BRPI0608162A2 - Pollution control element mounting member, and, Pollution control device - Google Patents

Abstract

A pollution control element mounting member, suitable for mounting a pollution control element within a housing of a pollution control device. The pollution control element mounting member comprises a mat of a fibrous material having a predetermined thickness, with the mat having a combination of at least two types of binders having different glass transition temperatures (Tg) impregnated therein.

Description

"POLLUTION CONTROL ELEMENT ASSEMBLY MEMBER, POLLUTION CONTROL DEVICE, AND EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE"

FIELD OF INVENTION

The present invention relates to a pollution control element retaining or mounting member and, more particularly, the present invention relates to a retaining or mounting member for a pollution control element, such as a catalyst vehicle and a pollution element. filter. In particular, the present invention relates to a retaining or mounting member of a catalyst vehicle which exhibits good operability during insertion of the catalyst vehicle mounting member in a state of being wrapped around a catalyst vehicle within a catalytic converter housing. which is excellent in thermal resistance, an area pressure retention property and abrasion resistance, and also that, despite the reduction in the amount of impregnation of the organic binder used, the reduction in air pressure and shedding of the broken fibers, particles and others may be simultaneously avoided. Furthermore, the present invention relates to a pollution control device provided with such a pollution control element mounting member, more particularly a catalytic converter having such catalyst vehicle mounting member and an exhaust cleaning device provided therewith. a retaining member or filter element assembly. The catalytic converter of the present invention may be advantageously used to treat exhaust gases from internal combustion engines of, for example, power generators, automobiles and other vehicles.

BACKGROUND OF THE INVENTION

Exhaust gas purification systems, for which ceramic catalytic converters are used, have been known to remove carbon monoxide (CO), hydrocarbons (HC), nitrogen oxide (NOx) and the like contained within the gases. exhaust systems of the internal combustion engines of automobiles. A ceramic catalyst catalyst includes, for example, a beehive shaped ceramic catalyst vehicle (also called a "catalyst element") contained within a metal housing, namely a housing.

As is well known, there are many types of catalytic converter. However, a ceramic catalytic converter is usually structured with a gap between the housing and the catalyst vehicle packed in it. This gap is sufficiently filled with a thermal insulating mounting member, typically formed of inorganic fibers, organic fibers and / or generally a combined liquid or pasty organic binder. See, for example, Japanese Unexamined Patent Publications (Kokai) Nos. 57-61686; 59-10345 and 61-239100. As a result, the mounting / thermal insulating member filling such gaps retains the catalyst vehicle and may prevent the catalyst vehicle from experiencing accidental mechanical shocks caused by impact, vibration or the like. Because neither destruction nor movement of the catalyst vehicle occurs within the catalytic converter having such a structure, the catalytic converter may perform the desired functions over a long period of time. In addition, if impregnated within or coated on inorganic fibers, the organic binder may prevent spillage or scattering of broken particles, similar powders (hereinafter also referred to as "fiber pieces") of the inorganic fibers and may also prevent deformation of the catalyst vehicle when Catalyst vehicle is inserted (this operation is called "canning") into the box. In addition, because such a heat insulation / insulating member, as mentioned above, has a function of melting a catalyst vehicle, it is commonly called a retaining member or catalyst vehicle assembly.

Fig. 1 is a perspective view of the catalytic converter for exhaust gas purification described in Japanese Unexamined Patent Publication (Kokai) No. 7-269334. By employing catalytic converter 201, it is possible to simultaneously achieve improvement in the catalyst vehicle canning and the prevention of spillage of fiber pieces by providing a vacuum-coated catalyst vehicle using an air impermeable foil. The catalytic converter can be produced by the method in which a layer of fibrous inorganic non-woven plate-like cloth 231 and a sealing material 932 are contained in an air impermeable sheet 232, a pressure in an inner section of the sheet 232, the pressure within a sheet. The inner section of the sheet 232 is reduced to reduce its thickness, thereby adjusting a mass density of the inorganic fibrous nonwoven cloth layer 231 to 0.10 to 0.40 g / cm and also its thickness to approximately 1.0 to 2. 5 times the gap between catalyst support 204 and wrap 202 (upper wrap 221, lower wrap 222) obtained in their assembly, sheet 232 is sealed and then the inorganic fibrous nonwoven cloth layer 231 and sealant 932 sealed under the reduced pressure are inserted between the catalyst support 204e and the wraps 221 and 222, followed by mounting these members under pressure application. This catalytic converter is advantageous in that it can prevent spillage of fiber pieces without employing an organic binder, however, since a vacuum guarding system is required, the specified production apparatus must be used in conjunction with the embarrassing and increased production costs. In addition, since the connection system for upper wrap 221 and lower wrap 222 is flange-based, production operability is reduced compared to the pressurized insertion method, wherein the vehicle catalyst is inserted into a cylindrical housing. after a catalyst vehicle holding member is wrapped around and integrated with an external catalyst vehicle surface.

