METHOD FOR PRODUCE A MOLDING MATERIAL MIXTURE AND A MOLDED BODY THEREOF IN THE FOUNDRY INDUSTRY, AS WELL AS KIT FOR USE IN THIS METHOD AND APPROVAL FOR USE IN THIS METHOD

Description

[0001] The present invention relates to a method for producing a molding material mixture or for producing a molding material mixture and a molded body therefrom, preferably a mold or core, for use in the foundry industry, wherein the molding material mixture comprises a molding base material and a solution or dispersion comprising lithium-containing water glass, comprising the steps (1) producing or providing a kit comprising at least as separate components: (K1) an aqueous solution or dispersion comprising water glass and (K2a) a first water glass-free solution or dispersion comprising lithium ions dissolved in water, and (K2b) a second water glass-free solution or dispersion comprising lithium ions dissolved in water at a lower concentration than in component (K2a).and then (2) producing a mixture of the mold base material with a portion of component (K1) and with a portion of component (K2a) as well as with a portion of component (K2b). The present invention further relates to a aforementioned kit, in particular for use in the process according to the invention. The present invention also relates to a system for producing an intermediate solution or dispersion comprising lithium-containing water glass, for use in the production of a mold base material mixture or for producing a mold base material mixture and a molded body therefrom. Molds essentially consist of molds or molds and cores, which, after assembly, represent the negative forms of the casting to be produced. These cores and molds are molded bodies and regularly consist of a refractory mold base material, for example quartz sand, and a suitable binder system.which gives the mold sufficient mechanical strength after removal from the molding tool. The refractory molding material is preferably in particulate and free-flowing form, so that (after being incorporated into a molding material mixture) it can be filled into a suitable mold cavity and compacted there. The binder creates a strong bond between the particles of the molding material, so that the mold achieves the required mechanical stability.

[0002] Molds and the components they contain (molds and, if applicable, cores) must meet various requirements. During the casting process itself, they must first possess sufficient strength and temperature resistance to accommodate the molten metal in the cavity formed by one or more molds. Once solidification begins, the mechanical stability of the casting is ensured by a solidified metal layer that forms along the walls of the mold.

[0003] The material of the mold is then intended to decompose under the influence of the heat emitted by the metal, losing its mechanical strength; that is, the cohesion between individual particles of the refractory material is lost. Ideally, the mold disintegrates back into fine particles of the mold material, which can be easily removed from the casting.

[0004] Both organic and inorganic binders can be used to produce molded parts, and their curing can be achieved through either cold or hot processes. Cold processes are those carried out essentially without heating the mold used for core production, typically at room temperature or at a temperature caused by a reaction. Curing occurs, for example, by passing a gas through the molding material mixture to be cured, thereby triggering a chemical reaction. In hot processes, the molding material mixture is heated to a sufficiently high temperature after shaping, for example, by the heated mold, to drive off the solvent contained in the binder and / or to initiate a chemical reaction that cures the binder.

[0005] Organic phenolic resin-based binders, regardless of their composition, have the disadvantage of decomposing during casting, sometimes emitting significant amounts of pollutants such as benzene, toluene, and xylene. Furthermore, casting organic binders generally results in undesirable odor and fume emissions. In some systems, undesirable emissions even occur during the production and / or storage of the molds.

[0006] For this reason, inorganic binders are increasingly preferred for use in the foundry industry; there is a high level of technical and economic interest in further improving the product properties of the foundry components produced in this way, especially molds and cores.

[0007] Inorganic binders have been known for a long time, especially those based on water glass. Three different methods are available for curing water glass: (i) passing a gas, e.g., CO₂, air, or a combination of both; (ii) adding liquid or solid hardeners, e.g., certain esters; and (iii) thermal curing, e.g., in the so-called hot box process or by microwave treatment.

[0008] However, the use of inorganic binder systems is often associated with other typical disadvantages: Foundry castings made from inorganic binders frequently exhibit relatively low strength unless suitable, special measures are taken. This is particularly evident immediately after the core or mold is removed from the tooling. The strength at this point ("hot strength" or "instant strength") is especially important for the safe handling of the cores or molds during removal from the tooling. High "cold strength" (i.e., the strength after the core or mold has fully cured) is also important to ensure that the desired casting can be produced with as few casting defects as possible.

[0009] Document DE-OS 2652421 describes binders consisting of a solution of a mixture of potassium silicate and / or sodium silicate with lithium silicate, which are suitable, for example, as binders for foundry cores.

[0010] Document US 4,347,890 describes a method for binding a particulate material. The method involves mixing the particulate material with a solution containing lithium ions (according to Example 1, this is an aqueous solution of lithium silicate or lithium water glass), adding sodium silicate to this mixture, and finally shaping the mixture and curing it using microwave radiation.

[0011] Document WO 2006 / 024540A2 describes, among other things, a process for the production of casting molds, in which a proportion of a particulate metal oxide is added to a water glass-based binder.

[0012] Document WO 2014 / 202042A1 describes lithium-containing molding compound mixtures based on an inorganic binder for the production of molds and cores for metal casting. It describes, for example, how the storage stability of cores or molds produced with such binders can be improved by the defined addition of lithium-containing compounds to inorganic binders based on water glass. At the same time, the cores or molds in question are intended to exhibit a high level of strength.

[0013] In industrial practice, it has been shown that liquid, inorganic binders containing lithium ions, especially those based on water glass, can become unstable too quickly, depending on the lithium ion concentration and storage conditions (particularly the storage temperature). Such unstable binders, for example, develop turbidity after only a few days of storage, such as through gel formation, and / or exhibit precipitation of solids, such as carbonates and / or silicates, thus becoming inhomogeneous or heterogeneous. It has also been shown that such turbidity in, or solid precipitation from, liquid, lithium-containing, inorganic binders is detrimental to their processing and can cause problems, particularly in pumps, filters, and / or dosing units, as well as in further processing.A high lithium ion content and elevated temperatures therefore promote the adverse tendency of these liquid binders to instability.

[0014] A certain, elevated lithium ion content in inorganic binder systems based on water glass is therefore advantageous for achieving high stability, particularly high storage stability, of cores or molds in the foundry industry. On the other hand, however, such binders with high lithium ion contents exhibit comparatively poor storage stability.

[0015] It was therefore a primary object of the present invention to provide a method for producing a molding material mixture or for producing a molding material mixture and a molded body (such as a mold or a core), in particular a storage-stable molded body, for the foundry industry, which allows the use of an inorganic binder, especially water glass, with a variably adjustable - even high - concentration of lithium ions depending on external parameters and thereby alleviates or avoids the aforementioned disadvantages of the prior art.

[0016] Another object of the present invention was to provide an easy-to-use kit suitable for producing a liquid, lithium-containing, inorganic binder with a variably adjustable lithium ion concentration, wherein the binder should be stable under the individual storage conditions at least until its intended use.

[0017] An additional specific objective of the present invention was to provide a system, such as a production system, which enables the execution of the aforementioned process on an industrial manufacturing scale.

[0018] The invention, as well as preferred combinations of preferred parameters, properties, and / or components of the present invention, are defined in the appended claims. Preferred aspects of the present invention are also specified or defined in the following description and in the examples.

[0019] It has now been surprisingly found that the primary problem as well as further problems and / or sub-problems of the present invention are solved by a method according to the invention for producing a molding material mixture as defined in claim 1.

[0020] A preferred embodiment of the inventive method is wherein the molar modulus SiO 2 / M 2 O in component (K1) is larger than the molar modulus of the lithium-containing water glass in the molding material mixture to be produced.

[0021] Particularly preferred is the embodiment of the process according to the invention, wherein the component (K1) is an aqueous solution or dispersion comprising water glass, wherein the SiO2 content is in the range of 20 to 34 wt.%, preferably in the range of 25 to 34 wt.%, based on the total mass of the solution or dispersion, and wherein the molar modulus SiO2 / M2O is greater than the molar modulus of the lithium-containing water glass in the molding compound mixture to be produced.

[0022] A preferred method according to the invention is as described above (in particular, a method according to the invention which is referred to as preferred in this text), wherein the aqueous solution or dispersion comprising water glass (K1) has a pH value in the range of 10.0 to 13.0, preferably in the range of 11.0 to 12.5. A preferred method according to the invention is also as described above (in particular, a method according to the invention which is referred to as preferred in this text), wherein the first water glass-free solution or dispersion comprising lithium ions (K2a) dissolved in water has a pH value in the range of 8.0 to 14.0, preferably in the range of 11.5 to 13.5.

[0023] Within the scope of the present invention, the following designations each have the meanings given below: "SiO 2" means the amount of substance in moles of silicon in the aqueous solution or dispersion, calculated according to the molecular formula SiO 2, regardless of whether the silicon underlying this calculation is actually present as SiO 2 in the inventive method (or the inventive kit).

[0024] "M" means an alkali metal, selected from the group consisting of lithium, sodium and potassium.

[0025] "M₂O" means the total amount of substance in moles of alkali metal in the aqueous solution or dispersion, calculated according to the molecular formula M₂O. "Li₂O" accordingly means the amount of substance in moles of lithium, calculated according to the molecular formula Li₂O. These calculations are independent of whether the alkali metals on which the calculation is based are actually present in the form "M₂O" in the process (or kit) according to the invention.

