Forming Pad and Method for Manufacturing the Same

Abstract

The present invention provides a forming mat with a sufficiently high surface pressure. The forming mat of the present invention is a forming mat composed of inorganic fibers, and is characterized in that the forming mat includes fiber bundles formed by intertwining 10 or more of the inorganic fibers in a twisted manner and the inorganic fibers not forming the fiber bundles. The average length of the fiber bundles is 5 to 15 mm, the average width of the fiber bundles is 0.2 to 1.0 mm, the fiber bundles include fiber bundles in a crimped state, and the drawing length of the fiber bundles in the crimped state measured by the following drawing length measurement method is 0.1 mm or more longer than the length of the fiber bundles in the crimped state. Drawing length measurement method: Place the fiber bundles in the crimped state on a flat surface. Observe the fiber bundles in the crimped state after standing from above, draw from one end of the fiber bundles in the crimped state to the other end along the fiber bundles in the crimped state, and take the distance of this drawing as the "drawing length of the fiber bundles in the crimped state".

Description

Technical Field

[0001] The present invention relates to a forming mat and a method for manufacturing the forming mat. Background Art

[0002] Exhaust gas discharged from internal combustion engines such as diesel engines contains particulate matter (hereinafter also referred to as PM). In recent years, the PM has become a problem for harming the environment and the human body. In addition, since the exhaust gas also contains harmful gas components such as CO, HC, and NOx, the influence of these harmful gas components on the environment and the human body is also a concern.

[0003] Therefore, as an exhaust gas purification device for capturing PM in exhaust gas or purifying harmful gas components, various exhaust gas purification devices have been proposed, which include: an exhaust gas treatment body made of porous ceramics such as silicon carbide or cordierite, a housing for accommodating the exhaust gas treatment body, and a sealing material (mat material) disposed between the exhaust gas treatment body and the housing. The sealing material (mat material) is mainly disposed for the following purposes: preventing the exhaust gas treatment body from being damaged by contact with the housing covering its outer periphery due to vibrations or impacts generated during vehicle driving or the like; preventing exhaust gas from leaking from between the exhaust gas treatment body and the housing; and the like.

[0004] In order to increase the force (surface pressure) of the mat material for holding the exhaust gas treatment body, Patent Document 1 discloses a mat material in which the surface pressure is increased by manufacturing an alumina fiber aggregate using a specific spinning aid.

[0005] In addition, Patent Document 2 discloses that a needle-punched sheet is temporarily produced, the needle-punched sheet is dry-opened to obtain opened fibers including massive aggregated fibers, and then a formed sheet is manufactured using the opened fibers including massive aggregated fibers. Further, Patent Document 2 describes that the surface pressure of the formed sheet is increased by including massive aggregated fibers.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: WO 2018 / 012423

[0009] Patent Document 2: JP 2008-82310 A Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] The mat material described in Patent Document 1 has problems that the alumina fibers are easily broken and the surface pressure is easily reduced.

[0012] Since the formed sheet material described in Patent Document 2 is obtained by dry fibrillation of a needle-punched sheet, the fibers after fibrillation become shorter, and the fibers constituting the bulked cohesive fibers also become shorter. Therefore, in the bulked cohesive fibers, the fibers do not sufficiently interlace with each other, and the bulked cohesive fibers do not form a twisted shape. In addition, the length of the bulked cohesive fibers also becomes shorter. Therefore, the elasticity of the bulked cohesive fibers does not sufficiently increase, and there is a problem that the surface pressure of the formed sheet material produced is difficult to become sufficiently high.

[0013] The present invention has been made in view of the above problems, and an object of the present invention is to provide a forming mat having a sufficiently high surface pressure.

[0014] Means for Solving the Problem

[0015] That is, the forming mat of the present invention is a forming mat composed of inorganic fibers, characterized in that the forming mat includes a fiber bundle formed by intertwining 10 or more of the inorganic fibers in a twisted manner and the inorganic fibers not constituting the fiber bundle, the average length of the fiber bundle is 5 to 15 mm, the average width of the fiber bundle is 0.2 to 1.0 mm, the fiber bundle includes a fiber bundle in a crimped state, and the drawing length of the fiber bundle in the crimped state measured by the following drawing length measurement method is 0.1 mm or more longer than the length of the fiber bundle in the crimped state.

[0016] Drawing Length Measurement Method:

[0017] Place the fiber bundle in the crimped state on a flat surface.

[0018] View the fiber bundle in the crimped state after standing from above, and draw from one end of the fiber bundle in the crimped state to the other end along the fiber bundle in the crimped state, and take the distance of this drawing as the "drawing length of the fiber bundle in the crimped state".

[0019] The forming mat of the present invention includes a fiber bundle having a specified size.

[0020] Such a fiber bundle is formed by intertwining 10 or more inorganic fibers in a twisted manner and having a specified length and width, and supports each other, so it does not deform due to pressing. Therefore, when pressing is applied to the forming mat, the fiber bundle functions as a core material and can relieve the pressing on the inorganic fibers not constituting the fiber bundle. Therefore, it is possible to prevent the inorganic fibers not constituting the fiber bundle from being broken due to pressing. As a result, the surface pressure of the forming mat of the present invention increases.

[0021] In the forming mat of the present invention, a fiber bundle in a state where the fiber bundle is crimped is included, and the drawing length of the fiber bundle in the crimped state measured by the above drawing length measurement method is 0.1 mm or more longer than the length of the fiber bundle in the crimped state.

[0022] The fiber bundle in a crimped state has elasticity, and the surface pressure of the forming mat containing such a fiber bundle becomes higher.

[0023] In the forming mat of the present invention, relative to 100 parts by weight of the inorganic fiber, it is preferable to contain 0.1 to 20 parts by weight of an organic binder and 0.1 to 10 parts by weight of an inorganic binder.

[0024] The organic binder and the inorganic binder bond the inorganic fibers to each other and maintain the shape of the forming mat.

[0025] When the contents of the organic binder and the inorganic binder are within the above ranges, the bonding between the inorganic fibers is appropriate, and the softness and shape maintainability of the forming mat can be taken into account.

[0026] In addition, the falling off and scattering of the inorganic fibers from the forming mat can be suppressed.

[0027] In the forming mat of the present invention, the glass transition temperature Tg of the above-mentioned organic binder is preferably 5°C or lower.

