MXPA99003618A - Papermakers fabric with enhanced cmd support and stacking - Google Patents

Abstract

A woven papermakers fabric having a first system of yarns interwoven with a second system of yarns. The second system of yarns define a five float repeat on the paper carrying side of the fabric while maintaining vertical alignment of the first system yarns in the respective first and second layers of the first system. Preferably, the first system yarns are cross machine direction (CMD) yarns which repeat with respect to eight pairs of stacked machine direction (MD) yarns.

Description

FABRIC THAT IS USED IN THE MANUFACTURE OF PAPER THAT HAS REINFORCED SUPPORT FEATURES AND MADE IN TRANSVERSAL DIRECTION TO THE MACHINE BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to fabric that is used in the manufacture of paper. More particularly, the present invention relates to the construction of fabric that is used for forming fabrics and press felts.

DESCRIPTION OF THE PREVIOUS TECHNIQUE Paper making machines transform an aqueous fibrous paste into a continuous sheet of paper. The papermaking process starts in a forming section of the papermaking machine, where a pulp of aqueous pulp is deposited on forming fabrics, which have the desired characteristics to retain the pulp fibers while being allowed let the water pass through the fabric. In the forming section, the pulp fibers take the form of an aqueous continuous paper web. The paper web is then transferred to press felts that transport it through a press section of the papermaking machine, where additional water is removed when the paper tape is transported through one or more pressing points. The paper tape is subsequently transferred and transported through a drying section, on drying cloths, to remove the additional water through forced evaporation. The designs of the fabrics for papermaking that are used in each section of the machine vary according to their function. The forming fabrics may possess a fine-mesh weave to support the paper fibers that come in the pulp. Additionally, a fine fabric prevents marks from forming on the paper being formed. The forming fabrics must also have good drainage characteristics to facilitate paper formation during the initial removal of water from the pulp. In addition, the forming fabrics must withstand tensile loads in the machine direction and compression buckling loads in the transverse direction to the machine. For press felt, other diverse characteristics are desired. The press felts must retain a sufficient volume of voids to allow efficient transfer of water leaving the aqueous paper tape as it is transported through the press points. Press felts should be designed to withstand the rigors of moisture and temperature in the pressing section. In addition, the felts must retain uniformity for a considerable period of time, since they are used in the pressing section. In light of these conditions and factors, it is desired to provide pressing felts with reinforced stability, low strength, flow, resistance to compaction, a greater volume of holes, easier cleaning and a lasting press uniformity. Attempts have been made to solve the problems associated with forming fabrics and press felts. For example, U.S. Patent Nos. 4,333,502 and 4,171,009 (Kar) disclose a two-layer forming fabric with a distinctive fabric and a sequential pattern. Although a two-layer forming fabric is disclosed, the two patents show a knitting pattern in the machine direction and do not exhibit the same level of support surface as the present invention. U.S. Patent No. 4,414,263 (Miller et al.) Discloses a two-ply press felt fabric having cords stacked or stacked in the machine direction, with a simple two-ply fabric. U.S. Patent Nos. 5,449,026; 5,167,261; and 5,103,874 (Lee) disclose various fabrics for fabrics having flat yarns stacked in the machine direction. Additionally, U.S. Patent Nos. 4,461,803 and 4,537,816 (Booth et al.) Disclose press base fabrics having yarns stacked in the machine direction, woven with yarns in the transverse direction to the machine, floating on several threads in the direction of the machine, but which do not carry a wide float along the support surface of the paper sheet. U.S. Patent No. 5,089,324 (Jackson) discloses a press base fabric that uses flat monofilament threads of higher dimensional ratio for AMENDED SHEET Provide a high fill factor on the side of the fabric that carries the paper.

Although these patents disclose fabrics that work satisfactorily for many applications, it is desired to provide a structure for forming fabrics and press felts that has characteristics that resolve, more particularly, the problems associated with the fabrics used in papermaking and processes. related, as previously discussed.

SOMARIO OF THE INVENTION The present invention provides a forming fabric and / or a pressing felt, for the field of papermaking, having two layers of yarns in the machine direction (hereinafter simply "MD" for its "machine direction") interwoven with a system of threads in the direction transverse to the machine (hereinafter simply "CMD" for its acronym in English of "cross machine direction"). The fabric structure of the invention contains a long jump in the transverse direction (CMD) to reinforce the support in that same direction (CMD), while at the same time it includes a pattern of type v acute that reinforces the capacity of the threads in The direction of the machine (MD) to be prone to hacinar or stacked. The present invention forms a multilayer fabric having a fine mesh.

