JP4382414B2 - Holding sealing material and exhaust gas purification device - Google Patents

Description

The present invention relates to a catalytic converter for purifying exhaust gas discharged from an internal combustion engine such as an automobile engine, an exhaust gas purification device such as a diesel particulate filter (DPF), and a holding seal used in the exhaust gas purification device. Regarding materials.

Conventionally, as an exhaust gas purification apparatus, a porous ceramic columnar body having a honeycomb structure in which a large number of through-holes are arranged in the longitudinal direction, a cylindrical metal shell covering the outer periphery of the porous ceramic columnar body, What is comprised from the mat-shaped holding | maintenance sealing material arrange | positioned between is known. In such an exhaust gas purification device, the exhaust gas can be purified by passing through the porous ceramic columnar body.

Such an exhaust gas purification device functions as a catalytic converter by coating a porous ceramic columnar body with a catalyst, and can oxidize and reduce harmful substances in the exhaust gas by a catalyst.
As the catalyst, a three-way catalyst based on alumina and containing platinum, palladium and rhodium is mainly used. Rhodium has a high ability to reduce nitrogen oxides (NOx), and platinum and palladium are hydrocarbons (HC). And the oxidation ability of carbon monoxide (CO) is high. Since the exhaust gas composition of the gasoline engine balances HC, CO, and NOx, the oxidation reaction of HC and CO and the reduction reaction of NOx can be performed simultaneously.

Further, the exhaust gas purifying device functions as a diesel particulate filter (hereinafter also referred to as DPF) by sealing through-holes arranged in parallel in the longitudinal direction of the porous ceramic columnar body with either one end face. In addition, particulates such as graphite in the exhaust gas can be collected and removed in the porous ceramic columnar body.

In these exhaust gas purifying devices, in order to prevent the porous ceramic body from being damaged by contact with the metal shell covering the outer periphery due to vibration or impact caused by running of the automobile, etc., and with the porous ceramic body A holding sealing material is interposed between the metal shells for the purpose of preventing exhaust gas from leaking from between the metal shells.

At present, as the holding sealing material, a heat-expandable holding sealing material which is a mixture of vermiculite, ceramic fiber or the like is mainly used. However, in recent years, the exhaust gas temperature has risen remarkably due to stricter regulations on exhaust gas, so that the heat resistance of conventional heat-expandable holding sealing materials has become insufficient, and the non-expanded form in which inorganic fibers are molded into a mat shape. A property holding sealing material is being used.

However, in the initial stage of use of the exhaust gas purifying device, the non-expandable holding sealing material made of a mat-like molded body of inorganic fibers has a low frictional resistance with the metal shell, and the porous ceramic body is firmly placed in the metal shell. In some cases, the porous ceramic body may be displaced. Normally, the frictional resistance between the holding seal material and the metal shell becomes higher as the exhaust gas purification device is used and the metal shell is exposed to a high temperature, and therefore the lowest in the initial use stage of the exhaust gas purification device. .
Also, the non-intumescent holding sealing material made of a mat-like molded body of inorganic fibers tends to be bulky, so that the assemblability when wound around a porous ceramic body and installed in a metal shell is poor, or the inorganic fibers There was a problem that was scattered and sucked into the respiratory system.

On the other hand, conventionally, a method of impregnating and applying an acrylic organic binder to a mat-like molded body of inorganic fibers has been used (see, for example, Patent Document 1). According to this method, the friction resistance between the non-inflatable holding sealing material and the metal shell can be increased, and the porous ceramic body can be firmly fixed in the metal shell. And the thickness can be reduced, and scattering of inorganic fibers can be prevented.
In order to obtain these effects, the acrylic organic binder usually needs to be blended in an amount of about 3 to 15% by weight in the non-expandable holding sealing material.

However, since the organic binder is gradually decomposed during use at a high temperature and the decomposition products are discharged together with the exhaust gas, in order to clear the regulation value in the exhaust gas, It was necessary to further reduce the content of the organic binder.

JP 11-182237 A

The present invention has been made to solve such problems, and a holding sealing material having a high coefficient of friction with respect to a metal shell even when the content of organic components is reduced as compared with the prior art, and this An object of the present invention is to provide an exhaust gas purifying apparatus using the above.

The holding sealing material of the present invention is a mat-like holding sealing material mainly composed of inorganic fibers,
Containing an organic binder having a coating strength of 5 MPa or more at room temperature ,
The content of the organic binder is 2% by weight or less .
In the holding sealing material of the present invention, the organic binder is preferably a styrene-butadiene resin and / or an acrylonitrile-butadiene resin.

The exhaust gas purifying apparatus of the present invention has a columnar ceramic body in which a number of through holes are arranged in parallel in the longitudinal direction and through which exhaust gas can pass in the longitudinal direction, and a cylinder that covers at least the outer circumference of the ceramic body in the longitudinal direction. The holding sealing material of the present invention is disposed between the metal shells having a shape.
In the exhaust gas purifying apparatus of the present invention, it is desirable that one end of each of the numerous through holes formed in the ceramic body is sealed, and the ceramic body functions as a filter.

