Mat material, exhaust gas purification apparatus, and method for manufacturing exhaust gas purification apparatus

Abstract

A mat material that is substantially rectangular in plan view and includes inorganic fibers, the mat material characterized by having a first main surface and a second main surface that face away from each other in the thickness direction, a first end surface and a second end surface that face away from each other in the longitudinal direction serving as a wrapping direction, and a first side surface and a second side surface that face away from each other in the width direction orthogonal to both the thickness direction and the longitudinal direction, the mat material moreover being characterized in that: a projecting section that protrudes toward the second end surface during wrapping, and non-protruding sections that are disposed on both width-direction sides of the projecting section and do not protrude toward the second end surface, are formed on the first end surface; a recessed section that corresponds to the shape of the projecting section of the first end surface during wrapping, and non-sunken sections that are disposed on both width-direction sides of the recessed section and correspond to the shapes of the non-protruding sections of the first end surface, are formed on the second end surface; and the ratio (D / C) of the width-direction length (D) of the non-sunken sections to the longitudinal-direction length (C) of the non-sunken sections is 1.0 or greater.

Description

Mat material, exhaust gas purification device, and method for manufacturing the same

[0001] The present invention relates to a mat material, an exhaust gas purification device, and a method for manufacturing an exhaust gas purification device.

[0002] Particulate matter (hereinafter referred to as PM) is contained in exhaust gases emitted from internal combustion engines such as diesel engines, and in recent years, the harm that this PM poses to the environment and human health has become a problem. Furthermore, because exhaust gases also contain harmful gas components such as CO, HC, and NOx, there are concerns about the impact that these harmful gas components have on the environment and human health.

[0003] Various exhaust gas purification devices have been proposed that capture PM in exhaust gases and purify harmful gas components, and are composed of an exhaust gas treatment body made of porous ceramics such as silicon carbide or cordierite, a casing that houses the exhaust gas treatment body, and a mat material made of an inorganic fiber aggregate that is disposed between the exhaust gas treatment body and the casing. This type of mat material is disposed primarily for the purposes of preventing damage to the exhaust gas treatment body due to contact with the casing that surrounds it due to vibrations and impacts caused by vehicle operation, and preventing exhaust gas from leaking between the exhaust gas treatment body and the casing.

[0004] The mat material is made of inorganic fibers, and its basic shape in plan view is a rectangle consisting of long sides extending in the longitudinal direction and short sides approximately perpendicular to the long sides, with a recess formed on one short side of the rectangle and a protrusion formed on the other short side of the rectangle having a shape similar to the shape cut off by the recess, and the mat material is wrapped around the exhaust gas treatment body and the protrusion is fitted into the recess to prevent exhaust gas from leaking from the mat material. The exhaust gas treatment body wrapped around the mat material is press-fitted into a casing and assembled into the exhaust gas purification device.

[0005] For example, Patent Document 1 discloses that by using a sheet material (mat material) on the first surface whose average unevenness difference h is in the range of 0.4 mm≦h≦9 mm, the contact area between the sheet material and another member is reduced, making it possible to easily attach the sheet material to a predetermined position without using a surface lubricant.

[0006] JP 2011-241837 A

[0007] Patent Document 1 does not mention anything about the detailed dimensions of the recessed and protruding portions, and when the mat material was produced and pressed into place, deformation occurred in a portion of the mat material located at the most upstream side of the fitting portion, and when the exhaust gas treatment body was fixed in a predetermined position, part of the mat material would protrude from the casing.

[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 protrude from a casing when press-fitted.

[0009] That is, the mat material of the present invention is a mat material that contains inorganic fibers and is generally rectangular in plan view, and has first and second main surfaces that face each other in a thickness direction, first and second end surfaces that face each other in a longitudinal direction, which is the winding direction, and first and second side surfaces that face each other in a width direction, which is perpendicular to the thickness direction and the longitudinal direction. The first end surfaces are formed with convex portions that, when wound, protrude toward the second end surfaces, and non-protruding portions that are disposed on both sides of the convex portions in the width direction and do not protrude toward the second end surfaces. The second end surfaces are formed with concave portions that, when wound, correspond to the shape of the convex portions on the first end surfaces, and non-depressed portions that are disposed on both sides of the concave portions in the width direction and correspond to the shape of the non-protruding portions on the first end surfaces. The ratio [D / C] of the length [D] of the non-depressed portions in the width direction to the length [C] of the non-depressed portions in the longitudinal direction is 1.0 or greater.

[0010] When a mat material having corresponding protrusions and recesses as described in Patent Document 1 is wrapped around an exhaust gas treatment body, a portion of the first end face and a portion of the second end face are alternately arranged at the fitting portion where the end faces of the mat material fit together. The portion of the first end face is a protrusion provided on the first end face, and the portion of the second end face is a non-depressed portion provided on the second end face. There are two non-depressed portions on the second end face, one located on the first side face and the other located on the second side face. During wrapping, the shapes of the protrusions on the first end face and the recesses on the second end face correspond to each other, and the shapes of the non-protrusions on the first end face and the non-depressed portions on the second end face correspond to each other. When the mat material is pressed into the casing, shear stress occurs between the exhaust gas treatment body and the casing, which tends to cause deformation in the mat material, pulling it upstream in the press-fit direction. This deformation is particularly likely to occur in the non-depressed portion where there is no structure further upstream to prevent deformation, i.e., the non-depressed portion located most upstream.

[0011] It is believed that the closer a non-depressed portion is to the main mat material body (the portion other than the convex portion and the non-depressed portion), the less likely it is to deform due to shear force, and the further it is from the main mat material body, the more likely it is to deform due to shear force. In other words, the shorter the length of a non-depressed portion, the less likely it is to deform. On the other hand, the longer the width of a non-depressed portion (the distance from the first side surface or the second side surface to the recessed portion), the longer the area in which the non-depressed portion is fixed to the main mat material body, and therefore the less likely it is to deform due to shear force. In other words, it is believed that adjusting the length and width of a non-depressed portion can improve the ease of deformation of the non-depressed portion. Furthermore, the above-mentioned effect is achieved even when there are multiple convex portions on the first end surface and multiple recessed portions on the second end surface.

[0012] In the mat material of the present invention, the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction is 1.0 or greater. Compared to the configuration of Patent Document 1, the above configuration can be said to have a relatively shorter length [C] of the non-depressed portion in the longitudinal direction and a relatively longer length [D] of the non-depressed portion in the width direction. Therefore, when the shape of the mat material satisfies the above conditions, the non-depressed portion is less likely to deform due to shear force during press-fitting, and is less likely to protrude from the casing.

[0013] The mat material of the present invention is preferably a needle mat.

[0014] The mat material of the present invention preferably has a plurality of inter-woven points formed by needling on at least one of its front and back surfaces, and at least one of a first region, which is a 4 mm x 4 mm region where the inter-woven points are not present, and a second region, which is a 3 mm x 8 mm region where the inter-woven points are not present, is disposed within a 25 mm x 25 mm region. When the first region and / or the second region is disposed within the 25 mm x 25 mm region, the surface pressure of the mat material can be increased.

[0015] In the mat material of the present invention, the inorganic fibers preferably have an average fiber length of 1 to 150 mm.

[0016] The mat material of the present invention is preferably a paper-made mat.

[0017] In the mat material of the present invention, the inorganic fibers preferably have an average fiber length of 200 to 20,000 μm.

[0018] In the mat material of the present invention, it is preferable that an inorganic binder is attached to the surfaces of the inorganic fibers. When an inorganic binder is attached to the surfaces of the inorganic fibers, the inorganic binder attached to the surfaces of the inorganic fibers increases the frictional resistance between the inorganic fibers, thereby increasing the holding power.

[0019] In the mat material of the present invention, it is preferable that an organic binder is attached to the surface of the inorganic fibers. When an organic binder is attached to the surface of the inorganic fibers, the adhesion between the inorganic fibers is improved and the inorganic fibers can be prevented from scattering when the mat material is handled.

[0020] In the mat material of the present invention, it is preferable that an inorganic binder and an organic binder are attached to the surfaces of the inorganic fibers. When the inorganic binder is attached to the surfaces of the inorganic fibers, the inorganic binder attached to the surfaces of the inorganic fibers increases the frictional resistance between the inorganic fibers, thereby increasing the holding power. Furthermore, when the organic binder is attached to the surfaces of the inorganic fibers, the adhesion between the inorganic fibers is improved, and the inorganic fibers can be prevented from scattering when the mat material is handled.

[0021] The mat material of the present invention preferably further contains a polymeric dispersant. When the mat material further contains a polymeric dispersant, the organic binder and the inorganic binder can be easily attached to the surface of the inorganic fibers in a dispersed state.

[0022] In the mat material of the present invention, it is preferable that the inorganic binder and the organic binder are attached to the surface of the inorganic fibers in a dispersed state. When the inorganic binder and the organic binder are attached to the surface of the inorganic fibers in a dispersed state, the inorganic binder is dispersed in a coating formed by the organic binder. The coating in this state has excellent mechanical strength, so it can prevent the inorganic fibers from sliding against each other and increase the holding force.

