Mat material and exhaust gas purification device

Abstract

This mat material comprises: a laminated mat in which a plurality of mats including inorganic fibers and each having a rectangular shape in a plan view are laminated; and a fixing member for fixing the laminated mat. The mat material is characterized in that: the plurality of mats include a first mat and a second mat; and, regarding a sagging amount measured through a sagging test by laminating and fixing two mats of the same type, the sagging amount of the first mat is larger than the sagging amount of the second mat, and the sagging amount of the mat material measured with the second mat below and the first mat up is 60 mm or less.

Description

Mat material and exhaust gas purification device

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

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

[0003] 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) disposed between the exhaust gas treatment body and the metal casing. This holding seal material (mat material) is disposed mainly for the purposes of preventing damage to the exhaust gas treatment body due to contact with the metal casing that surrounds it due to 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 mat material in which a plurality of mats made of inorganic fibers are stacked and bound together by a strip.

[0005] JP 2012-233433 A

[0006] When wrapping the mat material around the exhaust gas treatment body, the mat material may be transported in the work area while being partially gripped. Because the mat material is used by wrapping it around the exhaust gas treatment body and is flexible, if part of the mat material is gripped while being transported, part of the mat material will sag due to gravity.

[0007] Here, if the mat material is soft and sags a lot, it may collide with other equipment or pillars in the workplace during transport, so there is a need to reduce the amount of sagging.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to provide a mat material that can prevent the mat material from sagging.

[0009] The mat material of the present invention comprises a laminated mat in which a plurality of mats each containing inorganic fibers and having a rectangular shape in plan view are stacked, and a fixing member for fixing the laminated mat, wherein the plurality of mats include a first mat and a second mat, and a sagging test is conducted in which two mats of the same type are stacked and fixed together, and the sagging amount of the first mat is greater than the sagging amount of the second mat, and the sagging amount of the mat material measured with the second mat underneath and the first mat on top is 60 mm or less.

[0010] The mat material of the present invention includes a first mat and a second mat with different sagging amounts. The first mat is prone to sagging, while the second mat is resistant to sagging. When the first and second mats are combined to form a laminated mat and transported, the second mat is resistant to sagging, so even if the mat material contains the first mat, which is prone to sagging, the mat material as a whole is resistant to sagging, and the sagging amount of the mat material can be reduced to 60 mm or less. This results in a mat material that can prevent sagging.

[0011] In the mat material of the present invention, it is preferable that the mat further contains an organic binder, and the content of the organic binder is 10.0 wt % or less with respect to the weight of the laminated mat.

[0012] Incorporating an organic binder into the mat increases the strength of the mat, resulting in a mat material that is less likely to sag. However, mat materials are used in exhaust gas purification equipment, and the high-temperature environment in which the exhaust gas purification equipment is used can cause the organic binder to volatilize. Therefore, mat materials intended for use in exhaust gas purification equipment are required to contain a low organic binder content. Increasing the organic binder content in the mat makes the mat harder and less likely to sag. However, since the first mat can be a mat that is prone to sagging, a mat with a low organic binder content can be used as the first mat. By using a first mat with a low organic binder content, sagging of the mat material can be prevented even if the organic binder content in the entire laminated mat is reduced to 10.0 wt % or less.

[0013] In the mat material of the present invention, it is preferable that the content of the organic binder in the second mat is greater than the content of the organic binder in the first mat.

[0014] Increasing the organic binder content in the mat makes the mat harder and less prone to sagging, so increasing the organic binder content of the second mat compared to the organic binder content of the first mat can be used as a means for reducing the amount of sagging of the second mat compared to the amount of sagging of the first mat.

[0015] In the mat material of the present invention, it is preferable that the content of the organic binder in the first mat is 0.1% by weight or more and less than 4.0% by weight, and the content of the organic binder in the second mat is 4.0% by weight or more and 12.0% by weight or less.

[0016] When the organic binder content of the second mat is 4.0% by weight or more and 12.0% by weight or less, the second mat is hard and has a small amount of sagging, which is effective in preventing sagging of the entire mat material. On the other hand, when the organic binder content of the first mat is 0.1% by weight or more and less than 4.0% by weight, the organic binder content is low, which is effective in suppressing the organic binder content to a predetermined amount or less.

