BRPI0619832B1 - ASSEMBLY MATTER FOR A POLLUTION CONTROL DEVICE, POLLUTION CONTROL DEVICE AND METHOD FOR TREATING GAS EXHAUST GAS - Google Patents

Description

(54) Title: ASSEMBLY MAT FOR A POLLUTION CONTROL DEVICE, SAID

POLLUTION CONTROL DEVICE AND METHOD FOR TREATING THE EXHAUST GAS OF A DIESEL ENGINE (73) Holder: 3M INNOVATIVE PROPERTIES COMPANY, North American Company. Address: 3M CENTER, Ρ.Ο. ΒΟΧ 33427, ST. PAUL, MINNESOTA 55133-3427, UNITED STATES OF AMERICA (US) (72) Inventor: CLAUS MIDDENDORF; JUERGEN STRASSER; KNUT SCHUMACHER

Validity Term: 10 (ten) years from 10/02/2018, subject to legal conditions

Issued on: 10/02/2018

Digitally signed by:

Liane Elizabeth Caldeira Lage

Director of Patents, Computer Programs and Topographies of Integrated Circuits

1/26 “ASSEMBLY MAT FOR A POLLUTION CONTROL DEVICE, Said POLLUTION CONTROL DEVICE AND METHOD FOR TREATING THE EXHAUST GAS OF A DIESEL ENGINE”

Field of the Invention [001] The present invention relates to a support plate for supporting a pollution control element or monolith in a pollution control device. The invention also relates to a pollution control device comprising a support plate for supporting the pollution control element. The invention also relates to a machine with a pollution control device and a method for treating exhaust gas, in particular a diesel engine, with a pollution control device.

Background [002] Pollution control devices typically comprise a metal casing with a monolithic element securely fixed inside the compartment by a resilient and flexible mounting mat. Pollution control devices are universally used in motor vehicles to control air pollution. Generally, the pollution control device is designed according to the type of exhaust gas to be treated, as the composition of the exhaust, as well as the temperatures of the exhaust, can be different depending on the type of mechanism causing the exhaust. Consequently, pollution control devices are known to be used to treat the exhaust of gasoline engines as well as diesel engines. Pollution control devices include catalytic converters and particulate capture filters or devices. Two types of devices are currently used on a large scale - catalytic converters and filters or diesel particulate capture devices. Catalytic converters contain a catalyst, which is typically applied as a coating on a monolithic structure mounted inside a metal casingPetition 870180019655, 12/03/2018, p. 9/38

2/26 lico. Monolithic structures are typically ceramic, although metal monoliths have also been used. The catalyst oxidizes carbon monoxide and hydrocarbons, and reduces nitrogen oxides in automobile exhaust gases to control air pollution.

[003] Filters or devices for capturing diesel particles are typically wall flow filters, which have monolithic honeycomb structures, typically produced from porous crystalline ceramic materials. The alternating honeycomb cells are typically connected so that the exhaust gas enters a cell and is forced through the porous wall to an adjacent cell through which it can exit the structure. In this way, the small soot particles that are present in the diesel exhaust gas are collected.

[004] Monoliths and in particular ceramic pollution control monoliths used in pollution control devices are fragile and susceptible to damage and breakage due to vibration or shock. Generally, they have a coefficient of thermal expansion of an order of magnitude lower than the metal casing that contains it. This means that as the pollution control device is heated, the gap between the inner peripheral wall of the wrap and the outer wall of the monolith increases. Likewise, as the temperature of the pollution control device drops (for example, when the engine is turned off), this gap narrows. Although the metal casing undergoes a smaller temperature change due to the insulating effect of the plate, the higher coefficient of thermal expansion of the metal casing causes the casing to expand to a larger peripheral size faster than the expansion of the monolithic element. This higher coefficient of thermal expansion also causes the metal casing to shrink to a smaller peripheral size faster than the monolithic element. Thermal cycles and the resulting physical changes can occur hundreds or even thousands of times during life

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3/26 and the use of the pollution control device.

[005] Mounting mats are arranged between the pollution control element and the wrap to prevent damage to pollution control elements such as ceramic monoliths (for example, from shocks and vibrations on the roads), to compensate for the difference thermal expansion and to prevent the exhaust gases from passing between the monolith and the metal shell (thus avoiding the catalyst and / or filter). These mats can exert sufficient pressure to hold the pollution control element in place over the desired temperature range, but not so much pressure as to cause damage to the pollution control element (for example, a ceramic monolith).

[006] Many of the assembly belts described in the art have been developed to assemble the catalytic support of catalytic converters for the treatment of gasoline engine exhaust systems that typically operate at high temperature. Known assembly belts include intumescent laminated materials comprising ceramic fibers, intumescent materials and organic and / or inorganic binders. Intumescent laminated materials useful for supporting a catalytic converter in an enclosure are described, for example, in US Patent No. 3,916,057 (Hatch et al.), 4,305,992 (Langer et al.) 5,151,253 (Merry et al.) 5,250,269 (Langer) and 5,736,109 (Howorth et al.). In recent years, non-intumescent mats comprising ceramic fibers and polycrystalline binders have been used especially for so-called ultra-thin wall monoliths, which have significantly lower strength due to their extremely thin cell walls. Examples of non-intumescent mats are described, for example, in US Patent No. 4,011,651 (Bradbury et al.), 4,929,429 (Merry), 5,028,397 (Merry), 5,996,228 (Shoji et al.), and 5,580,532 (Robinson et al.). Polycrystalline fibers are much more expensive than normal ceramic fibers made of molten material and therefore mats with these fibers are used only when they are absolutely necessary, for example,

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4/26 with ultra-thin wall monoliths.

