JPWO2007063870A1 - Press belt - Google Patents

Abstract

The press belt reinforcing base material 10 includes first yarn groups 11, 12, and 13 that extend along the belt traveling direction, and second yarn groups 14 and 15 that extend across the first yarn group. The first yarn group includes a twisted yarn 11 located on the outermost surface side of the belt and single yarns 12 and 13 located on the inner surface side of the belt. The second yarn group includes a twisted yarn 14 located on the outermost surface side of the belt and a single yarn 15 located on the inner surface side of the belt.

Description

  The present invention relates to a press belt used for pressurizing an object to be pressed in the paper manufacturing industry, magnetic recording medium manufacturing industry, textile industry, and the like, and more particularly, to a press belt having excellent fatigue strength. .

  In various industries, a belt-like press object is placed on a press belt, and the press object is between one pressure member located inside the circumference of the press belt and the other pressure member located outside the circumference of the press belt. In general, a belt press for pressurizing is used. Examples of the pressure member include a press roll and a pressure shoe.

  One example of a belt press is a shoe press as a dewatering press in the paper industry. The shoe press is disclosed in, for example, Japanese Patent Laid-Open Nos. 11-124788 and 2005-207000.

  In the above shoe press, in order to increase the dewatering efficiency of the wet paper, a press roll as a pressurizing means located outside the circumference of the press belt and a pressurization as an internal pressurizing means located inside the circumference of the press roll Surface pressure is applied to the press object (wet paper) placed on the outer peripheral surface of the press belt with the shoe via the press belt to perform pressurization (dehydration). By using a pressure shoe having a predetermined width in the traveling direction, the nip width can be increased and the dewatering efficiency can be improved.

  The operation of the shoe press will be described in more detail with reference to FIG. FIG. 1 is a diagram showing a cross section in a running direction of a shoe press device used in a press process of a paper machine.

  The shoe press device includes a press roll 1 as pressurizing means, a press belt 2 facing the press roll 1, and a press shoe 3 as internal pressurizing means positioned inside the periphery of the press belt 2. . In the apparatus of FIG. 1, the pressure shoe 3 is covered with a press belt 2, and the press belt 2 is assembled as a roll to form a shoe press roll. The press roll is assembled into a roll. The endless belt can be used as it is.

  Between the press belt 2 and the press roll 1, a wet paper 5 as a press object is passed over the felt 4. The outer peripheral surface of the press belt 2 and the felt 4 are in direct contact. Lubricating oil is supplied between the press belt 2 and the pressure shoe 3, and the press belt 2 can slide on the pressure shoe 3. The press roll 1 is driven to rotate, and the press belt 2 is driven to rotate while sliding on the pressure shoe 3 by the frictional force with the traveling felt 4.

  The pressure shoe 3 is pressed toward the press roll 1 from the inside of the press belt 2, and the wet paper 5 is pressed and dehydrated by this pressing force. The surface of the pressure shoe 3 has a concave shape corresponding to the surface of the press roll 1. For this reason, a nip region having a wide width is formed between the press roll 1 and the press belt 2 along the belt running direction (MD direction: machine direction). This nip region functions as a pressure dewatering unit.

  The press belt 2 made of an elastic material such as resin or rubber usually has a reinforcing base made of a multi-woven fabric inside. As shown in FIG. 1, since the press belt 2 has a shape recessed inward in the nip region in the belt running direction during operation, bending stress and compressive stress always act simultaneously on the press belt portion in the nip region. is doing.

  FIG. 2 is a schematic cross-sectional view of the shoe press device as seen in a direction crossing the belt running direction (CD direction: cross direction). As shown in the drawing, both ends in the width direction of the press belt 4 are mounted on the fitting disc 6. In the nip region in the CD direction, the height of the pressure shoe 3 is lower than the height of the fitting disc 6. For this reason, in addition to the bending stress and compressive stress described above, bending in the CD direction repeatedly occurs at both ends of the nip region of the press belt 4 every time it passes through the nip region.

