp. Wet press papermakers felt

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Publication number Priority date Publication date Assignee Title
US1651476A (en) * 1925-12-17 1927-12-06 William E Sheehan Web carrier for paper-making machines
US3214327A (en) * 1963-04-16 1965-10-26 Huyck Corp Papermakers' felts and method for dewatering paper and similar webs
GB1455843A (en) * 1973-01-31 1976-11-17 Scapa Porritt Ltd Paper makers wet felts
US4283454A (en) * 1980-02-08 1981-08-11 Porritts & Spencer Inc. Papermakers wet felt with ribbed and smooth surface textures
FR2482147A1 (en) * 1980-04-16 1981-11-13 Binet Et Cie Ets Louis WET FELT FOR STATIONERY
JPS5887392A (en) * 1981-10-08 1983-05-25 日本フエルト株式会社 Papermaking felt and production thereof
US4414263A (en) * 1982-07-09 1983-11-08 Atlanta Felt Company, Inc. Press felt
FI77907C (en) * 1985-08-23 1989-05-10 Tamfelt Oy Ab PRESSFILT.
US4781967A (en) * 1987-10-07 1988-11-01 The Draper Felt Company, Inc. Papermaker press felt

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4500588A (en) * 1982-10-08 1985-02-19 Tamfelt Oy Ab Conveyor felt for paper making and a method of manufacturing such a felt
US4529643A (en) * 1982-10-08 1985-07-16 Tamfelt Oy Ab Press felt for paper making and a method of manufacturing such a felt
US4482601A (en) * 1983-05-31 1984-11-13 Albany International Corp. Wet press papermakers felt and method of fabrication
US4657806A (en) * 1985-03-25 1987-04-14 Albany International Corp. Wet press papermakers felt

Also Published As

Publication number Publication date
ES2058943T3 (en) 1994-11-01
EP0440076A3 (en) 1991-10-16
EP0440076A2 (en) 1991-08-07
FI910402A (en) 1991-08-01
DE4002761C2 (en) 1991-11-28
FI93239B (en) 1994-11-30
FI93239C (en) 1995-03-10
ATE107980T1 (en) 1994-07-15
FI910402A0 (en) 1991-01-28
DE59102041D1 (en) 1994-08-04
CA2034956C (en) 2001-08-21
CA2034956A1 (en) 1991-08-01
DK0440076T3 (en) 1994-10-31
DE4002761A1 (en) 1991-08-01

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