A set of chemicals for manufacturing ceramic dispersions or ceramic gels.

Abstract

Provide a set of chemicals for the production of ceramic dispersions or ceramic gels. The present invention relates to a set of chemicals for the production of ceramic dispersions or ceramic gels, a manufacturing process for ceramic molded parts, and ceramic molded parts manufactured by this process.

Description

Technical Field

[0001] The present invention relates to a set of chemicals for producing a ceramic dispersion or a ceramic gel, which is preferably suitable for the production of ceramic shaped parts such as ceramic veneers, or shaped bodies such as ceramic partial crowns, veneers, ceramic inlays, and onlays, by a layer build-up process such as stereolithography. The present invention also relates to a method for producing a ceramic shaped part and a ceramic shaped part produced by this method.

Background Art

[0002] In a layer build-up process for producing a ceramic veneer or a shaped body, a ceramic gel or a ceramic dispersion containing a (curable) polymer material is applied layer by layer to a substrate and continuously dried, for example, by exposure to radiation or heat, either simultaneously or downstream. This produces a so-called ceramic "green body". Next, a debinding process is carried out, that is, usually a polymeric binder is discharged at a high temperature, producing a so-called "white body". During the debinding process, the binder is converted by heat and / or a thermochemical process, at least partially changing the polymer repeating units and at least partially decomposing into volatile components.

[0003] The white body is sintered in a sintering furnace during high-temperature firing. The finely dispersed ceramic powder is compressed and solidified under the influence of temperature, and the porous components shrink and the strength increases.

[0004] However, the layer build-up process always has the drawback that defects such as cracks and bubbles occur during heating, especially in the debinding process, rendering the member unusable. This effect can usually only be addressed by slowing down the heating process, that is, by increasing the heat treatment time, but then the corresponding manufacturing process becomes uneconomical.

[0005] For example, Patent Document 1 discloses a curable composition for the production of three-dimensional bodies by stereolithography, the composition comprising 40 to 70 volume percent of ceramic or metal particles, 10 to 35 wt percent of monomer, 1 to 10 wt percent of photoinitiator, 1 to 10 wt percent of dispersant, and preferably a solvent, a plasticizer, and a coupling agent.

[0006] Patent Document 2 provides a slurry for manufacturing ceramic molded parts by a hot-melt inkjet printing process, comprising ceramic particles and one or more waxes that are polymerizable by free radicals and produce a green body that can be substantially debindered without cracking. However, in the stereolithography process, the slurry needs to remain stable in a liquid state for a long period of time, that is, it is necessary to prevent the particles dispersed in the slurry from settling prematurely, which presents particular problems in terms of achieving the desired maximum volume fraction of ceramic particles in the slurry.

[0007] Patent Document 3 discloses a stereolithography-based process that overcomes at least some of the aforementioned drawbacks. However, here again, a radical polymer precursor is used to generate the binder.

[0008] However, such radical reactions have a drawback, particularly in silicate ceramic gels, where free radicals can damage other components of the composition, potentially leading to discoloration. Furthermore, in radical reactions with high conversion rates, the reaction rate is observed to increase exponentially (Trommsdorff-Norrish effect). This effect is due to a decrease in the probability of chain termination by recombination of highly reactive chain ends, which is caused by increased immobility of the growing polymer chains. As a result, the rate of exothermic reactions increases, the temperature rises, the decomposition of radical initiators accelerates, and the concentration of reactive molecules increases. Simultaneously, the increased viscosity makes it more difficult to dissipate the reaction heat (polymerization heat). Consequently, localized overheating can occur, potentially causing cracking, explosion, or decomposition of other components of the ceramic composition when applied in multiple layers. In addition, the mechanical properties and durability of ceramic molded parts obtained from known compositions are limited, with a particular problem of susceptibility to cracking and decomposition. Furthermore, the stability / storability of ceramic compositions is also limited. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] U.S. Patent No. 5,496,682 [Patent Document 2] European Patent Application Publication No. 2233449 [Patent Document 3] European Patent Application Publication No. 3 147707 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Therefore, against this background, the object of the present invention is to provide a set of chemical substances that can overcome the aforementioned drawbacks. The set of chemical substances according to the present invention is intended to enable a simple build-up process for silicate mineral-based ceramic gels or ceramic dispersions, from which high-quality, less discolored ceramic molded parts can be obtained. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a photograph of the white body obtained in "Manufacturing Example 1" before firing. [Figure 2] Figure 2 shows the same white body after being baked at 950°C for 60 minutes. Description of the Invention

