JPH11510428A - Combined mounting system - Google Patents

Abstract

  (57) [Summary] The present invention relates to a composite mounting material for use in a catalytic converter element or a diesel particulate filter element, the composite mounting material comprising: (a) at least one flexible mat; and (b) at least one unexpanded intumescent material. And a sheet of intumescent paste or dry intumescent paste sheet.

Description

Description: FIELD OF THE INVENTION The present invention relates to mounting materials for use in catalytic converters and diesel particulate filters or traps. BACKGROUND OF THE INVENTION Pollution control devices are widely used in motor vehicles to control air pollution. Two types of equipment are currently in widespread use: catalytic converters and diesel particulate filters or traps. A catalytic converter comprises a catalyst that is generally coated on a unitary structure mounted within the converter. Monolithic structures are generally ceramic, but metal monoliths have been used. Catalysts oxidize carbon monoxide and hydrocarbons and reduce nitrogen oxides in vehicle exhaust to control air pollution. Diesel particulate filters or traps are generally wall flow filters having an integral honeycomb structure formed from a porous crystalline ceramic material. In the construction of these devices of the state of the art, a variety of such devices have a monolithic structure or a metal housing that holds elements that are metal or ceramic and most commonly ceramic. Ceramic monoliths generally have thin walls to provide most of the surface area and are brittle and fragile. Ceramic monoliths also generally have a smaller coefficient of thermal expansion than the metal (typically stainless steel) housing in which they are contained. To avoid damaging the ceramic monolith due to road impacts and vibrations, to compensate for differential thermal expansion, and to prevent the passage of exhaust gases between the monolith and the metal housing, a ceramic mat or paste material is used. Generally located between the ceramic and metal housing. The step of placing or inserting the mounting material is called canning and involves injecting the paste into the gap between the monolith and the housing or wrapping the monolith around a sheet or mat material and inserting the wrapped monolith into the housing. Process. In general, mounting materials include inorganic binders, inorganic fibers that can also serve as binders, expandable materials and optionally inorganic binders, fillers and other adjuvants, and the like. The materials are used as pastes, sheets and mats. Ceramic mat materials are ceramic paste and intumescent sheet materials useful for mounting monoliths in housings, for example, U.S. Patent Nos. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al.). No. 4,385,135 (Langer et al.), No. 5,254,410 (Langer et al.), No. 5,242,871 (Hashimoto et al.), No. 3,001,571 (Hatch), No. 5,385,873 (MacNeil), No. 5,207,9889 No. (MacNeil) and GB No. 1,522,646 (Wood). U.S. Pat.No. 4,999,168 (Ten Eyck) describes a crack resistant intumescent sheet having a preform intumescent layer adhesively bonded to a reinforcing layer of sheet material such as kraft paper, plastic film, and inorganic fabric. . U.S. Pat.No. 4,865,818 (Merry et al.) Describes a method of manufacturing a catalytic converter by wrapping a thin sheet or mat material around a monolith at least twice in a layer-like manner. . U.S. Pat. No. 4,929,429 (Merry) describes a composite material for use in a catalytic converter having a ceramic fiber mat stitch bonded to an intumescent mat material. U.S. Pat. No. 4,048,363 (Langer et al.) Describes a composite material having at least two layers of similar sheets of intumescent material. Although the mounting materials of the state of the art have their own benefits and benefits, there is still a need to improve the mounting materials in catalytic converters. It would further be desirable to provide a material that performs well over a wider temperature range. SUMMARY OF THE INVENTION The present invention provides a composite mounting material for use in a catalytic converter element or a diesel particulate filter, comprising: (a) at least one flexible mat; and (b) at least one unexpanded inflatable material. And at least one layer of intumescent paste or dry intumescent paste sheet comprising: Pastes are moldable compositions that include an inorganic binder and an organic binder. Other features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, and may be learned by practice of the invention. The objects and other advantages of the invention will be realized and attained by the methods and articles particularly pointed out in the written description and claims hereof. The foregoing general description and the following detailed description are exemplary and explanatory and are intended to further explain the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the results of an actual condition fixing test for Example 1. