Mat material, winding body, and exhaust gas purification device

Abstract

Provided is a mat material resistant to peeling when wound around a wound body. This mat material comprises inorganic fibers and a binder, and has a first main surface and a second main surface opposite the first main surface. The mat material is characterized in that: a first needle intrusion mark is formed on the first main surface of the mat material; a first needle exit mark is formed on the second main surface of the mat material; a first needle mark in which a plurality of the inorganic fibers are entangled is formed in the mat material from the first needle intrusion mark to the first needle exit mark; in the first needle exit mark, the plurality of inorganic fibers form a closed loop shape and a return part protruding from the second main surface is formed; and the ratio of the diameter of the return part to the diameter of the first needle mark ([the diameter of the return part] / [the diameter of the first needle mark]) exceeds 1.5.

Description

Mat material, wrapping body, and exhaust gas purification device

[0001] This invention relates to a mat material, a winding body, and an exhaust gas purification device.

[0002] Exhaust gases emitted from internal combustion engines such as diesel engines contain particulate matter (PM), and in recent years, the harm that PM causes 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 that houses the exhaust gas treatment body, and a retaining seal material (mat material) disposed between the exhaust gas treatment body and the casing. The main purposes of this retaining seal material (mat 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] As such a mat material, a needling mat is known, which is made by compressing an alumina fiber precursor, which is converted into inorganic fibers by firing, to create a sheet; inserting and removing needles with multiple barbs in the thickness direction of the sheet to create a needling sheet in which entangled parts are formed; and firing the needling sheet.

[0005] For example, Patent Document 1 discloses a method for manufacturing such a needling mat, comprising: preparing a sheet having a first main surface and a second main surface located opposite the first main surface, wherein inorganic fiber precursors that are converted into inorganic fibers by firing are intertwined with each other; producing a needling sheet by passing a needle through the sheet; and firing the needling sheet, wherein the sheet consists of at least two small sheets: a first sheet occupying a certain range in the thickness direction of the sheet from the first main surface, and a second sheet adjacent to the first sheet; the first sheet contains a first long fiber precursor; the second sheet contains a short fiber precursor with an average fiber length shorter than the first long fiber precursor; and in the needling step, the needle is passed from the first main surface side toward the second main surface side.

[0006] Japanese Patent Publication No. 2011-236526

[0007] When manufacturing an exhaust gas purification device using the needling mat described in Patent Document 1, the surface of the needling mat placed on the outer periphery sometimes tears and peels off from the edges.

[0008] This invention was made to solve the above problems, and the object of this invention is to provide a mat material that is less prone to peeling when wrapped around an object to be wound.

[0009] As a result of diligent research, the inventors of the present invention have found that by adjusting the size of the closed-loop return portion of the inorganic fibers that forms on the main surface of the mat material during needling, and by positioning the main surface of the mat material on which the closed-loop return portion is formed toward the outer periphery, delamination of the mat material becomes less likely, thus completing the present invention.

[0010] In other words, the mat material of the present invention comprises inorganic fibers and a binder, and has a first main surface and a second main surface opposite the first main surface, wherein a first needle penetration mark is formed on the first main surface of the mat material, a first needle exit mark is formed on the second main surface of the mat material, a first needle mark is formed in the mat material from the first needle penetration mark to the first needle exit mark in which a plurality of inorganic fibers are intertwined, in the first needle exit mark a plurality of inorganic fibers form a closed loop, and a return portion is formed that protrudes from the second main surface, and the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) is greater than 1.5.

[0011] In manufacturing the mat material of the present invention, an inorganic fiber precursor to be converted into inorganic fibers is compressed to produce a sheet, and a needle with multiple barbs is inserted and removed in the thickness direction of the sheet. When the needle is inserted and removed so as to penetrate the sheet, some of the inorganic fiber precursor is pushed out by the needle and protrudes from the main surface on the side where the needle penetrates. Some of the inorganic fiber precursor that is pushed out in this way is not cut by the needle and becomes a loop-shaped barb. The sheet is then fired, and the inorganic fiber precursor that has formed the loop-shaped barb is fired into inorganic fibers while maintaining its shape. In the mat material of the present invention, such a loop-shaped barb is formed on the second main surface.

[0012] The mat material of the present invention is used by being wrapped around a body to be wound. In this case, the mat material of the present invention is wrapped so that the first main surface is in contact with the body to be wound. When the mat material of the present invention is wrapped in this manner, the first main surface becomes the inner circumference and the second main surface becomes the outer circumference. If a return portion is written on the second main surface which becomes the outer circumference, the loop-shaped return portion acts as support near the second main surface, preventing delamination from occurring near the second main surface. In particular, this effect is more pronounced when the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) exceeds 1.5. Therefore, when the mat material of the present invention is wrapped around a body to be wound, delamination of the mat material of the present invention is less likely to occur.

[0013] In the mat material of the present invention, when the mat material is divided into three equal parts in the thickness direction, into a first main surface side portion to which the first main surface belongs, a second main surface side portion to which the second main surface belongs, and a central portion sandwiched between the first main surface side portion and the second main surface side portion, it is preferable that the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the central portion, and that the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the second main surface side portion. Furthermore, in the mat material of the present invention, it is more preferable that the weight ratio of the binder contained in the first main surface side portion is greater than the weight ratio of the binder contained in the central portion, and that the weight ratio of the binder contained in the first main surface side portion is greater than the weight ratio of the binder contained in the second main surface side portion. Furthermore, in the mat material of the present invention, it is preferable that the weight ratio of the binder contained in the second main surface portion is less than or equal to the weight ratio of the binder contained in the central portion.

[0014] In manufacturing the mat material of the present invention, a solvent containing a binder is impregnated onto the mat material, and then processes such as suction, compression, heating, and drying are carried out. One example of drying is drying by applying hot air. In this process, the binder may be unevenly distributed downwards due to gravity, or may be concentrated on the main surface to which the hot air is applied. As a result, the manufactured mat material will have a gradient in the weight ratio of the binder in the thickness direction.

