专利摘要:
A dried or at least partially dried ceramic starting material, a process for preparing a dried or at least partially dried ceramic starting material having a residual solvent content of up to about 15% by weight, ceramic comprising one or more ceramic precursors, temperature-sensitive gelling agent, solvent and viscosity suitable for low-pressure injection molding, processes for preparing such ceramic formulations, a method for forming a ceramic object from these ceramic formulations and a ceramic object that can be obtained therefrom.
公开号:FR3021968A1
申请号:FR1501146
申请日:2015-06-03
公开日:2015-12-11
发明作者:Wen Zhang；Gilles Gasgnier；Paul Micaletti；Gregory Etchegoyen；Benedicte Chastagnier
申请人:Imerys Ceramics France；
IPC主号:

专利说明:

[0001] TECHNICAL FIELD The present invention is directed to a dried or at least partially dried ceramic starting material, a process for preparing a dried or at least partially dried ceramic starting material having a residual solvent content up to about 15% by weight, ceramic formulations comprising one or more ceramic precursors, temperature-sensitive gelling agent, solvent and viscosity suitable for low-pressure injection molding, a method of preparation of these ceramic formulations, a method of forming a ceramic object from these ceramic formulations and a ceramic object that can be obtained therefrom. BACKGROUND OF THE INVENTION Low Pressure Injection Molding (MIBP) is used to form clean shaped ceramic pieces. In addition to the ability to provide complex and almost crisp shapes, the MIBP technique has attracted the attention of researchers by its relative simplicity and the advantages it offers over other ceramic manufacturing techniques. Injection molding is a direct consolidation operation in which there is no liquid removal during the formation. In other words, the green density of the ceramic bodies is approximately equivalent to the bulk solids load of the slips used. As a result, one of the challenges of this operation is to prepare highly concentrated slurries. Another challenge is in the preparation of starting materials for preparing highly concentrated slips and in obtaining such starting materials in a convenient form, easy to use by ceramic manufacturers.
[0002] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 (a) is a flowchart summarizing an illustrative embodiment of the present invention. Fig. 1 (b) is a flowchart summarizing another illustrative embodiment of the present invention. Fig. 2 is a graph showing the change in viscosity of a gelose solution (water) to 1.0% by weight. Figure 3 is a graph showing the change in gel strength of a 1.0% by weight agarose gel during the heating cycle. Figure 4 compares the gel strength of an agarose gel and an agarose / fructose gel. Figures 5 and 6 describe the breaking force and creep (deformation) of newly gelled bodies according to exemplary embodiments. Figure 7 is a schematic description of the devices used to determine the strength of the gel.
[0003] Figure 8 is a schematic description of the indenter used in the determination of the breaking strength of a gelled body. SUMMARY OF THE INVENTION According to a first facet, there is provided a ceramic formulation comprising one or more ceramic precursors, temperature-sensitive gelling agent, solvent and having a solids concentration of at least 50 % by volume, further characterized in that the ceramic formulation has a viscosity suitable for low-pressure injection molding, for example having a viscosity not greater than 10 Pa.s at a rate of shear 100 5-1 at a temperature above the freezing point of the gelling agent. According to a second facet, there is provided a method for making a ceramic formulation according to the first facet, comprising: providing at least one predispersed ceramic precursor; providing a solution or suspension comprising a solvent and at least one predispersed gelling agent, optionally with a reinforcing additive and a binder other than the gelling agent; mixing the at least one predispersed ceramic precursor and the solution or suspension to form the ceramic solution. According to a third aspect of the present invention, there is provided a starting material comprising one or more ceramic precursors, ceramic and temperature-sensitive gelling agent, the ceramic starting material being dried or dried at less partially and having a solvent content of up to about 15% by weight based on the total weight of the ceramic starting material.
[0004] According to a fourth aspect of the present invention there is provided a process for preparing a dried or at least partially dried ceramic starting material having a residual solvent content of up to about 15% by weight, the process comprising preparing obtaining or obtaining a ceramic slurry comprising one or more ceramic precursors, temperature-sensitive gelling agent, solvent and, optionally, dispersant and / or reinforcing additive and / or binding agent other than the gelling agent and treating the ceramic slip under suitable conditions to obtain a dried or dried ceramic starting material at least partly having a residual solvent content of up to about 15% by weight on the basis of the total weight of the ceramic starting material. According to a fifth facet of the present invention, there is provided a ceramic formulation comprising one or more ceramic precursors, temperature-sensitive gelling agent, solvent and having a viscosity suitable for low-pressure injection molding, for example having a viscosity of about 0.1 to 10.0 Pa.s at a shear rate of 100 s-1.
[0005] According to a sixth aspect of the present invention there is provided a method for preparing a ceramic formulation, the method comprising: preparing, obtaining or obtaining a ceramic slip comprising one or more ceramic precursors, temperature-sensitive gelling of the solvent and, optionally, the dispersing agent and / or a reinforcing additive and / or binder other than the gelling agent; treating the ceramic slurry under suitable conditions to obtain a dried or dried ceramic starting material at least in part; and mixing the dried or at least partially dried ceramic starting material with an appropriate amount of additional solvent at a temperature above the gel point of the gelling agent to obtain a ceramic formulation having a molding viscosity by low pressure injection.
[0006] According to a seventh facet of the present invention, there is provided a method of forming a ceramic article, the method comprising: forming a green gelled ceramic body from a ceramic formulation comprising one or more ceramic precursors, of the temperature-sensitive gelling agent, solvent and having a solids concentration of at least 50% by volume, optionally drying the green gelled ceramic body and baking the green gelled ceramic body to form a sintered ceramic object. According to an eighth facet of the present invention, there is provided a ceramic object that can be obtained by the method according to the seventh facet of the present invention.
[0007] DETAILED DESCRIPTION OF THE INVENTION The term "ceramic starting material" as used herein means a composition comprising one or more ceramic precursors, which is suitable for being packaged and transported and, furthermore, after mixing with a suitable amount of solvent, such as water, forms a ceramic formulation suitable for low pressure injection molding.
[0008] The ceramic starting material is dried or dried at least in part and has a solvent (eg, moisture content) of up to about 15% by weight based on the total weight of the ceramic starting material . In some embodiments, the solvent content is from about 0.1 to about 15% by weight, for example, from about 0.1 to about 10% by weight or from about 0.1 to about 7, 5% by weight or about 0.1 to about 5.0% by weight or about 0.1 to about 4.0% by weight or about 0.1 to about 3.0% by weight or from about 0.1 to about 2.0% by weight or from about 0.1 to 1.0% by weight or from about 0.2 to about 5.0% by weight or about 0.3% by weight at about 3.0% by weight or about 0.4 to 2.0% by weight or about 0.2 to about 1.0% by weight or about 0.3 to about 0.8% by weight or from about 0.4 to about 0.6% by weight. A dried starting material can be characterized as having a solvent (eg, a moisture content) of less than about 0.1% by weight based on the total weight of the ceramic starting material.