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a mounting composite having at least one layer of the paste composition and at least one layer of a mat or sheet material, wherein at least the paste composition is expandable. In a preferred embodiment, the paste composition and the mat or sheet material include at least one unexpanded intumescent material. The composite material of the present invention has a brittle integral structure of a catalytic converter, and is useful for diesel particulate filters and high temperature filters. Composite mounting materials offer the advantage of combining the properties of paste and sheet materials. In addition, the composite material of each layer can be formulated to expand at different temperatures to extend the useful temperature range of the mounting material. The paste composition of the present invention includes a material that can be formed into a flexible sheet. Preferred paste compositions include, based on dry weight, about 20% to 60% organic binder and 80% to 40% inorganic material. More preferably, the inorganic material comprises an inorganic binder material and an intumescent material. Suitable organic binder materials include aqueous polymer emulsions, solvent-based polymer solutions, and 100% solid polymers. Aqueous polymer emulsions are organic binder polymers and elastomers in latex form (eg, natural rubber latex, styrene butadiene latex, butadiene-acrylonitrile latex, ethylene vinyl acetate latex, and latexes of acrylate and methacrylate polymers and copolymers). Solvent-based polymer binders include, for example, acrylic, polyurethane, or rubber-based organic polymers contained in organic solvents such as toluene, methyl ethyl ketone, heptane, and mixtures thereof. 100% solid polymers include natural rubber, styrene-butadiene rubber and other elastomers. Acrylic materials are preferred for their excellent anti-aging properties, slow burn out in the operating temperature range, and non-corrosive combustion products. The binder material may include at least one tackifier, a plasticizer, or both. The tackifier or tackifying resin can be a hydrocarbon or a modified rosin ester, generally providing tack-type properties to the polymer. Tackifiers help in holding the filler and filler together. Preferably, the organic binder material comprises an aqueous acrylic emulsion. Useful emulsions include Rohm and Haas of Philad elphia under the designations "RHOPLEX TR-934" (44.5 weight percent solids aqueous acrylic emulsion) and "RHOPLEX HA-8" (44.5 weight percent solids acrylic copolymer aqueous emulsion). , PA. A preferred acrylic emulsion is commercially available from ICI Resins US of Wilmington, Massachusetts under the designation "NEOCRYL XA-2022" (60.5% solid aqueous dispersion of acrylic resin). Preferred organic binder materials include from about 25 to about 50 weight percent acrylic resin, from about 15 to about 35 weight percent plasticizer (product designation "SANTICIZER 148" (isodenyl diphenyl), based on the total weight of the resulting dispersion. Diphosphate), such as those commercially available from Monsant of St. Louis, Mis. Melting point: 55 ° C., including rosin tackifiers commercially available from Eka Nobel, Inc., Toronto, Canada.These ranges are for the desired flexibility of the binder material and for the organic binder that burns off during heating at the use temperature. A compromise was provided between minimizing the amount.Suitable inorganic materials include inorganic binders known to those skilled in the art used for such uses and include montmorillonite (Bentona Water-swelling clays, such as kaolinite, and water-swellable clays, either in water-swellable powder-exchanged form or as salts exchanged with divalent or polyvalent cations. Water-swellable synthetic mica, such as fluorinated silicate mica, expanded vermiculite, delaminated vermiculite, and crushed expanded vermiculite that can be produced, for example, by ball milling or high shear mixing of unexpanded or expanded vermiculite The inorganic binder also includes ceramic fibers, but the amount of ceramic fibers must not prevent the paste from being formable. Preferred inorganic binders include expanded vermiculite and crushed expanded vermiculite. Useful expandable materials include unexpanded vermiculite, expandable graphite, hydrobiotite, and water swell as described in US Patent No. 3,001,571 (Hatch). Mica of the synthetic synthetic bromine tetrasilicate type, partially dehydrated vermiculite described in U.S. Pat.No. 5,151,253 (Merry et al.), And alkali metal silicates described in U.S. Pat.No. 4,521,333 (Graham et al.) Preferred expandable materials include unexpanded vermiculite or flour ore and expandable graphite The choice of expandable material depends on the desired end use method. Above about 500 ° C., vermiculite material is suitable because it begins to expand at about 340 ° C. and fills the expanding gap between the expanding metal housing and the monolith inside the catalytic converter. Treated graphite is preferred because it begins to expand at about 210 ° C. when used at low temperatures, eg, below about 500 ° C., and when used in diesel particulate filters and the like. Treated vermiculite is also available, but they expand at about 290 ° C. Blends of each expandable material can also be used. Various forms of fillers, including particulates and chopped fibers, can be included in the composition. Fibers can be reduced in size by conventional techniques, including dry milling or wet