WO2021049274A1

WO2021049274A1 - Mat material, exhaust gas purification device, mat material-equipped exhaust tube, and exhaust system

Info

Publication number: WO2021049274A1
Application number: PCT/JP2020/031607
Authority: WO
Inventors: 隆彦岡部; 前田　敏幸
Original assignee: イビデン株式会社
Priority date: 2019-09-10
Filing date: 2020-08-21
Publication date: 2021-03-18

Abstract

The objective of the present invention is to provide a mat material wherefrom scattering of inorganic fibers can be prevented, and wherein the surface pressure during use does not drop readily. A mat agent according to the present invention is a mat material comprising inorganic fibers, characterized in that the mat material includes a fiber scattering prevention agent containing a water-soluble polymer, wherein the proportion in weight of the water-soluble polymer over the mat material (water-soluble polymer weight/mat material weight) is 3.0% by weight or less, and the water-soluble polymer is solid at room temperature and does not melt at 300°C.

Description

Mat material, exhaust gas purification device, exhaust pipe with mat material and exhaust system

The present invention relates to a mat material, an exhaust gas purification device, an exhaust pipe with a mat material, and an exhaust system.

Exhaust gas emitted from an internal combustion engine such as a diesel engine contains particulate matter (hereinafter, also referred to as PM), and in recent years, it has become a problem that this PM causes harm to the environment and the human body. .. In addition, since the exhaust gas also contains harmful gas components such as CO, HC, and NOx, there are concerns about the effects of these harmful gas components on the environment and the human body.

Therefore, as an exhaust gas purification device that collects PM in the exhaust gas and 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. And various exhaust gas purification devices composed of a holding seal material (mat material) disposed between the exhaust gas treatment body and the casing have been proposed. This holding seal material (mat material) prevents the exhaust gas treatment body from coming into contact with the casing covering the outer periphery of the exhaust gas treatment body due to vibration or impact generated by the running of an automobile or the like, and prevents the exhaust gas treatment body and the casing from being damaged. It is arranged mainly for the purpose of preventing exhaust gas from leaking from between.

Since the holding seal material (mat material) is a filamentous body and has a light specific gravity, when the holding seal material (mat material) is assembled to the catalyst carrier and the shell to prepare a catalytic converter, the surface of the holding seal material (mat material) is used. Inorganic fibers may be scattered in the air. Therefore, there is a possibility that the working environment of the work place where the above-mentioned assembly work is performed may be deteriorated, and it is necessary for the worker to wear a dust mask or the like to perform the work.

In order to prevent such scattering of inorganic fibers, Patent Document 1 describes that a mat material is impregnated with an acrylic resin as an organic binder.
Further, Patent Document 2 describes that the mat material is impregnated with silicone oil.

Japanese Unexamined Patent Publication No. 2014-92150 International Release 2017/141724

The mat material placed in the exhaust gas purification device or the like receives heat from the exhaust gas and becomes hot. When the matte material is impregnated with an acrylic resin as in Patent Document 1, there is a problem that the acrylic resin is decomposed by heat and the generated thermal decomposition gas has a strong odor.
Further, as the acrylic resin is decomposed, the surface pressure of the mat material is lowered, and there is also a problem that the exhaust gas treated body is likely to fall off.

Further, when the mat material is impregnated with silicone oil as in Patent Document 2, there is a problem that the mat material becomes too soft and difficult to handle, or a sufficient surface pressure cannot be obtained in the mat material in the initial state. ..

The present invention has been made in view of the above problems, and an object of the present invention is to provide a mat material that is easy to handle, can prevent scattering of inorganic fibers, and does not easily reduce the surface pressure during use. is there.

That is, the mat material of the present invention is a mat material made of inorganic fibers, and the mat material contains a fiber scattering inhibitor containing a water-soluble polymer, and the weight ratio of the water-soluble polymer to the mat material ( The weight of the water-soluble polymer / the weight of the mat material) is 3.0 wt% or less, and the water-soluble polymer is characterized in that it is solid at room temperature and does not melt at 300 ° C.

In the mat material of the present invention, the weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) is 3.0 wt% or less.
Therefore, the scattering of inorganic fibers can be sufficiently suppressed.
If this ratio exceeds 3.0 wt%, the mat material becomes hard and tends to lose its flexibility. Therefore, the mat material becomes difficult to handle.
The weight ratio of the water-soluble polymer to the mat material is preferably 0.01 to 3.0 wt%, more preferably 0.05 to 3.0 wt%.

