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

Abstract

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

Description

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

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

[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] 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 casing (cylindrical member) that houses the exhaust gas treatment body, and a holding seal material disposed between the exhaust gas treatment body and the casing. The holding seal material is disposed mainly for the purposes of preventing the exhaust gas treatment body from coming into contact with the casing that surrounds it 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 casing.

[0004] As a holding sealing material for such applications, a mat material made of inorganic fibers is used. The mat material made of inorganic fibers is also used for heat insulation and soundproofing by wrapping it around piping in automobiles, etc.

[0005] Patent Document 1 discloses a composite mat that is wrapped around a small-diameter exhaust gas treatment body (catalytic converter). The composite mat is made of inorganic fibers, a binder, and a flexible sheet attached to at least one surface of the inorganic fiber layer.

[0006] Furthermore, Patent Document 2 discloses a holding and sealing material in which a protective sheet having anisotropic elongation in its plane is placed on the surface of a mat substrate.

[0007] Furthermore, Patent Document 3 discloses a holding sealer in which a sheet material having an opening in at least a part of its surface is placed on at least one of the first and second main surfaces of a base material.

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

[0009] JP-T-2001-521847 A JP-A-2008-51004 A JP-A-2009-85092 A JP-A-2020-84798 A

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

[0011] A conventional method for manufacturing such mat materials is to punch them out using a punching die with a punching blade (also called punching processing). In this process, a large-sized adhesive body is prepared by attaching a sheet-like member made of inorganic fiber and a flexible sheet, and by punching this adhesive body, a large number of mat materials can be obtained in a single punching process.

[0012] The mat material has a longitudinal direction, which is the wrapping direction, and a lateral direction, which is perpendicular to the longitudinal direction. When obtaining such a mat material from a single large-sized adhesive body, a combination of punching locations where the mat material is punched in the direction where the vertical direction of the adhesive body is the longitudinal direction of the mat material and punching locations where the horizontal direction of the adhesive body is the longitudinal direction of the mat material is used is used to obtain as much mat material as possible from a single large-sized adhesive body. In this case, two types of mat material are obtained, each with a different relationship between the longitudinal and horizontal directions of the adhesive body and the longitudinal direction of the mat material.

[0013] Here, when a sheet having elongation anisotropy is used, two types of mat materials are obtained which have different relationships between the longitudinal direction of the mat material and the orientation of the tensile strength of the sheet. Specifically, two types of mat materials are obtained: a mat material in which the longitudinal direction of the mat material is aligned with the direction in which the tensile strength of the sheet is strong (hard mat material), and a mat material in which the longitudinal direction of the mat material is aligned with the direction in which the tensile strength of the sheet is weak (easy mat material).

[0014] A hard mat material is a mat material in which the longitudinal direction of the mat material and the direction in which the tensile strength of the sheet are strong are aligned, so that when the mat material is wrapped around an exhaust gas treatment body or the like in the longitudinal direction of the mat material as the wrapping direction, the resistance due to the tensile strength of the sheet is strong and force is required for wrapping. On the other hand, an easy mat material is a mat material in which the longitudinal direction of the mat material and the direction in which the tensile strength of the sheet are weak are aligned, so that when the mat material is wrapped around an exhaust gas treatment body or the like in the wrapping direction of the mat material, the resistance due to the tensile strength of the sheet is weak and force is not required for wrapping.

[0015] The product specifications require that mat materials have a certain level of wrapability, and mat materials that do not meet the specifications are deemed defective. Therefore, if two types of mat materials with different wrapability, a hard mat material and an easy mat material, are obtained from a single large adhesive sheet, there is a high possibility that one of the mat materials will be deemed defective.

[0016] For these reasons, even when two types of mat materials are obtained from one large adhesive body, it is preferable that the wrapability of the two types of mat materials be the same within the standard values.

[0017] Furthermore, even if a sheet such as a flexible sheet is provided, if the opening area of ​​the sheet is large, there is a risk that the mat material may crack when it is wrapped around the exhaust gas treatment body or the like.

[0018] The present invention has been made in consideration of such problems, and aims to provide a mat material that has a configuration that allows stable winding properties within standard values ​​and can suppress the occurrence of cracks during winding.

[0019] The mat material of the present invention includes a base mat containing inorganic fibers and having first and second main surfaces, and a sheet material placed on at least one of the first and second main surfaces, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, and the sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ / or less.

