JP2023048673A - Holding seal material, manufacturing method for holding seal material and exhaust gas purification device - Google Patents

Abstract

To provide a holding seal material having a high friction coefficient regardless of a service temperature.SOLUTION: In a holding seal material 1, a substrate 10 containing first inorganic fibers and a friction layer 20 containing second inorganic fibers having an average fiber length of 0.01 to 2.0 mm are laminated, where the friction layer 20 does not contain an organic binder. A manufacturing method for the holding seal material comprises: preparing the substrate 10 containing first inorganic fibers; preparing a paper-made mat containing second inorganic fibers and an organic binder, and heat-treating the paper-made mat to prepare the friction layer 20; and laminating the friction layer 20 on the substrate 10.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a holding seal material, a method for manufacturing the holding seal material, and an exhaust gas purification apparatus.

Exhaust gas emitted from internal combustion engines such as diesel engines contains particulate matter (hereinafter also referred to as PM), and in recent years, it has become a problem that this PM harms the environment and the human body. . Moreover, since the exhaust gas 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 purifying device for capturing PM in exhaust gas and purifying harmful gas components, an exhaust gas treating body made of porous ceramic such as silicon carbide or cordierite, and a casing accommodating the exhaust gas treating body are provided. and a holding sealing material (mat material) disposed between an exhaust gas treating body and a casing. This holding sealing material prevents the exhaust gas treating body from coming into contact with the casing covering its outer periphery and being damaged due to vibrations and impacts caused by the running of the vehicle, etc. It is arranged mainly for the purpose of preventing leakage.

It is conceivable to increase the coefficient of friction in order to increase the holding power of the holding sealing material. As a technique for increasing the coefficient of friction, Patent Document 1 discloses a method in which an inorganic binder is attached to inorganic fibers to increase the frictional force between the casing and the casing. An improved needle mat is disclosed.

Further, in Patent Document 2, grooves are formed with a mold on the surface of a raw material sheet (papermaking mat) made of an organic binder and inorganic fibers, and the obtained holding sealing material is wrapped around a casing, and then heated to dissolve the organic binder. is decomposed and the groove disappears, thereby improving the friction coefficient of the holding sealing material.

Further, Patent Document 3 discloses a holding sealing material in which a papermaking mat containing inorganic fibers, an inorganic binder, and an organic binder is laminated on a needle mat made of inorganic fibers and a binder.

JP 2013-213463 A JP-A-2017-31870 JP 2009-275638 A

However, the needle mat disclosed in Patent Document 1 generally has a lower coefficient of friction than the paper-made mat, and has a problem of insufficient holding power. Moreover, the paper-made mats disclosed in Patent Documents 2 and 3 contain an organic binder, and there is a problem that the coefficient of friction is lowered when used at a temperature at which the organic binder decomposes.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a holding sealing material having a high coefficient of friction regardless of the operating temperature.

As a result of intensive studies, the inventors found that the friction coefficient of the holding sealing material is affected by the fiber length of the inorganic fibers. In a general elastic body, the holding force is expressed as the product of the surface pressure and the coefficient of friction. If misalignment occurs, the holding force will decrease. Needle mats generally have a lower coefficient of friction than paper-made mats. This is because, as the fiber length of the inorganic fibers increases, the distance from the point of contact between the inorganic fibers at the friction-generating interface to the fulcrum (inter-fiber intersection) that supports the inorganic fibers increases, so that the inorganic fibers tend to be displaced.
The present inventors have found that the surface of the holding sealing material is heated regardless of the operating temperature due to a laminated structure in which a layer that is composed of inorganic fibers having a relatively short average fiber length and does not contain an organic binder is arranged on the surface of the holding sealing material. It was found to have a coefficient of friction.
That is, the holding sealing material according to the first embodiment of the present invention includes a base material containing first inorganic fibers and a friction layer containing second inorganic fibers having an average fiber length of 0.01 to 2.0 mm. and the friction layer does not contain an organic binder.
Since the holding sealing material according to the first embodiment of the present invention has the above structure, the friction layer has a high coefficient of friction and a high holding power.

