ES2371856T3 - PRESS FELT FOR A PAPER MANUFACTURING MACHINE WITH LONG FLOATING THREADS IN THE DIRECTION OF THE MACHINE IN THE BASE FABRIC. - Google Patents

Abstract

Press felt for a papermaking machine comprising: a base fabric, comprising: a set of upper threads in the machine direction (MD); a set of MD lower threads; a set of threads in the machine transverse direction (CMD); interwoven threads with MD upper threads and MD lower threads; the press felt further comprising at least one layer of eraser attached to the base fabric; characterized by the fact that: the upper MD threads, the lower MD threads, and the CMD threads are interwoven in a series of repeating units in which each upper MD thread forms a long MD floating thread on the side of the passing paper above 11 consecutive threads of the CMD thread assemblies.

Description

Press felt for a machine papermaking with long floating threads in the direction of The machine in the base fabric.

Field of the Invention

The present invention generally relates to papermaking, and more especially to fabrics used in Papermaking

Background of the invention

In the conventional manufacturing process of paper with a fourdrinier machine, an aqueous pulp or suspension of cellulosic fibers (known as the "base" paper) is fed at the top of the path of an endless belt of woven wire and / or synthetic material that circulates between two or more rollers The tape, often called "training fabric", provides a surface for papermaking in the upper surface of its upper path that functions as a filter to separate the cellulosic fibers from the base paper from the medium aqueous, which forms a wet paper band. The aqueous medium drains through openings in the mesh of the formation fabric, known as drain holes, by gravity alone or with support of one or more suction boxes located on the surface plus low (that is, on the "machine side") of the path upper tissue.

After leaving the training section, the paper band is transferred to a press section of the machine of making paper, in which it is passed through the openings between one or more pairs of press rollers covered with another fabric, usually called "press felt". The pressure of The rollers removes additional moisture from the belt; the Moisture removal is often accelerated by the presence of a layer of "erases" on the pressing felt. Then transport the paper to a drying section for disposal additional moisture After drying, the paper is ready to Secondary processing and packaging.

Pressing felts normally include one or more layers of base fabric together with one or more layers of erasure. The base fabrics can be designed in one or several layers, although recently conventional fabrics have often been replaced with laminated fabric designs, which may include, for example, a first fine top fabric to improve uniformity in pressure transfer and a more open bottom fabric design to improve water removal. More commonly, laminated base fabrics comprise two single-layered needle-punched fabrics, although double layer fabrics can also be used. In some fabrics, even three or more layers of tissue can be used (see, for example, US Patent No. 5,277,967 in the name of Zehle et al .). These tissues have been normally woven with 12 and 16 draft patterns such as taffeta or simple twill or 6 twill. However, these tissues often suffer from a longer start-up time.

Other advances in the design of felt press They have incorporated non-woven base layers. Examples of these are the spiral fabrics, such as those described in US Patent No. 6,240,608 and in the publication of US Patent No. 20040005833. The fabrics are not tissues can take advantage of the absence of a union in the upper surface of the tissue that can negatively impact the paper marking. However, these tissues may tend to suffer Hydraulic marking and sinking under high loads.

International Patent Publication No. WO 93/01350 discloses a press felt that has at least two distinct layers of monofilament warp threads vertically stacked European Patent Application No. 0549917 discloses a felt to make paper that has a double layer base fabric with a high absorption capacity, in which the plot pattern It has twice as many threads in the direction of the machine in the face upper tissue than the lower side of the tissue.

In view of the above, it would be desirable provide a base fabric for a press felt that exceeds some of the deficiencies of spiral tissues in a period Start-up lower than a laminated base fabric.

Summary of the invention

The present invention provides a felt of papermaking press according to claim independent 1. Preferred embodiments of the invention are reflected in the dependent claims.

