Method for manufacturing inorganic fiber mat and inorganic fiber mat

Abstract

The present invention provides a method for manufacturing an inorganic fiber mat and an inorganic fiber mat. A method for manufacturing an inorganic fiber mat, characterized in that it uses a first inorganic fiber formed body derived from a needled mat to which an organic binder is attached, and has the following steps: a fiber opening step of opening the first inorganic fiber formed body to obtain inorganic fibers; and a papermaking and forming step of papermaking and forming an inorganic fiber mat using a slurry containing the inorganic fibers opened in the fiber opening step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an inorganic fiber mat and an inorganic fiber mat. Background Art

[0002] As an exhaust gas purification device for collecting particulate matter (PM) in exhaust gas or purifying harmful gas components, various proposals for an exhaust gas purification device have been made, which is composed of an exhaust gas treatment body (made of porous ceramics such as silicon carbide and cordierite), a housing for accommodating the exhaust gas treatment body, and a mat material (sealing material) of inorganic fibers disposed between the exhaust gas treatment body and the housing. This mat material is mainly provided to prevent breakage caused by contact between the exhaust gas treatment body and the housing covering its outer periphery due to vibrations or impacts generated during the driving of an automobile, etc.; and to prevent leakage of exhaust gas from between the exhaust gas treatment body and the housing.

[0003] In addition, such a mat material of inorganic fibers is produced by punching out a prescribed shape or cutting from a large sheet-like inorganic fiber mat, and the cut-off parts at the corners of the sheet become scrap. In recent years, there has been a demand for reducing industrial waste, and it is required to reuse the scrap generated during manufacturing without discarding it.

[0004] Patent Document 1 discloses a method for manufacturing a heat-insulating molded body, which is characterized in that waste materials of an inorganic fibrous heat-insulating material are defibrated, new inorganic fibers are mixed in the defibrated heat-insulating material to form a cotton-like state, and a binder is mixed and molded.

[0005] In addition, Patent Document 2 discloses a method for manufacturing a fiber molded body, which is characterized in that ceramic fibers are mixed with an ionic organic binder powder, and further water containing a heat-resistant inorganic binder is added and mixed to make the whole substantially in a wet state, and then the wet mixture is filled in a mold and molded under pressure. In this manufacturing method, a crushed product obtained by finely crushing a used fiber product is used instead of a part of the above-mentioned ceramic fibers.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 9-210289

[0009] Patent Document 2: Japanese Patent Laid-Open No. 2001-335379 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] However, the methods disclosed in Patent Documents 1 and 2 have the problem that the moldability of the products is insufficient.

[0012] The present invention has been completed in view of the above problems, and an object thereof is to provide a method for manufacturing an inorganic fiber mat that is more easily moldable even when an inorganic fiber material is used in an inorganic fiber molded body.

[0013] Means for Solving the Problem

[0014] The present inventors conducted intensive studies and found that by using inorganic fibers derived from a needled mat to which an organic binder is attached as the inorganic fibers, the moldability of a newly produced inorganic fiber mat can be improved.

[0015] 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 needled mat to which an organic binder is attached, and has the following steps: a fiber opening step of opening the first inorganic fiber molded body to obtain inorganic fibers; and a papermaking and molding step of papermaking and molding an inorganic fiber mat using a slurry containing the opened inorganic fibers.

[0016] Since the method for manufacturing an inorganic fiber mat of the present invention uses inorganic fibers derived from a needled mat to which an organic binder is attached as the inorganic fibers, the inorganic fibers are not over-opened, and the moldability of the inorganic fiber mat is excellent.

[0017] In the method for manufacturing an inorganic fiber mat of the present invention, it is preferable to further use a second inorganic fiber molded body derived from a papermaking mat.

[0018] If a second inorganic fiber molded body derived from a papermaking mat is used, the manufactured inorganic fiber mat has both resilience and winding properties.

[0019] In the method for manufacturing an inorganic fiber mat of the present invention, it is preferable that the first inorganic fiber molded body and the second inorganic fiber molded body contain an inorganic binder.

[0020] By making the first inorganic fiber molded body and the second inorganic fiber molded body contain an inorganic binder, the dispersibility of the inorganic binder in the manufactured inorganic fiber mat is high.

[0021] In the method for manufacturing an inorganic fiber mat of the present invention, it is preferable that the first inorganic fiber molded body and the second inorganic fiber molded body are scraps.

[0022] By using scraps in the inorganic fiber material, the scraps can be effectively utilized without being discarded.

[0023] The average fiber length of the inorganic fibers constituting the needled mat is preferably 3.0 to 100 mm.

