JP2005281904A - Heat-resistant cloth, pleated bag filter and method for producing heat-resistant cloth - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-resistant cloth having high dust-collection efficiency, high rigidity and high airflow quantity and especially suitable for the use under a high-temperature and high-load conditions without deteriorating the excellent properties of polytetrafluoroethylene fiber and provide a pleated bag filter and a method for producing the heat-resistant cloth. <P>SOLUTION: The heat-resistant cloth has a fluororesin fiber web having a fiber diameter of ≥20 μm and integrally laminated to both surfaces of a scrim made of metallic wires wherein at least a part of the fiber is fibrillated. The method for producing the heat-resistant cloth comprises the lamination of a fluororesin fiber web having a fiber diameter of ≥20 μm on both surfaces of a scrim made of metallic wires, the water-jet punching treatment on one surface under a maximum water pressure of 7.8-14.7 MPa and and the water-jet punching treatment on the other surface under a maximum water pressure of 17.6-24.5 MPa to integrate the layers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention is a fabric that can be used particularly favorably in a high temperature and high load environment, and has a high dust collection efficiency, and has a high heat resistance and a high air flow rate, and a pleated bag filter. The present invention also relates to a method for producing a heat resistant fabric.

  Fluororesin fiber is a fiber with excellent heat resistance and chemical resistance among synthetic fibers, so it is widely used as a bag filter for dust collection of high temperature dusty gas discharged from garbage incinerators. .

  As a bag filter fabric, there has been proposed a filter felt containing a vat in which a close blend of polytetrafluoroethylene fiber and glass fiber is needle-processed (see, for example, Patent Document 1). This Patent Document 1 proposes a method in which the bat is needle-processed and fixed to a coarse woven cloth for support, and a polytetrafluoroethylene fiber is proposed as a coarse woven cloth. However, although polytetrafluoroethylene fiber is excellent in heat resistance and chemical resistance as described above, the fiber strength is lower than that of general-purpose fibers such as polyester, and problems to be solved when used under a high load condition There were many.

  Further, a felt has been proposed in which a sheet-like material containing polytetrafluoroethylene fiber and glass fiber is hydraulically entangled with a support scrim as a fabric for a bag filter (see, for example, Patent Document 2). Patent Document 2 proposes a heat-resistant and chemical-resistant material having a low shrinkage of less than about 5% up to 200 ° C. as a supporting scrim, and in particular, a polyimide material, polytetrafluoroethylene, glass fiber, Stainless steel, polyphenylene sulfide, etc. have been proposed. However, the hydraulic entanglement can be strengthened by increasing the water pressure, but the greater the water pressure, the more serious the physical degradation of the fibers.

On the other hand, there is a method for producing a metal mesh-containing nonwoven fabric made of metal mesh, in which a felt-like plate body in which metal fibers are interlaced and a wire mesh are appropriately stacked and heated and sintered, and then these are integrally compressed to form a thin plate shape. It has been proposed (see, for example, Patent Document 3). However, in this method, it is necessary to sinter at a high temperature of 1300 ° C., which is a problem in terms of the low versatility and flexibility with respect to repeated bending.
JP-A-57-205666 JP-A-62-140615 Japanese Patent Laid-Open No. 50-18770

  In view of the background of such prior art, the present invention can be used particularly favorably in a high temperature and high load environment without impairing the excellent properties of polytetrafluoroethylene fiber, and has a dust collection efficiency. The present invention is intended to provide a heat-resistant fabric, a pleated bag filter, and a method for producing a heat-resistant fabric that is a high fabric and has both high rigidity and high air flow.

  The present invention employs the following means in order to solve such problems. That is, the heat resistant fabric of the present invention has a fluororesin fiber web having a fiber diameter of 20 μm or more laminated on both sides of a metal wire scrim, and at least a part of the fiber is fibrillated. It is characterized by being.

  Furthermore, in the method for producing such a heat-resistant fabric, after laminating a fluororesin fiber web having a fiber diameter of 20 μm or more on both surfaces of a metal wire scrim, the maximum water pressure is 7.8-14. Water jet punching is performed within a range of 7 MPa, and the other surface is integrated by water jet punching within a range of 17.6 to 24.5 MPa. is there.

  According to the present invention, a pleated bag filter having a high fabric strength and a high rigidity in addition to a low pressure loss in spite of a filter having a remarkably high collection efficiency due to a fibrillated fiber of a fluororesin fiber. Can be provided.

