JPS59519A - Packing for automobile exhaust gas purifier - Google Patents

Abstract

PURPOSE:To reduce the amount of noxious gas generated due to an organic bonding agent and improve the insertion and assemblying property of the titled packing by superimposing an organic fiber non-woven cloth on the surface of a sheet subjected to sheet-making and interwisting the non-woven cloth to the sheet subjected to sheet making. CONSTITUTION:About 0.55kg of a bulk-shaped ceramic fiber having an average fiber length of about 50mm., and an average fiber diameter of about 2.2mum, is put into about 100l of a beater for testing, and beaten for about five minutes without applying a load onto a beater edge to remove non-fiber parts sunk on the bottom of the beater and obtain about 0.4kg of a ceramic fiber pulp. The thus obtained pulp is mixed, fixed and converted into a sheet to obtain a vermiculite sheet A. On one surface or both surfaces of this sheet, an organic fiber non-woven cloth is superimposed and a non-woven cloth is inter-twisted with the sheet by needle punching.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a packing for an automobile exhaust gas purifier, and particularly relates to an improvement of a packing mainly made of vermiculite.

The sheet-like packing, which is mainly made of vermiculite, has excellent heat resistance against high temperatures and expands due to heat.
Due to its ability to expand (called expansion), it has attracted attention as a packing material for equipment that handles high temperatures.One of its uses is to support precious metal catalysts, as shown in Figure 1. Ceramic monolith type cylindrical catalyst body (1)
In an automobile exhaust gas purifier configured by housing a monolithic cylindrical catalyst body (1) in a metal cylindrical container (2),
It is used as a filling gasket (3) between the container and the cylindrical container. (4) is a wire net packing.

Conventionally, the vermiculite packing for automobile exhaust gas purifiers has been made by combining unexpanded vermiculite grains with inorganic fibers and an organic binder, and forming the mixture into a sheet.

In the purifier using this vermiculite packing, the excellent heat resistance and sealing performance due to thermal expansion of vermiculite are fully utilized;
Since an organic binder such as NBR binder is used as a binder, there is a drawback that a large amount of odorous and harmful gas is generated during the heat expansion treatment of the packing attached to the purifier.
Therefore, the place where the heating and expansion treatment is performed must be equipped with an exhaust system, which imposes restrictions on its use.

However, in the vermiculite packing described above, the use of an organic binder not only strengthens the bond between the unexpanded vermiculite particles and the reinforcing inorganic fibers, but also provides the paper sheet product with appropriate flexibility and strength. It is essential for this, and it cannot be replaced with an inorganic binder.

In addition, in order to attach the vermiculite sheet packing to the purifier, it is inserted into the container by wrapping it around a monolithic cylindrical catalyst body, but it does not slide as desired when inserted. It is difficult to insert and arrange the seal in the desired shape, and exhaust gas may leak from a seal defect due to insertion deformation.

The present invention provides a packing for an automobile exhaust gas purifier which is made by blending unexpanded vermiculite particles with inorganic fibers and an organic binder, in which the amount of harmful gases generated by the organic binder is greatly reduced, and moreover, the amount of harmful gas generated by the organic binder is greatly reduced. The main purpose of this invention is to provide a vermiculite gasket that can be easily installed.

In order to achieve the above-mentioned object, the present invention aims to solve the problem of harmful gas generation caused by the organic binder by reducing the amount of specific binder mixed with vermiculite and inorganic fiber material.
We have created a paper sheet that generates less harmful gas by a large amount compared to conventional products, and in order to reduce the strength of the paper sheet due to the reduction in the amount of organic binder used, we have developed a paper sheet that generates less harmful gas. The organic fiber non-woven fabric is superimposed on the paper sheet, and the non-woven fabric is interlaced with the paper sheet by needle punching, thereby compensating for the decrease in strength of the paper sheet, and at the same time, the non-woven fabric improves the ease of inserting the packing into the purifier. I'll try something that will improve it.

In the present invention, the organic binder used is preferably blended to a weight of 5% or less, and natural rubber, butyl rubber, ethylene rubber, vinyl acetate, etc. are suitable as the binder.

Next, this invention will be specifically explained with reference to the following examples and comparative examples.

