JP2012097365A - Papermaking felt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a papermaking felt in which the surface texture is changed at each portion in the width direction without changing the internal structure to improve conveyability of wet paper.SOLUTION: A papermaking felt 1 has a base cloth 2 and a batt fiber layer 3 entangled with the base cloth by needling to form a papermaking surface 5, in which the papermaking surface includes a ground surface which has been subjected to a grinding process of a different condition at each portion in the width direction and has different surface roughnesses in the width direction.

Description

  The present invention relates to a papermaking felt.

  One of the functions required for papermaking felt is the wet paper transportability for stably transporting wet paper in a papermaking machine, and the surface properties (surface roughness) of the papermaking felt papermaking surface It has a great impact on transportability. For example, when the surface roughness of the papermaking surface of the papermaking felt is large, a gap is likely to be formed between the papermaking surface and the wet paper, and the wet paper is easily peeled off from the papermaking surface due to air entering the gap. Become. On the other hand, when the surface roughness is small, the wet paper is likely to be in close contact with the papermaking surface because there are few voids through which air can enter.

  In a papermaking machine, wet paper is transported while being transferred between a plurality of papermaking cloths such as a forming wire, a papermaking felt, and a transfer belt. Therefore, in order to stably transport wet paper, for papermaking felt, the papermaking felt supports the wet paper on the papermaking surface and moves together, and other papermaking felt and forming wire wet paper. In the step of receiving paper, it is preferable that the adhesion between the papermaking surface and the wet paper is high, and in the step of transferring the wet paper to other papermaking felt or the like, the papermaking surface is preferably easily peeled off from the wet paper. The papermaking surface of the paper is desired to have contradictory characteristics. When these wet papers are not delivered and transported ideally, a phenomenon such as abandonment, paper removal, and ear peeling occurs.

  Abandoned ears are a phenomenon that occurs when wet paper is transferred from the forming wire to the papermaking felt (pickup felt). Usually, both ends of the wet paper are passed before the wet paper is transferred from the forming wire to the papermaking felt. Separate the waste paper ear part from the wet paper web part, and pass only the wet paper web part to the papermaking felt, while continuing to transport the waste ear part from which the forming wire has been separated, and the wet paper web part and the waste paper ear part. Is a phenomenon in which the waste lug is transferred to the papermaking felt together with the wet paper body when the bond (adhesiveness) between the separated waste lug and the papermaking felt is high. Paper picked is a phenomenon that occurs during the transfer of wet paper between paper-making felts or between paper-making felts and press rolls, resulting from high adhesion between paper-making felt on the delivery side and wet paper. This means that the wet paper does not peel off from the papermaking felt on the delivery side and the delivery is not performed properly. Ear peeling means that when paper felt transports wet paper on its paper surface, the adhesion between the wet paper ear and the paper surface is weak, and the wet paper ear peels off from the felt paper surface. A phenomenon.

  In order to suppress the picking up of the waste paper, it is preferable that the binding force between the wet paper and the portion corresponding to the paper cutting surface of the papermaking felt is small (easy to peel off). It is preferable that the binding force with the wet paper in the portion corresponding to the entire wet paper on the paper making surface of the delivery paper making felt is small, and in order to prevent ear peeling, the portion corresponding to the wet paper ear on the paper surface It is preferable that the bonding force with the wet paper is large (high adhesion). For this reason, in order to simultaneously suppress the removal of the ears, the removal of the papers, and the peeling of the ears, it is necessary to realize a desired bonding force with the wet paper at each portion in the width direction of the papermaking surface. As an example of configuring such a papermaking felt, in the center and ears in the width direction of the papermaking felt, the yarn density of the base fabric, the number of bat fiber layers, the presence or absence of a resin coating, the presence or absence of a film, etc. There exists what changed the structure of the felt for paper manufacture (for example, patent document 1).

JP-T-2004-517224

  However, the width of the felt for papermaking changes greatly during the manufacturing process due to shrinkage due to density increase due to entanglement of bat fibers in the needling process and thermal contraction due to heating in resin processing and heat setting processes. To do. Therefore, when the yarn density and yarn type are partially changed during the weaving process, when the fineness of the bat fiber and the basis weight of the bat fiber are partially changed during the needling process, or when the resin coating is performed partially. It is difficult to accurately specify the position where the physical properties should be changed before the final heat setting process. In addition, a large change in felt physical properties such as yarn density, basis weight, thickness, and hardness may adversely affect felt performance other than wet paper transportability during use of the felt. For example, if the vat fineness of the wet paper web edge is reduced in order to prevent the peeling of the ears, dirt is accumulated due to a decrease in the air permeability of the portion, and the squeezing performance of the portion is reduced. .

  The present invention has been made in view of the above background, and after final heat setting, by performing processing that does not involve a width change such as heating, the position of a portion that needs to be processed can be more accurately specified. It is an object to improve the transportability of wet paper by changing the surface texture in each part in the width direction without changing the internal structure of the felt.