  The present invention is a fabric that can be used particularly favorably in a high-temperature and high-load environment without impairing the above-mentioned problems, that is, the excellent characteristics of polytetrafluoroethylene fibers, and has a high dust collection efficiency. The heat-resistant fabric having both high rigidity and high air flow was studied earnestly, a fluororesin-based fiber web was laminated and integrated on both sides of a metal wire scrim, and at least a part of the fibers constituting the web was Surprisingly, when fibrillated, it was discovered that it was possible to achieve both high collection efficiency and high rigidity. In particular, when one side of the double-sided web was integrated so as to contain more fluorinated fiber fibrils than the other side, it was found that the effect was remarkably improved. It is.

  That is, in the present invention, first, a fluororesin-based fiber web having the same single fiber fineness is laminated on both sides of a scrim made of metal wire, and water jet punching is performed on both sides to entangle and integrate them. In this case, the water pressure on one surface is punched at a higher water pressure than that on the other surface. In this way, the surface punched with high water pressure has a structure containing a large amount of the fluorinated resin fiber fibrils, and further provided with such a surface, the problem can be solved brilliantly. It was made.

  As a result, a heat-resistant fabric having a structure in which a fluororesin fiber web having a fiber diameter of 20 μm or more is laminated and integrated on both surfaces of a metal wire scrim, and at least a part of the fiber is fibrillated. Was able to provide.

  In the present invention, from the viewpoint of achieving such functions, that is, high rigidity and high collection efficiency, the heat-resistant fabric includes fluororesin fibers having a fiber diameter of 20 μm or more on both sides of a metal wire scrim. By making a laminated structure in which the web is laminated and integrated, and one surface has a web layer containing a large amount of fluororesin fiber fibrils with a fiber diameter of 1 μm or less, it has excellent heat resistance and chemical resistance for the first time. In addition, a heat resistant fabric having high rigidity and high collection efficiency can be obtained. Here, when one surface is a layer containing a large amount of fluororesin fiber fibrils having a fiber diameter of 1 μm or less, the collection efficiency is dramatically increased while the fabric strength is decreased. In the structure in which the fluororesin fiber having a fiber diameter of 20 μm or more is left in the fabric, the decrease in fabric strength is suppressed, and excessive densification is suppressed, and the air flow rate of the entire fabric can be maintained at an appropriate value. A filter with low pressure loss can be obtained. In addition, by using a metal scrim to achieve high rigidity, it was possible to achieve an effect that has excellent shape retention when processed into a pleated shape, and therefore a pleated bag filter with a large filter surface area was obtained. I was able to get it. The pleated bag filter has an advantage that a reduction in size can be achieved for the reasons described above, compared to a conventional envelope filter.

  In the heat resistant fabric of the present invention, a fluororesin fiber having a fiber diameter of 20 μm or more has a higher fiber strength than a fluororesin fiber fibril having a fiber diameter of 1 μm or less, and therefore the strength of the entire fabric can be increased. Since it can be used, it is used suitably. However, if a fluororesin fiber having a fiber diameter larger than 40 μm is used, the strength of the entire fabric can be further increased, but the density of the fabric is significantly reduced, and the collection efficiency of the entire fabric is reduced. A fluororesin fiber having a fiber diameter in the range of 20 to 40 μm is preferably used from the viewpoint of a balance between fiber strength and collection efficiency.

  Moreover, although the fluororesin fiber fibril having a fiber diameter of 1 μm or less has a function of dramatically improving the collection efficiency, the fluororesin fiber fibril having a fiber diameter of 1 μm or less is, for example, 20 μm or more. A fiber having a fiber diameter of 1 μm or less is obtained by partially dividing and branching (fibrillating) a thick fiber such as a fiber diameter of 1 μm or less.

Although it is essential to use a metal wire scrim for the heat resistant fabric of the present invention, a woven fabric having an opening in the range of 0.4 to 4.0 is preferably used as the scrim. The mesh opening is calculated by the following equation based on the number of mesh (M) wires / 2.54 cm (= inch) and fiber diameter (d) mm.
Aperture = 25.4 / Md
When the mesh opening is less than 0.4, when webs containing fluororesin fibers are laminated and integrated, webs containing fluororesin fibers arranged above and below the scrim are not strongly entangled. It is not preferable. On the other hand, when the mesh opening is larger than 4.0, the web containing the fluororesin fiber and the scrim do not sufficiently entangle, which is not preferable. As the metal wire scrim fabric, a texture such as twill weave, imitation weave, or plain weave can be used without any problem, but plain weave is preferably used.

