KR920000788B1 - Expansion mat of exhaust gas purification equipment for automobile - Google Patents

Abstract

The mat is used for a catalytic converter to purify exhaust gas from engine in automobiles. The mat is made of 20-40 wt.% inorganic fiber with 4-6 mm length, 30-50 wt.% vermiculite, 5-20 wt.% perlite, 8-20 % latex and acrylates for bonding material, 0.5-5 wt.% silica-sol or alumina-sol for inorganic reinforcing material, and 1-5 wt.% inorganic bonding material.

Description

Expansion mat for exhaust gas catalytic purifier of vehicle

The present invention relates to an expansion mat for a catalytic purifier, which is used for purifying exhaust gas emitted from an engine of an automobile.

Looking at the structure of a general catalyst purifier, it is a honeycomb ceramic structure covered with an expansion mat and the outer circumference is covered with a metal case, and carbon oxide and hydrocarbon oxidation and nitrogen in the exhaust gas passing therein are reduced and purified. This oxidation and reduction of the nitrogen is to be carried out at a high temperature, in the case of an engine in operation, this reaction can be made because the exhaust gas of the high temperature is discharged, and the reaction state is maintained continuously In order to prevent the release of heat, an expansion mat having sufficient thermal insulation performance is installed on the outer circumference of the ceramic structure.

The expansion mat is subjected to shrinkage and expansion due to the difference in coefficient of thermal expansion occurring between the ceramic structure and the case after the installation, and to impact and vibration from the outside. Therefore, the mechanical resistance and the oxidation of gas and In order to maintain the thermal insulation performance for maintaining the temperature required for the reduction and to serve as a packing for preventing the leakage of unpurified gas having a different coefficient of thermal expansion, a soft expandable material is selected.

For this purpose, U.S. Patent Nos. 3,916,057 (heat absorbing sheet material), 4,305,992 (heat absorbing sheet material), 4,617,176 (heat absorbing sheet material), British Patent 1,513,808 (heat absorbing sheet material) The sheet material which is useful as a mounting means of an expansion mat is proposed.

The sheet metal of the foregoing prior arts is used as a rectangular mat wrapped around a honeycomb ceramic structure in a catalytic purifier. In particular, the contents of US Patent No. 4,305,992, 25-50% of inorganic fibers, 40-65% of the expandable material, 5-15% of organic and inorganic binders, and other additives by mixing the amount of coma 2-100 times by standard papermaking process technology It is supposed to produce an expansion plate. This product has been useful so far, but it does not take into account some of the problems encountered during use. That is, the soft expandable material is mounted between the metal case and the honeycomb ceramic structure, wherein the pressure, friction coefficient, shear modulus, and heat transfer coefficient of the soft expandable material applied to the ceramic structure may cause cracking of the ceramic structure. As a result, in severe cases, the ceramic structure may be completely split into two pieces.

In addition, the soft expansion plate has a volume coefficient of 12-18 Kpa at a temperature of 200-300 ° C. due to the low temperature foaming treatment due to ion exchange of vermiculite. Due to the mechanical vibration applied to the catalyst purification device before the expansion plate is expanded by the heat of the exhaust gas, the ceramic structure may be subjected to continuous vibration and may be damaged. In addition, when the internal temperature of the catalyst purifier is about 400 ° C., the force of the organic binder in the soft expandable material is extinguished, and the shape is maintained by the binding force of the inorganic fiber. However, when the temperature reaches 600 ° C, it is difficult to maintain the shape of the expansion mat by using only inorganic fibers, and separation or detachment of the fibers may occur, and in severe cases, cracks may occur in the expansion materials. To address these problems, U. S. Patent No. 4,617, 176 (endothermic sheet material) proposed a flexible mat called mat having a sinusoidal portion, which initially had good bearing capacity when mounted on a catalytic purifier. When the internal temperature of the catalytic purifier is higher than 600 ° C., it is difficult to maintain the shape of the expansion mat by inorganic fibers alone, but it is supported by the force of the wire mesh. Forming a thermal gradient and causing thermal stress has resulted in the damage of the ceramic structure and the problem that the unpurified gas leaks as it is.

