JP2015229955A - Holding seal material, and holding seal material manufacturing process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a holding seal material having a sufficient holding power even in a low temperature region of 600°C or lower.SOLUTION: A holding seal material is made of inorganic fibers loaded with an organic binder and contains no expansion material. The holding seal material is characterized in that the organic binder is lower by 4-80% in the tensile strength measured by a method according to JIS-K 6251 than the organic binder subjected to a heat treatment at 105°C.

Description

The present invention relates to a holding sealing material and a method for manufacturing the holding sealing material.

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.

Conventionally, in order to solve such a problem, a method of impregnating an organic binder that thermally decomposes at 600 ° C. to 1500 ° C. and expanding the thickness by 1.5 to 10 times when the organic binder is burned out (for example, Patent Document 1) and a method using a foamed binder that expands at 130 to 200 ° C. (for example, see Patent Document 2) are known.

JP-A-8-174687 JP 2010-112267 A

However, since the temperature in the casing immediately after engine startup in a general exhaust gas purification apparatus is about 300 ° C., the method disclosed in Patent Document 1 is at 600 ° C. or less where the organic binder does not decompose and expand in the mat thickness direction. Problems relating to damage and retention of the exhaust gas treating body have not been solved. Specifically, in the method disclosed in Patent Document 1, the organic binder is softened in a temperature range of about 300 ° C., so that the binding force between the fibers due to the binder is weakened. When the action is taken, the surface pressure of the holding sealing material is temporarily lowered, and the exhaust gas treating body may be displaced or dropped.

Further, in the method disclosed in Patent Document 2, since the foaming temperature of the foamed binder is too low, manufacturing must be performed in a temperature range in which the foamed binder does not foam, and much time is required for the binder drying process and the like. There was a problem that production efficiency was bad.

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 having a sufficient holding power even in a low temperature range of 600 ° C. or lower. Moreover, an object of this invention is to provide the manufacturing method which manufactures such a holding sealing material by a simple process.

In order to achieve the above object, the holding sealing material of the present invention is a holding sealing material made of inorganic fibers to which an organic binder is attached and does not contain an expansion material, and the organic binder complies with JIS-K 6251. The tensile strength measured by the method is 4 to 80% lower than the organic binder heat-treated at 105 ° C.

The tensile strength (hereinafter, also simply referred to as tensile strength) of the organic binder attached to the inorganic fibers constituting the holding sealing material of the present invention is 4 to 80% as compared with the organic binder heat-treated at 105 ° C. It is low. That is, it can be said that the organic binder constituting the holding sealing material of the present invention has a lower tensile strength than that heat-treated at 105 ° C., and part of the organic binder is deteriorated.
By using such an inorganic fiber to which an organic binder is attached as a holding sealing material, even when the organic binder is exposed to a low temperature environment of 600 ° C. or lower, for example, about 300 ° C., the organic binder is heated by the thermal shock. The force which binds each other weakens, and the holding sealing material expands. Therefore, a sufficient surface pressure can be exhibited even in a low temperature range of 600 ° C. or lower, and the exhaust gas treating body can be stably held. When the holding sealing material of the present invention is heated at 300 ° C. for 10 minutes, the thickness of the mat constituting the holding sealing material changes to 2.2 times or more.

That is, the holding sealing material of the present invention is a holding sealing material made of inorganic fibers to which an organic binder is attached, and does not contain an expansion material. A mat having a predetermined thickness constituting the holding sealing material is formed at 300 ° C. The thickness of the mat changes to 2.2 times or more when heated for 10 minutes.
When the holding sealing material of the present invention is heated at 300 ° C. for 10 minutes, the thickness of the mat constituting the holding sealing material changes to 2.2 times or more. Therefore, a sufficient surface pressure can be exhibited even in a low temperature range of 600 ° C. or lower, and the exhaust gas treating body can be stably held.

The holding sealing material of the present invention is a holding sealing material made of inorganic fibers to which an organic binder is attached, and the organic binder has a tensile strength measured by a method according to JIS-K 6251 of 0.7-2. 5 MPa is preferred.
When the tensile strength of the organic binder is 0.7 to 2.5 MPa, even in a low temperature range of 600 ° C. or lower, the force that restrains the holding sealing material is weakened, and the holding sealing material can be expanded.

