JP6419556B2 - Holding sealing material and exhaust gas purification device - Google Patents

Description

The present invention relates to a holding sealing material, an exhaust gas purification device, and 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 purifying device that collects PM in exhaust gas or purifies harmful gas components, an exhaust gas treatment body made of porous ceramics such as silicon carbide and 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.

Further, as the engine output increases, the exhaust gas flowing through the exhaust gas purification device tends to increase in temperature and pressure. When such high-temperature and high-pressure exhaust gas is introduced into the exhaust gas purification device, the holding sealing material is altered by the heat of the exhaust gas, the inorganic fibers constituting the holding sealing material are scattered by the wind pressure of the exhaust gas, and the touch (holding) Inorganic fibers constituting the sealing material are broken by the wind pressure and the mass is reduced).
When the holding sealing material is altered, scattered, or subjected to a touch, not only the surface pressure decreases with the decrease in the amount of inorganic fibers constituting the holding sealing material, but also the inorganic fibers scattered from the holding sealing material There has been a problem of causing clogging of the exhaust gas treating body.

Conventionally, in order to solve such a problem, a method of reducing the proportion of inorganic fibers having a length of 200 μm or less among the inorganic fibers constituting the holding sealing material (see, for example, Patent Document 1) is known. .

JP 2007-231478 A

However, the holding sealing material described in Patent Literature 1 can suppress the touch of the holding sealing material, but has an insufficient ability to hold the exhaust gas treating body.

The present inventors have conducted intensive research, and in the holding sealing material described in Patent Document 1, most of the inorganic fibers constituting the holding sealing material are oriented in a direction perpendicular to the thickness direction of the holding sealing material. Therefore, it has been found that the surface pressure derived from the restoring force of the inorganic fibers is not sufficiently exhibited. Furthermore, if the size of the aggregate of inorganic fibers formed in the process of producing the holding sealing material by papermaking method becomes too large, the density of the inorganic fibers in the obtained holding sealing material will be uneven, and the inorganic fibers As a result, the present inventors have found that the wind resistance is lowered at a location where the density is low.

That is, the present invention has been made to solve the above-described problems, and an object thereof is to provide a holding sealing material that achieves both high surface pressure and wind resistance.

In order to achieve the above object, the holding sealing material of the present invention is a holding sealing material comprising an inorganic fiber and made of a layered mat obtained by a papermaking method so that an intermediate layer of the holding sealing material is exposed. When the holding sealing material is peeled off, the surface of the intermediate layer is an undulating surface having a concave portion and a convex portion, and a test piece obtained by cutting the holding sealing material with a size of 50 mm × 50 mm is used as the intermediate layer. A first line segment that is a line segment that connects the concave portion that is the most concave and the concave portion that is the second concave when the test piece is viewed from the cut surface. The shortest distance from the top of the convex part on the surface of the intermediate layer is 1 mm or less, and the number of convex parts is 3/5 cm or more.

Assuming that the inorganic fibers constituting the holding sealing material are all oriented in the direction perpendicular to the thickness direction of the holding sealing material, when the holding sealing material is compressed in the thickness direction, the restoring force (surface pressure) ). Further, regarding such a holding sealing material, when the holding sealing material is peeled off so that the intermediate layer is exposed, it is considered that the surface of the exposed intermediate layer is flat and has no unevenness.
On the other hand, when the inorganic fibers constituting the holding seal material are oriented parallel to the thickness direction of the holding seal material, the inorganic fibers are deformed when the holding seal material is compressed, resulting in a restoring force. The surface pressure of the holding sealing material will be exerted by the repulsion derived.
That is, in the holding sealing material of the present invention in which the number of convex portions is 3/5 cm or more on the surface of the intermediate layer, it can be said that the inorganic fibers are sufficiently oriented with respect to the thickness direction of the holding sealing material. . Therefore, the holding sealing material of the present invention can exhibit a high surface pressure.

Further, a mat manufactured by a papermaking method is generally formed by laminating aggregates in which inorganic fibers are aggregated, and compressing and drying. Aggregates in which inorganic fibers are aggregated maintain their shape to some extent even after being formed as a holding sealing material, and when the intermediate layer of the holding sealing material is peeled off, the aggregate unit in which inorganic fibers are aggregated Therefore, irregularities corresponding to the size of the aggregates are formed on the surface of the intermediate layer.
That is, when the size of the aggregate increases, the size of the unevenness formed on the surface of the intermediate layer increases, and the height of the convex portion (the shortest distance from the top of the convex portion to the first line segment) Becomes longer.
If the maximum height of the convex portion exceeds 1 mm on the surface of the intermediate layer, the density of the inorganic fibers constituting the holding sealing material is uneven, and wind resistance is reduced.