[0023] In the mat material of the present invention, it is preferable that an aggregate composed of the inorganic binder and the organic binder is attached to the surface of the inorganic fibers. When the aggregate composed of the inorganic binder and the organic binder is attached to the surface of the inorganic fibers, friction between the inorganic fibers can be increased, thereby improving holding power.

[0024] In the mat material of the present invention, it is preferable that at least a portion of the surface of the inorganic fibers is covered with a coating layer made of a mixture of the inorganic binder and the organic binder. A coating layer made of a mixture of the inorganic binder and the organic binder has higher mechanical strength than a coating layer made of only the organic binder. Therefore, peeling of the coating layer is less likely to occur, and frictional resistance between the inorganic fibers can be increased.

[0025] In the mat member of the present invention, the coating layer is preferably formed by a continuous scaly mixture of the inorganic binder and the organic binder. When the coating layer is formed by the scaly mixture, the surface roughness of the coating layer increases due to the scaly mixture, thereby further increasing the frictional resistance between the inorganic fibers.

[0026] In the mat member of the present invention, the coating layer preferably has a multi-stage shape, which can further increase the frictional resistance between the inorganic fibers.

[0027] In the mat member of the present invention, it is preferable that a particulate mixture of the inorganic binder and the organic binder is adhered to the surface of the coating layer. When a particulate mixture of the inorganic binder and the organic binder is adhered to the surface of the coating layer, the frictional resistance between the inorganic fibers can be further increased compared to when the coating layer is alone.

[0028] In the mat material of the present invention, it is preferable that the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is equal to or greater than 10. When the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is within the above range, the shape of the non-depressed portion becomes less likely to deform during press-fitting.

[0029] The exhaust gas purification device of the present invention is an exhaust gas purification device having a casing, an exhaust gas treatment body, and a mat material arranged between the casing and the exhaust gas treatment body, and is characterized in that the mat material is the mat material of the present invention.

[0030] Since the exhaust gas purification device of the present invention is equipped with the mat material of the present invention, the mat material does not protrude when pressed in, and the stability of the exhaust gas treatment body is excellent.

[0031] The method for manufacturing an exhaust gas purification device of the present invention is characterized by including a press-fitting step in which the mat material of the present invention is wrapped around an exhaust gas treatment body and then pressed into a casing by a hard stuffing method, a pre-calibration method, or a post-calibration method.

[0032] The hard stuffing method, the pre-calibration method, and the post-calibration method all require a step of press-fitting the exhaust gas treatment body wrapped with the mat material into a casing. Therefore, the mat material of the present invention is particularly suitable for the above methods because it can suppress displacement and deformation of the mat material during press-fitting.

[0033] FIG. 1 is a perspective view schematically showing an example of a mat material according to the present invention. FIG. 2 is a perspective view schematically showing an example of a process of winding the mat material shown in FIG. 1 around an exhaust gas treatment body. FIG. 3 is a perspective view schematically showing an example of a wound body prepared in the process shown in FIG. 2. FIG. 4 is a schematic view showing an example of a press-fitting process of press-fitting the wound body shown in FIG. 3 into a casing. FIG. 5 is a schematic view showing an example of an arrangement of inter-woven points in a mat material according to the present invention. FIG. 6 is a schematic view showing an example of a mat material in which inter-woven points are uniformly arranged. FIG. 7 is an example of an enlarged electron microscope image of a mat material according to the present invention. FIG. 8 is another example of an enlarged electron microscope image of a mat material according to the present invention. FIG. 9 is yet another example of an enlarged electron microscope image of a mat material according to the present invention. FIG. 10 is yet another example of an enlarged electron microscope image of a mat material according to the present invention. FIG. 11 is a conceptual view schematically showing a shear fracture load testing device. FIG. 12 is a cross-sectional view schematically showing an example of an exhaust gas purification device according to the present invention.

[0034] Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied within the scope of the present invention.

[0035] [Mat Material] The mat material of the present invention is a mat material that contains inorganic fibers and is generally rectangular in plan view. The mat material has first and second main surfaces that face each other in a thickness direction, first and second end surfaces that face each other in a longitudinal direction, which is a winding direction, and first and second side surfaces that face each other in a width direction, which is perpendicular to the thickness direction and the longitudinal direction. The first end surfaces are formed with convex portions that, when wound, protrude toward the second end surfaces, and non-protruding portions that are disposed on both sides of the convex portions in the width direction and do not protrude toward the second end surfaces. The second end surfaces are formed with concave portions that, when wound, correspond to the shapes of the convex portions on the first end surfaces, and non-depressed portions that are disposed on both sides of the concave portions in the width direction and correspond to the shapes of the non-protruding portions on the first end surfaces. The ratio [D / C] of the length [D] of the non-depressed portions in the width direction to the length [C] of the non-depressed portions in the longitudinal direction is 1.0 or greater.

[0036] Fig. 1 is a perspective view schematically illustrating an example of a mat material according to the present invention. As shown in Fig. 1, the mat material 10 has a generally rectangular flat plate shape in a plan view, having a first main surface 11 and a second main surface 12 that face each other in the thickness direction (the direction indicated by the double-headed arrow T in Fig. 1), a first end surface 13 and a second end surface 14 that face each other in the longitudinal direction (the direction indicated by the double-headed arrow A in Fig. 1), which is the winding direction, and a first side surface 15 and a second side surface 16 that face each other in the width direction (the direction indicated by the double-headed arrow B in Fig. 1), which is perpendicular to the thickness direction and the longitudinal direction.

[0037] The length of the mat material 10 is indicated by a double-headed arrow A in Fig. 1. The width of the mat material 10 is indicated by a double-headed arrow B in Fig. 1. The thickness of the mat material 10 is indicated by a double-headed arrow T in Fig. 1.

[0038] The first end surface 13 is formed with a convex portion 13a that protrudes toward the second end surface 14 when wound, and non-protruding portions 13b and 13c that do not protrude toward the second end surface 14 and are arranged on both sides of the width of the convex portion 13a.

[0039] The second end face 14 has a recess 14a that corresponds to the shape of the protrusion 13a of the first end face 13 when wound, and non-depressed portions 14b and 14c that are arranged on both sides of the recess 14a in the width direction and correspond to the shapes of the non-protrusions 13b and 13c of the first end face 13, respectively.

[0040] The length of the convex portion 13a in the longitudinal direction (hereinafter simply referred to as the length of the convex portion 13a) is the length indicated by the double-headed arrow C. The shape of the convex portion 13a corresponds to the shape of the concave portion 14a. Therefore, the length of the concave portion 14a in the longitudinal direction (hereinafter simply referred to as the length of the concave portion 14a) is the length indicated by the double-headed arrow C.

[0041] The length of the recess 14a in the width direction (hereinafter simply referred to as the width of the recess 14a) is the length indicated by the double-headed arrow E. The shape of the recess 14a corresponds to the shape of the protrusion 13a. Therefore, the length of the protrusion 13a in the width direction (hereinafter simply referred to as the width of the protrusion 13a) is the length indicated by the double-headed arrow E. Furthermore, the center of the protrusion 13a in the width direction coincides with the center of the recess 14a in the width direction.

[0042] The length of non-depressed portions 14b, 14c in the longitudinal direction (hereinafter simply referred to as the length of non-depressed portions 14b, 14c) is the same as the length of recessed portion 14a in the longitudinal direction, and is the length indicated by the double-headed arrow C. The length of non-depressed portions 14b, 14c in the width direction (hereinafter simply referred to as the width of non-depressed portions 14b, 14c) is the length indicated by the double-headed arrow D. The length of non-protruding portions 13b, 13c in the width direction (hereinafter simply referred to as the width of non-protruding portions 13b, 13c) is the same as the length of non-depressed portions 14b, 14c in the width direction, and is the length indicated by the double-headed arrow D.

[0043] The portion of the mat material 10 excluding the convex portions 13 a and the non-depressed portions 14 b and 14 c is also referred to as the main body portion of the mat material.

[0044] The length [A] of the mat material in the longitudinal direction corresponds to the length from the first end face to the second end face in each cross section when the mat material is cut along a plane parallel to the longitudinal direction and thickness direction.

[0045] In the mat member 10 shown in Fig. 1, when the length of the non-depressed portions 14b, 14c in the longitudinal direction is [D] and the length of the non-depressed portions 14b, 14c in the width direction is [C], the ratio [D / C] of the length [D] of the non-depressed portions 14b, 14c in the longitudinal direction to the length [C] of the non-depressed portions 14b, 14c in the width direction is 1.0 or more. Note that the ratio [D / C] in the mat member 10 shown in Fig. 1 is 2.1.

[0046] As described above, the length of the recess 14a in the longitudinal direction is the same as the length of the non-depressed portions 14b and 14c in the longitudinal direction. The length of the recess 14a in the longitudinal direction is also the same as the length of the protruding portion 13a in the longitudinal direction. The length of the non-depressed portions 14b and 14c in the width direction is also the same as the length of the non-protruding portions 13b and 13c in the width direction.