In the holding sealing material of the present invention, the content of the organic binder is preferably 0.1 to 10% by weight in terms of solid content with respect to the total amount of the holding sealing material.
When the content of the organic binder is less than 0.1% by weight, when the holding sealing material is wound around the exhaust gas treating body, the holding sealing material may break, and when the content exceeds 10% by weight. Although the effect of exerting the surface pressure of the holding sealing material does not change, the amount of decomposition 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 glass transition temperature (T _g ) of the organic binder is preferably −5 ° 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 organic binder film formed by the organic binder. it can. Therefore, the holding sealing material is not easily broken when the holding sealing material is wound around the exhaust gas treating body. Moreover, since an organic binder film | membrane does not become hard too much, when an inorganic fiber fractures | ruptures, the effect which connects inorganic fibers can be exhibited, and scattering of an inorganic fiber can be suppressed.
In this specification, the glass transition temperature (Tg) of the polymer resin component constituting the organic binder is the glass transition temperature (Tg) of the polymer resin component constituting the organic binder that has not undergone the degradation treatment described below unless otherwise specified. _Tg ).

In the holding sealing material of the present invention, the polymer resin component constituting the organic binder is preferably an acrylic resin.
When the polymer resin component constituting the organic binder is an acrylic resin, the tensile strength of the organic binder film formed by the organic binder can be easily manipulated by a deterioration treatment described later, and the organic constituting the holding sealing material of the present invention Suitable as a binder.

In the holding sealing material of the present invention, the inorganic fiber may be 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. preferable.
When the inorganic fiber 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, heat resistance, wind erosion resistance, etc. The characteristics required for the holding sealing material can be sufficiently satisfied.

The manufacturing method of the holding sealing material of the present invention includes a mat preparation step of preparing a mat for holding sealing material made of inorganic fibers with an organic binder attached thereto, and heat-treating the mat with the organic binder attached at 140 ° C. or higher. A heat treatment step.

In the method for producing a holding sealing material of the present invention, the polymer resin component constituting the organic binder can be partially degraded by heat-treating the mat to which the organic binder is attached at 140 ° C. or higher. The organic binder composed of a polymer resin component partially deteriorated by the heat treatment cannot maintain the restraining force for restraining the inorganic fibers by thermal shock even at a low temperature of 600 ° C. or lower, for example, about 300 ° C. Therefore, the holding sealing material expands. Therefore, it is possible to manufacture a holding sealing material that can stably hold the exhaust gas treating body even in a low temperature range of 600 ° C. or lower.

In the method for producing a holding sealing material of the present invention, the inorganic fiber 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.
When the inorganic fiber 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 has characteristics such as heat resistance and wind erosion resistance. A sufficiently satisfactory holding sealing material can be manufactured.

In the manufacturing method of the holding sealing material of the present invention, the organic binder preferably has a polymer resin component composed of an acrylic resin, and is preferably an emulsion.
When the polymer resin component constituting the organic binder is an acrylic resin, the strength of the organic binder film formed by the organic binder can be easily improved, and a holding sealing material excellent in flexibility can be manufactured.
In addition, when the organic binder is an emulsion, the emulsion easily covers the entire surface of the inorganic fiber, and it becomes easy to form a film of the organic binder on the entire surface of the inorganic fiber. It is an excellent way to do it.

In the method for producing a holding sealing material of the present invention, the glass transition temperature (T _g ) of the polymer resin component constituting the organic binder is preferably −5 ° C. or lower.
To produce a holding sealing material having high film elongation and excellent flexibility while increasing the strength of the organic binder film formed by the organic binder when the glass transition temperature of the organic binder is −5 ° C. or lower. Can do. Therefore, the holding sealing material is not easily broken when the holding sealing material is wound around the exhaust gas treating body. Moreover, since an organic binder film | membrane does not become hard too much, when an inorganic fiber fractures | ruptures, the effect which connects inorganic fibers can be exhibited, and scattering of an inorganic fiber can be suppressed.

FIG. 1 is a perspective view schematically showing an example of the holding sealing material of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus. FIG. 3 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus. FIG. 4 is a diagram schematically illustrating an example of a method for manufacturing an exhaust gas purification device.

(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 sealing material of the present invention will be described.
The holding sealing material of the present invention is a holding sealing material made of inorganic fibers to which an organic binder is attached, and the organic binder is heat-treated at 105 ° C. with a tensile strength measured by a method according to JIS-K 6251. It is characterized by being 4 to 80% lower than the above organic binder.

