JP2015214906A - Holding seal material, holding seal material manufacturing method, and exhaust gas purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding seal material capable of suppressing the dispersion amount of inorganic fiber effectively and satisfying a bearing characteristics required for the holding seal material sufficiently, and a method for manufacturing the holding seal material.SOLUTION: A holding seal material made of inorganic fibers is characterized: in that a binder membrane made of a first organic binder is formed on the surfaces of the inorganic fibers; and in that an aggregate composed of a second organic binder and an inorganic binder protrude from said binder membrane to form a plurality of salients.

Description

The present invention relates to a holding sealing material, a method for manufacturing the holding sealing material, and an exhaust gas purification apparatus.

The exhaust gas discharged from an internal combustion engine such as a diesel engine contains particulate matter (hereinafter also referred to as PM) such as soot. In recent years, this PM has a problem that it causes harm to the environment and the human body. It has become. Further, since the exhaust gas contains harmful gas components such as CO, HC and NOx, there is a concern about the influence of the harmful gas components on the environment and the human body.

Therefore, as an exhaust gas purification device that collects PM in exhaust gas or purifies harmful gas components, an exhaust gas treatment body made of a porous ceramic such as silicon carbide or cordierite, and a casing that houses the exhaust gas treatment body Various types of exhaust gas purifying apparatuses have been proposed, which are composed of an inorganic fiber aggregate disposed between an exhaust gas treating body and a casing. This holding sealing material prevents the exhaust gas treating body from being damaged by contact with the casing covering the outer periphery due to vibrations or impacts caused by traveling of an automobile or the like, or exhaust gas from between the exhaust gas treating body and the casing. The main purpose is to prevent leakage and the like. Therefore, the holding sealing material is required to have a function of increasing the surface pressure generated by the repulsive force caused by being compressed and holding the exhaust gas treating body reliably. Furthermore, it is known that when the exhaust gas treating body is accommodated in the casing, the inorganic fibers constituting the holding sealing material are broken and scattered in the atmosphere. Due to such scattering of the inorganic fibers, there is a problem that the inorganic fibers scattered in the atmosphere adversely affect the working environment of the worker handling the holding sealing material.

Conventionally, in order to solve such a problem, a method of impregnating a holding sealing material with an aggregate composed of an organic binder and an inorganic binder is known (for example, see Patent Document 1).

JP 2012-157809 A

However, the method disclosed in Patent Document 1 uses only an aggregate composed of an organic binder and inorganic particles as an inorganic binder, and the effect of suppressing the scattering of inorganic fibers is applied to the portion where the aggregate is attached. Limited. Therefore, when the inorganic fiber is broken at a portion where no aggregate is present, the scattering of the inorganic fiber cannot be suppressed. In addition, after the organic binder is burned down by the heat of the exhaust gas, the inorganic binder remaining on the surface of the inorganic fibers improves the surface pressure by preventing the fibers from slipping, but the remaining inorganic binder is Since it exists only on a part of the surface of the inorganic fiber, the effect of improving the surface pressure is small. Therefore, there has been a problem that the effect of improving the surface pressure and the effect of suppressing the scattering of inorganic fibers have not been sufficiently achieved.

The present invention has been made in order to solve the above-described problem, and can effectively suppress the scattering amount of the inorganic fibers and can sufficiently satisfy the surface pressure characteristics required for the holding sealing material. It aims at providing a sealing material and its manufacturing method. Moreover, an object of this invention is to provide the exhaust gas purification apparatus provided with the said holding sealing material.

In order to achieve the above object, the holding sealing material of the present invention is a holding sealing material made of inorganic fibers, and a binder film made of a first organic binder is formed on the surface of the inorganic fibers. An aggregate composed of the second organic binder and the inorganic binder protrudes from the binder film to form a plurality of convex portions.

In the holding sealing material of the present invention, since the binder film made of the first organic binder is formed on the surface of the inorganic fiber, the inorganic fiber is scattered by the binder film even when the inorganic fiber is broken. Can be suppressed. Therefore, when manufacturing the exhaust gas purification device by press-fitting the exhaust gas treating body around which the holding sealing material of the present invention is wound into a metal casing, scattering of inorganic fibers can be suppressed.

Moreover, the aggregate which consists of a 2nd organic binder and an inorganic binder protrudes in the binder film | membrane, and the convex part is formed. For this reason, when the inorganic fibers are in contact with each other, the protrusions are hooked to cause frictional resistance, and the inorganic fibers are less likely to slip. As a result, the surface pressure of the holding sealing material is improved.

Furthermore, the holding sealing material of the present invention can reduce the surface pressure of the holding sealing material even when high-temperature exhaust gas flows into the exhaust gas purification device and the first organic binder and the second organic binder are burned out. Can be kept high.
This is because when the second organic binder in the aggregate is burned off at a high temperature, the inorganic particles as the inorganic binder adhere to and bind to the surface of the inorganic fiber and are maintained as convex portions. Therefore, when the said convex part is caught, it becomes frictional resistance and it becomes difficult to occur that inorganic fiber slips. As a result, the surface pressure of the holding sealing material is improved, and the exhaust gas treating body can be stably held.

In the holding sealing material of the present invention, the aggregate is preferably constituted by dispersing inorganic particles as the inorganic binder in a polymer resin component as the second organic binder. Dispersing the inorganic particles as the inorganic binder in the polymer resin component as the second organic binder improves the mechanical strength of the aggregate and contributes to the improvement of the surface pressure.

In the holding sealing material of the present invention, it is preferable that the average height of the convex portions is smaller than the average fiber diameter of the inorganic fibers including the binder film.
If the average height of the protrusions is equal to or greater than the average fiber diameter of the inorganic fibers including the binder film, the protrusions may be caught too strongly, and the binder film may peel from the inorganic fibers or form protrusions. In some cases, the agglomerated particles may fall off the binder film.

In the holding sealing material of the present invention, the total content of the first organic binder and the second organic binder is preferably 2% by weight or less of the entire holding sealing material.
When the total content of the first organic binder and the second organic binder exceeds 2% by weight of the entire holding sealing material, the effect of suppressing the scattering of inorganic fibers and the effect of improving the surface pressure are Almost the same, the amount of cracked gas generated by the heat of the exhaust gas increases, which may adversely affect the surrounding environment.

In the holding sealing material of the present invention, the content of the inorganic binder is preferably 2% by weight or less of the entire holding sealing material.
In the holding sealing material of the present invention, when the content of the inorganic binder exceeds 2% by weight, the effect of improving the surface pressure is hardly changed. Therefore, excessive use of an inorganic binder is not preferable from the viewpoint of manufacturing cost.

In the holding sealing material of the present invention, the polymer resin component as the first organic binder and the polymer resin component as the second organic binder are preferably acrylic resins.
When the polymer resin component as the first organic binder and the polymer resin component as the second organic binder are acrylic resins, it is easy to improve the strength of the binder film.

In the holding sealing material of the present invention, the glass transition point (T _g ) of the polymer resin component as the first organic binder and the polymer resin component as the second organic binder is 5 ° C. or less. It is preferable.
When the glass transition point of the polymer resin component as the first organic binder is 5 ° C. or less, the binder film covering the surface of the inorganic fiber does not become too hard and is highly flexible. The holding sealing material is easily bent when wound around the exhaust gas treatment body. Further, when the glass transition point of the polymer resin component as the second organic binder is 5 ° C. or less, the strength can be increased while maintaining the flexibility of the aggregate. Therefore, while maintaining the flexibility of the holding sealing material, when the inorganic fibers are in contact with each other, the aggregates are less likely to fall off and the inorganic fibers are less likely to slip, and the surface pressure is easily improved.

The holding sealing material of the present invention is preferably subjected to needle punching treatment. By entanglement of the inorganic fibers by the needle punching process, the entanglement between the inorganic fibers is strengthened and the surface pressure is easily improved.

The manufacturing method of the holding sealing material of the present invention includes a mat preparation step for preparing a mat made of inorganic fibers, and a binder solution for forming a binder film made of a first organic binder on the surface of the inorganic fibers. A binder solution preparation step to prepare, an aggregate solution preparation step of mixing the second organic binder and the inorganic binder to form an aggregate composed of the second organic binder and the inorganic binder, and the above By bringing the binder solution and the aggregate solution into contact with the mat, a binder film composed of the first organic binder is formed on the surface of the inorganic fiber, and the aggregate is formed on the binder film. It comprises a solution contact step for forming a convex portion and a drying step for drying the mat in contact with the binder solution and the aggregate solution.