[0009] The solvent content (e.g., moisture content) can be determined by the weight difference between the precursor of the starting material, i.e. the ceramic slip described hereinafter, before treatment to obtain the ceramic starting material in the dried / partially dried state. The solvent content of the starting material can be referred to as the "residual solvent" since it is the amount of solvent remaining after the treatment of the precursor of the starting material, i.e. ceramic described below, to obtain the dried or dried ceramic starting material at least in part. The solvent may be any form suitable for allowing the gelling agent to gel after cooling to the gel point or below the gel point of the gelling agent. Advantageously, the solvent serves to dissolve the gelling agent (i.e., at a temperature above the melting point of the gelling agent) during the preparation of the ceramic starting material and serves supporting the ceramic mixture during molding. In some embodiments, the solvent is a polar solvent, for example an aqueous solution, such as water or alcohol. In some embodiments, the solvent is water. The ceramic starting material comprises one or more ceramic precursors. The one or more ceramic precursors will normally be in particulate form having, for example, a dso of from about 0.1 μm to about 500 μm, for example, from about 0.1 μm to about 250 μm. or about 0.1 μm to about 100 μm or about 0.1 μm to about 50 μm or about 0.1 μm to about 25 μm. Unless otherwise indicated, the mean equivalent particle diameter (on average) (d50 value), referred to herein, is as measured in a well-known manner by laser light scattering of the particulate matter in a state. fully dispersed in an aqueous medium using an LA950 machine, as supplied by Horiba, which will be referred to as a "Horiba LA950 unit". Such a machine provides measurements and a plot of the cumulative percentage by volume of particles having a certain size, referred to in the art as "equivalent spherical diameter" (dse) less than data values. The average particle size d50 is the value determined in this way of the dse particle, at which there is 50% by volume of the particles which have an equivalent spherical diameter smaller than the d50 value. Similarly, d90 is the value determined in this way of the dse particle, to which there is 90% by volume of the particles which have an equivalent spherical diameter smaller than this d90 value. Similarly, d10 is the value determined in this way of the dse particle, to which there is 10% by volume of the particles which have an equivalent spherical diameter smaller than this d10 value. In some embodiments, the one or more ceramic precursors are suitable for the manufacture of ceramics selected from tableware, sanitary ware, charging materials, refractory materials and technical grade ceramics. In some embodiments, the one or more ceramic precursors are suitable for the manufacture of tableware, including utensils, like containers adapted to contain or serve food. The one or more ceramic precursors may be suitable for the manufacture of porcelain tableware. In some embodiments, the one or more ceramic precursors are suitable for the manufacture of sanitary appliances, including toilets, bowls and the like, as well as other bathroom items, such as bathtubs and bathtubs. trays and shower columns. The one or more ceramic precursors may be suitable for the manufacture of porcelain stoneware or vitreous bathroom appliances. In some embodiments, the one or more ceramic precursors are suitable for the manufacture of charging equipment. The charging equipment comprises trays and posts and the like used to support products inside the oven. In some embodiments, the one or more ceramic precursors are suitable for the manufacture of refractory materials. The refractory materials comprise refractory coatings, such as a coating for a cupola sole and a siphon, blast furnaces, main, secondary and tilting channels, receptacles or jars, pockets, refractory vessels, refraction chambers and troughs, which contain, direct the current or are suitable for facilitating the industrial processing of liquid metals and slags, or any other liquids, solids or gases at high temperatures. Refractory materials also include refractory articles, such as those described above, and pre-formed objects in whole or in part such as refractory bricks and crucibles. In some embodiments, the one or more ceramic precursors are suitable for producing technical grade ceramics. Technical grade ceramics include objects made of ceramic precursors, such as, for example, quartz, silicon metal, alumina porcelain, steatite, cordierite, mullite, alumina, zirconium oxide, ferrites, garnets, titanates, carbides, such as silicon carbide, boron carbide, tungsten carbide and titanium carbide, boron nitride and silicides and mixtures thereof. Technical grade ceramics include objects, such as tiles having high heat resistance, such as those used in a space vehicle, gas burner nozzles, crucibles, molds and foundry cores, filters of molten metal, structured heat exchangers, such as honeycombs, random packings, welding rings and supports, ballistic protection, for example, armor inserts, biomedical implants, jet engine and their components, such as vanes, ceramic disc brakes, missile nose cones, bearings and the like. Other technical grade ceramics include parts used for electrical applications, such as plugs, sockets, insulators, resistor carriers, spark plugs, ignitors, fuses, and the like. Other technical grade ceramics include parts used for filtration or catalyst applications, such as molecular sieves, fluid and gas filters, catalytic bed supports, and the like. Other technical grade ceramics include component parts of glass screens, windows, rods, tanks, semiconductors, optical lenses and fibers. In certain embodiments, the one or more ceramic precursors are chosen from alumina, an aluminosilicate, nepheline syenite, feldspar, talc, mica, quartz, silica, titanium oxide, and the like. zirconium oxide, zirconium oxide silicate, wollastonite, perlite, diatomaceous earth, alkaline earth metal carbonate or sulphate, such as calcium carbonate, magnesium carbonate, dolomite and plaster, a carbide, such as silicon carbide, boron carbide, tungsten carbide and titanium carbide, boron nitride, a silicide, such as nickel silicide, sodium silicide, magnesium silicide, platinum silicide, titanium silicide, tungsten silicide, silica metal, cerium oxide, yttrium oxide, ferrite, such as zinc-iron ferrite, barium-strontium ferrite , strontium ferrite, a garnet, such as yttrium-aluminum garnet, a titanate, such as barium titanate, lead titanate, graphite or other carbon-based ceramic precursor materials and combinations thereof. The aluminosilicate may be one or more of andalusite, cyanite, sillimanite, mullite, molochite, hydrous candite clay, such as kaolin, illite, halloysite, or plastic clay, or an anhydrous (calcined) candy clay, such as metakaolin or fully calcined kaolin.
[0010] Alumina can be selected from one or more of the fused alumina (eg corundum), sintered alumina, calcined alumina, reactive or semi-reactive alumina, bauxite and chamotte having a content in alumina. The ceramic starting material may comprise up to about 99.9% by weight of the ceramic precursor (s) based on the total weight of the ceramic starting material, for example, from about 70% by weight to about 99.5% by weight, from about 70% by weight to about 99.0% by weight or from about 70% by weight to about 98.5% by weight or from about 70% by weight to about 98, 0% by weight or about 70% by weight to about 97.5% by weight or at least about 75% by weight or at least about 80% by weight or at least about 85% by weight or at least about 90% by weight or at least about 91% by weight or at least about 92% by weight or at least about 93% by weight or at least about 94% by weight or at least about 95% by weight or at least about 96% by weight or at least about 97% by weight or at least about 98% by weight or at least about 98.5% by weight by weight or at least about 99.0% by weight or at least about 99.1% by weight or about 99.2% by weight or at least about 99.3% by weight or at least about 99.5% by weight. The balance of the ceramic starting material comprises temperature-sensitive gelling agent and optionally residual solvent, dispersant, reinforcing additive, binder (other than the gelling agent, the biocide, admixture (e.g., lubricant) and / or antifoam, as described herein.In some embodiments, the total weight of the components other than the one or more ceramic precursors are not greater than that about 5% of the total weight of the ceramic starting material, for example, from about 0.5% by weight to about 5% by weight or from about 1.0% by weight to about 4.5% by weight or about 1.5% by weight to about 4.0% by weight or about 2.0% by weight to about 3.5% by weight or not more than about 3.0% by weight or not more than about 2.5% by weight The ceramic starting material comprises a temperature sensitive gelling agent. It is meant that in the presence of a suitable solvent, such as water, the gelling agent gels reversibly during a heating-cooling-heating-cooling cycle, i.e. after heating the gelling agent in the solvent, for example water, to dissolve the gelling agent, followed by cooling to or below its gelling point. In some embodiments, the gelling agent is a substance that has a gel force measured at room temperature (between about 18 and 25 ° C) on a gelled body formed from a gel of about 1, 0% by weight of the gelling agent, the balance being water, at least about 25 kPa, for example, at least about 35 kPa or at least about 45 kPa.
[0011] In some embodiments, the gelling agent has a first cycle gel strength of at least about 45 kPa. "First cycle gel strength" as measured by the process described herein refers to the strength of the gel after an initial heating cycle to dissolve the gelling agent in water (e.g. about 90 ° C), followed by cooling at the gel point or below the gel point of the gelling agent. The "second cycle gel strength" is the strength of the gel after a second heating stage to break the gel to a lower viscosity liquid and a second cooling stage at the gel point or below the freezing point gelling agent. The "third cycle gel strength" is the gel force after a subsequent cycle of heating and cooling. In some embodiments, the gelling agent has a second cycle gel strength, which represents at least 70% of the gel strength of the first cycle, and, optionally, a third cycle gel force, which represents at least minus about 50% of the first cycle freezing force. In some embodiments, the gelling agent has a second and / or third cycle gel strength, which is at least 90% of the first cycle gel strength or at least about 95% of the gel strength. first cycle or is approximately equal to 1% or 2% of the first cycle freezing force or is comparable to the first cycle freezing force. In some embodiments, the temperature-sensitive gelling agent (ST) is selected from one or more of a polysaccharide, a gelatin, a polysaccharide, a poloxamer, and mixtures thereof. In certain embodiments, the ST gelling agent is a polysaccharide or a polysaccharide mixture, for example, one or more of a polysaccharide selected from agarose, agarose, carrageenan, galactomannan (locust bean gum). and gum arabic.