  When attention is paid to the reinforcing base material made of multiple woven fabrics embedded in the press belt 4, the yarn on the outermost surface extending along the belt running direction (MD direction) tends to be fatigued in the MD nip region. Further, at the end of the CD nip region, the outermost surface yarn extending along the direction intersecting the belt running direction (CD direction) tends to be fatigued.

  Polyester monofilaments (single yarns) may be used as the yarns constituting the multi-woven fabric. Although this polyester monofilament has a property excellent in dimensional stability, it has a property weak against repeated compression. Therefore, in the case of a reinforced base material using polyester monofilaments on the outermost surface of the multi-woven fabric, a fatigue phenomenon tends to occur in a portion that passes through the nip region in a relatively short period.

  When the reinforcing base material made of multiple woven fabrics embedded in the elastic material of the press belt is fatigued and partially disconnected, a crack is generated in the elastic material portion located near the disconnected portion. Further, due to fatigue of the reinforcing base material, the running performance of the press belt may be deteriorated, or the press belt may be warped, which may cause cracks.

  Cracks generated in the press belt may develop in the MD direction and CD direction of the press belt due to repeated bending stress, compressive stress, and bending acting on the nip region, and may cause leakage of lubricating oil.

  An object of the present invention is to provide a press belt having excellent fatigue strength.

  The press belt according to the present invention is obtained by embedding a reinforcing base material made of multiple woven fabrics in an elastic material. The reinforcing base material includes a first yarn group extending along the belt traveling direction and a second yarn group extending so as to intersect the first yarn group. The first yarn group includes a twisted yarn located on the outermost surface side of the belt and a single yarn located on the inner surface side of the belt. The second yarn group includes a twisted yarn located on the outermost surface side of the belt and a single yarn located on the inner surface side of the belt.

  Twisted yarn is supple and high in strength and exhibits excellent resistance to bending stress and compressive stress. Therefore, by using the yarn located on the outermost surface side of the yarn group extending in the MD direction and the CD direction as a twisted yarn, the reinforcing base material has excellent resistance to bending stress and compressive stress acting on the nip region. become.

  Single yarns have strong shape fixability. In particular, when both the yarn extending in the MD direction and the yarn extending in the CD direction are single yarns, the strength of the knot portion at the intersection is increased, and twisting of the reinforcing base material can be suppressed.

  According to the present invention having the above configuration, the MD direction twisted yarn (twisted in the MD direction) and the CD direction twisted yarn (twisted in the CD direction) located on the outermost surface side act so as to increase the fatigue strength of the reinforcing base material, Since the MD direction single yarn and the CD direction single yarn located on the inner surface side act to stabilize the shape of the reinforcing base material, a press belt having excellent fatigue strength and a long life can be obtained.

  In one embodiment, at least one of the first and second yarn groups includes a multifilament between the twisted yarn and the single yarn. In this case, preferably the multifilament is impregnated with a sizing agent. By using the reinforcing base material including the multifilament impregnated with the sizing agent as described above, the generation of pinholes is suppressed, and a press belt excellent in appearance and crack resistance is obtained.

  Moreover, in one embodiment, the drainage groove extended along a belt running direction is formed in the outermost surface of an elastic material. The press belt is, for example, a shoe press belt.

  As described above, according to the present invention, a press belt having excellent fatigue strength can be provided.

It is a figure which shows the cross section of the running direction of the shoe press apparatus used at the press process of a paper machine. It is a figure which shows the cross section of the width direction of a shoe press apparatus. It is an illustration sectional view showing the reinforcement base material concerning the embodiment of the present invention. It is an illustration sectional view showing an example of a press belt concerning an embodiment of the present invention. It is an illustration sectional view showing the reinforcement base material concerning other embodiments of the present invention.

  The inventor of the present application evaluated the fatigue situation, crack progressability and running property of the press belt, and found the following.

