MOUNTING MEMBER FOR WRAPPING AND MOUNTING A POLLUTION CONTROL ELEMENT

Abstract

The invention relates to a mounting member for wrapping and mounting a pollution control element in a casing of a pollution control device, the mounting member comprising: inorganic fiber material; and inorganic particles, wherein the inorganic particles are distributed throughout most of the mat and comprise an average diameter of 800 nm to 15000 nm (DV 50), preferably of 1000 nm to 15000 nm (DV 50) measured according to DIN ISO 13320.

Claims

1. A mounting member for wrapping and mounting a pollution control element in a casing of a pollution control device, the mounting member comprising: inorganic fiber material; and inorganic particles, wherein the inorganic particles are distributed throughout most of the mounting member and comprise an average diameter of 1000 nm to 15000 nm (DV 50) measured according to DIN ISO 13320.

2. The mounting member according to claim 1 wherein the inorganic fiber material comprises fibers selected from the group of glass fibers, ceramic fibers, carbon fibers, silicon carbide fibers or boron fibers or a combination thereof.

3. The mounting member according to claim 1, wherein the inorganic fiber material of the mounting member is needle-punched.

4. The mounting member according to claim 1, wherein the inorganic particles are selected from the group consisting of metal oxides, metal hydroxides, metal oxide hydroxides, silicates, clays, nitrides, carbides, sulphides, carbonates and combinations thereof.

5. The mounting mat according to claim 1, wherein the inorganic particles are selected from Dispal particles from Sasol Corporation, USA.

6. The mounting member according to claim 1, wherein the mounting member contains organic binder up to 3 wt. %.

7. The mounting member according to claim 1, wherein the inorganic particles get impregnated through the mat by using a water based slurry containing the inorganic particles.

8. The mounting member according to claim 7, wherein the slurry contains at least 80 wt. % water.

9. The mounting member according to claim 7, wherein the slurry contains an organic binder.

10. The mounting member according to claim 9, wherein the organic binder comprises at least one of polymers or copolymers of acrylate, methacrylate, styrene, butadiene, vinyl pyridine, acrylonitrile, vinyl chloride, vinyl acetate, vinyl alcohol or ethylene, polyurethane, polyamides, silicones, polyesters, epoxy resins, or combinations thereof.

11. The mounting member according to claim 1, wherein the concentration of the inorganic particles within the mounting member is between 0.5 and 5 wt. %.

12. The mounting member according to claim 1, having a maximum reduction of the mount density of 3% caused by elongation of the mounting member during stuffing at a calculated mount density of 0.4 g/cm.sup.3.

13. The mounting member according to claim 1, wherein the mounting member comprises intumescent material disposed in the mounting member.

14. Method of manufacturing a mounting member for wrapping and mounting a pollution control element in a casing of a pollution control device, comprising the following steps: preparing a water based slurry containing fine inorganic particles with an average diameter of 1000 nm to 15000 nm (DV 50) measured according to DIN ISO 13320; impregnating a mat containing inorganic fiber material with the slurry.

15. The method according to claim 14, wherein the method comprises a drying step after the impregnating step.

16. (canceled)

17. (canceled)

18. The mounting member according to claim 1, wherein the concentration of the inorganic particles within the mounting member is between 1.0 and 2.5 wt. %.

19. The mounting member according to claim 11, having a maximum reduction of the mount density of 3% caused by elongation of the mounting member during stuffing at a calculated mount density of 0.4 g/cm.sup.3.

20. The mounting member according to claim 18, having a maximum reduction of the mount density of 3% caused by elongation of the mounting member during stuffing at a calculated mount density of 0.4 g/cm.sup.3.

21. The mounting member according to claim 19, wherein the inorganic fiber material of the mounting member is needle-punched, the mounting member contains organic binder up to 3 wt. %, and the inorganic particles are selected from the group consisting of metal oxides, metal hydroxides, metal oxide hydroxides, silicates, clays, nitrides, carbides, sulphides, carbonates and combinations thereof.

