Mat material, wound body, and exhaust gas purification device

Abstract

To provide a mat material which is unlikely to peel off when wrapped around a wound body. [Solution] A mat material comprising inorganic fibers and a binder, and 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 and a first needle protrusion mark is formed on the second main surface of the mat material, and a first needle mark in which a plurality of the inorganic fibers are entangled is formed in the mat material from the first needle penetration mark to the first needle protrusion mark, and in the first needle protrusion mark, the plurality of the inorganic fibers form a closed loop and a return portion is formed protruding from the second main surface, and a ratio of a diameter of the return portion to a diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) exceeds 1.5.

Description

[Technical field]

[0001] The present invention relates to a mat material, a wound body, and an exhaust gas purification device. [Background technology]

[0002] Exhaust gas emitted from internal combustion engines such as diesel engines contains particulate matter (hereinafter referred to as PM), and in recent years, the harm that this PM poses to the environment and human body has become a problem. In addition, exhaust gas also contains harmful gas components such as CO, HC, and NOx, and there are concerns about the impact that these harmful gas components have on the environment and human body.

[0003] In response to this, various exhaust gas purification devices have been proposed that capture PM in exhaust gas and purify harmful gas components, and are composed of an exhaust gas treatment body made of porous ceramics such as silicon carbide and 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 purpose of the retaining seal material (mat material) is to prevent the exhaust gas treatment body from coming into contact with the casing that covers its outer periphery and being damaged by vibrations and impacts caused by the running of the automobile, and to prevent exhaust gas from leaking from between the exhaust gas treatment body and the casing.

[0004] One such mat material known is a needling mat, which is made by compressing an alumina fiber precursor that is converted into inorganic fibers by firing to produce a sheet, inserting and removing needles with multiple barbs in the thickness direction of the sheet to produce a needling sheet in which entangled portions are formed, and firing the needling sheet.

[0005] For example, Patent Document 1 discloses a method for producing such a needling mat, the method comprising: preparing a sheet having a first main surface and a second main surface opposite to the first main surface, the sheet being composed of entangled inorganic fiber precursors that are converted into inorganic fibers by firing; a needling step of penetrating needles into the sheet to produce a needling sheet; and a firing step of firing the needling sheet, the sheet being composed 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 containing a first long fiber precursor and the second sheet containing a short fiber precursor having an average fiber length shorter than that of the first long fiber precursor, and the needling step being characterized in that the needles are penetrated from the first main surface side toward the second main surface side. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-236526 A Summary of the Invention [Problem to be solved by the invention]

[0007] When an exhaust gas purification device is manufactured using the needling mat described in Patent Document 1, the needling mat arranged on the outer periphery side sometimes tears on its surface and peels off from its edge.

[0008] The present invention has been made to solve the above problems, and an object of the present invention is to provide a mat material that is less likely to peel off when wrapped around a wound body. [Means for solving the problem]

[0009] As a result of extensive research, the inventors have discovered that by adjusting the size of the closed-loop return portions of the inorganic fibers that are generated on the main surface of the mat material during needling and positioning the main surface of the mat material on which the closed-loop return portions are formed on the outer periphery, the mat material is less likely to peel off, and have completed the present invention.

[0010] That is, the mat material of the present invention contains inorganic fibers and a binder, and has a first main surface and a second main surface opposite to the first main surface, wherein a first needle penetration mark is formed on the first main surface of the mat material, and a first needle protrusion mark is formed on the second main surface of the mat material, and a first needle mark in which a plurality of the inorganic fibers are entangled is formed in the mat material from the first needle penetration mark to the first needle protrusion mark, and in the first needle protrusion mark, the plurality of the inorganic fibers are in a closed loop shape, and a return portion protruding from the second main surface is formed, 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] When producing the mat material of the present invention, an inorganic fiber precursor to be converted into inorganic fibers is compressed to prepare a sheet, and a needle having a plurality of 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, a part of the inorganic fiber precursor is pushed out by the needle on the main surface on the needle protruding side and protrudes from the main surface. A part of the inorganic fiber precursor thus pushed out is not cut by the needle and becomes a loop-shaped return part. Thereafter, the sheet is fired, and the inorganic fiber precursor forming the loop-shaped return portions is fired into inorganic fibers while maintaining the same shape. In the mat member of the present invention, such a loop-shaped return portion is formed on the second main surface.

[0012] The mat material of the present invention is used by being wound around a body to be wound. At this time, the mat material of the present invention is wound so that the first main surface is in contact with the body to be wound. In the mat material of the present invention wound in this manner, the first main surface becomes the inner circumference and the second main surface becomes the outer circumference. When the return portion is provided on the second main surface side, which forms the outer periphery, the loop-shaped return portion provides support near the second main surface, making it possible to prevent peeling from occurring near the second main surface. In particular, 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, this effect is more pronounced. Therefore, when the mat material of the present invention is wound around a wound body, the mat material of the present invention is unlikely to peel off.

