Method for producing inorganic fiber mat, and inorganic fiber mat

Abstract

Provided are: a method for producing an inorganic fiber mat which is easier to mold even when an inorganic fiber material is an inorganic fiber molded body; and an inorganic fiber mat. A method for producing an inorganic fiber mat, which is characterized by using a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a paper-made mat, and which comprises: a splitting step for splitting the first inorganic fiber molded body and the second inorganic fiber molded body to obtain inorganic fibers; and a papermaking and molding step for performing papermaking and molding of the inorganic fiber mat using the slurry containing the split inorganic fibers.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of December 8, 2023, application number 202311683836.1, and invention name “Method for manufacturing inorganic fiber mat and inorganic fiber mat”. Technical Field

[0002] The invention relates to a method for manufacturing an inorganic fiber mat and the inorganic fiber mat. Background Art

[0003] As an exhaust gas purification device for capturing particulate matter (PM) in exhaust gas or purifying harmful gas components, various schemes of exhaust gas purification devices consisting of an exhaust gas treatment body (which is composed of porous ceramics such as silicon carbide and cordierite), a shell for accommodating the exhaust gas treatment body, and an inorganic fiber mat (holding sealing material) arranged between the exhaust gas treatment body and the shell. The mat is mainly arranged to prevent the exhaust gas treatment body from contacting with the shell covering its outer periphery and being damaged due to vibration or impact generated by the driving of the car, etc., and to prevent the exhaust gas from leaking from between the exhaust gas treatment body and the shell.

[0004] In addition, such inorganic fiber mats are produced by punching or cutting out a large sheet of inorganic fiber mats into a predetermined shape, and the edges of the sheet are generated as scraps. In recent years, it has been required to reduce industrial waste and to reuse scraps generated during manufacturing without discarding them.

[0005] Patent Document 1 discloses a method for producing a thermal insulation molded body, characterized in that waste inorganic fibrous thermal insulation materials are defibrated, new inorganic fibers are mixed with the defibrated thermal insulation materials to form a cotton-like body, and a binder is mixed therewith for molding.

[0006] In addition, Patent Document 2 discloses a method for manufacturing a fiber molding, which is characterized in that ceramic fibers are mixed with ionic organic binder powder, and water containing a heat-resistant inorganic binder is further added to the mixture so that the whole is roughly wet, and then the wet mixture is filled in a mold and pressurized for molding. In this manufacturing method, a part of the above-mentioned ceramic fibers is replaced with finely crushed fragments of used fiber products.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 9-210289

[0010] Patent Document 2: Japanese Patent Application Publication No. 2001-335379 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, the methods disclosed in Patent Documents 1 and 2 have a problem in that the moldability of the product is insufficient.

[0013] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for producing an inorganic fiber mat that is easier to mold even when an inorganic fiber molded body is used as an inorganic fiber material.

[0014] Means for solving problems

[0015] The present inventors have conducted intensive studies and have found that the moldability of a newly produced inorganic fiber mat can be improved by using inorganic fibers derived from a needle punched mat and inorganic fibers derived from a papermaking mat as inorganic fibers.

[0016] That is, the method for manufacturing an inorganic fiber mat of the present invention (hereinafter also referred to as the manufacturing method of the present invention) is characterized in that it uses a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a papermaking mat, and has the following steps: a fiber opening step, in which the above-mentioned first inorganic fiber molded body and the above-mentioned second inorganic fiber molded body are fiberized to obtain inorganic fibers; and a papermaking molding step, in which a slurry containing the above-mentioned inorganic fibers that have been fiberized is used to papermake the inorganic fiber mat.

[0017] Since the method for producing an inorganic fiber mat of the present invention has the above-mentioned structure, the inorganic fiber mat has excellent formability. Here, excellent formability means that the density and thickness of the inorganic fiber mat are easy to control. In addition, since inorganic fibers derived from a needle-punched mat are used as inorganic fibers, they are not excessively opened, and the produced inorganic fiber mat has both resilience and windability.

[0018] In the method for producing an inorganic fiber mat of the present invention, it is preferred that at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is cut.

[0019] By cutting the first inorganic fiber molded body and / or the second inorganic fiber molded body, the first inorganic fiber molded body and / or the second inorganic fiber molded body have a cut surface, and the inorganic fibers on the cut surface are easy to be opened, so that the inorganic fibers are not uniformly opened in the opening process, and the manufactured inorganic fiber mat has both resilience and windability. The cut first inorganic fiber molded body and the second inorganic fiber molded body include products and scraps described later.

[0020] In the method for producing an inorganic fiber mat of the present invention, it is preferred that at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is an irregular scrap having an uneven shape.

[0021] By using the scraps in the inorganic fiber material, the scraps can be effectively utilized without being discarded. In addition, by making the scraps into an irregular shape with a concave-convex shape, the inorganic fibers are not uniformly opened in the fiber opening process, and the manufactured inorganic fiber mat has both resilience and windability.

[0022] In the method for producing an inorganic fiber mat of the present invention, it is preferred that the first inorganic fiber molded body and the second inorganic fiber molded body have an area of ​​1 cm 2 The above sheet-shaped inorganic fiber molded body.

[0023] By dividing the area into 1cm 2 When the above-mentioned sheet-like inorganic fiber molded body is used as a material, the inorganic fibers are not uniformly opened, and the produced inorganic fiber mat has both resilience and windability.

[0024] In the method for producing an inorganic fiber mat of the present invention, it is preferred that the second inorganic fiber molded body contains an inorganic binder.

[0025] By including an inorganic binder in the second inorganic fiber molded body, the dispersibility of the inorganic binder in the produced inorganic fiber mat is high.

[0026] It is preferred that the average fiber length of the inorganic fibers constituting the needle punched mat is longer than the average fiber length of the inorganic fibers constituting the papermaking mat.

[0027] The first inorganic fiber molded body derived from the needle-punched mat is not over-fiberized compared to the second inorganic fiber molded body derived from the papermaking mat, and the average fiber length of the inorganic fibers derived from the papermaking mat after fiberization becomes shorter than the average fiber length of the inorganic fibers derived from the needle-punched mat after fiberization, so the manufactured inorganic fiber mat has both resilience and windability.

