Papermaking mats and papermaking mats with laminated sheets

Abstract

To provide a papermaking mat that has high moldability and retains sufficiently high retention even after the organic components have decomposed. The papermaking mat of the present invention is a papermaking mat comprising a plurality of inorganic fibers, a plurality of organic fibers, an organic binder, and an inorganic binder, wherein the organic fibers comprise a main fiber and a plurality of fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber, and a first mixture of the organic fibers, the organic binder, and the inorganic binder is present on the surface of the inorganic fibers.

Description

[Technical Field]

[0001] This invention relates to papermaking mats and papermaking mats with laminated sheets. [Background technology]

[0002] Exhaust gases emitted from internal combustion engines such as diesel engines contain particulate matter (PM), and in recent years, the harm that this PM poses to the environment and human health has become a problem. Furthermore, since exhaust gases also contain harmful gas components such as CO, HC, and NOx, there are concerns about the effects of these harmful gas components on the environment and human health.

[0003] Therefore, various exhaust gas purification devices have been proposed that collect PM in exhaust gas and purify harmful gas components, and consist of an exhaust gas treatment body made of porous ceramic such as silicon carbide or cordierite, a casing that houses the exhaust gas treatment body, and a mat material placed between the exhaust gas treatment body and the casing. The main purposes of this mat material are to prevent the exhaust gas treatment body from being damaged by contact with the casing that surrounds its outer circumference due to vibrations and shocks caused by the driving of the vehicle, and to prevent exhaust gas from leaking from between the exhaust gas treatment body and the casing.

[0004] As such a mat material, paper-formed mats made by papermaking inorganic fibers are known. In papermaking mats, organic fibers and organic binders are used to improve moldability.

[0005] For example, Patent Document 1 discloses an attachment mat containing inorganic fibers and organic nanofibrillated fibers, and further discloses the use of the mat in an exhaust gas purification device. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent No. 8765069 [Overview of the project] [Problems that the invention aims to solve]

[0007] The mat described in Patent Document 1 contains organic nanofibrillated fibers, which improves moldability. However, to fully obtain this effect, a certain amount of organic nanofibrillated fibers was necessary. In other words, the mat described in Patent Document 1 had a high content of organic components. When the mat described in Patent Document 1 is placed in an exhaust gas purification device to purify the exhaust gas, there was a problem that the organic components decomposed due to the heat of the exhaust gas, generating a large amount of gas. In addition, there was a problem that the mat's holding power decreased as the organic components decomposed.

[0008] This invention was made to solve the above problems, and the object of this invention is to provide a papermaking mat that has high moldability and sufficient holding power even after the organic components have decomposed. [Means for solving the problem]

[0009] As a result of diligent research, the inventors of the present invention discovered that the moldability of papermaking mats can be improved by using organic fibers that include main fibers and fine fibers that are subdivided by fluffing from the surface of the main fibers, thus completing the present invention.

[0010] The papermaking mat of the present invention is a papermaking mat comprising a plurality of inorganic fibers, a plurality of organic fibers, an organic binder, and an inorganic binder, wherein the organic fibers comprise a main fiber and a plurality of fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber, and a first mixture of the organic fibers, the organic binder, and the inorganic binder is present on the surface of the inorganic fibers.

[0011] In the papermaking mat of the present invention, the organic fibers include main fibers and fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fibers. When organic fibers have this shape, the fine fibers tend to cling to the surface of inorganic fibers through organic and inorganic binders. As a result, the adhesion between organic and inorganic fibers improves. Therefore, even with a low organic fiber content, the moldability of the papermaking mat tends to improve. Furthermore, the bending strength of the papermaking mat improves. Furthermore, since the amount of organic fibers contained in the papermaking mat can be reduced, even if the organic components decompose due to the heat of the exhaust gas, the amount of gas generated can be reduced, and the holding power of the papermaking mat can be sufficiently high.

[0012] In the papermaking mat of the present invention, the first mixture may contain the main fibers, the fine fibers, the organic binder, and the inorganic binder. Alternatively, the first mixture may contain the fine fibers, the organic binder, and the inorganic binder. Regardless of the embodiment of the first mixture, it is possible to improve the adhesion between organic fibers and inorganic fibers.

[0013] In the papermaking mat of the present invention, it is preferable that a second mixture of the organic fiber, the organic binder, and the inorganic binder is present at the intersection of the inorganic fibers. When the above-mentioned second mixture is present at the intersections of inorganic fibers, the inorganic fibers become less likely to shift from one another, further improving the moldability of the papermaking mat.

[0014] In the papermaking mat of the present invention, the second mixture may contain the main fibers, the fine fibers, the organic binder, and the inorganic binder. Alternatively, the second mixture may contain the fine fibers, the organic binder, and the inorganic binder. Regardless of the form of the second mixture, the effect of making it difficult for inorganic fibers to shift can be obtained.

[0015] In the forming mat of the present invention, it is preferable that the plurality of fine fibers formed on one organic fiber are in contact with the plurality of inorganic fibers. Fine fibers are thin and easily entangled with inorganic fibers. Therefore, the plurality of fine fibers formed on one organic fiber can be entangled with the plurality of inorganic fibers. Moreover, when the fine fibers formed on one organic fiber are in contact with the plurality of inorganic fibers, the formability of the forming mat is improved.

[0016] In the forming mat of the present invention, it is preferable that the inorganic fibers include at least one selected from the group consisting of alumina fibers, refractory ceramic fibers (RCF), glass fibers, mullite fibers, silica fibers, basalt fibers, and bio-soluble fibers. These inorganic fibers are suitable for the forming mat of the present invention.

[0017] In the forming mat of the present invention, it is preferable that the inorganic fibers include first inorganic fibers having an average fiber diameter of 3.0 to 20.0 μm and second inorganic fibers having an average fiber diameter of 0.1 to 15.0 μm. Since the first inorganic fibers are long, they are easily entangled with other inorganic fibers and organic fibers. Therefore, the formability of the forming mat is improved. Since the second inorganic fibers are short, they are less likely to receive stress and are not easily broken. Therefore, even when the forming mat receives stress, it is easy to maintain its shape. That is, the bending strength of the forming mat is improved.

[0018] In the forming mat of the present invention, it is preferable that the organic fibers include at least one selected from the group consisting of cellulose fibers, acrylic fibers, aramid fibers, PVA fibers, polyamide fibers, polyester fibers, polyethylene fibers, nylon fibers, polyurethane fibers, polyvinyl chloride fibers, and polylactic acid fibers. These organic fibers are suitable for the forming mat of the present invention.

[0019] In the forming mat of the present invention, it is preferable that the average fiber diameter of the organic fibers is 1 to 10 μm. When organic fibers have this shape, they become stronger, which improves the moldability of the papermaking mat.

[0020] In the papermaking mat of the present invention, it is preferable that the average fiber diameter of the above-mentioned fine fibers is 0.01 to 1 μm. When the average fiber diameter of the microfibers is within the above range, the microfibers tend to cling more easily to the surface of the inorganic fibers.

[0021] In the papermaking mat of the present invention, it is preferable that the above-mentioned organic binder includes at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, polyvinyl alcohol, styrene resin, and epoxy resin. In the papermaking mat of the present invention, the inorganic binder preferably includes at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice. These organic and inorganic binders are suitable for the papermaking mat of the present invention.

[0022] In the papermaking mat of the present invention, it is preferable that the content of organic components is 5% by weight or less. When the organic component content is 5% by weight or less, even if the organic component in the papermaking mat of the present invention decomposes due to the heat of the exhaust gas, the amount of gas generated is small. Furthermore, because the weight ratio of organic components in the papermaking mat is low, even if the organic component decomposes due to the heat of the exhaust gas, the holding power of the papermaking mat does not decrease easily. Furthermore, since the papermaking mat of the present invention contains organic fibers having the above-mentioned characteristics, it has sufficient moldability even with such a low content of organic components.