[007] US 5,290,522 describes a catalytic converter containing a non-woven assembly mat, comprising at least 60% by weight of high strength magnesium aluminum silicate glass fibers free of non-fibrous materials with a diameter greater than 5 micrometers. The assembly tracks shown in this reference are designed primarily for use in high temperature applications as can be seen from the test data in the examples where the tracks are subjected to exhaust gas temperatures of over 700 ° C.

[008] US 5,380,580 describes a flexible non-woven mat comprising free oxidized ceramic fibers of non-fibrous material selected from a group consisting of (a) aluminosilicate fibers comprising aluminum oxide in the range of 60 to about 85%, in weight, and silicon oxide in the range of 40 to about 15% by weight, based on the total weight of said aluminosilicate fibers, said aluminosilicate fibers being at least 20% crystalline, by weight, (b) crystalline quartz fibers and (c) mixtures of (a) and (b) and thus the combined weight of said aluminosilicate fibers and said crystalline quartz fibers is at least 50%, by weight, of the total weight of said non-woven mat. The flexible non-woven mat may additionally comprise high strength fibers selected from the group consisting of silicon carbide fibers, silicon nitride fibers, carbon fibers, glass fibers, stainless steel fibers, brass fibers, fibers ephemeral and mixtures thereof.

[009] Diesel Oxidation Catalysts (DOCs - Diesel Oxidation Catalysts) are used in modern diesel engines to oxidize the organic soluble fraction (SOF soluble organic fraction) of the emitted diesel particulate. Because of the relatively low exhaust gas temperatures, mounting DOCs with conventional mounting materials has been problematic. The exhaust gas of diesel engines moPetição 870180019655, dated 12/03/2018, p. 12/38

5/26 dernos, such as turbocharged direct injection (TDI) engines, can never exceed 300 Ό. This temperature is below the temperature required to expand most intumescent mats. This expansion is necessary to develop and maintain adequate pressure in the catalytic converter.

[0010] US 6,231,818 attempts to overcome the present difficulties in assembling low temperature diesel catalysts, using non-intumescent belts that comprise amorphous and inorganic fibers. Although it is shown in this patent that the mat can be free of organic binder, it shows that many of the mats used in the examples require the use of substantial amounts of binder. In addition, it has been found that the assembly tracks presented in this U.S. patent still do not adequately perform the exhaust treatment of diesel engines, in particular TDI engines.

[0011] EP 1388649 discloses a pollution control device suitable for use with a diesel engine, comprising a diesel pollution control monolith disposed in a metallic enclosure with a non-woven mat arranged between the metallic enclosure and the monolith of diesel pollution control. The nonwoven mat is a non-swelling mat comprising at least 90% by weight, based on the total weight of the mat, of ground magnesium aluminum silicate glass fibers, which has a diameter with a numerical average of 5 pm or more and a length of 0.5 to 15 cm and the glass fibers are needle-pierced or needled (stitch-bonded) and the mat is free or substantially free of organic binder.

Summary [0012] While the assembly belts presented in the prior art can provide good retention properties for diesel pollution control monoliths, there is still a need to further optimize the assembly mat, in particular resilience and strength retention at low temperaturePetition 870180019655, of 12/03/2018, p. 13/38

6/26 rature would desirably be improved.

[0013] It would be even more desirable to obtain such improved assembly mats manufactured in an easier and more convenient way and at a lower cost. Additionally, it would be desirable to find assembly mats that show good to excellent performance in at least one or more of the following tests: Real Fixture Test (RCFT), Cyclic Compression Test, and Vibration Test at Warm. Desirably, the assembly mat also has good qualities regarding health, safety and the environment.

[0014] In one aspect, the invention features a mounting mat for mounting a pollution control element or monolith on a pollution control device, with said mounting mat comprising a layer with a mixture of long and inorganic fibers short, with short fibers having a length of no more than about 13 mm and long fibers having a length of at least about 20 mm and the amount of short fibers being at least about 3% , by weight, based on the total weight of said mixture of long and short fibers.

[0015] In a specific embodiment, the mixture of long and short fibers is a mixture of long and short ceramic fibers that are formed and cut continuously or otherwise segmented (for example, by breaking fibers in the subsequent fiber or belt processing) to a desired length.

[0016] In a specific embodiment of the present invention, the assembly mat comprises a layer with at least about 90% by weight, based on the total weight of the layer, of magnesium aluminum silicate glass fibers, with the glass fibers comprising a mixture of long and short fibers with short fibers having a length of no more than about 13 mm and

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7/26 being that the long fibers have a length of at least about 20 mm and the amount of short fibers is at least about 3% by weight, based on the total weight of the glass fibers.

