Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
  • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
  • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
  • C04B24/24—Macromolecular compounds
  • C04B24/38—Polysaccharides or derivatives thereof
  • C04B24/383—Cellulose or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/636—Polysaccharides or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/632—Organic additives
  • C04B35/636—Polysaccharides or derivatives thereof
  • C04B35/6365—Cellulose or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/71—Ceramic products containing macroscopic reinforcing agents
  • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
  • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/0006—Honeycomb structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
  • B28B3/20—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/0081—Uses not provided for elsewhere in C04B2111/00 as catalysts or catalyst carriers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
  • C04B2235/602—Making the green bodies or pre-forms by moulding
  • C04B2235/6021—Extrusion moulding
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/94—Products characterised by their shape
  • C04B2235/945—Products containing grooves, cuts, recesses or protusions
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES
  • F01N2330/00—Structure of catalyst support or particle filter
  • F01N2330/06—Ceramic, e.g. monoliths

Definitions

• the present invention relates to extrudable ceramic masses and other masses which set as a result of baking or sintering, which masses comprise specific additives based on water-soluble cellulose ethers, an extrusion process, the extrudates and their use.
• Water-soluble cellulose ethers have been used for many years as water retention agents, plasticizers and lubricants in the extrusion of ceramic masses and other masses which set as a result of baking or sintering to produce honeycomb bodies or other complicated profiles having similarly fine structures (see, for example: James S. Reed, Principles of Ceramics Processing, John Wiley & Sons, 1995, Chapter 23: Extrusion and Plastic Deformation Forming, p. 450 ff.)
• the extrusion of ceramic masses and other masses which set as a result of baking or sintering is carried out by pressing a plastic mass through a die orifice to produce any desired profiles, preferably honeycomb profiles as are used in catalysts or diesel soot particle filters.
• These masses can have various makeups and basically comprise a material, in particular a ceramic material, which is sinterable or hardens as a result of a ceramic baking process. It can further comprise catalytically active materials, fibers, aggregates and lightweight aggregates.
• EP 1 025 130 B 1 claims largely fiber-free cellulose ethers which in purely aqueous solution in concentrations of 0.5% by weight display values of the loss factor (tan ⁇ ) of less than 1 at an angular frequency of 1 Hz. These are claimed as auxiliaries for applications in the cosmetics, pharmaceutical and food sectors and for the production of paints (emulsion paints and silicate paints) and also in civil engineering. Use in the extrusion of ceramic or other sinterable masses is not described.
• EP 1506979 describes a cellulose ether composition as additive for the extrusion of mineral masses. The extent to which cellulose ethers prove to be advantageous in the extrusion of ceramics or other sinterable materials is not disclosed.
• the masses of the invention preferably comprise cellulose ethers of the abovementioned type which are simultaneously characterized in that an alkaline solution of 1.5 parts by weight of the cellulose ethers per 100 parts by weight of solution has a capillary breakup time in an extensional flow experiment at a temperature of 20 0 C +/- 1°C when using a solvent comprising 98 parts by weight of water and 2 parts by weight of sodium hydroxide per 100 parts by weight of solvent of 2.0 or more seconds.
• the figures for the capillary breakup time are based on measurements using a Haake Capillary Breakup Extensional Rheometer (CaBER 1 ) from Thermo Fischer, Düsseldorf, Germany.
• a liquid sample is introduced between two smooth concentric plates between which the liquid forms a "liquid bridge".
• the upper plate moves upward from the starting position (plate spacing 3 mm) to a plate spacing of 9 mm in 25 milliseconds and is then fixed in this position.
• the sudden extension forms an unstable liquid capillary between the two plates.
• plate spacing 9 mm
• the middle of the liquid capillary is subject to an extension which is determined by the extension properties of the sample.
• the decrease in the diameter in the middle of the liquid capillary is monitored as a function of time by means of a laser micrometer.
• the capillary breakup time is defined as the time interval from the end of the moving apart of the plates to the point in time at which the liquid capillary has a diameter of only 0.1 mm.
• the capillary breakup times reported were obtained by forming the mean of five individual measurements. - A -
• cellulose ethers of the abovementioned type whose solutions as described above have a capillary breakup time of greater than 2.5 seconds, particularly preferably greater than 3.0 seconds.