  Furthermore, the wire diameter of the metal wire constituting the metal wire scrim is in the range of 0.1 to 0.6 mm, and the mesh of the scrim is in the range of 5 to 60 (number of wires / 2.54 cm). Those are preferably used. Use of a metal having a wire diameter of less than 0.1 mm is not preferable because the bending resistance of the metal wire scrim is lowered and the bending resistance of the heat resistant fabric is also less than 49 mN. Moreover, it is not preferable to use a metal with a metal wire diameter larger than 0.6 mm because the basis weight of the metal wire scrim becomes too high and the weight of the entire filter becomes heavy.

  When the mesh of the scrim is less than 5 wires / 2.54 cm, the tensile strength when the heat resistant fabric is used is lowered, and particularly when used as a pleated filter, the weight of the filter and the dust attached This is not preferable because it cannot withstand the weight. When the mesh of the scrim is larger than the number of 60 wires / 2.54 cm, the mesh opening of the scrim is greatly reduced, so that the webs containing fluororesin fibers arranged above and below the scrim do not sufficiently entangle with each other. It is not preferable.

  The metal wire scrim of the present invention is preferably made of SUS (stainless steel). As the material for the metal wire scrim, SUS, nickel, copper, aluminum, and the like can be used. Aluminum is less corroded by sodium hydroxide (slaked lime) than SUS, and nickel and copper are acid resistant. Since nitric acid resistance is inferior to SUS, SUS is most preferably used. When using it as a bag filter for dust collection of high temperature dust-containing gas discharged from the garbage incineration plant described in the prior art, slaked lime is generally used for the purpose of neutralizing incineration ash. Furthermore, since nitrogen oxide contained in the combustion gas may exist as a nitric acid component due to condensation, nitric acid resistance is also necessary.

  The fluororesin fiber used in the present invention is any fiber as long as 90% or more of the repeating structural units of the polymer are composed of monomers containing one or more fluorine atoms in the main chain or side chain. Although it can be used, fibers made of monomers having a large number of fluorine atoms are more preferable. For example, tetrafluoroethylene-6fluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer A combination (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), or the like can be used. As such a fluororesin fiber, it is more preferable to use polytetrafluoroethylene (PTFE) which is particularly excellent in heat resistance, chemical resistance, and low surface friction.

  Such a polytetrafluoroethylene fiber can be produced by any of the conventionally known matrix spinning method (emulsion spinning method), paste extrusion method, and split method (skive method). The matrix spinning method is a manufacturing method in which a matrix polymer such as viscose and a tetrafluoroethylene polymer are mixed to form an emulsion, which is discharged into a coagulation bath from a molding die and fiberized. This is a manufacturing method in which a paste in which a plasticizing aid such as sorben naphtha is mixed with a fluoroethylene polymer is extruded and stretched to form a fiber. The split method is a process in which a thermoformed body of tetrafluoroethylene is split into a film. This is a manufacturing method for forming fibers.

  Moreover, it is preferable that the web containing the fluororesin-type fiber of this invention consists of 50-100 wt% fluororesin type fiber. When the amount of the fluororesin fiber is less than 50 wt%, the excellent properties of the fluororesin fiber, particularly chemical resistance, do not function sufficiently, which is not preferable. Furthermore, in the heat resistant fabric of the present invention, a high collection efficiency is expressed by using a web containing a fluororesin fiber having a fiber diameter of 1 μm or less. However, when the fluororesin fiber is less than 50 wt%, Since there are few fluororesin type | system | group fibers of 1 micrometer or less, collection efficiency becomes low and is unpreferable.

The heat-resistant fabric of the present invention thus obtained is preferably used as a pleated bag filter having an air permeability of 3 to 25 cc / cm ² / sec and a bending resistance of 49 to 118 mN.

This is because when the air flow rate is less than 3 cc / cm ² / sec, the pressure loss when used as the filter increases, and the load on the blower increases, which is not preferable. Furthermore, when used as the filter, dust is collected for a certain period of time, the pressure loss of the filter rises to a specific value, and then compressed air is loaded from the clean air side of the filter, The operation to wipe off the layer is used repeatedly (hereinafter referred to as the “pulse-off pulse”). However, when the air flow rate is less than 3 cc / cm ² / sec, the initial pressure loss is high and the pulse of the drop-off It is not preferable because the time to reach the pressure loss to load is extremely short and the life is shortened. On the other hand, when the air flow rate is larger than 25 cc / cm ² / sec, the collection efficiency for collecting fine dust is lowered, which is not preferable. From the relationship between the collection efficiency and the pressure loss, it is more preferable that the heat resistance of the heat-resistant fabric is in the range of 3 to 18 cc / cm ² / sec.

