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
  • D21F7/10—Seams thereof
• • 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 covering, in particular a seam felt for use in a press section of a machine for producing a fiber web according to the preamble of claim 1, and a method for using such a covering according to the preamble of claim 8.
• seam felts are made with a pintle wire seam that connects the felt ends in the area of their base fabric.
• a fleece layer is applied and needled to this base fabric, which is made endless in this way, at least on the paper side - often also on the running side. Since this is advantageous in terms of production technology, the fleece layer is also needled over the pintle wire seam.
• the seam of the felt must be opened again. This can easily be done with the base fabric by removing the extension wire. However, the fleece layers needled over the seam must be separated.
• the paper-side fleece layer of one felt end is separated from the paper-side fleece layer of the other felt end by a cut in the area of the pintle wire.
• the cut is made over the seam in the fleece, which is still closed at this point in time.
• This cut can be carried out vertically, but it is preferably carried out at a slight angle, ie preferably with a deviation of 5-30 ° from the perpendicular.
• the pintle wire seam is closed again with a pintle wire, for example in the form of a fiber bundle.
• the fleece layers of the two felt ends touch or overlap, but the properties of the felt in this seam area, for example its porosity, differ from those of the rest of the felt.
• WO 02/35000 A1 proposes the introduction of a strip of flow-hindering material into the seam region of the covering.
• EP 1 918 453 A1 and WO 2015/024718 describe the introduction of liquid material or small particles into the seam region. All these optimizations of the seam region serve to change the flow properties of this region, but they do not remedy the fundamental deficiency that the fleece layer is permanently weakened at this point by the cut.
• the fiber anchoring in the seam area is less than in the remaining area of the felt surface. Due to the generally unfavorable geometry of the felt seam for fiber anchoring due to the seam loops, and the fact that the seam loops have to be kept largely free of fiber material in order to be able to insert the pintle wire, improvements in the fiber anchoring are possible, but these possibilities are limited
• the cut is prone to damage, as there is no fiber anchoring to the fibers on the other side of the fleece overlay directly in the cut area.
• the felt wears more in the seam area and a damaged seam area is often the reason for markings in the paper or for paper tears during paper production. So the cut is a reason for shorter felt running times, although the felt outside the seam would still be good enough to continue to be used for several days.
• the object is achieved by a covering, in particular a seam felt for use in a press section of a machine for producing a fiber web, the covering having at least one basic structure and at least one staple fiber layer arranged on the basic structure, which at least one staple fiber layer is arranged on a side facing the fiber web and / or on a side facing the machine, the covering having at least one seam zone , in which
• Seam loops are connected to one another by at least one pintle wire for making the covering endless, and wherein the at least one staple fiber layer is divided in the region of the seam zone by at least one cut to form a seam flap and a seam wedge. According to the invention it is provided that between the seam flap and the seam wedge at least one
• Connecting element is inserted, wherein the at least one connecting element is materially connected, in particular welded, to staple fibers of the seam flap and / or the seam wedge.
• the at least one staple fiber layer is customary on a side facing the fiber web; Staple fibers on the running side facing the machine can additionally also be provided.
• connection of the at least one connecting element to the staple fibers of the seam flap and / or the seam wedge can be carried out by means of NIR transmission welding.
• the at least one connecting element comprises or consists of a polymer material that emits light with a wavelength in the NIR range from 780 [nm] to 3 [pm], preferably between 780 [nm] and 1300 [nm] - at least largely absorbed.
• the polymer material does not necessarily cover the entire NIR range between 780 nm and 1300 nm (or 3000 nm) must be absorbent. It is completely sufficient if the polymer material is at least largely absorbent in one or more partial areas in this NIR range. A light with a wavelength from this partial range can then be used for welding.
• the staple fibers of the fleece layer are in most cases made of a polyamide that is largely transparent to light from this wavelength range.
• the seam zone with the at least one connecting element can thus be irradiated with the light of the corresponding wavelength under a certain joint pressure.
• a laser or another suitable source can be used as the light source.
• the connecting element absorbs the light, is thereby heated and completely or partially melted, so that a material connection is formed between the connecting element and the staple fibers in contact with it.