In the mat material of the present invention, the water-soluble polymer is solid at room temperature.
That is, in the mat material of the present invention, the water-soluble polymer adheres to the inorganic fiber in a solid state.
Therefore, the surface of the inorganic fibers is roughened, and the friction between the inorganic fibers is large. With such a mat material, the surface pressure becomes large.

In the mat material of the present invention, the water-soluble polymer does not melt at 300 ° C.
When the water-soluble polymer melts at 300 ° C., when the mat material is heated to 300 ° C., the water-soluble polymer adhering to the surface of the inorganic fibers melts, and the inorganic fibers become slippery. Therefore, the surface pressure of the mat material is reduced.
However, when the water-soluble polymer does not melt at 300 ° C., even if the mat material is heated to about 300 ° C., the state of the water-soluble polymer does not change, so that the surface pressure of the mat material is unlikely to decrease.

In the mat material of the present invention, the water-soluble polymer is preferably a water-soluble polycarboxylic acid salt, and more preferably a water-soluble sodium polycarboxylic acid.
These compounds are difficult to melt at 300 ° C. Therefore, even if the mat material reaches about 300 ° C., the surface pressure is unlikely to decrease.
Further, these compounds are less likely to generate pyrolysis gas and have less strong odor.

In the mat material of the present invention, the odor index measured by the odor sensor for the odor of the decomposition gas generated by placing the mat material on a hot plate at 500 ° C. is 1.0 for acrylic resin as a fiber scattering inhibitor. The odor index of the matte material adhered by weight% is preferably 80 or less as a relative value of 130.
The mat material of the present invention is designed so that the odor index by the odor sensor falls within a low range even if the fiber scattering inhibitor is thermally decomposed. Therefore, when the mat material is arranged around the exhaust pipe, it is possible to prevent the odor in the engine room from becoming severe.

For the odor index in the present specification, a mat material is placed on a hot plate at 500 ° C. using a handy odor monitor OMX-SRM (manufactured by Shinei Technology Co., Ltd.), which is a semiconductor type odor sensor, as an odor sensor. It is an index that measures the decomposition gas generated. Further, it is a relative value with the odor index of a mat material to which 1.0% by weight of acrylic resin (Nipol Lx854E, manufactured by Nippon Zeon Corporation) is attached as a fiber scattering inhibitor as 130.

The exhaust gas purification device of the present invention comprises an exhaust gas treatment body, a metal casing accommodating the exhaust gas treatment body, and a mat material arranged between the exhaust gas treatment body and the metal casing and holding the exhaust gas treatment body. The exhaust gas purifying device provided, wherein the mat material is the mat material of the present invention.

As described above, the mat material of the present invention can sufficiently suppress the scattering of inorganic fibers.
Therefore, it is possible to prevent the inorganic fibers from scattering from the mat material during the manufacture of the exhaust gas purification device.
Further, the water-soluble polymer in the mat material of the present invention is difficult to be melted by heat and is not easily decomposed by heat.
Therefore, even if the exhaust gas flows into the exhaust gas purification device of the present invention and the mat material is heated, the surface pressure of the mat material is unlikely to decrease and the odor is unlikely to become strong.

The exhaust pipe with a mat material of the present invention is an exhaust pipe with a mat material including an exhaust pipe, a mat material arranged so as to cover the exhaust pipe, and a metal cover arranged outside the mat material. The mat material is the mat material of the present invention.

As described above, the mat material of the present invention can sufficiently suppress the scattering of inorganic fibers.
Therefore, it is possible to prevent the inorganic fibers from scattering from the mat material during the production of the exhaust pipe with the mat material.
Further, the water-soluble polymer in the mat material of the present invention is difficult to be melted by heat and is not easily decomposed by heat.
Therefore, even if the exhaust gas flows into the exhaust pipe with the mat material of the present invention and the mat material is heated, when the mat material is arranged around the exhaust pipe, the odor in the engine room is unlikely to become strong.

The exhaust system of the present invention is characterized in that the mat material of the present invention is arranged on the inner peripheral side of a heat insulator arranged on the outside of an exhaust manifold in an automobile exhaust system.