milling. Useful fibers include graphite, silica, alumina-silica, calcium-silica, asbestos, glass, metals such as Inconel and stainless steel, and those formed from polymeric materials such as rayon, polyvinyl alcohol, and acrylic. Commercially available fibers include Inconel fibers (eg, available from Bekaert Steel Wire Corp., Atlanta, Georgia under the trade designation "BEKI-SHIEL D GR90 / C2 / 2"). Preferred fibers include glass fibers, metal fibers, and polymer fibers. Other suitable fillers include inert materials that are relatively insoluble in water. Such materials include hydrated metal oxides (eg, alumina and sodium silicate), borates (borate or zinc borate), calcium carbonate, talc, feldspar, silicon carbide, and silica sand. Other additives included in appropriate amounts for the purposes described above include defoamers, surfactants, dispersants, fungicides, fungicides, and the like. Generally, these types of additives are included in amounts less than about 5 weight percent. In practicing the present invention, the paste composition is formed by mixing together an organic binder material, an inorganic material and any filler to form a moldable composition. Optional water, dispersants, tackifiers, bactericides, plasticizers, surfactants, and the like are independently converted and aid in mixing the components together and / or adjusting the viscosity of the mixture. The mixing of the components can be accomplished by convenient means such as manual stirring or commercially available mechanical mixers such as Mogul mixers and Ross mixers. The paste composition can be formed into an organic paste layer on a release liner such as wax paper. This layer is dried, if necessary, and then laminated to a sheet or mat layer. This lamination can be done by physically pressing the paste layer into a sheet or mat layer, but may also use an adhesive to join the two layers. Suitable adhesives include pressure sensitive adhesive transfer tapes, spray adhesives, emulsion adhesives such as "Elmers Glue", paste adhesives, and the like. Alternatively, the paste layer can be formed directly on top of the sheet or mat layer. If the paste layer is sticky due to the organic field, spray talc or other finely divided inorganic or organic particulates on the exposed paste layer and reduce the adhesion to make the process ready Seems to be desirable. The mat or sheet material of the present invention is expandable or non-expandable. Examples of expandable sheet materials include U.S. Pat.Nos. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al.), 4,385,135 (Langer et al.), And 5,254,410 (Langer et al.). ), 4,865,818 (Merry et al.), 5,151,253 (Merry et al.), And 5,290,522 (Rogers et al.). Another intumescent sheet material is PCT application _______________, which is a co-pending application filed on the same date as the specification of the present application and whose title is `` INTUME SCENT MATERTAL ''(attorney's serial number No. 51746P CT1A), PCT application No. PCT Application No. ______________ (Attorney Docket No. 51745PCT3A). Useful commercially available expandable material and the mat, Minne sota Mining & Manufacturing Co. under the trade name of INTERAM ^TM, St. Paul and Minnesota. Suitable intumescent mats are, on a dry weight percent basis, from 20% to 65% unexpanded vermiculite flakes, 10% to 50% inorganic fiber material, 3% to 20% organic binder and up to 40% inorganic filler. including. Further, the sheet may include other expandable materials such as expandable graphite. The unexpanded vermiculite flakes may or may not be treated by treatment such as by ion exchange with ammonium compounds such as ammonium dihydrogen chloride, ammonium carbonate, ammonium chloride, or other suitable ammonium compounds. Is also good. Inorganic fiber materials include aluminosilicate fiber (commercially available under the trade name Fiberfrax ^™ from Carbon Ordum Co., Niagara Falls, New York, and commercially available from Cerafiber ^™ from Thermal Ceramic, Augusta, Georgia), asbestos fiber, soft glass fiber, zirconia -Silica fibers and crystalline alumina whiskers. Organic binders include natural rubber latex, styrene butadiene latex, butadiene acrylonitrile latex, tacrylate polymers and copolymers, and the like. Inorganic fillers include vermiculite, hollow glass microspheres, bentonite, and the like. Preferably, the inorganic filler is expanded vermiculite. Non-intumescent material sheets or mat layers include ceramic mats and paper. Suitable ceramic papers include Fiberfrax ^™ 880, available from Carborundum Co., Saffil LD, available from ICI Chemicals & Polymers, Widness, Cheshire, United Kingdom. The mat can be formed on a device such as a Fourdrinier device by well-known paper making techniques. Mats can also be formed by expanding the fibrous material on a collecting screen as is practiced in the nonwoven industry. The layers of the composite material can be formulated to suit the final purpose. For example, some composites include a paste layer having a material that expands at a lower temperature than the expander utilization of the mat. Using this concept, the paste surface can be mounted in contact with the monolith, expanding at low temperatures and providing fusing power at those temperatures. The