Example A bulk ceramic fiber (L55klil) with an average fiber length of 50mm and an average fiber diameter of 2.2μ was placed in a 100AI test beater, and was heated without applying any load to the beater edge.
After beating for a minute and removing the unfibered material (chicotte) that settled at the bottom of the beater, 4 kg of ceramic fiber pulp was obtained, and 4 kg of vermiculite grains from Montana, North America were added to this.
(Tyler sieve 28-65 mesh) o, 6skI? , natural rubber (I, CS Levertex solid content 613%)
Add 0.04 kg and mix evenly, add a small amount of alumina sol and sulfuric acid band to fix the rubber emulsion, and form the slurry into a sheet using a 1 m x 0.35 m hand paper machine with a surface pressure of 10 kl! / cm” and dried to obtain a ceramic fiber vermiculite sheet (5) (see Fig. 2) with a thickness (without load) of ?

On the top surface of this sheet,
Unitika spunbond polyester fiber nonwoven fabric (B)
(80407, WTD)) and needle punched at a rate of 30 strokes/i, then the reverse side was turned over and treated in the same manner. The obtained expandable sheet was heated to 3300 square meters by I/R.
rL”, thickness 6-Oynm (under no load), 52 m
m (Oo5kg/cm" (under 0 surface pressure))

A 25m11L wide tape-shaped packing was cut out from this sheet, one side of the cylindrical monolith was wrapped with an Inconel wire net packing, and the other side was wrapped with an inflatable sheet packing, and the purifier was inserted into a cast iron catalyst container. A bench test was conducted for 200 hours with the engine running at full speed.

Comparative Example Bulk ceramic fibers with an average fiber length of 50 mm and an average fiber diameter of 2.2 μm, 55 ky were placed in a 1001 test beater and beaten for 5 minutes without applying any load to the beater edge. By removing the non-fiber content (shot) that sank to the bottom, α4 kg of ceramic fiber pulp was obtained, and this was mixed with vermiculite grains 4 (Tyler sieve 28-65 mesh) from Montana, North America [165 kg, NBR (Ni
pol 1571 manufactured by Nippon Zeon Co., Ltd., solid content 40%)
Add 292 kg and mix uniformly, add a small amount of alumina sol and sulfuric acid to fix the rubber emulsion, and form the slurry into a sheet using a 1WL x α55rrL manual papermaking machine with a surface pressure of 10kg/cIIL! The material is compressed and dried to obtain a ceramic fiber vermiculite sheet approximately 6 mm thick (without load). A tape-shaped packing with a width of 25 plates was cut out from this sheet, and as in the example, one side of the cylindrical monolith was covered with Inconel wire net packing.
A purifier with an expandable sheet packing wrapped around the other side and inserted into a cast iron catalyst container was installed in an automobile, and a bench test was conducted for 200 hours with the engine running at full speed.

The table below shows the measured values of the amount of harmful gas generated and the required amount of dilution air per gram of sample for each expandable sheet obtained in the Examples and Comparative Examples.

The measurement was carried out using the measuring device shown in FIG. That is, α0 is an air supply pump, η is N, a gas cylinder, (2) is a controller, (to) is a flow meter, '14 is a quartz glass tube, (to) is an electric furnace, (to) is a plastic bag, α is a gas sampling device, in which a sample (P
) and baked at a temperature of 450°C for 3 minutes under an air supply (or N gas) of 151/min, the gas generated from the sample was collected in a vinyl tube (2), and the gas was collected. It was taken out in a vessel and subjected to quantitative analysis.

The gases to be analyzed are HCN, CO, acrylonitrile, H(
There are 5 types: J, NH and
g> was calculated using the following formula.

Flowing air (or N, ) amount Vl/min decomposition/combustion time tm1n detection tube measurement value
a Molecular weight of harmful gas measured in ppm
M g1 mol sample weight WI
Weight of harmful gas generated from 1 g of sample I The accuracy of analysis of the amount of air required to dilute the harmful gas generated from 1 g of sample to the allowable concentration level is 1 to 2 digits.