A holding sealing material according to a second embodiment of the present invention is obtained by laminating a base material containing a first inorganic fiber and a friction layer containing a second inorganic fiber, and the friction layer at room temperature and 500° C. When the coefficients of friction are connected by a straight line, the value of the coefficient of friction of the friction layer exceeds the straight line in the temperature range above room temperature and below 500°C.
In the holding sealing material according to the second embodiment of the present invention, since the coefficient of friction of the friction layer is high in the temperature range from room temperature to 500° C., high holding power can be exhibited even during use at the above temperature.

In the holding sealing material of the present invention, the second inorganic fibers preferably have an average fiber length of 0.2 to 2.0 mm.
When the average fiber length of the second inorganic fibers is within the above range, the coefficient of friction of the friction layer can be further increased.

In the holding sealing material of the present invention, the first inorganic fibers preferably have an average fiber length of 0.01 to 100 mm.
The holding sealing material of the present invention is preferably obtained by subjecting the base material to needling treatment.
In the holding sealing material of the present invention, the substrate preferably contains an organic binder.
In the holding sealing material of the present invention, it is preferable that the above-mentioned friction layer is subjected to a papermaking process.

In the holding sealing material of the present invention, the friction layer is preferably laminated on both sides of the base material.
When the friction layers are laminated on both sides of the base material, the holding force of the holding sealing material can be further enhanced.

The method for producing a holding sealing material of the present invention comprises steps of producing a substrate containing a first inorganic fiber, producing a paper-made mat containing a second inorganic fiber and an organic binder, and heat-treating the paper-made mat. A step of forming a friction layer and a step of laminating the friction layer on the base material are included.
Since the organic binder is decomposed by heat-treating the papermaking mat, a holding sealing material having a friction layer containing no organic binder can be produced.

The exhaust gas purifying apparatus of the present invention comprises an exhaust gas treating body, a metal casing that houses the exhaust gas treating body, and a holding sealing material that is disposed between the exhaust gas treating body and the metal casing and holds the exhaust gas treating body. , wherein the holding sealing material is the holding sealing material of the present invention.
Since the holding sealing material of the present invention is arranged between the exhaust gas treating body and the metal casing, the exhaust gas purifying apparatus of the present invention can stably hold the exhaust gas treating body.

In the exhaust gas purifier of the present invention, it is preferable that the holding sealing material is arranged so that the friction layer faces the metal casing side.
Since the friction layer faces the metal casing, the exhaust gas treating body can be held more stably.

FIG. 1 is a perspective view schematically showing an example of the holding sealing material of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas purifier of the present invention. FIG. 3 is a schematic diagram showing a device for measuring the coefficient of friction of the holding sealing material. FIG. 4 is a schematic diagram showing a device for measuring the coefficient of friction of the holding sealing material. 5 is a graph showing measurement results of the friction coefficient of the holding sealing material of Example 1. FIG. 6 is a graph showing measurement results of the friction coefficient of the holding sealing material of Example 2. FIG. 7 is a graph showing measurement results of the friction coefficient of the holding sealing material of Example 3. FIG. 8 is a graph showing measurement results of the friction coefficient of the holding sealing material of Example 4. FIG. 9 is a graph showing measurement results of the friction coefficient of the holding sealing material of Comparative Example 1. FIG. 10 is a graph showing measurement results of the friction coefficient of the holding sealing material of Comparative Example 2. FIG. 11 is a graph showing the coefficient of friction of the holding sealing material of Example 1 and the coefficient of friction of the holding sealing material of Example 5. FIG. FIG. 12 is a graph showing the correlation between the average fiber length of inorganic fibers forming the friction layer of the holding sealing material and the coefficient of friction.

First, the holding sealing material of the present invention will be described in detail.
A holding sealing material according to a first embodiment of the present invention includes a base material containing first inorganic fibers and a friction layer containing second inorganic fibers having an average fiber length of 0.01 to 2.0 mm. The friction layer is laminated and characterized in that the friction layer does not contain an organic binder.

The first inorganic fiber contained in the base material is not particularly limited, and inorganic fibers commonly used in holding sealing materials can be used, such as alumina fiber, alumina-silica fiber, silica fiber, and biosoluble fiber. , glass wool, rock wool, and the like. These inorganic fibers have high heat resistance, and substrates formed from such inorganic fibers are less likely to change shape due to temperature changes. Among these, alumina-silica fibers are preferred.