[0020] The mat material of the present invention has a laminated sheet material in which vertically oriented fibers and horizontally oriented fibers are laminated as the sheet material, and therefore the anisotropy of the tensile strength of the sheet material can be reduced, resulting in a mat material having a configuration in which the winding properties are stable and within the standard values.

[0021] In addition, in the mat material of the present invention, the sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ Since the number of the mat members is 1 / piece or less, the adhesion between the sheet material and the base mat is increased, and therefore, the occurrence of cracks when the mat member is wound can be suppressed.

[0022] In the mat material of the present invention, the average opening area of ​​the sheet material is 0.7 mm ２ If the number exceeds 1 / piece, it becomes difficult to prevent cracks from occurring when the mat material is wound.

[0023] In the mat material of the present invention, the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is preferably 60° or more and 120° or less, which can further reduce the anisotropy of the tensile strength of the sheet material, resulting in a mat material with a configuration that is more stable in terms of windability.

[0024] In the mat material of the present invention, the opening ratio of the sheet material is preferably greater than 0% and not greater than 40%, which makes it possible to more effectively prevent cracks from occurring when the mat material is wound.

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

[0026] In the mat material of the present invention, the sheet material is preferably made of at least one of an organic material and an inorganic material, which can more effectively prevent cracks from occurring when the mat material is wrapped around the sheet material.

[0027] The sheet material is preferably made of an organic material, which can more effectively prevent cracks from occurring when the mat material is wrapped around the sheet material.

[0028] In the mat material of the present invention, the material of the sheet material is preferably polyethylene terephthalate, polyethylene, or polypropylene, which can more effectively prevent cracks from occurring when the mat material is wrapped around the sheet material.

[0029] In the mat material of the present invention, the base mat preferably further contains at least one of an inorganic binder and an organic binder. When the base mat contains an inorganic binder, the holding force for holding the exhaust gas treatment body, etc. can be improved. When the base mat contains an organic binder, the scattering of inorganic fibers contained in the base mat can be prevented.

[0030] The exhaust gas purification device of the present invention is an exhaust gas purification device comprising an exhaust gas treatment body through which exhaust gas flows, a holding sealing material that is wrapped around the outer periphery of the exhaust gas treatment body, and a casing that houses the exhaust gas treatment body around which the holding sealing material is wrapped, and is characterized in that the holding sealing material is the mat material of the present invention.

[0031] As described above, the mat material of the present invention can suppress the occurrence of cracks during winding, and therefore the exhaust gas purification device of the present invention can suppress the leakage of untreated exhaust gas through cracks in the mat material.

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

[0033] The method for manufacturing a mat material of the present invention uses a laminated sheet material in which vertically oriented fibers and horizontally oriented fibers are laminated as the sheet material, thereby reducing the anisotropy of the tensile strength of the sheet material, and therefore, a large number of mat materials whose wrapability falls within the standard values ​​can be obtained from a single large adhesive body.

[0034] In the method for producing a mat material of the present invention, the sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ Since the number of sheets is equal to or less than 1 / piece, the sheet material can be placed in closer contact with the base mat, which makes it possible to prevent cracks from occurring when the mat material is wound around the base mat.

[0035] In the method for producing the mat material of the present invention, the average opening area of ​​the sheet material is 0.7 mm ２ If the number exceeds 1 / piece, it becomes difficult to prevent cracks from occurring when the mat material is wound.

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

[0037] (Detailed Description of the Invention) The mat material, exhaust gas purification device, and method for manufacturing the mat material of the present invention will be specifically described below. However, the present invention is not limited to the following configurations, and can be appropriately modified and applied within the scope that does not change the gist of the present invention. Note that a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0038] The mat material of the present invention includes a base mat containing inorganic fibers and having first and second main surfaces, and a sheet material placed on at least one of the first and second main surfaces, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, and the sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ / or less.

[0039] FIG. 1 is a perspective view schematically illustrating an example of a mat material. The mat material 10 shown in FIG. 1 has a structure in which a sheet material 30 is superimposed on the first main surface 21 of a substrate mat 20 having a first main surface 21 and a second main surface 22. Of the longitudinal ends of the mat material 10 (the direction indicated by the double-headed arrow L in FIG. 1 ), a convex portion 11 is formed at one end, i.e., a first end, and a concave portion 12 is formed at the other end, i.e., a second end. The convex portions 11 and the concave portions 12 are formed by overlapping the convex portions and concave portions provided on the substrate mat 20 and the sheet material 30, respectively. The convex portions and concave portions of the mat material are shaped to fit together 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. Note that in FIG. 1 , the direction indicated by the double-headed arrow W is the widthwise direction of the mat material, and the direction indicated by the double-headed arrow T is the thickness direction of the mat material.