[0026] In the above-described process according to the invention, component (K1) comprises an aqueous (water-containing) solution or dispersion comprising water glass. For the purposes of this invention, water glass is understood to be alkali water glass known per se, which comprises glassy, ​​i.e., amorphous, water-soluble sodium, potassium, and—in low concentrations that do not impair the stability, in particular the storage stability, of the water glass—lithium silicates, or aqueous solutions of the aforementioned sodium, potassium, and lithium silicates, solidified from a melt.

[0027] The mold base material (M1) is preferably a particulate refractory mold base material. In this text, "refractory" refers, in accordance with standard technical understanding, to masses, materials, and minerals that can withstand, at least briefly, the temperature stress during casting or the solidification of a molten metal, such as aluminum. Suitable mold base materials include, for example, quartz, zircon, or chromium ore sand, olivine, vermiculite, bauxite, chamotte, and artificial mold base materials. The mold base material (M1) can be a mixture of several (preferably particulate, refractory) materials.

[0028] The molded body produced according to the inventive method described above is preferably a molded body for use in the foundry industry, and particularly preferably a mold or a core. A particular advantage of the inventive method is the possibility of using a binder system with a high or variably adjustable lithium ion content, which is required for the production of molded bodies with high strength and high storage stability, and which is not subject, or is subject to a much lesser extent, to the time limitations of the storage periods of known binders with a high (but generally unchangeable and / or not intended to be changed) lithium ion content.According to the inventive method, molded parts can be produced that exhibit high strength and can be stored for extended periods, preferably from one day to two weeks, without losing their advantageous properties to a practically relevant degree. The molded parts produced according to the inventive method can thus be easily handled after their production and until use in a casting process without deforming or breaking, and / or can be stored for extended periods, enabling production for stock. A particularly advantageous property of the molded parts produced according to the inventive method is their ability to retain their high strength and stability even at elevated humidity levels, so that the manufactured molded parts are characterized by high storage stability even in humid or warm, humid climates.But the method according to the invention also offers advantages for changing weather conditions (seasons) in temperate climate zones.

[0029] In the process described above according to the invention, component (K2a) comprises lithium ions dissolved in water. If component (K2a) is a solution, the lithium ions are part of the solution. If component (K2a) is a dispersion, the lithium ions are present at least predominantly and preferably completely in the continuous (liquid, aqueous) phase, preferably dissolved. In addition to lithium ions, component (K2a) preferably also comprises sodium ions and / or potassium ions as further alkali metal ions. Component (K2a) can comprise lithium ions and potassium ions, or lithium ions and sodium ions, or lithium ions, sodium ions, and potassium ions. The maximum value of the total concentration of lithium, sodium, and potassium ions in component (K2a) depends, among other things, on the type and proportion of the alkali metal ions present.The person skilled in the art knows how to adjust the required and / or preferred concentrations of alkali metal ions under the given or desired conditions.

[0030] The kit manufactured or provided in step (1) includes the following component: (K2b) a second water glass-free solution or dispersion comprising dissolved in water, wherein the concentration of lithium ions is lower than in component (K2a) and is preferably in the range of 0.1 to 5.0 mol / L, particularly preferably in the range of 0.1 to 2.0 mol / L, and the total concentration of lithium, sodium and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and preferably the total concentration of lithium, sodium and potassium ions differs by no more than 20%, preferably by no more than 10%, from the total concentration of lithium, sodium and potassium ions in component (K2a).and wherein step (2) comprises: (2) preparing a mixture of the mold base material (M1) with a proportion of component (K1) as well as with a proportion of component (K2a) and optionally a proportion of component (K2b), wherein the solution or dispersion (M2) is formed by mixing the components of the kit used together.

[0031] A preferred method according to the invention is as described above (in particular, a method according to the invention which is referred to as preferred in this text), wherein the second water glass-free solution or dispersion comprising lithium ions dissolved in water (K2b) has a pH value in the range of 8.0 to 14.0, preferably in the range of 11.5 to 13.5. With regard to preferred pH values ​​for the solutions or dispersions (K1) and / or (K2a), reference is made to the disclosure above.

[0032] According to the invention, a method for producing a molding material mixture or for producing a molding material mixture and a molded body therefrom, preferably a storage-stable molded body, is thus a method comprising the molding material mixture: (M1) a mold base material and (M2) a solution or dispersion comprising lithium-containing water glass having a molar modulus SiO₂ / M₂O in the range of 1.6 to 3.5, preferably in the range of 1.8 to 3.0, and in which the molar fraction of Li₂O to M₂O is in the range of 0.05 to 0.60, preferably in the range of 0.1 to 0.4, comprising the following steps: (1) manufacturing or providing a kit comprising at least the following separate components: (K1) an aqueous solution or dispersion comprising water glass, wherein the SiO₂ content is in the range of 20 to 34 wt.%, preferably in the range of 25 to 34 wt.%, based on the total mass of the solution or dispersion, wherein optionally the molar modulus SiO₂ / M₂O is greater than the molar modulus of the lithium-containing water glass in the mold base mixture to be manufactured, (K2a) a first water glass-free solution or dispersion comprising lithium ions dissolved in water,wherein the concentration of lithium ions is in the range of 0.3 to 5.3 mol / L, preferably in the range of 1.0 to 5.0 mol / L, and the total concentration of lithium, sodium and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and (K2b) a second water glass-free solution or dispersion comprising lithium ions dissolved in water, wherein the concentration of lithium ions is lower than in component (K2a) and is preferably in the range of 0.1 to 5.0 mol / L, particularly preferably in the range of 0.1 to 2.0 mol / L, and the total concentration of lithium, sodium and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and preferably the total concentration of lithium, sodium and potassium ions is reduced by no more than 20%, preferably by no more than 10%,from the total concentration of lithium, sodium, and potassium ions in component (K2a), and then (2) preparing a mixture of the mold base material (M1) with a portion of component (K1), as well as with a portion of component (K2a), and optionally with a portion of component (K2b), wherein the solution or dispersion (M2) is formed by mixing the components of the kit used together, where M2O denotes the total amount of lithium, sodium, and potassium oxide.

[0033] In the process described above according to the invention, component (K2b) comprises alkali metal ions dissolved in water, preferably lithium ions, sodium ions, and / or potassium ions. Component (K2b) comprises lithium ions. Component (K2b) can comprise only lithium ions as alkali metal ions. Component (K2b) can also comprise lithium ions and sodium ions as alkali metal ions, or it can comprise lithium ions and potassium ions.

[0034] The concentration of lithium ions in component (K2b) is lower than in component (K2a) and is preferably in the range of 0.1 to 5.0 mol / L, particularly preferably in the range of 0.1 to 2.0 mol / L.

[0035] In a preferred embodiment of the inventive method, wherein the total concentration of lithium, sodium, and potassium ions in component (K2b) differs from the total concentration of lithium, sodium, and potassium ions in component (K2a) by no more than 20%, preferably by no more than 10%, it is achieved that when the kit components (K1), (K2a), and (K2b) are mixed together (in the absence or presence of the base material (M1)), the total concentration of lithium, sodium, and potassium ions in the resulting solution or dispersion (M2) is equal to or at least similar to the total concentration of lithium, sodium, and potassium ions in a solution or dispersion (M2) obtained solely by mixing the kit components (K1) and (K2a) together.Thus, when using the kit component (K2b) (which has a lower lithium ion concentration than the kit component (K2a)) in the process according to the invention, the lithium ion concentration of the resulting solution or dispersion (M2) is influenced, preferably reduced, compared to a solution or dispersion (M2) which was produced by mixing only the kit components (K1) and (K2a) with each other under otherwise identical conditions.

[0036] Kit component (K2b) can thus be used to easily and precisely reduce the lithium ion content in a solution or dispersion (M2) without affecting or altering the other properties of the resulting solution or dispersion (M2), such as its molar modulus SiO₂ / M₂O or its total alkali metal ion concentration, in a practically relevant way compared to adding a corresponding amount of kit component (K2a). By adding component (K2b), it can be ensured, even with a reduction in the amount of (K2a), that the binder (M2) to be produced has the same modulus and concentration as it did previously with a higher proportion of (K2a).

[0037] In step (2) of the preferred method according to the invention described above, a mixture of the mold base material (M1) is produced with a proportion of component (K1) as well as with a proportion of component (K2a) and with a proportion of component (K2b).

[0038] This allows for flexible, individual adjustment of the desired lithium ion concentration in the solution or dispersion (M2). Thus, the lithium ion content or concentration of the solution or dispersion (M2) can be adjusted to account for ambient conditions (especially humidity), and only the amount of lithium ions required to optimize the production process under the prevailing environmental conditions can be added. This flexible method of adding lithium ions during the production of the solution or dispersion (M2) also saves on raw material costs for the expensive lithium compounds contained in the kit components (K2a) and (K2b).