[0012] In some embodiments, the polysaccharide is selected from one or more of agar, agarose and acacia.
[0013] In some embodiments, the polysaccharide comprises D-galactose and L-galactose units, for example, alternating D-galactose and L-galactose, linked by glycosidic linkages. In some embodiments, the L-galactose unit is an L-galactopyranose unit, for example, a 3,6-anhydro-L-galactopyranose unit, and optionally the polysaccharide comprises D-galactose units and alternating L-galactopyranose, for example, alternating units of G-galactose and 3,6-anhydro-L-galactopyranose, linked by glycosidic linkages. Advantageously, the ST gelling agent is agar or agarose, preferably agarose. Agarose is one of the two main constituents of agar and is purified from agar by removing agaropectin, which is the other agar component. In some embodiments, the ST gelling agent has a gel point lower than about 70 ° C, for example, lower than about 60 ° C or lower than about 55 ° C or lower about 50 ° C or lower than about 45 ° C or lower than about 40 ° C. In some embodiments, the ST gelling agent has a gel point higher than ambient temperature, for example, a gel point of at least about 25 ° C or at least about 30 ° C or at least about 35 ° C. The freezing point can be determined by observing the increase in the viscosity of a 1.0% by weight solution of the gelling agent in water, when it is cooled to a temperature at which The gelling agent dissolves in water. The temperature at which there is a marked and rapid increase in viscosity indicates the freezing point. The freezing point can be determined by any suitable method which allows one skilled in the art to reliably determine and control the viscosity of the composition comprising the gelling agent as a function of temperature.
[0014] Thus, for example, by cooling a 1.0 wt.% Solution of agarose in water, it is seen that the agarose has a gel point of about 36 ° C. The ceramic starting material may further comprise dispersant. As described herein, the dispersant can be added during the preparation of the precursor of the starting material, i.e. ceramic slip. The dispersant is capable of dispersing the one or more ceramic precursors. Suitable dispersants are well known to those skilled in the art. A dispersant is a chemical additive capable, when present in a sufficient amount, of acting on the particles of the one or more ceramic precursors to prevent or effectively limit flocculation or agglomeration of the particles to a desired extent according to the requirements normal treatment. The dispersant can be a mixture of different dispersants. A suitable dispersant comprises one or more dispersants selected from the group consisting of sulfonated naphthalene and formaldehyde (CNSF) condensates, polyelectrolytes, such as polycarboxylic acids, polyacrylates and copolymers containing polyacrylate species, particularly polyacrylate salts (for example, sodium and aluminum, optionally with a salt of a Group II metal), polyphosphonates, sodium hexametaphosphates, a nonionic polyol, polyphosphoric acid, condensed sodium, nonionic surfactants, alkanolamines and other reagents commonly used for this purpose. For example, the dispersant can be selected from conventional dispersants commonly used in the treatment and grinding of mineral particulates. Dispersants of this kind will be well recognized by those skilled in the art. These are generally soluble salts in water capable of providing anionic species, which, in their effective amounts, can adsorb to the surface of the mineral particles and thus prevent aggregation of the particles. The unsolvated salts suitably include alkali metal cations, such as sodium. Solvation can, in some cases, be facilitated by making the aqueous substance slightly alkaline. Examples of suitable dispersants are: water-soluble condensed phosphates, for example, polymetaphosphate salts [in the general form of sodium salts (NaPO3), J, such as tetrasodium metaphosphate or the like; which is called "sodium hexametaphosphate" (Graham's salt); water-soluble salts of polysilicic acids; polyelectrolytes; salts of homopolymers or copolymers of acrylic acid or methacrylic acid, or polymer salts of other acrylic acid derivatives, suitably having a weight average molecular weight of at least about 20,000. The dispersant can be up to about 5% by weight, for example, up to about 2% by weight, for example, from about 0.05 to about 2% by weight or about 0.05 to 1, 5% by weight or from about 0.05 to about 1.0% by weight or from about 0.05 to about 0.75% by weight or from about 0.05 to about 0.5% by weight or from about 0.05 to about 0.25% by weight or from about 0.05 by weight to about 0.15% by weight of the total weight of the ceramic starting material. In some embodiments, the dispersant comprises or is an anionic polyelectrolyte or a mixture of anionic polyelectrolytes. In some embodiments, the dispersant is a polyelectrolyte, such as polyacrylates and copolymers containing polyacrylate species, particularly polyacrylate salts (eg, sodium and aluminum optionally with a metal salt of group II). In some embodiments, the dispersant is a polyacrylate, for example, sodium polyacrylate. Advantageously, the gel strength and thus the strength of the ceramic bodies formed from the ceramic starting material and the ceramic formulations described herein can be increased (for example, molded raw ceramic bodies). which have been cooled to the gel point or below the gel point of the gelling agent), incorporating a reinforcing additive. Thus, in some embodiments, the ceramic starting material (and thus, the ceramic formulation and the raw ceramic bodies formed therefrom) further comprises a reinforcing additive. Advantageously, the reinforcing additive improves the second cycle and third cycle gel strength (i.e., in the presence of the reinforcing additive, the second cycle gel force and / or third cycle is greater than it would be 30 otherwise in the absence of the reinforcing additive). Thus, for example, in the presence of a reinforcing additive, the second cycle and third cycle gel strength can be substantially the same, for example being comparable to the first cycle freezing force. . In some embodiments, the reinforcing additive is selected from one or more of a monosaccharide, a polysaccharide other than the ST gelling agent, a disaccharide, glycerol, and inulin syrup. an alkali metal or alkaline earth metal borate (eg, sodium borate, magnesium borate, calcium borate, and the like). In certain embodiments, the reinforcing additive is a polysaccharide other than the ST gelling agent, for example galactomannan (locust bean gum). In some embodiments, the reinforcing additive is a monosaccharide and / or a disaccharide. The monosaccharide may be a diose, a triose, a tetraose, a pentose, a hexose or a heptose. In some embodiments, the monosaccharide is a hexose, for example one or more of allose, altrose, mannose glucose, gulose, idose, galactose, talose, psicose, fructose, sorbose and tagatose. In some embodiments, the reinforcing agent is fructose. Suitable disaccharides are sucrose, lactulose, lactose, maltose, trehalose and cellobiose. The reinforcing additive (for example, a monosaccharide such as fructose) can represent up to about 5% by weight, for example up to about 2% by weight, for example from about 0.1 to about 2% by weight or from about 0.1 to about 1.5% by weight or from about 0.1 to about 1.25% by weight or from about 0.5 to about 1.25% by weight or from about 0.75 to about 1.25% by weight, based on the total weight of the ceramic starting material. In some embodiments, the ST gelling agent is agarose and the reinforcing additive is fructose. In these embodiments, the ceramic starting material may comprise up to about 5% by weight of agarose and fructose combined based on the total weight of the ceramic starting material, for example about 0, 1% by weight to about 5% by weight or about 0.5% by weight to about 4% by weight or up to about 3% by weight or up to about 2% by weight. In these embodiments, the ceramic starting material may comprise up to about 1% by weight of dispersant, for example polyacrylate, such as sodium polyacrylate, for example, from about 0.05% to about 0%. , 5% by weight or from about 0.05 to about 0.25% by weight or from about 0.05 to about 0.15% by weight of dispersant, based on the total weight of the starting material of ceramic. In some embodiments, the gelling agent serves as a binder for the ceramic body to be formed from the ceramic starting material. In some embodiments, the ceramic starting material comprises a binder other than the gelling agent.