[0040] 1 shows the case where the sheet material 30 is placed only on the first main surface 21 of the base mat 20, but the sheet material 30 may be placed on each of the first main surface 21 and the second main surface 22 of the base mat 20. Furthermore, in addition to the first main surface 21 and / or the second main surface 22 of the base mat 20, the sheet material 30 may also be placed on the side surfaces of the base mat 20.

[0041] FIG. 2 is an enlarged perspective view schematically illustrating the sheet material shown in FIG. 1 . FIG. 3 is a plan view of the sheet material shown in FIG. 2 . FIG. 4 is a side view of the sheet material shown in FIG. 2 . Note that in FIGS. 2 to 4 , the substrate mat 20 is also indicated by a dashed line to show the relative positioning of the sheet material 30 and the substrate mat 20. As shown in FIGS. 2 to 4 , the sheet material 30 is a laminated sheet material in which longitudinally oriented fibers 31 and laterally oriented fibers 32 are stacked. The orientation direction of the longitudinally oriented fibers 31 is the vertical direction, which is parallel to the longitudinal direction of the mat material 10 (the direction indicated by the double-headed arrow L). The orientation direction of the laterally oriented fibers 32 is the horizontal direction, which is parallel to the lateral direction of the mat material 10 (the direction indicated by the double-headed arrow W). As an example, FIGS. 2 to 4 show a case in which the angle between the orientation direction of the longitudinally oriented fibers 31 and the orientation direction of the laterally oriented fibers 32 is approximately 90°. The sheet material 30 is a nonwoven fabric with longitudinal and transverse fiber orientation, formed by laminating longitudinally oriented fibers 31, in which the fibers are oriented (aligned) in the vertical direction, and transversely oriented fibers 32, in which the fibers are oriented (aligned) in the horizontal direction. The sheet material 30 is produced using a manufacturing process in which raw materials are directly spun, and the spun fibers are stretched in both the vertical and horizontal directions, thereby uniformly oriented (aligned) the long fiber filaments in both the vertical and horizontal directions. Furthermore, the sheet material 30 has a high uniformity of basis weight due to the aligned fibers, and further has a smooth structure due to the small amount of overlapping of the fibers.

[0042] The longitudinally oriented fibers 31 and the laterally oriented fibers 32 are bonded to each other. The method for bonding the longitudinally oriented fibers 31 and the laterally oriented fibers 32 is not particularly limited, and examples thereof include a water jet method, a needle punch method, a through-air method, a thermal embossing method, an adhesive bonding method, a stitch bond method, an ultrasonic sealing method, and an induction heat sealing method.

[0043] 2 and 3, the sheet material 30 is a watermarked nonwoven fabric and has openings 35 surrounded by longitudinally oriented fibers 31 and transversely oriented fibers 32. As shown in FIG. 3, each opening 35 is substantially square or rectangular and is defined by the longitudinally oriented fibers 31 and the transversely oriented fibers 32.

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

[0045] The substrate mat constituting the mat material of the present invention is made of inorganic fibers. The inorganic fibers are not particularly limited and may be alumina-silica fibers, alumina fibers, silica fibers, etc. Glass fibers or biosoluble fibers may also be used. 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.

[0046] 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.

[0047] The substrate mat has a longitudinal direction, which is the wrapping direction, and a lateral direction perpendicular to the longitudinal direction. It is preferable that the substrate mat has a convex portion formed at one of the longitudinal ends, i.e., a first end, and a concave portion formed at the other end, i.e., a second end. It is preferable that the convex portion and the concave portion of the substrate mat are shaped so that they fit together perfectly when the mat material is wrapped around an exhaust gas purification device, an exhaust gas treatment body, or an exhaust pipe, which has a cylindrical outer periphery. Alternatively, the substrate mat may have a shape in which no convex portion or concave portion is formed.

[0048] The thickness of the base mat is preferably 2 to 30 mm. If the thickness of the base mat is less than 2 mm, the thickness is too thin, resulting in reduced thermal insulation and soundproofing performance. On the other hand, if the thickness of the base mat exceeds 30 mm, the flexibility decreases, resulting in reduced attachment to the component to which it is attached.

