JPH0327249B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for manufacturing a filter cloth for solid-liquid separation,
More specifically, the present invention relates to a method for producing a filter cloth suitable for use in a solid-liquid separator using a running filter cloth.

[Prior Art] Conventionally, an endless filter cloth carrying a solid liquid is run through a pressing section consisting of a transfer drum and a pressing roll, and the liquid component in the solid liquid is squeezed out by the pressing section, while the liquid component remaining on the filter cloth is Filter cloth traveling type dehydrators (belt press type dehydrators) transfer the ivy cake to a transfer drum and collect it by scraping it off with a scraper. Solid-liquid separators, such as filter cloth traveling type filters, which perform filtration and recover the remaining half-cake-like components from the filter cloth, are used in various fields. The filter cloth according to the present invention is used in such a solid-liquid separator.

Filter cloths used in the above-mentioned solid-liquid separator have conventionally been disclosed in, for example, JP-A-59-115720, JP-A-60-31811, JP-A-60-44013, and JP-A-60. −44014 Publication, JP-A-61-
164613, JP 61-171516, JP
Those described in JP-A No. 61-174912, JP-A-61-174915, JP-A-61-174916, etc. are known. This conventional filter cloth has a napped filter layer formed on the surface of a textile base material, which is made of ultrafine fibers with a thickness of 0.1 to 10 μm, which are mainly raised from the weft threads of the base material. This filter cloth has a thickness of 0.1 to 10μ
Since the filter layer is formed by the naps of microfine fibers, the gaps between the naps are very small, and even fine solid components can be blocked. The woven fabric that serves as the base material for the above-mentioned conventional filter cloth is
Multifilament or spun yarn made of bundles of ultrafine fibers of 0.1 to 10 μm is used as the weft, and crimped yarn with high elasticity is used as the longitudinal warp to sufficiently raise the weft. This is because when crimped yarn is used, the arranged warp yarns shrink in the width direction of the base material at the same time as the weft yarns are raised, making it easier to form a dense structure. Further, as the base fabric, a satin fabric is used because a structure in which the wefts are floating is easier to raise.

[Problems to be Solved by the Invention] However, the following problems remain in the conventional filter cloth as described above.

In filter cloth running type dehydrators and filters, the filter cloth is subjected to repeated tension and pressure.
Gradually, the crimped form of the warp threads is stretched out, permanent deformation occurs in the longitudinal direction of the filter cloth, and the length of the entire circumference of the filter cloth becomes longer, which causes the filter cloth to loosen or meander. There was a problem with unstable driving. Furthermore, if the filter cloth sag relative to the normal running path, there is a problem of damage to the filter cloth, such as when the filter cloth comes into contact with a nozzle provided for cleaning the filter cloth, damaging the filter cloth. Conventionally, in order to solve such a problem, a complicated operation was required to appropriately adjust the circumferential length of the device in accordance with the longitudinal deformation of the filter cloth. In addition, if a rubber belt with holes for phase adjustment of the filter cloth is sewn to the left and right sides of the filter cloth, even if the circumference of the device is adjusted, if the adjusted length becomes large, the rubber belt will also be stretched. The pitch of the holes varied, which caused other problems such as the rubber belt becoming disengaged from the pins that engaged the holes in the rubber belt.

Further, in the width direction of the filter cloth, since the center portion is particularly easy to deform, the amount of elongation in the center portion is greater than in both width direction portions. If this happens, the weave will curve into a U-shape in the running direction while running, and the width of the filter cloth will become smaller than the width of the device, causing the filter cloth to come off, or the rubber belts on the left and right to the part of the Nitzprol that transmits the driving force to the filter cloth. Undesirable problems such as pinching also occurred.

All of the above problems are caused by the fact that conventional filter cloths have a high elongation rate during use.
In other words, conventional filter fabrics have an elongation rate of 6 to 10%, and filter fabrics with such a high elongation rate can suffer from irreversible permanent deformation in the longitudinal direction due to repeated tension and pressure during running. It is caused by

The present invention focuses on this point, and aims to suppress the elongation rate of the filter cloth to at least 5% or less during the manufacturing stage of the filter cloth, thereby stabilizing the running of the filter cloth, The purpose is to stabilize processing performance and further stabilize the operation of the equipment.