[0024] When the average fiber length of the inorganic fibers constituting the needle-punched mat is within the above range, the inorganic fiber mat obtained by the production method of the present invention has both higher resilience and higher winding property.

[0025] The above fibrillation is preferably carried out only by wet fibrillation.

[0026] When the inorganic fibers are fibrillated only by wet fibrillation, the process becomes simple.

[0027] The above needle-punched mat is preferably formed by laminating thin sheets of the inorganic fiber precursor folded a plurality of times with a prescribed width and then firing.

[0028] In the scraps of such a needle-punched mat, the proportion of inorganic fibers with long fiber lengths is high. By using such scraps as a material, the inorganic fiber mat obtained by the production method of the present invention has a high surface pressure.

[0029] Before the above fibrillation step, it is preferable to cut the above first inorganic fiber formed body and the above second inorganic fiber formed body.

[0030] This is because when the inorganic fiber formed body is cut before the fibrillation step, the fibrillation step can proceed smoothly.

[0031] In the production method of the inorganic fiber mat of the present invention, it is preferable that the above slurry further contains new inorganic fibers, the new inorganic fibers have the same composition as the fibrillated inorganic fibers, and are alumina-silica fibers containing 60 to 80% by weight of Al 2 O 3

[0032] By adding new inorganic fibers to the slurry, the inorganic fiber mat obtained by the production method of the present invention can be adjusted to desired physical properties. In addition, if the new inorganic fibers have the same composition as the fibrillated inorganic fibers, the thermal expansion coefficients of the inorganic fibers are the same. Therefore, at high temperatures, the bonding portions between the fibers do not shift, and the surface pressure can be maintained. Furthermore, by making the inorganic fibers alumina-silica fibers containing 60 to 80% by weight of Al 2 O 3 the resilience and heat resistance of the obtained inorganic fiber mat are improved.

[0033] It is preferable to carry out a firing step of firing the above first inorganic fiber formed body and the above second inorganic fiber formed body before the above fibrillation step.

[0034] This is because when the organic binders attached to the first inorganic fiber formed body and the second inorganic fiber formed body are removed by firing, fibrillation can proceed smoothly.

[0035] The above firing is preferably carried out at 700 to 1000 °C for 1 to 8 hours.

[0036] When firing under the above conditions, the removal of the organic binder can be carried out more reliably.

[0037] In the method for manufacturing the inorganic fiber mat of the present invention, it is preferable to add an inorganic binder and an organic binder to the above slurry.

[0038] By adding an inorganic binder, the surface pressure of the inorganic fiber mat obtained by the manufacturing method of the present invention is further increased. In addition, by adding an organic binder, the inorganic fiber mat obtained by the manufacturing method of the present invention has excellent formability.

[0039] It is preferable to heat and dry the inorganic fiber mat formed by the above papermaking forming process at a temperature of 150 to 210 °C for 5 minutes to 1 hour.

[0040] The inorganic fiber mat of the present invention includes inorganic fibers derived from a needle-punched mat, inorganic fibers derived from a papermade mat, an inorganic binder, and an organic binder.

[0041] Since the inorganic fiber mat of the present invention includes inorganic fibers derived from a needle-punched mat and inorganic fibers derived from a papermade mat, it has both resilience and winding properties.

[0042] The inorganic fiber mat of the present invention may include fired particles of an inorganic binder, and a mixture of an unfired inorganic binder and an organic binder.

[0043] When the needle-punched mat containing an inorganic binder is fired and used as an inorganic fiber material, the inorganic fiber mat of the present invention includes fired particles of the inorganic binder. In addition, when an inorganic binder and an organic binder are added to the inorganic fibers, the inorganic fiber mat of the present invention includes a mixture of an unfired inorganic binder and an organic binder. For example, when silica sol and / or alumina sol is used as the inorganic binder, the inorganic binder in the above mixture is unfired amorphous silica and / or unfired amorphous alumina.

[0044] It is preferable that the major axis of the fired particles of the above inorganic binder is 0.01 to 4 μm, and the major axis of the above mixture is 5 to 20 μm.

[0045] It is preferable that the fired particles of the above inorganic binder are glass particles of the inorganic binder and / or particles containing crystals and glass of the inorganic binder.

[0046] When the inorganic binder is silica sol, for example, under the firing conditions (700 to 1000° C., 1 to 8 hours) in the manufacturing method of the present invention, no crystals are formed, and the fired particles are composed of silica glass. When the inorganic binder is alumina sol, crystals are generated by firing at 500° C. or above, so under the above firing conditions in the manufacturing method of the present invention, a part of the fired particles is composed of alumina glass as γ-alumina crystals.