  Further, when the bending resistance of the heat resistant fabric is out of the range of 49 to 118 mN, that is, when the bending resistance is less than 49 mN, the shape retention when used as a pleated bag filter is not sufficient. It is not preferable because crushing occurs in the pleats and valleys and the filtration area is reduced. In addition, when the bending resistance exceeds 118 mN, a heat-resistant fabric is likely to tear along the ridges of the pleats and valleys due to the impact of the pulsing pulse when used as a pleated bag filter. It is not preferable.

  The heat resistant fabric of the present invention can be suitably used as a pleated bag filter after being molded into a pleated shape. When used as the pleated bag filter, the surface of the web containing a large amount of fluororesin fiber fibrils having a fiber diameter of 1 μm or less is used as the air inflow surface (filtering surface), and the other web having a small amount of the fluororesin fiber fibrils is used. It is preferable to use the surface as an air discharge surface (non-filtration surface). This is because dust collection is surely performed on the surface of the filtration surface by using the surface of the web containing a large amount of fluororesin fiber fibrils having a fiber diameter of 1 μm or less as the filtration surface.

Such a heat-resistant fabric manufacturing method of the present invention is obtained by laminating a web made of an aggregate of short fibers containing 50 to 100 wt% of a fluororesin fiber on both surfaces of a metal wire scrim, and then, on one surface, a water jet The maximum water pressure of the punching process is weak and low within the range of 7.8 to 14.7 MPa, and the maximum water pressure of the water jet punching process is within the range of 17.6 to 24.5 MPa on the other surface. The method of integrating by carrying out strong and high water pressure treatment is adopted. The web comprising the aggregate of short fibers is opened and mixed with a known opener or the like short fibers containing 50 to 100 wt% fluororesin fibers, and then passed through a card machine or the like to orient the fibers. It can be the web. In order to obtain a desired web weight, the weight can be adjusted by a cross wrapper or the like. When the resulting heat resistant fabric is used as a pleated bag filter, the web weight is preferably 300 to 1000 g / m ² . A web weight of less than 300 g / m ² is not preferable because the total weight of the web is small and the collection efficiency is low. On the other hand, when the web weight exceeds 1000 g / m ² , the collection efficiency is high, but since the air flow rate is low, the pressure loss when used as a filter is high, which is not preferable.

  The maximum water pressure of the water jet punch treatment is preferably in the range of 7.8 to 14.7 MPa on one side, and in the range of 17.6 to 24.5 MPa on the other side. Preferably there is. When the maximum water pressure is less than 7.8 MPa, there is no entanglement between the web made of an aggregate of short fibers containing 50 to 100 wt% of the fluororesin fibers and the metal wire scrim, and between the laminated webs. This is not preferable because it is sufficient and may cause peeling during use. Moreover, when the water pressure exceeding the maximum water pressure of 24.5 MPa is too high, physical destruction of the fluororesin fiber occurs, and the entanglement with the metal wire scrim is lowered, which is not preferable.

  When the heat-resistant fabric obtained in such a production method is used as a pleated bag filter, the surface where the maximum water pressure in the water jet punching process is in the range of 7.8 to 14.7 MPa is the air discharge surface (non-filtering surface). It is preferable to use as the air inflow surface (filtration surface) a surface having a maximum water pressure in the range of 17.6 to 24.5 MPa. Because, in order to use as the filter, it is necessary to refine the fluororesin fiber on the air inflow surface by water jet punching so that the fiber diameter is 1 μm or less in order to improve the collection efficiency. It is preferable that the maximum water pressure is within a range of ˜24.5 MPa.

  Furthermore, in order to use it as a filter, the surface side used as the air discharge surface is minimized by reducing the strength of the fluororesin fiber due to the water jet punching process, reducing the strength, and increasing the density and reducing the air flow rate. Therefore, the maximum water pressure is more preferably in the range of 7.8 to 14.7 MPa. In order to suppress the miniaturization of the fluororesin fiber as much as possible and to sufficiently generate the entanglement between the laminated webs, it is more preferable that the maximum water pressure is in the range of 7.8 to 12.7 MPa. .

