JP2005041109A - Flow-on sheet forming method of cement sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the leakage of floating water from the end part of a scrape-off means when the floating water, which is floated to the surface layer of a green sheet by surface leveling, is scraped off. <P>SOLUTION: A weir (16) extended in the advance direction of the green sheet (6) is provided over the range from both sides of a flow box (2) to the scrape-off means (10) and the leakage of the floating water (8) from the end part of the scrape-off means is suppressed by the weir. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The invention of this application relates to a flow-on papermaking method for cement boards. More specifically, the invention of this application is directed to a flow-on of a cement board that can suppress leakage of floating water from the end of the scraping means when scraping floating water that floats on the surface of the green sheet due to surface smoothing. It relates to the paper making method.

  A flow-on papermaking method is known as a manufacturing technique of a cement board used for building exterior materials such as an outer wall material, a roof material, and a roofing material. In the flow-on papermaking method, a raw material containing reinforcing fibers such as cement and pulp and appropriately added with silica or the like is kneaded with water to have a relatively high concentration or a high concentration of about 25 to 65% solid content concentration. Supply cement slurry to papermaking belt. The papermaking belt has water permeability such as made of felt, is formed in an endless shape, and circulates while being suspended by a driving roll and a driven roll. The cement slurry supplied to this papermaking belt spreads over the papermaking width to form a green sheet. In the flow-on papermaking method, the green sheet is vibrated from the surface side by a vibration device in the leveling zone. The floating water that floats on the surface of the green sheet due to the smoothing of the surface is transferred downstream from the vibration device with respect to the traveling direction of the green sheet through the water-permeable sheet disposed on the surface side of the green sheet. Suction box disposed under the papermaking belt in the suction zone after draining the floating water scraped off by the scraping means such as a scraper or roll disposed and draining the scraped water above the green sheet using a suction device. The water contained in the green sheet is dehydrated under reduced pressure below the papermaking belt.

  The surface texture of the dehydrated product is improved by scraping and removing floating water by scraping means and a suction device.

  However, part of the floating water tends to leak from the end of the scraping means. Until now, no particular consideration has been given to the leakage of floating water, and the cement boards were continuously manufactured while flowing out to the end of the papermaking belt. For this reason, the solid content contained in the floating water gradually accumulates in the drive roll, the subsequent transport device, and the like, and a large amount of deposits was formed after 2 to 3 days. In addition, the solid content collected on the drive roll may be transferred to the surface of the dehydrated product. In this case, it has become a cause of troubles in an adsorption transfer process, a press molding process, and the like which are post processes. Thus, the leakage of floating water has affected the maintainability of the apparatus and the operating rate of cement board production.

  Conventionally, it is known that a raw material leakage prevention weir is provided at the side end of the suction box (see, for example, Patent Document 1). This raw material leakage prevention weir is for regulating the width of a green sheet, There is no effect of suppressing leakage of floating water from the end of the collecting means.

The invention of this application has been made in view of such circumstances, and suppresses leakage of floating water from the end of the scraping means when scraping floating water that floats on the surface of the green sheet due to surface smoothing. The problem to be solved is to provide a flow-on papermaking method for cement boards that can be done.
Japanese Patent Laid-Open No. 11-188712

  The invention of this application is to solve the above problems. First, a cement slurry is supplied from a flow box to a papermaking belt that moves, and a green sheet that is developed on the papermaking belt is fed from its surface side by a vibration device. After the surface is smoothed by vibration, the floating water that floats on the surface of the green sheet by the surface smoothing by the vibration device is green by scraping means arranged downstream of the vibration device in the traveling direction of the green sheet. Scattered through the water-permeable sheet placed on the surface side of the sheet, drained the floating water above the green sheet by a suction device, then dehydrated the water contained in the green sheet under the papermaking belt under reduced pressure This is a flow-on papermaking method for cement board, which is applied to both sides of the flow box and scraped off from the green box. Provided weir extending in the traveling direction of, this weir, to provide a flow-on papermaking method cement boards, characterized by suppressing the leakage of floating water from the end of the scraping means.

  The invention of this application is, secondly, in the flow-on papermaking method of the first cement board, a drainage device is provided outside the weir on the downstream side with respect to the traveling direction of the green sheet, A flow-on papermaking method for a cement board for draining floating water partially leaking from an end of the means is provided.