AMENDED SHEET The fabric of the present invention, when applied to the forming fabrics, allows these to have an important feature of direct drainage. In addition, another important feature for the forming fabrics is that the fabric provides a reinforced support of the yarn in the CMD direction, which improves the formation of the sheet. This construction of the fabric also allows the overcrowding of the threads while preventing them from twisting in the forming fabric. In press felts several advantages are provided with the fabric construction of the present invention. The fabric reinforces the stability of the felt allowing more threads per inch (that is, every 2.54 cms) in the MD direction. This construction of the press felts allows to provide a low resistance to flow, which in turn makes it possible to greatly improve the removal of water from the aqueous paper strip. _ The resistance to compaction of the press felts is improved. The fabric is resilient and maintains the volume of holes and the cleaning capacity of the pressed felts. Additionally, a durable compression uniformity is imparted to the press felts with this construction and a greater tendency to obtain a smooth sheet characteristic and improve drying is resulted. Other objects and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a fabric constructed in accordance with the teachings of the present invention. Figure 2 is a top view of the fabric shown in Figure 1. Figures 3a-h are a sequence of schematic views showing the successive threads in the CMD direction of the fabric repeat of the fabric shown in Figure 1. Figure 4 is a schematic view of the fabric as shown in Figure 3h, combined with a fluff material stitched on one of its sides to the fabric, so as to form a press felt.

DESCRIPTION OF THE PREFERRED MODALITY For experts in this field it will be easy to recognize that the fabrics used in papermaking can be either plain woven and then sewn or woven in an endless way, to produce what is effectively an endless conveyor belt. In the sense used here, when reference is made to the woven yarns is made according to their respective orientation in relation to the machine for the production of paper, this way you have wires in the direction of the machine (MD) or threads in the cross machine direction (CMD). The direction of the machine extends in the direction of travel of the fabric in the papermaking machine and the cross machine direction extends transversely to the travel direction of the fabric when it is on the papermaking machine. With reference to Figures 1 to 3, a papermaking fabric 10 is shown, comprised of a system of interwoven MD yarns with a CMD yarn system, in a selected repeat pattern. The MD yarns are placed in two layers 41, 42. The MD layer, top or "top 41, is on the side of the fabric leading to the aqueous paper tape, layer 42 MD, bottom or bottom, is on the side of the fabric that is in contact with the papermaking machine.The MD yarns 11-18 and 21-28 of the respective layers MD 41, 42, are vertically aligned in pairs stacked or stacked, 11 and 21, 12 and 22, etc. The knitting pattern of the fabric 10 is repeated with respect to eight cramped pairs of MD 11-18 and 21-28 threads and eight CMD 31-38 threads. repetition floats or jumps on five MD yarns of the upper layer, between a pair of upper and lower MD yarns crowded or stacked, under the next MD yarn of the lower layer, between the next pair of MD upper and lower yarns and, subsequently continue to float or jump over the next five MD yarns of the top layer, in this repeat, for example, the CMD 31 fl ote on the MD 11-15 threads, then continues between the MD 16 thread of the upper layer and the MD 26 thread of the lower layer, later it forms a shank under the thread MD 27 of the lower layer, later it continues between the MD 18 thread of the upper layer and the MD 28 thread of the lower layer, then it is repeated continuing on the next MD thread of the upper layer, starting a new jump or flotation of five MD yarns. When the CMD yarns descend from having woven the five-thread jump over the