• ceramic masses and other masses which set as a result of baking or sintering are all masses which comprise at least one of the components listed below which can be baked or sintered by baking or sintering alone or with addition of other sintering aids:
• ceramic masses and other masses which set as a result of baking or sintering does not include hydraulic binders such as cement or gypsum and masses based on cement or gypsum. These hydraulic binders set as a result of incorporation of water into the crystal lattice.
• cellulose ethers having the abovementioned properties are to be used.
• These can be water-soluble cellulose ethers such as ionic cellulose ethers such as sulfoethylcellulose or carboxymethylcellulose and salts thereof, or nonionic cellulose ethers such as alkylcelluloses, hydroxyalkylalkylcelluloses or hydroxyalkylcelluloses, in particular methylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, methylethylhydroxyethylcellulose, methylhydroxyethylhydroxypropylcellulose, methylhydroxyethylhydroxybutylcellulose or cellulose ethers which at the same time comprise methyl groups and longer-chain hydrophobic side chains and also mixtures of the abovementioned products.
• Such cellulose ethers can easily be prepared by etherification of commercially available celluloses.
• An overview of the chemical fundamentals and principles in the preparation (preparative processes and process steps) and a materials composition and description of the properties and uses of the various derivatives is given in, for example, Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, 4th edition, Volume E 20, p. 2042, Thieme Verlag, Stuttgart (1987) and Ullmann's encyclopedia of industrial chemistry, Verlag Chemie, Weinheim/New York, (5.) A 5, p. 468.
• the cellulose ethers to be used for the purposes of the invention can be selected from among the cellulose ethers mentioned without problems and without the need to be inventive with the aid of the parameters such as tan ⁇ and capillary breakup time which are relevant to the invention and can easily be determined by a person skilled in the art by means of routine experiments.
• the corresponding parameters for the synthesis of the cellulose ethers used are described in the examples.
• Further additives such as hydrophobicizing agents, redispersion powders, superabsorbents based on crosslinked acrylates and polysaccharides, plasticizers, gelatins, lubricants (for example polyethylene oxide homopolymers, copolymers and terpolymers), surfactants, defoamer, waxes, oils, fatty acids and esters thereof, polymers based on acids, salts, amides and esters of acrylic acids and methacrylic acids, polysaccharides such as natural or modified starches, xanthans, glucans, welans, guar, dextran, chitin, chitosan, xylan, gellan, mannan, galactan, arabinoxylan, alginates and related polysaccharides, polyvinyl alcohols including derivatives thereof and polymers based on urethanes can be added to the cellulose ethers.
• lubricants for example polyethylene oxide homopolymers, copolymers
• Fibers which leave behind pores after baking or remain in the extrudate and increase the flexural strength can also be added to the masses of the invention.
• fibers are all types of natural or synthetic fibers such as fibers based on cellulose, bamboo, coconut, polyethylene, polypropylene, polyamide, polyacrylonitrile, carbon, glass, ceramic and other mineral fibers. Their fiber lengths and thicknesses can be varied within wide ranges.
• the invention further provides a process for the extrusion of ceramic masses or other masses which set as a result of baking or sintering, which comprises mixing a ceramic mass or other mass which sets as a result of baking or sintering with at least one cellulose ether to be used according to the invention and subsequently extruding it.
• the invention likewise provides the extrudates which can be obtained by the process of the invention, shaped bodies which can be obtained therefrom by thermal treatment and their use as honeycomb bodies for exhaust gas purification or as catalyst.
• cellulose ethers used were prepared as described in Houben-Weyl, Methoden der Organischen Chemie, Makromolekulare Stoffe, 4th edition, Volume E 20, p. 2042 Thieme Verlag, Stuttgart (1987).
• the rheological characterization of the cellulose ethers described was carried out on the basis of the respective cellulose ether as solid taking account of residual salt contents and residual moisture contents.
• the storage modulus G' and the loss modulus G" or the loss factor tan ⁇ , respectively, as the ratio G7G' were in each case determined as a function of the angular frequency ⁇ in a rheological oscillation experiment.
• the storage modulus G' corresponds to the deformation energy which is completely available after the stress is removed.
• the storage modulus G' indicates the elastic behavior of the sample.
• the loss modulus G is a measure of the deformation energy consumed during the shearing process in the sample and thus represents the viscous behavior.