In the method for producing a holding sealing material of the present invention, a binder solution preparing step of preparing a binder solution composed of a first organic binder, a second organic binder and an inorganic binder are mixed to produce a second organic An aggregate solution preparation step for forming an aggregate composed of a binder and an inorganic binder is performed.
By bringing the binder solution into contact with the mat and drying it, a binder film made of the first organic binder is formed on the surface of the inorganic fiber. On the other hand, by bringing the aggregate solution into contact with the mat and then drying, a convex portion made of an aggregate in which the second organic binder and the inorganic binder are aggregated is formed. Therefore, it is suitable as a method for producing the holding sealing material of the present invention.

The exhaust gas purification apparatus of the present invention is wound around a metal casing, an exhaust gas treatment body accommodated in the metal casing, and the exhaust gas treatment body, and is disposed between the exhaust gas treatment body and the metal casing. An exhaust gas purification apparatus comprising a holding sealing material, wherein the holding sealing material is the holding sealing material of the present invention.

In the exhaust gas purifying apparatus of the present invention, the holding sealing material manufactured by the above manufacturing method is used as the holding sealing material. Therefore, the first organic binder and the second organic binder are heated by introducing exhaust gas or the like. When the inorganic fibers contact each other because the inorganic binder that formed the aggregates firmly binds to the surface of the inorganic fibers and many irregularities are formed on the surface of the inorganic fibers. The surface pressure of the holding sealing material can be improved.

Fig.1 (a) is the perspective view which showed typically an example of the aggregate which protrudes from the inorganic fiber which comprises the holding | maintenance sealing material of this invention, the binder membrane | film | coat which covers an inorganic fiber surface, and a binder membrane | film | coat. 1 (b) is a cross-sectional view taken along line AA in FIG. 1 (a), and FIG. 1 (c) is an enlarged cross-sectional view of the aggregate in FIG. 1 (b). FIG. 2A is a cross-sectional view schematically showing another example of an aggregate constituting the holding sealing material of the present invention, and FIG. 2B is an aggregate constituting the holding sealing material of the present invention. FIG. 2C is a cross-sectional view schematically showing still another example of the aggregate constituting the holding sealing material of the present invention. FIG. 3A is an SEM photograph before firing of the holding sealing material of the present invention, and FIG. 3B is an SEM photograph after firing of the holding sealing material of the present invention. FIG. 4 is a perspective view schematically showing an example of the holding sealing material of the present invention. Fig.5 (a) is a side view which shows typically an example of the measuring apparatus for measuring the dispersibility of an inorganic fiber, FIG.5 (b) is a measuring apparatus for measuring the dispersibility of an inorganic fiber. FIG. 6 is a plan view schematically showing a part of a sample support arm that constitutes the structure. FIG. 6 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention. FIG. 7 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention. FIG. 8 is a perspective view schematically showing an example of the manufacturing method of the exhaust gas purifying apparatus of the present invention.

(Detailed description of the invention)
Hereinafter, the holding sealing material of the present invention will be specifically described. However, the present invention is not limited to the following configurations, and can be applied with appropriate modifications without departing from the scope of the present invention.

Hereinafter, the holding sealing material of the present invention will be described.

In the holding sealing material of the present invention, the surface of the inorganic fiber is covered with the binder film made of the first organic binder, and the aggregate made of the second organic binder and the inorganic binder is further bonded to the binder. It protrudes from the film.

Fig.1 (a) is the perspective view which showed typically an example of the aggregate which protrudes from the inorganic fiber which comprises the holding | maintenance sealing material of this invention, the binder membrane | film | coat which covers an inorganic fiber surface, and a binder membrane | film | coat. 1 (b) is a cross-sectional view taken along line AA in FIG. 1 (a), and FIG. 1 (c) is an enlarged cross-sectional view of the aggregate in FIG. 1 (b).
As shown in FIG. 1A, in the holding sealing material of the present invention, the surface of the inorganic fiber 10 constituting the holding sealing material is covered with a binder film 20. Further, as shown in FIG. 1B, the aggregate 30 protrudes from the binder film 20.

Moreover, as shown in FIG.1 (b), in the inorganic fiber which comprises the holding | maintenance sealing material of this invention, even if the aggregate 30 may be contacting the inorganic fiber 10, it may not be contacting the inorganic fiber 10 Good. When the aggregate protrudes from the binder film, a convex portion is formed on the surface of the inorganic fiber. By this convex part, the frictional resistance between inorganic fibers increases, and the surface pressure of the holding sealing material can be improved.

FIG. 1C is a cross-sectional view schematically showing that the inorganic particles 32 as the inorganic binder are dispersed in the polymer resin component 31 as the second organic binder in the aggregate 30. is there.
When the inorganic particles as the inorganic binder are dispersed in the polymer resin component as the second organic binder, the mechanical strength of the aggregate is improved. Therefore, when the inorganic fibers are in contact with each other, it is difficult for the aggregates to drop and the inorganic fibers to slip, and the surface pressure is easily improved.

Further, as shown in FIG. 1C, the aggregate 30 protrudes from the binder film 20 made of the polymer resin component 21 as the first organic binder, but its height (FIG. 1C). ), The average value of the distance indicated by the double arrow a) (hereinafter also referred to as the average height of the convex portion) is the fiber diameter of the inorganic fiber 10 including the binder film 20 (double arrow in FIG. 1B). It is preferable that it is smaller than the average value of (length indicated by b). If the average height of the protrusions is equal to or greater than the average fiber diameter of the inorganic fibers including the binder film, the protrusions may be caught too strongly, and the binder film may peel from the inorganic fibers or form protrusions. In some cases, the agglomerated particles may fall off the binder film.
In addition, let the average height of a convex part be an average value of the height of ten convex parts selected at random from the SEM image of a holding sealing material.

FIG. 2A is a cross-sectional view schematically showing another example of an aggregate constituting the holding sealing material of the present invention, and FIG. 2B is an aggregate constituting the holding sealing material of the present invention. FIG. 2 (c) is a cross-sectional view schematically showing yet another example of the aggregate constituting the holding sealing material of the present invention.
In the aggregate constituting the holding sealing material of the present invention, the aggregation form of the polymer resin component as the second organic binder and the inorganic particles as the inorganic binder is not particularly limited. For example, FIG. 2 (a) The aggregate 35 may be formed so that the polymer resin component 31 as the second organic binder surrounds the periphery of the inorganic particles 32 as at least one inorganic binder as shown in FIG. On the contrary, as shown in FIG. 2B, the aggregate 36 may be formed so that the inorganic particles 32 as the inorganic binder surround the polymer resin component 31 as the second organic binder. Good.
Further, as shown in FIG. 2 (c), the inorganic particles 32 as the inorganic binder are one large particle, and the periphery is surrounded by the polymer resin component 31 as the second organic binder. The collection body 37 may be formed.
1C, FIG. 2A, FIG. 2B, and FIG. 2C are cross-sectional views of the polymer resin component (for example, latex) as the second organic binder. Particle) and inorganic particles as an inorganic binder schematically show the formation of aggregates, the shape of the polymer resin component as the second organic binder constituting the aggregates, and the inorganic binder as The shape of the inorganic particles and the shape of the aggregate are not particularly limited. The aggregate can be formed, for example, by aggregating a second organic binder and an inorganic binder in a solvent, but the shape of the polymer resin component as the second organic binder in the solvent. The shape of the inorganic particles as the inorganic binder is not particularly limited.

Hereinafter, various materials constituting the holding sealing material of the present invention will be described.

The binder film constituting the holding sealing material of the present invention is obtained by drying the first organic binder (binder solution) dispersed in a solvent.

The polymer resin component as the first organic binder is not particularly limited, and water-soluble organic polymers such as acrylic resins, acrylate latexes, rubber latexes, carboxymethyl cellulose or polyvinyl alcohol, and thermoplastic resins such as styrene resins. And thermosetting resins such as epoxy resins, and acrylic resins are particularly preferable.

The glass transition point of the polymer resin component as the first organic binder in the present invention is preferably 5 ° C. or lower, more preferably −10 ° C. or lower, and further preferably −30 ° C. or lower. preferable. When the glass transition point of the first organic binder is 5 ° C. or less, the binder film made of the first organic binder covering the surface of the inorganic fibers becomes soft, and the holding sealing material having excellent flexibility and can do. Therefore, the holding sealing material is easily bent when the holding sealing material is wound around the exhaust gas treating body. Moreover, since the binder film | membrane which consists of a 1st organic binder is formed in the surface of an inorganic fiber, even if it is a case where an inorganic fiber fractures | ruptures, scattering of an inorganic fiber can be suppressed with a binder film | membrane. .

The aggregate constituting the holding sealing material of the present invention is obtained by aggregating the second organic binder and the inorganic binder.

The polymeric resin component as a 2nd organic binder is not specifically limited, The thing similar to the polymeric resin component as a 1st organic binder can be used suitably.
The glass transition point of the polymer resin component as the second organic binder is preferably 5 ° C. or less, more preferably −10 ° C. or less, and further preferably −30 ° C. or less. . When the glass transition point of the second organic binder is 5 ° C. or less, the strength of the aggregate can be increased while maintaining the flexibility of the aggregate to which inorganic particles as the inorganic binder are added. Therefore, when the inorganic fibers are in contact with each other, it is difficult for the aggregates to drop and the inorganic fibers to slip, and the surface pressure is easily improved.