[0015] In such cases, the weight proportion of the binder increases near one main surface of the mat material. The inorganic fibers near the main surface on the side with a high weight proportion of the binder are firmly fixed by the binder, so the flexibility of the main surface on the side with a high weight proportion of the binder tends to decrease. When the mat material is wrapped around the body to be wound, the difference between the inner and outer circumferences of the mat material makes the main surface on the outer circumference side of the mat material susceptible to circumferential stress. Therefore, if the mat material is wrapped around the body to be wound so that the main surface on the side with a high weight proportion of the binder is on the outer circumference side, cracks are more likely to occur on the main surface on the side with a high weight proportion of the binder. Conversely, if the mat material is wrapped around the body to be wound so that the main surface on the side with a low weight proportion of the binder is on the outer circumference side, cracks are less likely to occur on the main surface on the side with a low weight proportion of the binder. As described above, the mat material of the present invention is wrapped around the body to be wound so that the first main surface is on the inner circumference and the second main surface is on the outer circumference. Therefore, by manufacturing the mat material of the present invention such that the weight ratio of the binder on the second main surface side is low, it is possible to prevent cracks from occurring on the second main surface which forms the outer periphery.

[0016] In the mat material of the present invention, the binder is preferably an organic binder and / or an inorganic binder. Organic binders and inorganic binders are useful binders for molding the mat material.

[0017] In the mat material of the present invention, the binder comprises an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, and it is preferable that the inorganic particles are dispersed in the polymer resin. In such a mat material, the binding of inorganic fibers by the binder becomes stronger, which prevents inorganic fibers from scattering from the mat material and also increases the strength of the mat material.

[0018] In the mat material of the present invention, the first needle marks may have a twisted shape. The twisted shape of the first needle marks indicates that the inorganic fibers constituting the first needle marks are strongly intertwined, causing distortion. When the first needle marks have a twisted shape, the intertwining of the inorganic fibers is less likely to break even if stress is applied to the first needle marks. Therefore, the first needle marks become stronger. In other words, even if outward stress in the thickness direction is applied to the mat material, the first needle marks are less likely to tear. Consequently, the effect of preventing delamination near the second main surface is further enhanced.

[0019] In the mat material of the present invention, it is preferable that a second needle penetration mark is formed on the second main surface of the mat material, a second needle exit mark is formed on the first main surface of the mat material, and a second needle mark is formed in the mat material from the second needle penetration mark to the second needle exit mark, in which a plurality of inorganic fibers are intertwined. In such a mat material, the needledling process is performed so that needles penetrate from the first main surface toward the second main surface and needles penetrate from the second main surface toward the first main surface. As a result, the plurality of inorganic fibers constituting the mat material become more intertwined, and the elasticity and strength of the mat material are improved.

[0020] The winding body of the present invention is a winding body comprising a body to be wound and a mat material wound around the body to be wound, wherein the mat material is the mat material of the present invention, and the mat material is wound around the body to be wound such that the first main surface of the mat material is in contact with the body to be wound.

[0021] In such a wrapped body, the first main surface of the mat material of the present invention is in contact with the wrapped body, so as described above, it is possible to prevent delamination of the mat material.

[0022] In the winding body of the present invention, the winding body is preferably an exhaust gas treatment body. By housing such a winding body in a metal casing, an exhaust gas purification device can be manufactured.

[0023] The exhaust gas purification device of the present invention includes an exhaust gas treatment body, a metal casing that houses the exhaust gas treatment body, and a mat material that is disposed between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body. The mat material is the mat material of the present invention, and the mat material is arranged such that the first main surface of the mat material contacts the exhaust gas treatment body.

[0024] In such an exhaust gas purification device, since the first main surface of the mat material of the present invention contacts the exhaust gas treatment body, as described above, it is possible to prevent the mat material from peeling. Therefore, it is possible to prevent the exhaust gas treatment body from falling out due to gas pressure or the like, and to prevent exhaust gas from leaking from the peeled portion of the mat material.

[0025] According to the present invention, it is possible to provide a mat material that is less likely to peel when wound around a wound body.

[0026] FIG. 1 is a perspective view schematically showing an example of the mat material of the present invention. FIG. 2 is a cross-sectional view taken along line A-A of the mat material of the present invention shown in FIG. 1. FIG. 3A is a schematic diagram explaining the principle of forming a return portion in the mat material of the present invention. FIG. 3B is a schematic diagram explaining the principle of forming a return portion in the mat material of the present invention. FIG. 3C is a schematic diagram explaining the principle of forming a return portion in the mat material of the present invention. FIG. 4 is a schematic diagram of an example of a first needle mark taken out from the mat material of the present invention. FIG. 5 is a cross-sectional view of the mat material schematically showing the first main surface side portion, the central portion, and the second main surface side portion of the mat material of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of the exhaust gas purification device of the present invention. FIG. 7 is a perspective view schematically showing an example of the wound body of the present invention. FIG. 8 is a photograph of a fiber bundle derived from the first needle mark included in the mat material according to Example 1.

[0027] Hereinafter, the mat material of the present invention will be specifically described. However, the present invention is not limited to the following configurations, and can be appropriately changed and applied within the scope of not changing the gist of the present invention. In addition, a combination of two or more of the individual preferred configurations of the present invention described below is also the present invention.

[0028] The mat material according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing an example of the mat material of the present invention. As shown in FIG. 1, the mat material 10 includes inorganic fibers and a binder, and has a first main surface 11 and a second main surface 12 facing the first main surface 11. It is a mat material rectangular in plan view.

[0029] As shown in FIG. 1, the mat material 10 is provided with a convex portion 13a at one end portion 13 and a concave portion 14a at the other end portion 14.

[0030] Although it will be described in detail later, the mat material 10 is wound around an exhaust gas treatment body and disposed in an exhaust gas purification device. At this time, the mat material 10 is wound so that the first main surface 11 contacts the exhaust gas treatment body. The convex portion 13a and the concave portion 14a are shaped to fit exactly when the mat material 10 is wound around the exhaust gas treatment body. When such convex portions 13a and concave portions 14a are provided, the sealing property is improved when the mat material 10 is disposed in the exhaust gas purification device described later.