[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 proportion of the binder contained in the first main surface side portion is greater than or equal to the weight proportion of the binder contained in the central portion, and the weight proportion of the binder contained in the first main surface side portion is greater than or equal to the weight proportion 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 proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the central portion, and that the weight proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the second main surface side portion. Furthermore, in the mat of the present invention, the weight percentage of the binder contained in the second main surface portion is preferably equal to or lower than the weight percentage of the binder contained in the central portion.

[0014] When producing the mat material of the present invention, a solvent containing a binder is applied to the mat material, and then the mat material is subjected to suction, compression, heating, drying, etc. For example, a method of drying by applying hot air can be mentioned as an example of drying. In this process, the binder may be unevenly distributed downward due to gravity, or may be unevenly distributed in large amounts on the main surface that is exposed to the hot air. Therefore, in the produced mat material, a gradient in the weight ratio of the binder is formed in the thickness direction.

[0015] In such a case, the weight ratio of the binder is high near one of the main surfaces of the mat material, and since the inorganic fibers near the main surface on the side where the weight ratio of the binder is high are firmly fixed by the binder, the flexibility of the main surface on the side where the weight ratio of the binder is high is likely to decrease. Here, when the mat material is wound around a wound body, the main surface on the outer periphery side of the mat material is likely to receive stress in the circumferential direction due to the difference between the inner periphery and the outer periphery of the mat material. Therefore, if the mat material is wound around the body so that the main surface on the side with the higher weight percentage of the binder faces the outer periphery, cracks are likely to occur on the main surface on the side with the higher weight percentage of the binder. Conversely, if the mat material is wrapped around the body so that the main surface on the side with the lower weight percentage of the binder faces the outer periphery, cracks are less likely to occur on the main surface on the side with the lower weight percentage of the binder. As described above, the mat material of the present invention is wound around a body to be wound so that the first main surface is the inner circumference and the second main surface is the outer circumference. Therefore, by manufacturing the mat material of the present invention so that the weight ratio of the binder in the second main surface portion is low, it is possible to prevent cracks from occurring in 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. In forming the mat material, organic binders and inorganic binders are useful binders.

[0017] In the mat material of the present invention, it is preferable that the binder contains an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, and the inorganic particles are dispersed in the polymer resin. In such a mat material, the inorganic fibers are strongly bound to each other by the binder, which makes it possible to prevent the 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 fact that the first needle marks have a twisted shape means that the inorganic fibers that make up the first needle marks are strongly entangled, causing distortion. When the first needle marks have a twisted shape, the inorganic fibers are less likely to become untangled even if stress is applied to the first needle marks, and therefore the first needle marks become stronger. In other words, even if an outward stress in the thickness direction is applied to the mat material, the first needle mark is unlikely to tear off. This further increases the effect of preventing peeling from occurring in the vicinity of the second main surface.

[0019] In the mat material of the present invention, it is preferable that second needle penetration marks are formed on the second main surface of the mat material, second needle protrusion marks are formed on the first main surface of the mat material, and second needle marks in which a plurality of the inorganic fibers are entangled are formed in the mat material from the second needle penetration marks to the second needle protrusion marks. In such a mat material, a needling process is performed so that the needles penetrate from the first main surface to the second main surface and from the second main surface to the first main surface, which causes the inorganic fibers constituting the mat material to be more entangled, improving the elasticity and strength of the mat material.

[0020] The wound body of the present invention is a wound body including a wound body and a mat material wound around the wound body, wherein the mat material is the mat material of the present invention, and the mat material is wound so that a first main surface of the mat material is in contact with the wound body.

[0021] In such a wound body, the first main surface of the mat material of the present invention is in contact with the wound body, so that peeling of the mat material can be prevented as described above.

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

[0023] The exhaust gas purification device of the present invention is an exhaust gas purification device comprising an exhaust gas treatment body, a metal casing that houses the exhaust gas treatment body, and a mat material that is arranged between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body, wherein the mat material is the mat material of the present invention, and the mat material is arranged so that a first main surface of the mat material is in contact with the exhaust gas treatment body.

[0024] In such an exhaust gas purification device, the first main surface of the mat material of the present invention is in contact with the exhaust gas treatment body, so that it is possible to prevent the mat material from peeling off, as described above. Therefore, it is possible to prevent the exhaust gas treatment body from falling off due to gas pressure or the like, and to prevent exhaust gas from leaking from peeled-off portions of the mat material. Effect of the Invention