[0047] It is preferred that the fired particles of the inorganic binder adhere to the surface of the inorganic fibers, and the mixture covers the contact portions between the inorganic fibers and the surfaces of the inorganic fibers, or adheres to the surfaces of the inorganic fibers in a massed form. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 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.

[0049] Figure 2A This is a schematic diagram showing one example of manufacturing a folded laminated needle punched mat.

[0050] Figure 2B yes Figure 2A AA cross-section of the folded laminated needle punched mat manufactured in.

[0051] Figure 3 This is an example of an enlarged electron microscope image of the inorganic fiber mat of the present invention. DETAILED DESCRIPTION

[0052] 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.

[0053] (Method for producing inorganic fiber mat)

[0054] 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 to which an organic binder is added is used as a material of the inorganic fiber mat.

[0055] The needle punched mat is a mat made by needle punching a mat containing inorganic fibers. Needle punching 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 on at least one of the front and back surfaces.

[0056] In order to present an interleaved structure, the average fiber length of the inorganic fibers constituting the above-mentioned needling mat needs to have a certain degree of length, preferably 3.0 to 100 mm. When the average fiber length of the inorganic fibers constituting the needling mat is within the above range, the inorganic fiber mat obtained by the manufacturing method of the present invention has both higher resilience and higher winding property. In addition, the average fiber diameter (diameter) of the inorganic fibers constituting the needling mat is preferably 2 to 10 μm, more preferably 3 to 7 μm.

[0057] In this specification, the average fiber length and average fiber diameter of the inorganic fibers are obtained by observing any 100 inorganic fibers in the field of view in the SEM (scanning electron microscope) observation of the sealing material while maintaining the seal.

[0058] The inorganic fibers constituting the first inorganic fiber formed body are not particularly limited, and are preferably composed of at least one selected from the group consisting of alumina fibers, silica fibers, alumina-silica fibers, mullite fibers, bio-soluble fibers, and glass fibers. When the inorganic fibers are at least one of alumina fibers, silica fibers, alumina-silica fibers, and mullite fibers, the heat resistance is excellent, so even when the exhaust gas treatment body is exposed to a sufficient high temperature, deterioration and the like do not occur, and the function as a mat material can be sufficiently maintained. In addition, when the inorganic fibers are bio-soluble fibers, when using the mat material to manufacture an exhaust gas purification device, even if scattered inorganic fibers are inhaled, they will dissolve in the living body, so it will not pose a hazard to the health of the operator.

[0059] In the alumina fibers, additives such as calcium oxide, magnesium oxide, and zirconium oxide can be contained in addition to alumina.

[0060] As the composition ratio of the alumina-silica fiber, the weight ratio is preferably Al 2 O 3 :SiO 2 = 60:40 to 80:20, more preferably Al 2 O 3 :SiO 2 = 70:30 to 74:26.

[0061] As the alumina-silica fiber, fibers containing 60 to 80% by weight of Al 2 O 3 can also be cited.

[0062] The first inorganic fiber formed body is attached with an organic binder. As the organic binder, for example, acrylic latex, rubber latex, etc. can be cited.

[0063] In the manufacturing method of the present invention, a second inorganic fiber formed body from a forming mat can be used together with the first inorganic fiber formed body. A forming mat is a mat manufactured by subjecting a mat containing inorganic fibers to a forming process. The forming process in this specification refers to the fibrillation, pulping, and forming of inorganic fibers.

[0064] The average fiber length of the inorganic fibers constituting the above-mentioned forming mat is preferably about 0.01 mm to 5.0 mm. In addition, the preferred average fiber diameter (diameter) of the inorganic fibers constituting the forming mat is the same as that of the inorganic fibers constituting the needled mat.

[0065] When using the second inorganic fiber formed body from a forming mat together with the first inorganic fiber formed body, the manufactured inorganic fiber mat has both resilience and winding properties.

[0066] The inorganic fibers of the first inorganic fiber formed body and the inorganic fibers of the second inorganic fiber formed body can have the same composition or different compositions.

[0067] In the case of using the above-mentioned second inorganic fiber formed body, the ratio of the first inorganic fiber formed body and the second inorganic fiber formed 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 winding properties, the ratio of the first inorganic fiber formed body is preferably 5 to 95% by weight, more preferably 70 to 90% by weight, based on the total weight of the first inorganic fiber formed body and the second inorganic fiber formed body.

[0068] The second inorganic fiber formed body can be attached with an organic binder. Examples of the composition of the organic binder can be the same as those of the organic binder of the first inorganic fiber formed body.