As described above, the mat material of the present invention can sufficiently suppress the scattering of inorganic fibers.
Therefore, it is possible to prevent the inorganic fibers from scattering from the mat material during the manufacture of the exhaust system.
Further, the water-soluble polymer in the mat material of the present invention is difficult to be melted by heat and is not easily decomposed by heat.
Therefore, even if the exhaust gas flows into the exhaust system of the present invention and the mat material is heated, the odor is unlikely to become strong.

FIG. 1 is a perspective view schematically showing an example of the mat material of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of an exhaust gas purification device provided with the mat material of the present invention. FIG. 3A is a perspective view schematically showing an example of an exhaust gas treatment body constituting the exhaust gas purification device of the present invention. FIG. 3B is a cross-sectional view taken along the line AA of FIG. 3A. FIG. 4 is a cross-sectional view schematically showing an example of an exhaust pipe with a matte material provided with the matte material of the present invention. FIG. 5 is a perspective view schematically showing another example of the exhaust system of the present invention. FIG. 6 is a cross-sectional view schematically showing a part of the exhaust system of the present invention shown in FIG.

(Detailed description of the invention)
Hereinafter, the mat material of the present invention will be described in detail.
FIG. 1 is a perspective view schematically showing an example of the mat material of the present invention.

As shown in FIG. 1, the mat material 10 is made of inorganic fibers and has a rectangular shape in a plan view.
Further, when the mat material 10 is wound around an object, a convex portion 11a is provided on one end portion 11 of the mat material 10 so that the end portions are fitted to each other, and the other end portion 12 is provided with a convex portion 11a. A recess 12a is provided.
When such a convex portion 11a and a concave portion 12a are provided, the sealing property is improved when the mat material 10 is arranged in the exhaust gas purification device described later.
The mat material of the present invention does not have to have a convex portion and a concave portion at the end portion of the mat material.

The mat material 10 contains a fiber scattering inhibitor containing a water-soluble polymer.
The weight ratio of the water-soluble polymer to the mat material 10 (weight of the water-soluble polymer / weight of the mat material) is 3.0 wt% or less. This weight ratio is preferably 0.01 to 3.0 wt%, more preferably 0.05 to 3.0 wt%, further preferably 0.1 to 3.0 wt%, and 0. .2 to 2.5 wt% is particularly preferable, and 0.3 to 2.0 wt% is more particularly preferable.
With such a weight ratio, scattering of inorganic fibers can be sufficiently suppressed.
If this ratio is less than 0.01 wt%, the amount of the water-soluble polymer is small, and it becomes difficult to prevent the inorganic fibers from scattering.
If this ratio exceeds 3.0 wt%, the mat material becomes hard and tends to lose its flexibility. Therefore, it is difficult for the mat material to be wrapped around the curved surface of the surface of the exhaust pipe, which makes it difficult to handle.

Further, in the mat material 10, the water-soluble polymer is solid at room temperature.
In the mat material 10, the water-soluble polymer 30 is attached to the inorganic fiber 20 in a solid state.
Therefore, the surface of the inorganic fibers 20 is roughened, and the friction between the inorganic fibers 20 is large. With such a mat material 10, the surface pressure becomes large.
In this specification, room temperature means 15 to 30 ° C.

Further, in the mat material 10, the water-soluble polymer does not melt at 300 ° C.
When the water-soluble polymer melts at 300 ° C., when the mat material is heated to 300 ° C., the water-soluble polymer adhering to the surface of the inorganic fibers melts, and the inorganic fibers become slippery. Therefore, the surface pressure of the mat material is reduced.
However, when the water-soluble polymer does not melt at 300 ° C., even if the mat material is heated to about 300 ° C., the state of the water-soluble polymer does not change, so that the surface pressure of the mat material is unlikely to decrease.

Examples of such a water-soluble polymer include a water-soluble polycarboxylic acid and a water-soluble polycarboxylic acid salt.
Among these, a water-soluble polycarboxylic acid salt is preferable, and a water-soluble sodium polycarboxylic acid is more preferable.
These compounds are difficult to melt at 300 ° C. Therefore, even if the mat material reaches about 300 ° C., the surface pressure is unlikely to decrease.
Further, these compounds are less likely to generate pyrolysis gas and have less strong odor.

The inorganic fibers constituting the mat material 10 are not particularly limited, and examples thereof include alumina fibers, alumina-silica fibers, silica fibers, biosoluble fibers, glass wool, and rock wool. Of these, alumina-silica fibers are preferred.
These inorganic fibers have high heat resistance, and the mat material formed of such inorganic fibers does not easily change its shape due to temperature changes.