The present invention can overcome some of the shortcomings of previous press felts. According to present invention, the press felt for a machine papermaking, comprises: a base fabric, comprising: a set of upper threads in the machine direction (MD); a set of MD lower threads; and a set of threads in the machine transverse direction (CMD) interwoven with threads upper MD and lower MD threads. MD upper threads, the lower MD threads, and the CMD threads are interwoven into a series of repeating units in which each upper thread MD form a long MD floating thread on the side of the paper that passes through over 11 consecutive threads of the CMD thread assemblies. He press felt further comprises at least one eraser layer attached to the base fabric. In this configuration, the floating threads paper side lengths of the base fabric can provide a desirable balance of properties.

Brief description of the figures

Figure 1 is a schematic diagram that Illustrates the press section of a papermaking machine that you can use a press felt according to the ways of embodiment of the present invention.

Figure 2 is a cross-sectional view. of a press felt according to the embodiments of the present invention

Figure 3 is a top view of a fabric Press felt base of Figure 1.

Figure 4 is a top view of the layer bottom of the base tissue of Figure 3.

Figures 5A-5L are seen in section along lines 5A-5A up to 5L-5L of Figure 3.

Figure 6 is a sectional view of a tissue basis according to the alternative embodiments of the present invention.

Figure 7 is a sectional view of a tissue basis according to the alternative embodiments of the present invention.

Figure 8 is a sectional view of a tissue basis according to the alternative embodiments of the present invention.

Figure 9 is a sectional view of a tissue basis according to the alternative embodiments of the present invention.

Figure 10 is a top view of a fabric triple layer base according to alternative embodiments of the invention.

Figure 11 is a top view of the layer bottom of the tissue of Figure 11.

Figure 12 is a sectional view of the tissue base taken along lines 13-13 of the Figure 11

Figure 13 is a sectional view of a base fabric according to the alternative embodiments of the present invention

Figure 14 is a sectional view of a base fabric according to the alternative embodiments of the present invention

Figure 15 is a top view of a fabric triple layer base according to alternative embodiments of the invention.

Figure 16 is a top view of the layer bottom of the tissue of Figure 15.

Figure 17 is a sectional view of the base fabric of Figure 15 taken along lines 22-22 of the
same.

Figure 18 is a sectional view of a base fabric according to the alternative embodiments of the present invention

Figure 19 is a sectional view of a base fabric according to the alternative embodiments of the present invention

Figure 20 is a sectional view of a base fabric according to the alternative embodiments of the present invention

Detailed description of the embodiments of the invention

The present invention will now be described with more detail, showing the embodiments of the invention. This invention can, however, be carried out in different ways and should not be considered limited to the embodiments that are set forth herein. Rather, these forms of realization are provided to make this description exhaustive and complete, and completely transfer the scope of the invention to subject matter experts In the drawings, the same numbers are They refer to similar elements. The thicknesses and dimensions of Some components may be exaggerated for clarity.

Here, the terms "machine direction" (MD) and "cross direction of the machine "(CMD) refers, respectively, to an address aligned with the direction of tissue flow in a machine papermaking, and in a direction parallel to the surface of the tissue and transverse to the direction of movement. Likewise, both flat tissue and endless tissue methods described They are previously well known in the art, and the term "tape endless "herein refers to tapes made by Any of the methods.

Referring now to the figures, in the Figure 1 illustrates a press section of a machine papermaking, usually designated with 10. The section of press 10 includes a press felt 14 that is installed on the same and transmitted by a set of rollers 12. On its way, the felt 14 circulates on a press roller 15. A roller of opposite press 17 is placed so that, together with felt 14 and the press roller 15, form an opening N between the rollers of press 15 and 17.

In operation, a paper band P is transmitted from a training section 16 through the opening N formed by the press rollers 15, 17, where the Press rollers 15, 17 apply pressure to the paper strip P. The pressure releases moisture from the paper strip P which is absorbed by the felt 14. When the felt 14 is transmitted around its roller assembly 12, moisture is removed from the felt 14 and conditioned by one or more suction boxes 20.

