Composite material moulded part comprising a composite material moulded part core having granular moulding material, method for manufacturing same, and use thereof

Abstract

The invention relates to a composite material moulded part core comprising a particulate material and an at least partially cured binder which bonds particles of the particulate material together. The composite material moulded part core is characterised by the fact that a mass fraction of the at least partially cured binder is ≤ 15 percent by mass. The invention also relates to a method for manufacturing a composite material and to a moulded part comprising such a composite material moulded part core.

Description

[0001] ISG- Industriestein Gesellschaft GmbH & Co KG Scharhof 1 92242 Hirschau

[0002] Composite molded part with composite molded part core comprising granular molding material, process for its production and its use

[0003] Description

[0004] The present invention relates to a composite molded part core comprising a particulate material and an at least partially cured binder that bonds particles of the particulate material together. Furthermore, the invention relates to a method for producing a composite material, a method for recycling a composite molded part core, and a molded part comprising such a composite molded part core.

[0005] Molded parts made of a granular material, such as sand, are known from the prior art. In such molded parts, the granular material is fixed by a binding agent, so that the molded part permanently retains its shape. The desired shape is achieved by filling a molding compound into a negative mold and allowing it to (at least partially) harden therein. Such molded parts are used in a wide variety of applications. Of particular importance are applications in the kitchen and sanitary sector, for example, in the form of washbasins, sinks, shower trays, and bathtubs.

[0006] Numerous intellectual property rights exist for such molded parts. Reference is made to the publications DE 3832351 A1, DE 4040 602 A1, DE 44 07 321 A1, DE 4410526 A1, and DE 199 20 719 A1, for example.

[0007] The intellectual property rights mentioned above as examples describe positive properties of various sands as well as various fillers, various binders, additives and pigments, as well as various manufacturing processes and / or various molded part geometries.

[0008] Molded parts of this type have the advantage of being virtually unlimited in their geometry due to the small size of the sand grains and their variable arrangement relative to each other. This allows washbasins, sinks, shower trays, and bathtubs to be manufactured in geometric shapes that are impossible to realize using other techniques.

[0009] A variety of particulate fillers are known from the state of the art. A typical average particle size of the filler is in the range of 1 μm to 3 mm. Known fillers include oxides, silicates, phosphates, carbonates, sulfates, glasses, as well as ceramics and amorphous materials. These particles can originate from a natural source, be specifically manufactured, or be obtained from a recycling process.

[0010] For example, this recycled material can consist of crushed polymer-bonded kitchen sinks, wash basins, shower trays, or bathtubs based on, for example, quartz, ATH, or carbonates as described above. The polymer used in these materials is, for example, polyester- or acrylic-based.

[0011] In the effort to produce products in the most resource-efficient and sustainable way possible, organic fillers based on renewable raw materials are increasingly being used. These include, for example, nutshells or olive pits, which are used, for example, as flour or as particles ground to a specific grain size.

[0012] However, quartz sand continues to be used predominantly for the production of such molded parts. The average grain size d50 (sieve analysis or laser diffraction) of the sand particles used is typically in the range of approximately 0.1 - 1.0 mm. The sand can be natural or colored. If coloring of the molded part is desired even with uncolored sand, the binder preparation used can be mixed with organic and / or inorganic pigments.

[0013] Optionally, additional components can be added to the molding compound. Examples of such additives include fine particulate materials such as quartz powder. Other minerals, particles of various grain sizes, or powders can also be used. Furthermore, the use of so-called organic and / or inorganic rheology additives is known. One example of such a rheology additive is fine glass beads.

[0014] It is also known that fibers can be added to the molding compound. These serve both to reduce weight and to stabilize and increase strength. This can, in particular, reduce waste due to breakage.

[0015] Most of the known processes have in common that the particulate components are mixed with a) a resin (syrup) made of polymethyl methacrylate (PMMA) and / or methyl methacrylate (methyl methacrylate, MMA) and cured in molded parts under certain pressure and temperature or b) are cast with polyester (precursors) in casting machines to form molded parts and cured.

[0016] The polyester used in b) can optionally also contain a certain amount of MMA. There is also currently an effort to obtain the polymers used from renewable raw materials. Examples of molding compounds with polymers or binders based on renewable raw materials are known.

[0017] A major disadvantage of these processes is that the composition from which the molded part is created after the binder has cured always has a resin content of >25 wt%. Frequently, the binder content is even >35 wt%. Since the binder is significantly more expensive—especially compared to sand—such molded parts are comparatively expensive. This is further exacerbated when binders based on renewable raw materials are used, which are even more expensive. However, this is increasingly desired in order to be able to produce molded parts more sustainably and to market them accordingly.

[0018] Even though molded parts are typically used for several years, the disadvantage is that at the end of their useful life, they cannot be recycled, or can only be recycled with great difficulty. Due in particular to the high polymer / binder content, reusing the sand with binder residues remaining on the individual grains is not possible, or only possible to a very limited extent. This disadvantage cannot be eliminated even by using binders from renewable sources.

[0019] The technology described above is nevertheless widespread. Possible reasons include the automation of the manufacturing process and the ability to quickly produce molded parts in large quantities. If acrylic resin is used as the binder, the required molds are somewhat more expensive to manufacture, but they are more durable than corresponding molds for molding compounds with a polyester-based binder. Therefore, molding compounds with a polyester-based binder are used especially when certain geometries are to be produced in relatively small quantities, for example, in small series.

[0020] However, both types of molded parts are generally considered to be mechanically very stable and visually and tactilely very appealing. They are also very hard, climate- and moisture-resistant, chemically and thermally stable, impact- and scratch-resistant, break-resistant, and colorfast, and can even withstand constant temperature fluctuations, such as those encountered in kitchen sinks. Due to these advantages, the number of units produced, and thus the revenue generated with such products, has increased significantly for both technologies in recent years. Millions of molded parts are launched worldwide every year.

[0021] To meet the demand for customized geometries, such molded parts have also been manufactured using 3D printing for a few years now. The materials used and applicable are essentially those mentioned above, plus furan or phenolic resin binders or inorganic binders, as well as a near-surface epoxy resin impregnation, which also acts as a binder, usually followed by a mechanical surface treatment with a final coating. This technology offers an extremely wide design variety with regard to the three-dimensional structure, but compared to the standard process described above, it is characterized as very slow due to the significantly lower number of parts per unit of time and, as mentioned above, very complex in post-processing. Accordingly, molded parts produced in this way are expensive and only available in comparatively small quantities.Even though the machines used are of the highest technological standard, such molds are primarily used in areas where small quantities are required and / or in manufacturing operations. This applies regardless of whether these molded parts are used as kitchen sinks or as washbasins, shower trays, or bathtubs in the sanitary sector.

[0022] The challenge, therefore, is to provide molded parts that can be manufactured in high quantities at a sufficient quality and at a reasonable price. In terms of possible geometries, they should be as flexible as possible, as conventional molded parts produced in large quantities. Furthermore, the molded parts should be as inexpensive as possible and available in a wide range of colors. Furthermore, they should be as easily recyclable as possible than conventional molded parts.

[0023] This object is achieved by a composite molded part core comprising a particulate material and an at least partially cured binder that bonds particles of the particulate material together. Such a composite molded part core is characterized in particular by the fact that the mass fraction of the at least partially cured binder is <15 mass percent.

[0024] Preferably, at least one surface of the composite molded part core is covered, at least in sections, by a composite molded part shell. This allows the composite molded part core to be protected, for example, from mechanical and / or thermal stress or the undesired penetration of liquid. In particular, it is preferred that all surfaces of the composite molded part core are covered, at least in sections, by a composite molded part shell, i.e., the composite molded part core is completely enclosed by a composite molded part shell.