[0025] According to the present invention, it is possible to provide a mat material that is unlikely to peel off when wrapped around a wound body. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a perspective view that illustrates an example of the mat material of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA of the mat material of the present invention shown in FIG. [Figure 3A] FIG. 3A is a schematic diagram illustrating the principle of how the return portion is formed in the mat member of the present invention. [Figure 3B] FIG. 3B is a schematic diagram illustrating the principle of how the return portion is formed in the mat member of the present invention. [Figure 3C] FIG. 3C is a schematic diagram illustrating the principle of how the return portion is formed in the mat member of the present invention. [Figure 4]FIG. 4 is a schematic diagram of an example of a first needle mark taken out from the mat material of the present invention. [Diagram 5] FIG. 5 is a cross-sectional view of the mat material of the present invention, which diagrammatically illustrates a first main surface side portion, a central portion, and a second main surface side portion. [Figure 6] FIG. 6 is a cross-sectional view that illustrates an example of an exhaust gas purification device of the present invention. [Figure 7] FIG. 7 is a perspective view showing a schematic diagram of an example of a wound body of the present invention. [Figure 8] FIG. 8 is a photograph of fiber bundles originating from the first needle marks included in the mat material according to Example 1. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The mat material of the present invention will be specifically described below. However, the present invention is not limited to the following configuration, and can be appropriately modified and applied within the scope that does not change 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 that illustrates an example of the mat material of the present invention. 1, the mat material 10 contains inorganic fibers and a binder, and has a first main surface 11 and a second main surface 12 opposing the first main surface 11. The mat material is rectangular in plan view.

[0029] As shown in FIG. 1, the mat material 10 has a protruding portion 13a at one end 13 and a recessed portion 14a at the other end 14. As shown in FIG.

[0030] As will be described in detail later, the mat material 10 is wrapped around an exhaust gas treatment body and placed in an exhaust gas purification device. At this time, the mat material 10 is wrapped so that the first main surface 11 is in contact with the exhaust gas treatment body. The convex portion 13a and the concave portion 14a are shaped to fit exactly together when the mat material 10 is wrapped around the exhaust gas treatment body. When such convex portions 13a and concave portions 14a are provided, the mat material 10 has improved sealing properties when placed in an exhaust gas purification device, which will be described later.

[0031] The mat material 10 is a mat material that has been subjected to a needling process. The needling process is a process in which an inorganic fiber precursor to be converted into inorganic fibers is compressed to produce a sheet, and a needle having multiple barbs is inserted and removed in the thickness direction of the sheet to produce a needling sheet in which entangled portions are formed. By firing such a needling sheet, a mat material that has been subjected to the needling process is produced. By carrying out the needling treatment, the inorganic fibers are entangled, and the strength of the mat material is improved.

[0032] The mat material 10 is a mat material that has been subjected to a needling process, and therefore needle marks are formed on it. These needle marks will be described in detail with reference to the drawings. FIG. 2 is a cross-sectional view taken along line AA of the mat material of the present invention shown in FIG.

[0033] As shown in Figures 1 and 2, first needle penetration marks 21 are formed on the first main surface 11 of the mat material 10, and first needle protrusion marks 22 are formed on the second main surface 12 of the mat material 10. Further, in the mat material 10, a first needle mark 20 in which a plurality of inorganic fibers are entangled is formed from a first needle penetration mark 21 to a first needle protrusion mark 22.

[0034] In the mat material 10, at the first needle protrusion marks 22, a plurality of inorganic fibers are arranged in a closed loop shape, and a return portion 23 protruding from the second main surface 12 is formed.

[0035] The principle of how the turned-back portion 23 is formed in the mat material 10 will be described. 3A to 3C are schematic diagrams illustrating the principle of how the return portion is formed in the mat member of the present invention. 3A to 3C, for the sake of convenience, the first main surface is shown as being on top and the second main surface is shown as being on the bottom, that is, the positional relationship between the first main surface and the second main surface in FIGS. 1 and 2 is upside down.

[0036] As shown in FIG. 3A, when manufacturing the mat material, an inorganic fiber precursor 30a to be converted into inorganic fibers is compressed to produce a sheet 10a, and needles 40 having a plurality of barbs 41 formed thereon are penetrated in the thickness direction of the sheet 10a (the direction from the first main surface 11a toward the second main surface 12a, which is the direction indicated by the arrow in FIG. 3A).

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

[0038] Thereafter, as shown in FIG. 3C, the needles 40 are pulled out of the sheet 10a, but a portion of the inorganic fiber precursor 30a pushed out toward the second main surface 12a is not cut by the needles 40 and becomes a loop-shaped return portion 23a.

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

[0040] The mat material 10 is wound around the exhaust gas treatment body so that the first main surface 11 forms the inner periphery and the second main surface 12 forms the outer periphery. When the return portion 23 is provided on the second main surface 12 side, which is the outer periphery, the loop-shaped return portion 23 provides 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]) exceeds 1.5. The ratio ([diameter of the barb portion] / [diameter of the first needle mark]) is preferably greater than 2.0. Moreover, the ratio ([diameter of the return portion] / [diameter of the first needle mark]) is preferably 6.0 or less, and more preferably 5.5 or less. When the ratio ([diameter of return portion] / [diameter of first needle mark]) exceeds 1.5, the loop-shaped return portion 23 acts as 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, the mat material 10 is unlikely to peel off.