  In order to solve the above-mentioned problems, the present invention provides a papermaking felt having a base fabric (2) and a bat fiber layer (3) entangled with the base fabric by needling to form a papermaking surface (5). (1) The papermaking surface includes a polished surface that has been subjected to a polishing process under different conditions in each portion in the width direction, and the surface roughness is different in the width direction.

  According to this configuration, it is possible to change the surface roughness of the papermaking surface in the width direction only by changing the polishing conditions. The surface roughness of the papermaking surface of the papermaking felt may be set in consideration of the wet paper transportability. Since the polishing treatment can be performed after heat setting, the distribution of the surface roughness of the papermaking surface can be set precisely.

  In another aspect of the present invention, the arithmetic mean roughness of the papermaking surface or the coefficient of variation of the pressure distribution under an average pressure of 0.1 MPa on the papermaking surface is such that both ends (ear portions 9) are centered in the width direction. It is larger than a part (7). According to this configuration, the surface roughness of both ends in the width direction of the papermaking felt, that is, the portion corresponding to the discarded ear portion of the wet paper increases, and the adhesion between the papermaking felt and the discarded ear portion decreases, Abandoned ears are suppressed.

  The arithmetic average roughness (Ra) here means the arithmetic average roughness Ra defined in JIS_B0601. The coefficient of variation (CV) of the pressure distribution under an average pressure of 0.1 MPa is based on the definition of JISZ8101-1_1.15, and after calculating the standard deviation of the measured surface pressure distribution, Divided by the average value. The coefficient of variation CV is a relative representation of the variation in pressure distribution on the surface, and represents the variation in surface irregularities. Specifically, by overlaying a pressure measurement film on the surface of the felt and pressurizing at 0.1 Pa, forming a pressure spot image corresponding to the unevenness of each sample surface on the pressure measurement film, and analyzing the pressure spot A coefficient of variation CV is obtained. For example, as a pressure measurement film, “Prescale for Fine Pressure (4LW) 0.05 MPa-0.2 MPa” manufactured by Fuji Film Co., Ltd. was used, and analysis of the obtained pressure spots was performed by “FPD-9210” manufactured by Fuji Film Co., Ltd. This is done using a pressure image analysis system.

  According to another aspect of the present invention, the papermaking surface has an arithmetic average roughness in a portion corresponding to both ends of the wet paper placed on the papermaking surface in the width direction (edge corresponding portion 8), or the papermaking surface. The variation coefficient of the pressure distribution under the average pressure of 0.1 MPa is the smallest. According to this configuration, the adhesion between the papermaking felt and the ear of the wet paper is increased, and the ear peeling is suppressed. Further, according to another aspect of the present invention, the arithmetic average roughness of the papermaking surface or the coefficient of variation of the pressure distribution under an average pressure of 0.1 MPa on the papermaking surface has both end portions (ear portions 9) in the width direction. And the central portion (7), and the portions (edge corresponding portions 8) corresponding to both ends of the wet paper placed on the paper making surface are smaller than the both end portions and the central portion. And According to this configuration, the adhesion between the papermaking felt and the ear of the wet paper is increased, and the ear peeling is suppressed.

  In another aspect of the present invention, the arithmetic average roughness of the papermaking surface or the variation coefficient of the pressure distribution under the average pressure of 0.1 MPa on the papermaking surface is preferably different by 10% or more in the width direction. Here, the rate of change is expressed as a percentage of the difference between the maximum value and the minimum value in the arithmetic average roughness in the width direction (or the coefficient of variation of the pressure distribution under an average pressure of 0.1 MPa). It is a thing. Further, the arithmetic average roughness of the portion where the arithmetic average roughness is the smallest in the width direction of the papermaking surface is preferably in the range of 10 μm to 38 μm, and the average pressure on the papermaking surface is 0.1 MPa. It is preferable that the variation coefficient of the portion where the variation coefficient of the pressure distribution is the smallest is in the range of 0 to 0.25. By setting the coefficient of variation of the arithmetic average roughness and pressure distribution within the above ranges, the wet paper web adhesion can be improved, and ear peeling can be reliably prevented.

  Another aspect of the present invention is characterized in that the batt fiber layer includes a core-sheath molten fiber in a portion forming the papermaking surface. According to this configuration, the batt fiber layers can be bonded to each other by melting the sheath portions, and can be efficiently polished in this bonded state.

  According to the above configuration, the papermaking felt can change the surface properties in each part in the width direction without changing the internal structure, and can improve the transportability of the wet paper.

