JP6333632B2 - Manufacturing method of holding sealing material - Google Patents

Description

The present invention relates to a method for manufacturing a 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 provides a manufacturing method for manufacturing a holding sealing material having a sufficient holding power even in a low temperature range of 600 ° C. or less by a simple process. With the goal.

In order to achieve the above object, one aspect of the method for producing a holding sealing material of the present invention includes a mat preparing step of preparing a mat for a holding sealing material made of inorganic fibers to which an organic binder is attached, and the organic binder described above. A holding sealing material manufacturing method characterized by comprising a microwave treatment step of irradiating a microwave to a mat to which is attached, and the obtained holding sealing material conforms to JIS-K 6251 The tensile strength of the organic binder measured by the method is 4 to 80% lower than that of the organic binder heat-treated at 105 ° C. without performing the microwave treatment step.

In the holding sealing material manufacturing method of the present invention, a microwave is applied to the mat preparing step of preparing a mat for holding sealing material made of inorganic fibers to which an organic binder is attached, and to the mat to which the organic binder is attached. And a microwave treatment step of irradiating.
In the microwave treatment step, the polymer resin component or inorganic fiber constituting the organic binder is heated, and the polymer resin component constituting the organic binder is partially degraded and deteriorated. Therefore, the holding sealing material manufactured by the manufacturing method of the holding sealing material of the present invention is an organic binder in which the tensile strength of the organic binder constituting the holding sealing material is heat-treated at 105 ° C. without performing the microwave processing step. 4 to 80% lower than That is, the organic binder constituting the holding sealing material manufactured by the method for manufacturing the holding sealing material of the present invention has a lower tensile strength than that which is heat-treated at 105 ° C. without performing the microwave processing step, It can be said that some have 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. In addition, when the holding sealing material manufactured by the manufacturing method of the holding sealing material of this invention is heated for 10 minutes at 300 degreeC, the thickness of the mat | matte which comprises a holding sealing material changes 2.2 times or more.

That is, another aspect of the method for producing a holding sealing material of the present invention includes a mat preparing step of preparing a mat for holding sealing material made of inorganic fibers to which an organic binder is attached, and a mat to which the organic binder is attached. On the other hand, it is a manufacturing method of a holding sealing material characterized by comprising a microwave processing step of irradiating microwaves, and the obtained holding sealing material is a mat having a predetermined thickness constituting the holding sealing material. The thickness of the mat changes to 2.2 times or more when heated at 300 ° C. for 10 minutes.
When the holding sealing material manufactured by the method for manufacturing a 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.

In the manufacturing method of the holding sealing material of the present invention, it is preferable that the organic binder is heated by microwave irradiation in the microwave treatment step.
By heating the organic binder by microwave irradiation, deterioration of the organic binder can be promoted.

In the manufacturing method of the holding sealing material of the present invention, it is preferable that the inorganic fiber is heated by microwave irradiation in the microwave treatment step.
By heating the inorganic fiber by microwave irradiation, the organic binder can be heated and deteriorated through the inorganic fiber. There is a frequency band that is easy to heat depending on the material, and it is necessary to set the frequency of the microwave to a frequency band that most affects the material to be used. A preferable frequency band is a frequency of 2.4 to 2.5 GHz which is an ISM band band of an industrial heating furnace. Further, a combination with an organic binder or a fiber material that can generate heat by microwaves having the above-described frequency is more preferable.