Figure 2 illustrates a cross section of the felt 14. As can be seen in these figures, felt 14 includes a layer of base fabric 22 (described in more detail below) and two layers of erasure: one layer of erasure on the side of the machine 24 and a layer of eraser on the side of paper 26. Illustrative and preferably, these eraser layers 24, 26 are attached to the layer of the base fabric 22 by a needle puncture process, but also Other fixing techniques can be used, such as thermal bonding and adhesives, with the present invention. The eraser layers 24, 26 of the machine side and paper side should be formed of a material, such as a synthetic fiber such as acrylic, aramid, polyester or nylon, or a natural fiber such as wool, that contributes to extract water from the base fabric layer 22. The materials Preferred for eraser layers 24, 26 include polyamide, polyester and mixtures thereof. The weight and thickness of the eraser layers 24, 26 may vary, although it is preferable that the proportion of weight of the erasure to the weight of the tissue is about 0.5 and 2.0, 1.0 being most preferred. Also in some embodiments, it may be desirable to have layers additional erase or skip any of the erase layers 24, 26.

Figure 3 illustrates a repeat unit of the top or tissue paper manufacturing surface double base 22, and Figure 4 illustrates a repeated unit corresponding of the bottom layer of the base fabric 22 seen from above. The base fabric 22 includes twelve MD upper threads 31-42, six lower MD threads 51-56, and twelve threads CMD 61-72. He interwoven of these threads is described below.

As can be seen in the Figures 5A-5L, each of the CMD threads 61-72 is interwoven with a pattern of "1 per up / 11 down "with respect to the upper MD threads 31-42. For example, the CMD 66 thread passes over the upper thread MD 31, then passes under each other upper threads MD 32-42.

Within the same tissue sequence, each CMD thread 61-72 is also interwoven with a pattern of "5 above / 1 below" with respect to the lower threads MD 51-56. This is illustrated with the CMD 66 thread, which passes over the lower threads MD 51 and 52, under the lower thread MD 53, and on the lower threads MD 54-56 (the lower threads 51, 52 and 54-56 are consecutive in contiguous repeat units and combine to form the "5 above" portion of the CMD thread sequence). In the embodiment illustrated in Figures 5A-5L, each CMD thread, after passing over an upper MD thread, Follow one of two paths. In the case of threads CMD 61, 63, 65, 67, 69, 71, each of these CMD threads passes under the next five adjacent threads of the upper MD threads and over the next two adjacent lower MD threads before passing under a lower thread MD as part of the weaving pattern. Thus, the CMD 61 thread passes over the MD 32 upper thread, then it passes under the upper threads MD 33-37 when it passes above the lower threads MD 52 and 53, then go through under the lower thread MD 54 before passing over MD lower threads remaining and below MD upper threads remaining. In the case of CMD 62, 64, 66, 68, 70, 72 threads, each one of these CMD threads passes under the next four threads upper MD and the next two lower CMD threads before pass under a lower thread MD. Thus, the CMD 66 thread passes over the upper thread MD 31, under the upper threads MD 32-35 when passing over the lower threads MD 51 and 52, then pass under the lower thread MD 53 before of passing over the remaining MD lower threads and below the remaining MD upper threads. The distance between adjacent CMD threads are between 3 and 7 MD upper threads, with the distancing being normally an odd number of threads superior MD.

Turning now to Figure 3, it can be seen that the upper surface of the fabric 22 includes floating MD threads long ("floating threads" are segments of passing threads or entirely over or entirely under multiple threads adjacent perpendicular; therefore, the "floating threads" MD are segments of MD threads that pass or entirely over or entirely under multiple adjacent CMD threads). At the moment memory, "long MD floating threads" are MD floating threads that pass over or under at least five CMD threads consecutive. "Long MD floating threads on the side of the paper "are long MD floating threads that pass over at least Five consecutive CMD threads on the manufacturing surface of paper, and the "long MD floating threads on the machine side" they are MD floating threads that pass under at least five threads Consecutive CMD on the surface directed towards the machine of the tissue.