The inorganic binder constituting the aggregate in the present invention refers to a solid component obtained by removing a solvent from an inorganic particle solution such as an inorganic sol dispersion solution.
The inorganic sol dispersion solution (inorganic particle solution) is not particularly limited, and examples thereof include alumina sol and silica sol.
As the inorganic particles, alumina particles derived from alumina sol and silica particles derived from silica sol are preferable.

The particle diameter and particle diameter distribution of the inorganic particles constituting the inorganic binder are not particularly limited, but the particle diameter of the inorganic particles is preferably smaller than the fiber diameter of the inorganic fibers. Specifically, the particle diameter of the inorganic particles is preferably 0.005 to 10 μm, more preferably 0.01 to 5 μm, and still more preferably 0.01 to 1 μm.

The total content of the first organic binder and the second organic binder is preferably 2% by weight or less, and more preferably 0.1 to 2% by weight of the entire holding sealing material.
When the total content of the first organic binder and the second organic binder exceeds 2% by weight of the entire holding sealing material, the effect of improving the surface pressure and suppressing fiber scattering is almost unchanged, and the heat of exhaust gas The amount of cracked gas generated by the gas increases, which may adversely affect the surrounding environment.

The content of the inorganic binder is preferably 2% by weight or less, more preferably 0.1 to 2% by weight of the entire holding sealing material.
When the content of the inorganic binder exceeds 2% by weight of the entire holding sealing material, the holding sealing material gradually becomes hard and the flexibility is lowered. When the holding sealing material is bent and wound around the exhaust gas treatment body, the holding sealing material is bent, so that the winding property cannot be wound along the outer periphery of the exhaust gas treatment body or the surface of the holding sealing material is cracked. Concerned. On the other hand, even if the content of the inorganic binder exceeds 2% by weight of the entire holding sealing material, the effect of improving the surface pressure is hardly observed. Further, excessive use of the inorganic binder is not preferable from the viewpoint of manufacturing cost.

The average height of the convex portions formed by the aggregates constituting the holding sealing material of the present invention is preferably smaller than the average fiber diameter of the inorganic fibers including the binder film. Specifically, the average height of the convex portions is preferably 0.05 to 11 μm, more preferably 0.1 to 6 μm, and further preferably 0.2 to 4 μm.

The size of the aggregate constituting the holding sealing material of the present invention in the aggregate solution is preferably 0.1 to 11 μm, more preferably 0.2 to 6 μm, and 0.2 to 4 μm. More preferably it is.
When the size of the aggregate exceeds 11 μm, when the aggregate solution is brought into contact with the mat in the step of applying the aggregate to the mat, the aggregate is too large and is clogged on the surface of the mat. It becomes difficult to make the aggregate contact evenly on the surface of each inorganic fiber present in the direction. Furthermore, if the aggregate is too large, the number of aggregates is reduced, and the convex portion formed by the aggregate formed on the surface of the inorganic fiber may be formed on only a part of the inorganic fiber. As a result, the effect of improving the surface pressure of the holding sealing material may be insufficient. Moreover, when the size of the aggregate is less than 0.1 μm, the aggregate is too small, the catch between the inorganic fibers becomes weak, and the surface pressure of the holding sealing material may not be improved.

The inorganic fiber constituting the holding sealing material of the present invention is not particularly limited, but is composed of at least one selected from the group consisting of alumina fiber, silica fiber, alumina silica fiber, mullite fiber, biosoluble fiber, and glass fiber. It is preferable that it be changed according to the characteristics required for the mat, such as heat resistance and wind erosion resistance, and use large diameter fibers or fiber lengths that can meet the environmental regulations of each country. Is preferred.
In the case where the inorganic fiber is at least one of alumina fiber, silica fiber, alumina silica fiber, and mullite fiber, the heat resistance is excellent, and therefore the exhaust gas treating body is exposed to a sufficiently high temperature. However, no alteration or the like occurs, and the function as the holding sealing material can be sufficiently maintained. In addition, when the inorganic fiber is a biosoluble fiber, when producing an exhaust gas purification device using a holding sealing material, even if the scattered inorganic fiber is inhaled, it is dissolved in the living body. Will not harm your health.

Among these, low crystalline alumina inorganic fibers are desirable, and low crystalline alumina inorganic fibers having a mullite composition are more preferable. In addition, inorganic fibers containing a spinel compound are more preferable. A highly crystalline alumina material is hard and brittle, so it is not suitable for a mat used as a cushioning material.

Further, in the case of an inorganic fiber containing a low crystalline alumina material and a spinel type compound, the crystallization ratio is preferably in the range of 0.1 to 30%, and more preferably in the range of the crystallization rate of 0.4 to 20%. Mats made of inorganic fibers in this range have a high rebound force and a high restoration surface pressure after a durability test. However, when the crystallization ratio is less than 0.1% or exceeds 30%, the repulsive force and the restoring surface pressure are rapidly decreased. The method for measuring the crystallization rate can be calculated from the integral intensity ratio of the mullite diffraction line (2θ = 26.4 °) and the γ-alumina diffraction line (2θ = 45.4 °).

The mat constituting the holding sealing material can be obtained by various methods. For example, the mat can be produced by a needling method or a papermaking method.

In order to exhibit the entangled structure, the inorganic fibers constituting the mat obtained by the needling method have a certain average fiber length, for example, the average fiber length of the inorganic fibers is preferably 1 to 150 mm, More preferably, it is 10-80 mm.
If the average fiber length of the inorganic fiber is less than 1 mm, the fiber length of the inorganic fiber is too short, so that the entanglement between the inorganic fibers becomes insufficient, the wrapping property to the exhaust gas treating body is lowered, and the holding sealing material is easily broken. Become. On the other hand, if the average fiber length of the inorganic fibers exceeds 150 mm, the fiber length of the inorganic fibers is too long, so the number of fibers constituting the holding sealing material is reduced, and the denseness of the mat is lowered. As a result, the shear strength of the holding sealing material is lowered.

The average fiber length of the inorganic fibers constituting the mat obtained by the papermaking method is preferably 0.1 to 20 mm.
When the average fiber length of the inorganic fiber is less than 0.1 mm, the fiber length of the inorganic fiber is too short, so that the characteristics as a fiber are no longer substantially exhibited. Entanglement does not occur and it becomes difficult to obtain sufficient surface pressure. Further, if the average fiber length of the inorganic fibers exceeds 20 mm, the fiber length of the inorganic fibers is too long, so that the entanglement between the inorganic fibers in the slurry solution in which the inorganic fibers are dispersed in the water in the paper making process becomes too strong. Inorganic fiber tends to accumulate non-uniformly when formed into a fiber-like aggregate.
The fiber length is measured by using tweezers for both the needling method and the papermaking method so that the inorganic fiber is not broken from the mat, and the fiber length is measured using an optical microscope. Here, the average fiber length was determined by extracting 300 inorganic fibers and measuring the fiber length. If the inorganic fibers cannot be removed from the mat without breaking, the mat is degreased, the degreased mat is put into water, and the inorganic fibers are collected so as not to break while loosening the entanglement between the inorganic fibers. .

As the holding sealing material of the present invention, a biosoluble fiber may be used as the inorganic fiber. The biosoluble fiber is, for example, an inorganic fiber made of at least one compound selected from the group consisting of an alkali metal compound, an alkaline earth metal compound, and a boron compound in addition to silica and the like.
Since the biosoluble fiber made of these compounds is easily dissolved even when taken into the human body, the mat containing these inorganic fibers is excellent in safety to the human body.

The specific composition of the biosoluble fiber is 60 to 85% by weight of silica and 15 to 40% by weight of at least one compound selected from the group consisting of alkali metal compounds, alkaline earth metal compounds and boron compounds. % Composition. The silica refers to SiO or SiO ₂ .

Examples of the alkali metal compound include sodium and potassium oxides, and examples of the alkaline earth metal compound include magnesium, calcium, strontium, and barium oxides. Examples of the boron compound include boron oxide.

In the composition of the biosoluble fiber, when the silica content is less than 60% by weight, it is difficult to produce by a glass melting method, and it is difficult to fiberize.
In addition, when the content of silica is less than 60% by weight, the content of flexible silica is small, so that it is structurally fragile, and is easily soluble in physiological saline, an alkali metal compound, an alkaline earth metal compound, and Since the ratio of at least one compound selected from the group consisting of boron compounds is relatively high, the biosoluble fiber tends to be too soluble in physiological saline.