[0069] The first inorganic fiber formed body and the second inorganic fiber formed body preferably contain an inorganic binder. This is because by making the first inorganic fiber formed body and the second inorganic fiber formed body contain an inorganic binder, the dispersibility of the inorganic binder in the newly manufactured inorganic fiber mat by the method of the present invention is improved.

[0070] The inorganic binder can be contained in either the first inorganic fiber formed body or the second inorganic fiber formed body, or can be contained in both the first inorganic fiber formed body and the second inorganic fiber formed body. It is preferably contained in both the first inorganic fiber formed body and the second inorganic fiber formed body.

[0071] Examples of the inorganic binder include at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice, or any suitable combination of them, etc. Aluminum sol and silica sol are preferred.

[0072] The above-mentioned first inorganic fiber molded body and the above-mentioned second inorganic fiber molded body are preferably scraps. Scraps refer to the remaining parts after taking the required parts from the material. In the case of manufacturing a holding and sealing material for an exhaust gas purification device, etc., it is made by punching or cutting a large sheet-shaped inorganic fiber mat into a specified shape, so the corner parts of the sheet become scraps. By using scraps in the inorganic fiber material, the scraps can be effectively utilized without being discarded, which is thus preferable.

[0073] Figure 1 It is a top view showing a holding and sealing material for an exhaust gas purification device cut out from an inorganic fiber mat and scraps. At the manufacturing site of the holding and sealing material, in order to cut out a plurality of holding and sealing materials from a large sheet of inorganic fiber mat, as Figure 1 shown, first, the inorganic fiber mat 31 is divided into a holding and sealing material forming part 32 and scraps 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 and sealing material forming part 32 is divided into individual holding and sealing materials 34.

[0074] When cutting out the holding and sealing material forming part 32, in order to perform cutting efficiently, the number of straight parts is increased and the pattern is considered in such a way that scraps 33 are not generated as much as possible. When the holding and sealing material 34 has a concavo-convex shape, the scraps 33 may have a concavo-convex shape.

[0075] In the manufacturing method of the present invention, as the inorganic fiber material, it is more preferable to use such irregular scraps having a concavo-convex shape.

[0076] When cutting out the holding and sealing material forming part 32 from the central part of the inorganic fiber mat 31, the scraps 33 become frame-shaped. The scraps 33 can also be directly used in the manufacturing method of the present invention in a frame shape, but if cut along, for example, the longitudinal and transverse directions, various-shaped scraps 33 can be obtained.

[0077] In the manufacturing method of the present invention, the above-mentioned needle-punched mat is preferably formed by laminating thin sheets of an inorganic fiber precursor with a specified width multiple times and then firing. Such a needle-punched mat is also called a folded and laminated needle-punched mat. Figure 2A It is a schematic diagram showing a manufacturing example of a folded and laminated needle-punched mat. Figure 2B It is Figure 2A an A - A cross-sectional view of the folded and laminated needle-punched mat manufactured in Figure 2A , Figure 2B shown, before firing, the needle-punched mat 31A is formed by folding and laminating thin sheets 35 of an inorganic fiber precursor with a specified width multiple times. As Figure 2AAs shown, the thin 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 folds are not particularly limited. For example, the width can be 1000 mm or more and the number of folds can be 5 or more. At the folded-back portion 36 of the needle-punched mat 31A before firing, the proportion of inorganic fibers with long fiber lengths is high.

[0078] By using the scrap material containing such a folded-back portion in the material of the inorganic fiber mat, the inorganic fiber mat obtained by the manufacturing method of the present invention has a high surface pressure.

[0079] The above-mentioned folded and laminated needle-punched mat can be manufactured, for example, by the method described in Japanese Patent Application Laid-Open No. 2008-7933.

[0080] The manufacturing method of the inorganic fiber mat of the present invention has the following steps: a fiber-opening step of opening the first inorganic fiber formed body to obtain inorganic fibers; and a papermaking and forming step of using a slurry containing the opened inorganic fibers to perform papermaking and forming of the inorganic fiber mat. In the case of using a second inorganic fiber formed body, the fiber opening can be performed together with the first inorganic fiber formed body or separately from the first inorganic fiber formed body to obtain inorganic fibers.

[0081] As described above, when the first inorganic fiber formed body and the second inorganic fiber formed body contain an organic binder, it is preferable to perform a firing step of firing the first inorganic fiber formed body and the second inorganic fiber formed body before the fiber-opening step. The firing is performed, for example, at 700 to 1000 °C for 1 to 8 hours. When firing is performed under the above conditions, the removal of the organic binder can be carried out more surely. The preferable firing temperature is 800 to 950 °C.

