JP6298452B2 - Holding sealing material, manufacturing method of holding sealing material, and exhaust gas purification device - Google Patents

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.

As such a holding sealing material, there is known a holding sealing material obtained by impregnating a mat made of an inorganic fiber material with an aggregate composed of an organic binder and inorganic particles (for example, see Patent Document 1).

JP 2012-157809 A

The surface pressure of the holding sealing material is derived from the force of returning the original when the inorganic fibers constituting the holding sealing material receive stress. From this, when the friction between inorganic fibers is large, or when the inorganic fibers are bonded together, the surface pressure of the holding sealing material increases.
In the holding sealing material disclosed in Patent Document 1, agglomerates are attached only to some of the inorganic fibers constituting the mat. Therefore, the friction between inorganic fibers is small in the portion where the aggregate is not attached, and the effect of improving the surface pressure is not sufficiently exhibited. Therefore, the holding sealing material disclosed in Patent Document 1 has room for improving the surface pressure. Further, in the holding sealing material disclosed in Patent Document 1, when the organic binder is burned down by the heat of exhaust gas, the inorganic particles are present only on a part of the surface of the inorganic fiber. Therefore, there is room for improvement in the surface pressure after firing, and further improvement in the surface pressure has been desired.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a holding sealing material that can sufficiently satisfy the surface pressure characteristics required for the holding sealing material, and a method for manufacturing the holding sealing material. 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 has an inorganic fiber surface covered with a binder layer, and the binder layer contains an organic binder, inorganic particles, and a polymeric dispersant. It is characterized by including.

Since the holding sealing material of the present invention includes a polymer dispersant in the binder layer, aggregation of the organic binder and the inorganic particles in the binder layer is suppressed. By suppressing the aggregation of the organic binder, the binder layer containing the organic binder is formed over a wide range of the surface of the inorganic fiber. Furthermore, since the binder layer contains inorganic particles, the binder layer is excellent in tensile strength. Since the aggregation of the inorganic particles is suppressed by the polymer dispersant, the strength of the binder layer is increased over a wide range.
When the strength of the binder layer is weak, when the inorganic fibers come into contact with each other, the inorganic fibers slip with the peeling of the binder layer, and the surface pressure of the holding sealing material becomes low, but the strength of the binder layer is high. And the inorganic fibers are prevented from slipping, and the holding sealing material has a high surface pressure.

In the holding sealing material of the present invention, the inorganic particles of the binder layer are coated on the surface with the polymer dispersant, and the inorganic particles are dispersed in an organic binder component. Is preferred. When the surface of the inorganic particles is coated with the polymer dispersant, the inorganic particles are more effectively prevented from aggregating in the binder layer, and the inorganic particles are dispersed in the organic binder component. Therefore, the strength of the binder layer is more uniformly improved over a wide range of the surface of the inorganic fiber. Therefore, the holding sealing material has a higher surface pressure.

In the holding sealing material of the present invention, the inorganic particles and the organic binder are preferably contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the inorganic fibers. Furthermore, the inorganic particles and the organic binder are more preferably contained in an amount of 0.1 to 3 parts by weight with respect to 100 parts by weight of the inorganic fibers.
It is known that when an impact is applied to the holding sealing material, the inorganic fibers are broken by the impact and the broken inorganic fibers are scattered. Controlling such scattering of inorganic fibers is one of the characteristics required for the holding sealing material.
Here, when the binder layer is formed on the surface of the inorganic fiber, even if the inorganic fiber is broken at the portion where the binder layer is formed, the broken inorganic fiber is held together, so that the fibers are scattered. Is prevented.
When the content of the inorganic particles and the organic binder is less than 0.1 parts by weight with respect to 100 parts by weight of the inorganic fibers, the portion where the binder layer is formed is small, and the effect of suppressing scattering of the inorganic fibers is small. Become. Further, when the content of the inorganic particles and the organic binder exceeds 10 parts by weight with respect to 100 parts by weight of the inorganic fibers, the effect of suppressing scattering of the inorganic fibers and the effect of improving the surface pressure are almost the same. Therefore, the amount of decomposition gas generated by the heat of the exhaust gas increases, which may adversely affect the surrounding environment. Therefore, the content of the organic binder is preferably towards only small as possible, it is more preferably at most 3 parts by weight.

In the holding sealing material of the present invention, the polymer dispersant is preferably an anionic polymer dispersant. When the polymer-based dispersant is an anionic polymer-based dispersant, even if the surface of the inorganic particles is positively charged, the inorganic particles are offset by canceling the charge on the surface of the inorganic particles. It becomes easy to disperse.

In the holding sealing material of the present invention, the organic binder is preferably an acrylic resin. When the organic binder is an acrylic resin, the compatibility between the organic binder and the polymeric dispersant is easily increased in the binder layer, and thus the strength of the binder layer is easily improved by the anchor effect. .

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.

In the holding sealing material of the present invention, when the organic binder is burned off by heat, it is preferable that irregularities due to the inorganic particles are formed over the entire surface of the inorganic fiber.
By forming irregularities due to the inorganic particles over the entire surface of the inorganic fibers, the inorganic fibers become less slippery and the entanglement between the inorganic fibers becomes stronger. Therefore, it becomes easy to improve the surface pressure of the holding sealing material.