[0047] From the above, the characteristic of the mat material of the present invention that "the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction is 1.0 or more" can also be rephrased as "the ratio [D / C] of the length [D] of the non-protruding portion in the width direction to the length [C] of the convex portion in the longitudinal direction is 1.0 or more."

[0048] In the mat material of the present invention, the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction is preferably 1.2 or more, and more preferably 1.6 or more.

[0049] In the mat member according to the present invention, the center of the recess in the width direction [E Ｃ ] is the center of the width direction of the mat material [B Ｃ ] may or may not overlap.

[0050] In the mat member 10 shown in FIG. 1, the center of the recess 14a in the width direction [E Ｃ ] is the center [B Ｃ ] overlaps with the non-depressed portion 14c. Therefore, the width of the non-depressed portion 14c is the same as the width of the non-depressed portion 14b, and is the length indicated by the double-headed arrow D. Furthermore, the width of the non-protruding portion 13c is the same as the width of the non-protruding portion 13b, and is the length indicated by the double-headed arrow D.

[0051] The center of the recess in the width direction [E Ｃ ] is the center of the width direction of the mat material [B Ｃ ] do not overlap, the widths of the two non-depressed portions will not match. The width of one non-depressed portion will be shorter than the width of the other non-depressed portion. In this case, the length of the non-depressed portion with the shorter width is used as [D] to calculate the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction.

[0052] Fig. 2 is a perspective view schematically showing an example of a process of winding the mat material shown in Fig. 1 around an exhaust gas treatment body. Fig. 3 is a perspective view schematically showing an example of a wound body prepared in the process shown in Fig. 2.

[0053] As shown in FIG. 2, the mat material 10 is wound around the exhaust gas treatment body 230, thereby obtaining a wound body 250 shown in FIG.

[0054] In Figure 2, the mat material 10 is wrapped around the exhaust gas treatment body 230 so that the first main surface 11 of the mat material 10 is in contact with the exhaust gas treatment body 230, but it may also be wrapped around the exhaust gas treatment body 230 so that the second main surface 12 of the mat material 10 is in contact with the exhaust gas treatment body 230.

[0055] Fig. 4 is a schematic diagram showing an example of a press-fitting step for press-fitting the wound body shown in Fig. 3 into a casing. Fig. 4 shows the state in which the wound body 250 shown in Fig. 3 is press-fitted into the casing 220. The press-fitting direction of the wound body 250 is from top to bottom on the paper. Therefore, of the two side surfaces (first side surface 15 and second side surface 16) of the mat material 10, the second side surface 16 is located downstream in the press-fitting direction, and the first side surface 15 is located upstream in the press-fitting direction.

[0056] When the wound body 250 is press-fitted into the casing 220, a large shear force is applied to the mat material 10 due to friction between the mat material 10 and the casing 220 and friction between the mat material 10 and the exhaust gas treatment body 230. Specifically, a force is applied to the surface of the mat material 10 constituting the wound body 250 such that the surface is pulled toward the upstream side in the press-fitting direction.

[0057] The magnitude of deformation of the convex and non-concave portions due to shear force is determined by the order of their arrangement in the press-fitting direction and the connection area (distance) with the main body of the mat material. That is, the deformation increases toward the upstream side in the press-fitting direction, and the shorter the connection area (distance) with the main body of the mat material, the greater the deformation.

[0058] 4, the non-depressed portion 14b of the mat material 10 is the portion furthest upstream in the press-fitting direction and is the portion most susceptible to deformation due to shear force. However, in the mat material according to the present invention, the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction is 1.0 or greater, so deformation of the non-depressed portion located upstream in the press-fitting direction can be suppressed regardless of the orientation of the mat material.

[0059] In the mat member according to the present invention, the arrangement of the two side surfaces of the mat member during the press-fitting process is not particularly limited. Therefore, as shown in FIG. 4 , the second side surface may be arranged downstream in the press-fitting direction and the first side surface may be arranged upstream in the press-fitting direction, or the first side surface may be arranged downstream in the press-fitting direction and the second side surface may be arranged upstream in the press-fitting direction. However, if the widthwise center of the recess does not overlap with the widthwise center of the mat member, it is preferable that the side surface of the mat member on which the non-depressed portion having a shorter widthwise length is arranged is arranged downstream in the press-fitting direction, and the side surface of the mat member on which the non-depressed portion having a longer widthwise length is arranged is arranged upstream in the press-fitting direction. By arranging the mat member in the above orientation, deformation of the non-depressed portion arranged upstream in the press-fitting direction can be further suppressed.

[0060] For example, if it is assumed that the center of the recess in the width direction does not overlap with the center of the mat material in the width direction, the mat material will have two non-depressed portions with different lengths. In this case, the width of one of the non-depressed portions is D １ , the width of the other non-depressed part is D ２ And D １ >D ２ If so, the non-depressed portion with a shorter width, i.e., the width D ２ The width direction length of the non-depressed portion [D ２ ] to the length [C] of the non-depressed portion in the longitudinal direction [D ２ / C] is 1.0 or more, the matting agent is included in the present invention. １ >D ２ From [D ２ / C] is 1.0 or more, it goes without saying that [D １ / C] is also 1.0 or more. ２ When the side surface of the mat material having the non-depressed portion is arranged on the upstream side in the press-fitting direction, [D ２ / C] is 1.0 or more, the deformation of the non-depressed portion is suppressed. １ When the side surface of the mat material having the non-depressed portion is arranged on the upstream side in the press-fitting direction, [D １ / C] is 1.0 or more, and [D ２ / C], so the width is D ２ In this case, deformation of the non-depressed portion is further suppressed than when the side surface of the mat material having the non-depressed portion is disposed on the upstream side in the press-fitting direction.

[0061] In the mat material of the present invention, the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is not particularly limited, but is preferably 10 or more.

[0062] When the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is 10 or more, the shape of the non-depressed portion becomes less likely to deform during press-fitting. The ratio [A / C] for the mat material 10 shown in Figure 1 is 10.1.

[0063] As described above, the length [C] of the non-depressed portion in the longitudinal direction is the same as the length [C] of the recessed portion and the length [C] of the protruding portion in the longitudinal direction. Therefore, the characteristic of the mat material of the present invention that "the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is 10 or more" can also be rephrased as "the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the protruding portion in the longitudinal direction is 10 or more" or "the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the recessed portion in the longitudinal direction is 10 or more."

[0064] 1 to 4, one convex portion 13a is formed on the first end surface 13 and one concave portion 14a is formed on the second end surface 14. However, in the mat material of the present invention, the number of convex portions formed on the first end surface of the mat material and the number of concave portions formed on the second end surface may be two or more. In this case, the non-depressed portion closest to the first side surface of the mat material and the non-depressed portion closest to the second side surface are focused on, and the ratio [D / C] of the widthwise length [D] of the non-depressed portion to the length [C] of the non-depressed portion is calculated. If both the ratio [D / C] of the non-depressed portion closest to the first side surface of the mat material and the ratio [D / C] of the non-depressed portion closest to the second side surface of the mat material are 1.0 or greater, the mat material corresponds to the present invention.

[0065] In the mat material according to the present invention, the thickness of the mat material is not particularly limited, but is preferably 2 to 40 mm. 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. In addition, the mat material is prone to wrinkles and cracks when wrapped around the exhaust gas treatment body. If the thickness of the mat material is less than 2 mm, the holding power of the mat material is insufficient, making the exhaust gas treatment body more likely to fall off. In addition, if a volume change occurs in the exhaust gas treatment body, the mat material has difficulty absorbing the volume change. As a result, cracks and the like are more likely to occur in the exhaust gas treatment body.

[0066] The mat is configured to include inorganic fibers.

[0067] The inorganic fibers are not particularly limited, but are preferably composed of at least one selected from the group consisting of alumina fibers, silica fibers, alumina-silica fibers, mullite fibers, biosoluble fibers, and glass fibers. When the inorganic fibers are at least one of alumina fibers, silica fibers, alumina-silica fibers, and mullite fibers, they have excellent heat resistance, so even if the exhaust gas treatment body is exposed to sufficiently high temperatures, they do not deteriorate and can fully maintain their function as a mat material. Furthermore, when the inorganic fibers are biosoluble fibers, even if the inorganic fibers scattered during the production of an exhaust gas purification device using the mat material are inhaled, they dissolve in the body and do not pose a risk to the health of workers.

[0068] The alumina fiber may contain additives such as calcia, magnesia, zirconia, etc. in addition to alumina. The composition ratio of the alumina silica fiber is as follows: Al 1:1, 2:2, 3:3, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, 29:1, 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, ２ O ３ : SiO ２ = 60:40 to 80:20, and Al ２ O ３ : SiO ２ It is more preferable that the ratio is 70:30 to 74:26.