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

In the holding sealing material of the present invention, an organic binder is attached to inorganic fibers.

The organic binder used in the present invention is not particularly limited, but is an acrylic resin, acrylate latex, rubber latex, water-soluble organic polymer such as carboxymethyl cellulose or polyvinyl alcohol, thermoplastic resin such as styrene resin, epoxy resin, etc. And thermosetting resins are preferable, and acrylic resins are preferable.
When the polymer resin component constituting the organic binder is an acrylic resin, the strength of the organic binder film formed by the organic binder can be easily manipulated by a deterioration treatment described later, and the organic binder constituting the holding sealing material of the present invention Is suitable.

The holding sealing material of the present invention preferably contains an organic binder in an amount of 0.1 to 10% by weight in terms of solid content with respect to the weight of the entire holding sealing material, and preferably contains 1 to 9% by weight. More preferably, the content is 4 to 8% by weight.
When the content of the organic binder is less than 0.1% by weight, the holding sealing material may not be sufficiently flexible, and cracks occur when the holding sealing material is wound around the exhaust gas treatment body. There are things to do. On the other hand, when the content of the organic binder exceeds 10% by weight, the amount of decomposition gas generated by the heat of exhaust gas increases, which may adversely affect the surrounding environment.

The glass transition temperature of the organic binder 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, the strength of the film formed by the organic binder can be increased, and thus a holding sealing material having excellent flexibility can be obtained. Therefore, the holding sealing material is not easily broken when the holding sealing material is wound around the exhaust gas treating body. Moreover, since the film | membrane formed with an organic binder does not become hard too much, it becomes easy to suppress scattering of inorganic fiber.

The organic binder constituting the holding sealing material of the present invention has a tensile strength measured by a method according to JIS-K 6251 that is 4 to 80% lower than that of the organic binder heat-treated at 105 ° C. The tensile strength of the organic binder is preferably 10 to 80% lower, more preferably 20 to 80% lower than that obtained by heat treatment at 105 ° C.
That is, the organic binder constituting the holding sealing material of the present invention has a tensile strength lower by 4 to 80% by performing a predetermined deterioration treatment as compared with the case of heat treatment at 105 ° C.
When such an organic binder is attached to inorganic fibers, the holding sealing material of the present invention has a mat thickness of 2.2 times or more when heated at 300 ° C. for 10 minutes. Therefore, even when exposed to a low temperature environment of 600 ° C. or lower, for example, about 300 ° C., the force that the organic binder restrains the inorganic fibers due to thermal shock is weakened, and the holding sealing material expands. Therefore, a sufficient surface pressure can be exhibited even in a low temperature range of 600 ° C. or lower, and the holding sealing material can be stably held. When the holding sealing material is heated at 300 ° C. for 10 minutes, the mat thickness is preferably changed to 3.5 times or less, more preferably 3.0 times or less, and more preferably 2.8 times or less. More preferably, it changes. When the thickness of the mat changes by more than 3.5 times when heated at 300 ° C. for 10 minutes, the retention performance in the low temperature range becomes too high, and the exhaust gas treating body may be destroyed.
The temperature at which the tensile strength of the organic binder is measured is room temperature of 20 ° C. unless otherwise specified.

The method for the deterioration treatment is not particularly limited as long as the tensile strength of the organic binder can be reduced by 4 to 80% compared with that obtained by heat treatment at 105 ° C. For example, heat treatment, ozone treatment, ultraviolet treatment, micro Wave treatment, needle treatment under heating conditions, etc. are mentioned, and it is only necessary to select the optimum one according to the type and chemical properties of the organic binder to be used. Also good.
In view of the cost for manufacturing the holding sealing material, heat treatment is most preferable among these.

In the holding sealing material of the present invention, the tensile strength of the organic binder is preferably 0.7 to 2.5 MPa, more preferably 0.7 to 2.0 MPa, and 0.7 to 1.5 MPa. More preferably.
When the tensile strength of the organic binder is 0.7 to 2.5 MPa, the force for restraining the holding sealing material is weakened in a low temperature region of 600 ° C. or lower, and the holding sealing material can be expanded.
Moreover, in order to make the organic binder have such tensile strength, it is preferable to perform the above-described deterioration treatment, particularly heat treatment.

The holding sealing material of the present invention may further contain an inorganic binder.