[0028] The first inorganic fiber molded body preferably has a ratio of 5 to 95% by weight relative to the total weight of the first inorganic fiber molded body and the second inorganic fiber molded body. When the ratio of the first inorganic fiber molded body is within the above range, the inorganic fiber mat obtained by the manufacturing method of the present invention has both higher resilience and higher windability.

[0029] The above-mentioned fiber-opening is preferably performed only by wet fiber-opening.

[0030] When the inorganic fibers are opened only by wet opening, the process becomes simple.

[0031] The needle punch mat is preferably formed by folding thin layers of an inorganic fiber precursor a plurality of times at a predetermined width, stacking the layers, and then firing the layers.

[0032] In such scraps of needle punched mats, the proportion of inorganic fibers with long fiber length is high, and by using such scraps in the material, the inorganic fiber mat obtained by the production method of the present invention has a high surface pressure.

[0033] Prior to the fiber-opening step, the first inorganic fiber molded body and the second inorganic fiber molded body are preferably cut.

[0034] This is because the fiber-opening step can be smoothly performed when the inorganic fiber molded body is cut in advance before the fiber-opening step.

[0035] In the method for producing an inorganic fiber mat of the present invention, the slurry may further contain new inorganic fibers. When the slurry contains new inorganic fibers, the new inorganic fibers have the same composition as the fiberized inorganic fibers and are alumina-silica fibers containing 60 to 80 wt% of Al2O3.

[0036] By adding new inorganic fibers to the slurry, the inorganic fiber mat obtained by the manufacturing method of the present invention can be adjusted to the desired physical properties. In addition, if the new inorganic fibers have the same composition as the above-mentioned inorganic fibers, the thermal expansion coefficient of the inorganic fibers is the same, so the close contact between the fibers will not shift when used at high temperatures, and the surface pressure can be maintained. Furthermore, by making the inorganic fibers contain 60 to 80 weight % of Al2O3, the resilience and heat resistance of the obtained inorganic fiber mat are improved.

[0037] The inorganic fiber mat of the present invention is produced by the method for producing an inorganic fiber mat of the present invention.

[0038] The inorganic fiber mat of the present invention is formed by papermaking using a slurry containing inorganic fibers obtained by fibrillating a first inorganic fiber molded body derived from a needle punched mat and a second inorganic fiber molded body derived from a papermaking mat. Therefore, the density and thickness can be easily controlled and both resilience and windability are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram for explaining how the first inorganic fiber molded body derived from the needle punched mat is opened.

[0040] Figure 2 This is a schematic diagram for explaining how the second inorganic fiber molded body derived from the papermaking mat is opened.

[0041] Figure 3A This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced by the production method of the present invention.

[0042] Figure 3B This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced from the first inorganic fiber molded body.

[0043] Figure 3C This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced from the second inorganic fiber molded body.

[0044] Figure 4 This is a plan view showing a holding sealing material for an exhaust gas purifying device and scraps cut out from an inorganic fiber mat.

[0045] Figure 5A This is a schematic diagram showing one example of manufacturing a folded laminated needle punched mat.

[0046] Figure 5B yes Figure 5A AA cross-sectional view of the folded laminated needle punched mat manufactured in. DETAILED DESCRIPTION

[0047] The embodiments of the present invention are described in detail below. However, the present invention is not limited to the following embodiments, and can be applied with appropriate modifications within the scope of the present invention.

[0048] In the method for producing an inorganic fiber mat of the present invention, a first inorganic fiber molded body derived from a needle punched mat and a second inorganic fiber molded body derived from a papermaking mat are used as materials.

[0049] The first inorganic fiber molded body is derived from a needle punched mat. The needle punched mat is a mat produced by subjecting a mat containing inorganic fibers to a needle punching treatment. Needle punching treatment refers to inserting and pulling out a fiber interlacing means such as a needle into and out of a mat containing inorganic fibers. The needle punched mat used as the first inorganic fiber molded body has a plurality of interlacing points formed by needle punching treatment on at least one of the front and back surfaces.

[0050] The average fiber length of the inorganic fibers constituting the needle punched mat is preferably longer than the average fiber length of the inorganic fibers constituting the papermaking mat.

[0051] As described later, the first inorganic fiber molded body derived from the needle-punched mat is not over-fiberized compared to the second inorganic fiber molded body derived from the papermaking mat, and the average fiber length of the inorganic fibers derived from the papermaking mat after fiberization becomes shorter than the average fiber length of the inorganic fibers derived from the needle-punched mat after fiberization, so the manufactured inorganic fiber mat has both resilience and windability.

[0052] The average fiber length of the inorganic fibers constituting the needle punched mat is not particularly limited, but needs to have a certain length in order to present an interlaced structure, preferably 3.0 to 100 mm, more preferably 10.0 to 100 mm. In addition, the average fiber diameter (diameter) of the inorganic fibers constituting the needle punched mat is preferably 2 to 10 μm, more preferably 3 to 7 μm.

[0053] In this specification, the average fiber length and average fiber diameter of the inorganic fibers are obtained by observing arbitrary 100 inorganic fibers within a field of view during SEM (scanning electron microscope) observation of the inorganic fiber mat.

[0054] The second inorganic fiber molded body is derived from a papermaking mat. A papermaking mat is a mat produced by subjecting a mat containing inorganic fibers to a papermaking process. The papermaking process in this specification refers to fiberizing, pulping, and molding of inorganic fibers.

[0055] The average fiber length of the inorganic fibers constituting the papermaking mat is preferably about 0.01 mm to 5.0 mm. The preferred average fiber diameter (diameter) of the inorganic fibers constituting the papermaking mat is the same as that of the inorganic fibers constituting the needle punched mat.

[0056] In the method for producing an inorganic fiber mat of the present invention, it is preferred that the average fiber length of the inorganic fibers constituting the needle punched mat is 10.0 to 100 mm, and the average fiber length of the inorganic fibers constituting the papermaking mat is 0.01 to 5.0 mm.