22. The mounting member according to claim 20, wherein the inorganic fiber material of the mounting member is needle-punched, the mounting member contains organic binder up to 3 wt. %, and the inorganic particles are selected from the group consisting of metal oxides, metal hydroxides, metal oxide hydroxides, silicates, clays, nitrides, carbides, sulphides, carbonates and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The invention will now be described in more detail with reference to the following Figures exemplifying particular embodiments of the invention:

[0044] FIG. 1 is a perspective view illustrating the retaining material according to an embodiment of the present invention;

[0045] FIG. 2 is a cross-sectional view schematically illustrating the pollution control device according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0046] Herein below various embodiments of the present invention are described and shown in the drawings wherein like elements are provided with the same reference numbers.

[0047] FIG. 1 is a perspective view illustrating an example of the mounting member of the present invention. The mounting member 10 illustrated in this figure may be wrapped around a pollution control element 30 having for example a round cylindrical or elliptical cylindrical outer shape, in order to retain the element in a casing 20 (refer to FIG. 2). All other shapes of the pollution control element 30 are possible as well. The mounting member 10 has a length that is in accordance with the length of the outer circumference of the pollution control element 30. The mounting member 10 has a convex part 10a and a concave part 10b on another end, for example, and has a shape such that the convex part 10a and the concave part 10b mutually engage when the mounting member 10 is wrapped around the pollution control element 30, but the shape for the mating is not restricted in particular, and any shape that can effectively prevent leaking of the exhaust gas in the mating region is acceptable, and other shapes such as an L shape are also possible. The mounting member 10 has also a width that is in accordance with the length of the pollution control element 30. As already pointed out above the width of the mounting member 10 needs to take into account an elongation of the mounting member 10 that might occur, when the mounting member 10 being wrapped around the pollution control element 30 gets stuffed into the casing 20, to avoid that the mounting member 10 after stuffing extends over the edge of the pollution control element 30.

[0048] FIG. 2 shows the mounting member 10 that is used to retain the pollution control element 30 in a pollution control device 50. A specific example of the pollution control element 30 is a catalyst carrier or a filter element or the like that is used for cleaning the exhaust gas from an engine. Specific examples of the pollution control device 50 include catalytic converters and exhaust cleaning devices (for example, a particulate filter device).

[0049] The pollution control device 50 illustrated in FIG. 2 has a casing 20, a pollution control element 30 provided in the casing 20, and a mounting member 10 provided between the inner surface of the casing 20 and the outer surface of the pollution control element 30. The pollution control device 50 also has a gas intake port 21 where the exhaust gases are introduced to the pollution control element 30, and a gas discharge port 22 where the exhaust gas that has passed through the pollution control element 30 is discharged.

[0050] The width of the gap between the inner surface of the casing 20 and the outer surface of the pollution control element 30 may be between 1.5 to 15 mm, preferably 3 to 10 mm. The mounting member 10 is preferably in an appropriately compressed condition to achieve a suitable bulk density between the casing 20 and the pollution control element 30. By using the mounting member 10 according to the invention to retain the pollution control element 30, a sufficiently high surface pressure can be maintained between the inner surface of the casing 20 and the pollution control element 30. Furthermore, the elongation during the mounting of the pollution control element into the pollution control device can be reduced as compared to conventional mounting members, and therefore the usage amount of the relative expensive inorganic fiber material can be reduced.

EXAMPLES

[0051] The present invention is described while referencing examples. Note that the present invention is in no way restricted by these examples.

[0052] All examples are based on alumina-silica fiber blankets from Mitsubishi Plastics Inc. (Maftec MLS 2). The mats are spray impregnated with a slurry of inorganic particles. In some examples an additional an organic latex binder was added to the slurry in addition to the inorganic particles. The impregnated mats were dried and then tested. The tests include multi-cycle compression testing at elevated temperatures and hard stuffing tests to determine the mat elongation.

Components Examples

[0053] Inorganic particles: Dispal 23N4-80, Dispal 18N4-80 both from Sasol Corporation, 12120 Wickchester Lane, Houston Tex. 77079, USA

[0054] Organic binder: Acronal A273 S from BASF SE, Ludwigshafen, Germany.

Components Comparative Examples

[0055] Inorganic particles: Snowtex OS; Nissan Chemical Industries, Japan; Colloidal Alumina; Nissan Chemical Industries, Japan

[0056] Organic binder: Nipol LX 874; Nippon Zeon Co., Japan

Slurry Preparation

[0057] The slurries for impregnation were prepared by adding the inorganic particles to water in an amount according to the below table and stirring with a laboratory mixer for 5 minutes. In some samples (see also below table) additional organic binder was added afterwards and was stirred for 1 additional minute.