In the holding sealing material of the present invention, the binder layer is preferably formed on the entire surface of the inorganic fiber. By forming the binder layer on the entire surface of the inorganic fibers, friction when the inorganic fibers come into contact with each other is increased, and the surface pressure is easily improved.
Furthermore, when the binder layer is formed on the entire surface of the inorganic fiber, it is easy to suppress the inorganic fiber from being scattered even if the inorganic fiber breaks at any part.

Another aspect of the holding sealing material of the present invention is a mat preparation step for preparing a mat containing inorganic fibers, an inorganic particle solution and a polymer dispersant are mixed, and then mixed with an organic binder dispersed in water. A binder solution preparing step for preparing a binder solution, an applying step for applying the binder solution to the mat, and drying the mat to which the binder solution has been applied to dry the organic binder and the inorganic It is manufactured by a process including a drying process for drying particles.

By mixing the inorganic particle solution and the polymer dispersant, the surface of the inorganic particles is coated with the polymer dispersant. Here, by mixing an organic binder dispersed in water, the binder solution dispersed in the organic binder dispersed in water with the inorganic particles coated on the surface of the polymer dispersant. It becomes. Since the organic binder and the inorganic particles are dispersed in the binder solution, the organic binder and the inorganic particles easily spread over the entire surface of the inorganic fiber, and a high-strength binder layer is formed on the entire surface of the inorganic fiber. . For this reason, slipping of the inorganic fiber is prevented over the entire surface of the inorganic fiber, and the holding sealing material has a high surface pressure.
Furthermore, since the binder layer is formed on the entire surface of the inorganic fiber, it is easy to prevent the inorganic fiber from scattering even if the inorganic fiber breaks at any location.

In another aspect of the holding sealing material of the present invention, it is preferable to use an organic binder having a glass transition temperature of −5 ° C. or lower as the organic binder in the binder solution preparation step. A binder layer obtained by a binder solution using an organic binder having a glass transition temperature of −5 ° C. or lower has high strength of the binder layer, high film elongation, and excellent flexibility. For this reason, the holding sealing material is unlikely to break when the holding sealing material is wound around the exhaust gas treating body.
Moreover, since a binder layer does not become hard too much, it becomes easy to suppress scattering of inorganic fiber.

In another aspect of the holding sealing material of the present invention, in the binder solution preparation step, the binder solution is prepared so that the tensile strength of the binder layer obtained by drying the binder solution is 5.0 MPa or more. It is preferable. When the tensile strength of the binder layer is less than 5.0 MPa, when the inorganic fibers come into contact with each other, the binder layer may be peeled off and the inorganic fibers may slip, making it difficult to improve the surface pressure.

The manufacturing method of the holding sealing material of the present invention includes a mat preparation step of preparing a mat containing inorganic fibers, and an inorganic particle solution and a polymer dispersant are mixed, and then mixed with an organic binder dispersed in water. A binder solution preparing step for preparing a binder solution by the step, an applying step for applying the binder solution to the mat, and drying the mat to which the binder solution has been applied to dry the organic binder and inorganic particles. And a drying step for drying.
Since the polymer dispersant suppresses aggregation with the organic binder by coating the inorganic particles, the binder solution prepared in the binder solution preparing step is an organic binder and inorganic in water. A binder solution in which the particles are dispersed is obtained. Since the binder solution in which the organic binder and the inorganic particles are dispersed in water tends to spread over the entire surface of the inorganic fiber, the binder is applied to the entire surface of the inorganic fiber by applying the binder solution to the mat. A layer can be formed.
Therefore, in the manufacturing method of the holding sealing material of the present invention, the entire surface of the inorganic fiber is covered with the binder layer, and the sliding of the inorganic fiber is prevented over the entire surface of the inorganic fiber. A holding sealing material that is a sealing material that can suppress scattering of the inorganic fiber even when the inorganic fiber breaks at any location can be manufactured.

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 winding wound around the exhaust gas treatment body and disposed between the exhaust gas treatment body and the metal casing. An exhaust gas purifying apparatus comprising a sealing material, wherein the holding sealing material is the holding sealing material of the present invention.

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 purification apparatus including a sealing material, wherein the holding sealing material is a holding sealing material manufactured by the method for manufacturing a holding sealing material of the present invention.

Fig.1 (a) is the perspective view which showed typically an example of the binder layer which covers the inorganic fiber and inorganic fiber surface which comprise the holding sealing material of this invention, FIG.1 (b) is FIG.1 (a). It is an AA line sectional view in). FIG.1 (c) is the elements on larger scale of the binder layer of FIG.1 (b). FIG. 2 (a) is a scanning electron microscope (hereinafter also referred to as SEM) photograph of a binder layer formed on the surface of the inorganic fibers constituting the holding sealing material of the present invention, and FIG. It is a SEM photograph after heat-treating the holding | maintenance sealing material of this invention, and burning off an organic binder. FIG. 3 is a perspective view schematically showing an example of the holding sealing material of the present invention. Fig.4 (a) is a side view which shows typically an example of the measuring apparatus for measuring the dispersibility of an inorganic fiber, FIG.4 (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. 5 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention. FIG. 6 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. 7 is a perspective view schematically showing an example of a method for producing 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.
The holding sealing material of the present invention is characterized in that the surface of the inorganic fiber is covered with a binder layer, and the binder layer contains an organic binder, inorganic particles, and a polymer dispersant.