[0017] The assembly mat has been found to have beneficial properties in the assembly of pollution control elements or monoliths and, in particular, in a diesel pollution control element. For example, the cold holding force, as measured by the compression test shown in the examples, can be improved. It is desirable that the present assembly belts comprise such longer and shorter fibers, to exhibit results in static compression tests of at least about 200 kPa and, preferably, at least about 250 kPa. In addition, good results can be achieved in the hot vibration test with the mounting belts present.

[0018] In another aspect, the invention presents a method for manufacturing an assembly mat. The method comprises: providing a plurality of continuously formed inorganic fibers; segmentation of inorganic fibers formed continuously into long and short fibers, with short fibers having a length of no more than about 13 mm and long fibers having a length of at least about 20 mm; combining long and short fibers to form a mixture of fibers and forming an assembly mat using the mixture of long and short fibers. The segmentation step may comprise the breaking of long and short fibers in the fiber mixture during the stage of forming the assembly mat, to produce at least one of the short fibers with a length of no more than about 13 mm and the long fibers having a length of at least about 20 mm. The segmentation step can also comprise shredding of inorganic fibers continuously into long and short fibers to produce at least one of the

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8/26 short fibers with a length of no more than about 13 mm and long fibers with a length of at least about 20 mm. The method can also comprise shredding of inorganic fibers formed continuously in lengths longer than desired, before performing the segmentation operation.

[0019] In another aspect, the invention features a pollution control device comprising a pollution control element or monolith disposed in a compartment or enclosure with a mounting mat arranged between the compartment and the pollution control element, being that the mounting belt is a mounting belt as defined above.

[0020] In yet another aspect, the invention features a machine comprising a diesel engine and a pollution control device as defined above.

[0021] In yet another aspect, the invention features a method for treating exhaust gas for a diesel engine, which submits the exhaust gas to a pollution control device as defined above.

[0022] The term 'diesel pollution control element' means a structure that is suitable for and / or adapted to reduce pollution caused by the exhaust of a diesel engine and includes, in particular, monolithic structures that are operational in reducing pollution at low temperatures of, for example, 350 Ό or less. Diesel pollution control elements include, without limitation, catalyst supports, diesel particulate filter elements, and NOx absorbers or capture devices.

[0023] The term 'aluminum and magnesium silicate glass fibers' includes glass fibers comprising oxides of silicon, aluminum and magnesium without excluding the presence of other oxides, in particular, other metal oxides.

Brief Description of Drawings

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9/26 [0024] For the purpose of illustration and better understanding of the invention only, and without the intention to limit the invention in any way, the following drawings are provided:

[0025] Figure 1 is a perspective view of a catalytic converter of the present invention shown in a disassembled form.

Detailed Description of the Modalities [0026] With reference to Figure 1, the pollution control device 10 comprises a metallic enclosure 11 with generally frusto-conical inlet and outlet ends 12 and 13, respectively. A pollution control monolith 20 is arranged within housing 11. According to a specific embodiment of the invention, pollution control monolith 20 is a diesel pollution control monolith formed, for example, by a monolithic body divided as a hive, with a plurality of gas flow channels (not shown) through it. The pollution control monolith 20 can also be one that is adapted for the treatment of gasoline engine hoods. The assembly mat of this invention is, however, particularly suitable for use with diesel pollution control monoliths and the invention will thus be described in more detail in relation to the treatment of diesel engine exhaust without, however, the intention to limit the invention. Surrounding the diesel pollution control monolith 20 is the assembly mat 30, comprising a layer of long and short inorganic fibers, for example, long and short cut or otherwise segmented aluminum silicate glass fibers (for example, by breaking fibers in the subsequent fiber or in the processing of the belt), which serve to firmly but resiliently support the monolithic element 20 without the casing 11. The mounting belt 30 supports the diesel pollution control monolith 20 in the place in the enclosure and closes the gap between the diesel pollution control monolith 20 and the enclosure 11 provides for Petition 870180019655, of 12/03/2018, p. 17/38

10/26 thereby reducing or minimizing the direct passage of diesel exhaust gases through the diesel pollution control monolith 20.

[0027] The metallic compartment can be produced from materials known in the art for such use, including stainless steel.

[0028] Examples of diesel pollution control monolith for use in pollution control device 10 include catalytic converters and filters for diesel particulates. Catalytic converters contain a catalyst, which is typically applied as a coating on a monolithic structure mounted within a metallic shell. The catalyst is typically adapted to be operational and effective at low temperature, typically not more than 350 ° C. Monolithic structures are typically ceramic, although metal monoliths have also been used. The catalyst oxidizes carbon monoxide and hydrocarbons, and reduces nitrogen oxides in the exhaust gases to control air pollution. While in a gasoline engine, all three of these pollutants can react simultaneously in a so-called three-way converter, most diesel engines are equipped with only one catalytic oxidation converter. Catalytic converters for reducing nitrogen oxides, which are used to a limited extent in diesel engines today, generally consist of a separate catalytic converter. Suitable ceramic monoliths used as catalyst assemblies are commercially available from Corning Inc. (Corning NY, USA) under the trade name CELCOR and commercially available from NGK Insulated Ltd (Nagoya, Japan) under the trade name HONEYCERAM, respectively.