According to the holding sealing material of the present invention, since an organic binder having a high coating strength (5 MPa or more) is used at room temperature, the coefficient of friction against the metal shell is increased even if the amount of the organic binder used is reduced. The ceramic body can be firmly fixed to the metal shell from the start of use. For this reason, the usage-amount of an organic binder can be reduced and the quantity of the decomposition gas of the organic binder generated during use at high temperature can be reduced.

According to the exhaust gas purifying apparatus of the present invention, since the holding sealing material of the present invention is used, the ceramic body is applied to the metal shell from the start of use even if the amount of the organic binder in the holding sealing material is reduced. Can be fixed firmly. For this reason, the usage-amount of an organic binder can be decreased and the discharge | emission amount of the decomposition gas of the organic binder generated during use at high temperature can be reduced.
Further, in the exhaust gas purifying apparatus of the present invention, the ceramic body can be made to function as a filter by sealing one end of a large number of through holes formed in the ceramic body, such as graphite in the exhaust gas. Particulates can be collected and removed from the ceramic body.

The holding sealing material of the present invention is a mat-like holding sealing material mainly composed of inorganic fibers,
It contains an organic binder having a film strength of 5 MPa or more at room temperature.

FIG. 1 is a plan view schematically showing an example of the holding sealing material of the present invention. FIG. 2 is a perspective view schematically showing how the holding sealing material of the present invention is wound around a ceramic body and inserted into a metal shell.

As shown in FIGS. 1 and 2, the holding sealing material 10 of the present invention is provided with a convex portion 12 on one short side of a substantially rectangular base material portion 11 and a concave portion 13 on the other short side. The convex portion 12 and the concave portion 13 are just fitted when the holding sealing material 10 is wound around the outer periphery of the ceramic body 20, thereby the holding sealing material 10. Can be wound around the outer periphery of the ceramic body 20 so as not to be misaligned.
The shape of the holding sealing material 10 is not particularly limited as long as it is a mat shape. For example, the holding sealing material 10 may have a plurality of convex portions and concave portions, or may not have convex portions and concave portions. May be. Moreover, the combination of the shape of the convex part 12 and the recessed part 13 other than the combination using a rectangular shape as shown in FIG. 1 may be a combination using a triangle, a combination using a semicircular shape, or the like.

The holding sealing material 10 is housed in a cylindrical metal shell 30 while being wound around the outer peripheral surface of the columnar ceramic body 20, and constitutes an exhaust gas purification device. When the holding sealing material 10 is accommodated in the metal shell 30, the holding sealing material 10 is compressed in the thickness direction, so that a repulsive force (surface pressure) against the compressive force is generated, and this repulsive force causes the ceramic body 20. Is fixed in the metal shell 30.

The holding sealing material 10 is mainly composed of inorganic fibers and contains an organic binder. Usually, a mat-like molded body made of inorganic fibers is impregnated with an organic binder. Moreover, additives such as a crosslinking agent may be added to the holding sealing material 10 as necessary.

The organic binder has a coating strength of 5 MPa or more at room temperature.
The inventor of the present invention uses an organic binder having a coating strength at room temperature of 5 MPa or more, thereby improving the coefficient of friction between the surface of the holding sealing material and the surface of the metal shell in the exhaust gas purification device. It was found that the ceramic body can be firmly fixed to the metal shell from the beginning. This is because the organic binder has a higher film strength than conventional organic binders and is not easily broken or stretched by an external force. Therefore, the strength of the part bonded through the organic binder is improved, and the inorganic fibers and This is considered to be because the adhesive strength between the metal shells, the adhesive strength between the inorganic fibers, and the adhesive strength between the inorganic fibers and the ceramic body are improved.
A more desirable lower limit of the coating strength of the organic binder at room temperature is 10 MPa.

The film strength is measured by using a dumbbell-shaped test piece having a thickness of 0.4 mm made of an organic binder and performing a tensile test at a speed of 300 mm / min with an Instron type tensile tester. Breaking strength.
The test piece can be produced by pouring latex, which is a raw material for the organic binder, into a framed glass plate, allowing it to stand at room temperature, drying, and forming a film.

As the organic binder having a coating strength of 5 MPa or more at room temperature, for example, styrene-butadiene resin, acrylonitrile-butadiene resin, and the like are preferably used.
These organic binders may be used independently and 2 or more types may be used together.
The styrene-butadiene resin is obtained by copolymerizing a styrene monomer, a butadiene monomer or the like. On the other hand, the acrylonitrile-butadiene-based resin is obtained by copolymerizing an acrylonitrile monomer, a butadiene monomer, or the like.

The decomposition temperature of the organic binder is desirably 200 ° C. or higher. When the temperature is lower than 200 ° C., the organic binder is burned out at the initial stage of use of the exhaust gas purifying apparatus using the holding sealing material 10, and the effect of the present invention to firmly fix the ceramic body 20 to the metal shell 30 is achieved. When using the exhaust gas purification device, it may not be sufficiently obtained.
When the exhaust gas purifying apparatus using the holding sealing material 10 is heated to 200 ° C. or higher, the coefficient of friction on the metal shell 30 side is improved due to oxidation of the metal shell 30 or the like. Even if burned out, the ceramic body 20 can be firmly fixed to the metal shell 30.