In addition, Fig. 2 is a perspective view of the exhaust gas purification catalytic converter described in Japanese Unexamined Patent Publication (Kokai) No. 2002-4848. Catalytic converter 300 is characterized by having a retention and sealing material 302 between a catalyst vehicle 301 and a wrap 395. The retention and sealing material 302 comprises an inorganic fiber mat-like product and has added 0.5 to 20% by weight of A binder consisting of an organic or inorganic binder and also its packing density, determined after assembly, shall be adjusted to 0,1 to 0,6 g / cm. In addition, the catalytic converter is characterized by the division of its retaining and sealing material 302 into three sections (upper sections 311, middle section 312 and lower section 313) in the thickness direction, the upper and lower sections each having a high solid content. doagglutinant compared to the middle section. However, for this catalytic converter, since the retention and sealing material has to be divided into three sections together with the control of the agglutinating solids content of each section, the production process is embarrassing and also the production cost is increased. In addition, while the organic binder will have to be added in an amount of 0.5 to 20% by weight, as described above, it is generally desired to reduce an amount of organic binder to meet the recent requirements of the advanced automotive internal engine control system. , because an increased amount of organic binder may adversely affect such a control system, especially the function of the sensor contained therein.

SUMMARY OF THE INVENTION

As described above, the catalyst carrier retaining or mounting members, commonly used in the form of mats, have been differently improved in catalytic converters, including having a padded structure, wherein the catalyst carrier is inserted under pressure application. However, vehicle catalyst assembly members may still suffer from problems associated with their structures, production processes and characteristics. An important problem is simultaneously to avoid reducing the area pressure or compressive strength of the assembly members and spilling or scattering the broken particles, powders and other fibers (pieces of fiber), while reducing the amount of organic binder used for joining or fixing purposes.

Accordingly, an object of the present invention may be to provide a catalyst vehicle mounting member which exhibits good operability during insertion of the catalyst vehicle mounting member in a state of being wrapped around a catalyst vehicle within the housing of a catalytic converter, which is excellent. in thermal resistance, an area pressure retention and abrasion resistance property, as well as a reduction in the area pressure of the fiber breakdown and spillage member, despite the reduced amount of impregnation of the organic binder used for fixation purposes.

In addition, another object of the present invention may be to provide a catalytic converter having a simple structure, which can be easily produced and wherein the vehicle catalyst mounting member is of excellent thermal resistance, has an area pressure retention property, spill prevention. fiber pieces and erosion resistance.

In addition, other objects of the present invention may be to provide a pollution control element mounting member for mounting pollution control elements other than the catalyst vehicle, such as, for example, a filter element and the like and a pollution control device provided with it. with such pollution control element.

In one aspect, the present invention resides in a member of the pollution control element assembly for retaining a pollution control element within a box by winding the pollution control element assembly around the pollution control element, in a that the pollution control element mounting member is composed of a mat of a fibrous material having a predetermined thickness and the mat has impregnated therein a combination of at least two types of binders having different glass transition temperatures (Tg).

Additionally, in another aspect, the present invention provides a pollution control device comprising a box, a pollution control element provided within the box and a pollution control element assembly disposed between the box and the control element. pollution, the pollution control element mounting member being the pollution control element mounting member described above in accordance with the present invention.

The pollution control element and the pollution control device according to the present invention may each advantageously be realized in various embodiments. For example, in a preferred embodiment of the present invention, the pollution control element is a catalyst vehicle and thus the pollution control device is a catalytic converter. In another preferred embodiment of the present invention, the pollution control element is a filter element (e.g., a particulate filter for diesel engines) and thus the pollution control device is an exhaust cleaning device. The pollution control device can be used in the automotive exhaust system and other internal combustion engines (eg, gasoline, diesel and other organic fuel combustion engines). As will be explained in detail below, according to the present invention, it makes It is possible to provide a catalyst carrier mounting member, which exhibits good operability when the catalyst vehicle mounting member, in a state of being wrapped around a catalyst vehicle, is inserted into a catalytic converter housing which is excellent in thermal resistance. , an area-retaining property, prevention of fiber spill and abrasion resistance, and in addition, an amount of impregnation of the organic binder used for fixing purposes can be reduced, while reducing an area pressure and spilling of broken particles. , powders and other fibers can be avoided simultaneously.

Further, according to the present invention, it is possible to provide a catalytic converter having a simple and easily producing structure, wherein the inserted vehicle catalyst mounting member is excellent in thermal insulation, area pressure-retention property, prevention of spillage of fiber pieces and erosion resistance.