The use of the base fabric 22 in the felt 14 can provide a desirable balance of properties. Felts with such base fabrics can exhibit a good sheet quality and a uniform operability. The long MD floating threads on the side of the paper can provide a uniform pressure support to the sheet of paper, which can result in improved quality of the blade and high drain performance. On the machine side of the woven, long MD floating threads can reduce the effect of "false air" during the removal of water from the felt and from the sheets of paper on suction rollers and suction boxes, which they can in turn increase the drain and improve the conditioning of felt. How long floating threads bind to fabrics base, tend to resist sinking (unlike designs nonwovens), and long MD floating threads on the paper side of the tissue provide relatively few joints that can cause a marking of the sheet of paper.

Other double fabrics that have floating threads MD may also be suitable for use herein. invention. For example, Figure 6 illustrates a typical CMD 101 thread for use in a double fabric 100. Fabric 100 differs from fabric 22 in the interwoven of the CMD threads with the upper MD threads and lower. As illustrated in Figure 6, the CMD 101 thread passes on an upper thread MD 122, then it passes under three threads upper MD 123-125 and on a lower MD thread 152 before passing under the lower thread MD 153. The CMD 101 thread then passes over the lower threads MD 154-156 and 151 and below the MD threads 126-132 and 121. As with fabric 22, the distance between adjacent CDM threads is usually between three and seven upper threads MD.

Figure 7 illustrates a double 400 fabric that includes twelve upper threads MD 401-412, twelve threads lower MD 421-432, and twelve CMD threads (here only a thread CMD 441) is illustrated. The CMD 441 thread is interwoven with the upper threads MD 401-412 in a sequence of "1 above / 11 below "and with the lower threads MD 421-432 in a sequence of "5 above / 1 per below / 5 above / 1 below. "As can be seen in Figure 7, the paper side joint formed by the CMD 441 thread when it passes above the upper thread MD 407 is substantially centered between machine side joints formed when the CMD thread 441 passes under the lower threads MD 424 and 430. In this way of embodiment, the adjacent CMD threads may be distanced one with respect to the other as described above.

Variations are illustrated in Figures 8 and 9 of the double fabric of Figure 1. Figure 8 illustrates a fabric 500 which includes twelve upper threads MD 501-512, twelve MD 521-532 lower threads, and twelve CMD threads (only a CMD 541 thread is shown here). The CMD 541 thread is interwoven with the upper threads MD 501-512 in a sequence of "1 above / 11 below" and with the lower threads MD 521-532 in a sequence of "7 above / 1 per below / 3 above / 1 below ". Figure 9 illustrates a fabric 600 in which twelve CMD threads (illustrated by CMD 641 thread) are interweave with the upper threads MD 601-612 in a sequence of "1 above / 11 below" and with the threads lower MD 621-632 in a sequence of "11 by up / 1 down. "In these embodiments, the threads Adjacent CMDs may be offset from each other as described above.

In addition to the double fabrics illustrated in the Figures 3-9, the press felts of the present invention can also employ triple fabrics. In the figures 10-12 an example of one such fabric is illustrated triple which is generally indicated with 700. The 700 fabric includes twelve upper threads MD 701-712, six threads intermediate MD 721-726, six lower MD threads 731-736 and twelve threads CMD 741-752. Each CMD thread is interwoven with the upper MD threads 701-712 with a pattern of "1 above / 11 per below ", and with the lower threads MD 731-736 with a guideline of "5 above / 1 below". As can be seen in the Figure 12, the CMD 741 thread is interwoven with the intermediate MD threads 721-726 in a sequence of "3 above / 3 times below ", with the CMD 741 thread interwoven with an upper thread MD (upper thread MD 702 in Figures 10 and 12) when it passes through above the intermediate threads 725, 726, 721 and interwoven with a lower thread MD (lower thread MD 733 in Figures 10 and 12 when it passes under the intermediate threads 722-724). In a similar but alternative fabric 800 shown in Figure 13, after passing over the upper thread MD 802, CMD 841 thread passes over only one intermediate 822 thread before passing under the intermediate MD threads 823-825 and interwoven under the lower thread MD 834 (CMD 841 thread also passes under the upper threads MD 803-812 and 801, above the lower MD threads 831-833 and 835-836, and above intermediate threads MD 826 and 821). For both embodiments, adjacent CMD threads may be distanced from each other with with respect to the other as described above.