[0031] The mat material 10 is a mat material subjected to needle punching treatment. The needle punching treatment is to compress an inorganic fiber precursor to be converted into inorganic fibers to produce a sheet, and to produce a needle punching sheet in which an entanglement portion is formed by inserting and removing needles having a plurality of barbs (returns) in the thickness direction of the sheet. By firing such a needle punching sheet, a mat material subjected to needle punching treatment is obtained. By performing the needle punching treatment, the inorganic fibers are entangled and the strength of the mat material is improved.

[0032] Since the mat material 10 is a mat material subjected to needle punching treatment, needle marks are formed. This needle mark will be described in detail with reference to the drawings. FIG. 2 is a cross-sectional view taken along the line A - A of the mat material of the present invention shown in FIG. 1.

[0033] As shown in Figures 1 and 2, a first needle penetration mark 21 is formed on the first main surface 11 of the mat material 10, and a first needle exit mark 22 is formed on the second main surface 12 of the mat material 10. In addition, a first needle mark 20, in which multiple inorganic fibers are intertwined, is formed on the mat material 10 from the first needle penetration mark 21 to the first needle exit mark 22.

[0034] In the mat material 10, at the first needle penetration marks 22, multiple inorganic fibers form a closed loop, creating a return portion 23 that protrudes from the second main surface 12.

[0035] The principle by which the return portion 23 is formed in the mat material 10 will now be explained. Figures 3A to 3C are schematic diagrams illustrating the principle by which the return portion is formed in the mat material of the present invention. For convenience, in Figures 3A to 3C, the first main surface is shown at the top and the second main surface at the bottom. In other words, the positional relationship between the first main surface and the second main surface in Figures 1 and 2 is inverted vertically.

[0036] As shown in Figure 3A, when manufacturing the mat material, an inorganic fiber precursor 30a, which is converted into inorganic fibers, is compressed to produce a sheet 10a, and a needle 40, which has multiple barbs 41 formed on it, is passed through the sheet 10a in the thickness direction (the direction from the first main surface 11a to the second main surface 12a, as indicated by the arrow in Figure 3A).

[0037] As shown in Figure 3B, when the needle 40 is inserted and removed so as to penetrate the sheet 10a, some of the inorganic fiber precursor 30a is pushed out by the needle 40 and protrudes from the second main surface 12a on the penetrating side of the needle 40 (in Figure 3B, the protruding portion is indicated by the symbol "23a").

[0038] Subsequently, as shown in Figure 3C, the needle 40 is withdrawn from the sheet 10a, but a portion of the inorganic fiber precursor 30a that has been pushed out toward the second main surface 12a is not cut by the needle 40 and becomes a loop-shaped return portion 23a.

[0039] Subsequently, the sheet 10a is fired, and the inorganic fiber precursor 30a, which forms the loop-shaped return portion 23a, is fired into inorganic fibers while maintaining its shape, thus becoming the loop-shaped return portion.

[0040] The mat material 10 is wrapped around the exhaust gas treatment body such that the first main surface 11 becomes the inner circumference and the second main surface 12 becomes the outer circumference. If a return portion 23 is provided on the second main surface 12 side which is the outer circumference, the loop-shaped return portion 23 will provide support near the second main surface 12, preventing peeling from occurring near the second main surface 12.

[0041] Furthermore, in the mat material 10, the ratio of the diameter of the return portion 23 to the diameter of the first needle mark 20 ([diameter of return portion] / [diameter of first needle mark]) is greater than 1.5. Preferably, this ratio ([diameter of return portion] / [diameter of first needle mark]) is greater than 2.0. Also, preferably, this ratio ([diameter of return portion] / [diameter of first needle mark]) is 6.0 or less, and more preferably 5.5 or less. When this ratio ([diameter of return portion] / [diameter of first needle mark]) exceeds 1.5, the loop-shaped return portion 23 acts as a support, and the effect of preventing peeling near the second main surface 12 is more pronounced. In other words, when the mat material 10 is wrapped around the exhaust gas treatment body, peeling is less likely to occur in the mat material 10.

[0042] In this specification, "diameter of the first needle mark" and "diameter of the return portion" refer to values ​​calculated as follows. Figure 4 is a schematic diagram of an example of a fiber bundle derived from the first needle mark extracted from the mat material of the present invention. In the first needle mark contained in the mat material of the present invention, the inorganic fibers are more strongly intertwined with each other than in other parts, so by loosening the mat material of the present invention, a fiber bundle derived from the first needle mark can be extracted. As shown in Figure 4, the fiber bundle 25 extracted from the mat material consists of a shaft portion 20' and a return portion 23' formed at one end of the shaft portion 20'. When measuring the "diameter of the first needle mark" and the "diameter of the return portion", any five fiber bundles are extracted from the mat material.

[0043] In the extracted fiber bundle 25, the distance D is the portion where the width of the axial portion 20' is maximum in a direction perpendicular to line A passing through the center of the fiber bundle 25. １ and the distance D of the part where the distance is minimized. ２ Measure the average value ((D １ +D２ Calculate the above average value ((D) for each fiber bundle. Note that when measuring the width of the shaft portion 20', parts where the inorganic fibers are intertwined and not in a single bundle are excluded from the measurement. １ +D ２ ) / 2) is measured, and the average value of these is calculated to determine the diameter of the first needle mark.

[0044] In the extracted fiber bundle 25, the distance D is the portion where the width of the return portion 23' is maximum in a direction perpendicular to line A passing through the center of the fiber bundle 25. ３ Measure the above distance D for each fiber bundle. ３ Measure the diameter and use the average value as the diameter of the return part.

[0045] In the mat material 10, the diameter of the first needle mark 20 is preferably 0.1 to 1.0 mm, and more preferably 0.3 to 0.9 mm.