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a filter cloth for solid-liquid separation of the present invention is a method of manufacturing a filter cloth for solid-liquid separation using synthetic fibers in which crimped yarn is used as the warp and bundles of ultrafine fibers are used as the weft. By directly raising the surface of the satin fabric base material, a filter layer consisting of a napped layer of ultrafine fibers is formed on the surface of the base material, and after the raising, applying tension in the warp direction to the base material, It consists of a method of heat-setting the base material in a state where the tension is applied.

To explain this invention in more detail, the filter cloth according to the invention has a thickness obtained by directly raising the surface of a base material made of synthetic fiber satin fabric in the warp direction, mainly by raising the wefts of the base material in the warp direction. It is covered with naps of ultrafine fibers of 0.1 to 10 μm, and the naps form a filter layer. Therefore, when it is used, it is processed into an endless piece as shown in FIG. Alternatively, it is possible to perform left and right phasing while driving. Therefore, in terms of appearance, it is no different from the conventional filter cloth described in Japanese Patent Application Laid-Open No. 59-115720 mentioned above.

The satin weave used as the base material has 50 to 500 denier crimped yarn as the warp, and multifilament or spun yarn made of ultrafine fibers with a thickness of 10 μm or less as the weft. 3~
It is preferable that the fabric has 8 raised threads, because a satin weave structure with many raised threads will allow sufficient napping.

The ultrafine fibers have a thickness of 0.1 to 10 μm, and if the thickness is larger than that, a rigid and flexible filter layer cannot be formed, and the gaps between the naps are large, resulting in a poor rejection rate for fine solids. If it is less than 0.1μ, the nape will be severely worn and stable solid-liquid separation cannot be performed.

Further, as the synthetic fiber crimped yarn for the warp, a false twisted yarn, a push type crimped yarn, a conduit type crimped yarn, etc. can be used, and elasticity is required. Considering napping properties, false twisted yarn is most preferred. In other words, if the warp yarns are crimped yarns, they will shrink in the width direction at the same time as they are raised, making it easier to create a dense structure.

The raising is performed by directly raising the surface of the base material made of synthetic fiber satin fabric using a raising machine.
In contrast to this raised yarn, the weft yarn has a single yarn thickness of 0.1 to 10 μm.
Consists of spun yarn (double yarn or triple yarn) or multifilament of ultra-fine fibers with 200 to 50,000 single yarns.
It is preferable that the yarn is a book and has a twist of 100 to 400 times/m. However, the weft is 20 to 100
The fibers are arranged in the width direction of the filter cloth at a density of threads/cm, while the warp yarns are arranged in the longitudinal direction (running direction of the filter cloth), and the weft yarns are mainly raised in the longitudinal direction of the filter cloth to form a nap filter layer. Ru. As a result of the hair being raised in the longitudinal direction, the raised hair generally lies facing in that direction,
When in use, it is stretched out so that its raised naps face in the opposite direction to the running direction of the filter cloth. The reason why the weft yarns are mainly raised is that the warp yarns are subjected to a large tension during use, and if they are raised, the strength of the filter cloth will be reduced.

Methods for forming naps on the substrate include clothing, sand paper, sand cloth, sand net, grindstone, steel brush, polishing brush, sand roll, garnet, sand honing, and the like. Among these, it is most preferable to use clothing.

After a filter layer consisting of a napped layer of ultrafine fibers is formed by raising, tension is applied to the base material in the warp direction, that is, in the longitudinal direction. This tension is such as to give the base material elongation within a certain range, as will be described later. The base material is heat-set while this tension is applied. Heat setting can be carried out directly while applying tension in the warp direction of the base material, or by impregnating a brushed filter cloth with urethane and drying it while applying tension during drying after impregnation. This is done by heat setting. In the case of this urethane impregnation, it is possible to obtain both elongation stabilization by heat fixation and structure stabilization effect by urethane adhesion.

In this way, by applying tension to align the warp yarns and heat-setting, it is possible to obtain a filter cloth that has a low permanent deformation elongation rate during use, and therefore can run stably with little deformation of the filter layer during running. can. The tension applied to the filter cloth during heat setting is preferably applied to such an extent that the base material is elongated by 7 to 3% in the longitudinal direction, and at the same time is preferably applied to such an extent that the base material is shrunk by 1 to 5% in the width direction. Moreover, the temperature of heat fixation is preferably 160 to 200°C. Urethane impregnation drying temperature is 100-130℃
is preferred. Heat setting after drying is preferably 160 to 200°C. Heat fixing under tension is not completed in one time, but in 3 times.
This may be done by repeating ~4 times.