[0017] In the mat material of the present invention, it is preferable that the length of the second mat in the longitudinal direction is longer than the length of the first mat in the longitudinal direction.

[0018] By placing the second mat, which is longer in the longitudinal direction, on the outside during wrapping, the influence of the difference in the inner and outer circumferences due to wrapping can be alleviated, and the mat material can be used as a mat material with good wrapping properties. Also, by placing the first mat, which is soft and has a relatively large amount of sagging, on the inside during wrapping, the mat material can be easily wrapped around the outer circumference of the object to be wrapped.

[0019] In the mat material of the present invention, it is preferable that both the first mat and the second mat are needle mats. Also, in the mat material of the present invention, it is preferable that both the first mat and the second mat are paper-made mats.

[0020] The fact that the first mat and the second mat are both needle mats or both paper-made mats means that the first mat and the second mat are of the same type, i.e., the amount of sagging of the first mat and the second mat is not different due to the difference in the type of mat material.

[0021] In the mat material of the present invention, it is preferable that the fixing member is a strip that is wrapped around the laminated mat to fix the laminated mat. Also, in the mat material of the present invention, it is preferable that the fixing member is a sewing thread that is sewn to the laminated mat to fix the laminated mat. Also, in the mat material of the present invention, it is preferable that the fixing member is an adhesive that bonds the multiple mats together to fix the laminated mats.

[0022] By fixing the laminated mat with these fixing members, a mat member can be formed in which a plurality of mats are laminated and fixed.

[0023] The exhaust gas purification device of the present invention is an exhaust gas purification device comprising: an exhaust gas treatment body; a metal casing that houses the exhaust gas treatment body; and a mat material that is arranged between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body, wherein the mat material is the mat material of the present invention, and the first mat is arranged on the exhaust gas treatment body side.

[0024] In the exhaust gas purification apparatus of the present invention, the organic binder content of the mat material is set to a predetermined amount or less, so that the amount of volatilization of the organic binder can be suppressed even when the exhaust gas purification apparatus is exposed to a high-temperature environment during use. Furthermore, when wrapping the mat material around the exhaust gas treatment body, sagging of the mat material can be effectively prevented by transporting the mat material with the second mat on the bottom and the first mat on the top. When the mat material is transported in this arrangement and wrapped around the exhaust gas treatment body, the first mat is positioned on the exhaust gas treatment body side.

[0025] Fig. 1 is a perspective view schematically showing an example of a mat material. Fig. 2 is a side view for explaining a sagging test. Fig. 3 is a cross-sectional view schematically showing an example of an exhaust gas purification device. Fig. 4 is a perspective view schematically showing an example of a mat material in which the fixing member is a sewing thread. Fig. 5 is a perspective view schematically showing an example of a mat material in which the fixing member is an adhesive.

[0026] An example of a mat material and an exhaust gas purification device according to 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 material. The mat material 10 shown in Fig. 1 includes a laminated mat 20 formed by stacking multiple mats, and a fixing member 30 for fixing the mats. In the mat material 10 shown in Fig. 1, the fixing member 30 is a strip-shaped body wrapped around the laminated mat 20.

[0027] The laminated mat 20 is formed by laminating two mats, a first mat 21 and a second mat 22. The first mat 21 and the second mat 22 are arranged in a longitudinal direction (indicated by a double-headed arrow L in FIG. 1 ). １ and L ２ The first mat 21 is a mat whose length in the longitudinal direction (direction indicated by a double arrow L) is longer than the second mat 22. １The second mat 22 is a mat whose length in the longitudinal direction is longer than that of the first mat 21, and its length in the longitudinal direction is indicated by a double-headed arrow L ２ is shown.

[0028] The laminated mat 20 has two main surfaces, the main surface having the shortest length in the longitudinal direction of the mat is the first main surface 23, and the main surface having the longest length in the longitudinal direction of the mat is the second main surface 24. The first main surface 23 is the upper main surface of the first mat 21, and the second main surface 24 is the lower main surface of the second mat 22.