[0028] When the glass transition temperature Tg of the above-mentioned organic binder is 5°C or lower, the strength of the organic binder film formed by the organic binder can be improved, and a forming mat with a high film elongation rate and excellent flexibility can be produced.

[0029] In the forming mat of the present invention, the above-mentioned organic binder is preferably at least one selected from the group consisting of an acrylic resin, an acrylate latex, a rubber latex, carboxymethyl cellulose, and polyvinyl alcohol that function as a water-soluble organic polymer, a styrene resin that functions as a thermoplastic resin, and an epoxy resin that functions as a thermosetting resin.

[0030] In addition, in the forming mat of the present invention, the above-mentioned inorganic binder preferably contains at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice.

[0031] These organic binders and inorganic binders are suitable for bonding the inorganic fibers to each other and maintaining the shape of the forming mat.

[0032] In the forming mat of the present invention, the above-mentioned fiber bundle may also contain a fiber bundle in a straight state.

[0033] The fiber bundle in a straight state can be obtained by fibrillating a first inorganic fiber formed body from a needle-punched mat and a second inorganic fiber formed body from a forming mat in water.

[0034] The manufacturing method of the forming mat of the present invention is a manufacturing method including the following steps: a fiber opening step of opening an inorganic fiber molded body in water to produce a slurry containing the opened inorganic fibers; and a forming step of forming a forming mat by forming the above slurry. The manufacturing method of the forming mat is characterized in that, in the above fiber opening step, the opening is performed in such a way that the slurry contains fiber bundles formed by intertwining 10 or more of the above inorganic fibers in a twisted manner, having an average length of 5 to 15 mm and an average width of 0.2 to 1.0 mm, and the above inorganic fibers not constituting the above fiber bundles.

[0035] In the manufacturing method of the forming mat of the present invention, an inorganic fiber molded body is opened in water, and the obtained inorganic fibers are formed.

[0036] When opening an inorganic fiber molded body, sometimes the inorganic fibers are not completely opened, and fiber bundles formed by intertwining multiple fibers in a twisted manner are generated.

[0037] In the manufacturing method of the forming mat of the present invention, such fiber bundles are intentionally generated.

[0038] It should be noted that the number of inorganic fibers intertwined in a twisted manner in the fiber bundle, as well as the average length and average width of the fiber bundle, can be adjusted by adjusting the fiber opening conditions.

[0039] The surface pressure of the forming mat manufactured by this method increases.

[0040] In the manufacturing method of the forming mat of the present invention, the above inorganic fiber molded body preferably includes a first inorganic fiber molded body from a needle punched mat and / or a second inorganic fiber molded body from a forming mat.

[0041] Whether the inorganic fiber molded body is from a needle punched mat or from a forming mat, fiber bundles can be formed in the fiber opening step.

[0042] Effects of the Invention

[0043] According to the present invention, a forming mat with a sufficiently high surface pressure can be provided. Description of the Drawings

[0044] Figure 1A It is a perspective view schematically showing an example of the forming mat of the present invention.

[0045] Figure 1B is Figure 1A an enlarged view of the dashed part of.

[0046] Figure 2 It is a schematic view of an example of a fiber bundle in a curled state included in the forming mat of the present invention.

[0047] Figure 3It is a cross-sectional view schematically showing an example of the exhaust gas purification device of the present invention.

[0048] Figure 4A It is a photograph of a straight fiber bundle included in the forming mat of Example 1.

[0049] Figure 4B It is shown Figure 4A A photograph of the direction of the fiber bundle shown.

[0050] Figure 5A It is a photograph of a crimped fiber bundle included in the forming mat of Example 1.

[0051] Figure 5B It is shown Figure 5A A photograph of the direction of the fiber bundle shown. Detailed Description

[0052] Hereinafter, the forming mat of the present invention will be specifically described. However, the present invention is not limited to the following configuration, and can be appropriately changed and applied within the scope of not changing the gist of the present invention. It should be noted that a configuration obtained by combining two or more of the following preferred configurations of the present invention is also the present invention.

[0053] The forming mat of the present invention will be described with reference to the accompanying drawings.

[0054] Figure 1A It is a perspective view schematically showing an example of the forming mat of the present invention.

[0055] Figure 1B It is Figure 1A An enlarged view of the dashed part of.

[0056] As Figure 1A shown, the forming mat 10 is a forming mat made of inorganic fibers.

[0057] The forming mat 10 has a convex portion 11a provided at one end 11 and a concave portion 12a provided at the other end 12, and has a rectangular shape when viewed from above.

[0058] As will be described in detail later, the forming mat 10 is wound around the exhaust gas treatment body and disposed in the exhaust gas purification device.

[0059] The convex portion 11a and the concave portion 12a are shaped so as to fit exactly when the forming mat 10 is wound around the exhaust gas treatment body.

[0060] If such a convex portion 11a and a concave portion 12a are provided, the sealing performance is improved when the forming mat 10 is disposed in the exhaust gas purification device described later.

[0061] It should be noted that the forming mat of the present invention may not have a convex portion and a concave portion at the end.

[0062] As shown Figure 1B in FIG. 1, the forming mat 10 includes a fiber bundle 21 formed by intertwining more than 10 inorganic fibers 20 in a twisted manner and inorganic fibers 22 that do not form the fiber bundle 21.

[0063] The fiber bundle 21 includes a straight state ( Figure 1B in FIG. 1, the state indicated by the symbol "21a") and a crimped state ( Figure 1B in FIG. 1, the state indicated by the symbol "21b").

[0064] It should be noted that in the forming mat 10, the fiber bundle 21 includes the crimped fiber bundle 21b as an essential component.

[0065] It should be noted that in this specification, the "straight state" means that the direction of the fiber bundle ( Figure 1B in FIG. 1, the direction indicated by the arrow D1) is linear.

[0066] In addition, in this specification, the "crimped state" means a state in which the direction of the fiber bundle ( Figure 1B in FIG. 1, the direction indicated by the arrow D2) is bent at least once.

[0067] The average length of the fiber bundle 21 ( Figure 1B in FIG. 1, the average value of the length indicated by the symbol L) is 5 to 15 mm. In addition, the average length of the fiber bundle 21 is preferably 7 to 13 mm, and more preferably 8 to 10 mm.