[0012] This problem is solved by a set of chemicals for producing a ceramic gel, according to this invention. This set consists of the following components, namely A) Preferably a powdered ceramic material, and B) Includes binder, Ceramic materials Selected from the group consisting of feldspar ceramics and leucite ceramics. The material contains or consists of a silicate ceramic material, and the binder contains or consists of a gelling agent. The gelling agent is a cross-linked polymer. Preferably, Bridge The polymer has one or more repeating units. It is a polymer that does so One or more repeating units have one or more chelate functional groups.

[0013] This set of chemicals is suitable for the preparation of ceramic dispersions, particularly ceramic dispersions and / or ceramic gels. For this purpose, it is preferable to add a solvent and / or dispersant, such as water or alcohol, to the set of chemicals, or the set of chemicals may contain an equivalent solvent and / or dispersant. Preferably, this ceramic dispersion is suitable for use in stereolithography, binder jetting, or material jetting processes.

[0014] In colloid chemistry and process engineering, a dispersion is a heterogeneous mixture of two or more substances that do not dissolve or chemically bond with each other, either little to no. One or more substances are finely dispersed as a dispersed phase in another continuous substance called a dispersion medium.

[0015] A "gel" is an example of a dispersion system consisting of two or more components. The gelling agent, which is a solid component, forms a spongy three-dimensional network of long and / or highly branched molecules, and its pores are filled with a liquid (liogel) or a gas (xerogel). The liquid component is thus fixed to the solid component. When the network is highly porous and the gas is embedded with air, the gel is also called an aerogel.

[0016] As a scaffolding agent, gelling agents thicken the liquid phase and / or form a rubbery gel. Therefore, they can also be used as thickeners or to stably support emulsifications. They are classified into natural (e.g., agar), inorganic (e.g., bentonite), semi-synthetic (e.g., carboxymethylcellulose), and synthetic gelling agents (e.g., polyvinyl alcohol). Semi-synthetic and synthetic gelling agents are particularly preferred in this invention due to their high performance.

[0017] According to this invention, “solvent and / or dispersant” means a substance that is a liquid at standard conditions (temperature: 298.15K = 25℃, pressure: 1013.25mbar = 1013.25hPa) and in which at least some of the components of a set of chemical substances can be dissolved and / or dispersed.

[0018] According to the present invention, a "binder" is a substance or combination of substances that generates a stable dispersion or gel by retaining and stabilizing ceramic particles, particularly during heat treatment, enabling a uniform distribution. As an essential component, the binder according to the present invention includes or consists of a gelling agent such as a polymer containing a chelating functional group. The binder according to the invention also contributes to stabilizing the ceramic material in a finely dispersed state in a solvent and / or a dispersant, that is, when a solvent and / or a dispersant is used, it suppresses the sedimentation of the ceramic material and also makes it possible to completely prevent it.

[0019] In the context of the present invention, a "polymer" shall mean a chemical substance composed of macromolecules. A "macromolecule" is a molecule composed of one or more identical or similar structural units, which is a constitutional repeating unit (IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"), A.D. McNaught, A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), S.J. Chalk. ISBN 0-9678550-9-8). Such a macromolecule has 10 or more repeating units, preferably 15 or more repeating units. The molar mass is preferably 3,000 g / mol or more, more preferably 5,000 g / mol or more, still more preferably 7,000 g / mol or more, and most preferably 10,000 g / mol or more.

[0020] Polymers are usually produced by reacting monomers or oligomers having one or more constitutional repeating units in a polymerization reaction. An oligomer is a molecule formed from a plurality of monomers and thus structurally consists of a number of identical or similar structural units. When a molecule is produced from the reaction of 2 to 10 monomers, preferably 2 to 8 monomers, preferably 3 to 7 monomers, in the context of the invention, this is referred to as an oligomer.

[0021] The binder preferably contains 50% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, even more preferably 90% by weight or more, most preferably 95% by weight or more, or 100% of a gelling agent, and the gelling agent is preferably in the form of a polymer having a chelating functional group.

[0022] Preferably, the ceramic material contains 50% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, even more preferably 90% by weight or more, most preferably 95% by weight or more of a silicate ceramic material.