[0029] The filters or devices for capturing diesel particulates are typically wall flow filters, which have honeycomb-shaped monolithic structures, typically produced from porous crystalline ceramic materials. The alternating honeycomb cells are typically linked so that the gas

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11/26 escape enters a cell and is forced through the porous wall to an adjacent cell through which it can exit the structure. In this way, the small soot particles that are present in the diesel exhaust gas are collected. Suitable diesel particle filters made from cordierite are commercially available from Corning Inc. (Corning N.Y., USA) and NGK Insulated Inc. (Nagoya, Japan). Diesel particulate filters made from Silicon Carbide are commercially available from Ibiden Co. Ltda. (Japan) and are described in, for example, JP 2002047070A.

[0030] The fibers of the long and short fiber blend are preferably non-breathable. The fibers typically have an average diameter of at least 5 pm. Preferably, the average diameter will be at least 7 pm and is typically in the range of 7 to 14 pm. Generally, the mixture of long and short fibers is a mixture of ceramic fibers formed in a continuous manner, for example, glass fibers. Typically, short fibers have a length of not more than 13 mm, for example not more than 10 or 8 mm. Long fibers typically have a length of at least 20 mm, for example, at least 25 mm or, in a specific embodiment, at least 30 mm. The maximum length of the long fibers is not particularly crucial, but it is conveniently up to about 15 cm. The amount of short fibers is typically at least 3% by weight, based on the total weight of the mixture of long and short fibers, for example, at least 5% by weight, or in a specific embodiment, of at least 6% by weight. Typically, the blend of long and short fibers will constitute at least 50% by weight of the fibers in the layer, for example, at least 80% by weight, and can typically be 90 or about 100% by weight , of the total weight of fibers in the layer. Generally, it will be necessary for the short fibers to be distributed homogeneously through the fiber layer. By 'homogeneous', in this context, it should be understood that there is not just one area, or just a small amount of areas in the layer where the short fibers are concentrated. In other words, the bedPetition 870180019655, of 03/12/2018, p. 19/38

12/26 of the fiber should appear completely uniform. However, a non-uniform or heterogeneous distribution of short fibers in the layer can also be used, but then it will generally be necessary to use a large amount of short fibers to obtain the previously mentioned advantages.

[0031] The layer comprising the mixture of short and long fibers may contain other fibers, including fibers with a length between 13 and 20 mm. In a specific embodiment, the mixture of short and long fibers is a mixture of glass fibers, in particular, a mixture of aluminum and magnesium silicate glass fibers. In a specific embodiment, the fiber layer of the assembly mat comprises a mixture of short and long glass fibers of aluminum and magnesium silicate, which constitute at least 50%, by weight, of the total weight of the fibers in the layer of the mat. Assembly. In a specific embodiment, the amount of mixing is at least 60% or at least 80% and, in a typical embodiment, substantially the entire layer of fibers (90 to 100%) is made up of the mixture of short glass fibers and long lengths of aluminum silicate.

[0032] The fibers are preferably individualized. To supply individualized fibers (ie separate each fiber from one another), a crude fiber or a strand of fibers can be cut, for example, using a mobile glass cutter (commercially available, for example, under the trade name MODEL 90 MOBILE GLASS CUTTER from Finn & Fram, Inc., Pacoma, Calif., USA), to the desired length. The fibers are typically free of non-fibrous material, or contain a low amount of non-fibrous material, typically less than 1% by weight based on the total weight of the fibers. In addition, the fibers are typically reasonably uniform in diameter, that is, the amount of fibers with a diameter within an average of +/- 3 pm is generally at least 70% by weight, preferably at least 80%, by weight, and more preferably at least 90%, by weight, of the total weight of the fibers.

[0033] The mat may comprise a mixture of different fibers, for example, 870180019655, from 12/03/2018, p. 20/38

13/26 pio, a mixture of aluminum and magnesium silicate glass fibers with other fibers such as aluminum silica fibers or polycrystalline fibers. Preferably, however, the mat will confine only substantially all or almost all aluminum and magnesium silicate glass fibers. If other fibers are confined to the mat, they may be contained in the short and long fiber blend layer, or they may be present in a separate layer or portion of the assembly mat. Generally, other fibers, other than aluminum and magnesium silicate glass fibers, will be amorphous fibers and they should also preferably have an average diameter of at least 5 pm. Preferably, the mat will be free or essentially free of fibers having a diameter of 3 pm or less, more preferably, the mat will be free of or essentially free of fibers having a diameter of less than 5 pm. Essentially exempt here means that the amount of fibers of such a small diameter is not more than 2% by weight, preferably not more than 1%, by weight, of the total weight of the fibers on the mat.

[0034] Examples of aluminum and magnesium silicate glass fibers that can be used in this invention include glass fibers having between 10 and 30% by weight of aluminum oxide, between 52 and 70% by weight of oxide silicon and between 1 and 12% magnesium oxide. The percentages by weight of the oxides mentioned above are based on the theoretical amount of AI2O3, S1O2 and MgO. It will be understood later that the aluminum and magnesium silicate glass fiber may contain additional oxides. For example, additional oxides that may be present include sodium or potassium oxides, boron oxide and calcium oxide. Specific examples of aluminum and magnesium silicate glass fibers include E glass fibers which typically have a composition of about 55% S1O2, 11% AI2O3, 6% B2O3, 18% CaO, 5% MgO and 5% of other oxides; S and S-2 glass fibers that typically have a composition of about 65% S1O2, 25% AI2O3 and 10% MgO, and R glass fibers that typically have a composition of

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14/26

60% S1O2, 25% AI2O3, 9% CaO and 6% MgO. E glass, S glass and S-2 glass are available, for example, from Advanced Glassfiber Yarns LLC and R glass is available from Saint-Gobain Vetrotex.