• the staple fibers are essentially only heated through contact with the connecting element.
• the staple fibers of the fleece layer remain almost unchanged through the joining process. Therefore, the joining process does not result in any noticeable changes in the permeability or porosity of the seam region.
• This positive property results automatically with transmission welding, while with a connection that is also possible, e.g. by gluing or ultrasonic welding, the joining process must be controlled very precisely.
• the absorption properties of the connecting element can be realized, for example, by adding an absorber additive to the connecting element.
• Soot carbon black
• absorbers with other colors and even transparent absorbers are commercially available, for example from Clearweld (www.clearweld.com).
• the additives can either be added to the polymer mass or they can be used as a coating on the connecting element.
• absorber additives it is possible to manufacture connecting elements from the same polymer material that the staple fibers of the fleece layer are made of - usually a polyamide, and still use the advantageous technology of NIR transmission welding. Because the materials are the same, the welded joints are particularly good and durable.
• the at least one connecting element is materially connected to both the staple fibers of the seam flap and the seam wedge.
• the two cut edges are firmly connected to one another, which improves the fiber anchoring and makes the seam more wear-resistant.
• a stretching of the fleece layer under tensile load is also prevented, which also reduces the tendency of the seam to mark.
• Attempts by the applicant to improve the seam have surprisingly shown that the use of connecting elements delivers significantly better results than is possible with a simple connection, e.g. welding the two cut edges together.
• a connecting element inserted into the seam serves as a bridge between the contact points of the two edges.
• the probability that each of the two edges will have a number of contact points with the connecting element and that a fixed joint will thus be created is significantly higher than without the use of a connecting element.
• a method for using a covering according to the invention can consist in first pulling the covering into a press section of a machine for producing a fiber web, and then making this endless by closing the pintle wire seam. This is where the process ends with known seam coverings. With a covering as proposed here, it is possible to subsequently connect the at least one connecting element to staple fibers of the seam flap and / or the seam wedge, in particular to weld it.
• Such a method can be carried out in different variants.
• the at least one connecting element is inserted between the seam flap and the seam wedge only after the covering has been drawn into the machine, in particular after being made endless by means of pintle wire, and is then connected in a materially bonded manner.
• the at least one connecting element can be provisionally connected to the seam wedge or the seam flap before being drawn into the machine.
• Provisional here means that in this embodiment the connecting element has a connection with a seam flap or wedge before it is pulled in. However, this connection is not yet the later cohesive one Connection.
• Such provisional connections can be, for example, form-fitting connections (such as light needling or spot sewing), or an adhesive connection, in particular by means of a water-soluble adhesive, which can be washed out again during later operation of the machine. This has the advantage that the connecting element (s) are placed in the right place, since the personnel who pull the coverings usually do not have the knowledge and technical skills required for this.
• the at least one connecting element can already be materially connected to the seam wedge or the seam flap before being drawn into the machine.
• This permanent joint connection means that slipping of the connecting element when it is pulled in can be almost completely ruled out.
• this method requires two joining processes - for example welding processes, which can have negative effects.
• the advantage or the disadvantage may outweigh the above.
• the at least one connecting element is designed as a thread-like or band-like connecting element.
• a connecting element should be called thread-like in which the thickness and width are similar, while the linear expansion is significantly greater.
• the connecting element can in particular be designed as a monofilament, multifilament bundle or as a twisted thread.
• a connecting element In the form of a band, a connecting element should be called in which the width is significantly greater than the thickness and the length expansion is once again significantly greater than the width.
• the at least one connecting element can be designed in particular as a textile band, fleece, film or foam.
• a textile tape can be, for example, a woven fabric, a knitted fabric or a knitted fabric.
• a fleece can, for example, be a so-called melt-blown fleece or meltblown fleece.
• the thread-like or band-like connecting element can preferably have a length of 10 mm or more, in particular more than 20 mm, in the longitudinal direction. A greater length of the connecting element improves the above-described bridging effect of the connecting element.
• one or more connecting elements are distributed essentially over the entire length of the cut (in the CD direction).