[0039] The mixture described above can be produced by first mixing a portion of component (K1) with the molding base material (M1) and then mixing this premix with a portion of component (K2a) and a portion of component (K2b) to form a molding material mixture, wherein the lithium ion content in the molding material mixture is preferably adjusted by selecting component (K2a) and component (K2b) in suitable amounts and lithium ion concentrations. Mixing the premix with a portion of component (K2a) and a portion of component (K2b) also forms the solution or dispersion (M2).

[0040] The mixture can also be prepared by first mixing the molding base material (M1) with a portion of component (K2a) and with a portion of component (K2b), and then mixing this premix with a portion of component (K1) to form a molding material mixture, wherein the lithium ion content in the molding material mixture is preferably adjusted by selecting component (K2a) and component (K2b) in suitable amounts and lithium ion concentrations. Mixing the premix with a portion of component (K1) also forms the solution or dispersion (M2).

[0041] Preferably, in step (2) of the process according to the invention, the mixture is prepared by first mixing a portion of component (K1) with a portion of component (K2a) and with a portion of component (K2b) to form a solution or dispersion (M2), wherein the lithium ion content in the solution or dispersion (M2) is preferably adjusted by selecting component (K2a) and component (K2b) in suitable amounts and lithium ion concentrations. This separately prepared solution or dispersion (M2) is then mixed with the mold base material (M1).

[0042] Particularly preferably, the mixture is produced in step (2) of the process according to the invention by first mixing a portion of component (K2a) with a portion of component (K2b) to form a "premix (K2a) + (K2b)" and then mixing this "premix (K2a) + (K2b)" with a portion of component (K1) to form a solution or dispersion (M2), wherein the lithium ion content in the solution or dispersion (M2) is preferably adjusted by selecting component (K2a) and component (K2b) in suitable amounts and lithium ion concentrations.

[0043] A method according to the invention or a method preferred according to the invention as specified above or below is preferred, wherein in step (2) a solution or dispersion (M2) is first formed in the absence of the mold base material by mixing the components of the kit used together and then a mixture of or a portion of the mold base material (M1) is formed with a portion or the total amount of the solution or dispersion (M2) obtained.

[0044] The mixing of the components of the kit is carried out in a manner known per se, preferably with the aid of a stirrer or a mixing tube, preferably a static mixing tube.

[0045] The preferred method variant (hereinafter also referred to as "premixing the kit components used") is particularly advantageous because it allows a premixed solution or dispersion (M2) to be prepared and then stored for a certain period of time, preferably adapted (or adaptable) to the ambient conditions, so that precipitation (due to the precipitation of components from the solution or dispersion (M2)) and / or gel formation does not occur due to instabilities. Such a premixed solution or dispersion (M2) can also be used to feed an automated or semi-automated production facility, so that the premixed solution or dispersion (M2) can be used directly in serial or predominantly serial industrial production.Our own investigations have shown that a (premixed) solution or dispersion (M2) prepared as described above – depending on the concentration and storage conditions (e.g. temperature, stirring) – can be stored for up to several weeks, preferably up to 6 days, particularly preferably up to 3 days, without any quality defects being observed in the solution or dispersion (M2) (see below) or in the production of molded parts using the stored solution or dispersion (M2) or in castings produced using the molded parts made with the stored solution or dispersion (M2).

[0046] It has also been shown that the separate (unmixed) components (K1), (K2a), and (K2b) remain stable over long periods, for example, over a year, and remain unchanged or substantially unchanged during storage without any practically relevant loss of quality. A particular advantage of the present invention is therefore that water glass-containing binders with a high lithium ion concentration can now be made available for manufacturing or production on demand and used quickly, thus solving the problem associated with the high perishability or poor (short) shelf life of such water glass-containing binders with a high lithium ion concentration. The prepared (premixed) solution or dispersion (M2) is preferably stored in closed containers.

[0047] In a particularly advantageous embodiment of the method according to the invention, a method as described above (in particular a method which is referred to above or below as preferred, preferably a method variant comprising premixing the kit components used) is preferred, wherein the solution or dispersion produced (M2) contains no visible precipitates or gel components before the mixture is formed with the mold base material (M1).

[0048] Our own experiments have shown that checking the prepared solution or dispersion (M2) for visible precipitates or gel components can be a simple visual inspection. In practice, a person skilled in the art can thus reliably determine whether the solution or dispersion (M2) has the required consistency or quality for further processing in step (2) of the inventive process. This inspection is preferably carried out directly before mixing the mold base material (M1) with the prepared solution or dispersion (M2) to produce a molding material mixture. If the inspection reveals that the prepared solution or dispersion (M2) does not have the required consistency or quality for further processing,If a product exhibits insufficient quality, it is not used in further process steps, but is preferably replaced by another solution or dispersion (M2) that possesses the consistency or quality required for further processing. This process design allows for fast, simple, and cost-effective quality control to be carried out in the manufacturing plant.

[0049] A preferred method according to the invention is also as described above (in particular a method which is referred to above or below as preferred, preferably a method variant comprising the premixing of the kit components used), wherein the mixing of the components of the kit used together to form the solution or dispersion (M2) takes place in a mixing device, wherein the mixing device is preferably a metering container or a mixing tube and preferably a mixing tube, particularly preferably a static mixing tube.

[0050] The mixing unit can be a separate, standalone unit operated alongside or independently of at least partially serial production of molded parts ("discontinuous operation"). Such discontinuous operation has the advantage that different batches of solutions or dispersions (M2) can be produced at any time, and their quality can be checked in each case. The mixing unit can also be part of at least partially serial production of molded parts, for example, as part of a plant for at least partially serial production of molded parts ("continuous or semi-continuous operation"). Such continuous or semi-continuous operation is particularly suitable for the (industrially preferred) at least partially serial production of larger quantities of molded parts, for example, production for stock.The mixing device can also be a storage container in which at least one of the components (K1), (K2a) and / or (K2b) is stored or kept for use in at least partially serial production of molded parts and into which at least one complementary component (K1), (K2a) and (K2b) is added as required.

[0051] The mixing device mentioned above is preferably a metering container or a mixing tube. A static mixing tube is preferred. A static mixing tube is a particularly preferred mixing device for use in the process according to the invention. Static mixing tubes from Sulzer, such as the "CompaX™<" or "SMX™< plus" type, are suitable for use in the process according to the invention. Preferred metering containers are selected from the group consisting of "Intermediate Bulk Containers" (also referred to as "IBC containers" or "Schütz containers"), drums, and canisters. A preferred mixing device for the aforementioned continuous or semi-continuous operation is a mixing tube, preferably a static mixing tube. However, a metering container can also be used in continuous or semi-continuous operation.

[0052] A method according to the invention as described above is also preferred (in particular a method designated as preferred above or below, preferably a method variant comprising premixing the kit components used), wherein the proportion or total amount of the solution or dispersion formed (M2) is stored in the mixing device for a period of no more than 7 days, preferably no more than 3 days, and particularly preferably no more than 2 days, before the formation of a mixture with the or a proportion of the base material (M1). This counteracts the formation of precipitates (by precipitation of components from the solution or dispersion (M2)) and / or gels.

[0053] If the mixing device (mixing tube or dosing container) is part of at least partial serial production of molded parts, longer storage of the produced solution or dispersion (M2), such as storage for more than two days, preferably more than one day, is generally not intended. Instead, in these cases, shorter storage, preferably for no more than one day, is usually provided, so that at least partial serial production or such a production process is possible. However, longer storage (preferably for the period defined above of no more than seven days) of the produced solution or dispersion (M2) may be preferred in cases where the mixing device also serves as a storage container for a produced solution or dispersion (M2) before mixing with the molding base material (M1).

[0054] A preferred method according to the invention as described above (in particular a method which is referred to above or below as preferred) for producing a molding material mixture and a molded body therefrom, with the additional steps Setting, determining, or estimating one or more parameters selected from the group consisting of ambient temperature during the manufacture of the molded part, relative humidity during the manufacture of the molded part, temperature during storage of the molded part, relative humidity during storage of the molded part, absolute humidity during the manufacture of the molded part, absolute humidity during storage of the molded part, and storage duration of the molded part, and controlling the proportions of components (K2a) and (K2b) to be used depending on the set, determined, or estimated parameter(s) selected from the group consisting of ambient temperature during the manufacture of the molded part, relative humidity during the manufacture of the molded part, temperature during storage of the molded part, relative humidity during storage of the molded part, and absolute humidity during the manufacture of the molded part.Absolute humidity during storage of the molded part, and storage duration of the molded part.

[0055] Particularly preferred is a combination of a parameter from the group consisting of ambient temperature during the manufacture of the molded body and temperature during the storage of the molded body with a parameter from the group consisting of relative humidity during the manufacture of the molded body and relative humidity during the storage of the molded body.

[0056] The "relative humidity" indicates - in accordance with the usual understanding of the person skilled in the art - the actual water content in the air at a given temperature, based on the physical maximum of the water content of the air at that temperature.

[0057] Absolute humidity is determined – in accordance with the usual understanding of experts – from temperature and relative humidity. Higher absolute humidity is achieved, for example, when the temperature rises while the relative humidity remains constant, or when the relative humidity increases while the temperature remains constant.

[0058] Factors that make setting a comparatively higher concentration of lithium ions in the inventive process seem advantageous include, in particular, a higher absolute humidity during the production and / or storage of a molded body and / or a longer storage period of the molded body.

