Mat material, exhaust gas purification device, and method for manufacturing mat material

Abstract

Provided is a mat material comprising a base material mat that has first and second main surfaces and that contains inorganic fibers, and a sheet material that is provided on the first main surface and / or the second main surface, said mat material being characterized in that the sheet material is a layered sheet in which vertically oriented fibers and transversely oriented fibers are layered, the sheet material has openings surrounded by the vertically oriented fibers and the transversely oriented fibers, and the average opening area of the sheet material is more than 0 mm2 per opening but not more than 0.7 mm2 per opening.

Description

[Technical Field]

[0001] This invention relates to a mat material, an exhaust gas purification device, and a method for manufacturing the mat material. [Background technology]

[0002] Exhaust gases emitted from internal combustion engines such as diesel engines contain particulate matter (PM), and in recent years, the harm that this PM poses to the environment and human health has become a problem. Furthermore, since exhaust gases also contain harmful gas components such as CO, HC, and NOx, there are concerns about the effects of these harmful gas components on the environment and human health.

[0003] Therefore, various exhaust gas purification devices have been proposed that collect PM in exhaust gas and purify harmful gas components, and consist of an exhaust gas treatment body made of porous ceramic such as silicon carbide or cordierite, a casing (cylindrical member) that houses the exhaust gas treatment body, and a retaining seal material disposed between the exhaust gas treatment body and the casing. The main purposes of this retaining seal material are to prevent the exhaust gas treatment body from being damaged by contact with the casing that surrounds its outer circumference due to vibrations and shocks caused by the driving of the vehicle, and to prevent exhaust gas from leaking from between the exhaust gas treatment body and the casing.

[0004] For these applications, a mat material made of inorganic fibers is used as a retaining sealant. This mat material is also used for thermal insulation and soundproofing purposes, such as wrapping it around piping in automobiles.

[0005] Patent Document 1 discloses a composite mat used by wrapping it around a small-diameter exhaust gas treatment unit (catalytic converter). The disclosed composite mat consists of inorganic fibers, a binder, and a flexible sheet attached to at least one surface of the inorganic fiber layer.

[0006] In addition, Patent Document 2 discloses a holding sealant in which a protective sheet having in-plane elongation anisotropy is installed on the surface of a mat base material.

[0007] In addition, Patent Document 3 discloses a holding sealant in which a sheet material having an opening in at least a part of the plane is installed on at least one of the first and second main surfaces of a base material.

[0008] In addition, Patent Document 4 discloses a mat material in which an oriented organic sheet is provided on the surface of a base mat. The organic sheet is formed by laminating at least two sheets of a first organic sheet and a second organic sheet, and the orientation direction of the first organic sheet is different from the orientation direction of the second organic sheet.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0010] In Patent Documents 1, 2, and 4, a sheet such as a flexible sheet is provided to prevent the mat material from cracking during winding. In addition, in Patent Document 3, the sheet material is provided to prevent the scattering of inorganic fibers contained in the base material.

[0011] As a method for manufacturing such a mat material, a method of punching with a punching die having a punching blade (also referred to as punching) has been conventionally used. In this process, a sheet-like material made of inorganic fibers and a large adhesive body with a flexible sheet attached are prepared, and by punching out this adhesive body, a large number of mat materials can be obtained in a single punching process.

[0012] The mat material has a longitudinal direction which is the direction in which it is wrapped, and a transverse longitudinal direction which is perpendicular to the longitudinal direction. When obtaining such mat material from a single large sheet of adhesive material, the method involves combining locations where the mat material is punched out in a direction where the vertical direction of the adhesive material is the longitudinal direction of the mat material, and locations where the mat material is punched out in a direction where the horizontal direction of the adhesive material is the longitudinal direction of the mat material, in order to obtain as much mat material as possible from a single large sheet of adhesive material. In this case, two types of matting materials are obtained, in which the relationship between the orientation of the adhesive body in the vertical and horizontal directions and the orientation of the matting material in the longitudinal direction is different.

[0013] In this case, if a sheet with anisotropic elongation is used, two types of mat materials can be obtained that differ in the relationship between the longitudinal orientation of the mat material and the orientation of the tensile strength of the sheet. Specifically, two types of mat materials can be obtained: a hard mat material in which the longitudinal direction of the mat material aligns with the direction of the sheet's strong tensile strength, and an easy mat material in which the longitudinal direction of the mat material aligns with the direction of the sheet's weak tensile strength.

[0014] A hard mat material is a type of mat material in which the longitudinal direction of the mat material aligns with the direction of the sheet's strongest tensile strength. Therefore, when wrapping the mat material around an exhaust gas treatment unit or the like with the longitudinal direction of the mat material as the wrapping direction, there is strong resistance due to the sheet's tensile strength, requiring considerable force to wrap. On the other hand, Easy Mat material is a type of mat material in which the longitudinal direction of the mat material and the direction of weak tensile strength of the sheet are aligned. Therefore, when wrapping the mat material around an exhaust gas treatment body or the like with the longitudinal direction of the mat material as the wrapping direction, the resistance due to the tensile strength of the sheet is weak, and no force is required for wrapping.

[0015] Mat materials are required to have a certain degree of winding ability according to their product specifications, and mat materials that do not meet the winding ability standards are considered defective. Therefore, if two types of matting materials—a hard matting material and an easy matting material—with different wrapping properties are obtained from a single large sheet of adhesive, there is a high probability that one of the matting materials will be considered defective.

[0016] For these reasons, even when obtaining two types of matting material from a single large sheet of adhesive, it is preferable to ensure that the wrapability of the two types of matting material is similar within the standard values.