Furthermore, when the first inorganic fibers are alumina-silica fibers, the composition ratio of alumina and silica is alumina (Al ₂ O ₃ ):silica (SiO ₂ ) = 60:40 to 80:20 by weight. More preferably, alumina (Al ₂ O ₃ ):silica (SiO ₂ )=70:30 to 74:26.

The base material may be either needling-processed or paper-making-processed, but needling-processed is preferred. The needling treatment means inserting and removing a fiber entangling means such as a needle with respect to a mat containing inorganic fibers.

The average fiber length of the first inorganic fibers is preferably 0.01 to 100 mm. In particular, when the substrate is subjected to needling treatment, the first inorganic fibers need to have a certain length in order to exhibit an entangled structure, and the more preferable average fiber length of the first inorganic fibers is 3.5. 0 to 100 mm. On the other hand, when the base material is paper-processed, the average fiber length of the first inorganic fibers is more preferably 0.01 to 5.0 mm.
Also, the average fiber diameter (diameter) of the first inorganic fibers is preferably 2 to 10 μm.

The average fiber length and average fiber diameter of the first inorganic fiber and the second inorganic fiber described later are obtained by observing 100 arbitrary inorganic fibers in the field of view in SEM (scanning electron microscope) observation of the holding sealing material. demand.

The base material may contain an organic binder. The organic binder allows the first inorganic fibers forming the base material to adhere to each other.
As the organic binder, an emulsion obtained by dispersing acrylic latex or rubber latex in water can be used.

The content of the organic binder in the substrate is preferably 0.11 to 30% by weight with respect to 100% by weight of the first inorganic fibers.

The substrate may contain an inorganic binder. Examples of inorganic binders that can be used include alumina sol, silica sol, and colloidal dispersions thereof. These colloidal dispersions may have too high a concentration in the undiluted solutions available on the market. It is preferable to use

The content of the inorganic binder in the substrate is preferably 0.11 to 30% by weight with respect to 100% by weight of the first inorganic fibers.

The friction layer of the holding sealing material according to the first embodiment of the present invention contains second inorganic fibers having an average fiber length of 0.01 to 2.0 mm. When the average fiber length of the second inorganic fibers is within the above range, the friction layer has a high coefficient of friction and the holding sealing material has a high holding power. The average fiber length of the second inorganic fibers is more preferably 0.2 to 2.0 mm. Moreover, the preferred range of the average fiber diameter (diameter) of the second inorganic fibers is the same as that of the first inorganic fibers.

The material of the second inorganic fibers contained in the friction layer is not particularly limited, and examples thereof include the inorganic fibers exemplified as the first inorganic fibers.

The friction layer is preferably made by papermaking. With the papermaking process, even inorganic fibers having a relatively short average fiber length as described above can be molded into a mat.

The friction layer of the holding sealing material according to the first embodiment of the present invention is characterized by not containing an organic binder. If the friction layer contains an organic binder, there is a problem that the coefficient of friction of the friction layer decreases when the holding sealing material is used in the decomposition temperature range of the organic binder. The holding sealing material according to the first embodiment of the present invention has a high coefficient of friction regardless of the operating temperature because the friction layer does not contain an organic binder.

A holding sealing material according to a first embodiment of the present invention has a structure in which a base material and a friction layer are laminated. The friction layer may be laminated on only one side of the substrate, or may be laminated on both sides of the substrate. Since the holding sealing material according to the first embodiment of the present invention has high holding power, it is preferable that friction layers are laminated on both sides of the base material.

In the holding sealing material according to the first embodiment of the present invention, the base material and the friction layer may be laminated, and the base material and the friction layer may be bonded together.

A holding sealing material according to a second embodiment of the present invention is obtained by laminating a base material containing a first inorganic fiber and a friction layer containing a second inorganic fiber, and the friction layer at room temperature and 500° C. When the coefficients of friction are connected by a straight line, the value of the coefficient of friction of the friction layer exceeds the straight line in the temperature range above room temperature and below 500°C. In the holding sealing material according to the second embodiment of the present invention, since the coefficient of friction of the friction layer is high in the temperature range from room temperature to 500° C., high holding power can be exhibited even during use at the above temperature.