In the method for producing a holding sealing material of the present invention, the microwave treatment step is preferably performed while heating the mat by a method other than microwave irradiation.
A method for heating the mat by a method other than the microwave irradiation is not particularly limited, and examples thereof include heating with an electric heater.
Although the temperature which heats a mat | matte is not specifically limited, It is preferable that it is 100-230 degreeC. By performing the microwave treatment process while heating the mat to 100 to 230 ° C., the deterioration of the organic binder can be further promoted.
Further, in the wet sealing paper holding seal material, the deterioration of the organic binder can be promoted while drying the holding seal material by simultaneous treatment with microwaves and heating, so that the manufacturing time can be further shortened. Here, when the heating temperature is less than 100 ° C., when applying to the holding sealing material in the wet paper state, most of the energy by the microwave is used for drying the holding sealing material, which causes deterioration of the organic binder. It may not contribute and productivity may decrease. Moreover, when it exceeds 230 degreeC, before promoting the deterioration of the organic binder by a microwave, the surface of a holding sealing material may discolor and the appearance may be impaired.

In the manufacturing method of the holding sealing material of the present invention, the organic binder preferably has a tensile strength measured by a method according to JIS-K 6251 of 0.7 to 2.5 MPa.
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 method for producing a 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 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.

In the method for producing a holding sealing material of the present invention, the polymer resin component constituting the organic binder is 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 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, in the microwave treatment step, it is preferable to irradiate the mat with microwaves at an output of 500 to 10000 W for 1 to 1000 minutes.
When the output of the microwave is less than 500 W, the output is too weak, so that the acceleration of deterioration is slow and productivity may be lacking. In addition, when the output exceeds 10,000 W, the organic binder may be burned out instantaneously, and the mat may not be able to maintain the restraint between the fibers.

FIG. 1 is a perspective view schematically showing an example of a holding sealing material obtained by the method for manufacturing a 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 manufacturing method of 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 manufacturing method of the sealing material of this invention is demonstrated.
The method for producing a 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 a microwave applied to the mat with the organic binder attached thereto. A method for producing a holding sealing material comprising an irradiation microwave treatment step, wherein the obtained holding sealing material has a tensile strength of the organic binder measured by a method according to JIS-K 6251, and the microwave treatment It is characterized by being 4 to 80% lower than the organic binder heat-treated at 105 ° C. without performing the process.

First, 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.

Since the types and characteristics of the inorganic fibers constituting the holding sealing material mat are the same as the inorganic fibers constituting the holding sealing material mat obtained by the method of manufacturing the holding sealing material of the present invention, Will be described in the description of the holding sealing material obtained by the method for manufacturing the holding sealing material of the present invention.

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.
Examples of the method for attaching a solution containing an organic binder include a method of spraying a solution containing an organic binder onto a holding sealing material, a method of immersing the holding sealing material in a solution containing an organic binder, and a curtain coat.

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.

The polymer resin component constituting the organic binder attached to the mat used in the method for producing the holding sealing material of the present invention is preferably an acrylic resin, and the organic binder 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 manipulated by a microwave treatment process described later, and the method for producing a holding sealing material of the present invention It is suitable as an organic binder constituting the obtained holding sealing material.

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.
In addition, in the manufacturing method of the holding sealing material of this invention, the glass transition temperature of an organic binder has shown the glass transition temperature of the organic binder before performing the microwave process process mentioned later.

(B) Microwave treatment step Subsequently, a microwave treatment step of irradiating the mat with the organic binder attached thereto is performed.

In the manufacturing method of the holding sealing material of the present invention, the shape of the holding sealing material is maintained by performing a microwave process treatment that irradiates microwaves to the mat for the holding sealing material made of inorganic fibers to which an organic binder is attached. Leave the organic binder 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.

As a method of irradiating the microwave, a generally used method can be used. For example, a method of generating a microwave using a magnetron can be employed.
A preferable frequency band is a frequency of 2.4 to 2.5 GHz which is an ISM band band of an industrial heating furnace. Further, a combination with an organic binder or a fiber material that can generate heat by microwaves having the above-described frequency is more preferable.