[0046] In the mat material 10, the diameter of the return portion 23 is preferably 0.8 to 3.5 mm, and more preferably 1.0 to 3.0 mm.

[0047] The diameter of the first needle mark 20 and the diameter of the return portion 23 can be controlled by adjusting the angle and pressure when inserting and removing the needle 40, the thickness and shape of the needle 40, and the length, size, shape, and position of the barb 41.

[0048] Furthermore, the first needle mark 20 may have a twisted shape. The twisted shape of the first needle mark 20 indicates that the inorganic fibers constituting the first needle mark 20 are strongly intertwined, causing distortion. When the first needle mark 20 has a twisted shape, even if stress is applied to the first needle mark 20, the intertwining of the inorganic fibers is less likely to break. Therefore, the first needle mark 20 becomes stronger. In other words, even if outward stress in the thickness direction is applied to the mat material 10, the first needle mark 20 is less likely to tear. Consequently, the effect of preventing delamination near the second main surface 12 is enhanced. In order to make the first needle mark 20 have a twisted shape, the angle and pressure when inserting and removing the needle 40, the thickness and shape of the needle 40, the length, size, shape and placement of the barb 41, etc. should be adjusted.

[0049] In the mat material 10, the density of the first needle marks 20 (the density of the first needle penetration marks 21 on the first main surface 11) is preferably 0.5 to 18 pieces / cm. ２ It is preferably so.

[0050] In the mat material 10, the inorganic fiber is not particularly limited, but it is preferably composed of at least one selected from the group consisting of alumina fiber, silica fiber, alumina-silica fiber, mullite fiber, bio-soluble fiber, and glass fiber. When the inorganic fiber is at least one of alumina fiber, silica fiber, alumina-silica fiber, and mullite fiber, it has excellent heat resistance. Therefore, even when the exhaust gas treatment body is exposed to a sufficiently high temperature, no alteration or the like occurs, and the function as a mat material can be sufficiently maintained. Further, when the inorganic fiber is a bio-soluble fiber, when manufacturing an exhaust gas purification device using the mat material, even if the scattered inorganic fiber is inhaled or the like, it dissolves in the living body, so it does not harm the health of the operator.

[0051] The alumina fiber may contain additives such as calcium, magnesia, zirconia, etc. in addition to alumina. As the composition ratio of the alumina-silica fiber, it is preferably Al ２ O ３ : SiO ２ = 60:40 to 80:20, and more preferably Al ２ O ３ : SiO ２ = 70:30 to 74:26.

[0052] In the mat material 10, the average fiber length of the inorganic fiber is preferably 1 to 150 mm, and more preferably 10 to 80 mm. When the average fiber length of the inorganic fiber is less than 1 mm, the fiber length of the inorganic fiber is too short, so the entanglement between the inorganic fibers becomes insufficient, the winding property deteriorates, and it is easy to break. Also, it becomes difficult to form the above-mentioned return part. Further, when the average fiber length of the inorganic fiber exceeds 150 mm, the fiber length of the inorganic fiber is too long, so the number of fibers constituting the mat decreases, and the density of the mat material decreases. As a result, the shear strength of the mat material becomes low.

[0053] In the mat material 10, the average fiber diameter of the inorganic fibers is preferably 3 to 8 μm, and more preferably 5 to 7 μm. If the average fiber diameter of the inorganic fibers is less than 3 μm, the strength is weak, and the inorganic fibers are easily cut by impact, etc. In particular, when needling is performed, the inorganic fibers are cut, making it difficult to form the above-mentioned return portion. If the average fiber diameter of the inorganic fibers exceeds 8 μm, the fiber diameter is too thick, the Young's modulus of the inorganic fibers themselves becomes high, and the flexibility of the mat material tends to decrease.

[0054] The mat material 10 contains a binder. The binder adheres the inorganic fibers together, making it easier to maintain the shape of the mat material 10. In addition, the binder can prevent the inorganic fibers from falling off or scattering from the mat material 10.

[0055] In the mat material 10, the binder may be an organic binder or an inorganic binder, or both may be used in combination. Organic binders and inorganic binders are useful binders for molding the mat material 10. The organic binder is preferably at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, and polyvinyl alcohol, which function as water-soluble organic polymers; styrene resin, which functions as a thermoplastic resin; and epoxy resin, which functions as a thermosetting resin. The inorganic binder is preferably at least one consisting of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice. These organic and inorganic binders are suitable for bonding inorganic fibers together and maintaining the shape of the mat material.

[0056] In the mat material 10, the binder includes an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, and it is preferable that the inorganic particles are dispersed in the polymer resin. When the mat material 10 contains such a binder, the bonding between inorganic fibers by the binder becomes stronger, preventing the inorganic fibers from scattering from the mat material and increasing the strength of the mat material. Examples of polymer resins included in the organic binder include rubber resins, styrene resins, silicone resins, acrylic resins, polyester resins, polyurethane resins, etc. Examples of inorganic particles included in the inorganic binder include inorganic sol dispersions (alumina sol, silica sol, zirconia sol, titania sol, etc.).

[0057] In the mat material 10, there is a concentration gradient of the binder in the thickness direction of the mat material, and it is preferable that the weight proportion of the binder increases from the second main surface 12 side toward the first main surface 11 side. Such a binder concentration gradient will be explained below with reference to the drawings. Figure 5 is a schematic cross-sectional view of the mat material of the present invention, showing the first main surface side portion, the central portion, and the second main surface side portion.

