MXPA97010227A - Intumesce layer material - Google Patents

Abstract

The invention provides an intumescent layer material comprising 20 to 80 percent by dry weight of at least one non-expanded intumescent material, 10 to 40 percent by dry weight of at least one processed vermiculite selected from expanded vermiculite, milled and vermiculite. delaminated, more than 0 to

Description

INTUMESCENT LAYER MATERIAL FIELD OF THE INVENTION This invention relates to assembly materials for a catalytic converter and diesel particulate filters.

BACKGROUND OF THE INVENTION Pollution control devices are used in motor vehicles to control air pollution. Two types of devices are currently in widespread use - catalytic converters and filters or separators or diesel particulate interceptors. The catalytic converters contain a catalyst, which is typically coated on a monolithically placed structure in the converter. Monolithic structures are typically ceramic, although metal monoliths have been used. The catalyst oxidizes carbon monoxide and hydrocarbons, and reduces nitrogen oxides in automobile exhaust to control air pollution. Diesel particulate filters or interceptors are wall flow filters that have monolithic structures REF .: 26433 cavernosa typically made of crystalline, porous ceramic materials. In the state of construction of the technique of these devices, each type of these devices has a metal housing that holds it inside a monolithic structure or element that can be metal or ceramic, and more commonly is ceramic. The ceramic monolith in general has very thin walls to provide a large amount of surface area so that it is brittle and susceptible to breakage. It also has a coefficient of thermal expansion, generally an order of magnitude smaller than the metal housing (usually stainless steel) in which it is contained. In order to avoid damage to the ceramic monolith from a shock or jolt and road vibration, to compensate for the difference in thermal expansion, and to prevent exhaust gases from passing between the monolith and the metal housing, they are typically placed Mat materials or ceramic paste between the ceramic monolith and the metal housing. The process of placing or inserting the mounting material is also referred to as carting and includes such processes as injecting a paste into an opening between the monolith and the metal housing, or wrapping a sheet or mat material around the monolith and insertion of the monolith wrapped inside the housing. Typically, the assembly materials include inorganic binder substances, inorganic fibers which may also serve as a binder, intumescent materials and, optionally, organic binder substances, fillers and other adjuvants. The materials are used as pastes, layered materials, and mats. The ceramic mat materials, • ceramic pastes and intumescent layer materials useful for mounting the monolith in the housing are described in, for example, U.S. Patent Nos. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al.), 4,385,135 (Langer et al.), 5,254,410 (Langer et al.) And 5,242,871 (Hashimoto et al.). The use of synthetic mica and asbestos or asbestos fibers as inorganic binders for the materials in inorganic fiber assembly layers is described in US Pat. No. 3,001,571 (Hatch).

Paste compositions using micaceous materials are described in the patent G.B. 1,522, 646 (Wood). U.S. Patent Nos. 5,385,873 (MacNeil) and 5,207,9889 (MacNeil) describe layered materials of inorganic fibers, bound by vermiculite in high aspect ratio in the paste to mount the monoliths in the catalytic converters. U.S. Patent No. 5,126,013 (iker et al.) describes the use of flocculating agents with chemically delaminated mica and / or vermiculite and fibers for making fire-resistant papers that are generally thin compared to mats and layered materials. The sequential, double flocculation system describes aids to achieve rapid dehydration in the manufacture of opposed materials in water and provide better formation of the material in layers without the agglutination of the fibers. U.S. Patent No. 5,137,656 (Connor) describes the use of vermiculite sheets that have an internal sizing agent to make water resistant mineral products. Various means of production of the vermiculite sheets are described. One of the limitations of the state of the pastes and mats of the technique used for the assembly occurs because the exposed edges of the assembly materials are subjected to the erosion of the hot, expelled exhaust gases. Under severe conditions, over a period of time, the assembly materials may wear out and portions of the materials may melt. Further, a sufficient amount of the mounting materials can be melted and the mounting materials can fail to provide the necessary protection to the monolith. Solutions to the problem include the use of a stainless steel wire screen (see for example, U.S. Patent No. 5,008,086 (Merry)) and braided or string-like ceramic fiber (i.e., glass, crystalline or ceramic ceramics). glass) braided or metal wire material (see, for example, U.S. Patent No. 4,156,333 (Cióse et al.)), and edge protecting agents formed from the compositions having glass particles (see, for example, application for European Patent No. 639701 Al (Howorth et al., European Patent Application No. 639702 Al (Howorth et al.), and European Patent No. 639700 Al (Stroom et al.)) to protect the edge of the intumescent mat from erosion by Exhaust gases These solutions employ the use of the state of the mounting materials of the technique as the primary support for the monolith.The materials currently available as mounting mats and materials in Assembly apas typically contain inorganic binder material, refractory ceramic fibers in the range of approximately less than 5 micrometers in diameter, and other adjuvants. The inorganic binder materials and the refractory ceramic fibers provide the strength and resilience necessary for handling before packaging as well as keeping the assembly material intact during the repeated cooling and heating cycles experienced in a catalytic converter. The fibers also bond the particulate materials to facilitate the drainage of the compositions in the manufacture of mounting mats in the state of the wetting or papermaking processes. The use of refractory ceramic fibers is undesirable and a current need remains for mounting materials, particularly mats, which have high performance without the use of refractory ceramic fibers of small diameter, i.e. less than 5 microns. Additionally, it is desirable that the compositions used for mat mounting materials have good drainage in the mat manufacturing process as well as resilience for the handling of the mats before assembly and in the use of a catalytic converter.