On the other hand, when the content of silica exceeds 85% by weight, the ratio of at least one compound selected from the group consisting of an alkali metal compound, an alkaline earth metal compound, and a boron compound is relatively low, so that it is biosoluble. Fibers tend to be too difficult to dissolve in saline.
The silica content is calculated by converting the amounts of SiO and SiO ₂ into SiO ₂ .

Further, when the content of at least one compound selected from the group consisting of an alkali metal compound, an alkaline earth metal compound and a boron compound exceeds 40% by weight in the composition of the biosoluble fiber, it is produced by the glass melting method. Difficult to fiberize. Further, when the content of at least one compound selected from the group consisting of an alkali metal compound, an alkaline earth metal compound and a boron compound exceeds 40% by weight, it is structurally fragile and the biosoluble fiber becomes physiological saline. It becomes too easy to dissolve.

The solubility of the biosoluble fiber in the present invention in physiological saline is preferably 30 ppm or more. This is because if the solubility of the biosoluble fiber is less than 30 ppm, it is difficult for the fiber to be discharged from the body when the inorganic fiber is taken into the body, which is not preferable for health.

Among the inorganic fibers constituting the holding sealing material of the present invention, the glass fibers are glassy fibers mainly composed of silica and alumina and made of calcia, titania, zinc oxide or the like in addition to alkali metals.

In the holding sealing material of the present invention, when the first organic binder and the second organic binder are burned away by heat, a convex portion is formed by the inorganic binder over the entire surface of the inorganic fiber.
FIG. 3A is an SEM photograph before firing of the holding sealing material of the present invention, and FIG. 3B is an SEM photograph after firing of the holding sealing material of the present invention.
In this specification, when the binder film is burned out, it means heating in the atmosphere at 600 ° C. for 1 hour unless otherwise specified.

As shown to Fig.3 (a), the binder membrane | film | coat and the aggregate are formed in the surface of the inorganic fiber which comprises the holding sealing material of this invention, and the convex part is formed with the aggregate. Since the binder film is formed on the surface of the inorganic fiber, the binder film can prevent scattering of the inorganic fiber even when the inorganic fiber is broken. Furthermore, aggregates protrude from the binder film. Therefore, when the inorganic fibers are in contact with each other, the convex portions due to the aggregates are caught, and the surface pressure of the holding sealing material can be improved by increasing the frictional resistance between the inorganic fibers.

The structure having the convex portion shown in FIG. 3A is also maintained in FIG. In FIG. 3 (b), a convex portion is formed on the entire surface of the inorganic fiber, and this convex portion is the one in which the inorganic binder constituting the aggregate remains without being decomposed by firing. Accordingly, even after the first organic binder and the second organic binder are burned out, the convex portions on the surface of the inorganic fibers are maintained by the inorganic binder in the aggregate, and the inorganic fibers can slip. Therefore, it is easy to improve the surface pressure.

The shape and the like of the holding sealing material of the present invention will be described.
FIG. 4 is a perspective view schematically showing an example of the holding sealing material of the present invention. As shown in FIG. 4, the holding sealing material of the present invention has a predetermined longitudinal length (hereinafter, indicated by an arrow L in FIG. 4), a width (indicated by an arrow W in FIG. 4), and a thickness ( In FIG. 4, it may be composed of a flat plate-like mat having a substantially rectangular shape in plan view having an arrow T).

In the holding sealing material shown in FIG. 4, the convex portion 111 is formed on the first end which is one of the end portions on the length direction side of the holding sealing material, and the other end A recess 112 is formed at a certain second end. The convex portion 111 and the concave portion 112 of the holding sealing material are shaped so as to be fitted to each other when the holding sealing material is wound around the exhaust gas treatment body in order to assemble an exhaust gas purification device to be described later.
Note that “substantially rectangular in plan view” is a concept including a convex portion and a concave portion. In addition, the substantially rectangular shape in plan view includes a shape whose corners have an angle other than 90 °.

The holding sealing material of the present invention is preferably subjected to needle punching treatment. By entanglement of the inorganic fibers by the needle punching process, the entanglement between the inorganic fibers is strengthened and the surface pressure is easily improved.

The needle punching process can be performed using a needle punching apparatus. The needle punching device is composed of a support plate that supports a sheet of inorganic fiber precursor, and a needle board that is provided above the support plate and can reciprocate in the piercing direction (thickness direction of the base mat). ing. A large number of needles are attached to the needle board. The inorganic fiber precursor is configured by moving the needle board with respect to the sheet-like material of the inorganic fiber precursor placed on the support plate, and inserting and removing a large number of needles with respect to the sheet-like material of the inorganic fiber precursor. The fibers can be intertwined in a complex manner. The number of needle punching processes and the number of needles may be changed according to the target bulk density and the basis weight.

The thickness of the holding sealing material is not particularly limited, but is preferably 2 to 20 mm. When the thickness of the holding sealing material exceeds 20 mm, the flexibility of the holding sealing material is lost, so that it becomes difficult to handle the holding sealing material when it is wound around the exhaust gas treating body. Further, the holding sealing material is likely to cause creases and cracks.
When the thickness of the holding sealing material is less than 2 mm, the surface pressure of the holding sealing material is not sufficient to hold the exhaust gas treating body. For this reason, the exhaust gas treating body is easily dropped off. Further, when a volume change occurs in the exhaust gas treating body, the holding sealing material is difficult to absorb the volume change of the exhaust gas treating body. Therefore, cracks and the like are likely to occur in the exhaust gas treating body.

The surface pressure of the holding sealing material of the present invention can be measured by the following method using a surface pressure measuring device.
For the measurement of the surface pressure, a hot surface pressure measuring device provided with a heater on the portion of the plate that compresses the mat is used, and the bulk density (GBD) of the sample becomes 0.3 g / cm ³ at room temperature. Compress until The contact pressure at that time is defined as the firing front pressure. Thereafter, it was held for 10 minutes. The bulk density of the sample is a value determined by “bulk density = sample weight / (sample area × sample thickness)”.
Next, while the sample is compressed, the compression is released until the bulk density becomes 0.273 g / cm ³ while raising the temperature to 900 ° C. on one side and 650 ° C. on one side at a rate of 40 ° C./min. And a sample is hold | maintained for 5 minutes in the state of temperature single side 900 degreeC, single side 650 degreeC, and bulk density 0.273g / cm < ³ >.
Thereafter, compression is performed at a rate of 1 inch (25.4 mm) / min until the bulk density becomes 0.3 g / cm ³ . Measurement of the load at a bulk density of 0.273 g / cm ³ after 1000 times of releasing the compression until the bulk density becomes 0.273 g / cm ³ and compressing the bulk density to 0.3 g / cm ^3. To do. By dividing the obtained load by the area of the sample, the surface pressure (kPa) is obtained and set as the surface pressure after firing.

The scattering property of the inorganic fibers constituting the holding sealing material of the present invention can be measured by the following procedure.
First, the holding sealing material is cut out to 100 mm × 100 mm to obtain a scattering test sample 210. About this sample for a scattering test, the scattering rate of an inorganic fiber can be measured using the measuring apparatus shown to Fig.5 (a) and (b).
Fig.5 (a) is a side view which shows typically an example of the measuring apparatus for measuring the dispersibility of an inorganic fiber, FIG.5 (b) is a measuring apparatus for measuring the dispersibility of an inorganic fiber. FIG. 6 is a plan view schematically showing a part of a sample support arm that constitutes the structure. As shown in FIG. 5A, the test apparatus 200 is connected to the upper ends of two support columns 260 provided vertically on a base 250 so that the sample support arm 270 can rotate within a predetermined range. Has been. Further, a vertical wall member 290 is fixed between the two support columns at a position where it can collide with the sample support arm.
Moreover, FIG.5 (b) is the top view which showed typically an example of the sample support arm part of the measuring apparatus for measuring the scattering property of inorganic fiber. As shown in FIG. 5B, the other end of the sample support arm 270 is fixed by a sample fixing member 280 that connects the ends of the sample support arm 270 to each other. There is another sample fixing member 280 at a position away from the sample fixing member 280 connected to the end of the sample supporting arm 270 in the direction of the support 260, and the two sample supporting arms 270 are at least Connected by sample fixing members at two locations.