The friction layer of the holding sealing material according to the second embodiment has a coefficient of friction that satisfies the following general formula.
μ≧(μ ₅₀₀ −μ _R )/(500−t _R )×(tt _R )+μ _R
μ: coefficient of friction of the friction layer at any temperature from room temperature to 500° C. μ ₅₀₀ : coefficient of friction at 500° C. μ _R : coefficient of friction at room temperature t _R : room temperature t: any temperature above room temperature and below 500° C. In this specification, room temperature is, for example, 25°C.

The holding sealing material according to the second embodiment of the present invention may have the features of the holding sealing material according to the first embodiment.

FIG. 1 is a perspective view schematically showing an example of a holding sealing material according to a first embodiment of the invention and an example of a holding sealing material according to a second embodiment of the invention. Hereinafter, the holding seal material according to the first embodiment of the present invention and the holding seal material according to the second embodiment of the present invention are also referred to as "the holding seal material of the present invention" or "the holding seal material".
The holding sealing material 1 shown in FIG. 1 is rectangular in plan view. The shape of the holding sealing material 1 in a plan view is not limited to a rectangle, and may be other shapes according to the place of use.
One end 2 of the holding sealing material 1 is provided with a protrusion 2a, and the other end 3 is provided so that the ends fit together when the holding sealing material 1 is wrapped around an object. is provided with a recess 3a. When such convex portions 2a and concave portions 3a are provided, the sealing performance is improved when the holding sealing material 1 is arranged in an exhaust gas purifying device to be described later.
It should be noted that the holding sealing material of the present invention does not have to have projections and recesses at the ends. Further, the holding sealing material of the present invention may have an L-shaped end portion so that the end portions are fitted together when wound around an object.

As shown in FIG. 1 , the holding sealing material 1 has a base material 10 and a friction layer 20 provided on the base material 10 . The base material 10 is a rectangular mat in plan view made of first inorganic fibers. The friction layer 20 is a rectangular mat made of second inorganic fibers. The base material 10 and the friction layer 20 have protrusions and recesses at their ends, similar to the holding sealing material 1 .

Next, a method for manufacturing the holding sealing material of the present invention will be described.
The method for producing a holding sealing material of the present invention comprises steps of producing a substrate containing a first inorganic fiber, producing a paper-made mat containing a second inorganic fiber and an organic binder, and heat-treating the paper-made mat. A step of forming a friction layer and a step of laminating the friction layer on the base material are included.

(Step of preparing base material)
The base material of the holding sealing material of the present invention can be obtained by various methods, and for example, it can be produced by a papermaking method or a needling method.
In the case of the papermaking method, for example, it can be produced by the following method.
Inorganic fibers are opened, and the opened inorganic fibers are dispersed in a solvent to form a mixed solution. An inorganic fiber assembly is obtained by pouring the mixed liquid into a molding device having a mesh for filtration formed on the bottom surface and removing the solvent in the mixed liquid. Then, by drying the inorganic fiber aggregate, a substrate containing the first inorganic fibers can be obtained.

In the case of the needling method, for example, it can be produced by the following method.
A spinning mixture made from a basic aqueous solution of aluminum chloride and silica sol or the like is spun by a blowing method to produce an inorganic fiber precursor. Subsequently, the inorganic fiber precursor is compressed to produce a continuous sheet-like material having a predetermined size, and is subjected to a sintering treatment. Needling treatment may be performed either before or after this firing treatment to entangle the inorganic fibers, thereby obtaining a base material containing the first inorganic fibers.

After the needling treatment, an inorganic binder or an organic binder is applied to the substrate, if necessary.
The method of applying the inorganic binder to the substrate is not particularly limited. Examples thereof include a method of impregnating a base material with an inorganic binder by a curtain coating method or the like, and a spray coating method of spraying an inorganic binder onto a base material. Other methods include a roll coating method, a film transfer method and a dip coating method.
The method and procedure for applying the organic binder to the substrate are not particularly limited, but examples include a method of spraying a liquid containing an organic binder onto the substrate.
After that, a drying step may be performed to dry the water contained in the inorganic binder and the organic binder.

(Step of producing friction layer)
The friction layer constituting the holding sealing material of the present invention is produced by producing a paper-made mat containing the second inorganic fibers and an organic binder, and heat-treating the paper-made mat.
The papermaking mat can be produced, for example, by the papermaking method described above in the step of producing the base material. At this time, the organic binder is included in the papermaking mat by adding the organic binder to the mixed liquid.
The resulting paper-processed mat is heat-treated, for example, at 100 to 800° C. for 0.5 to 10 hours. The heat treatment decomposes and disappears the organic binder contained in the paper-made mat to obtain the friction layer.