The inorganic binder is not particularly limited, and examples thereof include alumina sol and silica sol.

The holding sealing material of the present invention preferably contains an inorganic binder in an amount of 0.1 to 10% by weight, more preferably 1 to 9% by weight, based on the weight of the entire holding sealing material. More preferably, it is contained in an amount of ˜8% by weight.

The holding sealing material of the present invention may further include an aggregate in which an organic binder and an inorganic binder are aggregated.
The organic binder constituting the aggregate may be the same as or different from the organic binder already described. The inorganic binder constituting the aggregate may be the same as or different from the inorganic binder already described.
Moreover, in order to form an aggregate, the coagulant | flocculant may be further included.

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 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 ratio 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 °).

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.

The mat constituting the holding sealing material of the present invention 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. .

The average fiber diameter of the inorganic fibers constituting the holding sealing material of the present invention is preferably 1 to 20 μm, more preferably 2 to 15 μm, and further preferably 3 to 10 μm.
In addition, the said average fiber diameter averages the fiber diameter of 30 inorganic fibers in the SEM image expanded and displayed 1000 times.

The shape and the like of the holding sealing material of the present invention will be described.
FIG. 1 is a perspective view schematically showing an example of the holding sealing material of the present invention.
As shown in FIG. 1, the holding sealing material 110 has a predetermined longitudinal length (hereinafter, indicated by an arrow L in FIG. 1), a width (indicated by an arrow W in FIG. 1), and a thickness (FIG. 1). It may be composed of a flat plate-like mat having a substantially rectangular shape in a plan view having an arrow T).

In the holding sealing material 110, a convex portion 111 is formed at a first end that is one of the ends of the holding sealing material in the length direction, and a second that is the other end. A concave portion 112 is formed at the end of each. 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 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.

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, so that the wrapping property around the exhaust gas treating body is lowered and the holding sealing material is easily broken.

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 includes a mat preparation step of preparing a mat for holding sealing material made of inorganic fibers with an organic binder attached thereto, and heat-treating the mat with the organic binder attached at 140 ° C. or higher. A heat treatment step.

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 preparing step of preparing a mat for holding sealing material made of inorganic fibers to which an organic binder is attached is performed.
The inorganic fibers constituting the mat for the holding sealing material can be obtained by various methods, and for example, 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, 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, for example. Subsequently, the inorganic fiber precursor is compressed to produce a continuous sheet-like material having a predetermined size, which is subjected to a needle punching process, and then subjected to a firing process to thereby form an inorganic fiber aggregate made of alumina fibers. Prepare.
Subsequently, a mat for a holding sealing material made of inorganic fibers to which an organic binder is attached is obtained by attaching a solution containing an organic binder to the inorganic fiber aggregate and, if necessary, removing the solvent in the solution. Is ready.

In the case of the paper making method, the inorganic fiber such as alumina fiber and silica fiber, the organic binder, and the solvent are mixed so that the content of the inorganic fiber in the raw material liquid becomes a predetermined value, and mixed by stirring with a stirrer. Prepare the solution. You may add an inorganic particle, a pH adjuster, etc. as an inorganic binder to a liquid mixture as needed. Furthermore, you may add the aggregate which aggregated the organic binder and the inorganic binder with the coagulant | flocculant with respect to the said liquid mixture. Subsequently, after pouring the mixed solution into a molding machine having a mesh for filtration on the bottom surface, the solvent in the mixed solution is removed to remove the solvent, thereby holding the sealing material made of inorganic fibers to which an organic binder is attached. The mat preparation is complete.

The solvent removal treatment performed in the (a) mat preparation step is not particularly limited as long as the solvent contained in the mat can be removed. For example, the solvent is removed by means such as compression, rotation, suction, and reduced pressure. Can do.

(B) Heat treatment step Subsequently, a heat treatment step of heat-treating the mat for the holding sealing material made of inorganic fibers to which the organic binder is attached at a temperature of 140 ° C. or higher is performed.

In the manufacturing method of the holding sealing material of the present invention, the mat for the holding sealing material made of inorganic fibers to which the organic binder is attached is heat-treated at 140 ° C. or more, thereby maintaining the shape of the holding sealing material. Is partially degraded. By partially degrading the organic binder, the restraint of the inorganic fibers by the organic binder is weakened at a lower temperature than conventional, for example, 600 ° C. or less, and the holding sealing material is expanded. Therefore, the holding sealing material manufactured by using the method for manufacturing the holding sealing material of the present invention exhibits a sufficient holding power in a low temperature range of 600 ° C. or lower, and can stably hold the exhaust gas treating body.