[0058] As shown in Figure 5, the mat material 10 is divided into three equal parts in the thickness direction: a first main surface side portion 15 to which the first main surface 11 belongs, a second main surface side portion 17 to which the second main surface 12 belongs, and a central portion 16 sandwiched between the first main surface side portion 15 and the second main surface side portion 17. In this case, it is preferable that the weight ratio of the binder contained in the first main surface side portion 15 is greater than or equal to the weight ratio of the binder contained in the central portion 16, and that the weight ratio of the binder contained in the first main surface side portion 15 is greater than or equal to the weight ratio of the binder contained in the second main surface side portion 17. Furthermore, in the mat material 10, it is even more preferable that the weight ratio of the binder contained in the first main surface side portion 15 is greater than the weight ratio of the binder contained in the central portion 16, and that the weight ratio of the binder contained in the first main surface side portion 15 is greater than the weight ratio of the binder contained in the second main surface side portion 17. Furthermore, in the mat material 10, it is preferable that the weight ratio of the binder contained in the second main surface portion 17 is less than or equal to the weight ratio of the binder contained in the central portion 16. In addition, in the mat material 10, it is more preferable that the weight ratio of the binder contained in the first main surface portion 15 is greater than the weight ratio of the binder contained in the central portion 16, and that the weight ratio of the binder contained in the central portion 16 is greater than the weight ratio of the binder contained in the second main surface portion 17.

[0059] The weight percentage of the binder contained in the first main surface portion 15 is preferably 0.3 to 29.0 wt%, and more preferably 0.5 to 10.0 wt%. The weight percentage of the binder contained in the central portion 16 is preferably 0.2 to 15.0 wt%, and more preferably 0.3 to 5.0 wt%. The weight percentage of the binder contained in the second main surface portion 17 is preferably 0.05 to 5.00 wt%, and more preferably 0.1 to 3.0 wt%.

[0060] Generally, when manufacturing matting materials, a solvent containing a binder is applied to the matting material, followed by processes such as suction, compression, heating, and drying. One example of drying is drying with hot air. In this process, the binder may be unevenly distributed downwards due to gravity, or concentrated on the main surface where the hot air is applied. As a result, the manufactured matting material will have a gradient in the weight ratio of the binder along its thickness.

[0061] In such cases, the weight proportion of the binder increases near one main surface of the mat material. The inorganic fibers near the main surface on the side with a high binder weight proportion are firmly fixed by the binder, so the flexibility of the main surface on the side with a high binder weight proportion tends to decrease. When the mat material is wrapped around an exhaust gas treatment body, the difference between the inner and outer circumferences of the mat material makes the main surface on the outer circumference side of the mat material more susceptible to circumferential stress. Therefore, if the mat material is wrapped around the exhaust gas treatment body so that the main surface on the side with a high binder weight proportion faces the outer circumference, cracks are more likely to occur on the main surface on the side with a high binder weight proportion. Conversely, if the mat material is wrapped around the body so that the main surface on the side with a low binder weight proportion faces the outer circumference, cracks are less likely to occur on the main surface on the side with a low binder weight proportion.

[0062] The mat material 10 is wrapped around the exhaust gas treatment body such that the first main surface 11 becomes the inner circumference and the second main surface 12 becomes the outer circumference. Therefore, by manufacturing the mat material 10 such that the weight ratio of the binder on the second main surface side portion 17 is low, it is possible to prevent cracks from occurring on the second main surface 12 which is the outer circumference.

[0063] The thickness of the mat material 10 is not particularly limited, but is preferably 2 to 40 mm. If the thickness of the mat material is less than 2 mm, the surface pressure and holding power of the mat material will be insufficient, making it easy for the exhaust gas treatment body to fall out. Also, if a volume change occurs in the exhaust gas treatment body, the mat material will have difficulty absorbing the volume change of the exhaust gas treatment body. As a result, cracks and other damage are more likely to occur in the exhaust gas treatment body. If the thickness of the mat material exceeds 40 mm, the flexibility of the mat material is lost, making it difficult to handle when wrapping the mat material around the exhaust gas treatment body. Also, wrinkles and cracks are more likely to occur in the mat material.

[0064] The basis weight (weight per unit area) of mat material 10 is 200 to 4000 g / m². ２ Preferably, it is 1000 to 3500 g / m². ２ It is more preferable that the weight of the mat material be 200 g / m². ２ If the weight is less than 4000 g / m², the holding power will not be sufficient. ２Beyond a certain point, the bulk of the mat material does not decrease easily. Therefore, when manufacturing exhaust gas purification equipment using such mat material, the exhaust gas treatment components are more likely to fall off.

[0065] The bulk density of the mat material 10 (bulk density of the mat material before wrapping) is 0.10 to 0.25 g / cm³. ３ Preferably, it is 0.10 to 0.20 g / cm³. ３ It is more preferable that the bulk density of the mat material be 0.10 g / cm³. ３ If the density is less than 0.25 g / cm³, the inorganic fibers will not intertwine well and will easily peel off, making it difficult to maintain the shape of the mat material. ３ Beyond a certain point, the mat material hardens, reducing its ability to wrap around the exhaust gas treatment unit and making it more prone to cracking.

[0066] The mat material 10 may be subjected to a needlering process in which needles are inserted and removed from the first main surface 11 toward the second main surface 12. In this case, the needles may or may not penetrate the mat material 10.

[0067] When a needle penetrates the mat material 10 from the first main surface 11 toward the second main surface 12, a second needle penetration mark is formed on the second main surface 12 of the mat material 10, a second needle exit mark is formed on the first main surface 11 of the mat material 10, and a second needle mark is formed in the mat material from the second needle penetration mark to the second needle exit mark, where multiple inorganic fibers are intertwined.

[0068] By performing the needling treatment on both sides of the mat material 10 in this way, the multiple inorganic fibers constituting the mat material become more intertwined, improving the elasticity and strength of the mat material.

[0069] Next, the method for manufacturing the mat material of the present invention will be described.

[0070] The mat material of the present invention can be obtained, for example, by a spinning step of spinning a spinning mixture containing at least an inorganic compound and an organic polymer to produce an inorganic fiber precursor; a compression step of compressing the inorganic fiber precursor to produce a sheet; a needling step of performing a needling treatment on at least one surface of the sheet; a firing step of firing the needled sheet to produce a mat material; and a binder impregnation step of impregnating the mat material with a binder. Specific examples of the spinning step, compression step, needling step, firing step, and binder impregnation step will be described below.