The manufacturing conditions are adjusted so that the second inorganic fibers contained in the friction layer obtained in this step have an average fiber length of 0.01 to 2.0 mm.

(Step of laminating friction layer on base material)
The holding sealing material of the present invention is obtained by laminating the friction layer on the base material. In order to laminate the friction layer on the base material, a double-sided tape may be applied on the base material and an adhesive layer may be provided. Further, spray paste or the like may be spread over the adhesive layer. The friction layer may be laminated on one side of the substrate, or may be laminated on both sides.

Through the steps described above, the holding sealing material of the present invention is obtained.

In the above manufacturing method, the base material and the friction layer are prepared separately and then the friction layer is laminated on the base material. The holding sealing material of the present invention can also be produced by a method in which the sheet-made mats containing the binder are laminated and then heat-treated to decompose the organic binder.

The exhaust gas purifier of the present invention will be described below.
The exhaust gas purifying apparatus of the present invention comprises an exhaust gas treating body, a metal casing that houses the exhaust gas treating body, and a holding sealing material that is disposed between the exhaust gas treating body and the metal casing and holds the exhaust gas treating body. , wherein the holding sealing material is the holding sealing material of the present invention.

FIG. 2 is a cross-sectional view schematically showing an example of the exhaust gas purifier of the present invention.
As shown in FIG. 2, the exhaust gas purifying apparatus 100 of the present invention includes a metal casing 50, an exhaust gas treating body 40 housed in the metal casing 50, and a holding member disposed between the exhaust gas treating body 40 and the metal casing 50. A sealing material 1 is provided.

The exhaust gas treating body 40 has a columnar shape in which a large number of cells 41 are arranged side by side in the longitudinal direction with cell walls 42 interposed therebetween. One end of the cell is sealed with a sealing material 43 .
An introduction pipe for introducing exhaust gas discharged from the internal combustion engine and an exhaust pipe for discharging the exhaust gas that has passed through the exhaust gas purifying device are connected to the ends of the metal casing 50 as necessary. It will happen.

A case where exhaust gas passes through the exhaust gas purifier 100 having the above configuration will be described below with reference to FIG.
As shown in FIG. 2, the exhaust gas discharged from the internal combustion engine and flowing into the exhaust gas purifying device 100 (in FIG. The exhaust gas flows into one cell 41 opened at the exhaust gas inflow side end face of the , and passes through the cell wall 42 separating the cells 41 . At this time, the PM in the exhaust gas is captured by the cell walls 42, and the exhaust gas is purified. The purified exhaust gas flows out from another cell 41 that is open on the end surface on the exhaust gas outflow side and is discharged to the outside.

In the exhaust gas purifying apparatus 100 shown in FIG. 2, the holding sealing material 1 is the holding sealing material of the present invention, and the surface of the holding sealing material 1 on the side of the base material 10 is arranged on the side of the exhaust gas treating body 40, and the friction layer The surface on the 20 side is arranged on the metal casing 50 side.

It is preferable that the holding sealing material is arranged so that the friction layer faces the metal casing. In general, comparing the state of the surface of the metal casing with that of the surface of the exhaust gas treating body, the surface of the metal casing is smoother and slippery. Therefore, there is a strong need to improve the coefficient of friction between the holding seal material and the metal casing. If the surface of the holding seal material provided with the friction layer is provided on the metal casing side, the effect of increasing the coefficient of friction between the holding seal material and the metal casing can be favorably exhibited. More preferably, the friction layer of the holding sealing material is arranged so as to face both the metal casing side and the exhaust gas treating body side.

The material of the metal casing that constitutes the exhaust gas purifier of the present invention is not particularly limited as long as it is a heat-resistant metal, and specific examples include metals such as stainless steel, aluminum, and iron.

In addition, the shape of the casing may preferably be a substantially cylindrical shape, a clamshell shape, a substantially elliptical shape in cross section, a substantially polygonal shape, or the like.