It should be noted in Figure 13 that the threads intermediate MD 821-826 and lower MD threads 831-836 are stacked vertically (that is, each thread intermediate MD 821-826 is placed just above a corresponding lower thread MD 831-836), and that these wire stacks are placed between two upper MD threads 801-812. Figure 14 illustrates a fabric 900 in the that the CMD 941 thread has the interwoven sequence identical to the of the fabric 800 of Figure 13, but the intermediate threads MD 921-926 and the lower MD threads 931-936 not only stacked vertically the one with the other, but also stacked vertically under a thread upper corresponding MD 901-912. The experts in the matter will appreciate that a tissue can be woven following the 700 fabric weaving pattern with intermediate threads and lower MDs vertically stacked under a corresponding MD upper thread, or other embodiments of the fabric in which the intermediate and lower MD threads do not stack vertically

The triple fabric embodiments of Figures 10-14 include the same numbers of intermediate and lower threads MD; however, the tissue embodiments that have the same numbers of MD upper and intermediate threads for use herein invention. Figures 15-17 illustrate a form of realization of this triple fabric indicated in general with 1200. The 1200 fabric includes twelve MD upper threads 1201-1212, twelve intermediate MD threads 1221-1232, six lower MD threads 1241-1246 and twelve CMD threads 1251-1262. In this embodiment, the threads MD 1221-1232 intermediates are stacked vertically under the upper threads MD 1201-1212. The CMD threads are interwoven with MD upper threads 1201-1212 in a sequence of "1 above / 11 per below ", with intermediate threads MD 1221-1232 in a sequence of "7 above / 5 below" and with the threads lower MD 1231-1236 in a sequence of "5 by up / 1 down. "Referring to Figure 17 as a example, after passing over the upper thread MD 1203, the CMD 1260 thread passes over two intermediate threads MD 1224, 1225; he CMD 1260 thread then passes under the intermediate threads MD 1226 and 1227 before passing under the lower thread MD 1244. The CMD thread 1260 then passes under the intermediate MD threads 1228-1232 before passing over the threads intermediate 1221 and 1222 and travel to pass over the thread superior MD 1203. Following this path, the CMD 1260 thread passes on the lower threads MD 1241-1243 and 1245-1246.

Figure 18 illustrates another form of realization of the triple fabric, generally indicated with 1300. As the fabric 1200 described above, fabric 1300 has twelve threads upper MD 1301-1312, twelve intermediate MD threads 1321-1332, six lower MD threads 1341-1346, and twelve CMD threads. 1300 fabric differs of the fabric 1200 described above in the path followed by the CMD thread 1351: after passing over the upper thread MD 1303, the CMD thread 1351 passes over four intermediate MD threads 1324-1327 before passing under the threads intermediate MD 1328-1332 and the lower thread MD 1345. Figure 19 also represents an embodiment of the tissue Similary. The 1400 fabric shown here has twelve threads upper MD 1401-1412, twelve intermediate MD threads 1421-1432, six lower MD threads 1441-1446, and twelve CMD threads. 1400 fabric differs of the 1300 fabric in which the CMD 1451 thread follows a sequence of "6 above / 6 below "with respect to intermediate MD threads. More specifically, the CMD 1451 thread passes over the upper thread MD 1403, above an intermediate thread MD 1424, below six wires intermediate MD 1425-1430 when it passes under the thread lower MD 1444, and passes over six intermediate MD 1431 threads, 1432, and 1421-1424 when it passes over the thread upper MD 1403. Figure 20 shows a very similar fabric 1500, in which the twelve intermediate threads MD 1521-1532 are located under the interstices formed by the threads upper MD 1501-1512 instead of stacking vertically below them. Each of the MD lower threads 1541-1546 are stacked vertically under one of the upper threads MD 1501-1512. CMD threads (illustrated by the CMD 1551 thread) follow the same pattern of interwoven with the upper, intermediate and lower MD threads than the CMD 1451 thread in the 1400 fabric.