[0059] Depending on the set, determined, or estimated parameter value, a higher or lower concentration of lithium ions in the solution or dispersion (M2) is preferably achieved. A higher concentration of lithium ions can preferably be achieved by increasing the proportion of component (K2a) in the solution or dispersion (M2), for example, by increasing the proportion of component (K2a) added and / or by decreasing the proportion of component (K2b) added.

[0060] Accordingly, a method according to the invention as described above (in particular a method which is referred to above or below as preferred) is preferred, wherein the method is designed as at least partially serial, preferably as predominantly serial, production of a number of molded parts, wherein, in the event of an increase or expected increase of one or more parameters selected from the group consisting of ambient temperature during the production of the molded part, relative humidity during the production of the molded part, temperature during storage of the molded part, relative humidity during storage of the molded part, absolute humidity during the production of the molded part, absolute humidity during storage of the molded part, and storage duration of the molded part the proportions of component (K2a) used for the production of the molded parts are increased and / or the molar proportion of Li 2 O to M 2 O in the solution or dispersion (M2) for the production of the molded parts is increased.

[0061] Conversely, it is of course advantageous to design the method according to the invention in such a way that, in the event of a decrease or reduction, or an expected decrease or reduction, of one or more parameters, a parameter is selected from the

[0062] Group consisting of ambient temperature during the production of the molded part, relative humidity during the production of the molded part, temperature during the storage of the molded part, relative humidity during the storage of the molded part, absolute humidity during the production of the molded part, absolute humidity during the storage of the molded part, and storage duration of the molded part. the proportions of component (K2a) used for the manufacture of the molded parts are reduced and / or the proportions of component (K2b) used for the manufacture of the molded parts are increased and / or the molar proportion of Li 2 O to M 2 O in the solution or dispersion (M2) used for the manufacture of the molded parts is reduced.

[0063] A preferred method according to the invention is also as described above (in particular a method which is referred to above or below as preferred), wherein a data acquisition device or data processing device is provided for setting, determining or estimating one or more parameters selected from the group consisting of ambient temperature during the manufacture of the molded part, relative humidity during the manufacture of the molded part, temperature during the storage of the molded part, relative humidity during the storage of the molded part, absolute humidity during the manufacture of the molded part, absolute humidity during the storage of the molded part and storage duration of the molded part, and a control device is provided for controlling the proportions of components (K2a) and (K2b) to be used depending on the set, determined or estimated parameter(s).wherein preferably a data connection is established between the data acquisition device or the data processing device and the control device for the transmission of parameter data.

[0064] The aforementioned data acquisition or data processing device is preferably an instrument for recording climatic conditions or a data logger. The aforementioned control device is preferably an automated mixing device.

[0065] This aforementioned embodiment of the method according to the invention has the advantage that the addition or dosage of the kit components can be carried out automatically or at least semi-automatically in an industrial manufacturing process, depending on the influencing parameters.

[0066] A method according to the invention is also preferred as described above (in particular a method which is referred to above or below as preferred), wherein, in the preparation of the molding compound mixture, one or more components are additionally added which are selected from the group consisting of: (M3) particulate amorphous silicon dioxide; barium sulfate; carbohydrates; phosphorus compounds; surfactants; boron oxides; metal oxides; lubricants, esters and release agents.

[0067] The particulate amorphous silicon dioxide ("SiO₂") used is preferably particulate amorphous silicon dioxide of conventional purity, i.e., with typical impurities and minor components. For the purposes of the present invention, particulate amorphous silicon dioxide with a content of at least 85 wt%, particularly preferably at least 90 wt%, and most preferably at least 95 wt% silicon dioxide is used. The term "particulate" refers to a solid powder (including dusts) or granules, which are preferably free-flowing and thus sieveable. Preferably, the particle-number-related d90 value of the particulate amorphous silicon dioxide is less than 100 µm, particularly preferably less than 45 µm. This means that 90% of the particles of the particulate, amorphous silicon dioxide contained in the molding compound mixture are preferably smaller than 100 µm, preferably smaller than 45 µm.The d90 value is preferably determined by scanning electron microscopy. Both synthetically produced and naturally occurring types of particulate amorphous silicon dioxide can be used. The latter are known, for example, from document DE 102007045649, but are not preferred because they often contain significant crystalline components and are therefore classified as carcinogenic. Synthetically produced particulate amorphous silicon dioxide is manufactured by a controlled chemical reaction. Examples include the flame hydrolysis of silicon tetrachloride and the reduction of quartz sand with coke in an electric arc furnace during the production of ferrosilicon and silicon. The amorphous SiO₂ produced by these two processes is also referred to as "pyrogenic SiO₂".Another example of synthetically produced particulate amorphous silicon dioxide is silicon dioxide obtained by thermal decomposition of ZrSiO₄ to ZrO₂ and SiO₂ and partial or substantially complete separation of the ZrO₂, as described, for example, in document DE 102012020509. Preferably, synthetically produced particulate amorphous SiO₂ is used as or in component (M3) according to the inventive process, particularly pyrogenic particulate amorphous SiO₂ and / or SiO₂ from the thermal decomposition of ZrSiO₄. Particulate amorphous silicon dioxide suitable for the purposes of the present invention is also described, for example, in documents DE 102004042535A1, DE 102012020510A1, and DE 102012020511A1. Preferably, the particulate, amorphous silicon dioxide is used in an amount in the range of 0.3 to 3.0 wt.%, based on the total weight (total mass) of the molding material mixture (sum of the weights orMasses of the components (M1), (M2) and - if any - (M3) and, if applicable, other components).

[0068] Barium sulfate can be synthetically produced or natural, i.e., in the form of minerals containing barium sulfate, such as barite or baryte. Synthetically produced barium sulfate (also called "Blanc Fixe") is produced, for example, by means of a precipitation reaction. For this purpose, readily soluble barium compounds (barium salts) are usually dissolved in water. Subsequently, the sparingly soluble barium sulfate is precipitated by adding readily soluble sulfate salts (such as sodium sulfate) or sulfuric acid. The precipitated barium sulfate is filtered off, dried, and optionally ground. Barium sulfate suitable for the purposes of the present invention is also specified, for example, in document DE 102012104934. Preferably, the barium sulfate is used in an amount in the range of 0.02 to 5.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights of the components).Masses of the components (M1), (M2) and - if any - (M3) and, if applicable, other components).

[0069] The carbohydrates that can be used as or in component (M3) in the process described above according to the invention are preferably selected from the group consisting of oligosaccharides and polysaccharides, and more preferably from the group consisting of cellulose, starch, and dextrin. The carbohydrates mentioned can be used individually or in combination with one another. Carbohydrates suitable for the purposes of the present invention are also specified, for example, in document EP 2104580. Preferably, the carbohydrate(s) are used in an amount in the range of 0.01 to 10.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2), and—if present—(M3), and optionally other components).

[0070] The phosphorus compounds that can be used as or in component (M3) in the process described above according to the invention are preferably selected from the group consisting of organic phosphates and inorganic phosphates, and more preferably from the group consisting of inorganic alkali metal phosphates. The aforementioned phosphorus compounds can be used individually or in combination with one another. Phosphorus compounds suitable for the purposes of the present invention are also specified, for example, in document EP 2097192. Preferably, the phosphorus compound(s) are used in an amount in the range of 0.05 to 1.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2) and – if present – ​​(M3) and optionally further components).

[0071] The surfactants that can be used as or in component (M3) in the above-described process according to the invention are preferably selected from the group consisting of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. These surfactants can be used individually or in combination. Surfactants suitable for the purposes of the present invention are also specified, for example, in document DE 102007051850. Preferably, the surfactant(s) are used in an amount in the range of 0.001 to 1.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2), and—if present—(M3), and optionally other components). The aforementioned surfactants can also be used as a component of component (K1).

[0072] The oxide boron compounds that can be used as or in component (M3) in the process described above according to the invention are preferably selected from the group consisting of borates, boric acids, boric anhydrides, borosilicates, borophosphates, and borophosphosilicates, and particularly preferably selected from the group consisting of alkali and alkaline earth borate, wherein the oxide boron compound preferably does not contain any organic groups. The aforementioned oxide boron compounds can be used individually or in combination with one another. Oxide boron compounds suitable for the purposes of the present invention are also specified, for example, in document DE 102013111626. Preferably, the oxide boron compounds are used in an amount in the range of 0.001 to 1.0 wt.%, based on the total weight (total mass) of the molding material mixture (sum of the weights of the components).Mass of components (M1), (M2) and - if present - (M3) and any other components). The aforementioned oxide boron compounds can also be used as a component of component (K1).

[0073] The metal oxides that can be used as or in component (M3) in the process described above according to the invention preferably comprise particulate mixed metal oxides, preferably comprising oxides of aluminum and / or oxides of zirconium. Preferred metal oxides include particulate aluminum oxide, preferably in the alpha phase, and / or particulate aluminum / silicon mixed oxide without a layered silicate structure. The aforementioned metal oxides can be used individually or in combination with one another. Metal oxides suitable for the purposes of the present invention are also specified, for example, in documents DE 102012113074 and DE 102012113073. Preferably, the metal oxide(s) are used in an amount in the range of 0.05 to 8.0 wt.%, based on the total weight (total mass) of the molding material mixture (sum of the weights or masses of components (M1), (M2) and - if present - (M3) and optionally further components).

