Mat material and holding seal material

Abstract

To provide a mat material with high tensile strength so as to solve the problem that the mat material fractures when wound around an exhaust gas treatment body.SOLUTION: A mat material 10 comprises a laminated mat 20 including at least one orientation layer 30 that is made of inorganic fibers and in which orientation directions of the inorganic fibers are aligned, and at least one random layer 40 that is made of the inorganic fibers and in which the orientation directions of the inorganic fibers are set at random. In addition, the laminated mat includes a binder for increasing a friction force when it is wound around an exhaust gas treatment body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mat material and a holding sealing material. [Background technology]

[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. In addition, 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] Therefore, various exhaust gas purification devices have been proposed that capture PM in exhaust gas and purify harmful gas components, and are composed of an exhaust gas treatment body made of porous ceramics such as silicon carbide or cordierite, a metal casing that houses the exhaust gas treatment body, and a holding seal material (mat material) arranged between the exhaust gas treatment body and the metal casing. This holding seal material (mat material) is arranged mainly for the purposes of preventing the exhaust gas treatment body from coming into contact with the metal casing that covers its outer periphery and being damaged by vibrations and impacts caused by the running of the automobile, and preventing exhaust gas from leaking from between the exhaust gas treatment body and the metal casing.

[0004] As a mat material used for such purposes, Patent Document 1 discloses a holding and sealing material consisting of a mat of a predetermined thickness containing inorganic fibers whose surface is covered with a binder layer, wherein the binder layer contains an organic binder and an inorganic binder, and when the mat is divided into three equal parts in the thickness direction into a first surface portion, a central portion, and a second surface portion, the amount of organic binder attached to the first surface portion is greater than the amount of organic binder attached to the central portion and is also greater than the amount of organic binder attached to the second surface portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-63925 Summary of the Invention [Problem to be solved by the invention]

[0006] When wrapping the mat material around the exhaust gas treatment unit, the wrapping operation may be performed while applying a tensile load to the mat material. If the tensile strength of the mat material is low during this operation, the tensile load may cause the mat material to break, which is a problem. The mat material described in Patent Document 1 also has insufficient tensile strength, and it has been desired to improve the tensile strength of the mat material.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a mat material having high tensile strength. [Means for solving the problem]

[0008] The mat material of the present invention comprises a laminated mat including at least one oriented layer made of inorganic fibers in which the orientation direction of the inorganic fibers is uniform, and at least one random layer made of inorganic fibers in which the orientation direction of the inorganic fibers is random, The laminated mat is a mat material containing a binder.

[0009] The laminated mat constituting the mat material of the present invention comprises an orientation layer and a random layer. The presence of the orientation layer makes it possible to provide a mat material that is less likely to stretch and has high tensile strength. Furthermore, the random layer is easily impregnated with a binder. By incorporating a binder into the mat material, the frictional force of the surface of the mat material can be increased.

[0010] In the mat material of the present invention, the orientation layers and the random layers are alternately laminated in the thickness direction, and it is preferable that the random layers are disposed on both of the two outermost layers of the laminated mat.

[0011] When the binder is impregnated into the laminate mat, it is placed on the outermost layer of the laminate mat and the binder is allowed to penetrate through the random layer in the thickness direction of the laminate mat. Because the binder easily penetrates the random layer but is difficult to penetrate into the oriented layer, the binder is blocked by the oriented layer in the thickness direction of the laminate mat. As a result, the binder content is increased in the outermost layer of the laminated mat, which comes into contact with the binder liquid for binder impregnation. Since a high binder content increases frictional force, if the outermost layer with a high binder content is used as the surface that contacts the exhaust gas treatment body, which requires frictional force during wrapping, slippage between the exhaust gas treatment body and the mat material can be prevented, and it can be used preferably.

[0012] In the mat material of the present invention, the laminated mat preferably contains at least one binder selected from the group consisting of an organic binder and an inorganic binder.

[0013] In the mat material of the present invention, when the laminated mat is divided into three equal parts in the thickness direction into a first surface portion, a central portion, and a second surface portion, the random layer is disposed on the outermost layer of the first surface portion, It is preferable that the content of the binder in the first surface portion is greater than the content of the binder in the central portion and greater than the content of the binder in the second surface portion.

[0014] In the above-mentioned mat material, since the binder content in the first surface portion is high, when the first surface portion is used as the portion that contacts the exhaust gas treatment body, the displacement between the exhaust gas treatment body and the mat material is prevented, and the mat material can be preferably used. Furthermore, matting materials are used in exhaust gas purification equipment, but the environment in which the equipment is used is a high-temperature environment, which can cause binders (especially organic binders) to volatilize. Therefore, matting materials intended for use in exhaust gas purification equipment are required to contain a low binder content. In the above mat material, the binder content is increased in the first surface portion, but not in the entire mat material, so that the requirement for the binder content of the entire mat material can be met.