At a position where the angle between the sample support arm 270 and the column 260 becomes 90 °, the sample support arm 270 is locked by a predetermined locking mechanism, and the scattering test sample 210 is fixed to the sample fixing member 280 by the clip 220. When the lock of the sample support arm 270 is released, the sample support arm 270 and the scattering test sample 210 start dropping in the direction toward the base 250 to which the support column 260 is fixed. Connection between the sample support arm 270 and the support column 260 When the sample support arm 270 and the column 260 become parallel, the sample support arm 270 collides with the vertical wall member 290. Due to this collision, a part of the inorganic fibers constituting the scattering test sample 210 is broken and scattered. Therefore, the weight of the scattering test sample before and after the collision is measured, and the fiber scattering rate can be obtained using the following formula (1). :
Fiber scattering rate (% by weight) = (weight of sample for scattering test before test−weight of sample for scattering test after test) / (weight of sample for scattering test before test) × 100 (1)

Weight per unit area of the holding sealing material of the present invention (weight per unit area) is not particularly limited, is preferably 200~4000g / ^{m 2,} and more preferably 1000 to 3000 g / ^{m 2.} When the basis weight of the holding sealing material is less than 200 g / m ² , the holding force is not sufficient, and when the basis weight of the holding sealing material exceeds 4000 g / m ² , the bulk of the holding sealing material is difficult to decrease. Therefore, when manufacturing an exhaust gas purification apparatus using such a holding sealing material, the exhaust gas treating body is likely to drop off.

Further, the bulk density of the holding sealing material of the present invention (the bulk density of the holding sealing material before winding) is not particularly limited, but is preferably 0.1 to 0.3 g / cm ³ . When the bulk density of the holding sealing material is less than 0.1 g / cm ³ , the entanglement of the inorganic fibers is weak and the inorganic fibers are easily peeled off, so that it is difficult to keep the shape of the holding sealing material in a predetermined shape.
On the other hand, when the bulk density of the holding sealing material exceeds 0.3 g / cm ³ , the holding sealing material becomes hard, so that the winding property around the exhaust gas treating body is lowered and the holding sealing material is easily broken.

The holding sealing material of the present invention may further contain an expansion material. The expansion material preferably has a characteristic of expanding in the range of 400 to 800 ° C.
When the holding sealing material contains an expanding material, the holding sealing material expands in the range of 400 to 800 ° C., so that the holding strength is maintained even in a high temperature range exceeding 700 ° C. where the strength of the glass fiber is lowered. The holding force at the time of using as a sealing material can be improved.

Examples of the expanding material include vermiculite, bentonite, phlogopite, pearlite, expandable graphite, and expandable fluoride mica. These expanding materials may be used alone or in combination of two or more.
Although the addition amount of an expansion material is not specifically limited, It is preferable that it is 10-50 weight% with respect to the total weight of a holding sealing material, and it is preferable that it is 20-30 weight%.

When the holding sealing material of the present invention is used as a holding sealing material for an exhaust gas purification device, the number of holding sealing materials constituting the exhaust gas purification device is not particularly limited, and may be a single holding sealing material or coupled to each other. A plurality of holding sealing materials may be used. The method for bonding a plurality of holding sealing materials is not particularly limited, and examples thereof include a method for bonding holding sealing materials by sewing and a method for bonding holding sealing materials with an adhesive tape or an adhesive. .

Next, the manufacturing method of the holding sealing material of this invention is demonstrated.

The method for producing a holding sealing material of the present invention includes a mat preparing step for preparing a mat made of inorganic fibers, a binder solution preparing step for preparing a binder solution consisting of a first organic binder, and a second organic bond. An aggregate solution preparation step of mixing an agent and an inorganic binder to form an aggregate composed of the second organic binder and the inorganic binder, and bringing the binder solution and the aggregate solution into contact with the mat A solution contact step of forming a binder film made of the first organic binder on the surface of the inorganic fiber, and forming a convex part made of the aggregate on the binder film; and the binder A drying step of drying the mat in contact with the solution and the aggregate solution.

Below, each process which comprises the manufacturing method of the holding sealing material of this invention is demonstrated.

(A) Mat Preparation Step In the method for manufacturing a holding sealing material of the present invention, first, a mat preparation step for preparing a mat made of inorganic fibers is performed.
The mat constituting the holding sealing material can be obtained by various methods. For example, the mat can be produced by a needling method or a papermaking method.
In the case of the needling method, for example, it can be produced by the following method. That is, first, for example, an inorganic fiber precursor is prepared by spinning a spinning mixture using a basic aluminum chloride aqueous solution and silica sol as raw materials by a blowing method. Subsequently, the inorganic fiber precursor is compressed to produce a continuous sheet-like material having a predetermined size, subjected to needle punching treatment, and then subjected to firing treatment to obtain an average fiber diameter of 3 to 10 μm. The preparation of the mat made of the alumina silica fiber is completed.

In the case of the paper making method, inorganic fibers such as alumina fibers and silica fibers, inorganic particles, and water are mixed so that the content of the inorganic fibers in the raw material liquid becomes a predetermined value, and mixed by stirring with a stirrer. Prepare the solution. The mixed solution may contain a colloidal solution made of a polymer compound or a resin as necessary. Then, after pouring a liquid mixture into the molding machine in which the mesh for filtration was formed in the bottom face, the raw material sheet | seat is produced by dehydrating the water in a liquid mixture through a mesh. Thereafter, the preparation of the mat is completed by heat-compressing and drying the raw material sheet under predetermined conditions.
In the case of the papermaking method, the fiber length of the inorganic fiber is shorter than that of the needling method, and therefore it is necessary to maintain the sheet strength with a binder such as an inorganic binder or an organic binder. In order to maintain the sheet strength necessary for winding around the exhaust gas treatment body or assembling the exhaust gas purification device, an organic binder, an inorganic binder, or the like may be appropriately added to the mixed liquid before molding. .

(B) Binder solution preparation step Next, a step of preparing a binder solution by dispersing the first organic binder in a solvent is performed. A binder solution in which the first organic binder is dispersed in the solvent can be prepared by adding the first organic binder to the solvent and stirring sufficiently.

The first organic binder used in the above (b) binder solution preparation step is not particularly limited, and those described in the explanation of the holding sealing material of the present invention can be used. Omitted.

The solvent used in the binder solution preparation step is not particularly limited, and examples thereof include aqueous organic solvents such as methanol and ethanol, water, and the like. From the viewpoint of production cost, it is preferable to use water.

In the (b) binder solution preparation step, the concentration of the first organic binder is not particularly limited, but it is preferable to use a liquid diluted to about 0.2 to 20% by weight in terms of solid content.

In the (b) binder solution preparation step, the glass transition point of the first organic binder is not particularly limited, but is preferably 5 ° C. or lower, more preferably −10 ° C. or lower, and −30 More preferably, it is not higher than ° C.

In the (b) binder solution preparation step, a pH adjuster for adjusting the pH of the binder solution may be added as necessary.

(C) Aggregate solution preparation step Next, an aggregate solution preparation for preparing a solution containing an aggregate in which the second organic binder and the inorganic binder are aggregated by mixing the second organic binder and the inorganic binder. Perform the process.
The method for preparing the aggregate solution is not particularly limited as long as the second organic binder and the inorganic binder can be aggregated. For example, a solution in which the second organic binder is dispersed in a solvent (second The organic binder solution can be prepared by adding a solution (inorganic binder solution) in which an inorganic binder is dispersed in a solvent, and adding an aggregating agent as necessary.

The inorganic binder solution used in the above (c) aggregate solution preparation step is not particularly limited, and those described in the explanation of the holding sealing material of the present invention can be used, and alumina sol, silica sol or the like can be used. it can.

In the (c) aggregate solution preparation step, the concentration of the inorganic binder is not particularly limited, but it is preferable to use a solution in which the concentration of the inorganic binder is thinned to about 0.2 to 20% by weight in terms of solid content.

The second organic binder used in the above (c) aggregate solution preparation step is not particularly limited, and since the one described in the explanation of the holding sealing material of the present invention can be used, the detailed explanation thereof is as follows. Omitted.

Although the density | concentration of the 2nd organic binder solution in the said (c) aggregate solution preparatory process is not specifically limited, The density | concentration of a 2nd organic binder is 0.2-20 weight% in conversion of solid content. preferable.

It does not specifically limit as a solvent used at the said (c) aggregate solution preparation process, For example, the thing similar to the solvent used at the said (b) binder solution preparation process can be used.

In the (c) aggregate solution preparation step, the glass transition point of the second organic binder is not particularly limited, but is preferably 5 ° C. or lower, more preferably −10 ° C. or lower, and −30 More preferably, it is not higher than ° C.

In the (c) aggregate solution preparation step, a pH adjuster for adjusting the pH of the aggregate solution may be added as necessary.

(D) Solution contact step Next, a solution contact step is performed in which the binder solution and the aggregate solution are brought into contact with the mat.
In this solution contact step, the method of bringing the mat into contact with the binder solution and the aggregate solution is not particularly limited. For example, the mat is bonded to the inorganic fibers in the mat by impregnating the mat with the binder solution and the aggregate solution. The binder solution and the aggregate solution may be contacted, and the binder solution and the aggregate solution are dropped onto the inorganic fibers in the mat by dropping the binder solution and the aggregate solution on the mat by a method such as curtain coating. They may be contacted, and the binder solution and the agglomerate solution may be sprayed and sprayed onto the mat as in spray coating.
The order of contacting the binder solution and the aggregate solution is not particularly limited, and the aggregate solution may be contacted after the binder solution is contacted and the inorganic fibers are dried, or after the contact with the binder solution. The inorganic fibers may not be dried and subsequently contacted with the aggregate solution, or the mixture of the binder solution and the aggregate solution may be contacted at once.
By removing the solvent from the mat that has been brought into contact with the binder solution and the aggregate solution, it is possible to form a convex portion and a binder film on the inorganic fibers constituting the mat.
In the desolvation treatment, it is preferable to adjust the amount of the binder solution applied to 100 parts by weight of the inorganic fibers constituting the mat to be 50 to 200 parts by weight.

