PROCESS FOR THE PRODUCTION OF CORES FOR APPLICATION IN PRESSURE MOLDING, APPLICATION OF A CORE, APPLICATION OF A COMPOSITION AND PROCESS FOR THE APPLICATION OF A CORE IN PRESSURE MOLDING

Abstract

This document describes the application of a finishing composition for the production of cores for pressure molding, a kit for the production of cores for pressure molding, a process for the production of cores for pressure molding, cores for pressure molding, and the application of such cores in pressure molding, particularly of light metals.

Description

1 / 50 “PROCESS FOR THE PRODUCTION OF CORES FOR APPLICATION IN PRESSURE MOLDING, APPLICATION OF A CORE, APPLICATION OF A COMPOSITION AND PROCESS FOR THE APPLICATION OF A CORE IN PRESSURE MOLDING”

[0001] The present invention relates to the application of a finishing composition for the production of cores for pressure molding, to a kit for the production of cores for pressure molding, to a process for the production of cores for pressure molding, to the application of suitable cores in pressure molding, as well as to the application of such cores in pressure molding, particularly in the pressure molding of light metals. Other details of the invention result from the appended patent claims as well as from the following description and embodiments.

[0002] For casting metal parts that must have cavities, recesses, and other features, cores are used in the casting mold to keep the corresponding areas of the mold free of molten metal.

[0003] Pressure molding is understood to be an industrial molding process in which, for the mass production of castings, molten metal is introduced under high pressure (10 MPa to 200 MPa) and with a high mold filling speed (up to 12 m / s) into a permanent mold of two or more parts, where the metal is hardened. Low melting point metals such as aluminum and magnesium and alloys containing aluminum and / or magnesium are particularly suitable for pressure molding.

[0004] In cores used in pressure molding of metal parts within the mold to release the cavities foreseen in the parts by filling the molds with molten material, high requirements are demanded from the point of view of mold stability with respect to mechanical and thermal stresses during the molding process. Petition 870260046826, dated 05 / 18 / 2026, page 8 / 68 2 / 50 as from the point of view of easy removal of the cavities after the molding process.

[0005] Document WO 2011 / 151420 A1 discloses salt-based cores (e.g., sodium chloride), which can be produced by molding and compacting a mixture of core material consisting of at least one salt, at least one binder (e.g., water of glass), and optionally excipients such as additives, wetting agents, and catalysts, wherein the salt, binder, and excipients used are inorganic, these core materials are soluble with water as a solvent, the parts are molded and compacted by nuclear injection or pressing, and the compacted cores are stabilized by infiltration. The cores may be further provided with a finish. The production of salt cores is, however, relatively expensive, and their use is associated with some disadvantages, such as high weight, fragility, as well as low storage stability due to the hygroscopy of water-soluble salts.Extracting the casting by dissolving the salt cores results in a solution, which must be dried to obtain the salt again or discarded.

[0006] US patent 2018 / 0318912 A1 discloses a core for application in aluminum die casting, wherein the core comprises a combination of a synthetic ceramic molding material, an inorganic binder containing sodium silicate, and an additive containing amorphous silicon dioxide particles. The core may have a finishing coating, which should prevent molten aluminum from penetrating the core through the surface during die casting. Suitable refractory materials for the finishing coating are zirconium oxide and aluminum oxide, which should be used in powder form.

[0007] Document WO 2013 / 044904 A1 discloses a finishing composition containing Petition 870260046826, dated 05 / 18 / 2026, page 9 / 68 3 / 50 (A) at least the following clays (A1) 1 to 10 parts by weight of palygorskite, (A2) 1 to 10 parts by weight of hectorite and (A3) 1 to 20 parts by weight of sodium bentonite, based on the relative ratio of components (A1), (A2) and (A3) to each other, and (B) a carrier liquid containing water, which is totally evaporable up to 160°C and 1013 mbar, and (C) refractory materials other than (A).

[0008] Preferably, the total clay content A1, A2 and A3 of the combined finish is 0.1 to 4.0% by weight, relative to the solid content of the finish composition. The refractory materials (C) are preferably quartz, aluminum oxide, zirconium oxide, aluminum silicate, zirconium sands, zircon silicates, olivine, talc, mica, graphite, coke, feldspar, diatomite, kaolin, calcined kaolin, kaolinite, metakaolinite, iron oxide, bauxite and / or mixtures thereof. If the finish composition is used as a concentrate, the proportion of refractory (C) in the finish composition is greater than 70% by weight, preferably greater than 80% by weight, respectively relative to the proportion of refractory in the finish composition.

[0009] Document DE 10 2005 041 863 A1 discloses a molding mass for the production of foundry molds for the molding industry comprising at least one refractory molding material, a binder for hardening the molding mass and a proportion of a borosilicate glass.

[0010] Document DE 10 2014 004 914 A1 discloses a casting mold and a casting mold core for molten metal, in which a first layer of molding sand grains is placed on the surface of the molding sand, wherein the first layer is hardened and consists of water glass and / or phosphate glass.

[0011] Documents WO 2013 / 044904 A1, DE 10 2005 041 863 A1 and DE 10 2014 004 914 A1 do not refer to the technical field of molding under Petition 870260046826, dated 05 / 18 / 2026, page 10 / 68 4 / 50 pressure.

[0012] In the foundry industry there is a constant need for cores suitable for die casting, as well as suitable starting materials and processes for producing cores that are suitable for use in die casting.

[0013] A first aspect of the invention relates to a kit for producing cores for application in pressure molding. The kit according to the invention contains, as separate components, (A) a molding material selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum-silicate sands and mixtures thereof; (B) amorphous silicon dioxide in particles or a mixture of additives containing amorphous silicon dioxide in particles; (C) a solution or dispersion comprising water of glass or a kit containing raw materials for the production of a solution or dispersion containing water of glass; (D) a composition for the production of a coating, wherein that composition comprises (D1) a carrier liquid selected from the group consisting of water and mixtures of water with one or more alcohols (D2) a component from a group consisting of (D2a) one or more acids dissolved in the carrier liquid, wherein the aqueous phase formed by the carrier liquid with the acids dissolved therein has a pH of 5 or less (D2b) one or more organic compounds of formula (I) O xR2 R1 O (I), where R1 and R2 are respectively monovalent groups, which contain respectively 1 Petition 870260046826, dated 05 / 18 / 2026, p. 11 / 68 5 / 50 to 26 independent carbon atoms, wherein the R1 group is linked by a carbon atom contained in the R1 group or by an oxygen atom contained in the R1 group and the R2 group is linked by a carbon atom contained in the R2 group, or else they are linked together in the formation of an annular structure, wherein the annular structure comprises a total of 4 to 7 annular atoms and the R1 and R2 groups comprise a total of 2 to 26 carbon atoms, wherein the R1 group is linked by a carbon atom contained in the R1 group or by an oxygen atom contained in the R1 group and the R2 group is linked by a carbon atom contained in the R2 group; (D3) one or more refractory materials in the form of platelet-shaped particles (D4) one or more refractory materials in the form of granular particles wherein the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60% in relation to the total mass of refractory materials (D3) and refractory materials (D4) in component (D).

[0014] In the kit according to the invention, components (A), (B), (C) and (D) are separated, that is, spatially separated from each other, for example, each component (A), (B), (C) and (D) in a separate container.

[0015] Components (A), (B), and (C) of the kit according to the invention are used to produce a molding material mixture, from which, through molding and thermal hardening, a base body for a male mold is produced. Component (D) of the kit according to the invention is a finishing composition or a concentrate for the production of a finishing composition. The finishing composition is a coating composition and is used to produce a coating (finishing coating) on ​​the base body, which extends at least over the entire surface of the male mold that comes into contact Petition 870260046826, dated 05 / 18 / 2026, page 12 / 68 6 / 50 with a molten metal in the casting process. Preferably, the coating extends over the entire surface of the male part.

[0016] Surprisingly, it was found that when using cores according to the invention in pressure molding, despite the high pressure of the molten metal, penetration of the core surface by the molten metal is largely avoided. This is achieved by the finishing coating of the core according to the invention.

[0017] Component (A) of the kit according to the invention represents the molding material of the molding material mixture to be produced by components (A), (B), and (C) of the kit. Refined molding materials are preferred, particularly with an AFS grain unit number in the range of 50 to 100, and more preferably with an AFS grain unit number in the range of 60 to 80. The AFS grain unit number is determined in this case according to the VDG (“Vereins deutscher GieSereifachleute” - Association of German Foundry Experts) brochure, October 1999, page 34, point 5.2. In this publication, the AFS grain unit number is defined by the formula AFS grain unit number = Σ9' x M3' g 5 where g are the mass proportions of the individual grain classes. M3, the AFS multiplier for the respective grain class (according to table 3 of the VDG leaflet, page 34), e.g., total grain mass.

[0018] The molding materials according to the invention to be used are selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum silicate sands and mixtures thereof. Molding material (A) quartz sand is preferred.

[0019] A particularly preferred molding material is sand Petition 870260046826, dated 05 / 18 / 2026, p. 13 / 68 7 / 50 quartz with an AFS grain unit number in the range of 50 to 100, particularly preferably with an AFS grain unit number in the range of 60 to 80.

[0020] Components (B) and (C) of the kit according to the invention form the binder of the molding material mixture to be produced from components (A), (B) and (C) of the kit.