• connecting elements can be identical. Alternatively, it is also conceivable that different types of connecting elements are inserted into the cut.
• a thread-like or band-like connecting element extends over at least half the width, preferably the entire width of the clothing in the cross machine direction.
• the longitudinal direction or length direction of the connecting element in this case extends essentially along the cut and thus in the transverse direction (CD) of the covering. Since modern coverings can have a width of 10 m or more, in this case the length of the thread-like or band-like connecting elements is significantly more than the 10 mm or 20 mm described above.
• the length of the connecting elements is then more in the range of several meters (e.g. greater than 2m, or even greater than 5m).
• connecting elements can also be provided, which are designed, for example, in the form of staple fibers which are introduced into the cut.
• These fibers can advantageously be designed in such a way that they at least largely absorb light with a wavelength in the NIR range from 780 [nm] to 3 [pm].
• these fibers can be designed so that they absorb light with a wavelength in the NIR range from 780 [nm] to 1300 [pm] at least for the most part, since in the range above 1300 [nm] the risk increases that materials of the staple fibers or the basic structure absorb this light to a certain extent, which is not desirable in some cases.
• FIG. 1 shows a section of a covering according to an aspect of the invention.
• FIG. 2 shows a section of a covering according to a further aspect of the invention
• FIG. 3 shows a section of a covering according to a further aspect of the invention
• FIG. 4 shows a section of a covering according to a further aspect of the invention
• FIG. 1 shows a section from a covering 1 according to one aspect of the invention.
• a seam zone 2 is also shown here.
• the covering comprises a basic structure 3, which is designed as a basic fabric 3.
• the respective ends of the basic structure each have a seam loop 4.
• Such seam loops 4 can be formed, for example, by folding the basic structure 3 and laying it on top of one another.
• the seam loops 4 are formed by the longitudinal yarns (MD yarns) 6 of the base fabric 3.
• individual transverse threads (CD yarns) of the base fabric can also be removed.
• the covering 1 is made endless in that the two seam loops 4 are interlaced with one another and connected by inserting a pintle wire 5.
• the extension wire 5 can be a single filament.
• the covering 1 in FIG. 1 shows an extension wire 5 which is formed from a plurality of filaments.
• the person skilled in the art is completely free to choose the suitable pintle wire 5. The advantages of the present invention can be achieved independently of the choice of the pintle wire 5.
• the covering 1 also comprises two staple fiber layers 8, 8b.
• the staple fiber layer 8b on the running side can optionally also be dispensed with.
• the staple fiber layer 8 on the paper side is applied continuously to the basic structure 3, in particular needled.
• the staple fiber layer 8 was opened by a cut 9 above the seam.
• This section 9 can in principle be made perpendicular. Usually, however, as shown in FIG. 1, the section 9 will be inclined, that is to say at a certain angle to the vertical. This angle is advantageously between 5 ° and 30 °.
• a seam flap 10 and a seam wedge 11 are formed. The seam flap 10 overlaps the seam wedge 11 in the closed covering 1.
• connecting elements 20 are now inserted by way of example in the embodiment according to FIG.
• These connecting elements 20 are each designed as a thread which extends over the entire transverse direction of the covering 1 or the cut 9.
• threads 20 for example, monofilaments, Multifilament bundles or twists can be used. It is also possible to use more or less than the three threads 20 shown.
• the connecting elements 20 can be evenly distributed over the height of the cut 9.
• a non-uniform distribution can also be advantageous, for example such that in the vicinity of the basic structure 3 more
• Connecting elements 20 are arranged than in the direction of the paper side, or vice versa. If several connecting elements 20 are used, all of these connecting elements 20 can be identical. Alternatively, it is also conceivable that different types of connecting elements 20 are inserted into the section 9.
• threads 20 are materially connected both to the seam flap 10 and to the seam wedge 11.
• This material connection can be, for example, a welded connection.
• the connecting elements 20 - in this case the threads 20 - consist of a polymer which light is at least largely absorbed in a suitable NIR wavelength range from 780 [nm] to 1300 [nm].