[0074] The lubricants that can be used as or in component (M3) in the above-described process according to the invention are preferably selected from graphite and / or molybdenum(IV) sulfide. The lubricants mentioned can be used individually or in combination with one another. Suitable lubricants for the purposes of the present invention are also specified, for example, in document WO 2014 / 202042. Preferably, the lubricant(s) are used in an amount in the range of 0.01 to 0.2 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2) and – if present – ​​(M3) and optionally further components).

[0075] The silanes that can be used as or in component (M3) in the above-described process according to the invention are preferably selected from the group consisting of aminosilanes, epoxysilanes, mercaptosilanes, hydroxysilanes, and ureidosilanes. The aforementioned silanes can also act as lubricants. The silanes mentioned can be used individually or in combination with one another. Silanes suitable for the purposes of the present invention are also specified, for example, in document WO 2014 / 202042. Preferably, the silane(s) are used in an amount in the range of 0.1 to 2.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2), and—if present—(M3), and optionally other components).

[0076] The release agents that can be used as or in component (M3) in the above-described process according to the invention are preferably selected from the group consisting of calcium stearate, fatty acid esters, waxes, natural resins, and alkyd resins. These release agents can be used individually or in combination with one another. Release agents suitable for the purposes of the present invention are also specified, for example, in document EP 1802409. Preferably, the release agent(s) are used in an amount in the range of 0.1 to 2.0 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2), and—if present—(M3), and optionally other components).

[0077] The esters (one or more) that can be used as or in component (M3) in the process described above according to the invention are preferably selected from the group consisting of the intramolecular or intermolecular reaction products of an alcohol and an acid, wherein the alcohol is selected from the group consisting of C1-C8 mono-alcohols, C1-C8 di-alcohols, preferably C2-C8 di-alcohols, and C1-C8 tri-alcohols, preferably C3-C8 tri-alcohols, preferably selected from the group consisting of ethylene glycol, 1,2-propanediol and glycerol, and wherein the acid is selected from the group consisting of organic C1-C8 mono-carboxylic acids, preferably organic C2-C8 mono-carboxylic acids, organic C2-C8 di-carboxylic acids, organic C2-C8 tri-carboxylic acids, preferably organic C3-C8 tri-carboxylic acids, and inorganic acids, preferably selected from the group consisting of formic acid, Acetic acid, propionic acid, lactic acid, oxalic acidSuccinic acid, malonic acid, phosphoric acid, sulfuric acid, boric acid, and carbonic acid, wherein preferably at least one of the esters is propylene carbonate or γ-butyrolactone. The aforementioned esters can be used individually or in combination. Preferably, the ester(s) are used in an amount in the range of up to 0.4 wt.%, more preferably in an amount in the range of 0.01 wt.% to 0.4 wt.%, based on the total weight (total mass) of the molding compound mixture (sum of the weights or masses of components (M1), (M2), and – if present – ​​(M3), and optionally further components).

[0078] The aforementioned one or more components (M3) – particulate amorphous silicon dioxide; barium sulfate; carbohydrates; phosphorus compounds; surfactants; boron oxides; metal oxides; lubricants, esters, and release agents – can be used individually or in combination. The one or more components (M3) can, for example, be added individually or together, preferably together, to the mold base material (M1) and mixed with it. The prepared (premixed) solution or dispersion (M2) can then be added to this premix of components (M1) and (M3) and mixed with it (preferably homogeneously). Alternatively, the further components (K1), (K2a), and (K2b) can be added individually to the premix of components (M1) and (M3), and the resulting molding material mixture can then be mixed (preferably homogeneously).Water-soluble components (M3), preferably the aforementioned surfactant compounds and / or oxidic boron compounds, can be added individually or together to component (K1) or be a component of component (K1).

[0079] Furthermore, a method according to the invention as described above (in particular a method which is referred to above or below as preferred) is also preferred, wherein the first water glass-free solution or dispersion (K2a) and optionally the second water glass-free solution or dispersion (K2b) each comprise lithium hydroxide dissolved in water.

[0080] It is therefore preferred that the first water-glass-free solution or dispersion comprises lithium ions dissolved in water (K2a) or lithium hydroxide dissolved in water. It is also preferred that the second water-glass-free solution or dispersion comprises lithium hydroxide dissolved in water. Lithium hydroxide, in particular lithium hydroxide monohydrate, exhibits a water solubility suitable for the purposes of the present invention. Furthermore, it has been shown in our own experiments that solutions or dispersions (K2a) or (K2b) with excellent storage stability can be produced using lithium hydroxide, in particular lithium hydroxide monohydrate, for the purposes of the present invention. Therefore, lithium hydroxide, and especially lithium hydroxide monohydrate, is preferably used to produce lithium ion-containing components (K2a) or (K2b).

[0081] A preferred method is also one according to the invention as described above (in particular a method according to the invention which is referred to as preferred in this text), wherein the aqueous solution or dispersion comprising water glass (K1) has a pH value in the range of 10.0 to 13.0, preferably in the range of 11.0 to 12.5, and / or (preferably "and") the first water glass-free solution or dispersion comprising lithium ions dissolved in water (K2a) has a pH value in the range of 8.0 to 14.0, preferably in the range of 11.5 to 13.5, and / or (preferably "and") the second water glass-free solution or dispersion comprising lithium ions dissolved in water (K2b) has a pH value in the range of 8.0 to 14.0, preferably in the range of 11.5 to 13.5.

[0082] The invention also relates to a kit for producing a solution or dispersion comprising lithium-containing water glass, at least comprising the following separate components:(K1) an aqueous solution or dispersion comprising water glass, wherein the SiO2 content is in the range of 20 to 34 wt.%, preferably in the range of 25 to 34 wt.%, based on the total mass of the solution or dispersion, wherein optionally the molar modulus SiO2 / M2O is greater than the molar modulus of the lithium-containing water glass to be produced, (K2a) a first water glass-free solution or dispersion comprising lithium ions dissolved in water, wherein the concentration of the lithium ions is in the range of 0.3 to 5.3 mol / L, preferably in the range of 1.0 to 5.0 mol / L, and the total concentration of the lithium, sodium, and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and (K2b) a second water glass-free solution or dispersion containing lithium ions dissolved in waterwherein the concentration of lithium ions is lower than in component (K2a) and is in the range of 0.1 to 5.0 mol / L, particularly preferably in the range of 0.1 to 2.0 mol / L, and the total concentration of lithium, sodium, and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and preferably the total concentration of lithium, sodium, and potassium ions differs from the total concentration of lithium, sodium, and potassium ions in component (K2a) by no more than 20%, preferably by no more than 10%.

[0083] With regard to further preferred embodiments of a kit according to the invention, the explanations given above for the method according to the invention apply accordingly, and vice versa.

[0084] The kit according to the invention described above is suitable and intended for use in the method described above according to the invention.

[0085] The invention also relates to the use of a kit described above according to the invention for producing a molding material mixture or for producing a molding material mixture and a molded body therefrom, wherein the molding material mixture comprises: (M1) a mold base material and (M2) a solution or dispersion comprising lithium-containing water glass having a molar modulus SiO2 / M2O in the range of 1.6 to 3.5, preferably in the range of 1.8 to 3.0, and in which the molar fraction of Li2O to M2O is in the range of 0.05 to 0.60, preferably in the range of 0.1 to 0.4.

[0086] With regard to preferred embodiments of a use according to the invention, the explanations given above for the method and kit according to the invention apply accordingly.

[0087] The invention also relates to a system for use in the inventive method, wherein the system comprises at least: a first storage tank (Z1) containing as a first component an aqueous solution or dispersion (K1) comprising water glass, wherein the SiO₂ content is in the range of 20 to 34 wt.%, preferably in the range of 25 to 34 wt.%, based on the total mass of the solution or dispersion, wherein optionally the molar modulus SiO₂ / M₂O is greater than the molar modulus of the lithium-containing water glass in the molding compound mixture to be produced; a second storage tank (Z2) containing as a second component a first water glass-free solution or dispersion (K2a) comprising lithium ions dissolved in water, wherein ∘ the concentration of the lithium ions is in the range of 0.3 to 5.3 mol / L, preferably in the range of 1.0 to 5.0 mol / L, and ∘ the total concentration of the lithium, sodium, and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 up to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L,preferably a mixing device (Z3), particularly preferably a mixing tube, most preferably a static mixing tube, for mixing at least the first and the second component for the purpose of producing the intermediate solution or dispersion (with reference to the process according to the invention, this intermediate solution or dispersion is referred to as (M2)), and wherein preferably at least the first and the second storage tank are each connected to the mixing device (Z3) by one or more lines (Z4), wherein M2O denotes the total amount of lithium, sodium and potassium oxide, and / or wherein the lithium-containing water glass in the intermediate solution or dispersion has a molar modulus SiO2 / M2O in the range of 1.6 to 3.5, preferably in the range of 1.8 to 3.0, and / or wherein the molar proportion of Li2O to M2O is in the range of 0.05 to 0.60, preferably in the range of 0.1 to 0.4.where M₂O denotes the total amount of lithium, sodium, and potassium oxide, respectively.