MD yarns of the upper layer for weaving, between a cramped pair of upper and lower MD yarns, under the MD yarn of the lower layer and between the next pair crowded with upper and lower MD yarns, then return to knit the next jump of the MD yarn of the upper layer, forming a v-shaped pattern. This v-shaped pattern formed between the successive jumps of each CMD yarn maintains a vertical overcrowding of the upper MD yarns 11-18 with respect to the lower MD yarns 21-28 in the MD 41, 42 yarns. As best seen in the Figures 3a-3h, the five-thread jump defined by each CMD thread 31-38 is offset by a distance of three MD yarns from the upper layer relative to each successive CMD thread of the repeat. Accordingly, the first CMD yarn 31 in the repeat jumps or floats on the MD 11-15 yarns of the upper layer. The second yarn CMD 32 in the repeat, jumps or floats over the upper MD 14-18 yarns. The third yarn CMD 33 in the repetition, jumps or floats on the upper MD 17, 18, 11, 12 and 13 yarns. The fourth thread CMD 34 of the repetition, jumps or floats on the threads MD 12 to 16 of the top layer. The fifth yarn CMD 35 of the repetition, jumps or floats on the upper MD yarns 15-18 and 11. The sixth yarn CMD 36 in the repeat, jumps or floats on the yarns MD 18 and 11-14. The seventh CMD thread 37 in the repeat jumps or floats over the upper MD 13-17 yarns. The eighth and last thread CMD 38 of the repeat, jumps or floats on the MD 16-18 and 11, 12 threads of the upper layer. This knitting pattern maximizes the support in the CMD direction for the side of the fabric that carries the paper, while allowing direct drainage while keeping the CMD yarns cramped. Preferably, the fabric is woven in an endless manner. When the fabric 10 is used as a base fabric for a press felt, the MD yarns are preferably monofilament nylon yarns that form a 0.02cm / / (0.008"/ 2/2) cord or are nylon yarns. of a single monofilament that have a diameter of 0.025 to 0.05 cm (0.010"to 0.020"), which are woven from 7.87 to 15.75 threads per cm (20 to 40 threads per inch). The CMD yarns are preferably monofilament yarns from 0.02 to 0.05 cm (0.008"to 0.020") in diameter woven at 11.81 to 27.56 threads per cm (30-70 threads per inch). Alternatively, the CMD yarns can be wire-shaped yarns ranging in size from 0.02cm / 2/2 to 0.008cm / 15/3 (0.008"/ 2/2 to 0.003V15 / 3) or they can be multifilament yarns or EOLlares de 420-1260 denier.The CMD yarns are preferably made of nylon, but can be acrylic, polyethylene terephthalate (PET), polypropylene, polyetheretherketone (PEEK), alcohol HO AMENDED polyvinyl (PVA) or combinations of these. To finish the press felt, preferably a lint material 50 is used as illustrated in Figure 4, which is sewn on one or both sides of the base fabric 10. The amount of lint material preferably it is approximately equal to the weight of the base fabric, so that the weight of the fluff varies in 35-65% of the weight of the finished press felt. When the fabric 10 is intended to be used as a forming fabric, no eraser is used. The MD yarns are preferably woven at a ratio of 11.81 to 157.48 yarns per cm (30-400 yarns per inch) and the CMD yarns are woven at a ratio of 7.87 to 86.61 yarns per cm (20-2: 20 yarns per inch), starting from monofilament threads that have a diameter of 0.0089 to 0.089 cm (0.0035"-0.035"). The sizes of the yarns vary depending on the paper product to be produced, for example, a cross-air type air-drying fabric or a tissue-type paper-forming fabric can be used. Other variations within the scope and spirit of this invention will be apparent to those with ordinary skill in this technical field. Although the invention has been described in part by making detailed references to the preferred embodiments, this detail is intended only to be illustrative and in no way restrictive. Those experts in this field of technology will appreciate that many variations can be made to the structure and mode of AMENDED SHEET operation without departing from the spirit and scope of the invention, as disclosed in the teachings contained herein. AMENDED SHEET

