JP5955572B2 - Refractory double-layer tube and method for producing the same - Google Patents

Description

  The present invention relates to a fireproof double-layer pipe used as a drainage or ventilation pipe in a building such as an apartment house and a method for manufacturing the same.

  In buildings where many people live, such as apartment buildings and office buildings, the outer peripheral surface of the inner pipe made of synthetic resin, steel, cast iron, etc., is used as a refractory material such as mortar for piping for drainage and ventilation. A coated refractory double-layer tube is used. The fireproof double-layered pipe has a structure and fireproof performance defined by standards and administrative guidance based on the Building Standards Act and the Fire Service Act for the purpose of preventing the spread of fire to adjacent sections through piping in the event of a fire.

  In such a fireproof two-layer pipe, the material and the forming method of the coating layer are improved in order to improve not only fire resistance but also soundproofing and heat insulation (see Patent Documents 1 to 3).

  In Patent Document 1, a molding die is arranged outside a synthetic resin pipe, and a fireproof material extruded from a supply device by a screw is discharged into a gap between the outer peripheral surface of the pipe and the molding die. A method of manufacturing a refractory double-layer pipe for coating is described.

  Patent Document 2 describes a method for manufacturing an outer tube composed of a heat insulating / sound absorbing layer and a mortar layer. A heat insulating / sound absorbing material placed on an endless felt of a mortar film making apparatus is used as a metal core tube. To form a heat insulating sound absorbing layer, and then winding the mortar film made on the heat insulating sound absorbing layer to a predetermined thickness to form a mortar layer, and then pulling out the metal core tube This is an outer tube method. The manufactured outer tube is cured, and the inner tube is inserted into a fire-resistant double-layer tube. In addition, if an inner tube is used as the metal core tube in the above method, an outer tube composed of a heat insulating / sound absorbing layer and a mortar layer can be directly formed on the outer periphery of the inner tube.

  Patent Document 3 discloses a method of forming a coating layer (outer tube) having a two-layer structure by winding a non-woven fabric around the outer surface of a synthetic resin tube and then impregnating mortar only in the outer portion in the thickness direction of the non-woven fabric. Is described. According to this method, it is possible to manufacture a fireproof two-layer pipe in which the inner portion of the outer tube is a sound absorbing layer made of nonwoven fabric and the outer portion is a sound insulation / fireproof layer in which the nonwoven fabric is impregnated with mortar.

JP 2002-1712 A JP 2008-249028 A JP 2011-21617 A

  However, the above-described method for manufacturing a refractory double-layer tube has the following problems.

  The method described in Patent Document 1 needs to adjust the pressure and speed of extrusion from the supply device according to the blending and viscosity of the refractory material, and the setting is not easy. In addition, since the refractory material receives a force in a certain direction of the rotation direction of the screw of the supply device and the extrusion direction, the fiber component contained in the refractory material tends to be oriented in a specific direction. For this reason, the formed fireproof layer has a problem in strength characteristics against cracking and peeling.

  The method described in Patent Document 2 has a problem in that the mortar film making apparatus has a low degree of freedom in operation, and therefore, if a refractory double-layer pipe of another kind is to be manufactured, the manufacturing cost increases. In addition, since it is difficult to efficiently form a mortar film having a thickness of 3 mm or more, it is necessary to wind the mortar film so that the mortar film is laminated in order to form a mortar layer having a predetermined thickness. However, a step is generated in the circumferential direction at the beginning and end of winding, and the roundness is deteriorated. Moreover, since the adhesive strength between laminated mortar films is insufficient, there is a concern about delamination or dropping. Furthermore, since the fiber component in the mortar film is oriented two-dimensionally parallel to the film surface, the strength may decrease.

  The method described in Patent Document 3 can produce a fire-resistant double-layer tube with fewer steps than Patent Documents 1 and 2. However, since the mortar-impregnated layer is easily deformed so as to hang downward due to its own weight, it is difficult to form a refractory layer having a high roundness in the radial cross section of the pipe.

  In view of the above-described technical background, the present invention is intended to provide a fire-resistant double-layer pipe having a high roundness of the fire-resistant layer and hardly causing the fire-resistant layer to be peeled off or falling off, and a method for manufacturing the same.

  That is, this invention has the structure as described in following [1]-[6].