[0035] In a particular method for the production of the assembly mat, the fibers can be cut or chopped and then separated by passing them through a conventional two-zone Laroche Esfarrapadeira (commercially available, for example, next to the Laroche SA, Cours la Ville, France). The fibers can also be separated by passing them through a hammer mill, preferably a windmill with a wind discharge hammer (for example, commercially available under the trade name MOVING HAMMER WITH MODEL 20 WIND DISCHARGE from CS Bell Co. of Tiffin, Ohio, USA conventional two zone Laroche Opener). Although less efficient, the fibers can be individualized using a conventional fan such as those commercially available under the commercial designation DAYTON RADIAL FAN, Model 3C 539, 31.1 cm (12.25 inches), 3 horsepower, from WW Grainger of Chicago, Illinois, USA Chopped fibers usually need to be passed through the Laroche skimmer only once. When using a hammer mill, they usually need to pass through it twice. If a fan is used alone, the fibers are typically passed through it at least twice. Preferably, at least 50 weight percent of the fibers are individualized before they are molded into a layer of the assembly mat. It has been found that such a separation process can also be used to segment or break fibers longer than desired in desired lengths.

[0036] According to a method for the production of assembly mats, chopped and individualized fibers are supplied to a conventional blanket forming machine (commercially available, for example, under the designation

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15/26 commercial RANDO WEBBER by Rando Machine Corp. Macedon, N.Y., USA; or DAN WEB from ScanWeb Co. of Denmark), where the fibers are passed to a wire mesh or mesh mat (for example, a metallic or nylon mat). If a DAN WEB blanket forming machine is used, the fibers are preferably individualized using a hammer mill and then a fan. Fibers with a length greater than about 2.5 cm tend to be interwoven during the process of forming the blanket. To simplify the treadmill's ease of handling, the treadmill can be mounted on or placed on a screen. Depending on the length of the fibers, the resulting belt typically has sufficient handling capacity to be transferred to a needle punch machine without the need for a support (for example, a screen).

[0037] The inventive mixture of short and long fibers can be achieved by feeding a blanket forming machine with a mixture of the desired short and long fibers. Alternatively, only fibers longer than the desired ones can feed the blanket forming machine and the conditions for individualization and / or blanket formation will be defined in such a way as to deliberately cause rupture of certain amounts of fibers rather than establishing conditions that prevent rupture. of fibers as is normally the case. The method of segmentation or local breakdown of fibers is particularly suitable for generating a homogeneous distribution of fibers in the fiber layer. However, it is also possible to feed the blanket formation process with a desired mixture. In addition, a combination of feeding a mixture of the desired short and long fibers and conditions that cause a certain amount of fibers to rupture longer than the desired fibers can be used.

[0038] The rupture or other segmentation of fibers in the manufacture of assembly mats can be caused by the application of tension to the individual fibers, for example, feeding fiber filaments (bundles) through a gap, misunderstanding 870180019655, of 12 / 03/2018, p. 23/38

16/26 by calling the fibers in the gap while quickly rotating the lickerin roller, or by using a lickerin roller with pins or teeth that cause fiber breakage. The rupture of fibers can be caused in one or both stages of linting or formation of the blanket.

[0039] In a specific embodiment, the assembly mat is a non-woven mat pierced by needle. A needle-punched non-woven mat refers to a mat that has physical interlacing of the fibers supplied produced by total or partial (preferably total) multiple penetration of the mat, for example, by pointed needles. The non-woven mat can be needle-punched using a conventional needle-piercing device (for example, a commercially available needle punch under the trade name DILO from Dilo Germany, with pointed needles (commercially available, for example). example, with the Foster Needle Company, Inc., of Manitowoc, Wis., USA)) to provide a needle-punched non-woven mat. Needle piercing, which provides fiber entanglement, typically involves compressing the belt and then drilling and removing pointed needles through the belt. The ideal number of needle perforations per belt area will vary depending on the specific application. Typically, the non-woven mat is needle punched to provide about 5 to about 60 needle punches / cm ² . Preferably, the mat is needle punched to provide about 10 to about 20 needle punctures / cm ² .

[0040] Preferably, the needle-punched non-woven mat has a weight value per unit area in the range of about 1,000 to about 3,000 g / m ² , and in another aspect, a thickness in the range of about from 0.5 to about 3 centimeters. A typical bulk density less than a load of 5 kPa is in the range of 0.1 - 0.2 g / cm ³ .

[0041] The non-woven mat can be needled (stitch-bonded), using

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17/26 conventional techniques (see, for example, U.S. Patent No. 4,181,514 (Lefkowitz et al.), The description of which is incorporated herein by reference to the needling of non-woven mats). Typically, the mat is needled (stitch-bonded) with an organic thread. A thin layer of a sheet of organic or inorganic material can be placed on one or both sides of the mat during needle joining to prevent or minimize the threads from crossing the mat. Where it is desired that the suture does not decompose in use, an inorganic thread such as ceramic or metallic (for example, stainless steel) can be used. The spacing of the stitches is usually 3 to 30 mm, so that the fibers are compressed evenly across the entire area of the mat.