[0017] Furthermore, even if a flexible sheet or similar material is provided, if the opening area of ​​the sheet is large, it may lead to cracking of the mat material when wrapping it around the exhaust gas treatment body or the like.

[0018] This invention has been made in view of the above problems, and aims to provide a mat material that has a structure that ensures stable winding properties within standard values ​​and that can suppress the occurrence of cracks during winding. [Means for solving the problem]

[0019] The mat material of the present invention comprises a base mat containing inorganic fibers and having first and second main surfaces, and a sheet material installed on at least one of the first and second main surfaces, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, the sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm². 2 / more than 0.7mm 2 It is characterized by being less than or equal to / number.

[0020] The mat material of the present invention has a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated as the sheet material, which reduces the anisotropy of the tensile strength of the sheet material, resulting in a mat material with a structure that ensures stable winding properties within the standard values.

[0021] Furthermore, in the mat material of the present invention, the sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, but the average opening area of ​​the sheet material is 0 mm 2 / more than 0.7mm 2 Since the number is less than / piece, the adhesion between the sheet material and the base mat is improved, which suppresses the occurrence of cracks when wrapping the mat material.

[0022] In the mat material of the present invention, the average opening area of ​​the sheet material is 0.7 mm². 2 If the number exceeds one, it becomes difficult to prevent cracking during the wrapping of the matting material.

[0023] In the mat material of the present invention, the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is preferably 60° or more and 120° or less. This further reduces the anisotropy of the tensile strength of the sheet material, resulting in a mat material with a more stable winding structure.

[0024] In the mat material of the present invention, the opening ratio of the sheet material is preferably greater than 0% and less than or equal to 40%. This makes it possible to more effectively suppress the occurrence of cracks when wrapping the mat material.

[0025] In the mat material of the present invention, if the opening ratio of the sheet material exceeds 40%, it may not be possible to effectively suppress the occurrence of cracks when the mat material is wrapped.

[0026] In the mat material of the present invention, it is preferable that the sheet material is composed of at least one of an organic material and an inorganic material. This makes it possible to more effectively suppress the occurrence of cracks when wrapping the mat material.

[0027] The sheet material is more preferably composed of organic matter. This makes it possible to more effectively suppress the occurrence of cracks when wrapping the mat material.

[0028] In the mat material of the present invention, the material of the sheet material is preferably polyethylene terephthalate, polyethylene, or polypropylene. This makes it possible to more effectively suppress the occurrence of cracks when wrapping the mat material.

[0029] In the mat material of the present invention, it is preferable that the base mat further contains at least one of an inorganic binder and an organic binder. When the above-mentioned base material mat contains an inorganic binder, the holding power for holding exhaust gas treatment units and the like can be improved. If the above-mentioned base material mat contains an organic binder, it is possible to prevent the scattering of inorganic fibers contained in the base material mat.

[0030] The exhaust gas purification device of the present invention comprises an exhaust gas treatment body through which exhaust gas flows, a retaining seal material used by wrapping it around the outer circumference of the exhaust gas treatment body, and a casing that houses the exhaust gas treatment body around which the retaining seal material is wrapped, wherein the retaining seal material is the mat material of the present invention.

[0031] As described above, the mat material of the present invention can suppress the occurrence of cracks during wrapping. Therefore, the exhaust gas purification device of the present invention can suppress the leakage of untreated exhaust gas from cracks in the mat material.

[0032] The present invention provides a method for manufacturing a mat material, comprising: a base mat preparation step of preparing a base mat containing inorganic fibers and having first and second main surfaces; a sheet material preparation step of preparing a sheet material; and a sheet material installation step of installing the sheet material on at least one of the first and second main surfaces of the base mat, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, the sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm².2 exceeding 0.7 mm per piece 2 and being 0.7 mm or less per piece.

[0033] In the method for manufacturing the mat material of the present invention, as the sheet material, a laminated sheet material in which longitudinal fibers and transverse fibers are laminated is used. Therefore, the anisotropy of the tensile strength of the sheet material can be reduced, and a large number of mat materials with a winding property within the standard value can be obtained from a single large-sized adherent.

[0034] Further, in the method for manufacturing the mat material of the present invention, the sheet material has openings surrounded by the longitudinal fibers and the transverse fibers, and the average opening area of the sheet material is 0 mm 2 exceeding 0.7 mm per piece 2 and being 0.7 mm or less per piece. Therefore, the sheet material can be installed in a state of being closely adhered to the base mat, and the occurrence of cracks during the winding of the mat material can be suppressed.

[0035] In the method for manufacturing the mat material of the present invention, when the average opening area of the sheet material exceeds 0.7 mm 2 per piece, it becomes difficult to suppress the occurrence of cracks during the winding of the mat material.

Brief Description of the Drawings

[0036] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a mat material. [Figure 2] FIG. 2 is an enlarged perspective view schematically showing the sheet material shown in FIG. 1. [Figure 3] FIG. 3 is a plan view of the sheet material shown in FIG. 2. [Figure 4] FIG. 4 is a side view of the sheet material shown in FIG. 2. [Figure 5] FIG. 5 is a perspective view schematically showing an example of an adherent. [Figure 6] FIG. 6 is a top view schematically showing the process of obtaining two types of mat materials by punching. [Figure 7] FIG. 7 is a cross-sectional view schematically showing an example of the exhaust gas purification device of the present invention. [Figure 8] Figure 8 is a schematic enlarged plan view showing the sheet material of Comparative Example 1. [Figure 9] Figure 9 is a photograph of the mat material of Comparative Example 2.