[0015] In the mat material of the present invention, it is preferable that the content of the binder satisfies the following relationship. 0.4≦(center / first surface) 0.2≦(second surface portion / first surface portion) (Second surface / center)≦0.5 It is also preferable that the content of the binder further satisfies the following relationship: 0<(second surface / center)

[0016] If the binder contents in the first surface portion, the central portion, and the second surface portion satisfy the above relationship, when the first surface portion is brought into contact with and wrapped around the exhaust gas treatment body, the frictional force between the mat material and the exhaust gas treatment body is improved, and interfacial slippage between the mat material and the exhaust gas treatment body is less likely to occur when the mat material is assembled into the casing.

[0017] In the mat material of the present invention, the inorganic fibers in the orientation layer preferably contain 70% or more inorganic fibers having an inclination of 60 to 90 degrees with respect to the width direction of the mat material.

[0018] In the mat material of the present invention, the tensile strength at break measured by a tensile test is preferably 200 kPa or more. Furthermore, the elongation at break measured by a tensile test is preferably 3.5 mm or less.

[0019] When the tensile strength at break and the elongation at break measured by the tensile test are within the above ranges, the mat material is more reliably prevented from breaking when wrapped around an exhaust gas treatment unit or the like. Furthermore, if the tensile strength at break is high and the elongation at break is small, the variation in workability during winding is reduced.

[0020] The holding seal material of the present invention is made of the mat material of the present invention and is used to hold an exhaust gas treatment body in an exhaust gas purification apparatus.

[0021] The mat material of the present invention is a mat material that is resistant to stretching and has high tensile strength, and therefore is resistant to breakage when wrapped around an exhaust gas treatment body, making it suitable for use as a holding and sealing material. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a perspective view schematically showing an example of a mat member. [Figure 2] FIG. 2 is a cross-sectional view of the mat member shown in FIG. 1 taken along line AA. [Figure 3] FIG. 3 is a perspective view schematically illustrating an example of an alignment layer. [Figure 4] FIG. 4 is an example of a micrograph containing inorganic fibers. [Figure 5] FIG. 5 is a perspective view schematically illustrating an example of a random layer. [Figure 6] FIG. 6 is a cross-sectional view schematically showing a needle mat including a rivet portion. [Figure 7] FIG. 7 is a cross-sectional view that schematically shows an example of an exhaust gas purification device. [Figure 8] FIG. 8 is a perspective view that schematically shows an example of an exhaust gas treatment body that constitutes an exhaust gas purification device. [Figure 9] FIG. 9 is a perspective view that schematically shows an example of a method for manufacturing an exhaust gas purification device. DETAILED DESCRIPTION OF THE INVENTION

[0023] An example of the mat material and the holding sealing material of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a perspective view schematically showing an example of a mat member. FIG. 2 is a cross-sectional view of the mat member shown in FIG. 1 taken along line AA. The mat material 10 shown in FIG. 1 is a laminated mat 20 including an orientation layer 30 and a random layer 40 . Three layers, namely, a random layer 40a, an orientation layer 30, and a random layer 40b, are laminated along the thickness direction (the direction indicated by the double-headed arrow T in Figs. 1 and 2) of the laminate mat 20. The random layers 40a and 40b have the same specifications.

[0024] The laminated mat 20 is a mat that is long in its longitudinal direction (the direction indicated by the double arrow L in FIG. 1). The laminate mat 20 has two main surfaces, a first main surface 23 and a second main surface 24. The first main surface 23 is the surface of the random layer 40a, and the second main surface 24 is the surface of the random layer 40b.

[0025] The laminate mat 20 has four side surfaces, and the side surfaces along the longitudinal direction of the laminate mat 20 are a first long side surface 25 and a second long side surface 26. The side surfaces along the width direction of the laminate mat 20 (the direction indicated by the double-headed arrow W in FIG. 1) are a first short side surface 27 and a second short side surface 28. The laminated mat 20 has a generally rectangular shape when viewed from above, with a recessed portion formed on the first short side surface 27 and a protruding portion formed on the second short side surface 28. The recessed portion and the protruding portion are shaped to fit together perfectly when the mat material is wrapped around an exhaust gas purification device, an exhaust gas treatment body, or an exhaust pipe having a cylindrical outer periphery. In the mat member of this embodiment, the shapes of the mating portions are recessed and protruding, but the shapes of the mating portions may be an L-shaped combination.