[0042] In this specification, the terms "diameter of the first needle mark" and "diameter of the return portion" refer to values ​​calculated as follows. FIG. 4 is a schematic diagram of an example of a fiber bundle resulting from a first needle mark taken out from the mat material of the present invention. In the first needle marks contained in the mat material of the present invention, the inorganic fibers are more strongly entangled with each other than in other parts, so by loosening the mat material of the present invention, the fiber bundles originating from the first needle marks can be extracted. As shown in FIG. 4, the fiber bundle 25 extracted from the mat material comprises 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," five random fiber bundles are taken out from the mat material.

[0043] In the taken-out fiber bundle 25, the distance D of the part where the width of the shaft portion 20' is maximum in the direction perpendicular to the line A passing through the center of the fiber bundle 25 1 and the minimum distance D 2 The average value ((D 1 +D 2) / 2) is calculated. Note that, when measuring the width of shaft portion 20', a portion where the inorganic fibers are entangled and not formed into a single bundle is not measured. The average value (D 1 +D 2 ) / 2) is measured, and the average value of these is calculated to obtain the diameter of the first needle mark.

[0044] In the taken-out fiber bundle 25, the distance D of the part where the width of the return portion 23' is maximum in the direction perpendicular to the line A passing through the center of the fiber bundle 25 3 Measure. For each fiber bundle, the above distance D 3 The average value is the diameter of the return part.

[0045] In the mat material 10, the diameter of the first needle marks 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 barb 23 can be controlled by adjusting the angle, pressure, etc. when inserting and removing the needle 40, the thickness, shape, etc. of the needle 40, and the length, size, shape, and placement position of the barb 41, etc.

[0048] The first needle mark 20 may have a twisted shape. The fact that the first needle marks 20 have a twisted shape means that the inorganic fibers that make up the first needle marks 20 are strongly entangled, causing distortion. When the first needle marks 20 have a twisted shape, the inorganic fibers are unlikely to become untangled even if stress is applied to the first needle marks 20. Therefore, the first needle marks 20 become strong. In other words, even if an outward stress in the thickness direction is applied to the mat material 10, the first needle marks 20 are unlikely to tear off. Therefore, the effect of preventing peeling in the vicinity of the second main surface 12 is enhanced. In order to give the first needle mark 20 a twisted shape, the angle, pressure, etc. when inserting and removing the needle 40, the thickness, shape, etc. of the needle 40, and the length, size, shape, placement position, etc. of the barb 41 may 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 in the first main surface 11) is 0.5 to 18 marks / cm 2 It is preferable that:

[0050] In the mat material 10, the inorganic fibers are not particularly limited, but are desirably composed of at least one type selected from the group consisting of alumina fibers, silica fibers, alumina-silica fibers, mullite fibers, biosoluble fibers, and glass fibers. When the inorganic fiber is at least one of alumina fiber, silica fiber, alumina-silica fiber, and mullite fiber, it has excellent heat resistance, so that even if the exhaust gas treatment body is exposed to a sufficiently high temperature, deterioration does not occur and the function as a mat material can be sufficiently maintained. Furthermore, when the inorganic fiber is a biosoluble fiber, even if the inorganic fiber scattered during the production of the exhaust gas purification device is inhaled, it dissolves in the body and does not harm the health of the worker.

[0051] The alumina fibers may contain additives other than alumina, such as calcia, magnesia, and zirconia. The composition ratio of the alumina silica fiber is Al 2 O 3 :SiO 2 = 60:40 to 80:20 is preferable, and Al 2 O 3 :SiO 2 It is more preferable that the ratio is 70:30 to 74:26.

[0052] In the mat member 10, the average fiber length of the inorganic fibers is preferably 1 to 150 mm, and more preferably 10 to 80 mm. If the average fiber length of the inorganic fibers is less than 1 mm, the fiber length of the inorganic fibers is too short, leading to insufficient entanglement of the inorganic fibers with each other, reduced winding properties and increased susceptibility to cracking. Also, the above-mentioned turned portions are difficult to form. Furthermore, when the average fiber length of the inorganic fibers exceeds 150 mm, the fiber length of the inorganic fibers is too long, so the number of fibers constituting the mat decreases, and the density of the mat material decreases, resulting in a decrease in the shear strength of the mat material.

[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 a needling treatment is performed, the inorganic fibers are cut, making it difficult to form the above-mentioned turned portions. If the average fiber diameter of the inorganic fibers exceeds 8 μm, the fiber diameter becomes too large, 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 bonds the inorganic fibers together, so that the shape of the mat member 10 is easily maintained. Furthermore, the binder can prevent the inorganic fibers from falling off the mat material 10 and scattering.

[0055] In the mat member 10, the binder may be an organic binder or an inorganic binder, or these may be used in combination. In forming the mat material 10, organic binders and inorganic binders are useful binders. The organic binder is preferably at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethyl cellulose, 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 preferably contains at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice. These organic binders and inorganic binders are suitable for bonding the inorganic fibers together and maintaining the shape of the mat material.