[0025] Surprisingly, it has been found that such a composite molded part core is sufficiently stable to form a composite molded part core for a molded part according to an embodiment of the present invention. The binder content is usually very low—at least compared to the composite materials described in the prior art—and is below 15 percent by mass, usually even significantly lower, preferably <12 percent by mass, preferably <10 percent by mass, more preferably <8 percent by mass, most preferably <5 percent by mass.

[0026] Any information on the binder content preferably refers (throughout the description of the invention) to the mass fraction of the polymer used and / or the polymer precursor in one or more (uncured) precursors, for example a molding compound(s), as provided before the molding process.

[0027] In a preferred embodiment, the binder content in the composite molded part core is so low that - for example, after applying a composite molded part shell and / or impregnation - the mass fraction of all binders and coating agents used in the entire composite molded part is still < 25 mass percent, preferably < 22 mass percent, preferably < 20 mass percent, more preferably < 18 mass percent, most preferably < 15 mass percent. These figures preferably relate to the mass fraction of the polymer used, or the sum of the polymers or polymer precursors used, in the total mass of all compositions used to produce the composite molded part, i.e., in particular, the compositions used to produce the composite molded part core and optionally the composite molded part shell.

[0028] In one variant, the composite molded part shell can be additionally provided with one or more topcoats, which may also contain a polymer component. In this case, their polymer components are also included in the aforementioned < 25 mass percent total polymer content (based on a composite molded part).

[0029] It should be noted that all binders / polymers used in the composite molded part can be different and, in a preferred embodiment, are different. Preferably, the binder used for the composite molded part core differs from the one used to form the composite molded part shell.

[0030] In the context of this invention, the molding compound is understood to be the composition used to form the composite molded part core.

[0031] In the context of this invention, all percentages - unless explicitly stated otherwise - are to be understood as percentages by mass.

[0032] In the context of this invention, all information regarding grain size - unless explicitly stated otherwise - should be understood as the average grain size dso. Any information regarding grain size (i.e., for example ds, d , dso, dgo, dgs or others) should be understood - unless explicitly stated otherwise - as determined by sieve analysis and / or laser diffraction. Whether the (average) grain size is to be determined by sieve analysis or laser diffraction depends essentially on the expected average grain size dso: A person skilled in the art knows that sieve analysis is suitable for determining the size of larger (average) grain sizes, whereas laser diffraction is suitable for determining the size of smaller (average) grain sizes. In a preferred embodiment of a composite molded part core, the binding ability of the at least partially cured binder can be reduced by means of an activator.The activator is preferably a temperature application or reagent application, by which a chemical and / or physical reaction can be triggered in or with the binder, by which the composite molded part core itself or the binder can be converted into a subsequent product with reduced binding capacity.

[0033] A composite mold core therefore preferably has the further advantage that the composite mold core can disintegrate when exposed to temperature. Such a property is known, for example, from the field of metal casting. There, such thermally induced disintegration of a casting mold or casting mold core is often provided for, since such a casting mold or casting mold core can disintegrate due to the high temperature of the poured material and the long exposure to temperature. This has the advantage that its residues can be easily removed from the cooled casting. Furthermore, it allows the sand used for the casting mold or casting mold core to be recycled (sand). This helps keep sand costs low. This recycled sand is usually reused in the foundry to produce an outer, usually bentonite-bonded mold part.

[0034] Analogously, this is also possible with a preferred composite molded part core according to the present invention. Recycling of such composite molded part cores and / or molded parts with such a composite molded part core is therefore also easily possible, since it or its composite molded part core decomposes upon exposure to high temperatures, preferably > 150°C, more preferably > 200°C, more preferably > 250°C, even more preferably > 300°C, most preferably > 400°C. This preferably occurs with (at least partial) decomposition and / or degradation of the binder. In addition or as an alternative to at least one of the aforementioned temperatures, the decomposition of the composite molded part core or even of the entire composite material preferably occurs upon exposure to a temperature which is preferably < 1500°C, further preferably < 1250°C, more preferably < 1100°C, even more preferably < 1000°C, most preferably < 750°C.By selecting a decomposition temperature below the stated value, energy consumption during recycling can be kept acceptable. Thus, a composite molded part core is preferred in which the bonding capacity of the at least partially cured binder can be reduced by exposure to temperature. The temperature above which a reduction in the bonding capacity of the at least partially cured binder occurs is preferably > 150°C, more preferably > 200°C, more preferably > 250°C, even more preferably > 300°C, most preferably > 400°C. Additionally or alternatively, this temperature is preferably < 1500°C, more preferably < 1250°C, more preferably < 1100°C, even more preferably < 1000°C, most preferably < 750°C.

[0035] In addition to thermal stress, mechanical stress can also be applied alternatively or in combination to separate the particles of the particulate material (herein also referred to as "grains") from one another. A single process or a combination of several processes has proven particularly suitable for this purpose. These processes are selected from a group that includes coarse crushing (e.g. jaw crushers), fine crushing (e.g. rotating ball mills) or attrition processes (introduction of frictional energy). These processes are also particularly suitable for separating the separated particles from binder residues (in parallel to or after the separation of the particles from one another). The processes can be used dry or wet, either in water and / or solvents or mixtures, if necessary with cleaning additives. Optionally, separating processes can also be used before, between or after the mechanical treatments, e.g.sieving, sifting, optical sorting or (separation) processes based on density differences.

[0036] Both organic and inorganic components have proven suitable as binders. Polyurethane resin (PU resin) has proven particularly suitable for producing a composite molded part core. Polyurethane resin (PU resin) is already used on an industrial scale as a binder in the so-called "cold box process." Therefore, it is available in large quantities and at affordable prices almost worldwide.

[0037] Preferably, the particulate material is mixed with a PU resin, with the polyurethane resin content being approximately 0.5–2% by mass. It is particularly preferred that the particles are coated by mixing with the PU resin, and these coated particles are then formed into the desired geometry and gassed with amine to cure. In a preferred embodiment, one or more additives are also added to the mixing process.

[0038] The gassing causes the PU resin to cure. After curing, the particles are bonded together via resin bridges. Since the cost of the resin (per unit weight) far exceeds that of the sand, it is advantageous to keep the amount of resin used low. One solution to this is to limit the grain size distribution of the particulate material. This keeps the specific surface area (or the surface-to-volume ratio) of the particulate material low. Accordingly, the surface area present in the particulate material that must be bonded using the resin is comparatively small. This preferred embodiment makes it possible to produce a composite molded part core particularly cost-effectively.

[0039] Therefore, a composite molded part core is preferred in which the particulate material comprises sand whose average particle size d50 (sieve analysis or laser diffraction) is in a range of 5 μm - 10 mm, preferably 10 μm - 5 mm, particularly preferably 20 μm - 1 mm. Of course, the particulate material is not limited to sand, but can additionally or alternatively comprise other particulate substances. However, sand is preferred due to its widespread (worldwide) distribution and comparatively low cost. Furthermore, sand particles are characterized by their high hardness.

[0040] In one variant, it may also be desirable to use the quartz content, representative of all forms of crystalline silica, only in a proportion of < 0.1 mass% (based on the total mass of the composition or the composite molded part).

[0041] Preferably, for such a variant, only fillers are used which, alone or in the sum of the total of the (various) fillers, have a proportion of crystalline silica < 0.1 wt.%.

[0042] In a preferred embodiment, a filler fraction comprises inorganic and / or organic fillers or mixtures thereof, wherein each of the fillers preferably has a sufficiently low crystalline quartz content (e.g., <0.1 wt%). The mixing ratio of two fillers can be selected in a ratio between 99.9:0.1 and 0.1:99.9.