By the above manufacturing method, a filter cloth whose elongation in the warp direction can be suppressed to 5% or less can be obtained.

Here, the elongation rate (E) is defined below.

E=L−L ₀ /L ₀ ×100 (%) E: Elongation rate (%) L ₀ : Initial length (cm) L: Loaded length (cm) The procedure for measuring the elongation rate (E) above is as follows: A filter cloth sample is taken with the warp direction of the filter cloth as the longitudinal direction and the weft direction as the width direction. The width is 3 cm, and the length (measurement part excluding the grip part) is approximately 20 cm. Hold this filter cloth sample horizontally at one longitudinal end and drop it vertically in an atmosphere with a temperature of 25±2℃ and a relative humidity of 65±5%, and apply an initial load of 80g to the bottom of the filter cloth for 3cm.
The length after 30 minutes (distance from the gripping part to the weighted part) is the initial length (L ₀ cm). Next, instead of the initial load, 12 kg is applied uniformly to a width of 3 cm, the length after 80 minutes is taken as the weighted length (Lcm), and the above elongation rate (E) is calculated.

The elongation rate defined above is preferably 5% or less, more preferably 4% or less. An endless filter cloth using a filter cloth with such a small elongation rate has high running stability and stable processing performance. By the way, if the elongation rate is 5% or less, stable running can be ensured by adjusting the circumference two or three times after the start of operation. Furthermore, if it is 4% or less, there is no need to adjust the circumferential length after the start of operation. In the above, as the synthetic fiber constituting the satin fabric, the warp is preferably polyester, and polyethylene terephthalate is particularly suitable. This has little elongation;
Moreover, since the water supply rate in water is small, dimensional changes can be made small. The weft is also preferably polyester, but is not limited thereto. For impregnation with urethane, a dimethyl formamide solution of polyurethane obtained from polyether, polyester, methylene diphenyl diisocyanate, and methylene bisaniline may be applied from the back side of the filter cloth using a gravure coater or as a polyurethane aqueous emulsion.

The filter cloth obtained by the method of this invention has a napped filter layer of ultrafine fibers, so it has high solid-liquid separation efficiency, and the elongation rate is suppressed to 5% or less, so it has high running stability and is easy to operate. Are better. Moreover, since there is little permanent deformation of the filter cloth, the processing capacity is stable. Therefore, it can be used for various solid-liquid separations. For example, sludge, scum, flocs, etc. generated during wastewater treatment, such as so-called suspended sludge discharged from activated sludge treatment equipment and so-called fixed sludge discharged from biofilm treatment equipment,
It can be used to concentrate and dehydrate wash water, concentrated sludge, etc. Specifically, sludge generated from water and sewage treatment, excess sludge generated from septic tanks, sludge generated from human waste treatment, scum generated from pressurized flotation operations, and coagulated flocs and flocculated sediment flocs generated from industrial wastewater treatment. , backwash water from various filtration devices such as sand filters, and sludge condensed in screen devices. Furthermore, it can be used to recover solid components in various manufacturing industries, such as paper pulp manufacturing, food manufacturing, sake brewing, and miso brewing. Furthermore, it can be used to purify ponds and rivers, remove algae at water purification plants, and prevent rivers and lakes from becoming contaminated during dredging.

Various types of solid-liquid separators can be used for the filter cloth manufactured by the method according to the present invention. An example is shown in FIG. In the figure, 11 is an endless filter cloth, and the filter cloth 1
1 is a drive roll 12 and a guide roll 13,1
These rolls 12, 13, 14, 15 and squeeze rolls 16, 1
7, 18, it travels and circles in the direction of arrow A on a fixed trajectory regulated by the transfer drum 19. 2
0 is the solid liquid to be treated, and vacuum suction means 2
1, the liquid component is sucked through the running filter cloth 11, and the solid component is left on the filter cloth 11 and filtered. Solid components are squeeze rolls 16, 17, 18
is pressed onto the transfer drum 19 and scraped off by the scraper 22.