[0069] The mat can be produced by a needling method or a papermaking method. A mat produced by the needling method is also called a needle mat, and a mat produced by the papermaking method is also called a paper-made mat.

[0070] In the case of the needling method, the average fiber length of the inorganic fibers is preferably 1 to 150 mm, more preferably 10 to 80 mm. If the average fiber length of the inorganic fibers is less than 1 mm, the inorganic fibers are too short, resulting in insufficient entanglement between each other, which reduces the ability to wrap around the exhaust gas treatment body and makes the mat material more likely to crack. If the average fiber length of the inorganic fibers exceeds 150 mm, the inorganic fibers are too long, resulting in a decrease in the number of fibers constituting the mat material and a decrease in the density of the mat material. As a result, the shear strength of the mat material decreases.

[0071] In the case of papermaking, the average fiber length of the inorganic fibers is preferably 200 to 20,000 μm, more preferably 300 to 10,000 μm, and even more preferably 500 to 1,500 μm.

[0072] In the case of the needling method, interwoven points are formed on the front or back surface of the mat material. The density ρ of the interwoven points is 0.5 pieces / cm ２ ≦ρ<18 pieces / cm ２ In addition, when the inter-woven points are formed on both the front and back surfaces of the mat material, the density ρ of the inter-woven points is the density of the inter-woven points measured on the main surface, either the front surface or the back surface, whichever has a higher density of the inter-woven points.

[0073] In the needling method, it is preferable that at least one of a first region, which is a 4 mm x 4 mm region where no inter-woven points exist, and a second region, which is a 3 mm x 8 mm region where no inter-woven points exist, be arranged within a 25 mm x 25 mm region on the front or back surface of the mat material. The arrangement of at least one of the first region and the second region provides a high surface pressure. The main surface of the mat material used to determine whether the first region and / or the second region exist is the same main surface used to measure the density of the inter-woven points.

[0074] Figure 5 is a schematic diagram showing an example of the arrangement of inter-woven points in the mat material of the present invention. The planar dimensions of the mat material 10 shown in Figure 5 are 25 mm x 25 mm. In Figure 5, multiple inter-woven points 115 are unevenly arranged. Therefore, it can be said that a first region 117, which is a 4 mm x 4 mm region (indicated by a solid square in Figure 5) where no inter-woven points 115 exist, and a second region 118, which is a 3 mm x 8 mm region (indicated by a dashed rectangle in Figure 5) where no inter-woven points 115 exist, are arranged. Note that Figure 5 does not show all of the first region 117 and second region 118.

[0075] FIG. 6 is a schematic diagram showing an example of a mat material in which inter-woven points are uniformly arranged. The planar dimensions of the mat material 10 shown in FIG. 6 are 25 mm x 25 mm. In FIG. 6, the inter-woven points 115 are uniformly arranged at 2.8 mm intervals. Each of the 4 mm x 4 mm squares and 3 mm x 8 mm rectangles shown in FIG. 6 contains one or more inter-woven points. The 4 mm x 4 mm squares that do not correspond to the first region and the 3 mm x 8 mm rectangles that do not correspond to the second region are marked with an "X". Therefore, neither the first region nor the second region can be arranged in the mat material shown in FIG. 6.

[0076] The method for counting the number of first regions and second regions within a 25 mm x 25 mm region is as follows: (1) Find a 4 mm x 4 mm region (first region) where no inter-woven points are formed. At this time, select multiple first regions so that they do not overlap with each other. (2) Find a 3 mm x 8 mm region (second region) where no inter-woven points are formed. At this time, select multiple second regions so that they do not overlap with each other. However, the second region may overlap with the first region. If the second region and the first region overlap, the area without inter-woven points becomes larger, thereby increasing the surface pressure of the mat material. (3) Select a 25 mm x 25 mm region where the number of first regions that do not overlap with each other and the number of second regions that do not overlap with each other are maximized. The above operation is performed on 10 samples, and the average value is calculated. The above operation may also be performed using commercially available image processing software, etc.

[0077] It is preferable that a plurality of first regions and / or second regions are arranged in a 25 mm x 25 mm area. When a plurality of first regions and / or second regions are arranged in a 25 mm x 25 mm area, the surface pressure of the mat material can be increased. "A plurality of first regions and / or second regions" means that the total number of first regions and the number of second regions is two or more, and includes cases where a plurality of first regions are arranged, a plurality of second regions are arranged, and a plurality of first regions and a plurality of second regions are arranged.

[0078] It is preferable that a third region, which is a 4 mm x 4 mm region having four or more interwoven points, is arranged within a 25 mm x 25 mm region on the front or back surface of the mat material. When the third region is arranged, the inorganic fibers are strongly entangled with each other in the third region, thereby increasing the shear strength of the mat material. The method for counting the number of third regions within the 25 mm x 25 mm region is the same as the method for counting the number of first regions described above.

[0079] It is preferable that an inorganic binder (also referred to as an inorganic binding agent) is attached to the surface of the inorganic fiber. When an inorganic binder is attached to the surface of the inorganic fiber, the inorganic binder attached to the surface of the inorganic fiber increases the frictional resistance between the inorganic fibers, thereby increasing the holding power.

[0080] Examples of the inorganic binder include alumina sol and silica sol.

[0081] It is preferable that an organic binder (also referred to as an organic bonding agent) is attached to the surface of the inorganic fibers. When an organic binder is attached to the surface of the inorganic fibers, the adhesion between the inorganic fibers is improved and the inorganic fibers can be prevented from scattering when the mat material is handled.

[0082] Examples of organic binders include water-soluble organic polymers such as acrylic resin, acrylate latex, rubber latex, carboxymethyl cellulose or polyvinyl alcohol, thermoplastic resins such as styrene resin, and thermosetting resins such as epoxy resin.

[0083] It is preferable that an inorganic binder and an organic binder are attached to the surface of the inorganic fibers. When the inorganic binder is attached to the surface of the inorganic fibers, the frictional resistance between the inorganic fibers increases due to the inorganic binder attached to the surface of the inorganic fibers, thereby increasing the holding power. Furthermore, when the organic binder is attached to the surface of the inorganic fibers, the adhesion between the inorganic fibers is improved, and the inorganic fibers can be prevented from scattering when handling the mat material.

[0084] The weight ratio of the inorganic binder to the mat material (weight of inorganic binder / weight of mat material) is preferably more than 0 wt % and not more than 10 wt %. When the weight ratio of the inorganic binder to the mat material is in the above range, the holding power can be sufficiently increased.

[0085] The weight ratio of the organic binder to the mat material (weight of the organic binder / weight of the mat material) is preferably more than 0 wt % and not more than 10 wt %. When the weight ratio of the organic binder to the mat material is in this range, both the effect of preventing fiber scattering and high retention force can be achieved.

[0086] The contents of the organic binder and inorganic binder contained in the mat material can be measured, for example, by the following method. First, a fixed weight sample of the mat material whose contents are to be measured is collected. Next, an organic solvent (e.g., tetrahydrofuran) in which the organic binder contained in the sample dissolves is selected, and the organic binder is dissolved using a Soxhlet extractor and separated from the sample. At this time, the inorganic binder contained in the dissolved organic binder is also separated from the sample, and the organic binder and inorganic binder are recovered in the organic solvent. Next, the organic solvent containing the organic binder and the inorganic binder is placed in a crucible, and the organic solvent is evaporated and removed by heating. The residue remaining in the crucible is considered to be the total weight of the organic binder and the inorganic binder relative to the weight of the mat material, and the content (wt%) relative to the weight of the mat material is calculated. Next, the crucible is heated at 600°C for 1 hour to burn off the organic binder. Since the inorganic binder remains in the crucible, this is considered to be the inorganic binder content (wt%) relative to the total of the organic binder and inorganic binder, and the content is calculated. The remainder is the content (wt %) of the organic binder.

[0087] In the mat material, it is preferable that the inorganic binder and the organic binder are attached to the surface of the inorganic fibers in a dispersed state. When the inorganic binder and the organic binder are attached to the surface of the inorganic fibers in a dispersed state, the inorganic binder is dispersed in a coating formed by the organic binder. The coating in this state has excellent mechanical strength, so it can prevent the inorganic fibers from sliding against each other and increase the holding force.

[0088] In the mat material, it is preferable that at least a portion of the surface of the inorganic fibers is covered with a coating layer made of a mixture of an inorganic binder and an organic binder. A coating layer made of a mixture of an inorganic binder and an organic binder has higher mechanical strength than a coating layer made of only an organic binder. Therefore, peeling of the coating layer is less likely to occur, and frictional resistance between the inorganic fibers can be increased.

[0089] The coating layer is preferably formed by a continuous flake-like mixture (a mixture of an inorganic binder and an organic binder). When the coating layer is formed by the flake-like mixture, a large number of irregularities resulting from the flake-like mixture are formed on the surface of the coating layer, which can further increase the frictional resistance between the inorganic fibers.