[0043] Additionally or alternatively, it is preferred that the particulate (granular) material used to produce the composite molded part core has a particle size (dso Sedigraph or laser diffraction) of > 5 pm, preferably > 10 pm, preferably > 20 pm. Additionally or alternatively, it is preferred that the particulate (granular) material used to produce the composite molded part core has a particle size (dso analogous, e.g., to sieve analysis) of < 3000 pm, < 2000 pm, preferably < 1000 pm, preferably < 500 pm, preferably < 250 pm, preferably < 200 pm, preferably < 150 pm, preferably < 100 pm.

[0044] A composite molded part core is preferred in which the particles of the particulate material (occasionally also referred to as "filler" in the context of this invention) are packed as densely as possible. Accordingly, a composite molded part core according to this invention preferably has a particularly dense grain packing. In addition to the advantages already mentioned above, this also makes it possible (alternatively or additionally) to obtain a comparatively smooth (flat) surface of the composite molded part core.

[0045] In a preferred embodiment, a particularly smooth (flat) surface of the composite molded part core is achieved by mixing particles of different grain sizes and using them together. In this embodiment, the particles of the smaller grain size can fill gaps that remain between the particles of the larger grain size.

[0046] If a particularly smooth surface and / or particularly dense packing is desired, it is therefore preferred that the composite molded part core comprises a particulate material comprising at least two components that differ at least in an average particle size dso (sieve analysis or laser diffraction).

[0047] Conversely, it is also possible to deliberately exploit the above-described situation to produce a composite molded part core with increased porosity. In this case, the intention is to ensure that gaps between particles of one grain size fraction are not filled by particles of the same or a different grain size fraction. This can be advantageous in some cases, as this increased porosity, for example, allows a (liquid) surface treatment material to intentionally and specifically penetrate these pores better and deeper, if necessary. This can, for example, be used to significantly increase strength.

[0048] In a preferred embodiment of the composite molded core already described above, a surface of the composite molded core is at least partially covered by a composite molded shell. Such a composite molded shell preferably comprises a polymer. The composite molded shell can completely envelop the composite molded core or only cover individual surfaces or surface portions of the composite molded core. Preferably, the surface covered by the composite molded shell is a surface of the composite molded core that is exposed to particular stress during use of the composite material formed therefrom and / or that forms a visible side.

[0049] The polymer of the composite molded part shell is preferably a solid or liquid or disperse polymer, which is preferably selected from a group and / or is produced from a precursor selected from a group comprising acrylates, styrene acrylates, silanes, silicones, alkanes, alkenes, alkynes, alcohols, urethanes, epoxides, cellulose, methylcellulose, inorganic polymers and mixtures thereof.

[0050] For example, it is conceivable that a composite molded part core could be coated with a sizing agent after it has cured. A sizing agent is a suspension of, for example, a refractory material that can be applied to the surface of a composite molded part core, improving its properties. Any unevenness that may occur, for example, caused by the structure of the sand grains, could be compensated for by such a composite molded part shell (also referred to as a coating or, as above, as a sizing agent).

[0051] Analogously, according to a preferred embodiment, it is possible to refine the surface of a composite molded part core. This refinement can form the composite molded part shell or be part of the composite molded part shell. The composite molded part shell can serve, for example, to impart to the molded part a desired optical property (e.g., color or gloss) and / or a desired haptic and / or mechanical property (scratch / abrasion resistance) and / or chemical and / or thermal resistance. To achieve these additional advantageous properties, the composite molded part shell can, in one variant, additionally be provided with one or more top coatings, which can be based on the aforementioned polymers.

[0052] As an alternative or supplement to the use of quartz sand for the production of composite molded part cores, other particulate materials from the prior art are also conceivable. For example, composite molded part cores are conceivable and preferred for some applications, comprising a particulate material selected from a group consisting of feldspar, chromite sand, andalusite, chamotte, Cerabeads, olivine, alumina spheres, and zircon sand. Furthermore, the use of mixtures of some of these materials, for example, feldspar and quartz sand and ceramic spheres, is also conceivable and preferred for some applications. Some of the materials used and their properties are shown in Table 1.

[0053] Table 1 : Overview of preferred particulate materials for composite molded cores and their type

[0054] These materials have demonstrated their suitability for use alone, in combination with one another, or in combination with quartz sand, in the production of composite molded part cores. They can be considered non-exclusive examples of the fillers based on oxides, silicates, phosphates, carbonates, sulfates, glasses, and ceramics mentioned above. In an article published by Hüttenes-Albertus Chemische Werke GmbH in 2008 entitled "Special Sands - Molding Materials for Modern Core and Mold Production" by Ulrich Recknagel and Martin Dahlmann, the advantages and properties of various particulate materials were presented using their use as casting molds. It has been demonstrated that the respective advantages of the various materials or mixtures can also be used analogously to produce composite molded part cores.

[0055] For example, the above-mentioned article describes that specially processed, high-quality quartz sands are preferred. These sands are particularly suitable as particulate material for the production of composite molded part cores. Thanks to numerous deposits, quartz sand is available in sufficient quantities and at low cost in Germany and many other parts of the world, resulting in cost advantages in addition to the technical advantages. The production of composite molded part cores can therefore be carried out almost anywhere, and the processes for handling and processing these raw materials are long-established.

[0056] In addition, sufficient plant capacity for the treatment, processing, and conversion of these raw materials on an industrial scale is already available at various locations. The known processes can be used analogously for the production of composite molded cores in large quantities.

[0057] A further advantage is that inexpensive molds and processes for the production of mold cores already exist. For example, molds for the production of molded parts for the metal casting industry are available in a wide variety of shapes and sizes. It has been shown that such systems can also be used to produce composite mold cores ranging in size from a few centimeters to several meters. This makes it possible to design and produce composite mold cores relatively inexpensively and in almost any size and shape.

[0058] In a preferred embodiment, the composite molded core is formed as a positive mold. In particular, such a mold is selected from a group comprising the shape of a kitchen sink, a washbasin, a shower tray, a bathtub, and a worktop. The composite molded core can be uncolored or colored. In a preferred embodiment, coloring can be achieved by at least a fraction of the particulate material having a color, for example, by prior application of a pigment. Alternatively, a particulate material can be used which, due to its type and origin, already has an advantageous intrinsic color, for example, deep black. Additionally or alternatively, a pigment or dye can also be introduced independently of a fraction of the particulate material used.In a preferred embodiment, a pigment and / or dye is contained in a binder composition.

[0059] Alternatively or additionally, it is preferred that a colored layer be applied to a surface of the composite molded part core. This colored layer can be part of the composite molded part shell or form the composite molded part shell itself. Alternatively, the colored layer can also be transparent, comparable, for example, to a clear coat.

[0060] To produce a composite molded part with a composite molded part core as described above, the composite molded part core is preferably provided with at least one layer on at least one surface. This layer forms the composite molded part shell or is part of the composite molded part shell.

[0061] The layer can be clear and unpigmented (colorless). In a further embodiment, this layer can contain transparent colored components. However, in a preferred embodiment, the layer comprises a pigment. This layer can preferably impart a desired color to the composite molded part.

[0062] In addition, a color layer can also be achieved by one or more pigmented or dye-containing top coats.

[0063] In one embodiment, the above-mentioned first and / or further layer and / or composite molded part shell preferably comprises (independently of the other features mentioned above) a polymer and / or a polymer precursor. The polymer and / or the polymer precursor is or preferably comprises a solid or liquid or disperse polymer, oligomer, or monomer, which is preferably selected from a group comprising acrylates, styrene acrylates, silanes, silicones, alkanes, alcohols, urethanes, epoxides, celluloses, methylcelluloses, or mixtures thereof and / or is convertible to a substance from this group. Alternatively or additionally, the polymer and / or the polymer precursor can also be inorganic. An inorganic polymer and / or an organic polymer can each be used as the sole polymer or in combination with one or more other inorganic polymers and / or organic polymers.Combinations of several inorganic polymers, several organic polymers or combinations of one or more inorganic polymers with one or more organic polymers are therefore also possible and preferred in some variants.