Further, when the inorganic fiber is an alumina-silica fiber, the composition ratio of alumina to silica is preferably alumina (Al ₂ O ₃ ): silica (SiO ₂ ) = 60: 40 to 80:20 in terms of weight ratio. , Alumina (Al ₂ O ₃ ): Silica (SiO ₂ ) = 70: 30 to 74: 26 is more preferable.

The average length of the inorganic fibers is preferably 0.1 to 150 mm, more preferably 0.2 to 80 mm.
If the average fiber length of the inorganic fibers is less than 0.1 mm, the fiber lengths of the inorganic fibers are too short, so that the inorganic fibers are not sufficiently entangled with each other, it becomes difficult to obtain the strength of the mat material, and the shape of the mat material is maintained. The sex tends to decrease.
If the average fiber length of the fibers exceeds 150 mm, the fiber lengths of the fibers are too long, so that the number of fibers constituting the mat material is reduced, and the denseness is lowered.

The average fiber diameter of the inorganic fibers is preferably 1 to 20 μm, more preferably 2 to 15 μm, and even more preferably 3 to 10 μm.
When the average fiber diameter of the inorganic fiber is less than 1 μm, the breaking load is low and the inorganic fiber is easily broken by an impact or the like.
When the average fiber diameter of the inorganic fiber exceeds 20 μm, defects inside the fiber are likely to occur, the strength of the inorganic fiber is lowered, and the surface pressure value as a mat material for holding the exhaust gas treated body is lowered.

An inorganic binder may be attached to the mat material 10.
Examples of the inorganic binder include particles such as alumina, silica, and zirconia. These particles are preferably derived from an inorganic sol dispersion solution (alumina sol, silica sol, zirconia sol, etc.).
When an inorganic binder is attached to the mat material, the frictional force between the inorganic fibers is improved, so that the warping force of the mat material is improved, and the mat material is misaligned when it is sandwiched between exhaust pipes and arranged as a heat insulating material. Is suppressed.
Further, when the mat material is wrapped around the exhaust gas treatment body and sandwiched between the metal casing and the exhaust gas treatment body and arranged as a holding seal material, the holding power of the exhaust gas treatment body is improved.
Further, even when the mat material is not arranged by being sandwiched between something, the frictional resistance of the mat material increases due to the adhesion of the inorganic binder, so that the misalignment of the mat material is suppressed.

In the mat material 10, the odor index measured by the odor sensor for the odor of the decomposition gas generated by placing the mat material 10 on a hot plate at 500 ° C. is 1.0% by weight of acrylic resin as a fiber scattering inhibitor. The relative value of the attached mat material with the odor index as 130 is preferably 80 or less, more preferably 65 or less, and further preferably 55 or less.
The mat material of the present invention is designed so that the odor index by the odor sensor falls within a low range even if the fiber scattering inhibitor is thermally decomposed. Therefore, when the mat material is arranged around the exhaust pipe, it is possible to prevent the odor in the engine room from becoming severe.

Next, the method for producing the mat material of the present invention will be described.
The mat material of the present invention may be produced by a needle punching method or a papermaking method.
Each method will be described below.

(1) Method for Producing Matte Material of the Present Invention by Needle Punching Method (1-1) Inorganic Fiber Precursor Fabrication Step Inorganic fiber by spinning a spinning mixture containing raw materials for inorganic fibers such as alumina and silica by the blowing method. Make a precursor.

(1-2) Firing Step Subsequently, the inorganic fiber precursor is compressed to prepare a continuous sheet-like product having a predetermined size, which is subjected to needle punching treatment and then calcining treatment to obtain alumina. Prepare an inorganic fiber assembly consisting of fibers.
The density of needle punching is preferably 0.1 to 30 pieces / cm ² .

(1-3) Step of Applying Fiber Scattering Inhibitor Next, a water-soluble polymer is dissolved in water to prepare an aqueous solution of the fiber scattering inhibitor.
Then, the fiber scattering inhibitor aqueous solution is adhered to the inorganic fiber aggregate so that the weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) is 3.0 wt% or less. , Then dry.
As a result, the water-soluble polymer is deposited on the surface of the inorganic fiber, and unevenness is formed on the surface of the inorganic fiber.