[0015] In some embodiments, the ceramic starting material comprises a binder or a plurality of binders selected from the group consisting of methyl cellulose (MC), hydroxymethylpropyl cellulose (HEMC), carboxymethyl cellulose (CMC), polyvinyl butyral emulsified acrylates, polyvinyl alcohols (PVOH), polyvinyl pyrrolidones, polyacrylics, starch, silicone binders, polyacrylates, silicates, polyethylene imine, lignosulfonates and alginates. The binders may be in total from about 0.1 wt.% To about 10 wt.% Or from about 0.2 wt.% To about 8 wt.% Or from about 0.2 wt.% To about 5 wt.% or between about 0.5% by weight and about 3% by weight (based on the total weight of the ceramic starting material). In another embodiment, the ceramic starting material comprises a mineral binder or a plurality of inorganic binders. A suitable inorganic binder can be selected from the group including, but not limited to, one or more of bentonite, aluminum phosphate, boehmite, sodium silicates, boron silicates, or mixtures thereof. In some embodiments, the ceramic starting material comprises an adjuvant or a plurality of adjuvants (e.g., plasticizers and lubricants) selected from the group consisting of polyethylene glycol (PEGs), glycerol, glycerin, and the like. ethylene glycol, octyl phthalates, stearates such as ammonium stearate, wax emulsions, oleic acid, Manhattan fish oil, stearic acid, wax, palmitic acid, linoleic acid, myristic acid and lauric acid. The adjuvants may be in total from 0.01% by weight to 5% by weight (based on the total weight of the ceramic starting material), for example, from about 0.01% by weight to about 2% by weight. weight or between about 0.1% by weight and 2% by weight or between about 0.5% by weight and 2% by weight. In some embodiments, the ceramic starting material comprises one or more biocides / deterioration control agents, for example at levels up to about 1% by weight, for example oxidizing biocides, such as chlorine. gaseous chlorine dioxide, sodium hypochlorite, sodium hypobromite, hydrogen, peroxide, peracetic acid, ammonium bromide / sodium hypochlorite, or non-oxidative biocides, such as GLUT (Glutaraldehyde, CAS No. 90045-36-6), ISO (CIT / MIT) (Isothiazolinone, CAS No. 55956-84-9 and 96118-96-6), ISO (BIT / MIT) (Isothiazolinone), ISO (BIT) (Isothiazolinone, CAS No. 2634-33-5), DBNPA, BNPD (Bronopol), NaOPP, CARBAMATE, THIONE (Dazomet), EDDM-dimethanol (O-formai), HT-Triazine (N-formal), THPS - tetrakis (0-formal), TMAD 15 diurea (N-formal, metaborate, sodium dodecylbenzene sulfonate, thiocyanate, organosulfur, sodium benzoate and other compounds sold as For this purpose, for example, the range of biocidal polymers sold by Nalco. In some embodiments, the ceramic starting material comprises an antifoam or several defoamers and suds suppressing agents, for example, at levels up to about 1% by weight, for example, blends of agents. surfactants, tributyl phosphate, polyoxyethylenated fatty esters plus fatty alcohols, fatty acid soaps, silicone emulsions and other compositions containing silicones, waxes and mineral particles in mineral oil , emulsified hydrocarbon mixtures and other compounds sold commercially for this purpose. The ceramic starting material may be in any form that is suitable for further processing or for packaging and transportation to the customer. In some embodiments, the ceramic starting material is in the form of a powder. In some embodiments, the ceramic starting material is in the form of granules. In some embodiments, the ceramic starting material is in pellet form. In some embodiments, the ceramic starting material is in the form of a wire, for example, a coil of wire. In some embodiments, the ceramic precursor, which may be a mixture of ceramic precursors, is subjected to crushing / grinding / sieving to obtain inorganic particles having a desired particle size distribution prior to combining them with gelling agent. For example, it is possible to combine and grind a ceramic precursor or several ceramic precursors in a mill, for example, in a ball mill, under dry conditions or in a liquid medium, by example, in water. A dispersant may be included during wet milling. Grinding can be carried out for a suitable period of time, sufficient to obtain particles having a desired particle size distribution. Those skilled in the art will understand that the duration of milling will depend on the number of processing parameters, such as, for example, the type of milling, the energy supplied, the amount of raw material and the desired particle size distribution. In some embodiments, the total grinding time is smaller than about 25 hours, for example, less than about 20 hours, or less than about 15 hours, or less than about 10 hours, or less than about 10 hours. approximately 5 hours or less than about 3 hours or less than about 2 hours or less than about 1 hour or less than about 45 minutes. Normally, the total grinding time is greater than about 10 minutes. In some embodiments, the ceramic precursor or the plurality of ceramic precursors are milled to obtain particles having a d50 of from about 0.1 μm to about 500 μm, for example from about 0.1 μm to about 250 μm. or from about 0.1 μm to about 100 μm or from about 0.1 μm to about 50 μm or from about 0.1 μm to about 25 μm. In some embodiments, the dried or dried ceramic starting material may be obtained at least in part by an operation or may be prepared by an operation comprising (i) preparing, obtaining or obtaining a ceramic slip comprising a ceramic precursor or more ceramic precursors, the temperature-sensitive gelling agent, the solvent and optionally the dispersant and / or the reinforcing additive and / or the binder other than the gelling agent and (ii) treating the ceramic slip for obtaining a dried or at least partially dried ceramic starting material having a residual solvent content of up to about 15% by weight based on the total weight of the ceramic starting material. This method is also the method according to the fourth facet of the present invention. In some embodiments, the ceramic slip is prepared by an operation comprising (i) (a) mixing the ceramic precursor or plural ceramic precursors with solvent and optionally with dispersant and heating, (i) ( b) separately dissolving the gelling agent in a solvent optionally with the reinforcing additive and the binder other than the gelling agent and (i) (c) mixing the precursor of the ceramic or the plurality of precursors of the ceramic to the solvent and optionally to the dispersant having the dissolved gelling agent. The mixture of the ceramic precursor precursor or the plurality of ceramic precursors can be mixed with solvent and optionally dispersant in any suitable mixing apparatus, for example, a Z-arm mixer or an Eirich mixer. In some embodiments, the ceramic slip is prepared by grinding the ceramic precursor or the plurality of ceramic precursors, the solvent and optionally the dispersant, for example, in a ball mill, under conditions to obtain a slurry of ceramic. The ceramic slurry can be heated during its preparation or heated after its preparation. The ceramic slip is preferably carried at a temperature which is higher than the gel point of the gelling agent, for example at a temperature which is at least 10 ° C or at least 20 ° C. or at least 30 ° C above the gel point of the gelling agent. Normally, the temperature is below the melting point of the gelling agent. The dissolution of the gelling agent in the solvent, especially water, can be carried out together with other optional additives, such as reinforcing additive, in any suitable apparatus. The gelling agent may be added to water and brought to a temperature above the dissolution point of the gelling agent or the water may have already been brought to the required temperature and the gelation dissolved in heated water. After the preparation of the mixture comprising a ceramic precursor or several solvent and optionally dissolved gelling, the ceramic precursors, the dispersant, and the mixing agent (at the elevated temperature above the gel point of the gelling agent) and the gelling agent dissolves in forming the ceramic slip. In some embodiments, the temperature during mixing is less than or equal to about 85 ° C, for example less than or equal to about 80 ° C. In general, a suitable temperature is chosen which is greater than the gel point of the gelling agent, less than the melting point of the gelling agent and, for embodiments in which a dispersant is present, at a lower temperature. temperature that does not affect the functionality of the dispersant. In some embodiments, the temperature during mixing of the ceramic precursor mixture and the dissolved gelling agent is from about 50 ° C to 85 ° C, for example, from about 65 ° C to about 85 ° C. or from about 70 ° C to about 85 ° C or from about 75 ° C to about 85 ° C or from about 75 ° C to about 80 ° C. In some embodiments, the mixture comprising ceramic precursor or several ceramic precursors, solvent and optionally dispersant and the gelling agent dissolved under conditions which make it possible to obtain a substantially homogenized ceramic slip. By "homogenize" is meant that the mixture of raw materials everywhere has a uniform composition.
