JP2000352311A - Manufacturing method and usage of sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve anti-peeling performance between fiber layers through minimizing peeling during resin impregnation for homogeneous impregnation with resin, by sewing an inorganic short fiber laminated product with a continuous inorganic fiber thread to form a heat-resistant inorganic fiber compound impregnated with resin. SOLUTION: A spinning stock solution prepared by mixture of 60 wt.% alumina and 40 wt.%; silica, with a spinning auxiliary agent added thereto is put in a hollow disc having holes on a circumferential face, and applied with a centrifugal force for drying and solidifying the fiber forming stock solution scattering therefrom like fibers. The solidified precursor is stitched with a precursor of a continuous inorganic fiber thread. Then, the obtained continuous fiber thread sewn precursor mat is baked so as to produce a heat resistant inorganic fiber compound. Further, the compound is impregnated with a resin component, dried and solidified to obtain a sealing material 2. The sealing material 2 is wound around a catalyst carrier 1, with half-split metal shells 3, 4 covering outside thereof to form a catalyst converter. Therefore, the sealing material can be formed without using a special jig or costly process, peeling or displacement of the sealing material is not caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealing material for a catalytic converter, a method for producing the same, and a catalytic converter for purifying automobile exhaust gas using the same.

[0002]

2. Description of the Related Art Conventionally, a catalytic converter for purifying an automobile exhaust gas has been used to convert C contained in exhaust gas from an internal combustion engine.
O, it is widely used in internal combustion engine for a vehicle as to detoxify harmful components such as NO _x. Such a catalytic converter is mainly provided with a ceramic catalyst carrier and a metal shell that covers the outside of the catalyst carrier, and is disposed between the metal shells to prevent breakage of the ceramic catalyst carrier due to vibration and the like and to prevent leakage of exhaust gas. And an inorganic sheet layer.

In recent years, alumina fiber laminates have been widely used as an inorganic sheet layer from the viewpoint of coping with a high exhaust gas temperature for improving fuel efficiency and stability for use for a long time.

[0004]

However, in the alumina fiber laminate used as the inorganic sheet layer, separation between the fiber layers easily occurs inside the laminate, and it is assembled between the honeycomb catalyst carrier and the metal shell. For this purpose, it is necessary to use a special jig or perform special processing such as vacuum-packing the alumina fiber laminate with a film in advance to prevent peeling. In addition, there is also a problem that the catalyst carrier falls off from the inorganic sheet layer due to peeling between the fiber layers even during use after assembly.

As a means for preventing such peeling, a method has been proposed in which a precursor laminate before firing of alumina fibers is subjected to needle punching to obtain a blanket shaped body. Although it is said that this method can obtain a molded product having high strength, the peel strength was also as low as 1 g / cm ² or less in this method.

On the other hand, as a processing method for assembling the alumina fiber laminate between the catalyst carrier and the metal shell,
Generally, there is a method of impregnating the laminate with a resin to reduce the thickness of the laminate and then assembling the laminate. However, in this case, the conventional alumina-based fiber laminate has a problem that peeling is likely to occur when impregnating the resin. In addition, since the thickness is large and the water absorption is partially different, the resin is not uniformly impregnated, and there are portions where the adhesive force of the resin does not act, and it is difficult to keep the thickness small.

The present invention has been made in view of such a situation, and an object of the present invention is to reduce peeling during resin impregnation, perform uniform resin impregnation, and increase the peel strength between fiber layers. An object of the present invention is to provide a sealing material for a catalytic converter, which does not require a special jig and does not require costly processing, and maintains a stable holding force during use.

[0008]

That is, the present invention provides a catalytic converter characterized in that the inorganic short fiber laminate is made of a heat-resistant inorganic fiber molded article sewn with continuous inorganic fiber yarns and impregnated with a resin. Seal material.

In particular, in this sealing material, the composition of the inorganic short fiber laminate and the continuous inorganic fiber yarn is such that the alumina component 60
-100% by weight and 40 to 0% by weight of a silica component, and the number of sewn by continuous inorganic fiber yarns is at least 10 per 1m in the vertical direction and 1m in the horizontal direction of the inorganic short fiber laminate. Is what you do.