[0090] Figure 7 is an example of an enlarged electron microscope image of the mat material of the present invention. As shown in Figure 7, a portion of the surface of the inorganic fibers 120 is covered with a coating layer 130 made of a mixture of an inorganic binder and an organic binder. The coating layer 130 is formed by a continuous flake-like mixture of the inorganic binder and the organic binder. A particulate mixture 140 of the inorganic binder and the organic binder is attached to the surface of the inorganic fibers 120. Whether the coating layer or particles are made of a mixture of the inorganic binder and the organic binder can be confirmed by combining visual observation using an electron microscope with elemental analysis.

[0091] Figure 8 is another example of an enlarged electron microscope image of the mat material of the present invention. As shown in Figure 8, a coating layer 130 made of a mixture of an inorganic binder and an organic binder covers a portion of the surface of the inorganic fiber 120. The coating layer 130 is formed by a continuous flake-like mixture of the inorganic binder and the organic binder. A particulate mixture 140 of the inorganic binder and the organic binder adheres to the surface of the inorganic fiber 120.

[0092] The thickness of the coating layer may be uniform, but it does not have to be uniform. A coating layer with an uneven thickness is also called a multi-step shape. If the coating layer has a multi-step shape, it can be said that the coating layer has an uneven surface, and the frictional resistance between the inorganic fibers can be further increased. Whether the coating layer has an uneven surface, that is, whether the coating layer has a multi-step shape, can be determined by magnifying the surface of the inorganic fiber using a scanning electron microscope at 3000 times and confirming the presence or absence of unevenness on the surface of the coating layer.

[0093] Figure 9 is another example of an enlarged electron microscope image of the mat material of the present invention. As shown in Figure 9, a coating layer 130 made of a mixture of an inorganic binder and an organic binder covers a portion of the surface of the inorganic fibers 120. The coating layer 130 does not have a uniform thickness but has multiple layers. A particulate mixture 140 of the inorganic binder and the organic binder adheres to the surface of the inorganic fibers 120.

[0094] It is preferable that particles made of a mixture of an inorganic binder and an organic binder are attached to the surface of the coating layer. When particles made of a mixture of an inorganic binder and an organic binder are attached to the surface of the coating layer, the frictional resistance between the inorganic fibers can be further increased compared to when the particles are not attached.

[0095] Figure 10 is yet another example of an enlarged electron microscope image of the mat material of the present invention. As shown in Figure 10, a portion of the surface of the inorganic fiber 120 is covered with a coating layer 130 made of a mixture of an inorganic binder and an organic binder. The coating layer 130 is formed by a series of scale-like mixtures of the inorganic binder and the organic binder. The thickness of the coating layer 130 is not uniform, but rather has multiple layers. A particulate mixture 140 of the inorganic binder and the organic binder adheres to the surface of the coating layer 130.

[0096] The matting material preferably further contains a polymeric dispersant. When the matting material further contains a polymeric dispersant, the organic binder and the inorganic binder are easily attached to the surface of the inorganic fibers in a dispersed state. The content of the polymeric dispersant is preferably 50 to 1000 ppm relative to the weight of the inorganic fibers.

[0097] The mat material preferably has an aggregate of an inorganic binder and an organic binder attached to the surface of the inorganic fibers. The aggregate of the inorganic binder and the organic binder can form irregularities on the surface of the inorganic fibers, thereby increasing friction between the inorganic fibers and improving holding power.

[0098] The mat material may further contain a flocculant, which makes it easier for the organic binder and the inorganic binder to be attached to the surface of the inorganic fibers in an aggregated state.

[0099] Whether the inorganic binder and organic binder attached to the surface of the inorganic fiber are dispersed or aggregated can be confirmed by observing the surface of the inorganic fiber with SEM-EDX or the like.

[0100] The mat material of the present invention preferably has a shear coefficient of 0.20 or more. When the shear coefficient is 0.20 or more, shear is less likely to occur in the mat material when the exhaust gas treatment body is press-fitted into a casing using the mat material of the present invention. The shear coefficient can be calculated by dividing the shear failure load by the relaxation surface pressure.

[0101] The shear fracture load can be measured using a shear fracture load testing device shown in Figure 11. Figure 11 is a conceptual diagram that schematically illustrates the shear fracture load testing device. In the shear fracture load testing device 170 shown in Figure 11, test pieces 1a and 1b are arranged on both sides of a stainless steel plate 173, and the outside of the test pieces is further sandwiched between a left jig 171 and a right jig 172. A number of protruding members 174 are provided on the surfaces of the left jig 171, the right jig 172, and the stainless steel plate 173 that come into contact with the test pieces. The test pieces 1a and 1b are fixed to the left jig 171, the right jig 172, and the stainless steel plate 173 by being pierced by the protruding members 174. In this state, when the bulk density (GBD) of the test pieces is 0.3 g / cm ３ The stainless steel plate 173 is then moved in the direction indicated by the arrow in FIG. 11 (upward) at a speed of 5 mm / min. Since the stainless steel plate 173 is fixed to the test pieces 1a and 1b by the protruding members 174, it cannot be separated from the test pieces 1a and 1b and removed. Therefore, when a shear force equal to or greater than the shear fracture load of the test pieces is applied to the test pieces 1a and 1b, the test pieces 1a and 1b will undergo shear fracture. The shear force applied to the stainless steel plate when the test pieces undergo shear fracture is determined.

[0102] The shear fracture load (kPa) can be determined by dividing the obtained shear force by the area of ​​the test piece. The shear fracture load may also be measured using a test piece cut out from a part of the mat material.

[0103] The relaxation surface pressure can be measured by the following procedure. First, the bulk density of the mat material is measured at room temperature. ３ The load is measured after the compression is maintained for 20 minutes.

[0104] The relaxation surface pressure (kPa) can be determined by dividing the load obtained by the area of ​​the test piece. Note that the relaxation surface pressure may also be measured using a test piece cut out from a part of the mat material.

[0105] The surface pressure of the mat material after firing is preferably 50 kPa or more. The surface pressure of the mat material after firing can be measured by the following method using a hot surface pressure measuring device equipped with a heater on the plate portion that compresses the mat material to be used as a test piece. First, a test piece having a bulk density of 0.3 g / cm at room temperature is measured. ３ The test piece (mat material) is compressed until the bulk density reaches 0.27 g / cm3, and then held for 10 minutes. After that, the test piece is heated in a compressed state at a temperature rising rate of 45°C to 900°C on one side and 650°C on the other side, and the temperature is increased until the bulk density reaches 0.27 g / cm3. ３ The compression is then released and held for 5 minutes until the bulk density reaches 0.3 / cm. After that, the plate compressing the mat material is moved at a speed of 1 inch (25.4 mm) / min. ３ The bulk density is 0.27 g / cm ３ Release of compression until the bulk density is 0.3 g / cm ３ After 1000 cycles of compression, the bulk density was 0.27 g / cm ３ The load obtained is divided by the area of ​​the test piece to determine the surface pressure (kPa), which is taken as the surface pressure after firing.

[0106] [Method for Producing Mat Material] The mat material of the present invention can be obtained, for example, by carrying out a cutting step of cutting a mat containing inorganic fibers into a predetermined shape, or a molding step of molding the mat into a predetermined shape.

[0107] The mat can be obtained by, for example, a needling method or a papermaking method.

[0108] In the case of the needling method, for example, a mat can be obtained 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-like material, a needle-punching step of needle-punching at least one surface of the sheet-like material to produce a needle-punched body, and a firing step of firing the needle-punched body. Specific examples of the spinning step, compression step, needle-punching step, and firing step are described below.

[0109] [Spinning Process] In the spinning process, a spinning mixture containing at least an inorganic compound and an organic polymer is spun to produce an inorganic fiber precursor. In the spinning process, for example, a spinning mixture made from a basic aluminum chloride aqueous solution and silica sol or the like as raw materials is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm.

[0110] [Compression Step] In the compression step, the inorganic fiber precursor obtained in the spinning step is compressed to produce a continuous sheet-like material of a predetermined size.

[0111] [Needle-punching step] In the needle-punching step, needle-punching is performed on at least one surface of the sheet-like material obtained in the compression step to produce a needle-punched body.

[0112] In the needle punching process, the needle placement density was set to 0.5 needles / cm ２ Over 18 strands / cm ２ The positions where the needles are arranged in the needle punching process correspond to the intertwining points in the mat. Therefore, it is preferable to set the needle arrangement density to 0.5 needles / cm ２ Over 18 strands / cm ２ By setting the density ρ to less than 0.5 pieces / cm3, the density ρ of the inter-woven points can be reduced to 0.5 pieces / cm3 by one needle punching treatment. ２ ≦ρ<18 pieces / cm ２ However, when needle punching is performed multiple times on the same sheet material, the needle arrangement density is not limited to the above range.

[0113] In addition, by intentionally biasing the arrangement of needles in the needle punching process, the arrangement of the interwoven points formed in the needle punched body is varied in density, and the density ρ of the interwoven points is set to 0.5 pieces / cm ２ ≦ρ<18 pieces / cm ２ While keeping the range of the inter-woven points at 25 mm × 25 mm, a 4 mm × 4 mm region (first region) where no inter-woven points exist and / or a 3 mm × 8 mm region (second region) where no inter-woven points exist can be formed within the 25 mm × 25 mm region.