In the holding sealing material of the present invention, it is preferable that the proportion of fibers having a fiber length of 200 μm or less among the inorganic fibers is 40% or less, and the average fiber length of the inorganic fibers is 500 to 1500 μm.
In addition, it is preferable that the ratio of the fiber whose fiber length is 200 micrometers or less among inorganic fibers is 40% or less, It is more preferable that it is 30% or less, It is further more preferable that it is 25% or less. Of inorganic fibers, the ratio of fibers having a fiber length of 200 μm or less can be reduced to 40% or less, so that the ratio of short fibers that are easily scattered by the wind pressure of exhaust gas can be reduced. It becomes. Therefore, both wind resistance and good surface pressure can be achieved.
If the proportion of fibers having a fiber length of 200 μm or less among the inorganic fibers exceeds 40%, the inorganic fibers are likely to be scattered by the wind pressure of the exhaust gas, and sufficient surface pressure may not be exhibited. In addition, if the average fiber length of the inorganic fibers exceeds 1500 μm, the fiber length of the inorganic fibers constituting the holding sealing material is too long, and the aggregates of inorganic fibers in the manufacturing process become too large, thereby forming the holding sealing material. Unevenness may occur in the density of inorganic fibers.
Further, when the proportion of inorganic fibers having a fiber length of 3000 μm or more is increased, similarly, the inorganic fibers may be excessively aggregated in the production process, and the density of the inorganic fibers constituting the holding sealing material may be uneven. Therefore, the proportion of inorganic fibers having a fiber length of 3000 μm or more is preferably 20% or less.

In the holding sealing material of the present invention, the holding sealing material preferably contains an organic binder.
When the holding sealing material contains an organic binder, inorganic fibers can be connected to each other, and the moldability of the holding sealing material can be improved.

In the holding sealing material of the present invention, the content of the organic binder is preferably 2 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 2% by weight, when the holding sealing material is wound around the exhaust gas treating body, the holding sealing material may break, and when it 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, and more preferably −5 ° C. or lower.
When the glass transition temperature of the organic binder is 5 ° C. or lower, the holding binder is excellent in flexibility because it has a high film elongation and a flexible film while increasing the strength of the organic binder film formed by the organic binder. It can be. Therefore, when the holding sealing material is wound around the exhaust gas treating body, the surface of the holding sealing material becomes difficult to break. 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. Therefore, it is possible to reduce adverse effects on the working environment of the worker who installs the catalytic converter in handling the holding sealing material.

In the holding sealing material of the present invention, the holding sealing material preferably contains an inorganic binder.
When the holding sealing material contains the inorganic binder, the friction between the inorganic fibers can be increased, and the surface pressure can be improved.

In the holding sealing material of the present invention, the content of the inorganic 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 inorganic binder is less than 0.1% by weight, the surface pressure is hardly improved by the addition of the inorganic binder. In addition, when the content of the inorganic binder exceeds 10% by weight, the effect of improving the surface pressure is hardly changed. Therefore, excessive use of the inorganic binder is not preferable from the viewpoint of manufacturing cost.

In the holding sealing material of the present invention, the inorganic fiber is preferably composed of at least one selected from the group consisting of alumina, silica, alumina-silica, mullite, biosoluble fiber and glass fiber.
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 resistance, etc. The characteristics required for the holding sealing material of the invention can be sufficiently satisfied.

The exhaust gas purification apparatus of the present invention includes an exhaust gas treatment body, a metal casing that houses the exhaust gas treatment body, and a holding sealing material that is disposed between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body The holding sealing material is the holding sealing material of the present invention.
Since the exhaust gas purification apparatus of the present invention includes the holding sealing material of the present invention, the exhaust gas treating body can be stably retained.

The manufacturing method of the holding sealing material of the present invention includes a fiber-opening step for opening inorganic fibers, a classification step for classifying the opened inorganic fibers, a solvent, an organic binder, and an inorganic binder for the classified inorganic fibers. And a slurry preparation step for preparing a slurry by mixing with a papermaking step for producing an inorganic fiber aggregate by papermaking the slurry, wherein the fiber length is 200 μm in the classification step. It is characterized by removing a part or all of the inorganic fibers below.
If some or all of the inorganic fibers having a fiber length of less than 200 μm are removed in the classification step, flocs in which the inorganic fibers are loosely entangled with each other can be easily formed. Therefore, it is possible to produce a holding sealing material in which inorganic fibers are sufficiently entangled and can exhibit a sufficient surface pressure.

In the method for producing a holding sealing material of the present invention, it is preferable that the ratio of inorganic fibers having a fiber length of 200 μm or less in the classification step is 40% or less.
By setting the proportion of inorganic fibers having a fiber length of 200 μm or less to 40% or less, a floc in which inorganic fibers are entangled with each other is more easily formed. On the other hand, when the ratio of the inorganic fiber having a fiber length of 200 μm or less exceeds 40%, the inorganic fiber constituting the obtained holding sealing material may be easily scattered by the wind pressure of the exhaust gas.