In addition, in the above-mentioned (1-3) fiber scattering inhibitor applying step, inorganic particles, an inorganic binder, an organic binder and the like may be added to the fiber scattering inhibitor aqueous solution as needed.

Through the above steps, the mat material of the present invention can be produced.

(2) Method for Producing Mat Material of the Present Invention by Manufacturing Method (2-1) Mixture Solution Preparation Step First, a water-soluble polymer is dissolved in water to prepare an aqueous solution of a fiber scattering inhibitor.
Next, an inorganic fiber, an aqueous solution of a fiber scattering inhibitor, and water are mixed and stirred with a stirrer to prepare a mixed solution.
At this time, the weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) should be 3.0 wt% or less.
Further, if necessary, an inorganic binder, an inorganic binder dispersant, a coagulant and the like may be added to the mixed solution.

(2-2) Dehydration Step Next, after the mixed solution is poured into a molding machine having a mesh for filtration formed on the bottom surface, the water in the mixed solution is dehydrated through the mesh to prepare a raw material sheet. ..

(2-3) Heating and Pressurizing Step Next, the raw material sheet is heated and pressurized to prepare a mat material. Further, at the time of heating and pressurizing, a heat treatment may be performed in which hot air is aerated through the raw material sheet to dry the raw material sheet, or a wet state may be obtained without the heat treatment.
When heat treatment is performed, the heating temperature and hot air temperature are preferably 100 to 250 ° C. in order to prevent deterioration of the organic binder due to heat. In the range of 100 to 250 ° C., moisture can be removed from the mat material while suppressing deterioration of the organic binder. If the heating temperature or hot air temperature is less than 100 ° C., the temperature is not transmitted to the central portion of the mat material, and the drying time becomes long. On the other hand, if the temperature exceeds 250 ° C., the organic binder is deteriorated and the binding force between the fibers is reduced, so that the thickness of the mat material cannot be controlled.

The mat material of the present invention can be produced through the above steps.
In the above method, the fiber scattering inhibitor was added to the mixed solution in the mixed solution preparation step, but in the method for producing the mat material of the present invention, the fiber scattering inhibitor is suppressed in the "(2-1) mixed solution adjusting step". An aqueous solution of a fiber scattering inhibitor containing a water-soluble polymer is attached to the mat material after the "(2-3) heating and pressurizing step" without using an agent, and then dried to make the inorganic fibers of the mat material water-soluble. A sex polymer may be attached.

An exhaust gas purification device provided with the mat material of the present invention, which is an example of the method of using the mat material of the present invention, will be described.
The exhaust gas purification device provided with the mat material of the present invention is also the exhaust gas purification device of the present invention.
FIG. 2 is a cross-sectional view schematically showing an example of an exhaust gas purification device provided with the mat material of the present invention.

As shown in FIG. 2, the exhaust gas purification device 100 is arranged between the exhaust gas treatment body 40, the metal casing 50 accommodating the exhaust gas treatment body 40, and the exhaust gas treatment body 40 and the metal casing 50, and is arranged between the exhaust gas treatment body 40 and the metal casing 50. It is provided with a mat material 10 for holding the above.
Further, the mat material 10 is the mat material of the present invention.

Normally, the exhaust gas flows into the exhaust gas purification device 100 (in FIG. 2, the exhaust gas is indicated by a symbol "G" and the gas flow is indicated by an arrow), and the exhaust gas treatment body 40 and the mat material 10 are heated. become.

As described above, even if the mat material 10 is exposed to a high temperature, the water-soluble polymer adhering to the surface of the inorganic fiber is difficult to melt. Therefore, it is possible to prevent the inorganic fibers from slipping each other. As a result, it is possible to prevent the surface pressure of the mat material from decreasing.

Hereinafter, the exhaust gas treatment body and the metal casing constituting the exhaust gas purification device 100 will be described.

(Exhaust gas treatment body)
FIG. 3A is a perspective view schematically showing an example of an exhaust gas treatment body constituting the exhaust gas purification device of the present invention. FIG. 3B is a cross-sectional view taken along the line AA of FIG. 3A.
As shown in FIGS. 3A and 3B, the exhaust gas treatment body 40 included in the exhaust gas purification device 100 is a columnar one in which a large number of cells 41 are arranged side by side in the longitudinal direction across the cell wall 42.
Further, in the exhaust gas treatment body 40, one of the cells 41 is an exhaust gas filter (honeycomb filter) sealed with a sealing material 43.