[0056] In the mat member 10, the binder preferably contains an organic binder containing a polymer resin and an inorganic binder containing inorganic particles, and the inorganic particles are preferably dispersed in the polymer resin. When the mat material 10 contains such a binder, the inorganic fibers are bonded together by the binder more strongly, the inorganic fibers can be prevented from scattering from the mat material, and the strength of the mat material is increased. Examples of the polymer resin contained in the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins. Examples of inorganic particles contained in the inorganic binder include inorganic sol dispersions (alumina sol, silica sol, zirconia sol, titania sol, etc.).

[0057] It is preferable that the mat material 10 has a binder concentration gradient in the thickness direction of the mat material, with the weight proportion of the binder increasing 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. FIG. 5 is a cross-sectional view of the mat material of the present invention, which diagrammatically illustrates a first main surface side portion, a central portion, and a 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 into 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 proportion of the binder contained in the first main surface side portion 15 is greater than or equal to the weight proportion of the binder contained in the central portion 16, and that the weight proportion of the binder contained in the first main surface side portion 15 is greater than or equal to the weight proportion of the binder contained in the second main surface side portion 17. Furthermore, in the mat material 10, the weight proportion of the binder contained in the first main surface side portion 15 is greater than the weight proportion of the binder contained in the central portion 16, and it is more preferable that the weight proportion of the binder contained in the first main surface side portion 15 is greater than the weight proportion of the binder contained in the second main surface side portion 17. Furthermore, in the mat member 10, the weight percentage of the binder contained in the second main surface side portion 17 is preferably equal to or lower than the weight percentage of the binder contained in the central portion 16. In addition, in the mat material 10, the weight proportion of the binder contained in the first main surface side portion 15 is greater than the weight proportion of the binder contained in the central portion 16, and it is more preferable that the weight proportion of the binder contained in the central portion 16 is greater than the weight proportion of the binder contained in the second main surface side portion 17.

[0059] The weight percentage of the binder contained in the first main surface side 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 side portion 17 is preferably 0.05 to 5.00 wt %, and more preferably 0.1 to 3.0 wt %.

[0060] In general, when manufacturing a mat material, a solvent containing a binder is applied to the mat material, and then the mat material is subjected to suction, compression, heating, drying, etc. For example, a method of drying by applying hot air can be mentioned. In this process, the binder may be unevenly distributed downward due to gravity, or may be unevenly distributed in large amounts on the main surface that is exposed to the hot air. Therefore, in the produced mat material, a gradient in the weight ratio of the binder is formed in the thickness direction.

[0061] In such a case, the weight ratio of the binder is high near one of the main surfaces of the mat material, and since the inorganic fibers near the main surface on the side where the weight ratio of the binder is high are firmly fixed by the binder, the flexibility of the main surface on the side where the weight ratio of the binder is high is likely to decrease. Here, when the mat material is wound around the exhaust gas treatment body, the main surface on the outer periphery side of the mat material is likely to receive stress in the circumferential direction due to the difference between the inner periphery and the outer periphery of the mat material. Therefore, when the mat material is wrapped around the exhaust gas treatment body so that the main surface on the side with the higher weight ratio of the binder is on the outer periphery, cracks are likely to occur on the main surface on the side with the higher weight ratio of the binder. Conversely, if the mat material is wrapped around the body so that the main surface on the side with the lower weight percentage of the binder faces the outer periphery, cracks are less likely to occur on the main surface on the side with the lower weight percentage of the binder.

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

[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, and the exhaust gas treatment body will easily fall off. In addition, 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 the like will easily occur in the exhaust gas treatment body. If the thickness of the mat material exceeds 40 mm, the mat material loses its flexibility, making it difficult to handle when wrapping it around the exhaust gas treatment body. In addition, the mat material is prone to wrinkles and cracks when wrapped.

[0064] The weight per unit area of ​​the mat material 10 is 200 to 4000 g / m 2 It is preferable that the thickness is 1000 to 3500 g / m 2 It is more preferable that: The weight of the matte material is 200g / m 2 If it is less than this, the holding power is unlikely to be sufficient. The weight of the matte material is 4000g / m 2 If the thickness of the mat material exceeds this value, the bulk of the mat material is difficult to reduce. Therefore, when an exhaust gas purification device is manufactured using such a mat material, the exhaust gas treatment body is likely to fall off.

[0065] The bulk density of the mat material 10 (the bulk density of the mat material before winding) is 0.10 to 0.25 g / cm 3 and preferably 0.10 to 0.20 g / cm 3 It is more preferable that: The bulk density of the mat material is 0.10g / cm 3 If the thickness is less than this, the inorganic fibers will not be entangled well and will be prone to peeling, making it difficult to maintain the mat material in a predetermined shape. The bulk density of the mat material is 0.25g / cm 3 If the thickness exceeds this value, the mat material becomes hard, so that the wrapping property around the exhaust gas treatment body decreases and the mat material becomes more likely to crack.