  Thirdly, the invention of this application corresponds to the both ends of the green sheet in the flow-on papermaking method of the first or second cement board, on the downstream side of the scraping means with respect to the traveling direction of the green sheet. A residual water drainage device is provided at the site, and a flow-on papermaking method for a cement board that drains residual water partially leaking from the gap between the end portion of the scraping means and the weir is provided by the residual water drainage device.

  According to the flow-on papermaking method of the first cement board of the invention of this application, the leakage of floating water from the edge of the scraping means is suppressed when scraping off floating water that floats on the surface of the green sheet due to surface smoothing. can do. Maintainability of the drive roll, the conveying device, etc. is improved, troubles in the subsequent process are reduced, and the operation rate of manufacturing cement boards is improved.

  According to the second cement board flow-on papermaking method of the invention of this application, in addition to the effect of the first cement board flow-on papermaking method, the floating water partially leaked from the end of the scraping means is drained. can do.

  According to the flow-on papermaking method of the third cement board of this application, in addition to the effect of the flow-on papermaking method of the first or second cement board, a part from the gap between the end of the scraping means and the weir. Residual water leaking can be drained.

  Hereinafter, the flow-on papermaking method for a cement board according to the invention of this application will be described in more detail.

  1 and 2 are a plan view and a side view, respectively, showing an outline of a flow-on papermaking method for a cement board according to the invention of this application.

  For example, as shown in FIG. 1 and FIG. 2, the flow-on papermaking method for the cement board of the invention of this application contains reinforcing fibers such as cement and pulp, silica, etc., as in the conventional flow-on papermaking methods. A papermaking belt in which a cement slurry (1) having a relatively high concentration or a high concentration prepared by kneading a raw material to which is appropriately added with water and having a solid content concentration of about 25 to 65% is moved from the flow box (2) Supply to (3). The papermaking belt (3) is made of felt, plastic, metal or the like and has a water permeability, is formed in an endless shape, and circulates around the drive roll (4) and the driven roll (5). The cement slurry (1) supplied to the papermaking belt (3) is then developed to a papermaking width to become a green sheet (6).

  In the flow-on papermaking method for the cement board of the invention of this application, in the leveling zone, the green sheet (6) is vibrated from the surface side thereof by the vibration device (7) to smooth the surface. The moisture in the green sheet (6) floats up to the surface layer due to the smoothing of the surface. The floating water (8) is a water-permeable sheet (9) having water permeability disposed on the surface side of the green sheet (6). Is scraped off by scraping means (10) such as a scraper and a roll disposed on the downstream side of the vibration device (7) with respect to the traveling direction of the green sheet (6). The floating water (8) thus scraped off is drained above the green sheet (6) using the suction device (11). As shown in FIG. 1, the suction device (11) is provided with a plurality of holes (12), slits, and the like on the back surface side, and the floating water (8) has these holes (12), slits, etc. And is drained above the green sheet (6).

  In the above leveling zone, a natural dewatering box (13) is provided below the papermaking belt (3). The natural dewatering box (13) drains water contained in the green sheet (6) by being naturally flown down through the papermaking belt (3) by vibration by the vibration device (7). Is.

  Next, in the flow-on papermaking method for the cement board of the invention of this application, in the suction zone, the water contained in the green sheet (6) is dehydrated by reducing the pressure below the papermaking belt (3), and the dehydrated product (14) Get. In this suction zone, a suction box (15) is provided below the papermaking belt (3), and receives and drains water that moves from the green sheet (6) to the back side of the papermaking belt (3) by dehydration under reduced pressure. .

  And in the flow-on papermaking method of the cement board of the invention of this application, as shown in FIGS. 1 and 2, the traveling direction of the green sheet (6) from the both sides of the flow box (2) to the scraping means (10) A spreading weir (16) is provided, and the weir (16) suppresses leakage of floating water (8) from the end of the scraping means (10). Accordingly, the floating water (8) is prevented from flowing out to the end of the papermaking belt (3), and the solid content contained in the floating water (8) is reduced to the drive roll (4), the following conveying device, and the like. It is reduced that it accumulates in. There is little transfer of the solid content to the surface of the dehydrated product, and the occurrence of troubles in the adsorption transfer process, press molding process, etc., which are subsequent processes, is also suppressed. The maintainability of the equipment is improved and the operation rate of cement board production is improved.

  In the cement sheet flow-on papermaking method of the invention of this application, as shown in FIGS. 3 and 4, in addition to the disposition of the weir (16), the weir (16 on the downstream side in the traveling direction of the green sheet (6) ) On the outside of the drainage device (17). Leakage of the floating water (8) from the end of the scraping means (10) is suppressed by the weir (16), but there is a possibility that the leakage cannot be completely suppressed. Considering this, in the flow-on papermaking method for the cement board of the invention of this application, the drainage device (17) is provided at the predetermined position, and the floating water (8) that partially leaks from the end of the scraping means (10). ) Can be drained by the drainage device (17).