[0082] The fiber opening performed in the fiber-opening step can be carried out by a single treatment of only wet fiber opening or a two-stage treatment of dry fiber opening and wet fiber opening. In the manufacturing method of the present invention, for the reason of simplicity of the process, it is preferable that the fiber-opening step only performs wet fiber opening.

[0083] Wet fiber opening can be carried out using a wet fiber-opening device such as a beater or a mixer. Wet fiber opening can be carried out by putting the first inorganic fiber formed body and, optionally, the second inorganic fiber formed body into water and stirring. In the case of using a second inorganic fiber formed body, the order of putting the first inorganic fiber formed body and the second inorganic fiber formed body is not particularly limited. It is preferable to first put the first inorganic fiber formed body into water and stir, and then put the second inorganic fiber formed body and stir; or put the first inorganic fiber formed body and the second inorganic fiber formed body into water at the same time and stir. In the manufacturing method of the present invention, in order to sufficiently open the first inorganic fiber formed body, it is preferable to first put the first inorganic fiber formed body and stir, and then put the second inorganic fiber formed body and stir further.

[0084] In the case of dry fibrillation, it is carried out before wet fibrillation. The dry fibrillation treatment can be carried out using devices such as a screen crusher Feather Mill.

[0085] It should be noted that before the fibrillation process, the first inorganic fiber formed body and the above-mentioned second inorganic fiber formed body can be pre-cut into desired sizes. This is because when the inorganic fiber formed body is pre-cut before the fibrillation process, the fibrillation process can proceed smoothly. When using scraps as the first inorganic fiber formed body and the above-mentioned second inorganic fiber formed body, the fibrillation process can also be directly carried out without further cutting.

[0086] Here, by changing the treatment conditions of wet fibrillation and dry fibrillation (such as stirring speed, stirring time, etc.), the average fiber length of the obtained inorganic fibers can be adjusted. As an example of the treatment conditions of wet fibrillation, 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.

[0087] Through such a fibrillation process, 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 investigating the bulk density.

[0088] Next, a papermaking forming process is carried out, and an inorganic fiber mat is formed by papermaking using a slurry containing the fibrillated inorganic fibers.

[0089] The preparation of the slurry can be carried out as follows, for example.

[0090] First, a liquid containing water and fibrillated inorganic fibers is prepared, and the concentration of the inorganic fibers is about 0.5 to 2.0% by weight. When adding water or fibrillated inorganic fibers to the liquid during the preparation of the slurry, it is stirred for about 20 to 120 seconds using a stirrer. Then, an organic binder of about 0.5 to 10% by weight relative to the inorganic fibers is added to the liquid and stirred for about 1 to 5 minutes. Further, an inorganic binder of about 0.5 to 3% by weight relative to the inorganic fibers is added to the liquid and stirred for about 1 to 5 minutes. Further, a coagulant of about 0.01 to 1.0% by weight relative to the inorganic fibers is added to the liquid and stirred for up to about 2 minutes to prepare the slurry.

[0091] The above-mentioned 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 desired physical properties. Here, the new inorganic fibers refer to inorganic fibers that are formed into the state of inorganic fibers for the first time and have never been used as a product.

[0092] 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 needled mat and the inorganic fibers constituting the hand-made mat.

[0093] As the composition of the new inorganic fibers, the same compositions as those exemplified for the inorganic fibers constituting the first inorganic fiber formed body and the inorganic fibers constituting the second inorganic fiber formed body can be cited. The new inorganic fibers are preferably of the same composition as the inorganic fibers constituting the first inorganic fiber formed body and the inorganic fibers constituting the second inorganic fiber formed body. This is because if the compositions of the inorganic fibers are the same, the thermal expansion coefficients of the inorganic fibers are the same, so the bonding parts between the fibers at high temperatures do not shift, and the surface pressure can be maintained.

[0094] The new inorganic fibers, the inorganic fibers constituting the first inorganic fiber formed body, and the inorganic fibers constituting the second inorganic fiber formed body are more preferably alumina-silica fibers containing 65 to 80% by weight of Al 2 O 3 This is because the resilience and heat resistance of the obtained inorganic fiber mat can be improved.

[0095] As the inorganic binder added in the preparation of the slurry, the same binder as that contained in the first inorganic fiber formed body and the second inorganic fiber formed body can be cited. In addition, as the organic binder, latex etc. are used, and as the coagulant, existing publicly known coagulants can be used.