[0037] (Detailed description of the invention) The following describes in detail the mat material, exhaust gas purification device, and method for manufacturing the mat material of the present invention. However, the present invention is not limited to the following configurations and can be modified and applied as appropriate without changing the gist of the invention. Furthermore, a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0038] The mat material of the present invention comprises a base mat containing inorganic fibers and having first and second main surfaces, and a sheet material installed on at least one of the first and second main surfaces, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, the sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm². 2 / more than 0.7mm 2 It is characterized by being less than or equal to / number.

[0039] Figure 1 is a schematic perspective view showing an example of a mat material. The mat material 10 shown in Figure 1 has a structure in which a sheet material 30 is layered on the first main surface 21 of a base mat 20 having a first main surface 21 and a second main surface 22. Of the ends of the mat material 10 in the longitudinal direction (indicated by the double arrow L in Figure 1), a protrusion 11 is formed at one end, the first end, and a recess 12 is formed at the other end, the second end. The convex portion 11 and the concave portion 12 are formed by the overlapping of the convex portion and the concave portion provided on the base material mat 20 and the sheet material 30, respectively. The convex and concave parts of the mat material are shaped to fit together perfectly when the mat material is wrapped around a cylindrical exhaust gas purification device, exhaust gas treatment unit, or exhaust pipe. In Figure 1, the direction indicated by the double-headed arrow W is the short-side direction of the mat material, and the direction indicated by the double-headed arrow T is the thickness direction of the mat material.

[0040] Although Figure 1 shows the case where the sheet material 30 is installed only on the first main surface 21 of the base mat 20, the sheet material 30 may also be installed on both the first main surface 21 and the second main surface 22 of the base mat 20. Furthermore, in addition to the first main surface 21 and / or the second main surface 22 of the base mat 20, the sheet material 30 may also be installed on the sides of the base mat 20.

[0041] Figure 2 is a schematic enlarged perspective view of the sheet material shown in Figure 1. Figure 3 is a plan view of the sheet material shown in Figure 2. Figure 4 is a side view of the sheet material shown in Figure 2. In addition, Figures 2 to 4 show the arrangement relationship between the sheet material 30 and the base material mat 20, and therefore the base material mat 20 is also indicated by a dashed line. As shown in Figures 2 to 4, the sheet material 30 is a laminated sheet material in which longitudinally oriented fibers 31 and transversely oriented fibers 32 are laminated together. The orientation direction of the longitudinally oriented fibers 31 is longitudinal and parallel to the longitudinal direction of the mat material 10 (the direction indicated by the double-headed arrow L). The orientation direction of the transversely oriented fibers 32 is transverse, and is parallel to the short side direction of the mat material 10 (the direction indicated by the double arrow W). Figures 2 to 4 show, as an example, the case where the angle between the orientation direction of the longitudinally oriented fibers 31 and the orientation direction of the transversely oriented fibers 32 is approximately 90°. The sheet material 30 is a nonwoven fabric having fiber orientation in both the longitudinal and transverse directions, formed by laminating longitudinally oriented fibers 31 in which fibers are oriented (arranged) in the longitudinal direction and transversely oriented fibers 32 in which fibers are oriented (arranged) in the transverse direction. The sheet material 30 is manufactured using a manufacturing process that spins directly from raw materials, and the spun fibers are stretched in both the longitudinal and transverse directions, so that the long fiber filaments are uniformly oriented (arranged) in both the longitudinal and transverse directions. Furthermore, because the fibers of the sheet material 30 are arranged in a specific pattern, it has high uniformity in weight, and because there is little overlap of fibers, it has a smooth structure.

[0042] The longitudinally oriented fibers 31 and the transversely oriented fibers 32 are joined to each other. The method for joining the longitudinally oriented fibers 31 and the transversely oriented fibers 32 is not particularly limited and includes, for example, the water jet method, needle punch method, through-air method, thermal embossing method, adhesive bonding method, stitch bond method, ultrasonic sealing method, induction heating sealing method, etc.

[0043] As shown in Figures 2 and 3, the sheet material 30 is a perforated nonwoven fabric and has an opening 35 surrounded by longitudinally oriented fibers 31 and transversely oriented fibers 32. As shown in Figure 3, each opening 35 is substantially square or rectangular, demarcated by longitudinally oriented fibers 31 and transversely oriented fibers 32.

[0044] Although Figures 2 to 4 show the case where longitudinally oriented fibers 31 and transversely oriented fibers 32 are each laminated in one layer, the number of layers of longitudinally oriented fibers 31 and transversely oriented fibers 32 is not particularly limited, and longitudinally oriented fibers 31 and transversely oriented fibers 32 may be laminated alternately in a total of three or more layers. Furthermore, while Figures 2 to 4 show the case where these layers are laminated in the order of longitudinally oriented fibers 31 and transversely oriented fibers 32 from the base mat 20 side, these layers may also be laminated in the order of transversely oriented fibers 32 and longitudinally oriented fibers 31 from the base mat 20 side. The details of these configurations are described below.

[0045] The base mat constituting the mat material of the present invention is made of inorganic fibers. The inorganic fibers are not particularly limited and may be alumina-silica fibers, alumina fibers, silica fibers, etc. They may also be glass fibers or biosoluble fibers. The materials may be changed according to the properties required of the mat material, such as heat resistance and wind corrosion resistance, and it is preferable to use fibers with a large diameter and fiber length that can comply with environmental regulations in each country.

[0046] Among these, inorganic fibers with low crystalline alumina are preferred, and inorganic fibers with low crystalline alumina having a mullite composition are more preferred. In addition, inorganic fibers containing spinel-type compounds are even more preferred.