[0114] Examples of methods for intentionally biasing the arrangement of the inter-woven points include a method in which needle-punching is performed so as to uniformly arrange the inter-woven points, and then additional needling is performed on a portion of the material. Other examples include a method in which needle-punching is performed multiple times while moving the inorganic fiber precursor, and a method in which needle-punching is performed using a needle board in which needles are not arranged at equal intervals.

[0115] In the needle punching step, the needles may or may not penetrate the sheet material in the thickness direction.

[0116] [Firing step] In the firing step, the needle-punched body is fired to obtain a mat made of inorganic fibers. The temperature at which the needle-punched body is fired is not particularly limited, but is preferably 1000° C. to 1600° C. A mat can be obtained by the above steps.

[0117] [Cutting Step] The mat obtained in the above step can be cut into a predetermined shape to obtain the mat material of the present invention.

[0118] In producing the mat material of the present invention, an impregnation step may be carried out in which an inorganic binder and / or an organic binder is impregnated onto the surface of the inorganic fibers that constitute the mat or mat material.

[0119] [Impregnation Step] In the impregnation step, an inorganic binder and / or an organic binder is impregnated onto the mat. When there is no need to distinguish between the inorganic binder and the organic binder, they are also simply referred to as binders.

[0120] Examples of the inorganic binder include alumina sol and silica sol.

[0121] Examples of organic binders include water-soluble organic polymers such as acrylic resin, acrylate latex, rubber latex, carboxymethyl cellulose or polyvinyl alcohol, thermoplastic resins such as styrene resin, and thermosetting resins such as epoxy resin.

[0122] Examples of methods for attaching a binder to a mat include a method of bringing a binder mixture, which is a mixture of a solvent and a binder, into contact with the mat and then drying the mixture. Examples of methods for bringing the binder mixture into contact with the mat include a method of immersing the mat in the binder mixture, and a method of dropping the binder mixture onto the mat by a curtain coating method or the like.

[0123] The content of the inorganic binder in the binder mixture is preferably 0.05 wt % or more and 5 wt % or less. The content of the organic binder in the binder mixture is preferably 0.05 wt % or more and 5 wt % or less. That is, the binder mixture may contain only an inorganic binder as a binder, may contain only an organic binder, or may contain both an inorganic binder and an organic binder.

[0124] The binder mixture may contain a polymeric dispersant. When the binder mixture contains a polymeric dispersant, the binder is dispersed in the binder mixture. By bringing the binder mixture in this state into contact with the mat, the binder can be attached to the surface of the inorganic fibers in a dispersed state.

[0125] Examples of polymeric dispersants include anionic polymeric dispersants such as polycarboxylic acids and / or their salts, naphthalenesulfonate-formalin condensates and / or their salts, polyacrylic acids and / or their salts, polymethacrylic acids and / or their salts, and polyvinylsulfonic acids and / or their salts; nonionic polymeric dispersants such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol; hydrophilic synthetic polymeric substances; natural hydrophilic polymeric substances such as gelatin, casein, and water-soluble starch; and hydrophilic semi-synthetic polymeric substances such as carboxymethyl cellulose. Among these, hydrophilic synthetic polymeric substances are preferred, and anionic polymeric dispersants are more preferred. These polymeric dispersants may be used alone or in combination. Alternatively, polymeric dispersants may have both a structure exhibiting properties as an anionic polymeric dispersant and a structure exhibiting properties as a nonionic polymeric dispersant.

[0126] The binder mixture may contain a flocculant. When the binder mixture contains a flocculant, the binder is in an agglomerated state in the binder mixture. By bringing the binder mixture in this state into contact with the mat, the binder can be attached to the surface of the inorganic fibers in an agglomerated state.

[0127] The binder mixture may contain a polymeric dispersant. When the binder mixture contains a polymeric dispersant, the binder is dispersed in the binder mixture. That is, the binder mixture becomes a dispersion in which the binder is dispersed in a dispersion medium. By bringing the binder mixture (dispersion) in this state into contact with the mat, the binder can be attached to the surface of the inorganic fibers in a dispersed state.

[0128] The binder mixture may contain a flocculant. When the binder mixture contains a flocculant, the binder is in an agglomerated state in the mixture. That is, the binder mixture becomes an agglomerated dispersion in which aggregates formed by agglomeration of the binder are dispersed in a dispersion medium. By bringing the mixture (agglomerated dispersion) in this state into contact with the mat, the binder can be attached in an agglomerated state to the surface of the inorganic fibers.

[0129] In the impregnation step, the impregnation of the inorganic binder and the impregnation of the organic binder may be performed separately. Examples of methods for separately impregnating the inorganic binder and the organic binder include a method in which an inorganic binder mixed solution containing an inorganic binder is brought into contact with the mat to impregnate the inorganic binder, and then the mat is brought into contact with an organic binder mixed solution containing an organic binder to impregnate the organic binder. The order in which the inorganic binder and the organic binder are impregnated is not particularly limited, and either the inorganic binder or the organic binder may be impregnated first.

[0130] By the above steps, the mat material of the present invention can be obtained in which the inorganic binder and / or organic binder is attached to the surface of the inorganic fibers.

[0131] Next, a papermaking method will be described. In the papermaking method, for example, a mat can be obtained by a fiber-opening process of opening inorganic fibers, a slurry preparation process of mixing the opened inorganic fibers with a solvent, an inorganic binder, and an organic binder to prepare a slurry, a papermaking process of papermaking the slurry to obtain an inorganic fiber aggregate, and a drying process of drying the inorganic fiber aggregate. Specific examples of the fiber-opening process, the slurry preparation process, the papermaking process, and the drying process will be described below.

[0132] [Opening Process] In the opening process, inorganic fibers are shortened (also called opening) by a grinder such as a feather mill or an agitator such as a pulper, and adjusted to a desired fiber length.

[0133] The shortened inorganic fibers may be subjected to classification treatment as needed, and it is preferable to perform classification treatment so as to remove part or all of the inorganic fibers having a fiber length of 200 μm or less.

[0134] Examples of the classification treatment include classification treatment using a dry centrifugal classifier (also called a dry cyclone) and a wet centrifugal classifier (also called a wet cyclone).

[0135] [Slurry Preparation Step] In the slurry preparation step, the opened inorganic fibers are mixed with a solvent, an inorganic binder, and an organic binder to prepare a slurry.

[0136] The order of mixing the inorganic binder and the organic binder is not particularly limited, but it is preferable to first mix the inorganic fibers and the inorganic binder, let it stand for a while, and then add the organic binder. By mixing the inorganic fibers and the inorganic binder first, the inorganic binder is reliably attached to the surface of the inorganic fibers, which increases the friction between the inorganic fibers and improves the surface pressure. Furthermore, aggregates obtained by aggregating the organic binder and the inorganic binder with a flocculant may be added to the above slurry.

[0137] [Papermaking process (molding process)] In the papermaking process, the slurry is poured into a molding machine with a filtration mesh formed on the bottom surface, and then the solvent in the slurry is removed to obtain an inorganic fiber aggregate. The shape of the molding machine at this time determines the shape of the mat. In other words, the papermaking process can also be said to serve as a molding process. Therefore, it is preferable to shape the molding machine in the shape of the mat material to be obtained.

[0138] The solvent removal treatment is not particularly limited as long as it can remove the solvent contained in the mat. For example, the solvent can be removed by means of compression, rotation, suction, decompression, or the like.

[0139] [Drying Step] In the drying step, the inorganic fiber aggregate is dried while being compressed using a method such as compression drying with a hot plate using a press dryer, etc. Through the above steps, the mat material of the present invention can be obtained in which the inorganic binder and / or organic binder is attached to the surface of the inorganic fibers.

[0140] [Exhaust gas purification device] The exhaust gas purification device of the present invention is an exhaust gas purification device comprising an exhaust gas treatment body, a casing that houses the exhaust gas treatment body, and a mat material that is arranged between the exhaust gas treatment body and the casing and holds the exhaust gas treatment body, wherein the mat material is the mat material of the present invention.

[0141] In the exhaust gas purification device of the present invention, the mat material of the present invention is disposed between the exhaust gas treatment body and the casing, and therefore the exhaust gas treatment body can be stably held.

[0142] Fig. 12 is a cross-sectional view schematically illustrating an example of an exhaust gas purification apparatus of the present invention. As shown in Fig. 12, the exhaust gas purification apparatus 200 includes a casing 220, an exhaust gas treatment body 230 housed in the casing 220, and a mat material 10 disposed between the exhaust gas treatment body 230 and the casing 220. The mat material 10 is the mat material of the present invention. The exhaust gas treatment body 230 is a columnar body having a large number of cells 231 arranged in parallel in the longitudinal direction, separated by cell walls 232. Note that, as necessary, an inlet pipe for introducing exhaust gas emitted from an internal combustion engine and an outlet pipe for discharging exhaust gas that has passed through the exhaust gas purification apparatus to the outside are connected to the ends of the casing 220. In the exhaust gas purification device 200 shown in Figure 12, an exhaust gas filter (honeycomb filter) in which one of the cells is sealed with a plugging material 233 is used as the exhaust gas treatment body 230, but a catalyst carrier in which none of the end faces are sealed with a plugging material may also be used.