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

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
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.

In addition to alumina, the alumina fiber may contain additives such as calcia, magnesia, zirconia, and the like.
The composition ratio of the alumina silica fiber is preferably Al ₂ O ₃ : SiO ₂ = 60: 40 to 80:20 by weight ratio, and Al ₂ O ₃ : SiO ₂ = 70: 30 to 74:26. It is more preferable.

The average fiber length of the inorganic fibers is preferably 5 to 150 mm, and more preferably 10 to 80 mm.
If the average fiber length of the inorganic fiber is less than 5 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 treatment 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.

In the holding sealing material of the present invention, the inorganic fiber surface is covered with a binder layer.
Fig.1 (a) is the perspective view which showed typically an example of the binder layer which covers the inorganic fiber and inorganic fiber surface which comprise the holding sealing material of this invention, FIG.1 (b) is FIG.1 (a). It is an AA line sectional view in). FIG.1 (c) is the elements on larger scale of the binder layer of FIG.1 (b).

As shown in FIG. 1A and FIG. 1B, 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 layer 20. The binder layer 20 is preferably formed on the entire surface of the inorganic fiber 10. Furthermore, as shown in FIG. 1B, it is preferable that a plurality of inorganic fibers 10 are bonded through a binder layer 20.

As shown in FIG. 1C, the binder layer 20 includes inorganic particles 21, a polymer dispersant 23, and an organic binder component 22. Further, in the binder layer 20, the surface of the inorganic particles 21 is covered with the polymer dispersant 23, and the inorganic particles 21 covered with the polymer dispersant 23 are dispersed in the organic binder component 22. Yes.
When the surfaces of the inorganic particles 21 are covered with the polymer dispersant 23, the aggregation of the inorganic particles 21 in the binder layer 20 can be effectively suppressed. Furthermore, since the inorganic particles 21 are dispersed in the organic binder component 22, the tensile strength of the binder layer can be easily kept high.

The tensile strength of the binder layer in the present invention is preferably 5.0 MPa or more. When the tensile strength of the binder layer is less than 5.0 MPa, when the fibers come into contact with each other, the binder layer may be peeled off and the inorganic fibers may slip, making it difficult to improve the surface pressure.

For the tensile strength of the binder layer in the present invention, a tensile test is performed at a rate of 300 mm / min with an Instron type tensile tester at room temperature using a dumbbell-shaped test piece having a thickness of 0.4 mm. It is the tensile breaking strength of the above-mentioned specimen measured by this.
In addition, the said test piece can be produced by pouring the binder solution used as the raw material of a binder layer on a glass plate with a frame, leaving it to dry at room temperature, and making it into a film form.

The organic binder constituting the holding sealing material of the present invention is obtained by drying an organic binder (organic binder solution) dispersed in water.
Mentioned above is not particularly restricted but includes organic binders include acrylic resins, water-soluble organic polymers such as acrylate latex or rubber latex scan, thermoplastic resins such as styrene resins, thermosetting resins such as epoxy resin It is done.

The organic binder in the present invention is preferably contained in a solid content of 0.1 to 10 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of inorganic fibers constituting the holding sealing material. More preferably, it is more preferably 0.1 to 2 parts by weight.
When content of the said organic binder is less than 0.1 weight part with respect to 100 weight part of said inorganic fibers, the effect which suppresses scattering of inorganic fiber becomes small. When the amount exceeds 10 parts by weight, the effect of improving the surface pressure is hardly changed, and the amount of decomposition gas generated by the heat of the exhaust gas increases, which may adversely affect the surrounding environment. Therefore, the content of the organic binder is preferably as small as possible, preferably 10 parts by weight or less, more preferably 3 parts by weight or less, and still more preferably 2 parts by weight or less.

The glass transition temperature of the 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. When the glass transition temperature of the organic binder is −5 ° C. or lower, it is possible to obtain a holding sealing material having high film elongation and excellent flexibility while increasing the strength of the binder layer. Therefore, the holding sealing material is not easily broken when the holding sealing material is wound around the exhaust gas treating body.
Moreover, since a binder layer does not become hard too much, it becomes easy to suppress scattering of inorganic fiber.

The inorganic particles constituting the binder layer in the present invention refer to a solid component obtained by removing the 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.

It can be confirmed with a transmission electron microscope (hereinafter also referred to as TEM) that the organic binder component and the inorganic particles are dispersed in the binder layer in the present invention. An organic binder mainly composed of carbon atoms has a lower electron density than inorganic particles composed of alumina, silica, and the like, and easily transmits an electron beam. Therefore, the organic binder component is displayed brighter than the inorganic particles in the TEM image.