[0029] The laminated mat 20 has four side surfaces, with the side surfaces along the longitudinal direction of the mat being a first long side surface 25 and a second long side surface 26. The side surfaces along the width direction of the mat (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. A recess is formed on the first short side surface 27, and a protrusion is formed on the second short side surface 28. The recess and protrusion are shaped to fit together when the mat material is wrapped around an exhaust gas purification device, exhaust gas treatment body, or exhaust pipe having a cylindrical outer periphery. In the mat material of this embodiment, the fitting portions are shaped as a recess and a protrusion, but the fitting portions may also be shaped as an L-shaped combination. In FIG. 1 , the direction indicated by the double-headed arrow T is the thickness direction of the mat material.

[0030] 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.

[0031] 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.

[0032] The number of mats stacked in the laminated mat is not particularly limited as long as it is plural. Two or three mats are preferable, and two mats are more preferable. When the number of mats is three or more, one of the mats located on the outermost side of the laminated mat is referred to as the first mat, and the other is referred to as the second mat.

[0033] The preferred range of dimensions of the laminate mat is as follows: １ The length indicated by the double-headed arrow W in FIG. 1 is the longitudinal length of the first mat 21 having the first main surface 23, and is preferably 333 mm or more and 1500 mm or less. The width direction length of the laminated mat (the length indicated by the double-headed arrow W in FIG. 1) is preferably 40 to 400 mm. The thickness of the laminated mat (the length indicated by the double-headed arrow T in FIG. 1) is preferably 4 to 60 mm. If the thickness of the laminated mat is less than 4 mm, it is too thin, resulting in reduced thermal insulation and soundproofing performance. On the other hand, if the thickness of the laminated mat exceeds 60 mm, flexibility decreases, and attachment to the component to which it is attached becomes difficult.

[0034] The laminate mat has a longitudinal direction, which is the wrapping direction, and a lateral direction perpendicular to the longitudinal direction. It is preferable that the laminate 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 laminate mat are shaped so that they fit together perfectly when the laminate mat is wrapped around an exhaust gas purification device, an exhaust gas treatment body, or an exhaust pipe, which has a cylindrical outer periphery. The laminate mat may also have a shape in which no convex portion or concave portion is formed. In addition, although the shape of the fitting portions in the laminate mat of this embodiment is a concave-convex portion, the shape of the fitting portions may also be an L-shaped combination.

[0035] The first mat and the second mat included in the mat material have different sagging amounts. The sagging amount in the mat material of the present invention will be explained. FIG. 2 is a side view for explaining the sagging test. The sagging amount is measured by a sagging test in which two mats of the same type are stacked. The term "mats of the same type" means mats with the same composition, dimensions, etc. FIG. 2 shows a laminated mat 20 in which two second mats 22 are stacked.

[0036] When measuring the amount of sagging, two mats of the same type are stacked to form a laminated mat, and the laminated mat is fixed at the center in the longitudinal direction with a fixing member. The fixing conditions using the fixing member are the same as the fixing conditions for the target mat material. Figure 2 shows the laminated mat 20 fixed by wrapping a strip-shaped member as the fixing member 30 around it.

[0037] The amount of sagging is measured by simulating the state in which a portion of the mat material is gripped and transported, and measuring the amount of sagging in a state in which a portion of the mat material is allowed to sag using a jig. Figure 2 shows how the mat material 10 is gripped by gripping portions 41a and 41b of a jig 40 to measure the amount of sagging. The distance between gripping portions 41a and 41b (the distance along the longitudinal direction of the mat material) is indicated by a double-headed arrow B. The distance B between the gripping portions is the same as the dimension X of the fixing member 30 in the longitudinal direction of the mat material.

[0038] When the mat material is gripped as shown in Figure 2, the longitudinal ends of the mat material hang down. The amount of this hanging down (the length indicated by the double-headed arrow D in Figure 2) is measured and taken as the amount of sagging of the mat.

[0039] If the amount of sagging of a mat material comprising a laminated mat formed by stacking two mats used as the first mat is D1 and the amount of sagging of a mat material comprising a laminated mat formed by stacking two mats used as the second mat is D2, then D1 > D2. The first mat and second mat having such a relationship are combined to form a laminated mat, which is then fixed with a fixing member to form the mat material.