[0010] Further, the present invention provides a method for producing a heat-resistant inorganic fiber molded article in which an inorganic short fiber laminate is sewn with continuous inorganic fiber yarns. A method for producing a sealing material for a catalytic converter, which is characterized in that the material is sewn with a body and then fired, and in particular, a precursor of a continuous fiber yarn is characterized by being compounded with a reinforcing substance. Things.

Further, the present invention is characterized in that the sealing material for the catalytic converter according to the present invention is disposed between the catalyst carrier and a metal shell covering the outside of the catalyst carrier. Catalytic converter.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The inorganic short fiber laminate used in the present invention comprises:
For example, a viscous sol dispersion containing an alumina component and a silica component called a spinning dope and having a viscosity adjusted by a spinning aid such as an organic polymer is spun by a spinning method such as an extrusion method or a centrifugal method, and then spun. It can be obtained by firing the precursor of the short fiber laminate integrated in a certain area.
One example of the spinning method is a method in which a spinning solution is extruded as a liquid thread from a 0.1 to 1.0 mm nozzle, and dried and solidified by a dry air stream at 150 to 600 ° C., and the solution is collected by suction. At this time, by changing the mixing ratio of the alumina component and the silica component in the spinning dope arbitrarily, the desired alumina / silica component can be obtained.
An inorganic short fiber laminate having a silica ratio can be obtained. In the present invention, 60 to 100% by weight of the alumina component, 4
0 to 0% by weight, particularly 70 to 98% by weight of alumina component and 30 to 2% by weight of silica component are preferred.

The continuous inorganic fiber yarn used in the present invention can be obtained by spinning and firing a spinning solution having a higher viscosity than in the production of the above-mentioned inorganic short fiber laminate at a low speed and firing. It is a filamentary fiber with an infinite length. The composition of the continuous inorganic fiber yarn is 60 to 100% by weight of the alumina component, 40 to 0% by weight of the silica component, and particularly 70 to 98% of the alumina component.
% By weight, and 30 to 2% by weight of a silica component are preferred. The continuous inorganic fiber yarn is 1 m in the longitudinal direction and 1 m in the horizontal direction of the inorganic short fiber laminate.
It is preferable that the sewing is performed at a rate of at least 10 per m area.

In order to produce the sealing material of the present invention, the inorganic short fiber laminate may be sewn with continuous inorganic fiber thread, but a precursor of the inorganic short fiber laminate (unfired inorganic short fiber laminate) Alternatively, it is preferable to sew before firing using a precursor of continuous fiber yarn (unfired continuous inorganic fiber yarn), preferably both. In this case, the precursor of the continuous inorganic fiber yarn is reinforced with a high-strength continuous fiber such as glass fiber, carbon fiber, and organic fiber, an inorganic binder such as silica sol and alumina sol, and an organic binder such as polyvinyl alcohol and latex emulsion. It is preferable that they are complexed with a substance.

Sewing with continuous fiber yarn or its precursor is
As long as the continuous fiber yarn or its precursor remains in the inorganic short fiber laminate or its precursor, any method and apparatus may be used. For example, stitching with upper and lower threads, threading with only the upper thread, and the like can be adopted. Further, as a sewing device, for example, a quilting machine or the like is used, and a device in which sewing is performed with a sewing needle while continuously feeding an inorganic short fiber laminate or a precursor thereof with a roller is convenient.

The sealing material of the present invention is impregnated with a resin,
It is preferable that the entire volume is smaller than that of the sealing material before resin impregnation. The resin impregnation amount is preferably an amount capable of reducing the thickness of the sealing material by 10% or more by applying a compressive force, and the content is about 3 to 20% by weight, particularly about 4 to 10% by weight. . When impregnating the resin, it is preferable to use a vacuum.