Therefore, U.S. Patent No. 4,269,807 and German Utility Model No. 8,019,813 have been proposed, but they also have insufficient thermal insulation, failed to maintain fiber bonding at high temperatures, and insufficient packing to prevent outflow of unpurified gas. It was a condition. Therefore, recently published patent applications No. 89-9455 (catalytic converter for exhaust system and its particle filter) and No. 89-13319 (contact converter) have been proposed as the most advanced contents which have been proposed in recent years. Insert a metal screen, metal mesh, or metal mesh between the mat and remove the wrinkles to increase the volume coefficient in order to prevent breakage or dropping of the fibers and cracks in the expansion mat caused by thermal shock. Alternatively, the expanded layer mat and the non-expanded layer mat are doubled to seal at the sides.

However, they are complicated in the manufacturing process and the number of processes, there is a problem in productivity, and the pressure applied to the ceramic structural material due to the pressure applied during assembly to improve the volume coefficient at high temperature is unreasonable from the beginning. This will result in higher volumetric modulus at higher temperatures resulting in higher pressure on the ceramic structure, resulting in unimproved separation or separation of the fibers due to hot shrinkage and expansion of the case. In addition, since a metal screen or wire mesh having a different coefficient of thermal expansion is inserted into the expansion member, the adhesion to the fiber with the change of temperature will be weakened and will trigger the detachment of the fiber further.

In order to solve the problems of the prior art as described above, the present invention is to spun inorganic fibers and to strengthen the support of ceramic structures by promoting foamability at low temperatures. The light was ionized.

And in order to strengthen the bonding force between fibers at low temperature below 300 ℃ and to give flexibility, it was used by mixing an appropriate amount of latex and acrylates as an organic binder, it has a high volume coefficient at high temperature and is unreasonable to the ceramic structure Vermiculite pearlite was used in order to avoid stress, and bentonite, Xonotlite, Edenite, Calcium Silicate, Mica and Asbestos were used as inorganic binders. Alumina sol or silica sol is added as an inorganic bonding reinforcing material to prevent fiber decomposition and detachment at high temperature by combining with a).

In the present invention, as inorganic fibers, asbestos, hornblende asbestos, glass fibers, zirconia silica fibers, crystalline alumina fibers, alumina silicate fibers, etc. may be used, and 20-40% by weight is prepared and wet milled with a blender to make the fiber length 4-6mm. After mixing, the mixture is stirred with water corresponding to 20 to 80 times the total weight of the slurry.

As a result, after the sea surface is completed, 30-50% by weight of ion-exchanged vermiculite is added to 5-20% by weight of ion-exchanged pearlite. The ion exchanged vermiculite used in the present invention is an ammonium compound [NH ₄ H ₄ PO ₄ , (NH ₄ ) ₂ CO ₃ , NH ₄ C ₂ H ₃ O ₂ , NH ₄ OH, etc. in order to improve the expandability at low temperatures; It is used after ion exchange with Ina potassium compound [KC ₂ H ₃ O ₂ , KMNO ₄ etc.], which is completely foamed around 800 ℃, but since the pearlite starts foaming around 800 ℃, In order to form the volume coefficient at high temperature by dissolving compounds having polar ions such as Kt, NH ₄ ⁺ , Li ⁺ , and soaking for 10-15 hours to relax and relax, the foam was foamed at about 800 ℃. It is foamed around -650 ℃ (see Table 1).

TABLE 1

By utilizing these characteristics, when the expansion mat is mounted between the metal case and the ceramic structure to receive heat, all organic binders are burned at about 400 ° C., so that organic binder sites form voids.