In such a device, the circumferential length of the filter cloth 11 is adjusted to a predetermined tension state, for example, at the position of the guide roll 13, but there is a risk that the filter cloth 11 will stretch due to repeated tension applied to the filter cloth 11. If the elongation is large, stable running cannot be maintained unless the circumference is adjusted frequently. However, in the filter cloth 11 according to the present invention, since its elongation rate is suppressed, stable running is possible and processing performance is also stabilized.

More specific embodiments of the present invention will be described below.

Example 1 Made by spinning 18-core multicore composite fibers with polyester as the island component and polystyrene as the sea component.
The weft is a 20/2S spun yarn, and the warp is a false twisted yarn made by bundling 30 single yarns with a fineness of 5 denier.
A 5-ply satin fabric with a weft of 30 threads/cm and a warp thread of 40 threads/cm was obtained.

Next, the sea component of the weft was removed using trichlorethylene as a solvent to obtain a fabric whose weft was a bundle of ultrafine fibers with a thickness of 3 μm.

Next, the above-mentioned fabric was subjected to a napping machine, and mainly the weft yarns were raised in the warp direction to obtain a raised fabric having a filter layer with a nap count of about 1000/mm.

Next, the above-mentioned brushed fabric was heat-set at a heating temperature of 180°C at a processing speed of 8 m/min while applying tension to shrink the fabric by 3% in the width direction and stretch it by 4% in the longitudinal direction using a tenter machine to form a filter fabric. Obtained. The elongation rate of this filter cloth was measured to be 3.5%.

Next, use the filter cloth with an effective width of 1200 mm and a length of 5670 mm.
It is cut into strips and sewn together so that the warp is in the longitudinal direction, and processed into the endless filter cloth shown in Figure 1.The cloth is then passed through the belt press dehydrator shown in Figure 2 to remove excess sludge generated from activated sludge equipment at a chemical factory. The target solid-liquid separation was performed. The size of particles contained in this sludge is 1 to 80 μm, and the concentration is 10,000 μm.
mg/. The circumference of the initial device was 5740 mm, and the endless filter cloth was set in an average stretched state of 1.2%. The running speed of the filter cloth was kept constant at 20 m/min. The throughput after 720 hours of operation is:
The solid content was about 30 kg/hour, and the solid content recovery rate was about 96%. These conditions were almost the same as they were immediately after the start of operation. During this time, no meandering or sagging of the endless filter cloth was observed, and the circumferential length of the device remained at 5740 mm without being adjusted. After 720 hours, the endless filter cloth was removed and the length was measured after air drying, and the length was only 0.5%, with almost no irreversible deformation occurring.

Example 2 A filter cloth that is almost the same as Example 1, but heated at a processing speed of 8 m/min with tension applied to it in a tenter machine to shrink it by 1% in the width direction and stretch it by 2% in the longitudinal direction.
A filter cloth was obtained by heat fixing at 180°C. The elongation rate of this filter cloth was measured to be 5%.

Next, this filter cloth was processed into an endless filter cloth with the same dimensions as in Example 1, and solid-liquid separation was performed on the same surplus sludge using the same apparatus. The initial device circumference is 5740
mm, the endless filter cloth was set in an average stretched state of 1.2%. The filter cloth became slightly slack after 24 hours of operation, so the circumference was increased by 15 mm. After 48 hours, some sagging was observed, so the circumference was further increased.
Made it 15mm longer. Thereafter, no adjustment of the circumference was required until 720 hours after the start of operation. The throughput after 720 hours was approximately 29 kg/hour of solid components, and the recovery rate of solid components was approximately 94%. These remained almost the same as after the start of operation. After 720 hours, I removed the endless filter cloth and measured the length after air drying, and it was 1.5.
% longer. A small amount of irreversible deformation occurred. As described above, although the effectiveness was slightly inferior to that of Example 1, substantially satisfactory results were obtained.

Example 3 Made by spinning 18-core multicore composite fibers with polyester as the island component and polystyrene as the sea component.
The weft is a 20/2S spun yarn, and the warp is a false twisted yarn made by bundling 30 single yarns with a fineness of 5 denier.
A 5-ply satin fabric with a weft of 30 threads/cm and a warp thread of 40 threads/cm was obtained.