[0071] [Spinning Process] In the spinning process, an inorganic fiber precursor is produced by spinning a spinning mixture containing at least an inorganic compound and an organic polymer. For example, in the spinning process, an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm is produced by spinning a spinning mixture made from a basic aluminum chloride aqueous solution and silica sol, etc., using a blowing method.

[0072] [Compression Process] In the compression process, the inorganic fiber precursor obtained in the spinning process is compressed to produce a continuous sheet of a predetermined size.

[0073] [Needling Process] In the needling process, a needle is inserted through the sheet obtained in the compression process from the first main surface to the second main surface to perform the needling treatment. At this time, inorganic fiber precursors form a closed loop in the first needle penetration marks on the second main surface, and a return portion protruding from the second main surface is formed. Furthermore, in the mat material after firing, which will be described later, the ratio of the diameter of the return portion to the diameter of the first needle mark ([Diameter of the return portion] / [Diameter of the first needle mark]) is made to exceed 1.5.

[0074] [Casturing Process] In the calcination process, the sheet is calcined. This calcines the inorganic fiber precursor into inorganic fibers. The calcination temperature is not particularly limited, but it is preferably between 1000°C and 1600°C.

[0075] [Bonding agent impregnation process] In the bonding agent impregnation process, the bonding agent is mixed with a solvent, and the solvent containing the bonding agent is impregnated onto the mat material by a coating method or a spray method. Then, the solvent is evaporated from the mat material. At this time, suction, compression, heating, and drying may be performed so that the weight ratio of the bonding agent increases from the second main surface side to the first main surface side of the mat material. For example, by drying the mat material so that hot air hits the first main surface side of the mat material, the weight ratio of the bonding agent can be increased from the second main surface side to the first main surface side of the mat material. Alternatively, by leaving the mat material to stand with the second main surface side facing upwards and drying it, the weight ratio of the bonding agent can be increased from the second main surface side to the first main surface side of the mat material. The mat material of the present invention can be manufactured through the above process.

[0076] Next, an exhaust gas purification device of the present invention using the mat material of the present invention will be described. Figure 6 is a schematic cross-sectional view showing an example of the exhaust gas purification device of the present invention.

[0077] As shown in Figure 6, the exhaust gas purification device 100 comprises a metal casing 50, an exhaust gas treatment unit 60 housed in the metal casing 50, and a mat material 10 disposed between the exhaust gas treatment unit 60 and the metal casing 50. The mat material 10 is the mat material of the present invention. As shown in Figure 6, in the exhaust gas purification device 100, the first main surface 11 of the mat material 10 is in contact with the exhaust gas treatment unit, and the second main surface 12 is in contact with the metal casing.

[0078] The exhaust gas treatment unit 60 is a columnar structure in which numerous cells 61 are arranged longitudinally separated by cell walls 62. 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 are connected to the ends of the metal casing 50 as needed. In the exhaust gas purification device 100 shown in Figure 6, an exhaust gas filter (honeycomb filter) is used as the exhaust gas treatment unit 60, in which one end face of each cell is sealed with a sealing material 63. However, a catalyst carrier without sealing material on either end face may also be used.

[0079] As shown in Figure 6, exhaust gas (in Figure 6, 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 61 that opens on the exhaust gas inlet end face 60a of the exhaust gas treatment body (honeycomb filter) 60, and passes through the cell wall 62 separating the cells 61. At this time, PM in the exhaust gas is captured by the cell wall 62, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 61 that opens on the exhaust gas discharge end face 60b and is discharged to the outside.

[0080] The exhaust gas treatment body 60 may be made of a non-oxidizing porous ceramic such as silicon carbide or silicon nitride, or it may be made of an oxidizing porous ceramic such as sialon, alumina, corderite, or mullite. Among these, silicon carbide is preferred.

[0081] When the exhaust gas treatment body 60 is a porous ceramic made of silicon carbide, the porosity of the porous ceramic is not particularly limited, but it is preferably 35 to 60%. If the porosity is less than 35%, the exhaust gas treatment body may quickly become clogged, while if the porosity exceeds 60%, the strength of the exhaust gas treatment body may decrease and it may easily break.

[0082] Furthermore, the average pore size of the porous ceramic is preferably 5 to 30 μm. If the average pore size is less than 5 μm, PM may easily clog the pores. If the average pore size exceeds 30 μm, PM may pass through the pores, making it impossible to collect PM and thus rendering the filter ineffective. The above porosity and pore size can be measured by conventionally known methods using a scanning electron microscope (SEM).

[0083] The cell density in the cross-section of the exhaust gas treatment body 60 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 pieces / cm ２ (250 pieces / inch ２A more preferable upper limit is 77.5 pieces / cm². ２ (500 pieces / inch ２ )

[0084] The exhaust gas treatment unit 60 may be supported with a catalyst for purifying the exhaust gas. Preferably used 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. The presence of these catalysts facilitates the combustion and removal of PM and enables the purification of toxic exhaust gases.

[0085] (Metal casing) The metal casing 50 is approximately cylindrical in shape. Preferably, the inner diameter of the metal casing 50 (the inner diameter of the part that houses the exhaust gas treatment body) is slightly shorter than the diameter of the exhaust gas treatment body 60 around which the mat material 10 is wrapped.

[0086] The metal casing 50 is not particularly limited, but is preferably made of stainless steel.

[0087] When manufacturing such an exhaust gas purification device 100, the mat material 10 is wrapped around the exhaust gas treatment body 60 to form a wrapped body, which is then housed in a metal casing 50. The wrapped body in which the mat material 10 is wrapped around the exhaust gas treatment body 60 is also the wrapped body of the present invention.

[0088] Figure 7 is a schematic perspective view showing an example of a winding body according to the present invention. As shown in Figure 7, the winding body 70 includes an exhaust gas treatment body 60 which is the body to be wound, and a mat material 10 which is wound around the exhaust gas treatment body 60.

[0089] In the wrapped body 70, the first main surface 11 of the mat material 10 is wrapped around the exhaust gas treatment body 60 so that it is in contact with it.