Although the microwave irradiation intensity | strength is not specifically limited, It is preferable that it is 0.1-1000 J / cm < ² >. When the irradiation intensity of the microwave is less than 0.1 J / cm ² , the irradiation intensity is too weak, so that the tensile strength of the organic binder may hardly be reduced. On the other hand, the irradiation intensity of the microwave is 1000 J / cm ^2. If it exceeds, the irradiation intensity is too strong, so that the deterioration of the organic binder proceeds quickly, and it may be difficult to adjust the degree of deterioration of the organic binder.

The microwave irradiation time is preferably 1 to 1000 minutes, more preferably 5 to 800 minutes, and even more preferably 10 to 600 minutes.
In addition, when the microwave irradiation time is less than 1 minute, the microwave irradiation time is too short, so the tensile strength of the organic binder may hardly be reduced. On the other hand, when the microwave irradiation time exceeds 1000 minutes In addition, since the microwave irradiation time is too long, the tensile strength of the organic binder may be reduced too much.

In the above-described microwave treatment step, heating (heat treatment) by a method other than microwave irradiation may be performed.
The temperature of the heat treatment in the microwave treatment step is more preferably 100 to 230 ° C, and further preferably 100 to 200 ° C.
When the temperature of the heat treatment is less than 100 ° C., the effect of promoting the deterioration of the organic binder due to the heat treatment is small, and the productivity is hardly improved. On the other hand, when the temperature exceeds 230 ° C., the organic binder may be destroyed because the effect of promoting the deterioration of the organic binder due to the heat treatment becomes too large. Further, the heat treatment time is preferably the same as the microwave treatment step time. By making the time of the microwave treatment step and the heat treatment time the same, the holding sealing material can be efficiently manufactured.

The tensile strength of the organic binder is compared with that of the organic binder heat-treated at 105 ° C. without performing the microwave treatment step by performing the microwave treatment step under the above conditions or by performing the heat treatment in the microwave treatment step. It can be reduced by 4 to 80%. 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. The characteristics of the obtained holding sealing material will be described in more detail.

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. In the first step of preparing the mat, a cutting process may be performed in order to obtain the mat having the above shape.
Through the above steps, a holding sealing material having the following characteristics can be obtained.

The organic binder constituting the holding sealing material obtained by the above method has a tensile strength measured by a method according to JIS-K 6251 compared with the organic binder heat-treated at 105 ° C. without performing the microwave treatment step. 4 to 80% lower. The tensile strength of the organic binder is preferably 10 to 80% lower and more preferably 20 to 80% lower than that obtained by heat treatment at 105 ° C. without performing microwave treatment.
When the tensile strength is reduced by less than 4% compared to the organic binder heat treated at 105 ° C. without performing microwave treatment, the strength of binding the inorganic fibers of the organic binder is too strong, so that the low temperature Sometimes the holding seal material hardly expands. In addition, when the tensile strength is reduced by more than 80% compared to an organic binder that has been heat treated at 105 ° C. without performing microwave treatment, with a slight impact when handling the holding sealing material, The organic binder may be destroyed, and the holding sealing material may expand greatly even at room temperature.
That is, the organic binder constituting the holding sealing material obtained by the manufacturing method of the holding sealing material of the present invention is compared with the case where it is heat-treated at 105 ° C. without performing the microwave treatment through the manufacturing process described above. The tensile strength is 4 to 80% lower.
The temperature at which the tensile strength of the organic binder is measured is room temperature of 20 ° C. unless otherwise specified.

When such an organic binder is attached to inorganic fibers, the holding sealing material obtained by the method for manufacturing a holding sealing material of the present invention is a mat that constitutes the holding sealing material when heated at 300 ° C. for 10 minutes. Since the thickness of the fiber changes 2.2 times or more, even when exposed to a low temperature environment of 600 ° C. or less, for example, about 300 ° C., the organic binder has a force to restrain inorganic fibers by thermal shock. It 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 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 tensile strength of the organic binder constituting the obtained holding sealing material 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 microwave treatment step.
When the tensile strength of the organic binder constituting the obtained holding seal material is less than 0.7 MPa, the force to bind the inorganic fibers of the organic binder is too weak, so with a little impact when handling the holding seal material, The organic binder may be destroyed, and the holding sealing material may expand greatly even at room temperature. Further, when the tensile strength of the organic binder exceeds 2.5 MPa, the holding sealing material hardly expands at a low temperature because the force for binding the inorganic fibers of the organic binder is too strong.
In addition, in the manufacturing method of the holding sealing material of this invention, the tensile strength of an organic binder has shown the tensile strength of the organic binder after performing a microwave process process.