[0068] The average width of the fiber bundle 21 ( Figure 1B in FIG. 1, the average value of the length indicated by the symbol W) is 0.2 to 1.0 mm. In addition, the average width of the fiber bundle 21 is preferably 0.2 to 0.8 mm.

[0069] It should be noted that as Figure 1B shown in FIG. 1, in the case of the straight fiber bundle 21a and the crimped fiber bundle 21b, the maximum width ( Figure 1B in FIG. 1, the lengths respectively indicated by the symbols Wa and Wb) is the width of the fiber bundle 21.

[0070] The fiber bundle 21 is formed by intertwining more than 10 inorganic fibers 20 in a twisted manner and supports each other, so it is not easily deformed by pressing. Therefore, when pressure is applied to the forming mat 10, the fiber bundle 21 functions as a core material and can relieve the pressure on the inorganic fibers 22 that do not form the fiber bundle 21. Therefore, it is possible to prevent the inorganic fibers 22 that do not form the fiber bundle 21 from being broken by pressing. As a result, the surface pressure of the forming mat 10 increases.

[0071] In particular, in the case of the fiber bundle 21b in a crimped state, this effect is appropriately exhibited, and the surface pressure of the forming mat 10 is further increased.

[0072] If the average length of the fiber bundle is less than 5 mm, the fiber bundle is too short, and it is difficult for the fiber bundle to serve as a core material to relieve the pressing force applied to the inorganic fibers that do not form the fiber bundle.

[0073] If the average length of the fiber bundle exceeds 15 mm, since the fiber bundle is too long, it is likely to bend when pressed on the side surface of the fiber bundle, and it is difficult to function as a core material.

[0074] If the average width of the fiber bundle is less than 0.2 mm, the strength of the fiber bundle is reduced, the fiber bundle is likely to bend, and it is difficult to function as a core material.

[0075] If the average width of the fiber bundle exceeds 1.0 mm, the strength of the fiber bundle becomes too high, and the softness of the entire forming mat is reduced.

[0076] It should be noted that in this specification, a "fiber bundle" refers to a part in the forming mat where inorganic fibers are concentrated and the density is higher than that of other parts.

[0077] In this specification, a "fiber bundle formed by intertwining inorganic fibers in a twisted manner" refers to the following fiber bundle.

[0078] The forming mat of the present invention is manufactured using inorganic fibers obtained by opening a needle-punched mat and a forming mat, which will be described in detail later.

[0079] When opening the needle-punched mat and the forming mat, sometimes the inorganic fibers are not completely opened, and fiber bundles formed by intertwining multiple fibers in a twisted manner are generated.

[0080] That is, when manufacturing the needle-punched mat, needles are used to intertwine the inorganic fibers with each other, so the inorganic fibers are strongly intertwined with each other in this part.

[0081] In addition, when manufacturing the forming mat, inorganic fibers are bonded to each other using an organic binder, so it is difficult for the inorganic fibers to separate from each other. When manufacturing the forming mat using the forming method, unevenness occurs in the collection of inorganic fibers, and a collection of inorganic fibers with a high density is formed.

[0082] The part where the inorganic fibers are intertwined with each other by needles in the needle-punched mat and the part where the inorganic fibers with a high density are collected in the forming mat are not easily opened and remain as fiber bundles intertwined in a twisted manner.

[0083] In this way, the fiber bundles remaining when opening the needle-punched mat and the forming mat are the "fiber bundles formed by intertwining inorganic fibers in a twisted manner" in this specification.

[0084] The forming mat of the present invention comprises a fiber bundle formed by intertwining inorganic fibers in a twisted manner.

[0085] The average length and average width of the fiber bundle refer to the values measured as follows.

[0086] Cut out a test piece of 150 cm 3 from the forming mat.

[0087] After that, the test piece is fired under the conditions of 600 °C for 1 hour to thermally decompose the binder component.

[0088] Next, place the test piece in a container and vibrate the container vertically, horizontally, and diagonally to untangle the inorganic fibers constituting the test piece.

[0089] Take out the fiber bundle from the untangled test piece and measure the length and width of the fiber bundle.

[0090] Repeat the same operation 3 times and calculate the average values of the length and width of the obtained fiber bundles.

[0091] It should be noted that when calculating the average length and average width of the fiber bundle, the fiber bundles composed of less than 10 inorganic fibers are excluded from the calculation.

[0092] It should be noted that when the mat material of the present invention contains a fiber bundle with an average length of 5 to 15 mm and an average width of 0.2 to 1.0 mm, it may contain fiber bundles with a length less than 5 mm, fiber bundles with a length exceeding 15 mm, fiber bundles with a width less than 0.2 mm, and fiber bundles with a width exceeding 1.0 mm.

[0093] As described above, the forming mat 10 includes the curled fiber bundle 21b as an essential component.

[0094] The curled fiber bundle 21b will be described in detail below with reference to the drawings.

[0095] Figure 2 is a schematic view of an example of the curled fiber bundle included in the forming mat of the present invention.

[0096] In Figure 2 the curled fiber bundle 21b shown, the drawing length L of the curled fiber bundle 21b measured by the following drawing length measurement method is preferably t longer than the length L of the curled fiber bundle 21b, more preferably 0.1 mm or more longer, and further preferably 0.2 to 0.6 mm longer.

[0097] (Drawing length measurement method)

[0098] Place the curled fiber bundle 21b on a flat surface.

[0099] Next, observing the fiber bundle 21b in the curled state after standing still from above, draw from one end P1 to the other end P2 of the fiber bundle 21b in the curled state along the fiber bundle 21b in the curled state, and take the distance L of this drawing t as the "drawing length of the fiber bundle in the curled state".

[0100] When the drawing length L of the fiber bundle 21b in the curled state t is longer than the length L of the fiber bundle 21b in the curled state, the elasticity of the fiber bundle 21b in the curled state increases, and the surface pressure of the forming mat 10 increases.

[0101] The forming mat 10 preferably contains a fiber bundle 21b in the following curled state: in the fiber bundle 21b in the curled state shown Figure 2 when measuring the "drawing length of the fiber bundle in the curled state", the fiber bundle 21b in the curled state can be drawn such that the line segment S connecting the end P1 and the end P2 crosses more than 2 times.