[0023] The silicate ceramic material is an inorganic non-metallic material obtained from a silicate raw material, that is, a compound having [SiO4] 4 -tetrahedrons in its crystal structure. The SiO2 content of the silicate ceramic material is preferably 20% by weight or more, more preferably 30% by weight or more. The term "silicate ceramic material" may include glass ceramics, but preferably does not include them. Preferably, the proportion of glass ceramics in the silicate ceramic material is less than 5% by weight, more preferably less than 2% by weight, still more preferably less than 1% by weight, even more preferably less than 0.5% by weight, most preferably less than 0.1% by weight.

[0024] According to this invention, the term "set of chemical substances" shall mean a predetermined composition, whether the individual chemical substances are in separate containers or exist as a composition in which some or all are mixed. Particularly preferably, the set of chemical substances exists as a composition in the form of a liquid, paste or solid.

[0025] The term "chelate functional group" refers to a functional group that can form a chelate. A chelate is a cyclic coordination compound having one or more central metal atoms or ions and a polydentate ligand, also known as a chelate ligand. A ligand is an ion or molecule that can bond to, i.e., coordinate to, the central metal atom or ion via a coordinate bond. The difference between a coordinate bond and a classical covalent bond is that in a coordinate bond, the ligand provides both bonding electrons, and thus the ligand becomes a "Lewis base." In this context, polydentate means that the ligand has two or more coordination sites to coordinate to the metal atom or ion. In other words, a chelate ligand needs to have two or more atomic groups that can act as electron donors.

[0026] In a preferred embodiment of the present invention, the chelate ligand has three or more, more preferably four or more, particularly preferably five or more, and most preferably six or more coordination sites.

[0027] The inventors have confirmed that by using a gelling agent according to the present invention, such as a polymer having a chelating group, a silicate ceramic dispersion, or a silicate ceramic gel, it is possible to produce ceramic particles having high stability, i.e., ceramic particles that have no tendency to separate or only a very slight tendency to separate. Furthermore, this composition has a structure that is easy to process while simultaneously possessing sufficient stability. This was previously impossible or only possible to an insufficient degree.

[0028] In particular, when using polymers with chelating groups, although not bound by this theory, the inventors believe that the chelating groups constitute polar interactions with the partially positively charged silicon atoms of the silicate ceramic, and as a result, stabilization can be achieved, especially in dispersions. Polymer materials having one or more chelating functional groups thus act as binders. The corresponding polymer material also increases the viscosity of the gel or dispersion, resulting in a fluid, easily processable, and especially sprayable material. This eliminates the need to use radically polymerizable polymer precursor compounds during manufacturing to ensure the processability of the corresponding ceramic gel.

[0029] The set of chemicals described in this invention makes it possible to produce ceramic gels or dispersions that are extremely delicate and capable of constructing fine particle structures. Furthermore, peripheral shrinkage observed during the debinding and sintering processes is minimal, meaning that volume changes are not significant. The inventors believe this is because the ceramic particles in the gel are uniformly dispersed. Moreover, the debinding process is particularly efficient and rapid.

[0030] To achieve particularly good processability of a gel or dispersion, it is preferable to increase its viscosity. To achieve this, the present invention by The gelling agent is a cross-linked polymer can be, More precisely, the polymers of the set of chemical substances are crosslinked. 。

[0031] Preferred gelling agents include chitosan or chitosan derivatives, polysaccharides such as alginic acid, xanthan gum or alginates, polyuronic acid, gelatin, hyaluronic acid, polyvinyl alcohol, polyethylene glycol, ammonium acryloyldimethyltaurate, hydroxypropyl starch (HPS), hydroxypropyl distarch phosphate (HDP), polyquaternium, especially 3-methyl-1-vinylimidazolium methyl sulfate-N-vinylpyrrolidone copolymer or poly(2-methacryloxyethyltrimethylammonium chloride), bentonite, sorbitan monooleate, polyethylene glycol triether or polypropylene glycol triether, propylene glycol dicaprylate / dicaprate, silicate clay, and The material is selected from the group consisting of and / or layered silicates, such as sodium-magnesium silicate or aluminum-magnesium silicate, montmorillonite-type sodium-magnesium, or sodium-magnesium-fluorine-lithium layered silicate, polyacrylamide, silica (such as Aerosil), sorbitan oleate decyl glucoside crosslinked polymer, styrene-maleic anhydride or ethylene-maleic anhydride copolymer and its derivatives, hydrophobized ethoxylate urethane, polyvinylpyrrolidone, amylopectin, cellulose or cellulose derivatives (e.g., cellulose acetobutyrate), polyacrylate or polymethacrylate and its esters, copolymers and / or salts, or mixtures and copolymers thereof. The above Gelling agent 、 It is preferable that the bridges are formed by covalent bonds.