The heat treatment temperature in the heat treatment step is 140 ° C. or higher, more preferably 140 to 300 ° C., and further preferably 140 to 220 ° C.
By setting the heat treatment temperature to 140 ° C. or higher, the tensile strength of the organic binder can be reduced by 4 to 80% compared to the organic binder heat treated at 105 ° C. Further, when such a holding sealing material is heated at 300 ° C. for 10 minutes, the thickness of the mat changes to 2.2 times or more.
When the heat treatment temperature is lower than 140 ° C., the deterioration of the organic binder constituting the holding sealing material does not proceed efficiently.

Thereafter, in order to obtain a mat having a convex portion and a concave portion as shown in FIG. 1, a cutting step for cutting the mat into a predetermined shape may be further performed.

As described above, the holding sealing material of the present invention can be manufactured.
The holding sealing material of the present invention can be used as a holding sealing material for holding an exhaust gas treating body constituting an exhaust gas purification device.

Hereinafter, an exhaust gas purification apparatus using the holding sealing material of the present invention will be described.

FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus.
As shown in FIG. 2, the exhaust gas purification apparatus 100 includes a metal casing 130, an exhaust gas treatment body 120 accommodated in the metal casing 130, and a holding sealing material 110 disposed between the exhaust gas treatment body 120 and the metal casing 130. And.
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.

As the holding sealing material constituting the exhaust gas purifying apparatus, the holding sealing material of the present invention including the holding sealing material 110 shown in FIG. 1 can be used.

Subsequently, an exhaust gas treatment body (honeycomb filter) and a metal casing constituting the exhaust gas purification apparatus 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 purification device 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 purification device, a clamshell shape or the like can be suitably used in addition to the substantially cylindrical shape.

Subsequently, the exhaust gas treating body constituting the exhaust gas purifying apparatus will be described.
FIG. 3 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus.

The exhaust gas treatment body 120 shown in FIG. 3 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. Further, an outer peripheral coat layer 127 is formed on the outer peripheral surface of the exhaust gas treating body 120.

When any one end of the cell 125 is sealed as in the exhaust gas treating body 120 shown in FIG. 3, the cell whose end is sealed when viewed from one end of the exhaust gas treating body 120. It is preferable that the cells and the cells that are not sealed are alternately arranged.

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

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

The material constituting the exhaust gas treating body 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 mechanical impact or the like. However, in the exhaust gas purification apparatus 100 shown in FIG. 2, 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. Can be prevented.

The exhaust gas treating body constituting the exhaust gas purifying apparatus may carry a catalyst for purifying the exhaust gas. As the catalyst to be carried, for example, a noble metal such as platinum, palladium, rhodium, etc. is preferable. Is more preferable. Further, 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 may be an integrally formed honeycomb structure made of cordierite or the like, or may be made of silicon carbide or the like, and a large number of through holes may have partition walls. A collective honeycomb structure formed by binding a plurality of columnar honeycomb fired bodies arranged in parallel in the longitudinal direction with a paste mainly containing ceramics may be used.

In the exhaust gas treating body constituting the exhaust gas purifying apparatus, the end portion 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, the outer peripheral coat layer may or may not 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 purifying apparatus having the above-described configuration will be described below with reference to FIG.
As shown in FIG. 2, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification device 100 (in FIG. 2, 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 side end face 120 a 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, a method for manufacturing the exhaust gas purification apparatus will be described.
FIG. 4 is a diagram schematically illustrating an example of a method for manufacturing an exhaust gas purification device.

As shown in FIG. 4, first, the holding sealing material 110 is wound around the exhaust gas treating body 120 to obtain a wound body 140. Next, by accommodating this wound body 140 in the metal casing 130, an exhaust gas purification device can be manufactured.

As a method for accommodating the wound body 140 in the metal casing 130, for example, a press-fitting method (stuffing method) in which the exhaust gas treatment body 120 having the holding sealing material 110 disposed around to a predetermined position inside the metal casing 130 is press-fitted. 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 is formed into a shape that can be separated into parts of the first casing and the second casing. For example, a clamshell method in which the second casing is covered and sealed after the 140 is placed on the first casing.
When the wound body is accommodated in the metal casing by the press-fitting method, the inner diameter of the metal casing (the inner diameter of the portion accommodating the exhaust gas treating body) is preferably slightly smaller than the outer diameter of the wound body.