[0049] The bulk density of the base mat is not particularly limited, but is preferably 0.05 to 0.30 g / cm ３ It is preferable that the bulk density of the base mat is 0.05 g / cm ３ If the bulk density of the base mat is less than 0.30 g / cm, the entanglement of the inorganic fibers is weak and the inorganic fibers are easily peeled off, making it difficult to maintain the desired shape of the base mat. ３ If the hardness exceeds 100%, the base mat becomes hard, the attachability to the member to be attached decreases, and the base mat becomes more likely to crack.

[0050] The sheet material constituting the mat member of the present invention is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated. Therefore, the sheet material has similar properties in both the longitudinal and transverse directions, and can exhibit isotropic tensile strength. As a result, the mat member of the present invention is configured to have stable winding properties within the specified range. The direction in which the lengthwise direction of the fibers constituting the longitudinally oriented fibers is aligned is the orientation direction of the longitudinally oriented fibers, and the direction in which the lengthwise direction of the fibers constituting the transversely oriented fibers is aligned is the orientation direction of the longitudinally oriented fibers.

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

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

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

[0054] Furthermore, the sheet material may have a large number of openings with various different shapes.

[0055] If the openings in the sheet material are large, the adhesion between the sheet material and the base mat deteriorates, and cracks occur when the mat material is wound around the sheet material. Therefore, it is preferable that the openings in the sheet material be as small as possible. Specifically, the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ This increases the adhesion between the sheet material and the base mat, making it possible to suppress the occurrence of cracks when the mat material is wound around.

[0056] The average opening area of ​​the sheet material is 0.0001 mm ２ / piece or more, 0.5mm ２ / piece or less, and 0.0001 mm ２ / piece or more, 0.1mm ２ / piece or less is more preferable, and 0.0001 mm ２ / piece or more, 0.01mm ２ It is more preferable that the number is equal to or less than 1 / 10.

[0057] The average opening area of ​​the sheet material can be calculated as follows: A magnified photograph of the sheet material is taken using a microscope, the magnified photograph is imported into any graphic drawing software, a rectangle approximating each opening in the sheet material is drawn, and the area of ​​the opening is calculated by comparing the rectangle with a reference rectangle of known area. The average value of the calculated areas of all openings is then taken as the average opening area of ​​the sheet material (average area per opening).

[0058] The sheet material preferably has substantially the same planar shape as the base mat. That is, in a plan view, the arrangement areas of the sheet material and the base mat preferably substantially coincide. Furthermore, the sheet material is preferably attached to the base mat. The sheet material and the base mat may be attached, for example, via an adhesive, or by thermocompression bonding (e.g., thermal lamination) of the sheet material itself without using an adhesive.

[0059] The basis weight of the sheet material is not particularly limited, but is preferably 5 g / m２ Above, 100g / m ２ Preferably, it is 5 g / m or less. ２ Above, 50g / m ２ More preferably, it is 5 g / m or less. ２ Above, 30g / m ２ It is more preferable that the basis weight of the sheet material mentioned here is the basis weight per sheet of the sheet material.

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

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

[0062] The relationship between the orientation directions of the vertically and horizontally oriented fibers and the longitudinal and short-side directions of the mat material is not particularly limited, but it is preferable that the orientation direction of one of the vertically and horizontally oriented fibers is parallel to the longitudinal direction of the mat material, and the orientation direction of the other of the vertically and horizontally oriented fibers is parallel to the short-side direction of the mat material.

[0063] The opening rate of the sheet material is preferably more than 0% and not more than 40%, more preferably 5% to 30%, and even more preferably 10% to 25%. The opening rate of the sheet material can be calculated by calculating the area of ​​the openings using the procedure for measuring the average opening area of ​​the sheet material, and determining the ratio (percentage) of the total value of the calculated areas of all the openings to the area of ​​the sheet material in the enlarged photograph.

[0064] The sheet material is preferably made of at least one of an organic material and an inorganic material. For example, the longitudinally oriented fibers may be made of organic fibers and / or inorganic fibers, and the transversely oriented fibers may be made of organic fibers and / or inorganic fibers. The longitudinally oriented fibers and the transversely oriented fibers may be made of different materials. However, typically, when the longitudinally oriented fibers are made of organic fibers, the transversely oriented fibers are also made of organic fibers, and when the longitudinally oriented fibers are made of inorganic fibers, the transversely oriented fibers are also made of inorganic fibers.

