EP3587664A1 - Fabric for paper machines or cellulose dewatering machines, use of the same and use of monofilaments comprising or consisting of a partially aromatic polyamide for producing fabrics for paper machines or cellulose dewatering machines - Google Patents

Abstract

The present invention relates to a covering (1, 12, 23, 41, 56) for paper or pulp dewatering machines, comprising or consisting of monofilaments (8, 10, 11, 16, 19, 27-30, 37-40, 42, 44 -47, 59, 61, 62) with or from a partially aromatic polyamide.

Description

The invention relates to a covering for paper machines or pulp dewatering machines and the use of such.

Large paper machines usually consist of three so-called lots, namely a forming section, a press section and a dryer section when viewed in the direction of the paper web. The forming section is used to form the paper web from the paper pulp and a first mechanical dewatering of the paper web thus formed. In the press section, the paper web is passed between press rollers, in which it is exposed to high pressures and is thereby further mechanically dewatered. The paper web is then fed to the dryer section, in which the paper web is guided over heated drying cylinders, as a result of which the paper web is thermally dewatered.

The paper web is guided through the paper machine by means of belts which are adapted to the requirements of the respective lot and against which the paper web lies and which also serve to transfer the paper web from one lot to the next.

So-called forming fabrics are used in the forming section. Examples of such and their guidance through a paper machine go from the EP 2 067 895 B1 and the state of the art discussed therein. Press felts are used in the press section, for which examples the EP 1 452 639 B1 can be removed. So-called dryer fabrics are used in the dryer section, which are designed in particular as dry fabrics consisting of warp and weft threads. Examples of such dryer fabrics and for guiding the dryer fabrics through the dryer section of a paper machine can be the EP 1 002 155 B1 . EP 1 507 041 B1 . EP 1 558 807 B1 . EP 1 857 588 A1 and EP 1 054 097 B1 be removed.

Furthermore, in order to guide the paper web in the areas in which there is no support, in particular through the press felt, which applies above all to the transition area to the dryer section, so-called transfer belts can be used, which transfer the paper web through one or more presses pass the press section together with the associated press felt and, after detaching the press felt, guide it from the paper web to a point where the paper web is usually detached from the transfer belt with the aid of a suction roller and taken over by a dryer fabric circulating in the dryer section. Examples of the guidance of transfer belts in the press section of a paper machine are, in particular Figures 1 to 3 the EP 0 576 115 A1 refer to.

It is known that threads made of polyamide are used in paper machine clothing. From the EP 2 096 206 B1 and the EP 2 206 828 B1 For example, there is a transfer belt for paper machines, which has a carrier fabric with weft threads made from aromatic polyamide. This material is distinguished by a comparatively low degree of water absorption, as a result of which an increase in the expansion of the tape in the width direction can be reduced on account of the high water absorption of a paper-side nonwoven fabric made of hydrophilic fibers. The US 2006/0275604 A1 discloses a paper machine felt with yarns, fibers or filaments that have polyamide and / or polyester in their polymer matrix, thereby ensuring a comparatively high abrasion resistance.

The fabrics for known paper machines have proven themselves in principle. However, there is still a need for clothing for paper machines or pulp dewatering machines, which are characterized in particular by improved mechanical and thermal properties compared to the prior art. It is therefore an object of the present invention to provide a covering for paper machines or pulp dewatering machines that meets these requirements.

This object is achieved by a covering for paper or pulp dewatering machines, comprising or consisting of monofilaments comprising or consisting of a partially aromatic polyamide.

The applicant has found that partially aromatic polyamide can be used to obtain monofilaments, the use of which in fabrics for paper or pulp dewatering machines leads to a combination of excellent product properties.

It is particularly preferably provided that at least some of the monofilaments of the covering according to the invention consist of or comprise a partially aromatic copolyamide, which has proven to be very particularly suitable. Alternatively or additionally, it can be provided that at least some of the monofilaments of the covering according to the invention consist of or comprise a partially aromatic homo-polyamide. Of course, it is also possible that at least part of the Monofilaments consists of a combination of partially aromatic homo- and partially aromatic copolyamide or comprises such a combination.