[0040] The mat material of the present invention is a laminated mat comprising a first mat and a second mat, and when measured with the second mat on the bottom and the first mat on the top, the sagging amount of the mat material is 60 mm or less. The first mat is a mat material that is prone to sagging, and the second mat is a mat material that is not prone to sagging. By placing the second mat on the bottom and the first mat on the top, even if the first mat sags, the second mat, which is less prone to sagging, is located below the first mat, and the sagging portion of the first mat is supported by the second mat. As a result, the sagging amount of the entire mat material is determined almost entirely by the sagging amount of the second mat. Conversely, if the sagging amount is measured with the first mat on the bottom and the second mat on the top, the first mat will sag without being supported, and the sagging amount of the entire mat material will be determined almost entirely by the sagging amount of the first mat, resulting in a mat material with a large sagging amount overall. Therefore, when transporting the mat material of the present invention, transporting it with the second mat on the bottom will reduce the sagging amount.

[0041] With regard to the mat material of the present invention, the amount of sagging of the mat material measured with the second mat underneath and the first mat on top is preferably 50 mm or less, more preferably 40 mm or less.

[0042] The sagging amount of each of the first mat and the second mat is not particularly limited, but as a sagging amount measured in a sagging test using two mats of the same type stacked together, the sagging amount of the first mat is preferably 40 to 120 mm, more preferably 70 to 100 mm. The sagging amount of the second mat is preferably 60 mm or less, more preferably 50 mm or less, and even more preferably 40 mm or less. It is also preferably 20 mm or more. The sagging amount may be measured using a mat with a longitudinal length of 600 mm, a width of 100 mm, and a thickness of 8 mm, with the distance between the gripping portions set to 300 mm.

[0043] The first mat and the second mat have different amounts of sagging, and one method for making the amounts of sagging different between the first mat and the second mat is to add an organic binder to the mat to adjust its strength. That is, in the mat material of the present invention, it is preferable that the mat further includes an organic binder. Since the addition of an organic binder increases the strength of the mat and makes it less likely to sag, it is preferable to add an organic binder to the second mat. It is also preferable to add an organic binder to both the first mat and the second mat so that the organic binder content of the second mat is greater than the organic binder content of the first mat.

[0044] In the mat material of the present invention, the organic binder content is preferably 10.0 wt% or less relative to the weight of the laminated mat. The mat material is used in an exhaust gas purification device, but the environment in which the exhaust gas purification device is used is a high-temperature environment, so the organic binder may volatilize. Therefore, it is required that the organic binder content of mat materials intended for use in exhaust gas purification devices not be high. As a guideline for the organic binder content, an organic binder content of 10.0 wt% or less relative to the weight of the laminated mat is unlikely to cause practical problems. In the mat material of the present invention, the first mat may be a mat that is prone to sagging, so a mat with a low organic binder content can be used as the first mat. By using a first mat with a low organic binder content, sagging of the mat material can be prevented even if the organic binder content of the entire laminated mat is reduced to 10.0 wt% or less.

[0045] Examples of organic binders include rubber-based resins, styrene-based resins, silicone-based resins, acrylic-based resins, polyester-based resins, polyurethane resins, etc. The organic binder can be incorporated into the mat by adhering an emulsion liquid containing an acrylic resin, a rubber-based resin, or the like as a polymer resin component to inorganic fibers and then removing the solvent.

[0046] The glass transition temperature of the organic binder is preferably 5° C. or lower, more preferably −5° C. or lower, even more preferably −10° C. or lower, and particularly preferably −30° C. or lower.

[0047] In the mat material of the present invention, the organic binder content of the first mat is preferably 0.1 wt % or more and less than 4.0 wt %, and the organic binder content of the second mat is preferably 4.0 wt % or more and 12.0 wt % or less.

[0048] When the organic binder content of the second mat is 4.0 wt % or more and 12.0 wt % or less, the second mat is hard and has a small amount of sagging, which is effective in preventing sagging of the entire mat material.More preferably, the organic binder content of the second mat is 7.0 wt % or more and 12.0 wt % or less.