A desirable upper limit of the content of the organic binder is 2% by weight. If it exceeds 2% by weight, the total amount of the organic binder decomposition gas generated during use at high temperatures may not be sufficiently reduced. The more desirable upper limit of the content of the organic binder with respect to the entire holding sealing material of the present invention is 1.5% by weight, and the more desirable upper limit is 1% by weight.
The organic binder used in the holding sealing material of the present invention can improve the coefficient of friction with the metal shell even when the content is 1% by weight or less.

Is not particularly restricted but includes inorganic fibers, such as alumina fibers mainly containing alumina, alumina (Al 2 _{O 3)} and silica alumina as a main component (SiO ₂₎ - ceramic fibers such as silica-based fibers Preferably used.
The desirable lower limit of the alumina content in the alumina-silica fiber is 40% by weight, and the desirable upper limit of the silica content is 60% by weight. When the content of alumina is less than 40% by weight or when the content of silica exceeds 60% by weight, the heat resistance and the repulsive force when a compressive load is applied may not be sufficient. More preferably, the alumina content is 72% by weight and the silica content is 28% by weight.

The fiber tensile strength of the inorganic fiber is desirably 1.2 GPa or more, and more desirably 1.5 GPa or more. The fiber bending strength of the inorganic fiber is desirably 1.0 GPa or more, and more desirably 1.5 GPa or more. Further, fracture toughness of the inorganic fibers is desirably 0.8Mn ^{/ m 3/2} or more, and more desirably at 1.3MN ^{/ m 3/2} or more. This is because when the fiber tensile strength, fiber bending strength, and fracture toughness value are large, the inorganic fiber is strong against tension and bending, and is flexible and difficult to break.

A desirable lower limit of the average fiber length of the inorganic fibers is 10 mm, and a desirable upper limit is 100 mm. If the average fiber length is less than 10 mm, the fibers may be easily sucked into the respiratory system. In addition, the characteristic as a fiber is no longer substantially exhibited, and when a mat-like molded body is formed, an appropriate entanglement between fibers does not occur, and a sufficient surface pressure cannot be obtained. When the average fiber length exceeds 100 mm, the entanglement between the fibers becomes too strong, so that when the mat-shaped molded body is formed, the fibers are likely to be unevenly accumulated, and the variation in the surface pressure value may become too large. A more desirable lower limit of the average fiber length of the inorganic fibers is 20 mm, and a more desirable upper limit is 40 mm.

The variation in the fiber length of the inorganic fiber is preferably within ± 4 mm with respect to the average fiber length. If the variation in fiber length exceeds ± 4 mm, the fibers are likely to accumulate unevenly and the variation in surface pressure value may become too large. The variation in the fiber length of the inorganic fiber is more preferably within ± 2 mm.

A desirable lower limit of the average fiber diameter of the inorganic fibers is 3 μm, and a desirable upper limit is 25 μm. If the average fiber diameter is less than 3 μm, the strength of the fiber itself may be low and a sufficient surface pressure may not be obtained, and the fiber may be easily sucked into the respiratory system. When the average fiber diameter exceeds 25 μm, the resistance to air flow is reduced when a mat-like molded body is formed, and the sealing performance may be deteriorated. In addition, the damage is caused by an increase in small scratches accompanying an increase in the fiber surface area. The strength may decrease. A more desirable lower limit of the average fiber diameter of the inorganic fibers is 5 μm, and a more desirable upper limit is 15 μm.

The variation in the fiber diameter of the inorganic fibers is desirably within ± 3 μm with respect to the average fiber diameter. If the variation in the fiber diameter exceeds ± 3 μm, the fibers are likely to be accumulated unevenly, and the variation in the surface pressure value may become too large. The variation in fiber diameter of the inorganic fibers is more preferably within ± 2 μm.

The shot content of the inorganic fiber is desirably 3% by weight or less. If it exceeds 3% by weight, the variation of the contact pressure value may become too large. More preferably, the inorganic fiber has a shot content of 0% by weight, that is, the inorganic fiber does not contain any shot.

In addition to the circular shape, the cross-sectional shape of the inorganic fiber may be, for example, an elliptical shape, an oval shape, a substantially triangular shape, a rectangular shape, or the like.

A desirable lower limit of the thickness of the holding sealing material 10 before being accommodated in the metal shell 30 is a gap formed by the outer diameter of the ceramic body 20 and the inner diameter of the metal shell 30 accommodating the ceramic body 20. The upper limit is 1.1 times, and the desirable upper limit is 4.0 times. If the thickness of the holding sealing material 10 is less than 1.1 times, the ceramic body 20 may be displaced or loose with respect to the metal shell 30. Further, in this case, an excellent gas sealing property cannot be obtained, so that exhaust gas easily leaks from the gap portion, and exhaust gas purification may be incomplete. Further, when the thickness of the holding sealing material 10 exceeds 4.0 times, when the ceramic body 20 is accommodated in the metal shell 30, the metal shell 30 of the ceramic body 20 is used particularly when a press-fitting method is employed. Containment may be difficult. A more desirable lower limit of the thickness of the holding sealing material 10 is 1.5 times, and a more desirable upper limit is 3.0 times.