[0102] The degree of curling of such a fiber bundle 21b in the curled state is appropriate, the elasticity of the fiber bundle 21b in the curled state increases, and the surface pressure of the forming mat 10 increases.

[0103] In the forming mat 10, the drawing length L of the fiber bundle 21b in the curled state is preferably t the ratio of L to the length L of the fiber bundle 21b in the curled state is L t / L = 1.1 - 1.6.

[0104] In the forming mat 10, the value of the following formula (1) is preferably 0.1 or more, more preferably 0.2 - 0.6.

[0105] (L t - L) / Wb...(1)

[0106] In the forming mat 10, when the fiber bundle 21b in the curled state is placed still on a plane, the area of the fiber bundle 21b in the curled state observed from above is preferably 2.6 - 8.3 mm 2 .

[0107] In the forming mat 10, the proportion of the number of fiber bundles 21b in the curled state contained in the fiber bundle 21 is preferably 85% or less, more preferably 60% or less, further preferably 30% or less, and even more preferably 10% - 30%.

[0108] As the inorganic fiber 20 constituting the forming mat 10, it is preferably to contain at least 1 kind selected from alumina fiber, silica fiber, alumina - silica fiber, mullite fiber, glass fiber, and bio - soluble fiber.

[0109] If the forming mat 10 is composed of these inorganic fibers, the heat resistance is sufficient.

[0110] The inorganic fibers 20 constituting the forming mat 10 preferably have an average fiber diameter of 2 to 10 μm and an average fiber length of 0.01 to 5.0 mm.

[0111] The bulk density of the forming mat 10 is preferably 0.05 to 0.30 g / cm 3 .

[0112] If the bulk density of the forming mat 10 is less than 0.05 g / cm 3 , the mutual entanglement of the inorganic fibers is weak, and the inorganic fibers are easily peeled off. Therefore, it is difficult to maintain the shape of the forming mat as a specified shape.

[0113] If the bulk density of the forming mat 10 exceeds 0.30 g / cm 3 , the forming mat becomes hard, the winding property decreases, and mat breakage easily occurs.

[0114] In the forming mat 10, preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight of an organic binder is contained with respect to 100 parts by weight of the inorganic fibers 20.

[0115] In addition, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 3.0 parts by weight of an inorganic binder is contained with respect to 100 parts by weight of the inorganic fibers 20.

[0116] The organic binder and the inorganic binder bond the inorganic fibers to each other and maintain the shape of the forming mat.

[0117] If the contents of the organic binder and the inorganic binder are within the above ranges, the bonding between the inorganic fibers is appropriate, and the softness and shape maintainability of the forming mat can be taken into account.

[0118] In addition, the falling off and scattering of the inorganic fibers from the forming mat can be suppressed.

[0119] In the forming mat 10, the glass transition temperature Tg of the organic binder is preferably 5°C or lower, more preferably -35 to 5°C.

[0120] If the glass transition temperature Tg of the organic binder is 5°C or lower, the strength of the organic binder film formed by the organic binder can be improved, and a forming mat with a high film elongation rate and excellent flexibility can be produced.

[0121] In addition, when the forming mat 10 is wound around an exhaust gas treatment body or the like, mat breakage hardly occurs. In addition, since the organic binder film does not become too hard, when the inorganic fibers are broken, the effect of connecting the inorganic fibers to each other can be exerted, and the scattering of the inorganic fibers can be suppressed.

[0122] When the glass transition temperature Tg of the organic binder exceeds 5°C, the flexibility of the formed mat sometimes decreases, and the elongation at break decreases.

[0123] In the formed mat of the present invention, the above-mentioned organic binder may be a water-soluble organic polymer, a thermoplastic resin, or a thermosetting resin.

[0124] Examples of the water-soluble organic polymer include acrylic resins, acrylate-based latexes, rubber-based latexes, carboxymethyl cellulose, and polyvinyl alcohol. Examples of the thermoplastic resin include styrene resins. Examples of the thermosetting resin that functions as a thermosetting resin include epoxy resins.

[0125] In the formed mat 10, the inorganic binder preferably contains at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice.

[0126] These organic binders and inorganic binders are suitable for bonding inorganic fibers to each other and maintaining the shape of the formed mat.

[0127] Next, the manufacturing method of the formed mat of the present invention will be described.

[0128] The manufacturing method of the formed mat of the present invention includes (1) a fiber opening step and (2) a forming step.

[0129] It should be noted that in the following description, the case where both the first inorganic fiber formed body from the needle-punched mat and the second inorganic fiber formed body from the formed mat are used as the inorganic fiber formed body will be described, but in the manufacturing method of the formed mat of the present invention, any inorganic fiber formed body can be used.

[0130] Each step will be described in detail below.

[0131] (1) Fiber opening step

[0132] In this step, the first inorganic fiber formed body from the needle-punched mat and the second inorganic fiber formed body from the formed mat are opened in water to produce a slurry containing the opened inorganic fibers.

[0133] In this step, the fiber opening is performed in such a manner that the slurry contains fiber bundles formed by intertwining 10 or more of the above-mentioned inorganic fibers in a twisted manner, having an average length of 5 to 15 mm and an average width of 0.2 to 1.0 mm, and the above-mentioned inorganic fibers that do not form fiber bundles.

[0134] It should be noted that in this step, dry fiber opening is preferably not performed.

[0135] When opening the needle-punched mat and the formed mat, sometimes the inorganic fibers are not completely opened, and fiber bundles formed by intertwining multiple fibers in a twisted manner are generated.

[0136] More specifically, it is described as follows.

[0137] When manufacturing a needled mat, inorganic fibers are intertwined with each other by needles, so that the inorganic fibers are strongly intertwined with each other in this part.

[0138] In addition, when manufacturing a wet-laid mat, inorganic fibers are bonded to each other by an organic binder, so that the inorganic fibers are difficult to separate from each other. When manufacturing a wet-laid mat by the wet-laid method, unevenness occurs in the aggregation of inorganic fibers with each other, and an aggregation of inorganic fibers with a high density is formed.

[0139] In the needled mat, the part where inorganic fibers are intertwined with each other by needles and the part where the aggregation of inorganic fibers with a high density in the wet-laid mat are not easily fibrillated and remain as fiber bundles intertwined in a twisted manner.