[0026] FIG. 3 is a perspective view schematically illustrating an example of an alignment layer. FIG. 3 shows the orientation layer 30, and schematically shows inorganic fibers 31 that make up the orientation layer 30 together with their orientation directions. The orientation layer 30 is made of inorganic fibers and is a layer in which the orientation direction of the inorganic fibers is uniform. In the orientation layer shown in Fig. 3, the inorganic fibers are oriented in the longitudinal direction of the mat material.

[0027] In this specification, "the orientation direction of inorganic fibers is uniform" means that when the angle of the inorganic fibers is measured in one direction of the photographed area (usually the horizontal direction of the photographed area) in a microscopic photograph containing inorganic fibers, 50% or more of the fibers are in the range of 75 to 90 degrees.

[0028] FIG. 4 is an example of a micrograph containing inorganic fibers. Inorganic fibers 31 are visible in the photograph shown in Fig. 4. It can be seen from Fig. 4 that many of the inorganic fibers are oriented in the vertical direction (90° direction) of the photographed area. 52% of the inorganic fibers have an angle θ of 75 to 90 degrees measured with respect to the horizontal direction (0° direction) of the photographed area. That is, the layer from which the photograph shown in FIG. 4 was taken is the alignment layer.

[0029] In addition, the inorganic fibers in the orientation layer preferably contain 70% or more inorganic fibers having an inclination of 60 to 90 degrees with respect to the width direction of the mat material. If the orientation layer satisfies the above conditions, the direction in which tensile stress is applied when the mat material is wound is aligned with the orientation of the inorganic fibers, which is preferable because the tensile strength of the mat material tends to be high. The horizontal direction of the photograph shown in FIG. 4 is the width direction of the mat material, and 78% of the inorganic fibers have an angle θ in the range of 60 to 90 degrees. That is, in the orientation layer from which the photograph shown in FIG. 4 was taken, 70% or more of the inorganic fibers contain inorganic fibers inclined at 60 to 90 degrees with respect to the width direction of the mat material. A direction inclined at 60 to 90 degrees with respect to the width direction of the mat material can be said to be a direction along the longitudinal direction of the mat material, and therefore the inorganic fibers in the orientation layer can be said to be oriented along the longitudinal direction of the mat material.

[0030] In the orientation layer, the proportion of inorganic fibers whose angle θ measured with respect to the horizontal direction (0° direction) of the imaging area is in the range of 75 to 90 degrees may be 60% or more, or even 70% or more, and the proportion of inorganic fibers whose angle θ is in the range of 75 to 90 degrees may be 90% or less, or even 80% or less.

[0031] The orientation layer may contain 75% or more, or 85% or more, of inorganic fibers inclined at 60 to 90 degrees relative to the width direction of the mat material, and 95% or less, or 90% or less, of inorganic fibers inclined at 60 to 90 degrees relative to the width direction of the mat material.

[0032] FIG. 5 is a perspective view schematically illustrating an example of a random layer. FIG. 5 shows the random layer 40, and schematically shows inorganic fibers 41 that make up the random layer 40. The random layer 40 is made of inorganic fibers, and the orientation direction of the inorganic fibers is random.

[0033] In this specification, "the orientation direction of inorganic fibers is random" means that in a micrograph containing inorganic fibers, it is visible that the inorganic fibers are not oriented in a specific direction in the photographed area. A layer in which the orientation of inorganic fibers does not fit the definition of an oriented layer described above may also be called a random layer.

[0034] The oriented layers and random layers in the laminate mat are preferably arranged alternately in the thickness direction. In Figures 1 and 2, they are arranged alternately in the order of random layer 40a / oriented layer 30 / random layer 40b, and the two outermost layers of the laminate mat each have a random layer. The number of mats stacked in the laminated mat is not particularly limited as long as it contains at least one oriented layer and one random layer. Since it is preferable that the random layer is arranged as the outermost layer and that the random layers and the oriented layers are arranged alternately, three or five mats are preferred. Examples include a three-layer structure of random layer / oriented layer / random layer, or a five-layer structure of random layer / oriented layer / random layer / oriented layer / random layer.

[0035] The mats constituting the laminated mat contain inorganic fibers. The inorganic fibers are not particularly limited and may be alumina fibers, silica fibers, etc. They may also be glass fibers or biosoluble fibers. The inorganic fibers may be changed depending on the properties required of the mat material, such as heat resistance and wind erosion resistance, and it is preferable to use fibers with a large diameter and fiber length that comply with the environmental regulations of each country.

[0036] Among these, inorganic fibers of low crystalline alumina are preferred, inorganic fibers of low crystalline alumina having a mullite composition are more preferred, and inorganic fibers containing a spinel compound are even more preferred.

[0037] In the mat material of the present invention, the laminated mat contains a binder. By incorporating a binder into the mat material, the frictional force of the surface of the mat material can be increased. Since the random layer is easily impregnated with a binder, it is preferable to impregnate the random layer with a binder.