[0057] When the average fiber length of the inorganic fibers constituting the needle punched mat and the average fiber length of the inorganic fibers constituting the papermaking mat are respectively within the above ranges, the inorganic fiber mat obtained by the production method of the present invention has both higher resilience and higher windability.

[0058] The inorganic fibers constituting the first inorganic fiber molded body and the inorganic fibers constituting the second inorganic fiber molded body are not particularly limited, but are preferably composed of at least one selected from the group consisting of alumina fibers, silica fibers, alumina-silica fibers, mullite fibers, biosoluble fibers and glass fibers.

[0059] When the inorganic fiber is at least one of alumina fiber, silica fiber, alumina-silica fiber and mullite fiber, the heat resistance is excellent, so even when the inorganic fiber mat is exposed to high temperature, it will not deteriorate, and the function as a mat material can be fully maintained. In addition, when the inorganic fiber is a biosoluble fiber, when the manufactured inorganic fiber mat is used to make an exhaust gas purification device, even if the scattered inorganic fiber is inhaled, it will dissolve in the body, so it will not cause harm to the health of the operator.

[0060] The alumina fibers may contain additives such as calcium oxide, magnesium oxide, and zirconium oxide in addition to aluminum oxide.

[0061] The composition ratio of the alumina-silica fibers is preferably Al2O3:SiO2=60:40 to 80:20, more preferably Al2O3:SiO2=70:30 to 74:26 in terms of weight ratio.

[0062] Examples of alumina-silica fibers include fibers containing 60 to 80% by weight of Al2O3.

[0063] The inorganic fibers of the first inorganic fiber molded body and the inorganic fibers of the second inorganic fiber molded body may have the same composition or different compositions.

[0064] Below, refer to Figure 1 , Figure 2 , Figure 3A , Figure 3B as well as Figure 3C The difference in moldability between the case where only an inorganic fiber molded body derived from a needle punched mat is used as a raw material and the case where only an inorganic fiber molded body derived from a papermaking mat is used as a raw material, and in the production method of the present invention will be described.

[0065] Inorganic fiber materials derived from papermaking mats generally have short average fiber length and high bulk density in water. Therefore, it is difficult to increase the thickness of the inorganic fiber mat by papermaking, and it is difficult to control the density and thickness of the inorganic fiber mat.

[0066] Secondly, since the needle punched mat has a structure in which inorganic fibers are interwoven, unlike a papermaking mat, the fibers are not evenly opened even if opened.

[0067] Figure 1 This is a schematic diagram for explaining how the first inorganic fiber molded body derived from the needle punched mat is opened. Figure 2 Schematic diagram for explaining the opening of the second inorganic fiber molded body from the papermaking mat. Figure 1 and Figure 2 As shown, the inorganic fibers 11 derived from the needle punched mat constituting the first inorganic fiber molded body 10 derived from the needle punched mat and the inorganic fibers 21 derived from the papermaking mat constituting the second inorganic fiber molded body 20 derived from the papermaking mat are both short-fibered by fiber opening to obtain short-fibered inorganic fibers 11a derived from the needle punched mat, short-fibered inorganic fibers 12a derived from the interlacing points of the needle punched mat, and short-fibered inorganic fibers 21a derived from the papermaking mat.

[0068] like Figure 1As shown, in the needle punched mat, the entanglement of the inorganic fibers is completely different at the parts where the needle punching is performed (also called needle punch marks or interlacing points) and other parts. The inorganic fibers 12 at the interlacing points are not easily untied even after the fiber opening treatment and exist as fiber bundles. Therefore, compared with the second inorganic fiber molded body 20 derived from the papermaking mat, the average fiber length of the inorganic fibers (short-fibered inorganic fibers derived from the interlacing points of the needle punched mat) 12a tends to be less likely to be shortened. Although the average fiber length of the inorganic fibers of the needle punched mat and the papermaking mat is sometimes the same, since the needle punched mat is mostly formed of relatively long inorganic fibers and has interlacing points, it also contains fiber bundles after fiber opening, unlike the papermaking mat, and the average fiber length of the inorganic fibers (short-fibered inorganic fibers derived from the needle punched mat, short-fibered inorganic fibers derived from the interlacing points of the needle punched mat) 11a, 12a after fiber opening tends to be long.

[0069] exist Figure 3A , Figure 3B as well as Figure 3C In the following, the process of forming the fiber-opened inorganic fibers into a mold is described. Figure 3A This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced by the production method of the present invention. Figure 3B This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced from the first inorganic fiber molded body. Figure 3C This is a schematic cross-sectional view showing the structure of an inorganic fiber mat produced from the second inorganic fiber molded body.

[0070] In order to be used as an inorganic fiber mat, the inorganic fibers need to be evenly distributed, but if Figure 3B As shown, when only inorganic fibers 11a, 12a derived from a needle punched mat are used, it is difficult to reduce the thickness of the manufactured inorganic fiber mat 101 due to the presence of fiber bundles and the long average fiber length of the inorganic fibers.

[0071] In the papermaking process in the manufacturing method of the present invention, Figure 3A As shown, a papermaking process is performed using a slurry containing inorganic fibers 11a, 12a derived from a needle-punched mat and inorganic fibers 21a derived from a papermaking mat. As described later, the raw material sheet is usually pressed after papermaking to adjust the thickness by about 0.3 to 0.5 times. However, when only inorganic fibers 11a, 12a derived from a needle-punched mat are used, the distribution of inorganic fibers in the prototype sheet is uneven compared to the case of using short inorganic fibers 21a derived from a papermaking mat, and the volume of the prototype sheet increases, so it is difficult to adjust the thickness and density by pressing. In addition, it is difficult to eliminate the uneven distribution of inorganic fibers during pressing. Therefore, it is important to obtain a prototype sheet with uniform distribution of inorganic fibers during papermaking.

[0072] When a material including inorganic fibers and fiber bundles of various fiber lengths is subjected to papermaking, the fiber bundles and inorganic fibers of different fiber lengths are entangled with each other because the material is uniformly dispersed. If inorganic fibers 21a derived from a papermaking mat are present in addition to inorganic fibers 11a and 12a derived from a needle punched mat, short inorganic fibers 21a derived from a papermaking mat enter between inorganic fibers 11a and 12a derived from a needle punched mat. As a result, when an inorganic fiber mat 100 having the same fiber surface specific gravity is manufactured, the thickness of the manufactured inorganic fiber mat can be reduced compared to the case where only inorganic fibers 11a and 12a derived from a needle punched mat are used.