[0021] The amorphous particulate silica in component (B) is preferably selected from the group consisting of - particulate synthetic amorphous silica, which has at least carbon as a secondary component, in which the proportion of silica is 90% or more, in relation to the total mass of the particulate synthetic amorphous silica and the secondary components, preferably, which can be produced by reduction of quartz in an arc furnace; - particulate synthetic amorphous silica, which, as a secondary component, preferentially contains zirconium oxides, which can be produced by thermal decomposition of ZrSiO4; - particulate synthetic amorphous silica that can be produced by oxidizing metallic silicon using an oxygen-containing gas; - particulate synthetic amorphous silica that can be produced by quenching a silica melt; - pyrogenic silica, preferably produced by pyrolysis of silicon tetrachloride; and mixtures thereof.

[0022] The term “particulate” (“in the form of particles”) indicates a solid powder (including dust) or a granule, which is preferably pourable and therefore also sievable.

[0023] Particulate amorphous silica is preferably produced synthetically. Synthetically produced particulate amorphous silica means, in the context of this text, that amorphous silica - is the target product of a chemical reaction process programmed for the Petition 870260046826, dated 05 / 18 / 2026, page 14 / 68 8 / 50 technical synthesis of particulate amorphous silica or - a byproduct of a chemical reaction process designed for the technical synthesis of a target product that is not particulate amorphous silica.

[0024] An example of a reaction process with the target product particulate amorphous silica is the flame hydrolysis of silicon tetrachloride. The particulate amorphous SiO2 (“silica”) produced by this process is also referred to as “pyrogenic SiO2” (“pyrogenic silica”) or as fumed silica (CAS RN 112945-52-5).

[0025] An example of a reaction process in which particulate amorphous silica is formed as a byproduct is the reduction of quartz with, for example, coke in an arc furnace for the production of silicon or ferrosilicon as the target product. The particulate amorphous SiO2 formed in this case (“silica”) is also referred to as silica powder, silicon dioxide powder or SiO2 fume condensate, “silica fume” or microsilica (CAS RN 69012-64-2).

[0026] Another reaction process, in which particulate amorphous silica is produced synthetically, is the thermal decomposition of ZrSiO4 into ZrO2 and SiO2.

[0027] Particulate amorphous silica can also be obtained by oxidizing metallic silicon using an oxygen-containing gas (for more details, see document DE 10 2012 020 510 A1) as well as by quenching a silica melt.

[0028] In the literature, both amorphous silica formed by flame hydrolysis of silica and amorphous silica resulting from the reduction of quartz with, for example, coke in an arc furnace, as a byproduct, as well as amorphous silica formed by thermal decomposition of ZrSiO4, are frequently referred to as “pyrogenic SiO2” (“pyrogenic silica”) or as fumed silica.

[0029] Particulate amorphous silica of the type produced by quartz reduction Petition 870260046826, dated 05 / 18 / 2026, page 15 / 68 9 / 50 with carbon (e.g., coke) in the arc furnace (in the production of ferrosilicon and silicon) presents, conditioned to production, carbon as a secondary component, in which the proportion of silica is 90% or greater, in relation to the total mass of particulate synthetic amorphous silica and the secondary component.

[0030] Particulate amorphous silica of the type produced by thermal decomposition of ZrSiO4 has, as a condition of production, zirconium oxide, particularly zirconium, as a secondary component.

[0031] Synthetic particulate amorphous silica that can be produced by oxidation of metallic silicon by means of an oxygen-containing gas and synthetic particulate amorphous silica that can be produced by quenching a silica melt refers to very pure SiO2 with very few unavoidable impurities (i.e., related to manufacturing).

[0032] In the context of the present invention, particularly preferably, the particulate amorphous silica to be used comprises those types of particulate amorphous silica that are classified with CAS RN 69012-64-2 or CAS RN 112945-52-5. These can be obtained as specified above. The “CAS RN” means, in this case, the CAS Registry Number, CAS = Chemical Abstracts Service.

[0033] Similarly, SiO2 produced by thermal decomposition of ZrSiO4 into ZrO2 from ZrSiO4 and SiO2 obtained by hydrolysis of silicon tetrachloride are particularly preferred.

[0034] Particulate amorphous silica is preferred, with a particle size distribution having a median (d50 value) in the range of 0.7 to 1.5 μm, determined by laser scattering. This determination of the particle size distribution by means of laser scattering is based on the relationship between the size of a particle, on the one hand, and the angle and intensity of the light scattered by these particles. From the measured angles and intensities of the laser radiation, which can be scattered by the contained particles Petition 870260046826, dated 05 / 18 / 2026, page 16 / 68 In a 10 / 50 sample, information about the dimensions of the particles can be obtained using an algorithm based on Mie scattering theory.

[0035] In some cases, component (B) of the kit according to the invention consists of particulate amorphous silica.

[0036] In other cases, component (B) is a powdered additive mixture containing particulate amorphous silica and other components. These other components include, for example, -particulate inorganic materials (for more details, see below), - alkali metal hydroxides - organic silicon compounds, such as silanes, silicones and siloxanes; - waxes; - paraffins; - metal soap; - carbohydrates, wherein carbohydrates are preferably selected from the group consisting of oligosaccharides, polysaccharides and mixtures thereof, particularly preferably from the group consisting of cellulose, cellulose esters, cellulose ethers, starch and dextrin.

[0037] The inorganic particulate materials mentioned above are likewise additives whose addition to the mixture of molding material with water-glass as a binder is known to those skilled in the art. Inorganic particulate materials selected from the group consisting of are preferred. - Aluminum oxide, preferably in the alpha bauxite phase; mixed aluminum / silicon oxides; - zirconium oxide, preferably zirconium (IV) oxide; - zinc oxide; - barium sulfate; - phosphorus compounds, in which the phosphorus compounds are preferably selected from the group of alkali metal phosphates and Petition 870260046826, dated 05 / 18 / 2026, page 17 / 68 11 / 50 salts M5(PO4)3OH, wherein M is an alkaline earth metal, preferably Ca; - layered silicates; Graphite, carbon black; - glass balls; hollow ceramic spheres; - magnesium oxides.

[0038] In certain cases, component (B) of the kit according to the invention is a mixture of powdered additives containing - particulate amorphous silica, wherein the total concentration of particulate amorphous silica is preferably from 25% to 99.5%, particularly preferably from 40% to 95% relative to the total mass of the powder additive mixture (B) and - one or more boron oxide compounds, preferably selected from the group consisting of borates, boric acids, boric anhydrides, borosilicates, borophosphates and borophosphosilicates, wherein the total concentration of boron oxide compounds is preferably from 0.5% to 8%, particularly preferably 2% to 5% in relation to the total mass of powder additive (B).

[0039] Through the boron oxide compounds in component (B), the resistance of the mold body produced from the mixture of molding material against water and air humidity is improved. High resistance to water is important so that the mold body, during the application of the coating composition (D), is affected as little as possible by the water contained in the carrier liquid (D1). High resistance to air humidity improves the storage stability of the mold body.

[0040] Component (C) of the kit according to the invention is either a solution or dispersion comprising water of glass or a kit containing raw material for the production of a solution or dispersion containing water of Petition 870260046826, dated 05 / 18 / 2026, page 18 / 68 12 / 50 glass.

[0041] By “water of glass” is meant alkali metal silicates, which can be obtained, for example, by the joint fusion of quartz sand with sodium or potassium carbonate at 1400 °C to 1500 °C, or by a hydrothermal process. These alkali metal silicates are typically soluble in water.

[0042] The glass water to be used according to the invention contains cations preferably of one or more alkali metals from the group consisting of lithium, sodium and potassium.

[0043] The SiO2 / M2O molar modulus of water of glass is preferably in the range of 1.6 to 4.0, where M2O designates the total amount of alkali metal oxides M.

[0044] Preferably, component (C) of the kit according to the invention has an alkali metal silicate content (i.e., water of glass) in the range of 20% to 60%, preferably in the range of 25% to 55%, relative to the total mass of component (C).

[0045] In a preferred variant, component (C) of the kit according to the invention contains one or more boron oxide compounds, preferably selected from the group consisting of borates, boric acids and boric anhydrides, particularly preferably sodium tetraborate decahydrate, wherein the total concentration of boron oxide compounds calculated as B2O3 is from 0.4% to 1.0%, particularly preferably from 0.5% to 0.8% relative to the total mass of component (C).

[0046] Through the oxide boron compounds in component (C) the resistance of the mold body produced from the mixture of molding material against water and air humidity is enhanced.

[0047] In another preferred variant, component (C) of the kit according to the invention is a solution or dispersion comprising lithium-containing glass water, wherein the total lithium concentration calculated as Li2O is, Petition 870260046826, dated 05 / 18 / 2026, p. 19 / 68 13 / 50 preferably, 0.4% to 1.0%, particularly preferably 0.4% to 0.7% relative to the total mass of component (C). By “lithium-containing glass water” is meant here alkali metal silicates containing lithium ions and possibly ions of other alkali metals, typically sodium and / or potassium ions. Particularly preferred here is a solution or dispersion comprising lithium-containing glass water with a SiO2 / M2O molar modulus in the range of 1.6 to 3.5, preferably in the range of 1.8 to 3.0, wherein the molar ratio of Li2O in M2O is in the range of 0.05 to 0.60, preferably in the range of 0.1 to 0.4, wherein M2O designates respectively the total amount of lithium oxide, sodium and potassium.

[0048] Through lithium-containing glass water, the resistance of the mold body produced from the mixture of molding material against water and air humidity is enhanced.