[0096] In the manufacturing method of the present invention, it is preferable to add an inorganic binder during the preparation of the slurry. When the first inorganic fiber formed body and the second inorganic fiber formed body contain an inorganic binder, it is not necessary to newly add an inorganic binder in the hand-made forming process. Even when an inorganic binder is added, the amount can be small compared with the above-mentioned addition amount. Even when the first inorganic fiber formed body and the second inorganic fiber formed body contain an inorganic binder, an inorganic binder with the same addition amount as above can be added to the slurry. By adding an inorganic binder during the preparation of the slurry, the surface pressure of the inorganic fiber mat obtained by the manufacturing method of the present invention can be further improved.

[0097] 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 forming process 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.

[0098] In the manufacturing method of the present invention, it is preferable to add an organic binder during the preparation of the slurry. By adding the organic binder, the formability of the inorganic fiber mat obtained by the manufacturing method of the present invention is excellent.

[0099] In the manufacturing method of the present invention, it is more preferable to add an inorganic binder and an organic binder during the preparation of the slurry.

[0100] The papermaking forming of the inorganic fiber mat using the slurry can be carried out as follows, for example.

[0101] The prepared slurry is added to a former of a desired shape to form a raw material sheet, and further dewatering is performed. Usually, a filter metal mesh (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 filter metal mesh. Therefore, by using such a former, the forming and dewatering of the raw material sheet can be performed simultaneously. Additionally, if necessary, a suction pump, a vacuum pump, etc. can be used to forcibly suck the water from the lower side of the former through the filter metal mesh.

[0102] Next, the obtained raw material sheet is taken out from the former, and the raw material sheet is compressed using a press, etc. to a thickness of about 0.3 to 0.5 times, and at the same time, heating and drying are performed at a temperature of, for example, 150 to 210 °C for 5 minutes to 1 hour, whereby an inorganic fiber mat can be obtained.

[0103] The inorganic fiber mat obtained by the manufacturing method of the present invention can be cut into a desired shape and used as a holding and sealing material for an exhaust gas purification device, etc.

[0104] (Inorganic fiber mat)

[0105] The inorganic fiber mat of the present invention contains inorganic fibers from a needled mat, inorganic fibers from a papermade mat, an inorganic binder, and an organic binder. The inorganic fiber mat of the present invention is a papermade mat obtained by papermaking and forming using a slurry containing inorganic fibers from a needled mat, inorganic fibers from a papermade mat, an inorganic binder, and an organic binder.

[0106] Examples of the needled mat, papermade mat, inorganic fibers, inorganic binder, and organic binder include the same materials as those exemplified in the manufacturing method of the inorganic fiber mat of the present invention, etc.

[0107] The method for obtaining the inorganic fibers from the needled mat and the inorganic fibers from the wet-laid mat is not particularly limited. For example, the same method as the fibrillation step of the manufacturing method of the inorganic fiber mat of the present invention can be cited.

[0108] In the inorganic fiber mat of the present invention, as the inorganic binder, fired particles of the inorganic binder and unfired (a mixture of a dried inorganic binder and an organic binder) inorganic binder are preferably included. The fired particles of the inorganic binder are particles formed by firing the inorganic binder. When at least one of the needled mat and the wet-laid mat contains an inorganic binder and an organic binder and is fired to remove the organic binder from the inorganic fibers, the inorganic binder becomes glass particles or particles containing crystals and glass of the inorganic binder.

[0109] For example, when the inorganic binder is silica sol, almost no crystals are formed under the firing conditions (e.g., 700 to 1000 °C, 1 to 8 hours) in the manufacturing method of the present invention, and it becomes glass particles.

[0110] On the other hand, when the inorganic binder is alumina sol, crystals are generated by firing at 500 °C or higher, and under the firing conditions (e.g., 700 to 1000 °C, 1 to 8 hours) in the manufacturing method of the present invention, it becomes glass particles partly formed of crystalline γ-alumina.

[0111] The major axis of the fired particles of the inorganic binder is preferably 0.01 to 4 μm.

[0112] The inorganic fiber mat of the present invention preferably has an inorganic binder additionally attached separately from the inorganic binder from the needled mat and / or the inorganic binder from the above-mentioned wet-laid mat. When an inorganic binder is added to the material of the inorganic fiber mat after the above-mentioned firing, the inorganic binder is an amorphous inorganic binder that has not undergone the firing process.

[0113] The inorganic fiber mat of the present invention contains an organic binder. In the inorganic fiber mat of the present invention, it is preferable that an unfired amorphous inorganic binder and an organic binder form a mixture. The above-mentioned mixture preferably has a major axis of 5 to 20 μm.