The exhaust gas treating body 40 shown in FIG. 2 is a filter in which one end of the cell 41 is sealed with a sealing material 43, but the exhaust gas treating body constituting the exhaust gas purifying apparatus of the present invention is , the ends of the cell may not be sealed. Such an exhaust gas treating body can be suitably used as a catalyst carrier.

The exhaust gas treating body 40 may be made of a non-oxide 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 preferred.

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

The exhaust gas treating body 40 may carry a catalyst for purifying the exhaust gas, and the catalyst to be carried is preferably a noble metal such as platinum, palladium, rhodium, etc. Among them, platinum is more preferable. As other catalysts, for example, alkali metals such as potassium and sodium, and alkaline earth metals such as barium can also be used. These catalysts may be used alone or in combination of two or more.
When these catalysts are carried, it becomes easier to burn and remove PM, and it becomes possible to purify toxic exhaust gas.

Since the holding sealing material of the present invention has high holding power, it is possible to reduce the size and weight of the holding sealing material as compared with conventional holding sealing materials when used in an exhaust gas purifier. By reducing the size and weight of the holding seal material, it is possible to reduce the weight of the entire exhaust gas purifier, which leads to a reduction in transportation costs and the like.

Examples that more specifically disclose the present invention are shown below. In addition, the present invention is not limited only to these examples.

Example 1
(Preparation of base material)
As a base mat of inorganic fibers having an alumina-silica composition, a base mat having a composition ratio of Al ₂ O ₃ :SiO ₂ =72:28 was prepared. By subjecting this base mat to a needling treatment, a needle mat having a bulk density of 0.15 g/cm ³ and an inorganic fiber weight per unit area of 1050 g/m ² was produced. Next, the needle mat was cut into a size of 930×515 mm in plan view, and used as a base material for the holding sealing material. The average fiber length of the inorganic fibers (first inorganic fibers) forming the substrate was 60 mm.

(Preparation of friction layer)
First, a slurry for papermaking was prepared by the following procedure.
A raw material fiber composed of alumina fibers having a composition ratio of Al ₂ O ₃ :SiO ₂ =72:28 was prepared, and 2 kg of this raw material fiber was spread by a feather mill for 10 minutes. By this opening, friction layer inorganic fibers (second inorganic fibers) having an average fiber length of 0.95 mm were obtained.

Next, 790 g of friction layer inorganic fibers were added to 79000 g of water, and the mixture was stirred with a stirrer for 5 minutes to prepare a mixture.

Latex as an organic binder was added to the above mixture so as to be 24% by weight of the inorganic fibers for the friction layer, and the mixture was stirred for 1 minute. Further, 3.95 g of Percoll 292 (manufactured by BASF) was added to the mixture as a flocculating agent, and the mixture was stirred for 1 minute to prepare a slurry for papermaking.

Next, a papermaking mat was produced using the papermaking slurry.
A filtering mesh (30 mesh) was placed at the bottom of a papermaking molding machine (length 930 mm, width 515 mm, depth 400 mm).

Next, the slurry for papermaking was charged from above the molding machine for papermaking. Thereafter, the charged slurry for papermaking was held for 20 seconds without performing any operation.

After holding the slurry for papermaking, a dehydration treatment was performed to form a papermaking mat. The dehydration treatment was carried out by applying suction pressure from the bottom side of the papermaking molding machine using a suction pump to forcibly suck water in the papermaking slurry through the filtration mesh.

The paper-processed mat was taken out from the paper-process molding machine, dried at 135° C. for 60 minutes, and then heated at 600° C. for 1 hour to decompose the organic binder contained in the paper-processed mat and form a friction layer. The obtained friction layer was placed on the base material to produce a holding sealing material in which the base material and the friction layer were laminated. The friction layer was laminated only on one side of the substrate. The basis weight of the friction layer was 1650 g/m ² .

Example 2
A holding sealing material was produced in the same manner as in Example 1, except that the average fiber length of the inorganic fibers for the friction layer was 0.05 mm.

Example 3
A holding sealing material was produced in the same manner as in Example 1, except that the average fiber length of the inorganic fibers for the friction layer was 0.21 mm.

Example 4
A holding sealing material was produced in the same manner as in Example 1, except that the average fiber length of the inorganic fibers for the friction layer was 0.65 mm.