  [1] A cylindrical mesh sheet having a fireproof layer obtained by impregnating a fireproof material with a porous sheet in which a large number of pores exist three-dimensionally on the outer peripheral side of the inner tube, and the fireproof layer is stretchable A fire-resistant double-layer pipe characterized by being coated in a close contact state.

  [2] The refractory double-layer tube according to item 1 above, wherein a sound-absorbing layer is provided between the inner tube and the refractory layer.

[3] A porous sheet mounting step of mounting a porous sheet in which a large number of pores exist three-dimensionally on the outer peripheral side of the inner tube;
A mesh sheet attaching step of covering the porous sheet attached to the inner pipe with a cylindrical mesh sheet having elasticity in a close contact state;
A refractory material impregnation step of impregnating a wet refractory material into at least an outer portion in the thickness direction of the porous sheet attached to the inner pipe;
And a curing process for curing the refractory material impregnated in the porous sheet.

[4] A porous sheet mounting step of mounting a porous sheet in which a large number of pores exist three-dimensionally on the outer peripheral side of the core tube;
A mesh sheet attaching step of covering the porous sheet attached to the core tube with a cylindrical mesh sheet having elasticity in a close contact state;
A refractory material impregnation step of impregnating a wet refractory material into at least an outer portion in the thickness direction of the porous sheet attached to the core tube;
After performing a curing step of curing the refractory material impregnated in the porous sheet,
A method for producing a fire-resistant double-layer tube, wherein the core tube is extracted to form an outer tube, and the inner tube is inserted into the outer tube.

  [5] The method for producing a fire-resistant two-layer pipe according to the above item 3 or 4, wherein the mesh sheet attaching step is performed between the porous sheet attaching step and the refractory material impregnation step.

  [6] The method for producing a fire-resistant double-layered tube according to item 3 or 4, wherein the mesh sheet attaching step is performed between the fire-resistant material impregnation step and the curing step.

  According to the fireproof two-layer pipe described in [1] above, since the fireproof layer is restrained in the radial direction by the shrinkage force of the cylindrical mesh sheet, the roundness of the fireproof layer is high. In addition, since the outermost layer of the refractory double-layer pipe is a mesh sheet, and the refractory layer is protected by the mesh sheet, the refractory layer is prevented from peeling off or falling off. Further, the mesh sheet acts as a cushioning material and has an effect of preventing breakage during transportation or piping construction. Further, the mesh sheet functions as a cushioning material for the construction worker, and can prevent scratches caused by a hard fireproof layer.

  According to the fireproof double-layer tube described in [2] above, a sound absorbing effect is added to the above effect.

  According to the method for manufacturing a refractory double-layer pipe described in [3], [5] and [6] above, the porous sheet for forming the refractory layer is restrained in the radial direction by the contraction force of the cylindrical mesh sheet. Therefore, the impregnated refractory material is prevented from being deformed by its own weight, and a highly round refractory layer formed integrally with the inner tube can be formed.

  According to the method for manufacturing a fireproof double-layer tube according to the above [4], [5] and [6], the porous sheet for forming the fireproof layer in the manufacture of the outer tube is formed in the radial direction by the shrinkage force of the cylindrical mesh sheet. Therefore, the impregnated refractory material is prevented from being deformed by its own weight, and a refractory layer having high roundness can be formed.

It is the perspective view which fractured | ruptured one part of one Embodiment of the fireproof double layer pipe concerning this invention. It is the 1B-1B sectional view taken on the line in FIG. 1A. It is sectional drawing which shows other embodiment of the fireproof two-layer pipe concerning this invention.

  1A and 1B show an embodiment of a refractory double-layer pipe according to the present invention.

  The refractory double-layer pipe (1) has a refractory layer (12) in which a porous sheet is impregnated with a refractory material in close contact with the outer peripheral surface of the inner pipe (11). (13) is placed in close contact with the refractory layer (12).

  The refractory layer (12) is a layer that impregnates a refractory material with a porous sheet as a base material and holds the refractory material in the pores. This refractory layer (12) uniformly contains fibers and resin constituting the porous sheet in the refractory material, and the fibers and resin function as a reinforcing material. Therefore, the refractory layer (12) has characteristics such as high strength, excellent impact resistance and resistance to cracking.