[0032] The gelling agent is particularly preferably a hydrogel-forming polymer. A hydrogel is a gel composed of an insoluble polymer capable of binding to water. The molecules that form the gel are bonded together by chemical bonds such as covalent bonds, supramolecular bonds, and ionic bonds, or by physical bonds such as entanglement of polymer chains, forming a network capable of binding to solvents such as water. Polymers crosslinked by covalent bonds include, for example, thiolated polymers (thiomers) that crosslink polymer chains by forming disulfide bonds.

[0033] Superabsorbent polymers are a particularly preferred form of gelling agent. Preferably, the superabsorbent polymer ("super absorber") is a cross-linked polymer capable of absorbing polar solvents, such as water, several times its own weight. Upon absorption of liquid, the superabsorbent polymer swells and forms a hydrogel. The functions of superabsorbent polymers are described, for example, in Koltzenburg, S., Nuyken, O., Maskos, M. (2013). Polymers: Synthesis, properties and applications. Germany: Springer Berlin Heidelberg.

[0034] According to the present invention, the superabsorbent polymer is preferably a crosslinked copolymer having repeating units consisting of acrylic acid and / or sodium acrylate and / or acrylic acid ester.

[0035] According to the present invention, the superabsorbent polymer is preferably a crosslinked copolymer having repeating units consisting of methacrylic acid and / or sodium methacrylate and / or methacrylic acid ester.

[0036] Particularly preferred are crosslinked copolymers of acrylic acid and sodium acrylate, or crosslinked copolymers of acrylic acid and / or sodium acrylate and / or acrylamide, and especially crosslinked copolymers of acrylic acid, sodium acrylate and acrylamide.

[0037] Particularly preferred are crosslinked copolymers of methacrylic acid and sodium methacrylate, or crosslinked copolymers of methacrylic acid and / or sodium methacrylate and / or methacrylamide, and especially crosslinked copolymers of methacrylic acid, sodium methacrylate and methacrylamide. The corresponding copolymer is particularly preferably crosslinked with an allyl ether of sucrose or an allyl ether of pentaerythritol.

[0038] Carbomers, particularly those crosslinked with polyalcohols, polyalkene ethers (e.g., polyalcohol allyl ethers or polyalkene ethers of sugars), allyl ether sucrose, or allyl ether pentaerythritol, are especially preferred because they have a wide range of applications and are readily available.

[0039] Polymers containing one or more oxygen atoms in the chelating group have also proven to be particularly preferred in use. The inventors believe that the stabilizing effect is particularly high due to the particularly prominent Si-O interaction. The chelating group may be, for example, an acid group, base, or ester group contained in polyacrylic acid or polyacrylate. Polyvinylpyrrolidone or polyvinyl phosphonate has also proven to be particularly preferred. The polymers of the aforementioned polymers are particularly preferably crosslinked, and covalent crosslinking is preferred. In this context, the terms "bonding" and "crosslinking" are used synonymously and refer to the formation of a three-dimensional network by bonding of numerous polymers constituting the polymer. Crosslinking can be achieved directly during polymer formation or by reaction with an existing polymer. As a result, swelling is observed in the polymer, which has a positive effect on the dispersion medium.

[0040] The set of chemicals preferably includes polymerizable polymer precursor compounds such as monomers or oligomers in amounts of less than 5% by weight, more preferably less than 2% by weight, even more preferably less than 1% by weight, even more preferably less than 0.5% by weight, and most preferably less than 0.1% by weight.

[0041] Particularly preferably, the weight ratio of the polymerizable polymer precursor compound to the polymer in the set of chemical substances is 1:10 or more, preferably 1:50 or more, and especially preferably 1:100 or more.

[0042] By keeping the proportion of polymerizable compounds reasonably low, side reactions and decomposition reactions can be avoided during gel production.