[0140] In the method for manufacturing a wet-laid mat of the present invention, such fiber bundles are intentionally generated.

[0141] It should be noted that the number of inorganic fibers intertwined in a twisted manner in the fiber bundle, the average length of the fiber bundle, and the average width of the fiber bundle can be adjusted by adjusting the fibrillation conditions.

[0142] The fibrillation conditions are not particularly limited. For example, when fibrillating in water using a stirrer, by adjusting the rotation speed and time of the stirrer, the number of inorganic fibers intertwined in a twisted manner in the fiber bundle, the average length of the fiber bundle, and the average width of the fiber bundle can be adjusted.

[0143] It should be noted that when performing dry fibrillation in this process, the inorganic fibers are easily broken and the length of the fiber bundle becomes shorter. As a result, the length of the obtained fiber bundle becomes shorter, and a fiber bundle having a desired shape cannot be obtained.

[0144] Therefore, in this process, it is preferable not to perform dry fibrillation.

[0145] In addition, the fiber bundles generated in this process can be from the first inorganic fiber molded body or from the second inorganic fiber molded body.

[0146] Regardless of whether the inorganic fiber molded body is from the first inorganic fiber molded body (from a needled mat) or from the second inorganic fiber molded body (from a wet-laid mat), fiber bundles can be formed in the fibrillation process.

[0147] As an example of fibrillation, the following methods can be cited, for example.

[0148] First, the first inorganic fiber molded body and the second inorganic fiber molded body are fired at 700 to 1000 °C for 1.0 to 8.0 hours. The preferred firing temperature is 800 to 950 °C.

[0149] Thereby, the organic binder contained in the first inorganic fiber formed body and the second inorganic fiber formed body can be thermally decomposed, and the first inorganic fiber formed body and the second inorganic fiber formed body can be easily fibrillated.

[0150] Next, the fired first inorganic fiber formed body and the second inorganic fiber formed body are left standing until room temperature, and then, the first inorganic fiber formed body and the second inorganic fiber formed body are untied by hand.

[0151] Next, the first inorganic fiber formed body and the second inorganic fiber formed body are added to water in an amount of 50 to 400 times by weight, and stirred to fibrillate, thereby producing a slurry containing inorganic fibers. This weight ratio is preferably 100 to 200 times by weight.

[0152] In addition, the stirring conditions are preferably set appropriately. For example, when producing 10 L of slurry, it is preferable to use (product name: SMT-101, manufacturer: AS ONE) as a stirrer, and stir under the conditions of a rotation speed of 500 to 1000 rpm and a stirring time of 200 to 900 seconds. The rotation speed is preferably 650 to 850 rpm and the stirring time is preferably 500 to 700 seconds, and more preferably the rotation speed is 700 to 800 rpm and the stirring time is 500 to 650 seconds.

[0153] It should be noted that at this time, when drying the slurry, fibrillation is performed in such a manner that a fiber bundle having an average length of 5 to 15 mm and an average width of 0.2 to 1.0 mm formed by intertwining 10 or more of the above-mentioned inorganic fibers in a twisted manner is formed.

[0154] Next, an organic binder and an inorganic binder are added to the slurry.

[0155] The organic binder is preferably added in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the inorganic fibers in the produced wet laid mat, and more preferably added in an amount of 0.5 to 15.0 parts by weight.

[0156] The inorganic binder is preferably added in an amount of 0.1 to 15.0 parts by weight with respect to 100 parts by weight of the inorganic fibers in the produced wet laid mat, and more preferably added in an amount of 0.5 to 10 parts by weight.

[0157] The preferred types of the organic binder and the inorganic binder have been described, and thus the description thereof is omitted here.

[0158] (2) Wet laying process

[0159] Next, a slurry is poured into a former having a filter net formed on the bottom surface, and the solvent in the slurry is desolvated to obtain an inorganic fiber aggregate. Then, the inorganic fiber aggregate is dehydrated and dried to obtain the wet laid mat of the present invention.

[0160] It should be noted that, in the wet laying process, the inorganic fiber aggregate can be dried by heating and pressing. When heating and pressing, heat treatment can be performed by passing hot air through the inorganic fiber aggregate for drying, or it can be in a wet state without heat treatment.

[0161] In the case of performing heat treatment, in order to prevent the organic binder from deteriorating due to heat, the heating temperature and the hot air temperature are preferably 150 to 210°C.

[0162] In the range of 150 to 210°C, deterioration of the organic binder can be suppressed, and at the same time, moisture can be dispersed from the inorganic fiber aggregate. When the heating temperature and the hot air temperature are less than 150°C, the temperature does not reach the central part of the inorganic fiber aggregate, and the drying time becomes long. In addition, if it exceeds 210°C, the organic binder deteriorates, and the binding force between fibers decreases, so that it becomes difficult to control the thickness of the inorganic fiber aggregate.

[0163] In the manufacturing method of the wet laid mat of the present invention, it is preferable to perform batch wet laying or continuous wet laying in the wet laying process.

[0164] By performing batch wet laying or continuous wet laying, the wet laid mat of the present invention can be easily obtained.

[0165] It should be noted that the wet laid mat of one embodiment of the present invention is produced through a fiber opening process and a wet laying process. The fiber opening process is a process of opening an inorganic fiber formed body in water to produce a slurry containing the opened inorganic fibers, and the wet laying process is a process of wet laying the slurry to form a wet laid mat. Among them, in the fiber opening process, the slurry is opened so that the slurry contains fiber bundles formed by the intertwining of 10 or more of the above-mentioned inorganic fibers in a twisted manner, with an average length of 5 to 15 mm and an average width of 0.2 to 1.0 mm, and the above-mentioned inorganic fibers that do not form the fiber bundles.

[0166] It should be noted that, in the above-mentioned fiber opening process, preferably, the slurry contains fiber bundles in a crimped state, and the traced length of the fiber bundles in the crimped state measured by the above-mentioned traced length measurement method is 0.1 mm or more longer than the length of the fiber bundles in the crimped state.

[0167] Next, the usage method of the wet laid mat of the present invention will be described.

[0168] Figure 3 It is a cross-sectional view schematically showing an example of the exhaust gas purification device of the present invention.