[0023] In the papermaking mat of the present invention, the ratio of the total weight of the organic fibers, organic binder, and inorganic binder to the weight of the inorganic fibers (([Weight of organic fibers] + [Weight of organic binder] + [Weight of inorganic binder]) / [Weight of inorganic fibers]) is preferably 0.01 to 0.1. The fact that the above ratio falls within this range means that the inorganic fiber content is high, and relatively, the organic components contained in the papermaking mat are low. Therefore, even if the mat material of the present invention is placed in an exhaust gas purification device and the organic components contained in the papermaking mat are decomposed by the heat of the exhaust gas, the amount of gas generated is small.

[0024] In the papermaking mat of the present invention, the ratio of the weight of the organic fibers to the total weight of the organic fibers, organic binder, and inorganic binder ([weight of organic fibers] / ([weight of organic fibers]+[weight of organic binder]+[weight of inorganic binder])) is preferably 0.01 to 0.9. The fact that the above ratio falls within this range means that the organic fiber content is low, and therefore the amount of organic components in the papermaking mat is also sufficiently low. Therefore, even if the mat material of the present invention is placed in an exhaust gas purification device and the organic components contained in the papermaking mat are decomposed by the heat of the exhaust gas, the amount of gas generated is small.

[0025] In the papermaking mat of the present invention, if the thickness of the papermaking mat is T1, and the thickness of the papermaking mat after heating it at 50°C and 80% humidity for 24 hours is T2, then it is preferable that the ratio of T2 to T1 (T2 / T1) is 1.0 to 1.3. For example, when inorganic fibers are bonded together with an organic binder, heating the papermaking mat causes the organic binder to soften, making the inorganic fibers more likely to release. Therefore, the above ratio tends to exceed 1.3. Such papermaking mats can be said to have poor moldability. However, because the papermaking mat of the present invention contains organic fibers, the inorganic fibers are less likely to be released even when the papermaking mat is heated. Therefore, the above ratio tends to be 1.3 or less. Consequently, such a papermaking mat can be said to have high moldability.

[0026] The papermaking mat of the present invention is preferably used as the holding material in an exhaust gas purification device comprising a metal casing, an exhaust gas treatment body housed in the metal casing, and a holding material disposed between the metal casing and the exhaust gas treatment body. As described above, since the papermaking mat of the present invention has a low weight ratio of organic components, even if the organic components decompose due to the heat of exhaust gas, the holding power of the papermaking mat does not easily decrease. Therefore, the papermaking mat of the present invention is suitable as a holding material for exhaust gas purification devices.

[0027] The laminated sheet-attached papermaking mat of the present invention is characterized by comprising the papermaking mat of the present invention described above, and a laminated sheet material consisting of a plurality of fibers arranged on at least one main surface of the papermaking mat described above. Furthermore, in the laminated sheet-attached papermaking mat of the present invention, it is preferable that the laminated sheet material is a web-like body comprising a fiber bundle for the laminated sheet material formed by the entanglement of multiple fibers, and single fibers for the laminated sheet material.

[0028] The laminated sheet-attached papermaking mat of the present invention will be wrapped around an exhaust gas treatment body and placed in an exhaust gas purification device. At this time, stress is applied to the main surface of the papermaking mat, making it more prone to cracking. However, if the laminated sheet described above is placed on the main surface of the papermaking mat, such cracking can be prevented.

[0029] The laminated sheet-attached papermaking mat of the present invention preferably has an organic component content of 8% by weight or less. The laminated sheet-attached papermaking mat of the present invention will be placed in an exhaust gas purification device. If the organic component content of the laminated sheet-attached papermaking mat of the present invention is 8% by weight or less, even if exhaust gas reaches the exhaust gas purification device on which the laminated sheet-attached papermaking mat of the present invention is placed and the organic component is decomposed by the heat of the exhaust gas, the amount of gas generated will be small. Therefore, the generation of odor associated with gas generation can be suppressed. [Effects of the Invention]

[0030] According to the present invention, it is possible to provide a papermaking mat that has high moldability and retains sufficiently high retention even after the organic components have decomposed. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 is a schematic perspective view showing an example of the papermaking mat of the present invention. [Figure 2] Figure 2 is a schematic diagram of an example of organic fibers included in the papermaking mat of the present invention. [Figure 3] Figure 3 is a schematic enlarged view showing an example of a state in which multiple inorganic fibers are bonded to each other in the papermaking mat of the present invention. [Figure 4] Figure 4 is a schematic diagram of an example of a fiber bundle formed by the twisting and entanglement of inorganic fibers contained in the papermaking mat of the present invention. [Figure 5] Figure 5 is a schematic cross-sectional view showing an example of the exhaust gas purification device of the present invention. [Figure 6] Figure 6 is a schematic perspective view showing an example of a laminated sheet-attached papermaking mat according to the present invention. [Figure 7] Figure 7 is a schematic enlarged plan view showing an example of the laminated sheet shown in Figure 6. [Figure 8] Figure 8 is a magnified photograph of the inorganic fibers constituting the papermaking mat according to Example 1. [Figure 9] Figure 9 is a magnified photograph of the inorganic fibers constituting the papermaking mat according to Example 2. [Modes for carrying out the invention]

[0032] The papermaking mat of the present invention will be described in detail below. However, the present invention is not limited to the following configuration and can be modified and applied as appropriate without changing the gist of the invention. Furthermore, a combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0033] (First Embodiment) A papermaking mat according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic perspective view showing an example of the papermaking mat of the present invention. As shown in Figure 1, the papermaking mat 10 is a rectangular papermaking mat in plan view, made of inorganic fibers. The papermaking mat 10 has a rectangular shape in plan view, with a protrusion 11a at one end 11 and a recess 12a at the other end 12.

[0034] As will be explained in more detail later, the papermaking mat 10 is wrapped around the exhaust gas treatment body and placed in the exhaust gas purification device. The convex portion 11a and the concave portion 12a are shaped to fit together perfectly when the papermaking mat 10 is wrapped around the exhaust gas treatment body. The presence of such protrusions 11a and recesses 12a improves the sealing performance when the papermaking mat 10 is placed in the exhaust gas purification device described later.

[0035] The papermaking mat 10 includes multiple inorganic fibers, multiple organic fibers, an organic binder, and an inorganic binder.

[0036] Furthermore, in the papermaking mat 10, the organic fibers include main fibers and a plurality of fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fibers. These organic fibers will be explained using diagrams.

[0037] Figure 2 is a schematic diagram of an example of organic fibers included in the papermaking mat of the present invention. The organic fiber 30 shown in Figure 2 includes a main fiber 31 and a plurality of fine fibers 32 that are frayed and subdivided from at least a portion of the entire surface of the main fiber 31. The fine fibers 32 may be subdivided by fuzzing from the side of the main fiber 31, or they may be subdivided by fuzzing from the end face of the main fiber 31.

[0038] When organic fibers have this shape, the fine fibers tend to cling to the surface of inorganic fibers through organic and inorganic binders. As a result, the adhesion between organic and inorganic fibers improves. Therefore, even with a low organic fiber content, the moldability of the papermaking mat tends to improve. Furthermore, the bending strength of the papermaking mat improves. Furthermore, since the amount of organic fibers contained in the papermaking mat can be reduced, even if the organic components decompose due to the heat of the exhaust gas, the amount of gas generated can be reduced, and the holding power of the papermaking mat can be sufficiently high.

[0039] Furthermore, in the papermaking mat 10, a first mixture of organic fibers, an organic binder, and an inorganic binder is present on the surface of the inorganic fibers. This embodiment will be explained using drawings.

[0040] Figure 3 is a schematic enlarged view showing an example of a state in which multiple inorganic fibers are bonded to each other in the papermaking mat of the present invention. As shown in Figure 3, in the papermaking mat 10, multiple inorganic fibers 20 intersect and are in contact with each other. Furthermore, a first mixture 41, which is a mixture of organic fibers, an organic binder, and an inorganic binder, is present on the surface of the inorganic fibers 20. In addition, a second mixture 42, which is a mixture of organic fibers, an organic binder, and an inorganic binder, is present at the intersections of the inorganic fibers 20. For the sake of clarity, in this specification, the first mixture 41 and the second mixture 42 are described separately, but they are mixtures with the same composition. The first mixture 41 improves the moldability of the papermaking mat 10 by bonding the inorganic fibers 20 together. When the second mixture 42 is present at the intersections of the inorganic fibers 20, the inorganic fibers 20 become less likely to shift from one another, further improving the moldability of the papermaking mat 10.