The holding sealing material obtained by the method for producing the holding sealing material 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 1 to 9% by weight. % Is more preferable, and 4 to 8% by weight is more preferable.
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 holding sealing material may be further attached with an inorganic binder.
The inorganic binder is not particularly limited, and examples thereof include alumina sol and silica sol.

The holding sealing material preferably contains an inorganic binder in an amount of 0.1 to 10% by weight, more preferably 1 to 9% by weight, more preferably 4 to 8% by weight based on the weight of the entire holding sealing material. % Content is more preferable.

The holding sealing material may further be attached with 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 fibers constituting the mat of the holding sealing material obtained from the method for producing the holding sealing material of the present invention (or the inorganic fibers constituting the mat used in the mat preparation step) are not particularly limited, but are alumina fibers and silica fibers. It is preferably composed of at least one selected from the group consisting of alumina silica fiber, mullite fiber, biosoluble fiber and glass fiber, and has characteristics required for mats such as heat resistance and wind erosion resistance. Depending on the environmental regulations of each country, it is preferable to use a fiber having a large diameter or a fiber length.
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 the inorganic fibers, 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 °).

Biosoluble fibers may be used as the inorganic fibers constituting the mat. 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.

Of the inorganic fibers constituting the mat, 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.

As described above, the mat constituting the holding sealing material can be manufactured by, for example, 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 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 mat constituting the holding sealing material obtained by the method for manufacturing the holding sealing material of the present invention will be described. The mat has the same shape as the mat used in the mat preparation step.

FIG. 1 is a perspective view schematically showing an example of a holding sealing material obtained by the method for manufacturing a 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 is formed on the first end 111 which is one end of the end portions on the length direction side of the holding sealing material, and the second end which is the other end. A concave portion is formed in the end portion 112. The first end portion 111 and the second end 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 described later. It has become.
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 obtained by the method for manufacturing a holding sealing material of the present invention (weight per unit area) is not particularly limited, is preferably ^{200~4000g / m 2, 1000~3000g / m} 2 It is more preferable that 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 obtained by the method for producing the holding sealing material of the present invention (the bulk density of the holding sealing material before winding) is not particularly limited, but is 0.10 to 0.30 g / cm ³ . Preferably there is. 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 obtained by the method for manufacturing a 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 one holding sealing material is used. It may be a plurality of holding sealing materials 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. .

The holding sealing material obtained by the manufacturing method of the holding sealing material of the present invention can be used as a holding sealing material for holding the exhaust gas treating body constituting the exhaust gas purification device.

Hereinafter, an exhaust gas purification apparatus using the holding sealing material 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, a holding sealing material obtained by the method of manufacturing 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 a holding sealing material obtained by the manufacturing method of 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 effect of the manufacturing method of the holding sealing material of the present invention will be described.

(1) The holding sealing material obtained by the manufacturing method of the holding sealing material of the present invention is subjected to the microwave treatment step, and the tensile strength of the organic binder attached to the inorganic fiber is not subjected to the microwave treatment step. 4 to 80% lower than when heated at 105 ° C. Therefore, the holding sealing material manufactured by the manufacturing method of 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) When the holding sealing material obtained by the manufacturing method of the holding sealing material of the present invention is heated at 300 ° C. for 10 minutes, the thickness of the mat changes to 2.2 times or more. 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.

(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.