BRIEF SUMMARY OF THE INVENTION The invention provides an intumescent layer material comprising 20 to 80 percent by dry weight of at least one unexpanded intumescent material, 10 to 47 percent dry of at least one processed vermiculite selected from ground expanded vermiculite and delaminated vermiculite, greater 0 to 5 percent dry weight of inorganic fibers having diameters greater than 5 microns and greater than 0 to 10 percent dry weight of organic fibers; wherein the layered material substantially comprises non-ceramic fibers of less than 5 microns. The invention also provides a catalytic converter and a particulate diesel filter containing the intumescent layered material. Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and joined by the methods and articles particularly pointed out in the description and written claims thereof. It is understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide additional explanation of the invention as claimed.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a mounting material having improved erosion resistance on the state of the art materials used for monolithic, brittle, assembly structures for use in environments that demand high temperature, such as would be found in catalytic converters. and particulate diesel interceptors. The mounting materials can be provided in various forms including mats, layered materials and pastes. Preferably, the mounting materials are mats that are preferably greater than 1 millimeter (m) in thickness, and more preferably, greater than 1.5 mm in thickness. The mounting materials of the invention comprise from about 10 to 40% by weight of a micaceous binder material, 20% to 80% by weight of an intumescent material and from about 0% to 5% by weight of glass fibers having a diameter less than approximately 2.0 micrometers. Optionally, the mounting materials may include 0 to 5% inorganic fibers having a diameter between approximately greater than 5 microns, and 0 to 10% organic or polymeric fibers which may be staple fibers, fibrillated fibers, bicomponent binding fibers or a mixture thereof and 0-5% organic, resinous binder substance.