[0064] In a preferred embodiment, a polymer is first formed in the desired form. It therefore does not have to be used as a one-component system, but in this embodiment is the product of a two-component system. Such a two-component system may include a solvent. Preferably, it is water-based or based on an organic solvent, or it is a 100% system (i.e., both water- and solvent-free).

[0065] The composite molded part shell preferably comprises an additive, wherein the additive preferably comprises a coloring component, preferably a dye, a color paste and / or a pigment and / or the additive has a Mohs hardness > 4, preferably > 4.5, more preferably > 5.

[0066] The composite molded part shell preferably comprises multiple layers. These can each impart different properties to the composite molded part. For example, it is conceivable that one layer imparts a desired optical effect (e.g., color or gloss) to the molded part, while another layer increases scratch resistance, provides a desired haptic quality, improves fracture strength, improves hot-cold cycling resistance, increases chemical resistance, and / or improves (UV) light resistance.

[0067] Of course, even a single layer can impart several of the aforementioned desired effects to the composite molded part. For example, a single layer can contain pigments or dyes as well as other components that have a different positive effect, such as fine fillers (which fill the gaps between particles and improve the smoothness (and thus the gloss) as well as the haptics and possibly also the UV barrier properties of the layer). Such a layer can also contain other additives such as silanes or silicones, which can also improve the haptics, gloss and / or bond to an adjacent layer, as well as lead to a desired hydrophobicity, e.g., the so-called lotus effect. Finally, additives can also be incorporated that impart a biocidal, e.g., bactericidal, effect to the surface.

[0068] If multiple layers are present, they can be applied simultaneously or at different times or locations. For example, it's conceivable that after applying one layer, this layer is cured first, and only then is another layer applied.

[0069] Preferably, a layer is cured after its application. This is preferably done by gassing, UV exposure, light exposure, IR exposure, and / or thermal treatment. An example of such a layer is a thermally curable lacquer and / or a powder coating.

[0070] Preferably, a layer is applied to the composite molded part core (or previously applied layers) by brushing, spraying, flooding, or dipping. This can be done using positive or negative pressure (e.g., vacuum). Many established methods are available for applying layers to a body, including manual and machine (automated) processes.

[0071] In a preferred variant, the composite molded part core and / or the composite molded part shell is subjected to a further processing step. This processing step is, in particular, a mechanical processing step. This mechanical processing is preferably selected from a group that includes smoothing, grinding, brushing, and dust removal. This can, for example, produce a smoother and / or easier-to-coat surface.

[0072] The mechanical processing can be carried out on the composite molded part core, for example immediately after the composite molded part core has been manufactured and / or before and after the application of a first or further coating, for example the composite molded part shell. In addition, further mechanical processing can be provided, which is preferably selected from a group comprising milling, drilling, polishing, and deburring. This step can serve in particular to provide the molded part with a desired functionality. This can be achieved, for example, by attaching attachments to the molded part, wherein an attachment is preferably selected from a group comprising a faucet, a drain strainer, a wastewater connection, a control element (for example for controlling the drain), a soap or detergent dispenser, and a storage element.It is also conceivable that sensors are inserted or applied which record certain physical properties, e.g. temperature, or that operating elements are applied, e.g. with a touch function for operation.

[0073] This further processing step can be carried out before, during or after the application of the layers described above or a composite molded part shell.

[0074] The particulate (granular) material used to produce the composite molded part core preferably has a density of <5 kg / l, preferably <4 kg / l, most preferably <3 kg / l. This has the advantage that the composite molded part core, or the composite molded part containing it, can be made comparatively lightweight, which reduces transport costs and improves handling.

[0075] In order to keep the composite molded part as light as possible and thus transportable and handleable, the particulate (granular) material used to produce the composite molded part core preferably has a bulk density of < 2.5 kg / l, preferably < 2 kg / l, preferably < 1.5 kg / l, more preferably < 1 kg / l, particularly preferably < 0.8 kg / l.

[0076] Alternatively, the mass of a composite molded part can be reduced by adding fiber materials to the composite molded part core during production, which increases mechanical strength. This allows for reduced wall thicknesses, which ultimately also reduces weight. Such fibers can be organic or inorganic, mineral, amorphous, synthetic, or bio-based.

[0077] The binder of the composite molded part core and / or the composite molded part shell preferably has (optionally independently of one another) a density of > 0.6 kg / l, preferably > 0.9 kg / l, preferably e 1 kg / l, preferably e 1.1 kg / l, preferably e 1.2 kg / l, and additionally or alternatively < 1.7 kg / l, preferably < 1.6 kg / l, preferably < 1.5 kg / l, preferably < 1.4 kg / l, preferably < 1.3 kg / l, preferably < 1.2 kg / l, preferably < 1.1 kg / l.

[0078] In a preferred embodiment, the composite molded part (as a whole) has a mass fraction of the particulate (granular) material used to produce the molded part core of > 70%, preferably > 75%, particularly preferably > 80%, preferably > 85%, most preferably > 90%, and additionally or alternatively < 99%, preferably < 98%, preferably < 97%, preferably < 96%, preferably < 95%. A weight fraction of the particulate material in this range has proven advantageous, as it allows the proportion of the cost-intensive binder to be minimized, while at the same time ensuring sufficient strength and crosslinking through the binder.

[0079] An embodiment of the composite molded part core has proven particularly preferred in which a value which corresponds to one hundred times the quotient of the binder content in mass percent and the theoretical specific surface in cm 2 / g (BET) of the particulate material, is less than or equal to 5, preferably <4.5, further preferably <4, more preferably <3.5, and especially preferably <3. Surprisingly, a composite molded core with such a value exhibits excellent strength while still having a low binder content. This is advantageous both in terms of production costs and in terms of handling and use in practice.

[0080] Preferably, the composite molded part core and / or the composite molded part shell are impregnated at least in sections. The composite molded part shell can also be formed by the impregnate. The impregnate is preferably a polymer, for example a resin, preferably an epoxy resin, PU resin, acrylic resin, most preferably an epoxy resin. If the impregnate forms the composite molded part shell, it is conceivable that it also penetrates at least partially into pores of the composite molded part core. This penetration has the advantage that, in addition to the adhesion to the surface of the composite molded part core, a mechanical bond in the sense of interlocking and / or anchoring of the composite molded part shell in the pores of the composite molded part core also occurs.It has surprisingly been found that the hardness and / or fracture strength of a composite molded part core and / or a composite molded part shell is significantly increased by impregnation compared to non-impregnated composite molded parts. In particular, it is preferred that the composite molded part core is impregnated at least in sections and / or that a composite molded part shell is formed by an impregnate that penetrates at least in sections into the composite molded part core. The impregnate preferably comprises a curable polymer, for example a resin. An embodiment in which the curable polymer is a PU resin, acrylic resin, and very particularly preferably an epoxy resin has proven particularly advantageous. Epoxy resins can penetrate particularly well into the pores of the composite molded part core and cure there. In doing so, they stabilize the composite molded part core.Preferably, portions of the curable polymer remaining outside the composite molding core form parts of the composite molding shell. This is particularly advantageous because the curable polymer penetrating the pores of the composite molding core not only stabilizes the composite molding core, but also creates a mechanical bond in the sense of interlocking and / or anchoring the composite molding shell in the pores of the composite molding core.