[0049] When the organic binder content of the first mat is 0.1 wt % or more and less than 4.0 wt %, the mat has a low organic binder content, and is therefore effective for suppressing the organic binder content to a predetermined level or less.More preferably, the organic binder content of the first mat is 0.2 wt % or more and 2.0 wt % or less.

[0050] The ratio of the content of the organic binder in the second mat to the content of the organic binder in the first mat is preferably 3.5 to 60.

[0051] The first mat and the second mat may each contain an inorganic binder. The strength and sagging amount of the mat can also be adjusted by changing the content of the inorganic binder.

[0052] In the mat material of the present invention, the fixing member is preferably a strip, and the strip is preferably wrapped around the laminated mat to fix the laminated mat.

[0053] The dimension of the strip-shaped mat material in the longitudinal direction is the length indicated by the double-headed arrow X in Fig. 1, and this length is preferably 20 to 400 mm. If the strip-shaped body is long, the area for fixing the mat material is wide, making it less likely for the mat material to sag, but if the strip-shaped body is long, the winding ability decreases.

[0054] It is preferable that the strip be provided in a region including the center in the longitudinal direction of the mat material, thereby fixing the laminated mat at the center in the longitudinal direction of the mat material. Alternatively, the strip may be divided into multiple pieces and wrapped around the mat to fix the laminated mat. In this case, it is preferable that the region sandwiched between the multiple strips includes the center in the longitudinal direction of the mat material. Furthermore, the dimension of the strip in the longitudinal direction of the mat material is the width of the region sandwiched between the multiple strips.

[0055] The strip preferably comprises at least one material selected from the group consisting of organic materials, ceramic materials, and metallic materials.

[0056] When the strip is made of an organic material, the organic material is not particularly limited. Examples include paper, resin film, and nonwoven fabric made of organic fibers. The strip is preferably made of at least one resin selected from the group consisting of polyester, polyethylene, and polypropylene. These materials are preferred because they have excellent flexibility and elasticity and can be attached to the laminate mat by heat sealing.

[0057] An example of a nonwoven fabric made of organic fibers is one in which PE (polyethylene terephthalate) powder is fused to PET (polyethylene terephthalate) fibers. Other usable organic fibers include PP (polypropylene) and rayon. When the strip is a resin film, examples of the organic material constituting the resin film include PET (polyethylene terephthalate), PP (polypropylene), and PE (polyethylene).

[0058] When the strip is made of a ceramic material, the ceramic material is not particularly limited. Examples include sheets of alumina, silica, titania, etc. Alternatively, the ceramic material may be a cloth made of ceramic fibers, such as alumina cloth, silica cloth, or titania cloth.

[0059] When the strip is made of a metal material, the metal material is not particularly limited. Examples include a sheet of stainless steel, aluminum, nickel, etc. Alternatively, the strip may be a mesh made of metal fibers, such as a stainless steel mesh or an aluminum mesh.

[0060] The strips may not be bonded to the laminate mat, and if the strips are not bonded to the laminate mat, the positions of the mats constituting the laminate mat can be adjusted.

[0061] The strip may also be bonded to the laminate mat via an adhesive. When the strip is made of an organic material, the strip may be bonded to the laminate mat by heat-sealing the strip itself to the laminate mat without using an adhesive. When bonding the strip to the laminate mat via an adhesive, an acrylic adhesive, an acrylate latex, a urethane adhesive, an epoxy resin adhesive, or the like can be used as the adhesive. When heat-sealing the strip itself to the laminate mat, the heat-sealing can be performed at a heating temperature appropriate for the type of organic material constituting the strip.

[0062] It is preferable that the length of the second mat in the longitudinal direction is longer than the length of the first mat in the longitudinal direction. In Figure 1, the mat with a longer length in the longitudinal direction is shown as the second mat 22, and the mat with a shorter length in the longitudinal direction is shown as the first mat 21.

[0063] By placing the second mat, which is longer in the longitudinal direction, on the outside during wrapping, the influence of the difference in inner and outer circumferences during wrapping is mitigated, resulting in a mat material with good wrapping properties. Furthermore, by placing the first mat, which is softer and has a relatively large amount of sagging, on the inside during wrapping, the mat material can be more easily wrapped around the outer circumference of the object to be wrapped. Furthermore, by transporting the second mat, which is longer in the longitudinal direction and has a small amount of sagging, on the bottom, transport is stable and problems caused by sagging of the mat material during transport are eliminated.