[0049] In another preferred variant, component (C) of the kit according to the invention is a kit containing raw material for the production of a solution or dispersion comprising lithium-containing glass water. In this variant, component (C) of the kit according to the invention contains, as a separate component (C1), an aqueous solution or dispersion comprising glass water, wherein, in component (C1), the SiO2 content is in the range of 20% to 34% relative to the total mass of the solution or dispersion, wherein component (C1) preferably has a pH in the range of 10.0 to 13.0, particularly preferably in the range of 11.0 to 12.5, (C2), a first free glass water solution or dispersion comprising lithium ions dissolved in water, wherein, in component (C2) - The concentration of lithium ions is in the range of 0.3 mol / L to 5.3 mol / L. - and the total concentration of lithium, sodium, and potassium ions is in the range of 0.3 mol / L to 28.0 mol / L, Petition 870260046826, dated 05 / 18 / 2026, p. 20 / 68 14 / 50 - wherein component (C2) preferably has a pH in the range of 8.0 to 14.0, particularly preferably in the range of 11.5 to 12.3, as well as optionally (C3), a second glass water-free solution or dispersion comprising alkali metal ions dissolved in water, wherein, in component (C3) - the concentration of lithium ions is lower than in component (C2) and is preferably in the range of 0.1 mol / L to 5.0 mol / L, particularly preferably in the range of 0.1 mol / L to 2.0 mol / L; - and the total concentration of lithium, sodium, and potassium ions is in the range of 0.3 mol / L to 28.0 mol / L - and the total concentration of lithium, sodium and potassium ions in component (C3) deviates by no more than 20% from the total concentration of lithium, sodium and potassium ions in component (C2) wherein component (C3) preferably has a pH in the range of 8.0 to 14.0, particularly preferably in the range of 11.5 to 13.5.

[0050] In this variant of component (C) of the kit according to the invention, components (C1), (C2) and - when present - (C3) are separated, i.e., they are present spatially separated from each other, for example, in separate containers.

[0051] In the glass water of component (C1) the concentration of lithium ions is significantly lower than in the lithium-containing glass water to be produced. Preferably, component (C1) does not contain lithium ions.

[0052] The production of lithium-containing glass water from the raw materials described above is described in patent application WO 2019 / 002452 A1.

[0053] In component (D) of the kit according to the invention, components (D1), (D2a) or (D2b), (D3) and (D4) are present, respectively in relation to the total mass of component (D), in the following concentration: (D1) 20% to 75% Petition 870260046826, dated 05 / 18 / 2026, p. 21 / 68 15 / 50 (D2a) 0.1% to 10% or (D2b) 0.1% to 10% (D3) 10% to 58% (D4) 14% to 64%.

[0054] In composition (D) there is an aqueous phase (aqueous liquid phase) for which it is valid that the ratio of the mass of water to the total mass of the aqueous phase is greater than 50%, preferably greater than 70%, and particularly preferably greater than 90%. This aqueous phase comprises the carrier liquid (D1) as well as components dissolved therein.

[0055] The compositions (D) as described above comprise both ready-to-use finishing compositions and concentrates for the formation of ready-to-use finishing compositions. Ready-to-use finishing compositions have a sufficiently high content of carrier liquid (D1) such that they can be applied directly to form a coating on the base body. In a ready-to-use finishing composition, the mass of the carrier liquid (D1) is 40% to 75%, preferably 60% to 75%, relative to the total mass of the composition. Concentrates for the production of a ready-to-use finishing composition contain a significantly lower amount of carrier liquid (D1) compared to the ready-to-use finishing composition. In a concentrate, the total mass of the carrier liquid (D1) is 40% or less relative to the total mass of the composition.A ready-to-use finishing composition can be obtained by diluting the concentrate with a carrier liquid (D1). To dilute the concentrate, a carrier liquid (D1) that is contained in the concentrate's carrier liquid (D1) is normally used, preferably water.

[0056] The solid content of component (D) is less than 80%, preferably less than 75%, relative to the total mass of component (D). The solid content of component (D) essentially comprises components (D3) and (D4). By solids are meant components of Petition 870260046826, dated 05 / 18 / 2026, p. 22 / 68 16 / 50 component (D) that are present in component (D) in solid form, i.e., they are not dissolved but suspended in the carrier liquid (D1). In a ready-to-use finishing composition, the proportion of components (D3) and (D4) is 25% to 60%, relative to the total mass of the finishing composition. In a concentrate for the production of a ready-to-use finishing composition, the proportion of refractory is greater than 40%, however, less than 80% relative to the total mass of component (D).

[0057] As a carrier liquid (component (D1)), component (D) of the kit according to the invention contains water or a mixture of water and one or more alcohols, for example, ethanol, methanol, isopropanol.

[0058] The carrier liquid (D1) serves only as a vehicle for the application of the suspended and dissolved material onto the base body of the male to be produced and is removed during drying of the base body coated with a composition (D) as defined above (for more details, see the disclosure in the context of the process according to the invention, described below). The carrier liquid is present liquid under normal conditions (20 °C and 1013.25 hPa) and is evaporable under normal pressure (1013.25 hPa) at temperatures in the range of 80 °C to 200 °C.

[0059] As component (D2), component (D) of the kit according to the invention normally contains either (D2a) one or more acids dissolved in the carrier liquid, wherein the aqueous phase formed by the carrier liquid with the acids dissolved therein has a pH of 5 or less or (D2b) one or more organic compounds of formula (I) O xR2R1 O(I), where R1 and R2 are respectively monovalent groups, which contain respectively 1 Petition 870260046826, dated 05 / 18 / 2026, p. 23 / 68 17 / 50 to 26 carbon atoms independent of each other, wherein the R1 group is linked by a carbon atom contained in the R1 group or by an oxygen atom contained in the R1 group and the R2 group is linked by a carbon atom contained in the R2 group, or else they are linked together in the formation of an annular structure, wherein the annular structure comprises a total of 4 to 7 annular atoms and the R1 and R2 groups comprise a total of 2 to 26 carbon atoms, wherein the R1 group is linked by a carbon atom contained in the R1 group or by an oxygen atom contained in the R1 group and the R2 group is linked by a carbon atom contained in the R2 group.

[0060] Compounds of formula (I) in component (2b) are preferred, where R1 and R2 - are respectively monovalent groups, which are linear or branched chains independently of each other and contain from 1 to 16, preferably from 1 to 12, carbon atoms, whose carbon atoms may be respectively substituted one to four times (i.e., once, twice, three times or four times) by oxygen and / or hydroxyl, wherein group R1 is linked by a carbon atom contained in group R1 or by an oxygen atom contained in the group and R2 is linked by a carbon atom contained in group R2, or - then, they are linked together in the formation of an annular structure in which the annular structure comprises, in total, 4 to 7, preferably 5 to 7, annular atoms, selected from oxygen and carbon and in which the R1 and R2 groups together comprise, in total, 2 to 16, preferably 3 to 8, carbon atoms, which are linear or branched chain and may be substituted one to four times (i.e., once, twice, three times, four times), preferably one to two times, by oxygen and / or hydroxyl, in which the R1 group is linked by Petition 870260046826, dated 05 / 18 / 2026, p. 24 / 68 18 / 50 a carbon atom contained in group R1 or by an oxygen atom contained in group R1 and group R2 is linked by a carbon atom contained in group R2.

[0061] It has been demonstrated that components (D2a) or (D2b) cause an increase in the predicted male strength with the finishing coating. It is currently believed that by component (D2a) or by hydrolysis of component (D2b) of component (D) of the kit according to the invention, an acid is provided which, by an acid-base reaction, can harden (cure) again the alkaline silicate structure of the base body bonded with glass water eventually affected by the aqueous carrier liquid (D1) of the coating composition. It is also assumed that the acid-base reaction of the acid of component (D2a) or the acid formed by hydrolysis of component (D2b) with the alkaline silicate structure of the base body enhances the bonding of the finishing coating to the base body.

[0062] When component (D) contains component (D2a) defined above, it is preferred that the acids have a pKa < 5, and particularly preferably a pKa < 4 at 25 °C. Acids selected from the group consisting of are particularly preferred. - Selected organic acids from the group consisting of mono-, di- and tricarboxylic acids, preferably mono-, di- and tricarboxylic acids that are solid at 25 °C and 101.3 kPa, particularly preferably citric acid and oxalic acid, - and selected inorganic acids from the group consisting of hydrochloric acid, nitric acid, phosphoric acid and acid phosphates, particularly preferably from the group consisting of hydrochloric acid, nitric acid and phosphoric acid.

[0063] When component (D) contains component (D2b) defined above, it is preferred that the organic compounds of formula (I) be selected from the group consisting of esters, lactones and Petition 870260046826, dated 05 / 18 / 2026, p. 25 / 68 19 / 50 acid anhydrides. In this case, esters, lactones and water-soluble acid anhydrides are preferred. Compounds of formula (I) from the group consisting of methyl formate, ethyl formate, propylene carbonate, γ-butyrolactone, diacetin, triacetin, dibasic esters, acetic anhydride, methyl carbonate and ε-caprolactone are particularly preferred. Propylene carbonate is particularly preferred.

[0064] Components (D3) and (D4) of component (D) are refractory materials. "Refractory" refers, in accordance with common understanding to those skilled in the art (see DIN 51060:2000-06), to masses, materials, and minerals that can withstand, at least for a short period of time, the temperature stress during casting or solidification of molten iron. "Highly refractory" refers to masses, materials, and minerals that can withstand the heat of a molten steel casting for a short period of time. The temperatures that can occur when melting molten steel are generally higher than the temperatures that can occur when molten iron melts. Refractory masses, materials, and minerals (refractory materials) and highly refractory masses, materials, and minerals are known to those skilled in the art, for example, from DIN 51060:2000-06.Refractory materials are particularly suitable if they have melting points at least 200 °C above the temperature of the molten metal used and / or do not react with the molten metal. The term "refractory" as used here includes highly refractory materials.