When contacting the aggregate solution, it is preferable to contact the inorganic fiber while dispersing the aggregate in the solution by stirring the aggregate solution. By bringing the aggregate solution into contact with the inorganic fibers while stirring, precipitation of the aggregate can be prevented, and further, the size of the aggregate can be suppressed from becoming too large.

In the above (d) solvent contact step, when the binder solution is brought into contact with the mat and when the aggregate solution is brought into contact with the mat, a solvent removal treatment for removing the solvent in the binder solution and the aggregate solution is performed. May be.
The solvent removal treatment is not particularly limited as long as the solvent contained in the mat can be removed. For example, the solvent can be removed by means such as compression, rotation, suction, and reduced pressure.

(E) Drying step Thereafter, a drying step is performed in which the mat with which the binder solution and the aggregate solution are brought into contact is dried at a temperature of about 110 to 140 ° C., and the first organic binder, the second organic binder, By drying the organic binder and the inorganic binder, and removing the solvent in the binder solution and the aggregate solution, a binder film made of the first organic binder is formed on the surface of the inorganic fiber, and further, Aggregates made of the second organic binder and the inorganic binder protrude from the binder film to form convex portions. Therefore, the holding sealing material of the present invention can be manufactured by such a manufacturing method. In the drying step, the mat can be dried using a method such as hot air drying, ventilation drying, or compression drying with a hot plate.
If drying with a hot plate is performed, the distribution of the binder solution and the aggregate solution impregnated in the mat becomes uniform in the thickness direction, which is advantageous for a mat for papermaking with poor thickness formability.

Thereafter, in order to obtain a holding sealing material having a shape having convex portions and concave portions as shown in FIG. 4, a cutting step of cutting the holding sealing material into a predetermined shape may be further performed.

The holding sealing material can be cut using a Thomson blade, a guillotine blade, a laser, a water jet, or the like. The above cutting method may be used as appropriate depending on the situation, but a Thomson blade or a guillotine blade is preferable if mass processing is important, and a laser or a water jet is preferable if cutting accuracy is important.

In the method for producing a holding sealing material according to the present invention, a binder solution made of a first organic binder and an aggregate solution containing an aggregate made of a second organic binder and an inorganic binder are brought into contact with the mat. By bringing the binder solution made of the first organic binder into contact with the mat, a binder film made of the first organic binder is formed on the inorganic fiber surface. Further, by bringing the aggregate solution into contact with the mat, an aggregate composed of the second organic binder and the inorganic binder is formed so as to protrude from the binder film.
Therefore, even if the inorganic fiber is broken, the scattering of the inorganic fiber can be suppressed by the binder film. Furthermore, a convex part is formed in the binder film | membrane by the aggregate which consists of a 2nd organic binder and an inorganic binder protrudes from a binder film | membrane. For this reason, when the inorganic fibers are in contact with each other, the protrusions are hooked to cause frictional resistance, thereby strengthening the entanglement between the inorganic fibers. As a result, the surface pressure of the holding sealing material is improved.

The holding sealing material of the present invention can be used as a holding sealing material for an exhaust gas purification device.

Hereinafter, the exhaust gas purifying apparatus of the present invention will be described.
The exhaust gas purifying apparatus of the present invention includes a metal casing, an exhaust gas treatment body accommodated in the metal casing, and a holding member that is wound around the exhaust gas treatment body and disposed between the exhaust gas treatment body and the metal casing. An exhaust gas purifying apparatus including a sealing material, wherein the holding sealing material is a holding sealing material manufactured by the holding sealing material of the present invention or the manufacturing method of the holding sealing material of the present invention.

FIG. 6 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 6, the exhaust gas purification apparatus 100 of the present invention includes a metal casing 130, an exhaust gas treatment body 120 accommodated in the metal casing 130, and a holding disposed between the exhaust gas treatment body 120 and the metal casing 130. And a sealing material 110.
The exhaust gas treatment body 120 has a columnar shape in which a large number of cells 125 are arranged in parallel in the longitudinal direction with a cell wall 126 therebetween. Note that an end of the metal casing 130 is connected to an introduction pipe for introducing the exhaust gas discharged from the internal combustion engine and an exhaust pipe for discharging the exhaust gas that has passed through the exhaust gas purification device to the outside, if necessary. It will be.

Next, the exhaust gas treatment body (honeycomb filter) and the metal casing constituting the exhaust gas purification apparatus of the present invention will be described.
In addition, about the structure of the holding sealing material which comprises an exhaust gas purification apparatus, since it has already demonstrated as the holding sealing material of this invention, it abbreviate | omits.

The material of the metal casing constituting the exhaust gas purifying apparatus of the present invention is not particularly limited as long as it is a metal having heat resistance, and specifically, metals such as stainless steel, aluminum, iron and the like can be mentioned.

As the shape of the metal casing constituting the exhaust gas purifying apparatus of the present invention, a clamshell shape or the like can be suitably used in addition to a substantially cylindrical shape.

Subsequently, the exhaust gas treating body constituting the exhaust gas purifying apparatus will be described.
FIG. 7 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention.

The exhaust gas treatment body 120 shown in FIG. 7 is a honeycomb structure made of a columnar ceramic material in which a large number of cells 125 are provided side by side with cell walls 126 therebetween. One end of each cell 125 is sealed with a sealing material 128.

When either end of the cell 125 is sealed, when viewed from one end of the exhaust gas treating body 120, the cells whose end are sealed and the cells that are not sealed are alternately arranged. It is preferable that

The cross-sectional shape obtained by cutting the exhaust gas treatment body 120 in a direction perpendicular to the longitudinal direction is not particularly limited, and may be a substantially circular shape or a substantially elliptical shape, or a substantially polygonal shape such as a substantially triangular shape, a substantially rectangular shape, a substantially pentagonal shape, or a substantially hexagonal shape. There may be.

The cross-sectional shape of the cells 125 constituting the exhaust gas treating body 120 may be a substantially triangular shape, a substantially quadrangular shape, a substantially pentagonal shape, a substantially hexagonal shape or the like, or may be a substantially circular shape or a substantially elliptical shape. Further, the exhaust gas treating body 120 may be a combination of cells having a plurality of cross-sectional shapes.

The material constituting the exhaust gas treatment body 120 is not particularly limited, and non-oxides such as silicon carbide and silicon nitride, and oxides such as cordierite and aluminum titanate can be used. Of these, non-oxide porous fired bodies such as silicon carbide or silicon nitride are particularly preferable.
Since these porous fired bodies are brittle materials, they are easily broken by a mechanical impact or the like. However, in the exhaust gas purifying apparatus of the present invention, the holding sealing material 110 is interposed around the side surface of the exhaust gas treatment body 120 to absorb the impact, so that the exhaust gas treatment body 120 is cracked by a mechanical impact or a thermal shock. It can be prevented from occurring.

The exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention may carry a catalyst for purifying exhaust gas, and the supported catalyst is preferably a noble metal such as platinum, palladium, rhodium, etc. Then, platinum is more preferable. In addition, as other catalysts, for example, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can be used. These catalysts may be used alone or in combination of two or more. When these catalysts are supported, it is easy to burn and remove PM, and toxic exhaust gas can be purified.

The exhaust gas treatment body constituting the exhaust gas purification apparatus of the present invention may be an integrally formed honeycomb structure made of cordierite or the like, or may be made of silicon carbide or the like, and has a large number of through holes. May be a collective honeycomb structure in which a plurality of columnar honeycomb fired bodies arranged in parallel in the longitudinal direction with partition walls are bundled together through a paste mainly containing ceramic.

In the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention, the end of the cell may not be sealed without providing the cell with the sealing material. In this case, the exhaust gas treating body functions as a catalyst carrier that purifies harmful gas components such as CO, HC, or NOx contained in the exhaust gas by supporting a catalyst such as platinum.

In the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention, an outer peripheral coat layer may be formed on the outer peripheral surface. When the outer peripheral coating layer is formed on the outer peripheral surface of the exhaust gas treating body, the outer peripheral portion of the exhaust gas treating body can be reinforced, the shape can be adjusted, and the heat insulation can be improved. In addition, the outer peripheral surface of the exhaust gas treatment body refers to a side surface portion of the exhaust gas treatment body that is columnar.

