JPH09946A - Nonlight holding material and its production as well as catalyst converter using this monolith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate mounting and to improve the service life and gas sealability over a long period of time by setting the thickness and restoration surface pressure of a monolith holding material to the respectively specific values at the time of obtaining this holding material by impregnating an aluminous fiber mat with an org. binder liquid and compressing this mat in a thickness direction, then removing a medium liquid. SOLUTION: The production of the monolith holding material 3 is executed by first impregnating the base material consisting of the aluminous fibers with the org. binder liquid in a first stage. This base plate material is then compressed in a thickness direction in a second stage. The medium liquid of the org. binder liquid is removed while the thickness of the base material mat is maintained in the compressed state in a third stage, by which the monolith holding material is obtd. The thickness of the monolith holding material obtd. in this third stage is 1 to 1.5 times the compression thickness of the time when the mat is compressed in the second stage. The monolith holding material has the thickness restoration property in the state of releasing both sides when the org. binder is thermally decomposed. The restoration surface pressure in the compressed state of the thickness corresponding to the clearance formed of the outer peripheral surface of the monolith 1 and the inner peripheral surface of a metallic casing 2 is set at 0.5 to 30kg/cm<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolith holding material, a method for manufacturing the same, and a catalytic converter using the monolith. More specifically, the assembly is maintained in a compressed state by a binding force of an organic binder and heated. After that, the monolith holding material that restores the thickness by decomposing the organic binder and expresses the desired surface pressure in a fixed state on both sides and a method for producing the same, and the monolith holding material stably holds the monolith in the casing for a long period of time. The present invention relates to a catalytic converter that can be fixed.

[0002]

2. Description of the Related Art In the exhaust system of an internal combustion engine, various catalytic converters that use heavy metals or precious metals as catalysts are used as exhaust gas purifying devices for treating harmful components such as carbon monoxide and various hydrocarbons in exhaust gas. Used as. Catalytic converters are classified into the following two types depending on the form of the catalyst.

(1) A catalytic converter composed of a pellet catalyst formed by supporting a catalytic metal on a granular carrier such as ceramics, and a metal casing for containing the pellet catalyst. (2) A so-called monolithic catalyst in which a catalytic metal is supported on a tubular monolith carrier (hereinafter abbreviated as “monolith”) having a large number of exhaust gas passages therein, and the monolithic catalyst is housed therein. A catalytic converter composed of metal casings whose both ends are connected to exhaust gas conduits.

Unlike the catalytic converter of (1), the catalytic converter of (2) does not have wear due to collision of pellets during operation and can make the apparatus itself relatively small.
Widespread. The monolith is used by winding the monolith holding material in order to properly fix the monolith in the metal casing.

From the viewpoint of heat resistance, monoliths made of ceramic or metal are often used. In addition, in order to reduce the resistance when passing exhaust gas and increase the catalyst efficiency,
The mainstream is a monolith with a honeycomb structure that can secure a larger surface area in the exhaust gas flow path.

Further, as the structure of the metal casing,
The clamshell structure in which the monolith is housed so as to be sandwiched from both sides by a half-shaped metal casing and the joint portion of the casing is welded, or the stuffing structure in which the monolith is inserted into the metal casing is adopted.

In either case of the clam shell or the stuffing, the thickness of the monolith holding material is set so that the monolith is properly fixed in the metal casing, and therefore the thickness of the monolith holding material is different from the clearance between the outer peripheral surface of the monolith and the inner peripheral surface of the casing. It needs to be equal or slightly thicker. The reason is that when the fixing force of the monolith holding material with respect to the monolith decreases, when operating, there is a problem such as detachment of the monolith, misalignment in the metal casing, or leakage of exhaust gas from the outer periphery of the monolith. Is. Such a defect becomes a fatal defect in the catalytic converter.

Particularly, in a catalytic converter using a ceramic monolith, the thermal expansion of the monolith itself is small and the thermal expansion of the metal casing is large, so that the clearance between the outer peripheral surface of the monolith and the inner peripheral surface of the casing increases during operation. As a result, the holding power of the monolith holding material tends to decrease. Further, in manufacturing, the variation in the outer diameter dimension of the monolith is relatively large, and when the monolith is extremely small, a predetermined holding force may not be obtained from the time of assembly.

Therefore, since the monolith holding material maintains a predetermined holding force from room temperature to high temperature during operation, the above-mentioned difference in clearance due to variations in outer diameter of individual monoliths, and the monolith and metal casing It is necessary to follow the above-mentioned change in clearance due to thermal expansion.

In recent years, a method for fixing a monolith in a metal casing has been earnestly studied, and various inorganic fibers are used as a monolith holding material to be mounted between the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing. There has been proposed a monolith holding material processed into the above form. The technologies disclosed so far and their problems are as follows.

Japanese Unexamined Patent Publication No. 1-240715 proposes an elastic mat (monolith holding material) of shotless ceramic fibers sewn and compressed in the thickness direction. However, such an elastic mat cannot be compressed to a desired thickness unless the sewing pitch is made fine, and if the sewing pitch is made fine, the fibers are damaged and the elasticity is lost. It is difficult to perform fine processing, and there are problems such as fraying of the sewing end portion and thread breakage.

British Patent No. 2171180A proposes a mat-like body (monolith holding material) in which inorganic fibers are vacuum-packed in a plastic bag. However, since the plastic bag lacks flexibility in such a mat-shaped body, it is difficult to wind the mat-shaped body in close contact with the monolith, and since it is difficult to provide a labyrinth for joining at both ends of the plastic bag, sealing performance is improved. There is a problem that it lacks. Further, there is a problem that the film is easily broken during carrying and assembling.

US Pat. No. 4,693,338 describes
A monolith holding material has been proposed which uses a blanket obtained by adding a small amount of a binder to ceramic fibers and highly compressing the binder, and a braid made of ceramic fibers. However, such a monolith holding material is unsatisfactory because mounting and assembling are complicated.

Japanese Unexamined Patent Publication (Kokai) No. 53-2753 discloses a heat insulating material (monolith holding material) formed by molding and compressing a fibrous heat insulating material such as ceramic fiber, silica fiber and glass fiber together with an organic binder, which is more than the actual use state. )
Is proposed. However, such a monolith holding material has a thickness recovery property due to the decomposition of the organic binder, but is inferior in elasticity, and also has a drawback that thermal deterioration such as softening shrinkage proceeds in a high temperature range. Since the thickness is thinner than the clearance, the monolith may move in the casing and damage the monolith until the binder is decomposed.

Japanese Unexamined Patent Publication No. 7-77036 discloses that heat resistance
As a catalytic converter made of non-thermally expandable ceramic fiber, a metal case, a ceramic honeycomb catalyst (monolith) housed in the metal case, and a monolith arranged in a compressed state between the outer surface of the honeycomb catalyst and the inner surface of the metal case. There is described a catalytic converter comprising a ceramic fiber mat as a holding material, the mat having a compression characteristic that does not cause a large increase or decrease within a practical temperature range. However, since the above-mentioned ceramic fiber mat is not compressed by using a binder, it is necessary to highly compress it when it is mounted, so that the workability is poor, and the fiber itself is broken due to insufficient strength of the mat. I have a problem to say. There is also a problem that fibers are scattered.

Japanese Unexamined Patent Publication (Kokai) No. 57-56615 discloses a metal case, a ceramic monolith, and a seal material as a monolith holding material installed in the clearance between the inner peripheral surface of the metal case and the outer peripheral surface of the monolith. An exhaust gas purifying apparatus, wherein the sealing material is composed of ceramic fibers having a fiber diameter of 6 to 30 μm and has a bulk density of 0.1.
A device has been proposed which is compressed to 0.35 g / cm ³ and the ratio of the thickness after installation to the thickness before installation is 2.7 to 8.7. However, the sealing material is
Since the bulk density is low and the compression rate at the time of mounting is high, workability at the time of assembling the device is difficult.