A desirable lower limit of the coefficient of static friction with respect to the metal shell 30 of the holding sealing material 10 is 0.25. If it is less than 0.25, the effect of the present invention for firmly fixing the ceramic body 20 to the metal shell 30 may not be sufficiently obtained.
The static friction coefficient can be measured using a measuring apparatus as shown in FIG. Specifically, an SUS plate 201, a holding seal material 210 having a size of 30 mm × 50 mm, and a weight 202 having a weight of 5 kg are placed in this order on a hot plate 200 at room temperature, and held in this state for 10 minutes. The wire 203 attached to is pulled by the universal testing machine 205 through the pulley 204 at a speed of 10 mm / min, and the peak load F is measured. The measurement is performed by fixing both of the weights 202 by providing protrusions or the like so that no deviation occurs at the interface between the weight 202 and the holding sealing material 210. From the obtained peak load F (N) and the vertical force N (N) acting on the contact surface between the SUS plate 201 and the holding sealing material 210, the static friction coefficient μ is calculated by the following relational expression (1).
μ = F / N (1)

The desirable lower limit of the bulk density (GBD; Gap Bulk Density) in the state accommodated in the metal shell 30 of the holding sealing material 10 is 0.20 g / cm ³ , and the desirable upper limit is 0.60 g / cm ³ . When the GBD is less than 0.20 g / cm ³ , a sufficiently high initial surface pressure cannot be obtained, and the state in which the ceramic body 20 is firmly fixed to the metal shell 30 due to deterioration of the surface pressure over time is an exhaust gas. It may not be sufficiently obtained during use of the purification device. On the other hand, when GBD exceeds 0.60 g / cm ³ , the assembly property of the holding sealing material 10 is deteriorated, the inorganic fibers are broken in the holding sealing material 10, or the ceramic body 20 is damaged. Sometimes. A more desirable upper limit of the GBD is 0.50 g / cm ³ .

A desirable lower limit of the initial surface pressure in a state where the holding sealing material 10 is housed in the metal shell 30 is 40 kPa. If the initial surface pressure is less than 40 kPa, a state in which the ceramic body 20 is firmly fixed to the metal shell 30 may not be sufficiently obtained during use of the exhaust gas purification device due to deterioration of the surface pressure over time. A more desirable lower limit of the initial surface pressure is 70 kPa.

A method for producing the holding sealing material 10 is not particularly limited, and a method of impregnating the organic binder into the molded body of the inorganic fiber having the shape of the holding sealing material 10 is preferably used.

A known method can be used as a method for producing an inorganic fiber molded body in the shape of the holding sealing material 10. For example, (1-1) a starting material containing an alumina source, a silica source, etc. is about 2000 ° C. To melt and spin and quench to produce inorganic long fibers containing alumina, silica, etc., (1-2) cutting the inorganic long fibers into a short length of inorganic short fibers; 1-3) The above-mentioned inorganic short fibers are molded to produce a mat-like inorganic fiber molded body, and (1-4) the first method of punching the molded body into a desired shape with a mold, (2-1) ) A precursor fiber is produced by discharging a spinning stock solution containing an alumina source, a silica source, and the like from a nozzle. (2-2) The precursor fiber is baked into inorganic long fibers, and (2-3) the above Cut the inorganic long fiber into a short length of inorganic short fiber, (2-4) Molding the inorganic short fibers to produce a shaped body of the mat-shaped inorganic fibers, and can use a second method such as punching into a desired shape by mold (2-5) the shaped body.
A commercially available inorganic fiber aggregate or the like can be used as the inorganic fiber molded body in the shape of the holding sealing material 10.

The method of impregnating the organic binder into the molded body of the inorganic fiber having the shape of the holding sealing material 10 is not particularly limited. For example, a latex in which the organic binder is dispersed in water using an emulsifier is manufactured. Examples include a method of immersing the molded body, a method of spraying the latex on the molded body by spraying, and a method of directly applying or dropping the latex on the molded body. Especially, the method of immersing the said molded object in the said latex is used suitably. This is because the organic binder can be impregnated reliably and evenly into the molded body.

A desirable lower limit of the content of the organic binder in the latex is 0.5% by weight, and a desirable upper limit is 2% by weight. When the content of the organic binder in the latex is less than 0.5% by weight, the obtained holding sealing material 10 may be easily dispersed with inorganic fibers. On the other hand, when the content of the organic binder in the latex exceeds 2% by weight, the content of the organic binder in the obtained holding sealing material 10 may increase, and the exhaust gas regulation value may not be cleared.

The minimum with the preferable viscosity of the said latex is 10 mPa * s, and a desirable upper limit is 40 mPa * s.