[0065] Platelet-shaped particles (D3) in the sense of the present invention are particles with three dimensions perpendicular to each other (length, width, thickness), wherein the length has the largest measurement and the thickness the smallest measurement, wherein length and width do not differ significantly and the thickness / length ratio is 0.2 or Petition 870260046826, dated 05 / 18 / 2026, page 26 / 68 20 / 50 lower. Preferably, the length of the platelet-shaped particles (D3) is in the range of 1 µm to 600 µm, more preferably 5 µm to 500 µm, most preferably 5 µm to 200 µm, particularly preferably 10 µm to 200 µm, particularly 10 µm to 150 µm, 10 µm to 100 µm, or 10 µm to 80 µm. The particle dimensions are determined in accordance with ISO 13322-2. The dimensions of these particles can be determined, for example, in a manner known to those skilled in the art, by means of a camsizer. Such particles are referred to as flakes, sheets, scales, or tablets. The platelet-shaped particles (D3) can be obtained, for example, by delamination (e.g., in a grinding process) of layered silicates or layered graphites.

[0066] Layered silicates are those clay minerals that belong to the layered silicate group, such as mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illite, and bentonite. Suitable graphites are natural macrocrystalline graphite and synthetic macrocrystalline graphite. Natural macrocrystalline graphites, as well as synthetic macrocrystalline graphites, are present in the form of crystallites (flakes, chips, scales, or panels) that can be seen with the naked eye, whose extent is in the c-plane in the range of 100 pm to a few millimeters.

[0067] Synthetic graphite can be obtained by the Acheson process, or by compression molding and burning (800-1300 °C) of petroleum coke with the addition of a binder (coal tar pitch) and subsequent electrographitization. The synthetic graphite is present in the form of crystallites, whose extension in the c-plane is between some 100 Å (some 10 nm) and a few millimeters. As a refractory (D3) in the sense of the present invention, macrocrystalline synthetic graphite in the form of crystallites with an expansion in the c-plane of 100 pm a few millimeters can be used, while microcrystalline synthetic graphite can be used as a refractory (D4) in the sense of the present invention (see below). Petition 870260046826, dated 05 / 18 / 2026, page 27 / 68 21 / 50

[0068] Natural graphite occurs in both macrocrystalline, foliaceous, and microcrystalline, terrestrial forms. The macrocrystalline, flaky form of natural graphite can be used as a refractory (D3) in the sense of the present invention, while the microcrystalline, terrestrial form can be used as a refractory (D4) in the sense of the present invention (see below).

[0069] Refractory materials (D3) in the form of platelet-shaped particles are preferably selected from the group consisting of macrocrystalline graphites, hexagonal boron nitride and layered silicates. Preferred layered silicates are powdered clays (of clay minerals belonging to the layered silicate group), mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illitase bentonite. Pyrophyllite and powdered clays are particularly preferred.

[0070] Granular particles (D4), within the meaning of the present invention, are particles with three dimensions extending perpendicularly to each other (length, width, thickness), wherein thickness and width do not differ significantly, and the thickness / length ratio is in the range of 0.8 to 1. Granular particles (D4) within the meaning of the present invention also thereby comprise spherical particles (for further details, see below). Preferably, the length of the granular particles (D4) is in the range of 10 nm to 250 pm, preferably from 50 nm to 200 pm, particularly preferably from 50 nm to 100 pm, particularly from 100 nm to 50 pm or from 100 nm to 20 pm. The particle dimensions are determined in accordance with ISO 13322-2. The dimensions of these particles can be determined, for example, in a manner known to those skilled in the art, by means of a Camsizer.

[0071] Granular particles with well-defined edges are also referred to in practice as fragmented particles; these count as granular particles within the meaning of the present invention. Granular particles, particularly fragmented particles (D4), can be obtained, for example, by breaking (e.g., in a grinding process) glasses, Petition 870260046826, dated 05 / 18 / 2026, page 28 / 68 22 / 50 monocrystalline sands or polycrystalline sands or rocks.

[0072] Refractory materials (D4) in granular particle form are preferably selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxide, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, preferably Ca, silicon nitride and rutile. Zirconium silicate and microcrystalline graphite are particularly preferred.

[0073] Carbon black is a form of carbon that forms during the incomplete combustion or thermal decomposition of vaporous carbonaceous substances. Coke can be obtained by heating coal, lignite, or peat in the absence of air at temperatures of approximately 800 °C.

[0074] Suitable microcrystalline graphites are natural microcrystalline graphites (natural earthy graphites) and synthetic microcrystalline graphites. Natural microcrystalline graphite and synthetic microcrystalline graphite are a form of crystallites whose extent in the c-plane is less than 100 pm; the individual crystallites can therefore only be seen under a microscope.

[0075] In component (D) of the kit according to the invention, the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range of 85% to 20%, preferably 70% to 40%, respectively in relation to the total mass of refractory materials (D3) and refractory materials (D4). This is also valid for ready-to-use finishing compositions produced by diluting component (D) of the kit according to the invention.

[0076] It is possible to distinguish between platelet-shaped particles (D3), on the one hand, and granular particles (D4), on the other, for example, based on two-dimensional microscopic images of the particles. Petition 870260046826, dated 05 / 18 / 2026, page 29 / 68 23 / 50 corresponding. Other possibilities for distinguishing between platelet-shaped particles (D3), on the one hand, and granular particles (D4), on the other, are sedimentation and granulometry methods. These suitable methods are known to the expert in the field.

[0077] In a preferred variant, component (D4) of component (D) of the kit according to the invention further comprises (D4a) amorphous particulate silica.

[0078] Surprisingly, component (D4a) has been shown to contribute to increasing the strength of the intended core with the finishing coating and improves the bonding of the finishing coating to the base body, which also contains particulate amorphous silica (from component (B)). Preferably, the proportion of particulate amorphous silica (D4a) is 3% to 30% relative to the total mass of the refractory materials (D4).

[0079] From the point of view of the characteristics of amorphous particulate silica and the selection of suitable types of amorphous particulate silica, the above embodiments apply correspondingly to component (B) of the kit according to the invention. Preferably, the same type of amorphous particulate silica is used in component (B) of the kit according to the invention, as well as in component (D4) of component (D) of the kit according to the invention.

[0080] The primary particles of amorphous silicon dioxide are agglomerated according to the production process mentioned above, i.e., as agglomerates of primary particles. The particle shape of the particulate amorphous silicon dioxide primary particle (D4a) is preferably nearly spherical, wherein the sphericity is 0.9 or greater. Sphericity in the context of the present invention is defined as the circumference of the circle of equal area (Equivalent Projection Area of ​​a Circle, abbreviated: EQPC) of a particle divided by the actual circumference of the particle. The determination of particle size, necessary for the Petition 870260046826, dated 05 / 18 / 2026, page 30 / 68 24 / 50 to determine sphericity is performed for particles with a particle size smaller than 5 μm, preferably according to the standard verification method according to ISO 13322-1:2014, as well as for particles with a particle size larger than 5 μm, preferably according to the standard verification method according to ISO 13322-02:2006. Modern commercially available electron microscopy or light microscopy systems allow for digital image analysis and therefore a convenient determination of particle shape. Digital image analysis is preferred for sphericity studies. Digital image analysis is preferably performed using commercial image analysis software, such as Media Cybernetics' ImagePro Plus software. When preparing samples for digital image analysis, ensure that the particles are randomly oriented. If necessary, thin sections should be prepared.

[0081] Refractory materials in the form of platelet-shaped particles are preferred (D3) from the group consisting of macrocrystalline graphites, hexagonal boron nitride, and layered silicates, wherein layered silicates are preferably selected from the group consisting of powdered clays (of clay minerals, which belong to the layered silicate group), mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illites and bentonites, as well as refractory materials in the form of grains or fragmented particles are preferably selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, preferablyCa, silicon nitride, and rutile. Petition 870260046826, dated 05 / 18 / 2026, page 31 / 68 25 / 50

[0082] In a particularly preferred variant, component (D3) is formed from layered silicates, for example pyrophyllite and / or clay powder, and component (D4) is formed from microcrystalline graphite and zirconium silicate (in a mass ratio of 2:3 to 3:2). In this case, the proportion of refractory materials (D3) is preferably 40% to 60%, relative to the total mass of refractory materials (D3) and refractory materials (D4). Preferably, component (D4) additionally contains (D4a) amorphous particulate silica.

[0083] By combining, according to the invention, components (D3) and (D4) in particle form in component (D), it is achieved that the finishing composition (D) or a finishing composition produced by dilution of component (D) combines the effects of a coating finish (covering coating) and a penetrating finish. Covering coatings typically contain refractory materials predominantly in platelet form, penetrating finishes typically contain refractory materials predominantly in granular form. When applied to a base body formed as described above, from a mixture of molding material, the particle-form refractory materials contained in the covering coatings form a covering layer on the molding material of the base body, which, during casting, comes into direct contact with the molten material, i.e., the surface of the base body is sealed.In other words, when applying a coating over a base body formed as described above, from a mixture of molding material, the refractory materials in particle form contained in the coatings form a covering layer on the base body molding material, which, during casting, comes into direct contact with the molten material; that is, the surface of the base body is sealed. Coatings penetrate less than approximately 2 mm into the molding material. Penetrating finishes, on the other hand, penetrate further. Petition 870260046826, dated 05 / 18 / 2026, page 32 / 68 26 / 50 deeper into the molding material such that the particle-form refractory materials contained in such a finish fill the pores in the molding material. By applying a finish composition containing the combination, according to the invention, of the particle-form components (D3) and (D4), it is achieved that both the pores are filled in the molding material and a covering layer is formed over the molding material, which comes into direct contact with the molten material (for this, see also the embodiments below in the context of cores according to the invention).