[0081] Furthermore, the invention is directed to a method for producing a composite molded part, comprising the steps:

[0082] - Providing a composition comprising a particulate material and < 15 mass percent of a binder based on the total mass of the composition,

[0083] - producing a shaped composite molded part core by at least partially curing the binder,

[0084] - Creating a composite molded part shell which partially covers at least one surface of the composite molded part core in the composite material.

[0085] This process makes it particularly easy to produce a composite molded part as described above with a composite molded part core and a composite molded part shell.

[0086] Preferably, a composition is provided that contains the particulate material and less than 15 mass percent, preferably <12 mass percent, preferably <10 mass percent, more preferably <8 mass percent, most preferably <5 mass percent of the binder, based on the total mass of the composition. By reducing the proportion of the comparatively expensive binder, the costs of a composite molded part core produced from this composition can be significantly reduced. It should be noted that the steps of producing the composite molded part core and creating a composite molded part shell do not have to be carried out in the order specified above.It is also conceivable that the composite molded part shell is produced first, for example by spraying a composite molded part shell raw material composition into a negative mold, into which - if appropriate after formation (for example curing) of the composite molded part shell - the provided composition is introduced to form the composite molded part core.

[0087] Alternatively, in one process variant, it is preferred that the composite molded part core is first produced and, in a subsequent process step, is covered at least partially with the composite molded part shell. This, in turn, can be provided with one or more additional thin cover layers.

[0088] In all cases, it is possible, and in some process variants preferred, for the step of producing the composite molded part shell to take place at a temporally and / or spatially different time and / or location from the step of manufacturing the composite molded part core. For example, it is conceivable that the composite molded part core is manufactured at one location and later customized at another location by the same or a different company by applying the desired composite molded part shell and / or cover layer.

[0089] Preferably, a composition for producing the composite molded part shell is selected such that the mass fraction of all binders used to produce the composite molded part is <25 mass percent, preferably <22 mass percent, preferably <20 mass percent, more preferably <18 mass percent, most preferably <15 mass percent. This allows a composite molded part to be manufactured and offered particularly cost-effectively.

[0090] In a preferred variant of the process, it is provided that the at least partial curing of the binder takes place under

[0091] Exposure to a temperature > 25°C, more preferably > 30°C, more preferably

[0092] > 40°C, more preferably > 50°C, most preferably > 60°C, and / or exposure to a reagent, preferably gassing, preferably with an amine, and / or

[0093] Exposure to electromagnetic radiation, preferably UV, light, and / or IR, and / or the addition of a catalyst, is performed. It has been shown that this can achieve exceptional strength and / or durability of the composite molded part core.

[0094] Furthermore, a preferred process variant involves machining a surface of the composite molded part core and / or the composite molded part shell. This machining is preferably performed mechanically. The machining preferably comprises at least one step selected from a group including smoothing, grinding, brushing, dust removal, milling, drilling, polishing, and deburring. One or more of these steps makes it easy to adapt the composite molded part core or the entire composite molded part comprising the composite molded part core to specific customer requests and / or requirements.

[0095] In a preferred process variant, the composite molded part core and / or the composite molded part shell is impregnated. The impregnate is preferably a polymer, for example a resin, preferably acrylates, urethanes, or epoxies, most preferably an epoxy resin. Surprisingly, it has been shown that such impregnation can significantly increase the hardness and fracture strength of a composite molded part, or of the composite molded part core and / or the composite molded part shell. The impregnation process can be supported by external influences, for example, by ultrasonic treatment or vibration.

[0096] In addition to these and other technical advantages, the novel process also leads to significant economic and ecological advantages, which is ultimately also enormously beneficial for the economic and ecological evaluation of the composite molded parts produced thereby and / or the end products containing such a composite molded part, such as sinks, washbasins, shower trays, bathtubs and worktops.

[0097] Furthermore, the object underlying the invention is achieved by a method for recycling a composite molded part core and / or a composite molded part produced according to the method described above. This method is characterized in that the binding capacity of the at least partially cured binder is reduced such that the bond between two adjacent particles of the particulate material is eliminated. If this bond between several, preferably (almost) all, particles of the particulate material is eliminated, the composite molded part core and / or the composite molded part disintegrates. The individual components can be separated from one another and separately recycled. In particular, this makes it possible to recover the particulate material and, for example, to reuse it as particulate material in a composite molded part core.

[0098] A process variant has proven particularly preferred in which the binding capacity of the at least partially cured binder is reduced by applying pressure and / or shear forces. The pressure and / or shear forces can be applied, for example, using a mixer or stirrer.

[0099] Alternatively or additionally, a reduction in the binding capacity of the at least partially cured binder by applying heat is conceivable and preferred in some variants. Upon exposure to heat, the at least partially cured binder may denature and / or decompose, thereby reducing its ability to bind the particles of the particulate material.

[0100] Furthermore, the invention is directed to a composite molded part comprising a composite molded part core as described above. Such a composite molded part has proven particularly advantageous if it is intended and suitable for use in kitchens and / or sanitary facilities. In particular, it is preferred that the composite molded part is selected from a group comprising washbasins, sinks, shower trays, bathtubs, bidets, toilets, countertops, furniture or furniture parts, floor coverings, wall coverings, and tiles.

[0101] In a preferred embodiment, such a composite molded part has a mass fraction of all binders used in its production of < 25 mass percent, preferably < 22 mass percent, preferably < 20 mass percent, more preferably < 18 mass percent, most preferably < 15 mass percent. Such a low proportion of the comparatively expensive binder makes it possible to produce and offer such a composite molded part particularly cost-effectively. It has been shown that, in particular, by adapting the properties of a composite molded part shell, the properties of the composite molded part can be adapted such that they also achieve or even exceed the properties of the products known from the prior art that are relevant for the respective application.

[0102] A composite molded part as described above can preferably be produced using the method described above. Accordingly, all properties resulting directly or indirectly from the method are to be considered disclosed for the composite molded part. The method is particularly suitable and / or intended for producing a composite molded part as described above.

[0103] Conversely, all described properties of the composite molded part and / or the composite molded part core, individually or in combination, are also intended to characterize the process described above in its entirety or individual raw materials or compositions used and / or the (intermediate) products obtained thereby.

[0104] Further advantages, objects and features of the present invention are explained with reference to the following examples of selected embodiments and variants.

[0105] Examples and test results

[0106] In an initial series of tests, the influence of particle size and binder quantity on strength and processability was investigated. Various test specimens were prepared and compared.

[0107] Sands of various average particle sizes were used as particulate material. The physical characteristics of these sands are presented in Table 2. Based on the average particle size of these three sands, they are designated No. 15 (average particle size < 0.15 mm (sieve analysis)), No. 19 (average particle size < 0.19 mm (sieve analysis)), and No. 25 (average particle size < 0.25 mm (sieve analysis)).

[0108] Table 2: Physical characteristics of various sands

[0109] A composition known as a cold-box binder system was used as the binder. For the test series described, this system comprises "Askocure 388" (Part 1) and "Askocure 688" (Part 2) in a 1:1 mixing ratio, as well as a catalyst, "ASK 704" (A-min).

[0110] To create the compositions, the binder system was added to the three different sands in three different quantities: to Sand No. 15 in proportions of 3 mass%, 4 mass%, and 5 mass%; to Sand No. 19 in proportions of 2 mass%, 3 mass%, and 4 mass%; and to Sand No. 25 in proportions of 1 mass%, 2 mass%, and 3 mass%. As shown in Table 3, these figures refer to the total mass of the mix of components Part 1 and Part 2 (see Table 3).

[0111] The compositions were prepared based on 30 kg of the respective sand. The respective sand was mixed with the binder in a forced mixer for 5 minutes in the amount specified in Table 3. Composite molded cores of each composition were produced using a laboratory core shooter (semi-automatic ramming device, PN / DIN from Morek Multiserw), in this example, bending bars measuring 22 x 22 x 160 mm. The strengths of the manufactured bending bars were determined after the times specified in Table 3 using a strength testing device (universal strength testing device 0 - 6000 N / cm 2 , Morek Multiserw). The results are listed in Table 3.