[0065] The sheet material is preferably made of an organic material. For example, both the longitudinally oriented fibers and the transversely oriented fibers may be made of organic fibers.

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

[0067] In the mat material of the present invention, the base mat preferably further includes at least one of an inorganic binder and an organic binder. The amount of the inorganic binder used (weight of the inorganic binder / weight of the mat material) may be, for example, more than 0 wt % and not more than 15 wt %. The amount of the organic binder used (weight of the organic binder / weight of the mat material) may be, for example, more than 0 wt % and not more than 15 wt %.

[0068] As the inorganic binder, alumina sol, silica sol, etc. can be used.

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

[0070] Next, a method for producing the mat material of the present invention will be described. The method for producing the mat material of the present invention includes a substrate mat preparation step of preparing a substrate mat containing inorganic fibers and having first and second main surfaces, a sheet material preparation step of preparing a sheet material, and a sheet material installation step of installing the sheet material on at least one of the first and second main surfaces of the substrate mat, wherein the sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, and the sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ / or less.

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

[0072] In the method for manufacturing the mat member of the present invention, first, a substrate mat having first and second main surfaces and a sheet material are prepared. The structure and physical properties of the substrate mat and sheet material prepared here are the same as those of the substrate mat and sheet material described in the mat member of the present invention, so detailed description will be omitted here. However, the substrate mat and sheet material prepared here are preferably large sheets that can be punched to obtain a large number of mat members of the present invention.

[0073] The substrate mat can be obtained by various methods, for example, by a papermaking method or a needling method. In the case of the papermaking method, it can be produced, for example, by the following method. Inorganic fibers are opened and dispersed in a solvent to form a mixed solution. The mixed solution is poured into a molding machine with a filtration mesh formed on the bottom surface, and the solvent in the mixed solution is removed to obtain an inorganic fiber aggregate. The inorganic fiber aggregate is then dried to obtain a substrate mat. In the case of the needling method, it can be produced, for example, by the following method. A spinning mixture made from a basic aluminum chloride aqueous solution and silica sol, etc., is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 3 to 10 μm. Next, the inorganic fiber precursor is compressed to produce a continuous substrate mat of a predetermined size, and the substrate mat can be obtained by subjecting it to a calcination treatment. A needle-punching treatment is performed either before or after this calcination treatment to entangle the inorganic fibers.

[0074] The sheet material can be produced, for example, by the following method. First, a raw material (e.g., a resin) is melt-spun using a nonwoven fabric spinning device such as a melt-blown nonwoven fabric or a spunbond nonwoven fabric. Next, fibers are aligned in both the machine direction (MD) and the cross direction (CD) and stretched to produce a longitudinally stretched web in which a continuous body of long fiber filaments is stretched in the machine direction, and a transversely stretched web in which a continuous body of the same long fiber filaments is stretched in the transverse direction. The machine-stretched web and the transversely stretched web are then laminated and joined to produce a sheet material (laminate sheet material) in which machine-oriented fibers and transversely oriented fibers are laminated. As described above, the machine-stretched web and the transversely stretched web can be joined by, for example, a water jet method, a needle punch method, a through-air method, a thermal embossing method, an adhesive bonding method, a stitch-bonding method, an ultrasonic sealing method, an induction heat sealing method, or the like.

[0075] The sheet material thus produced has openings surrounded by longitudinally oriented fibers and transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ / or less.

[0076] Next, a sheet material is placed on at least one of the first and second main surfaces of the base mat. At this time, it is preferable to obtain an adhesive body by attaching a large-sized sheet material to a large-sized base mat. This attachment may be performed, for example, via an adhesive, or by thermocompression bonding (e.g., thermal lamination) of the sheet material itself without using an adhesive. FIG. 5 is a perspective view schematically illustrating an example of an adhesive body. The adhesive body 150 is a rectangular sheet having two longitudinal sides and two lateral sides, with a large-sized sheet material 130 attached to the first main surface 121 of a large-sized base mat 120. The sheet material 130 is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated together. The longitudinally oriented fibers of the sheet material 130 are oriented longitudinally and parallel to the two longitudinal sides of the adhesive body 150, and the transversely oriented fibers of the sheet material 130 are oriented transversely and parallel to the two lateral sides of the adhesive body 150.

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

[0078] Subsequently, the adhesive body is subjected to a punching process, whereby a mat member having a predetermined shape can be produced.