[0041] In the papermaking mat 10, the first mixture 41 may contain main fibers, fine fibers, an organic binder, and an inorganic binder. Alternatively, the first mixture 41 may contain fine fibers, an organic binder, and an inorganic binder. Regardless of the embodiment of the first mixture, it is possible to improve the adhesion between organic fibers and inorganic fibers.

[0042] In the papermaking mat 10, the second mixture 42 may contain main fibers, fine fibers, an organic binder, and an inorganic binder. Alternatively, the second mixture may contain fine fibers, an organic binder, and an inorganic binder. Regardless of the embodiment of the second mixture 42, the effect of making it difficult for inorganic fibers to shift can be obtained.

[0043] In the papermaking mat 10, it is preferable that multiple fine fibers formed on a single organic fiber 30 are in contact with multiple inorganic fibers 20. The microfibers are thin and easily entangled with the inorganic fibers 20. Therefore, multiple microfibers formed on a single organic fiber 30 can become entangled with multiple inorganic fibers 20. Furthermore, when the fine fibers formed on a single organic fiber 30 are in contact with multiple inorganic fibers 20, the moldability of the papermaking mat is improved.

[0044] In the papermaking mat 10, the content of organic components is preferably 5% by weight or less, and more preferably 0.5 to 4.5% by weight. As will be explained in more detail later, the papermaking mat 10 will be placed in the exhaust gas purification system. In the papermaking mat 10, if the organic component content is 5% by weight or less, even if the exhaust gas reaches the exhaust gas purification device and the organic component in the papermaking mat 10 decomposes due to the heat of the exhaust gas, the amount of gas generated will be small. Furthermore, because the weight ratio of organic components in the papermaking mat 10 is low, even if the organic component decomposes due to the heat of the exhaust gas, the holding power of the papermaking mat 10 is less likely to decrease.

[0045] In this specification, the "organic component content (by weight) of the papermaking mat" is calculated as follows: First, measure the weight W1 of the papermaking mat. Next, the papermaking mat is heated at 600°C for 1 hour to decompose the organic components. Then, the weight W2 of the papermaking mat after heating is measured. The organic component content (by weight) of the papermaking mat is calculated using the following formula (1). [Amount of organic components in the papermaking mat (weight %)] = (W1 - W2) / W1 × 100 ... (1)

[0046] In the papermaking mat 10, the ratio of the total weight of organic fibers, organic binders, and inorganic binders to the weight of inorganic fibers (([weight of organic fibers] + [weight of organic binders] + [weight of inorganic binders]) / [weight of inorganic fibers]) is preferably 0.01 to 0.1, and more preferably 0.05 to 0.09. The fact that the above ratio falls within this range means that the inorganic fiber content is high, and relatively, the organic components contained in the papermaking mat 10 are low. Therefore, even if the papermaking mat 10 is placed in an exhaust gas purification device and the organic components contained in the papermaking mat 10 are decomposed by the heat of the exhaust gas, the amount of gas generated is small.

[0047] In the papermaking mat 10, the ratio of the weight of organic fibers to the total weight of organic fibers, organic binders, and inorganic binders ([weight of organic fibers] / ([weight of organic fibers]+[weight of organic binders]+[weight of inorganic binders])) is preferably 0.01 to 0.9, and more preferably 0.05 to 0.8. The fact that the above ratio falls within this range means that the organic fiber content is low, and therefore the amount of organic components in the papermaking mat 10 is also sufficiently low. Therefore, even if the papermaking mat 10 is placed in an exhaust gas purification device and the organic components contained in the papermaking mat 10 are decomposed by the heat of the exhaust gas, the amount of gas generated is small.

[0048] The following describes preferred configurations of each component of the papermaking mat 10.

[0049] (Inorganic fibers) The inorganic fibers constituting the papermaking mat 10 preferably include one or more types of fiber species. For inorganic fibers, it is preferable to select the fiber type according to the function required for the papermaking mat 10. In particular, if the product contains inorganic fibers of two or more different fiber types, the resulting paper-making mat 10 will exhibit the characteristics of each fiber.

[0050] The inorganic fiber is preferably made up of at least one selected from the group consisting of alumina fiber, refractory ceramic fiber (RCF), glass fiber, mullite fiber, silica fiber, basalt fiber, and biosoluble fiber. When the papermaking mat 10 is made of these inorganic fibers, its heat resistance becomes sufficiently high.

[0051] The inorganic fibers 20 constituting the papermaking mat 10 preferably have an average fiber diameter of 0.1 to 50.0 μm and an average fiber length of 100 to 100,000 μm.

[0052] In the papermaking mat 10, it is preferable that the inorganic fibers include first inorganic fibers with an average fiber diameter of 3.0 to 20.0 μm and second inorganic fibers with an average fiber diameter of 0.1 to 15.0 μm. The first inorganic fiber is thick, so it has high strength and is less prone to breaking. Therefore, even if the papermaking mat 10 is subjected to stress, it is easier to maintain its shape. In other words, the bending strength of the papermaking mat 10 is improved. Because the second inorganic fiber is thin, it easily becomes entangled with other inorganic and organic fibers. As a result, the moldability of the papermaking mat 10 is improved.

[0053] The first inorganic fiber is preferably made of alumina fiber, and the second inorganic fiber is preferably made of a fiber other than alumina fiber (for example, refractory ceramic fiber).

[0054] In the papermaking mat 10, the inorganic fiber content is preferably 95.0 to 99.8% by weight, and more preferably 96.5 to 99.5% by weight. When the inorganic fiber content is within the above range, the bulk density of the papermaking mat 10 becomes sufficiently high, making gas leakage less likely when the papermaking mat 10 is placed in the exhaust gas purification device.

[0055] The papermaking mat 10 may contain fiber bundles formed by the entanglement of inorganic fibers in a twisted manner. This type of fiber bundle will be explained using diagrams.

[0056] Figure 4 is a schematic diagram of an example of a fiber bundle formed by the twisting and entanglement of inorganic fibers contained in the papermaking mat of the present invention. The fiber bundle 50 shown in Figure 4 consists of multiple inorganic fibers 20 that are intertwined in a twisted manner. Furthermore, the fiber bundle 50 is in a crimped state. However, in the papermaking mat of the present invention, the fiber bundle does not have to be in a crimped state.

[0057] In the fiber bundle 50, the inorganic fibers 20 are intertwined in a twisted manner and support each other, making them resistant to deformation under pressure. Therefore, when pressure is applied to the papermaking mat 10, the fiber bundle 50 acts as a core material, mitigating the pressure on the inorganic fibers 20 that do not constitute the fiber bundle 50. Consequently, it is possible to prevent the inorganic fibers 20 that do not constitute the fiber bundle 50 from breaking due to pressure. As a result, the surface pressure of the papermaking mat 10 increases. In particular, when the fiber bundle 50 is in a crimped state, this effect is preferably exhibited, and the surface pressure of the papermaking mat 10 becomes even higher.

[0058] The fiber bundle 50 shown in Figure 4 has a trace length L of the fiber bundle 50 measured using the following tracing length measurement method. t It is preferable that the length of the fiber bundle 50 is longer than the length L of the fiber bundle, more preferably 0.1 mm or more longer, and even more preferably 0.2 to 0.6 mm longer.

[0059] (Method for measuring tracing length) The fiber bundle 50 is placed on a flat surface. Next, looking at the stationary fiber bundle 50 from above, trace along the fiber bundle 50 from one end P1 to the other end P2, and measure the distance L traced. t Let this be defined as the "tracing length of the fiber bundle".

[0060] Tracing length L of fiber bundle 50 t If the length of the fiber bundle 50 is longer than the length L of the fiber bundle 50, the elasticity of the fiber bundle 50 increases, and the surface pressure of the papermaking mat 10 improves.