The top view which shows the principal part of the felt which concerns on embodiment FIG. 1 is an enlarged sectional view showing portions A, B, and C of FIG. Side view showing schematic configuration of polishing apparatus Rear view showing schematic configuration of polishing equipment Micrograph of paper surface of B part in Fig. 1 Diagram showing schematic configuration of paper machine (A) Sample 1, (B) Sample 3, (C) Pressure image of sample 4 Diagram showing schematic configuration of wet paper transportability testing device

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A papermaking felt according to the following embodiment is used as a transport means for transporting wet paper in a papermaking machine, and is used in a pressure dehydration (water extraction) process of wet paper.

<Composition of felt>
The papermaking felt (hereinafter simply referred to as felt) 1 according to the embodiment may be an endless felt manufactured endlessly, or may be a seam felt in which ends are joined together in use. .

  As shown in FIGS. 2A to 2C, the felt 1 has a multilayer structure in which a bat fiber layer 3 is laminated and integrated on a base fabric 2 by needling. The base fabric 2 is a woven fabric obtained by weaving warp yarns and weft yarns such as monofilament yarns such as polyamide, twisted yarns obtained by twisting a plurality of monofilaments, and the like. In addition, a multilayer woven fabric, a woven fabric formed only of warp or weft, a resin sheet, or the like can be applied to the base fabric 2.

  The batt fiber layer 3 is composed of staples such as polyamide and polyester, and core-sheath fibers made of two different polymer components. The core-sheath fiber is composed of a core part made of a high melting point polymer and a sheath part made of a low melting point polymer having a lower melting point than the core part. For example, the core part has a high melting point of 200 ° C. or higher. The melting point is a polyamide, and the sheath is a low melting point polyamide having a melting point of 140 ° C to 160 ° C. When the core-sheath fiber is used, the sheath parts are melted and bonded to each other by heat setting, and the form of the batt fiber layer 3 is further stabilized.

  As shown in FIG. 1, the felt 1 has a central part 7 located in the center in the width direction, edge corresponding parts 8 located on both sides of the central part 7, and outwards in the width direction of both edge corresponding parts 8. It is located and is divided into the ear | edge part 9 which comprises the both ends in the width direction of the felt 1. As shown in FIG. Each of the center part 7, the edge corresponding part 8, and the ear | edge part 9 is extended in the length direction. In a state where the wet paper 11 is placed on the papermaking surface 5 of the felt 1, the ear portion 9 faces the discarded ear portion 13 that is separated from the wet paper body portion 12 of the wet paper 11, and the edge corresponding portion 8 is the wet paper web. Opposite both end portions 14 in the width direction of the main body portion 12. That is, both end edges in the width direction of the wet paper web main body portion 12 are arranged on the boundary line between the ear portion 9 and the edge corresponding portion 8. The length in the width direction of the edge corresponding part 8 and the ear | edge part 9 may be 10 cm, for example.

  As shown in FIGS. 2A to 2C, the papermaking surface 5 of the central portion 7, the edge corresponding portion 8, and the ear portion 9 has different surface properties, that is, surface roughness (unevenness). The surface roughness of the papermaking surface 5 of the felt 1 increases in the order of ear portion 9> center portion 7> edge corresponding portion 8. The difference in the surface roughness of the papermaking surface 5 in each of the portions 7 to 9 is caused by the presence and degree of surface polishing described later. The arithmetic average roughness Ra at the ear portion 9 of the papermaking surface 5 is preferably 10% or more larger than the edge corresponding portion 8, more preferably 20% or more. When expressed using other parameters, the coefficient of variation CV of the pressure distribution under 0.1 MPa at the ear portion 9 of the papermaking surface 5 is preferably 10% or more larger than the edge corresponding portion 8, more preferably 20 More than%. The arithmetic average roughness Ra in the edge corresponding portion 8 of the papermaking surface 5 is preferably in the range of 10 μm to 38 μm. When expressed using other parameters, the variation coefficient CV of the pressure distribution under 0.1 MPa in the edge corresponding portion 8 of the papermaking surface 5 is preferably in the range of 0 to 0.25. In addition, since the center part 7 of the felt 1, the edge corresponding | compatible part 8, and the running surface 6 of the ear | edge part 9 are not surface-polished, the surface roughness is substantially the same.

<Method for forming felt papermaking surface>
3 and 4 are schematic views of a polishing apparatus 20 for polishing the papermaking surface 5 of the felt 1 as an example of an apparatus for manufacturing the felt of the present invention. The polishing apparatus 20 includes a drive roll 21 and a stretch roll 22 for running the endless felt 1 in the length direction, and a first polishing roll 23 and a second polishing roll 24 for polishing the papermaking surface 5 of the felt 1. ing. Here, the drive roll 21 may be a dryer cylinder roll using heated oil or steam, which is often used at the time of finishing the felt including the final heat set. The first polishing roll 23 and the second polishing roll 24 are supported so as to be in contact with the papermaking surface 5 of the felt 1 in a state where the felt 1 is wound around the driving roll 21 and the stretch roll 22.