[0016] In some embodiments, the solvent is water. The ceramic slurry will comprise a quantity of solvent, for example water, which is larger than the residual amount of solvent in the at least partially dried or dried ceramic starting material. In some embodiments, the ceramic slip, after mixing, but prior to treatment to obtain the at least partially dried or dried ceramic starting material, comprises from about 15% by weight to about 80% by weight of solvent, for example water, for example from about 15% by weight to about 60% by weight of solvent or from about 15% by weight to about 50% by weight of solvent or from about 20% by weight to about about 50% by weight of solvent or about 20% by weight to about 40% by weight of solvent or about 30% by weight to about 40% by weight of solvent, based on the total weight of the slurry of ceramic. Since the ceramic slurry is treated to obtain the dried or dried ceramic starting material at least in part, suitable amounts of ceramic precursors, gelling agent and other optional additives can be selected in order to obtain a ceramic filler material dried or dried at least in part, according to the embodiments described herein. The ceramic slurry is treated to obtain at least a partially dried or dried ceramic filler having a residual solvent content of up to about 15% by weight, based on the total weight of the ceramic starting material. for example, a ceramic starting material having a residual solvent content according to the embodiments described herein. The solvent, for example water, is removed in part or completely from the ceramic slip at the end of the treatment. In some embodiments, treating the ceramic slip to obtain a dried or at least partially dried ceramic starting material comprises cooling the ceramic slip below the gel point of the gelling agent, breaking up the gelled material In the resulting cooled ceramic, dry and grind the fragmented chilled ceramic gelled material. The gelled ceramic material can be comminuted in any suitable fragmentation apparatus. Fragmentation breaks the gelled material into small pieces of material and facilitates further processing and grinding. Grinding can be carried out in any suitable grinding apparatus, such as, for example, a mixer or grinder, for example a ball mill, such as a planetary ball mill. In some embodiments, the total grinding time is smaller than about 10 hours, for example, less than about 5 hours, or less than about 3 hours, or less than about 2 hours, or less than about 2 hours. about 1 hour or less than about 25 to 45 minutes. Usually, the total grinding time is longer than about 10 minutes. The drying can be carried out in any suitable drying device, for example in a drying oven. Other dryers include tunnel dryers and periodic dryers. The drying can be carried out at an appropriate temperature and for a time appropriate to remove the solvent, for example water, all or part of the milled material. In some embodiments, the temperature is greater than about 50 ° C, for example greater than or equal to about 60 ° C. In some embodiments, the temperature is less than about 150 ° C, for example, less than about 125 ° C or less than about 110 ° C. In some embodiments, treating the ceramic slip to obtain a dried or at least partially dried ceramic starting material comprises spray drying the ceramic slurry, for example, to prepare a pellet ceramic starting material. . In some embodiments, the ceramic slurry is spray dried into granulated material, which can then be passed through a sieve having a mesh size of no greater than about 2000 μm to remove oversized particles. for example, oversized particles which may be formed by sticking along the walls of the spray dryer, for example a spray drying tower. In some embodiments, the screen has a mesh size of not greater than about 1500 μm, for example not greater than 1000 μm or not greater than about 750 μm or not greater than than about 500 pm or no greater than about 250 pm. Also provided is a ceramic formulation comprising a ceramic precursor or a plurality of ceramic precursors, a temperature-sensitive gelling agent, a solvent and having a viscosity suitable for low-pressure injection molding, having a for example, a viscosity of about 0.1 to 10.0 Pa.s at a shear rate of 100 s-1, as can be determined using a Haake rheometer at 65 ° C. In some embodiments, the ceramic formulation can be obtained by mixing the dried or partially dried ceramic starting material with a suitable amount of solvent to obtain a ceramic formulation having the desired viscosity suitable for low-pressure injection molding. pressure. Advantageously, the solvent is water. In some embodiments, the ceramic formulation has a viscosity of from about 0.5 to about 10 Pa.s, for example from about 0.5 to about 8 Pa.s or from about 0.5 to 7 Pa. or from about 0.5 to 6 Pa.s or from about 0.5 to 5 Pa.s or from about 0.5 to 4 Pa.s or from about 1.0 to about 8 Pa. or about 2 to about 7 Pa.s or about 3 to about 7 Pa.s or about 4 to about 6 Pa.s. It is seen that the ceramic formulation will have a larger solvent content, often significantly greater, than the ceramic starting material from which it is prepared. In some embodiments, the ceramic starting material is used to prepare the ceramic formulation according to the fifth facet of the present invention. Advantageously, the ceramic formulation is suitable for low pressure injection molding at a relatively high solids content, for example at a solids concentration of at least about 40% by volume or at least about 50% solids. in volume. In some embodiments, the ceramic formulation has a solids concentration of about 50% by volume to about 80% by volume or about 50% by volume to about 70% by volume or about 50% by volume. volume at about 65% by volume or about 50% by volume to about 60% by volume. In some embodiments, the solids concentration of the ceramic formulation is at least about 51% by volume or at least 52% by volume or at least about 53% by volume or at least about 54% by volume or at least about 55% by volume or at least about 56% by volume or at least about 57% by volume or at least about 58% by volume or at least less about 59% by volume. Advantageously, the ceramic formulation can be prepared by mixing the ceramic starting material with an appropriate amount of solvent at a temperature above the gel point of the gelling agent. Normally, the solvent, for example water, will be heated to the required temperature, for example from about 60 ° C to about 100 ° C or from about 60 ° C to about 80 ° C, and then combined. to the ceramic starting material. In some embodiments, the required temperature is lower than the melting point of the gelling agent. In some embodiments, mixing is performed in the mixing tank of a low pressure injection molding device. In an exemplary embodiment, a flow chart of a ceramic starting material / ceramic formulation preparation is shown in Figure 1 (a). The method comprises the preparation of a ceramic slip comprising a ceramic precursor or a plurality of ceramic precursors in the form of powder (for example, a ceramic powder), water (as a solvent) and dispersant (for example, polyacrylate, such as sodium polyacrylate). The ceramic slurry is prepared by mixing these constituents by any suitable means. In some embodiments, the ceramic slip is prepared by grinding, for example by grinding the balls, the mixture of ceramic powder, water and dispersant. Independently, agarose is mixed with water and optional additives, such as a reinforcing additive (eg, fructose) and heated to a temperature suitable for dissolving the gelling agent. In certain embodiments in which the gelling agent is agarose, the mixture of gelling agent and solvent is brought to a temperature above about 80 ° C, for example above about 85 ° C or greater than about 90 ° C. The ceramic slurry is preferably carried at a temperature above the freezing point of the gelling agent, and the solution of the gelling agent and optionally additives to the ceramic slurry are mixed. The ceramic slurry can be mixed until homogeneity is achieved. The resulting ceramic slurry is then treated to obtain a dried or dried ceramic starting material in less than a portion. The treatment may comprise (1) cooling of the ceramic slip below the gel point of the gelling agent, fragmentation of the resulting gelled cooling material, drying and grinding of chilled cooled ceramic gelled, In order to prepare the ceramic formulation for low pressure injection, the ceramic is mixed with the material or (2) the ceramic. a mold ceramic filler material dried or dried at least in part simply with water at a temperature above the gel point of the agarose, for example from about 60 ° C to about 90 ° C or about 60 ° C to about 80 ° C. The ceramic formulation is then ready for low pressure injection molding. In some embodiments, the ceramic formulation (i.e., a ceramic formulation according to the first aspect of the present invention and having a solids concentration of at least 50% by volume) is prepared by a according to the second aspect of the present invention. Thus, in some embodiments, the ceramic formulation is made by a method comprising: providing at least one pre-dispersed ceramic precursor; a solution or suspension comprising a solvent and at least one pre-dispersed ST gelling agent, optionally with reinforcing additive and binder other than the gelling agent; and mixing the at least one pre-dispersed precursor and the suspension solution to form the ceramic formulation. The various constituents and their amounts of the ceramic formulation described herein, for example the ceramic precursor, the solvent, the ST gelling agent, the dispersant, the reinforcing additive and the like, are those described above in connection with with the ceramic formulation according to the third facet and / or the ceramic starting material and its preparation.