[0061] Preferably, the papermaking mat 10 includes a crimped fiber bundle 50 such that, when measuring the "tracing length of the crimped fiber bundle," the fiber bundle 50 can be traced so as to cross the line segment S connecting end P1 and end P2 two or more times. In this state, the degree of crimp in the fiber bundle 50 is favorable, the elasticity of the fiber bundle 50 is favorably increased, and the surface pressure of the papermaking mat 10 is improved.

[0062] In the papermaking mat 10, the tracing length L of the fiber bundle 50 is relative to the length L of the fiber bundle 50. t The ratio of L t It is preferable that / L = 1.1 to 1.6.

[0063] The bulk density of the papermaking mat 10 is 0.05~0.30 g / cm³. 3 It is preferable that this be the case. The bulk density of papermaking mat 10 is 0.05 g / cm³. 3 If the value is less than the required level, the inorganic fibers will not intertwine well and will easily peel off, making it difficult to maintain the desired shape of the papermaking mat. The bulk density of papermaking mat 10 is 0.30 g / cm³. 3 Beyond a certain point, the papermaking mat becomes hard, its ability to be wrapped decreases, and it becomes more prone to tearing.

[0064] (Organic fibers) The organic fibers constituting the papermaking mat 10 preferably include at least one selected from the group consisting of cellulose fibers, acrylic fibers, aramid fibers, PVA fibers, polyamide fibers, polyester fibers, polyethylene fibers, nylon fibers, polyurethane fibers, polyclar fibers, and polylactic acid fibers. These organic fibers are suitable for improving the moldability of the papermaking mat of the present invention.

[0065] In the papermaking mat 10, the average fiber length of the organic fibers is preferably 100 μm or more. When the average fiber length of the organic fibers is within this range, the organic fibers and inorganic fibers become more easily intertwined, improving the moldability of the papermaking mat 10.

[0066] In the papermaking mat 10, the average fiber diameter of the organic fibers is preferably 1.0 to 10.0 μm, and more preferably 2.0 to 10.0 μm. When organic fibers have this shape, they become stronger, and the moldability of the papermaking mat 10 is improved. If the average fiber diameter of the organic fibers is less than 1 μm, the organic fibers become weaker, making it difficult to improve the moldability of the papermaking mat. When the average fiber diameter of organic fibers exceeds 10 μm, organic fibers and inorganic fibers become less likely to intertwine.

[0067] In the papermaking mat 10, the content of organic fibers is preferably 4.5% by weight or less, and more preferably 1.0 to 4.0% by weight. If the organic fiber content is within the above range, the amount of organic components contained in the papermaking mat can be reduced.

[0068] The organic fiber content in the papermaking mat 10 can be calculated by measuring the weight of the papermaking mat 10 before and after heating to thermally decompose the organic fibers. In addition, the papermaking mat of the present invention may contain organic binders as organic components in addition to organic fibers. In this case, when measuring the content of organic fibers only, the organic fiber content can be measured based on the weight change when the papermaking mat of the present invention is heated, by utilizing the difference between the thermal decomposition temperature of the organic fibers and the thermal decomposition temperature of the organic binder.

[0069] In the papermaking mat 10, the average fiber diameter of the fine fibers formed on the organic fibers is preferably 0.01 to 1 μm, and more preferably 0.05 to 0.8 μm. When the average fiber diameter of the microfibers is within the above range, the microfibers tend to cling more easily to the surface of the inorganic fibers.

[0070] In the papermaking mat of the present invention, when the organic fibers, including main fibers and fine fibers, are left to stand and observed from above, it is preferable that the area of ​​the outline of the main fibers is 10% or more of the area of ​​the region formed by connecting the tips of the fine fibers.

[0071] (Organic binder) In the papermaking mat 10, the glass transition temperature Tg of the organic binder is preferably 5°C or lower, and more preferably -35 to 5°C. If the glass transition temperature (Tg) of the organic binder is 5°C or lower, it is possible to create a papermaking mat with high strength of the organic binder film formed by the organic binder, while also having high film elongation and excellent flexibility. Furthermore, when wrapping the paper-formed mat 10 around the exhaust gas treatment body, the mat is less likely to tear. In addition, because the organic binder coating does not become too hard, it has the effect of binding the inorganic fibers together when they break, thereby suppressing the scattering of inorganic fibers. Organic binders with a glass transition temperature (Tg) below -35°C are expensive, resulting in higher manufacturing costs. If the glass transition temperature (Tg) of the organic binder exceeds 5°C, the flexibility of the papermaking mat may decrease, resulting in a reduced elongation at break.

[0072] In the papermaking mat 10, it is preferable that the organic binder includes at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, polyvinyl alcohol, styrene resin, and epoxy resin.

[0073] These organic binders are suitable for bonding inorganic fibers together and maintaining the shape of the papermaking mat.

[0074] In the papermaking mat 10, the content of the organic binder is preferably 0.1 to 3.0% by weight.

[0075] (Inorganic binder) In the papermaking mat 10, it is preferable that the inorganic binder includes at least one of the following: alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice.

[0076] These inorganic binders are suitable for bonding inorganic fibers together and maintaining the shape of the papermaking mat.

[0077] In the papermaking mat 10, the inorganic binder content is preferably 0.1 to 5.0% by weight.

[0078] In the papermaking mat 10, the ratio of the average fiber diameter of organic fibers to the average fiber diameter of inorganic fibers ([average fiber diameter of organic fibers] / [average fiber diameter of inorganic fibers]) is preferably 0.1 to 1.5, and more preferably 0.3 to 1.2. When the above ratio is within this range, inorganic and organic fibers become more easily intertwined, which improves the moldability of the papermaking mat. Furthermore, improved dispersibility of organic and inorganic fibers leads to a more uniform structure of the papermaking mat, resulting in improved retention.

[0079] In the papermaking mat 10, if the thickness of the papermaking mat 10 is T1, and the thickness of the papermaking mat 10 after heating it at 50°C and 80% humidity for 24 hours is T2, then the ratio of T2 to T1 (T2 / T1) is preferably 1.0 to 1.3, and more preferably 1.05 to 1.25. For example, when inorganic fibers are bonded together with an organic binder, heating the papermaking mat causes the organic binder to soften, making the inorganic fibers more likely to release. Therefore, the above ratio tends to exceed 1.3. Such papermaking mats can be said to have poor moldability. However, since the papermaking mat 10 contains organic fibers, the inorganic fibers are less likely to be released even when the papermaking mat 10 is heated. Therefore, the above ratio tends to be 1.3 or less. Consequently, such a papermaking mat 10 can be said to have high moldability.

[0080] Next, the method for producing the papermaking mat of the present invention will be described.

[0081] [Opening process] In the fiber opening process, water is added to the inorganic fibers before opening to open them and prepare an inorganic fiber dispersion.

[0082] The unopened inorganic fibers may be produced by conventionally known methods or may be commercially available. Furthermore, the unopened inorganic fibers may be derived from needle mats or from papermaking mats. Examples of methods for producing inorganic fibers before fiber opening include the following: Specifically, an inorganic fiber precursor is produced by spinning a spinning mixture containing basic aluminum chloride and silica sol using a blowing method. Next, the inorganic fiber precursor is compressed to produce a rectangular sheet, and by firing the compressed sheet, pre-opening inorganic fibers made of silica-alumina fibers can be produced.

[0083] The method of fiber opening is not particularly limited, but the inorganic fibers may be opened using a dry method, followed by the addition of water for wet opening, or water may be added from the beginning for wet opening.

[0084] Fiber opening can be performed using machines such as slash pulpers, feather mills, disc mills, bale openers, beaters, hammer mills, carding machines, and wool bickers. The fiber opening process may be carried out using one type of machine, or it may be carried out using two or more types of machines. Furthermore, when wet fiber opening is performed, it is preferable to use a slash pulper for fiber opening.

[0085] This makes it possible to obtain a slurry containing inorganic fibers.

[0086] Furthermore, by opening the fibers of a needle mat or papermaking mat, a slurry can be obtained that contains fiber bundles formed by the twisting and entanglement of inorganic fibers.

