JP2003293757A - Holding material for catalytic converter and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide a holding material for a catalytic converter, in which the variation in thickness and area density is much smaller than that of a conventional holding material, and which can sufficiently cope with a thinner catalyst carrier. The present invention is used for a catalytic converter including a catalyst carrier, a metal casing accommodating the catalyst carrier, and a holding material wound around the catalyst carrier and interposed in a gap between the catalyst carrier and the metal casing. A holding material for a catalytic converter, wherein the holding material is formed by laminating an inorganic fiber mat having a thickness per layer of 3 mm or less or a blanket material obtained by needle-working the mat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst carrier holding material used in a catalytic converter for purifying exhaust gas of automobiles and the like, and a method for producing the same.

[0002]

2. Description of the Related Art As is well known in vehicles such as automobiles, an exhaust gas purifying catalyst is used to remove harmful components such as carbon monoxide, hydrocarbons and nitrogen oxides contained in the exhaust gas of the engine. The converter is loaded. Such a catalytic converter is generally formed into a cylindrical shape as shown in a sectional view of FIG.
And a holding member 3 mounted on the catalyst carrier 1 and interposed in the gap between the catalyst carrier 1 and the casing 2.

Since the catalyst carrier 1 is generally a cylindrical honeycomb molded body made of cordierite or the like and carrying a noble metal catalyst or the like, it is interposed in the gap between the catalyst carrier 1 and the casing 2. The holding material 3 has a function of safely holding the catalyst carrier 1 so that the catalyst carrier 1 does not collide with and damage the casing 2 due to vibration or the like while the vehicle is running, and has a gap between the catalyst carrier 1 and the casing 2. It is necessary to combine the function of sealing the unpurified exhaust gas so as not to leak. Therefore, at present, a so-called mat-type holding material is used in which inorganic fibers such as alumina fibers, mullite fibers, or other ceramic fibers are assembled to a predetermined thickness using an organic binder to have appropriate elasticity. There is.

[0004]

By the way, the mat-type holding material 3 is generally produced by using the Fourdrinier papermaking machine 100 as shown in FIG. The fourdrinier papermaking machine 100 shown in the drawing has an aqueous slurry 110 containing an inorganic fiber or an organic binder from a nozzle 104 of a stock inlet 103 on a mesh wire 102 that moves in the direction of the arrow by the rotation of a conveying roller 101. Is continuously supplied to the aqueous slurry 11 as the wire 102 moves.
The water in 0 is dehydrated and the inorganic fiber papermaking product 111 is sent to the subsequent pressing step and drying step (neither is shown).

In the stock inlet 103, the aqueous slurry 110 is constantly stirred to disperse the inorganic fibers, but the dispersion state of the inorganic fibers is not always constant,
Some fluctuation is inevitable. Therefore, the composition and the amount of the aqueous slurry 110 supplied from the nozzle 104 of the stock inlet 103 to the wire 102 are not strictly constant, and the thickness and the surface density of the inorganic fiber paper-making product 111 also vary. Then, such variations in thickness and areal density also appear in the holding material 3 which is the final product as they are, which is a cause of lowering the product yield.

Such variations in the thickness and areal density of the holding material 3 also greatly affect the holding performance and sealing performance of the catalyst carrier 1. The catalyst carrier 1 periodically repeats a high temperature state due to the passage of exhaust gas and a low temperature state in which the exhaust gas does not pass, and the expansion and contraction due to heat is severe. Therefore, if the thickness or the surface density of the holding material 3 is not uniform, a large stress may be applied to a portion of the catalyst carrier 1 that is in contact with the thick portion or the high density portion of the holding material 3, and cracks or damage may occur. There is. In order to improve the purifying ability, the wall thickness of the catalyst carrier 1 tends to decrease more and more, and the variation of the thickness and the surface density of the holding material 3 is becoming a big problem.

Therefore, an object of the present invention is to provide a holding material for a catalytic converter, which has a significantly smaller variation in thickness and areal density than conventional holding materials and can sufficiently cope with thinning of a catalyst carrier. Especially.

[0008]

Means for Solving the Problems The present inventors have conducted extensive studies to achieve the above object, and as a result, found that the above object can be achieved by laminating a mat material made of a thin inorganic fiber, and the present invention has been completed. did.

That is, in order to achieve the above object, the present invention provides a catalyst carrier, a metal casing for accommodating the catalyst carrier, and a catalyst carrier which is wound around the catalyst carrier and provided in a gap between the catalyst carrier and the metal casing. Holding material used for a catalytic converter having a holding material having a thickness of 3 m per layer.
An inorganic fiber mat of m or less or a blanket material obtained by needle-processing the mat is laminated, and a holding material for a catalytic converter, and an inorganic fiber having a basis weight of 500 g / cm ² or less. A mat made of blanket material made by needle processing the mat or the mat,
A holding material for a catalytic converter, which is characterized by being laminated.