[0084] Component (D) of the kit according to the invention may comprise other components, which are normally contained in compositions (D) for the production of finishing coatings, particularly components selected from the group consisting of wetting agents, rheological additives, binders, suspending agents and biocides. Suitable wetting agents, rheological additives, binders, suspending agents and biocides and their function and effect are known to those skilled in the art. Provided that one of these components (e.g., rheological additives) is a refractory in the form of platelet-shaped particles (D3) as defined above or a refractory in the form of granular particles (D4) as defined above, it is assigned to component (D3) or (D4) as defined above.

[0085] In an alternative variant, a kit according to the invention contains, as separate components (A) a molding material selected from the group consisting of quartz sand, chrome ore sand, olivine sand, natural aluminum-silicate sands and mixtures thereof (B) amorphous silicon dioxide particles or a mixture of additives containing amorphous silicon dioxide particles (C) a solution or dispersion comprising glass water or a kit containing raw material for the production of a solution or dispersion that Petition 870260046826, dated 05 / 18 / 2026, page 33 / 68 27 / 50 contains water of glass (D) a composition for the production of a coating, wherein that composition comprises (D1) a carrier liquid selected from the group consisting of water and mixtures of water with one or more alcohols (D2) a component of a group consisting of (D2a) one or more acids dissolved in the carrier liquid, wherein the aqueous phase formed by the carrier liquid with the acids dissolved therein has a pH of 5 or less (D2b) one or more organic compounds of formula (I) The xR2 R1 O (I), wherein R1 and R2 are respectively monovalent groups, containing respectively 1 to 26 carbon atoms independent of each other, wherein group R1 is linked by a carbon atom contained in group R1 or by an oxygen atom contained in group R1 and group R2 is linked by a carbon atom contained in group R2, or else they are linked to each other in the formation of an annular structure, wherein the annular structure comprises a total of 4 to 7 annular atoms and groups R1 and R2 comprise a total of 2 to 26 carbon atoms, wherein group R1 is linked by a carbon atom contained in group R1 or by an oxygen atom contained in group R1 and group R2 is linked by a carbon atom contained in group R2; (D3) one or more refractory materials from the group consisting of macrocrystalline graphite, hexagonal boron nitride, and layered silicates; (D4) one or more refractory materials from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, Petition 870260046826, dated 05 / 18 / 2026, page 34 / 68 28 / 50 andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxide, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, preferably Ca, silicon nitride and rutile; wherein the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60% in relation to the total mass of refractory materials (D3) and refractory materials (D4) in component (D).

[0086] The above embodiments apply mutatis mutandis to components (A) to (C), as well as to components (D1), (D2a) and (D2b) of component (D), as well as to other optional components of component (D) selected from the group consisting of wetting agents, rheological additives, binders, suspending agents and biocides.

[0087] In component (D) of the kit according to the invention, the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range of 85% to 20%, preferably 70% to 40%, respectively in relation to the total mass of refractory materials (D3) and refractory materials (D4). This is also valid for ready-to-use finishing compositions produced by diluting component (D) of the kit according to the invention.

[0088] Suitable layered silicates (D3) are clay minerals belonging to the layered silicate group, such as mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illite and bentonite. Pyrophyllite and clay powder (from clay minerals belonging to the layered silicate group) are particularly preferred as component (D3). Microcrystalline graphite and zirconium silicate are particularly preferred as component (D4).

[0089] In a preferred variant, component (D4) of component (D) of the alternative variant described above of the kit according to the invention further comprises Petition 870260046826, dated 05 / 18 / 2026, p. 35 / 68 29 / 50 (D4a) amorphous particulate silica.

[0090] Preferably, the proportion of amorphous particulate silica (D4a) is 3% to 30%, relative to the total mass of the refractory materials (D4).

[0091] From the point of view of the characteristics of amorphous particulate silica and the selection of suitable types of amorphous particulate silica, the above embodiments apply correspondingly to component (B) of the kit according to the invention. Preferably, the same type of amorphous particulate silica is used in component (B) of the alternative variant of the kit according to the invention and in component (D4) of component (D) of the alternative variant of the kit according to the invention.

[0092] In a preferred variant, component (D3) is formed by layered silicates, for example pyrophyllite and / or clay powder, and component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2:3 to 3:2). In this case, the proportion of refractory materials (D3) is preferably 40% to 60%, relative to the total mass of refractory materials (D3) and refractory materials (D4). Preferably, component (D4) additionally contains (D4a) amorphous particulate silica.

[0093] Component (D) of the alternative variant of the kit according to the invention may comprise other components, which are normally contained in compositions for the production of finishing coatings, particularly components selected from the group consisting of wetting agents, rheological additives, binders, suspending agents and biocides. Suitable wetting agents, rheological additives, binders, suspending agents and biocides and their function and effect are known to those skilled in the art. Provided that one of these components (e.g., rheological additives) is a refractory in the form of platelet-shaped particles (D3) as defined above or a refractory in the form of granular particles (D4) as defined above, it is assigned to component (D3) or (D4) as defined above.

[0094] A second aspect of the present invention relates to a process Petition 870260046826, dated 05 / 18 / 2026, page 36 / 68 30 / 50 for the production of cores for application in pressure molding, comprising the steps (a) producing a molding material mixture by mixing components (A), (B) and (C), (b) molding the molding material mixture, (c) thermally hardening the formed molding material mixture, in which a base body of the core to be produced is formed, (d) applying - a composition (D) - or a coating composition formed by diluting a composition (D) with carrier liquid (D1) on the base body and subsequent drying, such that a coating is produced on the base body, in which a core is formed comprising the base body and a coating disposed over the base body, which extends over at least the entire surface of the core that, in the molding process, comes into contact with molten metal.

[0095] In step (a) of the process according to the invention, components (B) and (C), which are spatially separated, of the kit according to the invention, are mixed simultaneously or successively in the molding material (component (A) of the kit according to the invention).

[0096] In certain cases it is preferred that component (B) of the kit according to the invention be initially mixed into the molding material (component (A) of the kit according to the invention), such that a premix comprising components (A) and (B) of the kit according to the invention is formed, and that component (C) of the kit according to the invention (i.e., an aqueous solution or dispersion containing water of glass or raw material for the production of a solution or dispersion comprising water of glass as described above) be mixed into the thus obtained premix, such that the mixture of Petition 870260046826, dated 05 / 18 / 2026, page 37 / 68 31 / 50 molding material.

[0097] In other cases, it is preferred that component (C) of the kit according to the invention (i.e., an aqueous solution or dispersion containing water of glass or raw material for the production of a solution or dispersion comprising water of glass) be initially mixed into the molding material (component (A) of the kit according to the invention), such that a premix comprising components (A) and (C) of the kit according to the invention is formed, and component (B) of the kit according to the invention is mixed into the thus obtained premix, such that the molding material mixture is obtained.

[0098] The molding material (component (A) of the kit according to the invention, as defined above) preferably constitutes more than 80% by weight, more preferably more than 90% by weight, and more particularly preferably more than 95% by weight of the total mass of a molding material mixture produced in step (a).

[0099] In a molding material mixture produced in step (a) of the process according to the invention, the concentration of particulate amorphous silicon dioxide of component (B) of the kit according to the invention is preferably from 0.05% to 3.0%, more preferably from 0.1% to 2.0%, particularly preferably from 0.3% to 1.5% relative to the total mass of the molding material.

[0100] In step (a) of the process according to the invention, component (C) of the kit according to the invention is added, preferably in an amount of 0.2% to 3%, particularly preferably 0.3% to 2% relative to the total mass of the molding material.

[0101] A molding material mixture produced in step (a) of the process according to the invention is preferably present in molten form, such that it can be easily filled into a mold and compacted there. Compacting the molding material mixture in a molding tool serves to increase the Petition 870260046826, dated 05 / 18 / 2026, page 38 / 68 32 / 50 resistance of casting molds or casting cores produced from the mixture of molding material.

[0102] The molding of the molding material mixture in step (b) of the process according to the invention normally takes place in a molding tool. The molding material mixture is preferably introduced into the molding tool by means of compressed air.

[0103] The thermal hardening in step (c) of the process according to the invention preferably takes place at temperatures in the range of 100 °C to 300 °C, particularly preferably from 100 °C to 250 °C.

[0104] The thermal hardening of the binder system occurs through a chemical reaction of the binder system components with each other, resulting in a mold body (the base body of the core to be produced). The main reason for the thermal hardening of the binder system is the condensation of water glass, that is, the bonding of the silicate units of water glass with each other (the reaction mechanism has been described as understood in the technical literature). For this, water is removed from the binder system by heat treatment.

[0105] Heating of the molded molding material mixture for thermal hardening of the binder system can occur, for example, in a molding tool that has temperatures above 100 °C, preferably temperatures from 100 °C to 300 °C, particularly preferably temperatures from 120 °C to 250 °C. Preferably, the thermal hardening of the binder system in the molded molding material mixture occurs completely or at least partially in a common molding tool for the industrial production of mold bodies.

[0106] In this case, the thermal hardening of the binder system in the molded mixture of molding material can occur in suitable facilities and / or through the use of equipment (such as piping, pumps, etc.) in which the thermal hardening is supported by Petition 870260046826, dated 05 / 18 / 2026, page 39 / 68 33 / 50 Targeted gasification of the molded mixture of molding material with tempered air. For this purpose, the air is tempered, preferably from 100 °C to 250 °C, particularly preferably from 110 °C to 180 °C. The air contains carbon dioxide; however, this does not correspond, in the sense of the present invention, to hardening according to the CO2 process known from the prior art for glass water hardening, which requires targeted gasification of the molded mixture of molding material with a CO2-rich gas, particularly in suitable facilities and / or under the use of suitable equipment (such as piping, pumps, etc.). Gasification of the molded mixture of molding material with a gas containing CO2 at a high concentration relative to its concentration in air does not occur in the context of the thermal hardening provided for according to the invention or in combination therewith.