[0073] like Figure 3B As shown, when only the inorganic fibers 11a and 12a derived from the needle-punched mat are used, it is difficult to reduce the thickness of the inorganic fiber mat 101. Figure 3C As shown, it is difficult to increase the thickness of the inorganic fiber mat 102 using only the inorganic fibers 21a derived from the papermaking mat.

[0074] By using a slurry containing inorganic fibers derived from a needle punched mat and inorganic fibers derived from a papermaking mat for papermaking molding as in the manufacturing method of the present invention, the thickness of the inorganic fiber mat can be appropriately controlled to manufacture the inorganic fiber mat so that the thickness of the inorganic fiber mat is smaller than that of an inorganic fiber mat derived only from a needle punched mat and larger than that of an inorganic fiber mat derived from a papermaking mat. Therefore, the inorganic fiber mat of the manufacturing method of the present invention has excellent moldability.

[0075] The second inorganic fiber molded body preferably contains an inorganic binder. This is because the dispersibility of the inorganic binder in the inorganic fiber mat newly produced by the method of the present invention is improved by making the second inorganic fiber molded body contain an inorganic binder.

[0076] The inorganic binder may or may not be contained in the first inorganic fiber molded body, but is preferably contained in both the first inorganic fiber molded body and the second inorganic fiber molded body.

[0077] Examples of the inorganic binder include any appropriate hard ceramic material such as at least one of alumina, silica, silicon carbide, zirconium oxide, boron nitride, diamond and pumice, or a combination thereof, and preferably alumina sol and silica sol.

[0078] The first inorganic fiber molded body and the second inorganic fiber molded body may contain an organic binder. In this case, it is preferred that the first inorganic fiber molded body and the second inorganic fiber molded body be fired before the fiber opening step described below to decompose and remove the organic binder.

[0079] The first inorganic fiber molded body and the second inorganic fiber molded body used in the present invention may be inorganic fiber molded bodies in a molded shape that has not been cut, but preferably inorganic fiber molded bodies in which at least one of the molded bodies is cut. By cutting the first inorganic fiber molded body and / or the second inorganic fiber molded body, the first inorganic fiber molded body and / or the second inorganic fiber molded body have a cut surface, and the inorganic fibers on the cut surface are easily opened, so that the inorganic fibers are not evenly opened in the opening process, and the manufactured inorganic fiber mat has both resilience and winding properties. The first inorganic fiber molded body and the second inorganic fiber molded body used in the present invention may all be cut. The first inorganic fiber molded body and the second inorganic fiber molded body that are cut include products and scraps described later.

[0080] The cut first inorganic fiber molded body and the second inorganic fiber molded body are preferably cut by punching or cutting. Punching is a method of sandwiching the material to be processed between a die and a plate, pressing the die from above, and cutting into a desired shape. Cutting is a method of cutting the material with a cutter. Punching usually cuts the material along the shape of the die, but cutting is different from punching, and the cutting shape is not limited.

[0081] In the method for manufacturing an inorganic fiber mat of the present invention, the first inorganic fiber molded body and the second inorganic fiber molded body as materials preferably have two or more different shapes. Here, "the inorganic fiber molded body has a different shape" means that at least one of the appearance and size of the inorganic fiber molded body is different. The difference in appearance and size does not include a difference in size of about a few percent. Even if the appearance is the same, if the size is different, it is considered to be different in shape.

[0082] If two or more inorganic fiber molded bodies of different shapes are used, the inorganic fibers will not be evenly opened in the fiber opening process, and inorganic fiber materials of various fiber lengths and shapes can be obtained, so that the density and thickness of the manufactured inorganic fiber mat can be adjusted more easily, and an inorganic fiber mat with both resilience and winding properties can be manufactured. The shape of the inorganic fiber molded body is not particularly limited, and can include sheet-like, rope-like, spherical, and block-like shapes. As sheet-like inorganic fiber molded bodies, square, rectangular, circular, elliptical, etc. can be mentioned.

[0083] At least one of the first inorganic fiber molded body and the second inorganic fiber molded body is preferably a scrap. Scraps refer to the remaining portion after taking the required portion from the material. In the case of manufacturing a retaining sealing material for an exhaust gas purification device, etc., it is made by punching out a predetermined shape or cutting out a large sheet-like inorganic fiber mat, so the corners of the sheet are generated as scraps. By using scraps in the inorganic fiber material, it can be effectively utilized without discarding the scraps, so it is preferred.

[0084] Figure 4 This is a top view showing the holding seal material and scraps cut out of the inorganic fiber mat for the exhaust gas purification device. At the manufacturing site of the holding seal material, in order to cut out a plurality of holding seal materials from a large inorganic fiber mat, such as Figure 4 As shown, first, the inorganic fiber mat 31 is divided into a holding seal material forming part 32 and a scrap 33. The outer peripheral end 31a of the inorganic fiber mat shows the outer shape of the inorganic fiber mat 31 before cutting. Then, the holding seal material forming part 32 is divided into individual holding seal materials 34.

[0085] When the sealing material forming portion 32 is cut out, the pattern is considered in such a way as to increase the number of straight line portions for efficient cutting and to minimize the generation of scraps 33. When the sealing material 34 has a concave-convex shape, the scraps 33 may have a concave-convex shape.

[0086] In the manufacturing method of the present invention, it is more preferable to use such irregular scraps with concavoconvex shapes as the material of the inorganic fibers. By making the scraps have irregular shapes with concavoconvex shapes, the inorganic fibers are not uniformly opened in the fiber opening step, and the manufactured inorganic fiber mat has both resilience and windability.

[0087] When the sealing material forming part 32 is cut from the central part of the inorganic fiber mat material 31, the scrap 33 becomes a frame shape. The scrap 33 can also be directly used in the manufacturing method of the present invention in a frame shape, but if it is cut along, for example, the longitudinal direction and the transverse direction, then the scrap 33 of various shapes can be obtained.