In the manufacturing method of the holding sealing material of the present invention, the average fiber length of the classified inorganic fibers is preferably 200 to 20000 μm.
When the average fiber length of the classified inorganic fibers is 200 to 20000 μm, it becomes easy to form flocs in which the inorganic fibers are loosely entangled with each other, so that the entanglement between the inorganic fibers constituting the obtained holding sealing material has anisotropy. It is difficult to form and tends to become a strong entanglement. On the other hand, when the average fiber length of the classified inorganic fibers exceeds 20000 μm, the size of the formed flocs becomes too large, and thus the density of the inorganic fibers constituting the holding sealing material may be uneven.

In the method for producing a holding sealing material of the present invention, it is preferable to use a wet cyclone in the classification step. Since the wet cyclone is excellent in classification accuracy and hardly breaks the inorganic fiber, it is suitable for the method for producing the holding sealing material of the present invention.

FIG. 1 is a perspective view schematically showing an example of the holding sealing material of the present invention. FIG. 2A is a side view schematically showing a view of an example of a test piece peeled off so that the intermediate layer is exposed from the cut surface, and FIG. It is an expanded sectional view of the broken line part in a). FIG. 3 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus. FIG. 4 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus. FIG. 5 is a diagram schematically illustrating an example of a method for manufacturing an exhaust gas purification apparatus.

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

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

The holding sealing material of the present invention is a holding sealing material comprising an inorganic fiber and comprising a layered mat obtained by a papermaking method, and when the holding sealing material is peeled off so that an intermediate layer of the holding sealing material is exposed. The surface of the intermediate layer is a undulating surface having a concave portion and a convex portion, and the test piece obtained by cutting the holding sealing material with a size of 50 × 50 mm is peeled off so that the intermediate layer is exposed, and the test piece is viewed from the cut surface. In this case, the first line segment that connects the concave portion that is the most concave on the surface of the intermediate layer and the concave portion that is the second concave, and the apex of the convex portion that is the most convex on the surface of the intermediate layer The shortest distance is 1 mm or less, and the number of convex portions is 3/5 cm or more.

First, 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 length in the longitudinal direction (hereinafter, indicated by an arrow L in FIG. 1), width (indicated by an arrow W in FIG. 1), and 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, the step corresponding to the first end 111 as one end and the second end 112 as the other end among the ends in the lengthwise direction of the holding sealing material. 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, the shape is such that the two just fit each other.
The “substantially rectangular shape in plan view” is a concept including the above steps. In addition, the substantially rectangular shape in plan view includes a shape whose corners have an angle other than 90 °.

The holding sealing material of the present invention is composed of a mat obtained by a papermaking method.
Since the mat obtained by the papermaking method has a structure in which a plurality of thin layers are laminated, the plurality of thin layers can be separated from each other. The holding sealing material of the present invention is characterized by the surface shape when the mat is peeled so that the intermediate layer is exposed.

A method for measuring the unevenness of the intermediate layer in the holding sealing material of the present invention will be described below.
The holding sealing material of the present invention evaluates the unevenness of the intermediate layer using a test piece cut to a size of 50 × 50 mm. The test piece is peeled by the following procedure.
Since the test piece is obtained by a papermaking method, a striped pattern in which a plurality of thin layers are superimposed on the cut surface of the test piece can be confirmed. Therefore, a gap for inserting a clamp, which will be described later, is inserted by inserting a thin plate-like jig into one of a plurality of thin layer gaps formed near the center in the thickness direction from any one corner of the test piece. Form. The length for inserting the jig is from the corner to 10 mm.
Of the region from the corner to 10 mm, the region in the thickness direction from any one main surface of the test piece to the intermediate layer is clamped and fixed. Subsequently, in the region from the corner to 10 mm, the region in the thickness direction from the other main surface of the test piece to the intermediate layer is fixed with another clamp. Each of the two clamps is fixed to both ends of a tensile tester, and pulled with a predetermined force to peel the test piece and expose the intermediate layer. At this time, one clamp is fixed to the tensile tester, and the other clamp is moved at a speed of 50 mm / min.
By the above procedure, the intermediate layer of the test piece can be exposed and the unevenness of the surface of the intermediate layer can be evaluated. Also, if the test piece is about to break during the above procedure, the test piece is fixed by hand instead of the clamp, and the test piece is peeled off by gradually pulling both ends of the test piece so that the test piece does not break. You may let them.

Subsequently, an image of the cut surface of the peeled test piece is taken. A method for capturing an image on the cut surface of the test piece is not particularly limited, and examples thereof include a commercially available digital camera and a digital microscope.
By analyzing the photographed image according to the following procedure, unevenness in the intermediate layer of the holding sealing material is evaluated. Note that the image of the test piece is arranged so that the exposed intermediate layer is on the upper side and the surface constituting the main surface of the holding sealing material is on the lower side.