A partially aromatic copolyamide is one which has both aromatic and aliphatic components, as is the case for PA6T / 6, for example, which comes from the range offered by the manufacturer BASF under the brand name Ultramid® T. In particular, due to the presence of both components, the material is easier to process than is the case for aromatic polyamides which contain only aromatic components. According to the applicant's knowledge, monofilaments can be spun from partially aromatic copolyamide, which are characterized in particular by low water absorption, high dimensional stability, high thermal and mechanical strength, high abrasion resistance and good processability, and to optimize their use in fabrics of the type mentioned Results with comparable moderate costs. The fabrics according to the invention are distinguished on the one hand by a slight (water-related) change in shape, since the monofilaments made from partially aromatic copolyamide absorb water only to a comparatively small and significantly slower extent and thus have a shape-stabilizing effect. Furthermore, using these monofilaments, due to the high mechanical stability, there is only a slight flattening at offset points of the fabric. As a result, a problem known to the applicant in the case of coverings of a conventional type, especially sieving with monofilaments made of PET-TPU and in particular on the machine side, is reliably avoided. Furthermore, it has been shown that the monofilaments made from partially aromatic copolyamide are characterized by a particularly good positioning relative to the other threads in the fabric in a covering. They also have a high load capacity compared to cleaning units, such as high-pressure spray pipes, and excellent chemical resistance. It continues to be a particularly low one Abrasion is guaranteed, which offers a considerable advantage, particularly on the machine side, of a covering.

Due to the combination of the mentioned advantageous properties and a significantly improved hydrolysis stability compared to polyethylene terephthalate (PET), monofilaments made from partially aromatic copolyamide can also be an excellent alternative to filaments made from PET and, above all, a significantly cheaper alternative to threads made from polyphenylene sulfide (PPS) in particular form in dryer fabrics. PPS is used as an alternative to PET in dryer fabrics if the conditions of use can lead to polymer degradation of the PET by hydrolysis, while PPS is not damaged under these conditions.

Further advantageous properties of partially aromatic copolyamide are a comparatively high glass transition temperature, a comparatively high melting point, in particular of about 295 ° C., constant mechanical properties, high strength and rigidity, very good toughness, good spring properties.

The monofilaments which can be used in the context of the present invention can, for example, consist of a material or comprise such a material as is shown in FIG EP 2 860 220 A1 or in the EP 2 857 456 A1 is disclosed, the content of which is hereby incorporated by reference. These documents show, in particular, an impact-modified polyamide molding compound made from partially aromatic copolyamide, for example PA6T / 6, and an olefinic copolymer for adjusting the impact strength, which can be used to obtain the covering according to the invention.

The production of monofilaments from partially aromatic polyamide can, in particular, as already generally known for thermoplastics, take place by extrusion.

In particular, it is provided that plastic threads made of partially aromatic polyamide, in particular copolyamide, formed as monofilaments form part of a covering for a paper machine or cellulose dewatering machine.

It should be noted that copolyamide of known dimensions is a co-polymer (also known as a heteropolymer), that is to say a polymer which is composed of two or more monomers. The counterpart to copolymers are also known dimensions, homopolymers, which are polymers which are composed of only one type of monomer. Partially aromatic homo-polyamides such as polyphthalamide PA6T (T stands for terephthalic acid = aromatic dicarboxylic acid) are therefore not among the partially aromatic copolyamides. The same naturally applies to the aliphatic homo-polyamides, such as polyamide 6 (PA6), polyamide 6.6 (PA6.6) or polyamide 6.10 (PA6.10), and the aromatic homo-polyamides, such as polyaramide poly (m-phenylene isophthalamide), which likewise do not fall into the group of partially aromatic copolyamides.

As far as the proportion of partially aromatic polyamide, especially co-polyamide in a fabric according to the invention is concerned, it is possible, on the one hand, that only a part of all the threads of a fabric is given by monofilaments made of or with partially aromatic polyamide, in particular co-polyamide, that is to say in combination with There are threads of a different kind.

A covering has in particular longitudinal threads extending in a running direction and transverse threads extending transversely thereto, which then some or all of them can be given by monofilaments made of or with partially aromatic polyamide, in particular partially aromatic copolyamide. At least part of the transverse threads is preferably given by monofilaments made of such a material, for example PA6T / 6. Depending on the application, the longitudinal threads, which are primarily the force-absorbing threads, can be made of polyester, as is known from conventional coverings, which is characterized by an even higher tensile strength. Of course, however, these can also consist at least in part of partially aromatic polyamide, in particular copolyamide.

Of course, it is also possible that all threads of a covering are formed by these monofilaments. This can be particularly advantageous, in particular, in the event that the covering according to the invention is designed as a press felt or also a dryer fabric and is used.