Example 5
First, a needle mat was produced in the same manner as in Example 1. Next, alumina sol (Nissan Chemical Industries, Ltd. alumina sol solution AS550 (solid concentration: 15% by weight, particle diameter 0.04 μm)) is diluted with water to a solid concentration of 1.0% by weight, containing inorganic particles. An inorganic binder was prepared. This inorganic binder was brought into contact with a needle mat cut by a curtain coating method, and the cut needle mat was impregnated with the inorganic binder.

The needle mat to which the inorganic binder had adhered was dehydrated by suction using a dehydrator, so that 100 wt % of the inorganic binder adhered to 100 wt % of the inorganic fibers of the needle mat was adjusted. Since the solid content concentration of the inorganic particles in the inorganic binder is 1.0% by weight, the adhesion amount of the inorganic particles per unit weight of the inorganic fiber is 1.0% by weight in terms of solid content. Thus, a needle mat with an inorganic binder was produced.

The organic binder was applied as follows. First, an acrylic latex emulsion in which acrylic latex is dispersed in water was prepared and used as an organic binder. An organic binder was uniformly sprayed onto the needle mat to which the inorganic binder was adhered so that the amount of inorganic fibers in the needle mat to which the inorganic binder was adhered was 1.0% by weight. Thereafter, the needle mat to which the inorganic binder and the organic binder were adhered was air-dried at a temperature of 140° C. for 5 minutes under a pressure of 70 kPa. Thus, a substrate containing an inorganic binder and an organic binder was obtained.

A friction layer was produced in the same manner as in Example 1. The friction layer was placed on the base material obtained above to produce a holding sealing material in which the base material and the friction layer were laminated. The friction layer was laminated only on one side of the substrate.

Comparative example 1
A holding sealing material of Comparative Example 1 was obtained without laminating the friction layer on the base material containing the inorganic binder and the organic binder prepared in Example 5.

Comparative example 2
The amount of latex in the slurry for papermaking was adjusted so that the content of the organic binder in the papermaking mat after drying was 7.5% by weight, and the organic binder was not thermally decomposed. A sheet-processed mat was prepared in the same manner as the friction layer, and used as a holding sealing material of Comparative Example 2.

Table 1 shows the configurations of the holding sealing materials produced in Examples 1-5 and Comparative Examples 1-2.

(Measurement of friction coefficient)
The friction coefficients of the holding sealing materials of Examples 1 to 5 and Comparative Examples 1 and 2 were measured by the following method.
3 and 4 are schematic diagrams showing a friction coefficient measuring device for a holding sealing material.
In the friction coefficient measuring device 200, stainless steel flat plates (left plate 210 and right plate 220) are arranged on the left and right sides of the device so as to face each other. In addition, the left plate 210 is a load cell, and can measure the load applied to the right side of the left plate 210 (the side in contact with the mat material).

First, the left plate 210, the holding seal material 1a, the stainless steel flat plate (middle plate 230), the holding seal material 1b, and the right plate 220 are arranged in this order. was placed.
Projections are provided on the surfaces of the left plate 210 and the right plate 220 to prevent slipping between the left plate 210 and the holding seal material 1a and between the right plate 220 and the holding seal material 1b (between the plate and the holding seal material). A member 240 was provided.
The friction layer 20 side surfaces of the holding sealing materials 1a and 1b were arranged on the intermediate plate 230 side.
The holding seal material 1 a is sandwiched between the left plate 210 and the middle plate 230 , and the holding seal material 1 b is sandwiched between the middle plate 230 and the right plate 220 .
In addition, the intermediate plate 230 is a load cell and can measure the load applied to the intermediate plate.

First, pressure was applied to the left plate 210 and the right plate 220 in the direction of the middle plate 230 to compress the holding sealing material until the bulk density (GBD) thereof reached 0.3 g/cm ³ .
The compressed state was held (relaxed) for 10 minutes.

Next, while the temperature between the holding sealing materials 1a and 1b and the intermediate plate 230 is 25° C., the intermediate plate 230 is moved in the direction indicated by the arrow in FIG. A shear stress was applied to the friction layer of the sealing material.
FIG. 4 shows a state in which the middle plate 230 has been moved.
The load value of the load cell of the intermediate plate during movement and the static frictional force applied to the intermediate plate were measured, and the coefficient of friction (static friction coefficient) when the static frictional force reached its maximum was measured.