The inorganic particles in the present invention are preferably contained in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the inorganic fibers constituting the holding sealing material. More preferably, it is contained in 1 to 2 parts by weight.
When the content of the inorganic particles is less than 0.1 parts by weight with respect to 100 parts by weight of the inorganic fiber, the effect of improving the surface pressure tends to be small because the content of the inorganic particles is insufficient. When the amount exceeds 10 parts by weight, the effect of improving the surface pressure is hardly changed, but the binder layer may become too hard and it is difficult to suppress scattering of inorganic fibers. Therefore, in order to sufficiently suppress the scattering of inorganic fibers, the inorganic particles in the present invention are more preferably contained in an amount of 0.1 to 3 parts by weight with respect to 100 parts by weight of the inorganic fibers constituting the holding sealing material of the present invention. preferable.

Although it does not specifically limit about the particle diameter of the inorganic particle in this invention, It is preferable that the average particle diameter of an inorganic particle is 0.005-0.1 micrometer.

The number average molecular weight of the polymer dispersant in the present invention is not particularly limited, but is preferably 500 to 100,000.

The type of the polymeric dispersant in the present invention is not particularly limited, but polycarboxylic acid and / or salt thereof, naphthalene sulfonate formalin condensate and / or salt thereof, polyacrylic acid and / or salt thereof, polymethacrylic acid And / or salts thereof, hydrophilic synthetic polymers such as anionic polymer dispersants such as polyvinyl sulfonic acid and / or salt thereof, and nonionic polymer dispersants such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyethylene glycol. Substances: Natural hydrophilic polymer substances such as gelatin, casein and water-soluble starch; hydrophilic semi-synthetic polymer substances such as carboxymethyl cellulose.
Of these, hydrophilic synthetic polymer substances are preferable, and anionic polymer dispersants are more preferable. For example, when alumina particles derived from alumina sol are used as the inorganic particles, the surface of the alumina particles becomes cationic in the dispersion solution. Therefore, the anionic polymer dispersant is easily adsorbed on the alumina particles by electrostatic attraction. Furthermore, when the polymer dispersant is polar, the organic binder is preferably polar, such as an acrylic resin. This is because the compatibility of the organic binder and the polymeric dispersant is increased in the binder layer, and the strength of the binder layer is improved by the anchor effect.
Moreover, only one type of these polymer dispersants may be used, or a plurality of types may be used in combination. Further, it may be a polymer dispersant having both a structure showing properties as an anionic polymer dispersant and a structure showing properties as a nonionic polymer dispersant.

In addition, as the polymer dispersant in the present invention, an anionic polymer dispersant having a number average molecular weight of 500 to 100,000 is particularly preferable.

The content of the polymer dispersant in the present invention is preferably 50 to 1000 ppm with respect to the weight of the inorganic fibers constituting the holding sealing material. When the content of the polymer dispersant is less than 50 ppm with respect to the weight of the inorganic fiber, it is difficult to suppress aggregation of the inorganic particles and the organic binder in the binder solution. If it exceeds 1000 ppm, the effect of dispersing the inorganic particles in the organic binder component does not change, so excessive addition is not preferable.

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 containing 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.

In the present invention, the solubility of the biosoluble fiber in physiological saline is desirably 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 containing silica and alumina as main components and containing calcia, titania, zinc oxide and the like in addition to alkali metals.

In the holding sealing material of the present invention, when the organic binder is burned off by heat, irregularities due to inorganic particles are formed over the entire surface of the inorganic fiber.
FIG. 2 (a) is an SEM photograph of the binder layer formed on the surface of the inorganic fiber constituting the holding sealing material of the present invention, and FIG. 2 (b) is a heat treatment of the holding sealing material of the present invention. It is a SEM photograph after burning off an organic binder.
In the present specification, when the organic binder is burned out, it means heating in the atmosphere at 600 ° C. for 1 hour unless otherwise specified.

As shown to Fig.2 (a), the binder layer is formed in the surface of the inorganic fiber which comprises the holding | maintenance sealing material of this invention, and it has become the smooth surface where the unevenness | corrugation is not formed. On the other hand, in FIG. 2B, innumerable irregularities are formed over the entire surface of the inorganic fiber. This is presumably because the inorganic particles dispersed in the binder layer were exposed due to the burnout of the organic binder. When unevenness is formed by inorganic particles over the entire surface of the inorganic fiber, the inorganic fiber is caught by the unevenness when the inorganic fiber comes into contact after the organic binder is burned out, and the surface of the inorganic fiber is prevented from slipping. Therefore, it becomes easy to improve the surface pressure.

The shape and the like of the holding sealing material of the present invention will be described.
FIG. 3 is a perspective view schematically showing an example of the holding sealing material of the present invention. As shown in FIG. 3, the holding sealing material of the present invention has a predetermined longitudinal length (hereinafter, indicated by an arrow L in FIG. 3), a width (indicated by an arrow W in FIG. 3), and a thickness ( 3 may be configured by a flat mat having a substantially rectangular shape in plan view.