  As shown in FIG. 4, the first polishing roll 23 and the second polishing roll 24 are formed by attaching abrasive cloth paper such as sandpaper to the peripheral surface of a cylindrical shaft body to form abrasive material surfaces 25 and 26. Each is connected to a driving source and is rotatable. The abrasive surfaces 25 and 26 may be integrally formed on the peripheral surface of the shaft body by processing. The width in the width direction of the abrasive material surface 25 of the first abrasive roll 23 is set so as to coincide with the portion of the felt 1 corresponding to the wet paper web body 12. Two second polishing rolls 24 are provided, and each abrasive material surface 26 is set to a portion overlapping with both end portions in the width direction of the abrasive material surface 25 of the first abrasive roll 23. The roughness of the abrasive material surface 26 of the second abrasive roll 24 and the abrasive material surface 25 of the first abrasive roll 23 can be changed as appropriate according to the central portion 7 and the edge corresponding portion 8. The roughness of the material surfaces 25 and 26 may be the same, or the roughness of the abrasive material surface 26 may be smaller than that of the abrasive material surface 25.

  Polishing of the papermaking surface 5 of the felt 1 is performed with the abrasive of the first polishing roll 23 and the second polishing roll 24 rotated while the felt 1 is run in the length direction by the drive roll 21 and the stretch roll 22 of the polishing apparatus 20. This is done by bringing the surfaces 25 and 26 into contact with the papermaking surface 5. The felt 1 is polished by a portion corresponding to the wet paper web main body 12 by the first polishing roll 23, and a portion corresponding to both end portions 14 in the width direction of the wet paper web main body 12 is overlapped by the second polishing roll 24. Is done. As a result, the papermaking surface 5 of the felt 1 was polished only by the ears 9 that were not subjected to the polishing process (that is, the surface of the original bat fiber layer 3 was exposed) and the first polishing roll 23. The center portion 7 and the edge corresponding portion 8 subjected to the polishing process by the first polishing roll 23 and the second polishing roll 24 are formed. The edge corresponding portion 8 is polished by the second polishing roll 24 in addition to the first polishing roll 23, so that the surface roughness can be made smaller than that of the central portion 7. The polishing may be performed using the first polishing roll 23 and then the second polishing roll 24, or may be performed using the first polishing roll 23 and the second polishing roll 24 simultaneously.

  FIG. 5 is a photomicrograph of the papermaking surface 5 of the central portion 7 that has undergone the polishing treatment. As FIG. 5 shows, it is confirmed that each fiber which comprises the bat fiber layer 3 is shaved in the same direction, and is flattened. By cutting each fiber in this way, the surface of the bat fiber layer 3, that is, the papermaking surface 5 of the felt 1 is smoothed. When the fibers constituting the batt fiber layer 3 are core-sheath fibers and the sheath portions are melted and connected to each other by heat setting, the relative displacement of each fiber is restricted, so that the polishing process makes smoother. A smooth surface can be formed. The flattening and the formation of fine scratches and burrs by cutting the fiber increase the surface area of the fiber, thereby increasing the hydrophilicity of the felt 1 and improving the familiarity (initial affinity) with the wet paper web 11. The rotation direction of the polishing roll may be the same direction as the felt traveling direction before the final stage of the polishing process, or may be a direction opposite to the felt traveling direction. However, in the final stage of the polishing process, it is desirable that the direction be opposite to the felt traveling direction. As a result, as shown in FIG. 5, the direction of the burrs formed on the bat fibers by the polishing process can be set to the direction in which the burrs can be suppressed in the papermaking process. It becomes difficult to remove hair.

  The size and arrangement of the central portion 7, the edge-corresponding portion 8, and the ear portion 9 can be achieved by changing the length and position in the width direction of the abrasive material surfaces 25 and 26 of the first polishing roll 23 and the second polishing roll 24. It can be changed as appropriate. Further, the surface properties of the central portion 7 and the edge corresponding portion 8 are the roughness of the abrasive material surfaces 25 and 26 of the first polishing roll 23 and the second polishing roll 24, the first polishing roll 23 and the second polishing roll 24 and the felt. 1, the rotation speed of the felt 1, the rotation speeds of the first polishing roll 23 and the second polishing roll 24, and the relative rotation direction of the felt 1 with the first polishing roll 23 and the second polishing roll 24. It can be changed as appropriate. In another embodiment, three or more polishing rolls having different abrasive surfaces are provided, and the surface of the papermaking surface 5 of the felt 1 is added to the central portion 7, the edge-corresponding portion 8, and the ear portion 9, and more finely. You may make it partition an area | region.

  By changing the polishing conditions in the width direction of the felt, the amount of polishing in each portion in the width direction (the basis weight of the bat fibers removed by polishing) differs, and as a result, the finished felt basis weight differs in the width direction. In particular, if the basis weight difference in the width direction becomes large in the range where the wet paper web body contacts, troubles other than wet paper transport properties such as partial reduction in water squeezing will occur when using felt in a paper machine. There is a fear. Therefore, in consideration of the presence of spot weight of 5% or less in normal felt, it is desirable that the difference in the polishing amount in each part with different polishing conditions is 5% or less. However, when it is known in advance that a difference in the polishing amount in the felt width direction of 5% or more will not cause trouble other than wet paper transportability, it is useful to set the difference in the polishing amount to 5% or more. Is not limited to this.