[0038] The lamination mat preferably contains at least one of an organic binder and an inorganic binder. By adding a binder to the laminated mat, the frictional force of the mat material can be increased.

[0039] Examples of the organic binder include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, and polyurethane resins.

[0040] Examples of inorganic binders include inorganic sol dispersions (alumina sol, silica sol, zirconia sol, titania sol, etc.).

[0041] The content of the binder (total amount of organic binder and inorganic binder) in the laminate mat is preferably 0.2 to 30% by weight of the laminate mat. When an organic binder is included, the content of the organic binder is preferably 0.1 to 20% by weight, and when an inorganic binder is included, the content of the inorganic binder is preferably 0.1 to 10% by weight.

[0042] When the laminate mat contains a binder, it is preferred that the outermost layer of the laminate mat is a random layer, and that the orientation layer is disposed inside the random layer. When the binder is impregnated into the laminate mat, it is placed on the outermost layer of the laminate mat and the binder is allowed to penetrate through the random layer in the thickness direction of the laminate mat. Because the binder easily penetrates the random layer but is difficult to penetrate into the oriented layer, the binder is blocked by the oriented layer in the thickness direction of the laminate mat. As a result, the binder content is increased in the outermost layer of the laminated mat, which comes into contact with the binder liquid for binder impregnation. Since a high binder content increases frictional force, if the outermost layer with a high binder content is used as the surface that contacts the exhaust gas treatment body, which requires frictional force during wrapping, slippage between the exhaust gas treatment body and the mat material can be prevented, and it can be used preferably.

[0043] In addition, as a specific example of a configuration in which the outermost layer of the laminated mat is a random layer and an orientation layer is arranged inside the random layer, it is preferable that the orientation layer and the random layer are laminated alternately in the thickness direction, and that both of the two outermost layers of the laminated mat are random layers.

[0044] Furthermore, when the laminated mat is divided into three equal parts in the thickness direction into a first surface portion, a central portion, and a second surface portion, it is preferable that a random layer is disposed on the outermost layer of the first surface portion, and that the binder content in the first surface portion is greater than the binder content in the central portion and greater than the binder content in the second surface portion.

[0045] 2, random layer 40a, orientation layer 30, and random layer 40b are all the same thickness, so random layer 40a can be considered the first surface portion, orientation layer 30 the central portion, and random layer 40b the second surface portion. In this case, it is preferable that the binder content in random layer 40a be greater than the binder content in orientation layer 30 and greater than the binder content in random layer 40b.

[0046] In a mat material having a random layer arranged on the outermost layer of the first surface portion, the binder content in the first surface portion is high, so when the first surface portion is used as the part that contacts the exhaust gas treatment body, misalignment between the exhaust gas treatment body and the mat material is prevented, making it suitable for use. Furthermore, matting materials are used in exhaust gas purification equipment, but the environment in which the equipment is used is a high-temperature environment, which can cause binders (especially organic binders) to volatilize. Therefore, matting materials intended for use in exhaust gas purification equipment are required to contain a low binder content. In the mat material having the above configuration, the binder content is increased in the first surface portion, but not in the entire mat material, so that the requirement for the binder content of the entire mat material can be met.

[0047] The binder content preferably satisfies the following relationship: 0.4≦(center / first surface) 0.2≦(second surface portion / first surface portion) (Second surface / center)≦0.5 Furthermore, it is preferable that the binder content satisfies the following relationship: 0<(second surface / center)

[0048] If the binder contents in the first surface portion, the central portion, and the second surface portion satisfy the above relationship, when the first surface portion is brought into contact with and wrapped around the exhaust gas treatment body, the frictional force between the mat material and the exhaust gas treatment body is improved, and interfacial slippage between the mat material and the exhaust gas treatment body is less likely to occur when the mat material is assembled into the casing.

[0049] Furthermore, it is preferable that the binder content of the first surface portion is 0.1% by weight or more and 29.0% by weight or less, the binder content of the central portion is 0.2% by weight or more and 15.0% by weight or less, and the binder content of the second surface portion is 0.05% by weight or more and 5.0% by weight or less.

[0050] In the mat material of the present invention, the tensile strength at break measured by a tensile test is preferably 200 kPa or more. Furthermore, the elongation at break measured by a tensile test is preferably 3.5 mm or less.

[0051] The tensile strength at break and the elongation at break are measured by cutting the mat material into a sample having a length of 200 mm along the longitudinal direction of the mat material and a width of 50 mm along the width direction of the mat material. The thickness of the sample is measured at three points, and using a universal testing machine equipped with a chuck (gripping jig) for tensile tests, the chuck distance is set to 40 mm on each side, and the mat material is pulled in the longitudinal direction of the sample at a speed of 100 mm / min. The load and pulling distance at the time of break are determined. Tensile strength at break is calculated as follows: Tensile strength at break = Load at break / (Sample thickness x width). The pulling distance at break is defined as the elongation at break.