[0079] The method for manufacturing a mat material of the present invention uses a laminated sheet material in which vertically oriented fibers and horizontally oriented fibers are stacked as the sheet material, thereby reducing the anisotropy of the tensile strength of the sheet material, and therefore it is possible to obtain a large number of mat materials whose wrapability falls within the standard values ​​from a single large adhesive body.

[0080] In addition, in the method for manufacturing a mat material of the present invention, the sheet material has openings surrounded by longitudinally oriented fibers and transversely oriented fibers, and the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２Since the number of sheets is equal to or less than 1 / piece, the sheet material can be placed in closer contact with the base mat, which makes it possible to prevent cracks from occurring when the mat material is wound around the base mat.

[0081] In the punching process of the adhesive body, it is preferable to carry out a process of obtaining a first mat material in which the vertical direction of the adhesive body is the longitudinal direction of the mat material and the horizontal direction of the adhesive body is the short side direction of the mat material, and a second mat material in which the horizontal direction of the adhesive body is the longitudinal direction of the mat material and the vertical direction of the adhesive body is the short side direction of the mat material, thereby obtaining two types of mat material, the first mat material and the second mat material.

[0082] Figure 6 is a top view schematically showing the process of obtaining two types of mat materials by punching. Punching is performed on the adhesive body 150 shown in Figure 6 to obtain two types of mat materials. The left side of Figure 6 shows the production of a first mat material 1 in which the orientation direction of the longitudinally oriented fibers of the sheet material (the longitudinal direction shown in Figure 6) is the longitudinal direction of the mat material and the orientation direction of the transversely oriented fibers of the sheet material (the transverse direction shown in Figure 6) is the short-side direction of the mat material. The right side of Figure 6 shows the production of a second mat material 2 in which the orientation direction of the transversely oriented fibers of the sheet material (the transverse direction shown in Figure 6) is the longitudinal direction of the mat material and the orientation direction of the longitudinally oriented fibers of the sheet material (the longitudinal direction shown in Figure 6) is the short-side direction of the mat material.

[0083] The first mat material 1 and the second mat material 2 have the same number and density of fibers (longitudinal or horizontally oriented fibers) of the sheet material oriented in the longitudinal direction of the mat material and the same number and density of fibers (horizontal or vertically oriented fibers) of the sheet material oriented in the lateral direction of the mat material, so they exhibit approximately the same tensile strength and wrapability. In other words, the difference in wrapability between the first mat material and the second mat material is the smallest, and both mat materials achieve wrapability within the standard values. This means that a large number of mat materials with wrapability within the standard values ​​can be obtained from a single large-sized adhesive body.

[0084] In addition, in the punching process, it is preferable that the orientation direction of one of the longitudinally oriented fibers and the transversely oriented fibers of the sheet material is parallel to the longitudinal direction of the first mat material and parallel to the short direction of the second mat material. It is also preferable that the orientation direction of the other of the longitudinally oriented fibers and the transversely oriented fibers of the sheet material is parallel to the short direction of the first mat material and parallel to the longitudinal direction of the second mat material. The punching direction shown in Figure 6 is a direction that satisfies the above conditions.

[0085] As described above, the mat material manufacturing method of the present invention produces a first mat material and a second mat material. The wrapability of the first mat material and the second mat material is affected by both the orientation direction of the longitudinally oriented fibers of the sheet material and the orientation direction of the transversely oriented fibers of the sheet material. Because the orientation directions of the longitudinally oriented fibers and the transversely oriented fibers are different, these orientation directions have different effects on the wrapability of the mat material. For both the first mat material and the second mat material, the wrapability of the mat material is determined not only by the orientation direction of the longitudinally oriented fibers or the orientation direction of the transversely oriented fibers, so the effect of one orientation direction on the wrapability of the mat material is mitigated. In this way, the difference in wrapability between the first mat material and the second mat material, which are punched in different directions, is reduced, allowing the wrapability of both the first mat material and the second mat material to be within the specified values.

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

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

[0088] Fig. 7 is a cross-sectional view schematically showing an example of an exhaust gas purification apparatus of the present invention. As shown in Fig. 7, the exhaust gas purification apparatus 100 of the present invention includes a casing 50, an exhaust gas treatment body 40 housed in the casing 50 and through which exhaust gas flows, and a holding seal material 60 disposed between the exhaust gas treatment body 40 and the casing 50 and holding the exhaust gas treatment body 40. The holding seal material 60 is a mat material wrapped around the outer periphery of the exhaust gas treatment body.