[0043] Preferably, the binder and / or gelling agent have a low ashing residue, preferably 10% by weight or less, more preferably 5% by weight or less, even more preferably 1% by weight or less, quite preferably 0.5% by weight or less, and most preferably 0.2% by weight or less.

[0044] The ashing residue, i.e., the residue remaining after the heat treatment of ashing, can be determined, in particular, by thermogravimetric analysis, as described in DIN EN ISO 3451-1. The less ashing residue there is, the less discoloration the ceramic molded parts will undergo.

[0045] The set of chemicals according to the present invention preferably further comprises a solvent and / or a dispersant. In this context, polar and / or protic solvents, such as water and / or alcohols, particularly polyhydric alcohols such as ethylene glycol and monopropylene glycol, are especially preferred. These are particularly suitable for keeping the components of the gel or dispersion obtained from the set of chemicals dispersed or dissolved, thereby enabling processing of the gel or dispersion.

[0046] In preferred embodiments of the present invention, the weight ratio of the solvent and / or dispersant to the weight of the set of chemical substances is 5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, even more preferably 20% by weight or more, even more preferably 30% by weight or more, and most preferably 40% by weight or more, but generally 70% by weight or less.

[0047] Preferably, the weight ratio of the solvent and / or dispersant to the weight of the set of chemicals, excluding the weight of the ceramic material, is 50% to 99.9% by weight, more preferably 70% to 99% by weight, and most preferably 90% to 99% by weight.

[0048] In a preferred embodiment of the present invention, the weight ratio of the ceramic material to the weight of the set of chemical substances is 70% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, even more preferably 35% by weight or less, and most preferably 30% by weight or less, but preferably 20% by weight or more.

[0049] In preferred embodiments of the present invention, the weight ratio of the ceramic material to the weight of the set of chemical substances is in the range of 5 to 70% by weight, preferably 10 to 50% by weight, more preferably 15 to 40% by weight, and most preferably 20 to 35% by weight.

[0050] By moderately reducing the proportion of ceramic material, it is generally possible to manufacture gels that are highly fluid and easy to handle.

[0051] Particularly preferably, the composition further comprises one or more bases, particularly Brønsted bases, i.e., compounds whose monomolar aqueous solution has a pH > 7, preferably > 8. The base ensures that the interaction between the ceramic particles and the polymer material is improved. Particularly in the case of chelating groups with acidic function, the base plays a role in capturing protons, thereby further improving the complex formation strength of the chelating groups. This effect can be particularly observed in polyacrylic acid or polyacrylate and polyvinylphosphonic acid or polyvinylphosphonate. The base is particularly preferably selected from the group consisting of alkali metal and alkaline earth metal hydroxides, and alkali metal and alkaline earth metal carbonates. Particularly preferably, the base is selected from the group consisting of NaOH, KOH, Na2CO3, K2CO3, CaCO3, CaO and Ca(OH)2, NaHCO3, or mixtures thereof.

[0052] The set of chemical substances preferably contains 15% by weight or less, more preferably 10% by weight or less, even more preferably 5% by weight or less, even more preferably 1% by weight or less, and most preferably 0.5% by weight or less of a base. The minimum base content is preferably 0.05% by weight or more, more preferably 0.1% by weight or more.

[0053] Preferably, the weight ratio of base(s) to the weight of the set of chemicals, excluding the weight of the ceramic material, is 0.10% to 0.99% by weight, more preferably 0.20% to 0.8% by weight, and most preferably 0.3% to 0.7% by weight.

[0054] In preferred embodiments of the present invention, the set of chemicals preferably includes a biocide preservative as an additional component. The preservative plays a role in extending the shelf life of the ceramic gel or ceramic dispersion, particularly by preventing the degradation process. Sulfur-containing preservatives, such as isothiazolinones, are particularly preferred as preservatives. Their bactericidal and fungicidal effects prevent microbial degradation of the components of the set of chemicals. Particularly preferred are 5-chloro-2-methyl-4-isothiazolinone-3-one, 2-methyl-4-isothiazolinone-3-one, isothiazolinone-3-one, methylisothiazolinone, bendisothiazolinone, octylisothiazolinone, dichlorooctylisothiazolinone, or mixtures thereof. Alternatively, formaldehyde-releasing agents such as O-formaldehyde or N-formaldehyde are also suitable as preservatives. Particularly preferred are benzylhemiformaldehyde, 1,6-dihydroxy-2,5-dioxahexane, methylolurea, 7-ethylbicyclooxazolidine, methenamine, paraformaldehyde, tris(hydroxymethyl)nitromethane, or mixtures thereof.