  Further, in the flow-on papermaking method for the cement board of the invention of this application, as shown in FIGS. 5 and 6, the green sheet (10) is disposed downstream of the scraping means (10) with respect to the traveling direction of the green sheet (6). 6) A residual water drainage device (18) can be provided at a portion corresponding to both end portions of 6). There may be a gap between the scraping means (10) and the weir (16). In this case, there is a concern that the floating water (8) leaks from the gap and becomes residual water (19) and remains on the surface layer of the green sheet (6). The presence of the residual water (19) increases the moisture content at the end of the green sheet (6) in addition to the above-mentioned problem, so that it is necessary to increase the dehydration time in the suction zone. This extension of the dehydration time extremely reduces the water content at the center of the dehydrated product (14), so that cracks and the like are generated on the surface, which may reduce the strength of the dehydrated product (14). Therefore, in the flow-on papermaking method for the cement board according to the invention of this application, the residual water drainage device (18) is provided at the predetermined position, and the gap is formed between the end of the scraping means (10) and the weir (16). The residual water (19) leaking out can be drained.

  Furthermore, in the flow-on papermaking method for the cement board of the invention of this application, as shown in FIG. 7, the drainage device (17) shown in FIGS. 3 and 4 and the residual water drainage device shown in FIGS. (18) can also be used in combination. Thereby, it becomes possible to further suppress the leakage of the floating water (8).

[Examples 1 and 2 and Comparative Examples 1 and 2]
A raw material containing 50% by weight of ordinary Portland cement, 5% by weight of pulp and 45% by weight of silica was dispersed in water to prepare a cement slurry having a solid concentration of 40%. This cement slurry is supplied from the flow box to the papermaking belt, the surface of the green sheet is smoothed with a vibration device, and the floating water is scraped off and sucked through the water-permeable sheet placed on the surface side of the green sheet. After suctioning and draining upward using a device at a vacuum of 20 kPa, vacuum dehydration was also performed from below the papermaking belt at a vacuum of 40 kPa. The papermaking belt was made of felt, moved at a speed of 30 m / min, and continuously operated for 10 days.

  In Example 1, as shown in FIG.1 and FIG.2, the weir extended in the advancing direction of a green sheet from the both sides of the flow box to the scraping means was provided. The weir was made of polyester and had a thickness of 2 mm. In Example 2, as shown in FIG. 3 and FIG. 4, in addition to the arrangement of the weirs in Example 1, a drainage device is provided outside the weir on the downstream side in the traveling direction of the green sheet, and the suction pressure is 1 to 3 kPa. Sucked in. A water-sealed pump (5 kW) was used as the drainage device, and a springed hose with an outer diameter of 33 mm and an inner diameter of 25 mm was used near the suction port.

  In Comparative Example 1, the weir was provided, but not from the flow box to the scraping means but to the vibration device. In Comparative Example 2, the same drainage device as in Example 2 was provided in Comparative Example 1.

  The maintenance time of the driving roll, the maintenance time of the conveying device following the driving roll, and the operating rate of cement board production were measured and evaluated. The results are shown in Table 1.

  As shown in Table 1, Examples 1 and 2 are more maintainable than Comparative Examples 1 and 2, and Example 2 is particularly excellent.

  In Comparative Example 1, the frequency of trouble occurrence in the post-process (adsorption transfer process, press molding process, etc.) is high, and therefore, the operating rate of cement board production is low. In Comparative Example 2, the drainage device sucks not only the floating water but also the end of the green sheet, and the solid content in the drainage device is large. Therefore, in Comparative Example 2, it is necessary to frequently remove the solid content, and the operating rate of cement board production is low.

On the other hand, in Examples 1 and 2, there are few troubles and the operation rate of cement board manufacture is high. In Example 2, the operating rate is particularly high.
[Example 3, Comparative Example 3]
A raw material containing 50% by weight of ordinary Portland cement, 5% by weight of pulp and 45% by weight of silica was dispersed in water to prepare a cement slurry having a solid concentration of 40%. This cement slurry is supplied from a flow box to a felt papermaking belt, the surface of the green sheet is smoothed by a vibration device, and floating water is scraped off by a scraping means through a water-permeable sheet arranged on the surface side of the green sheet. After suction and drainage using a suction device at a vacuum degree of 20 kPa, vacuum dehydration was performed at a vacuum degree of 40 kPa from below the papermaking belt. The operation was continued for 10 days while adjusting the water content of the dehydrated product to 25%.