Furthermore, it can be provided that the covering according to the invention has only one fabric layer or also a plurality of fabric layers. If several layers are present, only one of the layers can have monofilaments with or made from partially aromatic polyamide, in particular copolyamide, or this applies to several, if necessary all, layers of the covering, the individual layer (s) again only partially or can be formed entirely from monofilaments of this material. Is z. If, for example, a machine-side fabric layer is provided, it is preferred that at least the machine-side fabric layer comprises or consists of monofilaments with or made from a partially aromatic polyamide, in particular copolyamide. Then a particularly high abrasion resistance is ensured, especially on the particularly stressed machine side.

If the machine-side fabric layer has longitudinal threads extending in a running direction and transverse threads extending transversely to the longitudinal threads, it is preferably provided that at least some of the cross-threads of the machine-side fabric layer are monofilaments made from a partially aromatic polyamide, in particular copolyamide.

The covering according to the invention can be designed, for example, as a forming fabric or a drying fabric and can be used in this function in particular in a paper machine. It is also possible that the covering according to the invention is designed as a press felt or transfer belt and is used accordingly. It should be noted that the structure of the fabric according to the invention is identical to that of a corresponding type of fabric known from the prior art, and the only difference may be that at least part of the fabric is covered by monofilaments with or made from partially aromatic polyamide, in particular Co Polyamide is formed.

The partially aromatic copolyamide used in particular is preferably one which is characterized by a base of hexamethylenediamine and terephthalic acid and caprolactam. The PA6T / 6 already mentioned is particularly preferably used.

Another object of the invention is the use of a fabric according to the invention in a paper machine or pulp dewatering machine.

Finally, the invention preferably relates to the use of monofilaments with or made from partially aromatic polyamide, in particular copolyamide PA6T / 6, for the production of fabrics for paper machines or cellulose dewatering machines.

• Figur 1 in einem Querschnitt - also quer zur vorgesehenen Laufrichtung - einen Ausschnitt einer ersten Ausführungsform einer erfindungsgemäßen, als Formiersieb ausgebildeten Bespannung,
• Figur 2 in einem Querschnitt einen Ausschnitt einer zweiten Ausführungsform einer erfindungsgemäßen, ebenfalls als Formiersieb ausgebildeten Bespannung,
• Figur 3 einen Längsschnitt durch eine dritte Ausführungsform einer erfindungsgemäßen, als Nasspressfilz ausgebildeten Bespannung,
• Figur 4 einen Querschnitt durch die Bespannung aus Figur 3 in vergrößerter Darstellung,
• Figur 5 eine Draufsicht auf den Endabschnitt einer vierten Ausführungsform einer erfindungsgemäßen, als Trockensieb ausgebildeten Bespannung,
• Figur 6 einen Längsschnitt durch den Ausschnitt gemäß Figur 5,
• Figur 7 eine Draufsicht auf einen Ausschnitt des Basisgewebes einer fünften Ausführungsform einer erfindungsgemäßen Bespannung, die als Bespannung zur Entwässerung einer Papierbahn oder von Zellstoff ausgebildet ist,
• Figur 8 eine Draufsicht auf einen Ausschnitt eines Basisgewebes einer sechsten Ausführungsform einer erfindungsgemäßen Bespannung, die ebenfalls als Bespannung zur Entwässerung einer Papierbahn oder von Zellstoff ausgebildet ist, und
• Figur 9 einen Ausschnitt aus der Polymerkette eines teilaromatischen Co-Polyamids PA6T/6.

In the drawing, the invention is illustrated in more detail using several exemplary embodiments. It shows

• Figure 1 in a cross-section - that is to say transversely to the intended running direction - a section of a first embodiment of a covering according to the invention, designed as a forming screen
• Figure 2 in a cross section a section of a second embodiment of a fabric according to the invention, also designed as a forming fabric,
• Figure 3 2 shows a longitudinal section through a third embodiment of a covering according to the invention, designed as a wet press felt,
• Figure 4 a cross section through the covering Figure 3 in an enlarged view,
• Figure 5 2 shows a plan view of the end section of a fourth embodiment of a covering according to the invention, designed as a dryer fabric,
• Figure 6 a longitudinal section through the cutout Figure 5 .
• Figure 7 2 shows a plan view of a section of the base fabric of a fifth embodiment of a covering according to the invention, which is designed as a covering for dewatering a paper web or cellulose,
• Figure 8 a plan view of a section of a base fabric of a sixth embodiment of a covering according to the invention, which is also designed as a covering for dewatering a paper web or cellulose, and
• Figure 9 a section of the polymer chain of a partially aromatic co-polyamide PA6T / 6.