TABLE-US-00001 Inorganic Inorganic Particle Organic Binder Particle Organic Binder or slurry Emulsion Water Example No. or Slurry Emulsion wt. % wt. % wt. % 1 Dispal 23N4-80 None 0.74 99.3 2 Dispal 23N4-80 Acronal 0.74 0.18 99.1 A273S 3 Dispal 18N4-80 None 0.74 99.3 4 Dispal 18N4-80 Acronal 0.74 0.18 99.1 A273S Comp. Ex. 1 no particles no binder Comp. Ex. 2 Snowtex OS Nipol LX874 4.6 0.13 95.3 Comp. Ex. 3 Colloidal Nipol LX874 6.7 0.13 93.2 Alumina Comp. Ex. 4 Snowtex OS Nipol LX874 4.6 0.13 95.3 Surface Snowtex OS Nipol LX874 48.5 1.5 50.0 Coating Comp. Ex. 2 and 3

Example 1

[0058] A sheet of the MLS 2 blanket was cut into pieces and impregnated by spraying the above described slurry containing the Dispal 23N4-80 particles, particle size 1.87 nm (DV 50) measured according to DIN ISO 13320, onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed in a forced air dryer for 15 minutes at 150 C. air temperature. The impregnated and dried mounting member contained about 1.5% by weight of the particles.

Example 2

[0059] A sheet of the MLS 2 blanket was cut into pieces and impregnated by spraying the above described slurry containing the Dispal 23N4-80 particles, particle size 1.87 nm (DV 50) measured according to DIN ISO 13320, and the organic binder Acronal A273S, onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed in a forced air dryer for 15 minutes at 150 C. air temperature. The impregnated and dried mounting member contained about 1.5% by weight of the inorganic particles and 0.8% by weight organic binder.

Example 3

[0060] A sheet of the MLS 2 blanket was cut into pieces and impregnated by spraying the above described slurry containing the Dispal 18N4-80 particles, particle size 3.51 nm (DV 50) measured according to DIN ISO 13320, onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed in a forced air dryer for 15 minutes at 150 C. air temperature. The impregnated and dried mounting member contained about 1.5% by weight of the particles.

Example 4

[0061] A sheet of the MLS 2 blanket was cut into pieces and impregnated by spraying the above described slurry containing the Dispal 18N4-80 particles, particle size 3.51 nm (DV 50) measured according to DIN ISO 13320, and the organic binder Acronal A273 S, onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed in a forced air dryer for 15 minutes at 150 C. air temperature. The impregnated and dried mounting member contained about 1.5% by weight of the particles and 0.8% by weight of the organic binder.

Comparative Example 1a

[0062] MLS 2 blanket without any treatment was cut into pieces and used as comparative example 1a. For the stuffing and multi-cycle tests, the mounting density was adapted to the mounting density of examples 1 and 2.

Comparative Example 1b

[0063] MLS 2 blanket without any treatment was cut into pieces and used as comparative example 1b. For the stuffing and multi-cycle tests, the mounting density was adapted to the mounting density of examples 3 and 4.

Comparative Example 2

[0064] A comparative sample was prepared by adding inorganic colloid particles (Snowtex OS, produced by Nissan Chemical Industries, Ltd.) 68.55 g and 2.0 g organic binder (Nipol LX874, produced by Nippon Zeon Co., Ltd.) to 1429.50 g Water and stirring for 5 minutes. The inorganic colloidal particles had a particle size of 16.9 nm (DV 50) measured according to DIN ISO 13320. A needle punched alumina fiber blanket (produced by Mitsubishi Plastics, Inc.) was impregnated by spraying the above described slurry onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed for 15 minutes using a forced air dryer with the temperature set to 150 C.

[0065] A second liquid containing inorganic colloid particles and organic binder was prepared by adding 63 g of colloidal silica (Snowtex OS) and 10 g Nipol LX874 to 65 g of water and stirring for 1 minute. The second liquid was coated to both an upper and lower surface of the blanket that had been impregnated before with the first liquid. In total the amount of 7 g/m.sup.2 of colloid silica was sprayed onto both surfaces and the total amount of organic binder was 0.8%. The impregnated material was dried for 5 minutes in a forced air dryer with temperature set to 150 C.