  The refractory double-layer tube (1) can be produced by the method of the present invention. The method for producing a fire-resistant double-layered tube according to the present invention includes four steps: a porous sheet attaching step, a mesh sheet attaching step, a refractory material impregnation step, and a curing step. Below, each manufacturing process is explained in full detail, and the material which comprises a fireproof double layer pipe (1) is explained in full detail.

(1) Porous sheet mounting step A porous sheet serving as a reinforcing material for the refractory layer (2) is mounted on the outer peripheral surface of the inner tube (11). As the porous sheet, a flat sheet may be wound, or an inner tube may be inserted into a porous sheet formed in advance in a cylindrical shape, but the porous sheet is mounted so that the outer peripheral surface of the inner tube (11) is surrounded.

  The inner pipe (11) can be made of any material such as a synthetic resin pipe, a steel pipe, or a cast iron pipe. Examples of the synthetic resin pipe include thermoplastic resin pipes such as a hard polyvinyl chloride pipe (PVC pipe), a polyethylene terephthalate pipe (PET pipe), and a polypropylene pipe (PP pipe). Further, the dimensions of the inner pipe (11), and the pipe shapes such as the straight pipe, the bent pipe and the branch pipe are not limited.

  The porous sheet is a base material for impregnating a refractory material to form a refractory layer (2) and, after curing, acts as a reinforcing material for the refractory layer (2). In order to impregnate the conductive material, it is required that a large number of pores exist three-dimensionally and have a required thickness. Specifically, a nonwoven fabric (including felt) formed by binding or entanglement of fibers, or open-cell foam can be recommended. In addition, a woven fabric or a knitted fabric can be used as long as it has a required thickness and can hold a refractory material.

  Non-woven fabrics can be uniformly impregnated with refractory materials evenly because the fibers are randomly oriented, and the strength against tension and bending is three-dimensionally uniform, so they are excellent in impact resistance and hard to break. A refractory layer can be formed. The material of the fiber used as the material for the nonwoven fabric may be either organic or inorganic. Examples of organic fibers include polyester, polyethylene terephthalate (PET polyester), polyamide (6-nylon, 6,6 nylon, etc.), acrylic, polyvinyl alcohol (vinylon, etc.), polyolefin, cotton, wool, etc. it can. Examples of the inorganic fiber include glass fiber, rock wool, and ceramic fiber. Among these, inorganic fibers are preferable from the viewpoint of improving fire resistance, but it is preferable to use a nonwoven fabric made of synthetic fibers such as polyester and polypropylene from the viewpoint of cost and ease of handling. Since the fire resistance of the fire resistant layer (12) is sufficiently obtained by the fire resistant material impregnated in the nonwoven fabric, there is no inconvenience even if a nonwoven fabric made of synthetic fibers is used.

  The nonwoven fabric can be used as it is, but it is also preferable to use a felt obtained by compressing a nonwoven fabric, a needle punched nonwoven fabric or a felt. Since the shape retention is enhanced by compressing or needle punching the nonwoven fabric, the shape retention after impregnation with the refractory material is also enhanced, and as a result, the roundness of the refractory double-layer tube (1) can be increased.

  Examples of the open cell foam include urethane foam and the like, and a high-strength fire-resistant layer (12) can be formed by impregnating a fire-resistant material in the cells as in the case of the nonwoven fabric.

  Among the porous sheets, the nonwoven fabric has the most excellent reinforcing effect.

  Since the thickness of these porous sheets is approximately the thickness of the fireproof layer (12), the thickness corresponding to the required fireproof performance is used. The thickness of the porous sheet, that is, 3 to 30 mm of the refractory layer (12) is preferable. When the thickness of the porous sheet is less than 3 mm, the fire resistance is low. On the other hand, if the thickness is 30 mm, sufficient fireproof performance can be obtained, and the use of a porous sheet thicker than that results in the weight of the fireproof double-layer tube. A particularly preferred porous sheet thickness is 5 to 10 mm.

(2) Mesh sheet attaching step The porous sheet attached to the inner tube (11) is covered with a tubular mesh sheet (13) having elasticity, and is adhered to the porous sheet. Since the mesh sheet (13) has a stretchable cylindrical shape, the mesh sheet (13) can be easily put on the porous sheet when it is expanded and expanded in diameter, and when the diameter expansion force is removed, the mesh sheet (13) contracts and adheres to the porous sheet. Moreover, since it does not kink or overlap, it can be adhered to the porous sheet with a uniform pressure in the circumferential direction, and as a result, the roundness of the refractory double-layer tube can be maintained.