[0088] The first inorganic fiber molded body and the second inorganic fiber molded body preferably have an area of ​​1 cm 2 More preferably, the area is 10 cm 2 In addition, there is no particular upper limit on the size of the first inorganic fiber molded body and the second inorganic fiber molded body. For example, when the first inorganic fiber molded body and the second inorganic fiber molded body are in sheet form, the preferred area is 130 cm 2 This is because by taking the area of ​​1cm 2 When the above-mentioned sheet-like inorganic fiber molded body is used as a material, the inorganic fibers are not uniformly opened, and the produced inorganic fiber mat has both resilience and windability.

[0089] In the production method of the present invention, the needle punched mat is preferably formed by folding a thin layer sheet of an inorganic fiber precursor a plurality of times at a predetermined width, stacking the sheets, and then firing the sheets. Such a needle punched mat is also called a folded and stacked needle punched mat. Figure 5A This is a schematic diagram showing one example of manufacturing a folded laminated needle punched mat. Figure 5B yes Figure 5A AA cross-sectional view of the folded laminated needle punched mat manufactured in FIG. Figure 5A , Figure 5B As shown, the pre-fired needle punch mat 31A is formed by folding and stacking a thin layer sheet 35 of an inorganic fiber precursor multiple times at a predetermined width. Figure 5A As shown, the thin layer sheet 35 of the inorganic fiber precursor is folded while continuously moving in a direction perpendicular to the folding direction. The width and number of folding are not particularly limited, and for example, the width can be greater than 1000 mm and the number of folding can be greater than 5 times. In the folded portion 36 of the needle-punched mat 31A before firing, the proportion of inorganic fibers with long fiber length is high.

[0090] By using scraps including such folded-back portions as the material of the inorganic fiber mat, the inorganic fiber mat obtained by the production method of the present invention has a high surface pressure.

[0091] The folded and laminated needle punched mat can be produced by the method described in, for example, Japanese Patent Application Laid-Open No. 2008-7933.

[0092] The ratio of the first inorganic fiber molded body and the second inorganic fiber molded body is not particularly limited. In order to make the inorganic fiber mat obtained by the manufacturing method of the present invention have both resilience and windability, the ratio of the first inorganic fiber molded body is preferably 5 to 95% by weight relative to the total weight of the first inorganic fiber molded body and the second inorganic fiber molded body. When the ratio of the first inorganic fiber molded body is within the above range, the inorganic fiber mat obtained by the manufacturing method of the present invention has both higher resilience and higher windability. The ratio of the first inorganic fiber molded body is more preferably 50 to 90% by weight.

[0093] The method for manufacturing an inorganic fiber mat of the present invention comprises the following steps: a fiber opening step, in which the first inorganic fiber molded body and the second inorganic fiber molded body are fiberized to obtain inorganic fibers; and a papermaking and molding step, in which a slurry containing the fiberized inorganic fibers is used to papermake the inorganic fiber mat.

[0094] As described above, when the first inorganic fiber molded body and the second inorganic fiber molded body contain an organic binder, it is preferred to perform a firing step of firing the first inorganic fiber molded body and the second inorganic fiber molded body before the fiber opening step. The firing is performed at 700 to 1000° C. for 1 to 8 hours, for example. The preferred firing temperature is 800 to 950° C.

[0095] The fiber opening in the fiber opening step can be performed by a single treatment of only wet fiber opening, or a two-step treatment of dry fiber opening and wet fiber opening. In the production method of the present invention, it is preferred that only wet fiber opening is performed in the fiber opening step for the sake of simplicity of the process.

[0096] Wet fiber opening can be performed using a wet fiber opening device such as a beater or a mixer. Wet fiber opening can be performed by putting the first inorganic fiber mold and the second inorganic fiber mold into a wet fiber opening device with water added and stirring. The order of putting the first inorganic fiber mold and the second inorganic fiber mold is not particularly limited. It is preferred that the first inorganic fiber mold is first put into water and stirred, and then the second inorganic fiber mold is subsequently put into water and stirred; or the first inorganic fiber mold and the second inorganic fiber mold are simultaneously put into water and stirred. In the manufacturing method of the present invention, in order to fully fiberize the first inorganic fiber mold, it is more preferred to first put the first inorganic fiber mold and stir it, and then put the second inorganic fiber mold and further stir it.

[0097] When dry fiber opening is performed, it is performed before wet fiber opening. Dry fiber opening can be performed using a device such as a screen-type crusher Feather Mill.

[0098] It should be noted that the first inorganic fiber molded body and the second inorganic fiber molded body may be pre-cut into desired sizes before the fiber-opening process. This is because the fiber-opening process can be smoothly performed when the inorganic fiber molded body is pre-cut before the fiber-opening process. When scraps are used as the first inorganic fiber molded body and the second inorganic fiber molded body, the fiber-opening process may be performed directly without further cutting.

[0099] Here, by changing the processing conditions (such as stirring speed, stirring time, etc.) of wet fiber opening and dry fiber opening, the average fiber length of the obtained inorganic fiber can be adjusted. As an example of the processing conditions of wet fiber opening, for example, a stirring speed of 500 to 1000 rpm and a stirring time of 200 to 900 seconds can be cited. Preferably, the stirring speed is 650 to 850 rpm and the stirring time is 500 to 700 seconds, and more preferably, the stirring speed is 700 to 800 rpm and the stirring time is 500 to 650 seconds.

[0100] Through such a fiber opening step, inorganic fibers having a desired fiber length distribution can be obtained. It should be noted that whether the inorganic fibers have a desired fiber length distribution can be confirmed by examining the bulk density.

[0101] Next, a papermaking and molding step is performed to papermake an inorganic fiber mat using a slurry containing the fiberized inorganic fibers.

[0102] The slurry can be prepared, for example, as follows.