The exhaust gas purifying apparatus may be composed of a plurality of holding sealing materials of two or more layers coupled to each other. 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. .

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

(1) In the holding sealing material of the present invention, the tensile strength of the organic binder affixed to the inorganic fibers is 4 to 80% lower than when heated at 105 ° C. Therefore, the holding sealing material of the present invention expands even at a low temperature range of 600 ° C. or lower, for example, a temperature of about 300 ° C. Therefore, the exhaust gas treating body can be stably held.

(2) In the holding sealing material of the present invention, the mat thickness changes to 2.2 times or more when heated at 300 ° C. for 10 minutes. Therefore, even if it is a low temperature range of 600 degrees C or less, for example, the temperature of about 300 degrees C, a holding sealing material fully expand | swells and can hold | maintain an exhaust gas processing body stably.

(3) By using the method for producing a holding sealing material of the present invention, a holding sealing material capable of stably holding an exhaust gas treating body even at a low temperature range of 600 ° C. or lower, for example, a temperature of about 300 ° C. Can be manufactured.

(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) Matt preparation step (a-1) Spinning step For basic aluminum chloride aqueous solution prepared such that Al content is 70 g / L and Al: Cl = 1: 1.8 (atomic ratio). The silica sol is blended so that the composition ratio in the inorganic fiber after firing is Al ₂ O ₃ : SiO ₂ = 72: 28 (weight ratio), and an appropriate amount of an organic polymer (polyvinyl alcohol) is added and mixed. A liquid was prepared.
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 5.6 μm. Then, this inorganic fiber precursor was heated at 740 degreeC for 10 minute (s), and the inorganic fiber was produced.

(A-2) Fiber-opening step Next, 168.3 g of the inorganic fiber was put into 75 L of water and stirred at 60 Hz for 30 minutes using a mixer to obtain a solution of the inorganic fiber opened.

(A-3) Slurry preparation step An acrylic latex solution (manufactured by BSAF Co., Ltd.) in which an acrylic resin is dispersed in water with respect to the solution of the opened inorganic fiber obtained in the (a-2) opening step. (Acranal A420S) was charged in 12.3 g and stirred at 60 Hz for 1 minute. Subsequently, 6.8 g of alumina sol (manufactured by SASOL, DISPERAL) was added and stirred at 60 Hz for 1 minute. Furthermore, 336.6 g of a 0.5 wt% aqueous solution of nonionic polyacrylamide (manufactured by BSAF, Percol 47NS) was added as a polymer flocculant, and the mixture was stirred at 60 Hz for 1 minute. A slurry was prepared by the method described above.

(A-4) Papermaking Step By making the slurry using a 335 mm × 335 mm tappi papermaking machine, an inorganic fiber aggregate having a basis weight (weight per unit area) of 1500 g / m ² was obtained.

(A-5) Heat treatment step Using a press-type dryer, the inorganic fiber aggregate is dried by heat-treating at 150 ° C. for 15 minutes in a state where the resulting inorganic fiber aggregate is compressed to a thickness of 7.0 mm. Thus, a holding sealing material according to Example 1 was produced.

(Example 2)
(A-5) A holding sealing material according to Example 2 was produced in the same procedure as in Example 1 except that heat treatment was performed at 200 ° C. for 10 minutes in the heat treatment step.

(Comparative Example 1)
(A-5) In the heat treatment step, a holding sealing material according to Comparative Example 1 was produced in the same procedure as Example 1 except that heat treatment was performed at 105 ° C. for 40 minutes.

(Expansion test)
The holding sealing materials according to Examples 1 and 2 and Comparative Example 1 are heated at 300 ° C. for 10 minutes, and the ratio of the thickness of the mat after heating to the thickness of the mat before heating (the thickness (%) of the mat after heating) is obtained. It was. The results are shown in Table 1.