[0064] The mats constituting the laminated mat can be obtained by various methods, but can be manufactured by, for example, a papermaking method or a needling method. In the case of the papermaking method, for example, the mat can be manufactured by the following method. Inorganic fibers are opened and dispersed in a solvent to form a mixed liquid. The mixed liquid is poured into a molding machine with a filtration mesh formed on the bottom surface, and the solvent in the mixed liquid is removed to obtain an inorganic fiber aggregate. The inorganic fiber aggregate is then dried to obtain a mat. In the case of the needling method, for example, the mat can be manufactured 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 sheet-like product of a predetermined size, and a calcination treatment is performed to obtain a mat. A needle-punching treatment is performed either before or after this calcination treatment to entangle the inorganic fibers.

[0065] It is preferable that both the first mat and the second mat are needle mats. A needle mat is a mat produced by a needling method. Alternatively, both the first mat and the second mat may be paper-formed mats. A paper-formed mat is a mat produced by a paper-forming method.

[0066] The fact that the first mat and the second mat are both needle mats or both paper-made mats means that the first mat and the second mat are of the same type, i.e., the amount of sagging of the first mat and the second mat is not different due to the difference in the type of mat material.

[0067] It is also preferable to apply an organic binder to the first mat and the second mat, and by adjusting the amount of the organic binder applied, the amount of sagging of the first mat and the second mat can be adjusted, thereby obtaining first mats and second mats with sagging amounts adjusted to an appropriate range.

[0068] The first mat and the second mat are stacked to form a laminated mat, and the laminated mat is fixed by a method such as wrapping a strip around it, thereby obtaining the mat material of the present invention.

[0069] Fig. 3 is a cross-sectional view showing an example of an exhaust gas purification apparatus. As shown in Fig. 3, the exhaust gas purification apparatus 100 of the present invention includes a metal casing 110, an exhaust gas treatment body 120 housed in the metal casing 110, and a mat material 10 disposed between the exhaust gas treatment body 120 and the metal casing 110.

[0070] The exhaust gas treatment body 120 is a columnar body with a large number of through holes 121 arranged in parallel in the longitudinal direction separated by partition walls 122. Note that, to the ends of the metal casing 110, 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 as necessary.

[0071] 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. 3. As shown in Fig. 3, exhaust gas discharged from an internal combustion engine and flowing into the exhaust gas purification device 100 (in Fig. 3, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by arrows) flows into through-holes 121 opened at the exhaust gas inlet end face of the exhaust gas treatment body 120, and harmful substances in the exhaust gas are purified by the action of a catalyst supported on partition walls 122. The purified exhaust gas flows out from the outlet end face and is discharged to the outside.

[0072] In the exhaust gas purification device 100 shown in Fig. 3, the mat material 10 is the mat material of the present invention, and the first mat 21 is arranged on the exhaust gas treatment body 120 side. The second mat 22 is arranged on the metal casing 110 side.

[0073] The material of the metal 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.

[0074] The casing may be of a generally cylindrical shape, a clamshell shape, or a generally elliptical or polygonal shape in cross section.

[0075] The exhaust gas treatment body 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, mullite, etc. Among these, silicon carbide is preferred.

[0076] The exhaust gas treatment body preferably supports 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, such as alkali metals such as potassium or sodium, or alkaline earth metals such as barium, can also be used. 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.

[0077] Below, another embodiment of the mat material of the present invention will be described, in which the fixing member is different. FIG. 4 is a perspective view schematically illustrating an example of a mat material in which the fixing member is a sewing thread. The mat material 11 shown in FIG. 4 includes a sewing thread as the fixing member 31, rather than a strip. In the mat material 11, the first mat 21 and the second mat 22, which are multiple mats constituting the laminated mat 20, are fixed with the sewing thread. The fixing with the sewing thread may be performed at a single central location or at multiple locations spaced apart by a predetermined distance. FIG. 4 illustrates a configuration in which the laminated mats are fixed with the sewing thread at two locations. When the sewing thread is provided at multiple locations, the dimension of the fixing member in the length direction of the mat material is the width of the area sandwiched between the multiple sewing threads (the width indicated by the double arrow X in FIG. 4). Other than the configuration of the fixing member, the mat material can be similar to the mat material in which the fixing member is a strip-shaped member described above.