The amounts of the materials for the compositions can be varied within the scope of the invention to achieve the desired final properties of the mounting materials before and after assembly in a catalytic converter. The paste compositions require suitable rheological properties so that the compositions can be pumped into the opening between the monolith and the metal housing during the assembly or packaging operation, and resilience to maintain the composition attached to the temperatures of use. The materials in layers and mats require resilience as well as strength, flexibility, and conformability before assembly, since these materials in layers or mats are formed first, and then wrapped around the monolith. Materials in layers and mats need sufficient internal strength to hold together as they undergo additional processing before assembly, such as die cutting, shipping, etc. Additionally, the mats are formed by a process of putting into water, also referred to as a process for making paper, so that in the formation of the mats, the compositions of the mat, which generally contain a large amount of water, are They must formulate to drain well and quickly during the training process. The compositions of the mat should also be formulated to provide a suitable mounting density to provide adequate pressure to hold the monolith in place. Typically, the assembly densities range from about 0.9 grams per cubic centimeter (g / cc) to about 1.2 g / cc. Materials in layers and mats must also be provided in a releasable outer carrier or liner. In a preferred embodiment for the mounting mats, the micaceous binding substances and intumescent materials comprise, on a dry weight basis, from about 20% to 30% of micaceous binder substance, 60% to 70% of intumescent material, 0.3% a 0.5% of glass fibers having a diameter of less than about 2 microns, 2% to 10% of organic fibers, preferably in a mixture of about 50% fibrillated fibers and about 50% staple fibers, 1% to 3% % of inorganic fibers having a diameter between about 8 and 15 microns, and 1% to 5% of organic, resinous binder substance. The inorganic materials of the invention include micaceous minerals that have been delaminated and preferentially delaminated and further crushed or milled. Preferred micaceous minerals include vermiculite. Especially preferred micaceous minerals are processed vermiculites, selected from ground expanded vermiculite and delaminated vermiculite. Vermiculite is typically delaminated by exfoliation. This can be done by heating the vermiculite to expand the particles, or by chemical treatment with hydrogen peroxide or aqueous solutions of salts followed by washing and soaking in water to swell the structure of the vermiculite particles. The expanded and thickened vermiculite is then mechanically sheared in water to produce an aqueous dispersion of vermiculite particles or platelets. Suitable micaceous materials are commercially available from W.R. Grace &; Company, and include a powder of delaminated vermiculite (VFPSMR vermiculite) and an aqueous dispersion of chemically exfoliated vermiculite (MicroliteMR vermiculite dispersion). In a preferred embodiment, expanded vermiculite flakes, such as Zonolite ™ # 5 available from W.R. Grace & Company, are milled with water in a slurry or subsequent blender to provide useful particles that improve the erosion resistance and resilience of a mounting mat, while providing adequate drainage of the mat composition in a manufacturing process. of paper to form the mats. While not wishing to be bound by theory, it is believed that the platelets prepared in this manner provide a fiber-like resilience to the compositions which allows the compositions to be formed by a process put in water. In the processes put into water, it is important that the compositions with the binders drain quickly after they have been drained into a screen in a paper machine. Additionally, the mats for the mounting materials are preferably thicker than about 1 mm, and it is generally difficult to properly drain thicker materials. Suitable intumescent materials include unexpanded vermiculite, vermiculite ore, hydrobiotite, mica of the fluorine, tetrasilicic, synthetic type, which can be swelled with water, described in U.S. Patent No. 3,001,571 (Hatch), alkali metal silicate granules as it is described in U.S. Patent No. 4,521,333 (Graham et al.), and expandable graphite. Suitable intumescent materials also include EXPANTROLMR 4BW granules available from Minnesota Mining & Manufacturing Co. , St. Paul Minnesota. Glass fibers useful in the practice of the invention are those having a diameter of less than about 2.0 microns. Suitable glasses include borosilicate glasses such as calcium aluminoborosilicate, magnesium aluminoborosilicate and alkaline borosilicate (for example sodium and potassium). Preferably, the fibers are made of alkaline borosilicate glass. The term "glass" as used herein refers to an amorphous organic oxide material (ie, a material having a diffuse X-ray diffraction pattern with no defined lines to indicate the presence of a crystalline phase). Suitable glass fibers have a softening point close to the use temperature. This temperature is typically below about 900C, preferably below about 850C, and more preferably below about 800C. The term "softening point" refers to the temperature at which a glass in the form of a fiber of uniform diameter is prolonged to a specific proportion under its own weight. Suitable glass fibers are commercially available under the trademarks Micro-Strand ™ Micro-Fibers ™ from Schuller Co. When used, glass fibers having a diameter less than 2.0 microns are included in amounts from about 0.1% to about 0.5% , and preferably from about 0.2% to about 1.0% for mat materials. Larger amounts of glass fibers can decrease the drainage of water during the process put in water. It is particularly surprising that the addition of a small amount, i.e., less than about 1%, of glass fibers less than about 1.5 micrometers in diameter, significantly improves the erosion resistance of the mounting materials. Without wishing to be bound by theory, it is believed that the glass fibers soften and act as binders to provide added strength to the mounting materials at the use temperature, i.e., in the range of about 200C to about 900C. Organic resinous binder substances and organic fibers can be included to provide resilience and flexibility to the layer or mat mounting materials prior to assembly. Organic binder materials, resinous, suitable include aqueous polymer emulsions, solvent based polymers and 100% solid polymers. Aqueous polymeric emulsions are organic binder polymers and elastomers in the form of latexes (eg, natural rubber latexes, styrene-butadiene latices, butadiene-acrylonitrile latices, and polymer latices and acrylate and methacrylate copolymers). The polymeric binder substances based on solvents can include a polymer such as an acrylic, a polyurethane or an organic polymer based on rubber. 100% solid polymers include natural rubber, styrene-butadiene rubber and other elastomers. Preferably, the organic binder material includes an aqueous acrylic emulsion. Acrylic emulsions are preferred due to their aging properties and non-corrosive combustion products. Useful acrylic emulsions include those commercially available under the trade designations "RHOPLEX TR-934" (44.5% by weight aqueous acrylic emulsion solids) and "RHOPLEX HA-8" (44.5% by weight aqueous solids emulsion). acrylic copolymers) from Rohm and Haas of Philadelphia, Pennsylvania, and Airflex ™ 600BP (55% solids of ethylene vinyl acetate copolymer) from Air Products of Allentown, Pennsylvania. The organic binder materials may also include at least one plasticizer. The plasticizers tend to soften a polymer matrix and thereby contribute to the flexibility and moldability of the layered materials made from the composition. When used, the organic binder substance is preferably used in amounts of about 1% to about 5%. For mat materials, the organic binder substance is preferably used in amounts between about 1% to about 4%.