[0112] Table 3. Strength testing*** of various bending bars

[0113] * = based on the dso value, which is approximately 150, 190 and 250 pm

[0114] ** = BET = theoretical specific surface area in cm2 / G

[0115] *** = Strengths in N / cm 2 **** = Mix: No. 15 and No. 25 were mixed 1:1

[0116] As can be seen from Table 3, the measured strengths of almost every test specimen increase with increasing maturation time, i.e. the time elapsed until the strength is measured.

[0117] For test specimens No. 1 - 3, each containing the same sand (No. 15), the measured strengths increase significantly with increasing binder content.

[0118] For test specimens No. 4 - 6 (with sand No. 19), those specimens with the highest binder content also show the highest strengths.

[0119] For test specimens No. 7 - 9, each containing sand No. 25, the measured strength also increases significantly with increasing binder content. For test specimens No. 10 and No. 11, which contain the (bimodal) mixture of sands No. 15 and No. 25, an even greater strength was measured. For example, the measured strength of test specimen 10 is greater than that of test specimen No. 1 at each of the measured times after removal from the core shooter, despite a lower binder content compared to test specimen 1. Even for test specimen No. 8, which has an identical binder content but only contains a single sand, namely sand No. 25, a higher strength was measured in each test than for test specimen No. 8 at the same time after removal from the core shooter.

[0120] With the same binder content of 3 wt%, significant strength differences are measurable between test specimens 1, 5, and 9, which contain only one of the three different sands. From these measurements, it can be concluded that the average particle size of the particulate material has a noticeable influence on the strength of the resulting test specimens. It is noteworthy that the test specimens produced with sand No. 19, which has an average particle size between the two other sands No. 15 and No. 25, exhibit the lowest strengths in comparison.

[0121] From these results, it can be concluded that the manufacturing process and properties of composite molded part cores can be specifically controlled by varying the average particle size, grain distribution, and binder content. It is expected that this will also result in differences in the post-processing properties and / or the properties of a resulting composite molded part, such as porosity, absorbency, and smoothness.

[0122] In a further series of tests, the influence of average particle size and binder content on the strength and processability of test specimens was determined. The three sands described above, No. 15, No. 19, and No. 25, were also used. However, an inorganic binder, namely ASK, Inotec EP 4158 (liquid, water glass preparation), was used as the binder, and ASK, Inotec TC 4500 (powder) was used as the promoter (hardener). The test specimens were produced using the hotbox process, with a Loramendi, MDR-0.5, 2014, core shooter. The compositions were prepared manually using a Kenwood mixer based on 1 kg of the respective sand. The sand was initially added, and the promoter was then mixed in. The binder was then added.

[0123] The mold temperature was 150 °C and the shooting pressure was 5 bar. Gassing was carried out with hot gas at a temperature of 200 °C and a hot gas pressure of 3 bar for a hot gas purge time of 15 s.

[0124] As shown in Table 4, 8 different samples A - H were prepared. Samples A - C are based on sand No. 19, samples D and E on sand No. 25, and samples F and G on sand No. 15. In addition, for sample H, a bimodal mixture of sands No. 15 and No. 25 in a mass ratio of 1:1 was used.

[0125] For each of the three individual sands, compositions were prepared with a low water glass content of 3 mass percent and a low additive content of 2.4 mass percent, as well as a high water glass content of 5 mass percent and a high additive content of 4 mass percent. Based on sand No. 19, a composition with a medium water glass content of 4 mass percent and a medium additive content of 3.2 mass percent was also prepared. For sample H, based on the bimodal mixture of sands No. 15 and No. 25, only the low water glass content of 3 mass percent and a low additive content of 2.4 mass percent were used to produce the composition. The compositions of samples A - H can be found in Table 3.

[0126] Table 3: Compositions of samples A - H

[0127] *= Mix: Sands No. 15 and No. 25 were mixed in a 1:1 mass ratio. Strength measurements were performed on the resulting test specimens. The determination was carried out using three-point bending on a ZwickRoell tensile-compression testing machine with a support spacing of 150 mm. Initially, a force of 20 N was applied, followed by a travel speed of 1 mm / min until failure. The maximum force determined in triplicate is shown in Table 5.

[0128] Table 5: Results Maximum force

[0129] As can be seen from Table 5, for all particle sizes of the sands used, the maximum force that can be applied to the test specimen until fracture increases with increasing mass fraction of the binder (water glass). The (bimodal) mixture of sands No. 15 and No. 25 exhibits a higher maximum force than any of the measured test specimens based on a single sand with the same binder content (3 mass % water glass).

[0130] Furthermore, the table shows that, with the same binder content, the measured strengths of the test specimens based on sands of different average particle sizes differ significantly. It can therefore be concluded that the average particle size has a demonstrable influence on the strength, or rather, the maximum force. For the only three average particle sizes measured, a tendency can be seen that a smaller average particle size leads to increased strength of the test specimen.

[0131] Furthermore, gas permeability measurements were performed on the test specimens A - H described above. The test setup used was developed in-house by the Technical University of Munich. It is shown schematically in Fig. 2.

[0132] Gas permeability was measured by measuring the volume flow through the sample with a pressure ramp in the test chamber from 0 to 440 mbar at 440 mbar / min. The results are presented in Table 6.

[0133] Table 6: Results of the gas permeability test, gas permeability expressed as volume flow through the sample in m / s

[0134] As can be seen from Table 6, it can be seen that gas permeability tends to be higher with coarser particle sizes. However, the influence of the binder content on gas permeability is small or almost nonexistent. The bimodal mixture (H) has a lower gas permeability than the test specimens based on sand No. 15 (samples F and G). Compared to test specimens based on sand No. 25 (samples D and E), the gas permeability is even significantly lower.

[0135] The influence of impregnation on the fracture strength of a selection of test specimens was investigated. The test specimens for investigating this type of post-treatment were prepared using a sand designated H33 with the grain size distribution shown in Table 7 (determined by sieve analysis).

[0136] Table 7: Grain class distribution of sand “H33”

[0137] Two different binder systems were used to produce the test specimens.

[0138] For test specimens of the first type, referred to here as "BAF," a two-component binder from Hüttenes Albertus, namely Biocure 7241 "P1" and Biocure 6324 "P2," was used as the binder. For a 3 kg batch, 24 g of each of these components, P1 and P2, were used, corresponding to 0.8 wt%. First, component P1 was added to the sand and mixed for 2 minutes in a 5-liter laboratory concrete mixer. P2 was then added, and the mixture was mixed again for 2 minutes. The pot life of the resulting sand / binder mixture was at least 20 minutes.

[0139] Further processing into test specimens was carried out using a Morek Multiserw laboratory shotgun, PL, with a shot time of 3 s, a delay of 3 s, and subsequent amine application. The amine quantity was 0.5 ml. After the amine application, the specimens were rinsed for 30 s (blowing time after amine: 30 s).

[0140] For test specimens of the second type, referred to here as "ASK," the same H33 sand was used, but a two-component binder from ASK, namely Askocure 688 "P1" and Askocure 388 "P2," was used. Analogous to the test specimens of the first type, 0.8 wt. % of each binder component was added to the sand. This was also carried out in two stages: first, component P1 was mixed with the sand in a 5-liter laboratory concrete mixer for 2 minutes. Subsequently, P2 was added and mixed again for 2 minutes. The test specimens were formed using a semi-automatic laboratory shotgun.