  The cylindrical mesh sheet (13) restrains the refractory layer (2) from the outside to assist in shape retention. Since it is a mesh sheet, it is necessary not only to have air permeability but also to have a mesh size that allows a wet refractory material to pass through, and to have elasticity and to be in close contact with the porous sheet. Therefore, the cylindrical mesh sheet (13) is also required to have a normal inner diameter smaller than the outer diameter of the porous sheet wound around the inner pipe (11). The mesh size is preferably a size that does not hinder the passage of the refractory material in the refractory material impregnation step and that can obtain a sufficient restraining force for the refractory layer, and a range of 1 to 10 mm can be recommended. Needless to say, if the mesh size is in the above range, curing is not hindered in the curing process. A particularly preferable mesh size is 1 to 5 mm.

  The mesh sheet (13) is not limited in its material and structure as long as stretchability is obtained. For example, a stretchable material made of polyester, polyethylene terephthalate (PET polyester), polyamide (6-nylon, 6,6 nylon, etc.), acrylic, polyvinyl alcohol (vinylon, etc.), polyolefin synthetic resin or rubber It may be a molded one or a non-stretchable fiber such as cotton or wool woven with the above stretchable material. In addition to the material itself having stretchability, a net-like body having stretchability in the radial direction by crossing synthetic resin filaments by extrusion molding and joining the intersections may be used. Since the cylindrical mesh sheet (13) constrains the refractory layer (12) from the radial direction, it does not require expansion and contraction in the length direction of the pipe, so that the above-described net-like body can be suitably used. Examples of the network material include high-density or low-density polyethylene, polypropylene, and ethylene-vinyl acetate copolymer (EVA). The network formed by extrusion molding does not collapse, and there is no deviation or peeling of intersections. Therefore, even if it contacts a wet refractory material, it does not deteriorate.

(3) Refractory material impregnation step The porous sheet wound around the inner pipe (11) is impregnated with a wet refractory material to form a refractory layer (12). The impregnation method of the refractory material is not limited, and examples thereof include application, injection, spraying, and immersion methods. Regardless of the impregnation method, the mesh sheet (13) has a mesh size through which the refractory material passes, and can be impregnated without any trouble. In addition, the porous sheet impregnated with a refractory material is held in shape by receiving the restraining force in the radial direction due to the shrinkage force of the mesh sheet, preventing deformation due to the weight of the uncured refractory layer (12) Is done. Moreover, since the said refractory layer (12) is restrained from the outside by the mesh sheet (13), it is in close contact with the inner tube (11). A fireproof layer (12) having a high roundness can be formed by these actions.

  From the viewpoints of strength, density, fire resistance, and the like after curing, the refractory material is normally, early strong, moderately hot and super early strong Portland cement, or a blast furnace in which fly ash or blast furnace slag is mixed with these Portland cements. Cement can be exemplified. Also, aggregates and various additives can be appropriately mixed with them. Water is mixed with these solid materials, and the porous sheet is impregnated as a wet material. The viscosity of the wet refractory material is adjusted by the mixing ratio of the solid material and water, and is appropriately set according to the material to the porous sheet, the surface density, the thickness, the penetration rate, the curing time, and the like. In general, fiber mortar in which fibers are mixed with cement is used for the purpose of improving strength. However, since the porous sheet functions as a reinforcing material in the fireproof layer (12) of the present invention, it is necessary to mix fibers. Absent. Since fiber mortar may prevent penetration into the porous sheet, it is preferable not to mix the fibers. In addition, the cylindrical mesh sheet (13) promotes the shape retention of the refractory layer (12), preventing deformation without the addition of thickeners or adhesives or by reducing the amount added. can do.

(4) Curing process The refractory material impregnated in the porous sheet is cured. The curing period is appropriately set according to the composition of the refractory material, the thickness of the refractory layer (12), the environment, and the like.

  The refractory material is cured to bring the refractory layer (12) into close contact with the inner pipe (11), and the mesh sheet (12) is also joined to the refractory layer (12) to complete the refractory double-layer pipe (1). The outermost layer of the refractory double-layer pipe (1) is a mesh sheet (13), and the refractory layer (12) is protected by the mesh sheet (13), so that the refractory layer (12) can be prevented from peeling off or falling off. . Further, the mesh sheet (13) serves as a cushioning material and has an effect of preventing breakage during transportation or piping construction. Further, the mesh sheet (13) functions as a cushioning material for the construction worker, and can prevent scratches caused by the hard fire-resistant layer (12).