It can be seen that each of the forms of embodiment of the fabric illustrated and described with respect to the Figures 6-20 has long MD floating wires. How such, each can provide the kind of performance advantages explained above with respect to tissue 22 of the Figures 3-5L. In addition, others can also be used base fabrics of different weft patterns that have threads long MD floats with the present invention, whether these fabrics doubles, triples, or quadruples.

Normally, the threads used in the fabrics base described above can be of any form (for example, monofilaments, multifilaments, hybrid threads, monofilaments fused and braided) known to be suitable for use in press felts, although monofilaments are preferred or braided For CMD threads, braided monofilaments of 3 or 4 threads may be especially suitable (especially those braided monofilaments of 0.1 to 0.3 mm), such as monofilaments up to 1.0 mm, yarns, multifilaments, threads with wrapped core or combinations thereof. MD threads are normally braided monofilaments, although the monofilaments of up to 1.0 mm, yarns, multifilaments, threads with the wrapped core and their combinations may also be especially suitable for use them in the base fabrics of the press felts of the invention.

The foregoing is illustrative of the invention and not It should be construed as a limitation of it. Although they have described illustrative embodiments of this invention, the subject matter experts will easily appreciate that these are susceptible to many modifications without substantially departing of the novel teachings and advantages of this invention. By consequently, all these modifications are expected to be included in the scope of this invention as defined in the claims. The invention is defined by the following claims.

       \ vskip1.000000 \ baselineskip
    

References cited in the description

This list of references cited by the applicant has been prepared solely as an aid to the reader. It is not part of the European Patent document. Although much attention has been given to compiling them, mistakes and omissions cannot be avoided, the EPO declining any responsibility in this regard .

Patent documents cited in the description

US 5277967 A [0004]

WO 9301350 A [0006]

US 6240608 B [0005]

EP 0549917 A [0006]

US 20040005833 A [0005]

Claims (11)

1. Press felt for a machine for paper manufacturing comprising:

a base fabric, which includes:

a set of upper threads in the machine direction (MD);

a set of MD lower threads;

a set of threads in the machine transverse direction (CMD);

threads interwoven with MD upper threads and lower threads MD;

the press felt further comprising at least one layer of eraser attached to the base fabric; characterized by the fact that:

the threads upper MD, lower MD threads, and CMD threads are interwoven into a series of repeating units in which each MD upper thread forms a long MD floating thread on the side of the paper that passes over 11 consecutive threads of the sets of CMD threads.

         \ vskip1.000000 \ baselineskip
      

2. Fabric according to claim 1, wherein MD upper thread set includes twelve MD upper threads per unit of repetition. 3. Fabric according to claim 1, wherein each of the CMD threads forms only one joint on the paper side in the repeat unit. 4. Fabric according to claim 1, wherein each of the CMD wires forms two joints on the machine side in the repeat unit. 5. Fabric according to claim 1, wherein each of the CMD threads forms only one joint on the side of the machine in the repeat unit. 6. Fabric according to claim 1, further comprising a set of intermediate MD threads located below the upper MD children and above the lower threads MD. 7. Fabric according to claim 6, wherein MD upper thread set includes twelve MD upper threads per unit of repetition. 8. Fabric according to claim 7, wherein the MD intermediate thread set includes six intermediate threads MD per repeat unit. 9. Fabric according to claim 7, wherein MD intermediate thread set includes twelve intermediate threads MD per repeat unit. 10. Fabric according to claim 7, wherein each of the CMD threads forms only one joint on the paper side in the repeat unit. 11. Fabric according to claim 7, wherein each of the CMD threads forms only one joint on the side of the machine in the repeat unit.