Comparative Example 3

[0066] A first liquid containing colloidal particles and organic binder was prepared by adding 201 g of colloidal alumina (alumina sol, produced by Nissan Chemical Industries, Ltd.) and 3.99 g organic binder (Nipol LX874, produced by Nippon Zeon Co., Ltd.) to 2790 g Water and stirring for 5 minutes. The inorganic colloidal particles had a particle size of 0.76 nm (DV 50) measured according to DIN ISO 13320. A needle punched alumina fiber blanket (produced by Mitsubishi Plastics, Inc.) was impregnated by spraying the above described slurry onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed for 15 minutes using a forced air dryer with the temperature set to 150 C.

[0067] A second liquid containing inorganic colloid particles and organic binder was prepared by adding 63 g of colloidal silica (Snowtex OS) and 10 g Nipol LX874 to 65 g of water and stirring for 1 minute. The second liquid was coated to both an upper and lower surface of the blanket that had been impregnated before with the first liquid. In total the amount of 7 g/m.sup.2 of colloid silica was sprayed onto both surfaces and the total amount of organic binder was 0.8%. The impregnated material was dried for 5 minutes in a forced air dryer with temperature set to 150 C.

Comparative Example 4

[0068] A further comparative sample was prepared by adding inorganic colloid particles (Snowtex OS, produced by Nissan Chemical Industries, Ltd.) 68.55 g and 2.0 g organic binder (Nipol LX874, produced by Nippon Zeon Co., Ltd.) to 1429.50 g Water and stirring for 5 minutes. The inorganic colloidal particles had a particle size of 16.9 nm (DV 50) measured according to DIN ISO 13320. A needle punched alumina fiber blanket (produced by Mitsubishi Plastics, Inc.) was impregnated by spraying the above described slurry onto the blanket. After the liquid was impregnated into the blanket in this manner, drying was performed for 15 minutes using a forced air dryer with the temperature set to 150 C.

Evaluation Tests

Measurement of Particle Size

[0069] The particle size is determined with laser diffraction according to DIN ISO 13320: 2009(E). The particle size is defined as DV50, which is the median particle diameter on a volumetric basis, i.e. 50% by volume of the particles are smaller than this diameter and 50% are larger.

Measurement of Multi Cycle Compression

[0070] The multi-cycle compression test is frequently used to design applications. The Examples were tested at a temperature of 650 C., the gap was cycled 1000 times between a closed gap and an open gap density. The open gap pressure after cycling is recorded.

[0071] For the tests in these examples a material test machine from Zwick/Roell Model Z010 from Zwick Gmbh & Co KG, Ulm, Germany was utilized. The test machine was equipped with a lower fixed heatable stainless steel block and a load cell capable of measuring forces up to 10 kN and an upper heatable stainless steel block mounted to the movable crosshead of the test machine. For the tests a sample of each example and comparative example with 50.8 mm diameter was cut out of the mounting member and placed on the lower heatable stainless steel block. The crosshead was moved downwards to compress the mounting member to a defined closed gap, which corresponds to a density of the mounting member of 0.366 g/cm.sup.3. The temperature of the heatable stainless steel blocks was raised to 650 C. while keeping the gap constant. After reaching the temperature of 650 C., the gap was cycled between the closed gap position corresponding to a density of the mounting member of 0.366 g/cm.sup.3 and an open gap position corresponding to a density of the mounting member of 0.329 g/cm.sup.3. After 1000 cycles the test was stopped and the open gap pressure after 1000 cycles was recorded.

Measurement of Elongation

[0072] Hard stuffing experiments were conducted to determine the elongation of the mounting members. The area weight of the mounting members, the metal shell inner diameter, and the pollution control element outer diameter were chosen to achieve a desired calculated mount density. The metal shell was calibrated using a shrinking machine from the company Wecotech, Gahwil, Switzerland. The transition angle between the inner shell diameter at the entrance side and the calibrated inner diameter was kept between 14 and 16, in order to ensure consistent conditions for each example.

[0073] The mounting members were cut so that they covered the complete length of the pollution control element. The mounting members were wrapped around the corresponding pollution control element and the stuffing was performed using a stuffing funnel with a contraction of 1.6. A compression test machine MTS Alliance RT/30 from MTS, Eden Prairie, Minn., USA was utilized to push the pollution control element together with the mounting member into the metal shell at a defined speed of 500 mm/min.