Suitable fibers that are commercially available for use as reinforcing fibers or as ground fibers dispersed within the mounting materials include inorganic fibers having a diameter greater than 5 microns (available, for example, under the trade designations "NEXTEL 312 CERAMIC FIBERS", "NEXTEL 440 CERAMIC FIBERS "and" NEXTEL 550 CERAMIC FIBERS " Minnesota Mining & Manufacturing Company, and Inconel fibers (commercially available, for example, under the trade designation "BEKI-SHIELD GR90 / C2 / 2" from Bekaert Steel Wire Corp. of Atlanta, Georgia). Suitable ceramic fibers are also described in U.S. Patent Nos. 3,795,524 (Sowman) and 4,047,965 (Karst et al.). The larger diameter glass fibers can also be included in the mounting materials. Preferably, the fibers are made of high temperature glass of diameters of greater than about 5 microns and more preferably between about 8 and 16 microns. An example of a commercially available glass fiber suitable is S-2 GlassMRHT from Owens-Corning Fiberglass Corp. which is a 9 micron glass fiber. When used, glass fibers of larger diameter are used in amounts of up to about 3% by weight. Larger amounts can be difficult to disperse in mat compositions that would lead to inconsistency in the mats that are formed. The organic or polymeric fibers can be staple fibers or fibrillated fibers which are used to provide wet strength during processing and dry strength and resilience to layer and mat mounting materials prior to packaging. In use, the fibers burn within the first few cycles of low catalytic converter heating. Useful staple fibers range from about 0.5 to 5 deniers and can be formed from materials including acrylic, cellulose, polyolefin, polyvinyl alcohol and polyester. Suitable rayon fibers having a size of 1.5 denier per filament (dpf) are commercially available from sources such as Minifiber, Inc. of Johnson City, Tennessee. Suitable polyvinyl alcohol fibers are available from Kuraray Company, Ltd. under the trade name Kuralon ™ such as VPW 105-2x3 mm. When used, the staple fibers are useful in the range of about 1% to 5% and preferably between about 1.5% to about 2.5% for the mats. Fibrillated fibers such as those described in one or more of US Pat. Nos. 4,565,727, 4,495,030, 4,904,343, 5,866,107 and 4,929,502 are also useful. A preferred fiber is a highly fibrillated acrylic fiber pulp commercially available from Cytek Industries, Inc., West Paterson, New Jersey, under the tradename CFFMR. The fibrillated acrylic fibers have an arborescent structure with a trunk in the range of about 10 microns and fibrils in sizes ranging from a macro fibril down to fibrils to a few microns. The length of the fiber should be short enough so that it does not interfere with the mixing or forming process. Suitable fiber lengths include less than about 8 mm in length, and are typically in the range of about 6.5 mm. Preferably, the fibers are easily dispersible in aqueous systems. The arborescent morphology of the fibrillated fibers provides a mechanical interlacing of the fibers together, as well as a very high surface area. Both of these properties can be effectively used as a binder substance to trap and maintain the particulate materials of the mat composition, and improve the drainage proportions during the water-setting processes for the mats. When used, the fibrillated fibers are included in amounts of less than about 5% by weight, and preferably less than about 4%, and more preferably less than about 2%. Preferred amounts of fibrillated fibers provide compositions that mix well and drain well. The resulting mounting materials also exhibit good tensile strength and resilience for handling before packaging while minimizing the amount of organic material in the composition that would burn in the catalytic converter. Mat compositions are slurries that have large amounts of water, typically over 95%, and can be formed into layered materials by traditional, nonwoven, nonwoven papermaking techniques. In summary, this process includes mixing the components and pouring the slurry over a wire mesh or sieve to remove most of the water. The layered material formed is then dried with blotting paper and rolled to form a resilient mat. In another aspect, the invention provides a catalytic converter or a diesel particulate filter using the mounting material of the invention. A catalytic converter or particulate diesel filter generally comprises a housing, a monolithic structure or element (s), and a mounting material positioned between the structure and the housing to hold the structure in place. The housing that is also referred to as a can or cover can be made of suitable materials known in the art for such use and is typically made of metal. Preferably, the housing is made of stainless steel. Suitable catalytic converter elements, also referred to as monoliths, are known in the art and include those made of metal or ceramic. The monoliths or elements are used to support the catalytic materials for the converter. A useful catalytic converter element is described, for example, in U.S. Patent No. RE 21, 141 (Johnson). In addition, elements of ceramic catalytic converters are commercially available, for example, from Corning Inc. of corning, New York, and NGK Insulator Ltd. of Nagoya, Japan. For example, a ceramic cavernous catalyst support is marketed under the trade designation "CELCOR" by Corning Inc. and "HONEYCREAM" by NGK Insulator Ltd. Elements of the metal catalytic converter are commercially available from Behr GmbH and Co. . from Germany. For further details regarding the catalytic monolith see, for example, "Systems Approach to Packaging Design for Automotive Catalytic Converters," Stroom et al., Document No. 900500, SAE Technical Paper Series, 1990; "Thin Wall Ceramics as Monolithic Catalyst Supports", Howitt, Document No. 800082, SAE Technical Paper Series, 1980; and "Flow Effects in Monolithic Honerycomb Automotive Catalytic Converters," Howitt et al., Document No. 740244, SAE Technical Paper Series, 1974.