[0087] When opening needle mats or papermaking mats, bake them at 700-1000°C for 1.0-8.0 hours before opening. This allows for the thermal decomposition of organic binders contained in needle mats and papermaking mats, making it easier to open the fibers of the needle mats and papermaking mats.

[0088] [Organic Fiber Preparation Process] Next, prepare the organic fibers. The organic fibers may be made by conventionally known methods or may be commercially available. The preferred types of organic fibers, average fiber length, and average fiber diameter are as described above, so further explanation is omitted here.

[0089] Next, the above organic fibers are placed in a mixer mill or similar device and stirred. As a result, some of the organic fibers become microfibers, and the organic fiber can be made to include a main fiber and multiple microfibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber.

[0090] For example, by adding water to 2.0g of organic fiber with a solid content to a concentration of 2.0% by weight, placing it in a mixer (product name: SJM-M1000P, manufacturer: Ishizaki Electric Works Co., Ltd.), and stirring at 13,000 to 18,000 rpm for 3.0 to 5.0 minutes, an organic fiber is obtained that contains main fibers and multiple fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fibers.

[0091] Alternatively, you can use a discriminator or similar tool to break it down. For example, by adding water to 100.0 g of organic fibers with a solid content to a concentration of 2.0% by weight, placing it in a disc refiner (product name: KRK type, manufacturer: Kumagai Riki Kogyo Co., Ltd.), and beating it at 3000 rpm, with a GAP of 0.05 to 0.10 mm, and passing it at least once, an organic fiber is obtained that contains main fibers and multiple fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fibers.

[0092] [Preparation process for papermaking slurry] Next, a slurry for papermaking is prepared by adding organic fibers, an organic binder, and an inorganic binder to a slurry containing inorganic fibers and mixing them together. In this case, it is preferable to adjust the concentration of each component so that the total weight of organic fibers and organic binders relative to the weight of the papermaking mat obtained through the papermaking process described later is 5% by weight or less. Since organic fibers and organic binders become organic components in the papermaking mat, by adjusting them in this way, it is possible to manufacture a papermaking mat with an organic component content of 5% by weight or less.

[0093] [Paper making process] Next, the papermaking slurry is poured into a molder with a filtration mesh formed on its bottom, and the solvent in the papermaking slurry is removed to obtain an inorganic fiber aggregate. Then, the inorganic fiber aggregate is dehydrated and dried to obtain the papermaking mat of the present invention.

[0094] Furthermore, during the papermaking process, the inorganic fiber aggregate may be heated and pressurized to dry it. During heating and pressurizing, a heat treatment may be performed in which hot air is passed through the inorganic fiber aggregate to dry it, or it may be left in a wet state without heat treatment. When heat treatment is performed, the heating temperature and hot air temperature are preferably between 150 and 210°C in order to prevent thermal degradation of the organic fibers and organic binders. Within the temperature range of 150-210°C, moisture can be removed from the inorganic fiber aggregate while suppressing the degradation of organic fibers and organic binders. If the heating temperature or hot air temperature is below 150°C, the heat does not reach the center of the inorganic fiber aggregate, resulting in a longer drying time. Furthermore, if the temperature exceeds 210°C, the organic fibers and organic binders will degrade, reducing the binding force between fibers, making it difficult to control the thickness of the inorganic fiber aggregate.

[0095] In the method for manufacturing papermaking mats of the present invention, it is preferable to perform batch papermaking or continuous papermaking in the papermaking process. The papermaking mat of the present invention can be easily obtained by batch papermaking or continuous papermaking.

[0096] Next, a method for using the papermaking mat of the present invention will be described. Figure 5 is a schematic cross-sectional view showing an example of the exhaust gas purification device of the present invention. As shown in Figure 5, the exhaust gas purification device 100 comprises a metal casing 60, an exhaust gas treatment unit 70 housed in the metal casing 60, and a papermaking mat 10, which is a holding material, disposed between the exhaust gas treatment unit 70 and the metal casing 60. The papermaking mat 10 is the papermaking mat of the present invention.

[0097] The exhaust gas treatment unit 70 is a columnar structure in which numerous cells 71 are arranged in a longitudinal direction separated by cell walls 72. An inlet pipe for introducing exhaust gas discharged from the internal combustion engine and an outlet pipe for discharging exhaust gas that has passed through the exhaust gas purification device are connected to the ends of the metal casing 60 as needed. In the exhaust gas purification device 100 shown in Figure 5, an exhaust gas filter (honeycomb filter) is used as the exhaust gas treatment body 70, in which one of the cells is sealed with a sealing material 73. However, a catalyst carrier in which neither end face is sealed with a sealing material may also be used.

[0098] As shown in Figure 5, exhaust gas (in Figure 5, exhaust gas is indicated by G and the flow of exhaust gas is indicated by arrows) discharged from the internal combustion engine and flowing into the exhaust gas purification device 100 flows into a cell 71 that opens on the exhaust gas inlet end face 70a of the exhaust gas treatment body (honeycomb filter) 70, and passes through the cell wall 72 separating the cells 71. At this time, PM in the exhaust gas is captured by the cell wall 72, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 71 that opens on the exhaust gas outlet end face 70b and is discharged to the outside.

[0099] As described above, the papermaking mat 10 holds the exhaust gas treatment body 70, and even when the exhaust gas treatment body 70 is subjected to high pressure from the exhaust gas during use of the exhaust gas purification device 100, it is possible to prevent the exhaust gas treatment body 70 from falling off the metal casing 60.

[0100] The exhaust gas treatment body 70 may be made of a non-oxidized porous ceramic such as silicon carbide or silicon nitride, or may be made of an oxidized porous ceramic such as sialon, alumina, cordierite, or mullite. Among these, silicon carbide is preferable.

[0101] When the exhaust gas treatment body 70 is a porous ceramic made of silicon carbide, the porosity of the porous ceramic is not particularly limited, but it is preferably 35 to 60%. When the porosity is less than 35%, the exhaust gas treatment body may easily become clogged, while when the porosity exceeds 60%, the strength of the exhaust gas treatment body may decrease and it may be easily broken.

[0102] Also, the average pore diameter of the porous ceramic is preferably 5 to 30 μm. When the average pore diameter is less than 5 μm, PM may easily become clogged. When the average pore diameter exceeds 30 μm, PM may pass through the pores and it may not be possible to collect PM and the body may not function as a filter. The above porosity and pore diameter can be measured by a conventionally known method using a scanning electron microscope (SEM).

[0103] The cell density in the cross section of the exhaust gas treatment body 70 is not particularly limited, but the preferable lower limit is 31.0 cells / cm 2 (200 cells / inch 2 [[ID=2t4]]) and the preferable upper limit is 93.0 cells / cm 2 (600 cells / inch 2 [[ID=t28]]) is. Also, the more preferable lower limit is 38.8 cells / cm 2 (250 cells / inch 2 ) and the more preferable upper limit is 77.5 cells / cm 2 (500 cells / inch 2 ) is.

[0104] The exhaust gas treatment unit 70 may be supported with a catalyst for purifying the exhaust gas. Precious metals such as platinum, palladium, and rhodium are preferred as the supported catalyst, with platinum being the most preferred among these. Other catalysts that can be used include alkali metals such as potassium and sodium, and alkaline earth metals such as barium. These catalysts may be used individually or in combination of two or more. When these catalysts are supported, PM (particulate matter) can be more easily burned off, and toxic exhaust gases can also be purified.

[0105] The metal casing 60 is approximately cylindrical in shape. The inner diameter of the metal casing 60 (the inner diameter of the portion that houses the exhaust gas treatment body) is preferably slightly shorter than the diameter of the exhaust gas treatment body 70 around which the papermaking mat 10 is wrapped.

[0106] The metal casing 60 is not particularly limited, but is preferably made of stainless steel.

[0107] (Second Embodiment) Next, a laminated sheet-attached papermaking mat according to a second embodiment of the present invention will be described. A papermaking mat with a laminated sheet according to the second embodiment of the present invention comprises the papermaking mat according to the first embodiment of the present invention and a laminated sheet material made of a plurality of fibers arranged on at least one main surface of the papermaking mat.