Moreover, after impregnating the organic binder into the molded body of the inorganic fiber, it is usually dried by heating while compressing in the thickness direction of the holding sealing material to remove excess moisture caused by the latex and hold it. The sealing material 10 is compressed in the thickness direction to reduce the thickness.

The holding sealing material 10 is preferably subjected to needle punching. In this needle punching process, the holding sealing material 10 is pierced with a needle (needle) to entangle the inorganic fibers in the vertical direction, so that the holding sealing material 10 having high elasticity can be obtained.
The needle punching process may be performed before or after impregnation with the organic binder.

According to the holding sealing material of the present invention, since an organic binder having a high film strength (5 MPa or more) at room temperature is used, the coefficient of friction with the metal shell 30 can be reduced even if the amount of the organic binder used is reduced. The ceramic body 20 can be firmly fixed to the metal shell 30 from the beginning of use. For this reason, the usage-amount of an organic binder can be reduced and the quantity of the decomposition gas of the organic binder generated during use at high temperature can be reduced.

As described above, the holding sealing material 10 of the present invention has a columnar ceramic body 20 in which a large number of through holes are arranged in the longitudinal direction and exhaust gas can pass in the longitudinal direction, and at least the longitudinal direction of the ceramic body 20. The exhaust gas purification device is configured by being disposed between the cylindrical metal shell 30 covering the outer periphery in the direction.
The exhaust gas purifying apparatus of the present invention has a columnar ceramic body in which a number of through holes are arranged in parallel in the longitudinal direction and through which exhaust gas can pass in the longitudinal direction, and a cylinder that covers at least the outer circumference of the ceramic body in the longitudinal direction. The holding sealing material of the present invention is disposed between the metal shells having a shape.

FIG. 3 is a cross-sectional view schematically showing an example of the exhaust gas purifying apparatus of the present invention.
As shown in FIG. 3, the exhaust gas purification apparatus 100 of the present invention mainly includes a columnar ceramic body 120, a cylindrical metal shell 130 that covers the outer periphery in the longitudinal direction of the ceramic body 120, and a ceramic body. An internal combustion engine such as an engine is provided at the end of the metal shell 130 on the side where the exhaust gas is introduced. The other end of the metal shell 130 is connected to an externally connected discharge pipe. In FIG. 3, arrows indicate the flow of exhaust gas.

The ceramic body 120 is a honeycomb structure made of porous ceramic in which a large number of through-holes 121 are arranged in parallel in the longitudinal direction, and the through-hole 121 has either an exhaust gas inflow side or an outflow side end. The exhaust gas, which is sealed with the filler 122, flows into one through hole 121, and always flows out from the other through hole 121 after passing through the partition wall 123 that separates the through holes 121. The ceramic body 120 having the through-hole 121 in which either the inflow side or the outflow side end of the exhaust gas is sealed with the filler 122 is a diesel particulate filter that collects particulates in the exhaust gas. Function as (DPF).

The ceramic body used in the exhaust gas purification apparatus of the present invention may function as a catalytic converter. In this case, the ceramic body can purify CO, HC, NOx, etc. in the exhaust gas. Although it is necessary to support a catalyst that can be formed, the through-holes may simply be those that are not sealed. Further, CO, HC, NOx, etc. in the exhaust gas can be purified to the ceramic body 120 having the through hole 121 in which either the inflow side or the outflow side end of the exhaust gas is sealed with the filler 122. By supporting a catalyst that can be used, the ceramic body 120 functions as a filter that collects particulates in the exhaust gas, and also serves as a catalytic converter for purifying CO, HC, NOx, and the like contained in the exhaust gas. Function.

Although the cross-sectional shape of the ceramic body 120 shown in FIG. 3 is circular, in the exhaust gas purification apparatus of the present invention, the cross-sectional shape of the ceramic body is not limited to a circular shape, for example, an elliptical shape, an oval shape, Any shape such as a polygonal shape can be used. In this case, it is desirable to change the cross-sectional shape of the metal shell according to the cross-sectional shape of the ceramic body.
Moreover, the ceramic body 120 may be integrally formed, or a plurality of porous ceramic members may be bundled through an adhesive layer.
Furthermore, a sealing material layer may be formed on the outer periphery of the ceramic body 120 in order to prevent the exhaust gas from leaking from the outer periphery.

The material constituting the ceramic body 120 is not particularly limited, and examples thereof include nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, and carbides such as silicon carbide, zirconium carbide, titanium carbide, tantalum carbide, and tungsten carbide. Examples thereof include oxide ceramics such as ceramic, alumina, zirconia, cordierite, and mullite. Among these, oxide ceramics such as cordierite, silicon carbide and the like are preferably used. This is because oxide ceramics such as cordierite can be manufactured at a low cost, have a relatively low coefficient of thermal expansion, and are not oxidized during use. Moreover, silicon carbide has excellent heat resistance and mechanical properties, and also has a high thermal conductivity. Note that a silicon-containing ceramic in which metallic silicon is mixed with the above-described ceramic, or a ceramic bonded with silicon or a silicate compound can also be used.