Catalytic materials coated within the elements of the catalytic converter include those known in the art (for example, metals such as ruthenium, osmium, rhodium, iridium, nickel, palladium and platinum and metal oxides such as vanadium pentoxide and titanium dioxide). ). For further details regarding catalytic coatings see, for example, U.S. Patent No. 3,441,381 (Keith et al.). Conventional monolithic particulate filter elements are typically wall flow filters comprised of crystalline, porous, cavernous ceramic material (eg, cordierite). The alternate cells of the cavernous structures are typically plugged such that the exhaust gas enters a cell and is forced through the porous wall of one cell and leaves the structure through another cell. The particle size of the diesel particulate filter depends on the particular application needs. Diesel particulate filter elements useful are commercially available, for example, from Corning Inc. of corning, New York and KGK Insulator Ltd. of Nagoya, Japan. In addition, particulate diesel particulate filter elements are described in "Cellular Ceramic Diesel Particulate Filter", Howitt et al., Document No. 810114, SAE Technical Paper Series, 1981. In use, the assembly materials of the invention are They place between the monolith and the housing in a similar way for either a catalytic converter or for a diesel particulate filter. This can be done by wrapping the monolith with a layered material of the mounting material and inserting the monolith wrapped in the housing, pumping the mounting material into a housing containing the monolith, coating the mounting material around the monolith, or molding the mounting material around the monolith and inserting the compound into the housing. The objects and advantages of this invention are further illustrated by the following examples, but the particulate materials and amounts thereof cited in these examples, as well as other conditions and details, should not be constructed to undoubtedly limit this invention. All parts and percentages are by weight unless stated otherwise.

TEST METHODS Cold Erosion Test This test is an accelerated test conducted under conditions that are more severe than the actual conditions, in a catalytic converter provides comparative data such as the erosion resistance of a mat mounting material. A test sample is cut into a square measurement of 2.54 cm by 2.54 cm, weighed and mounted between two high temperature Inconel 601 steel plates that use spacers to obtain a mounting density of 0.700 +/- 0.005 g / cm3 . The test assembly is then heated for two hours at 800C and cooled to room temperature. The cooled test assembly is then placed at 3.8 mm in front of an air jet that oscillates back and forth on the edge of the mat at 29 cycles per minute. The test is discontinuous after 0.2 grams of material is lost or after 24 hours, whichever comes first. The jet of air hits the mat at a speed of 305 meters per second. The erosion rate is determined by the weight loss divided by the time of the test and is reported in grams / hour (g / hr).

Test of the Device in Real Conditions (RCFT) The RCFT is a test used to measure the pressure exerted by the assembly material under conditions representative of real conditions found in a catalytic converter during normal use. Two heated plates of 50.8 mm by 50.8 mm independently controlled are heated to different temperatures to simulate metal housing and monolith temperatures, respectively. Simultaneously, the space or opening between the thick plates is increased by a value calculated from the temperature and coefficients of thermal expansion of a typical catalytic converter. The temperatures of the thick plates and the change of opening are presented in Table 1 below. The force exerted by the mounting material is measured by a load structure controlled by a Sintech ID computer with an Extensometer (MTS Systems Corp., Research Triangle Park, North Carolina).

Table 1 Plate Temperature Plate Temperature Change of Opening Thick Upper (° C) Thick Lower Í ° C) mm) 25 25 0 50 25 0 100 30 0 150 33 0 200 35 0 250 38 0 300 40 0 350 45 0 400 50 0 450 60 0 500 70 0 550 85 0.0127 600 100 0.0254 650 125 0.0381 700 150 0.0508 750 185 0.0762 800 220 0.1016 850 325 0.1651 900 430 0.2286 900 480 0.2667 900 530 0.3048 850 502 0.2921 800 474 0.2794 750 445 0.2540 700 416 0.2286 650 387 0.2159 600 358 0.2023 550 329 0.1905 500 300 0.1778 450 275 0.1651 400 250 0.1524 350 210 0.1270 300 180 0.1016 250 155 0.0889 200 130 0.0762 150 95 0.0508 100 60 0.0254 50 43 0.0127 25 25 0 Hot Shake Test The Hot Shake Test is used to evaluate a mounting material for a catalytic converter by attaching a catalytic converter with the assembly to the vibration and hot exhaust gas of a gasoline engine.

A catalytic converter, with the ceramic monolith mounted securely within it, is attached to a solid device on top of a shaker table (Model TC 208 Electrodynamic Sharker Table by Unholtz-Dickie Corp., Wallingford, Connecticut). The converter is then attached via a flexible coupling to the exhaust system of a 7.5-liter displacement 7.5-liter V-8 petrol driven internal combustion engine, Ford Motor Co. The converter is tested using an inlet exhaust temperature of 900C at a machine speed of 2200 rpm with a load of 30.4 kg-meter using an Eddy current dynamometer, Eaton 8121 while shaking the converter at 100 Hz and 30 g of acceleration of the shaking table. The converter is shaken for 100 hours and then disassembled and visually examined.