For example, the normal felt width is wider than the width of the press roll. Therefore, in the felt width direction, there are a portion that receives the press (within the press width) and a portion that does not receive the press (outside the press width). Within the width of the press, the dirt inside the felt is squeezed out together with the water that is squeezed out during pressing. May adversely affect the running performance of the felt. In such a case, the amount of polishing of the portion outside the press width is increased by 5% or more compared to other portions, and the basis weight of this portion is reduced, so that the ease of accumulation of dirt can be suppressed. Since the felt of the present invention performs polishing after the final heat setting, it is easy to set the processing position, so it is possible to reliably set a portion where the basis weight differs by 5% or more to a position where it is not pressed without affecting water squeezing It is.

<Effect>
The function and effect of the felt 1 configured as described above will be described with reference to an example applied to the papermaking machine 40 shown below. As shown in FIG. 6, the felt 1 is used as a pickup felt (hereinafter referred to as Pu felt) 41 of the papermaking machine 40. The papermaking machine 40 cuts the formed wet paper 11 from the suspension containing pulp into the wet paper main body 12 and the discard ear 13 on the forming wire 42. Water jet 43, Pu felt 41, 1PB felt 44 and 2PT felt 45 for sequentially conveying wet paper main body 12, a pair of press rolls 47 and 48 for pressing wet paper main body 12, and wet paper main body The first suction roll 52 for adsorbing the portion 12 from the forming wire 42 to the Pu felt 41, the first suction roll 52 for adsorbing the Pu felt 41 to the 1PB felt 44, and the second PT 45 for adsorbing the 1PB felt 44 to the 2PT felt 45. 2 suction rolls 53.

  The water jet 43 forms a cut at the boundary between the wet paper web body portion 12 and the discard ear portion 13 with respect to the wet paper web 11 on the forming wire 42. The Pu felt 41 is disposed by the Pu roll 51 so as to be in contact with the wet paper 11 on the forming wire 42, and adsorbs and conveys only the wet paper main body 12 from the wet paper 11. The discarded ear portion 13 of the wet paper web 11 is continuously conveyed by the forming wire 42 and separated from the wet paper web main body portion 12. A part of the 1PB felt 44 is disposed so as to be able to contact the wet paper web body 12 held on the Pu felt 41. A pair of press rolls 47 and 48 are provided in the part where the wet paper web main body 12, Pu felt 41, and 1PB felt 44 run together, and they are put together and pressed. The first suction roll 52 is provided on the downstream side of the pair of press rolls 47 and 48, separates the wet paper web main body 12 from the paper making surface 5 of the Pu felt 41, and adsorbs the wet paper web main body 12 to the 1 PB felt 44. . The second suction roll 53 is arranged so that the 2PT felt 45 is in contact with the wet paper web main body 12 on the 1PB felt 44 and adsorbs the wet paper web main body 12 to the 2PT felt 45.

  In the paper making machine 40 described above, the felt 1 used as Pu felt has a surface roughness of the ear portion 9 corresponding to the discarded ear portion 13 from the central portion 7 and the edge corresponding portion 8 corresponding to the wet paper web body portion 12. Since the wet paper is less adsorbable, when receiving the wet paper web portion 12 from the forming wire 42, it is possible to reliably receive only the wet paper web portion 12 without receiving the discard ear portion 13. It can be suppressed and abandoned ears can be suppressed.

  Moreover, since the surface roughness of the edge corresponding | compatible part 8 corresponding to the both ends 14 in the width direction of the wet paper main body part 12 is smaller than the center part 7, the felt 1 has both end parts of the wet paper web main body part 12. 14 can be more closely attached to each other, and the ear peeling can be suppressed. Further, in the felt 1, the surface roughness of the central portion 7 corresponding to most of the wet paper web main body portion 12 is larger than that of the edge corresponding portion 8, and the adhesiveness with the wet paper web main body portion 12 is relatively reduced. Therefore, when the wet paper web body 12 is delivered from the Pu felt 41 to the 1PB felt 44, the wet paper web body 12 is easily peeled off from the Pu felt 41, the delivery is performed smoothly, and paper removal is suppressed. The

  As described above, since the surface roughness of the papermaking surface 5 is different in the width direction, the felt 1 can be abandoned, peeled off, and removed simultaneously. Since the surface roughness of the papermaking surface 5 of the felt 1 is formed by changing the presence / absence and degree of surface polishing in each part in the width direction, there is no significant difference in felt physical properties other than surface properties. It does not adversely affect the performance required for felts other than wet paper transportability, such as the occurrence of partial clogging due to a decrease in air permeability. Further, since the surface polishing can be performed after heat setting of the felt 1, the positions of the central portion 7, the edge corresponding portion 8, and the ear portion 9 can be set precisely.