  (1) In the case of a reinforced woven fabric base material in which all yarns are composed of single yarns, MD single yarns and CD single yarns located on the outermost surface side due to the effects of repeated bending stress and compressive stress in the nip region Is fibrillated and easily broken.

  (2) In the case of a reinforced woven fabric reinforced base material in which all yarns are composed of twisted yarns, the shape fixability becomes weak, and the press belt twists and twists during running.

  (3) If the MD direction yarn and the CD direction yarn of the reinforcing base located on the outermost surface side of the press belt are twisted yarns, they will not be fibrillated over a long period of time and will have excellent fatigue strength. In addition, the press belt If the MD direction yarn and the CD direction yarn of the reinforcing base located on the inner surface side of the yarn are single yarns, the strength of the knot portion between the MD direction single yarn and the CD direction single yarn is increased, and the shape fixability is excellent. .

  Embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 schematically shows a reinforcing substrate made of multiple woven fabrics, and FIG. 4 is a cross-sectional view schematically showing a press belt. The press belt according to the embodiment of the present invention is used for pressurizing an object to be pressed in the paper industry, the magnetic recording medium manufacturing industry, the textile industry, etc. The size of the press belt is, for example, 2 in width. ˜15 m, circumference is 1 to 30 m, and thickness is about 2 to 10 mm. The press belt is typically a shoe press belt.

  As shown in FIGS. 3 and 4, the press belt includes an elastic material 20 and a reinforcing base 10 embedded in the elastic material 20. The reinforcing base material 10 includes a first yarn group 11, 12, 13 extending along the belt running direction (MD direction), and a second yarn group 14 extending along a direction intersecting the first yarn group (CD direction). , 15 and a multi-woven fabric.

  As a material for forming the reinforcing substrate 10, organic fibers are preferably used. The press belt is required to be flexible, but when inorganic fibers such as glass fibers are used as the reinforcing base material, the press belt becomes too hard and defects such as cracks are likely to occur. . Therefore, it is preferable to use organic fibers such as polyamide fiber, aromatic polyamide fiber, polyester fiber, nylon fiber, and polyvinyl alcohol fiber as the forming material of the reinforcing substrate 10. In particular, a reinforced base material containing polyester fibers is preferable in that it has excellent dimensional stability.

  When attention is paid to the specific structure of the reinforcing base material 10 made of multi-woven fabric, the yarn 11 located on the outermost surface side of the belt among the first yarn group extending along the belt traveling direction is a twisted yarn (MD direction twisted yarn). The yarns 12 and 13 located on the inner surface side of the belt are single yarns (MD direction single yarns). Of the second yarn group extending along the direction intersecting the first yarn group 11, 12, 13, the yarn 14 located on the outermost surface side of the belt is a twisted yarn (CD direction twisted yarn) and is located on the inner surface side of the belt. The yarn 15 to be processed is a single yarn (CD direction single yarn).

  As the elastic material 20, for example, thermosetting polyurethane is used. The elastic material 20 includes, for example, a back surface layer 20 a formed from the back surface side of the reinforcing base material 10 and a surface layer 20 b formed from the front surface side of the reinforcing base material 10. On the outermost surface of the elastic material 20, a number of drain grooves 21 extending along the belt running direction are formed. This drain groove 21 is not essential and can be omitted.

  Twisted yarns are supple and high in strength compared to single yarns and exhibit good fatigue strength against bending. On the other hand, since the single yarn is harder than the twisted yarn, the strength at the knot portion between the single yarns is increased, and the twist of the reinforcing base material is suppressed.

  In the embodiment of the present invention, the MD direction twisted yarn 11 and the CD direction twisted yarn 14 located on the outermost surface side of the belt among the yarn group constituting the reinforcing base material 10 are subjected to repeated bending stress and compressive stress in the nip region. Show good resistance. Further, since the MD direction single yarns 12 and 13 and the CD direction single yarn 15 positioned on the inner surface side of the belt increase the strength at the knot portion, the twist of the reinforcing base material is suppressed, and the press belt is not twisted during traveling. .