[0114] Figure 3 is an example of an electron microscope image of the inorganic fiber mat of the present invention enlarged. As Figure 3 shown, the fired particles 42 of the inorganic binder adhere to the surface of the inorganic fibers 41. The mixture 43 of the unfired amorphous inorganic binder and the organic binder covers the contact portions between the inorganic fibers 41, the surface of the inorganic fibers 41, or adheres to the surface of the inorganic fibers 41 in a lump.

[0115] The inorganic fiber mat of the present invention contains inorganic fibers from a needled mat and inorganic fibers from a hand-sheeted mat, and thus has both resilience and winding property.

[0116] The inorganic fiber mat of the present invention can be produced, for example, by the method for producing an inorganic fiber mat of the present invention, but the production method is not particularly limited.

[0117] The following matters are disclosed in this specification.

[0118] This disclosure (1) relates to a method for producing an inorganic fiber mat, which is characterized in that it uses a first inorganic fiber formed body from a needled mat to which an organic binder is attached, and has the following steps: a fiber-opening step of opening the first inorganic fiber formed body to obtain inorganic fibers; and a hand-sheet forming step of forming an inorganic fiber mat by hand-sheeting using a slurry containing the opened inorganic fibers.

[0119] This disclosure (2) relates to the method for producing an inorganic fiber mat according to disclosure (1), wherein a second inorganic fiber formed body from a hand-sheeted mat is further used.

[0120] This disclosure (3) relates to the method for producing an inorganic fiber mat according to disclosure (2), wherein the first inorganic fiber formed body and the second inorganic fiber formed body contain an inorganic binder.

[0121] This disclosure (4) relates to the method for producing an inorganic fiber mat according to disclosure (2) or (3), wherein the first inorganic fiber formed body and the second inorganic fiber formed body are scraps.

[0122] This disclosure (5) relates to the method for producing an inorganic fiber mat according to any one of disclosures (1) to (4), wherein the average fiber length of the inorganic fibers constituting the needled mat is 3.0 to 100 mm.

[0123] This disclosure (6) relates to the method for producing an inorganic fiber mat according to any one of disclosures (1) to (5), wherein the fiber opening is performed only by wet fiber opening.

[0124] This disclosure (7) relates to the method for producing an inorganic fiber mat according to any one of disclosures (1) to (6), wherein the needled mat is formed by laminating thin sheets of an inorganic fiber precursor folded multiple times with a specified width and then firing.

[0125] This disclosure (8) relates to the method for producing an inorganic fiber mat according to any one of disclosures (2) to (4), wherein the first inorganic fiber formed body and the second inorganic fiber formed body are cut before the fiber-opening step.

[0126] The present disclosure (9) relates to a method for manufacturing an inorganic fiber mat according to any one of the present disclosures (1) to (8), wherein the slurry further contains virgin inorganic fibers, the virgin inorganic fibers have the same composition as the fibrillated inorganic fibers, and are alumina-silica fibers containing 60 to 80% by weight of Al 2 O 3 oxide.

[0127] The present disclosure (10) relates to a method for manufacturing an inorganic fiber mat according to the present disclosure (3), wherein a firing step of firing the first inorganic fiber compact and the second inorganic fiber compact is performed before the fibrillation step.

[0128] The present disclosure (11) relates to a method for manufacturing an inorganic fiber mat according to the present disclosure (10), wherein the firing is performed at 700 to 1000 °C for 1 to 8 hours.

[0129] The present disclosure (12) relates to a method for manufacturing an inorganic fiber mat according to any one of the present disclosures (1) to (11), wherein an inorganic binder and an organic binder are added to the slurry.

[0130] The present disclosure (13) relates to a method for manufacturing an inorganic fiber mat according to the present disclosure (12), wherein the inorganic fiber mat formed by the above-mentioned papermaking forming step is heated and dried at a temperature of 150 to 210 °C for 5 minutes to 1 hour.

[0131] The present disclosure (14) relates to an inorganic fiber mat, which comprises inorganic fibers from a needle-punched mat, inorganic fibers from a papermaking mat, an inorganic binder, and an organic binder.

[0132] The present disclosure (15) relates to the inorganic fiber mat according to the present disclosure (14), which comprises fired particles of an inorganic binder, and a mixture of an unfired inorganic binder and an organic binder.

[0133] The present disclosure (16) relates to the inorganic fiber mat according to the present disclosure (15), wherein the major axis of the fired particles of the inorganic binder is 0.01 to 4 μm, and the major axis of the mixture is 5 to 20 μm.

[0134] The present disclosure (17) relates to the inorganic fiber mat according to the present disclosure (15) or (16), wherein the fired particles of the inorganic binder are glass particles of the inorganic binder and / or particles containing crystals and glass of the inorganic binder.