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

In addition, the measuring method of each physical property of a fabric is as follows.
[Fiber diameter of air inflow surface]
An enlarged photograph of the air inflow surface is taken at a magnification of 100 using an electron microscope. The shooting range is 0.9 mm × 1.3 mm. The photographed part is divided into 20 parts, and the minimum fiber diameter in each part is dn, and the maximum fiber diameter is Dn (n = 1 to 20). When there were 13 or more regions with dn of 1 μm or less, the average value of dn of 1 μm or less was taken as the fiber diameter of the air inflow surface. When the number of regions having a dn of 1 μm or less was 12 or less, the average value of Dn in a region larger than 1 μm was taken as the fiber diameter of the air inflow surface.
[Fiber diameter of air discharge surface]
An enlarged photo of the air discharge surface is taken at a magnification of 100 using an electron microscope. The shooting range is 0.9 mm × 1.3 mm. The photographed part is divided into 20 parts, and the minimum fiber diameter in each part is dn, and the maximum fiber diameter is Dn (n = 1 to 20). When there were 7 or more regions with Dn of 20 μm or more, the average value of Dn of 20 μm or more was taken as the fiber diameter of the air discharge surface. When the number of regions having Dn of 20 μm or more became 6 or less, the average value of dn in the region of less than 20 μm was taken as the fiber diameter of the air discharge surface.
[Fiber fibrils on the air inflow surface]
When the fibers were extracted from the air inflow surface with tweezers and the extracted fibers were branched into 5 or more, it was determined that fiber fibrils were generated. When 20 fibers are randomly extracted from the air inflow surface and fiber fibrils are formed with 10 or more fibers, it is determined that there is fiber fibrils, and fiber fibrils are generated with 9 or less fibers. It was determined that there was no fibril.
[Fiber fibrils on the air discharge surface]
Twenty fibers were randomly extracted from the air discharge surface with tweezers, and judged in the same manner as described above [Fiber fibrils on the air inflow surface].
[Unit weight]
The basis weight (mass per unit area) was measured by the method described in JIS L 1913. The sample size was 300 mm square, and three samples were measured and averaged.
[Thickness]
It was measured by the method described in JIS L 1913 A method. The measuring device is NAKAYAMA ELECTRIC IND. A compression elasticity tester manufactured by KK
[Air flow rate]
The measurement was performed based on the fragile method defined in JIS L 1096. Five measurement points were selected at random and measured.
[Bending softness]
It measured based on the Gurley method prescribed | regulated to JISL1096. The fabric was cut into a size of 63.5 mm in length and 25.4 mm in width and measured once each on the front and back sides. The measurement sample was implemented by n = 3.
[Collection efficiency]
Evaluation was carried out using a measuring device conforming to JIS B 9908 Format 3. A schematic diagram is shown in FIG. The number of particles in the range of particle size 0.3 to 0.5 μm existing in the atmosphere at normal temperature is counted with a particle counter (upstream) 1 (manufactured by Rion Co., Ltd.). Further, the air flow is passed at a filtration wind speed of 1 m / min, and the number of particles that have passed through the heat-resistant fabric 2 is also counted by the particle counter (downstream) 3 to be B. All sample volumes were evaluated at 0.01 CF (cubic feet). The collection efficiency was determined by the following equation from the obtained values.

Collection efficiency = (A−B) / A × 100
(Example 1)
Polytetrafluoroethylene short fibers (TOYOFLON (R) manufactured by Toray, 7.4 dtex × 70 mm, fiber diameter is 21 μm average, specific gravity 2.3 g / cm as a web used on the air inflow surface side and a web used on the air discharge surface side. Calculated from the fineness using ³ ). As the scrim, a 14-mesh plain weave scrim made of a metal wire made of SUS304 and having a wire diameter of 0.3 mm is used. Short fibers are passed through an opener device and a carding device to form a web having a basis weight of 340 g / m ² , and laminated in the order of the air inflow surface web / scrim / air discharge surface web and integrated by water jet punching. A heat resistant fabric was obtained. Here, the maximum water pressure of the water jet punch on the air inflow surface side was 17.6 MPa, and the maximum water pressure of the water jet punch on the air discharge surface side was 9.8 MPa. The processing speed of the water jet punching process was 1 m / min.