Further, in the present invention, in order to obtain the above-mentioned holding material, the inorganic fiber has a thickness of 3 mm or less or a basis weight of 500 g /
Provided is a method for producing a holding material for a catalytic converter, which comprises a step of forming a mat material by papermaking so as to have a cm ² or less, and a step of laminating the mat material.
In addition, in order to make a blanket material, after obtaining the mat material,
Add a process of needle processing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The holding material and the method for producing the same according to the present invention will be described in detail below.

FIG. 1 is a sectional view schematically showing the holding material 3 of the present invention. As shown in the drawing, a plurality of thin inorganic fiber mat materials 30 are laminated to have a predetermined thickness. . The thickness of each mat member 30 made of inorganic fibers is 3 mm or less, and the thinner the mat member 30 made of inorganic fibers, the smaller the fluctuation in the thickness and density of each mat member 30 made of inorganic fibers. Preferably, it is 1 mm or less.

Further, such a mat material made of thin inorganic fibers
30 is 500 g / cm as basis weight ²Within the following range
It Furthermore, the inorganic fiber mat material 30 is needled.
It may be worked into a blanket material.

As the inorganic fibers, various inorganic fibers conventionally used for a holding material can be used. For example, alumina fibers, mullite fibers, or other ceramic fibers can be used as appropriate. More specifically, as the alumina fiber, for example, Al ₂ O ₃ having 90% by weight or more (the balance being SiO ₂ ) and having a low crystallinity in terms of X-ray is preferable. Average fiber diameter is 2-5
μm, wet volume 500-1000cc / 5g
Is preferred. As the mullite fiber, for example, a mullite composition having an Al ₂ O ₃ min / SiO ₂ min weight ratio of about 72/28 to 80/20 and a low crystallinity in X-ray is preferable. The average fiber diameter is preferably 3 to 7 μm, and the wet volume is preferably 500 to 1000 cc / 5 g. The wet volume is the height of the inorganic fibers in the graduated cylinder when 1 liter of water was added to a female cinder containing 5 g of inorganic fibers, stirred, and allowed to stand for 30 minutes.

Examples of other ceramic fibers include silica-alumina fibers and silica fibers, all of which may be those conventionally used as a holding material.
Further, glass fiber, rock wool or biosoluble fiber may be blended.

The organic binder used for assembling the inorganic fibers may be any known one, and rubbers, water-soluble organic polymer compounds, thermoplastic resins, thermosetting resins and the like can be used. Specifically, examples of rubbers include natural rubber, acrylic rubber such as a copolymer of ethyl acrylate and chloroethyl vinyl ether, and butadiene rubber. Examples of water-soluble organic polymer compounds include carboxymethyl cellulose and polyvinyl alcohol. Examples of the thermoplastic resin include acrylic resins such as homopolymers and copolymers of acrylic acid, acrylic acid ester, acrylamide, methacrylic acid, and methacrylic acid ester. Examples of the thermosetting resin include bisphenol type epoxy resin and novolac type epoxy resin.

To make the holding material 3, a paper making machine called a reticulated paper making machine is used. FIG. 2 is a cross-sectional view showing an example of a reticulated paper making machine. In the reticulated paper making machine 10, a semi-cylindrical paper making tank 12 is arranged inside a housing 11, and a central portion of a paper making machine 12 is provided. A cylindrical circular net 13 is rotatably arranged. An aqueous slurry 20 containing inorganic fibers and an organic binder is continuously supplied to the papermaking tank 12 from a stock inlet 14, and an overflow of the aqueous slurry 20 is discharged through a reflux passage 15 formed by the papermaking tank 12 and the housing 11. The liquid is discharged from the outlet 16 and the liquid level L1 is maintained substantially constant. Further, the upper portion of the gauze 13 projects from the liquid surface L1, and the felt 18 is pressed against a part of the outer peripheral surface of the gauze 12 by the couch roll 17 at this protruding portion.

The aqueous slurry may have the same composition (inorganic fiber concentration, additives) as the backslurry used for producing a mat-type holding material by a conventional Fourdrinier paper machine.

In the cylinder-shaped papermaking machine 10 thus constructed, when the cylinder 13 is rotated in the direction of the arrow in the figure, the liquid level inside the cylinder 13 is lowered to the position of L2, Liquid level difference occurs inside and outside. Along with this, water pressure is applied to the portion of the gauze 13 immersed in the aqueous slurry 20, moisture flows into the inside of the gauze 13, and the inorganic fibers adhere to the outer peripheral surface of the gauze 13. The rotation speed of the round net 13 is, for example, 5 to 20 rpm when the size of the round net is 500 mm in outer shape.
Is appropriate. Then, the adhered inorganic fibers have a liquid level L1.
When it comes out of the sheet, it is transferred to the felt 18 and becomes a paper product 21 of inorganic fibers, and then, a treatment such as drying is performed to form a mat material made of thin inorganic fibers. In addition, the member indicated by reference numeral 19 is made of an inorganic fiber not transferred to the felt 18
3 is a cleaning member (for example, a brush) to be removed from the outer peripheral surface.