[0052] When the tensile strength at break and the elongation at break measured by the tensile test are within the above ranges, the mat material is more reliably prevented from breaking when wrapped around an exhaust gas treatment unit or the like. Furthermore, if the tensile strength at break is high and the elongation at break is small, the variation in workability during winding is reduced.

[0053] The orientation layer and random layer constituting the laminated mat may be a paper-made mat obtained by a paper-making method, or a needle mat obtained by a needling method.

[0054] In the papermaking method, for example, inorganic fibers such as alumina fibers or silica fibers, an inorganic binder, and water are mixed together so that the inorganic fiber content in the raw material liquid reaches a predetermined value, and the mixture is stirred with a stirrer to prepare a slurry containing the inorganic fibers. The slurry may optionally contain a colloidal solution of a polymer compound or resin. The mixed liquid is then poured into a molding machine with a filtration mesh on the bottom, and the water in the mixed liquid is dehydrated through the mesh to produce a raw material sheet. The raw material sheet is then heated and compressed under predetermined conditions to obtain a papermaking mat.

[0055] In the case of the needling method, for example, a spinning mixture made from a basic aluminum chloride aqueous solution, silica sol, or the like is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm. Subsequently, the inorganic fiber precursor is compressed to produce a continuous sheet-like product of a predetermined size, which is subjected to a needling treatment (needle punching treatment), and then subjected to a firing treatment to obtain a needle mat.

[0056] The method for producing the orientation layer and the random layer is not particularly limited, but the following method can be mentioned, for example. When the orientation layer is produced by a papermaking method, if a slurry containing inorganic fibers is papered and allowed to flow in one direction, the fibers are oriented in the flow direction, and an orientation layer can be formed. When a random layer is produced by the papermaking method, a slurry containing inorganic fibers is poured into a mold from above. Because there is no flow of the slurry, the fibers do not orient in a specific direction, resulting in a random layer. The slurry containing inorganic fibers may contain at least one of an organic binder and an inorganic binder.

[0057] The laminated mat may also be a paper-made mat obtained by laminating an orientation layer and a random layer and then subjecting them to a needling treatment.

[0058] A binder may be applied to the laminate mat. When applying a binder to the laminate mat, a binder liquid containing the binder is allowed to penetrate into the laminate mat in the thickness direction from one main surface (first main surface) of the laminate mat. The penetration of the binder liquid may be carried out by a method such as curtain coating, in which the binder solution is dropped onto the mat, thereby applying the binder solution to the inorganic fibers in the mat, or by a method such as spray coating, in which the binder solution is sprayed onto the mat.

[0059] When a random layer is placed on the outermost layer of a laminated mat and an oriented layer is placed inside it, the binder easily penetrates the random layer but does not easily penetrate the oriented layer, so the binder is blocked by the oriented layer in the thickness direction of the laminated mat. As a result, the binder content is increased in the outermost layer of the laminated mat, which comes into contact with the binder liquid for binder impregnation. Since a high binder content increases frictional force, if the outermost layer with a high binder content is used as the surface that contacts the exhaust gas treatment body, which requires frictional force during wrapping, slippage between the exhaust gas treatment body and the mat material can be prevented, and it can be used preferably.

[0060] It is also preferable that the needle mat contains a binder and has rivet portions that extend from the first main surface of the laminated mat along the needle marks in the thickness direction and have a higher binder concentration than other portions.

[0061] FIG. 6 is a cross-sectional view schematically showing a needle mat including a rivet portion. FIG. 6 shows rivet portions 51 formed by impregnating needle marks 50 formed by needling treatment from the first main surface 23 of the laminate mat 20 with a binder. When the needle mat has rivets, the binder penetrates into the mat material in the thickness direction, which causes binding between the inorganic fibers and leads to structural reinforcement of the mat material, which is preferable. The rivet portion is a portion where the binder (organic binder) looks like a rivet in the cross section of the laminated mat when the mat material is heated and the binder is burnt. The depth of the rivet is not particularly limited. FIG. 6 also shows that needle marks 50 are present on the second main surface 24 of the laminate mat 20, but no rivet portions are present because the binder has not penetrated from the second main surface 24.

[0062] The mat material of the present invention can be used as a holding and sealing material used to hold an exhaust gas treatment body in an exhaust gas purification device. The holding seal material of the present invention comprises the mat material of the present invention and is used as a holding seal material for holding an exhaust gas treating body in an exhaust gas purification apparatus.