[0107] The interval for thermal hardening, therefore, also the interval for heating and for targeted gasification of the molded mixture of molding material with tempered air, can be varied according to the needs of each case and depend, for example, on the size and geometric texture of the molded mixture of molding material. The flow rate and / or volume flow of tempered air in the targeted gasification of the molded mixture of molding material are then preferably adjusted in such a way that, within a preferably very short interval acceptable for industrial application, sufficient hardening of the molded mixture of molding material is achieved for other machining or applications (for more details, see below). An interval of less than 5 minutes is preferred in the context of the present invention, and particularly preferably less than 2 minutes.However, for very large mold bodies, longer intervals may be necessary depending on the needs of each case.

[0108] The molded mixture of molding material can be widely Petition 870260046826, dated 05 / 18 / 2026, page 40 / 68 34 / 50 already hardened in the molding tool.

[0109] The process according to the invention does not, however, assume that complete hardening of the binder system occurs during the heat treatment. “Thermal hardening” in the sense of the process according to the invention, as described above, therefore also includes incomplete hardening of the binder. This corresponds to the technical understanding of the term “hardening,” since, for reasons of reaction kinetics, the binder system is not expected to react in the entire volume of the molded mixture of molding material during the relatively short interval of the heat treatment. In this respect, those skilled in the art are familiar, for example, with the post-curing phenomenon (e.g., thermal hardening) of the binder system in a mold body, for example, of a casting mold or a casting core.

[0110] According to the invention, it is possible to harden the binder system in the molding tool initially only in an edge area of ​​the molded mixture of molding material, such that sufficient strength (green strength) is achieved to be able to remove the molding mixture from the molding tool. Then, the molded mixture of molding material can be further hardened by removing more water (e.g., in an oven or by evaporating the water at reduced pressure or in a microwave oven).

[0111] Thermal hardening can also be supported or induced by the effect of microwaves or by the effect of electromagnetic radiation, particularly infrared radiation, on the molded mixture of molding material.

[0112] Thermal hardening can be supported or induced, in the same way, by conducting electric current through the molded mixture of molding material, preferably uniform and of a certain shape. Petition 870260046826, dated 05 / 18 / 2026, page 41 / 68 35 / 50 particularly preferred, also uniform current conduction or by a preferably uniform and particularly preferably uniform application of an electromagnetic field through or into the molded mixture of molding material. By means of this, the molding material mixture is heated, preferably uniformly heated, and thereby hardened particularly uniformly with a high-quality result. Particularities are disclosed in document DE 10 2017 217098 B3 and in the literature cited therein.

[0113] In step (d) of the process according to the invention, a composition (D) or a coating composition formed by diluting a composition (D) with carrier liquid (D1) is applied to the surface of the base body. When component (D) of the kit according to the invention is not present as a ready-to-use finish, but as a concentrate (proportion of carrier liquid (D1) 40% or less in relation to the total mass of composition (D)), a coating composition (ready-to-use finish) is initially produced by diluting this concentrate with carrier liquid (D1), with a proportion of carrier liquid (D1) of 40% to 75% in relation to the total mass of the coating composition, or a coating composition with a proportion of components (D3) and (D4) of 25% to 60% in relation to the total mass of the coating composition, and the coating composition thus formed is applied to the surface of the base body.To dilute the concentrate, a carrier liquid (D1) is normally used, which is contained within the carrier liquid (D1) of the concentrate, usually water.

[0114] In the lining composition applied in step (d), the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range of 85% to 20%, preferably in the range of 70% to 40%, respectively in relation to the total mass of refractory materials (D3) and refractory materials (D4). Petition 870260046826, dated 05 / 18 / 2026, p. 42 / 68 36 / 50

[0115] In the application of composition (D) or of the coating composition formed therefrom, the base body preferably has a temperature below 80 °C, preferably in the range of 15 °C to 35 °C. When the base body, after thermal hardening (step (c)), is cooled to a temperature below 80 °C, preferably in the range of 15 °C to 35 °C, the binder has achieved sufficient strength in the base body such that the water-bonded base body is sufficiently water-resistant when it comes into contact with the aqueous coating composition.

[0116] The application of composition (D) or of the coating composition formed from it onto the surface of the base body may occur using any suitable technique. Preferably, the composition is applied to the surface of the base body in such a way as to result in a core with a coating formed from composition (D) or of the coating composition produced from it, which extends over at least the entire surface of the core that, in the casting process, comes into contact with molten metal. Preferably, the coating extends over the entire surface of the core. Preferably, composition (D) or of the coating composition formed from it is applied to the surface of the base body by a process selected from the group consisting of spraying, dipping, flooding and brushing, particularly preferably dipping.

[0117] The composition (D) or the coating composition formed from it is preferably applied in such a way as to result in a wet film thickness in the range of 25 µm to 600 µm, preferably from 150 µm to 350 µm.

[0118] After applying the composition (D) or the coating composition formed from it onto the surface of the base body, the carrier liquid (D1) is removed by drying and then a coating is formed on the base body. Thus a male is formed comprising Petition 870260046826, dated 05 / 18 / 2026, page 43 / 68 37 / 50 the base body and a coating disposed over the base body that extends at least over the entire surface of the core, which, in the casting process, comes into contact with the molten metal. Preferably, the coating extends over the entire surface of the core. The drying of the composition (D) applied to the surface of the base body or the coating composition produced by dilution of composition (D) preferably occurs at temperatures in the range of 80°C to 220°C, more preferably at temperatures in the range of 100°C to 140°C, and particularly preferably at temperatures in the range of 105°C to 120°C.

[0119] A third aspect of the present invention relates to a male for application in pressure molding. The core according to the invention comprises (i) a base body comprising (A) a molding material selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum silicate sands and mixtures thereof and (B) particulate amorphous silica bound together by glass water and (ii) a coating disposed on the base body extending at least over the entire surface of the core, which, in the casting process, comes into contact with a molten metal, wherein the coating comprises: (D3) one or more refractory materials in the form of platelet-shaped particles (D4) one or more refractory materials in the form of granular particles wherein the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60% in relation to the total mass of refractory materials (D3) and refractory materials (D4).

[0120] For components (A) and (B) of the base body (i), as well as for Petition 870260046826, dated 05 / 18 / 2026, page 44 / 68 38 / 50 the components (D3) and (D4) of the male coating (ii) according to the invention are equivalent to the above embodiments relating to the corresponding components and components of the kit according to the invention, mutatis mutandis.

[0121] In the coating (ii) of the male according to the invention, the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range of 85% to 20%, preferably in the range of 70% to 40%, respectively in relation to the total mass of refractory materials (D3) and refractory materials (D4).

[0122] Refractory materials (D3) are preferably selected from the group consisting of macrocrystalline graphites (as defined above), hexagonal boron nitride and layered silicates. Layered silicates (D3) are clay minerals belonging to the layered silicate group, such as mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illite and bentonite.

[0123] Pyrophyllite and powdered clay (from clay minerals belonging to the layered silicate group) are particularly preferred as component (D3). Microcrystalline graphite and zirconium silicate are particularly preferred as component (D4).

[0124] Refractory materials (D4) in granular particle form are preferably selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxide, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, preferably Ca, silicon nitride and rutile. Zirconium silicate and microcrystalline graphite are particularly preferred.

[0125] In a preferred variant, the component (D4) of the component (D) of the male coatings according to the invention described above Petition 870260046826, dated 05 / 18 / 2026, page 45 / 68 39 / 50 also includes (D4a) amorphous particulate silica.

[0126] Preferably, the proportion of amorphous particulate silica (D4a) is 3% to 30%, relative to the total mass of the refractory materials (D4).

[0127] In a preferred variant, component (D3) is formed by layered silicates, for example pyrophyllite and / or clay powder, and component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2:3 to 3:2). In this case, the proportion of refractory materials (D3) is 40% to 60%, relative to the total mass of refractory materials (D3) and refractory materials (D4). Preferably, component (D4) additionally contains (D4a) amorphous particulate silica.

[0128] Through the coating (ii), intermediate spaces between the particles of the molding material on the surface of the base body (i) of the core according to the invention are filled, and on the base body (i) a covering layer is formed which, in the casting process, comes into contact with a molten metal. Surprisingly, it was found that, during the drying of the coating composition, the platelet-shaped particles of component (D3) with their largest dimension align parallel to the surface of the core, and thereby also cause a corresponding alignment of the granular particles of component (D4). In the absence of platelet-shaped particles (not in accordance with the invention), it is observed, in turn, that granular particles are regularly deposited in a completely random manner, i.e., without a specific orientation, on the surface of the core, i.e., the base body.It is believed that by aligning the platelet-shaped particles of component (D3) and the granular particles of component (D4) parallel to the core surface, the molten metal core surface offers very low flow resistance.

[0129] Without being bound to any particular theory, it is currently believed that in, a male according to the invention, on the surface of Petition 870260046826, dated 05 / 18 / 2026, pp. 46 / 68 40 / 50 base body (i), intermediate spaces between the molding material particles are filled by granular particles of coating component (D4) (ii) at least partially, while platelet-shaped particles of coating component (D3) (ii) cover and close the cavities. The coating (ii) of a male according to the invention is therefore almost free of macroscopic pores and cavities. By macroscopic pores is meant pores clearly visible to the naked eye with a size of 0.05 mm or larger.

[0130] Because the granular particles fill the spaces between the molding material particles on the surface of the base body, a relatively flat and smooth surface is produced, on which, again, the platelet-shaped particles can orient themselves.