[0047] The base mat has a longitudinal direction which is the winding direction and a transverse longitudinal direction which is perpendicular to the longitudinal direction. Preferably, the base mat has a convex portion formed at one end (a first end) and a concave portion formed at the other end (a second end) along its longitudinal direction. Preferably, the convex and concave portions of the base mat are shaped to fit together precisely when the mat material is wrapped around an exhaust gas purification device, exhaust gas treatment body, or exhaust pipe with a cylindrical outer circumference. Furthermore, the base mat may have a shape that does not have any convex or concave parts.

[0048] The thickness of the above-mentioned base material mat is preferably 2 to 30 mm. If the base mat is less than 2mm thick, its thinness will reduce its thermal insulation and soundproofing performance. On the other hand, if the base mat is more than 30mm thick, its flexibility will decrease, making it difficult to attach to the target material.

[0049] The bulk density of the above-mentioned base material mat is not particularly limited, but is generally between 0.05 and 0.30 g / cm³. 3 It is preferable that this be the case. The bulk density of the base mat is 0.05 g / cm³ 3 If the density is less than 0.30 g / cm³, the inorganic fibers will not intertwine well and will easily peel off, making it difficult to maintain the shape of the base mat. On the other hand, if the bulk density of the base mat is 0.30 g / cm³, 3 Beyond a certain point, the base mat hardens, reducing its ability to attach to the component to be mounted, and making the base mat more prone to cracking.

[0050] The sheet material constituting the mat material of the present invention is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together. Therefore, the sheet material has similar properties in both the longitudinal and transverse directions and can exhibit isotropic tensile strength. As a result, the mat material of the present invention has a structure that ensures stable winding properties within the specified values. The orientation direction of longitudinally oriented fibers is determined by the direction in which the length directions of the fibers constituting longitudinally oriented fibers are aligned, and the orientation direction of longitudinally oriented fibers is determined by the direction in which the length directions of the fibers constituting transversely oriented fibers are aligned.

[0051] The fibers constituting the longitudinally oriented fibers and the transversely oriented fibers are preferably long filaments. The long fiber filament is preferably longer than the length of a normal short fiber (e.g., 10-50 mm), preferably has an average fiber length of 100 mm or more, and more preferably has an average fiber length of several hundred mm or more. The long fiber filament may also be a continuous long fiber.

[0052] The average fiber diameter of the fibers constituting the longitudinally oriented fibers and transversely oriented fibers is usually 10 μm or less, and preferably around 5 μm, in the main constituent filaments.

[0053] The sheet material has openings surrounded by longitudinally oriented fibers and transversely oriented fibers. In other words, in a plan view, the sheet material has numerous gaps where neither longitudinally oriented nor transversely oriented fibers are present. The shape of the opening in the sheet material is not particularly limited, but it is preferably substantially square or rectangular.

[0054] Furthermore, the numerous openings in the sheet material may include openings of various shapes with different forms.

[0055] If the opening in the sheet material is large, the adhesion between the sheet material and the base mat will deteriorate, and cracks may occur when wrapping the mat material. Therefore, it is preferable to keep the opening in the sheet material as small as possible. Specifically, the average opening area of ​​the sheet material is 0 mm². 2 / more than 0.7mm 2It is less than or equal to / items. This improves the adhesion between the sheet material and the base mat, thereby suppressing the occurrence of cracks when wrapping the mat material.

[0056] The average opening area of ​​the sheet material is 0.0001 mm². 2 / pcs or more, 0.5mm 2 Preferably, the number of pieces is less than or equal to 0.0001 mm. 2 / pcs or more, 0.1mm 2 It is more preferable that the number be less than or equal to 0.0001 mm. 2 / piece or more, 0.01mm 2 It is even more preferable that the number be less than or equal to / .

[0057] The average opening area of ​​the sheet material can be calculated as follows: Using a microscope, magnified photographs of the sheet material are taken. These magnified photographs are imported into any graphic drawing software, rectangles approximating each opening in the sheet material are drawn, and the area of ​​each opening is calculated by comparing these rectangles with a reference rectangle whose area is known. Then, the average value of the area of ​​all the calculated openings is taken as the average opening area of ​​the sheet material (average area per opening).

[0058] It is preferable that the sheet material has substantially the same planar shape as the base mat. That is, it is preferable that the arrangement areas of the sheet material and the base mat substantially coincide in a plan view. Furthermore, it is preferable that the sheet material is attached to the base mat. The sheet material and the base mat may be attached, for example, by using an adhesive, or by heat-pressing the sheet material itself (e.g., by heat lamination) without using an adhesive.

[0059] The basis weight of the sheet material is not particularly limited, but is 5 g / m². 2 More than 100g / m 2 Preferably, it is 5 g / m 2 More than 50g / m 2 More preferably, the following is true: 5 g / m 2 More than 30g / m2 The following is even more preferable: Note that the basis weight of the sheet material referred to here is the basis weight per sheet.

[0060] The angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is not particularly limited, but is preferably 60° or more and 120° or less, more preferably 70° or more and 110° or less, even more preferably 80° or more and 100° or less, and particularly preferably substantially 90°.

[0061] The angle between the orientation direction of longitudinally oriented fibers and the orientation direction of transversely oriented fibers can be calculated as follows. A magnified photograph of the sheet material is taken using a microscope, and the magnified photograph is imported into a graphic drawing software. Then, rectangles approximating each opening in the sheet material are drawn, and the angle of each opening is calculated to determine the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers.

[0062] The relationship between the orientation directions of the longitudinally oriented fibers and transversely oriented fibers and the longitudinal and transverse directions of the mat material is not particularly limited, but it is preferable that the orientation direction of one of the longitudinally oriented fibers and transversely oriented fibers is parallel to the longitudinal direction of the mat material, and the orientation direction of the other of the longitudinally oriented fibers and transversely oriented fibers is parallel to the transverse direction of the mat material.