[0103] First, prepare a liquid containing water and fiberized inorganic fibers so that the concentration of the inorganic fibers is about 0.5 to 2.0 weight %. When adding water or fiberized inorganic fibers to the liquid during the preparation of the slurry, stir it with a stirrer for about 20 to 120 seconds. Next, add an organic binder in an amount of about 0.5 to 10 weight % relative to the inorganic fibers to the liquid, and stir for about 1 to 5 minutes. Further, add an inorganic binder in an amount of about 0.5 to 3 weight % relative to the inorganic fibers to the liquid, and stir for about 1 to 5 minutes. Further, add a coagulant in an amount of about 0.01 to 1.0 weight % relative to the inorganic fibers to the liquid, stir for about 2 minutes at most, and prepare the slurry.

[0104] The slurry preferably further contains new inorganic fibers. By adding new inorganic fibers to the slurry, the inorganic fiber mat obtained by the manufacturing method of the present invention can be adjusted to the desired physical properties. Here, new inorganic fibers refer to inorganic fibers that are first formed into inorganic fibers and have never been used as a product.

[0105] The average fiber length of the new inorganic fibers can be adjusted according to the desired physical properties, and is preferably about 0.01 mm to 100 mm. The preferred average fiber diameter (diameter) of the new inorganic fibers is the same as that of the inorganic fibers constituting the needle punched mat and the inorganic fibers constituting the papermaking mat.

[0106] As the composition of the new inorganic fiber, the same composition as the composition exemplified as the inorganic fiber constituting the first inorganic fiber molded body and the inorganic fiber constituting the second inorganic fiber molded body can be cited. The new inorganic fiber is preferably the same composition as the inorganic fiber constituting the first inorganic fiber molded body and the inorganic fiber constituting the second inorganic fiber molded body. This is because if the composition of the inorganic fiber is the same, the thermal expansion coefficient is the same, so the close contact between the fibers will not deviate when used at high temperature, and the surface pressure can be maintained.

[0107] The new inorganic fibers, the inorganic fibers constituting the first inorganic fiber molded body, and the inorganic fibers constituting the second inorganic fiber molded body are more preferably alumina-silica fibers containing 60 to 80 wt% of Al2O3, because the resilience and heat resistance of the obtained inorganic fiber mat can be improved.

[0108] As the inorganic binder added in the preparation of the slurry, the same binder as the inorganic binder contained in the first inorganic fiber molded body and the second inorganic fiber molded body is used. In addition, latex is used as the organic binder, and a conventionally known coagulant can be used as the coagulant.

[0109] In the manufacturing method of the present invention, an inorganic binder is preferably added during the slurry preparation. When the first inorganic fiber molded body and the second inorganic fiber molded body contain an inorganic binder, the inorganic binder need not be newly added in the papermaking molding step, and even when an inorganic binder is added, the amount added may be a small amount compared to the above amount. Even when the first inorganic fiber molded body and the second inorganic fiber molded body contain an inorganic binder, the same amount of inorganic binder added as above may be added to the slurry.

[0110] When the first inorganic fiber molded body and the second inorganic fiber molded body contain an inorganic binder, the inorganic binder mixed in the papermaking molding step may be the same material as the inorganic binder contained in the first inorganic fiber molded body and the second inorganic fiber molded body, or an inorganic binder of a different material may be used.

[0111] The sheet-forming of the inorganic fiber mat using the slurry can be performed, for example, as follows.

[0112] The prepared slurry is added to a former of the desired shape, and a raw material sheet is formed, which is further dehydrated. Under normal circumstances, a metal mesh for filtering (mesh size: 30 mesh) is provided at the bottom of the former, and the water in the slurry added to the former is discharged through the metal mesh for filtering. Therefore, by using such a former, the forming and dehydration of the raw material sheet can be carried out simultaneously. In addition, a suction pump, a vacuum pump, etc. can be used if necessary to force the water to be sucked from the lower side of the former via the metal mesh for filtering.

[0113] Next, the obtained raw material sheet is taken out from the molding machine, and compressed using a press to a thickness of about 0.3 to 0.5 times, and heated and dried at a temperature of, for example, 150 to 210°C for 5 minutes to 1 hour, thereby obtaining an inorganic fiber mat.

[0114] The inorganic fiber mat obtained by the production method of the present invention can be cut into a desired shape and used as a holding sealing material for an exhaust gas purification device or the like.

[0115] The inorganic fiber mat obtained by the manufacturing method of the present invention is also one of the present invention. The inorganic fiber mat of the present invention is formed by papermaking using a slurry containing inorganic fibers obtained by fibrillating a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a papermaking mat, so that the density and thickness are easily controlled, and both resilience and windability are achieved.

[0116] The following matters are disclosed in this specification.

[0117] The present disclosure (1) relates to a method for manufacturing an inorganic fiber mat, characterized in that a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a papermaking mat are used, and the method comprises the following steps: a fiber opening step, in which the first inorganic fiber molded body and the second inorganic fiber molded body are fiberized to obtain inorganic fibers; and a papermaking molding step, in which a slurry containing the fiberized inorganic fibers is used to papermake the inorganic fiber mat.

[0118] The present disclosure (2) is the method for producing the inorganic fiber mat according to the present disclosure (1), wherein at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is cut.

[0119] The present disclosure (3) relates to the method for producing the inorganic fiber mat described in the present disclosure (1) or (2), wherein at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is an irregular scrap having a concave-convex shape.

[0120] The present disclosure (4) is a method for producing an inorganic fiber mat according to any one of the present disclosures (1) to (3), wherein the first inorganic fiber molded body and the second inorganic fiber molded body are each 1 cm in area. 2 The above sheet-shaped inorganic fiber molded body.

[0121] The present disclosure (5) is the method for producing an inorganic fiber mat according to any one of the present disclosures (1) to (4), wherein the second inorganic fiber molded body contains an inorganic binder.

[0122] The present disclosure (6) is a method for producing an inorganic fiber mat according to any one of the present disclosures (1) to (5), wherein the average fiber length of the inorganic fibers constituting the needle punched mat is longer than the average fiber length of the inorganic fibers constituting the papermaking mat.

[0123] The present disclosure (7) is a method for producing an inorganic fiber mat as described in any one of the present disclosures (1) to (6), wherein the proportion of the first inorganic fiber molded body relative to the total weight of the first inorganic fiber molded body and the second inorganic fiber molded body is 5 wt% to 95 wt%.