<Experimental Examples and Examples>
In the following experimental examples, the influence of the surface properties of the felt papermaking surface on the wet paper transportability was confirmed. Samples 1 to 5 used in the experiment are shown in Table 1 below. The felts of these samples have a multi-layer structure in which a bat fiber layer is laminated and integrated on a base fabric by needling, and all other configurations are the same except for the bat fineness and the conditions for polishing the paper surface. The papermaking surface was polished using the polishing apparatus 20 of the above-described embodiment. In the polishing in this experiment, only the first polishing roll 23 was used to form a central portion on which the polishing process was performed on the papermaking surface and an ear portion on which the polishing process was not performed. In the polishing, the first polishing roll 23 was rotated at a speed of about 800 revolutions / minute in the running direction and the reverse rotation direction of each sample, and the sample was rotated at a predetermined number of grinding revolutions at a speed of 20 m / minute.

Here, the variation coefficient CV of the pressure distribution under 0.1 MPa was obtained by using “Pre-scale for fine pressure (4LW) 0.05 MPa-0.2 MPa” manufactured by Fuji Film Co., Ltd. as a pressure measurement film. The analysis of the image was performed using Fuji Film's “FPD-9210” pressure image analysis system. The pressure at the time of measuring the pressure on the felt surface is optimally 0.1 MPa. Felt pressure uniformity can be divided into pressure uniformity mainly due to the base fabric layer and pressure uniformity due to the surface bat layer (= surface pressure uniformity). Since spots are not generated (not measured) under a pressure of about 0.1 MPa, only the felt surface pressure uniformity can be evaluated by a pressure measurement of 0.1 MPa. For samples 2 to 5 in Table 1, the values shown in parentheses for the arithmetic mean roughness Ra and the coefficient of variation CV of the pressure distribution under 0.1 MPa represent the rate of change with reference to sample 1, and the following equation: It can be obtained using.
Rate of change (%) = (Ra (or CV) of sample 1−Ra (or CV) of each sample) / Ra (or CV) of sample 1 × 100

  From comparison between Sample 1 and Sample 2 in Table 1, it can be confirmed that the surface roughness is reduced by decreasing the vat fineness, but the air permeability is also reduced. From the comparison between Sample 1 and Samples 3 to 5, it can be confirmed that the surface roughness decreases according to the degree of polishing. FIG. 7 shows pressure spots formed on the pressure measurement film when samples 1, 3 and 4 were subjected to pressure measurement using the above pressure measurement film. A is sample 1 and B is sample. 3 and C show Sample 4. Also from these figures, it can be confirmed that the unevenness of the felt surface is reduced according to the degree of the polishing treatment. Further, it can be confirmed that the air permeability hardly changes when the polishing treatment is performed. From a comparison between sample 5 and sample 2, surface roughness comparable to that obtained when the vat fineness is reduced can be obtained by polishing. In Sample 1, the arithmetic average roughness Ra and the coefficient of variation CV of the pressure distribution under 0.1 MPa are 10% or more larger than Sample 4 and 20% or more larger than Sample 5 respectively.

  These samples 1 to 5 were evaluated using a wet paper web transportability test apparatus 70 shown in FIG. The wet paper web transportability testing apparatus 70 includes an endless forming wire 75 that is wound around guide rolls 71, 72, 73, and 74 and travels in the length direction. On the path of the forming wire 75, a shower 76 for wetting the forming wire 75 and a suction box 77 for sucking moisture from the forming wire 75 wetted by the shower 76 are provided. It is kept wet. Further, the wet paper web transportability test apparatus 70 squeezes the guide rolls 81, 82, 83, 84 and the suction roll 85 for winding the endless felt made of each of the samples 1 to 5, and each of the samples 1 to 5. A pair of press rolls 86 and 87, a shower 88 for wetting each sample 1-5, and a suction box 89 for sucking moisture from each sample 1-5 wetted by the shower 88 are provided. Each sample 1 to 5 is maintained in a constant wet state by a shower 88 and a suction box 89, and is disposed in the vicinity of the surface of the forming wire 75 by a suction roll 85.

  In the evaluation test, each of the samples 1 to 5 and the forming wire 75 was run in the direction of the arrow in the figure at a speed of 100 m / min, and the wet paper 91 in which moisture was adjusted to 80% in advance was shown in the figure. It was placed on the forming wire 75 at the point A, and it was measured whether the wet paper web 91 was transferred from the forming wire 75 to each of the samples 1 to 5 at the point B in the figure. In the measurement, the suction force of the suction roll was changed in three stages of 5 kPa, 10 kPa, and 20 kPa, and each measurement was performed 20 times. During 20 measurements, the case where the wet paper reached the point C in the figure was 17 or more was evaluated as ◯, 4 to 16 was evaluated as Δ, and 3 or less was evaluated as x. The results are shown in Table 2 below.