[0135] The present disclosure (18) relates to the inorganic fiber mat according to any one of the present disclosures (15) to (17), wherein fired particles of the inorganic binder adhere to the surface of the inorganic fiber, and the mixture covers the contact portions between the inorganic fibers and the surface of the inorganic fiber, or adheres to the surface of the inorganic fiber in a lump.

[0136] Symbol description

[0137] 31 Mat material of inorganic fiber

[0138] 31A Needled mat before firing

[0139] 31a Outer peripheral end

[0140] 32 Portion for forming holding sealant

[0141] 33 Scrap

[0142] 34 Holding sealant

[0143] 35 Thin sheet of inorganic fiber precursor

[0144] 36 Folded-back portion

[0145] 41 Inorganic fiber

[0146] 42 Fired particles of inorganic binder

[0147] 43 Mixture of amorphous inorganic binder and organic binder

Claims

1. A method for manufacturing an inorganic fiber mat, characterized in that, the manufacturing method uses a first inorganic fiber formed body from a needled mat to which an organic binder is attached, and has the following steps: A fiber opening step of opening the first inorganic fiber formed body to obtain inorganic fibers; and A papermaking forming step of forming an inorganic fiber mat by papermaking using a slurry containing the opened inorganic fibers.

2. The method for manufacturing an inorganic fiber mat according to claim 1, wherein, a second inorganic fiber formed body from a papermaking mat is further used.

3. The method for manufacturing an inorganic fiber mat according to claim 2, wherein, the first inorganic fiber formed body and the second inorganic fiber formed body contain an inorganic binder.

4. The method for manufacturing an inorganic fiber mat according to claim 2 or 3, wherein, the first inorganic fiber formed body and the second inorganic fiber formed body are scraps.

5. The method for manufacturing an inorganic fiber mat according to claim 1 or 2, wherein, the average fiber length of the inorganic fibers constituting the needled mat is 3.0 mm to 100 mm.

6. The method for manufacturing an inorganic fiber mat according to claim 1 or 2, wherein, the fiber opening is only performed by wet fiber opening.

7. The method for manufacturing an inorganic fiber mat according to claim 1 or 2, wherein, the needled mat is formed by laminating thin sheets of an inorganic fiber precursor folded multiple times with a specified width and then firing.

8. The method for manufacturing an inorganic fiber mat according to claim 2 or 3, wherein, before the fiber opening step, the first inorganic fiber formed body and the second inorganic fiber formed body are cut.

9. The method for manufacturing an inorganic fiber mat according to claim 1 or 2, wherein, the slurry further contains new inorganic fibers, The new inorganic fiber and the fibrillated inorganic fiber have the same composition and are alumina-silica fibers containing 60% to 80% by weight of Al 2 O 3 .

10. The method for manufacturing an inorganic fiber mat according to claim 3, wherein, a firing step of firing the first inorganic fiber formed body and the second inorganic fiber formed body is performed before the fiber opening step.

11. The method for manufacturing an inorganic fiber mat according to claim 10, wherein, the firing is performed at 700 °C to 1000 °C for 1 hour to 8 hours.

12. The method for manufacturing an inorganic fiber mat according to claim 1 or 2, wherein, an inorganic binder and an organic binder are added to the slurry.

13. The method for manufacturing an inorganic fiber mat according to claim 12, wherein, the inorganic fiber mat formed by papermaking through the papermaking forming step is heated and dried at a temperature of 150 °C to 210 °C for 5 minutes to 1 hour.

14. An inorganic fiber mat, which comprises inorganic fibers from a needled mat, inorganic fibers from a papermaking mat, fired particles of an inorganic binder, and a mixture of an unfired inorganic binder and an organic binder.

15. The inorganic fiber mat according to claim 14, wherein, the major axis of the fired particles of the inorganic binder is 0.01 μm to 4 μm, and the major axis of the mixture is 5 μm to 20 μm.

16. The inorganic fiber mat according to claim 14 or 15, wherein, The fired particles of the inorganic binder are glass particles of the inorganic binder and / or particles containing crystals and glass of the inorganic binder.

17. The inorganic fiber mat according to claim 14 or 15, wherein, the fired particles of the inorganic binder adhere to the surfaces of the inorganic fibers from the needle-punched mat and the inorganic fibers from the wet-laid mat, and the mixture covers the contact portions and surfaces of the inorganic fibers from the needle-punched mat and the inorganic fibers from the wet-laid mat with each other, or adheres to the surfaces of the inorganic fibers from the needle-punched mat and the inorganic fibers from the wet-laid mat in a lump.

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