[0042] According to a specific embodiment of the present invention, the mat can be formed by a plurality of layers of aluminum and magnesium silicate glass fibers, with at least one of them having a mixture of short and long fibers. Such layers can be distinguished from each other by the average diameter of the fibers used, the length of the fibers used and / or the chemical composition of the fibers used. Since the heat resistance and the mechanical resistance of the fibers at temperature varies according to their composition and, to a lesser extent, to the fiber diameter, fiber layers can be selected to improve performance, while decreasing the cost. For example, a non-woven mat consisting of a layer of S-2 glass combined with a layer of E glass can be used to assemble a diesel catalytic converter. In use, the S-2 glass layer is placed directly against the warmer monolith side of the catalytic converter, while the E glass layer is against the cooler metal casing side of the catalytic converter. The layer combination mat can withstand considerably higher temperatures than a mat consisting only of E glass fibers, at very reduced costs compared to mats consisting only of S-2 glass fibers. Layered mats are made first by forming individual layers

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18/26 non-woven fabrics having a specific type of fiber using forming techniques previously described in this document. These layers are then connected to each other by needles to form the final mat with the desired desired layers.

[0043] The mounting belts of the invention are particularly suitable for mounting a diesel pollution control monolith in a pollution control device. Typically, the mat assembly density, that is, the apparent mat density after assembly, should be at least 0.2 g / cm ³ to provide sufficient pressure to hold the monolith securely in place. At assembly densities above about 0.70 g / cm ³ the fibers can be unduly pressed. In addition, at high mounting densities, there may be a risk that the monolith will break when installing the pollution control device. Preferably, the mounting density should be between about 0.25 g / cm ³ and 0.45 g / cm ³ . The pollution control device has excellent performance characteristics for use in low temperature applications, such as exhaust treatment of diesel engines. The pollution control device can be used on a stationary machine to treat the exhaust from a diesel engine contained therein. Such stationary machines include, for example, energy sources for producing electricity or pumping fluids.

[0044] The pollution control device is suitable, in particular, for the exhaust treatment of diesel engines in motor vehicles. Examples of such motor vehicles include 'low capacity' trains, buses, trucks and passenger vehicles. 'Low capacity' passenger vehicles means a motor vehicle that is designed to carry a small number of passengers, typically no more than 15 people. Examples of these include cars, vans and so-called minivan cars. The pollution control device is particularly suitable for exhaust treatment of engines with direct injection turbine system (TDI) which are more and

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19/26 most frequently used in motor vehicles, particularly in Europe.

[0045] The following examples illustrate the invention in more detail, but without the intention of limiting the scope of the invention.

Examples

Materials Used in the Examples [0046] Glass fibers R (RC-10 P109) of approximately 10 pm average diameter and 36 mm in length were used, (obtained from Saint-Gobain Vetrotex França SA, Chambery Cedex, France.)

Test Methods

Fiber Length Measurement [0047] A fiber length measurement was made on samples of the mats prepared in the examples to determine the amount of fibers less than 12.7 mm in length.

[0048] The test equipment comprised a balance to detect the weight of the samples, an area where the fiber bundles were separated for individual fiber measurement and an area where the individual fibers were transported pneumatically through an optical sensor. The specific device employed was a measuring device commercially available under the name Advanced Fiber Information System Model (AFIS - Advanced Fiber Information System9) (USTER Technologies AG, Uster, Switzerland). The instrument was used in module L mode to measure the fiber length. The machine was calibrated using polyester fibers of known length.

[0049] Ten fiber samples, each weighing about 0.5 g, were taken off the mat to be tested. Each sample was then weighed on the AFIS test equipment. The sample was then placed manually on the transport strip, with the fiber bundle oriented so that the fibers were parallel to the transport direction.

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20/26 [0050] The fibers were automatically supplied to the separation zone where a counter carding cylinder containing fine needles separated the fiber bundles into single fibers. The fibers were then transported pneumatically, by means of an air flow with a defined speed, through an infrared optical sensor. This sensor detected the number of single fibers and their lengths. The measurement ended after 3,000 fibers were detected.

[0051] The test results were shown by means of a graph showing the fiber frequency (%) in contrast to the fiber length (mm). From the graph, the percentage of fibers less than 12.7 mm in length was obtained using software integrated with the AFIS system. The average of the ten measurements was calculated and reported. The reported percentage was based on W, the average fiber length based on weight.

Static Compression Test [0052] A static compression test was conducted under ambient conditions on the conveyors prepared in the examples to determine their compressive strength. The test equipment comprised two anvils that could advance against each other, thereby compressing the sample mat that was placed between them. The specific device employed was a material testing system Model RT / 30 (available from MTS Allience ™, Eden Prairie MN, USA). The device was equipped with a 5kN load cell to measure the resistance of the sample mat to compression, and with a height measurement device to measure the thickness of the sample in various stages of compression.