[0143] As shown in Figure 12, exhaust gas discharged from an internal combustion engine and flowing into the exhaust gas purification device 200 (in Figure 12, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by arrows) flows into one cell 231 opening at the exhaust gas inlet end face 230a of the exhaust gas treatment body (honeycomb filter) 230 and passes through a cell wall 232 separating the cells 231. At this time, PM in the exhaust gas is captured by the cell wall 232, and the exhaust gas is purified. The purified exhaust gas flows out from the other cell 231 opening at the exhaust gas outlet end face 230b and is discharged to the outside.

[0144] The exhaust gas inlet end surface 230a and the exhaust gas outlet end surface 230b, which are determined by the direction of the exhaust gas flowing into the exhaust gas purification device, are independent of the direction at the time of press-fitting.

[0145] [Method for manufacturing exhaust gas purification device] The method for manufacturing an exhaust gas purification device of the present invention is characterized by including a press-fitting step of wrapping the mat material of the present invention around an exhaust gas treatment body and then press-fitting it into a casing by a hard stuffing method, a pre-calibration method, or a post-calibration method.

[0146] The hard stuffing method, the pre-calibration method, and the post-calibration method all require a step of press-fitting the exhaust gas treatment body wrapped with the mat material into a casing. Therefore, the mat material of the present invention is particularly suitable for the above methods because it can suppress displacement and deformation of the mat material during press-fitting.

[0147] The hard stuffing method is a method in which a cylindrical casing having a predetermined inner diameter is prepared in advance, and an exhaust gas treatment body with a mat material wrapped around it is press-fitted into this casing. The pre-calibration method is a method in which a cylindrical casing having a predetermined inner diameter is once reduced in diameter, and then the exhaust gas treatment body with the mat material wrapped around it is press-fitted into the casing. The post-calibration method is a method in which an exhaust gas treatment body with the mat material wrapped around it is press-fitted into a cylindrical casing having a predetermined inner diameter, and then the casing is reduced in diameter together with the exhaust gas treatment body and the mat material.

[0148] In all of the above methods, a large shear force is applied to the mat material during press-fitting, which tends to cause displacement and deformation of the mat material. In contrast, the mat material of the present invention can suppress displacement and deformation of the mat material during press-fitting, and is therefore particularly suitable for the manufacturing method of an exhaust gas purification device that includes these press-fitting steps.

[0149] In the method for manufacturing an exhaust gas purification device of the present invention, in the press-fitting step, it is preferable to press-fit the mat material into the casing with the first side surface on the upstream side and the second side surface on the downstream side. In particular, when the width direction length of the non-depressed portion arranged on the first side surface side is longer than the width direction length of the non-depressed portion arranged on the second side surface side, it is preferable to press-fit the mat material into the casing with the first side surface on the upstream side and the second side surface on the downstream side.

[0150] The present specification discloses the following:

[0151] The present disclosure (1) relates to a mat material that is generally rectangular in plan view and contains inorganic fibers, the mat material having first and second main surfaces that face each other in a thickness direction, first and second end surfaces that face each other in a longitudinal direction, which is a winding direction, and first and second side surfaces that face each other in a width direction, which is perpendicular to the thickness direction and the longitudinal direction, the first end surfaces being formed with convex portions that, when wound, protrude toward the second end surfaces, and non-protruding portions that are disposed on both sides of the convex portions in the width direction and do not protrude toward the second end surfaces, the second end surfaces being formed with concave portions that, when wound, correspond to the shapes of the convex portions on the first end surfaces, and non-depressed portions that are disposed on both sides of the concave portions in the width direction and correspond to the shapes of the non-protruding portions on the first end surfaces, the ratio [D / C] of the length [D] of the non-depressed portions in the width direction to the length [C] of the non-depressed portions in the longitudinal direction is 1.0 or greater.

[0152] The present disclosure (2) is the mat material according to the present disclosure (1), which is a needle mat.

[0153] The present disclosure (3) is the mat material according to the present disclosure (2), which has a plurality of interwoven points formed by needling on at least one of the front and back surfaces, and in which at least one of a first region, which is a 4 mm x 4 mm region where the interwoven points are not present, and a second region, which is a 3 mm x 8 mm region where the interwoven points are not present, is arranged within a 25 mm x 25 mm region.

[0154] The present disclosure (4) is the mat material according to the present disclosure (2) or (3), in which the inorganic fibers have an average fiber length of 1 to 150 mm.

[0155] The present disclosure (5) is the mat material according to the present disclosure (1), which is a paper-made mat.

[0156] The present disclosure (6) is the mat material according to the present disclosure (5), in which the inorganic fibers have an average fiber length of 200 to 20,000 μm.

[0157] The present disclosure (7) is a mat material in any combination with any of the present disclosures (1) to (6), in which an inorganic binder is attached to the surface of the inorganic fibers.

[0158] The present disclosure (8) is a mat material in any combination with any of the present disclosures (1) to (6), in which an organic binder is attached to the surface of the inorganic fibers.

[0159] The present disclosure (9) is a mat material in any combination with any of the present disclosures (1) to (6), in which an inorganic binder and an organic binder are attached to the surface of the inorganic fibers.

[0160] The present disclosure (10) is a mat material in any combination with any of the present disclosures (1) to (9), which further contains a polymeric dispersant.

[0161] The present disclosure (11) is the mat material according to the present disclosure (9), in which the inorganic binder and the organic binder are attached to the surface of the inorganic fibers in a dispersed state.

[0162] The present disclosure (12) is the mat material according to the present disclosure (9), in which an aggregate composed of the inorganic binder and the organic binder is attached to the surface of the inorganic fibers.

[0163] The present disclosure (13) is the mat material according to the present disclosure (12), in which at least a part of the surface of the inorganic fibers is covered with a coating layer made of a mixture of the inorganic binder and the organic binder.

[0164] The present disclosure (14) is the mat material according to the present disclosure (13), wherein the coating layer is formed by a continuous scaly mixture of the inorganic binder and the organic binder.

[0165] The present disclosure (15) is the mat material according to the present disclosure (13) or (14), in which the coating layer has a multi-stage shape.

[0166] The present disclosure (16) is a mat material in any combination with any of the present disclosures (13) to (15), in which a particulate mixture of the inorganic binder and the organic binder is attached to the surface of the coating layer.

[0167] The present disclosure (17) is a mat material in any combination with any of the present disclosures (1) to (16), in which the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is 10 or more.

[0168] The present disclosure (18) is an exhaust gas purification device having a casing, an exhaust gas treatment body, and a mat material disposed between the casing and the exhaust gas treatment body, characterized in that the mat material is any combination of mat materials with any of the present disclosures (1) to (17).

[0169] The present disclosure (19) is a manufacturing method for an exhaust gas purification device, characterized by including a press-fitting step of wrapping a mat material in any combination with any of the present disclosures (1) to (17) around an exhaust gas treatment body, and then press-fitting the mat material into a casing by a hard stuffing method, a pre-calibration method, or a post-calibration method.

[0170] Examples that more specifically disclose the present invention are shown below. In the following examples, mats are produced by a needling method, but the present invention is not limited to these examples.

[0171] (Example 1) (a) Spinning Step A basic aluminum chloride aqueous solution was prepared so that the Al content was 70 g / l and the atomic ratio of Al:Cl was 1:1.8. After calcination, the inorganic fibers were calcined to obtain a composition ratio of Al:Cl=1:1.8. 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 added to prepare a mixture. The resulting mixture was concentrated to prepare 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.

[0172] (b) Compression Step The inorganic fiber precursor obtained in the above (a) spinning step was compressed to prepare a continuous sheet-like material.

[0173] (c) Needle-punching process: The sheet-like material obtained in the compression process (b) above was subjected to needle-punching multiple times using a needle board on which needles were arranged at a predetermined density to produce a needle-punched body. First, a needle board on which needles were attached at a predetermined density was prepared. Next, this needle board was placed above one surface of the sheet-like material, and needle-punching was performed multiple times by moving the needle board up and down once along the thickness direction of the sheet-like material while moving the inorganic fiber precursor, to produce a needle-punched body. At this time, the needles were penetrated until the barbs formed at the tip portions of the needles completely penetrated the opposite surface of the sheet-like material.

[0174] (d) Firing step: The needle-punched body obtained in the needle-punching step (c) above was continuously fired at a maximum temperature of 1250°C to produce a fired sheet-like 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 was 3.2 μm. The fired sheet-like material thus obtained had a bulk density of 0.15 g / cm ３ The basis weight is 1400 g / m ２ The density ρ of the interwoven points was 9 points / cm ２ Within a 25 mm × 25 mm area, ten first regions, which were 4 mm × 4 mm regions with no inter-woven points, and four second regions, which were 3 mm × 8 mm regions with no inter-woven points, were arranged.