[0063] The opening ratio of the sheet material is preferably greater than 0% and 40% or less, more preferably 5% or more and 30% or less, and even more preferably 10% or more and 25% or less. The opening ratio of the sheet material can be calculated by determining the area of ​​each opening using the procedure for measuring the average opening area of ​​the sheet material, and then determining the ratio (percentage) of the total area of ​​all calculated openings to the area of ​​the sheet material as depicted in the enlarged photograph.

[0064] The sheet material is preferably composed of at least one of organic and inorganic materials. For example, longitudinally oriented fibers may be composed of organic fibers and / or inorganic fibers, and transversely oriented fibers may be composed of organic fibers and / or inorganic fibers. The materials of the longitudinally oriented fibers and transversely oriented fibers may be different from each other, but usually, if the longitudinally oriented fibers are composed of organic fibers, the transversely oriented fibers are also composed of organic fibers, and if the longitudinally oriented fibers are composed of inorganic fibers, the transversely oriented fibers are also composed of inorganic fibers.

[0065] It is more preferable that the sheet material is composed of organic materials. For example, both the longitudinally oriented fibers and the transversely oriented fibers may be composed of organic fibers.

[0066] More specifically, suitable materials for the sheet include polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP).

[0067] In the mat material of the present invention, it is preferable that the base mat further contains at least one of an inorganic binder and an organic binder. The amount of inorganic binder used (weight of inorganic binder / weight of mat material) may be, for example, greater than 0 wt% and less than or equal to 15 wt%. The amount of organic binder used (weight of organic binder / weight of mat material) may be greater than 0 wt% and less than or equal to 15 wt%.

[0068] Inorganic binders such as alumina sol and silica sol can be used.

[0069] As the organic binder, it is preferable to use water-soluble organic polymers such as acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, or polyvinyl alcohol, thermoplastic resins such as styrene resin, or thermosetting resins such as epoxy resin.

[0070] Next, a method for manufacturing the mat material of the present invention will be described. The present invention provides a method for manufacturing a mat material, comprising: a base mat preparation step of preparing a base mat containing inorganic fibers and having first and second main surfaces; a sheet material preparation step of preparing a sheet material; and a sheet material installation step of installing the sheet material on at least one of the first and second main surfaces of the base mat, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, the sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm². 2 / more than 0.7mm 2 It is characterized by being less than or equal to / number.

[0071] In the method for manufacturing the mat material of the present invention, it is preferable to manufacture two types of mat material. The two types of mat material are a first mat material and a second mat material, and both mat materials are the mat material of the present invention.

[0072] In the method for manufacturing the mat material of the present invention, first, a base material mat having first and second main surfaces and a sheet material are prepared. The structure and physical properties of the base mat and sheet material prepared here are the same as those described for the mat material of the present invention, so a detailed explanation is omitted here. However, the base mat and sheet material prepared here are preferably large sheets that allow for the production of numerous mat materials of the present invention by die-cutting.

[0073] The base material mat can be obtained by various methods, but for example, it can be manufactured by papermaking or needling. In the case of papermaking, for example, it can be manufactured by the following method. Inorganic fibers are opened, and the opened inorganic fibers are dispersed in a solvent to form a mixture. The mixture is poured into a molder with a filtration mesh formed on the bottom, and the solvent in the mixture is removed through a desolvation treatment to obtain an inorganic fiber aggregate. Then, the inorganic fiber aggregate is dried to obtain a base mat. In the case of the needling method, for example, it can be manufactured by the following method. A spinning mixture made from a basic aluminum chloride aqueous solution and silica sol, etc., is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm. Subsequently, the inorganic fiber precursor is compressed to produce a continuous base mat of a predetermined size, and a base mat can be obtained by firing. Needle punching is performed either before or after this firing process to entangle the inorganic fibers.

[0074] The sheet material can be manufactured, for example, by the following method. First, the raw material (e.g., resin) is melt-spun using a nonwoven spinning apparatus such as a melt-blown nonwoven or spunbond nonwoven. Next, the fibers are arranged in the longitudinal (MD) and transverse (CD) directions and stretched to produce a longitudinally stretched web, which is a continuous body of long fiber filaments stretched longitudinally, and a transversely stretched web, which is a continuous body of long fiber filaments stretched transversely. Then, the longitudinally stretched web and the transversely stretched web are laminated and joined to produce a sheet material (laminated sheet material) in which longitudinally oriented fibers and transversely oriented fibers are laminated. As for joining the longitudinally stretched web and the transversely stretched web, as mentioned above, methods such as the water jet method, needle punch method, through-air method, thermal embossing method, adhesive bonding method, stitch bond method, ultrasonic sealing method, and induction heating sealing method can be used.

[0075] The sheet material produced in this manner has openings surrounded by longitudinally oriented fibers and transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm². 2 / more than 0.7mm 2 It is less than or equal to / items.

[0076] Next, a sheet material is placed on at least one of the first and second main surfaces of the base material mat. In this case, it is preferable to obtain the adhesive body by attaching a large sheet material to a large base material mat. This bonding may be done, for example, by using an adhesive, or by heat-pressing the sheet material itself (e.g., by heat lamination) without using an adhesive. Figure 5 is a schematic perspective view showing an example of an adhesive body. The adhesive body 150 is formed by attaching a large sheet material 130 to the first main surface 121 of a large base material mat 120, and is a rectangular sheet having two sides in the vertical direction and two sides in the horizontal direction. The sheet material 130 is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together. The orientation direction of the longitudinally oriented fibers of the sheet material 130 is longitudinal and parallel to the two longitudinal sides of the adhesive body 150, and the orientation direction of the transversely oriented fibers of the sheet material 130 is transverse and parallel to the two transverse sides of the adhesive body 150.