Further, WO 94/24425 discloses a mat containing an integral composite sheet containing ceramic fibers and a binder, wherein the ceramic fibers are substantially free of shots and have an average fiber length of about 1: 1. Disclosed is a mounting mat that is -10 cm and yet exhibits a substantially constant pressure over about 20-1200 ° C when the mat has a flexible structural integrity and is fixed in the clearance. However, since such a mat becomes bulky due to its drying method and a large amount of compression is applied when it is mounted, there is a problem that workability is poor.
Further, from the characteristic of constant pressure, it is considered that the content of the binder resin is small, and there is a concern that the fiber may be damaged due to friction with the casing during mounting. Therefore, there is concern that the holding power with respect to the monolith may be reduced and the exhaust gas may leak from the outer peripheral portion of the monolith.

[0018]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object thereof is to easily mount a monolith because it is kept in a thin compressed state before the catalytic converter is assembled. It is a holding material that exhibits thickness restoration by heating when used, and can develop desired surface pressure on the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing, does not deteriorate even after long-term use, and has a high flow rate. It is intended to provide a monolith holding material which is not corroded even when exposed to the exhaust gas and can maintain a sufficient gas sealing property, and a method for producing the monolith holding material.

Still another object of the present invention is that the above-mentioned monolith holding material is mounted in a clearance formed between the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing, and the monolith holding material can withstand high-temperature exhaust gas flowing at high speed and violently. An object of the present invention is to provide a catalytic converter in which the monolith is stably fixed even when subjected to vibration or shock, and the leakage of exhaust gas in the monolith holding material does not occur.

[0020]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, have found that the thickness corresponding to the clearance between the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing. By constructing the monolith holding material from an alumina fiber mat that has a predetermined restoring force when compressed to 1, it was possible to prevent buckling of the monolith and to sufficiently exert its supporting effect, thus completing the present invention. did.

That is, the present invention relates to a monolith holding material, a method for producing the same, and a catalytic converter using the monolith, and the gist of these is as follows.

A first aspect of the present invention is a monolith which is formed in a tubular shape and carries an exhaust gas purifying catalyst, a metal casing which houses the monolith and whose both ends are connected to an exhaust gas conduit, and the monolith. A monolith holding material used in a catalytic converter comprising a monolith holding material mounted in a clearance between an outer peripheral surface and an inner surface of a metal casing, the monolith holding material being alumina compressed in a thickness direction. An organic binder that disappears due to thermal decomposition is uniformly contained in the high-quality fiber mat, (I)
The first step of impregnating the alumina-based fiber mat with the organic binder solution, (II) the second step of compressing the alumina-based fiber mat impregnated with the organic binder solution in the thickness direction, (II)
I) The thickness of the monolith holding material produced through the third step of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat, and the thickness of the monolith holding material obtained in the third step are It is 1 to 1.5 times the compressed thickness of the two steps, and when the organic binder is pyrolyzed, it has a thickness restoring property in an open state on both sides, and has a thickness equivalent to the clearance. Restoring surface pressure is 0.5 to 30 kg / c
m ² is a monolith holding material.

A second aspect of the present invention is a monolith formed in a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing that houses the monolith and has both ends connected to an exhaust gas conduit, and a monolith. A monolith holding material used in a catalytic converter comprising a monolith holding material mounted in a clearance between an outer peripheral surface and an inner surface of a metal casing, the monolith holding material being alumina compressed in a thickness direction. An organic binder that disappears by thermal decomposition is uniformly contained in the high quality fiber mat, and the compressed state is maintained by the organic binder to 0.1 to 0.5 g /
has a bulk density of cm ^3, when the organic binder is thermally decomposed, has a thickness recovery ratio of 2 to 10 times in both open, restorative surface pressure in the compression state of the thickness corresponding to the clearance 0 It exists in the monolith holding material characterized by being 0.5 to 30 kg / cm ² .

A third gist of the present invention is a monolith formed in a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing containing the monolith and having both ends connected to an exhaust gas conduit, and the monolith. A method for producing a monolith holding material for use in a catalytic converter comprising a monolith holding material mounted in a clearance between an outer peripheral surface and an inner surface of a metal casing, comprising: (I) a bulk density of 0.05 to
The first step of impregnating 0.20 g / cm ³ of the alumina fiber mat with the organic binder solution that disappears by thermal decomposition, (II) ½ the alumina fiber mat impregnated with the organic binder solution in the thickness direction. A third step of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat, and (III) When thermally decomposed, it has a thickness restoring property in a state where both sides are opened, and a restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 30 kg / cm ² , a monolith holding material. Exists in the manufacturing method of.

A fourth aspect of the present invention is a monolith which is formed in a tubular shape and carries an exhaust gas purifying catalyst, a metal casing which houses the monolith and whose both ends are connected to an exhaust gas conduit, and the monolith. In a catalytic converter composed of a monolith holding material mounted in the clearance between the outer peripheral surface and the inner surface of the metal casing, the monolith holding material is an organic material that disappears by thermal decomposition in the alumina fiber mat compressed in the thickness direction. A first step of impregnating an alumina fiber mat with an organic binder liquid, which comprises a binder uniformly contained, and (II) a second step of compressing the alumina fiber mat impregnated with the organic binder liquid in the thickness direction. Process, (III) Manufactured through a third process of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat And the thickness of the monolith holding material obtained in the third step is 1 to the compression thickness of the second step.
It is 1.5 times, and when the organic binder is pyrolyzed, it has a thickness restoring property in the open state on both sides, and the restoring surface pressure in the fixed state on both sides is 0.5 to 30 kg / cm ^2. It exists in the characteristic catalytic converter.

A fifth aspect of the present invention is a monolith which is formed in a tubular shape and carries an exhaust gas purifying catalyst, a metal casing which houses the monolith and whose both ends are connected to an exhaust gas conduit, and the monolith. In a catalytic converter composed of a monolith holding material mounted in a clearance between an outer peripheral surface and an inner surface of a metal casing, the monolith holding material is made of an alumina fiber mat having a bulk density of 0.05 to 0.20 g / cm ³ The mat is uniformly compressed, and an organic binder that disappears by thermal decomposition is uniformly contained in the mat, and the compressed state is maintained by the organic binder to obtain a bulk density of 0.1 to 0.5 g / cm ³ . When the organic binder is decomposed, the
The catalytic converter is characterized by having a thickness recovery rate of 10 times and a recovery surface pressure of 0.5 to 30 kg / cm ² in a fixed state on both surfaces.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a monolith holding material of the present invention, a method for producing the same, and a catalytic converter using the monolith will be described in detail with reference to the drawings.
FIG. 1 is an assembly perspective view showing a catalytic converter as one embodiment of the present invention. FIG. 2 is an assembly perspective view showing a winding procedure of the monolith holding material with respect to the monolith. FIG.
FIG. 3 is a schematic explanatory view showing a state change of the alumina fiber mat used in the present invention up to the monolith holding material.

In the figure, the monolith holding material of the present invention shown by reference numeral (3) is a holding material used in the catalytic converter shown in FIG. 1, and is exposed to high-temperature exhaust gas from an internal combustion engine. The binder is thermally decomposed and exhibits a thickness restoring property, and accordingly, a surface pressure is applied to the outer peripheral surface of the monolith (1) and the inner peripheral surface of the metal casing (2), and this surface pressure causes the metal casing ( 2) Hold the monolith (1) securely in.

The catalytic converter of the present invention is shown in FIG.
As shown in FIG. 1, a monolith (1) formed in a tubular shape and carrying an exhaust gas purifying catalyst, and a metal casing (2) housing the monolith (1) and having both ends connected to an exhaust gas conduit (2). , The monolith holding member (3) mounted in the clearance between the outer peripheral surface of the monolith (1) and the inner surface of the metal casing (2).