The Figure 1 shows in a cross section - that is transverse to the intended direction of travel - a section of a first embodiment of a fabric according to the invention in a schematic representation, which is given specifically by a forming wire 1 for use in the forming area of a paper machine. The forming fabric 1 is a double-layer fabric with an upper, paper-side fabric layer 2 and a lower, machine-side fabric layer 3. Both fabric layers 2, 3 comprise longitudinal or warp threads - which are exemplified in the figure with 4 and 5, respectively - In the thread count ratio of 1: 1, wherein a longitudinal thread 4 of the paper-side fabric layer 2 is arranged exactly above a longitudinal thread 5 in the machine-side fabric layer 3. The longitudinal threads 4, 5 thus lie one above the other in pairs.

The diameter of the longitudinal threads 4 in the paper layer 2 is 0.11 mm and the diameter of the longitudinal threads 5 in the machine layer 3 is 0.18 mm. They consist of polyethylene terephthalate (PET). The number of longitudinal threads is 58 per cm in the transverse direction.

In the paper-side fabric layer 2, paper-side transverse or weft threads 6, 7 are integrated with the longitudinal threads 4 to form a plain weave. At right angles to the plane of the drawing, adjacent to each other paper-side transverse threads 6, 7 on top of each other. The cross threads 6, 7 on the paper side are made of polyethylene terephthalate (PET) and they have a diameter of 0.11 mm.

Machine-side transverse threads 8 are integrated exclusively into the machine-side longitudinal threads 5, of which only one can be seen in the figure. The machine-side transverse threads 8 each form floats going over five longitudinal threads 5 - designated by way of example with 9 - on the machine side of the forming fabric 1 and then bind each with a single machine-side longitudinal thread 5. The machine-side floats 9 represent abrasion material to protect the machine-side longitudinal threads 5, which are subject to high tensile stress. The diameter of the machine-side transverse threads 8 is 0.22 mm. According to the present invention, the machine-side transverse threads 8 are given by monofilaments made from partially aromatic copolyamide, specifically PA6T / 6. A section of the polymer chain of PA6T / 6 can be Figure 9 be removed. It should be emphasized that the proportions and the order shown therein can vary.

The fabric layers 2, 3 are connected by pairs of two binding transverse threads 10, 11 each lying side by side in the longitudinal direction. They have a diameter of 0.11 mm and are made of PET. They bind in the paper-side fabric layer 2 one after the other alternately on the top and bottom with paper-side longitudinal threads 4, then run between the two fabric layers 2, 3 over three longitudinal threads 4 and 5 and then bind with a single longitudinal thread 5 in the machine-side fabric layer 3, before floating again between the two fabric layers 2 and 3. The paired binding transverse threads 10 and 11 each have the same weave repeat, but are shifted relative to one another in the transverse direction - ie in their longitudinal direction - in such a way that the weave patterns in the paper-side fabric layer 2 complement one another so that they together form a canvas pattern there form analogously to the paper-side transverse threads 6, 7. In this way, an almost uniform canvas pattern is created on the paper side of the forming wire 1, which provides a high fiber retention.

The longitudinal thread filling degree of the paper-side fabric layer 2 is 31%, the total filling degree of paper-side and machine-side longitudinal threads 4, 5 82%. The number of cross threads is 108 per cm in the longitudinal direction of the forming fabric 1. This creates a high degree of openness and thus a good drainage effect despite high fiber retention.

In terms of its structure, the forming fabric 1 corresponds to that which in the single figure also goes back to the applicant EP 2 067 895 B1 is shown and its advantages are explained in more detail therein.

According to the present invention, the in Figure 1 Forming sieve 1 shown, as already noted above, but the machine-side transverse threads 8 are given by monofilaments made from partially aromatic copolyamide, specifically PA6T / 6. This gives us a forming fabric 1, which offers several advantages. In particular, due to the low water absorption of the monofilaments of this type, it is characterized by a slight change in shape, due to the high mechanical stability there is at most a slight flattening at offset points, and the monofilaments are well positioned relative to the remaining threads in the fabric (" Stacking "), there is a high load-bearing capacity compared to cleaning units such as high-pressure spray pipes and there is a particularly high abrasion resistance of the monofilaments, so there is at most little abrasion on the roll side. Due to the high dimensional stability, the disadvantageous occurrence of "edge curling" is completely avoided or at least greatly reduced.

The Figure 2 shows in a cross section a section of a second embodiment of a fabric according to the invention, which is also designed as a forming screen 12 for a paper machine and the structure of which in Figure 1 who also goes back to the applicant EP 2 899 311 B1 forming fabric shown is the same.

The forming fabric 12 Figure 2 is also multi-layer, specifically comprises a paper layer and a machine-side fabric layer 13, 14.