[0131] Thus, through the interaction of components (D3) and (D4), a male part according to the invention is obtained, in pressure molding, exhibiting high penetration resistance against the molten metal.

[0132] Unlike salt-based plugs described in WO 2011 / 151420 A1, a plug according to the invention contains water-soluble salts as solvents (as described in WO 2011 / 151420 A1) at a concentration of less than 8%, preferably less than 5%, particularly preferably less than 3%, less than 2%, less than 1%, relative to the total mass of the plug. Particularly preferably, the plug according to the invention does not contain any water-soluble salts as solvents (as described in WO 2011 / 151420 A1).

[0133] A male according to the invention can be produced by the process according to the invention as described above.

[0134] In an alternative variant, a male according to the invention comprises (i) a base body comprising (A) a molding material selected from the group consisting Petition 870260046826, dated 05 / 18 / 2026, pp. 47 / 68 41 / 50 in quartz sand, chrome ore sand, olivine sand, aluminum-silicate sands and mixtures thereof and (B) particulate amorphous silica bound by water of glass and (ii) a coating disposed on the base body that forms a surface of the core, which, in the casting process, comes into contact with molten metal, wherein the coating comprises: (D3) one or more refractory materials from the group consisting of macrocrystalline graphite, hexagonal boron nitride, and layered silicates; (D4) one or more refractory materials from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, preferably Ca, silicon nitride and rutile; wherein the proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30 to 60% in relation to the total mass of refractory materials (D3) and refractory materials (D4).

[0135] Refractory materials (D3) are preferably selected from the group consisting of macrocrystalline graphite (as defined above), hexagonal boron nitride and layered silicates. Layered silicates (D3) are clay minerals belonging to the layered silicate group, mica, talc, kaolin, metakaolin, calcined kaolin, pyrophyllite, illite and bentonite.

[0136] The proportion of refractory materials (D3) is in the range of 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range of 85% to 20%, preferably in the range of 70% to 40%, respectively in relation to the total mass of refractory materials (D3) and refractory materials (D4). Petition 870260046826, dated 05 / 18 / 2026, pages 48 / 68 42 / 50

[0137] For components (A) of the (B) base body (i) of the male according to the invention, the above embodiments relating to the corresponding components and components of the kit according to the invention apply, mutatis mutandis.

[0138] In a preferred variant, component (D4) of component (D) of the coating of the cover of the alternative variant described above of the male according to the invention further comprises (D4a) amorphous particulate silica.

[0139] Preferably, the proportion of amorphous particulate silica (D4a) is 3% to 30%, relative to the total mass of the refractory materials (D4).

[0140] In a preferred variant, component (D3) is formed by layered silicates, for example pyrophyllite and / or clay powder, and component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2:3 to 3:2). In this case, the proportion of refractory materials (D3) is preferably 40% to 60%, relative to the total mass of refractory materials (D3) and refractory materials (D4). Preferably, component (D4) additionally contains (D4a) amorphous particulate silica.

[0141] A male according to the invention can be produced by the process according to the invention as described above.

[0142] Another aspect of the invention relates to the application of a male part according to the invention, corresponding to the third aspect of the invention described above, or to a male part produced according to a process, according to the invention, corresponding to the second aspect of the invention described above, in pressure molding.

[0143] A process for applying a core in pressure molding, particularly in pressure molding of light metals, comprises the steps - to produce a male part according to a process according to the invention corresponding to the second aspect of the invention described above or to supply a male part according to the invention corresponding to Petition 870260046826, dated 05 / 18 / 2026, pp. 49 / 68 43 / 50 third aspect of the invention described above or of a male produced according to a process according to the invention corresponding to the second aspect of the invention described above, - insert the male part into a casting mold, - To produce a casting by melting a molten metal under pressure of up to 200 MPa, preferably 10 MPa to 200 MPa, in the casting mold and solidifying the molten metal. - Remove the male part from the casting.

[0144] Surprisingly, it was found that when using cores according to the invention in die casting, despite the high pressure of the molten metal, penetration of the core surface by the molten metal is largely avoided. This is achieved by the finishing coating of the core according to the invention. Furthermore, the cores proved to be stable under the rapidly increasing pressure load during die casting.

[0145] The cores according to the invention, corresponding to the third aspect described above of the invention, or cores produced according to a process according to the invention, corresponding to the second aspect of the invention, are particularly suitable for application in pressure molding of light metals, particularly of the group consisting of aluminum and aluminum alloys. After cooling and solidification of the casting, for example, by abrupt cooling of the casting by immersion in water, the core can be removed from the casting by means of common techniques, for example, by slowly releasing the binder in water, or by hydrostatic pressure (for example, by means of water jets), or by means of vibration, acoustic debolization, or pulse current debolization.

[0146] In the male application according to the invention corresponding to the third aspect of the invention described above or males produced according to a process according to the invention corresponding to Petition 870260046826, dated 05 / 18 / 2026, pp. 50 / 68 44 / 50 According to the second aspect of the invention described above, pressure molding is preferably carried out with the following machine parameters. - piston speed in the range of 1.00 m / s to 10.00 m / s, preferably 1.00 m / s to 5.00 m / s, particularly preferably 2.00 m / s to 2.10 m / s; - cutting speed in the range of 5.0 m / s to 50.0 m / s, preferably 5.0 m / s to 40.0 m / s, more preferably 10 m / s to 20 m / s, particularly preferably 13 m / s to 19 m / s; - Outlet pressure in the range of 15 MPa to 100 MPa, preferably 35 MPa to 80 MPa, particularly preferably 60 MPa to 70 MPa.

[0147] Another aspect of the invention relates to the application of a composition (D) as described above in the context of the first aspect of the invention. - for the production of a male according to the invention corresponding to the third aspect of the invention, described above or - in a process according to the invention corresponding to the second aspect of the invention described above.

[0148] From the point of view of preferred composition characteristics (D), of the process according to the invention and of the male according to the invention, the above embodiments apply.

[0149] The invention is explained in more detail below based on embodiments and comparison examples. Examples of modality 1. Production of males

[0150] Components (A)-(D) of a kit according to the invention have been made available for the production of cores for application in pressure molding. The composition of components (A)-(D) is described below. For the production of comparison cores, the same components (A)-(C) as a coating composition have been made available. Petition 870260046826, dated 05 / 18 / 2026, pp. 51 / 68 45 / 50 not in accordance with the invention, the composition of which is specified below. Step (a): Produce a mixture of molding material

[0151] A molding material mixture was produced by mixing (A) H32 quartz sand as molding material with (B) particulate amorphous silica (0.3% to 1.5%, relative to the total mass of molding material (A)) and (C) a solution of water of glass (alkali metal silicate) containing lithium, sodium and potassium ions (0.3% to 3% solution (C), relative to the total mass of the molding material) Steps (b) and (c): Produce the base body for males

[0152] From this mixture of molding material were formed, by, through the usual manner, by (b) molding the mixture of molding material by means of a core-launching machine and (c) thermal hardening of the molded mixture of molding material in the core box heated to a temperature in the range of 100°C to 250°C supported by gasification with tempered air at a temperature in the range of 100°C to 250°C the base body for cores to be produced. Step d): Application of the coating composition

[0153] A coating composition was applied to the base body cooled to a temperature below 80 °C, preferably 15 °C to 35 °C.

[0154] For the production of the male part according to the invention, coating (finishing) compositions were used, which were formed by diluting the concentrates (D) (see tables 1 and 2 below) with water as the carrier liquid (D1). The coating composition was applied respectively by immersing the base body in a bath with the respective Petition 870260046826, dated 05 / 18 / 2026, pp. 52 / 68 46 / 50 coating composition on the surface of the base body. For the production of comparison cores, a coating composition was used which was formed by diluting the concentrates (V) (see Table 1 below) with isopropanol as the carrier liquid. The coating composition not according to the invention corresponds to common finishing compositions obtained commercially. In the prior art, common finishes are used for glass-bonded cores, whose carrier liquid contains alcohols as the main component and contains very little water or even no water, since water attacks the alkaline silicate structure of water-bonded glass cores.

[0155] The viscosities of the coating compositions according to the invention and not according to the invention are almost identical.In the state of the art, "other components" (see Table 1) should be understood to mean common components of the group consisting of wetting agents, rheological additives, binders, suspending agents and biocides.