The holding material 3 of the present invention is obtained by cutting the long thin inorganic fiber mat material obtained as described above into a predetermined size and laminating a plurality of them to a predetermined thickness. To be

In addition, a plurality of reticulated paper making machines 10 shown in FIG.
It is also possible to have a multi-stage configuration in which 0 is continuously passed.
As a result, the inorganic fiber papermaking products 21 are sequentially laminated and the thickness is increased each time the material passes through the reticulated papermaking machine 10, and after passing through the final stage, a thin inorganic fiber matting material similar to the above is laminated. A holding material having a laminated structure is obtained.

The inorganic fiber mat material can also be produced by using the papermaking machine 40 shown in FIG. In the illustrated paper making machine 40, a mesh-shaped endless belt 42 is arranged inside a cotton collection chamber 41, and inorganic fibers 31 to which a binder has been applied in advance are continuously introduced into the cotton collection chamber 41 from an introduction port 43. The mesh-shaped endless belt 42 is deposited on the transport surface. A blower 44 is arranged below the transport surface of the mesh endless belt 42, and the accumulated inorganic fibers 31 are adsorbed to the transport surface by suction. A heat roller 45 is arranged at the end of the reticulated endless belt 42 to heat and compress the inorganic fibers 31 deposited on the conveying surface to a predetermined thickness (here, 3 mm or less). As a result, the inorganic fiber mat material 30 is continuously obtained.

As described above, the inorganic fiber mat material 30 is obtained by the reticulated papermaking machine 10 or the papermaking machine 40. To make the matte material 30 into a blanket material, known needle processing may be performed. The processing conditions such as the pitch during needle processing are not particularly limited.

Since the holding material 3 of the present invention is formed by laminating a thin inorganic fiber mat material or a blanket material, when the same thickness is compared, the variation in thickness is 3% or less. In addition, the fluctuation of the surface density can be suppressed to 5% or less.

The holding material of the present invention formed as described above is
As shown in FIG. 4, it is wound around the catalyst carrier 1 and interposed in the gap with the casing 2 as in the conventional case, but since the variation in thickness and density is small, it is uniform over the entire outer peripheral surface of the catalyst carrier 1. It can be held at a constant surface pressure.

[0026]

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

Example 1 Alumina fiber 100 having an average fiber diameter of 3.5 μm and a wet volume of 800 cc / 5 g
An aqueous slurry containing 10 parts by weight of a solid content of an organic binder (“LX874” manufactured by Nippon Zeon Co., Ltd.) with respect to parts by weight was prepared. Then, using this aqueous slurry and the reticulated papermaking machine 10 shown in FIG.
mm long matte material made of inorganic fiber was prepared. In addition, the circular net 13 has a diameter of 500 mm, its rotation speed is 7 rpm, the felt 18 has a width of 1000 mm, its moving speed is 3.5 m / min, and the pressing force of the couch roll 17 is 5 mm.
It was set to kMPa.

Then, the obtained long matte material made of inorganic fiber was cut at intervals of 500 mm, and 30 sheets were randomly extracted from the mat material to prepare a laminate having a thickness of 8 mm. When the thickness and areal density of the laminate were measured, the thickness variation was 1.
It was 06%, and the variation in areal density was 2.84%.

(Example 2) A thickness of 3 mm was obtained in the same manner as in Example 1 except that alumina fibers having an average fiber diameter of 5 μm were used.
A long matte material made of inorganic fiber was obtained. Then, this inorganic fiber mat material is cut into a width of 600 mm and a length of 1000 mm, and the needle pitch is a staggered pattern of 5.5 mm and the needle length is 68 mm.
Using a needle mat manufacturing machine equipped with a mm needle needle, the blanket material was produced by needle processing at a feed rate of 850 mm / min.

Then, 30 blanket materials were laminated to prepare a laminated body having a thickness of 8 mm. When the thickness and areal density of the laminate were measured, the variation in thickness was 1.06% and the variation in areal density was 2.84%.

COMPARATIVE EXAMPLE 1 Using the same aqueous slurry as in Example 1 and the Fourdrinier paper machine 100 shown in FIG. 5, a long matte material made of inorganic fibers having a thickness after drying of 8 mm was prepared. did. The wire had a width of 1200 mm and the conveying speed was 15 m / min.