Next, the sea component of the weft was removed using trichlorethylene as a solvent to obtain a fabric whose weft was a bundle of ultrafine fibers with a thickness of 3 μm.

Next, the above-mentioned fabric was subjected to a napping machine, and mainly the weft yarns were raised in the warp direction to obtain a raised fabric having a filter layer with a nap count of about 1000/mm.

Next, this raised fabric was impregnated with a solution containing urethane emulsion, compressed, and then dried at 110°C under tension to increase the length by 4%, and then heat-set under hot air at 190°C. Next, the cloth was soaked in hot water in a circular device to remove excess urethane, and then dried to obtain a filter cloth. The elongation rate of this filter cloth was 3%.

As in Example 1, it was processed into an endless filter cloth with the same dimensions, and solid-liquid separation was performed on the same excess sludge using the same equipment. The processing conditions were very good, almost the same as in Example 1, and after 720 hours the processing amount was about 30 kg/hour of solid components and the recovery rate was about 96%. Further, no circumference adjustment was performed during this period.
After 720 hours had elapsed, the endless filter cloth was removed and its length after air drying was measured, and it was found that it had become longer by about 0.4%, with almost no irreversible deformation occurring.

Comparative Example For comparison, the filter cloth of Example 1 before being applied to the tenter machine was processed with an endless filter cloth.
Apply to the same belt press type dehydrator as in Example 1,
Solid-liquid separation was performed on the same surplus sludge. In other words, it is a conventional filter cloth with a high elongation rate. The effective width of the filter cloth was 1200 mm and the length was 5670 mm, the same dimensions as in Example 1. The circumference of the initial device was 5740 mm, and the endless filter cloth was set to be stretched by an average of 1.2%.
Approximately 12 hours after the start of operation at a filter cloth running speed of 20 m/min, the endless filter cloth began to sag, making it difficult to run the filter cloth stably, so the circumference was increased by 30 mm. After another 24 hours, the sag increased again, the filter cloth meandered, the holes in one rubber belt became poorly engaged with the pins, and the holes in the left and right rubber belts began to be out of phase. For this reason, the circumference was further increased by 30 mm. After another 36 hours, the endless filter cloth became sagging again, and the holes in the left and right rubber belts began to be out of phase, so the circumference was further increased by 20 mm, but the holes in the rubber belt became deformed and the pins and holes did not mesh well on both sides, causing the rubber belt to become out of phase. A crack developed from the hole, causing damage. As a result, the plant became inoperable three days after it started operating. In addition, remove this endless filter cloth and dry it naturally.
When the dimensions were measured a few days later, it had elongated by 3%, indicating a large amount of irreversible deformation.

[Effects of the Invention] In the method according to the present invention, since the warp threads of the base material are heat-set under tension,
A filter cloth with an elongation rate in the warp direction of 5% or less can be easily obtained. By keeping this elongation rate low, it is possible to stabilize the longitudinal dimension of the filter cloth during use, and it is possible to suppress irreversible permanent deformation of the filter cloth during use. Therefore, if the circumferential length is determined at the start of operation, stable running of the filter cloth can be obtained with slight or no circumferential adjustment during use. Therefore, there is no damage to the filter cloth due to sagging or meandering of the filter cloth, the life of the filter cloth can be maintained for a long time, and the device can be easily operated. Further, the treatment performance, that is, the amount of water permeation and the rejection rate of solids, do not change during operation due to permanent deformation of the filter cloth, and stable treatment performance can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing one embodiment of a filter cloth obtained by the method of the present invention, and FIG. 2 is a schematic side view of a belt press type dehydrator using the filter cloth according to the present invention. 1, 11...filter cloth, 2...rubber belt, 12...
...Drive roll, 13, 14, 15... Guide roll, 16, 17, 18... Press roll, 19...
Transfer drum, 20... solid liquid, 21... reduced pressure suction means, 22... scraper.

Claims (1)

[Claims] 1. By directly raising the surface of a satin fabric base material made of synthetic fibers with crimped yarn as warp threads and bundles of microfine fibers as weft threads, a filter layer made of a napped layer of microfine fibers is formed on the surface of the base material. 1. A method for manufacturing a filter cloth for solid-liquid separation, which comprises: forming a filter cloth, applying tension in the warp direction to the base material, and heat-setting the base material in a state where the tension is applied.