A case where the exhaust gas passes through the exhaust gas purification apparatus 100 having the above-described configuration will be described below with reference to FIG.
As shown in FIG. 6, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 100 (in FIG. 6, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by an arrow) is an exhaust gas treatment body (honeycomb filter) 120. Flows into one cell 125 opened in the exhaust gas inflow end face 120a and passes through the cell wall 126 separating the cells 125. At this time, PM in the exhaust gas is collected by the cell wall 126, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 125 opened in the exhaust gas treatment side end face 120b and is discharged to the outside.

Next, the manufacturing method of the exhaust gas purification apparatus of the present invention will be described.

FIG. 8 is a perspective view schematically showing an example of the manufacturing method of the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 8, the exhaust gas treating body and the holding sealing material constituting the exhaust gas purifying apparatus of the present invention are wound around the exhaust gas treating body 120 to form a wound body 140. Next, by accommodating the wound body 140 in the metal casing 130, the exhaust gas purifying apparatus of the present invention is obtained.

Next, as a method of accommodating the wound body 140 in the metal casing 130, for example, a press-fitting method in which the exhaust gas treatment body 120 having the holding sealing material 110 disposed around it to a predetermined position inside the metal casing 130 is press-fitted ( Stuffing method), a sizing method (swaging type) that compresses from the outer peripheral side so as to reduce the inner diameter of the metal casing 130, and the metal casing in a shape that can be separated into parts of the first casing and the second casing, For example, a clamshell method in which the wound body 140 is placed on the first casing and then covered with the second casing and sealed.
When the wound body is accommodated in the metal casing by the press-fitting method (stuffing method), the inner diameter of the metal casing (the inner diameter of the portion accommodating the exhaust gas treating body) may be slightly smaller than the outer diameter of the wound body. preferable.

The exhaust gas purifying apparatus of the present invention may be composed of a plurality of holding sealing materials of two or more layers joined together. The method for bonding a plurality of holding sealing materials is not particularly limited, and examples thereof include a method for bonding holding sealing materials by sewing and a method for bonding holding sealing materials with an adhesive tape or an adhesive. .

Through these steps, the exhaust gas purification apparatus of the present invention is manufactured.

In the exhaust gas purification apparatus of the present invention, a holding sealing material is interposed between the exhaust gas treating body and the metal casing, and the holding sealing material is different from the holding sealing material of the present invention and the holding sealing material of the present invention. It is the holding sealing material manufactured by the manufacturing method of the aspect or this invention.
In the holding sealing material manufactured by the method for manufacturing a holding sealing material of the present invention, a binder film made of the first organic binder is formed on the surface of the inorganic fiber. Therefore, even if the inorganic fiber is broken, the scattering of the inorganic fiber can be suppressed by the binder film. Furthermore, since the aggregate protrudes from the binder film, when the inorganic fibers are brought into contact with each other, the convex portion due to the aggregate is caught and the frictional resistance between the inorganic fibers is increased. As a result, the surface pressure of the holding sealing material can be improved. In addition, when the binder film and the organic binder in the aggregate are burned out by the heat of the exhaust gas, a convex portion derived from the inorganic binder in the aggregate is formed on almost the entire surface of the inorganic fiber. Since the convex portion derived from the inorganic binder is formed on the entire surface of the inorganic fiber, the fibers are less likely to slip, can maintain a high surface pressure, and suppress damage to the exhaust gas treating body. Can do.

Hereinafter, the operation and effect of the holding sealing material, the manufacturing method of the holding sealing material, and the exhaust gas purification apparatus of the present invention will be described.

(1) In the holding sealing material of the present invention, a binder film made of the first organic binder is formed on the surface of the inorganic fiber. Therefore, even if the inorganic fiber is broken, the scattering of the inorganic fiber can be suppressed by the binder film. Therefore, when manufacturing the exhaust gas purification device by press-fitting the exhaust gas treatment body around which the holding sealing material of the present invention is wound into a metal casing, scattering of inorganic fibers can be suppressed.

(2) In the holding sealing material of the present invention, an aggregate composed of the second organic binder and the inorganic binder protrudes from the binder film to form a plurality of convex portions. For this reason, when the inorganic fibers come into contact with each other, the convex portions are hooked to cause frictional resistance, and the inorganic fibers are difficult to slip. As a result, the surface pressure of the holding sealing material is improved.

(3) In the manufacturing method of the holding sealing material of the present invention, the holding sealing material having the above configuration can be easily manufactured.

(4) In the exhaust gas purification apparatus of the present invention, since the holding sealing material is interposed between the exhaust gas treating body and the metal casing, it is possible to prevent the exhaust gas from leaking and to form the holding sealing material. Aggregates composed of the second organic binder and inorganic binder protrude from the surface of the fiber to form a plurality of convex portions, so the surface pressure of the holding sealing material is high, and the exhaust gas treatment body is stably held. can do.

(5) Further, in the exhaust gas purification apparatus of the present invention, the first organic binder in the binder film and the first in the aggregate are obtained by circulating high-temperature exhaust gas through the exhaust gas treatment body constituting the exhaust gas purification apparatus. 2 organic binder burns out. Even if the first organic binder in the binder film and the second organic binder in the aggregate are burned out, the inorganic binder in the aggregate is not burned out. Since the convex part derived from the agent is formed and the frictional resistance between the inorganic fibers is increased, the surface pressure can be kept high.

(Example)
Examples in which the present invention is disclosed more specifically are shown below. In addition, this invention is not limited only to these Examples.

Example 1
(A) Mat preparation step First, a mat made of inorganic fibers was prepared by the following procedure.

(A-1) Spinning Step Inorganic fibers after firing with respect to a basic aluminum chloride aqueous solution prepared so that the Al content is 70 g / l and Al: Cl = 1: 1.8 (atomic ratio) A silica sol was blended so that the composition ratio in Al ₂ O ₃ : SiO ₂ = 72: 28 (weight ratio) was added, and an organic polymer (polyvinyl alcohol) was added in an appropriate amount to prepare a mixed solution.
The obtained mixed solution was concentrated to obtain a spinning mixture, and the spinning mixture was spun by a blowing method to prepare an inorganic fiber precursor.

(A-2) Compression step The inorganic fiber precursor obtained in the step (a-1) was compressed to produce a continuous sheet-like material.

(A-3) Needle punching process The needle punching process body was produced by performing a needle punching process continuously on the sheet-like material obtained in the above-mentioned process (a-2) under the following conditions.
First, a needle board to which needles were attached at a density of 21 pieces / cm ² was prepared. Next, the needle board is disposed above the one surface of the sheet-like material, and the needle board is moved up and down once along the thickness direction of the sheet-like material to perform needle punching treatment. Was made. At this time, the needle was penetrated until the barb formed at the tip of the needle completely penetrated the surface on the opposite side of the sheet-like material.

(A-4) Firing step Inorganic fiber containing 72 parts by weight and 28 parts by weight of alumina and silica by continuously firing the needle punched body obtained in the step (a-3) at a maximum temperature of 1250 ° C. A fired sheet-like material consisting of The average fiber diameter of the inorganic fibers was 5.1 μm, and the minimum value of the inorganic fiber diameter was 3.2 μm. The fired sheet material thus obtained has a bulk density of 0.15 g / cm ³ and a basis weight of 1500 g / m ² .

(A-5) Cutting step The fired sheet-like material obtained in the step (a-4) was cut to produce a mat made of inorganic fibers.

(B) Binder solution preparation step An acrylate latex (Nipol LX854E manufactured by Nippon Zeon Co., Ltd., solid content concentration: 45 wt.%) In which acrylic rubber having a glass transition point of −10 ° C. is dispersed in water as the first organic binder solution. %)) Was added to water to prepare a binder solution prepared such that the first organic binder was 1% by weight in terms of solid content with respect to the total amount of the binder solution.

(C) Aggregate solution preparation step As the second organic binder solution, acrylate latex (Nipol LX854E manufactured by Nippon Zeon Co., Ltd., solid content concentration: 45) in which acrylic rubber having a glass transition point of −10 ° C. is dispersed in water. %)), And as an inorganic binder solution, an alumina colloid solution (alumina sol) (Alumina sol 550 (solid content concentration: 15% by weight) manufactured by Nissan Chemical Industries, Ltd.) is used as a solid content conversion with respect to the whole solution. The second organic binder and inorganic binder are mixed and stirred so that the second organic binder: inorganic binder = 1 wt%: 2 wt%, and left to stand for a while, so that the second organic binder and the inorganic binder are An agglomerated aggregate solution was prepared.

(D) Solution contact step (d-1) Solution mixing step The aggregate solution and binder solution prepared in the above (b) aggregate solution preparation step and (c) binder solution preparation step are mixed in equivalent amounts, First organic binder: second organic binder: inorganic binder = 0.5 wt%: 0.5 wt%: 1 in terms of solids with respect to the total amount of the mixed solution of the collecting solution and the binder solution It prepared so that it might become weight%.