The catalyst to be supported when the ceramic body 120 also functions as a catalytic converter is not particularly limited as long as it is a catalyst that can purify CO, HC, NOx and the like in the exhaust gas. For example, platinum, palladium, rhodium, etc. The noble metal can be mentioned. The catalyst made of these noble metals is a so-called three-way catalyst, and the ceramic body 120 on which such a three-way catalyst is supported functions in the same manner as a conventionally known catalytic converter. Therefore, detailed description in the case where the ceramic body 120 also functions as a catalytic converter is omitted here.

The catalyst may be supported on the surface of pores inside the partition wall 123 or may be supported with a certain thickness on the surface of the partition wall 123. Further, the catalyst may be uniformly supported on the surface of the pores inside the partition wall 123 and / or the surface of the partition wall 123, or may be supported unevenly at a certain place.

As the metal shell 130, for example, when a press-fitting method is adopted as a method of assembling the ceramic body 120, a metal cylindrical member 131 having an O-shaped cross section as shown in FIG. When employed, a metal cylindrical member 132 having an O-shaped cross section as shown in FIG. 5 divided into a plurality of pieces along the longitudinal direction (that is, a clamshell) is used, and the tightening method is used. When employed, a metal cylindrical member having a C-shaped or U-shaped cross section having a slit (opening) extending along the longitudinal direction only at one place is used. When the canning method or the winding method is adopted, when the ceramic body 120 is assembled, the ceramic body 120 to which the holding sealing material 110 is fixed is accommodated in the metal shell 130 and the metal shell 130 is tightened. In this state, the open end is joined by a method such as welding, bonding, or bolting.
The metal constituting the metal shell 130 is preferably a metal having excellent heat resistance and impact resistance such as stainless steel.

The exhaust gas purification apparatus 100 having such a configuration functions as at least a diesel particulate filter (DPF), and collects particulates in exhaust gas discharged from an internal combustion engine such as a diesel engine to purify the exhaust gas. can do.
That is, the exhaust gas is introduced into the metal shell 130 through the introduction pipe, flows into the ceramic body 120 from the one through-hole 121, passes through the partition wall 123, and the particulates in the exhaust gas are passed through the partition wall 123. Are collected from the other through-holes 121 to the outside of the ceramic body 120 and discharged to the outside through the discharge pipe.

In the exhaust gas purification apparatus 100, when a large amount of particulates accumulates on the partition wall 123 of the ceramic body 120 and the pressure loss increases, the regeneration processing of the ceramic body 120 is performed.
In the regeneration process, a high-temperature gas is caused to flow into the through holes 121 of the ceramic body 120, the ceramic body 120 is heated, and the particulates deposited on the partition walls 123 are burned and removed. The high-temperature gas is generated by a method of providing a heating means on the exhaust gas inflow side in the metal shell 130 or the like.

Next, an example of the manufacturing method of the exhaust gas purification apparatus of the present invention described above will be described.
First, after preparing a raw material paste containing ceramic powder, binder, dispersion medium liquid, forming aid, pore-forming agent and the like made of the ceramic as described above, the raw material paste is subjected to extrusion molding to obtain a ceramic body 120. A ceramic molded body having substantially the same shape as the above is produced.
Next, after the ceramic molded body is dried using a drier, a predetermined through hole is filled with a sealing material paste having a composition similar to that of the raw material paste as a sealing material, and the through hole is filled with the ceramic material. Seal it.
Finally, the ceramic dried body filled with the above-mentioned sealing material paste is degreased and fired under predetermined conditions to be made of porous ceramic, and the ceramic is entirely composed of one sintered body. The body 120 can be manufactured.

In the case where the ceramic body 120 is formed by binding a plurality of porous ceramic members via an adhesive layer, for example, a prismatic porous ceramic member is formed in the same manner as described above. After the production, a plurality of porous ceramic members are bundled with an adhesive to produce a laminated body of prismatic porous ceramic members having a predetermined size.
Next, after heating the laminated body of porous ceramic members to dry and solidify the adhesive to form an adhesive layer, the outer peripheral portion thereof is cut into a predetermined shape using a diamond cutter or the like.
Finally, in the same manner as the adhesive layer, a ceramic body formed by forming a sealing material layer on the outer periphery using an adhesive and binding a plurality of porous ceramic members via the adhesive layer 120 can be manufactured.

Next, the holding sealing material 110 of the present invention is wound around and fixed to the outer periphery in the longitudinal direction of the ceramic body 120 manufactured through the above steps.
The method of winding and fixing the holding sealing material 110 around the ceramic body 120 is not particularly limited, and examples thereof include a method of attaching with an adhesive or a tape, a method of binding with a string-like body, and the like. Moreover, you may transfer to the following process in the state which just wound, without fixing by a special means.
The string-like body is preferably made of a material that decomposes by heat.