  The refractory double-layer pipe of the present invention and the manufacturing method thereof are not limited to those described above.

  As shown in FIG. 2, the fireproof two-layer pipe (2) may be one in which a sound absorbing layer (14) is provided between the inner pipe (11) and the fireproof layer (12). The sound absorbing layer (14) is a layer not impregnated with a refractory material, and the material thereof is not limited. For example, a porous sheet used for the refractory layer (12) can be used as the sound absorbing material. The preferred thickness of the sound absorbing layer (14) is 1 to 30 mm. When manufacturing a fire-resistant double-layer pipe (2) having a sound-absorbing layer (14), a sound-absorbing material of the required thickness for forming the sound-absorbing layer (14) is attached to the inner pipe (11), and the fire-resistant layer ( 12) Laminate a porous sheet for formation, and then perform the steps after the mesh sheet attaching step to form the fireproof layer (12) outside the sound absorbing layer (14). If the porous sheet for forming the sound absorbing layer (14) and the fireproof layer (12) are of the same quality, the porous sheet with the total thickness attached to the inner tube (11) is attached. It is also possible to form the two layers by impregnating the refractory material only in the outer part in the thickness direction.

  In the manufacturing method of a fire-resistant two-layer pipe, the order of the mesh sheet mounting process and the fire-resistant material impregnation process described above can be switched. That is, after impregnating the porous sheet with a wet refractory material, the tubular mesh sheet (13) is covered before the curing process. Since the deformation due to the weight of the refractory material gradually occurs after the impregnation, even when the tubular mesh sheet (13) is covered after the impregnation and then cured, an effect of preventing deformation can be obtained.

  In addition, in the manufacturing process described above, if the curing process is performed from the porous sheet mounting process using a synthetic resin or metal core pipe instead of the inner pipe (11), and the core pipe is pulled out after curing, the fire resistance An outer tube made of a layer and a mesh sheet can be produced. And if an inner pipe | tube is inserted in the said outer pipe | tube, a fireproof double layer pipe | tube will be obtained. Moreover, the outer tube | pipe which consists of a sound absorption layer, a fireproof layer, and a mesh sheet can be manufactured by implementing the process after a porous sheet mounting process after attaching a sound-absorbing material to the said core pipe. Since the sound absorbing material is softer than the fireproof layer, it is easy to remove the core tube and insert the inner tube.

  An embodiment of the present invention will be described with reference to FIGS. 1A and 1B.

The materials common to the following examples and comparative examples are the inner tube (11), the porous sheet for forming the refractory layer (12), the stretchable cylindrical mesh sheet (13), and the refractory material. The inner pipe (11) used was a 2 m long nominal diameter φ100 mm rigid polyvinyl chloride pipe (PVC pipe; VP100A). As the porous sheet, PET felt (material PET; mainly 33 desynax, a mixture of several other fiber diameters, approximate thickness 6.5 mm, surface weight 120 g / m ² ) was used. As the cylindrical mesh sheet (13), a mesh body having a mesh size of 2 mm was used. The fire-resistant material is a mixture of Portland cement and sand in a proportion of 75 parts by weight (portland cement): 25 parts by weight (mixture of calcium carbonate and lightweight aggregate) based on the conditions approved by the Minister of Land, Infrastructure, Transport and Tourism. And kneaded to prepare a wet refractory material.

[Example 1]
A PET felt for forming the refractory layer (12) is wound around the outer peripheral surface of the inner tube (11) (porous sheet mounting step), and the PET mesh is covered with a cylindrical mesh sheet (13). It was made to adhere to a felt (mesh sheet attachment process). Next, a wet refractory material was sprayed and impregnated onto the PET felt covered with the cylindrical mesh sheet (13) to form a refractory layer (12) (refractory material impregnation step). Next, after curing at 30 ° C. for 24 hours, the refractory layer (12) was cured by natural curing for an additional 14 days (curing process). The fireproof double-layer pipe (1) was produced by the above process.