In the holding sealing material shown in FIG. 3, a convex portion is formed on the first end 111 which is one of the end portions on the length direction side of the holding sealing material, and at the other end. A concave portion is formed in a certain second end portion 112. 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 2.0 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 2.0 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 property 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.4 (a) and (b).
Fig.4 (a) is a side view which shows typically an example of the measuring apparatus for measuring the scattering property of inorganic fiber. As shown in FIG. 4A, the test apparatus 200 is connected to the upper ends of two support columns 260 vertically provided 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.4 (b) is the top view which showed typically an example of the sample support arm part which comprises the measuring apparatus for measuring the scattering property of inorganic fiber. As shown in FIG. 4B, 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. Unlocking the sample support arm 270, the sample support arm 270 and the test sample 210 begins to fall toward the base 250 that secure the pole 260, the connecting portion of the sample support arm 270 and support post 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 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 equation (5). :
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 (5)

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 0.10 to 0.30 g / cm ³ . When the bulk density of the holding sealing material is less than 0.10 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, if the bulk density of the holding sealing material exceeds 0.30 g / cm ³ , the holding sealing material becomes hard, the wrapping 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 more 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 manufacturing method of the holding sealing material of the present invention is suitable for the method of manufacturing the holding sealing material of the present invention.

The manufacturing method of the holding sealing material of the present invention includes a mat preparing step of preparing a mat containing inorganic fibers, an organic binder dispersed in water after preparing a solution in which inorganic particles and a polymeric dispersant are mixed. A binder solution preparing step of preparing a binder solution by mixing, an applying step of applying the binder solution to the mat, drying the mat to which the binder solution has been applied, and the organic binder and And a drying step of drying the inorganic particles.

(A) Mat preparation process In the manufacturing method of the holding sealing material of this invention, the mat preparation process which prepares the mat containing an inorganic fiber first 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 having an average fiber diameter of 3 to 10 μm 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 a needle punching process, and then subjected to a firing process to complete the preparation of the mat.

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 spin-dry | dehydrating the water in a liquid mixture through a mesh. Thereafter, the preparation of the mat is completed by heating and compressing the raw material sheet under predetermined conditions.

(B) Binder solution preparation step Next, after preparing a solution in which an inorganic particle solution and a polymer dispersant are mixed, the binder is mixed with an organic binder (organic binder solution) dispersed in water. A binder solution preparation step for preparing a solution is performed. First, by preparing a solution in which inorganic particles and a polymer dispersant are mixed, the surface of the inorganic particles is coated with the polymer dispersant. Subsequently, by mixing with an organic binder dispersed in water, the inorganic particles and the organic binder coated with the polymer dispersant can be dispersed in water.

The inorganic particle solution used in the binder solution preparation step of the present invention 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 and the like can be used.

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

In the binder solution preparation step of the present invention, the polymer dispersant to be mixed with the inorganic particle solution is not particularly limited, and those described in the explanation of the holding sealing material of the present invention can be used. Detailed description is omitted. The preferred range and type of number average molecular weight are also the same.

Although the density | concentration of the polymeric dispersing agent in the binder solution prepared in the binder solution preparation process of this invention is not specifically limited, It is preferable that it is 50-1000 ppm. When the concentration of the polymeric dispersant is less than 50 ppm, the amount of the polymeric dispersant is insufficient, so that it is difficult to suppress aggregation of the inorganic particles and the organic binder in the binder solution. Since the effect of dispersing is not changed, excessive addition is not preferable.

It does not specifically limit as an organic binder used at the binder solution preparation process of this invention, Since what was described in description of the holding sealing material of this invention can be used, the detailed description is abbreviate | omitted.

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

In the binder solution preparation step of the present invention, the glass transition temperature of the organic binder is not particularly limited, but is preferably −5 ° C. or lower, more preferably −10 ° C. or lower, and −30 ° C. or lower. More preferably it is.

In the binder solution preparation step of the present invention, the mixing ratio of the solution obtained by mixing the inorganic particles and the polymer dispersant and the organic binder solution is not particularly limited, but the inorganic particle solution and the polymer dispersant It is preferable to mix in the weight ratio of the solid content of the inorganic particles of the solution mixed with: the solid content weight of the organic binder in the organic binder solution = 3: 1 to 1: 3.

In the binder solution preparation step of the present invention, a pH adjuster for adjusting the pH of the binder solution may be added.

(C) Applying step Next, an applying step of applying the binder solution to the mat is performed.
In this application step, the method of bringing the mat into contact with the binder solution is not particularly limited. For example, the binder solution may be applied to the inorganic fibers in the mat by impregnating the mat with the binder solution. The binder solution may be applied to the inorganic fibers in the mat by dropping the binder solution onto the mat by a method such as curtain coating, and the binder solution is sprayed onto the mat and sprayed onto the mat as in spray coating. May be attached.
Furthermore, it is preferable to adjust the amount of the binder solution applied to 100 to 50 parts by weight of the inorganic fibers constituting the mat by dehydrating the mat to which the binder solution is applied. .