[0077] In the sheet material 130, the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is preferably approximately 90°, but this angle is not particularly limited. From the viewpoint of reducing the anisotropy of the tensile strength of the sheet material, it is preferable that the angle is 60° or more and 120° or less, more preferably 70° or more and 110° or less, even more preferably 80° or more and 100° or less, and particularly preferably substantially 90°.

[0078] Next, by performing a die-cutting process on the adhesive material, a mat material of a predetermined shape can be produced.

[0079] The present invention's method for manufacturing mat material uses a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together as the sheet material. This reduces the anisotropy of the tensile strength of the sheet material, making it possible to obtain a large number of mat materials with wrapability within the standard value from a single large sheet of adhesive.

[0080] Furthermore, in the manufacturing method of the mat material of the present invention, the sheet material has an opening surrounded by longitudinally oriented fibers and transversely oriented fibers, but the average opening area of ​​the sheet material is 0 mm 2 / more than 0.7mm 2Since the number of pieces is less than / unit, the sheet material can be installed in close contact with the base mat, thus suppressing the occurrence of cracks when wrapping the mat material.

[0081] In the die-cutting process for the adhesive body, it is preferable to obtain two types of mat material, the first mat material and the second mat material, by performing a process to obtain a first mat material in which the vertical direction of the adhesive body is the longitudinal direction of the mat material and the horizontal direction of the adhesive body is the longitudinal direction of the mat material and the vertical direction of the adhesive body is the short direction of the mat material.

[0082] Figure 6 is a schematic top view illustrating the process of obtaining two types of mat material by punching. The adhesive body 150 shown in Figure 6 is subjected to a punching process to obtain two types of mat materials. The left side of Figure 6 shows that a first mat material 1 is obtained in which the orientation direction of the longitudinally oriented fibers of the sheet material (the longitudinal direction shown in Figure 6) becomes the longitudinal direction of the mat material, and the orientation direction of the transversely oriented fibers of the sheet material (the transverse direction shown in Figure 6) becomes the short direction of the mat material. Furthermore, the right side of Figure 6 shows that a second mat material 2 is obtained in which the orientation direction of the transversely oriented fibers of the sheet material (the transverse direction shown in Figure 6) becomes the longitudinal direction of the mat material, and the orientation direction of the longitudinally oriented fibers of the sheet material (the longitudinal direction shown in Figure 6) becomes the short-side direction of the mat material.

[0083] In the first mat material 1 and the second mat material 2, the number and density of the sheet material fibers oriented in the longitudinal direction of the mat material (longitudinal or transverse orientation) and the sheet material fibers oriented in the short direction of the mat material (transverse or longitudinal orientation) are equivalent, resulting in nearly the same tensile strength and winding properties. In other words, the difference in winding properties between the first mat material and the second mat material is smallest, and both mat materials can be obtained as mats with winding properties within the standard values. This suggests that a large number of mat materials with wrapability within the standard values ​​can be obtained from a single large sheet of adhesive.

[0084] Furthermore, in the die-cutting process, it is preferable that the orientation direction of either the longitudinally oriented fibers or the transversely oriented fibers of the sheet material be parallel to the longitudinal direction of the first mat material and parallel to the short direction of the second mat material. Furthermore, it is preferable that the orientation direction of the longitudinally oriented fibers and the other transversely oriented fibers of the sheet material are parallel to the short-side direction of the first mat material and parallel to the long-side direction of the second mat material. The punching direction shown in Figure 6 is the direction that satisfies the above conditions.

[0085] As explained above, the method for manufacturing the mat material of the present invention yields a first mat material and a second mat material. The winding properties of the first mat material and the second mat material are influenced by both the orientation direction of the longitudinally oriented fibers of the sheet material and the orientation direction of the transversely oriented fibers of the sheet material. Because the orientation directions of longitudinally oriented fibers and transversely oriented fibers are different, these orientation directions have different effects on the wrapability of the mat material. In both the first and second mat materials, the winding properties of the mat material are not determined solely by the orientation direction of the longitudinally oriented fibers, nor solely by the orientation direction of the transversely oriented fibers. Therefore, the influence of one orientation direction on the winding properties of the mat material is mitigated. In this way, the difference in the winding properties between the first and second mat materials, which are punched in different directions, is reduced, so that the winding properties of both the first and second mat materials can be brought within the standard values.

[0086] The exhaust gas purification device of the present invention will be described below. The exhaust gas purification device of the present invention comprises an exhaust gas treatment body through which exhaust gas flows, a retaining seal material used by wrapping it around the outer circumference of the exhaust gas treatment body, and a casing that houses the exhaust gas treatment body around which the retaining seal material is wrapped, wherein the retaining seal material is the mat material of the present invention.

[0087] As described above, the mat material of the present invention can suppress the occurrence of cracks during wrapping. Therefore, the exhaust gas purification device of the present invention can suppress the leakage of untreated exhaust gas from cracks in the mat material (holding seal material).

[0088] Figure 7 is a schematic cross-sectional view showing an example of the exhaust gas purification device of the present invention. As shown in Figure 7, the exhaust gas purification device 100 of the present invention comprises a casing 50, an exhaust gas treatment unit 40 housed in the casing 50 through which exhaust gas flows, and a retaining seal material 60 disposed between the exhaust gas treatment unit 40 and the casing 50 to hold the exhaust gas treatment unit 40. The retaining seal material 60 is a mat material wrapped around the outer circumference of the exhaust gas treatment unit.