[0156] Subsequently, the males according to the invention thus obtained were exposed to a temperature in the range of 80°C to 220°C and the comparison males to a temperature in the range of 15°C to 30°C in such a way that the carrier liquid evaporates and a coating is formed on the base body from the non-liquid components of the respective coating composition. Petition 870260046826, dated 05 / 18 / 2026, pp. 53 / 68 47 / 50 Table 1: Composition of coating compositions Concentrate (D) for the coating composition according to the invention 1 Concentrate (V) for the coating composition not according to the invention V Component % by weight % by weight Carrier liquid (D1) Water 38.5 Isopropanol 34 Water 4 Component (D2) Acid (D2a) 0.5 0 Refractory materials (D3) Layered silicates (pyrophyllites, clay powder) 31 0 Refractory materials (D4) Zirconium silicate 8 Zirconium silicate 40 Microcrystalline graphite 8 Aluminum oxide 14.5 Particulate amorphous silica (D4a) 10 Other components 4 7.5 Coating composition according to the invention Coating composition not according to the invention Concentrate 100 parts by weight of concentrate (D) 100 parts by weight of concentrate (V) Dilution by carrier liquid 40 parts by weight of water 5 parts by weight of isopropanol Petition 870260046826, dated 05 / 18 / 2026, pages 54 / 68 48 / 50 Table 2: Composition of other coating compositions for the production of the male part according to the invention. Concentrate (D) for the coating composition according to invention no. 2 3 4 5 Component % by weight % by weight % by weight % by weight Carrier liquid (D1) Water 49.5 Water 49.5 Water 44.5 Water 36 Component (D2) Acid (D2a) 0.5 Acid (D2a) 0.5 Acid (D2a) 0.5 Acid (D2a) 0.5 Refractories (D3) Layered silicates (mica, clay powder) 26 Layered silicates (pyrophyllites, mica, clay powder) 26 Layered silicates (pyrophyllites, mica, clay powder) 23 Layered silicates (mica, clay powder) 31 Refractories (D4) Microcrystalline graphite 12 Microcrystalline graphite 12 Microcrystalline graphite 8 Microcrystalline graphite 8 Zirconium silicate 10 Zirconium silicate 9 Particulate amorphous silica (D4a) 8 Particulate amorphous silica (D4a) 8 Particulate amorphous silica (D4a) 10 Particulate amorphous silica (D4a) 8 Other components 4 4 4 7,5 Concentrate 100 parts by weight of concentrate (D) 100 parts by weight of concentrate (D) 100 parts by weight of concentrate (D) 100 parts by weight of concentrate (D) Dilution with carrier liquid 40 parts by weight of water 25 parts by weight of water 40 parts by weight of water 40 parts by weight of water, 2. Microscopic light examination

[0157] Starting from a male according to the invention (production and composition as described in point 1, coating composition as specified above in table 1) and starting from a male not according to the invention (production and composition as described in point 1, composition Petition 870260046826, dated 05 / 18 / 2026, pages 55 / 68 49 / 50 coating as specified above in Table 1), parts were extracted and embedded under vacuum using a two-component epoxy resin. Preparation was then carried out using a Struers Tegramin 20 sanding and polishing machine. Here, the samples are first ground with diamond discs and then polished with diamond suspensions to the final stage, resulting in the so-called polished section. The polished sections produced were then examined microscopically using a Zeiss Axioscope 5 light microscope with an Axiocam 305 color microscopy camera (D).

[0158] When comparing dry cores (according to the invention vs. not according to the invention), a clear difference in surface nature was discernible. In the core not according to the invention, the finish penetrates very deep into the base body and generates almost no surface seal, so that the molding material (A) can be easily recognized with the naked eye through the coating. Cores according to the invention, in turn, are characterized by a smooth surface seal, i.e., a cohesive coating layer, which is almost free of macroscopic pores, which is placed over the base body in such a way that it is possible to recognize which molding material (A) lies beneath the coating.

[0159] Figure 1 shows a micrograph of the core that does not conform to the invention, Figure 2 shows a micrograph of the core according to the invention. The micrograph extends, respectively, over an area close to the surface of the base body and the coating applied to that surface. In the base body, it is possible to clearly recognize the relatively larger particles of the molding material (H32 quartz sand, see below) (in Figure 1 at the bottom margin, in Figure 2 at the top margin). The coating joins the surfaces of the outer particles of the base body.

[0160] Figure 1 shows that the granular particles of the composition of Petition 870260046826, dated 05 / 18 / 2026, pages 56 / 68 50 / 50 coatings not conforming to the invention are deposited on the surface of the male part in a completely random manner, i.e., without a specific orientation. The granular particles penetrate the pores between the particles of the molding material, but these are not plugged and sealed. Therefore, the surface formed by the coating is neither flat nor smooth, but at least partially reproduces the contours of the surface of the base body, i.e., the coating presents unevenness and cavities, which mirror, to some extent, the irregularities of the surface of the base body.

[0161] Figure 2 shows that the platelet-shaped particles of the coating composition according to the invention align with their largest dimension parallel to the surface of the male part, and thereby bridge and cover the unevenness and cavities on the surface of the base body filled by the granular particles, such that irregularities on the surface of the base body hardly affect the surface of the coating. Therefore, the coating has a relatively flat and smooth surface. 3. Molding tests

[0162] Molding tests with aluminum were carried out on a cold chamber die casting machine. It was possible to successfully produce castings with a cutting speed of 15 m / s to 20 m / s, without penetration errors (penetration of the molten material into the core) or core breakage. In molding with cores not conforming to the invention, under the same conditions, constant penetration failures were observed. After molding, the castings were abruptly cooled by immersion in water. The core can be removed from the casting, for example, by slowly releasing the binder in water, or by removing it using water jets. Petition 870260046826, dated 05 / 18 / 2026, pages 57 / 68

Claims

1 / 5 CLAIMS 1. Process for the production of cores for application in pressure molding, characterized in that it comprises the steps of: (a) producing a molding material mixture by mixing components (A), (B) and (C); (b) molding the molding material mixture; (c) thermally hardening the formed molding material mixture, in which a base body of the core to be produced is formed;(d) apply - a composition (D) or a coating composition formed by diluting a composition (D) with carrier liquid (D1) onto the base body and subsequent drying, such that a coating is produced on the base body, in which a core is formed comprising the base body and a coating disposed over the base body, extending over at least the entire surface of the core which, in the molding process, comes into contact with a molten metal, wherein the components (A), (B) and (C) and the composition (D) are defined as follows: (A) a molding material selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum silicate sands and mixtures thereof; (B) particulate amorphous silicon dioxide or a mixture of additives containing particulate amorphous silicon dioxide;(C) a solution or dispersion comprising water of glass or a kit comprising raw materials for the production of a solution or dispersion comprising water of glass; (D) a composition for the production of a coating, wherein that composition comprises: (D1) a carrier liquid selected from the group consisting of Petition 870260046826, dated 18 / 05 / 2026, page 58 / 68 2 / 5 water and mixtures of water with one or more alcohols;(D2) a component of a group consisting of (D2a) one or more acids dissolved in the carrier liquid, wherein the aqueous phase formed by the carrier liquid with the acids dissolved therein has a pH of 5 or less, (D2b) one or more organic compounds of formula (I) O xR2 R1 O (I), wherein R1 and R2 are each monovalent groups independently containing from 1 to 26 carbon atoms, wherein group R1 is linked by a carbon atom contained in group R1 or by an oxygen atom contained in group R1 and wherein group R2 is linked by a carbon atom contained in group R2, or are linked together to form an annular structure such that the annular structure comprises in total from 4 to 7 annular atoms and groups R1 and R2 comprise in total from 2 to 26 carbon atoms, wherein group R1 is linked by a carbon atom contained in group R1 or by an oxygen atom contained in group R1 and wherein group R2 is linked by a carbon atom contained within the group;(D3) one or more refractory materials in the form of platelet-shaped particles selected from the group consisting of macrocrystalline graphites, hexagonal boron nitride and layered silicates; (D4) one or more refractory materials in the form of granular particles selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, nitride Petition 870260046826, dated 05 / 18 / 2026, page. 59 / 68 3 / 5 of silicon and rutile, wherein the refractory materials (D4) further comprise: (D4a) particulate amorphous silicon dioxide wherein the proportion of particulate amorphous silicon dioxide is preferably from 3 to 30% in relation to the total mass of the refractory materials (D4);where the proportion of refractory materials (D3) is in the range of 15% to 80% in relation to the total mass of refractory materials (D3) and refractory materials (D4) in component (D).; 2. Process according to claim 1, characterized in that in step (c) the thermal hardening occurs at temperatures in the range of 100°C to 300°C, particularly preferably from 100°C to 250°C.

3. Process, according to any one of claims 1 or 2, characterized in that in step (d), - the base body, when applying composition (D) or the coating composition, has a temperature below 80°C, preferably in the range of 15°C to 35°C; and / or - composition (D) or the coating composition is applied to the surface of the base body by a process selected from the group consisting of spraying, dipping, flooding and brushing, preferably dipping; and / or - drying occurs at temperatures in the range of 80°C to 220°C, preferably at temperatures in the range of 100°C to 140°C, particularly preferably at temperatures in the range of 105°C to 120°C.

4. Application of a core, characterized by the fact of using, in pressure molding, a core comprising: (i) a base body comprising (A) a molding material selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum silicate sands and mixtures thereof and (B) particulate amorphous silicon dioxide bonded by water of glass (ii) and a coating disposed over the base body extending at least over the entire surface of the core, which, in the casting process, comes into contact with a molten metal, wherein the coating comprises: (D3) one or more refractory materials in the form of platelet-shaped particles selected from the group consisting of macrocrystalline graphites, hexagonal boron nitride and layered silicates;(D4) one or more refractory materials in the form of granular particles selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, sillimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M5(PO4)3OH, wherein M is an alkaline earth metal, silicon nitride and rutile, wherein the refractory materials (D4) further comprise: (D4a) particulate amorphous silicon dioxide wherein the proportion of particulate amorphous silicon dioxide is preferably from 3 to 30% in relation to the total mass of the refractory materials (D4); where the proportion of refractory materials (D3) is in the range of 15% to 80% in relation to the total mass of refractory materials (D3) and refractory materials (D4).

5. Application of a male die, according to claim 4, characterized in that it is for pressure molding of light metals, particularly of the group consisting of aluminum and aluminum alloys.

6. Process for applying a core in pressure molding, particularly in pressure molding of light metals, characterized by comprising: - producing a core according to a process for producing cores for application in pressure molding as defined in any of claims 1 to 3, or providing a core as defined in claim 4, or a core produced according to a process for producing cores for application in pressure molding as defined in any of claims 1 to 3, - inserting the core into a casting mold, - producing a casting by melting a molten metal under applying a pressure of up to 200 MPa in the casting mold and solidifying the molten metal, - removing the core from the casting. Petition 870260046826, dated 05 / 18 / 2026, pages 62 / 68

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