(D) Drying step Thereafter, the mat provided with the binder solution is dried at a temperature of about 110 to 140 ° C., and the organic binder and the inorganic particles are dried. By evaporating the solvent, the holding sealing material of the present invention in which the binder layer contains an organic binder, inorganic particles, and a polymer dispersant can be produced.

Thereafter, in order to obtain a holding sealing material having a shape having convex portions and concave portions as shown in FIG. 3, a cutting step of cutting the holding sealing material into a predetermined shape may be further performed.

In the method for producing a holding sealing material of the present invention, after mixing an inorganic particle solution and a polymeric dispersant, a binder solution prepared by mixing with an organic binder dispersed in water is applied to a mat composed of inorganic fibers. Give. By mixing the inorganic particle solution and the polymeric dispersant first, the surface of the inorganic particles is coated with the polymeric dispersant, and the aggregation of the organic binder and the inorganic particles is suppressed during the subsequent mixing with the organic binder. Is done. Moreover, aggregation of the organic binder is also suppressed by the effect of the polymer dispersant. Therefore, a binder solution is provided to the whole surface of an inorganic fiber by an application | coating process, and becomes a binder layer through a drying process.
The binder layer formed by the steps (a) to (d) has high tensile strength because it contains an organic binder, inorganic particles, and a polymer dispersant. Therefore, the surface pressure of the holding sealing material manufactured by the manufacturing method of the holding sealing material of the present invention is high. Furthermore, since the binder layer is formed on the entire surface of the inorganic fiber, the scattering of the inorganic fiber can be suppressed even if the inorganic fiber breaks at any part.

Next, another aspect of the holding sealing material of the present invention will be described.
Another aspect of the sealing material of the present invention is a holding sealing material manufactured by the method for manufacturing a holding sealing material of the present invention, a mat preparation step of preparing a mat containing inorganic fibers, an inorganic particle solution, and a polymer system A binder solution preparing step of preparing a binder solution by mixing with an organic binder dispersed in water after mixing the dispersant, an applying step of applying the binder solution to the mat, and the binder The mat provided with the solution is dried to produce the organic binder and the inorganic particles, and the drying step is performed.
Regarding each process for producing another embodiment of the holding sealing material of the present invention, each process described in the column of the manufacturing method of the holding sealing material of the present invention may be the same unless otherwise specified. it can.

In another aspect of the holding sealing material of the present invention, it is preferable to use an anionic polymer dispersant as the polymer dispersant in the binder solution preparation step.

In another embodiment of the holding sealing material of the present invention, in the above-mentioned binder solution preparation step, solids weight of the inorganic particles is preferred to prepare a binder solution to a 0.1 to 10 parts by weight, 0 it is more preferable that .1～3 to, prepare binder solution to a part by weight, still more preferably, prepare a binder solution so that 0.1 to 2 parts by weight. Further, the solid weight of the organic binder be prepared binder solution so that 0.1 to 10 parts by weight Preferably, manufactured by adjusting the binder solution to a 0.1 to 3 parts by weight and even more preferably it is made of regulating the binder solution to a 0.1 to 2 parts by weight. Moreover, it is preferable to use an organic binder having a glass transition temperature of −5 ° C. or lower, more preferably an organic binder of −10 ° C. or lower, and an organic binder of −30 ° C. or lower. Is more preferable.
In the binder solution preparation step, the binder solution is preferably prepared such that the tensile strength of the binder layer obtained by drying the binder solution is 5.0 MPa or more.

In another aspect of the holding sealing material of the present invention, the surface of the inorganic fiber is covered with a binder layer, and the binder layer preferably contains an organic binder, inorganic particles, and a polymer dispersant. .
By performing the mat preparatory step, the binder solution preparatory step, the application step, and the drying step, the inorganic fiber surface is covered with a binder layer, and the binder layer is organic binder, inorganic particles, and high A holding sealing material containing a molecular dispersant can be obtained.

In another aspect of the holding sealing material of the present invention, the binder layer is preferably formed on the entire surface of the inorganic fiber. Moreover, it is preferable that the surface of the inorganic particles is coated with a polymer dispersant and that the inorganic particles are dispersed in the organic binder component.
Moreover, when the organic binder is burned out by heat, it is preferable that the unevenness | corrugation by the said inorganic particle is formed over the whole surface of inorganic fiber.
In order to suppress aggregation of the inorganic particles and the organic binder in water, the polymer dispersant is a binder in which the organic binder and the inorganic particles are dispersed in water. Become a solution. Since the binder solution in which the organic binder and the inorganic particles are dispersed in water is likely to spread over the entire surface of the inorganic fiber, the binder is applied to the entire surface of the inorganic fiber by applying the binder solution to the mat. A layer can be formed. As a result, a holding sealing material in which the binder layer is formed on the entire surface of the inorganic fiber can be obtained.
Further, since the surface of the inorganic particles is coated with the polymer dispersant by mixing the inorganic particles and the polymer dispersant, the surface of the inorganic particles is coated with the polymer dispersant, and the inorganic It can be a holding sealing material in which particles are dispersed in an organic binder component. Furthermore, since the inorganic particles have a structure that spreads over the entire surface of the inorganic fiber, when the organic binder is burned off by heat, a holding sealing material in which irregularities due to the inorganic particles are formed over the entire surface of the inorganic fiber; can do.