Additionally, according to the present invention, it is possible to provide catalytic converters which can be advantageously used to treat exhaust gases from internal combustion engines of automobiles and other vehicles.

In addition, according to the present invention, it is also possible to realize the excellent effects described above in other pollution control devices than the catalytic converter, for example diesel particulate filters and other exhaust cleaning devices.

The objectives described above and other objectives of the present invention will be readily understood by the following descriptions.

REVE DESCRIPTION OF THE DRAWING Fig. 1 is a perspective view showing a structure of prior art catalytic converters for exhaust gas purification.

Fig. 2 is a perspective view showing another structured prior art catalytic converters for exhaust gas purification.

Fig. 3 is a side view showing a preferred catalytic converter structure for exhaust gas purification according to the present invention.

Fig. 4 is a cross-sectional view taken along line A-A of the catalytic converter of Fig. 3.

Fig. 5 is a graph showing the results of fiber spill determination in the impact test with respect to the acrylic latex impregnated catalyst vehicle mounting member having different Tg.

Fig. 6 is a graph showing the results of the area pressure determination at room temperature with respect to the assembly member of catalyst vehicle impregnated with different acrylic latex Tg.

Fig. 7 is a graph showing the relationship between fiber shedding and area pressure at room temperature with respect to a catalyst vehicle assembly simultaneously impregnated with acrylic latex having different Tg.

DETAILED DESCRIPTION OF MODES FOR CARRYING OUT THE INVENTION

The pollution control element mounting member and the pollution control device according to the present invention may be practiced in various embodiments. For example, the pollution control element may be a catalyst vehicle (or catalyst element), a filter element (for example, engine exhaust and other cleaning filters) or any other pollution control elements. Similarly, depending on a pollution control element applied thereon, the pollution control device may be a catalytic converter, an exhaust cleaning device such as an engine exhaust cleaning device (eg diesel particulate filter device) or any other devices. pollution control In the following, embodiments of the present invention will be described particularly with reference to the vehicle catalyst mounting member and catalytic converter, however it should be noted that the present invention is not limited to only the following embodiments.

The catalytic converter according to the present invention may be particularly advantageously used to treat exhaust gases from automobile and other internal combustion engines. The catalytic converter comprises at least one housing and one catalyst vehicle (element catalyst) disposed within the housing. The catalyst vehicle mounting member according to the present invention which will be explained in detail below is inserted between the housing and the catalyst vehicle so that the catalyst vehicle mounting member is wrapped around the outer peripheral surface of the catalyst vehicle. In addition, as is accomplished in the production of prior art catalytic converters, a catalyst vehicle and a catalyst vehicle mounting member may be joined together with a bonding means, such as a pressure sensitive adhesive or adhesive tape. However, for the catalytic converter of the invention, because the catalyst vehicle mounting member itself may exhibit adequate adhesion, insertion of the bonding medium, which makes structure and production complicated and increases the cost of production, is unnecessary. In addition, although the catalyst vehicle mounting member is usually wrapped around a substantially entire surface of the catalyst vehicle, if desired, it may be wound only on a portion of the catalyst vehicle. Additionally, securing means, such as a wire mesh, may optionally be used auxiliaryly.

It is preferred that the catalyst vehicle mounting member is suitably compressed so that it can provide proper mass density when inserted into the housing. Compression procedures include jaw bucket compression, fill compression, Turnikit compression, and others. The catalyst mounting member of the present invention may be advantageously used for producing a catalytic converter having a so-called padded structure, which is formed by a procedure such as fill compression, for example, by pushing the catalyst mounting member under pressure into a cylindrical box.

The catalytic converter of the present invention may include different types of catalytic converters. Preferably, the catalytic converter is equipped with a monolithically formed catalyst element, i.e. a monolithic catalytic converter. Because the catalytic converter is composed of a catalyst element having small passages, each having a beehive shaped cross section, which is smaller compared to the prior art pellet catalytic converters, they can suppress the exhaust gas resistance while adequately securing an area. contact with the exhaust gases, thereby enabling the treatment of the exhaust gases more efficiently.

The catalytic converters of the present invention may usefully be used to treat exhaust gases in combination with different types of internal combustion engines. In particular, catalytic converters can adequately exhibit their excellent functions and effects when mounted on car exhaust systems, such as passenger cars, buses and trucks.