[0078] FIG. 5 is a perspective view schematically illustrating an example of a mat material in which the fixing member is an adhesive. The mat material 12 shown in FIG. 5 includes an adhesive as the fixing member 32 instead of a strip. In the mat material 12, the first mat 21 and the second mat 22, which are multiple mats that make up the laminated mat 20, are fixed with an adhesive that bonds the surfaces of the mats. Fixation with the adhesive is preferably performed in a region including the center in the longitudinal direction of the mat material. The dimension in the longitudinal direction of the fixing member fixed with the adhesive is the length indicated by the double arrow X in FIG. 5. Other than the configuration of the fixing member, the mat material can be similar to the mat material in which the fixing member is a strip, as described above.

[0079] The present specification discloses the following:

[0080] The present disclosure (1) is a mat material comprising a laminated mat in which a plurality of mats each containing inorganic fibers and having a rectangular shape in a planar view are stacked, and a fixing member for fixing the laminated mat, wherein the plurality of mats include a first mat and a second mat, and a sagging test is performed in which two mats of the same type are stacked and fixed, and the sagging amount of the first mat is greater than the sagging amount of the second mat, and the sagging amount of the mat material measured with the second mat underneath and the first mat on top is 60 mm or less.

[0081] The present disclosure (2) is the mat material according to the present disclosure (1), wherein the mat further contains an organic binder, and the content of the organic binder is 10.0 wt % or less relative to the weight of the laminated mat.

[0082] The present disclosure (3) is the mat material according to the present disclosure (2), in which the content of the organic binder in the second mat is greater than the content of the organic binder in the first mat.

[0083] The present disclosure (4) is the mat material according to the present disclosure (2) or (3), in which the content of the organic binder in the first mat is 0.1% by weight or more and less than 4.0% by weight, and the content of the organic binder in the second mat is 4.0% by weight or more and 12.0% by weight or less.

[0084] The present disclosure (5) is the mat material according to any one of the present disclosures (1) to (4), in which the length of the second mat in the longitudinal direction is longer than the length of the first mat in the longitudinal direction.

[0085] The present disclosure (6) is the mat material according to any one of the present disclosures (1) to (5), in which the first mat and the second mat are both needle mats.

[0086] The present disclosure (7) is the mat material according to any one of the present disclosures (1) to (5), in which the first mat and the second mat are both paper-made mats.

[0087] The present disclosure (8) is a mat material according to any one of the present disclosures (1) to (7), in which the fixing member is a strip, and the strip is wrapped around the laminated mat to fix the laminated mat.

[0088] The present disclosure (9) is a mat material according to any one of the present disclosures (1) to (7), in which the fixing member is a sewing thread, and the sewing thread is sewn to the laminated mat to fix the laminated mat.

[0089] The present disclosure (10) is a mat material according to any one of the present disclosures (1) to (7), in which the fixing member is an adhesive, and the adhesive bonds the plurality of mats together to fix the laminated mat.

[0090] The present disclosure (11) is an exhaust gas purification device comprising: an exhaust gas treatment body; a metal casing that houses the exhaust gas treatment body; and a mat material that is disposed between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body, wherein the mat material is the mat material described in any one of the present disclosures (1) to (10), and the first mat is disposed on the exhaust gas treatment body side.

[0091] The needling method was used to obtain a fiber weight per unit area of ​​1400 g / m ２ A sheet-like member made of inorganic fibers (mullite fibers) was prepared. This sheet-like member was punched to prepare a needled mat having a longitudinal length of 600 mm, a width of 100 mm, and a thickness of 8 mm. The needled mat had a shape with recesses and protrusions as shown in Figure 1.

[0092] An organic binder was applied to this needle mat so that the organic binder content was different, to obtain three types of mats: Mat A: organic binder content 10.0 wt %, Mat B: organic binder content 4.5 wt %, and Mat C: organic binder content 1.0 wt %.