  As shown in Table 2, it can be seen from the comparison between Sample 1 and Sample 2 that the surface roughness of the felt 1 is reduced and the adhesion to the wet paper is improved by reducing the vat fineness of the vat fiber layer. I can confirm. From the comparison of Samples 1 and 3 to 5, it can be confirmed that the surface roughness is reduced and the adhesion to the wet paper is improved by increasing the polishing amount. Also, when looking at sample 1, sample 3, and sample 4, when the rate of change of arithmetic mean roughness Ra due to surface polishing and variation coefficient CV of pressure distribution under 0.1 MPa is less than 10% (sample 3), It can be seen that the change in wet paper web adhesion is small. As can be seen from the results of Sample 4, in order to reliably change the wet paper web adhesion, the arithmetic average roughness Ra and the variation coefficient CV of the pressure distribution under 0.1 MPa are changed by 10% or more by surface polishing. Is desirable.

  Examples of the present invention will be described below. Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 3 below. The felts of Examples 1 to 3 and Comparative Examples 1 to 3 have a multilayer structure in which the bat fiber layer 3 is laminated and integrated on the base fabric 2 by needling, except for the bat fineness and the polishing conditions of the papermaking surface 5. All other configurations are the same. The papermaking surface 5 was polished using the polishing apparatus 20 of the above-described embodiment. The polishing in each of the examples and the comparative examples is performed on the papermaking surface 5 using the first polishing roll 23 and the second polishing roll 24 having the abrasive surfaces 25 and 26 having the same roughness and having the same diameter. Predetermined surface properties were set in the central portion 7, the edge corresponding portion 8, and the discarded ear portion 9. In addition, the contact pressure to the felt which concerns on each Example and comparative example of the 1st grinding | polishing roll 23 and the 2nd grinding | polishing roll 24 is substantially the same. In each embodiment, the width direction length B of the edge corresponding portion 8 and the width direction length C of the throw-away ear portion 9 are each 10 cm.

  In Example 1, only the first polishing roll 23 is used, and the first polishing roll 23 is rotated at a speed of about 800 rotations / minute in the traveling direction and the reverse rotation direction of the felt 1, and the felt 1 is rotated at a speed of 20 m / minute. It was rotated 16 times. In Example 2, polishing was performed using the first polishing roll 23 and the second polishing roll 24 simultaneously. The first polishing roll 23 is rotated at a speed of about 800 revolutions / minute in the traveling direction and the reverse rotation direction of the felt 1, and the felt 1 is rotated by eight revolutions at a speed of 20 m / min and polished by the first polishing roll 23. The second polishing roll 24 was rotated at a speed of about 800 revolutions / minute in the direction of rotation of the felt 1 and in the reverse rotation direction, and the felt 1 was rotated eight times at a speed of 20 m / minute and polished by the second polishing roll 24. That is, in Example 2, the center portion 7 is subjected to polishing for 8 laps of the felt, and the edge corresponding portion 8 is subjected to polishing for 16 laps of the felt. In Example 3, only the second polishing roll 24 is used, and the second polishing roll 24 is rotated at a speed of about 800 rotations / minute in the traveling direction and the reverse rotation direction of the felt 1, and the felt 1 is rotated at a speed of 20 m / minute. It was rotated 16 times. That is, in Example 3, only the edge corresponding portion 8 is subjected to polishing for 16 rounds of felt. In Comparative Example 3, a polishing roll for comparative example in which the abrasive material surface 25 of the first polishing roll 23 is extended to a portion corresponding to the throw-away portion 9 is used instead of the first polishing roll 23, and the polishing roll for comparative example is used. Was rotated at a speed of about 800 revolutions / minute in the traveling direction of the felt 1 and in the reverse rotation direction, and the felt 1 was rotated 16 times at a speed of 20 m / minute.