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 comprising a sealing material, wherein the holding sealing material is manufactured by the holding sealing material of the present invention, another aspect of the holding sealing material of the present invention, or the method of manufacturing a holding sealing material of the present invention. Holding seal material.

FIG. 5 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 5, 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, a downsizing 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. 6 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention.

An exhaust gas treatment body 120 shown in FIG. 6 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 desirable. 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.

The 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. 5, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 100 (in FIG. 5, 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. 7 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. 7, 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 method ) 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. Therefore, the holding sealing material can exhibit a high surface pressure, and the exhaust gas treating body can be stably held. Furthermore, when the organic binder in the binder layer is burned out by the heat of the exhaust gas, irregularities due to inorganic particles are formed on the entire surface of the inorganic fiber. Since the unevenness due to the inorganic particles is formed on the entire surface of the inorganic fiber, the fibers are not easily slipped, a high surface pressure can be maintained, and damage to the exhaust gas treating body can be suppressed.
Furthermore, even if the inorganic fiber which comprises a holding | maintenance sealing material fractures | ruptures in any site | part, it can suppress that an inorganic fiber scatters.

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

(1) In the holding sealing material of the present invention, since the binder layer contains a polymer dispersant, aggregation of the organic binder and inorganic particles in the binder layer is suppressed. By suppressing the aggregation of the organic binder, the binder layer containing the organic binder is formed over a wide range of the surface of the inorganic fiber. Furthermore, since the binder layer contains inorganic particles, the binder layer is excellent in tensile strength. Since the aggregation of the inorganic particles is suppressed by the polymer dispersant, the strength of the binder layer is increased over a wide range.
When the strength of the binder layer is weak, when the inorganic fibers come into contact with each other, the inorganic fibers slip with the peeling of the binder layer, and the surface pressure of the holding sealing material becomes low, but the strength of the binder layer is high. And the inorganic fibers are prevented from slipping, and the holding sealing material has a high surface pressure.
Furthermore, in the holding sealing material of the present invention, since the binder layer is formed in a wide range on the surface of the inorganic fiber, the organic binder and the polymer dispersant in the binder layer are decomposed by the heat of the exhaust gas. In this case, the inorganic particles constituting the binder layer are exposed, and irregularities are formed in a wide range of the surface of the inorganic fiber. Therefore, the unevenness due to the inorganic particles increases the friction between the inorganic fibers, and even after the binder layer is decomposed by the heat of the exhaust gas, it becomes a holding sealing material having a high surface pressure.

(2) 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.

(3) In another aspect of the holding sealing material of the present invention, the same effects as the holding sealing material of the present invention can be achieved.

(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. Since the binder layer containing the polymer dispersant is formed on the fiber surface, the surface pressure of the holding sealing material is high, and the exhaust gas treating body can be stably held.

(5) Further, in the exhaust gas purifying apparatus of the present invention, the binder layer is burned out by the exhaust gas flowing through the exhaust gas treating body constituting the exhaust gas purifying apparatus. When the binder layer burns out, the inorganic particles constituting the binder layer are exposed and the friction between the inorganic fibers is improved, so that 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 containing 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 having an average fiber diameter of 5.1 μm.

(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. The baked sheet-like material which consists of was manufactured. 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 containing inorganic fibers.

(B) Binder solution preparation step (b-1) Organic binder solution preparation step Acrylate latex in which an acrylic rubber having a glass transition temperature of −10 ° C. is dispersed in water (Nipol LX854E manufactured by Nippon Zeon Co., Ltd. (solid content concentration) : 45 wt%)) and diluted with water to prepare an organic binder solution having a solid content concentration of 2 wt%.

(B-2) Inorganic binder solution preparation step Alumina colloid solution (alumina sol) (Alumina sol 550 (solid content concentration: 15 wt%) manufactured by Nissan Chemical Industries, Ltd.) was diluted with water, and an anionic polymer dispersant (San Nopco) Nopcosanto RFA) was added and stirred sufficiently to prepare an inorganic binder solution having a solid content concentration of inorganic particles of 2% by weight and a concentration of the anionic polymer dispersant of 500 ppm.

(B-3) Binder solution preparation step The organic binder solution obtained in the step (b-1) is added to the inorganic particle solution obtained in the step (b-2). = 1: 1 by weight and sufficiently stirred, the organic binder is 1% by weight in solid content, the inorganic particles are 1% by weight in solid content, and the concentration of the anionic polymer dispersant is 250 ppm. A binder solution was prepared.

(C) Application Step The binder solution obtained in the step (b) binder solution preparation step was applied to the mat obtained in the (a) mat preparation step by the curtain coating method.

(D) Drying step (d-1) Dehydration step The mat provided with the binder solution obtained in the step (c) applying step is sucked and dehydrated with a dehydrator so that the binder solution contains inorganic fibers. It was prepared so that 100 parts by weight was applied to 100 parts by weight.