In the above-mentioned bench test, gasoline is injected into cars assembled on the general assembly line, and then transferred to the tester line, at which point the gasket inside the purifier is heated for the first time, generating harmful gases. . The amount of harmful gas generated (expressed as the required amount of dilution air) is approximately 251 times the amount of gas used in the purifier! Therefore, it is calculated using the measured values in the table above. At that time, the car is warmed up (500 to 100
0 r-p-m), the engine exhaust gas amount is approximately 1 Nm
''/min, and the decomposition of the organic binder in the packing is completed in a few minutes. Therefore, the packing of the comparative example requires a large amount of dilution air in addition to the engine exhaust gas, whereas the packing of the comparative example requires a large amount of dilution air in addition to engine exhaust gas. In the case of packing, the amount is about 1/10 of that of the comparative example, and is not particularly required.In addition, since the exhaust gas emitted from the engine is purified by a purifier, there are few harmful gases.

Next, we will describe the experimental method and results of an insertability test into a purifier on tape-shaped packings cut from the expandable sheets obtained in the Examples and Comparative Examples.

Packing insertion test A cast iron catalyst container with an inner diameter of 107.2 mm s surface roughness was used, and a monolithic catalyst with an outer diameter of 102.9 m was placed at the lower end of the catalyst.
5 strength, areal density 3300. Wrap the inflatable sheet packing of Iil/♂ and push the monolith through an insertion jig with a tapered bottom shape. Since the shape of the catalyst container was complicated and the gasket attached to it could not be observed from the outside, a snowmaking method for measuring ventilation pressure drop as shown in FIG. 4 was used. (To) is the air pressure pump, α is the flow rate controller, Kan is the flow meter, Q
I) is a pressure gauge, (A) is a container, @ is a flange, (C) is a monolith catalyst body, (C) is a wire net packing, (2)
) is the sample inflatable sheet gasket, and (a) is the expanded polystyrene sheet gasket.

When the pressure loss was small in the above device, it was determined that the gasket was partially displaced and gas was leaking (no sealing performance). In a normal case, the internal pressure of the injected air shows 100 to 110 liters of water for an air injection amount of 4.5 J/min.

Test results: In the case of the packing covered with the polyester fiber non-woven fabric of the example, all (50 pieces) were normal, and in the comparative example, 50 pieces were normal.
In two of them, the differential pressure was less than 10 mm, and when the catalyst container was cut and the end face of the gasket was observed, it was confirmed that a part of the gasket was torn off.

In addition, regarding the pushing force when pushing the monolithic catalyst body wrapped only with the packing into the container, as shown in the measured values of the queen, the packing of the above example has much easier insertion than the comparative example. It was recognized that it was excellent.

Example 40-6011,9 (area specific gravity 35009
7m”) Comparative example 110-160kg (surface specific gravity 350
0g/m2) As stated above, according to this invention,
An organic fiber nonwoven fabric is superimposed on one or both sides of a sheet obtained by paper-making a compound consisting of unexpanded vermiculite particles, inorganic fibers, and an organic binder, and the nonwoven fabric is entwined with the sheet by needle punching. As a packing for an automobile exhaust gas purifier, a packing can be obtained which greatly reduces the amount of harmful gas generated due to the organic binder and has excellent insertion and assemblability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an automobile exhaust gas purifier, FIG. 2 is a partially cutaway perspective view of a packing showing an embodiment of the present invention, and FIG.
This figure is a block diagram of Packkin's harmful gas measuring device, and FIG. 4 is a block diagram of Packkin's ventilation pressure loss measuring device. (1)... Monolithic cylindrical catalyst body, (2)... Purifier container! , (3)...Filling gasket, (4)...
Wire packing, prisoner...inflatable sheet, (BL...
Inorganic fiber nonwoven fabric, αQ...Air supply pump, α9...
・N, gas cylinder, (2)...controller, (to)...
Flow rate needle, α metallurgy...quartz glass tube, αυ...electric furnace,
(a)...Plastic bag, Q71...Gas sampler, (
To)...Air supply pump, H...Flow rate controller, (A)...Flow meter, (C)...Pressure gauge, (A)...Container, Hanging...Flange, ( C)...Monolith M medium,
(c)...wire net packing, (e)...sample, (b)...gasket. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) An organic fiber nonwoven fabric is superimposed on one or both sides of a sheet obtained by paper-making a compound consisting of unexpanded vermiculite particles, inorganic fibers, and an organic binder, and the nonwoven fabric is made by needle punching. A gasket for an automobile ef1% gas purifier according to claim 1. (3) The organic binder contains natural rubber or acetic acid and 0% nitrogen. (4) The packing for an automobile gas purifier according to claim 1, wherein the organic fiber nonwoven fabric is made of polyester fiber.