Next, the ceramic body 120 around which the holding sealing material 110 is wound is housed and fixed in the metal shell 130, thereby completing the exhaust gas purification apparatus of the present invention.
Examples of the method of accommodating the ceramic body 120 around which the holding sealing material 110 is wound in the metal shell 130 include methods such as a press-fitting method, a canning method, and a tightening method as described above.
In the press-fitting method, the ceramic body 120 around which the holding sealing material 110 is wound is accommodated in the metal cylindrical member 131 by being pushed in from one end of the metal cylindrical member 131 having an O-shaped cross section as shown in FIG. And fix.
In the canning method, for example, the ceramic body 120 around which the holding sealing material 110 is wound is placed in the semi-cylindrical lower shell 132b shown in FIG. 5, and then the upper shell provided on the semi-cylindrical upper shell 132a. The upper shell 132a is installed so that the through hole 134a of the fixing portion 133a and the through hole 134b of the lower shell fixing portion 133b provided in the lower shell 132b are exactly overlapped. Then, by inserting the bolt 135 through the through holes 134a and 134b and fixing with a nut or the like, the ceramic body 120 around which the holding sealing material 110 is wound is housed and fixed in a metal cylindrical member 132 having an O-shaped cross section. To do. Further, instead of bolting, a method such as welding or adhesion may be used.
In the above-described winding method, the ceramic body 120 in which the holding sealing material 110 is wound around a metal cylindrical member having a C-shaped or U-shaped cross section having a slit (opening) extending along the longitudinal direction only at one place. After the housing, as in the above canning method, the open end is joined and fixed by welding, bonding, bolting or the like with the metal shell tightened.

According to the exhaust gas purification apparatus 100 of the present invention, since the holding sealing material 110 of the present invention is used, the metal shell 130 can be used from the beginning of use even if the amount of the organic binder in the holding sealing material 110 is reduced. Further, the ceramic body 120 can be firmly fixed. For this reason, the usage-amount of an organic binder can be decreased and the discharge | emission amount of the decomposition gas of the organic binder generated during use at high temperature can be reduced.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

Example 1
Matt-like inorganic fiber aggregate having a thickness of 7.8 mm (Mitsubishi Chemical Co., Ltd., trade name: Maftech blanket, alumina 72% by weight-silica 28% by weight, GBD: 0.08 to 0.16 g / cm ³ , fiber (Diameter: 5 μm, fiber length: 5-10 cm, fiber tensile strength: 1 GPa, surface specific gravity: 1240 g / m ² ) were immersed in a latex containing 1% by weight of a styrene-butadiene resin (manufactured by Zeon Corporation). Thereafter, the inorganic fiber aggregate was taken out and dried at 120 ° C. for 1 hour while being compressed at 13 MPa to produce a holding seal material having a thickness of 7.4 mm containing 1% by weight of a styrene-butadiene binder.

(Examples 2 and 3)
Except for changing the concentration of the styrene-butadiene binder in the latex containing styrene-butadiene resin (manufactured by Zeon Corporation), 3% by weight of the styrene-butadiene binder was obtained in the same manner as in Example 1 (Example) 2) A holding sealing material having a thickness of 7.4 mm and containing 5% by weight (Example 3) was produced.

(Example 4)
A thickness containing 2% by weight of a styrene-butadiene binder in the same manner as in Example 1 except that the concentration of the styrene-butadiene binder in the latex containing styrene-butadiene resin (manufactured by Zeon Corporation) was changed. A holding sealing material having a thickness of 7.4 mm was produced.

(Comparative Examples 1-3)
An acrylate binder in the same manner as in Example 1, except that a latex containing an acrylate binder (manufactured by Nippon Zeon Co., Ltd.) was used instead of a latex containing styrene-butadiene resin (manufactured by Nippon Zeon Co., Ltd.). A holding sealing material having a thickness of 7.4 mm was prepared, containing 1% by weight (Comparative Example 1), 3% by weight (Comparative Example 2), and 5% by weight (Comparative Example 3).

(Evaluation Test 1)
About the holding | maintenance sealing material manufactured in Examples 1-4 and Comparative Examples 1-3, the static friction coefficient was measured using the measuring apparatus shown in FIG.
The results are shown in Table 1.

(Evaluation test 2)
Ceramic bodies made of cylindrical cordierite having a number of through-holes of 31 / cm ² , a partition wall thickness of 0.3 mm, a diameter of 143.8 mm, and a length of 150 mm were used in Examples 1 to 4 and Comparative Examples 1 to 4. 3 is fixed in a cylindrical metal shell made of stainless steel having an inner diameter of 151.8 mm and a length of 150 mm through the holding sealing material manufactured in step 3, and a load is applied from one end face side of the ceramic body to position the ceramic body. The value of the load causing the deviation was measured, and this load value was defined as the punching strength.
In addition, the surface pressure in the state accommodated in the metal shell of the said holding sealing material was 97 kPa.
The results are shown in Table 1.