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

[0090] The 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. 7 . 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 41 opening at the exhaust gas inlet end face of the exhaust gas treatment body (honeycomb filter) 40 and passes through a cell wall 42 separating the cells 41. At this time, PM in the exhaust gas is captured by the cell wall 42, and the exhaust gas is purified. The purified exhaust gas flows out of another cell 41 opening at the exhaust gas outlet end face and is discharged to the outside.

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

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

[0093] The casing may be of a generally cylindrical shape, a clamshell shape, or a generally elliptical or polygonal shape in cross section.

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

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

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

[0097] The exhaust gas treatment body 40 may be supported with a catalyst for purifying the 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 combustion and removal of PM, making it possible to purify toxic exhaust gases.

[0098] EXAMPLES The following examples more specifically disclose the present invention, but the present invention is not limited to these examples.

[0099] (Example 1) A papermaking method was used to produce a paper sheet with a basis weight (fiber weight per unit area) of 2400 g / m ２ A large substrate mat was fabricated from inorganic fibers (mullite fibers) with a fiber orientation in both the longitudinal and transverse directions, in which longitudinally oriented fibers in which PET fibers are oriented in the longitudinal direction and transversely oriented fibers in which PET fibers are oriented in the transverse direction were laminated as the large sheet material (nonwoven fabric). This sheet material has orientation in the direction in which the length of the PET fibers are aligned, and the angle between the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is approximately 90°. This sheet material also has substantially square or rectangular openings. Furthermore, this sheet material has a basis weight of 10 g / m ２ is.

[0100] The substrate mat and the sheet material were thermocompression bonded to obtain a rectangular adhesive body similar to the adhesive body shown schematically in Fig. 5. The adhesive body was then punched in the same arrangement as shown schematically in Fig. 6 to obtain two types of mat materials (a first mat material and a second mat material). In the first mat material, the orientation direction of the longitudinally oriented fibers of the sheet material is parallel to the longitudinal direction of the mat material, and in the second mat material, the orientation direction of the transversely oriented fibers of the sheet material is parallel to the longitudinal direction of the mat material.

[0101] Comparative Example 1 A large-sized substrate mat was prepared in the same manner as in Example 1. A nonwoven fabric with randomly oriented PET fibers was prepared as a large-sized sheet member. However, the lengthwise direction of the PET fibers was the machine direction (MD), and the PET fibers were loosely oriented in that direction. This sheet member also had randomly shaped openings, such as parallelograms. The substrate mat and the sheet member were thermocompression-bonded to obtain a rectangular adhesive body with two longitudinal sides and two lateral sides. The adhesive body was then punched in the same manner as in Example 1 to obtain two types of mat members (a first mat member and a second mat member). In the first mat member, the lengthwise direction of the PET fibers of the sheet member was parallel to the longitudinal direction of the mat member, while in the second mat member, the lengthwise direction of the PET fibers of the sheet member was parallel to the lateral direction of the mat member. FIG. 8 is an enlarged plan view schematically illustrating the sheet member of Comparative Example 1. The sheet material 30' of Comparative Example 1 has longitudinally oriented fibers 31 but does not have transversely oriented fibers. The openings 35 are formed by being surrounded by the longitudinally oriented fibers 31.

[0102] Comparative Example 2 A large-sized substrate mat was produced in the same manner as in Example 1. A large-sized sheet material was prepared by laminating and heat-sealing a longitudinal web with fiber orientation in the longitudinal direction, obtained by splitting a longitudinally stretched polyolefin film, and a transverse web with fiber orientation in the transverse direction, obtained by splitting a transversely stretched polyolefin film. This sheet material had a substantially square or rectangular opening. The substrate mat and the sheet material were heat-pressed together to obtain a rectangular adhesive body with two longitudinal sides and two transverse sides. The adhesive body was then punched in the same manner as in Example 1 to obtain two types of mat materials (a first mat material and a second mat material). In the first mat material, the orientation direction (longitudinal direction) of the longitudinal web of the sheet material was parallel to the longitudinal direction of the mat material, and in the second mat material, the orientation direction (transverse direction) of the transverse web of the sheet material was parallel to the longitudinal direction of the mat material.