[0066] The mat material 10 may be subjected to a needling 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 to 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 protrusion mark is formed on the first main surface 11 of the mat material 10, and a second needle mark in which multiple inorganic fibers are entangled is formed in the mat material from the second needle penetration mark to the second needle protrusion mark.

[0068] By carrying out the needling process from both sides of the mat material 10 in this manner, the inorganic fibers constituting the mat material are more entangled, improving the elasticity and strength of the mat material.

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

[0070] The mat material of the present invention can be obtained, for example, by carrying out 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 application step of applying a binder to the mat material. Specific examples of the spinning step, compression step, needling step, baking step and binder impregnation step will be described below.

[0071] [Spinning process] In the spinning step, a spinning mixture containing at least an inorganic compound and an organic polymer is spun to produce an inorganic fiber precursor. In the spinning step, for example, a spinning mixture made from a basic aluminum chloride aqueous solution, silica sol, or the like is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm.

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

[0073] [Needling process] In the needling step, needles are inserted from the first main surface to the second main surface of the sheet obtained in the compression step to perform a needling treatment. At this time, the inorganic fiber precursor is made to form a closed loop at the first needle protrusion 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 described later, the ratio of the diameter of the return portion to the diameter of the first needle marks ([diameter of return portion] / [diameter of first needle marks]) is made to exceed 1.5.

[0074] [Firing process] In the firing step, the sheet is fired, whereby the inorganic fiber precursor is fired to inorganic fibers. The firing temperature is not particularly limited, but is preferably from 1000°C to 1600°C.

[0075] [Binder application process] In the binder impregnation step, the binder is mixed with a solvent, and the solvent containing the binder 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 binder increases from the second main surface side toward the first main surface side of the mat material. For example, by drying the mat material so that hot air is applied to the first main surface, the weight percentage of the binder can be increased from the second main surface side to the first main surface side of the mat material. Furthermore, by leaving the mat material stationary with the second main surface facing up and drying it, the weight proportion of the binder can be increased from the second main surface side to the first main surface side of the mat material. Through the above steps, the mat material of the present invention can be manufactured.

[0076] Next, an exhaust gas purification device of the present invention in which the mat material of the present invention is used will be described. FIG. 6 is a cross-sectional view that illustrates an example of an exhaust gas purification device of the present invention.

[0077] 6, the exhaust gas purification device 100 includes a metal casing 50, an exhaust gas treatment body 60 housed in the metal casing 50, and a mat material 10 disposed between the exhaust gas treatment body 60 and the metal casing 50. The mat material 10 is the mat material of the present invention. As shown in FIG. 6, in the exhaust gas purification device 100, the mat material 10 is disposed so that the first main surface 11 contacts the exhaust gas treatment body and the second main surface 12 contacts the metal casing.

[0078] The exhaust gas treatment body 60 is a columnar structure in which a large number of cells 61 are arranged in parallel in the longitudinal direction with cell walls 62 separating them. Note that, if necessary, 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 are connected to the ends of the metal casing 50. In the exhaust gas purification device 100 shown in FIG. 6, an exhaust gas filter (honeycomb filter) in which one of the cells is sealed with a plugging material 63 is used as the exhaust gas treatment body 60, but a catalyst carrier in which none of the end faces are sealed with a plugging material may also be used.

[0079] As shown in Fig. 6, exhaust gas discharged from an internal combustion engine and flowing into the exhaust gas purification device 100 (in Fig. 6, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by arrows) flows into one cell 61 opening at an exhaust gas inlet end face 60a of the exhaust gas treatment body (honeycomb filter) 60, and passes through a 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 opening at an exhaust gas outlet 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 may be made of an oxidizing porous ceramic such as sialon, alumina, cordierite, mullite, etc. Among these, silicon carbide is preferable.

[0081] When the exhaust gas treatment body 60 is made of porous ceramics of silicon carbide, the porosity of the porous ceramics is not particularly limited, but is preferably 35 to 60%. If the porosity is less than 35%, the exhaust gas treatment body may easily become clogged, whereas if the porosity is more than 60%, the strength of the exhaust gas treatment body may decrease and the body may easily be destroyed.

[0082] 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 cause clogging. If the average pore diameter exceeds 30 μm, PM may pass through the pores, making it impossible to capture PM and thus unable to function as a filter. The porosity and pore size can be measured by a conventionally known method 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 the preferred lower limit is 31.0 cells / cm 2 (200 pieces / inch 2 ), the preferred upper limit is 93.0 particles / cm 2 (600 pieces / inch 2 ) A more preferable lower limit is 38.8 particles / cm 2 (250 pieces / inch 2 ), and a more preferable upper limit is 77.5 particles / cm 2 (500 pieces / inch 2 ).