In the following description, the terms used are defined as follows. The base mat is an alumina fiber mat, and the compression mat is a base mat compressed in the thickness direction. The mat refers to a non-woven fabric-like aggregate of alumina fibers having a substantially uniform thickness, and also includes a blanket or a block.

The normal thickness is the thickness of the base mat to which no compressive force is applied in the thickness direction (thickness (A) in FIG. 3 (a)). The compressed thickness refers to the thickness of the compressed mat (thickness (B) in FIG. 3B). The normal thickness of the monolith holding material means the thickness of the monolith holding material (molded body) before being attached to the catalytic converter (thickness (C) in FIG. 3C). The clearance means a clearance formed between the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing (reference numeral (D) in FIG. 3D). In the following description, the monolith holding material is simply referred to as "holding material".

First, the holding material according to the first aspect of the present invention will be described with reference to FIG. In the figure, the above-mentioned holding material indicated by reference numeral (3) is a holding material in which the organic binder that disappears by thermal decomposition is uniformly contained in the compression mat, and (I) the base mat is coated with the organic binder liquid. First step of impregnation, (II) Second step of compressing the base mat impregnated with the organic binder liquid in the thickness direction, (III) Organic while maintaining the thickness (B) of the compressed base mat. The thickness (C) of the holding material (3) manufactured through the third step of removing the medium liquid of the binder liquid and obtained in the third step is 1 to the compressed thickness (B) of the second step. It is 1.5 times, and when the organic binder is pyrolyzed, it has a thickness restoring property in a state where both sides are opened, and a restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 30 k.
It is characterized in that it is g / cm ² . Hereinafter, a compressed state having a thickness corresponding to the clearance will be abbreviated as “double-sided fixed state”.

The alumina fiber constituting the base mat is
It is selected from fibers having a thickness restoring property when formed into a compression mat, that is, fibers having a repulsive force against the compressive force in the thickness direction. The alumina fiber generally has a fiber diameter of 1 to 50 μm, preferably 1 to 10 μm and a fiber length of 0.5 to 500 m, though it depends on the aggregated form of the fibers.
m, preferably 0.5-300 mm fibers are used.

As a typical example of the alumina fiber, in addition to the alumina-silica-based crystalline short fiber having a silica component content of 5% by weight or less, that is, an alumina component content of 95% by weight or more, 70% by weight of alumina is contained. Typical alumina fibers are 95% by weight and the balance is silica. In particular, mullite fiber containing 72% by weight of alumina is excellent in high temperature stability and elasticity and is a preferable alumina fiber.

The above-mentioned alumina-silica-based polycrystalline fibers, which are generally called alumina fibers, have a maximum operating temperature of about 120.
It is superior in heat resistance to amorphous ceramic fibers at 0 ° C, can withstand use at 1500 to 1600 ° C which is sufficiently higher than the exhaust gas temperature of an internal combustion engine, and its compression mat is highly elastic, And since there is very little heat deterioration such as softening and shrinkage seen in ceramic fibers,
A holding material (3) with little deterioration over time can be obtained.

The base mat may be a base mat using one of the above-mentioned alumina fibers alone, or a base mat using a mixture of two or more kinds. Furthermore 1
It may be a laminated mat formed by laminating a plurality of mats of the same kind or different kinds by using a single kind of alumina fiber alone. The bulk density of the base mat is usually 0.05 to 0.2 g / cm ^3.
, Preferably 0.05 to 0.15 g / cm ³ .
Bulk density becomes large 0.05 g / cm ³ less than the compression margin, the thickness recovery ratio of the holding member exceeds 0.2 g / cm ³ may be insufficient.

The holding material (3) of the present invention is formed by uniformly containing an organic binder in the base mat compressed in the thickness direction, that is, the compressed mat. The thickness of the organic binder is suppressed from being restored due to the binding force of the organic binder.

The above organic binder can be used without any particular limitation as long as it can maintain the compressed thickness (B) of the compressed mat at room temperature and restores the thickness when thermally decomposed. An organic binder that is easily thermally decomposed and burned at the use temperature of the holding material (3) is preferable. However, if the organic binder is a binder that loses its properties as a binder and restores its thickness under the use temperature condition of the holding material (3),
It doesn't have to be burned down. As for the organic binder, the holding material (3) is usually 600 ° C. or higher, and 900 to 100 at high temperature
Since it is used under a temperature condition of 0 ° C., a binder that is pyrolyzed in a short time to lose its properties as a binder under a temperature condition of about 600 ° C. or less is preferable, and a binder that burns out is particularly preferable.

As the organic binder, various rubbers, water-soluble polymer compounds, thermoplastic resins, thermosetting resins and the like can be used. As the rubber, natural rubber; a copolymer of ethyl acrylate and chloroethyl vinyl ether, n-
Examples thereof include acrylic rubbers such as a copolymer of butyl acrylate and acrylonitrile, copolymers of ethyl acrylate and acrylonitrile, nitrile rubbers such as a copolymer of butadiene and acrylonitrile, and butadiene rubber. Examples of the water-soluble polymer compound include carboxymethyl cellulose and polyvinyl alcohol. As the thermoplastic resin, an acrylic resin which is a homopolymer or a copolymer of acrylic acid, acrylic ester, acrylamide, acrylonitrile, methacrylic acid, methacrylic acid ester, etc .; acrylonitrile-styrene copolymer; acrylonitrile-butadiene-styrene copolymer Examples thereof include polymers. Examples of the thermosetting resin include bisphenol type epoxy resin and novolac type epoxy resin.

The above organic binder is used as an aqueous solution, a water dispersion type emulsion, a latex or an organic medium liquid solution. Hereinafter, these are collectively referred to as "binder liquid". As the binder liquid, a commercially available product may be used as it is or after diluted with water or the like. The organic binder does not necessarily have to be one kind, and may be a mixture of two or more kinds.

Among the above organic binders, compounds selected from the group consisting of synthetic rubbers such as acrylic rubber and nitrile rubber; water-soluble polymer compounds such as carboxymethyl cellulose and polyvinyl alcohol; acrylic resins are preferable.
Among them, acrylic rubber, nitrile rubber, carboxymethyl cellulose, polyvinyl alcohol, and acrylic resin not included in acrylic rubber are particularly preferable. These organic binders are easy to prepare or obtain a binder liquid, and the impregnation operation into the compression mat is easy, and even if the content is relatively low, sufficient thickness binding force is exerted, and It is easily pyrolyzed under operating temperature conditions, and the obtained holding material (3) is flexible and has excellent strength.

The content of the organic binder in the compression mat is not particularly limited, and is appropriately determined depending on the type of fibers constituting the compression mat, the compression thickness (B) of the compression mat, the repulsive force against compression, and the like. However, the organic binder is usually 10 to 100 parts by weight of the alumina fiber.
The amount is preferably 30 parts by weight (solid content basis). If the above-mentioned ratio of the organic binder is less than 10 parts by weight, the compressed thickness (B) of the compressed mat may not be maintained, and in order to maintain the compressed thickness (B) of the compressed mat, 30 parts by weight may be maintained. If the content is too large, the cost becomes high and it is difficult to decompose the entire amount. From such a viewpoint, the above-mentioned proportion of the organic binder is
It is preferably in the range of 15 to 25 parts by weight.

The above-mentioned holding material (3) of the present invention is (I)
The first step of impregnating the base mat with the organic binder liquid,
(II) Second step of compressing the base mat impregnated with the organic binder liquid in the thickness direction, (III) Medium liquid of the organic binder liquid while maintaining the compressed thickness (B) of the compressed base mat. It is manufactured through a third step of removing.

The normal thickness (A) of the base mat used in the first step is preferably 2 to 10 times the thickness (C) of the holding material (3). The compression thickness (B) of the compression mat in the second step is the thickness recovery property, the repulsive force against compression,
It is determined by the desired restoring surface pressure, gas sealability, etc. of the target holding material (3), but in order to achieve the above-mentioned restoration rate, it is usually 1 / (1) of the normal thickness (A) of the base mat.
It is about 1.25 or less, preferably in the range of 1/2 to 1/15. Further, the thickness (C) of the holding material (3) obtained in the third step is 1 to 1.5 times the compressed thickness (B) in the second step. The details of each of the above steps will be described in the method of manufacturing the holding material (3) according to the third aspect described later.