  In the case of polyester fiber, the twisted yarn is, for example, two to three multifilaments having a thickness of 200d to 1500d. The thickness of the single yarn is 0.3 to 1.0 mm in diameter.

  FIG. 5 schematically shows a reinforcing substrate 30 of a press belt according to another embodiment of the present invention. The reinforcing base material 30 is a multi-woven fabric. The first yarn group extending in the belt traveling direction includes an MD direction twisted yarn 31 located on the outermost surface side, an MD direction single yarn 32 located on the inner side, an MD direction multifilament 33 located on the inner side, and an innermost side. MD single yarn 34 located. The second yarn group extending in the direction crossing the first yarn group includes a CD direction twisted yarn 35 located on the outermost surface side and a CD direction single yarn 36 located on the innermost surface side.

  MD direction multifilament 33 is not twisted. The multifilament 33 is impregnated with a sizing agent. The sizing agent can eliminate air inside the multifilament by entering between the filaments constituting the multifilament. Therefore, when the press belt is manufactured using the sizing agent-impregnated multifilament 33, the generation of air bubbles can be suppressed, so that the generation of pinholes can be suppressed.

  When thermosetting polyurethane is used as the elastic material for the press belt, a sizing agent containing a urethane resin or an epoxy resin as a main component is preferable in consideration of adhesion to the elastic material.

  As described above, the elastic material typically includes a back surface layer formed from the back surface side of the reinforcing base material and a surface layer formed from the front surface side of the reinforcing base material. In this case, the sizing agent-impregnated multifilament 33 suppresses the penetration of the resin, and thus is located at the boundary between the front surface layer and the back surface layer.

  Six types of samples were prepared as reinforcing substrates made of multiple woven fabrics. Table 1 shows the structures of the six types of samples.

  In Table 1, “MD” means a yarn extending in the belt running direction, and “CD” means a yarn extending in a direction intersecting with it. MD1 and CD1 mean yarns located on the outermost surface side of the press belt, MD2 and CD2 mean yarns located on the inner side thereof, and MD3 means a yarn located on the innermost surface side of the press belt. means. Moreover, in all the samples, a multifilament for resin stopping was arranged between MD2 and MD3.

  In the reinforcing base material of Sample 1, all the yarns are polyester single yarns. In the reinforcing base material of Sample 2, the MD yarn (MD3) located on the innermost surface side is a single nylon yarn, and all the remaining yarns are single polyester yarns. In the reinforcing base material of Sample 3, MD yarn (MD1) located on the outermost surface side is a polyester twisted yarn, MD yarn (MD3) located on the innermost surface side is a single yarn made of nylon, and the remaining yarn is a single yarn made of polyester. is there. The reinforcing base material of Sample 4 is an example of the present invention, MD yarn (MD1) located on the outermost surface side is a polyester twisted yarn, CD yarn located on the outermost surface side (CD1) is a polyester twisted yarn, and the innermost surface side. The MD yarn (MD3) located in is a nylon single yarn, and the remaining yarn is a polyester single yarn. In the reinforcing base material of Sample 5, all the yarns are polyester twisted yarns. The reinforcing base material of Sample 6 is an embodiment of the present invention, and the MD yarn (MD1) located on the outermost surface side and the MD yarn (MD2) located on the inner side are polyester twisted yarns, the MD yarn located on the innermost surface side. (MD3) is a nylon single yarn, a CD yarn (CD1) located on the outermost surface side is a polyester twisted yarn, and a CD yarn (CD2) located on the innermost surface side is a polyester single yarn.