[0108] The laminated sheet-attached papermaking mat of the present invention will be wrapped around an exhaust gas treatment body and placed in an exhaust gas purification device. At this time, stress is applied to the main surface of the papermaking mat, making it more prone to cracking. However, if the laminated sheet described above is placed on the main surface of the papermaking mat, such cracking can be prevented.

[0109] The laminated sheet material, which consists of multiple fibers, may be a nonwoven fabric or a woven fabric.

[0110] The fibers constituting the laminated sheet material may be organic fibers or inorganic fibers, but organic fibers are preferred.

[0111] Examples of organic fiber materials include polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP).

[0112] Furthermore, the laminated sheet material is preferably a web-like body containing fiber bundles for the laminated sheet material formed by the entanglement of multiple fibers, and single fibers for the laminated sheet material.

[0113] A laminated sheet-covered papermaking mat, which includes a laminated sheet material that is a web-like body containing fiber bundles for the laminated sheet material and single fibers for the laminated sheet material, will be described below with reference to the drawings. Figure 6 is a schematic perspective view showing an example of a laminated sheet-attached papermaking mat according to the present invention.

[0114] The laminated sheet-attached papermaking mat 210 shown in Figure 6 comprises a papermaking mat 10 and a laminated sheet material 280 arranged on the main surface of the papermaking mat 10.

[0115] The preferred configuration of the papermaking mat 10 is as described above, so its description is omitted here.

[0116] Figure 7 is a schematic enlarged plan view showing an example of the laminated sheet shown in Figure 6. As shown in Figure 7, the laminated sheet material 280 is a web-like body that includes fiber bundles 281 for laminated sheet material formed by the entanglement of multiple fibers, and single fibers 282 for laminated sheet material.

[0117] The laminated sheet-attached papermaking mat 210, like the papermaking mat 10 described above, will be wrapped around the exhaust gas treatment body and placed in the exhaust gas purification device. In this process, stress is applied to the main surface of the papermaking mat 10, making it more prone to cracking. However, such cracking can be prevented if the laminated sheet material 280 is placed on the main surface of the papermaking mat 10.

[0118] The multiple fibers constituting the fiber bundle 281 for the laminated sheet material are twisted and intertwined with each other. Because the fibers constituting the fiber bundle 281 for the laminated sheet material are not fused with each other but are merely intertwined, the laminated sheet material 280 has high flexibility. The number of fibers constituting the fiber bundle 281 for the laminated sheet material is not particularly limited, but is preferably 2 or more and 10 or less, and more preferably 3 or more and 7 or less. Furthermore, the single fiber 282 used for laminated sheet materials is a fiber that is not entangled with other fibers.

[0119] The fiber bundle 281 for the laminated sheet material contains multiple fiber bundles with different stretching directions, and the laminated sheet material 280 is formed from these multiple fiber bundles and single fibers 282. As a result, the number of fibers in the longitudinal direction and the number of fibers in the transverse direction can be made to be approximately the same in the laminated sheet material 280.

[0120] In this example, the laminated sheet material 280 consists of longitudinally oriented fibers and transversely oriented fibers, which are stretched in two directions, the longitudinal direction and the transverse direction, respectively. In other words, the laminated sheet material 280 is a nonwoven fabric with fiber orientation in both the longitudinal and transverse directions, composed of longitudinally oriented fibers and transversely oriented fibers arranged in the transverse direction.

[0121] This nonwoven fabric is manufactured using a process that spins the raw materials directly, and the spun fibers are stretched in both the longitudinal and transverse directions, causing the long fiber filaments to be oriented in those directions.

[0122] Furthermore, the fibers forming the laminated sheet material 280 do not necessarily need to be straight; at least some of the fibers forming the laminated sheet material 280 may be curved. This increases the number of intersections between the fibers forming the laminated sheet material 280, which helps to distribute the stress applied to the laminated sheet material 280, thereby further suppressing the occurrence of cracks when the papermaking mat 10 is wrapped around it.

[0123] Furthermore, the laminated sheet material 280 may be a three-dimensional web-like body. As a result, the strength of the laminated sheet material 280 is further improved and the stress applied to the laminated sheet material 280 is distributed, making it possible to more efficiently suppress the occurrence of cracks on the main surface of the laminated sheet-attached papermaking mat 210.

[0124] Furthermore, the laminated sheet material 280 may contain fibers that are extended in three or more directions. For example, in addition to longitudinally oriented fibers and transversely oriented fibers, it may also contain fibers that are extended in an oblique direction, and these fibers may result in the presence of fiber bundles and single fibers that are extended in an oblique direction.

[0125] The fibers constituting the laminated sheet material 280 (hereinafter referred to as web fibers) are preferably long filament fibers. The long fiber filament is preferably longer than the length of a normal short fiber (e.g., 10-50 mm), preferably has an average fiber length of 100 mm or more, and more preferably has an average fiber length of several hundred mm or more. The long fiber filament may also be a continuous long fiber.

[0126] The average fiber diameter of the web fibers described above is usually 10 μm or less in the main constituent filaments, and preferably around 5 μm.

[0127] The web fibers are preferably composed of at least one of organic fibers and inorganic fibers. For example, longitudinally oriented fibers may be composed of organic fibers and / or inorganic fibers, and transversely oriented fibers may be composed of organic fibers and / or inorganic fibers. The materials of the longitudinally oriented fibers and transversely oriented fibers may be different from each other.

[0128] It is more preferable that the web fibers described above are composed of organic fibers. This makes it possible to more effectively suppress the occurrence of cracks on the main surface of the papermaking mat.

[0129] Suitable materials for the above-mentioned web fibers include polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP).

[0130] As shown in Figure 7, the laminated sheet material 280 further has a plurality of base portions 283 made of organic material, and fiber bundles 281 for the laminated sheet material and single fibers 282 for the laminated sheet material may extend from each base portion 283 in multiple directions.

[0131] The base portions 283 are distributed within the laminated sheet material 280, and each base portion 283 joins together fiber bundles 281 and single fibers 282 for the laminated sheet material that are stretched in different directions. In other words, the base portions 283 are positioned in the regions where the fiber bundles 281 and single fibers 282 for the laminated sheet material intersect, and they join these fibers together.

[0132] Furthermore, the base portion 283 plays a role in fixing the laminated sheet material 280 to the papermaking mat 10. In other words, the base portion 283 joins the fibers that form the laminated sheet material 280 to the papermaking mat 10 by fusing them together.

[0133] The base 283 may be composed of organic material. The organic material constituting the base 283 is different from the material of the web fibers. Specifically, the base 283 may be formed by heat-sealing hot-melt powder (hot-melt adhesive) to the web fibers.

[0134] The organic material constituting the base 283 is not particularly limited as long as it can be used as a hot melt powder, but specific examples include polyethylene (PE), polyethylene terephthalate (PET), polyamide (PA), ethylene-vinyl acetate copolymer resin (EVA), etc.

[0135] The laminated sheet-attached papermaking mat 210 preferably has an organic component content of 8% by weight or less, and more preferably 7% by weight or less. If the organic component content of the laminated sheet-attached papermaking mat 210 is 8% by weight or less, even if exhaust gas reaches the exhaust gas purification device on which the laminated sheet-attached papermaking mat 210 is placed and the organic component is decomposed by the heat of the exhaust gas, the amount of gas generated will be small. Therefore, the generation of odors associated with gas generation can be suppressed.

[0136] In this specification, the "organic component content (by weight) of the laminated sheet-attached papermaking mat" is calculated as follows. First, measure the weight W3 of the laminated sheet-attached papermaking mat. Next, the laminated sheet-attached papermaking mat is heated at 600°C for 1 hour to decompose the organic components. Then, the weight W4 of the papermaking mat after heating is measured. The organic component content (by weight) of the laminated sheet-attached papermaking mat is calculated using the following formula (2). [Amount of organic components in laminated sheet-attached papermaking mat (weight %)] = (W3 - W4) / W3 × 100 ... (2)

[0137] This specification contains the following information:

[0138] (1) The present disclosure is a papermaking mat comprising a plurality of inorganic fibers, a plurality of organic fibers, an organic binder, and an inorganic binder, wherein the organic fibers comprise a main fiber and a plurality of fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber, and a first mixture of the organic fibers, the organic binder, and the inorganic binder is present on the surface of the inorganic fibers.