(D-2) Contacting step While the mixed solution of the aggregate solution and the binder solution obtained in the (d-1) solution mixing step is sufficiently stirred, the above (a) mat contacting step is performed by the curtain coating method. The resulting mat was contacted.

(D-3) Solvent removal step The mat with the aggregate solution and the binder solution obtained in the above (d-2) solution contact step is set in a suction dehydrator and dehydrated, whereby the first organic The contents of the binder, the second organic binder, and the inorganic binder are 0.5% by weight, 0.5% by weight, and 1% by weight, respectively, of the entire holding sealing material after the completion of the drying step (e) described later. It adjusted so that it might become.

(E) Drying Step The mat obtained in the step (d) solution contact step was dried with hot air by blowing hot air at a temperature of 130 ° C. and a wind speed of 2 m / s to obtain a holding sealing material.

(Comparative Example 1)
(B) Without performing the binder solution preparatory step, (c) In the aggregate solution preparatory step, the second organic binder and the inorganic binder are converted into the second organic bond in terms of solid content with respect to the entire solution. Agent: Inorganic binder = 1% by weight: 1% by weight. (D) In the solution contact step, only the aggregate solution is brought into contact with the mat, whereby the first organic binder, the second Example 1 except that the contents of the organic binder and the inorganic binder were adjusted to 0% by weight, 1% by weight, and 1% by weight of the whole holding sealing material after the completion of the drying step (e), respectively. A holding sealing material according to Comparative Example 1 was manufactured by the same method.

(Comparative Example 2)
(C) The first organic binder, the second organic binder, and the inorganic binder are obtained by bringing the mat into contact with only the binder solution in the solution contact step without performing the aggregate solution preparation step. In the same manner as in Example 1, except that the content of (e) was adjusted to 1% by weight, 0% by weight, and 0% by weight after the completion of the drying step, respectively, Comparative Example A holding sealing material according to 2 was produced.

(Measurement of content (% by weight) of first organic binder, second organic binder and inorganic binder)
The holding sealing material obtained in each example and each comparative example was collected as a constant weight sample, an organic solvent (tetrahydrofuran) in which the first organic binder and the second organic binder were dissolved was selected, and the soxhlet extractor was used. Then, the first organic binder and the second organic binder (both together, also simply referred to as organic binder) were dissolved and separated from the sample. At this time, the inorganic binder contained in the dissolved organic binder is also separated from the sample, and the organic binder and the inorganic binder are recovered in an organic solvent.
The organic solvent composed of the organic binder and the inorganic binder was placed in a crucible, and the organic solvent was evaporated and removed by heating.
The residue remaining in the crucible was regarded as the total weight of the organic binder and the inorganic binder relative to the holding sealing material, and the content (% by weight) relative to the weight of the holding sealing material was calculated.
Furthermore, the crucible was heat-treated at 600 ° C. for 1 hour to burn off the organic binder. Since the inorganic binder remained in the crucible, this was regarded as the content (% by weight) of the inorganic binder with respect to the total of the organic binder and the inorganic binder, and the content was calculated. The remainder is the content of the organic binder (the total content of the first organic binder and the second organic binder) (% by weight).

In this example and this comparative example, the content of the organic binder and the inorganic binder can be measured by the above method. However, when the organic binder is a crosslinkable resin, all the crosslinkable resin is eluted with an organic solvent. Difficult to do. Therefore, in that case, the inorganic fibers constituting the mat (those in which the binder film and aggregates are not formed) are collected and the weight (A1) is measured, and the same conditions as in this example and this comparative example are obtained. After adhering the organic binder and the inorganic binder to the inorganic fiber, it is sufficiently dried and the weight is measured (A2). Thereafter, heat treatment is performed at 600 ° C. for 1 hour, and the weight is further measured (A3). Since A2-A3 is the weight of the organic binder and A3-A1 is the weight of the inorganic binder, the content (% by weight) of the organic binder and the inorganic binder relative to the weight of the sample can be calculated.

(Confirmation of binder film)
About Example 1 and each comparative example, the surface of the inorganic fiber which comprises the holding sealing material before baking is observed with a fluorescent X-ray analyzer, and the binder film is the one in which carbon is detected from most of the surface of the inorganic fiber. Was determined to be formed. The results are shown in Table 1. In Table 1, the case where it was determined that the binder film was formed was indicated by ◯, and the case where it was not formed was indicated by ×.

(Confirmation of aggregates)
About Example 1 and each comparative example, the inorganic fiber which comprises the holding sealing material before baking was observed with the scanning electron microscope, and it was confirmed whether the convex part was formed with the aggregate. The results are shown in Table 1. In Table 1, the case where convex portions are formed by aggregates is indicated by ◯, and the case where convex portions are not formed is indicated by ×.

(Surface pressure test)
A surface pressure test was performed on the holding sealing materials of the examples and comparative examples.
The surface pressure test method using the surface pressure measuring device is as described in the description of the holding sealing material of the present invention.
The results are shown in Table 1.

(Inorganic fiber scattering test)
Using the holding sealing material produced in each example and comparative example, the inorganic fiber scattering test was performed.
The method of the inorganic fiber scattering test is as described in the description of the present invention.
The results are shown in Table 1.

As shown in Table 1, when the holding sealing material according to Example 1 is used, a high surface pressure of 170 kPa or more before firing and 30 kPa or more after firing can be secured, and the fiber scattering rate is 0.1 weight. % Could be suppressed.
On the other hand, in the holding sealing material according to Comparative Example 1, a binder film was not formed, and scattering of inorganic fibers could not be sufficiently suppressed. Furthermore, the surface pressure before and after firing was not sufficient.
In the holding sealing material of Comparative Example 2, since no inorganic binder was added, aggregates were not formed. Therefore, the scattering of inorganic fibers could be sufficiently suppressed, but the surface pressure after firing was greatly reduced.
From the above, the holding sealing material of the present invention having the binder film and the protrusions from which the aggregates protruded from the binder film is excellent in suppressing the scattering of fibers and in the surface pressure before and after firing. I found out.

DESCRIPTION OF SYMBOLS 10 Inorganic fiber 20 Binder film | membrane 21 Polymer resin component 30, 35, 36, 37 as a 1st organic binder Aggregate 31 Polymer resin component 32 as a 2nd organic binder Inorganic particle as an inorganic binder DESCRIPTION OF SYMBOLS 100 Exhaust gas purification apparatus 110 Holding sealing material 120 Exhaust gas treatment body 130 Metal casing

Claims (10)

A holding sealing material made of inorganic fibers,
A binder film composed of a first organic binder is formed on the surface of the inorganic fiber,
An agglomerate composed of a second organic binder and an inorganic binder protrudes from the binder film to form a plurality of convex portions. The holding sealing material according to claim 1, wherein the aggregate is configured by dispersing inorganic particles as the inorganic binder in a polymer resin component as the second organic binder. The holding sealing material according to claim 1 or 2, wherein an average height of the convex portions is smaller than an average fiber diameter of the inorganic fibers including the binder film. The holding sealing material according to any one of claims 1 to 3, wherein a total content of the first organic binder and the second organic binder is 2% by weight or less of the entire holding sealing material. The holding sealing material according to any one of claims 1 to 4, wherein the content of the inorganic binder is 2% by weight or less of the entire holding sealing material. The holding sealing material according to any one of claims 1 to 5, wherein the polymer resin component as the first organic binder and the polymer resin component as the second organic binder are acrylic resins. 7. The glass transition point (T _g ) of the polymer resin component as the first organic binder and the polymer resin component as the second organic binder is 5 ° C. or less. The holding sealing material according to 1. The holding sealing material according to any one of claims 1 to 7, wherein a needle punching process is performed. A mat preparation step of preparing a mat made of inorganic fibers;
A binder solution preparation step of preparing a binder solution for forming a binder film composed of a first organic binder on the surface of the inorganic fiber;
An aggregate solution preparation step of mixing a second organic binder and an inorganic binder to form an aggregate composed of the second organic binder and the inorganic binder;
By bringing the binder solution and the aggregate solution into contact with the mat, a binder film made of the first organic binder is formed on the surface of the inorganic fiber, and the aggregate is formed on the binder film. A solution contact step for forming a convex portion comprising:
The method for producing a holding sealing material according to any one of claims 1 to 8, further comprising a drying step of drying the mat in contact with the binder solution and the aggregate solution. A metal casing;
An exhaust gas treating body housed in the metal casing;
An exhaust gas purification apparatus comprising a holding sealing material wound around the exhaust gas treatment body and disposed between the exhaust gas treatment body and the metal casing,
The exhaust gas purification apparatus, wherein the holding sealing material is the holding sealing material according to any one of claims 1 to 8.