As shown in FIG. 3B, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas treatment body 40 (in FIG. 3B, the exhaust gas is indicated by G and the flow of the exhaust gas is indicated by an arrow) is the exhaust gas inflow side end face of the exhaust gas treatment body 40. It flows into one cell 41 opened in the air and passes through the cell wall 42 separating the cells 41. At this time, PM in the exhaust gas is collected by the cell wall 42, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 41 opened on the exhaust gas outflow side end face and is discharged to the outside.

The exhaust gas treatment body 40 shown in FIGS. 3A and 3B is a filter in which one end of the cell 41 is sealed with a sealing material 43, but the exhaust gas constituting the exhaust gas purification device of the present invention. The processed body does not have to be sealed at the end of the cell. Such an exhaust gas treated body can be suitably used as a catalyst carrier.

The exhaust gas treatment body 40 may be made of a non-oxidized porous ceramic such as silicon carbide or silicon nitride, or may be made of an oxide porous ceramic such as alumina, cordierite, or mullite. Among these, silicon carbide is preferable.

The cell density in the cross section of the exhaust gas treatment body 40 is not particularly limited, but the preferable lower limit is 31.0 pcs / cm ² (200 pcs / inch ² ), and the preferable upper limit is 93.0 pcs / cm ² (600 pcs / inch / inch). inch ² ). The more preferable lower limit is 38.8 pieces / cm ² (250 pieces / inch ² ), and the more preferable upper limit is 77.5 pieces / cm ² (500 pieces / inch ² ).

The exhaust gas treatment body 40 may be supported with a catalyst for purifying the exhaust gas, and the catalyst to be supported is preferably a noble metal such as platinum, palladium, or rhodium, and among these, platinum 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, PM can be easily burned and removed, and toxic exhaust gas can be purified.

(Metal casing)
The metal casing 50 has a substantially cylindrical shape.
The inner diameter of the metal casing 50 (the inner diameter of the portion accommodating the exhaust gas treatment body) is preferably slightly shorter than the diameter of the exhaust gas treatment body 40 around which the mat material 10 is wound.

The metal casing 50 is not particularly limited, but is preferably made of stainless steel.

Next, an exhaust pipe with a matte material provided with the matte material of the present invention, which is an example of how to use the matte material of the present invention, will be described.
The exhaust pipe with a mat material provided with the mat material of the present invention is also the exhaust pipe with a mat material of the present invention.

FIG. 4 is a cross-sectional view schematically showing an example of an exhaust pipe with a matte material provided with the matte material of the present invention.
As shown in FIG. 4, the exhaust pipe 200 with a mat material includes an exhaust pipe 60, a mat material 10 arranged so as to cover the exhaust pipe 60, and a metal cover 70 arranged outside the mat material 10. ..

Normally, when the exhaust gas (in FIG. 4, the exhaust gas is indicated by the symbol “G” and the gas flow is indicated by the arrow) passes through the exhaust pipe 60, the exhaust pipe 60 becomes hot.
As described above, even if the mat material 10 is exposed to a high temperature, the water-soluble polymer adhering to the surface of the inorganic fiber is difficult to melt. Therefore, when the mat material is arranged around the exhaust pipe, the odor in the engine room is unlikely to become strong.

Next, an exhaust system including the mat material of the present invention, which is an example of the method of using the mat material of the present invention, will be described.
The exhaust system including the mat material of the present invention is also the exhaust system of the present invention.

FIG. 5 is a perspective view schematically showing another example of the exhaust system of the present invention.
FIG. 6 is a cross-sectional view schematically showing a part of the exhaust system of the present invention shown in FIG.

As shown in FIG. 5, in the exhaust system 300, an exhaust manifold 82 is attached to the side surface of the automobile engine 81. A part of the outer peripheral surface of the exhaust manifold 82 is covered with the heat insulator 83.
As shown in FIG. 6, the heat insulator 83 is partially fixed to the exhaust manifold 82 by bolts 84, but there is a space between the heat insulator 83 and the exhaust manifold 82.
The mat material 10 of the present invention is arranged on the inner peripheral side of the heat insulator 83, that is, on the exhaust manifold 82 side. In FIG. 6, the mat material 10 is also fixed by the bolt 84.