[0139] Disclosure (2) is a papermaking mat according to Disclosure (1), wherein the first mixture comprises the main fibers, the fine fibers, the organic binder, and the inorganic binder.

[0140] Disclosure (3) is a papermaking mat according to Disclosure (1) wherein the first mixture comprises the fine fibers, the organic binder, and the inorganic binder.

[0141] Disclosure (4) is a papermaking mat according to any one of Disclosures (1) to (3), wherein a second mixture of the organic fiber, the organic binder, and the inorganic binder is present at the intersection of the inorganic fibers.

[0142] The present disclosure (5) is a papermaking mat according to the present disclosure (4), wherein the second mixture comprises the main fibers, the fine fibers, the organic binder, and the inorganic binder.

[0143] The present disclosure (6) is a papermaking mat according to the present disclosure (4), wherein the second mixture comprises the fine fibers, the organic binder, and the inorganic binder.

[0144] Disclosure (7) is a papermaking mat according to any of Disclosures (1) to (6), wherein a plurality of fine fibers formed on a single organic fiber are in contact with a plurality of inorganic fibers.

[0145] Disclosure (8) is a papermaking mat according to any one of Disclosures (1) to (7), wherein the inorganic fiber comprises at least one selected from the group consisting of alumina fiber, refractory ceramic fiber (RCF), glass fiber, mullite fiber, silica fiber, basalt fiber, and biosoluble fiber.

[0146] Disclosure (9) is a papermaking mat according to any one of Disclosures (1) to (8), wherein the inorganic fibers include first inorganic fibers having an average fiber diameter of 3.0 to 20.0 μm and second inorganic fibers having an average fiber diameter of 0.1 to 15.0 μm.

[0147] Disclosure (10) is a papermaking mat according to any one of Disclosures (1) to (9), wherein the organic fiber is selected from the group consisting of cellulose fiber, acrylic fiber, aramid fiber, PVA fiber, polyamide fiber, polyester fiber, polyethylene fiber, nylon fiber, polyurethane fiber, polyclar fiber, and polylactic acid fiber.

[0148] Disclosure (11) is a papermaking mat according to any of Disclosures (1) to (10), wherein the average fiber diameter of the organic fibers is 1 to 10 μm.

[0149] Disclosure (12) is a papermaking mat according to any of Disclosures (1) to (11), wherein the average fiber diameter of the above-mentioned fine fibers is 0.01 to 1 μm.

[0150] Disclosure (13) is a papermaking mat according to any one of Disclosures (1) to (12), wherein the organic binder is at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, polyvinyl alcohol, styrene resin, and epoxy resin.

[0151] This disclosure (14) is a papermaking mat according to any one of this disclosure (1) to (13), wherein the inorganic binder comprises at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice.

[0152] Disclosure (15) is a papermaking mat according to any of Disclosures (1) to (14), wherein the content of organic components is 5% by weight or less.

[0153] The present disclosure (16) is a papermaking mat according to any of the present disclosures (1) to (15), wherein the ratio of the total weight of the organic fibers, the organic binder, and the inorganic binder to the weight of the inorganic fibers (([Weight of organic fibers] + [Weight of organic binder] + [Weight of inorganic binder]) / [Weight of inorganic fibers]) is 0.01 to 0.1.

[0154] The present disclosure (17) is a papermaking mat according to any of the present disclosures (1) to (16), wherein the ratio of the weight of the organic fibers to the total weight of the organic fibers, the organic binder, and the inorganic binder ([weight of organic fibers] / ([weight of organic fibers]+[weight of organic binder]+[weight of inorganic binder])) is 0.01 to 0.9.

[0155] (18) is a papermaking mat according to any of (1) to (17) of this disclosure, wherein if the thickness of the papermaking mat is T1, and the thickness of the papermaking mat after heating the papermaking mat at 50°C and 80% humidity for 24 hours is T2, then the ratio of T2 to T1 (T2 / T1) is 1.0 to 1.3.

[0156] (19) of this disclosure is a papermaking mat according to any one of (1) to (18) of this disclosure, used as the retaining material for an exhaust gas purification device comprising a metal casing, an exhaust gas treatment body housed in the metal casing, and a retaining material disposed between the metal casing and the exhaust gas treatment body.

[0157] The present disclosure (20) is a papermaking mat with a laminated sheet, characterized by comprising a papermaking mat according to any one of the present disclosures (1) to (19) and a laminated sheet material made of a plurality of fibers arranged on at least one main surface of the papermaking mat.

[0158] The present disclosure (21) is a laminated sheet-covered papermaking mat according to the present disclosure (20), wherein the laminated sheet material is a web-like body comprising a fiber bundle for the laminated sheet material formed by the entanglement of a plurality of fibers and single fibers for the laminated sheet material.

[0159] The present disclosure (22) is a laminated sheet-attached papermaking mat according to the present disclosure (20) or (21), wherein the content of organic components is 8% by weight or less. [Examples]

[0160] The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0161] (Example 1) [Opening process] A bulk material consisting of alumina-silica fibers with an Al2O3:SiO2 ratio of 72:28 (by weight) was prepared.

[0162] Next, 34.0 g of an aggregate of inorganic fibers was taken from the bulk material and placed in 7.0 L of water. Then, using a stirrer (product name: SMT-101, manufacturer: ASONE), the mixture was stirred at a rotation speed of 1000 rpm for a stirring time of 10 minutes to open the fibers and prepare an inorganic fiber slurry.

[0163] [Organic Fiber Preparation Process] Cellulose fibers with an average fiber diameter of 10.0 μm were prepared, and 2.0 g of the cellulose fibers were placed in a mixer (product name: SJM-M1000P, manufacturer: Ishizaki Electric Works Co., Ltd.) and stirred at 17,000 rpm for 5.0 minutes. This process resulted in the creation of cellulose fibers containing a main fiber and multiple fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber. The average fiber diameter of the microfibers was 8.3 μm.

[0164] [Preparation process for papermaking slurry] To the slurry of the inorganic fibers described above, cellulose fibers with fine fibers formed on them were added. In this process, the amount of cellulose fibers was adjusted to 1.0 to 4.0 parts by weight per 100 parts by weight of inorganic fibers. Furthermore, a papermaking slurry was prepared by adding LX854E, manufactured by Nippon Zeon Co., Ltd., as an organic binder, and AS-520-A, manufactured by Nissan Chemical Corporation, as an inorganic binder. In this preparation, the ratio of organic binder to inorganic binder was 1.0 to 4.0 parts by weight and inorganic binder to inorganic binder was 2.0 parts by weight per 100 parts by weight of inorganic fibers.

[0165] [Paper making process] Next, the papermaking slurry was poured into a molder with a filtration mesh formed on its bottom, and the solvent in the papermaking slurry was removed to obtain an inorganic fiber aggregate. Subsequently, the inorganic fiber aggregate was dehydrated and dried at 150-210°C for 5 minutes to 1 hour to produce the papermaking mat according to Example 1.

[0166] (Example 2) [Opening process] It is made of alkali earth silicate fibers, which are biosoluble fibers, and has a bulk density of 0.17 g / cm³. 3 The density of needle marks is 21 / cm³. 2 We prepared a needle mat with a specific density.

[0167] Next, the needle mat was fired at 800°C for 1 hour to thermally decompose the organic components contained in the needle mat.

[0168] Next, the fired needle mat was left to stand until it reached room temperature, and then the needle mat was loosened by hand.

[0169] Next, 5.0 g of an aggregate of inorganic fibers was taken from the needle mat and placed in 0.4 L of water. Then, using a stirrer (product name: SMT-101, manufacturer: ASONE), the mixture was stirred at a rotation speed of 1000 rpm for a stirring time of 10 minutes to open the fibers and prepare an inorganic fiber slurry.