• the material from which, for example, press felts are built up in the seam area (usually PA6 or PA66) is largely transparent in this wavelength range.
• the welded connection can therefore be produced very easily by means of NIR transmission welding.
• connecting element 20 As for the staple fibers 8, which only has the advantageous absorption property due to added absorber additives.
• connecting element 20 and staple fibers 8 enables particularly durable welded connections to be achieved.
• suitable thermoplastics for example copolyamides, PEBA or thermoplastic polyurethanes, can also be used for the connecting elements 20, which have good compatibility with the material of the staple fiber layer 8, 8b.
• the staple fiber layer 8b on the running side has a larger gap in the seam region 2. This makes it easier, for example, to insert the pintle wire 5 and then only minimally affects the quality of the paper produced, if at all.
• the staple fiber layer 8b is treated in the same way on this side as on the paper side. This means that the staple fiber layer 8b can also be connected on the running side by inserting connecting elements 20 above the seam.
• the covering 1 shown in FIG. 2 differs from the embodiment from FIG. 1 only in the choice of the connecting element 20.
• a single, band-shaped connecting element 20 is provided.
• the band-shaped connecting element 20 can be, for example, a fleece, a foam, a film or also a fabric band, which in particular can again extend over the entire width of the felt 1 or the cut 9.
• strip-shaped connecting elements 20 in particular in the case of foils 20, it is advisable to choose very thin foils which do not influence the permeability of the seam zone 20 or only influence them very slightly.
• a film can, for example, be cut so that its length corresponds to the width of the felt and its width to the height of the cut 9.
• the drainage in the depth direction of the felt 1 is hardly influenced by the small film thickness, but the anchoring of the fleece is improved by the film.
• permeable or perforated films are advantageous.
• Foils or films can be unoriented or oriented monoaxially or biaxially. It can also be provided that a completely or largely foil or a film is inserted into the cut 9, and the permeability of this foil only arises when the closed foil structure is dissolved by the welding process (eg by melting).
• a covering 1 is shown in which the connecting element 20 is implemented by flocking the seam wedge 11. Alternatively or additionally, the seam flap 10 can also be flocked.
• the flock fibers 20 are included advantageously designed to be absorbent in the NIR wavelength range.
• the flocking creates a connection between the connecting element and the seam wedge 11. However, this connection is usually provisional. If the section 9, which is still shown as open in FIG. 3, is closed - possibly with the application of a joining pressure, the material connection with the seam wedge 11 and / or the seam flap 10 can be realized by a welding process - preferably by transmission welding.
• FIG. 4 shows an embodiment in which staple fibers absorbing in the NIR wavelength range have been introduced as connecting element 20 into the staple fiber layer 8 in the region of the cut 9.
• the material connection can be made again by welding.
• the absorbent staple fibers can either be introduced when the fleece layer 8 is in the fiering position. Alternatively, they can also be added to the seam wedge 11 and / or the seam flap 10 subsequently, that is to say after the cut 9 has been produced.
• These absorbent staple fibers can advantageously be distributed in the seam flap 10 and / or the seam wedge 11 over the entire width of the covering 1 and an area of 1 mm to 20 mm, in particular 2 mm to 10 mm, in the longitudinal direction thereof.
• Absorbent fibers can also be provided in a larger area of the staple fiber layer 8, 8b. In particular, it can also be provided that absorbent fibers are distributed over the entire staple fiber layer 8, specifically the entire staple fiber layer on the paper side.

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• Nonwoven Fabrics (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2019
  • 2019-12-18 DE DE102019134837.4A patent/DE102019134837A1/de active Pending
• 2020
  • 2020-11-11 US US17/783,842 patent/US20230013706A1/en active Pending
  • 2020-11-11 JP JP2022537835A patent/JP2023506575A/ja active Pending
  • 2020-11-11 WO PCT/EP2020/081780 patent/WO2021121789A1/de unknown
  • 2020-11-11 CN CN202080088212.3A patent/CN114867910A/zh active Pending
  • 2020-11-11 EP EP20806986.4A patent/EP4077802A1/de active Pending

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