Fig. 3 is a side view showing a typical example of the catalytic converter according to the present invention, wherein the main part of the converter is illustrated with the cross section for easy understanding of the structure. In addition, Fig. 4 is a cross-sectional view of the catalytic converter of Fig. 3 taken along line AA.As understood by these figures, a catalytic converter 10 is equipped with a metal housing 4, a monolithic solid catalyst vehicle 1 disposed within the metal housing 4 and a catalyst vehicle mounting member 2 of the present invention disposed within the metal housing 4 and a catalyst vehicle mounting member 2 of the present invention disposed between the metal housing 4 and the catalyst vehicle 1. It is explained in detail below that the catalyst vehicle mounting member 2 is composed of a mat of a fibrous material having a predetermined thickness and the mat is characterized by being impregnated with a combination of at least two types of binders, for example latex acrylic having different temperatures. of glass transition (Tg). An exhaust gas inlet 12 and an exhaust gas outlet 13, each having a truncated cone format, are attached to the catalytic converter 10.

As explained above, for the catalytic converter 10 of the present invention, it is fundamentally unnecessary to use greasing means such as an adhesive agent and a pressure sensitive adhesive sheet between the catalyst vehicle and the catalyst vehicle mounting member 2. However, such coupling means may be usefully used if it does not adversely affect the functions and effects of the invention and greatly improves the adhesion between catalyst vehicle and vehicle catalyst mounting member 2 and the effect of promoting canning operation can be expected. Usually, the binding means is preferably partially used. In addition, although a protective coating is generally required, the catalyst vehicle mounting member 2 may have a protective coating to protect the surface from damage.

Being particularly explained, the solid catalyst vehicle within the housing is usually composed of a ceramic catalyst vehicle having a honeycomb structure with a plurality of exhaust gas passages. The catalyst vehicle mounting member of the present invention is applied by wrapping it around the catalyst vehicle. The catalyst vehicle retention or mounting member retains the catalyst vehicle within the metal housing and seals the gaps formed between the catalyst vehicle and the metal housing and functions as a heat insulating member. As a result, the catalyst vehicle mounting member may prevent exhaust gases from deviating from the catalyst vehicle or at least inhibit such unwanted flow to the minimum level. In addition, the catalyst vehicle can be firmly and classically supported within the metal case.

In the catalytic converter of the present invention, the metal housing may be prepared from various metallic materials which are known to those skilled in the art in any arbitrary shape according to suitable functions, effects and the like. A suitable metal housing is made of stainless steel and has a shape as shown in Fig. 3. Of course, a metal housing having a suitable shape may optionally be made of metal such as iron, aluminum, titanium or an alloy of these metals.

Similar to the production of the metal housing, the solid catalyst vehicle may be produced from a material that is similar to that in a similar shape to that used in the production of conventional catalytic converters. Suitable catalyst vehicles include those known to those skilled in the art and made of metal, ceramic and similar. Usable catalyst vehicles are described, for example, in U.S. Reissue Patent No. 27,747. In addition, ceramic catalyst vehicles are commercially available, for example, from Corning Inc. in the US. For example, a beehive-shaped ceramic catalyst vehicle is available from Corning Inc. under the trade name "CELCOR" and another is available from NGK Insulated Ltd. under the trade name "HONEYCERAM". Metal catalyst vehicles are commercially available, for example, from Behr GmbH and Co. of Germany. Note that detailed explanations of catalyst monoliths can be found, for example, in SAE Techn. Paper 900.500, "System Approachto Packaging Design for Automotive Catalytic Converters" by Stroom et al.; SAE Techn. Paper 800.082, "Thin Wall Ceramics as Monolithic CatalystSupport" by Howitt; and SAE Techn. Paper 740,244, "Flow Effect in Monolithic Honeycomb Automotive Catalytic Converter" by Howitt et al.

The catalysts to be supported on catalyst vehicles explained above are usually metals (eg, platinum, ruthenium, osmium, rhodium, iridium, nickel and palladium) and metal oxides (eg vanadium pentoxide and titanium dioxide) and are preferably used in the form of coatings. Note that the detailed explanation of catalyst coating may be found, for example, in U.S. Patent 3,441,381.

In the practice of the present invention, the catalytic converter may optionally be produced in various structures and by various methods, provided that the production does not deviate from the scope of the present invention. The catalytic converter can be fundamentally produced by accommodating, for example, a beehive-shaped ceramic catalyst in a metal case. In addition, it is particularly suitable for a catalyst layer (catalyst coating) composed of a noble metal, such as platinum, rhodium or palladium, to be supported by a beehive-shaped ceramic monolith to provide a final catalyst vehicle (element catalyst). Use of this production process can manifest effective catalytic action at relatively high temperature.

In accordance with the present invention, the catalyst vehicle mounting member of the invention is disposed between the metal housing and the catalyst element. The catalyst vehicle mounting member is composed of a mat, blanket or the like of a fibrous material having a predetermined thickness. The catalyst vehicle mounting member may be formed of one member or may be formed of two or more members by lamination or joining of the members. It is usually advantageous for the catalyst vehicle mounting member to have a shape such as a track or blanket, in view of the handling property, however, the catalyst vehicle mounting member may optionally have other shapes. The size of the catalyst carrier member may be varied over a wide range according to its use and the like. For example, when a track-shaped vehicle catalyst mounting member is inserted into an automotive catalytic converter, the catalyst vehicle mounting member usually has a belt thickness of about 1.5 to 15 mm, a width of about 200 to 500 mm. mm and a length of about 100 to 1500mm. Such catalyst vehicle mounting member may optionally be cut with scissors, a cutter or the like to achieve desired shape and size.