The paper-side fabric layer 13 has paper-side longitudinal threads - in the Figure 2 designated 15 by way of example - which extend in the running direction of the screen 12, as well as transverse transverse threads 16, 17 oriented to the paper, both of which have a round cross section. The paper-side transverse threads comprise transverse binding threads 16 and transverse threads 17 which do not form any transverse binding threads. These two types of threads 16, 17 alternate in the direction of the paper-side longitudinal threads 15. The paper-side transverse threads 16, 17 are in principle woven in a plain weave.

The machine-side fabric layer 14 consists of machine-side longitudinal threads - designated 18 by way of example - and machine-side transverse threads 19, of which in the Figure 2 only one is recognizable. The machine-side transverse threads 19 run in such a way that they form floats 20 on the machine side, which each run under five adjacent longitudinal threads 18 on the machine side. Between the floats 20, the machine-side transverse threads 19 bind a machine-side longitudinal thread 18 in a crank 21. Both the machine-side transverse threads 19 and the machine-side longitudinal threads 18 each have a circular cross section. The ratio of the paper-side longitudinal threads 15 and the machine-side longitudinal threads 18 is again 1: 1.

At the binding point 22, the transverse binding thread 16 binds with a paper-side longitudinal thread 15a, by running over its paper side, then from the paper-side fabric layer 13 to the machine-side fabric layer 14 through an almost vertical course, that is to say in the thickness direction of the screen 12, and with the machine-side fabric layer 14 binds with two adjacent longitudinal threads 18a and 18b by overlapping them on the machine side. The two machine-side longitudinal threads 18a, 18b lie next to the offset 21. The transverse binding thread 16 then runs back to the paper-side fabric layer 13 and binds with a paper-side longitudinal thread 15b. The paper-side longitudinal threads 15a, 5b are separated from one another only by a paper-side longitudinal thread 15c. The Figure 2 shows only one binding point 22. The number of binding points 22 can be selected depending on the requirement of a sufficiently strong connection of the two fabric layers 13, 14. Further explanations, including the advantages of the specific structure of the forming fabric 12, can be found in the EP 2 899 311 B1 be removed.

The machine-side transverse threads 19 are - just like in the first exemplary embodiment - given by monofilaments made of partially aromatic copolyamide, specifically PA6T / 6, whereby the same advantages compared to the previously known embodiment are achieved, which already apply to the first embodiment Figure 1 have been explained.

Figure 3 shows a third embodiment of a covering according to the invention, specifically a schematically illustrated wet press felt 23, which is intended for use in the press section of a paper machine. For reasons of clarity, only the carrier 24 can be seen from the wet press felt 23. The fiber layers embedding the carrier 24 are omitted. The carrier 24 is only partially shown here. He sits in shape to the left of a lying U - in Figure 3 indicated by dashed lines - away, so that the carrier 24 overall represents a lying U. The extent of the U is adapted to the respective installation conditions in the paper machine. The structure of the wet press felt 23 is the same as that in FIGS Figures 1 and 2 who also goes back to the applicant EP 1 452 639 B1 shown wet press felt.

The carrier 24 consists of an inner carrier layer 25 and an outer carrier layer 26. Both carrier layers 25, 26 are designed as fabrics which are produced in a continuous weaving process by circular weaving. The fabrics have transverse threads - designated by way of example 27 or 28 - which formed the warp threads during the weaving process, and longitudinal threads 29, 30 as weft threads. The longitudinal threads 29, 30 are parts of a single continuous thread due to their property as weft threads. The transverse threads 27, 28 bind with the longitudinal threads 29, 30 in such a way that the two carrier layers 25, 26 have no connection to one another via the surface, i.e. the transverse threads 27 do not bind into the carrier layer 26 and the transverse threads 28 do not bind into the carrier layer 25 and the longitudinal threads 29, 30 remain in the respective carrier layer 25 or 26 over the entire length of the carrier 24.

At the front ends 31, 32 of the carrier 24, every second longitudinal thread 29, 30 forms seam loops 33, 34 which protrude beyond the ends 31, 32. This results in a plurality of seam loops 33, 34 perpendicular to the plane of the drawing (see reference numbers 17 and 19 in Figure 2 the WO 00/09802 and the reference numerals 20 and 22 in the Figures 2 to 5 the US 5,015,220 ). The longitudinal threads 29, 30, which each run between two longitudinal threads 29, 30 forming seam loops 33, 34, are led back in a short way without forming seam loops. One row of seam loops 33 is connected to the other row of seam loops 34 - as shown - have been brought into a comb-like overlap so that a push-through channel 35 is formed perpendicular to the plane of the drawing. By pushing a plug wire 36 through the push-through channel 35, the seam loops 33, 34 and thus the ends 31, 32 of the carrier 24 are coupled to one another, so that an endless carrier 24 and thus also an endless wet press felt 23 is created. The coupling takes place after the wet press felt 23 has been drawn into the press section of the paper machine.