Flexibility Test This test is a measure of the flexibility and resilience of a mounting material, and is an indication of whether and how the material can be used as a layered material or a mat.

The test is conducted by taking a strip of 2. 54 cm wide of the material in dry layers or mat material and is wrapped 180 degrees around various diameters ranging from 9.5 mm to 203 mm. The smallest diameter was recorded when cracking occurred (openings of 1 mm to 2 mm begin to form on the mat material), and when cracking occurred (openings greater than 10 mm are formed, or complete separation of the mat occurs ).

EXAMPLES Example 1 A delaminated vermiculite composition was prepared by mixing 500 grams of expanded vermiculite (Zonolite # 5 available from WR Grace &Co.) and approximately 1400 milliliters of water in a 3.8-liter Baker Perkins Sigma Blade Mixer (one gallon) (Model 4 ANZ of Baker Perkins, now APV Chemical Machinery, Inc., Saginaw, Michigan) for 30 minutes. During mixing, the expanded vermiculite particles delaminated and had a gradient of particles ranging in size from very fine powder particles to thick platelets. The resulting material, which has a solids content of 26.7%, is then referred to as a ground expanded vermiculite (GEV). An intumescent mat composition was prepared by adding 2500 ml of water, 1.4 grams of polyvinyl alcohol binder fiber.

(PVA) (KuralonMRVPB 105 - 2x3 mm available from Kuraray Co., Ltd.), and 78.8 grams of GEV (26.7% solids) to a 3.8-liter warming mixer, and mix at a low speed setting for 10 seconds. After mixing, 0.36 grams of 0.65 micron diameter glass microfibers (Micro-strandMRMicro-FiberMR 106/465 available from Schuller) is added and mixed for another 10 seconds. Then 2.8 grams of rayon fibers of 1.5 dpf 6 mm (available from Minifiber, Inc.) were added and mixed for 15 seconds and 1.4 grams of 3 mm long, 11 micron diameter ceramic fibers (available NEXTELMR 312 fibers) from Minnesota Mining &; Manufacturing Co.) were added and mixed for 20 seconds. The resulting slurry was then transferred to a 4 liter flask using 500 ml of rinse water and mixed with an air blender having a plenum. During mixing, 43.2 grams of 18 mesh vermiculite ore (less than 1 mm in size) (available from Cometáis, Inc., New York, New York), 7 grams of alkali silicate granules (Expantrol ™ granules available from Minnesota Mining &manufacturing Co.) and 3 grams of a 1% solids solution of polyacrylamide flocculant (NalcoMR 7530 from Nalco Chemical Company, Chicago, Illinois) was added. The mixture was vigorously stirred and then quickly emptied into a mold of 20 cm x 20 cm 80 mesh screen layer material (Williams Apparatus Co., Watertown, New York). The valve in the mold was opened immediately to minimize the settlement of the particulates and the slurry was dehydrated. The surface of the layer material was then dried with paper and removed from the mold. The layered material was then interposed between additional blotting papers, pressed at 6 kiloPascals for 5 minutes, and dried in a layer dryer (Williams Apparatus Co.) For 45 minutes at 110C. The resulting layered material had a thickness of 2.5 mm. The dry layered material was tested by cold weathering according to the test method described above. The results of the Cold Erosion test are shown in Table 2, as well as the composition in percent dry weight (% by weight).

Example 2 Example 2 was prepared and tested as in Example 1 except that 0.18 grams of glass microfibers were added and 65.5 grams of GEV (26.7% solids) were used. The test data is shown in Table 2.

Example 3-6 Examples 3-6 were prepared and tested as in Example 1, except that the microfibers were omitted. The specific compositions and test results are shown in Table 2 and varying amounts of GEV and alkali silicate granules were used.

Comparative Example Cl This material was the well-accepted commercial product (Automotive Assembly Mat 100 Type INTERAMMR manufactured by Minnesota Mining &Manufacturing Co., St. Paul Minnesota).

Table 2 Example Materials-% in Weight in 3 4 5 6 C1 Dry PVA Binder Fiber 1.8 2.0 1.8 2.0 2.0 2.2 Rayon Fibers 3.6 4.0 3.6 4.0 4.0 4.4 NextelMR Fibers 1.8 2.0 1.8 2.0 2.0 2.2 Ore of Vermiculite 56.0 61.7 56.3 61.9 61.9 68.8 GEV 27.2 25.0 27.3 20.1 30.1 22.3 Glass Microfibers 0.5 0.3 0 0 0 0 ExpantrolMR 4BW 9.1 5.0 9.1 10.0 0 0 Cold Erosion (g / hr) 0.002 0.06 0.01 3 5 340 0.1 The data in Table 2 show that the amounts of GEV, Expantrol MR granules glass microfibers can be adjusted to improve the erosion resistance. Preferred compositions of the invention exhibit superior resistance to accelerated erosion as compared to a commercially accepted product.