Each reinforcing substrate shown in Table 1 was embedded in an elastic material of thermosetting polyurethane to prepare an elastic band, and this elastic band was mounted on a roll having a diameter of 350 mm, and a fatigue test was performed. Specifically, continuous operation was performed for 7 days while applying a pressure of 50 kg / cm ² to a metal roll rotating at a speed of 200 m / min on an elastic band mounted on a rotatable roll. After the operation was completed, the elastic material of the elastic band was dissolved with a dimethylformamide solvent, the reinforcing base material was taken out, and the deterioration state of the MD yarn and the CD yarn was visually observed. The results are shown in Table 2.

  In Table 2, “x” indicates that the yarn is fibrillated and crushed, and “◯” indicates that there is no change (in particular, no deterioration).

  In Sample 1 and Sample 2 that are all composed of a single yarn, the outermost MD1 and CD1 are fibrillated and crushed. In Sample 3 in which MD1 was a twisted yarn and all the remaining yarns were single yarns, only CD1 was fibrillated and crushed.

  In Sample 4 in which MD1 and CD1 were twisted and the remaining yarn was a single yarn, and in Sample 6 in which MD1, MD2 and CD1 were twisted and the remaining yarn was a single yarn, there was no fibrillated yarn. In Sample 5 in which all yarns were twisted yarns, no fibrillated yarns were found.

  Using the dematcher type bending tester defined in JIS K6260, the crack progress was evaluated for the elastic bands in which the samples 1 to 6 were embedded. In addition, the crack progressability of MD direction and the crack progressability of CD direction were evaluated using a separate test piece, respectively. The size of the test piece was 20 mm wide and 150 mm long. The reciprocating motion was a distance of 42.0 mm. The cut was made at the center in the length direction of the test piece on the outer surface of one end in the width direction with a length of 5 mm and a depth of 1.7 mm.

  After bending 1000 times under the above conditions, the size of the crack was measured. The results are shown in Table 3 as the crack growth length.

  As can be seen from Table 3, in the elastic band in which Sample 1 and Sample 2 were embedded, cracks progressed in both the MD direction and the CD direction. In the elastic band in which the sample 3 in which MD1 was twisted was embedded, cracks in the CD direction did not progress, but cracks progressed in the MD direction. In the elastic band in which Sample 4 and Sample 5 in which MD1 and CD1 were twisted were embedded, cracks did not propagate in both the MD direction and the CD direction. Further, even in the elastic band in which the sample 6 having MD1, MD2 and CD1 as twisted yarns was embedded, cracks did not develop in both the MD direction and the CD direction.

  Next, in order to see the bending rigidity of the reinforcing base materials of Samples 1 to 6, each sample was cut into a 10 cm × 30 cm rectangle. One end on the long side of the rectangular sample piece was grasped by hand, and the sample piece was set up vertically. The shape fixability of each sample piece was evaluated depending on whether it was standing vertically. The results are shown in Table 4.

  As can be seen from Table 4, Sample 5 in which all yarns were composed of twisted yarns did not stand vertically and was found to have poor shape fixability. It was recognized that Samples 1-4 and Sample 6 containing MD single yarn and CD single yarn were all standing vertically and had strong shape fixability.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

The present invention can be advantageously used as a press belt having excellent fatigue strength and strong shape fixability.

Claims (5)

A press belt in which a reinforcing base material composed of multiple woven fabrics is embedded in an elastic material,
The reinforcing substrate includes a first yarn group extending along the belt traveling direction, and a second yarn group extending across the first yarn group,
The first yarn group includes a twist yarn located on the outermost surface side of the belt, and a single yarn located on the inner surface side of the belt,
The second yarn group is a press belt including a twisted yarn located on the outermost surface side of the belt and a single yarn located on the inner surface side of the belt. The press belt according to claim 1, wherein at least one of the first and second yarn groups includes a multifilament between the twisted yarn and the single yarn. The press belt according to claim 2, wherein the multifilament is impregnated with a sizing agent. The press belt according to claim 1, wherein a drainage groove extending along a belt running direction is formed on an outermost surface of the elastic material. The press belt according to claim 1, wherein the press belt is a shoe press belt.

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