(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. Prepare the solution.
The obtained mixed solution is concentrated to form a spinning mixture, and this spinning mixture is spun by a blowing method to produce an inorganic fiber precursor having an average fiber diameter of 5.6 μm. Subsequently, the inorganic fiber precursor is heated at 740 ° C. for 10 minutes to produce inorganic fibers.

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

(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) is charged and stirred at 60 Hz for 1 minute. Furthermore, 336.6 g of a 0.5% by weight aqueous solution of nonionic polyacrylamide (manufactured by BSAF, Percol 47NS) is added as a polymer flocculant and stirred at 60 Hz for 1 minute. A slurry is prepared by the method described above.

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

(A-5) Drying step Using a press-type dryer, the obtained inorganic fiber aggregate is compressed by heat treatment at 105 ° C for 40 minutes and dried in a state compressed to a thickness of 7.0 mm.

(A-6) Microwave treatment step (a-5) A holding sealing material is produced by irradiating the mat obtained in the drying step with microwaves.

(Expansion test)
The holding sealing material subjected to the microwave treatment step is 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.

(Tensile strength test)
(A-3) The acrylic latex solution used in the slurry preparation step (BSAF, Acronal A420S) is poured into a 100 mm × 100 mm mold.
Subsequently, the acrylic latex solution poured into the mold is dried at 105 ° C. over 2.5 hours to obtain an organic binder sheet. The organic binder sheet is irradiated with microwaves to obtain a tensile strength test sheet. The amount of acrylic latex solution poured into the mold is adjusted so that the thickness of each tensile strength test sheet is 1 mm.
Each tensile strength test sheet is punched out so as not to include bubbles having a diameter of 3 mm or more so as to have a No. 2 dumbbell shape defined in JIS-K 6251, and a test piece for tensile strength test is produced. At that time, the number of bubbles having a diameter of 1 to 3 mm present in the dumbbell-shaped constricted portion of the test piece is desirably 5 or less, and more desirably 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 acrylic latex solution poured into the mold, the tensile strength test sheet is punched out by breaking the bubbles when the organic binder has fluidity or moving the bubbles by applying vibration. Reduce air bubbles.
Subsequently, the test piece is pulled at a speed of 500 mm / min with an Instron type tensile tester, and the tensile strength is obtained from the load when it breaks.

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

Claims (11)

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 microwave treatment step of irradiating microwaves on the mat to which the organic binder is attached,
The obtained holding sealing material has a tensile strength of the organic binder measured by a method according to JIS-K 6251 of 4 compared with the organic binder heat-treated at 105 ° C. without performing the microwave treatment step. A method for producing a holding sealing material characterized by being 80% lower. 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 microwave treatment step of irradiating microwaves on the mat to which the organic binder is attached,
The obtained holding sealing material is characterized in that 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. Manufacturing method of holding sealing material. The method for manufacturing a holding sealing material according to claim 1 or 2, wherein, in the microwave treatment step, the organic binder is heated by microwave irradiation. The method for producing a holding sealing material according to claim 1 or 2, wherein, in the microwave treatment step, the inorganic fiber is heated by microwave irradiation. The method for producing a holding sealing material according to any one of claims 1 to 4, wherein the microwave treatment step is performed while heating the mat by a method other than microwave irradiation. The method for producing a holding sealing material according to any one of claims 1 to 5, 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 method for producing a holding sealing material according to any one of claims 1 to 6, 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 method for producing a holding sealing material according to claim 1, wherein a glass transition temperature (T _g ) of a polymer resin component constituting the organic binder is −5 ° C. or lower. The method for producing a holding sealing material according to any one of claims 1 to 8, wherein the polymer resin component constituting the organic binder is an acrylic resin and further an emulsion. 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. Manufacturing method of the holding sealing material. The irradiation intensity of the microwaves in the microwave treatment step method for manufacturing a holding sealing material according to any one of claims 1 to 10 is 0.1~1000J / cm ^2.

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