[0124] The present disclosure (8) is the method for producing the inorganic fiber mat according to any one of the present disclosures (1) to (7), wherein the fiber-opening is performed only by wet fiber-opening.

[0125] The present disclosure (9) is a method for producing an inorganic fiber mat according to any one of the present disclosures (1) to (8), wherein the needle punched mat is formed by folding thin layers of an inorganic fiber precursor a plurality of times in a predetermined width, stacking the layers, and then firing the layers.

[0126] The present disclosure (10) is a method for producing an inorganic fiber mat according to any one of the present disclosures (1) to (9), wherein the first inorganic fiber molded body and the second inorganic fiber molded body are cut before the fiber-opening step.

[0127] The present disclosure (11) is a method for manufacturing an inorganic fiber mat as described in any one of the present disclosures (1) to (10), wherein the slurry further contains new inorganic fibers, the new inorganic fibers have the same composition as the fiber-opened inorganic fibers, and are alumina-silica fibers containing 60 to 80 weight percent of Al2O3.

[0128] The present disclosure (12) relates to an inorganic fiber mat manufactured by the following method for manufacturing an inorganic fiber mat, the manufacturing method being characterized in that it comprises: a fiber opening step, using a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a papermaking mat, the first inorganic fiber molded body and the second inorganic fiber molded body are fiberized to obtain inorganic fibers; and a papermaking molding step, using a slurry containing the fiberized inorganic fibers to perform papermaking molding of the inorganic fiber mat.

[0129] The present disclosure (13) is the inorganic fiber mat according to the present disclosure (12), wherein at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is cut.

[0130] The present disclosure (14) is the inorganic fiber mat described in the present disclosure (12) or (13), wherein at least one of the first inorganic fiber molded body and the second inorganic fiber molded body is an irregular scrap having a concave-convex shape.

[0131] The present disclosure (15) is the inorganic fiber mat according to any one of the present disclosures (12) to (14), wherein the first inorganic fiber molded body and the second inorganic fiber molded body are each 1 cm in area. 2 The above sheet-shaped inorganic fiber molded body.

[0132] The present disclosure (16) is the inorganic fiber mat according to any one of the present disclosures (12) to (15), wherein the second inorganic fiber molded body contains an inorganic binder.

[0133] The present disclosure (17) is the inorganic fiber mat according to any one of the present disclosures (12) to (16), wherein the average fiber length of the inorganic fibers constituting the needle punched mat is longer than the average fiber length of the inorganic fibers constituting the papermaking mat.

[0134] The present disclosure (18) is the inorganic fiber mat described in any one of the present disclosures (12) to (17), wherein the proportion of the first inorganic fiber molded body relative to the total weight of the first inorganic fiber molded body and the second inorganic fiber molded body is 5 to 95 weight %.

[0135] The present disclosure (19) is the inorganic fiber mat according to any one of the present disclosures (12) to (18), wherein the fiber-opening is performed only by wet fiber-opening.

[0136] The present disclosure (20) is the inorganic fiber mat described in any one of the present disclosures (12) to (19), wherein the needle punched mat is formed by folding thin layers of inorganic fiber precursors a plurality of times in a predetermined width, stacking the layers, and then firing the layers.

[0137] The present disclosure (21) is the inorganic fiber mat according to any one of the present disclosures (12) to (20), wherein the first inorganic fiber molded body and the second inorganic fiber molded body are cut before the fiber-opening step.

[0138] The present disclosure (22) is the inorganic fiber mat described in any one of the present disclosures (12) to (21), wherein the slurry further contains new inorganic fibers, the new inorganic fibers have the same composition as the fiber-opened inorganic fibers, and are alumina-silica fibers containing 60 wt% to 80 wt% of Al2O3.

[0139] (Example)

[0140] Hereinafter, embodiments that more specifically disclose the present invention will be described, but the present invention is not limited to these embodiments.

[0141] Next, a papermaking mat was prepared by papermaking an inorganic fiber material obtained by fiberizing a needle punched mat and a papermaking mat, and the bulk density, thickness, and windability (formability) in water were evaluated.

[0142] As shown in Table 1 below, Comparative Example 1 used only the first inorganic fiber molded body derived from the needle-punched mat, and Example 1 used the first inorganic fiber molded body derived from the needle-punched mat and the second inorganic fiber molded body derived from the paper-made mat (derived from the needle-punched mat: derived from the paper-made mat = 70:30, weight ratio). As the first inorganic fiber molded body derived from the needle-punched mat, alumina-silica fibers composed of Al2O3:SiO2=72:28 (weight ratio) and a density of needle marks of 21 / cm 2 As the second inorganic fiber molded body derived from the papermaking mat, a papermaking mat composed of alumina-silica fibers with Al2O3:SiO2=72:28 (weight ratio) was prepared.

[0143] First, the first inorganic fiber molded body and the second inorganic fiber molded body were fired at 800° C. for 1 hour to thermally decompose the organic binder, and then allowed to stand until they reached room temperature.

[0144] In Comparative Example 1, 40.0 g of the first inorganic fiber molded body was taken out, added to 1.6 L of water, and stirred using a stirrer (product name: SMT-101, manufacturer: ASONE) at a rotation speed of 750 rpm and a stirring time of 10 minutes to perform fiber opening, thereby preparing an inorganic fiber slurry.

[0145] Next, 0.5 to 10 parts by weight of an organic binder is added to the slurry based on 100 parts by weight of the inorganic fibers, and 0.5 to 3.0 parts by weight of an inorganic binder is added to the slurry based on 100 parts by weight of the inorganic fibers.

[0146] Next, the slurry is poured into a former having a filtration net formed on the bottom surface, and the solvent in the slurry is removed to obtain a sheet-like inorganic fiber aggregate. The inorganic fiber aggregate is then dehydrated and pressed using a general pressurized dryer so that the inorganic fiber aggregate has a thickness of 9.5 mm, and dried at 150 to 210° C. for 5 minutes to 1.0 hours to produce a sheet-like inorganic fiber aggregate having a fiber surface specific gravity of 1500 g / m 2 The papermaking mat of Comparative Example 1. The bulk density of the slurry of Comparative Example 1 in water is 0.01360 g / cm 3 , the thickness of the pad is 10.8mm.