  There are many fluororesin fiber fibrils with a fiber diameter of 1 μm or less on the air inflow surface of the obtained heat-resistant fabric, and the air discharge surface is composed of a layer with less fibrils compared to this, and The air inflow surface and the web of the air discharge surface have a laminated structure in which the web is firmly entangled and integrated.

(Example 2)
Polytetrafluoroethylene short fiber (TOYOFLON (R) manufactured by Toray, 7.4 dtex × 70 mm, fiber diameter is 21 μm average) and glass fiber (E-type glass fiber, fiber diameter 6 μm × 57 mm) as the web used on the air inflow surface side Are used at a weight ratio of 75:25 and a basis weight of 320 g / m ² is used. The web and scrim used on the air discharge surface side were the same as in Example 1, and the heat inflow fabric was obtained by laminating in the order of the web on the air inflow surface / scrim / web on the air discharge surface and integrated by water jet punching. . Here, the water jet punch maximum water pressure on the air inflow surface side was 19.6 MPa, and the water jet punch maximum water pressure on the air discharge surface side was 7.8 MPa. The processing speed of the water jet punching process was 1 m / min.

  On the air inflow surface of the obtained heat resistant fabric, there are many fluororesin fiber fibrils having a fiber diameter of 1 μm or less, and the air discharge surface is composed of a layer with less fibrils on the air discharge surface. And the web of the air inflow surface and the web of an air discharge surface had a laminated structure where the web was firmly intertwined and integrated.

(Example 3)
A 50 mesh plain woven fabric made of a metal wire made of SUS304 and having a wire diameter of 0.1 mm is used as the scrim. The web on the air inflow surface side and the web on the air discharge surface side have the same configuration as in Example 2 and have a basis weight of 300 g / m ² , the web on the air inflow surface / the scrim / the web on the air discharge surface were laminated in this order and integrated by water jet punching to obtain a heat resistant fabric. Here, the water jet punch maximum water pressure on the air inflow surface side was 17.6 MPa, and the water jet punch maximum water pressure on the air discharge surface side was 7.8 MPa. The processing speed of the water jet punching process was 1 m / min.

  On the air inflow surface of the obtained heat resistant fabric, there are many fluororesin fiber fibrils having a fiber diameter of 1 μm or less, and the air discharge surface is composed of a layer with less fibrils on the air discharge surface. And the web of the air inflow surface and the web of an air discharge surface had a laminated structure where the web was firmly intertwined and integrated.

Example 4
As a web used on the air inflow surface side, polytetrafluoroethylene short fibers (TOYOFLON (R) manufactured by Toray, 7.4 dtex × 70 mm, fiber diameter 21 μm average) and polytetrafluoroethylene short fibers (PROFILEN (R) manufactured by Lenzing), Type 803/60, 2.7 dtex × 60 mm, average fiber diameter of 12 μm, using a specific gravity of 2.3 g / cm ³ , calculated from the fineness assuming a circular cross section) at a weight ratio of 80:20 Is used as 350 g / m ² . The web and scrim used on the air discharge surface side were the same as in Example 1, and the heat inflow fabric was obtained by laminating in the order of the web on the air inflow surface / scrim / web on the air discharge surface and integrated by water jet punching. . Here, the water jet punch maximum water pressure on the air inflow surface side was 19.6 MPa, and the water jet punch maximum water pressure on the air discharge surface side was 9.8 MPa. The processing speed of the water jet punching process was 1 m / min.

  On the air inflow surface of the obtained heat resistant fabric, there are many fluororesin fiber fibrils having a fiber diameter of 1 μm or less, and the air discharge surface is composed of a layer with less fibrils on the air discharge surface. And the web of the air inflow surface and the web of an air discharge surface had a laminated structure where the web was firmly intertwined and integrated.

(Comparative Example 1)
Polyethylene terephthalate short fiber (Toray Tetron, Type 205, 7.7 dtex × 64 mm, fiber diameter 27 μm average. Specific gravity 1.38 g / cm ³ is used as a circular cross section as the web used on the air inflow side and air discharge side. The web having a basis weight of 400 g / m ² obtained by passing through an opener device and a carding device is used. A plain woven fabric made of polytetrafluoroethylene long fibers was used as the scrim, and a slit yarn yarn 440 dtex manufactured by Gore-Tex was used as the polytetrafluoroethylene long fibers, and a 20 mesh plain woven fabric was used as the scrim. The web on the air inflow surface / scrim / web on the air discharge surface were laminated in this order and integrated by water jet punching to obtain a heat resistant fabric. Here, the water jet punch maximum water pressure on the air inflow surface side was 19.6 MPa, and the water jet punch maximum water pressure on the air discharge surface side was 9.8 MPa.