[0017] In some embodiments, the at least one pre-dispersed ceramic precursor is in dry form or partially dried (for example, having a residual solvent content of up to about 15% by weight based on the weight total of the pre-dispersed ceramic precursor). In some embodiments, the solution or suspension is provided by adding a solvent to a dry or partially dried powder, including the pre-dispersed gelling agent. The solvent may be the same solvent used to prepare the pre-dispersed ceramic precursor. In some embodiments, the method further comprises bringing the solution or suspension to a temperature above the gel point of the gelling agent, for example at a temperature no greater than at about 100 ° C, before mixing it with the at least one pre-dispersed ceramic precursor. In some embodiments, the temperature is not greater than about 95 ° C or not more than about 90 ° C or not more than about 85 ° C or not more than about 80 ° C vs. In addition or alternatively, the method may further include bringing the ceramic formulation to a temperature above the gel point of the gelling agent, for example at a temperature of no greater than about 100 ° C or less greater than about 95 ° C or not more than about 90 ° C or not more than about 85 ° C or not more than about 80 ° C. In some embodiments, the pre-dispersed ceramic precursor is heated prior to mixing with solvent and solution or suspension, for example at a temperature above the gel point of the gelling agent or at a temperature at about 20 ° C from the gel point or at about 20 ° C from the freezing point or about 10 ° C from the freezing point. In some embodiments, the pre-dispersed ceramic precursor is not heated prior to mixing with the solution or suspension. In these embodiments, the pre-dispersed ceramic slip is added slowly enough to avoid (i) the temperature of the mixture falling below the freezing point of the gelling agent and / or (ii) ) to gel the mixture. In some embodiments, mixing is performed in the mixing tank of the low pressure injection molding apparatus. In another illustrative embodiment, a flowchart of a preparation of a ceramic formulation is shown in Fig. (B). The process comprises preparing a ceramic slip comprising a ceramic precursor or a plurality of ceramic precursors in the form of powder (eg, ceramic powder), water (as a solvent) and dispersant (eg for example, polyacrylate, such as sodium polyacrylate). The ceramic slurry is prepared by mixing these components in any suitable manner. Optional additives can be mixed with the ceramic slurry. In some embodiments, the ceramic slurry is prepared by grinding, for example by grinding the balls, the mixture of ceramic powder, water and dispersant. The ceramic slurry can be mixed until homogeneous. The resulting ceramic slurry is then treated to obtain a dried or dried ceramic starting material at least in part, for example by spray drying. Independently, the gelling agent is obtained, for example agarose, optionally mixed with optional additives, such as a reinforcing agent (eg, fructose). If optional additives are included, the gelling agent and the optional additives can be dry blended. To prepare the ceramic formulation for low pressure injection molding, the gelling agent (optionally comprising a dry blend) is mixed with water and optional additional binder and / or dispersant and the gate at a temperature above the gel point of the gelling agent, for example from about 60 ° C to about 90 ° C or from about 60 ° C to about 80 ° C forming a solution / suspension pre-dispersed gelling agent. The ceramic starting material, preferably at a temperature above the gel point of the gelling agent, is carried and mixed with the solution / suspension of the pre-dispersed gelling agent. The obtained ceramic formulation is then ready for pressure-based injection molding. In some embodiments, the ceramic starting material and the pre-dispersed gelling agent are independently prepared at a first location and then transported to a second location where a solution or suspension of the agent is prepared. pre-dispersed gelling agent and then combined with the ceramic starting material to prepare the ceramic formulation. In some embodiments, the ceramic starting material and the pre-dispersed gelling agent are prepared independently at different locations and then transported to another location for the preparation of a ceramic formulation.
[0018] In some embodiments, a ceramic article is formed by a process comprising forming a green gelled ceramic body from the ceramic formulation comprising a ceramic precursor or a plurality of ceramic precursors, temperature-sensitive gelling of the solvent and having a solids concentration of at least 50% by volume and baking the green gelled ceramic body to form a sintered ceramic article. To form is to transform the ceramic formulation into a green body of any desirable shape, for example in the form of a plate (for example, a tile), a panel or a brick, a cylinder , a sphere 15 or a complex shape, for example a complex mesh shape. The oven can be baked at any temperature appropriate to the type of ceramic material. Thus, for example, carbide based ceramics may require an oven at temperatures up to about 2300 ° C. The baking can be carried out at a temperature of about 900 ° C to about 2500 ° C. The baking can be carried out at a temperature of at least 900 ° C, for example at least about 1000 ° C or at least about 1100 ° C or at least about 1200 ° C. or at least about 1250 ° C or at least about 1300 ° C or at least about 1350 ° C or at least about 1400 ° C or at least about 1450 ° C or at least about 1500 ° C or at least about 1550 ° C or at least about 1600 ° C or at least about 1650 ° C or at least about 1700 ° C vs. The baking temperature may be less than about 2000 ° C, for example less than about 1750 ° C or less than about 1500 ° C or less than about 1450 ° C or less than about 1300 ° C. The baking time may vary depending on the type of ceramic material. Thus, for example, a baking time may be any suitable duration of up to about 96 hours or up to about 72 hours. The baking time can range from about 5 hours to 48 hours, for example from about 10 hours to about 36 hours, for example from about 10 hours to about 24 hours.
[0019] In some embodiments, the baking time is from 15 minutes to 120 minutes, for example from about 20 minutes to about 90 minutes, for example from about 20 minutes to about 60 minutes.
[0020] The gelled ceramic body may be dried, for example, at a temperature of at least about 100 ° C, for example about 105 ° C, and baked at an appropriate temperature for a period of time suitable for forming an article. sintered ceramic. The drying and baking conditions will depend on the composition and processing conditions, the formation, the size of the green body and the nature of the equipment. The oven can be baked in any suitable oven. Advantageously, the formation comprises low pressure injection molding of the ceramic formulation and cooling of the molded formulation below the gel point of the gelling agent thereby forming the gelled ceramic body. In some embodiments, low pressure injection molding is performed at a relative pressure of less than about 10 bar, optionally, while the ceramic formulation is at a temperature of not more than about 80 ° C. during injection molding. In general, during injection molding, the ceramic formulation is maintained at a temperature below the melting point of the gelling agent and above the gel point of the gelling agent. In some embodiments, the temperature of the ceramic formulation during injection molding and at least about 50 ° C, for example at least about 55 ° C or at least about 60 ° C. In some embodiments, low pressure injection molding is carried out at a relative pressure of from about 0.1 bar to about 10 bar, for example from about 0.5 bar to about 8 bar or about 1 bar. bar at around 6 bar. As described herein, the ceramic objects that can be obtained from the ceramic formulation are many and varied. They include tableware, including utensils, containers and the like, designed to store or serve food. The tableware can be porcelain. They include sanitary appliances, including toilets, bowls and the like, as well as other bathroom equipment, such as bathtubs and shower trays and columns. The sanitary article may be porcelain. Oven equipment items include trays and posts and the like used to support products within the oven. Refractory materials include refractory coatings, such as coatings for cupola floors and a siphon, blast furnaces, main, secondary and tilt channels, receptacles or jars of containers, pouches, baskets. casting, reaction chambers and troughs which contain, direct flow or are suitable for facilitating the industrial processing of liquid and slag metals, or other solid liquids or gases at high temperatures. The refractory materials also include refractory objects, such as those described above and pre-shaped objects, in whole or in part, such as refractory bricks and crucibles. Technical grade ceramic articles include highly heat resistant tiles, such as those used in space vehicles, gas burner nozzles, crucibles, molds and foundry cores, filters for molten metal, structured heat exchangers, such as honeycombs or random packings, solder rings and supports, ballistic protection, for example armor inserts for the body, biomedical implants, reaction motor turbine coatings, and parts thereof, such as vanes, ceramic disc brakes, missile nose cones, bearings and the like. Other technical grade ceramics include parts used for electrical applications, such as plugs, sockets, insulators, resistor carriers, spark plugs, ignitors, fuses, and the like. Other technical grade ceramics include parts used for filtration or catalyst applications, such as molecular sieves, fluid and gas filters, catalytic bed supports, and the like. Other technical grade ceramics include component parts of screens, windows, rods, vessels, semiconductors, optical lenses and glass fibers. EXAMPLES Control Example 1 The evolution of the viscosity of an agar solution (water) at 1.0% by weight is checked and depicted in FIG. The heating cycle begins at about room temperature (about 25 ° C) and ends at about 95 ° C, followed by the cooling cycle. It can be seen that complete dissolution takes place at about 90 ° C. and that the gel point (at cooling) is below 40 ° C., as indicated by the rapid and marked increase in viscosity between 40 and 30 ° C. vs.