FIG. 2A is a side view schematically showing a view of an example of a test piece peeled off so that the intermediate layer is exposed from the cut surface, and FIG. It is an expanded sectional view of the broken line part in a).
A method for measuring the degree of unevenness formed on the surface of the intermediate layer will be described below with reference to FIG.
The test piece 10 peeled so that the intermediate layer is exposed has an undulating surface in which irregularities are formed on the surface 30 of the intermediate layer. First, with respect to the surface 30 of the intermediate layer, a first line segment 33 that connects the concave portion 31 that is the most concave and the concave portion 32 that is the second concave is drawn. If the surface 30 of the intermediate layer is not exposed below the line segment 33 when the line segment is extended to the entire length of the test piece, the line segment is the first line segment 33.
Subsequently, on the surface 30 of the intermediate layer, a perpendicular 35 is drawn with respect to the first line segment 33 from the apex of the convex portion 34 that is the most convex. The length of the vertical line 35 (the length indicated by the double-headed arrow h in FIG. 2B) indicates the shortest distance between the first line segment 33 and the convex part 34 that is the most convex. The length of the perpendicular 35 is regarded as the maximum height of the convex portion in the test piece, and the maximum height of the convex portion and the number of convex portions per 5 cm are measured.
In addition, a perpendicular is drawn with respect to the 1st line segment from the vertex of all the convex parts formed in the surface of the intermediate | middle layer, and the convex part with the longest perpendicular | vertical length is a convex part which becomes the most convex.

When producing a holding sealing material by a papermaking method, first, inorganic fibers are aggregated to some extent to form a flock. That is, it can be said that the size of the floc (aggregate) is larger as the maximum height of the convex portion is higher. When the floc is too large, the density of the inorganic fiber is high in the part derived from the floc, and the density of the inorganic fiber in the part not derived from the floc is low. Therefore, it is preferable that the size of the floc is not too large. When the maximum height of the convex portion is 1 mm or less, the density of the inorganic fibers constituting the holding sealing material is not excessively uneven, and sufficient wind resistance can be obtained. When the maximum height of the convex portion exceeds 1 mm, excessive unevenness occurs in the density of the inorganic fibers constituting the holding sealing material, and wind resistance is reduced.

It can be said that the greater the number of convex portions, the greater the proportion of inorganic fibers oriented in the direction parallel to the thickness direction in the holding sealing material. If the number of convex portions is 3 or more per 5 cm, the inorganic sealing fibers are sufficiently oriented in a direction parallel to the thickness direction of the holding sealing material, so that the holding sealing material exhibits a high surface pressure. Can do.
The number of convex portions is counted by the number of vertices.

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

The holding sealing material of the present invention preferably contains an organic binder.

The organic binder is not particularly limited, and examples thereof include rubber resins, styrene resins, silicone resins, acrylic resins, polyester resins, and polyurethane resins.
The organic fiber can be contained in the inorganic fiber by attaching the emulsion liquid (organic binder solution) containing the organic binder to the inorganic fiber and removing the solvent.

The holding sealing material of the present invention preferably contains 2 to 10% by weight, more preferably 3 to 9% by weight, in terms of solid content with respect to the total amount of the holding sealing material, More preferably 4 to 8% by weight is contained.
When the content of the organic binder is less than 2% by weight, the holding sealing material may not be sufficiently flexible, and cracks may occur when the holding sealing material is wound around the exhaust gas treatment body. There is. 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 −5 ° C. or lower, further preferably −10 ° C. or lower, and particularly 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 holding sealing material of the present invention preferably further contains 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 2 to 9% by weight, based on the total amount of the holding sealing material. More preferably, the content is 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.
In addition, when the surface charge of the organic binder and inorganic binder disperse | distributed in a solvent differs, an organic binder and an inorganic binder may self-aggregate.
When the self-aggregation of the organic binder and the inorganic binder is not sufficient, the organic binder and the inorganic binder may be actively aggregated by adding a flocculant or the like.

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, silica, alumina silica, mullite, biosoluble fiber and glass fiber. It is preferable to use a fiber having a large diameter fiber or a fiber length that can be adapted to the environmental regulations of each country, such as heat resistance and wind resistance.
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 manufactured by a papermaking method.
The average fiber length of the inorganic fibers constituting the mat obtained by the papermaking method is preferably 200 to 20000 μm, more preferably 300 to 10000 μm, and further preferably 500 to 1500 μm.
If the average fiber length of the inorganic fibers is less than 200 μm, the fiber length of the inorganic fibers is too short, so that the characteristics as fibers are no longer substantially exhibited, and suitable entanglement between the fibers when formed into a mat-like fiber aggregate It does not occur and it becomes difficult to obtain a sufficient surface pressure. Furthermore, the inorganic fibers are likely to be scattered by the pressure of the exhaust gas, and wind resistance may be reduced.
In addition, when the average fiber length of the inorganic fibers exceeds 20000 μm, 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 paper making process becomes too strong. Inorganic fiber tends to accumulate non-uniformly when formed into a fiber-like aggregate.
In addition, it is preferable that the ratio of the fiber whose fiber length is 200 micrometers or less among inorganic fibers is 40% or less, It is more preferable that it is 30% or less, It is further more preferable that it is 25% or less.
The fiber length is measured by using tweezers so that the inorganic fibers are not broken from the mat, and the fiber length is measured using an optical microscope. In this specification, 300 inorganic fibers are extracted, and the ratio and average fiber length of fibers having a fiber length of 200 μm or less are determined.
When collecting inorganic fibers from the mat, if necessary, the mat may be degreased and put into water to collect the inorganic fibers 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.