[0055] The set of chemical substances preferably contains a preservative in an amount of 5% by weight or less, more preferably 2% by weight or less, even more preferably 1% by weight or less, even more preferably 0.5% by weight or less, and most preferably 0.25% by weight or less. The minimum content of the preservative is preferably 0.05% by weight or more, more preferably 0.1% by weight or more.

[0056] To suppress discoloration of ceramic gels or ceramic dispersions, the set of chemicals may further preferably include coloring components selected from transition metal compounds, particularly oxides of Er2O3, Fe2O3, Co3O4, MnO2, NiO2, Cr2O3, Pr2O3, Tb2O3, Bi2O3, and mixtures thereof. However, alternatively or additionally, acetylacetonates or carboxylates of iron, cerium, praseodymium, nickel, terbium, lanthanum, tungsten, osmium, terbium, and manganese may also be used.

[0057] It is preferable to select the coloring components so that tooth-colored ceramic molded parts can be obtained after binder removal treatment and sintering.

[0058] The coloring component can preferably also be included in the ceramic material. The ceramic material may also contain other additives such as fluids or release agents.

[0059] The set of chemical substances preferably contains less than 5% by weight of the above coloring component, more preferably 2% by weight or less, even more preferably 1% by weight or less, even more preferably 0.5% by weight or less, and most preferably 0.25% by weight or less. The minimum content of the above coloring component is preferably 0.05% by weight or more, more preferably 0.1% by weight or more.

[0060] In preferred embodiments of the present invention, the weight ratio of the ceramic material to the weight of the set of chemical substances is 40% by weight or more, preferably 50% by weight or more, more preferably 55% by weight or more, even more preferably 60% by weight or more, and most preferably 65% ​​by weight or more.

[0061] In a preferred embodiment of the present invention, the weight ratio of the ceramic material to the weight of the set of chemical substances is 95% by weight or less, preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, and most preferably 75% by weight or less.

[0062] In preferred embodiments of the present invention, the weight ratio of the ceramic material to the weight of the set of chemical substances is in the range of 50 to 90% by weight, preferably 55 to 85% by weight, more preferably 60 to 80% by weight, and most preferably 65 to 75% by weight.

[0063] Generally, by increasing the proportion of ceramic material, it is possible to obtain a very compact gel with low residual ash content.

[0064] Furthermore, a sufficiently high proportion of ceramic material significantly reduces the likelihood of mechanical damage occurring during the heat treatment of the ceramic gel or dispersion, resulting in more homogeneous ceramic molded parts.

[0065] In preferred embodiments of the present invention, the weight ratio of the gelling agent to the weight of the set of chemicals is, for example in the form of a polymer, 0.1% by weight or more, more preferably 0.2% by weight or more, even more preferably 0.5% by weight or more, even more preferably 1% by weight or more, even more preferably 1.5% by weight or more, even more preferably 1.5% by weight or more, even more preferably 2% by weight or more, and most preferably 2.5% by weight or more. This significantly stabilizes the ceramic material in the ceramic gel or ceramic dispersion. However, the weight ratio of the polymer is preferably 3.5% by weight or 4% by weight or less, which minimizes the residual ash generated by the heat treatment of the set of chemicals.

[0066] The weight ratio of the gelling agent to the weight of the set of chemicals, excluding the weight of the ceramic material, is preferably 0.10% to 0.99% by weight, more preferably 0.20% to 0.8% by weight, and most preferably 0.3% to 0.7% by weight.

[0067] The weight ratio of the ceramic material to the weight of the other components of the chemical set is preferably in the range of 1:1 to 5:1, more preferably 2:1 to 4:1, and most preferably 3:1 to 4:1. Furthermore, the ratio of ceramic powder to binder is very preferably 60:40 to 70:30.

[0068] The silicate ceramic is preferably selected from the group consisting of feldspar, leucite, lithium silicate, lithium disilicate, and lithium aluminosilicate ceramic. Feldspar ceramic is particularly preferred, and especially preferred in combination with polyacrylic acid and / or polyacrylate as polymers. A particularly remarkable stabilizing effect was observed in this combination.