The exhaust manifold 82 has a function of collecting the exhaust gas from each cylinder and further sending the exhaust gas to the exhaust gas purification device. A part of the outer peripheral surface of the exhaust manifold 82 is covered with the heat insulator 83.

High-temperature exhaust gas flows through the exhaust manifold 82 in the exhaust system of an automobile, and it is preferable that the exhaust gas flows to the downstream exhaust gas treatment body while the temperature of the exhaust gas remains high because the catalytic efficiency in the exhaust gas treatment body is improved. Therefore, it is preferable to insulate the exhaust manifold 82.
The heat insulator 83 is a plate-shaped member made of metal or the like, and a part of the heat insulator 83 is fixed to the exhaust manifold 82 by bolts 84 or the like, but there is a space between the heat insulator 83 and the exhaust manifold 82.

The mat material 10 is arranged on the inner peripheral side of the heat insulator 83, that is, on the exhaust manifold 82 side.
The mat material 10 is preferably fixed to the inner peripheral surface of the heat insulator 83 by fixing means such as an adhesive, bolts and nuts, rivets, staples, caulking, stud pins, and eyelets.
Since the mat material 10 arranged on the inner peripheral side of the heat insulator 83 is not wound around the pipe, it is not necessary to form concave portions or convex portions, and the outer shape is matched to the shape of the inner peripheral surface of the heat insulator 83. It may have a processed shape.
Further, since the inner peripheral surface of the heat insulator 83 is usually not a simple flat surface, it is also possible to arrange the mat material 10 on the inner peripheral surface of the heat insulator 83 without a gap by combining a plurality of mat materials 10. preferable.

As described above, the mat material 10 can sufficiently suppress the scattering of inorganic fibers.
Therefore, it is possible to prevent the inorganic fibers from scattering from the mat material 10 at the time of manufacturing the exhaust system 300.
Further, the water-soluble polymer in the mat material 10 is hard to be melted by heat and is hard to be thermally decomposed.
Therefore, even if the exhaust gas flows into the exhaust system 300 and the mat material 10 is heated, the odor is unlikely to become strong.

(Example)
Hereinafter, examples in which the present invention is disclosed more specifically will be shown. The present invention is not limited to these examples.

(Example 1)
(1-1) Inorganic Fiber Precursor Preparation Step Silica sol so that the composition ratio of the inorganic fiber after firing is Al ₂ O ₃ : SiO ₂ = 72: 28 (weight ratio) with respect to the basic aluminum chloride aqueous solution. Was blended, and an appropriate amount of an organic polymer (polyvinyl alcohol) was added to prepare a mixed solution.
The obtained mixture was concentrated to prepare a mixture for spinning, and this mixture for spinning was spun by a blowing method (spinning atmosphere temperature: 120 ° C.) to prepare an alumina fiber precursor.
The average fiber diameter of the obtained alumina fiber precursor was 5.5 μm.

(1-2) Firing Step Subsequently, the alumina fiber precursor was compressed to prepare a continuous sheet having a width of 1254 mm and a thickness of 7.9 mm.
Needle punching was performed so that the density was 23 pieces / cm ^2.
Then, the sheet-like material was calcined at a maximum temperature of 1300 ° C. to convert the alumina fiber precursor into alumina fiber to obtain a sheet of an inorganic fiber aggregate.

(1-3) Step of Applying Fiber Scattering Inhibitor Next, a water-soluble sodium polycarboxylic acid that does not fluidize at 300 ° C. was dissolved in water to prepare an aqueous solution of the fiber scattering inhibitor.
An aqueous solution of a fiber scattering inhibitor was attached to the inorganic fiber aggregate so that the weight ratio of sodium polycarboxylic acid to the produced mat material (weight of sodium polycarboxylic acid / weight of mat material) was 1 wt%.
Then, the mat material according to Example 1 was produced by drying the inorganic fiber aggregate under the conditions of 110 ° C. for 1 hour.

(Comparative Example 1)
The mat material according to Comparative Example 1 was produced in the same manner as in Example 1 except that a water-insoluble acrylic resin that softens and fluidizes at 200 ° C. or lower was used instead of the water-soluble sodium polycarboxylic acid.
Since the acrylic resin is water-insoluble, it adheres to the inorganic fiber aggregate with the emulsion liquid dispersed in water.