[0170] Using the obtained inorganic fiber slurry, the [organic fiber preparation step], [papermaking slurry preparation step], and [papermaking step] were performed in the same manner as in Example 1 to produce the papermaking mat according to Example 2.

[0171] The state of the inorganic fibers constituting the papermaking mats according to Example 1 and Example 2 was photographed using a scanning electron microscope (SEM). The photographs are shown in Figures 8 and 9. Figure 8 is a magnified photograph of the inorganic fibers constituting the papermaking mat according to Example 1. Figure 9 is a magnified photograph of the inorganic fibers constituting the papermaking mat according to Example 2. As shown in Figures 8 and 9, in the papermaking mats according to Example 1 and Example 2, a mixture of organic fibers, organic binders, and inorganic binders was found on the surface of the inorganic fibers, and furthermore, a mixture of organic fibers, organic binders, and inorganic binders was found at the intersections of the inorganic fibers.

[0172] (Examples 3) to (Examples 11) and (Comparative Example 1) to (Comparative Example 2) Except for adjusting the amount of organic binder used so that the proportion of organic components in the papermaking mat was as shown in Table 1, the papermaking mats according to Examples 3 to 11 were manufactured in the same manner as in Example 1. Furthermore, except that organic fibers were not used and the amount of organic binder used was adjusted so that the proportion of organic components in the papermaking mat was as shown in Table 1, papermaking mats according to Comparative Examples 1 and 2 were manufactured in the same manner as in Example 1.

[0173] [Measurement of organic components] The weight of the papermaking mat for each example was measured. Subsequently, the papermaking mats according to each example were heated at 600°C for 1.0 hour to decompose the organic components, and the weight of the papermaking mats after heating was measured. The organic component content (by weight) in the papermaking mat for each example was calculated from the weight of the papermaking mat before and after heating. The results are shown in Table 1.

[0174] [Table 1]

[0175] (Moldability test) The thickness T1 of each papermaking mat was measured. Then, the thickness T2 of each papermaking mat was measured after heating it at 50°C and 80% humidity for 24 hours. The ratio of T2 to T1 (T2 / T1) was then calculated. The results are shown in Table 1.

[0176] As shown in Table 1, the papermaking mats according to each example were found to have a low T2-to-T1 ratio (T2 / T1) and high moldability, despite having an organic component content that was about half that of the papermaking mats according to each comparative example.

[0177] (Measurement of holding power) The mat materials according to Example 2, Example 6, and Comparative Example 1 were placed between the upper and lower plates of a hot surface pressure measuring device manufactured by MTS Corporation, which is equipped with a heating element. Next, at room temperature, the top plate was moved at a speed of 25.4 mm / min, and the bulk density was 0.40 g / cm³.3 The surface pressure was measured when the mat material was compressed to that point. Subsequently, with the mat material compressed, the upper and lower plates were heated to 600°C at a heating rate of 45°C / min and held at that temperature for 10 minutes. The rate of reduction in surface pressure (%) ((1 - [initial surface pressure of the papermaking mat] / [minimum surface pressure of the papermaking mat during heating]) × 100) was measured.

[0178] As shown in Table 1, it was found that the papermaking mats of Example 2 and Example 6 exhibited a low rate of reduction in surface pressure even when heated. [Explanation of Symbols]

[0179] 10 Papermaking mats 11 End 11a Convex part 12 End 12a Recess 20 Inorganic Fibers 30 Organic Fibers 31 Main fiber 32 microfibers 41 1st mixture 42 Second mixture 50 fiber bundles 60 Metal casing 70 Exhaust gas treatment unit 70a Exhaust gas inlet side end face 70b Exhaust gas outlet side end face 71 cells 72 Cell Wall 73 Sealing material 100 Exhaust gas purification device 210 Laminated Sheet Papermaking Mat 280 Laminated Sheet Material 281 Fiber bundles for laminated sheet materials 282 Single fibers for laminated sheet materials 283 Base

Claims

1. A paper-formed mat used as the retaining material for an exhaust gas purification device comprising a metal casing, an exhaust gas treatment body housed in the metal casing, and a retaining material disposed between the metal casing and the exhaust gas treatment body, The aforementioned papermaking mat comprises a plurality of inorganic fibers, a plurality of organic fibers, an organic binder, and an inorganic binder. The organic fiber comprises a main fiber and a plurality of fine fibers that are frayed and subdivided from at least a portion of the entire surface of the main fiber. A first mixture of the organic fiber, the organic binder, and the inorganic binder is present on the surface of the inorganic fiber. A papermaking mat characterized in that the average fiber diameter of the organic fibers is 1 to 10 μm.

2. The papermaking mat according to claim 1, wherein the first mixture comprises the main fibers, the fine fibers, the organic binder, and the inorganic binder.

3. The papermaking mat according to claim 1, wherein the first mixture comprises the fine fibers, the organic binder, and the inorganic binder.

4. The papermaking mat according to claim 1, wherein a second mixture of the organic fiber, the organic binder, and the inorganic binder is present at the intersection of the inorganic fibers.

5. The papermaking mat according to claim 4, wherein the second mixture comprises the main fibers, the fine fibers, the organic binder, and the inorganic binder.

6. The papermaking mat according to claim 4, wherein the second mixture comprises the fine fibers, the organic binder, and the inorganic binder.

7. The papermaking mat according to claim 1, wherein a plurality of fine fibers formed on a single organic fiber are in contact with a plurality of inorganic fibers.

8. The papermaking mat according to claim 1, wherein the inorganic fiber comprises at least one selected from the group consisting of alumina fiber, refractory ceramic fiber (RCF), glass fiber, mullite fiber, silica fiber, basalt fiber, and biosoluble fiber.

9. The papermaking mat according to claim 1, wherein the inorganic fibers include first inorganic fibers having an average fiber diameter of 3.0 to 20.0 μm and second inorganic fibers having an average fiber diameter of 0.1 to 15.0 μm.

10. The papermaking mat according to claim 1, wherein the organic fiber comprises at least one selected from the group consisting of cellulose fiber, acrylic fiber, aramid fiber, PVA fiber, polyamide fiber, polyester fiber, polyethylene fiber, nylon fiber, polyurethane fiber, polyclar fiber, and polylactic acid fiber.

11. The papermaking mat according to claim 1, wherein the average fiber diameter of the fine fibers is 0.01 to 1 μm.

12. The papermaking mat according to claim 1, wherein the organic binder comprises at least one selected from the group consisting of acrylic resin, acrylate latex, rubber latex, carboxymethylcellulose, polyvinyl alcohol, styrene resin, and epoxy resin.

13. The papermaking mat according to claim 1, wherein the inorganic binder comprises at least one of alumina, silica, silicon carbide, zirconia, boron nitride, diamond, and pumice.

14. The papermaking mat according to claim 1, wherein the ratio of the total weight of the organic fibers, the organic binder, and the inorganic binder to the weight of the inorganic fibers (([weight of organic fibers] + [weight of organic binder] + [weight of inorganic binder]) / [weight of inorganic fibers]) is 0.01 to 0.

1.

15. The papermaking mat according to claim 1, wherein the ratio of the weight of the organic fibers to the total weight of the organic fibers, the organic binder, and the inorganic binder ([weight of organic fibers] / ([weight of organic fibers] + [weight of organic binder] + [weight of inorganic binder])) is 0.01 to 0.

9.

16. The thickness of the aforementioned papermaking mat is T １ The thickness of the papermaking mat after heating it at 50°C and 80% humidity for 24 hours is T. ２ Therefore, T １ T ２ The ratio (T ２ / T １ The papermaking mat according to claim 1, wherein ) is 1.0 to 1.

3.

17. A papermaking mat according to any one of claims 1 to 16, A papermaking mat with a laminated sheet, characterized by comprising a laminated sheet material made of multiple fibers arranged on at least one main surface of the papermaking mat.

18. The laminated sheet mat according to claim 17, wherein the laminated sheet material is a web-like body comprising a fiber bundle for laminated sheet material formed by the entanglement of multiple fibers and single fibers for laminated sheet material.

19. The laminated sheet-attached papermaking mat according to claim 17, wherein the content of organic components is 8% by weight or less.

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