[0103] (Measurement of Average Opening Area and Opening Ratio) Enlarged photographs of the sheet material used in Example 1 and Comparative Example 2 were taken using a microscope. The enlarged photographs were imported into any graphic drawing software, and a rectangle approximating each opening in the sheet material was drawn. The area of ​​the opening was calculated by comparing the rectangle with a reference rectangle of known area. The average value of the calculated areas of all openings was then taken as the average opening area of ​​the sheet material (average area per opening). The ratio (percentage) of the total area of ​​all calculated openings to the area of ​​the sheet material in the enlarged photograph was taken as the opening ratio. The results are shown in Table 1.

[0104] (Winding Test) Two types of mat materials (first mat material and second mat material) manufactured in each Example and Comparative Example were each wrapped around a cylindrical substrate having a diameter of 200 mm. During wrapping, the substrate mat was positioned on the substrate side, with the sheet material facing outward. The total length of the wrapped mat material, including the longitudinal dimension (mat dimension) and the gap (seam gap) between the convex and concave portions where the convex and concave portions fit together, was measured. The total length was measured for each of the two types of mat materials, and the difference (difference between first mat material and second mat material) was calculated. The results are shown in Table 1. ○ indicates good, and × indicates poor. The smaller the difference between the first and second mat materials, the more homogeneous the mat material.

[0105] (Presence or absence of cracks in mat material) The two types of mat materials manufactured in each example and comparative example were checked for the presence or absence of cracks after the winding test. The results are shown in Table 1. In the presence or absence of cracks, ○ indicates no cracks and × indicates the presence of cracks.

[0106]

[0107] From these results, it can be seen that by using a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, the difference in the mat dimensions and the total length of the seam gap between the first and second mat materials is reduced. This means that two types of mat materials with similar winding properties can be obtained, and that a large number of mat materials with good winding properties can be obtained from a single large-sized adhesive body. In addition, when the average opening area of ​​the sheet material is 0 mm ２ / piece, more than 0.7 mm ２ It can be seen that by setting the number of cracks to 1 / 1 or less, it is possible to prevent cracks from occurring during winding of the mat material. Fig. 9 is a photograph of the mat material of Comparative Example 2. As shown in Fig. 9, cracks occurred in the area surrounded by the dashed line in the mat material of Comparative Example 2 after the winding test.

[0108] REFERENCE SIGNS LIST 1 First mat material 2 Second mat material 10 Mat material 11 Convex portion 12 Concave portion 20, 120 Base material mat 21, 121 First main surface of base material mat 22 Second main surface of base material mat 30, 130 Sheet material 31 Vertically oriented fibers 32 Horizontally oriented fibers 35 Opening 40 Exhaust gas treatment body 41 Cell 42 Cell wall 43 Sealing material 50 Casing 60 Holding seal material 100 Exhaust gas purification device 150 Adhesive body

Claims

1. A mat material comprising an inorganic fiber and having a substrate mat with first and second main surfaces, A sheet material provided on at least one of the first and second main surfaces, A mat material having, The sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, The sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, The average opening area of the sheet material is more than 0 mm ２ / piece and 0.7 mm ２ / piece or less, and the mat material is characterized by this.

2. The mat material according to claim 1, wherein the angle formed by the orientation direction of the longitudinally oriented fibers and the orientation direction of the transversely oriented fibers is 60° or more and 120° or less.

3. The mat material according to claim 1 or 2, wherein the aperture ratio of the sheet material exceeds 0% and is 40% or less.

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

5. The mat material according to claim 4, wherein the sheet material is composed of an organic substance.

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

7. The mat material according to claim 1 or 2, wherein the substrate mat further includes at least one of an inorganic binder and an organic binder.

8. An exhaust gas treatment body through which exhaust gas flows, A holding seal material used by being wound around the outer periphery of the exhaust gas treatment body, A casing for housing the exhaust gas treatment body around which the holding seal material is wound, An exhaust gas purification device comprising, The exhaust gas purification device, wherein the holding seal material is the mat material according to claim 1 or 2.

9. A substrate mat preparation step of preparing a substrate mat containing inorganic fibers and having first and second main surfaces, A sheet material preparation step of preparing a sheet material, A sheet material installation step of installing the sheet material on at least one of the first and second main surfaces of the substrate mat, A method for manufacturing a mat material having, The sheet material is a laminated sheet material in which longitudinally oriented fibers and transversely oriented fibers are laminated, The sheet material has openings surrounded by the longitudinally oriented fibers and the transversely oriented fibers, The average opening area of the sheet material is more than 0 mm ２ / piece and not more than 0.7 mm ２ / piece, and a method for manufacturing a mat material characterized by this.