Examples 7-11 The mats of Examples 7-11 were prepared as in Example 1 using the dry weight percent materials indicated in Table 3. Fibrillated acrylic fibers (CCFMR 114-3 Fibrillated Acrylic Fibers available from Cytec Industries Inc.) were added to Example 7; fibrillated fibers and glass fibers (S-2 Glass MTHT available from Owens-Corning Fiberglass Corp. were added to Examples 8-10, and for Example 11 fibrillated fibers and a combination of two different types of delaminated vermiculite were added (VFPSMR Vermiculite powder and Microlite ™ 903 vermiculite dispersion, both available from WR Grace &Co.) were used instead of GEV.

Table 3 Material Isthmg-% in Dry Weight 7 8 9 10 11 Fibrillated fibers 2.1 2.0 2.1 2.0 2.0 Rayon Fiber 2.1 2.0 2.1 2.0 2.0 Microfibers of glass 0 0.3 0.3 0.3 0.3 Fiberglass 2.1 2.0 2.1 2.0 2.0 Vermiculite ore 67.3 63.7 67.1 63.7 67.7 ExpantrolMR 4BW 0 5.0 0 5.0 5.0 GEV 26.4 25.0 26.3 25.0 0 Vermiculite VFPS R 0 0 0 0 20.0 MicroliteMR903 0 0 0 0 1.0 Cold Erosion Ratio 0.15 0.03 0.01 0.03 0.04 (g / hr) The data in Table 3 illustrates the superior erosion resistance of the preferred compositions of the invention.

Example 12-16 The mats were prepared as in Example 1 using the materials shown in Table 4. All the compositions of the mats include an organic binder substance (Aqueous emulsion of 44.5% solids of acrylic copolymers ("RHOPLEX HA-8")) in the% by dry weight of solids shown in the table. Mats for the Examples 13 and 14 included a partially dehydrated vermiculite (PVC) instead of vermiculite ore. The partially dehydrated vermiculite was prepared as described in Example 11 of U.S. Patent No. 5,254,410 (Langer et al.) The mats were tested for the erosion rate as well as the performance of the Real Condition Device Test. Test results are shown in Table 4.

Table 4 EiemDl 0 Materials-% in Dry Weight 12 11 la 15 16 C1 Rayon Fibers 4.5 4.5 5.5 4.5 2.0 Glass Microfibers 1.0 1.0 1.0 1.0 0.3 Glass Fibers 2.5 2.5 2.5 2.5 2.0 Vermiculite Ore 61.0 0 0 68.2 64.5 ExpantrolMR 4BW 0 0 5.0 0 0 GEV 28.5 28.5 27.0 21.4 26.5 PVD 0 61.0 56.0 0 0 Organic agglutinating substance 2.5 2.5 3.0 2.5 3.0 Cold erosion ratio 0.07 0.05 0.01 0.04 - 0.01 (g / hr) Peak Pressure RCFT KPa) 1140 950 690 1510 .. 1000 Cycle pressure 3rd RCFT (KPa) 70 140 140 140 70 The data in Table 4 show that good erosion results and RCFT test results show that the mounting materials maintain adequate clamping force.

Example 17 A mat mounting material was formed in a Fourdriner paper making machine using the composition of Example 9. The mat was approximately 1.6 mm thick and had a basis weight of 950 grams per square meter. Two rectangular mats were cut from the mat mounting material to completely wrap the side surfaces of two oval ceramic monoliths measuring 146 mm by 89 mm by 89 mm in length (obtained from Maremont Corp., Louden, Tennessee) were wrapped with the mats The two wrapped monoliths were placed in a can of the double-cavity catalytic converter (also obtained from Maremont Corp.). The density of the assembly was 1.1 grams per square centimeter. The converter was then tested according to the hot shake test. After 100 hours, the converter can was disassembled and the mounting material found to be in good shape, as is evident from the non-cracking of the monolith and the non-erosion of the mat. There was also no relative movement of the monolith in place of the can, which indicates that the mounting material securely holds the monolith in place under severe test conditions.

Example 18-23 The mats were formed using the compositions shown in Table 5 and using different mixers to mix the materials. Examples 18-20 were mixed as described in Example 1. The GEV in Examples 21-23 was mixed in a Ross mixer that includes both a planetary blade and a high shear dispersing blade (PD 4 Model Mixer available by Charles Ross &Son Co., Hauppauge, New York). Layered materials were tested for drainage time, tensile strength and elongation. The drainage time was determined from the time that the valve in the forming substance of the layered material was opened until the water was no longer visible on the surface of the formed mat. The tensile strength and elongation were determined in a Thwing Albert tension tester with a jaw spacing of 12.7 cm and a jaw separation speed of 2.54 cm / min.