  The obtained heat-resistant fabric had low bending resistance and could not be pleated. Further, many polyethylene terephthalate fibers having a fiber diameter of 27 μm were present on the air inflow surface, and therefore the collection efficiency was low.

(Comparative Example 2)
Obtained by passing polytetrafluoroethylene short fibers (TOYOFLON (R) manufactured by Toray, 7.4 dtex × 70 mm, fiber diameter 21 μm average) through an opener and a carding device as webs used for the air inflow side and the air discharge side. A web having a weight per unit area of 350 g / m ² is used. A plain woven fabric of polytetrafluoroethylene long fibers was used as the scrim, and a slit yarn yarn 440 dtex manufactured by Gore-Tex Corporation was used as the polytetrafluoroethylene long fibers, and a 5 mesh plain woven fabric was used as the scrim. The web on the air inflow surface / scrim / web on the air discharge surface were laminated in this order and integrated by needle punching to obtain a heat resistant fabric. Needle punching was performed at a needle density of 400 needles / cm ² and a needle depth of 10 mm.

  The obtained heat-resistant fabric had low bending resistance and could not be pleated. Further, many fluororesin fibers having a fiber diameter of 21 μm were present on the air inflow surface, and the collection efficiency was low.

  As is clear from the evaluation results of Table 1, only the heat-resistant fabrics of Examples 1 to 4 have both high rigidity, high collection efficiency, and excellent pleatability.

It is the schematic of the collection efficiency evaluation apparatus used in an Example.

Explanation of symbols

1: Particle counter (upstream)
2: Heat resistant fabric 3: Particle counter (downstream)
4: Manometer (differential pressure gauge)
5: Blower (Hitachi Blower VB-007-E)
6: Flow of dust in the atmosphere 7: Flow of air from which dust in the atmosphere has been removed

Claims (13)

A heat-resistant fabric characterized in that a fluororesin fiber web having a fiber diameter of 20 μm or more is laminated and integrated on both surfaces of a metal wire scrim, and at least a part of the fiber is fibrillated. The heat resistant fabric according to claim 1, wherein the web constituting at least one surface of the heat resistant fabric contains fibrils having a fiber diameter of 1 µm or less. The heat resistant fabric according to claim 1 or 2, wherein more fibrils having a fiber diameter of 1 µm or less are contained on the other side than on one side of the heat resistant fabric. The heat-resistant fabric according to any one of claims 1 to 3, wherein the metal wire scrim is a woven fabric having an opening in the range of 0.4 to 4.0. The diameter of the metal constituting the metal wire scrim is in the range of 0.1 to 0.6 mm, and the mesh of the scrim is in the range of 5 to 60 (number of wires / 2.54 cm (= inch)). The heat resistant fabric according to any one of claims 1 to 4. The heat-resistant fabric according to any one of claims 1 to 4, wherein the metal wire scrim is made of stainless steel (SUS). The heat resistant fabric according to any one of claims 1 to 6, wherein the fluororesin fiber is a polytetrafluoroethylene fiber. The heat resistant fabric according to any one of claims 1 to 7, wherein the fluororesin-based fiber web contains 50 to 100 wt% of a fluororesin-based fiber. The heat resistance according to any one of claims 1 to 8, wherein the heat resistant fabric has air permeability of 3 to 25 cc / cm ² / sec and has a bending resistance in a range of 49 to 118 mN. Fabric. A pleated bag filter comprising a heat-resistant fabric according to any one of claims 1 to 9 pleated. After laminating a fluororesin fiber web having a fiber diameter of 20 μm or more on both sides of a metal wire scrim, one surface is subjected to a water jet punch treatment within a range of a maximum water pressure of 7.8 to 14.7 MPa, In addition, a method for producing a heat-resistant fabric, characterized in that the other surface is integrated by performing a water jet punch treatment within a range of a maximum water pressure of 17.6 to 24.5 MPa. The method for producing a heat-resistant fabric according to claim 11, wherein the fluororesin-based fiber web contains 50 to 100 wt% of a fluororesin-based fiber. The method for producing a heat resistant fabric according to claim 12, wherein the fluororesin fiber is a short fiber.

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