(Tensile strength test)
The acrylic latex solution used in the slurry preparation step (a-3, manufactured by BSAF, Achronal A420S) was poured into a 100 mm × 100 mm mold.
Subsequently, the acrylic latex solution poured into the mold was dried at 105 ° C., 150 ° C., and 200 ° C. for 2.5 hours. The tensile strength test sheet according to Comparative Example 1 was dried from an acrylic latex solution dried at 105 ° C., and the tensile strength test sheet according to Example 1 was dried at 200 ° C. from an acrylic latex solution dried at 150 ° C. Tensile strength test sheets according to Example 2 were obtained from the acrylic latex solution. In addition, the quantity of the acrylic latex solution poured into a type | mold was prepared so that the thickness of each tensile strength test sheet | seat might be set to 1 mm.
Each tensile strength test sheet was punched out into a No. 2 dumbbell shape as defined in JIS-K 6251 to prepare a test piece for a tensile strength test. At this time, the test piece was punched out so that the number of bubbles having a diameter of 1 to 3 mm existing in the dumbbell-shaped constricted portion of the test piece was 5 or less, preferably 0. If the test piece contains bubbles, the cross-sectional area decreases and the tensile strength decreases, and an accurate value cannot be measured. During the drying of the latex solution poured into the mold, when punching out the tensile strength test sheet by breaking the bubbles when the organic binder has fluidity or moving the bubbles by applying vibration Air bubbles can be reduced.
Then, the tensile strength was calculated | required from the load at the time of pulling a test piece with the speed | rate of 500 mm / min with the Instron type | mold tensile tester, and fracture | rupture. The results are shown in Table 1.

From the results shown in Table 1, when the holding sealing material of the present invention was heated at 300 ° C. for 10 minutes, the mat thickness changed to 2.2 times (220%) or more. On the other hand, in the holding sealing material according to Comparative Example 1, when heated at 300 ° C. for 10 minutes, the thickness of the mat is changed only about 1.1 times, and the surface pressure is not sufficiently exhibited. I understood. In addition, the tensile strength of the organic binder heat-treated at 105 ° C exceeded 2.5 MPa, whereas the tensile strength of the organic binder heat-treated at 150 ° C and 200 ° C was less than 2.5 MPa. I understood that it was.
From the above results, it was found that the holding sealing material of the present invention has sufficient holding power because the mat expands even in a low temperature range of 600 ° C. or lower.

DESCRIPTION OF SYMBOLS 100 Exhaust gas purification apparatus 110 Holding sealing material 120 Exhaust gas treatment body 130 Metal casing

Claims (11)

It is a holding sealing material made of inorganic fibers to which an organic binder is attached, and does not contain an expansion material,
The organic binder has a tensile strength measured by a method according to JIS-K 6251 which is 4 to 80% lower than that of the organic binder heat-treated at 105 ° C. It is a holding sealing material made of inorganic fibers to which an organic binder is attached, and does not contain an expansion material,
A holding sealing material, wherein when the mat having a predetermined thickness constituting the holding sealing material is heated at 300 ° C. for 10 minutes, the thickness of the mat changes to 2.2 times or more. A holding sealing material made of inorganic fibers to which an organic binder is attached,
The holding sealing material according to claim 1 or 2, wherein the organic binder has a tensile strength measured by a method according to JIS-K 6251 of 0.7 to 2.5 MPa. The holding sealing material according to any one of claims 1 to 3, wherein the content of the organic binder is 0.1 to 10% by weight in terms of solid content with respect to the total amount of the holding sealing material. The holding sealing material according to claim 1, wherein the organic binder has a glass transition temperature (T _g ) of −5 ° C. or lower. The holding sealing material according to any one of claims 1 to 5, wherein the polymer resin component constituting the organic binder is an acrylic resin. The said inorganic fiber is comprised from at least 1 sort (s) selected from the group which consists of an alumina fiber, a silica fiber, an alumina silica fiber, a mullite fiber, a biosoluble fiber, and a glass fiber. Holding sealing material. A mat preparation step of preparing a mat for a holding sealing material made of inorganic fibers to which an organic binder is attached;
A method for producing a holding sealing material, comprising a heat treatment step of heat-treating the mat to which the organic binder is attached at 140 ° C. or higher. The holding sealing material according to claim 8, wherein the inorganic fiber 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. Production method. The method for producing a holding sealing material according to claim 8 or 9, wherein the organic binder has a polymer resin component composed of an acrylic resin and is an emulsion. The method for producing a holding sealing material according to any one of claims 8 to 10, wherein a glass transition temperature ( _Tg ) of a polymer resin component constituting the organic binder is -5 ° C or lower.

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