[0084] The exhaust gas treatment body 60 may support a catalyst for purifying the exhaust gas. The catalyst to be supported is preferably a precious metal such as platinum, palladium, or rhodium, and among these, platinum is more preferable. In addition, other catalysts such as alkali metals such as potassium or sodium, or alkaline earth metals such as barium may also be used. These catalysts may be used alone or in combination of two or more kinds. When these catalysts are supported, PM can be easily burned and removed, and toxic exhaust gas can also be purified.

[0085] (Metal casing) The metal casing 50 is generally cylindrical. The inner diameter of the metal casing 50 (the inner diameter of the portion that houses the exhaust gas treatment body) is preferably 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 preferably made of, but not limited to, stainless steel.

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

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

[0089] The wound body 70 is wound so that the first main surface 11 of the mat material 10 is in contact with the exhaust gas treatment body 60.

[0090] That is, in the wound body 70, the mat material 10 is wound around the exhaust gas treatment body 60 so that the first main surface 11 forms the inner circumference and the second main surface 12 forms the outer circumference. The mat material 10 has a predetermined first needle mark (not shown) and a return portion (not shown) formed therein, so that the return portion provides support near the second main surface and prevents peeling from occurring near the second main surface.

[0091] Therefore, when the exhaust gas purification device 100 is manufactured, peeling of the mat material 10 can be prevented. Therefore, it is possible to prevent the exhaust gas treatment body 60 from falling off due to gas pressure or the like, and to prevent exhaust gas from leaking from the peeled portion of the mat material 10.

[0092] In the above explanation, a wound body in which the mat material 10 is wound around an exhaust gas treatment body is described. However, in the wound body of the present invention, the object around which the mat material is wound is not limited to the exhaust gas treatment body, but may be a pipe or the like that requires heat retention.

[0093] The present specification discloses the following:

[0094] The present disclosure (1) relates to a mat material that includes inorganic fibers and a binder, and has a first main surface and a second main surface opposite to the first main surface, wherein a first needle penetration mark is formed on the first main surface of the mat material, and a first needle protrusion mark is formed on the second main surface of the mat material, and a first needle mark in which a plurality of the inorganic fibers are entangled is formed in the mat material from the first needle penetration mark to the first needle protrusion mark, and in the first needle protrusion mark, the plurality of the inorganic fibers are in a closed loop shape, and a return portion is formed that protrudes from the second main surface, and a ratio of a diameter of the return portion to a diameter of the first needle mark ([diameter of return portion] / [diameter of first needle mark]) exceeds 1.5.

[0095] The present disclosure (2) is a mat material as described in the present disclosure (1), in which 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 percentage of the binder contained in the first main surface side portion is equal to or greater than the weight percentage of the binder contained in the central portion, and the weight percentage of the binder contained in the first main surface side portion is equal to or greater than the weight percentage of the binder contained in the second main surface side portion.

[0096] The present disclosure (3) is a mat material described in the present disclosure (2), in which the weight proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the central portion, and the weight proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the second main surface side portion.

[0097] The present disclosure (4) is a mat material according to the present disclosure (2) or (3), in which the weight proportion of the binder contained in the second main surface side portion is equal to or less than the weight proportion of the binder contained in the central portion.

[0098] The present disclosure (5) is the mat material according to any one of the present disclosures (1) to (4), wherein the binder is an organic binder and / or an inorganic binder.

[0099] The present disclosure (6) is a mat material according to any one of the present disclosures (1) to (5), 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.

[0100] The present disclosure (7) is the mat material according to any one of the present disclosures (1) to (6), wherein the first needle marks have a twisted shape.

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

[0102] The present disclosure (9) is a wound body including a wound body and a mat material wound around the wound body, the mat material being the mat material described in any one of the present disclosures (1) to (8), characterized in that the mat material is wound so that a first main surface of the mat material is in contact with the wound body.

[0103] The present disclosure (10) relates to the wound body according to the present disclosure (9), wherein the wound body is an exhaust gas treatment body.

[0104] The present disclosure (11) provides an exhaust gas purification apparatus comprising 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 being the mat material described in any one of the present disclosures (1) to (8), and the mat material being disposed so that a first main surface of the mat material is in contact with the exhaust gas treatment body. EXAMPLES

[0105] EXAMPLES Hereinafter, examples that more specifically disclose the present invention will be described, however, the present invention is not limited to these examples.

[0106] Example 1 [Spinning process] The aluminum content is 70 g / L, and the composition ratio of the inorganic fiber after firing is 1:1.8 (atomic ratio) in the basic aluminum chloride aqueous solution prepared so that the aluminum content is 70 g / L. 2 O 3 :SiO 2 The silica sol was mixed so that the weight ratio was 72:28, and an appropriate amount of an organic polymer (polyvinyl alcohol) was further added to prepare a mixed liquid. The resulting mixture was concentrated to obtain a spinning mixture, which was then spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 5.1 μm.