(Comparative Example 2)
Instead of the fiber scattering inhibitor aqueous solution, an emulsion liquid in which water-insoluble silicone oil is dispersed in water is used, and the weight ratio of silicone oil to the mat material produced (weight of silicone oil / weight of mat material) is 1 wt. The mat material according to Comparative Example 2 was produced in the same manner as in Example 1 except that the ratio was set to%.

(Measurement of surface pressure)
The mat material according to Example 1 and Comparative Example 1 was cut into a size of 5 cm × 5 cm, and a hot surface pressure measuring device equipped with a heater was used in the portion of the plate for compressing the mat as a sample for surface pressure measurement. Each surface pressure measurement sample was placed at 25 ° C. and compressed to a ^{bulk density (GBD) of 0.21 g / cm 3.}
The surface pressure at that time was defined as the surface pressure at 25 ° C.
Next, the mixture was heated at a heating rate of 45 ° C./min, and the surface pressure at 100 ° C. and the surface pressure at 300 ° C. were measured.
In addition, the ratio of the surface pressure at 300 ° C. to the surface pressure at 100 ° C. (surface pressure maintenance rate) was calculated.
For the mat material according to Comparative Example 2, the surface pressure at 25 ° C. was measured in the same manner.
The results are shown in Table 1.

(Measurement of odor index)
The matte material according to Example 1 and Comparative Example 1 was cut into a size of 25 mm × 25 mm, placed on a hot plate heated to 500 ° C., and handy odor monitor OMX-SRM (manufactured by Shinei Technology Co., Ltd.), which is a semiconductor type odor sensor. ) Was placed above the mat by about 10 to 20 cm, and the odor index of the decomposed gas was measured.
The odor index of the mat material of each Example and Comparative Example was shown as a relative value with the odor index of the decomposed gas of Comparative Example 1 as 130.

As shown in Table 1, the mat material according to Example 1 had a high surface pressure at room temperature, and it was difficult for the surface pressure to decrease due to an increase in temperature.
Further, as shown in Table 2, the mat material according to Example 1 had a sufficiently low odor index.

10 Matte material 11 One end 11a Convex 12 The other end 12a Concave 20 Inorganic fiber 30 Water-soluble polymer 40 Exhaust gas treatment body 41 Cell 42 Cell wall 43 Encapsulant 50 Metal casing 60 Exhaust pipe 70 Metal cover 81 Automobile engine 82 Exhaust manifold 83 Heat insulator 84 Bolt 100 Exhaust gas purification device 200 Exhaust pipe with mat material 300 Exhaust system

Claims

A mat material made of inorganic fibers
The mat material contains a fiber scattering inhibitor containing a water-soluble polymer and contains.
The weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) is 3.0 wt% or less.
The water-soluble polymer is a mat material that is solid at room temperature and does not melt at 300 ° C.
The mat material according to claim 1, wherein the water-soluble polymer is a water-soluble polycarboxylic acid salt.
The mat material according to claim 1 or 2, wherein the water-soluble polymer is a water-soluble sodium polycarboxylic acid.
The odor index of the mat material measured by placing the mat material on a hot plate at 500 ° C. and measuring the odor of the decomposed gas generated by the odor sensor is a mat material to which 1.0% by weight of acrylic resin is adhered as a fiber scattering inhibitor. The mat material according to any one of claims 1 to 3, wherein the relative value of the odor index is 130 or less.
The mat material according to any one of claims 1 to 4, wherein the weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) is 0.01 to 3.0 wt%. ..
The mat material according to any one of claims 1 to 4, wherein the weight ratio of the water-soluble polymer to the mat material (weight of the water-soluble polymer / weight of the mat material) is 0.05 to 3.0 wt%. ..
Exhaust gas treatment body and
A metal casing that houses the exhaust gas treatment body and
An exhaust gas purification device that is arranged between the exhaust gas treatment body and the metal casing and includes a mat material that holds the exhaust gas treatment body.
The exhaust gas purification device, wherein the mat material is the mat material according to any one of claims 1 to 6.
Exhaust pipe and
A matte material arranged so as to cover the exhaust pipe and
An exhaust pipe with a mat material having a metal cover arranged on the outside of the mat material.
The exhaust pipe with a mat material, wherein the mat material is the mat material according to any one of claims 1 to 6.
The exhaust system according to any one of claims 1 to 6, wherein the mat material according to any one of claims 1 to 6 is arranged on the inner peripheral side of a heat insulator arranged outside an exhaust manifold in an automobile exhaust system.