[0063] FIG. 7 is a cross-sectional view that schematically shows an example of an exhaust gas purification device. As shown in FIG. 7, the exhaust gas purification device 100 includes a metal casing 130, an exhaust gas treatment body 120 housed in the metal casing 130, and a mat material 10 which is a retaining sealing material arranged between the exhaust gas treatment body 120 and the metal casing 130. The exhaust gas treatment body 120 is a columnar structure in which a large number of cells 125 are arranged in parallel in the longitudinal direction, separated by cell walls 126. Note that, to the ends of the metal casing 130, an inlet pipe for introducing exhaust gas emitted from the internal combustion engine and an outlet pipe for discharging exhaust gas that has passed through the exhaust gas purification device to the outside are connected as necessary.

[0064] A case where exhaust gas passes through the exhaust gas purification device 100 having the above-described configuration will be described below with reference to FIG. As shown in FIG. 7, exhaust gas emitted from an internal combustion engine and flowing into the exhaust gas purification device 100 (in FIG. 7, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by arrows) flows into one cell 125 opening at the exhaust gas inlet end face 120a of the exhaust gas treatment body (honeycomb filter) 120 and passes through a cell wall 126 separating the cells 125. At this time, PM in the exhaust gas is captured by the cell wall 126, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 125 opening at the exhaust gas outlet end face 120b and is discharged to the outside.

[0065] In the exhaust gas purification device 100 shown in Figure 7, the retaining sealing material is the mat material 10 of the present invention, and the first main surface 23 of the laminated mat constituting the mat material 10 is arranged on the side of the exhaust gas treatment body 120, and the second main surface 24 is arranged on the side of the metal casing 130.

[0066] The material of the metal casing constituting the exhaust gas purification device is not particularly limited as long as it is a heat-resistant metal, and specific examples include metals such as stainless steel, aluminum, and iron.

[0067] The casing may be of a generally cylindrical shape, a clamshell shape, or a generally elliptical or polygonal shape in cross section.

[0068] FIG. 8 is a perspective view that schematically shows an example of an exhaust gas treatment body that constitutes an exhaust gas purification device.

[0069] The exhaust gas treatment body 120 shown in Fig. 8 is a honeycomb structure made of a columnar ceramic material in which a large number of cells 125 are arranged in parallel in the longitudinal direction, separated by cell walls 126. Either end of the cells 125 is sealed with a plugging material 128. An outer periphery coating layer 127 is provided on the outer periphery of the honeycomb structure for the purposes of reinforcing the outer periphery of the honeycomb structure, shaping the honeycomb structure, and improving the heat insulating properties of the honeycomb structure.

[0070] When either end of the cells 125 is sealed, it is preferable that, when viewed from one end of the exhaust gas treatment body 120, cells with sealed ends and cells without sealing ends are arranged alternately.

[0071] The cross-sectional shape of the exhaust gas treatment body 120 cut in a direction perpendicular to the longitudinal direction is not particularly limited, and may be approximately circular, approximately elliptical, or approximately polygonal, such as approximately triangular, approximately rectangular, approximately pentagonal, or approximately hexagonal.

[0072] The cross-sectional shape of the cells 125 constituting the exhaust gas treatment body 120 may be a substantially polygonal shape such as a substantially triangular, substantially rectangular, substantially pentagonal, or substantially hexagonal, or may also be a substantially circular or substantially elliptical shape. The exhaust gas treatment body 120 may also be a combination of cells with a plurality of cross-sectional shapes.

[0073] The material constituting the exhaust gas treatment body 120 is not particularly limited, but may be a non-oxide such as silicon carbide or silicon nitride, or an oxide such as cordierite or aluminum titanate. Of these, a non-oxide porous fired body such as silicon carbide or silicon nitride is particularly desirable. These porous sintered bodies are brittle materials and therefore easily broken by mechanical impact, etc. However, if the mat material 10 (holding sealing material) is interposed around the side surface of the exhaust gas treatment body 120, the impact is absorbed, and it is possible to prevent cracks, etc. from occurring in the exhaust gas treatment body 120 due to mechanical impact or thermal shock.

[0074] The exhaust gas treatment body may be supported with a catalyst for purifying exhaust gas. The supported catalyst is preferably a precious metal such as platinum, palladium, or rhodium, with platinum being more preferred. Other catalysts may also be used, such as alkali metals such as potassium or sodium, or alkaline earth metals such as barium. These catalysts may be used alone or in combination of two or more. Supporting these catalysts facilitates the burning and removal of PM, making it possible to purify toxic exhaust gases.

[0075] The exhaust gas treatment body constituting the exhaust gas purification device may be an integrally formed monolithic honeycomb structure made of cordierite or the like, or an aggregated honeycomb structure made of silicon carbide or the like, which is formed by bundling together a plurality of columnar honeycomb fired bodies having numerous through holes arranged in parallel in the longitudinal direction separated by partition walls, via a paste mainly containing ceramic.