[0169] like Figure 3 As shown, the exhaust gas purification device 100 includes a metal casing 30, an exhaust gas treatment body 40 accommodated in the metal casing 30, and a papermaking mat 10 disposed between the exhaust gas treatment body 40 and the metal casing 30. The papermaking mat 10 is the papermaking mat of the present invention.

[0170] The exhaust gas treatment body 40 is a columnar body having a plurality of cells 41 arranged in parallel along the length direction with a groove wall 42 therebetween. It should be noted that, at the end of the metal shell 30, an inlet pipe for introducing exhaust gas discharged from the internal combustion engine and an exhaust pipe for discharging the exhaust gas after passing through the exhaust gas purification device to the outside are connected as needed.

[0171] exist Figure 3 In the exhaust gas purification device 100 shown, an exhaust gas filter (honeycomb filter) in which any end of each groove is sealed with a sealing material 43 is used as the exhaust gas treatment body 40, but a catalyst carrier in which any end surface is not sealed with a sealing material may also be used.

[0172] like Figure 3 As shown, the exhaust gas ( Figure 3 In the figure, G represents exhaust gas and arrows represent the flow of exhaust gas) flows into a groove 41 opened at the exhaust gas inlet side end surface 40a of the exhaust gas treatment body (honeycomb filter) 40, and passes through the groove wall 42 separating the groove 41. At this time, PM in the exhaust gas is captured by the groove wall 42, and the exhaust gas is purified. The purified exhaust gas flows out from the other grooves 41 opened at the exhaust gas outlet side end surface 40b and is discharged to the outside.

[0173] As described above, the surface pressure of the papermaking mat 10 is high. Therefore, in the exhaust gas purifying device 100, even if the exhaust gas treating body 40 is subjected to high pressure from the exhaust gas, it is possible to prevent the exhaust gas treating body 40 from falling off from the metal casing 30.

[0174] The exhaust gas treating body 40 may be made of non-oxidizing porous ceramics such as silicon carbide and silicon nitride, or may be made of oxidizing porous ceramics such as sialon, alumina, cordierite, and mullite. Among them, silicon carbide is preferred.

[0175] When the exhaust gas treating body 40 is a silicon carbide porous ceramic, the porosity of the porous ceramic is not particularly limited, but is preferably 35 to 60%.

[0176] If the porosity is less than 35%, the exhaust gas treatment body may be immediately clogged. On the other hand, if the porosity exceeds 60%, the strength of the exhaust gas treatment body decreases and the exhaust gas treatment body may be easily broken.

[0177] In addition, the average pore diameter of the porous ceramic is preferably 5 to 30 μm.

[0178] If the average pore diameter is less than 5 μm, PM may sometimes cause clogging.

[0179] If the average pore diameter exceeds 30 μm, PM may sometimes pass through the pores, making it impossible to capture PM and function as a filter.

[0180] It should be noted that the above-mentioned porosity and pore diameter can be measured by known existing methods such as using a scanning electron microscope (SEM).

[0181] The groove density in the cross-section of the exhaust gas treatment body 40 is not particularly limited. The preferred lower limit is 31.0 pieces / cm 2 (200 pieces / inch 2 ), and the preferred upper limit is 93.0 pieces / cm 2 (600 pieces / inch 2 ). Additionally, the more preferred lower limit is 38.8 pieces / cm 2 (250 pieces / inch 2 ), and the more preferred upper limit is 77.5 pieces / cm 2 (500 pieces / inch 2 ).

[0182] The exhaust gas treatment body 40 can also be loaded with a catalyst for purifying exhaust gas. As the loaded catalyst, noble metals such as platinum, palladium, and rhodium are preferred. Among them, platinum is more preferred. Additionally, as other catalysts, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can also be used. These catalysts can be used alone or in combination of two or more.

[0183] If these catalysts are loaded, it is easy to burn and remove PM and also purify toxic exhaust gas.

[0184] (Metal housing)

[0185] The metal housing 30 is approximately cylindrical.

[0186] The inner diameter of the metal housing 30 (the inner diameter of the part that houses the exhaust gas treatment body) is preferably slightly shorter than the diameter of the exhaust gas treatment body 40 around which the paper-making mat 10 is wound.

[0187] The metal housing 30 is not particularly limited and is preferably made of stainless steel.

[0188] Examples

[0189] Hereinafter, examples that more specifically disclose the present invention are shown. It should be noted that the present invention is not limited to these examples.

[0190] (Example 1)

[0191] Prepare a first inorganic fiber molded body from a needle-punched mat, which is composed of alumina-silica fibers with Al2O3:SiO2 = 72:28 (weight ratio), and has a bulk density of 0.17 g / cm 3 , and the density of the stitches is 21 per cm 2 .

[0192] In addition, prepare a second inorganic fiber molded body from a wet-laid mat, which is composed of alumina-silica fibers with Al2O3:SiO2 = 72:28 (weight ratio), and has a bulk density of 0.12 g / cm 3 .

[0193] Next, sinter the first inorganic fiber molded body and the second inorganic fiber molded body at 800 °C for 1 hour to thermally decompose the organic binder contained in the first inorganic fiber molded body and the second inorganic fiber molded body.

[0194] Next, leave the sintered first inorganic fiber molded body and second inorganic fiber molded body to stand at room temperature, and then, untie the first inorganic fiber molded body and the second inorganic fiber molded body by hand.

[0195] Next, take out 5.0 g of the first inorganic fiber molded body and 5.0 g of the second inorganic fiber molded body, and add them to 0.4 L of water. Then, using a stirrer (product name: SMT-101, manufacturer: AS ONE), stir under the conditions of a rotation speed of 1000 rpm and a stirring time of 10 minutes to perform fibrillation, thereby producing a slurry of inorganic fibers.

[0196] It should be noted that, in order to confirm whether fiber bundles are formed in the slurry, a part of the slurry is taken out and dried, and as a result, it is confirmed that fiber bundles are formed in the form of being twisted by 10 or more inorganic fibers.

[0197] Next, an organic binder is added to the slurry in an amount of 0.5 to 10 parts by weight relative to 100 parts by weight of the inorganic fibers.

[0198] In addition, an inorganic binder is added to the slurry in an amount of 0.5 to 3.0 parts by weight relative to 100 parts by weight of the inorganic fibers.