The thickness of the holding sealing material is not particularly limited, but is preferably 2.0 to 30 mm. If the thickness of the holding seal material exceeds 30 mm, the flexibility of the holding seal material is lost, which makes it difficult to handle the holding seal material when it is wound around the exhaust gas treatment 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. .

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

Next, the manufacturing method of the holding sealing material of the present invention will be described as an example of the method of manufacturing the holding sealing material of the present invention.
The manufacturing method of the holding sealing material of the present invention includes a fiber-opening step for opening inorganic fibers, a classification step for classifying the opened inorganic fibers, a solvent, an organic binder, and an inorganic binder for the classified inorganic fibers. And a slurry preparation step for preparing a slurry by mixing with a papermaking step for producing an inorganic fiber aggregate by papermaking the slurry, wherein the fiber length is 200 μm in the classification step. It is characterized by removing a part or all of the inorganic fibers below.

(A) Opening process First, the opening process will be described.
In the fiber opening step, the inorganic fibers are shortened (also referred to as fiber opening) with a pulverizer such as a feather mill or a stirrer such as a pulper, and adjusted to a desired fiber length.

The inorganic fiber used in the opening process is not particularly limited, but an inorganic fiber produced by a melting method or an inorganic fiber produced by an inorganic salt method can be used.
As a method for producing inorganic fibers by a melting method, for example, a material (for example, silicon and aluminum) that constitutes inorganic fibers is heated and melted, and the melt is pressed onto a wheel that rotates at high speed to be fiberized ( And a method of forming fibers by pressing compressed air against the melt (also referred to as a blow method).
As a method for producing inorganic fibers by the inorganic salt method, for example, spinning a mixed solution obtained by adding an organic polymer such as polyvinyl alcohol to an aqueous solution containing materials (for example, aluminum and silicon) constituting the inorganic fibers by a blowing method. And a method of obtaining an inorganic fiber precursor and firing the inorganic fiber precursor.

(B) Classification step Subsequently, the classification step will be described.
The inorganic fibers opened in the (a) opening step are classified in the classification step.
In the classification step, a part or all of the inorganic fibers having a fiber length of 200 μm or less are removed from the opened inorganic fibers using a classifier.
The proportion of inorganic fibers having a fiber length of 200 μm or less in the classified inorganic fibers is preferably 40% or less, more preferably 30% or less, and even more preferably 25% or less.
When the proportion of inorganic fibers having a fiber length of 200 μm or less in the classified inorganic fibers exceeds 40%, the inorganic fibers constituting the obtained holding sealing material may be easily scattered by the wind pressure of the exhaust gas.
The average fiber length of the inorganic fibers obtained by the classification step is preferably 200 to 20000 μm, more preferably 300 to 10000 μm, and further preferably 500 to 1500 μm.

Examples of the classifier include a dry centrifugal classifier (also referred to as a dry cyclone) and a wet centrifugal classifier (also referred to as a wet cyclone), and a wet cyclone is preferable.

(C) Slurry preparation step Next, the slurry preparation step will be described.
In the slurry preparation step, the classified inorganic fibers are dispersed in a solvent to obtain a mixed solution (also referred to as a slurry). Although content of the inorganic fiber in the said slurry is not specifically limited, For example, it may be 0.05-2.0 weight%.
The slurry is stirred at a stirring speed such that the average fiber length of the inorganic fibers adjusted by the classification step (b) does not change. (C) When the average fiber length of the inorganic fibers is in the above-described range in the slurry preparation step, it becomes easy to form flocs in which the inorganic fibers are loosely entangled with each other. Anisotropy is difficult to form and tends to be strong entanglement. That is, by adjusting the average fiber length of the inorganic fibers, it is possible to control the floc aggregation form (whether the aggregation has anisotropy, etc.).

You may add an organic binder, an inorganic binder, a pH adjuster, etc. to the said slurry as needed. When adding an organic binder and an inorganic binder, it is preferable to add an organic binder after mixing an inorganic fiber and an inorganic binder first and leaving still for a while.
At the beginning of the slurry preparation process, the inorganic binder and the inorganic binder are first mixed to ensure that the inorganic binder adheres to the surface of the inorganic fiber, thus increasing the friction between the inorganic fibers and improving the surface pressure. be able to.
Furthermore, you may add the aggregate which aggregated the organic binder and the inorganic binder with the flocculent with respect to the said slurry.
The content of the organic binder in the slurry is preferably 2 to 10 parts by weight with respect to 100 parts by weight of the inorganic fiber, and the content of the inorganic binder in the slurry is 0 with respect to 100 parts by weight of the inorganic fiber. It is preferable that it is 3-5 weight part. When the content of the organic binder and the inorganic binder is within the above range, it becomes easy to form flocs in which inorganic fibers are loosely entangled with each other.