[0089] The exhaust gas treatment unit 40 is a columnar structure in which numerous cells 41 are arranged in a longitudinal direction separated by cell walls 42. One end of each cell is sealed with a sealing material 43. Furthermore, an inlet pipe for introducing exhaust gas discharged from the internal combustion engine and an outlet pipe for discharging exhaust gas that has passed through the exhaust gas purification device to the outside will be connected to the end of the casing 50 as needed.

[0090] The case in which exhaust gas passes through the exhaust gas purification device 100 having the above-described configuration will be explained below with reference to Figure 7. As shown in Figure 7, exhaust gas (in Figure 7, exhaust gas is indicated by G and the flow of exhaust gas is indicated by arrows) discharged from the internal combustion engine and flowing into the exhaust gas purification device 100 flows into one cell 41 that opens on the exhaust gas inlet end face of the exhaust gas treatment body (honeycomb filter) 40, and passes through the cell wall 42 separating the cells 41. At this time, PM in the exhaust gas is captured by the cell wall 42, and the exhaust gas is purified. The purified exhaust gas flows out from the other cell 41 that opens on the exhaust gas outlet end face and is discharged to the outside.

[0091] In the exhaust gas purification device 100 shown in Figure 7, the retaining seal material 60 is the mat material of the present invention, and at least one of the first main surface and the second main surface of the retaining seal material 60 is made of a sheet material (a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated) that constitutes the mat material of the present invention.

[0092] The material of the casing constituting the exhaust gas purification device of the present invention is not particularly limited as long as it is a heat-resistant metal, and specifically, examples include metals such as stainless steel, aluminum, and iron.

[0093] Furthermore, in addition to a roughly cylindrical shape, the casing can suitably be a clamshell shape, or have a roughly elliptical or polygonal shape in its cross-section.

[0094] In Figure 7, the exhaust gas treatment body 40 is a filter in which one end of the cell 41 is sealed with a sealing material 43. However, the exhaust gas treatment body constituting the exhaust gas purification device of the present invention does not need to have the ends of the cells sealed. Such an exhaust gas treatment body can be suitably used as a catalyst carrier.

[0095] The exhaust gas treatment body 40 may be made of a non-oxide porous ceramic such as silicon carbide or silicon nitride, or of an oxide porous ceramic such as alumina, cordierite, or mullite. Among these, silicon carbide is preferred.

[0096] The cell density in the cross-section of the exhaust gas treatment body 40 is not particularly limited, but a preferred lower limit is 31.0 cells / cm³. 2 (200 pieces / inch 2 ), the preferred upper limit is 93.0 pieces / cm 2 (600 pieces / inch 2 ) Furthermore, a more preferable lower limit is 38.8 particles / cm². 2 (250 pieces / inch 2 A more preferable upper limit is 77.5 pieces / cm². 2 (500 pieces / inch 2 )

[0097] The exhaust gas treatment unit 40 may be supported with a catalyst for purifying the exhaust gas. Preferred catalysts include precious metals such as platinum, palladium, and rhodium, with platinum being the most preferred. Other catalysts that can be used include alkali metals such as potassium and sodium, and alkaline earth metals such as barium. These catalysts may be used individually or in combination of two or more. When these catalysts are supported, PM (particulate matter) can be more easily burned off, and toxic exhaust gases can also be purified.

[0098] (Examples) The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0099] (Example 1) The papermaking method results in a basis weight (weight of fibers per unit area) of 2400 g / m². 2 A large-format base mat made of inorganic fibers (mullite fibers) was fabricated. As a large-format sheet material, a laminated sheet material (nonwoven fabric) with fiber orientation in both the longitudinal and transverse directions was prepared, consisting of longitudinally oriented PET fibers and transversely oriented PET fibers. This material has orientation in the direction of the alignment of the lengthwise direction of the PET fibers, and the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is approximately 90°. Furthermore, this sheet material has substantially square or rectangular openings. In addition, this sheet material has a weighing capacity of 10 g / m². 2 That is the case.

[0100] The base mat and the sheet material were heat-pressed together to obtain a rectangular adhesive body similar to the adhesive body schematically shown in Figure 5. Then, the adhesive material was punched out in the same manner as schematically shown in Figure 6 to obtain two types of mat material (the first mat material and the second mat material). In the first mat material, the orientation direction of the longitudinally oriented fibers of the sheet material is parallel to the longitudinal direction of the mat material, while in the second mat material, the orientation direction of the transversely oriented fibers of the sheet material is parallel to the longitudinal direction of the mat material.

[0101] (Comparative Example 1) A large-format base mat was prepared in the same manner as in Example 1. A nonwoven fabric with randomly oriented PET fibers was prepared as a large-format sheet material. However, the direction in which the PET fibers are aligned along their length is the longitudinal direction (MD), and the fibers have a gentle orientation in that direction. Furthermore, this sheet material has openings of random shapes, such as parallelograms. A base mat and a sheet material were heat-pressed together to obtain a rectangular adhesive body having two sides in the vertical direction and two sides in the horizontal direction. Then, the adhesive body was punched out in the same manner as in Example 1 to obtain two types of mat material (a first mat material and a second mat material). In the first mat material, the length direction of the PET fibers in the sheet material is parallel to the longitudinal direction of the mat material, while in the second mat material, the length direction of the PET fibers in the sheet material is parallel to the short direction of the mat material. Figure 8 is a schematic enlarged plan view showing the sheet material of Comparative Example 1. The sheet material 30' of Comparative Example 1 has longitudinally oriented fibers 31 but no transversely oriented fibers. The opening 35 is formed by being surrounded by the longitudinally oriented fibers 31.