As can be understood from the above description, in the holding material (3) of the present invention, the specific material of the substrate mat, the normal thickness (A), etc., are elastic in the thickness direction, It is determined based on the clearance (D) of the catalytic converter, the desired restoring surface pressure of the holding material (3), the gas sealability, and the like. When the organic binder is thermally decomposed, the holding material (3) is
It has thickness restoration property when both sides are open, and the restoration surface pressure is 0.5 to 30kg for both fixed sides when both sides are fixed.
/ Cm ² , preferably 0.5 to 8 kg / cm ² .

The restoring surface pressure of the holding material (3) cannot be directly measured in a state where it is mounted on the catalytic converter, and is therefore defined as the value of the molded body before mounting. Then, the restored surface pressure is measured by any of the following methods.

(1) The organic binder is thermally decomposed in a state where one surface of the organic binder is in contact with the fixed plate and the other surface is in contact with the surface plate for measuring the surface pressure. A method of measuring pressure directly. (2) A method of indirectly measuring the surface pressure required for compressing the organic binder to its original thickness (C) before thermal decomposition after the organic binder is thermally decomposed and restored in a state where both sides are released.

Of the above methods, the latter method is simple and preferable. And in the below-mentioned embodiment of the present invention,
It is used as an index of the above-mentioned restoring surface pressure by the compression force when forming the compression mat.

The reason for defining the restoring surface pressure within the above range is as follows. That is, the restoring surface pressure is 0.5 kg / cm
^If the surface pressure is less than 2, fixing of the monolith (1) to the metal casing (2) may be uncertain, and the surface pressure of more than 30 kg / cm ² is not necessary as the fixing force of the monolith (1). . If the restoring surface pressure is within the above range, there is no problem with the gas sealability of the outer periphery of the monolith (1).

Further, the above-mentioned resilience of the holding material (3) is determined by the thickness (C) of the holding material (3) in the state in which both sides are opened after the binder is decomposed, that is, the thickness in the state in which both sides are opened. It can be specified by the restoration rate, and the restoration rate is 2 to 10
It is preferably double. Here, the thickness recovery rate of the holding material (3) is defined as the following formula (I) when the thicknesses before and after the thermal decomposition of the organic binder are d0 mm and d mm, respectively.

[0051]

[Formula 1] Thickness recovery rate = d / d0 (I)

[0052] Further, the holding member of the present invention (3) is a material configuration described above, a bulk density of 0.1 to 0.5 g / cm ^3, preferably is set to 0.2-0.4 g / cm ³ ,Also,
The unit tensile strength is preferably set to 10 to 40 kg / cm ² , and the tensile elastic modulus is preferably set to ²⁰⁰ to 700 kg / cm ² . The holding material (3) having such physical properties reliably holds the monolith without buckling due to the restoring surface pressure developed after the thermal decomposition of the organic binder when the converter is constructed.

Here, the unit tensile strength and the tensile elastic modulus are measured from the holding material (3) to a band (sample piece) having a predetermined length and width.
Is obtained by measuring the elongation and tensile strength of a sample piece using a tensile tester under a constant width and span and a constant pull rate. The unit tensile strength and the tensile elastic modulus E are calculated from the following equations, where the length of the sample piece is 10, the elongation of the sample piece is Δl, the tensile strength is Pn, and the cross-sectional area of the sample piece is A.

[0054]

[Equation 2] E = (Pn / A) / (Δl / l0) (II) Unit tensile strength Pa = Pn / A (III)

The thickness (C) of the above-mentioned holding material (3)
Is determined according to the clearance (D) of the catalytic converter. Generally, the clearance (D) is 2 to
When the clearance (D) is 8 mm, preferably 3 to 6 mm, and the clearance (D) is in this range, the thickness (C) of the holding material (3) to be fitted is preferably 3 to 10 mm. That is, the thickness of the holding material (3) is 1.0 to 2.0 times the clearance (D), preferably 1.0 to 1.6.
Double thickness is preferred.

Next, the holding material according to the second aspect of the present invention will be described with reference to FIG. The above-mentioned holding material indicated by reference numeral (3) is a holding material in which a base mat compressed in the thickness direction uniformly contains an organic binder that disappears by thermal decomposition. It has a bulk density of 0.1 to 0.5 g / cm ³ which is maintained, and when the organic binder is pyrolyzed, it has a thickness recovery rate of 2 to 10 times in the open state on both sides, and restores in the fixed state on both sides. The surface pressure is 0.5 to 30 kg / cm ² .

The above-mentioned holding material (3) uses the same base material as that of the holding material (3) according to the first aspect, and is the same as that of the holding material (3) according to the first aspect, for example. It can be manufactured through steps. Then, the holding material (3) is maintained in a compressed state by the organic binder and is 0.1 to 0.5 g.
It has a bulk density of / cm ³ and has a thickness recovery rate of 1.25 to 10 times when the organic binder is thermally decomposed when both sides are open, and the restoring surface pressure when both sides are fixed is 0.5 to 30 kg.
It is important that it is / cm ² .

The above-mentioned holding material (3) has other characteristics.
It is preferable that the holding material (3) according to the first aspect has the same characteristics. Specifically, the normal thickness (A) of the base mat is preferably 2 to 10 times the thickness (C) of the holding material (3). The organic binder is acrylic rubber, nitrile rubber, carboxymethyl cellulose,
It is preferably at least one selected from the group consisting of polyvinyl alcohol and acrylic resins not included in acrylic rubber, and the content thereof is the alumina fiber mat 1
It is preferably 10 to 30 parts by weight with respect to 00 parts by weight. Further, as in the case of the holding material according to the first aspect of the present invention, the restoring surface pressure in the both-side fixed state is 0.5 to 8 k.
g / cm ² , unit tensile strength is 10-40 kg / cm ²
The tensile elastic modulus is preferably 200 to 700 kg / cm ² .

Next, a method of manufacturing the holding material according to the third aspect of the present invention will be described with reference to FIG. The above production method is (I) bulk density 0.05 to 0.2 g /
cm ³ , preferably 0.05 to 0.15 g / cm ³ of a substrate mat impregnated with an organic binder solution that disappears by thermal decomposition, (II) a substrate mat impregnated with an organic binder solution The second step of compressing to 1/2 to 1/15 in the thickness direction, (III) the third step of removing the medium liquid of the organic binder liquid while maintaining the thickness (B) of the compressed base mat. When the organic binder is thermally decomposed, it has a thickness restoring property in a state where both sides are opened, and a restoring surface pressure in a state where both sides are fixed is 0.5 to 30 kg / cm ^2.
It is characterized by being.

In the above manufacturing method, the same material as described above is used as the base mat and the organic binder liquid. The above-mentioned first step is a step of impregnating the base mat with the organic binder liquid.

The substrate has a bulk density of 0.05 to 0.2 g
/ Cm < ³ >, preferably 0.05 to 0.15 g / cm < ³ > and a substrate mat of the above-mentioned normal thickness (A) is used. Further, as the organic binder liquid, acrylic rubber, nitrile rubber, carboxymethyl cellulose, polyvinyl alcohol, an aqueous solution containing an acrylic resin as an active ingredient, a water-dispersed emulsion, latex, or an organic medium liquid solution is preferably used. Then, the binder concentration in the organic binder liquid is the method of impregnating the base mat,
Although it can be appropriately determined depending on the content, etc., it is usually 2
To 50% by weight.