(Evaluation Test 3)
The latex containing styrene-butadiene resin used in Examples 1 to 4 (manufactured by Zeon Corporation) was poured into a glass plate with a frame, left to dry at room temperature, punched out, and a dumbbell having a thickness of 0.4 mm. A test piece having a shape was prepared. As a result of measuring the coating strength (tensile breaking strength) and the elongation at the time of tensile fracture by conducting a tensile test at 300 mm / min with an Instron type tensile tester using this test piece, the coating strength Was 11.5 MPa, and the elongation at the time of tensile fracture was 100%.
Similarly, the test piece was produced using the latex (made by Nippon Zeon Co., Ltd.) containing the acrylate resin used in Comparative Examples 1-3. As a result of measuring the film strength and the elongation at the time of tensile fracture using this test piece, the film strength was 1.0 MPa and the elongation at the time of tensile fracture was 1300%.

In addition, the latex containing styrene-butadiene resin used in Examples 1 to 4 (manufactured by Nippon Zeon Co., Ltd.) was poured into a framed glass plate, left to dry at room temperature, and then heat treated at 130 ° C. for 10 minutes. This was performed, punched out, and a dumbbell-shaped test piece having a thickness of 0.4 mm was produced. As a result of measuring the coating strength (tensile breaking strength) and the elongation at the time of tensile fracture by conducting a tensile test at 300 mm / min with an Instron type tensile tester using this test piece, the coating strength Was 12.0 MPa, and the elongation at the time of tensile fracture was 100%.
Similarly, using the latex (made by Nippon Zeon Co., Ltd.) containing the acrylate resin used in Comparative Examples 1 to 3, a test piece was prepared by heat treatment at 130 ° C. for 10 minutes. As a result of measuring the film strength and the elongation at the time of tensile fracture using this test piece, the film strength was 2.0 MPa and the elongation at the time of tensile fracture was 450%.

(Evaluation Test 4)
About the test piece which put the latex (made by Nippon Zeon Co., Ltd.) containing the styrene-butadiene system resin used in Examples 1 to 4 and dried at 120 ° C. for 1 hour, TG− When DTA was measured and the decomposition start temperature of the styrene-butadiene resin was determined, the decomposition start temperature was 369 ° C. in air and 363 ° C. in a nitrogen atmosphere.
Similarly, a latex (made by Nippon Zeon Co., Ltd.) containing the acrylate resin used in Comparative Examples 1 to 3 was put in a mold and dried at 120 ° C. for 1 hour, and the decomposition start temperature was determined. However, the decomposition initiation temperature was 363 ° C. in air and 380 ° C. in a nitrogen atmosphere.

As is apparent from the results of the evaluation test, when a styrene-butadiene resin was used as the binder, the friction coefficient was high even when contained in 1% by weight (see Evaluation Test 1), and the punching strength was high. (See Evaluation Test 2).
In addition, the styrene-butadiene resins used in Examples 1 to 4 had higher tensile fracture strength (film strength) and smaller tensile fracture elongation than the acrylate resins used in Comparative Examples 1 to 3 (evaluation). Test 3).
The decomposition start temperatures of the styrene-butadiene resins used in Examples 1 to 4 and the acrylate resins used in Comparative Examples 1 to 3 were not significantly different.

It is the top view which showed typically an example of the holding sealing material of this invention. It is the perspective view which showed typically a mode that the holding sealing material of this invention was wound around a ceramic body, and inserted in metal shells. It is sectional drawing which showed typically an example of the exhaust-gas purification apparatus of this invention. It is the perspective view which showed typically an example of the metal shell which comprises the exhaust-gas purification apparatus of this invention. It is the disassembled perspective view which showed typically another example of the metal shell which comprises the exhaust-gas purification apparatus of this invention. It is the figure which showed typically the measuring apparatus of the static friction coefficient.

Explanation of symbols

10, 110, 210 Holding sealing material 11 Base material portion 12 Protruding portion 13 Recessing portion 20, 120 Ceramic body 30, 130 Metal shell 100 Exhaust gas purifying device 121 Through hole 122 Filling material 123 Partition 131, 132 Metal cylindrical member 132a Upper part Shell 132b Lower shell 133a Upper shell fixing part 133b Lower shell fixing part 134a, 134b Through hole 135 Bolt 200 Hot plate 201 SUS plate 202 Weight 203 Wire 204 Pulley 205 Universal testing machine

Claims (4)

A mat-like holding sealing material mainly composed of inorganic fibers,
Containing an organic binder having a coating strength of 5 MPa or more at room temperature ,
A holding sealing material, wherein the content of the organic binder is 2% by weight or less . The holding sealing material according to claim 1, wherein the organic binder is a styrene-butadiene resin and / or an acrylonitrile-butadiene resin. A large number of through-holes are arranged in parallel in the longitudinal direction, and between a columnar ceramic body capable of passing exhaust gas in the longitudinal direction and a cylindrical metal shell covering at least the outer circumference of the ceramic body in the longitudinal direction. An exhaust gas purification apparatus comprising the holding sealing material according to claim 1 or 2 . The exhaust gas purifying device according to claim 3 , wherein one end of each of a plurality of through holes formed in the ceramic body is sealed, and the ceramic body functions as a filter.

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