[0199] Next, the slurry is poured into a former having a filter mesh formed on the bottom surface, and the solvent in the slurry is subjected to a desolvation treatment, thereby obtaining an inorganic fiber aggregate. Then, the inorganic fiber aggregate is dehydrated and dried under the conditions of 150 to 210 °C for 5 minutes to 1 hour, thereby manufacturing the wet-laid mat of Example 1.

[0200] (Observation of fiber bundles 1)

[0201] Cut out 150 cm from the wet-laid mat of Example 13 Test piece

[0202] Then, the test piece was fired under the conditions of 600 °C for 1 hour to thermally decompose the binder component.

[0203] Next, the test piece was placed in a container and the container was vibrated up, down, left, and right, thereby unraveling the inorganic fibers constituting the test piece.

[0204] Fiber bundles were randomly taken out from the unraveled test piece, and the length and width of the fiber bundles were measured.

[0205] The same operation was repeated 3 times, and the average values of the length and width of the fiber bundles were calculated.

[0206] As a result, the average length of the fiber bundles was 8 mm, and the average width of the fiber bundles was 0.393 mm.

[0207] In addition, photographs of the fiber bundles contained in the forming mat of Example 1 are shown in Figure 4A and Figure 5A . In addition, the directions of the respective fiber bundles are shown in Figure 4B and Figure 5B .

[0208] Figure 4A is a photograph of a straight fiber bundle contained in the forming mat of Example 1.

[0209] Figure 4B is a photograph showing Figure 4A the direction of the fiber bundle shown.

[0210] Figure 5A is a photograph of a crimped fiber bundle contained in the forming mat of Example 1.

[0211] Figure 5B is a photograph showing Figure 5A the direction of the fiber bundle shown.

[0212] Figure 4B The fiber bundle shown is in a straight state, and the direction of the fiber bundle is along arrow D1.

[0213] Figure 5B The fiber bundle shown is in a crimped state, and the direction of the fiber bundle is along arrow D2.

[0214] (Example 2) and (Comparative Example 1) and (Comparative Example 2))

[0215] When making a slurry of inorganic fibers by fibrillating each inorganic fiber preform with a stirrer, the stirring time was changed to adjust the average length of the fiber bundles contained in the made hand sheet to the lengths shown in Table 1. Other than that, hand sheets of Example 2, Comparative Example 1, and Comparative Example 2 were manufactured in the same manner as in Example 1.

[0216] [Table 1]

[0217] Average length of fiber bundle (mm) Surface pressure (kPa) Comparative Example 1 4 88.6 Example 1 8 97.0 Example 2 10 104.8 Comparative Example 2 18 92.2 Comparative Example 3 20 87.4

[0218] (Comparative Example 3)

[0219] For the aqueous solution of basic aluminum chloride, silica sol was mixed in such a way that the composition ratio in the fired inorganic fibers was Al2O3:SiO2 = 72:28 (weight ratio). Furthermore, an organic polymer (polyvinyl alcohol) was added in an appropriate amount to prepare a mixed solution.

[0220] The obtained mixed solution was concentrated as a spinning mixture, and the spinning mixture was spun by the spray spinning method (spinning atmosphere temperature: 120 °C) to produce an alumina fiber precursor.

[0221] Next, the obtained inorganic fiber precursor was compressed to produce a continuous sheet. After that, the sheet was placed in a heating furnace and subjected to a firing treatment to manufacture an inorganic fiber aggregate.

[0222] Next, using a stirrer (product name: SMT-101, manufacturer: AS ONE Corporation), stirring was carried out under the conditions of a rotation speed of 1000 rpm and a stirring time of 10 minutes to fibrillate the inorganic fiber aggregate.

[0223] It should be noted that in order to confirm whether fiber bundles were formed in the slurry, a part of the slurry was taken out and dried, and as a result, it was confirmed that fiber bundles were formed, but the fiber bundles were not twisted.

[0224] Next, the slurry was poured into a former having a filter net formed on the bottom surface, and the solvent in the slurry was subjected to a desolvation treatment to obtain an inorganic fiber aggregate. After that, the inorganic fiber aggregate was dehydrated and dried under the conditions of 150 to 210 °C for 5 minutes to 1 hour to manufacture the hand sheet of Comparative Example 3.

[0225] The hand sheet of Comparative Example 3 was observed by the same method as in the above-mentioned "(Observation of fiber bundles 1)", and as a result, it contained untwisted fiber bundles. The average length of the fiber bundles was 20 mm, and the average width of the fiber bundles was 0.37 mm.

[0226] (Measurement of surface pressure)

[0227] The forming pads of Examples 1 and 2 and Comparative Examples 1 to 3 were placed on a testing machine (product name: SMT-101, manufacturer: ASONE Corporation) and compressed at a speed of 25.4 mm / minute until the void bulk density (GBD) reached 0.40 mm 3 / g. They were kept in the state with a void bulk density (GBD) of 0.40 mm 3 / g for 10 minutes.

[0228] After that, the surface pressure of each forming pad was measured. The results are shown in Table 1.

[0229] As shown in Table 1, it was clarified that the surface pressure of the forming pads of each example was high.

[0230] (Comparative Example 4)

[0231] In an aqueous solution of basic aluminum chloride with an aluminum content of 70 g / l and Al / Cl = 1.8 (atomic ratio), silica sol was mixed in such a way that the composition of the alumina-based fiber was Al2O3:SiO2 = 72:28 to form a precursor of the alumina-based fiber. Then, an organic polymer such as polyvinyl alcohol was added to the precursor of the alumina-based fiber. Furthermore, the liquid was concentrated to prepare a spinning solution, and the spinning solution was used for spinning by the blow method. Then, the material formed by folding the precursor of the alumina-based fiber was laminated to produce a laminated sheet of the alumina-based fiber. Then, the laminated sheet was subjected to needling treatment. Two sets of needle plates each provided with 50 needles / 100 cm 2 were arranged on each of the front and back sides of the laminated sheet, and needling treatment was performed from both sides of the laminated sheet. Thus, a laminated sheet with an interlacing point density of about 1 per cm 2 was obtained.

[0232] Then, the obtained laminated sheet was continuously fired from room temperature to a maximum temperature of 1250 °C to obtain a needled sheet with a thickness of about 7 mm.