[0088] Preferably, the system according to the invention comprises a mixing device (Z3), and preferably at least the first and the second storage tank are each connected to the mixing device (Z3) by one or more lines (Z4). In this preferred embodiment, the system according to the invention is a system for producing an intermediate solution or dispersion comprising lithium-containing water glass (with reference to the process according to the invention, this intermediate solution or dispersion is designated as (M2)) for use in the production of a molding material mixture or for producing a molding material mixture and a molded body therefrom.

[0089] However, the invention also includes a system described above which does not require a mixing device and in which the components (K1), (K2a) and (K2b) are fed directly into the mold base material (M1) and are only mixed there with each other and with the mold base material (M1).

[0090] The mixing unit (Z3) can simultaneously be a storage tank ((Z1), (Z2) or (Z5), see below). The contents of the storage tank(s) can be pumped to the mixing unit by means of one or more pumps.

[0091] With regard to preferred embodiments of a system according to the invention, the explanations given above for the method, kit and use according to the invention apply accordingly, and vice versa.

[0092] The apparatus according to the invention described above or below is suitable and intended for use in the method described above according to the invention.

[0093] The kit according to the invention described above is suitable and intended for use in the plant described above or below.

[0094] The system according to the invention further comprises a third storage tank (Z5) containing a second water glass-free solution or dispersion (K2b) comprising lithium ions dissolved in water, wherein: o the concentration of the lithium ions is lower than in component (K2a) and preferably in the range of 0.1 to 5.0 mol / L, particularly preferably in the range of 0.1 to 2.0 mol / L, and o the total concentration of the lithium, sodium, and potassium ions is in the range of 0.3 to 28.0 mol / L, preferably in the range of 0.3 to 20.0 mol / L, particularly preferably in the range of 1.0 to 10.0 mol / L, and o preferably the total concentration of the lithium, sodium, and potassium ions differs from the total concentration of the lithium, sodium, and potassium ions in component (K2a) by no more than 20%, preferably by no more than 10%. wherein preferably the mixing device (Z3) is configured to mix at least the first, second and third components for the purpose of producing the intermediate solution or dispersion, and wherein preferably at least the first, second and third storage tank are each connected to the mixing device (Z3) by one or more lines (Z4).

[0095] The invention is described in more detail in the examples given below and with reference to the figures below. Figures:

[0096] Fig. 1: Fig 1 Figure 1 shows a schematic diagram of a section of a system according to the invention with the system components: a first storage tank (Z1), a second storage tank (Z2), a mixing device (Z3) and one or more (here: several) lines (Z4) which connect the first and the second storage tank to the mixing device. Fig. 2: Fig 2Figure 1 shows a schematic diagram of a section of a system according to the invention with the system components: a first storage tank (Z1), a second storage tank (Z2), a mixing device (Z3) (here identical to the first storage tank (Z1)) and one or more (here: one) lines (Z4) which connect the first and the second storage tank to the mixing device (where the first storage tank and the mixing device are identical). Fig. 3: Fig 3 Figure 1 shows a schematic diagram of a section of a system according to the invention with the system components: a first storage tank (Z1), a second storage tank (Z2), a third storage tank (Z5), a mixing device (Z3) and one or more (here: several) lines (Z4) which connect the first, the second and the third storage tank to the mixing device. Examples:

[0097] The examples are intended to describe and explain the invention in more detail without limiting its scope of protection.

[0098] Unless otherwise stated, work was carried out under standard laboratory conditions (25 °C, normal pressure). Example 1a: Exemplary components (K1), (K2a) and (K2b)

[0099] Exemplary components (K1), (K2a) and (K2b) were produced in a manner known per se, with the properties shown in Table 1a. Table 1a: Exemplary components (K1), (K2a) and (K2b) ingredient Component (K1) Component (K2a) Component (K2b) Molar modulus SiO₂ / M₂O 2,7 n / a n / a Solids content [wt.%] 41 14 22 SiO2 content [wt.%] 29 0 0 c (Li +< ) [mol / L] 0 2,4 0,3 c (Li +< / Na +< / K +< ) [mol / L] n / a 3,0 3,0

[0100] In Table 1a, "c (Li +< )" indicates the concentration of lithium ions, and "c (Li' / Na' / K')" indicates the total concentration of lithium, sodium, and potassium ions. "kA" means that no value is given for the respective cell. The values ​​given as "wt.%" refer to the total mass of the corresponding component (K1), (K2a), or (K2b). Example 1b: Determination of the pH value in components (K1), (K2a) and (K2b)

[0101] Preferred components (K1), (K2a) and (K2b) were prepared using a known method. The pH values ​​of the preferred components were then determined using a known method. The results are given below in Table 1b: Table 1b: pH values ​​of preferred components (K1), (K2a) and (K2b) ingredient Component (K1) Component (K2a) Component (K2b) PH value: 11,6 12,0 13,5

[0102] The other properties of the preferred components (K1), (K2a) and (K2b) are very similar to those in Table 1a; there are no significant deviations. Example 2: Production of solutions or dispersions according to the invention comprising lithium-containing water glass

[0103] Exemplary solutions or dispersions (M2) comprising lithium-containing water glass are prepared by mixing components (K1), (K2a) and, according to the inventive method, (K2b) together in a manner known per se. The components specified in Example 1 are used in each case. For this purpose, the respective proportion of component (K1) is placed first, and the respective proportion of components (K2a) and, optionally, (K2b) are added. The resulting solutions or dispersions (M2) are homogenized by shaking or stirring. The results are given in Table 2. Table 2: Composition of solutions or dispersions (M2) produced according to the invention (experiments 2-4) and not according to the invention (experiment 1) comprising lithium-containing water glass Composition (M2) Molar modulus SiO₂ / M₂O Solids content [wt.%] SiO2 content [wt.%] Molar fraction of Li₂O in M₂O Attempt 1: 2,3 38 26 0,11 (K1): 90 wt.% (K2a): 10 wt.% Attempt 2: 2,3 39 26 0,07 (K1): 90 wt.% (K2a): 6 wt.% (K2b): 4 wt.% Attempt 3: 2,2 37 25 0,11 (K1): 85 wt.% (K2a): 10 wt.% (K2b): 5 wt.% Attempt 4: 2,2 37 25 0,14 (K1): 85 wt.% (K2a): 13 wt.% (K2b): 2 wt.% Example 3: Production of molding compound mixtures

[0104] Molding material mixtures (EF1 to EF3) were produced from the components listed in Table 4 according to the inventive method, as well as a comparative molding material mixture (VF1) according to a conventional, non-inventive method, in accordance with the operating procedure given below. All quantities in Table 4 are given in parts by weight.

[0105] The solutions or dispersions according to the invention, comprising lithium-containing water glass (M2) or the non-inventive solution or dispersion (M2v) prepared according to Table 3 (see binders EL1 to EL3 and VL1) were used as "binders" (see Table 4). Quartz sand (H31 from Quarzwerke GmbH, Frechen) was used as the "mold base material" (M1) in each case. The commercially available powdered additive for foundry molds, Anorgit® < 8610 (Hüttenes-Albertus Chemische Werke Gesellschaft mit beschränkter Haftung), which contains, among other things, particulate amorphous silicon dioxide, was used as the "additive" in each case. Table 3: Composition of prepared solutions or dispersions according to the invention (M2) and comparison solution (M2v) Composition (M2) or (M2v) Molar modulus SiO₂ / M₂O Solids content [wt.%] SiO2 content [wt.%] Molar fraction of Li₂O in M₂O EL1 (M2) 2,3 38 26 0,06 EL2 (M2) 2,2 38 26 0,08 EL3 (M2) 2,3 38 26 0,12 VL1 (M2v) 2,4 37 26 0 Table 4: Composition of the molding material mixtures Attempt Molding base material [weight parts] Binder / [parts by weight] Additive [parts by weight] EF1 100 EL1 / (2,2) 1,3 EF2 100 EL2 / (2,2) 1,3 EF3 100 EL3 / (2,2) 1,3 VF1 100 VL1 / (2,2) 1,3

[0106] The components of the molding compound mixture were mixed in a laboratory paddle mixer (Multiserw). First, the quartz sand was added, followed by the powdered additive. Then, the premixed binder (see Table 3) was added. The mixture was then stirred for a total of two minutes. The resulting molding compound mixtures were then used for the subsequent tests. Example 4: Production of molded bodies

[0107] From the molding material mixtures produced in Example 3 (see Table 4), molded specimens (test specimens, i.e., standard bending bars with dimensions 22.4 mm x 22.4 mm x 165 mm) were produced using a heated mold for the production of bending bars (as specified in leaflet M11 of the Association of German Foundry Experts from March 1974). These specimens were then used for the following tests: The molding material mixtures were injected into the mold (core temperature 180 °C) using compressed air (4 bar). The injection time was 3 s, followed by a curing time of 30 s (retarding time 3 s). To accelerate the curing of the mixtures, hot air (2 bar gas pressure, 180 °C gas and gas hose temperature) was passed through the mold during the 30 s curing time.