Furthermore, in the slurry preparation step, the size of the floc and the form of the aggregate of inorganic fibers can be prepared by adding an organic binder, an inorganic binder, a pH adjuster, or the like to the slurry.
For example, an anionic organic binder (an organic binder having a negative surface charge in the solvent) is added to the slurry obtained in the slurry preparation step (c), and then a cationic inorganic binder (solvent) By adding an inorganic binder having a positive surface charge in the inside, the organic binder and the inorganic binder aggregate while taking in the inorganic fibers, so that a floc in which the inorganic fibers are entangled with each other is formed. Thereafter, the flocs are further aggregated by adding a flocculant and stirring. At this time, by adjusting the addition amount of the flocculant and the stirring speed, the size of the floc can be adjusted to an appropriate size.
Examples of the flocculant include inorganic flocculants such as polyaluminum chloride, aluminum sulfate, and ferric sulfate, and polymer flocculants such as polyacrylamide.

(D) Papermaking process Subsequently, after pouring the slurry into a molding machine having a mesh for filtration on the bottom surface, the solvent in the slurry is desolvated to obtain an inorganic fiber aggregate.

The solvent removal treatment is not particularly limited as long as the solvent contained in the mat can be removed. For example, the solvent can be removed by means such as compression, rotation, suction, and reduced pressure.

In the method for producing a holding sealing material of the present invention, (d) a drying step of drying the inorganic fiber aggregate obtained by the paper making step by heating or the like may be performed.
In the drying step, the mat can be dried using a method such as hot air drying, ventilation drying, or compression drying with a hot plate.
Although the temperature at the time of drying is not specifically limited, For example, it can carry out at 110-200 degreeC.

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

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

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.

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

FIG. 3 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus.
As shown in FIG. 3, 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 seal 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. 4 is a perspective view schematically showing an example of the exhaust gas treating body constituting the exhaust gas purifying apparatus.

An exhaust gas treatment body 120 shown in FIG. 4 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. 4, 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. 3, since the holding sealing material 110 is interposed around the side surface of the exhaust gas treatment body 120 and absorbs the impact, the exhaust gas treatment body 120 is cracked by mechanical shock or 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. 3, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purification apparatus 100 (in FIG. 3, 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. 5 is a diagram schematically illustrating an example of a method for manufacturing an exhaust gas purification apparatus.

As shown in FIG. 5, 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. In addition, the metal casing is formed into a shape that can be separated into the first casing and the second casing parts, and the wrapping body 140 is placed on the first casing and then the second casing is covered and sealed. Shell method etc. are mentioned.
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 effect of the manufacturing method of the holding sealing material, the exhaust gas purifying apparatus, and the holding sealing material of the present invention will be described.

(1) The holding sealing material of the present invention is a test piece obtained by cutting the holding sealing material with a size of 50 mm × 50 mm so that the intermediate layer is exposed, and when the test piece is viewed from the cut surface, The shortest distance between the first line segment, which is the line segment connecting the concave part that is the most concave on the surface of the layer and the concave part that is the second concave, and the apex of the convex part that is the most convex on the surface of the intermediate layer is 1 mm or less, and the number of convex portions is 3/5 cm or more.
That is, it can be said that the inorganic fibers constituting the holding sealing material of the present invention are sufficiently oriented with respect to the thickness direction of the holding sealing material, and the density of the inorganic fibers is not uneven. Therefore, the holding sealing material of the present invention can exhibit a sufficient surface pressure while improving the wind resistance.

(2) Since the exhaust gas purifying apparatus of the present invention includes the holding sealing material of the present invention, the holding sealing material is excellent in wind resistance and can stably hold the exhaust gas purifying apparatus.

(3) In the manufacturing method of the holding sealing material of the present invention, flocs in which inorganic fibers are loosely entangled can be easily formed. Therefore, it is possible to produce a holding sealing material in which inorganic fibers are sufficiently entangled and can exhibit a sufficient surface pressure.

(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
(Inorganic fiber preparation process)
First, an inorganic fiber to be opened in the opening process was produced.
With respect to the basic aluminum chloride aqueous solution prepared so that the Al content is 70 g / L and Al: Cl = 1: 1.8 (atomic ratio), the composition ratio in the inorganic fiber after firing is Al _2. A silica sol was blended so that O ₃ : SiO ₂ = 72: 28 (weight ratio), and an organic polymer (polyvinyl alcohol) was added in an appropriate amount to prepare a mixed solution.
The obtained mixed solution was concentrated to obtain a spinning mixture, and the spinning mixture was spun by a blowing method to prepare an inorganic fiber precursor. Subsequently, the inorganic fiber precursor was compressed to produce a continuous sheet-like material. The compressed sheet was fired at a maximum temperature of 1250 ° C., and inorganic fibers containing alumina and silica at 72 parts by weight: 28 parts by weight and having an average fiber diameter of 5.6 μm were produced.