Examples of the resin used in the present invention include acrylate latex, butadiene polymer latex, styrene / butadiene copolymer latex, carboxy-modified styrene / butadiene copolymer latex, acrylonitrile / butadiene latex, vinylpyridine •
Styrene / butadiene copolymer latex, polyvinyl chloride latex, chloroprene latex, polyvinyl alcohol and the like can be mentioned, and at least one of these is used.

In the catalytic converter for purifying automobile exhaust gas of the present invention, the sealing material of the present invention is disposed between a catalyst carrier and a metal shell covering the outside of the catalyst carrier. As the catalyst carrier, for example, a ceramic honeycomb made of cordierite, alumina, silicon carbide, silicon nitride or the like is generally used. The cross section of the metal shell is a cylinder or a half, such as an ellipse or a circle. In order to dispose the sealing material between them, in the case of a cylinder, a method of winding the sealing material around the outside of the catalyst carrier and integrating it and inserting it into a metal shell is adopted. In the case of a shell made of metal, the joint is welded.

When a resin-impregnated sealing material is used, the resin component is burned off by the heat of the exhaust gas, and the function of holding the catalyst carrier and the function of sealing the exhaust gas are exhibited.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 An aqueous solution of aluminum oxychloride as an alumina component and a silica sol as a silica component (Snowtex manufactured by Nissan Chemical Industries, Ltd.)
O), the two components are mixed so that the component ratio becomes 60% by weight of alumina and 40% by weight of silica, and polyvinyl alcohol is further added as a spinning aid to obtain a viscosity of 4,500.
A stock solution of cp was prepared.

The undiluted spinning solution is coated on a circumferential surface with a diameter of 0.5 mm.
Was placed in a hollow disk having a diameter of 250 mm provided with 300 holes, and by rotating the disk, the spinning stock solution was made fibrous by centrifugal force. The spinning stock solution that popped out as a fibrous form from the rotating disk was dried and solidified by hot air at 500 ° C. and laminated to obtain a precursor of an inorganic short fiber laminate.

The precursor of the inorganic short fiber laminate was sewn with a precursor of a continuous inorganic fiber yarn comprising 80% by weight of an alumina component and 20% by weight of a silica component using a quilting machine. The density of the sewing thread is determined by the lengthwise direction of the inorganic short fiber laminate.
m, 40 lines per 1 m ^{2 in} an area of 1 m in the horizontal direction.

Thereafter, the obtained continuous fiber thread sewing precursor mat was fired in a tunnel furnace at a temperature of 1250 ° C. to produce a spinel / mullite heat-resistant inorganic fiber molded article.
This heat-resistant inorganic fiber molded article had a thickness of 15 mm and a bulk density of 0.15 g / cm ² .

Next, a commercially available acrylic resin emulsion diluted 5 times with water is sprayed on the heat-resistant inorganic fiber molded article from above, and suction is performed from below to impregnate the resin component. Punching holes from top and bottom 7
It was sandwiched while being compressed so as to have a thickness of 1 mm, dried at 120 ° C. with a hot-air dryer while maintaining the clearance as it was, and the resin component was solidified to produce the sealing material of the present invention. The content of the resin component in the sealing material was about 6%.

Next, as shown in FIG.
Catalyst carrier 1 made of 0 mm cordierite honeycomb
The above-obtained sealing material 2 is wound around, and a metal shell having an inner diameter of 108 mm is halved on the outside of the sealing material 2,
4, and the joint of the metal shell was welded to produce a catalytic converter. At the time of assembling, peeling and displacement of the sealing material did not occur, and the appearance was excellent.

Thereafter, the evaluation was performed assuming the actual use of the catalytic converter. Evaluation conditions were as follows: After heating the catalytic converter at 400 ° C. for 1 hour, a vibration test was performed at 400 Hz for 100 hours.

As a result, in the catalytic converter, there was no peeling or damage of the sealing material, no displacement of the catalyst carrier from the sealing material, and no damage such as cracking of the catalyst carrier.

Example 2 An inorganic short fiber laminate was prepared by adding 100% by weight of an alumina component and α-
A sealing material was produced in the same manner as in Example 1 except that alumina was crystalline, and a catalytic converter was produced. as a result,
The result was as good as that of Example 1.