[0074] After stuffing the mat extended over the pollution control element due to the elongation during the stuffing process. This portion of the mat was cut and weighed to determine the effective mount density of the mat in the pollution control device.

[0075] In the following table the particle diameters of all examples and comparative examples are shown as well as the measured elongation and the results of the multi-cycle compression test:

TABLE-US-00002 Elongation Multi-Cycle-Compression Weight Par- of ticle material Mount Open gap dia. Calcul. extend. Eff. density Closed press. (DV Mat mount over the mount reduc- cap Open gap after 1000 50) weight density* edge density tion** density density cycles nm (g) (g/cm.sup.3) (g) (g/cm.sup.3) % (g/cm.sup.3) (g/cm.sup.3) (kPA) Example 1 1.87 124.9 0.391 2.02 0.385 1.5 0.366 0.329 84 Example 2 1.87 125.1 0.392 2.843 0.383 2.3 0.366 0.329 75 Comp. Ex. 1a 123.5 0.391 4.25 0.378 3.3 0.366 0.329 70 Example 3 3.51 126.3 0.401 2.965 0.392 2.2 0.366 0.329 68 Example 4 3.51 128.8 0.402 3.696 0.390 3.0 0.366 0.329 55 Comp. Ex. 1b 127.6 0.398 4.815 0.393 3.8 See Comp. Ex. 1a Comp. Ex. 2 16.9 Does not work in canning processthe mat does not slide into the can and is destroyed during the stuffing process Comparative 0.76 Does not work in canning processthe mat does not slide into the can and is destroyed during Example 3 the stuffing process Comparative 16.9 Does not work in canning processthe mat does not slide into the can and is destroyed during Example 4 the stuffing process *Calculated mount density: is the calculated mount density of the mounting member in the pollution control device (assuming no mat elongation). It is calculated by dividing the weight per area 2 times by the difference between metal shell inner diameter minus pollution control element outer diameter. MD.sub.ccalculated mount density W/A.sub.mweight per area or area weight of mounting member (mat) ID.sub.msmetal shell inner diameter OD.sub.pcepollution control element outer diameter Wt.sub.mweight of (mat) L.sub.mlength of mat W.sub.mwidth of mat (= length of pollution control element) [00004]${\mathrm{MD}}_c=\frac{W/\mathrm{Ax}.Math..Math.2}{{\mathrm{ID}}_{m.Math..Math.s}-{\mathrm{OD}}_{\mathrm{pce}}}$[00005]$W/A=\frac{{\mathrm{Wt}}_m}{L_m{W}_m}$**Mount density reduction: (Uli kannst Du bitte noch angeben, wie die berechnet wird?) After canning the mat extends over the pollution control element due to its elongation during the canning process. This portion of the mat is cut off and weighed. This cut off weight is subtracted from the original mat weight and the reduced weight per area of the mat after canning is calculated based on its original dimension. The mount density after canning is calculated using the weight per area after canning. The mount density difference is calculated in percent of the calculated mount density. MD.sub.redmount density reduction MD.sub.acmount density after canning Wt.sub.emweight of mat extended over the edge of the pollution control element after canning [00006]$W/A_{a.Math..Math.c}=\frac{{\mathrm{Wt}}_m-{\mathrm{Wt}}_{\mathrm{em}}}{L_m{W}_m}$[00007]${\mathrm{MD}}_{a.Math..Math.c}=\frac{W/A_{a.Math..Math.c}2}{{\mathrm{ID}}_{m.Math..Math.s}-\mathrm{OD}-\mathrm{pce}}$[00008]${\mathrm{MD}}_{\mathrm{red}}=\frac{{\mathrm{MD}}_c-{\mathrm{MD}}_{a.Math..Math.c}}{{\mathrm{MD}}_c}100.Math.\%$
The results show:

[0076] It can be seen from the table above, that the examples 1 to 4 with the inorganic particles distributed through the mat show less elongation than the comparative example 1a and 1b. Comparative examples 2, 3 and 4 failed completely during the canning, the mats did not slide into the can and were destroyed. For these mounting members no elongation could be measured.

[0077] The results show also that the examples 1 and 2, with 1.5% Dispal 23N4-80 show the higher results in the multi-cycle compression test. The open gap pressure after 1000 cycles for Examples 3 and 4 is lower than the one for comparative example 1a or 1b but they are still acceptable.