Then, the long-sized inorganic fiber mat material was cut at intervals of 500 mm, and 30 pieces were randomly extracted from the cut mat material to measure the thickness and areal density of each.
The variation rate of the thickness was 5.02% and the variation rate of the areal density was 6.71%, which was larger than those of Examples 1 and 2.

(Mounting Test) Each of the holding materials obtained in Examples 1 and 2 was wound around a cordierite catalyst carrier having an outer diameter of 110 mm and a length of 100 mm and having a cylindrical honeycomb structure, and was made into a stainless steel casing. It was attached and a catalytic converter was produced. Then, when the produced catalytic converter was connected to an exhaust pipe of a gasoline engine and exhaust gas was allowed to pass through, no unpurified exhaust gas was detected and it was confirmed that the sealing performance was good.

[0034]

As described above, according to the present invention,
It is possible to obtain a holding material for a catalytic converter in which variations in thickness and areal density are significantly smaller than those of conventional holding materials.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a holding material of the present invention.

FIG. 2 is a cross-sectional view showing an example of a papermaking machine used in the present invention (cylinder-type papermaking machine).

FIG. 3 is a cross-sectional view showing another example of the papermaking machine used in the present invention.

FIG. 4 is a sectional view schematically showing a catalytic converter.

FIG. 5 is a schematic diagram showing a configuration of a main part of a fourdrinier papermaking machine.

[Explanation of symbols]

1 Catalyst carrier 2 casing 3 holding material 10 Round-net paper making machine 11 housing 12 paper making tanks 13 round net 14 Stock Inlet 16 Couch roll 17 felt 20 Aqueous slurry 21 Paper made from inorganic fibers 40 paper making machine 41 Cotton collection chamber 42 mesh endless belt 44 Blower 45 heat roll

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Sakane             Nichias 1-8-1 Shintoda, Hamamatsu City, Shizuoka Prefecture             Hamamatsu Laboratory Co., Ltd. (72) Inventor Takahito Mochida             Nichias 1-8-1 Shintoda, Hamamatsu City, Shizuoka Prefecture             Hamamatsu Laboratory Co., Ltd. F-term (reference) 3G091 AA02 AB01 BA07 BA10 BA39                       GA06 HA27 HA29                 4D048 BB18 CC04

Claims (11)

[Claims] 1. A catalytic converter comprising a catalyst carrier, a metal casing for housing the catalyst carrier, and a holding member wound around the catalyst carrier and interposed in a gap between the catalyst carrier and the metal casing. A holding material for a catalytic converter, which is a holding material for laminating an inorganic fiber mat having a thickness of 3 mm or less per layer or a blanket material obtained by needle-working the mat. 2. A catalytic converter comprising a catalyst carrier, a metal casing for housing the catalyst carrier, and a holding member wound around the catalyst carrier and interposed in a gap between the catalyst carrier and the metal casing. An inorganic fiber mat having a basis weight of 500 g / cm ² or less or a blanket material obtained by needle-processing the mat,
A holding material for a catalytic converter, which is characterized by being laminated. 3. The holding material for a catalytic converter according to claim 1, wherein a mat or blanket material having different kinds of inorganic fibers is laminated. 4. The catalyst according to claim 1, wherein the density per layer of the inorganic fiber mat or blanket material is 0.1 to 0.6 g / cm ^3. Holding material for converter. 5. The holding material for a catalytic converter according to claim 1, wherein the variation amount of the areal density is 5% or less. 6. The inorganic fiber is at least one selected from alumina fiber, mullite fiber, alumina silica fiber, glass fiber, rock wool and biodegradable fiber, according to any one of claims 1 to 5. The holding material for a catalytic converter according to the item. 7. The holding material for a catalytic converter according to claim 1, wherein the inorganic fiber mat or blanket material is mixed with vermiculite. 8. A catalyst converter comprising a catalyst carrier, a metal casing for housing the catalyst carrier, and a holding member wound around the catalyst carrier and interposed in the gap between the catalyst carrier and the metal casing. A method of manufacturing a holding material, comprising:
Inorganic fibers with a thickness of 3 mm or less or basis weight of 500 g / cm
^{2. A} method of manufacturing a holding material for a catalytic converter, comprising: a step of forming a mat material by paper-making so that the number of sheets is ² or less; and a step of laminating the mat material. 9. The method for producing a holding material for a catalytic converter according to claim 8, wherein a step of performing needle processing is added after the mat material is obtained. 10. The method for producing a holding material for a catalytic converter according to claim 8 or 9, wherein the mat material is made into a paper by using a round-net paper making machine. 11. A method according to claim 10, wherein the reticulated paper making machines are connected in multiple stages and the formed matte materials are sequentially laminated.
A method for producing the holding material for a catalytic converter as described.