As the method of impregnating the organic binder liquid, a method of immersing the base mat in the organic binder liquid, a method of spraying the organic binder liquid on the base mat, or the like can be adopted. It is preferable to adopt the dipping method when the normal thickness (A) of the base mat is thick, and to adopt the spraying method when the normal thickness (A) is thin. In the case of the spraying method, the organic binder solution is sprayed at the time of spraying. Emulsion type with less stringing phenomenon is suitable.

As another impregnation method, a bulk alumina fiber is used as a starting material, which is dispersed and suspended in an organic binder liquid, and a flat aggregate of alumina fibers is obtained from this suspension. Examples of the method include collecting on a mesh plate or a porous plate by filtration or a papermaking technique. In such a method, when the alumina fibers are dispersed and suspended, the fibers are likely to be cut, so it is necessary to pay attention to the dispersion and suspension operations, and as the organic binder liquid, a liquid having a low viscosity is used. Is preferred.

The above-mentioned second step is a step of compressing the base material mat impregnated with the organic binder liquid in the thickness direction thereof. In this step, the target thickness (C) of the holding material (3) is set. Is defined and the content of the organic binder is controlled.

As the compression means, a method of pressing using a press plate or a press roller can be mentioned. Examples of the press plate include two liquid-permeable plate-like bodies, typically punching metal, resin net, metal net (mesh), perforated plate or plate-like body with good air permeability. The compression means,
It is preferable to use a binder liquid suction means in combination, and centrifugal dewatering may be used in combination with the compression method. That is,
By promoting deliquoring of the surface of the compression mat, uneven distribution of the organic binder on the surface of the compression mat is prevented, and various inconveniences caused by the organic binder, for example, removal of the medium liquid in the next third step (drying) In this case, it is possible to effectively prevent sticking to the drying equipment.

In the third step, the compressed thickness (B) of the compression mat obtained in the second step is measured in order to prevent the restoration of the temporary thickness in the undried state and avoid the uneven distribution of the organic binder. ) Is maintained, the medium liquid of the organic binder liquid is removed.

The third step is preferably carried out rapidly with hot hot air under a temperature condition in which the organic binder does not deteriorate or decompose. This is because the sedimentation of the organic binder in the organic binder liquid is prevented, and the ubiquity of the organic binder is further avoided. As a result, the holding material (3) having a large restoring surface pressure can be obtained.

Then, the holding material (3) of the present invention obtained by the above-mentioned manufacturing method has a thickness restoring property in the open state on both sides when the organic binder is pyrolyzed, as described above.
Restoration surface pressure is 0.5 to 30 kg / c when both sides are fixed
It is necessary to be m ² , preferably 0.5 to 8 kg / cm ² . Further, the holding material (3) has other characteristics,
It is preferable that the holding material (3) according to the first aspect or the second aspect has the same characteristics.

Next, a catalytic converter according to a fourth aspect of the present invention will be described with reference to FIGS. The above-mentioned catalytic converter shown in FIG. 1 has a monolith (1) formed in a tubular shape and carrying an exhaust gas purifying catalyst, and a metal casing (1) for accommodating the monolith and having both ends connected to an exhaust gas conduit ( In the catalytic converter composed of 2) and the holding material (3) mounted in the clearance (D) between the outer surface of the monolith (1) and the inner surface of the metal casing (2), the holding material (3) is thick. In the first step of impregnating the base mat with the organic binder solution, (II) the organic binder solution is formed. Second step of compressing the impregnated base mat in the thickness direction, (III) Third step of removing the medium liquid of the organic binder liquid while maintaining the thickness (B) of the compressed base mat
The thickness (C) of the holding material (3) manufactured through the steps and obtained in the third step is 1 of the compressed thickness (B) in the second step.
˜1.5 times, and when the organic binder is pyrolyzed, it has a thickness restoring property in a state where both sides are opened, and a restoring surface pressure in a state where both sides are fixed is 0.5 to 30 kg / cm ^2. Is characterized by.

The catalytic converter illustrated in the figure uses a monolith (1) having a honeycomb structure as a preferred embodiment. In the figure, reference numeral (2a) is a casing member in the upper half of the metal casing, reference numeral (21a) is a flange portion of the casing member (2a), reference numeral (2b) is a casing member in the lower half of the metal casing, and reference numeral (21b). ) Is a flange portion of the casing member (2b), reference numerals (22a) and (22b) are bolt holes for fixing the catalytic converter to the chassis of the automobile, and (4) and (5) are connection ports to the exhaust gas conduit. Indicates.

In the catalytic converter of the present invention, the holding material (3) is the same as the holding material (3) according to the first or second aspect obtained by the manufacturing method according to the third aspect. The holding material (3) is used. Particularly, in the above catalytic converter, the normal thickness (A) of the base mat is preferably 2 to 10 times the thickness (C) of the holding material (3).

In the above catalytic converter, the holding material (3) does not have to have the same thickness as the clearance (D), and a slightly thicker one can be mounted. However, if it is too thick or if it slips poorly with the metal casing (2), the flange portion (21
The thickness (C) of the holding material (3) is 1 with respect to the clearance (D) of the catalytic converter, since the protrusions (a) and (21b) stick out and welding becomes impossible. It is preferably from 0.0 to 2.0 times. Also, the second
The compression thickness (B) of the compression mat in the step is preferably larger than the clearance (D) of the catalytic converter, because a sufficient restoring force may not be generated due to the compression history.

Further, the initial bulk density of the holding material (3) mounted on the catalytic converter is 0.18 to 0.8.
g / cm ^3, when preferably 0.2 to 0.6 g / cm ^3, an initial surface pressure in the state of being attached to the catalytic converter holding material (3) is to 0~8kg / cm ^2, the organic binder is thermally decomposed , Retaining material in clearance (D) (3)
It is preferable to design the restoration surface pressure of 0.5 to 8 kg / cm ² and 50 to 90% or 110 to 150% of the initial surface pressure.

In the catalytic converter illustrated in the figure,
The metal casing (2) has a two-part clamshell structure in which two members, that is, a casing member (2a) that constitutes the upper half of the casing and a casing member (2b) that constitutes the lower half of the casing are integrated together. ing. The casing members (2a) and (2b) each have a flange portion (21
a) and (21b), and flange portions (21a) and (2
1b) functions as a joint surface when welding the casing members (2a) and (2b). Further, at both ends of one casing member (2b), connection ports (4), (5) for connecting to the exhaust gas conduit are provided. In addition,
As the metallic casing (2), a casing having a stuffing structure, which is formed in a tubular shape in advance and into which the monolith (1) is inserted, can be adopted.

The inner diameter of the metal casing (2) is made larger than the outer diameter of the monolith (1), and the clearance (D) is about 3 to 6 mm, generally 4 mm, and the clearance (D) is maintained. The material (3) is mounted. The thickness (C) of the holding material (3) is 1.0 to 2.0 times, preferably 1.0 to 1.6 times the clearance (D), and the outer periphery of the cylindrical monolith (1). It is installed on almost the entire surface. However, such a holding material (3) does not necessarily need to be attached to almost the entire outer peripheral surface of the monolith (1), and depending on the restoring surface pressure and the like, the holding material (3) is strip-shaped at the central portion in the longitudinal direction of the monolith (1). Attached to a monolith (1)
It is also possible to attach two strips at both ends.

Further, the holding material (3) of the present invention can be mounted by laminating it with another mat. That is, the holding material (3) of the present invention is used on the monolith (1) side, and the inner surface side of the metal casing (2) having a low temperature is made of a ceramic fiber such as an alumina-silica fiber having a lower heat resistance temperature than the alumina fiber. You may use the mat. The above-mentioned catalytic converter can be basically obtained according to the method for producing a catalytic converter described later.