In Figure 4 the binding transverse threads 37, 38, 39, 40 are shown reinforced in order to make their course clear compared to the course of the other transverse threads 27, 28. While the other transverse threads 27, 28 bind with the longitudinal threads 29, 30 in a plain weave each exclusively in the carrier layer 25 or the carrier layer 26, the binding transverse threads 37, 38, 39, 40 run in such a way that they alternately bind in both carrier layers 25, 26 , in each case by a longitudinal thread 29 in one carrier layer 25 and - offset by two longitudinal threads 29, 30 - by a longitudinal thread 30 in the other carrier layer 26. Through this course of the binding transverse threads 37, 38, 39, 40, the seam loops 33, 34 closed on the carrier side.

All threads 27, 28, 29, 30, 37, 38, 39, 40 of the wet press felt 23 from the Figures 3 and 4 are given by monofilaments made from partially aromatic copolyamide, specifically from PA6T / 6, whereby a wet press felt with the excellent properties already discussed above in connection with the previous exemplary embodiments is obtained. It is characterized in particular by excellent dimensional stability in both the length and width directions, high thermal resistance and high mechanical resistance, especially against pressure loads, and particularly high abrasion resistance.

In the Figures 5 and 6 A fourth embodiment of a covering according to the invention is shown, which is a dryer fabric 41.

From the top view according to Fig. 5 It can be seen that the dryer fabric 41 has broad flat transverse threads on the paper side - designated 42 by way of example - which are bound in by longitudinal thread pairs - designated 43 by way of example, each longitudinal thread pair 43 consisting of two longitudinal threads - designated 44, 45 by way of example, which run identically within a pair of longitudinal threads 43. The longitudinal thread pairs 43 bind with the flat transverse threads 42 in the manner of a plain weave, ie they bind a flat transverse thread 42 on the paper side and the subsequent flat transverse thread 42 on the machine side and then the subsequent flat transverse thread 42 again on the paper side. The incorporation of the longitudinal threads 44, 45 with the flat transverse threads 42 is even clearer Fig. 6 refer to. In this figure it can be seen that on the underside of the flat transverse threads 42 there are two round transverse threads in each case - designated by way of example with 46, 47 - and support them in pairs. A displacement of the round transverse threads 46, 47 relative to the flat transverse threads 42 is avoided by the alternate integration of the flat transverse threads 42 and the associated round transverse threads 46, 47 by means of the longitudinal thread pairs 43.

The longitudinal threads 44, 45 of the longitudinal thread pairs 43 form in the version below the dash-dotted line on the front edge 48 of the drying wire 41 large loops - designated 49 for example - and small loops - labeled 50 for example. The large loops 49 alternate with small loops 50. The version above the dash-dotted line forms only large loops 49. It goes without saying that two different types of end edges 48 are to be shown by this illustration, but that only one loop version is present for a dryer fabric. The large loops 49 form loop eyelets 51, these loops 49 being able to overlap with corresponding large loops on the other end edge of the drying wire 41 in such a way that all loop eyelets 51 are aligned and thus form a channel through which in a manner known per se Plug wire for connecting the front edges 48 can be pushed to form a so-called plug wire seam. A longitudinal thread 44 of a pair of longitudinal threads 43 is woven back after the loop formation in such a way that it forms the adjacent longitudinal thread 52 of the adjacent longitudinal thread pair 53. The same applies to the longitudinal thread 45 of the pair of longitudinal threads 43, ie the loop formation makes it the adjacent longitudinal thread 54 of the adjacent pair of longitudinal threads 55. This results in only a slight twisting of the loops 49, 50 and a very uniform product image of the dryer fabric 41 on the paper side.

According to the invention, all of the threads 42, 44, 45, 46, 47 of the drying wire 41 are from the Figures 5 and 6 by monofilaments made from partially aromatic copolyamide, specifically from PA6T / 6. As an alternative to the embodiment shown, it can also be provided that only the flat transverse threads 42 and / or the round transverse threads 46, 47 are given in the form of monofilaments made of partially aromatic copolyamide, in particular PA6T / 6, and the remaining threads consist of a different material. Since the dryer fabric 41 consists of monofilaments made of partially aromatic copolyamide, or has them, it is also distinguished by the advantages compared to the prior art, already discussed in connection with the previous embodiments, in particular by good hydrolysis stability and compared to the prior art Technology significantly higher abrasion resistance - especially compared to dryer fabrics made of PPS. The Figures 7 and 8 Finally, sections show the base fabric 56 of a fifth and a sixth embodiment of a covering according to the present invention, which are each designed as flow-through coverings for the dewatering of a paper web or of cellulose and are similar in structure to those described in FIGS Figures 1 and 2 who also goes back to the applicant DE 20 2013 104 888 U1 are shown.