[0076] The exhaust gas treatment body constituting the exhaust gas purification device may not have a sealing material provided in the cells, and the ends of the cells may not be sealed. In this case, the exhaust gas treatment body supports a catalyst such as platinum, and functions as a catalyst carrier that purifies harmful gas components such as CO, HC, and NOx contained in the exhaust gas.

[0077] The holding sealing material of the present invention made of the mat material of the present invention is used by being wrapped around an exhaust gas treating body. An example in which a wrapped body in which the holding sealing material is wrapped around an exhaust gas treating body is placed in an exhaust gas purification device will be described.

[0078] FIG. 9 is a perspective view that schematically shows an example of a method for manufacturing an exhaust gas purification device. 9, a holding sealing material made of the mat material 10 is wound around the periphery of the exhaust gas treatment body 120 to form a wound body 140. Next, the wound body 140 is housed in a metal casing 130 to manufacture an exhaust gas purification device.

[0079] When the wound body 140 is produced, the first main surface 23 of the laminated mat 20 constituting the mat material 10 is wound toward the exhaust gas treatment body 120. As a result, the first main surface 23 becomes the surface on the exhaust gas treatment body 120 side, and the second main surface 24 becomes the surface on the metal casing 130 side.

[0080] Next, methods for accommodating the wound body 140 in the metal casing 130 include, for example, a stuffing method in which the exhaust gas treatment body 120 (wound body 140) surrounded by a retaining sealing material made of mat material 10 is pressed into a predetermined position inside the metal casing 130, a sizing method in which the metal casing 130 is compressed from the outer periphery to reduce the inner diameter, and a clamshell method in which the metal casing is shaped so that it can be separated into a first casing and a second casing, and the wound body 140 is placed on the first casing and then the second casing is placed over it to seal it. When the wound body is housed in the metal casing by the press-fitting method (stuffing method), it is desirable that the inner diameter of the metal casing (the inner diameter of the part that houses the exhaust gas treatment body) is slightly smaller than the outer diameter of the wound body. Through these steps, the wrapped body with the holding sealing material wrapped around the exhaust gas treatment body can be placed in the exhaust gas purification device.

[0081] The present specification discloses the following:

[0082] The present disclosure (1) is a mat material comprising a laminated mat including at least one oriented layer made of inorganic fibers in which the orientation direction of the inorganic fibers is uniform, and at least one random layer made of inorganic fibers in which the orientation direction of the inorganic fibers is random, and the laminated mat includes a binder.

[0083] The present disclosure (2) is a mat material described in the present disclosure (1), in which the orientation layers and the random layers are alternately stacked in the thickness direction, and the random layers are arranged on both of the two outermost layers of the laminated mat.

[0084] The present disclosure (3) is the mat material according to the present disclosure (1) or (2), wherein the laminated mat contains at least one binder selected from the group consisting of an organic binder and an inorganic binder.

[0085] The present disclosure (4) is a method for manufacturing a laminated mat, the method comprising the steps of: dividing the laminated mat into three equal parts in the thickness direction into a first surface part, a central part, and a second surface part; and disposing the random layer on the outermost layer of the first surface part; The mat material according to any one of the present disclosures (1) to (3), wherein the binder content in the first surface portion is greater than the binder content in the central portion and greater than the binder content in the second surface portion.

[0086] The present disclosure (5) is the mat material according to the present disclosure (4), in which the content of the binder satisfies the following relationship: 0.4≦(center / first surface) 0.2≦(second surface portion / first surface portion) (Second surface / center)≦0.5

[0087] The present disclosure (6) is the mat material according to the present disclosure (5), in which the content of the binder further satisfies the following relationship: 0<(second surface / center)

[0088] The present disclosure (7) is a mat material according to any one of the present disclosures (1) to (6), wherein the inorganic fibers in the orientation layer contain 70% or more inorganic fibers having an inclination of 60 to 90 degrees with respect to the width direction of the mat material.

[0089] The present disclosure (8) is the mat material according to any one of the present disclosures (1) to (7), which has a tensile strength at break measured by a tensile test of 200 kPa or more.

[0090] The present disclosure (9) is the mat material according to any one of the present disclosures (1) to (8), which has an elongation at break measured by a tensile test of 3.5 mm or less.

[0091] The present disclosure (10) is a holding sealing material made of the mat material according to any one of the present disclosures (1) to (9), and used to hold an exhaust gas treating body in an exhaust gas purification device. [Example]

[0092] Example 1 Using a papermaking method, a papermaking mat consisting of inorganic fibers and consisting of an oriented layer and a random layer was produced, and the mats were stacked in the order of random layer / oriented layer / random layer / oriented layer / random layer, and then needling was performed on them all to produce a laminated mat.