[Example 2]
A refractory double-layer pipe (1) was produced in the same process as in Example 1, except that the order of the mesh sheet attaching step and the refractory material impregnation step in Example 1 was changed.

[Comparative Example 1]
In the mesh sheet attachment process in Example 1, a polyester refrigeration (manufactured by Toyobo Specialty Trading Co., Ltd., product number ES3000) was wound instead of the cylindrical mesh sheet (13), and the same process as in Example 1 was performed. A laminar tube was made. The polyester cold chill is a non-stretchable plain woven fabric, and a flat sheet was wound around the outer peripheral surface of a PET felt and both ends in the circumferential direction were overlapped and temporarily bonded.

[Comparative Example 2]
A refractory double-layer tube was produced in the same process as in Example 1 except that the mesh sheet mounting process in Example 1 was not performed.

  About the fireproof double layer pipe produced by the said Example and the comparative example, the roundness of the fireproof layer, the adhesiveness of a fireproof layer and a mesh tube or a cold chill, and the surface state of the fireproof double layer pipe were evaluated on the following reference | standard. The evaluation results are shown in Table 1.

(Roundness)
Evaluation was made by the difference between the maximum diameter and the minimum diameter in the same circular cross section in the radial direction of the tube.

(Adhesion)
The floating state of the mesh tube or the cold chill from the refractory layer was visually observed, and “○” indicates that there was no lifting, and “X” indicates that the lifting occurred. The occurrence of these lifts indicates that the refractory layer is less constrained.

(Surface condition)
Visually observe the surface condition of the fireproof double-layer tube. If the surface unevenness is less than the size of the mesh sheet or chilled net, “○” indicates that the smoothness is good. Those exceeding the size of were marked with “x” because the smoothness was poor. Since the decrease in surface smoothness is due to sagging of the refractory material, the surface smoothness indicates the degree of deformation of the refractory layer.

  From Table 1, it was confirmed that by attaching a stretchable cylindrical mesh sheet to the PET felt (porous sheet), it is possible to prevent deformation of the refractory layer and to form a layer with high roundness.

  The fireproof double-layer pipe of the present invention can be suitably used as piping for buildings.

1, 2 ... Fireproof double-layer pipe
11 ... Inner pipe
12 ... Fireproof layer
13 ... Cylinder mesh sheet
14 ... Sound absorbing layer

Claims (6)

On the outer peripheral side of the inner tube, there is a fireproof layer impregnated with a fireproof material on a porous sheet in which a large number of pores exist three-dimensionally, and the fireproof layer is covered with a tubular mesh sheet having elasticity And the tubular mesh sheet is in close contact with the porous sheet .   The fireproof double-layer pipe according to claim 1, further comprising a sound absorbing layer between the inner pipe and the fireproof layer. A porous sheet mounting step of mounting a porous sheet in which a large number of pores exist three-dimensionally on the outer peripheral side of the inner tube;
A mesh sheet mounting step of covering the porous sheet mounted on the inner pipe with a tubular mesh sheet having elasticity in a close contact state and restraining the porous sheet in the radial direction by the contraction force of the cylindrical mesh sheet ;
A refractory material impregnation step of impregnating a wet refractory material into at least an outer portion in the thickness direction of the porous sheet attached to the inner pipe;
And a curing process for curing the refractory material impregnated in the porous sheet. A porous sheet mounting step of mounting a porous sheet in which a large number of pores exist three-dimensionally on the outer peripheral side of the core tube;
A mesh sheet attaching step of covering the porous sheet attached to the core tube with a tubular mesh sheet having elasticity in a close contact state, and restraining the porous sheet in the radial direction by the contraction force of the tubular mesh sheet ;
A refractory material impregnation step of impregnating a wet refractory material into at least an outer portion in the thickness direction of the porous sheet attached to the core tube;
After performing a curing step of curing the refractory material impregnated in the porous sheet,
A method for producing a fire-resistant double-layer tube, wherein the core tube is extracted to form an outer tube, and the inner tube is inserted into the outer tube.   The manufacturing method of the fireproof two-layer pipe | tube of Claim 3 or 4 which performs the said mesh sheet mounting process between a porous sheet mounting process and a refractory material impregnation process.   The manufacturing method of the fireproof two-layer pipe | tube of Claim 3 or 4 which performs the said mesh sheet mounting process between a fireproof material impregnation process and a curing process.

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