[0021] Control Example 2 A dissolution-gelation-dissolution cycle is carried out on a 1.0% by weight (water) agarose solution. A total of three cycles are performed. The strength of the agarose gel after each cycle is measured and shown in FIG. It can be seen that the strength of the gel decreases with each cycle. But, all gels have a gel strength significantly greater than 10 kPa, which is the minimum value for ceramic gel casting.
[0022] Gel Force: Referring to Fig. 7, a compressive load is applied to a gelled body (generally cylindrical with a cross-section of 1,256 mm 2 and a height of 25 mm) at room temperature , using a cylindrical indenter (3) (with a cross section of 78.5 mm 2 and a length of 50 mm), at a speed of 4 N / min. The arrow in Figure 7 indicates the direction of movement of the indenter towards the gelled body. A mark (ring) (7) is made at a distance of 2 mm from the bottom of the cylindrical indenter. The cylindrical indenter is supported from above by a suitable box (5). The box comprises or is attached to means (not shown) for raising and lowering the cylindrical indenter (3). The gelled body (9) is supported from below by a suitable tray (11). At the beginning of the charge, the gelled body (9) deforms elastically. As the charge increases, the penetrator (3) enters the barrel of the gelled material (9) or the body (9) cracks. The load at which a 2 mm penetration of the cylindrical indenter (3) in the body of the gelled material (9) is observed or at which the body (9) splits corresponds to the compression force of the gel. Control Example 3 Example 3 is repeated for a gelling solution comprising 1.0% by weight of agarose and 1.0% by weight of fructose. The strength of the agarose / fructose gel after each cycle is measured and shown in Figure 4. The results of Example 2 are included for comparison purposes. It is seen that the addition of fructose improves / retains the strength of the gel on repeated gelation cycles. EXAMPLE 4 Two porcelain ceramic starting materials are prepared according to the procedure shown in FIG. 1. In each case, porcelain ceramic starting material is obtained by the treatment route 1, i.e. say cooling, followed by fragmentation, drying and grinding. Each starting material has a residual water content of about 0.5% by weight. The details of the compositions of the starting material are given in Table 1. Each starting material is mixed with hot water (75 ° C.) in the mixing tank of a low-pressure injection molding machine (Peltzamn). ), forming a ceramic formulation. A range of formulations having a solids loading ranging from 40% by volume to 60% by volume is prepared. Each ceramic formulation (under a pressure smaller than 10 bar) is injected into a non-porous mold. The moldings are cooled below the gel point of the agarose and demolded. The properties of newly gelled bodies, particularly strength, indicate their ability to be handled safely before drying and baking. The breaking force and the creep of the bodies which have just been gelled are determined. The results obtained are shown in Figures 5 and 6.
[0023] Table 1 Samples ab Composition (parts) Porcelain 99.99 99.99 Dispersant 0.1 0.1 Agarose 1.0 1.0 Fructose 0.0 1.0 Breaking Strength: The test procedure and equipment are The gelled samples (generally, a cylindrical body) have a diameter of 27 mm and a height of 30 mm are slightly modified with respect to the procedure used to determine the gel strengths of the pure gels of Control Examples 2 and 3. Instead of the cylindrical indenter (3), as shown in FIG. 7, the indenter (13) has a blunt edge (15), as shown schematically in FIGS. 8A and 8B. Figure 8B is a view of the indenter turned 90 ° to the view of Figure 8A.
[0024] During compression, the indenter (13) is lowered into the top of the gelled body at a rate of 1 mm / min. The maximum force measured during the load is taken as the breaking force of the sample. Creep: Creep measurement was performed on gelled slip pieces having a solids loading of 52% by volume. It evaluates the tendency of the piece that has just been gelled to deform / collapse slowly under its own weight after demolding. The test specimen is cylindrical with a diameter of 27 mm and a height of 30 mm. During the test, the specimen is placed between two trays (standard compression testing equipment). The device is similar to that shown in Figure 7, except that the indenter is replaced by an upper plate which is parallel to a bottom plate (11). A constant uniaxial load of 2 N is applied for a period of 5 minutes. The creep corresponds to the deformation in height of the specimen. Example 5 A porcelain ceramic starting material is prepared according to the procedure shown in Figure 1b. Porcelain ceramic starting material is obtained by ball milling followed by spray drying. The starting material has a residual water content of about 5% by weight. Details of the composition of the starting material are given in Table 2. Table 2 Constituent Composition (Portions) Porcelain 99.9 Dispersant 0.1 Independently, agarose is mixed with hot water (100 ° C.). C) in the mixing tank of a low-pressure injection molding machine (Cerinnov). Once the agarose is well dissolved, the temperature of the vessel is lowered to 80 ° C. and the dispersant and additional porcelain ceramic starting material are added and mixed into the mixing tank to form a ceramic formulation. . A series of formulations having a solids content of about 53% by volume and a viscosity of about 5.6 Pa.s at a shear rate of 100 s -1 are prepared. Each ceramic formulation (under a pressure of less than 10 bar, the injection time varying from 5 to 60 seconds for a 118 cm 3 piece) is injected into a non-porous cooled mold. The molded pieces (30 seconds) are cooled to below the freezing point of the agarose and demolded. Pieces that have just been gelled can be handled safely before drying, baking, glazing and baking.

权利要求:
Claims (29)
[0001]
REVENDICATIONS1. A ceramic formulation comprising a ceramic precursor or a plurality of ceramic precursors, a temperature-sensitive gelling agent having a solids concentration of at least 50% by volume, further characterized in that the formulation The ceramic material has a viscosity suitable for low-pressure injection molding, for example having a viscosity of not more than 10 Pa.s at a shear rate of 100 s-1 at a temperature higher than the gel point of the gelling agent.
[0002]
Ceramic starting material comprising a ceramic precursor or a plurality of ceramic precursors and a temperature-sensitive gelling agent, characterized in that the ceramic starting material is dried or is at least partially dried and has a content of in solvent up to about 15% by weight, based on the total weight of the ceramic starting material.
[0003]
Ceramic starting material according to Claim 2, characterized in that the starting material can be obtained by a process in which: a ceramic slurry comprising a ceramic precursor or a plurality of precursors is prepared, obtained or obtained. ceramic, temperature sensitive gelling agent, solvent and optionally dispersant and / or reinforcing additives and / or binder other than the gelling agent; and treating the ceramic slurry to obtain a ceramic starting material dried or dried at least in part with a residual solvent content of up to about 15% by weight based on the total weight of the starting material of the present invention. ceramic.