Claims (16)

1. CLAIMS: 1. A fabric used in the production of paper (10) having a paper carrier side and a side that comes into contact with the machine, which comprises a first system of threads (11-18,21). 28) having an upper layer (41) of threads (11-18) on the side of the fabric (10) that carries the paper and a lower layer (42) of threads (21-28) on the side of the paper. the fabric (10) that is in contact with the machine; the first thread system (11-18,21-28) is interlocked in a selected repeat pattern with a second thread system (31-38), so that the second thread system (31-38) retains the threads of the upper layer (41) of the first system (11-18") in a crowded relationship with respect to the threads of the lower layer (42) of the first system (21-28), the fabric being characterized in that each thread of the second system (31-38) is round or cable-shaped and is woven in a repeating pattern over five successive threads of the first thread system (11-18) of the upper layer (41), to define a five-thread jump formed by round or cable-shaped threads on the side of the fabric (10) where the paper is carried, and below a single thread of the first thread system (21-28) in the lower layer (42), for define a single hock on the side of the fabric (10) that will be in contact with the machine, this in each repetition 2. A fabric that is used for training e paper (10) according to claim 1, wherein the yarns AMENDED SHEET of the first system (11-18,21-28) are threads in the machine direction (MD) and the threads of the second system (31-38) are threads in the cross-machine direction (CMD). 3. A wet pressing felt (10) according to claim 2, wherein the machine direction yarns (MD) (11-18,21-28) are woven in a ratio of 7.87 to 15.75 yarns per cm ( 20 to 40 threads per inch) and the threads in the cross machine direction (CMD) (31-38) "are woven in a ratio of 11.81 to 27.56 threads per cm (30 to 70 threads per inch). wet pressing felt (10) according to claim 2, wherein the wires in the machine direction (MD) (11-18,21-28) constitute monofilament nylon in wire form of 0.02cm / 2/2 (0.008) "/ 2/2). A wet pressing felt (10) according to claim 2, wherein the machine direction yarns (MD) (11-18,21-28) are single monofilament yarns having a diameter of 0.025 to 0.05 cm ( 0.010"inches to 0.020 inches.) 6. A wet pressing felt (10) according to claim 2, wherein the yarns in machine transverse direction (CMD) (31-38) are made of a material selected from the group that It consists of nylon, acrylic, polyethylene terephthalate, polypropylene, polyetheretherketone, polyvinyl alcohol and combinations thereof 7. A forming fabric - used in the manufacture of paper (10), comprising a fabric for the SHEET E IN A papermaking according to claim 2, wherein the yarns in the machine direction (MD) (11-18,21-28) are woven in a ratio of 11.81 to 157.48 yarns per cm (30 to 400 yarns per inch), the threads in the cross machine direction (CMD) are woven in a ratio of 7.87 to 78.74 threads per cm (20 to 200 threads per inch), and threads (11-18,21-28,31-38) have a diameter in the range of 0.0089 to 0.089 cm (0.0035 inches to 0.035 inches). 8. A fabric that is used in the papermaking (10) according to claim 2, wherein the repeat pattern is eight threads in the cross machine direction (CMD) (31-38), and eight pairs crammed together Machine direction yarns (MD) of the upper and lower layers (11-18,21-28). A fabric that is used in papermaking (10) according to claim 8, wherein the five-wire jump defined by each yarn in machine-transverse direction (CMD) (31-38) is offset by a distance of three threads of the address of the machine (MD) (11-18) of the upper layer (41), with respect to each successive thread in the direction transverse to the machine (CMD) (31-38), in the repetition. 10. A wet pressing felt (10) comprising a base fabric according to claim 9 and a fluff material (50) stitched to the base fabric, so that the fluff material (50) comprises 35 to 65% by weight of the press felt (10). AMENDED SHEET 11. A wet pressing felt (10) according to claim 10, wherein the yarns in the machine direction (MD) (11-18,21-28) are woven in a ratio of 7.87 to 15.75 yarns per cm (20 a 40 threads per inch) and the threads in the cross machine direction (CMD) (31-38) are woven in a ratio of 11.81 to 27.56 threads per cm (30 to 70 threads per inch). 12. A wet pressing felt (10) according to claim 10, wherein the wires in the machine direction (MD) (11-18,21-28) are monofilament nylon cable-shaped 0.02cm / 2 / 2 (0.008"/ 2/2) 13. A wet pressing felt (10) according to claim 10, wherein the wires in the machine direction (MD) (11-18,21-28) are monofilament threads. singles having a diameter of 0.025 to 0.05 cm (0.010 inches to 0.020 inches) 14. A wet pressing felt (10) according to claim 10, wherein the yarns in the cross-machine direction (CMD) (31- 38) are made of a material selected from the group consisting of nylon, acrylic, polyethylene terephthalate, polypropylene, polyetheretherketone, polyvinyl alcohol and combinations thereof 15. A forming fabric (10) comprising a fabric for the manufacture of paper according to claim 9, wherein the yarns in the machine direction (MD) (11-18,21-28) they are woven in a ratio of approximately 11.81 to approximately 157.48 threads per cm (approximately 30 a AMENDED SHEET about 400 threads per inch), the threads in the cross machine direction (CMD) are woven in a ratio of about 7.87 to about 78.74 threads per cm (about 20 to about 200 threads per inch), and the threads (11- 18.21-28.31 ^ 38) have a diameter of about 0.0089 to about 0.089. cms (about 0.0035 inches to about 0.035 inches) 16. A wet press felt (10) comprising a base fabric according to claim 1 and a fluff material (50) stitched to the base fabric so that the fluff material comprises 35 to 65% by weight of the press felt (10). AMENDED SHEET A woven fabric that is used in papermaking and that has a first system of interlaced yarns with a second thread system. The second yarn system defines a five yarn skip repeat on the side of the paper carrier fabric, while retaining the vertical alignment of the yarns of the first system in the respective first and second layers of the first system. Preferably, the yarns of the first system are yarns in the transverse direction to the machine (CMD) that are repeated in relation to eight pairs of yarns crammed in the machine direction (MD).