In this case, the volume coefficient is lower than when it is first installed, and the inorganic fiber is decomposed or dislodged by mechanical force such as exhaust pressure, external shock, or vibration. In addition, the metal case is heated to a high temperature due to the deterioration of the thermal insulation effect, or is subjected to thermal shock due to the hot change of the ceramic structure. In the present invention, the problems of the present invention improve the initial support force at low temperature to improve the initial support force to prevent breakage caused by vibration or shock of the ceramic structure, to prevent hot change, to maintain the airtightness to prevent the leakage of gas and the strength of the inorganic binder This can prevent the fibers from falling off or falling off at high temperatures.

In the present invention, the primary factor in which the pearlite is thermal insulation at high temperatures, reinforcement of high-temperature bearing capacity, improvement of the volume coefficient, etc. is the forced increase of the volume modulus by the insertion of metal reinforcement, whereas the pearlite is 0.2-0.3 mm small particles before foaming. After being present at about 650 ° C, the shape changes while foaming into a hollow body of 1.0-1.5mm. That is, since it is a natural foaming material, even if foamed at a high temperature, it does not exert excessive force on the ceramic structure, and the inorganic binder is impregnated with silica sol or alumina sol to bind the inorganic fiber at high temperature, so that no fiber is separated or dropped.

In the present invention, as the organic binder, natural latex (Natual Rubber Latex), styrene-butadiene latex (Stylene-Butadiene Latex), butadiene-enrylonitrile Latex, Chlorroprene Rubber Latex, poly 8-20 weights of isoprenenet-acrylate rubber copolymer, acrylic rubber, ethyl acrylate copolymer, methacrylate polymer, etc. Inorganic binders include Bentonite, Xonotlite, Montmorillonite, Calcium Silicate, Mice, Asbestos Kaolin, etc. 1-5% by weight), and additionally 0.5-5% by weight of silica sol and alumina sol as binding reinforcing materials. In addition, some surfactants, foaming agents, flocculants, etc. may be used before making the inflator, and as the flocculant, an inorganic coagulant and an organic coagulant are used in parallel. The inorganic coagulant uses 5-15% by weight as the primary coagulant and a small mass It shows the phenomenon of aggregation, increasing the wet strength when forming a mat.

The organic coagulant is used as a secondary coagulant to use 2-10% by weight to induce a complete coagulation so that no residual fibers, organic or inorganic binders which are not coagulated in the first coagulation, are lost during dehydration. Such raw materials as described above are manufactured by a Magniny process or a standard papermaking process, and the expansion mat according to the present invention has a bearing capacity of the ceramic structure at high and low temperatures by ion exchanged vermiculite and pearlite. It is strong, and latexes, acrylates, and organic binders also enhance the bonding strength between expansion mat fibers, so it has excellent flexibility and excellent workability, and alumina sol and silica sol reinforce the bond between inorganic fibers at high temperature. It prevents the disintegration or detachment of the fiber, so that it is not damaged by vibration or shock applied during use, and thus it can maintain a long life, but it does not use a metal mesh, so there is no deterioration of insulation performance. According to the concrete description as follows.

Example 1

In this embodiment, 2000g of water is charged to a 5000ml container, and then 300g of CH ₃ COOK (potassium acetate) is added and stirred for about 15 minutes to dissolve the potassium acetate well.

Subsequently, 2000 g of vermiculite ore having a particle size of about 0.5 mm was deposited in the dissolved solution and maintained for about 10 hours, followed by dehydration and drying at 100 ° C.

Subsequently, 2000 g of water was filled in a container of 5000 ml, and then 300 g of CH ₃ COOK was added thereto, followed by stirring for about 15 minutes so that potassium acetate was dissolved well.

Subsequently, 2000 g of pearlite ore having a particle size of about 0.5 mm was deposited in the dissolved solution and maintained for about 10 hours, followed by dehydration and drying at 100 ° C. to prepare 265.2 g and 74.8 g of ion exchanged vermiculite and pearlite.