[0233] Next, after roughly cutting the needled sheet into a size of 200 mm × 200 mm or less, it was put into a screen type crusher (Feather mill) device (FM-1, manufactured by Hosokawa Micron Corporation) for dry fiber opening to obtain cotton-like opened fibers with a diameter of about 150 mm.

[0234] Next, to prepare the raw material slurry, 1200 g of the obtained opened fibers and 120000 g of water were put into a blender and stirred for 1 minute. Then, 60 g of an organic binder (latex) was added to the solution and further stirred for 1 minute. Then, 12 g of an inorganic binder (aluminum oxide sol) was added to the solution and further stirred for 1 minute. Finally, 6 g of a coagulant (Percol292) was added and stirred for 1 minute to obtain the raw material slurry.

[0235] Next, in order to form the molded body, the raw material slurry thus prepared was transferred to a mold with a vertical dimension of 930 mm, a horizontal dimension of 515 mm, and a depth of 400 mm, having a filter metal mesh (30 mesh) at the bottom, and dehydration treatment was performed. The dehydration treatment was carried out by forcibly sucking the moisture of the raw material slurry from the bottom side of the mold through the filter metal mesh using a suction pump.

[0236] Next, the molded body was taken out of the molding machine and compression-dried at 120 °C and 70 kPa for 30 minutes. Through such a process, a hand sheet of Comparative Example 4 with a thickness of 13 mm and a density of 0.19 g / cm 3 was manufactured.

[0237] The hand sheet of Comparative Example 4 was observed in the same manner as in the above-mentioned "(Observation of fiber bundles 1)", and the result was that it contained un-twisted fiber bundles. The average length of the fiber bundles was 3 mm, and the average width of the fiber bundles was 1.43 mm.

[0238] (Observation of fiber bundles 2)

[0239] Test pieces of 150 cm 3 were cut out from the hand sheet of Example 1 and the hand sheet of Comparative Example 4, respectively.

[0240] Then, the test pieces were fired under the conditions of 600 °C for 1 hour to thermally decompose the binder component.

[0241] Next, the test pieces were placed in a container, and the container was vibrated up, down, left, and right to untangle the inorganic fibers constituting the test pieces.

[0242] 13 fiber bundles were randomly taken out from the test piece of the hand sheet of Example 1, and 4 fiber bundles were randomly taken out from the test piece of the hand sheet of Comparative Example 4.

[0243] Among the fiber bundles taken out from the test piece of the hand sheet of Example 1, 9 fiber bundles were in a crimped state and 4 fiber bundles were in a straight state.

[0244] The average value of the length L of these crimped fiber bundles was 6.78 mm. In addition, the average value of the area was 4.95 mm 2 .

[0245] The average value of the length L of these straight fiber bundles was 7.97 mm. In addition, the average value of the area was 2.83 mm 2 .

[0246] All the fiber bundles taken out from the test piece of the hand sheet of Comparative Example 4 were in a straight state.

[0247] The average value of the length L of these fiber bundles in the straight state is 3.23 mm. Additionally, the average value of the area is 3.41 mm 2 .

[0248] For each fiber bundle in the crimped state of Example 1, place it statically on a plane and observe the fiber bundle from above to measure the drawn length L of the fiber bundle t , and calculate its average value.

[0249] Then, calculate the difference (L t -L) and the ratio (L t / L) between the length L of the fiber bundle and the drawn length L of the fiber bundle. The results are shown in Table 2. t / L). The results are shown in Table 2.

[0250] [Table 2]

[0251] Shape of fiber bundle L (mm) <![CDATA[L t (mm)]]> <![CDATA[L t -L(mm)]]> <![CDATA[L t / L]]> Example 1 Crimp state 6.78 7.89 1.11 1.16

[0252] Symbol Explanation

[0253] 10 Forming Pad

[0254] 11 One End

[0255] 11a Convex Portion

[0256] 12 The Other End

[0257] 12a Concave Portion

[0258] 20 Inorganic Fiber

[0259] 21 Fiber Bundle

[0260] 21a Fiber Bundle in Straight State

[0261] 21b Fiber Bundle in Crimped State

[0262] 22 Inorganic Fiber Not Constituting Fiber Bundle

[0263] 30 Metal Shell

[0264] 40 Exhaust Gas Treatment Body

[0265] 40a Exhaust Gas Inflow Side End

[0266] 40b Exhaust Gas Discharge Side End

[0267] 41 Groove

[0268] 42 Groove Wall

[0269] 43 Sealing Material

[0270] 100 Exhaust Gas Purification Device

Claims

1. A papermaking mat, which is a papermaking mat composed of inorganic fibers, used in an exhaust gas purification device, characterized in that: The paper-made mat includes a fiber bundle formed by entwining 10 or more of the inorganic fibers in a twisted manner and the inorganic fibers that do not constitute the fiber bundle. The average length of the fiber bundle is 5 mm to 15 mm. The average width of the fiber bundle is 0.2 mm to 1.0 mm, The fiber bundle includes a fiber bundle in a crimped state, and a drawn length of the fiber bundle in the crimped state measured by the following drawn length measuring method is longer than the length of the fiber bundle in the crimped state by 0.1 mm or more, The ratio of the number of the crimped fiber bundles contained in the fiber bundle is 10% to 85%, Method for measuring drawing length: The fiber bundle in a curled state is placed on a flat surface; Observe the curled fiber bundle after standing still from above, trace along the curled fiber bundle from one end to the other end of the curled fiber bundle, and define the traced distance as "the traced length of the curled fiber bundle".

2. The copying mat according to claim 1, wherein: The organic binder is contained in an amount of 0.1 to 20 parts by weight and the inorganic binder is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the inorganic fibers.

3. The copying mat according to claim 2, wherein: The glass transition temperature Tg of the organic binder is 5° C. or less.

4. The copying mat according to claim 2 or 3, wherein: The organic binder is at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethyl cellulose and polyvinyl alcohol functioning as water-soluble organic polymers, styrene resin functioning as thermoplastic resins, and epoxy resin functioning as thermosetting resins.

5. The copying mat according to claim 2 or 3, wherein: The inorganic binder includes at least one of alumina, silicon dioxide, silicon carbide, zirconium oxide, boron nitride, diamond and pumice.

6. The copying mat according to claim 1 or 2, wherein: The fiber bundle includes a straight fiber bundle.

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