[0108] The manufactured test specimens represent shaped bodies and, as is common in the relevant field, serve as models for shaped bodies such as molds or cores that can be used in the foundry industry. Example 5: Investigation of the storage stability of molded parts

[0109] The storage stability of water glass-bonded molded parts depends on environmental conditions, especially humidity. The higher the humidity, the greater the risk of damage to the molded part (e.g., core damage). Damage to the molded part manifests itself, for example, as component failure (e.g., core breakage) or a significant decrease in strength (low residual strength relative to cold strength). High humidity also leads to water absorption, which can cause gas defects during casting (e.g., gas bubbles in the casting).

[0110] The tests were carried out under defined conditions (temperature and relative humidity), each monitored using a data logger. The molded parts (test specimens) are characterized in Table 5 (see column "Test") by the molding material mixtures used for their production (see Example 3 and Table 3). 5.1. Determining the time until component failure

[0111] To determine the time until component failure (breakage of the test specimen), the test specimens were stored in a climate chamber and the time until breakage was observed. The respective times in hours are given in Table 5 as the mean of 3 measurements. 5.2. Determination of the residual strength of test specimens

[0112] To determine the residual strength, the test specimens were stored in a climate chamber for specific durations (see Table 5). The flexural strengths were then measured immediately after removal from the climate chamber.

[0113] To determine the flexural strengths, the test specimens produced in Example 4 were placed in a Georg Fischer strength testing machine equipped with a 3-point bending device (Multiserw company), and the force that caused the test specimens to break was measured. The flexural strengths were measured after the time intervals specified in Table 5. The molded parts (test specimens) are characterized in Table 5 (see column "Test") by the molding material mixtures used for their production (see Example 3 and Table 4).

[0114] The measured values ​​obtained (residual strengths given in % of the initial value) are shown in Table 5 as the mean of 3 measurements each. 5.3 Determination of the water absorption of test specimens

[0115] To determine water absorption, the test specimens were weighed one hour after removal from the mold and then stored in a climate chamber for a specific period (see Table 5). Immediately after removal from the climate chamber, the test specimens were weighed again. The resulting weight (or mass) differences, expressed as a percentage, are shown in Table 5 as the mean of three measurements. Table 5: Storage stability of molded parts Test (test specimen) Time until component failure [h] Residual strength at 35 °C, 79% rH, (31.3 g / m 3< ) / [%] Water absorption after 24 h [%] 35 °C, 79% RH, (31.3 g / m 3< ) 35 °C, 90% RH, (35.7 g / m 3< ) After 4 hours After 7 hours 25 °C, 64% RH, (14.7 g / m 3< ) 35 °C, 63% RH, (25.0 g / m 3< ) EF1 12,9 5,8 66 39 nb nb EF2 18,5 7,4 72 49 0,12 0,14 EF3 25,8 9,4 78 68 0,08 0,12 VF1 6,4 2,9 30 0 0,21 0,22

[0116] In Table 5, "rLF" indicates relative humidity and "nb" means "not determined" (i.e., no measurement was taken). The values ​​"31.3 g / m³<", "35.3 g / m³<", "14.7 g / m³<", and "25.0 g / m³<" each indicate absolute humidity.

[0117] The measured values ​​in Table 5 show that the molded parts (test specimens EF1, EF2, and EF3) produced according to a method according to the invention using lithium-containing water glass exhibit better storage stability than a comparison test specimen (VF1) produced according to a non-inventive method (without lithium). Molded parts produced according to the invention showed better storage life (see Table 5, column "Time to component failure"), higher residual strength after storage (see Table 5, column "Residual strength at 35 °C"), and lower water absorption (see Table 5, column "Water absorption") than a comparison molded part produced according to the non-inventive method.

[0118] Table 5 further shows that with increasing lithium ion content (M2) of the solutions or dispersions used to produce the molded parts within the specified range, the observed properties of storage stability (higher), residual strength (higher), and water absorption (lower) of the molded parts improved. Higher water absorption of the molded part generally increases the risk of gas evolution during the casting process and thus a reduction in the quality of the casting due to the inclusion of gas bubbles.

[0119] From these observations, it can be concluded that – depending on the prevailing climatic conditions (in particular ambient temperature and relative or absolute humidity) – at the place of use of the inventive method, kit, or system, a correspondingly flexibly adjustable lithium ion concentration in a solution or dispersion (M2) to be produced (as is possible with the inventive method or kit) is advantageous because it allows the desired properties of molded parts, in particular the desired storage properties of molded parts bound with binders, to be specifically controlled or adjusted: If, for example, the relevant climatic conditions do not require this, i.e.,Provided that less demanding relevant climatic conditions prevail, particularly lower humidity, the lithium ion content in the solution or dispersion (M2) can be reduced, resulting in cost savings. These cost savings have become even more significant recently, as lithium compounds have become considerably more expensive, primarily due to increased demand in the battery industry. 5.4. Influence of the storage duration of a solution or dispersion (M2) on the storage stability of molded parts

[0120] Components (K1), (K2a) and (K2b) of a solution or dispersion (M2) were used and mixed with each other or with each other and with the mold base material (M1) in the ways specified below and under otherwise constant conditions according to a method according to the invention: a) Components (K1), (K2a), and (K2b) were mixed directly with the mold base material without premixing. b) Components (K1), (K2a), and (K2b) were premixed, and the premix was then mixed directly with the mold base material. c) Components (K1), (K2a), and (K2b) were premixed, and the premix was mixed with the mold base material one day after its production. d) Components (K1), (K2a), and (K2b) were premixed, and the premix was mixed with the mold base material two days after its production. e) Components (K1), (K2a), and (K2b) were premixed, and the premix was mixed with the mold base material three days after its production.

[0121] From the molding material mixtures a) to e) obtained above, molded bodies (test specimens, see Example 4) were then produced as above and examined for their storage stability ("time until component failure", see Example 5.1).

[0122] No significant differences were found in the measurement of the storage stability of molded bodies (test specimens) produced according to the inventive method with the molding material mixtures a) to e) specified above.

[0123] From this result it can be concluded that the solutions or dispersions (M2) produced according to the inventive method can be stored under the test conditions for at least three days without causing any practically relevant impairment of quality. Example 6: Investigation of the storage stability of solutions or dispersions (M2)

[0124] Samples of the solution or dispersion (M2) produced in Example 3, designated "EL3", were stored in closed containers under the conditions specified in Table 6, and their quality or consistency was determined by visual inspection at the times specified in Table 6, with the results also given in Table 6: Table 6: Storage stability of a solution or dispersion (M2) Temperature [°C] 1 day 1.5 days 3 days 6 days 8 days 20 ++ ++ ++ + ○ 25 ++ ++ ++ + ○ 30 ++ ++ + ○ ○ 50 ++ + ○ - -

[0125] In Table 6, the entries "++" mean: no change in the solution or dispersion (M2) detectable; "+": slight change in the solution or dispersion (M2) detectable, no impairment of quality; "o": slight gel formation detectable, solution or dispersion (M2) still usable without impairment; "-": significant precipitation detectable, solution or dispersion (M2) no longer usable without impairment (e.g. in pumps, filters, dosing units).

[0126] The results above show that a solution or dispersion (M2) produced according to the inventive method could be used for the production of molded parts for the foundry industry even under unfavorable storage conditions for up to 8 days (preferably up to 7 days) without any practically relevant impairment of quality.

[0127] As can also be seen from Table 6, manufactured solutions or dispersions (M2) with a favorable (high) lithium content can therefore be premixed and stored for short-term and, at most, medium-term storage and used in industrial practice. However, for the reasons mentioned above, homogeneous (e.g., premixed) solutions or dispersions (M2) with a favorable (high) lithium content are not suitable for long-term storage (e.g., for several weeks).

[0128] According to the subject matter of the present invention, such solutions or dispersions (M2) with an advantageous (high) lithium content should therefore only be mixed in the short or medium term before actual industrial use by mixing separately stored components (K1), (K2a) and (K2b) with each other, or with a molding base material to form a molding material mixture.

Claims

1. Method for producing a moulding material mixture, wherein the moulding material mixture comprises: (M1) a mould base material and (M2) a solution or dispersion comprising lithium-containing waterglass, which possesses a molar SiO2 / M2O modulus in the range from 1.6 to 3.5, and in which the molar fraction of the Li2O within M2O is in the range from 0.05 to 0.60, comprising the following steps: (1) producing or providing a kit at least comprising the following separate components: (K1) an aqueous solution or dispersion comprising waterglass, where the SiO2 content is in the range from 20 to 34 wt%, based on the total mass of the solution or dispersion, (K2a) a first waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is in the range from 0.3 to 5.3 mol / L and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, and (K2b) a second waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is lower than in component (K2a), and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, and thereafter (2) producing a mixture of the mould base material (M1) with a fraction of component (K1) and also with a fraction of component (K2a) and with a fraction of component (K2b), where the solution or dispersion (M2) is formed by mixing together the components of the kit that are used, where M2O denotes in each case the total amount of lithium oxide, sodium oxide and potassium oxide.