Next, 190.4 g of the ceramic fiber as an inorganic fiber was wet-decomposed with a mixer to adjust the fiber length to about 4-6 mm, and then mixed with 27 l of water corresponding to 40 times the total weight of the slurry and stirred. After the fiber is sponged in water, 265.2 g of the ion-exchanged vermiculite, 74.8 g of ion-exchanged pearlite, 60% Chloroprene Rubber Latex, and 40% Ethyl Acrylate are mixed. Add 120 g of emulsion, 27.2 g of Mica, and 20.4 g of alumina sol, and stir for about 10 minutes.

The raw materials are sufficiently mixed and then agglomerated with 120g of inorganic coagulant (1% concentration) and 27g of organic coagulant (0.1% concentration), and the density is 520-550kg / m3 by the standard papermaking method such as Magniny method or hand foam sheet. 600mm × 300mm × 5t

Example 2

In this embodiment, 204 g of ceramic fibers are wet pulverized with a mixer to adjust the fiber length to about 4-6 mm, and then mixed with 47 l of water corresponding to 70 times the total weight of the slurry, followed by stirring.

After the fiber is sponged in water, 292.4g of vermiculite ion-exchanged with 40.8g Chloroprene Rubber Latex ion-exchanged with the same process as Example 1, 40% ethylacrylate Emulsi on 108.8g, mica (Mica) 20.4g, 13.6g of alumina sol was added and stirred for about 10 minutes.

The raw materials are sufficiently mixed and then agglomerated with 140g of inorganic coagulant (1% concentration) and 30g of organic coagulant (0.1% concentration), and then the density is 620-650kg / m 3 by the same Magni method or standard papermaking method as in Example 1. A product having the same physical properties as in Example 1 was obtained as a product having a standard of 600 mm x 300 mm x 5 t.

Example 3

In the ball embodiment, 210.8 g of ceramic fibers are pulverized with a blender and adjusted to have a fiber length of about 4-6 mm, followed by mixing with 40 l of water corresponding to 60 times the total weight of the slurry.

After the fiber was removed from the water, 306 g of ion-exchanged vermiculite, 40 g of ion-exchanged pearlite, 60% of chloroprene rubber latex, and 40% of ethyl acrylate were prepared in the same manner as in Example 1. 115.6 g of mixed emulsion, 20.4 g of Mica, and 6.8 g of alumina sol were added thereto, followed by stirring for about 10 minutes.

The raw materials were sufficiently mixed and then agglomerated with 140g (1% concentration) of inorganic coagulant and 30g (0.1% concentration) of organic coagulant, and the density was 680-700kg / m 3 and 600mm × 300mm by standard papermaking method as in Example 1. A product having the same physical properties as in Example 1 was obtained as a product of x 5t.

Example 4

In this embodiment, 224.4 g of ceramic fibers are wet-pulverized with a blender as inorganic fibers, and the fiber length is adjusted to about 4-6 mm, followed by mixing with 54 l of water corresponding to 80 times the total weight of the slurry.

After the fiber was removed in water, the same procedure as in Example 1 was carried out in the same manner as in Example 1, 251.6g of vermiculite ion-exchanged, 54.4g of Chloroprene Rubber Latex ion-exchanged, and 40% of ethylacrylate. 115.6 g of mixed emulsion, 20.4 g of Mica, and 13.6 g of alumina sol are added thereto, and the mixture is stirred for about 10 minutes. The raw materials are sufficiently mixed and then agglomerated with 140g (1% concentration) of inorganic flocculant and 30g (0.1% concentration) of organic flocculant.Then, the density is 680-720kg / m3 and 600mm × 300mm by the same standard paper industry as in Example 1. A product having the same physical properties as in Example 1 was obtained as a product of x 5t.

Claims (1)

20-40% by weight of inorganic fibers having a length of 4-6 mm, 30-50% by weight of vermiculite and 5-20% by weight of pearlite, and 8-20% by weight of latexes and acrylates as organic binders, and silica sol An expansion mat for a catalyst for purifying exhaust gases in a vehicle comprising 0.5-5% by weight of inorganic binder reinforcing materials such as alumina sol and 1-5% by weight of inorganic binder.