  In Example 1, as shown in FIGS. 5 and 6, weirs extending in the traveling direction of the green sheet from both sides of the flow box to the scraping means are provided, and on the downstream side of the scraping means with respect to the traveling direction of the green sheet. A residual water drainage device was provided at a portion corresponding to both end portions of the green sheet. The weir was made of polyester and had a thickness of 2 mm. A water-seal pump (5 kW) was used for the residual water drainage device, and suction was performed at a suction pressure of 1 to 3 kPa.

  In Comparative Example 3, in Example 3, the weir was not applied from the flow box to the scraping means, but up to the vibration device.

  The dehydration time, the variation in the moisture content in the width direction of the dehydrated product, the bending strength of the dehydrated product, the operating rate of cement board production and the maintenance time of the drive roll and the transport device following the drive roll were measured and evaluated. The results are shown in Table 2.

  The bending strength of the dehydrated product was measured by a three-point bending test using a test piece having a thickness of 7 mm and a bending span of 100 mm and a head speed of 2 mm / min. The value described in Table 2 shows the average value of the values obtained by sampling the dehydrated product 6 times / 1 day × 10 days = 60 times.

  As shown in Table 2, the productivity of Example 3 is much higher than that of Comparative Example 3. Moreover, in Example 3, since the variation in the moisture content of the dehydrated product is small and cracks or the like are hardly formed on the surface, the bending strength of the dehydrated product is high. Even in Comparative Example 3, the dehydrated product has high bending strength, but compared with Example 3, the operation rate and maintenance performance of cement board production are far inferior.

  Of course, the invention of this application is not limited by the above embodiments. It goes without saying that various aspects are possible for the details.

  As described above in detail, the flow-on papermaking method for the cement board according to the invention of this application prevents leakage of floating water from the end of the scraping means when scraping floating water that floats on the surface of the green sheet due to surface smoothing. Can be suppressed.

It is the top view which showed the outline | summary of the flow-on papermaking method of the cement board of this invention. It is the side view which showed the outline | summary of the flow-on papermaking method of the cement board of this invention. It is the top view which showed one form of the flow-on papermaking method of the cement board of invention of this application. It is the side view which showed one form of the flow-on papermaking method of the cement board of this invention. It is the top view which showed one form of the flow-on papermaking method of the cement board of invention of this application. It is the side view which showed one form of the flow-on papermaking method of the cement board of this invention. It is the top view which showed one form of the flow-on papermaking method of the cement board of invention of this application.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cement slurry 2 Flow box 3 Papermaking belt 4 Drive roll 5 Driven roll 6 Green sheet 7 Vibrating device 8 Floating water 9 Water-permeable sheet 10 Scraping means 11 Suction device 12 Hole 13 Natural dehydration box 14 Dehydrated product 15 Suction box 16 Weir 17 Drainage device 18 Residual water drainage device 19 Residual water

Claims (3)

  The cement slurry is supplied from the flow box to the moving papermaking belt, and the green sheet developed on the papermaking belt is vibrated from the surface side with a vibration device to smooth the surface, and then vibrates with respect to the traveling direction of the green sheet. By the scraping means disposed downstream of the apparatus, the floating water that floats on the surface of the green sheet due to the surface smoothing by the vibration device was scraped off and scraped through the water-permeable sheet disposed on the surface side of the green sheet. This is a cement-on flow-on papermaking method in which floating water is drained above the green sheet by a suction device, and then the water contained in the green sheet is depressurized and dehydrated below the papermaking belt. A weir extending in the traveling direction of the green sheet is provided, and by this weir, scraping means Flow on papermaking method cement boards, characterized by suppressing the leakage of floating water from the end portion.   The flow-on of the cement board according to claim 1, wherein a drainage device is provided outside the weir on the downstream side with respect to the traveling direction of the green sheet, and the floating water that partially leaks from the end of the scraping means is drained by the drainage device. Paper making method.   On the downstream side of the scraping means with respect to the traveling direction of the green sheet, a residual water drainage device is provided at a portion corresponding to both side edge portions of the green sheet, and this residual water drainage device allows the end of the scraping means and the weir to The flow-on papermaking method for a cement board according to claim 1 or 2, wherein residual water partially leaking from the gap is drained.