combination of high temperature and low temperature expansion materials can facilitate holding the monolith in place in the catalytic converter over an extended temperature range. Further, the composite sheet of the present invention may further include an edge protection material. Suitable materials include stainless steel wire screens wrapped around edges as described in U.S. Pat.No. 5,008,086 (Merry), braided wires or rope-like ceramics described in U.S. Pat.No. 4,156,333 (Close et al.). (Ie, glass, crystalline ceramic or glass-ceramic) fiber blades or metallic materials. The edge protection material formed is also formed from the glass particulates described in EP 639701 A1 (Howorth et al.), EP 639 702 A1 (Howorth et al.), And EP 639 700 A1 (Stroom et al.). be able to. In another aspect, the present invention provides a catalytic converter or a diesel particulate filter using the mounting material of the present invention. Catalytic converters or diesel particulate filters generally include a housing, a unitary structure or element, and a mounting material disposed between the structure and the housing to maintain the structure in place. The housing, also called the can or casing, is formed from a suitable material known to those skilled in the art for such use, and is generally formed from metal. Preferably, the housing is formed from stainless steel. Suitable catalytic converter elements, also called monoliths, are well known to those skilled in the art and include those formed from metal or ceramic. Monoliths or elements are used as catalytic materials for converters. Useful catalytic converters are disclosed, for example, in US Patent No. RE 27,747 (Johnson). Ceramic catalytic converter elements are commercially available, for example, from Corning Inc. of Corning, New York, and NGK Insulator Ltd., Nagoya, Japan. For example, honeycomb ceramic catalyst supports are available from Corning Inc. under the product designation "CELCOR". and "HONEYCERAM" by NGK Insulator Ltd. Metal catalytic converter elements are commercially available from Behr GmbH and Co., Germany. For further details on catalytic monoliths, see, for example, “Systems Approach to Packaging Design for Automotive Catalytic Converters”, Stroom et al., Paper No. 900500, SAE Technical Paper Series, 1990, “Thin Wall Ceramics as monolithic Catalyst Supports”, Howitt, Paper 800082, SAE Technical Paper Series, 1980, “Flow Effects in Monolithic Honeycomb Automotive Catalytic Converters”, Howitt et al., Paper No. See 740244, SAE Technical Paper Series, 1974. Catalytic materials coated on the catalytic converter include those known to those skilled in the art (e.g., ruthenium, osmium, rhodium, iridium, nickel, palladium, and platinum, vanadium pentoxide, metal oxides such as titanium dioxide, etc.). For further details on catalyst coatings, see, eg, US Patent No. 3,441,381 (Keith et al.) Conventional monolithic diesel particulate filter elements are honeycomb-structured and porous crystalline. A ceramic (cordite) material, another cell of the honeycomb structure is generally inserted into a cell where the exhaust gas enters one cell, passes through the porous walls of one cell, and exits the structure through another cell. Cured filter elements depend on the needs of a particular application. Diesel particulate filter elements are commercially available, for example, from Corning Inc., Corning, New York, and NGK Insulator Ltd., Nagoya, Japan A useful diesel particulate filter element is "Cellular Ceramic Diesel Particulate Filter." , "Howitt et al., Paper No. 810114, SAE Technical Paper Series, 1981. In use, the mounting material of the present invention may be used in either a catalytic converter or a diesel particulate filter. It is arranged in a similar manner between the monolith and the housing, which can be achieved by wrapping the monolith with one piece of mounting material, inserting the wrapped monolith into the housing, and sealing the housing. The objects and advantages of the present invention will be more specifically illustrated by the following examples, which will be incorporated by reference. Other conditions and details, as well as materials and amounts thereof, are not to be construed to unduly limit the invention, and all parts and percentages are by weight unless otherwise indicated. Test (RCFT) The RCFT is a test used to measure the pressure applied by the fixture under conditions typical of the actual conditions found in a catalytic converter during normal use. Two 50.8 mm x 50.8 mm heating platens are each heated to mimic the metal housing and monolith temperatures to different temperatures. At the same time, the spacing or gap between the platens is increased by values calculated from typical catalyst converter temperatures and coefficients of thermal expansion. Table 1 below shows changes in the temperature and gap of the surface plate. The force applied by the mounting material was measured by a Sintech ID computer controlled load frame using an extensometer (MTS Systems Corp., Research Triangle Park, North Carolina). Example 1 Ingredient A of the intumescent paste composition was treated with 3003 grams of inflatable vermiculite (Zonalite # 5, commercially available from WR. Grace Co., Cambridge, Mass.), 2000 grams