The catalyst vehicle mounting member is preferably formed of an inorganic fibrous material, more preferably an inorganic fibrous material containing dealumin fibers. In addition, while the inorganic fibrous material may comprise a combination of two or more types of alumina fibers, another inorganic material may be used in combination with the alumina fibers to form the desired catalyst carrier assembly member. Examples of usable inorganic material include desily fibers, glass fibers, bentonite, vermiculite and graphite, although examples are not limited to those materials mentioned above. These inorganic materials may be used alone or at least two types of inorganic materials may be mixed for use in combination.

The inorganic fibers forming the catalyst carrier member preferably comprise inorganic fibers containing alumina (Al 2 O 3) and silica (S 1 O 2). The inorganic fibers used herein comprise two components of alumina fibers and silica fibers and the mixing ratio of alumina fibers to silica fibers is preferably from about 40:60 to 96: 4. When the mixing ratio of alumina fibers to silica fibers is outside the above range, for example, the mixing ratio is less than 40%, inconvenience such as deterioration of thermal resistance occurs.

Although there is no specific limitation on the thickness (diameter) of inorganic fibers, they have an average diameter of about 2 to 7 μηι. When inorganic fibers have a diameter smaller than about 2 μηι, the fibers are likely to become brittle and have insufficient strength. In contrast, when inorganic fibers have an average diameter greater than about 7 μιη, the catalyst carrier member tends to be difficult to form.

Furthermore, there is no specific limitation on the length of inorganic fibers, similar to their thickness. However, inorganic fibers suitably have an average length of about 0.5 to 50mm. When the average length of the inorganic fibers is less than 0.5 mm, the effect of forming the vehicle catalyst mounting member in which the inorganic fibers are used cannot be achieved. Conversely, when the length exceeds about 50 mm. mm, it becomes difficult to produce the catalyst vehicle mounting member in the soft process, because the handling property of inorganic fibers becomes weak.

Alternatively, in the practice of the present invention, an alumina fiber mesh mainly composed of an alumina fiber laminate sheet may be advantageously used. For such a alumina fiber mat, the average length of the alumina fibers is usually about 20 to 200 mm and the thickness (average diameter) of the fibers is usually about 1 to 40 μιη. In addition, the alumina fibers preferably have a mullite composition having a weight ratio of Al 2 O 3 / S 1 O 2 of about 70/30 to 74/26.

The above-described alumina fiber mat may be produced from a stock spinning solution composed of a mixture of, for example, an alumina source such as aluminum oxychloride, a silica font such as silica sol, an organic binder such as polyvinyl alcohol and water. That is, a spun aluminum fiber precursor is laminated to form a sheet, which is then preferably needle punched. The punctured sheet is usually cooked at temperatures as high as about 1000 to 1300 ° C.

The aforementioned needle punching usually has the effect of orienting part of the fibers vertically to the laminated surface. Part of the alumina fiber precursor within the sheet thus penetrates the sheet and is oriented vertically to securely tie the sheet. As a result, the specific weight of the sheet is increased and adhesion and shifting between the layers is avoided. Although needle punching density can be widely varied, it is usually from about 1 to 50 punctures / cm. The thickness, excess specific weight and belt resistance are adjusted by the needle punch density.

In the production of the alumina fiber mat, as explained above, ceramic fibers other than alumina fibers and inorganic expansive materials may optionally be added to the alumina fibers. In this case, although additives may be uniformly mixed with the mat, they may also be added so that they are localized while the parts to be heated are being particularly avoided. Additives can thus be added at low cost while the properties of the additives are being maintained. Examples of ceramic fibers include silica fibers, glass fibers and the like and examples of inorganic expansive material include bentonite, expansive vermiculite, and similar expansive graphite.

The catalyst vehicle mounting member according to the present invention is preferably produced by a dry process. This contrasts with the conventional catalyst vehicle mounting members, which were produced by a wet process (including each step of mixing inorganic fibers and organic fibers; opening inorganic fibers; preparing a sludge; shaping by a papermaking procedure; and compressing to form a shaped body). The dry process may be conducted fundamentally using any of the well known conventional methods. Typically the drying process using needle punch etc. is advantageous as explained above.