[0102] (Comparative Example 2) A large-format base mat was prepared in the same manner as in Example 1. As a large-format sheet material, a longitudinal web with longitudinal fiber orientation was prepared by splitting a polyolefin film stretched in the longitudinal direction, and a transverse web with transverse fiber orientation was prepared by splitting a polyolefin film stretched in the transverse direction, and these layers were laminated and heat-sealed together. This sheet material has substantially square or rectangular openings. A base mat and a sheet material were heat-pressed together to obtain a rectangular adhesive body having two sides in the vertical direction and two sides in the horizontal direction. Then, the adhesive body was punched out in the same manner as in Example 1 to obtain two types of mat material (a first mat material and a second mat material). In the first mat material, the orientation direction of the vertical web of the sheet material (vertical direction) is parallel to the longitudinal direction of the mat material, and in the second mat material, the orientation direction of the horizontal web of the sheet material (horizontal direction) is parallel to the longitudinal direction of the mat material.

[0103] (Measurement of average aperture area and aperture ratio) Magnified photographs of the sheet materials used in Example 1 and Comparative Example 2 were taken using a microscope. The enlarged photographs were imported into a drawing software, rectangles approximating each opening in the sheet material were drawn, and the area of ​​each opening was calculated by comparing these rectangles with a reference rectangle whose area was known. Then, the average of the calculated opening areas was used as the average opening area of ​​the sheet material (average area per opening). Furthermore, the ratio (percentage) of the total area of ​​all calculated openings to the area of ​​the sheet material in the enlarged photograph was defined as the opening ratio. The results are shown in Table 1.

[0104] (Wrapping test) A cylindrical base with a diameter of φ200 mm was wrapped with two types of matting materials (the first matting material and the second matting material) manufactured in each example and comparative example. When wrapping, the base material mat was placed on the base side, and the sheet material was placed on the outside. The total length of the mat material in the longitudinal direction (mat dimensions) when wrapped, and the gap between the convex and concave parts at the point where the convex and concave parts fit together (seam gap), were measured. The total length of each of the two types of matting materials was measured, and the difference (difference between the first and second matting materials) was calculated. The results are shown in Table 1. The ○ in the difference indicates good, and × indicates poor. The smaller the difference between the first and second mat materials, the more homogeneous the resulting mat material will be.

[0105] (Presence or absence of cracks in the mat material) For each example and comparative example, the two types of mat materials produced were checked for the occurrence of cracks after the above-mentioned wrapping test. The results are shown in Table 1. A circle (○) indicates no cracks, while a cross (×) indicates cracks.

[0106] [Table 1]

[0107] These results show that using a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are layered reduces the difference in the total length of the mat dimensions and seam gap between the first and second mat materials. This means that two types of matting materials with similar wrapping properties can be obtained, and that a large number of matting materials with good wrapping properties can be obtained from a single large sheet of adhesive. Furthermore, the average opening area of ​​the sheet material is set to 0 mm². 2 / more than 0.7mm 2 It can be seen that by keeping the number of pieces to less than / unit, it is possible to prevent cracking during the wrapping of the matting material. Figure 9 is a photograph of the mat material of Comparative Example 2. As shown in Figure 9, the mat material of Comparative Example 2 developed cracks in the area enclosed by the dashed line after the wrapping test. [Explanation of symbols]

[0108] 1. First mat material 2. Second mat material 10 Mat material 11 Convex part 12 recesses 20, 120 base material mat 21, 121 First main surface of the substrate mat 22 Second main surface of the base material mat 30, 130 sheet material 31 Longitudinal oriented fibers 32 Transversely oriented fibers 35 Aperture 40 Exhaust gas treatment unit 41 cells 42 Cell Wall 43 Sealing material 50 Casing 60 Retaining seal material 100 Exhaust gas purification device 150 adhesive pieces

Claims

1. A base mat containing inorganic fibers and having first and second main surfaces, A sheet material installed on at least one of the first and second main surfaces, A mat material having, The aforementioned sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together. The sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, The average opening area of ​​the sheet material is 0.0001 mm² / piece or more and 0.01 mm² / piece or less. The angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is 60° or more and 120° or less. The mat material is characterized in that the opening ratio of the sheet material is greater than 0% and less than or equal to 40%.

2. The mat material according to claim 1, wherein the sheet material is composed of at least one of an organic material and an inorganic material.

3. The mat material according to claim 2, wherein the sheet material is composed of organic material.

4. The mat material according to claim 1 or 2, wherein the material of the sheet material is polyethylene terephthalate, polyethylene, or polypropylene.

5. The mat material according to claim 1 or 2, wherein the base material mat further comprises at least one of an inorganic binder and an organic binder.

6. Exhaust gas treatment unit through which exhaust gas flows, A retaining seal material used by being wrapped around the outer circumference of the exhaust gas treatment body, A casing that houses the exhaust gas treatment unit around which the retaining seal material is wrapped, An exhaust gas purification device comprising, The exhaust gas purification device is characterized in that the retaining seal material is the mat material described in claim 1 or 2.

7. A base material mat preparation step of preparing a base material mat containing inorganic fibers and having first and second main surfaces, The sheet material preparation process involves preparing the sheet material, A sheet material installation step of installing the sheet material on at least one of the first and second main surfaces of the base material mat, A method for manufacturing a mat material having the following characteristics: The aforementioned sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together. The sheet material has an opening surrounded by the longitudinally oriented fibers and the transversely oriented fibers, The average opening area of ​​the sheet material is 0.0001 mm² / piece or more and 0.01 mm² / piece or less. The angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is 60° or more and 120° or less. A method for manufacturing a mat material, characterized in that the opening ratio of the sheet material is greater than 0% and less than or equal to 40%.

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