That in the Figures 7 and 8 The illustrated base fabric 56 is designed as a single-layer fabric in plain weave and consists of base warp threads - denoted by example 57 - and base weft threads - denoted by example 58.

In the embodiment according to Fig. 7 are woven into the base fabric 56 a plurality of additional warp threads - designated 59 by way of example - which are arranged next to one another at equal intervals and have an identical course. They are shown filled in black. Their course is also symmetrical to axes of symmetry, which run parallel to the base warp threads 57 and to the base weft threads 58. The additional warp threads 59 move back and forth by crossing two adjacent base warp threads 57 on their upper sides, running parallel to the base weft threads 58, then tying at the point of inflection - designated 60 by way of example - with a base weft thread 58 and running there parallel to the base warp threads 57, then in In the opposite direction, cross two base warp threads 57 at the top and tie with the adjacent base weft thread 58 at the next turning point 60. This creates a rectangular meandering course of the additional warp threads 59.

In the embodiment according to Fig. 8 56 additional warp threads - for example designated 61 and 62 - are woven into the base fabric, some of them different course than the additional warp threads 59 according to Fig. 7 to have. The course is different from that of the additional warp threads 59 according to Fig. 7 more like an arch shape. The additional warp thread 61 initially runs in a section parallel to the base weft yarns 58 via a base warp yarn 57. Then there is an inclined section which runs between the adjacent base warp yarn 57 and a base weft yarn 58. At the turning point 60, a section parallel to the base warp threads 57 crosses the adjacent base weft thread 58 on its underside. Then there is again an inclined section which runs between the adjacent base weft thread 58 and a base warp thread 57, then a section which runs parallel to the base weft threads 58 via a base warp thread 57, then an inclined section which extends over a connecting point of the base warp thread 57 and base weft thread 58 runs, and a portion that then extends under the adjacent base weft 58 parallel to the base warp 57. This is followed again by a sloping section which crosses a binding point between base warp thread 57 and base weft thread 58 at the top, and then a section which runs parallel to the base weft threads 58 and thereby crosses a base warp thread 57. This is followed in turn by an inclined section which runs between a base warp thread 57 and a base weft thread 58. The additional warp thread 62, viewed in the drawing from top to bottom, first runs in a section parallel to the base weft threads 58 over a base warp thread 57. Then an inclined section follows, which runs over the adjacent base warp thread 57 and a base weft thread 58. At the turning point 60, a section parallel to the base warp threads 57 crosses the adjacent base weft thread 58 on its underside. Then there is again an inclined section which runs over the adjacent base weft thread 58 and a base warp thread 57, then a section which runs parallel to the base weft threads 58 over a base warp thread 57, then an inclined section which runs between the adjacent base weft thread 57 and base weft thread 58 , and a section which then extends under the adjacent base weft 58 parallel to the base warp threads 57. This is followed by a section that is again inclined, which runs between the base warp thread 57 and the base weft thread 58, and then a section which runs parallel to the base weft threads 58 and thereby crosses a base warp thread 57 on the upper side thereof. This is followed in turn by an inclined section which runs over a base warp thread 57 and a base weft thread 58. Because of their meandering course, the additional warp threads 61, 62 have regular arches. The adjoining additional warp threads 61, 62 form an identical thread pattern, but they can be tied in between the base weft threads 58 and the base warp threads 57 or lie on top of the base weft threads 58 and base warp threads 57 at the inclined sections which precede or follow the turning points 60.

The additional warp threads 59, 61, 62 form a structural principle that can be implemented in an extremely varied manner, so that the base fabric 56 provided with it can be flexibly adapted to the respective requirements in the individual batches of the paper machine or pulp dewatering machine in terms of a number of properties. The additional warp threads 59, 61, 62 in particular allow a kind of functional separation, in that the construction of the base fabric 56 is optimally adapted to the basic requirements such as strength and dimensional stability, while other properties such as drainage, abrasion resistance, fiber retention or the like, with the help of Additional warp threads 59, 61, 62 can be optimized.