Next, the temperature between the mat material and the intermediate plate was changed to 100° C., 200° C., 300° C., 400° C., and 500° C. At each temperature, shear stress was applied to the friction layer of the holding sealing material in the same manner as described above, The coefficient (static friction coefficient) was measured. The results are shown in Figures 5-12.

5 to 10 are graphs showing the measurement results of the friction coefficients of the friction layers of the holding sealing materials of Examples 1 to 4 and Comparative Examples 1 and 2. FIG. In the holding seal materials of Examples 1 to 4, when the coefficient of friction of the friction layer at 25°C and the coefficient of friction of the friction layer at 500°C are connected by a straight line, the value of the coefficient of friction exceeds 25°C and is less than 500°C. It exceeded the straight line in the temperature range. On the other hand, in the holding sealing materials of Comparative Examples 1 and 2, there was a range in which the values of the friction coefficients of the friction layers fell below the straight line.

11 is a graph showing the coefficient of friction of the holding sealing material of Example 1 and the coefficient of friction of the holding sealing material of Example 5. FIG.
The holding sealing material of Example 5 has the same structure as that of Example 1 except that the base material contains an organic binder and an inorganic binder. and Example 5 had substantially the same values. Therefore, it was found that the friction coefficient of the friction layer is hardly affected even if the base material contains an organic binder and an inorganic binder.

FIG. 12 is a graph showing the correlation between the average fiber length of inorganic fibers forming the friction layer of the holding sealing material and the coefficient of friction. The friction coefficients of the friction layers at 300° C. and 500° C. were compared for Examples 1 to 4 and Comparative Example 1. The horizontal axis represents the average fiber length of the inorganic fibers, and the vertical axis represents the coefficient of friction. Approximate curves were obtained by polynomial approximation.

As shown in FIG. 12, it was found that the friction coefficient varies depending on the fiber length of the inorganic fibers. Also, from the approximation curve obtained from the data, it was found that the preferred average fiber length of the inorganic fibers in the friction layer is 0.2 to 2.0 mm.

1, 1a, 1b holding sealing material 2 one end 2a projection 3 other end 3a recess 10 base material 20 friction layer 40 exhaust gas treating body 41 cell 42 cell wall 43 sealing material 50 metal casing 100 exhaust gas purification device 200 Friction coefficient measuring device 210 Left plate 220 Right plate 230 Middle plate 240 Protruding member G Exhaust gas

Claims (11)

a substrate comprising a first inorganic fiber;
A friction layer containing a second inorganic fiber having an average fiber length of 0.01 to 2.0 mm is laminated,
A holding sealing material, wherein the friction layer does not contain an organic binder. a substrate comprising a first inorganic fiber;
A friction layer containing a second inorganic fiber is laminated,
A holding sealing material, wherein when a straight line connects the coefficient of friction of the friction layer at room temperature and 500°C, the value of the coefficient of friction of the friction layer exceeds the straight line in a temperature range above room temperature and below 500°C. 3. The holding sealing material according to claim 1, wherein the second inorganic fibers have an average fiber length of 0.2 to 2.0 mm. The holding sealing material according to any one of claims 1 to 3, wherein the first inorganic fibers have an average fiber length of 0.01 to 100 mm. The holding sealing material according to any one of claims 1 to 4, wherein the base material is subjected to needling treatment. The holding sealing material according to any one of claims 1 to 5, wherein the base material contains an organic binder. The holding sealing material according to any one of claims 1 to 6, wherein the friction layer is made by papermaking. The holding sealing material according to any one of claims 1 to 7, wherein the friction layer is laminated on both sides of the base material. creating a substrate comprising first inorganic fibers;
a step of preparing a paper-made mat containing second inorganic fibers and an organic binder, and heat-treating the paper-made mat to prepare a friction layer;
and laminating the friction layer on the base material. an exhaust gas treating body;
a metal casing housing the exhaust gas treating body;
An exhaust gas purifying apparatus comprising a holding sealing material arranged between the exhaust gas treating body and the metal casing and holding the exhaust gas treating body,
An exhaust gas purifier, wherein the holding sealing material is the holding sealing material according to any one of claims 1 to 8. 11. The exhaust gas purifying device according to claim 10, wherein said holding sealing material is arranged so as to face said friction layer on said metal casing side.

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