As described above, the catalyst vehicle mounting member of the present invention is composed of a mat of a fibrous material having the predetermined thickness which is inserted between a housing and a catalyst vehicle inserted into the housing while the belt is wrapped around the outer peripheral surface. of the catalyst vehicle. The belt-like catalyst vehicle assembly member is characterized by being impregnated with at least two types of binders having different glass transition temperatures (Tg) together according to the present invention.

In the practice of the present invention, a wide variety of conventional binders may be used to join and secure the fibrous material. Suitable examples of the binder include naturally occurring or synthetic polymeric material such as resinous material, e.g., debutadiene-styrene resin, polystyrene resin, polyvinyl acetate and acrylic resin or an organic material such as polyvinyl alcohol. Preferably, an acrylic latex may be used as the binder.

That is, in the catalyst vehicle mounting member of the present invention, it is preferred that its fibrous material mat is especially impregnated with an acrylic latex as a binder and also that the acrylic latex used as the binder is a combination of at least one acrylic latex having a Tg is relatively low and at least an acrylic latex having a higher Tg than that of low Tg acrylic latex. According to the present invention, with the use of acrylic latex binders having different Tg, it is possible to obtain extraordinary actions and functions that could not be expected from conventional catalyst vehicle assembly members impregnated with an acrylic latex, transmembrane protein, The use of acrylic latex having a relatively low Tg makes it possible to effectively prevent spillage of fiber pieces, and the use of acrylic latex having a relatively high Tg makes it possible to avoid reducing the pressure of the vehicle mounting member area or pressure. thus ensuring stable maintenance of increased area pressure. Particularly according to the present invention the problem of reducing area pressure can be solved by using a high acrylic latex Tg in combination with the low acrylic latex Tg. although generally recognized in vehicle mounting members It is conventional catalyst that the limb area pressure can be reduced if acrylic latex is deeply impregnated around a central part of the catalyst vehicle mounting member to prevent spillage of fiber pieces. More extraordinarily, since low Tg and high Tg acrylic latex are used in combination to simultaneously achieve the functions originating from these acrylic latexes as described above, it is possible to perform satisfactory binding functions with a small amount of the impregnated acrylic latex. adverse effect on the sensor is avoided due to the use of the large amount of acrylic latex, while a relatively large amount of the acrylic latex has to be impregnated to obtain a sufficient prior art binding function.

In the catalyst vehicle mounting member of the present invention, the acrylic latex to be impregnated in the member may include a wide range of acrylic latexes, provided they can provide the expected functions and effects described above and do not adversely affect the catalyst vehicle mounting member's other characteristics. . If desired, commercially available latexacrylic may be used as obtained or may be used after optional modification depending on the subject use of the present invention. Suitable acrylic latex includes a colloidal dispersion prepared by dispersing an acrylic latex in water or other medium.

In the practice of the present invention, the acrylic latex generally has a glass transition temperature (Tg) of about -50 to 500 ° C. Among acrylic latex having such a wide range of Tg, the most suitable combination of high Tg acrylic latex and low Tg acrylic latex may be selected and determined, depending on factors such as the catalyst assembly assembly and the required characteristics of the catalytic converter. . The present inventors have found that a combination of the first acrylic latex having a Tg of about 15 to 45 ° C and the second acrylic latex having a Tg of about 45 to 150 ° C is suitable for the present invention, although the present invention should not be limited to stacombination.

Generally, acrylic latex is preferably used after being substantially uniformly dispersed in the catalyst carrier mounting member. That is, when the track-like catalyst vehicle mounting member surrounding the catalytic vehicle is observed with respect to its thickness, it is preferred that the acrylic latex be substantially uniformly dispersed in the thickness direction of the catalyst-carrier mounting member.

In addition, as described above, acrylic latex can be impregnated into the catalyst vehicle mounting member at a reduced amount compared to that of conventional catalytic converters. Although the impregnation content of the acrylic latex may usefully be modified within the small amount range, it is generally in the range of about 0.1 to 5 wt%, preferably in the range of about 0.1 to 3 wt%.

Impregnating the vehicle catalyst mounting member with an acrylic latex, as explained above, can conveniently be conducted with well-known and conventional technologies, namely dipping, spraying, coating and the like. Especially the dipping method is simple and economical because A catalyst vehicle assembly may be fully immersed in a container containing an acrylic latex after preparation of such a container. In addition, according to the dipping method, the effect can be obtained that acrylic latex can be substantially impregnated on an entire catalyst vehicle assembly part. After impregnation, the acrylic latex may be naturally dried or heat dried to a suitable temperature.

ExamplesThe present invention will be further explained by reference to its examples. Note that the present invention should not be limited to examples.