[0175] (e) Cutting Step The fired needle-punched body was cut to prepare a mat. The dimensions of the mat were a substantially rectangular shape in plan view, with a longitudinal length [A] of 348.0 mm and a width [B] of 93.5 mm, a convex portion length [C] of 20.0 mm, and a non-concave portion width [D １ and D ２ ] is 31 mm, the width [E] of the convex portion is 31.5 mm, and the center in the width direction of the concave portion [E Ｃ ] and the widthwise center of the mat [B Ｃ ] were overlapping.

[0176] (f) Impregnation Step (f-1) Organic Binder Mixture Preparation Step An organic binder mixture solution with a solid content concentration of 2.0 wt % was prepared by diluting acrylate-based latex, which was an organic binder, with water.

[0177] (f-2) Inorganic binder mixed solution preparation step Alumina, which is an inorganic binder, was diluted with water, and a polymeric dispersant was added and thoroughly stirred to prepare an inorganic binder mixed solution having a solids concentration of inorganic particles of 2.0 wt % and a concentration of the polymeric dispersant of 1000 ppm.

[0178] (f-3) Binder Mixture Preparation Step The organic binder mixture obtained in the (f-1) organic binder mixture preparation step was added to the inorganic binder mixture obtained in the (f-2) inorganic binder mixture preparation step in a weight ratio of 1:1 and thoroughly stirred to prepare a binder mixture having an organic binder solids concentration of 1.0 wt %, an inorganic binder solids concentration of 1.0 wt %, and a polymer dispersant concentration of 500 ppm.

[0179] (f-4) Contacting step: The binder mixture obtained in the (f-3) binder mixture preparation step was brought into contact with the mat obtained in the (e) cutting step by a curtain coating method. (f-5) Dehydration step: The mat obtained in the (f-4) contacting step to which the binder mixture was applied was dehydrated by suction using a dehydrator, so that 100 parts by weight of the binder mixture was applied to 100 parts by weight of the inorganic fibers.

[0180] (f-6) Drying Step The mat that had undergone the above (f-5) dewatering step was dried in a dryer to produce the mat material according to Example 1.

[0181] (Examples 2 to 6 and Comparative Examples 1 to 3) (e) Mat materials according to Examples 2 to 6 and Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the cutting shape in the cutting step was changed to satisfy the conditions in Table 1. １ ] is the width of the non-depressed portion on the first side surface side, and [D ２ ] indicates the width of the non-depressed portion on the second side surface side.

[0182] (Press-fitting test) The mat materials according to Examples 1 to 3 and Comparative Examples 1 and 2 were wound around an exhaust gas treatment body having a diameter of 103 mm and a length of 105 mm to form a wound body having a diameter of 115 mm. Using a press-fitting jig with a taper angle of 4.5° and a narrowing diameter of 110.7 mm, the wound body was pressed into a stainless steel casing having an inner diameter of 110.8 mm at a speed of 500 mm / min so that the first side surface of the mat material was on the upstream side and the second side surface was on the downstream side. When the mat material was wound around the exhaust gas treatment body, the length [L ０ ] is recorded, and after press-fitting, the length [L １ ] was measured, and the difference [ΔL] was taken as the deformation amount (shift amount) of the mat material, and was evaluated according to the following criteria. For the mat materials according to Examples 4 to 6 and Comparative Example 3, a 141 mm diameter wound body was wrapped around an exhaust gas treatment body having a diameter of 129 mm and a length of 105 mm. Using a press-fitting jig with a taper angle of 4.5° and a narrowing diameter of 145.3 mm, the mat material was press-fitted into a stainless steel casing having an inner diameter of 145.4 mm at a speed of 500 mm / min so that the first side surface of the mat material was on the upstream side and the second side surface was on the downstream side. [Evaluation Criteria] ⊚: The deformation amount (shift amount) was 6 mm or less, and deformation of the mat material was particularly suppressed. ◯: The deformation amount (shift amount) was more than 6 mm but not more than 8 mm, and deformation of the mat material was sufficiently suppressed. ×: The deformation amount (shift amount) was more than 8 mm, and deformation of the mat material was not sufficiently suppressed.

[0183]

[0184] As shown in Table 1, it was confirmed that all of the mat materials according to the present invention can suppress deformation and displacement of the mat material during press-fitting. Furthermore, a comparison between Examples 1 to 5 and Example 6 revealed that deformation and displacement of the mat material during press-fitting can be particularly suppressed by setting the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction to be 10 or more.

[0185] 1a, 1b Test piece 10 Mat material 11 First main surface 12 Second main surface 13 First end surface 13a Convex portion 13b, 13c Non-protruding portion 14 Second end surface 14a Concave portion 14b, 14c Non-depressed portion 15 First side surface 16 Second side surface 115 Interwoven point 117 First region 118 Second region 120 Inorganic fiber 130 Coating layer 140 Particulate mixture 170 Shear fracture load test device 171 Left jig 172 Right jig 173 Stainless steel plate 174 Projecting member 200 Exhaust gas purification device 220 Casing 230 Exhaust gas treatment body 230a Exhaust gas inlet side end surface 230b Exhaust gas outlet side end surface 231 Cell 232 Cell wall 233 Sealing material 250 Wrapping body

Claims

1. A mat material containing inorganic fibers and having a substantially rectangular shape in a plan view, The mat material has a first main surface and a second main surface opposed to each other in a thickness direction, a first end surface and a second end surface opposed to each other in a longitudinal direction which is a winding direction, and a first side surface and a second side surface opposed to each other in a width direction perpendicular to the thickness direction and the longitudinal direction, The first end surface is formed with a convex portion that protrudes toward the second end surface when the wire is wound, and a non-protruding portion that is disposed on both sides of the convex portion in the width direction and does not protrude toward the second end surface, a recessed portion having a shape corresponding to the protruding portion of the first end surface and a non-depressed portion having a shape corresponding to the non-protruding portion of the first end surface, the non-depressed portion being disposed on both sides of the recessed portion in the width direction when the wire is wound; A mat material characterized in that the ratio [D / C] of the length [D] of the non-depressed portion in the width direction to the length [C] of the non-depressed portion in the longitudinal direction is 1.0 or more.

2. The mat material according to claim 1 , which is a needle mat.

3. 3. The mat material according to claim 2, which has a plurality of interwoven points formed by a needling process on at least one of its front and back surfaces, and which is disposed within an area of ​​25 mm x 25 mm, at least one of a first area which is a 4 mm x 4 mm area where no interwoven points are present, and a second area which is a 3 mm x 8 mm area where no interwoven points are present.

4. 4. The mat material according to claim 2, wherein the inorganic fibers have an average fiber length of 1 to 150 mm.

5. 2. The mat material according to claim 1, which is a paper-made mat.

6. 6. The mat material according to claim 5, wherein the inorganic fibers have an average fiber length of 200 to 20,000 μm.

7. 6. The mat material according to claim 1, wherein an inorganic binder is attached to the surface of the inorganic fibers.

8. 6. The mat material according to claim 1, wherein an organic binder is attached to the surface of the inorganic fibers.

9. 6. The mat material according to claim 1, wherein an inorganic binder and an organic binder are attached to the surfaces of the inorganic fibers.

10. 6. The mat material according to claim 1, further comprising a polymeric dispersant.

11. 10. The mat material according to claim 9, wherein the inorganic binder and the organic binder are attached to the surfaces of the inorganic fibers in a dispersed state.

12. 10. The mat material according to claim 9, wherein an aggregate made of the inorganic binder and the organic binder is attached to a surface of the inorganic fibers.

13. The mat material according to claim 12, wherein at least a portion of the surface of the inorganic fibers is covered with a coating layer made of a mixture of the inorganic binder and the organic binder.

14. The mat member according to claim 13, wherein the coating layer is formed by a continuous flake-like mixture of the inorganic binder and the organic binder.

15. The mat member according to claim 13, wherein the coating layer has a multi-stage shape.

16. The mat member according to claim 13, wherein a particulate mixture of the inorganic binder and the organic binder is attached to a surface of the coating layer.

17. 6. The mat material according to claim 1, wherein the ratio [A / C] of the length [A] of the mat material in the longitudinal direction to the length [C] of the non-depressed portion in the longitudinal direction is 10 or more.

18. An exhaust gas purification device having a casing, an exhaust gas treatment body, and a mat material disposed between the casing and the exhaust gas treatment body, 6. An exhaust gas purification device, comprising the mat material according to claim 1, 2 or 5.

19. A method for manufacturing an exhaust gas purification device, comprising a pressing step of wrapping the mat material according to claim 1, 2 or 5 around an exhaust gas treatment body and then pressing the mat material into a casing by a hard stuffing method, a pre-calibration method or a post-calibration method.