Next, a catalytic converter according to the fifth aspect of the present invention will be described with reference to FIGS. The above-mentioned catalytic converter is basically the same as the catalytic converter according to the fourth aspect, except that the manufacturing method of the holding material (3) is not limited. In the above catalytic converter, the holding material (3) has a bulk density of 0.05 to 0.
2 g / cm ³ , preferably 0.05 to 0.15 g / cm
The base mat of No. ³ is compressed in the thickness direction, and the compression mat uniformly contains an organic binder that disappears by thermal decomposition. 5 g / cm ³ , preferably 0.2
It has a bulk density of ˜0.4 g / cm ³ , and when the organic binder is pyrolyzed, it has a thickness recovery rate of 2 to 10 times when both sides are open, and has a surface pressure of 0 when restored on both sides. ．
It is set to 5 to 30 kg / cm ² .

As described above, the converter has a monolith (1) formed in a cylindrical shape and carrying an exhaust gas purifying catalyst, and a metallic member for accommodating the monolith and having both ends connected to an exhaust gas conduit. It is composed of a casing (2) and a holding material (3) mounted in the clearance (D) between the outer peripheral surface of the monolith (1) and the inner surface of the metal casing (2). Clearance (D) formed between the outer peripheral surface and the inner peripheral surface of the metal casing (2)
The holding material (3) having a thickness (C) 1.0 to 2.0 times that of the holding material (3) is mounted, and the initial bulk density of the holding material (3) mounted on the catalytic converter is 0.18 to 0.8 g
/ Cm ³ , preferably 0.2 to 0.6 g / cm ³ , an initial surface pressure of 0 to 8 kg / cm ² when the holding material (3) is attached to the catalytic converter, when the organic binder is thermally decomposed, The restoring surface pressure of the holding material (3) in the clearance (D) is 0.5 to 8 kg / cm ² and is 5 times the initial surface pressure.
It is preferable to design so as to be 0 to 90%, or 110 to 150%.

Next, a method for manufacturing the above catalytic converter will be described with reference to FIGS. The above-mentioned manufacturing method includes (I) a first step of winding the holding material (3) around the outer peripheral surface of the cylindrical monolith (1), (II) a casing member (2a) of the upper half and a casing member (2) of the lower half.
After housing the monolith (1), around which the holding material (3) is wound, in the metal casing (2) having a two-part structure composed of b), the upper half casing member (2a) and the lower half of the metal casing are placed. It consists of a second step of welding half the casing members (2b) together and welding the outer periphery of the abutting portions thereof, and as the holding material (3), it disappears by thermal decomposition in the base material mat compressed in the thickness direction. A holding material containing an organic binder uniformly and having a restoring surface pressure of 0.5 to 30 kg / cm ² when the organic binder is thermally decomposed in a compressed state having a thickness corresponding to the clearance (D) ( Use 3).

In the first step, the holding material (3) is wound around the outer peripheral surface of the cylindrical monolith (1). The holding material (3) is wound such that the end portions, one of which is concave and the other of which is convex, are fitted and closed when the winding is completed. In the second step, the tubular monolith (1) that has been wound is housed in a proper position in the lower half casing member (2b), and then the casing member (2a) and the casing member (2b) are combined. Weld the outer periphery of the contact portion. At that time, if the thickness (C) of the holding material (3) is usually 2 times or less, preferably 1.6 times or less of the clearance (D), a part of the holding material (3) is a flange portion (21a). , (21b) are not bitten, which is preferable.

As can be understood from the above description, the present invention has the following excellent effects. That is, since the holding material (3) having the above-described configuration and the holding material (3) manufactured by the above-described manufacturing method are composed of the compressed body of alumina fiber having excellent durability, they are discharged from the internal combustion engine. There is no erosion or deterioration even when exposed to hot exhaust gas with a high flow velocity. Moreover, since the organic binder is thermally decomposed and disappears by the high-temperature exhaust gas to restore its thickness and exert elasticity, the clearance (D) between the monolith (1) and the metal casing (2) is completely closed. Thus, the exhaust gas can be prevented from leaking, and the monolith (1) can be stably held with a predetermined force in the metal casing (2) without being dissipated even by the exhaust gas having a high flow velocity.

Further, the holding material (3) follows the temporal change of the clearance (D) due to the temperature change of the monolith (1) and the metal casing (2), and is elastic in the metal casing (2). The monolith (1) can be fixed as desired. In addition, since the thickness of the alumina fiber mat as the base material can be restored to the original thickness, the monolith (1) can be stably held for a long period of time.

Further, since the holding material (3) is kept thin when the catalytic converter is assembled, the thickness restoring property is suppressed by the binding force of the organic binder, and the holding material itself is easily damaged. Can be installed without doing. Since the catalytic converter of the present invention uses the holding material (3) having the above characteristics, it can withstand long-term use even when subjected to severe vibration or shock, and the mounting of the holding material (3) Since it is simple, it can be easily manufactured, and the cost at the time of manufacturing can be reduced. Therefore, the catalytic converter of the present invention exhibits excellent effects as a high-performance catalytic converter attached to internal combustion engines of various vehicles that require high purification efficiency.

[0084]

EXAMPLES Next, the present invention will be described more specifically by way of examples, but the present invention is not limited to the description of these examples unless it exceeds the gist. In addition, in the following description, reference numerals of FIGS. 1 to 3 are cited, and numerical values of Examples and Comparative Examples are collectively shown in Tables 1 to 3. Also,
Unless otherwise specified, "%" means% by weight.

[Example 1] As a base mat, the normal thickness (A) was 16 mm, the width was 600 mm, and the length was 3600 m.
m mullite fiber mat (Mitsubishi Chemical Co., Ltd. trade name "Maftec blanket"; bulk density 0.10 g / cm
³ , average fiber diameter 4 μm, fiber length 20 to 200 mm; alumina component 72%, silica component 28%) were prepared. When the base mat is compressed to a thickness of 5.5 mm to form a compressed mat, 2.0 kg is required to maintain the compressed thickness (B).
/ Required pressure of cm ^2, when the pressure is released after keeping the compression thickness of 5 minutes (B), has a characteristic of thickness is restored to 16 mm.

Next, the above-mentioned base mat was immersed in a stock solution of an organic binder solution (trade name "LX874" manufactured by Nippon Zeon Co .; water-dispersion emulsion of acrylate rubber having a solid content of 45%) for 1 minute. Then, the openings of both sides of the base mat dipped in the organic binder liquid are 0.33.
2 mm punching metal (hole diameter 3.5 mm, aperture ratio 22.7)
%, Thickness 2.3 mm), and then pressed while sucking from one side to obtain a compressed thickness of 5.5 mm (B).
Compressed up. Next, while maintaining this compressed thickness (B), it was dried with hot air at 100 ° C. for 3 hours. After cooling, the polyester net and punching metal were removed to obtain the target holding material (3).

The holding material (3) thus obtained had a thickness (C) of 6.0 mm, and the content of the organic binder (solid content) was 13 parts by weight based on 100 parts by weight of the alumina fiber mat. This holding material (3) is equivalent to the clearance (D) 4
The pressure required to compress to 4.1 mm is 4.1 kg / cm ²
It was confirmed that the surface pressure when mounted on a catalytic converter designed to have a clearance of 4 mm, that is, the initial pressure at the time of mounting was 4.1 kg / cm ² .

Further, from the obtained holding material (3), the width is 20
A band (sample piece) having a length of 20 mm and a length of 150 mm is cut out, and the width is set to 20 mm and the span is set to 80 mm.
S-500 ") was used to measure the elongation and tensile strength of the sample piece under the conditions of a tensile speed of 5 mm / min., And the unit tensile strength and tensile elastic modulus were obtained (see table). The unit tensile strength and the tensile elastic modulus E can be obtained from the above formulas (II) and (III).

Next, a sample was cut from the obtained holding material (3) and then heated in an oven whose temperature was controlled at 800 ° C. for 1 hour to thermally decompose the binder. as a result,
The thickness (C) of the holding material (3) was restored to 15 mm, and the thickness restoration rate obtained by the above formula (I) was 2.5 times.