Example 1

A needle punched alumina fiber mat (trade name "MAFTEC" manufactured by Mitsubishi ChemicalFunctional Products Inc.) having a mat surface density of 0.4g / cm was provided. The size of alumina fiber was 260 mm long, 90 mm wide and 12.5 cm thick. Then, totally 8 types of acrylic latex (organic binder) described in the following Table 1, each was diluted with 10 liters of water to prepare a latex dipping flock. The alumina fiber mat was immersed in latex dipping board to uniformly disperse the acrylic latex over an entire part of the mat. An excess amount of acrylic latex was absorbed into the wire mesh, the acrylic latex impregnated alumina fiber mat was introduced and dried in an oven at a temperature of 180 ° C to obtain a water content of about 50%. Then, the alumina fiber mat was dried completely using a 145 ° C cylindrical dryer. On each of the dry comagglutinating impregnated alumina fiber mats, the content of the organic component, indicating the amount of impregnation of the acrylic latex, was 0.5% by weight. The resulting alumina-impregnated alumina fiber mat was stored at room temperature.

The dry binder impregnated alumina fiber mat was wound around the outer peripheral surface of a monolithic cylindrical body, having a size of 78 mm outside diameter and 100 mm length (manufactured by NGK Insulators, Ltd.) separately supplied. Then the catalyst vehicle around which the alumina fiber belt was wound was stuffed into a cylindrical stainless steel case, having a size of 78 mm internal diameter and 100 mm long, with a guide grain at a rate of 40 mm / s. No defect was observed inside the resulting catalytic converter, such as belt displacement or deformation, which would cause a catalyst retention problem.

Table 1

<table> table see original document page 23 </column> </row> <table>

Assessment Tests:

Different types of organic binder impregnated alumina fiber mats (organic content: 0.5% by weight), produced according to the method described above, were tested for fiber spill and area pressure at room temperature. , according to the following way, to get the results plotted inFigs. 5 and 6.

[Fiber Piece Spill Determination]

The impact test machine described in the Japanese Industrial Standard (JIS K-6830) was used to conduct the impact test according to the guideline described in this standard. The impact test was performed in the following steps (1) to (4).

(1) Totally 8 types of binder impregnated alumina fiber mat (size: 250 mm χ 250 mm) were produced according to the method described above. Next, a test sample (size: 100 mm χ 100 mm) was produced from each of the alumina fiberglass mats in a punch mold and its weight was measured.

(2) The test sample was placed on an impact test machine described in JIS K-6830 and the impact was applied at a 30 degree angle.

(3) After applying the impact to the area, the test sample was moved from the machine and its weight was again measured.

(4) A spill amount of fiber pieces was calculated from the weight variation of the test sample before and after the test. Spill (% by weight) of the fiber pieces plotted in Fig. 5 was thus obtained.

[Determination of Area Pressure at Ordinary Temperature]

(1) 8 total types of binder impregnated alumina fiber mat (size: 250 mm χ 250 mm) were produced according to the method described above. Then a circular test sample (diameter: 45 mm) was produced from each of the alumina fiber mats in a punch mold, and its weight was measured.

(2) A belt thickness required to achieve a loading density of 0.3 g / cm was calculated from the measured weight.

(3) The test sample was placed in a central part of the compression plate of the compression test machine (Model "976.29-32" produced by MTS Co.) and the test sample was compressed at a speed of 20 mm. / minutes until the mat thickness is changed to the predetermined thickness calculated by the above procedure. A peak pressure or pressure (area pressure) at the peak was determined at an ambient temperature in the X-Y recorder. The area pressure (KPa) at ambient temperature plotted in Fig. 6 was thus obtained.

We observe from the spill plot of the fiber pieces plotted in Fig. 5 and from the room temperature plot pressure plotted in Fig. 6 that when acrylic latex having a relatively low Tg is used, the spill from the fiber pieces Fiber can be avoided, but reducing area pressure cannot be avoided. In contrast to this, when acrylic latex having a relatively high Tg is used, the area pressure may be increased, but at the same time the spillage of the fiber pieces is increased. In other words, we note that when acrylic latex having a relatively low Tg is used in combination with acrylic latex having a relatively high Tg, an area pressure can be highly maintained, while inhibiting spillage of the fiber pieces.

Example 2;

Totally 8 types of binder impregnated alumina fiber mats were produced according to the method described in Example I and the spillage of the fiber pieces and the area pressure at room temperature were determined on each of the alumina fiber mats as described in Example 1. Note that in this example, to simultaneously evaluate the effect of the degree of acrylic dolex impregnation on fiber spill and common area pressure at temperatures, the organic component content in the dealumin fiber mat was changed to 0.5 and 3. 0.5% by weight. The results are summarized in the following Table 2.