(A) Fiber opening step Next, 168.3 g of the inorganic fiber was put into 75 L of water, and stirred at 60 Hz for 10 minutes using a pulper, whereby the inorganic fiber was stirred and shortened.

(B) Classification process Thereafter, a part of the inorganic fibers having a fiber length of 200 μm or less was removed using a wet cyclone to obtain a classified inorganic fiber solution.
The classified inorganic fiber solution was observed with an optical microscope, and the average fiber length of the inorganic fibers and the ratio of the number of fibers having a fiber length of 200 μm or less were determined. The results are shown in Table 1.

(C) Slurry preparation step 12 Acrylic latex solution (Nipol LX852, manufactured by Zeon Corporation) in which an acrylic resin is dispersed in water with respect to the solution of the classified inorganic fiber obtained in the classification step (b). A slurry was prepared by charging 3 g and stirring at 60 Hz for 1 minute.

Using Tappi type papermaking machine (d) papermaking process 335 mm × 335 mm, by papermaking the slurry, (weight per unit area) basis weight to obtain an inorganic fiber aggregate 1500 g / ^{m 2.}

(E) Drying step In a state where the obtained inorganic fiber aggregate is compressed to 7.0 mm in thickness using a press dryer, the inorganic fiber aggregate is dried by heat treatment at 140 ° C. for 15 minutes, A holding sealing material according to Example 1 was produced.

(Example 2)
(A) In the fiber opening step, the average fiber length of the inorganic fibers was changed by setting the stirring time using the pulper to 7 minutes. Then, in (c) slurry preparation step, before adding acrylic latex, first, 6.8 g of alumina sol (Nissan Chemical Industry Co., Ltd., alumina sol 520) was charged, stirred at 60 Hz for 1 minute, and then allowed to stand. . Further, after adding acrylic latex, 336.6 g of 0.5% by weight aqueous solution of nonionic polyacrylamide (BASF, Percol 47NS) was added as a polymer flocculant and stirred at 60 Hz for 1 minute. A holding sealing material according to Example 2 was produced in the same procedure as in Example 1.

(Comparative Example 1)
(B) In the classification step, a holding sealing material according to Comparative Example 1 was produced in the same procedure as Example 1 except that the short fibers were not removed by a wet cyclone.

(Comparative Example 2)
(A) In the fiber opening step, the stirring time using the pulper is 15 minutes, and in the (b) classification step, short fibers are not removed by a wet cyclone, and the same procedure as in Example 1 is compared. A holding sealing material according to Example 1 was produced.

(Measurement of peeling and unevenness of intermediate layer)
The holding sealing materials according to Examples 1 and 2 and Comparative Examples 1 and 2 were cut to a size of 50 × 50 mm using a Thomson blade to prepare three test pieces. Then, each test piece was peeled by the method mentioned above, and the intermediate | middle layer was exposed. Then, the test piece which exposed the intermediate | middle layer was image | photographed with the commercially available digital camera (the Ricoh Imaging company make, compact digital camera PENTAX Optio W60). Import the captured image into a computer and measure the number of convex parts per 5 cm and the maximum height of the convex parts. From the data of 6 test pieces, the number of convex parts per 5 cm and the maximum height of the convex parts The average value was obtained. The results are shown in Table 1.

(Wind resistance test)
A wind resistance test was performed using the following wind texture measuring apparatus.
The wind measurement device continuously holds the upper plate member and the lower plate member that can hold the sample at a predetermined compression density and the air supplied from the outside by sandwiching the sample for wind resistance test from above and below. In particular, the air nozzle can be adjusted so as to blow on the side surface of the sample with a predetermined wind pressure.
In this specification, a compression density shall show the calculated value which computed the bulk density of the sample after compression using the bulk density of the sample before compression. For example, if the sample is compressed so that the apparent volume is halved, the compression density is twice the bulk density of the sample before compression.

The wind resistance test was performed according to the following procedure.
The holding sealing material according to each example and each comparative example was cut into 25 mm squares to obtain wind resistance test samples. Next, the sample was sandwiched and held between the upper plate member and the lower plate member so that both surfaces of the sample were in contact with the upper plate member and the lower plate member. At this time, the compression density of the sample was adjusted to 0.3 g / cm ³ . Further, the position of the air nozzle was adjusted so that the distance from the side surface of the sample to the tip of the air nozzle was 3.6 mm. In this state, the sample was touched by blowing air continuously for 3 hours under a wind pressure of 135 kPa. This operation was performed under a temperature condition of 700 ° C. About the hole formed in the side surface of the sample touched, the distance from the surface of a sample to the bottom of a hole was measured, and it was set as the amount of winds (mm).
As a result, the amount of wind in each example and comparative example was evaluated according to the following criteria. The results are shown in Table 1.
○: Touch amount is less than 3 mm Δ: Touch amount is 3 mm or more and less than 5 mm ×: Touch amount is 5 mm or more