(D-2) Drying Step The mat after the above (d-1) dehydration 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.

(Example 2)
Example 1 except that an acrylate latex (Nipol LX874 (solid content concentration: 45 wt%) manufactured by Nippon Zeon Co., Ltd.) in which an acrylic rubber having a glass transition temperature of −31 ° C. was dispersed in water was used as the organic binder. A holding sealing material was produced in the same manner as described above.

(Example 3)
(B-1) In the organic binder solution preparation step, the solid content concentration of the organic binder solution is 1.0% by weight. (B-2) Inorganic particle solids in the inorganic particle solution in the inorganic particle solution preparation step A holding sealing material was produced in the same manner as in Example 2 except that the partial concentration was changed to 3.0% by weight. At this time, the amount of the inorganic particles contained in the binder layer constituting the holding sealing material is 1.5 parts by weight with respect to 100 parts by weight of the inorganic fibers, and the amount of the organic binder is 100 parts by weight of the inorganic fibers. The amount was 0.5 part by weight.

Example 4
A holding sealing material was produced in the same manner as in Example 1 except that a polyethylene glycol dispersant (Emanon 1112 manufactured by Kao Corporation) was used as the polymer dispersant.

(Example 5)
A holding sealing material was produced in the same manner as in Example 1 except that a naphthalenesulfonic acid formalin condensate-based dispersant (Demol N manufactured by Kao Corporation) was used as the polymer dispersant.

(Example 6)
A holding sealing material was produced in the same manner as in Example 1 except that a polyvinyl alcohol dispersant (Denkapoval B-24N manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the polymer dispersant.

(Comparative Example 1)
(B-2) A holding sealing material was produced in the same manner as in Example 2 except that the polymer dispersant was not added in the inorganic particle solution preparation step.

(Comparative Example 2)
(B) A holding sealing material was produced in the same manner as in Example 2 except that the organic binder was not added in the binder solution preparation step.

(Comparative Example 3)
(B) A holding sealing material was produced in the same manner as in Example 2 except that inorganic particles were not added in the binder solution preparation step.

(Binder layer tensile strength test)
The binder solution prepared in each example and comparative example was poured into a glass plate with a frame, left to dry at room temperature, and then punched to prepare a dumbbell-shaped test piece having a thickness of 0.4 mm. Using this test piece, the tensile strength (tensile breaking strength) of the binder layer was measured by conducting a tensile test at a speed of 300 mm / min with an Instron type tensile tester. The results are shown in Table 1.

(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 materials according to Examples 1 to 6 are used, a high surface pressure of 150 kPa or more before firing and 35 kPa or more after firing can be secured, and scattering of inorganic fibers is further achieved. Can be suppressed to 0.2 wt% or less. Moreover, the tensile strength of the binder layer showed a high value of 5.0 MPa or more.
On the other hand, in Comparative Example 1 in which the polymeric dispersant is not included in the binder layer, the organic binder and the inorganic particles are aggregated in the binder solution, and the tensile strength of the binder layer is low. The contact pressure was also low.
Moreover, in the holding sealing material of Comparative Example 2, the binder layer could not be formed because the binder solution did not contain an organic binder. Therefore, scattering of inorganic fibers could not be suppressed.
Further, in the holding sealing material of Comparative Example 3, since the binder layer did not contain inorganic particles, the tensile strength of the binder layer was low, and the surface pressure was also low.

DESCRIPTION OF SYMBOLS 10 Inorganic fiber 20 Binder layer 21 Inorganic particle 22 Organic binder component 23 Polymer dispersing agent 100 Exhaust gas purification device 110 Holding sealing material 120 Exhaust gas treatment body 130 Metal casing

Claims (6)

A mat preparation step of preparing a mat containing inorganic fibers;
Mixing an inorganic particle solution using an alumina sol-derived alumina particle whose surface is cationic in the dispersion solution and an anionic polymer dispersant as inorganic particles, and then mixing with an organic binder dispersed in water A binder solution preparation step of preparing a binder solution by:
An application step of applying the binder solution to the mat;
A holding sealing material produced by a process including a drying process of drying the mat to which the binder solution has been applied to dry the organic binder and inorganic particles. In the binder solution preparation step, the organic binder, the holding sealing material according to claim 1 having a glass transition temperature used -5 ° C. or less of the organic binder. The holding sealing material according to claim 1 or 2 , wherein in the binder solution preparation step, the binder solution is prepared so that a tensile strength of a binder layer obtained by drying the binder solution is 5.0 MPa or more. A mat preparation step of preparing a mat containing inorganic fibers;
Mixing an inorganic particle solution using an alumina sol-derived alumina particle whose surface is cationic in a dispersion solution and an anionic polymer dispersant as inorganic particles, and then mixing with an organic binder dispersed in water A binder solution preparation step of preparing a binder solution by:
An application step of applying the binder solution to the mat;
A drying step of drying the mat provided with the binder solution to dry the organic binder and inorganic particles. 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 3 . 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 a holding sealing material manufactured by the method for manufacturing a holding sealing material according to claim 4 .