Table 2

<table> table see original document page 25 </column> </row> <table>

It is observed from the results described in Table 2 that when a degree of impregnation of the acrylic latex as an increased binder, the spillage of the fiber pieces could be prevented, as is well known in the art. In addition, it is observed that when the acrylic latex used as a binder has a Tg of no more than room temperature (20 ° C), the resulting effect of preventing spillage of fiber pieces is extremely high. Furthermore, it is observed that when the latex acrylic used as a binder has a Tg in the low temperature range (probably at a temperature of no more than 100 ° C), the area pressure at ambient temperature may be reduced. In contrast, it is observed that when the acrylic latex used as a binder has a Tg close to room temperature or more, the area pressure at room temperature may be increased.

Example 3

The binder impregnated alumina fiber mats were produced according to the method described in Example 1 of the fiber pieces and the area pressure at room temperature were determined on each of the manner of alumina fiber mats described in Example 1. Note In this example, to assess the combined effect of two acrylic latexes on fiber spill and area pressure at room temperature, the acrylic latex (LX816 and LX844 described in Table 1) was used alone or in combination (mix ratio). : 1: 1, 1: 4 and 1: 7) as described in Fig. 7. In addition, the organic component content in the alumina fiber mat was 3% ρ in each test sample. Measurement results concerning fiber shedding and area pressure at room temperature were summarized to obtain a graph plotted in Fig. 7.

It is observed by the graph showing the relationship between the fiber spill and the area pressure at room temperature that when two types of acrylic latex, having different Tg, are used in combination with a binder, an increased area pressure and a low level of Fiber shedding can be achieved simultaneously, as evidenced by the dotted line area of Fig. 7, unlike the unique use of acrylic latex, according to which such extraordinary effects were impossible to achieve.

Example 4:

The binder impregnated alumina fiber mats were produced according to the method described in Example 1 of the fiber pieces and the area pressure at room temperature were determined on each of the manner of alumina fiber mats described in Example 1. Note In this example, to evaluate the combined effect of two acrylic latexes on the spillage of fiber pieces and the area pressure at room temperature, the acrylic latex (LX816, LX814, LX844 and K-3, described in Table 1), were used as a mixture of two acrylic latexes (mixing ratio: 1: 1) as described in the following Table 3. In addition, in this example, to evaluate the effect of the degree of acrylic dolex impregnation on fiber shedding and pressure At room temperature at room temperature, the organic component content in the dealumin fiber mat was changed to 0.5 and 3.5% by weight. Measurement results consistent with fiber spill and area pressure at ambient temperature were summarized to give Table 3 described below.

Table 3

<table> table see original document page 27 </column> </row> <table>

It can be seen from the measurement results described in Table 3 that when acrylic latex, which can contribute to an increase in area pressure, and acrylic latex, which can contribute to the prevention of fiber spillage, are used in combination, it becomes if possible simultaneously perform an increase in area pressure and a doderrame inhibition of fiber pieces.

Claims (13)

1. Pollution control element mounting member, suitable for mounting a pollution control element within a box of a pollution control device, said pollution control element mounting member characterized in that it comprises a mat of a material fibrous material having a predetermined thickness, with the mat having a combination of at least two bonding types having different glass transition temperatures (Tg) impregnated therein. Pollution control element assembly member according to claim 1, characterized in that said binder is acrylic latex. Pollution control element assembly member according to claim 2, characterized in that the acrylic latex is a combination of the first acrylic latex having a Tg of 15 to 45 ° C and the second acrylic latex having a Tg of -45 to 15 ° C. . Pollution control element assembly member according to claim 2 or 3, characterized in that the total acrylic dolat content in the mat of the fibrous material is in the range 0.1 to 5% by weight. Pollution control element assembly member according to any one of claims 1 to 4, characterized in that the fibrous material is an inorganic fibrous material comprising alumina-containing fibers. Pollution control element assembly member according to Claim 5, characterized in that the inorganic fibrous material further comprises silica fibers and / or glass fibers in combination with the alumina-containing fibers. Pollution control element assembly member according to any one of claims 1 to 6, characterized in that the fibrous material belt is formed by a dry process. Pollution control element assembly member according to any one of claims 1 to 7, characterized in that said pollution control element is a catalyst vehicle. Pollution control element assembly member according to any one of claims 1 to 7, characterized in that said pollution control element is a filter element. 10. Pollution control device, characterized by the fact that it comprises a housing, a pollution control element provided within the housing and a pollution control element mounting member disposed between the housing and the pollution control element, a mounting arrangement. pollution control element being the pollution control element assembly described in any one of claims 1 to 7. Pollution control device according to claim 10, characterized in that said pollution control element is a catalyst vehicle and said pollution control device is a catalytic converter. Pollution control device according to claim 10, characterized in that said pollution control element is a filter element and said pollution control device is an exhaust cleaning device. Exhaust system for an internal combustion engine, said exhaust system characterized in that it comprises a pollution control device as defined in any one of claims 10 to 12.