[0004]
4. Ceramic starting material according to claim 2 or 3, in the form of powder, granules or lozenges.
[0005]
A process for the preparation of at least partly dried or dried ceramic starting material having a residual solvent content of up to about 15% by weight, in which process is prepared, obtained or obtained ceramic slurry comprising a ceramic precursor or a plurality of ceramic precursors, the temperature-sensitive gelling agent, the solvent and optionally the dispersant and / or the reinforcing additive and / or the binder other than the agent gelation; and treating the ceramic slurry under suitable conditions to obtain a ceramic starting material dried or dried at least in part with a residual solvent content of up to about 15% by weight, based on the total weight of the ceramic slurry. the ceramic starting material.
[0006]
6. A process for the preparation of a ceramic formulation, wherein: a ceramic slip comprising a ceramic precursor or a plurality of ceramic precursors, a temperature-sensitive gelling agent is prepared, obtained or obtained, solvent and optionally dispersant and / or reinforcing additive and / or binder other than the gelling agent; the ceramic slip is treated under conditions suitable for obtaining a dried or dried ceramic starting material at least in part; the dried or dried ceramic starting material is mixed at least in part with an appropriate amount of additional solvent at a temperature above the freezing point of the gelling agent to obtain a ceramic formulation having a viscosity suitable for injection molding at low pressure.
[0007]
Ceramic starting material according to claim 3 or 4 or method according to claim 5 or 6, wherein the ceramic slip is prepared by an operation comprising: mixing the ceramic precursor or the plurality of ceramic precursors with solvent and optionally to dispersant and heating; dissolving independently of the gelling agent in a solvent optionally with reinforcing agent and binder; and mixing the precursor or precursors with solvent, and optionally dispersant, with the dissolved gelling agent.
[0008]
Ceramic starting material according to claim 3, claim 4 or claim 7 or method according to claim 5, claim 6 or claim 7, wherein treating the ceramic slurry comprises: (i) cooling the ceramic slurry below the freezing point of the gelling agent, breaking down the resulting cooled ceramic gelled material, drying and milling the fragmented chilled ceramic gelled material; or (ii) spray drying the ceramic slurry.
[0009]
A process according to claim 6, 7 or 8, wherein mixing the dried or dried ceramic starting material at least in part with an appropriate amount of additional solvent comprises mixing the ceramic starting material with water having a temperature above the freezing point of the gelling agent, optionally the temperature being lower than about 90 ° C, and optionally the mixing being performed in a mixing tank of a low pressure injection molding device.
[0010]
A process for making a ceramic formulation according to claim 1, wherein: at least one pre-dispersed ceramic precursor is provided; a solution or slurry comprising a solvent and at least one temperature-sensitive and pre-dispersed gelling agent, optionally with reinforcing additive and binder other than the gelling agent; andmixing the at least one pre-dispersed ceramic precursor and the solution or suspension to form the ceramic formulation.
[0011]
11. The process of claim 10 wherein the at least one dispersed ceramic precursor is provided in a dry or partially dry form.
[0012]
The process of claim 10 or claim 11, wherein the solution or slurry is obtained by adding a solvent to a dry or partially dry powder comprising the pre-dispersed gelling agent.
[0013]
The process of any one of claims 10 to 12, further comprising heating the solution or suspension to a temperature above the gel point of the gelling agent, optionally not higher than about 100 ° C, before mixing with the at least one pre-dispersed ceramic precursor.
[0014]
The process of any one of claims 10 to 13, further comprising heating the ceramic formulation to a temperature above the gel point of the gelling agent, optionally not higher than about 80 ° C.
[0015]
A method of forming a ceramic article, the method comprising: forming a green gelled ceramic body from a ceramic formulation comprising a ceramic precursor or a plurality of ceramic precursors, the gelling agent temperature sensitive, solvent and having a solids concentration of at least 50% by volume; optionally drying the raw gelled ceramic body; and baking the green gelled ceramic body to form a sintered ceramic article.
[0016]
The process of claim 15, further comprising preparing a ceramic formulation according to the process of any one of claims 10 to 14.
[0017]
The method of claim 15 or 16, wherein forming comprises low pressure injection molding the ceramic formulation and cooling the molded formulation below the gel point of the gelling agent.
[0018]
The method of claim 17, wherein the injection molding is performed at a relative pressure of less than about 10 bar, optionally while the ceramic formulation is at a temperature of not more than about 80 ° C. during injection molding.
[0019]
Ceramic article obtainable by the process of any one of claims 15 to 18.
[0020]
The ceramic starting material, ceramic formulation or process according to any one of the preceding claims, wherein the temperature sensitive gelling agent is selected from one or more of a polysaccharide, gelatin, a polysaccharide, a poloxamer and mixtures thereof.
[0021]
The ceramic starting material, ceramic formulation or process of claim 20, wherein the temperature sensitive gelling agent is a polysaccharide or a mixture of polysaccharides.
[0022]
The ceramic starting material, ceramic formulation, or method of claim 21, wherein the polysaccharide is selected from one or more of agar, agarose, and gum arabic.
[0023]
23. Ceramic starting material, ceramic formulation or process according to any one of the preceding claims, wherein the temperature-sensitive additive has a gel point lower than about 60 ° C.
[0024]
24. Ceramic starting material, ceramic formulation or process according to any one of the preceding claims, further comprising dispersant and / or reinforcing additive and / or binder other than the gelling agent.
[0025]
The ceramic starting material, ceramic formulation or process according to claim 24, wherein the dispersant is selected from the group consisting of a condensation product of formaldehyde and sulfonated naphthalene (CFNS), polyelectrolytes such as polycarboxylic acids. , polyacrylates and copolymers containing polyacrylate species, in particular polyacrylate (for example, sodium and aluminum salts, optionally with a salt of a Group II metal), polyphosphonates, sodium hexametaphosphates, a nonionic polyol, polyphosphoric acid, condensed sodium phosphate, nonionic surfactants and alkanolamines.
[0026]
The ceramic starting material, ceramic formulation or process of claim 24 or 25, wherein the reinforcing additive is a monosaccharide or a polysaccharide other than the temperature sensitive gelling agent.
[0027]
Ceramic starting material, ceramic formulation or process according to any one of the preceding claims, wherein the ceramic precursor or the several ceramic precursors are suitable for the manufacture of ceramics selected from tableware, sanitary ware , porcelain statues or decorative figurines, kiln equipment, refractory materials and technical grade ceramics.
[0028]
A ceramic starting material, ceramic formulation or process according to any of the preceding claims, wherein the ceramic precursor or the plurality of ceramic precursors are selected from alumina, aluminosilicate, nepheline syenite, feldspar, talc, mica, quartz, silica, titanium oxide, zirconium oxide, zirconium silicate, wollastonite, perlite, diatomaceous earth, carbonate or metal sulphate alkaline earth metals, such as calcium carbonate, magnesium carbonate, dolomite and plaster, a carbide, such as silicon carbide, boron carbide, tungsten carbide and titanium carbide, boron nitride, silicon nitride, a silicide, such as nickel silicide, sodium silicide, magnesium silicide, platinum silicide, titanium silicide, tungsten silicide, cerium oxide, 'yttrium, a ferrite, such as zinc-iron ferrite, barium ferrite, strontium ferrite, a garnet, such as yttrium-aluminum garnet, a titanate, such as barium titanate, lead titanate, graphite or other carbon-based precursor materials and combinations thereof.
[0029]
Ceramic starting material, ceramic formulation or process according to any one of the preceding claims, wherein the solvent is an aqueous solvent, for example being water.

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法律状态:
2016-06-28| PLFP| Fee payment|Year of fee payment: 2 |

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2017-06-27| PLFP| Fee payment|Year of fee payment: 3 |

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2018-06-26| PLFP| Fee payment|Year of fee payment: 4 |

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2020-06-25| PLFP| Fee payment|Year of fee payment: 6 |

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2021-06-25| PLFP| Fee payment|Year of fee payment: 7 |

优先权:

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申请号 | 申请日 | 专利标题

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EP14290162|2014-06-04|

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