2. Method according to Claim 1, where the moulding material mixture comprises: (M1) a mould base material and (M2) a solution or dispersion comprising lithium-containing waterglass, which possesses a molar SiO2 / M2O modulus in the range from 1.6 to 3.5, preferably in the range from 1.8 to 3.0, and in which the molar fraction of the Li2O within M2O is in the range from 0.05 to 0.60, preferably in the range from 0.1 to 0.4, comprising the following steps: (1) producing or providing a kit at least comprising the following separate components: (K1) an aqueous solution or dispersion comprising waterglass, where the SiO2 content is in the range from 20 to 34 wt%, preferably in the range from 25 to 34 wt%, based on the total mass of the solution or dispersion, (K2a) a first waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is in the range from 0.3 to 5.3 mol / L, preferably in the range from 1.0 to 5.0 mol / L and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, preferably in the range from 0.3 to 20.0 mol / L, more preferably in the range from 1.0 to 10.0 mol / L, and (K2b) a second waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is lower than in component (K2a) and is in the range from 0.1 to 5.0 mol / L, more preferably in the range from 0.1 to 2.0 mol / L, and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, preferably in the range from 0.3 to 20.0 mol / L, more preferably in the range from 1.0 to 10.0 mol / L, and preferably the total concentration of the lithium, sodium and potassium ions differs by not more than 20%, preferably by not more than 10%, from the total concentration of the lithium, sodium and potassium ions in component (K2a), and thereafter (2) producing a mixture of the mould base material (M1) with a fraction of component (K1) and also with a fraction of component (K2a) and with a fraction of component (K2b), where the solution or dispersion (M2) is formed by mixing together the components of the kit that are used, where M2O denotes in each case the total amount of lithium oxide, sodium oxide and potassium oxide.

3. Method according to any of the preceding claims for producing a moulding material mixture and a moulding therefrom, comprising the additional steps of - establishing, determining or estimating one or more parameters selected from the group consisting of ambient temperature during the production of the moulding, relative humidity during the production of the moulding, temperature during the storage of the moulding, relative humidity during the storage of the moulding, absolute humidity during the production of the moulding, absolute humidity during the storage of the moulding, and storage duration of the moulding, and - controlling the fractions to be used of components (K2a) and (K2b) as a function of the established, determined or estimated parameter or parameters selected from the group consisting of ambient temperature during the production of the moulding, relative humidity during the production of the moulding, temperature during the storage of the moulding, relative humidity during the storage of the moulding, absolute humidity during the production of the moulding, absolute humidity during the storage of the moulding, and storage duration of the moulding, and / or where the method is embodied as at least partial serial fabrication of a number of mouldings, where, in the case of increase or expected increase in one or more parameters selected from the group consisting of ambient temperature during the production of the moulding, relative humidity during the production of the moulding, temperature during the storage of the moulding, relative humidity during the storage of the moulding, absolute humidity during the production of the moulding, absolute humidity during the storage of the moulding, and storage duration of the moulding, - the fractions that are used of component (K2a) are increased for the fabrication of the mouldings and / or - the molar fraction of the Li2O within M2O in the solution or dispersion (M2) is increased for the fabrication of the mouldings.

4. Method according to Claim 3, where, for establishing, determining or estimating the one or more parameters selected from the group consisting of ambient temperature during the production of the moulding, relative humidity during the production of the moulding, temperature during the storage of the moulding, relative humidity during the storage of the moulding, absolute humidity during the production of the moulding, absolute humidity during the storage of the moulding, and storage duration of the moulding, a data capture facility or data processing facility is provided and to control the fractions that are to be used of components (K2a) and (K2b) as a function of the established, determined or estimated parameter or parameters, a control facility is provided, where preferably, between the data capture facility or the data processing facility and the control facility, a data connection is set up to transfer parameter data.

5. Method according to any of the preceding claims, where, during production of the moulding material mixture, one or more constituents are additionally added which are selected from the group consisting of: (M3) particulate, amorphous silicon dioxide; barium sulfate; carbohydrates; phosphorus compounds; surface-active compounds; oxidic boron compounds; metal oxides; lubricants, esters and release agents.

6. Method according to any of the preceding claims, where the first waterglass-free solution or dispersion (K2a) and optionally the second waterglass-free solution or dispersion (K2b) in each case comprise lithium hydroxide in solution in water.

7. Method according to any of the preceding claims, where - the aqueous solution or dispersion comprising waterglass (K1) has a pH in the range from 10.0 to 13.0, preferably in the range from 11.0 to 12.5, and / or - the first waterglass-free solution or dispersion comprising lithium ions in solution in water (K2a) has a pH in the range from 8.0 to 14.0, preferably in the range from 11.5 to 13.5, and / or - the second waterglass-free solution or dispersion comprising lithium ions in solution in water (K2b) has a pH in the range from 8.0 to 14.0, preferably in the range from 11.5 to 13.5.

8. Method according to any of the preceding claims, where in step (2) first, in the absence of the mould base material, a solution or dispersion (M2) is formed by mixing together the components of the kit that are used, and thereafter a mixture of the or a fraction of the mould base material (M1) with a fraction or the total amount of the resulting solution or dispersion (M2) is formed and / or where the solution or dispersion (M2) used for the forming of the mixture with the mould base material (M1) contains no visible precipitates or gel fractions.

9. Method according to Claim 8, where the components of the kit that are used are mixed together to form the solution or dispersion (M2) in a mixing facility, where preferably the mixing facility is a metering vessel or a mixing pipe and is more preferably a mixing pipe, very preferably a static mixing pipe.

10. Method according to Claim 9, where the fraction or the total amount of the solution or dispersion (M2) formed, before the forming of a mixture with the or a fraction of the mould base material (M1), is stored for a period of not more than 7 days, preferably of not more than 3 days, more preferably of not more than 2 days, in the mixing facility.

11. Kit for producing a solution or dispersion comprising lithium-containing waterglass, at least comprising the following separate components: (K1) an aqueous solution or dispersion comprising waterglass, where the SiO2 content is in the range from 20 to 34 wt%, based on the total mass of the solution or dispersion, and (K2a) a first waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is in the range from 0.3 to 5.3 mol / L and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, characterized in that the kit additionally comprises as a further separate component: (K2b) a second waterglass-free solution or dispersion comprising lithium ions in solution in water, where the concentration of the lithium ions is lower than in component (K2a) and is in the range from 0.1 to 5.0 mol / L, more preferably in the range from 0.1 to 2.0 mol / L, and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, preferably in the range from 0.3 to 20.0 mol / L, more preferably in the range from 1.0 to 10.0 mol / L, and preferably the total concentration of the lithium, sodium and potassium ions differs by not more than 20%, preferably by not more than 10%, from the total concentration of the lithium, sodium and potassium ions in component (K2a).

12. Use of a kit according to Claim 11 for producing a moulding material mixture or for producing a moulding material mixture and a moulding therefrom, where the moulding material mixture comprises: (M1) a mould base material and (M2) a solution or dispersion comprising lithium-containing waterglass, which possesses a molar SiO2 / M2O modulus in the range from 1.6 to 3.5, and in which the molar fraction of the Li2O within M2O is in the range from 0.05 to 0.60.

13. Installation for use in a method according to any of Claims 1 to 10, - where the installation at least comprises: - a first storage tank (Z1), containing as first component an aqueous solution or dispersion (K1) comprising waterglass, where the SiO2 content is in the range from 20 to 34 wt%, based on the total mass of the solution or dispersion, - a second storage tank (Z2), containing as second component a first waterglass-free solution or dispersion (K2a), comprising lithium ions in solution in water, where ∘ the concentration of the lithium ions is in the range from 0.3 to 5.3 mol / L and ∘ the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, - preferably a mixing facility (Z3), more preferably a mixing pipe, for mixing at least the first and the second components to produce an intermediate solution or dispersion, where M2O denotes in each case the total amount of lithium oxide, sodium oxide and potassium oxide, and further comprising a third storage tank (Z5), containing a second waterglass-free solution or dispersion (K2b) comprising alkali metal ions in solution in water, where ∘ the concentration of the lithium ions is lower than in component (K2a) and is in the range from 0.1 to 5.0 mol / L, more preferably in the range from 0.1 to 2.0 mol / L, and ∘ the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 to 28.0 mol / L, preferably in the range from 0.3 to 20.0 mol / L, more preferably in the range from 1.0 to 10.0 mol / L, and o preferably the total concentration of the lithium, sodium and potassium ions differs by not more than 20%, preferably by not more than 10%, from the total concentration of the lithium, sodium and potassium ions in component (K2a), where preferably the mixing facility (Z3) is embodied for mixing at least the first, second and third components, to produce the intermediate solution or dispersion, and where preferably at least the first, the second and the third storage tank are connected to the mixing facility (Z3) in each case by one or more lines (Z4).

14. Installation according to Claim 13, where the lithium-containing waterglass in the intermediate solution or dispersion possesses a molar SiO2 / M2O modulus in the range from 1.6 to 3.5 and / or in which the molar fraction of the Li2O within M2O is in the range from 0.05 to 0.60, where M2O denotes in each case the total amount of lithium oxide, sodium oxide and potassium oxide.