[0090] In other words, in the wrapped body 70, the mat material 10 is wrapped around the exhaust gas treatment body 60 such that the first main surface 11 is the inner circumference and the second main surface 12 is the outer circumference. Since predetermined first needle marks (not shown) and return portions (not shown) are formed on the mat material 10, the return portions act as support near the second main surface, preventing peeling from occurring near the second main surface.

[0091] Therefore, it is possible to prevent peeling of the mat material 10 when manufacturing the exhaust gas purification device 100. As a result, it is possible to prevent the exhaust gas treatment body 60 from falling out due to gas pressure, etc., and to prevent exhaust gas from leaking from the peeled parts of the mat material 10.

[0092] In the above description, we have described a wrapped body in which the mat material 10 is wrapped around an exhaust gas treatment body. However, in the wrapped body of the present invention, the body to which the mat material is wrapped is not limited to an exhaust gas treatment body, but may also be piping or the like that requires heat retention.

[0093] This specification discloses the following:

[0094] (1) The present disclosure is a mat material comprising inorganic fibers and a binder, having a first main surface and a second main surface opposite the first main surface, wherein a first needle penetration mark is formed on the first main surface of the mat material, a first needle exit mark is formed on the second main surface of the mat material, a first needle mark is formed in the mat material from the first needle penetration mark to the first needle exit mark in which a plurality of inorganic fibers are intertwined, in the first needle exit mark a plurality of inorganic fibers form a closed loop and a return portion is formed protruding from the second main surface, and the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) is greater than 1.5.

[0095] The present disclosure (2) is a mat material according to the present disclosure (1), wherein when the mat material is divided into three equal parts in the thickness direction, it is divided into a first main surface side portion to which the first main surface belongs, a second main surface side portion to which the second main surface belongs, and a central portion sandwiched between the first main surface side portion and the second main surface side portion, the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the central portion, and the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the second main surface side portion.

[0096] The present disclosure (3) is a mat material according to the present disclosure (2), wherein the weight ratio of the binder contained in the first main surface portion is greater than the weight ratio of the binder contained in the central portion, and the weight ratio of the binder contained in the first main surface portion is greater than the weight ratio of the binder contained in the second main surface portion.

[0097] Disclosure (4) is a mat material according to Disclosure (2) or (3), wherein the weight ratio of the binder contained in the second main surface portion is less than or equal to the weight ratio of the binder contained in the central portion.

[0098] Disclosure (5) is a mat material according to any one of Disclosures (1) to (4), wherein the binder is an organic binder and / or an inorganic binder.

[0099] Disclosure (6) is a mat material according to any one of Disclosures (1) to (5), wherein the binder comprises an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, the inorganic particles being dispersed in the polymer resin.

[0100] Disclosure (7) is a mat material according to any of Disclosures (1) to (6), wherein the first needle marks described above have a twisted shape.

[0101] The present disclosure (8) is a mat material according to any one of the present disclosures (1) to (7), wherein a second needle penetration mark is formed on the second main surface of the mat material, a second needle exit mark is formed on the first main surface of the mat material, and a second needle mark is formed on the mat material from the second needle penetration mark to the second needle exit mark, in which a plurality of inorganic fibers are intertwined.

[0102] The present disclosure (9) is a winding body comprising a body to be wound and a mat material wound around the body to be wound, wherein the mat material is a mat material according to any one of the present disclosures (1) to (8), and the mat material is wound around the body such that the first main surface of the mat material is in contact with the body to be wound.

[0103] This disclosure (10) states that the wrapped body is the winding body described in this disclosure (9), which is an exhaust gas treatment body.

[0104] The present disclosure (11) is an exhaust gas purification device comprising an exhaust gas treatment body, a metal casing housing the exhaust gas treatment body, and a mat material disposed between the exhaust gas treatment body and the metal casing and holding the exhaust gas treatment body, wherein the mat material is the mat material described in any of the present disclosures (1) to (8), and the mat material is arranged such that its first main surface is in contact with the exhaust gas treatment body.

[0105] The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0106] (Example 1) [Spinning Process] A basic aluminum chloride aqueous solution was prepared with an Al content of 70 g / L and Al:Cl = 1:1.8 (atomic ratio). The composition ratio of the inorganic fibers after calcination was Al ２ O ３ SiO ２ A silica sol was blended in a ratio of 72:28 (by weight), and an appropriate amount of organic polymer (polyvinyl alcohol) was added to prepare a mixture. The resulting mixture was concentrated to make a spinning mixture, and this spinning mixture was spun by the blowing method to produce an inorganic fiber precursor with an average fiber diameter of 5.1 μm.

[0107] [Compression Process] The inorganic fiber precursor obtained in the [Spinning Process] above was compressed to produce a continuous sheet.

[0108] [Needling Process] The sheet obtained in the [Compression Process] above was subjected to continuous needling using the following conditions. First, 9 needles / cm ２ A needle board was prepared with a density of [density]. Next, this needle board was placed on the first main surface side of the sheet, and a needlering process was performed by inserting and removing the needle board once along the thickness direction of the sheet. During this process, the needle was penetrated until the barb formed at the tip of the needle completely penetrated the second main surface of the sheet. As a result, the inorganic fiber precursor formed a closed loop in the first needle penetration mark on the second main surface, and a return portion protruding from the second main surface was formed.

[0109] [Firing Process] The needling-treated sheets were continuously fired at a maximum temperature of 1250°C to produce a mat material consisting of inorganic fibers containing alumina and silica in a ratio of 72 parts by weight: 28 parts by weight. The average fiber diameter of the inorganic fibers was 5.1 μm, and the minimum value of the inorganic fiber diameter was 3.2 μm. The mat material obtained in this way had a bulk density of 0.15 g / cm³. ３ The basis weight is 1500 g / m². ２ The density of the first needle marks (density of first needle penetration marks on the first main surface) was 9 marks / cm². ２ That was the case.

[0110] [Binding agent impregnation process] Latex, an organic binder, was diluted with industrial water to prepare an organic binder solution with a concentration of 1.0 wt%. Next, the organic binder solution was impregnated onto the mat material using a spray so that the amount of organic binder was 1.0 wt% relative to the amount of inorganic fibers in the mat material.