• G' and G" were determined by means of measurements in oscillating shear flow at low amplitude (deformation ⁇ ⁇ 5%) and variable angular frequency. At small deformations (amplitudes), the material functions measured are independent of the magnitude of the deformation and thus dependent only on the angular frequency employed.
• the cellulose ethers were measured in a concentration of 1.0 part by weight per 100 parts by weight of a solvent comprising 98 parts by weight of water and 2 parts by weight of sodium hydroxide per 100 parts by weight of solvent and at a temperature of 20 0 C in a rheological oscillation experiment in the linear viscoelastic range.
• the measurements were carried out at 20 0 C using a Haake rotational rheometer RS 600 from Thermo Fischer, Düsseldorf, Germany, having a cone-plate geometry (C60/2°) and a Physica MCR 501 (Anton Paar, Ostfildern, Germany) having a cone- plate geometry (CP5O/1 0 ).
• RS 600 Haake rotational rheometer
• Physica MCR 501 Anton Paar, Ostfildern, Germany
• CP5O/1 0 cone- plate geometry
• the extensional flow experiments necessary to determine the capillary breakup time are based on measurements using a Haake Capillary Breakup Extensional Rheometer (CaBER 1 ) from Thermo Fischer, Düsseldorf, Germany.
• a liquid sample was introduced between two smooth, concentric plates between which the liquid formed a "liquid bridge".
• the upper plate moved upward from the starting position (plate spacing: 3 mm) over a period of 25 milliseconds to a plate spacing of 9 mm and was then fixed at this position.
• the capillary breakup time is the time until the liquid capillary formed on extension breaks again.
• Solutions of 1.5 parts by weight of the cellulose ether per 100 parts by weight of a solvent comprising 98 parts by weight of water and 2 parts by weight of sodium hydroxide per 100 parts by weight of solvent were used for these studies.
• a cushioned strike profile was used for this extension profile.
• the measurement of the decrease in the diameter of the liquid capillary was carried out in the real time mode at a sampling frequency of 1000 Hz. All measurements were carried out at a temperature of 20 0 C. Procedure for the extrusion experiments
• the dry components were firstly premixed dry, then admixed with water and mixed again. They were subsequently kneaded, compacted in a single-screw extruder and extruded through a die orifice:
• the mass was then immediately introduced into the feed trough of a single-screw extruder maintained at 20 0 C (Handle 8D, screw diameter 8 cm, from Handle, M ⁇ hlacker, Germany). In this, the mass was extruded through a perforated plate and passed through the vacuum chamber for degassing. It was then firstly strained (i.e. pressed through a screen having a mesh opening of 0.4 or 0.2 mm in order to separate off aggregates) and subsequently extruded through a honeycomb die orifice (for details see below) and discharged onto a conveyor belt. To be able to see differences between cellulose ethers which lubricate well and lubricate poorly, the cooling was switched off on the extruder after commencement of the experiment and the heating of the mass during the experiment was measured.
• the parts by weight of the cellulose ethers are based on 100 parts of silicon carbide (dry).
• W/S is the water/solids factor. The amount of water used is calculated only on the basis of silicon carbide.
• Pressure is the pressure measured just before the mass passes through the honeycomb die orifice.
• the temperature of the strained and extruded masses was measured by means of a noncontact infrared thermometer after leaving the die orifice; these temperatures coincided with those measured via the temperature sensor built into the die head.
• Examples A to C using cellulose ethers 6, 5 and 4 according to the invention having tan ⁇ ⁇ 1 and a capillary breakup time > 3 seconds in each case could be extruded without difficulty.
• Currents drawn by the extruder, extrusion pressure and heating of the mass were in a tolerable range.
• examples D and E using cellulose ethers 3 and 2 show, the use of cellulose ethers having a tan ⁇ and capillary breakup time outside the range according to the invention does not lead to a process which functions well in technical terms, since the heating of the mass in an uncooled extruder exceeds the critical figure of 10 0 C.
• the current drawn gets too close to the critical value of 2 A.
• a pressure of 60 bar is exceeded during extrusion through a 300 cpsi die.
• example F could not be strained at a W/S of 0.165; the addition of further water (to a W/S of 0.21 , cf. example G) also did not lead to the necessary plasticization, so that the experiment had to be stopped after a current increase to 3.52 A for the main screw.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)
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• 2006
  • 2006-12-22 DE DE102006062140A patent/DE102006062140A1/de not_active Withdrawn
• 2007
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