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

(Measurement of organic binder and inorganic binder content (% by weight))
The holding sealing material obtained in each example and each comparative example was collected as a constant weight sample, an organic solvent (tetrahydrofuran) in which the organic binder contained in the sample was dissolved was selected, and the organic binder was dissolved in a Soxhlet extractor. And separated from the sample. At this time, the inorganic binder contained in the dissolved organic binder is also separated from the sample, and the organic binder and the inorganic binder are recovered in an organic solvent.
The organic solvent composed of the organic binder and the inorganic binder was put in a crucible, and the organic solvent was removed by evaporation by heating.
The residue remaining in the crucible was regarded as the total weight of the organic binder and the inorganic binder relative to the holding sealing material, and the content (% by weight) relative to the weight of the holding sealing material was calculated.
Furthermore, the crucible was heat-treated at 600 ° C. for 1 hour to burn off the organic binder. Since the inorganic binder remained in the crucible, this was regarded as the content (% by weight) of the inorganic binder with respect to the total of the organic binder and the inorganic binder, and the content was calculated. The remainder is the organic binder content (% by weight).
About the holding sealing material which concerns on each Example and each comparative example, content of the organic binder and the inorganic binder was measured. The results are shown in Table 1.

In this example and this comparative example, the contents of the organic binder and the inorganic binder can be measured by the above method. However, when the organic binder is a crosslinkable resin, all of the crosslinkable resin can be eluted with an organic solvent. Have difficulty. Therefore, in that case, the inorganic fibers (not containing the binder) constituting the mat are collected and the weight (A1) is measured, and the organic binder and the inorganic binder are added under the same conditions as in this example and this comparative example. After making it adhere to an inorganic fiber, it fully dries and measures a weight (A2). Thereafter, heat treatment is performed at 600 ° C. for 1 hour, and the weight is further measured (A3). Since A2-A3 is the weight of the organic binder and A3-A1 is the weight of the inorganic binder, the content (% by weight) of the organic binder and the inorganic binder with respect to the weight of the sample can be calculated.

As shown in Table 1, the holding sealing materials according to Examples 1 and 2 were provided with sufficient wind resistance, and furthermore, since the surface pressure exceeded 30 kPa, sufficient surface pressure could be exhibited. In contrast, the holding sealing materials according to Comparative Examples 1 and 2 were not sufficient in wind resistance and surface pressure.
From the above, it has been found that the holding sealing material of the present invention can exhibit high surface pressure in addition to excellent wind resistance.

DESCRIPTION OF SYMBOLS 10 Test piece 30 Surface 31 of intermediate | middle layer The most concave part 32 The second concave part 33 The first line segment 34 The most convex part 35 Perpendicular line 100 Exhaust gas purification device 110 Holding sealing material 120 Exhaust gas treatment body 130 Metal casing

Claims (9)

A holding sealing material comprising a layered mat obtained by a papermaking method, including inorganic fibers,
When the holding sealing material is peeled off so that the intermediate layer of the holding sealing material is exposed, the surface of the intermediate layer is a undulating surface having a concave portion and a convex portion,
A test piece obtained by cutting the holding sealing material in a size of 50 mm × 50 mm is peeled off so that the intermediate layer is exposed, and when the test piece is viewed from the cut surface, a concave portion which is the most concave on the surface of the intermediate layer and The shortest distance between the first line segment, which is a line segment connecting the concave part that is the second concave, and the apex of the convex part that is the most convex on the surface of the intermediate layer, and further, A holding sealing material characterized in that the number is 3/5 cm or more. The holding sealing material according to claim 1, wherein a ratio of fibers having a fiber length of 200 µm or less among the inorganic fibers is 40% or less, and an average fiber length of the inorganic fibers is 500 to 1500 µm. The holding sealing material according to claim 1, wherein the holding sealing material contains an organic binder. The holding sealing material according to claim 3, wherein the content of the organic binder is 2 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 3 or 4, wherein the glass transition temperature (Tg) of the organic binder is 5 ° C or lower. The holding sealing material according to claim 1, wherein the holding sealing material contains an inorganic binder. The holding sealing material according to claim 6, wherein the content of the inorganic 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 seal according to any one of claims 1 to 7, wherein the inorganic fiber is composed of at least one selected from the group consisting of alumina, silica, alumina-silica, mullite, biosoluble fiber, and glass fiber. Wood. An exhaust gas purification apparatus comprising: an exhaust gas treatment body; a metal casing that houses the exhaust gas treatment body; and a holding sealing material that is disposed between the exhaust gas treatment body and the metal casing and holds the exhaust gas treatment body. And
The exhaust gas purification apparatus, wherein the holding sealing material is the holding sealing material according to any one of claims 1 to 8 .

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