[0093] A binder liquid containing an organic binder was applied to one main surface (random layer) of the laminated mat, and then dried to prepare a mat material. The laminated mat was divided into three equal parts in the thickness direction, and the part containing the random layer on the side where the binder liquid was applied was designated as the first surface part, and the part containing the random layer on the opposite side to the side where the binder liquid was applied was designated as the second surface part. The part between the first surface part and the second surface part was designated as the center part. The binder content was determined from the change in weight before and after the binder liquid was applied. Table 1 shows the binder content ratio, which is the ratio of the binder content in two of the first surface portion, the central portion, and the second surface portion.

[0094] The photograph of the orientation layer is shown in Figure 4, and 52% of the inorganic fibers had an angle θ in the range of 75 to 90 degrees. In addition, 78% of the inorganic fibers had an inclination of 60 to 90 degrees with respect to the width direction of the mat material. In the random layer photographed in the same manner as in Figure 4, 14% of the inorganic fibers had an angle θ of 75 to 90 degrees, and 27% of the inorganic fibers had an inclination of 60 to 90 degrees relative to the width direction of the mat material.

[0095] (Comparative Example 1) A mat material (holding seal material) according to Example 1 of Patent Document 1 was prepared. The mat material in Example 1 of Patent Document 1 is not a laminated mat and does not have both an oriented layer and a random layer inside.

[0096] (Tensile test) The mat material was cut into a sample having a length of 200 mm along the longitudinal direction of the mat material and a width of 50 mm along the width direction of the mat material. The thickness of the sample was measured at three points, and using a universal testing machine equipped with a chuck (gripping jig) for tensile testing, the chuck distance was set to 40 mm on each side, and the mat material was pulled along the longitudinal direction of the sample at a speed of 100 mm / min, and the load and pulling distance at the time of break were determined. The tensile strength at break was calculated as follows: (tensile strength at break) / (sample thickness x width). The pulling distance at break was defined as the elongation at break. The results are shown in Table 1.

[0097] [Table 1]

[0098] The results shown in Table 1 show that the mat material of Example 1 has high tensile strength. [Explanation of symbols]

[0099] 10 Mat material 20 Laminated Mat 23 First main surface of laminated mat 24 Second main surface of laminated mat 25 First long side of laminated mat 26 Second long side of laminated mat 27 First short side of laminate mat 28 Second short side of laminate mat 30 Alignment layer 31 Inorganic fibers constituting the orientation layer 40, 40a, 40b random layers 41 Inorganic fibers that form random layers 50 Needle marks 51 Rivet section 100 Exhaust gas purification device 120 Exhaust gas treatment body 120a, 120b Exhaust gas inlet end surface 125 cells 126 Cell Wall 127 Peripheral coating layer 128 Encapsulating material 130 Metal Casing 140 Wrapped body

Claims

1. The laminated mat includes at least one oriented layer made of inorganic fibers in which the orientation direction of the inorganic fibers is uniform, and at least one random layer made of inorganic fibers in which the orientation direction of the inorganic fibers is random, The laminated mat includes a binder.

2. The mat material according to claim 1, wherein the orientation layers and the random layers are alternately laminated in the thickness direction, and the random layers are disposed on both of the two outermost layers of the laminated mat.

3. 3. The mat member according to claim 1, wherein the binder is at least one of an organic binder and an inorganic binder.

4. When the laminated mat is divided into three equal parts in the thickness direction into a first surface portion, a central portion, and a second surface portion, the random layer is disposed on the outermost layer of the first surface portion, The mat material according to claim 1 or 2, wherein the binder content in the first surface portion is greater than the binder content in the central portion and greater than the binder content in the second surface portion.

5. The mat member according to claim 4 , wherein the binder content satisfies the following relationship: 0.4≦(center portion / first surface portion) 0.2≦(second surface portion / first surface portion) (second surface portion / center portion)≦0.5

6. The mat member according to claim 5 , wherein the content of the binder further satisfies the following relationship: 0<(second surface portion / center portion)

7. 3. The mat material according to claim 1, wherein the inorganic fibers in the orientation layer contain 70% or more inorganic fibers having an inclination of 60 to 90 degrees with respect to the width direction of the mat material.

8. 3. The mat material according to claim 1, wherein the tensile strength at break measured by a tensile test is 200 kPa or more.

9. 9. The mat material according to claim 8, wherein the elongation at break measured by a tensile test is 3.5 mm or less.

10. A holding and sealing material comprising the mat material according to claim 1 or 2, and used to hold an exhaust gas treatment body in an exhaust gas purification device.

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