[0093] For each of Mat A, Mat B, and Mat C, two mats of the same type were stacked and wrapped around a 300 mm wide nonwoven fabric to form a mat material, and the amount of sagging was measured. Regarding the measurement of the amount of sagging, the distance B between the gripping parts was set to 300 mm in the method for measuring the amount of sagging shown in Figure 2. The results of the measurement of the amount of sagging are shown in Table 1 as Test Nos. 1 to 3. The amounts of sagging measured in Test Nos. 1 to 3 are the amounts of sagging for Mat A, Mat B, and Mat C, respectively.

[0094] For different types of mats, the mat with the smallest sagging amount was placed on the bottom and the mat with the largest sagging amount was placed on top, and a nonwoven fabric with a width of 300 mm was wrapped around and fixed to form a mat material, and the sagging amount was measured. The measurement results of the sagging amount are shown in Table 1 as Test Nos. 4 and 5.

[0095]

[0096] Test Nos. 4 and 5 correspond to the mat material of the present invention, and are mat materials with small sagging amounts. Furthermore, the organic binder content is smaller than that of the mat material of Test No. 1, which is made by laminating two sheets of Mat A. Furthermore, the amount of sagging is smaller than that of the mat material of Test No. 2, which is made by laminating two sheets of Mat B, and the mat material of Test No. 3, which is made by laminating two sheets of Mat C.

[0097] 10, 11, 12 Mat material 20 Laminated mat 21 First mat 22 Second mat 23 First main surface of laminated mat 24 Second main surface of laminated mat 25 First long side surface of laminated mat 26 Second long side surface of laminated mat 27 First short side surface of laminated mat 28 Second short side surface of laminated mat 30 Fixing member (strip-shaped body) 31 Fixing member (sewing thread) 32 Fixing member (adhesive) 40 Jig 41a, 41b Grip portion 100 Exhaust gas purification device 110 Metal casing 120 Exhaust gas treatment body 121 Through hole 122 Partition wall

Claims

1. A mat material comprising a laminated mat in which multiple rectangular mats containing inorganic fibers are stacked together, and a fixing member for fixing the laminated mat, The aforementioned multiple mats include a first mat and a second mat, In a sag test conducted by stacking two identical mats, the amount of sag of the first mat was greater than the amount of sag of the second mat. A mat material characterized in that the amount of sagging of the mat material measured with the second mat below and the first mat above is 60 mm or less.

2. The mat material according to claim 1, wherein the mat further comprises an organic binder, and the content of the organic binder is 10.0% by weight or less relative to the weight of the laminated mat.

3. The mat material according to claim 2, wherein the content of the organic binder in the second mat is greater than the content of the organic binder in the first mat.

4. The organic binder content of the first mat is 0.1% by weight or more and less than 4.0% by weight. The mat material according to claim 2 or 3, wherein the content of the organic binder in the second mat is 4.0% by weight or more and 12.0% by weight or less.

5. The mat material according to any one of claims 1 to 3, wherein the length of the second mat in the longitudinal direction is longer than the length of the first mat in the longitudinal direction.

6. The mat material according to any one of claims 1 to 3, wherein both the first mat and the second mat are needle mats.

7. The mat material according to any one of claims 1 to 3, wherein both the first mat and the second mat are papermaking mats.

8. The mat material according to any one of claims 1 to 3, wherein the fixing member is a strip-shaped body, and the strip-shaped body is wrapped around the laminated mat to fix the laminated mat.

9. The mat material according to any one of claims 1 to 3, wherein the fixing member is a sewing thread, and the sewing thread is sewn to the laminated mat to fix the laminated mat.

10. The mat material according to any one of claims 1 to 3, wherein the fixing member is an adhesive, and the adhesive adheres the plurality of mats to each other to fix the laminated mat.

11. Exhaust gas treatment unit, A metal casing housing the exhaust gas treatment unit, An exhaust gas purification device comprising a mat material disposed between the exhaust gas treatment body and the metal casing and holding the exhaust gas treatment body, The mat material is the mat material described in any one of claims 1 to 3. An exhaust gas purification device characterized in that the first mat is arranged on the exhaust gas treatment body side.