The holding material (3) whose thickness was restored was compressed to a thickness of 4 mm corresponding to the clearance (D). The pressure required to maintain the thickness equivalent to the clearance (D) was 4.0 kg / cm ² . Therefore, the obtained holding material (3) was used by mounting it on a catalytic converter designed to have a clearance (D) of 4 mm, and after the binder burned, it had a restoring surface pressure of 4.0 kg / cm ^2. It was confirmed that it could be fixed.

Next, the obtained holding material (3) (thickness (C)
A strip having a width of 80 mm and a length of 320 mm, and the monolith (1) is cut as shown in FIG.
After being wound around the outer peripheral surface of No. 2, the canning property was examined by setting it in a two-part metal casing (2) (clearance: 4 mm) having the structure shown in FIG. As a result, the cut band can be easily wound by closely adhering to the outer peripheral surface of the monolith (1), and also when set in the metal casing (2), the flange portion (21
It was confirmed that there was no protrusion or biting into (a) and (21b), and excellent canning property was exhibited.

[Examples 2 to 7] A base mat having a bulk density and a normal thickness (A) shown in the table was used, and a compressed thickness (B) shown in the table was used.
A holding material (3) having a thickness (C) was obtained by performing the same operation as in Example 1 except that the holding material (3) was compressed. The content of the organic binder (solid content) in the obtained holding material (3) was as shown in the table. The pressure required to compress the holding material (3) to the clearance (D), that is, the initial pressure, and the unit tensile strength and tensile elastic modulus measured by the same method as in Example 1 are shown in the table.

Further, a sample was cut from the obtained holding material (3), and the binder was pyrolyzed by the same method as in Example 1. The thickness recovery rate at this time and the pressure required to compress the holding material (3) whose thickness has been restored into the clearance (D), that is, the surface pressure after combustion, are also shown in the table.

Next, the canning property was examined by performing the same operation as in Example 1 except that the two-division type metal casing (2) having the clearance (D) shown in the table was used. The band can be easily wound by closely adhering to the outer peripheral surface of the monolith (1), and also when set in the metal casing (2), the flange portion (21
It was confirmed that there was no protrusion or biting into (a) and (21b), and that it exhibited excellent canning properties.

[Comparative Example 1] In the example described in Example 1, both sides of an alumina fiber mat impregnated with an organic binder solution are sandwiched by polyester nets having openings of 0.33 mm, and the outer side thereof is punched with two sheets. After pressing with a metal (hole diameter: 3.5 mm, opening ratio: 22.7%, thickness: 2.3 mm), pressing was performed while sucking from one surface side to compress to a compressed thickness (B) of 5.5 mm. Then, instead of drying while maintaining the compressed thickness (B),
When one polyester net and punching metal were removed and one side was opened and dried, a molded body having a thickness (C) of 13 mm and containing 13 parts by weight of an organic binder (solid content) was obtained (see table). .

Next, the obtained molded body (thickness (C) 13 m
As a holding material, the width is 80 mm and the length is 320 mm.
The strip was cut out, and it was tried to mount it in a two-division type metal casing (clearance: 4 mm) having the structure shown in FIG. However, such a bulky holding material is
It was difficult to wind around the outer peripheral surface of the monolith (1), and during the canning, the flanges (21a) and (21b) were squeezed out and caught too much, and could not be set in the metal casing (Table. See).

[0097]

[Table-1] ──────────────────────────────────── Base material Mat Compressed thickness Binder Retaining material Thickness Bulk density B (mm) Amount (parts by weight) Thickness Bulk density A (mm) (g / cm3) C (mm) (g / cm3) ──────────────── ───────────────────── Example 1 16 0.1 5.5 13 6.0 6.0 0.30 Example 2 16 0.05 5.5 5.5 20 6 0.0 0.16 Example 3 12 0.05 5.5 20 20 5.5 0.13 Example 4 35 0.05 0.05 3.0 17 3.5 0.60 Example 5 16 0.1 6.0 6.0 25 7.0 0.29 Example 6 16 0.1 6.0 25 25 7.0 0.29 Example 7 16 0.1 6.0 25 25 7.0 0.29 Comparative Example 1 16 0.1 5.5 13 13 0.14 ─────────────────── ──────────────────

[Table-2] ──────────────────────────────────── Clearance With wearing After burning with wearing After burning D (mm) Initial pressure Bulk density Restoring surface pressure Bulk density (kg / cm2) (g / cm3) (kg / cm2) (g / cm3) ────────────── ─────────────────────── Example 1 4.0 4.1 0.45 4.0 0.40 Example 2 4.0 0.5 0.24 0.9 0.20 Example 3 4.0 0.6 0.1 0.18 0.6 0.15 Example 4 3.0 6.9 0.70 9.8 0.58 Example 5 4. 0 5.0 0.50 4.3 0.40 Example 6 7.0 0 0.29 1.1 0.23 Example 7 6.5 0.3 0.31 1.5 0.25 Comparative Example 1 4.0 (Difficult to wear) ───────────────────────────── ──────

[Table-3] ──────────────────────────────────── Holding material thickness ratio Unit tensile strength Tensile modulus Thickness C / B A / C C / D (kg / cm2) (kg / cm2) Restoration rate ──────────────────────── ──────────── Example 1 1.1 2.7 1.5 24 550 2.5 2.5 Example 2 1.1 2.7 1.5 23 23 580 2.5 Example 3 1 0.0 2.2 1.4 19 390 2.2 Example 4 1.2 10 1.2 25 500 8.6 Example 5 1.2 2.3 1.8 34 610 2.1 Example 6 1. 2 2.3 1.0 34 610 2.1 Example 7 1.2 2.3 1.1 34 610 2.1 Comparative Example 1 2.4 1.2 3.3 -------- ──────────────────────────── ──

[0098]

EFFECT OF THE INVENTION Since the monolith holding material of the present invention and the monolith holding material obtained by the manufacturing method of the present invention are composed of a compressed body of alumina fiber having excellent durability, they are highly discharged from an internal combustion engine. There is no erosion or deterioration even when exposed to hot exhaust gas with a flow velocity, and the organic binder is thermally decomposed and disappears due to the hot exhaust gas, and its thickness is restored to exert elasticity, so that the monolith and metal It is possible to completely close the clearance of the manufactured casing to prevent the exhaust gas from leaking, and to stably hold the monolith with a predetermined force without being scattered even by the exhaust gas having a high flow rate.

Further, the monolith holding material of the present invention can follow the change in the clearance with time due to the temperature change of the monolith and the metal casing, and elastically fix the monolith in the metal casing. Since the thickness of the alumina fiber mat as the base material can be restored to the initial thickness, the monolith can be stably held for a long period of time.

Furthermore, the monolithic holding material of the present invention can be easily and easily held when the catalytic converter is assembled, since the thickness of the monolithic holding material is suppressed by the binding force of the organic binder and the thickness is kept thin. It can be installed without damage. Since the catalytic converter of the present invention uses the above-mentioned characteristic monolith holding material, it can withstand long-term use even under severe vibration or shock, and the monolith holding material can be easily attached. Therefore, it can be easily manufactured, and the cost at the time of manufacturing can be reduced.

[Brief description of drawings]

FIG. 1 is an assembled perspective view showing a catalytic converter as one embodiment of the present invention.

FIG. 2 is an assembled perspective view showing a winding procedure of a monolith holding material with respect to a monolith.

FIG. 3 is a schematic explanatory view showing a state change of an alumina fiber mat up to a monolith holding material.