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

[0108] [Needling process] The sheet obtained in the above [Compression Step] was continuously subjected to a needling treatment under the conditions shown below. First, there are 9 needles per cm.2 A needle board was prepared in which the needles were attached at a density of 100 μm to the first main surface of the sheet. Next, this needle board was placed on the first main surface of the sheet, and the needle board was inserted and removed once along the thickness direction of the sheet to perform a needling process. At this time, the needles were penetrated until the barbs formed at the tips of the needles completely penetrated the second main surface of the sheet. As a result, the inorganic fiber precursor formed a closed loop in the first needle protrusion mark on the second main surface, and a return portion protruding from the second main surface was formed.

[0109] [Firing process] The needling-treated sheet was continuously fired at a maximum temperature of 1250° C. to produce a mat material made 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 fiber diameter of the inorganic fibers was 3.2 μm. The mat material thus obtained has a bulk density of 0.15 g / cm 3 The basis weight is 1500g / m 2 The density of the first needle marks (density of the first needle penetration marks on the first main surface) was 9 marks / cm 2 It was.

[0110] [Binder application process] Latex, which is an organic binder, was diluted with industrial water to prepare an organic binder solution with an organic binder concentration of 1.0 wt %. Next, an organic binder solution was applied to the mat material using a spray so that the organic binder was 1.0 wt % relative to the amount of inorganic fibers in the mat material.

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

[0112] (Measurement of [diameter of return part] / [diameter of first needle mark]) The mat material according to Example 1 was loosened by hand, and fiber bundles originating from the first needle marks were taken out. A representative photograph of one of the extracted fiber bundles is shown in Figure 8. FIG. 8 is a photograph of fiber bundles originating from the first needle marks included in the mat material according to Example 1. As shown in FIG.

[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 by the above-mentioned method. In the mat material of Example 1, 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]) was 3.4.

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

[0115] Comparative Example 1 The mat material of Comparative Example 1 was manufactured in the same manner as Example 1, except that the needling process was performed by adjusting the barb formed at 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 the return portion] / [diameter of the first needle mark]) in the manufactured mat material was 1.5.

[0116] Comparative Example 2 The mat material of Comparative Example 2 was manufactured in the same manner as Comparative Example 1, except that in the above-mentioned [Binder Application Process], the mat material was dried while being heated and compressed so that the organic binder was concentrated in a large amount on the second main surface side.

[0117] (Wrapping property evaluation) The mat materials according to Example 1 and Comparative Examples 1 and 2 were cut into rectangular pieces with a longitudinal length of 350 mm and a lateral length of 30 mm to prepare test pieces. Next, a cylinder with a diameter of 100 mm was prepared, and each test piece was wrapped around the cylinder so that the first main surface was in contact with the cylinder. At this time, the second main surface of each test piece was visually observed to see if peeling or cracking occurred. The results are shown in Table 1.

[0118] [Table 1]

[0119] As shown in Table 1, it was found that the mat material according to Example 1 was less likely to peel off and less likely to crack when wrapped around a wound body. [Explanation of symbols]

[0120] 10 Mat material 10a sheet 11, 11a 1st main surface 12, 12a Second main surface 13 One end 13a Convex part 14 The other end 14a Recess 15 First main surface side portion 16 Central part 17 Second main surface side portion 20 First needle mark 20´ Shaft 21 First needle penetration mark 22 First needle extrusion 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 end face 60b Exhaust gas exhaust side end surface 61 Cells 62 Cell Wall 63 Encapsulating materials 70 Wrapping body 100 Exhaust gas purification equipment

Claims

1. A mat material including inorganic fibers and a binder, the mat material having a first main surface and a second main surface opposite to the first main surface, a first needle penetration mark is formed on the first main surface of the mat material, a first needle protrusion 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 penetration mark to the first needle protrusion mark, In the first needle protrusion mark, a plurality of the inorganic fibers are formed in a closed loop shape, and a return portion protruding from the second main surface is formed, A mat material characterized in that 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]) exceeds 1.

5.

2. When the mat material is divided into three equal parts in the thickness direction, that is, 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, A mat material as described in claim 1, wherein the weight proportion of the binder contained in the first main surface side portion is greater than or equal to the weight proportion of the binder contained in the central portion, and the weight proportion of the binder contained in the first main surface side portion is greater than or equal to the weight proportion of the binder contained in the second main surface side portion.

3. A mat material as described in claim 2, wherein the weight proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the central portion, and the weight proportion of the binder contained in the first main surface side portion is greater than the weight proportion of the binder contained in the second main surface side portion.

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

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

6. The binder includes an organic binder including a polymer resin and an inorganic binder including inorganic particles, 2. The mat material according to claim 1, wherein the inorganic particles are dispersed in the polymer resin.

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

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

9. A wound body including a wound body and a mat material wound around the wound body, The mat material is the mat material according to any one of claims 1 to 8, The mat material is wound around the wound body such that a first main surface of the mat material is in contact with the wound body.

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

11. An exhaust gas purification device comprising 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 according to any one of claims 1 to 8, The exhaust gas purification device, wherein the mat material is disposed so that a first main surface of the mat material is in contact with the exhaust gas treatment body.

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