[0069] The present invention also relates to compositions, particularly gels or dispersions, that consist of or contain a set of chemical substances. Preferably, the weight ratio of the set of chemical substances to the total weight of the composition is 10 to 70% by weight, more preferably 15 to 70% by weight, more preferably 20 to 60% by weight, even more preferably 25 to 60% by weight, and most preferably 30 to 60% by weight.

[0070] The gel or dispersion is preferably prepared by mechanically mixing component B) (i.e., the binder) and any other components (component C), component E), etc.) with a ceramic material (preferably in the form of ceramic powder).

[0071] Furthermore, this invention also relates to a method for manufacturing ceramic molded parts, which includes or consists of the following steps. a1) A step of mixing the components of the set of chemical substances defined above to obtain a gel or dispersion, b) A step of irradiating or heat-treating a gel or dispersion in a temperature range of 50°C to 150°C to obtain a green body, c) The step of removing the binder, preferably completely, by heat treatment or irradiation of the green body at least partially, preferably in a temperature range of 150°C to 350°C, to obtain a white body. d) To obtain a ceramic molded part, the process includes sintering the white body, or, if steps b) and / or c) are optional, heat-treating the green body or gel or dispersion in a temperature range of 700°C to 1000°C. The process steps are preferably performed at different times in the order of a1) to d).

[0072] Steps b) and c) above are optional and can be performed together as a single step, without any time interval between them. Ceramic molded parts can also be manufactured by omitting the intermediate step of producing the green body or white body. In step d), the binder is removed. However, performing these steps results in particularly high product quality.

[0073] The method for manufacturing ceramic molded parts according to the present invention preferably includes the following additional steps.

[0074] a2) A step of applying a gel or dispersion in layers to a surface, preferably a metal or zirconium copper or mounting die, preferably by a spray and / or 3D printing process, particularly preferably by multi-jet modeling.

[0075] This step is preferably performed between steps a1) and b), and particularly preferably separately in time from these steps.

[0076] Preferably, steps a2) and / or b) and / or c) and / or d) of the method according to the present invention are carried out in a rapid prototyping process, in particular a stereolithography process.

[0077] Furthermore, the present invention relates to ceramic molded parts manufactured by the method according to the present invention, such as crowns, crown components, veneers, ceramic inlays or onlays, bridge anchor crowns, bridge pontics, and their components. By using the set of chemicals according to the present invention in the above process, ceramic molded parts with particularly high homogeneity and a natural appearance can be obtained. Thus, they exhibit preferable properties compared to known ceramic molded parts of the prior art. Preferably, to obtain a white body, the binder is removed by heat treatment of the green body in a temperature range of 150°C to 350°C, particularly by irradiation with infrared light, which is carried out particularly quickly and homogeneously when using the gel or dispersion according to the present invention. In the above temperature range, the debinder treatment time can be 20 minutes or less, 15 minutes or less, or even 10 minutes or less.

[0078] Furthermore, ceramic molded parts manufactured by the method according to the present invention are characterized by high strength and attention to detail. The bending strength according to ISO 6872 is preferably greater than 50 MPa for molded bodies made of feldspar or glass ceramic, and is particularly preferably in the range of 100 to 500 MPa.

[0079] The present invention also, Selected from the group consisting of feldspar ceramics and leucite ceramics. Silicate ceramics and gels This also relates to the use of the combination with the cross-linked polymer inside to manufacture ceramic veneers.

[0080] The present invention also relates to the use of a gelling agent as a binder in a gel or dispersion for the manufacture of a ceramic molded body, wherein the gel preferably contains or consists of silicate ceramics.

[0081] Furthermore, the present invention is For the manufacture of ceramic veneers, use a crosslinked polymer, preferably a polymer having one or more repeating units, as a binder in the gel or dispersion. Related to this, More preferably, one or more of the repeating units Containing one or more chelate functional groups, this The gel contains or consists of silicate ceramics.

[0082] Examples The present invention will be explained below with specific examples, accompanied by corresponding photographs.

[0083] Manufacturing Example 1 Prepare a mixture of the following ingredients in a petri dish. 1) Deionized water (~70% by weight) 2) Carbomer (~17% by weight) 3) Sodium hydroxide (~3% by weight) 4) Monopropylene glycol (~7% by weight) 5) A mixture of 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, and isothiazolin-3-one (remainder).