Comparative Example 1 The precursor of the inorganic short fiber laminate produced in Example 1 was fired in a tunnel furnace at 1250 ° C. to produce a spinel / mullite inorganic short fiber laminate. The thickness of the inorganic short fiber laminate was 40 mm, and the bulk density was 0.056 g / cm ³ . In the same manner as in Example 1, resin was impregnated to produce a sealing material, and an attempt was made to produce a catalytic converter.

As a result, when the sealing material was wound around the catalyst carrier, peeling occurred due to low peel strength between the fiber layers and uneven resin impregnation on the outer surface of the sealing material. Peeling was about 30 mm in width, 30 mm in length, and about 3 mm in depth, and completely peeled off from the sealing material. Therefore, the production of the catalytic converter was stopped.

Comparative Example 2 The precursor of the inorganic short fiber laminate produced in Example 1 was needle-punched at 50 strokes / cm 2 by a needling machine, and then fired at 1250 ° C. in a tunnel furnace.
A spinel / mullite short inorganic fiber laminate was produced.
This inorganic short fiber laminate has a thickness of 15 mm and a bulk density of 0.1 mm.
It was 15 g / cm ³ .

Using this as a sealing material, a catalytic converter was produced in the same manner as in Example 1, but a peeling crack having a width of about 20 mm, a length of about 10 mm, and a depth of about 2 mm occurred on the outer surface of the sealing material. Further, in the obtained catalytic converter, the catalyst carrier came off from the sealing material, hit the metal shell, and the catalyst carrier was damaged.

[0035]

According to the sealing material of the catalytic converter of the present invention, the peeling or displacement of the sealing material can be achieved without using a special jig or performing a costly process when assembling the catalytic converter. Thus, it is possible to provide a catalytic converter having a good finish.

According to the method for producing a sealant of a catalytic converter of the present invention, the sealant of the present invention having the above characteristics can be easily produced.

According to the catalytic converter of the present invention, there is provided a highly efficient and highly durable catalytic converter which does not cause peeling or damage of the sealing material and does not cause displacement or cracking of the catalyst carrier.

[Brief description of the drawings]

FIG. 1 is an exploded view showing a configuration of a catalytic converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Catalyst support 2 Sealing material 3 Half-metallic shell part 4 Other half-metallic shell part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 3/10 B01D 53/36 B F16J 15/10 C08L 101/00 F-term (Reference) 3G091 AA02 AB01 BA07 BA39 GA06 GB01X GB01Z GB10X GB10Z GB16Z GB17X GB19Z HA27 HA28 HA29 HA31 3J040 AA01 AA13 BA01 EA16 FA20 HA01 HA06 HA15 4D048 AA06 AA13 AA14 AB05 BB02 CA01 CC04 CC06 4H017 AA04 AA18 AB01 AB10 AC17 DE011 AC04 FB016 FB017 FB266 FB267 GF00 GJ02 GN00

Claims (6)

[Claims] 1. A sealing material for a catalytic converter, wherein an inorganic short fiber laminate is formed of a heat-resistant inorganic fiber molded article sewn with continuous inorganic fiber threads and impregnated with a resin. 2. The sealing material according to claim 1, wherein the composition of the inorganic short fiber laminate and the continuous inorganic fiber yarn is 60 to 100% by weight of an alumina component and 40 to 0% by weight of a silica component. 3. The sealing material according to claim 1, wherein the number of sewn by the continuous inorganic fiber thread is at least 10 per 1 m in the vertical direction and 1 m in the horizontal direction of the inorganic short fiber laminate. 4. The method for producing a sealing material according to claim 1, wherein a precursor of the inorganic short fiber laminate is sewn with a precursor of a continuous fiber thread and then fired. 5. The method for producing a sealing material according to claim 4, wherein the precursor of the continuous fiber yarn is compounded with a reinforcing substance. 6. A vehicle exhaust, wherein the sealing material for a catalytic converter according to claim 1 is disposed between a catalyst carrier and a metal shell covering the outside of the catalyst carrier. Catalytic converter for gas purification.