of water, 2,896 grams of 60.5% solid acrylic latex ( Neocryl ^™ 2022, commercially available from Zeneca Resins, Wilmington, Massachusetts), 16 grams of fungicide (Busan ^™ 1024, commercially available from Buckman Laboratories, Memphis, Tennessee), Ross mixer with planetary blades and high shear dispersing blades (Model PD4 Mixer, commercially available from Charles Ross & Son Co., Haup pauge, New York). The mixer was sealed and placed under 15 inches of mercury vacuum (in Hg) (50.7 kilopascals (kPa)). The materials were mixed for 20 minutes at a planetary and dispersing blade speed set at 20 on the control panel. After blowing air into the vacuum to open the mixer, 6,237 grams of tubular alumina (-48 + 200 mesh alumina, Alcoa, Bauxite, Arizona) and 1,944 grams of plasticizer (Sanitisizer ^™ 148, Monsanto Co., Bridgeport, New Jersey) (Commercially available) was added to the batch. The mixer was sealed, placed under a reduced pressure of 15 inches Hg (50.7 kPa), and the batch was mixed for an additional 20 minutes with the planetary and dispersing blade speed set at 20. After air was blown into the vacuum to open the mixer, 2,896 grams of tackifier (Snowtack ^™ 810A, commercially available from Eka Nobel Canada, Inc., Toronto, Ontario) and 6,362 grams of flour ore (Cometals, Inc., New York) , New York) was added to the batch. Again, the mixer was sealed and placed under reduced pressure of 15 inches Hg (50.7 kPa). The batch was mixed for an additional 20 minutes with the planetary and dispersing blade speed set at 20. After blowing air into the vacuum, the mixer was opened and the resulting composition was placed in a sealed 5 gallon (18.9 liter) plastic container. The composition on a dry weight basis is about 30.6% swelling agent, 8.4% acrylic polymer, 9.4% plasticizer, 7.1% tackifier, 14.4% inorganic binder, 0.08% fungicide and 30% Filler (alumina). Component B of the expansion paste composition, 5 grams expansion vermiculite ^{(Zonolite TM Vermiculi te # 5)} , 41.7 grams of 60.5% solids acrylic latex (Neocryl ^TM 2022), 4 1.7 grams of tackifier (Snowtack ^TM 810A ), 27.9 grams of plasticizer (Sanitisizer ^TM 148) and 31.5 grams of expanded graphite (product number 533-61-26, commercially available from Ucar Carbon Co., Danbury, Connecticut) in a beaker by hand Prepared by Next, an intumescent paste composition was prepared by mixing 25 parts of component A and 75 parts of component B. The resulting composition was cast on a piece of wax paper at a thickness of about 3.2 mm to form a paste layer. The paste layer was dried overnight in a convection oven set at 95 ° C. The intumescent mounting composite material is a spray adhesive (Shipping-Mate ^™ case seal adhesive, Minnesota Mining & Manufacturing Co., St. Paul, Minnesota) using an intumescent mat (Type 100 Interam ^™ brand automotive mounting mat, 3100). g / m ² , commercially available from Minnesota Mining & Manufacturing Co.) and prepared by laminating the paste layer to a mat. The composite sheet was tested for holding force under the above-described actual condition fixing test. The test results shown in FIG. 1 show that the composite material applies sufficient pressure to fix the monolith in the casing over the operating temperature range. Those skilled in the art will appreciate that various changes and modifications can be made to the methods and articles of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their corresponding parts.

Claims (1)

[Claims]   1. Catalytic converter element or diesel particulate filter element A composite mounting material for the (a) at least one flexible mat; (b) at least one layer of intumescent paste comprising at least one unexpanded intumescent material; Or a composite mounting material comprising a dry intumescent paste sheet.   2. The flexible mat comprises at least one unexpanded intumescent material. A composite mounting material according to item 1.   3. The composite mounting material comprises two or more layers of an intumescent paste or a dry intumescent paste. 2. The material of claim 1, comprising a sheet.   4. The mat has at least one unexpanded swell of 25 to 60 dry weight percent. Claims: comprising a tonic material and 25 to 60 dry weight percent ceramic fibers. 2. The composite mounting material according to 2.   5. The composite mounting material according to claim 4, wherein the mat further comprises an organic binder. Fees.   6. 3. The composite mounting material according to claim 2, wherein the mat includes an organic binder.   7. The expandable paste or the dry expandable paste sheet has a dry weight of 20 to 60%. 2. The composite mounting material according to claim 1, comprising an amount of an organic binder.   8. The expandable paste or the dry expandable paste sheet has a dry weight of 20 to 60%. Weight percent organic binder and at least one of 1 to 70 dry weight percent An expansive material that is not swelling, and 5 to less than 79 dry weight percent of an inorganic binder. The composite of claim 1, comprising 0 to 70 dry weight percent of one or more fillers. Mounting material.   9. A pollution control device, (a) a housing; (b) a contaminated tube comprising the composite mounting material of claim 1 disposed within the housing. And a pollution control device.