[0053] Samples were prepared by taking circular die cuts with a diameter of 50.8 mm from the complete assembly mat. Three samples were taken at equally spaced intervals along the width of the mat, at least 25 mm from the edge. The distance between the samples was at least 100 mm. Each sample had an area weight of about 1300 g / m ² (+/- 15%). The test

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21/26 was conducted using the following procedure. Each sample was weighed first. Then, the weight per area of each sample was calculated, dividing the weight of the sample by the sample surface area (calculated from the known diameter of 50.8 mm), and recorded in g / mm ² .

[0054] The gap between the anvils that was necessary to reach a final compression density of 0.40 g / cm ³ was then calculated. This is the desired density where the compressive strength will be measured.

Calculation example:

Weight per area in g / cm ²

Gap size in cm = ......................

Initial density in g / cm ³ [0055] Thus, a sample with an area weight of 1300 g / m ² and an initial density of about 0.15 g / cm ^{3 would} need to be compressed to a thickness of 0.325 cm (3.25 mm) to obtain a final density of 0.4 g / cm ³ . The sample was then placed on the lowest anvil of the test equipment. The gap between the anvils was then closed at a rate of 25.4 mm per minute, starting at a distance of 20 mm between the anvils. The anvil advance was then stopped in the gap between the anvils that was calculated above.

[0056] After a 45-second compression period at the calculated gap distance, the compressive strength was measured and recorded in kPa.

Example 1 [0057] R P109 glass fibers of approximately 10pm of average diameter and 36 mm in length were obtained from Saint-Gobain Vetrotex France SA, Chambery Cedex, France. The fibers were essentially free of non-fibrous material.

[0058] A quantity of 40 kg of glass fibers was shredded in a La Roche skidder with an ückerin roller equipped with pins. The filaments

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22/26 the second zone was fed directly at a feed speed of 3 m / min and a lickerin roller speed of 2,000 rpm. The exit speed was 6.0 m / min. The tattered fibers were then fed to a conventional blanket forming machine Rando weaving machine and the fibers were blown into a porous metal cylinder to form a continuous blanket. The lickerin roller had teeth, the lickerin speed was 1,900 rpm, the elevator speed was 300 rpm, the separator speed was 350 rpm. The cylinder feed speed was 1.1 rpm, the feeder depression was 51.7 kPa (7.5 psi), the weave depression was 48 kPa (7 psi). The lid opening was 30 mm. The line speed was 1 m / min.

[0059] The continuous blanket was then connected by needle in a conventional needle tacker. The needle type was GB15x16x3 ¹ / 2R222G53047 (GrozBeckert Group, Germany). The needle density was 1.2 needles per cm ² randomized with an upper board graduation of 19. The needle board worked from the top with a needle frequency of 100 cycles / min. The inlet speed was 1 m / min and the outlet speed was 1.05 m / min. The penetration of the needles was 10 mm, the product had a density of 24 perforations per cm ^2, the base weight of Rando was 1,000 g / m ² [0060]. however, it was very aggressive due to the fact that the lickerin roller with teeth was used instead of the pin. This resulted in a percentage of 10.5 of the fibers having a length less than 12.7 mm.

[0061] Table 1 summarizes the process parameters for the production of example 1. Also in Table 1 there is an amount in% of fibers with a length less than 12.7 mm, measured following the test method described above. In Table 1, the process parameters for each example were classified as mild, moderate or aggressive, regardless of the process step where

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23/26 most of the disruptions were caused. The result of the static compression test can be found in Table 1.

Example 2 [0062] Example 2 was prepared by the method described in Example 1 except that a pre-skidder and a La Roche fine skidder were used, each having a lickerin roller equipped with pins.

[0063] The rotational speed was 2,000 rpm for both polishing cylinders, the gap in the pre-skimmer was 0.8 mm, the fine skimmer gap was 2 mm for example 2. The used weaving machine for the production of example 2 it was a La Roche weaving machine in which the lickerin roll was equipped with pins. The rotation speed was 2,000 rpm. The line speed was 2.4 m / min.

[0064] The needling process was done in a Dilo ™ tacker with an upper and lower board. The penetration depth was 15 mm, the frequency of needles was 330 perforations per minute. The speed of the tacking line was 3 m / min.

[0065] The polishing process was carried out under aggressive conditions, obtained by small gaps between the stuck fibers and the lickerin roller pins in both polishing steps. The individual fibers are hit most effectively by the lickerin roll pins while being fed through a small gap. The formation of the blanket, however, was designed to prevent fiber breakage due to the fact that the lickerin roller with pins was used instead of the one with teeth. The Uster AFIS test method showed 6.5% of the fibers less than 12.7 mm in length. Example 2 was tested using the Cold Compression Test as described above. The results are summarized in Table 1.

Example 3 [0066] 0 Example 3 was prepared using the method described in Example 2,

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24/26 except that the gap in the first skidder was 2 mm and the gap in the second skidder was 3 mm.

[0067] The formation of the blanket, as well as the splicing with needles, was processed by the same method as described in Example 2, except for the fact that the needle frequency was 300 perforations per min.

[0068] The ragging process was carried out under moderate conditions, obtained by moderate gap openings in both ragging steps. Small gaps of 2 mm and 3 mm caused less fiber breakage than in the example

2. This can be observed using the Uster AFIS test method, resulting in 4.3% of fibers less than 12.7 mm in length.

[0069] Example 3 was tested in a cold compression test as described above. The results are summarized in Table 1.