[0141] Fracture and impregnation tests were then conducted on the resulting specimens of both types. The (fracture) strength of the (impregnated) specimens was determined using a three-point bending test on a ZwickRoell tensile-compression testing machine. The support spacing was 150 mm. A force of 20 N was applied, followed by movement of the loading body until fracture occurred at a travel speed of 1 mm / min.

[0142] Some of the resulting "ASK" and "BAF" test specimens were impregnated with a two-component epoxy resin (EP resin). The EP resin components were CeTePox 255-3R (resin) and CeTePox 1502H (hardener). These were used in a mass ratio of 100:55.

[0143] For impregnation, the resulting EP resin mixture was placed at room temperature and the test specimens were impregnated by fully immersing them for 9 minutes. For some test specimens, the impregnation was additionally supported by a) ultrasonic treatment and b) treatment on a vibrating table.

[0144] After completion of the immersion process, the impregnated test specimens were cured for 12 h at 65 °C.

[0145] The (breaking) strength of the (impregnated) test specimens was then measured on the ZwickRoell tensile-compression testing machine using three-point bending as described above. The measured strengths of the various test specimens are listed in Table 8.

[0146] Table 8: (Fracture) strengths of the (impregnated) test specimens

[0147] *) Proportion of polymer based on the mass of the test specimen after impregnation

[0148] As can be seen from Table 8, the strength increases significantly through impregnation.

[0149] The measured strength after impregnation is slightly higher for the "BAF" type test specimens than for those of the "ASK" type. Mechanical support during impregnation through ultrasonic treatment or vibrating table treatment does not have a significant positive effect.

[0150] For comparison, test specimens measuring 22 x 22 x 160 mm were cut from PMMA and polyester-bonded composite kitchen sinks. In addition, composite test bars measuring 22 x 22 x 160 mm were cast from polyester with quartz filler at various quartz contents. The test specimens were tested for strength as described above. The measured strengths of the various test specimens are shown in Table 9.

[0151] Table 9: Strengths of the test specimens (comparison)

[0152] A comparison of the strengths of the test specimens listed in Table 9 with those in Table 8 shows that the measured strengths of the test specimens without additional impregnation are lower than those of the comparison test specimens listed in Table 9. However, if the test specimens are impregnated, their strength increases significantly in all cases and significantly exceeds the measured strengths of all comparison test specimens.

[0153] To investigate the effect of impregnation more closely, the "BAF" and "ASK" test specimens described above were each impregnated for different time intervals. The EP resin components were identical to the impregnated materials described above, namely CeTePox 255-3R (resin) and CeTePox 1502H (hardener) in a mass ratio of 100:55. This EP resin mixture was initially introduced at room temperature, and the test specimens were completely immersed in the resin mixture. In no case was mechanical assistance provided by ultrasonic treatment or vibrating table treatment.

[0154] The duration of the impregnation process was significantly reduced and was 1 s, 5 s, or 15 s in this test series. Due to the shortened impregnation time, less impregnate was able to penetrate the pores of the test specimens. The fill level resulting from the sum of binder and impregnate is therefore significantly lower than the fill level specified in Table 8 for impregnated test specimens, but increases with longer impregnation time. After removing the test specimens from the impregnation mass, the impregnated samples were cured for 12 hours at 65 °C, analogous to the above test series.

[0155] Unlike the "BAF" type test specimens, the "ASK" type test specimens were impregnated with an impregnating compound that contained a pigment in addition to the EP resin components. In the described test series, a black pigment (carbon black) was used and added to the impregnating compound at a mass fraction of 10%. The strengths determined for the test specimens impregnated in this way over shorter periods are shown in Table 10. Table 10: (Fracture) strengths of the (impregnated) test specimens

[0156] *) Proportion of polymer based on the mass of the test specimen after impregnation. Table 10 shows that the strength increases significantly with the impregnation time and thus with the degree of filling (of the EP resin).

[0157] The degree of blackening of the test specimen surface increases with the duration of the impregnation steps. A deep black, opaque surface is achieved after just 15 seconds of impregnation.

[0158] Furthermore, the influence of the binder content on the manufacturing process and on the strength was investigated using various test specimens. Analogous to the "BAF" type test specimens described above, the above-described sand H33 and the binder from Hüttenes Albertus, Biocure 7241 P1 and Biocure 6324 P2, were used. First, P1 was added to 3 kg of sand in a 5-liter laboratory concrete mixer and mixed for 2 minutes. This was followed by the addition of P2, and mixing was continued for another 2 minutes. However, in contrast to the test specimens described above, the mass of the added binder was changed and adjusted to a total of (P1 + P2) 2.0 wt%, 4.0 wt%, 6.0 wt%, or 8.0 wt% for the various test specimens. The pot life of the resulting compositions was at least 20 minutes in each case.

[0159] A laboratory firing machine from Morek Multiserw, PL was used to produce the test specimens. The firing time was 3 s, and the delay was also 3 s. Subsequently, an amine injection was carried out, with the amine quantity being 1.5 ml. After the amine injection, the specimens were rinsed for 30 s (blowing time after amine: 30 s). The strengths measured for these test specimens (analogous to the measurement described above) are shown in Table 11.

[0160] Table 11 : Strengths of test specimens (type “BAF”) with different binder contents

[0161] The trend is clearly visible that the strength increases with increasing proportion of polymer relative to the mass of the test specimen.

[0162] Analogous test specimens were also produced using a different binder, namely a 2-component epoxy resin. Test specimens of this type are referred to below as "EP" or "EP-type." The epoxy resin was made from 100 parts by mass of CeTePox 255-3R (resin) and 55 parts by mass of CeTePox 1502H (hardener). After thoroughly mixing these components, the resulting mixture was added to 3 kg of H33 sand in a 5-liter laboratory concrete mixer and mixed for 2 minutes. For the various test specimens, 2.0 wt%, 4.0 wt%, 6.0 wt%, or 8.0 wt% of the binder (in this case, the mixture of resin and hardener) were also used. The test specimens were also manufactured using a laboratory firing machine from Morek Multiserw, PL, with a firing time of 3 s and a delay of 3 s. Curing took place at a mold temperature of 70 °C for a duration of 7.5 minutes.The strengths determined on the test specimens produced in this way are shown in Table 12. The resin and hardener quantities given in this table refer to the batch size of 3 kg sand described above.

[0163] Table 12: Strengths of test specimens with different epoxy resin binder contents

[0164] *) Proportion of polymer based on the mass of the test specimen

[0165] Even when using an epoxy resin as a binder, the strength increases with increasing binder content, as can be seen in Table 12. The test specimens with EP resin as a binder show higher strength than the "BAF" type test specimens at the same binder content.

[0166] Additional EP-type test specimens were also produced based on a sand other than the H33 sand used above. These test specimens were produced analogously to the process described above. The only difference is that a mixture of two black sands was used instead of the H33 sand. The sands used are designated a) Mix 29 / 2013 and b) Mix 10 / 2022. These materials are pigmented sands with a grain size (sieve analysis) of 0.09–0.5 mm and an average grain size d50 = 0.25 mm, with the pigment fixed to the sand with a binder. These sands are used in the state-of-the-art production of acrylic and / or polyester-based kitchen sinks, typically with a sand content of 65–70 wt% based on the total mass of the sink. Uniformly colored, deep black test specimens were obtained. The strength test results are shown in Table 13.

[0167] Table 13: Strengths of test specimens with colored sand mixtures

[0168] As can be seen from Table 13, the strength increases with the filling level, regardless of the sand used.

[0169] In a further series of tests, test specimens containing Croning sand "LH" as particulate material were examined. This is a resin-coated sand (phenolic resin coated) with a grain size d50 (sieve analysis) of 250 μm. To produce the test specimens, the EP resin was used as a binder with a mass fraction of 2.0 wt. %, 2.5 wt. %, or 3.0 wt. %, analogous to the above tests. The mixture was molded by shooting as described above, with preheating to 120°C and a mold temperature of 300°C. The strength measurements were carried out analogously to the above, and the strengths shown in Table 14 were determined.