According to the present invention, both are in the embodiment Figure 7 as well as the embodiment Figure 8 all existing additional warp threads 59, 61, 62 of the respective covering by monofilaments made of partially aromatic copolyamide, specifically given PA6T / 6, whereby the Advantages already explained above can be achieved. Above all, the high thermal and mechanical resilience represents a considerable advantage in the application area of pulp dewatering, for example, where higher temperatures can prevail than in conventional paper machines.

The above-described embodiments of coverings according to the invention are to be understood only as examples and not as restrictive. The use of monofilaments made from partially aromatic copolyamide can, of course, also be provided for clothing of a different design, the advantages which have already been discussed in detail and associated with this then also being achieved. As a purely exemplary example, reference is made to all remaining exemplary embodiments from all of the above-mentioned documents, which also go back to the applicant, for further designs of coverings.

Claims (13)

Covering (1, 12, 23, 41, 56) for paper or pulp dewatering machines, comprising or consisting of monofilaments (8, 10, 11, 16, 19, 27-30, 37-40, 42, 44-47, 59, 61, 62) with or from a partially aromatic polyamide. Covering (1, 12, 23, 41, 56) according to claim 1, characterized in that a machine-side fabric layer (3, 14, 25) is provided, and at least the machine-side fabric layer (3, 14, 25) monofilaments (8, 10 , 11, 16, 19, 27-30, 37-40, 42, 44-47, 59, 61, 62) with or consisting of a partially aromatic polyamide or consists of these. Covering (1, 12, 23, 41, 56) according to claim 1 or 2, characterized in that the covering (1, 12, 23, 41, 56) longitudinal threads (4, 5, 15, 18, extending in one running direction) 29, 30, 44, 45, 57) and transverse threads (6-8, 10, 11, 16-19, 27, 28, 37-40, 42, 46, 47, 58) extending transversely to the longitudinal threads or of this is formed, and at least some of the transverse threads (6-8, 10, 11, 16-19, 27, 28, 37-40, 42, 46, 47, 58) are monofilaments (8, 10, 11 , 16, 19, 27, 28, 37-40, 42, 46, 47, 58) with or from a partially aromatic polyamide. Covering (1, 12, 23, 41, 56) according to claim 2 and 3, characterized in that the machine-side fabric layer (3, 14, 25) extending in one direction longitudinal threads (5, 18, 29, 30) and transversely has transverse threads (8, 19, 27, 37-40) extending to the longitudinal threads, and at least some of the transverse threads of the machine-side fabric layer (3, 14, 25) are monofilaments (8, 19, 27, 37-40) deals with or from a partially aromatic polyamide. Covering (1, 12, 23, 41, 56) according to one of the preceding claims, characterized in that all threads of the covering are given by monofilaments with or made from partially aromatic polyamide. Covering (1, 12, 23, 41, 56) according to one of claims 1 to 5, characterized in that the covering (1, 12, 23, 41, 56) is designed as a forming fabric (1, 12) or dryer fabric (41) is. Covering (1, 12, 23, 41, 56) according to any one of claims 1 to 5, characterized in that the covering (1, 12, 23, 41, 56) is designed as a press felt (23), wherein the Press felt is preferably a seam felt. Covering (1, 12, 23, 41, 56) according to one of the preceding claims, characterized in that at least some of the monofilaments consist of or comprise a partially aromatic homo-polyamide. Covering (1, 12, 23, 41, 56) according to one of the preceding claims, characterized in that at least some of the monofilaments consist of or comprise a partially aromatic copolyamide. Covering (1, 12, 23, 41, 56) according to claim 9, characterized in that at least some of the monofilaments (8, 10, 11, 16, 19, 27-30, 37-40, 42, 44-47, 59, 61, 62) consists of or comprises a partially aromatic copolyamide based on a composition with hexamethylenediamine, terephthalic acid and lactam, preferably caprolactam, or an aliphatic dicarboxylic acid. Covering (1, 12, 23, 41, 56) according to one of the preceding claims, characterized in that at least some of the monofilaments (8, 10, 11, 16, 19, 27-30, 37-40, 42, 44- 47, 59, 61, 62) consists of PA6T / 6 or comprises PA6T / 6. Use of a covering (1, 12, 23, 41, 56) according to one of the preceding claims in a paper machine or pulp dewatering machine. Use of monofilaments (8, 10, 11, 16, 19, 27-30, 37-40, 42, 44-47, 59, 61, 62) with or made of partially aromatic polyamide, in particular partially aromatic copolyamide, preferably PA6T / 6 for the production of fabrics (1, 12, 23, 41, 56) for paper machines or pulp dewatering machines.

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