[0084] After a uniform paste is obtained, feldspar or glass ceramic powder is added to this mixture. Add 3 to 4 times the amount of ceramic powder relative to the total mass of the mixture of components 1) to 5) so that a sprayable ceramic dispersion is obtained after mechanical mixing. Transfer the mixture to a 10 ml Coltene syringe and apply it in layers to the framework body. Then, heat treatment is performed at 150°C to obtain a green body. Further heat treatment at 300°C yields a white body, which is then fired at 950°C.

[0085] Manufacturing Example 2 Prepare a mixture of the following ingredients in a petri dish. 1) Deionized water (~98.5% by weight) 2) Carbomer (~1.0% by weight) 3) Potassium hydroxide (~0.5% by weight)

[0086] After a uniform paste is obtained, feldspar or glass ceramic powder is added to this mixture. To obtain a sprayable ceramic dispersion after mechanical mixing, the amount of ceramic powder is added in an amount of 3 to 4 times the total mass of the mixture of components 1) to 3). The mixture is transferred to a 10 ml Coltene syringe and applied in layers to the framework body. Then, it is heat-treated at 150°C to obtain a green body. Further heat treatment at 300°C yields a white body, which is then fired at 950°C.

[0087] Figure 1 is a photograph of the white body before firing, obtained in the above process, "Manufacturing Example 1". Figure 2 is a photograph of the same white body after firing at 950°C for 60 minutes. As can be seen from Figure 2, a ceramic component with a uniform closed structure is obtained.

Claims

1. A set of chemical substances containing the following components A and B, The component A is a ceramic powder material containing or consisting of a silicate ceramic material. The aforementioned component B is a binder containing or consisting of a gelling agent. The gelling agent is a crosslinked polymer, The silicate ceramic material is selected from the group consisting of feldspar ceramics and leucite ceramics. The aforementioned set of chemical substances includes a basic component as the additional component D, The weight ratio of the ceramic powder material to the weight of the set of chemical substances is in the range of 50 to 90% by weight. The weight ratio of the base component to the weight of the set of chemical substances is 15% by weight or less. A set of chemical substances characterized by being a gel or dispersion.

2. The set of chemical substances according to claim 1, wherein the crosslinked polymer comprises one or more repeating units.

3. The set of chemicals according to claim 1 or 2, wherein the binder is a superabsorbent polymer of a copolymer having repeating units of (meth)acrylic acid and / or sodium (meth)acrylate.

4. The set of chemical substances according to claim 1, wherein the set of chemical substances comprises, as an additional component C, a solvent and / or dispersant selected from the group consisting of water and alcohols.

5. The set of chemical substances according to claim 1, wherein the basic component is selected from the group consisting of hydroxides of alkali metals and alkaline earth metals, and carbonates of alkali metals and alkaline earth metals.

6. The set of chemical substances according to claim 1, wherein the set of chemical substances includes a biocide preservative as an additional component E.

7. The set of chemical substances according to claim 1, wherein the set of chemical substances includes, as an additional component F, a coloring component selected from Er2O3, Fe2O3, Co3O4, MnO2, NiO2, Cr2O3, Pr2O3, Tb2O3, Bi2O3 and mixtures thereof.

8. The weight ratio of the ceramic powder material to the weight of the set of chemical substances is 85% by weight or less. The chemical set according to claim 1, wherein the weight ratio of the base component to the weight of the chemical set is 0.05% by weight or more.

9. Step a1 involves mixing the components of the set of chemical substances defined in claim 1 to obtain a gel or dispersion, Step b involves heat-treating the gel or dispersion in a temperature range of 50°C to 200°C to obtain a green body, Step c involves heat-treating the green body in a temperature range of 250°C to 350°C to remove the binder and obtain a white body. A process for manufacturing ceramic molded products, comprising step d, which involves sintering by heat treatment in a temperature range of 700°C to 1000°C to obtain a ceramic molded part.

10. The following additional steps, namely A process for manufacturing a ceramic molded article according to claim 9, comprising step a2 of applying a gel or dispersion in layers to a surface by a spray and / or 3D printing process, binder jetting, material jetting, polyjet or multijet modeling.

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