Comparative Examples C2 and C3 The mats for Examples C2 and C3 were formed using the compositions described in Examples 1 and 3 of British Patent No. 1,522,646 (Wood), except that the compositions were formed in a test sheet former preferably that dehydrated with a filter paper. The examples were tested by drainage, flexibility, tension and elongation as in Examples 18-23. The test results are shown in Table 5.

Table 5 Example Materials-% in Weight 18 19 20 21. 22 23 C2 C3 Dry Rayon Fiber 2.0 2.0 2.0 2.0 2.0 2.0 Glass Microfibers 0.3 0.3 0.3 0.3 0.3 0.3 Glass Fiber 2.0 2.0 2.0 2.0 2.0 2.0 Vermiculite Ore 67.3 67.3 65.9 65.9 65.9 65.9 60 60 Fibers Fibrillated 0 2.0 2.0 2.0 2.0 2.0 GEV 26.3 26.3 25.8 25.8 25.8 25.8 * Coagulating substance 2.0 0 2.0 2.0 2.0 2.0 Organic Vermiculite # 5 Expanded - - - - - - 20.0 26.7 4 Fiberglass Code 106 - - - - - - 1.7 2.3 Ceramic Fibers - - - - - - 5.0 11.5 Bentonite - - - - - - 13.3 Drainage time (sec.) 10 10 20 20 75 37 500 17 Erosion Ratio in 1.2 - 5.9 7.2 1.0 2.1 Cold (g / hr) Voltage (Kpa) 226 230 284 296 405 371 168 98 Elongation (%) 2.3 - 1.3 2.2 1.8 2.1 0.5 0.7 Flexibility - diameter at 2.54 1.54 1.54 2.54 2.54 2.54 20.32 20.32 cracking - cm Flexibility - diameter at 0.95 0.95 0.95 0.95 0.95 0.95 12.7 12.7 cracking - cm * Vermiculite Powder Used VFPSMR ** Acrylic emulsion used (Airflex ™ 600BP DEV) available from Air Products and Chemicals, Inc., Allentown, Pennsylvania, an ethylene-vinyl acetate-acrylate terpolymer.

The data in Table 5 shows that the compositions of the invention have excellent drainage properties as compared to the prior art paste compositions, while having improved tensile strength and elongation, and significantly better flexibility. It will be apparent to those skilled in the art that various modifications and variations may be made in the method and article of the present invention without departing from the spirit or scope of the invention. Thus, it is proposed that the present invention covers the modifications and variations of this invention with the proviso that they come within the scope of the appended claims and their equivalents.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following:

Claims (12)

1. An intumescent, flexible layer material, characterized in that it comprises 20 to 80 percent by dry weight of at least one processed vermiculite, selected from ground expanded vermiculite and delaminated vermiculite, greater than 0 to 5 weight percent inorganic fibers having diameters greater than 5 microns, and more than 0 to 10 percent dry weight of organic fibers; wherein the layered material substantially does not comprise ceramic fibers of less than 5 microns.

2. The intumescent, flexible layer material characterized in that it also comprises amorphous organic oxide fibers having a diameter of less than about 2 microns.

3. The intumescent, flexible layer material according to claim 1 or 2, characterized in that the layer material comprises more than 0 to less than 1 percent by dry weight of amorphous organic oxide fibers having a diameter of less than about 2. mieras

4. The intumescent, flexible layer material according to claim 3, characterized in that the amorphous organic oxide fibers are glass fibers.

5. The flexible intumescent layer material according to any of claims 2 to 4, characterized in that the amorphous organic oxide fibers have a diameter of less than 1 miera.

6. The flexible intumescent layer material according to any of claims 1 to 5, characterized in that the layer material comprises from 0.1 to 5 weight percent dry weight of inorganic fibers having diameters greater than 5 microns.

7. The flexible, intumescent layered material according to any of claims 1 to 6, characterized in that the layered material comprises from 0.7 to 10 percent by dry weight of organic fibers.

8. The flexible, intumescent layered material according to any of claims 1 to 7, characterized in that the layered material additionally comprises more than 0 to 5 weight percent of an organic binder substance.

9. The flexible intumescent layer material according to any of claims 1 to 8, characterized in that the processed vermiculite is ground, expanded vermiculite.

10. The intumescent, flexible layer material according to any of claims 1 to 9, characterized in that the layered material comprises 2 to 5 percent fibrillated acrylic fiber.

11. The flexible intumescent layer material according to any of claims 1 to 10, characterized in that the organic fibers are rayon fibers.

12. A device for controlling pollution, characterized in that it comprises: (a) a housing. (b) a device for controlling the contamination placed inside the housing; and (c) the intumescent layer material of any of claims 1 to 10, the layered material is placed between the device for controlling the contamination.