[0147] In Example 1, a fiber having a fiber area specific gravity of 1500 g / m was produced in the same manner as in Comparative Example 1 except that 28.0 g of the first inorganic fiber molded body and 12.0 g of the second inorganic fiber molded body were used. 2 The papermaking mat of Example 1. The bulk density of the slurry of Example 1 in water is 0.01489 g / cm 3 , the thickness of the pad is 9.9mm.

[0148] The pads of Comparative Example 1 and Example 1 were cut into a rectangular shape with a length of 350 mm in the longitudinal direction and a length of 30 mm in the width direction to prepare test pieces, and the pads were wound around a cylinder with a diameter of 100 mm, and the test pieces were visually observed to see if cracks occurred. The case where no cracks occurred was evaluated as 0, and the case where cracks occurred was evaluated as ×, and the winding property was evaluated.

[0149] [Table 1]

[0150] Comparative Example 1 Example 1 Ratio of the first inorganic fiber molded body derived from the needle punched mat 100 70 Ratio of the second inorganic fiber molded body derived from the papermaking mat 0 30 <![CDATA[Volume density in water (g / cm 3 )]]> 0.01360 0.01489 <![CDATA[Fiber surface specific gravity (g / m 2 )]]> 1500 1500 Thickness(mm) 10.8 9.9 Winding × ○

[0151] As shown in Table 1, Example 1 using the first inorganic fiber molded body and the second inorganic fiber molded body as the material has a smaller mat thickness when pressed under the same conditions compared to Comparative Example 1 using only the first inorganic fiber molded body. When the material is only the first inorganic fiber molded body derived from the needle punched mat, the manufactured mat tends to be thicker, but when both the first inorganic fiber molded body derived from the needle punched mat and the second inorganic fiber molded body derived from the papermaking mat are used as the material and the papermaking mat is manufactured under the same conditions, the inorganic fibers derived from the papermaking mat enter the gaps between the inorganic fibers or fiber bundles derived from the needle punched mat and become dense, so it can be seen that even an inorganic fiber mat with the same fiber surface specific gravity can be formed into a mat with a smaller thickness.

[0152] From these results, it is understood that the density and thickness of the mat can be adjusted by variously changing the ratio of the first inorganic fiber molded body to the second inorganic fiber molded body.

[0153] Furthermore, the mat of Example 1 was thinner than the mat of Comparative Example 1 and was less likely to break even when wound around a cylinder. It was also found that the production method of the present invention can provide an inorganic fiber mat having excellent windability.

[0154] Description of Reference Numerals

[0155] 10First inorganic fiber molded body derived from needle punched mat

[0156] 11Inorganic fibers from needle punched mats

[0157] 11a Short fiberized inorganic fibers from needle punched mat

[0158] 12 interlaced inorganic fibers

[0159] 12a Short fiberized inorganic fibers derived from the interlacing points of the needle punched mat

[0160] 20 Second inorganic fiber molded body derived from papermaking mat

[0161] 21Inorganic fibers from papermaking mats

[0162] 21a Short fiberized inorganic fiber from papermaking mat

[0163] 31 Inorganic fiber mat

[0164] 31A Needle Punched Mat Before Firing

[0165] 31a Outer peripheral end

[0166] 32 Maintain the sealing material forming part

[0167] 33 Scrap

[0168] 34 Maintain sealing material

[0169] 35 Thin sheets of inorganic fiber precursors

[0170] 36 Turnaround

[0171] 100, 101, 102 inorganic fiber mat

Claims

1. An inorganic fiber mat manufactured by the following method for manufacturing an inorganic fiber mat, the manufacturing method comprising: a fiber opening step, using a first inorganic fiber molded body derived from a needle-punched mat and a second inorganic fiber molded body derived from a papermaking mat, the first inorganic fiber molded body and the second inorganic fiber molded body are fiberized to obtain inorganic fibers; and a papermaking molding step, using a slurry containing the fiberized inorganic fibers to perform papermaking molding of the inorganic fiber mat.

2. The inorganic fiber mat according to claim 1, wherein At least one of the first inorganic fiber molded body and the second inorganic fiber molded body is cut.

3. The inorganic fiber mat according to claim 1 or 2, wherein: At least one of the first inorganic fiber molded body and the second inorganic fiber molded body is an irregular scrap having a concavo-convex shape.

4. The inorganic fiber mat according to any one of claims 1 to 3, wherein The first inorganic fiber molded body and the second inorganic fiber molded body are 1 cm in area. 2 The above sheet-shaped inorganic fiber molded body.

5. The inorganic fiber mat according to any one of claims 1 to 4, wherein The second inorganic fiber molded body contains an inorganic binder.

6. The inorganic fiber mat according to any one of claims 1 to 5, wherein The average fiber length of the inorganic fibers constituting the needle punched mat is longer than the average fiber length of the inorganic fibers constituting the papermaking mat.

7. The inorganic fiber mat according to any one of claims 1 to 6, wherein The ratio of the first inorganic fiber molded body to the total weight of the first inorganic fiber molded body and the second inorganic fiber molded body is 5 wt% to 95 wt%.

8. The inorganic fiber mat according to any one of claims 1 to 7, wherein The fiber opening is performed only by wet fiber opening.

9. The inorganic fiber mat according to any one of claims 1 to 8, wherein The needle punch mat is formed by folding thin layers of an inorganic fiber precursor a plurality of times at a predetermined width, stacking the layers, and then firing the layers.

10. The inorganic fiber mat according to any one of claims 1 to 9, wherein Prior to the fiber-opening step, the first inorganic fiber molded body and the second inorganic fiber molded body are cut.

11. The inorganic fiber mat according to any one of claims 1 to 10, wherein The slurry further comprises new inorganic fibers, which have the same composition as the fiberized inorganic fibers and are alumina-silica fibers containing 60 wt % to 80 wt % of Al 2 O 3 .

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