  In Table 3, what is written in parentheses indicates that each part has a surface property (surface roughness) corresponding to each sample of the experimental example described above. When ear peeling occurs in the felt of the specification of Comparative Example 1 or when it is desired to improve wet paper smoothness, the conventional measures are changed to the specification of Comparative Example 2 using a bat fiber having a smaller fineness. From the measurement results in Table 1 above, it is possible to improve the felt smoothness and wet paper web smoothness by changing the specification. From the test results in Table 2 above, the wet paper web adhesion can be achieved by changing the specification. As can be seen from the graph, the peeling of the ear can be prevented. However, the change in the specifications of Comparative Example 2 also improves the wet paper web adhesion of the discarded ear part, so that there is a risk that the discarded ear part will be caught this time, and the air permeability of the felt will decrease. Therefore, dirt easily accumulates, and there is a new risk that the felt usage period will be shortened. Compared to Comparative Example 2, Comparative Example 3 does not change the vat fineness, and improves felt smoothness and wet paper web adhesion by surface polishing. As a result, the problem of contamination due to a decrease in air permeability as in Comparative Example 2 can be solved. However, since the wet paper adhesion of the whole felt is improved like the felt 2, it is impossible to avoid the risk of being thrown away. In contrast to Comparative Examples 2 and 3 as described above, Example 1 improves the felt smoothness and wet paper web adhesion of the wet paper body part compared to Comparative Example 1 by polishing only the wet paper body part. The wet paper web adhesion of the discarded ear is the same as in Comparative Example 1. For this reason, improvement in wet paper web smoothness and ear peeling can be prevented, and occurrence of abandoned ears can be prevented from newly occurring. Further, the felt air permeability is the same level in Comparative Example 1 and Example 1, and there is no fear that dirt easily accumulates. Also, depending on the conditions of the place where the felt is used, the felt of Example 1, Comparative Example 2 or 3 may be taken out of paper. In such a case, it is effective to use the specifications of Examples 2 and 3, and if you want to achieve both paper removal prevention and wet paper smoothness, use the specifications of Example 2 to improve wet paper smoothness. Although there is no effect, it is effective to use the specifications of Example 3 if it is desired to more reliably prevent paper removal.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, four or more parts having different surface roughnesses may be provided in the width direction of the papermaking surface 5 of the felt 1. In addition, the polishing location and the degree of polishing may be appropriately changed according to the desired surface properties.

  DESCRIPTION OF SYMBOLS 1 ... Papermaking felt, 2 ... Base fabric, 3 ... Butt fiber layer, 5 ... Paper-making surface, 6 ... Running surface, 7 ... Center part, 8 ... Edge corresponding part, 9 ... Ear part, 11 ... Wet paper, 12 ... Wet paper main body, 13 ... ear part, 14 ... both ends, 20 ... polishing device, 21 ... drive roll, 22 ... stretch roll, 23 ... first abrasive roll, 24 ... second abrasive roll, 40 ... paper machine, 41 ... Pu felt, 42 ... Forming wire, 43 ... Water jet, 44 ... 1PB felt, 45 ... 2PT felt, 47 ... Press roll, 51 ... Pu roll, 52 ... First suction roll, 53 ... Second suction roll

Claims (12)

A papermaking felt having a base fabric and a bat fiber layer that is entangled with the base fabric by needling and forms a papermaking surface,
The papermaking felt, wherein the papermaking surface includes a polishing surface that has been subjected to a polishing process under different conditions in each portion in the width direction, and has a different surface roughness in the width direction.   2. The papermaking felt according to claim 1, wherein the arithmetic average roughness of the papermaking surface is greater in the width direction at both end portions than in the central portion.   3. The papermaking felt according to claim 2, wherein the papermaking surface has the smallest arithmetic average roughness in a portion corresponding to both ends of the wet paper placed on the papermaking surface in the width direction.   The arithmetic average roughness of the papermaking surface is the same in both end portions and the central portion in the width direction, and portions corresponding to both ends of the wet paper placed on the papermaking surface are the both end portions and the central portion. The papermaking felt according to claim 1, wherein the felt is smaller than the portion. The papermaking felt according to any one of claims 2 to 4, wherein the arithmetic average roughness of the papermaking surface differs by 10% or more in the width direction.
  The arithmetic mean roughness of the portion where the arithmetic mean roughness is the smallest in the width direction of the papermaking surface is in the range of 10 μm to 38 μm, according to any one of claims 2 to 5 The papermaking felt described.   2. The papermaking felt according to claim 1, wherein the coefficient of variation of the pressure distribution under an average pressure of 0.1 MPa on the papermaking surface is such that both end portions are larger than the central portion in the width direction.   The papermaking surface has a smallest variation coefficient of pressure distribution under an average pressure of 0.1 MPa in a portion corresponding to both ends of the wet paper placed on the papermaking surface in the width direction. Item 8. The papermaking felt according to Item 7.   The coefficient of variation of the pressure distribution under an average pressure of 0.1 MPa on the papermaking surface is the same at both ends and the central portion in the width direction, and corresponds to both ends of the wet paper placed on the papermaking surface. The papermaking felt according to claim 1, wherein a portion to be made is smaller than the both end portions and the central portion.   The papermaking felt according to any one of claims 7 to 9, wherein a coefficient of variation in pressure distribution under an average pressure of 0.1 MPa on the papermaking surface differs by 10% or more in the width direction.   11. The variation coefficient of the portion where the variation coefficient of the pressure distribution under the average pressure of 0.1 MPa on the papermaking surface is the smallest is in the range of 0 to 0.25, The papermaking felt according to any one of the items.   The felt for papermaking according to any one of claims 1 to 11, wherein the batt fiber layer includes a core-sheath molten fiber in a portion forming the papermaking surface.