[Explanation of symbols]

 1: Monolith 2: Metal casing 2a, 2b: Casing member 3: Monolith holding material 4, 5: Connection port A: Normal thickness of alumina fiber mat (base material mat) B: Thickness of compression mat C: Monolith Normal thickness of holding material D: Clearance

Claims (28)

[Claims] 1. A monolith that is formed in a tubular shape and carries an exhaust gas purification catalyst, a metal casing that houses the monolith and has both ends connected to an exhaust gas conduit, an outer peripheral surface of the monolith, and an inner surface of the metal casing. A monolith holding material used in a catalytic converter composed of a monolith holding material mounted in a clearance between the monolith holding material and the monolith holding material, wherein the monolith holding material is thermally decomposed in an alumina fiber mat compressed in a thickness direction. The first step of (I) impregnating the alumina fiber mat with the organic binder liquid is made by uniformly containing the organic binder that disappears by (II) in the thickness direction of the alumina fiber mat impregnated with the organic binder liquid. Second step of compressing, (III) Third step of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat Processed and third
The thickness of the monolith holding material obtained in the step is 1 to 1.5 times the compressed thickness in the second step, and when the organic binder is pyrolyzed, it has a thickness restoring property in both open states. Then
A monolithic holding material, wherein a restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 30 kg / cm ² . 2. The monolith holding material according to claim 1, wherein the content of the organic binder is 10 to 30 parts by weight based on 100 parts by weight of the alumina fiber mat. 3. The monolith holding material according to claim 1, wherein the thickness of the alumina fiber mat is 2 to 10 times the thickness of the monolith holding material. 4. The monolith holding material according to claim 1, wherein the restored surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² . 5. The thickness recovery rate in the open state on both sides is 2 to 10.
The monolithic holding material according to claim 1, which is double. 6. The monolith holding material according to claim 1, which has a bulk density of 0.1 to 0.5 g / cm ³ . 7. The unit tensile strength is 10 to 40 kg / cm ^2.
The monolith holding material according to claim 1. 8. A monolith formed in a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing containing the monolith and having both ends connected to an exhaust gas conduit, an outer peripheral surface of the monolith and an inner surface of the metal casing. A monolith holding material used in a catalytic converter composed of a monolith holding material mounted in a clearance between the monolith holding material and the monolith holding material, wherein the monolith holding material is thermally decomposed in an alumina fiber mat compressed in a thickness direction. The organic binder that disappears due to is uniformly contained, the compressed state is maintained by the organic binder, and the bulk density is 0.1 to 0.5 g / cm ^{3. When} the organic binder is thermally decomposed, both sides are opened. In 2
It has a thickness recovery rate of 10 to 10 times, and a recovery surface pressure in a compressed state of a thickness corresponding to the clearance is 0.5 to 30 k.
A monolith holding material characterized in that it is g / cm ² . 9. The monolith holding material according to claim 8, wherein the organic binder is at least one selected from the group consisting of acrylic rubber, nitrile rubber, carboxymethyl cellulose, polyvinyl alcohol, and acrylic resins not included in acrylic rubber. 10. The monolith holding material according to claim 8, wherein the content of the organic binder is 10 to 30 parts by weight based on 100 parts by weight of the alumina fiber mat. 11. The monolith holding material according to claim 8, wherein the thickness of the alumina fiber mat is 2 to 10 times the thickness of the monolith holding material. 12. The monolith holding material according to claim 8, wherein the restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² . 13. The unit tensile strength is 10 to 40 kg / cm.
9. The monolith holding material according to claim 8, which is ² . 14. A monolith having a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing containing the monolith and having both ends connected to an exhaust gas conduit, an outer peripheral surface of the monolith and an inner surface of the metal casing. A method for producing a monolith holding material used in a catalytic converter, comprising: a monolith holding material mounted in a clearance between the (I) bulk density of 0.05 to 0.20 g / cm ³
The first step of impregnating the alumina fiber mat of (1) with an organic binder solution that disappears by thermal decomposition, (II) compressing the alumina fiber mat impregnated with the organic binder solution to 1/2 to 1/15 in the thickness direction. Second step, (III)
A third step of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat,
When the organic binder is thermally decomposed, it has a thickness restoring property in a state where both sides are open, and a restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 30 kg /
The method for producing a monolith holding material is characterized in that it is cm ² . 15. A monolith formed in a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing containing the monolith and having both ends connected to an exhaust gas conduit, an outer peripheral surface of the monolith and an inner surface of the metal casing. In a catalytic converter composed of a monolith holding material mounted in a clearance between the monolith holding material and the monolith holding material, the organic binder that disappears by thermal decomposition is uniformly contained in the alumina fiber mat compressed in the thickness direction. And (II) the first step of impregnating the alumina fiber mat with the organic binder solution, (II) the second step of compressing the alumina fiber mat impregnated with the organic binder solution in the thickness direction, (II)
I) The thickness of the monolith holding material produced through the third step of removing the medium liquid of the organic binder liquid while maintaining the thickness of the compressed alumina fiber mat, and the thickness of the monolith holding material obtained in the third step is 1 to 1.5 times the compressed thickness of the second step,
Then, when the organic binder is thermally decomposed, it has a thickness restoring property in a state where both sides are opened, and a restoring surface pressure in a compressed state having a thickness corresponding to the clearance is 0.5 to 30 kg / cm.
Catalytic converter characterized by being ² . 16. The catalytic converter according to claim 15, wherein the thickness of the alumina fiber mat is 2 to 10 times the thickness of the monolith holding material. 17. The catalytic converter according to claim 15, wherein the thickness of the compressed aluminous fiber mat in the second step is larger than the clearance of the catalytic converter. 18. The catalytic converter according to claim 15, wherein the thickness of the monolith holding material is 1.0 to 2.0 times the clearance of the catalytic converter. 19. An initial bulk density of 0.18 to 0.8 when the monolith holding material is mounted on a catalytic converter.
The catalytic converter according to claim 15, wherein the catalytic converter has g / cm ³ . 20. The initial surface pressure of the monolith holding material mounted on a catalytic converter is 0 to 8 kg / cm ^2.
The catalytic converter according to claim 15, which is 21. When the organic binder is thermally decomposed, the restoring surface pressure of the monolith holding material in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² and 50 to 90% of the initial surface pressure. 16. The catalytic converter of claim 15, wherein. 22. When the organic binder is thermally decomposed, the restoring surface pressure of the monolith holding material in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² and 110 to 150% of the initial surface pressure. 16. The catalytic converter of claim 15, wherein. 23. A monolith having a tubular shape and carrying an exhaust gas purifying catalyst, a metal casing containing the monolith and having both ends connected to an exhaust gas conduit, an outer peripheral surface of the monolith and an inner surface of the metal casing. In the catalytic converter composed of a monolith holding material mounted in the clearance between the monolith holding material and the monolith holding material, the monolith holding material has a bulk density of 0.05.
˜0.20 g / cm ^{3 of} an alumina fiber mat is compressed in the thickness direction, and the mat contains an organic binder that disappears by thermal decomposition uniformly, and the organic binder maintains a compressed state. 0.1 to 0.5
It has a bulk density of g / cm ³ , and when the organic binder is decomposed, it has a thickness recovery rate of 2 to 10 times in the open state on both sides, and the recovery surface pressure in a compressed state with a thickness corresponding to the clearance. catalytic converter, characterized in that but a 0.5~30kg / cm ^2. 24. The clearance formed by the outer peripheral surface of the monolith and the inner peripheral surface of the metal casing is 1.0 to 1.0.
24. The catalytic converter according to claim 23, wherein a monolith holding material having a thickness of 2.0 times is mounted. 25. An initial bulk density of 0.18 to 0.8 when the monolith holding material is mounted on a catalytic converter.
24. The catalytic converter according to claim 23, wherein the catalytic converter is g / cm ³ . 26. The initial surface pressure of the monolith holding material mounted on a catalytic converter is 0 to 8 kg / cm ^2.
24. The catalytic converter according to claim 23. 27. When the organic binder is thermally decomposed, the restoring surface pressure of the monolith holding material in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² and 50 to 90% of the initial surface pressure. 24. The catalytic converter of claim 23. 28. When the organic binder is thermally decomposed, the restoring surface pressure of the monolith holding material in a compressed state having a thickness corresponding to the clearance is 0.5 to 8 kg / cm ² and 110 to 150% of the initial surface pressure. 24. The catalytic converter of claim 23.