[0111] Subsequently, the mat material was dried while being heated and compressed so that a large amount of organic binder was unevenly distributed on the first main surface side. This produced the mat material according to Example 1.

[0112] (Measurement of [Diameter of the return portion] / [Diameter of the first needle mark]) The mat material according to Example 1 was loosened by hand, and fiber bundles originating from the first needle mark were extracted. A representative example of one of the extracted fiber bundles is shown in Figure 8. Figure 8 is a photograph of a fiber bundle originating from the first needle mark contained in the mat material according to Example 1.

[0113] Five such fiber bundles were taken out, and the diameter of the first needle mark and the diameter of the return portion were measured using the method described above. In the mat material according to Example 1, the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) was 3.4.

[0114] (Measurement of the weight ratio of binder in the first main surface portion, central portion and second main surface portion) The mat material according to Example 1 was cut into three equal parts in the thickness direction, and divided into the first main surface portion, central portion and second main surface portion. The weight of each portion was measured. Next, the organic binder contained in each portion was decomposed by heating each portion at 600°C. The weight of each portion after heating was measured, and the weight reduction was taken as the weight of the binder contained in each portion. The weight ratio of the organic binder contained in the first main surface portion to the organic binder contained in the central portion was 3.3. The weight ratio of the organic binder contained in the second main surface portion to the organic binder contained in the central portion was 0.5.

[0115] (Comparative Example 1) A mat material according to Comparative Example 1 was manufactured in the same manner as in Example 1, except that the needling process was performed by adjusting the barb formed on the tip of the needle so that the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of the first needle mark]) was 1.5.

[0116] (Comparative Example 2) In the above [bonding process], the mat material was heated and compressed while drying so that a large amount of organic bond was unevenly distributed on the second main surface side, except that the mat material according to Comparative Example 2 was manufactured in the same manner as in Comparative Example 1.

[0117] (Evaluation of Wrapping Ability) Test specimens were prepared by cutting the mat material according to Example 1 and Comparative Examples 1-2 into rectangles with a longitudinal length of 350 mm and a transverse length of 30 mm. Next, a cylindrical body with a diameter of 100 mm was prepared, and each test specimen was wrapped around the cylindrical body so that the first main surface was in contact with the cylindrical body. At this time, the second main surface of each test specimen was visually observed to see if delamination and cracking occurred. The results are shown in Table 1.

[0118]

[0119] As shown in Table 1, the mat material according to Example 1 was found to be less prone to peeling and cracking when wrapped around the body to be wound.

[0120] 10 Mat material 10a Sheet 11, 11a First main surface 12, 12a Second main surface 13 One end 13a Convex part 14 Other end 14a Recessed part 15 First main surface side part 16 Central part 17 Second main surface side part 20 First needle mark 20' Shaft part 21 First needle penetration mark 22 First needle exit mark 23, 23', 23a Return part 25 Fiber bundle 30a Inorganic fiber precursor 40 Needle 41 Barb 50 Metal casing 60 Exhaust gas treatment body 60a Exhaust gas inlet side end surface 60b Exhaust gas discharge side end surface 61 Cell 62 Cell wall 63 Sealing material 70 Winding body 100 Exhaust gas purification device

Claims

1. A mat material comprising inorganic fibers and a binder, having a first main surface and a second main surface opposite the first main surface, wherein the first main surface of the mat material has a first needle penetration mark formed thereon, the second main surface of the mat material has a first needle exit mark formed thereon, the mat material has a first needle mark formed thereon where a plurality of the inorganic fibers are intertwined from the first needle penetration mark to the first needle exit mark, the plurality of the inorganic fibers form a closed loop in the first needle exit mark, and a return portion is formed that protrudes from the second main surface, and the ratio of the diameter of the return portion to the diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) is greater than 1.

5.

2. The mat material according to claim 1, wherein when the mat material is divided into three equal parts in the thickness direction, into a first main surface side portion to which the first main surface belongs, a second main surface side portion to which the second main surface belongs, and a central portion sandwiched between the first main surface side portion and the second main surface side portion, the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the central portion, and the weight ratio of the binder contained in the first main surface side portion is equal to or greater than the weight ratio of the binder contained in the second main surface side portion.

3. The mat material according to claim 2, wherein the weight ratio of the binder contained in the first main surface portion is greater than the weight ratio of the binder contained in the central portion, and the weight ratio of the binder contained in the first main surface portion is greater than the weight ratio of the binder contained in the second main surface portion.

4. The mat material according to claim 2, wherein the weight ratio of the binder contained in the second main surface portion is less than or equal to the weight ratio of the binder contained in the central portion.

5. The mat material according to claim 1, wherein the binder is an organic binder and / or an inorganic binder.

6. The mat material according to claim 1, wherein the binder comprises an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, and the inorganic particles are dispersed in the polymer resin.

7. The mat material according to claim 1, wherein the first needle mark has a twisted shape.

8. The mat material according to claim 1, wherein a second needle penetration mark is formed on the second main surface of the mat material, a second needle exit mark is formed on the first main surface of the mat material, and a second needle mark is formed in the mat material from the second needle penetration mark to the second needle exit mark, in which a plurality of inorganic fibers are intertwined.

9. A winding body comprising a body to be wound and a mat material wound around the body to be wound, wherein the mat material is the mat material described in any one of claims 1 to 8, and the mat material is wound around the body such that the first main surface of the mat material is in contact with the body to be wound.

10. The winding body according to claim 9, wherein the winding body is an exhaust gas treatment body.

11. An exhaust gas purification device comprising an exhaust gas treatment body, a metal casing housing the exhaust gas treatment body, and a mat material disposed between the exhaust gas treatment body and the metal casing and holding the exhaust gas treatment body, wherein the mat material is the mat material described in any one of claims 1 to 8, and the mat material is arranged such that the first main surface of the mat material is in contact with the exhaust gas treatment body.

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