Example 4 [0070] 0 Example 4 was prepared by the method described in Example 2 except that the chisel was fed with a fiber mixture consisting of 80% by weight of glass fibers R, with a diameter of about 10 pm, cut to a length of 36 mm (1.5 inches), (obtainable as dispersible cut glass filaments R available from Saint-Gobain Vetrotex France SA, Chambery Cedex, France,) and 20% by weight of fibers R-, about 10 pm in diameter, cut to a length of 12 mm (0.5 inches), (obtainable from the same supplier).

[0071] The formation of the blanket as well as the splicing by needles was done by the same method described in Example 2. The process parameters were summarized in Table 1.

[0072] The mechanical stress on the fibers in the 0.8 mm and 2 mm gaps is similar to that described in Example 2.

[0073] Example 4 was tested in the cold compression test described above.

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The results are summarized in Table 1.

Example 5 [0074] Example 5 was prepared by the method described in Example 2, except that the fibers were aggressively pre-ragged through a third rag, before being processed through the first and second rag, the gap in this the first skidder was 3 mm and the gap in the second skidder was 4 mm. The third skimmer was fitted with a 1.0 mm gap and was made by the same manufacturer as the skimmer 2 (commercially available from Laroche S.A., Cours la Ville, France), but uses twice the number of pins found in the skimmer 2.

[0075] The formation of the mat as well as the needle splicing was done by the same method described in Example 2. The process parameters of example 5 were summarized in Table 1.

[0076] Example 5 was subjected to the cold compression test described above. The results are summarized in Table 1.

Comparative example 1 [0077] Comparative example 1 was prepared by the method described in Example 3, except that the gap in the first mat was 3 mm, and the gap in the second mat was 4 mm.

[0078] The formation of the mat as well as the adhesion by needle was done by the same method described in Example 3.

[0079] The ragging process was done under mild conditions, obtained by wide gaps in both ragging processes. The stress that occurred in the 3 mm and 4 mm gaps caused less fiber breakage than in examples 2 and 3. The process parameters of comparative example 1 were summarized in Table 1. The test results can be found in Table 1.

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Conditions of preparation of Blanket very aggressive vas » CO > CZ) CZ) CD Ϊ— σι co moderate CZ) CO > CZ) CZ) CD Ϊ— σ co CZ) CO > CZ) CZ) CD σ) co smooth Static compression (kPa) 490 270 209 299 304 189 % of fibers shorter that 12.7 mm 10.5 6.5 4.3 Not measured Not measured Not measured Weaving Machine type of lic- kerin teeth CZ) O ç Q. pins CZ) O ç Q CZ) O ç Q pins Ragged ra2 Gap // (mm) none O CM 3.0 O cm 4.0 co Ragged ra 1 Gap (mm) none 00 O O cm 00 O 3.0 3.0 Input from fiber 36 mm / 12 m m 0/100 0/100 0/100 80/20 100/0 * 0/100 Example- plo - CM 00 m Comp. 1

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Claims (8)

1. Mounting mat (30) for mounting a pollution control element (20) in a pollution control device (10), said mounting mat FEATURED by the fact that it comprises a layer having a plurality of fibers comprising a mixture of long and short inorganic fibers constituting at least 50% by weight of said plurality of fibers in said layer, said short fibers having a length of no more than 13 mm, said long fibers having a length of at least 20 mm and the quantity of said short fibers is at least 3% by weight based on the total weight of said mixture of long and short fibers, and said mat (30) being dimensioned for the assembly of a pollution control element ( 20) in a pollution control device (10). 2. Assembly mat (30) according to claim 1, CHARACTERIZED by the fact that said mixture of long and short fibers is a mixture of long and short glass fibers. 3. Assembly mat (30) according to claim 1, CHARACTERIZED by the fact that at least 90% by weight, based on the total weight of said layer, of said mixture of long and short fibers is made of glass fibers of aluminum and magnesium silicate. 4. Assembly mat (30) according to claim 1, CHARACTERIZED by the fact that said short fibers and said long fibers together constitute at least 80% by weight of the fibers of said layer having said mixture of long fibers and short. Assembly mat (30) according to any one of claims 1 to 4, CHARACTERIZED in that it comprises two or more layers of chopped aluminum and magnesium silicate glass fibers, at least one of said layers comprising one mixture of said short and long glass fibers Petition 870180019655, of 12/03/2018, p. 35/38 2/2 as defined in any one of claims 1 to 4. 6. Pollution control device (10), CHARACTERIZED by the fact that it comprises a pollution control element (20) arranged in a housing (11), with a mounting mat (30) disposed between said housing (11) and said pollution control element (20), said mounting mat (30) being a mounting mat as defined in claim 1. 7. Pollution control device (10), according to claim 6, CHARACTERIZED by the fact that said pollution control element (20) is a diesel pollution control element. 8. Method for treating the exhaust gas of a diesel engine CHARACTERIZED by submitting the exhaust gas to a pollution control device (10) as defined in claim 6 or 7. Petition 870180019655, of 12/03/2018, p. 36/38 1/1 Petition 870180019655, dc 12/03/2018, p. 37/38 1/1