[0170] Table 14: Strengths of test specimens with Croning sand “LH”

[0171] *) Proportion of polymer based on the mass of the test specimen Further advantages, objectives and properties of the present invention are explained with reference to the following description of the attached figures.

[0172] The figures show:

[0173] Fig. 1 shows an exemplary geometry of a composite molded part,

[0174] Fig. 2 a device for measuring the porosity of a test specimen

[0175] Fig. 3a - 3e Parts of a mold used to produce composite molded cores,

[0176] Fig. 4a - 4b Sections of a profile of a composite molded core,

[0177] Fig. 5a - 5b Sections of a profile of a composite molded core,

[0178] Fig. 6a - 6d Exemplary composite molded cores

[0179] Fig. 7 shows an example of a composite molded part core produced using a foundry stand,

[0180] Fig. 8a - 8b Examples of impregnation and coating, and

[0181] Fig. 9a - 9b an example of a composite molded part after impregnation and

[0182] Stratification.

[0183] Figure 1 shows an example of the geometry of a composite molded part. A kitchen sink 1 is shown in Fig. 1. It comprises a (at least largely flat) storage surface 2 in the left-hand area and a (rinsing) basin 3 in the right-hand area. An opening 4 is arranged in this basin, which, when in use, is usually designed as a closable drain 4.

[0184] In order to allow liquid to drain between objects arranged on the storage surface 2 into the basin 3, even underneath the respective object, the storage surface 2 has profiles 5. These can be designed as elevations or depressions. In the example shown, the profiles 5 are designed as elevations. In this variant, it is not absolutely necessary for the profiles 5 to extend to the edge of the basin 3, as would be necessary for channels that would have to have an opening in the area of ​​the basin 3 to allow liquid to drain into the basin. The elevations 5 ensure that a gap is formed at least in some areas between the storage surface 2 and an object arranged on it. This gap enables liquid to drain into the basin 3 and thus also into the drain 4.

[0185] Reference numeral 6 denotes an opening through which, for example, a fluid line can be routed. Such a fluid line is usually equipped with a valve and usually also a mixing unit, so that the fluid flow can be regulated and, if necessary, several fluids (usually hot and cold water) can be mixed together. Accordingly, such a fluid line is usually designed as a faucet and is permanently connected to the kitchen sink 1. The connection is usually realized by a clamp connection.

[0186] It goes without saying that Figure 1 merely represents an exemplary variant of a composite molded part, illustrated here using the example of a kitchen sink. A kitchen sink can, for example, also have two or more sink inserts or even additional storage areas. The design here (and elsewhere) is only exemplary. The same applies in principle to the variety of shapes and designs for washbasins, shower trays, and bathtubs.

[0187] Figure 2 shows the device used to measure the porosity of a test specimen. This test device is a setup used at the Technical University of Munich for conducting gas permeability tests.

[0188] The sample, designated by reference numeral 42, is located in a crucible 41, which is closed by an upper and a lower end piece 40. The crucible 41 can be temperature-controlled by a temperature control system 30. The crucible 41 with the sample 42 is located in a housing 39, the internal temperature of which can be measured with a temperature sensor 34. The temperature of the crucible 41 itself can be determined non-contact using a pyrometer 32. The gas permeability is measured by feeding a gas, in this case the inert gas argon, from a pressure reservoir 31 into the housing interior 39. On the path between the pressure reservoir 31 and the housing interior 39, the gas passes a control device 33, by means of which the flow and pressure of the gas can be regulated. The test specimen 42 is exposed to the gas flowing into the housing interior 39.The gas passing through the test specimen 42 can flow out through an exhaust line 36 along the direction of arrow P. It passes through a flow measuring device 35, which provides data characteristic of the gas permeability of the sample.

[0189] The exhaust line 36 preferably opens into a container filled with water 37. The depth of immersion of the end piece of the exhaust line 36 into the water 37 allows the backpressure acting on the exhaust gas flow to be adjusted very precisely. To ensure consistent conditions in this regard, the container filled with water 37 is preferably arranged on an analytical balance 38. This makes it possible to precisely adjust and document the water quantities and thus the backpressure acting on the exhaust gas flow.

[0190] Figures 3a to 3e show parts of a mold used to produce composite mold cores. Figure 3e shows the individual parts shown in the previous figures arranged as they are placed one upon the other to form a mold. As can be seen particularly in Figure 3a, the mold has openings to allow the escape of displaced gas.

[0191] On the contact surfaces shown exposed in Figure 3b between two adjacent molded parts, channels can be seen through which a temperature control medium can flow, by means of which the molded parts can be adjusted to a desired temperature.

[0192] Composite molded part cores 100 were produced using the mold shown in Figures 3a to 3e, which were used for further testing and visual evaluation. The mold shown in Figures 3a to 3e was chosen because it is similar to a mold for producing a kitchen sink or washbasin. However, it has fine circumferential contours, so that the formation of these contours allows a very precise assessment of the quality of the molding process. For the tests, compositions as described above in connection with Table 3 were used. Accordingly, Askocure 388 and Askocure 688 were used as the binders. An amine (ASK 704) acted as the catalyst. For each of the test specimens produced in this way, approximately 6 kg of the respective composition was used.

[0193] The resulting composite molded cores 100 were subjected to a visual inspection. As indicated above, the formation of the profiles in the peripheral area of ​​the mold was of particular importance. Some sections of the resulting profiles are shown in Figures 4a to 6b. The profile shown in Figure 4a is an example of a composite molded core in which the molding was not completed. Defects 62 are clearly visible in the area of ​​a projection 60.

[0194] The situation is different with the section of the profile shown in Figure 4b. In the composite molded core shown in Figure 4b, the profile is fully formed and the projection 60 also has no defects.

[0195] For a better overview, such a situation is also illustrated in Figures 5a and 5b. The profiles are fully formed in the composite molded core 100 marked with the number 8. No defects are visible. In contrast, in the composite molded core 100 shown in Figure 5b and marked with the number 9, a defect 62 is visible in the profile marked with reference numeral 60.

[0196] A summary of the results of the visual evaluation is presented in Table 15 below. It is noteworthy that the molding was not complete for composite molding cores numbered 3, 6, and 9. These are the composite molding cores with the highest binder contents for their group (with an identical mean particle size), namely 5 mass percent, 4 mass percent, and 3 mass percent, respectively.

[0197] Table 15: Results of the optical evaluation of various molded parts

[0198] *BET = theoretical specific surface area in cm 2 / G

[0199] Surprisingly, it was found that there is a relationship between the forming behaviour and the hundredfold quotient of the binder content in

[0200] 5 mass percent (“BM”) and the BET value. Complete deformation was achieved if this index did not exceed 3. However, if the index was above 3, the deformation of the test specimens was incomplete.

[0201] Further composite molding cores were produced based on a sand designated as Sand No. 19 with the binder system also used for the composite molding cores described above, comprising the components Askocure 388 (P1), Askocure 688 (P2) in a 1:1 mass ratio and the amine ASK 704. The mass fractions of the binder were 0.8%, 1.0%, or 1.2%, resulting in a BM / BETx100 index of significantly less than 3. Sand No. 19 exhibits the properties listed in Table 16.

[0202] Table 16: Properties of sand No. 19

[0203] The compositions and the composite mold cores were prepared using the same process as described in connection with the composite mold cores shown in Figures 4a and 5b. The mold used was also identical.

[0204] As can be seen from Table 17, complete molding was achieved for all composite molding cores produced in this way. Example composite molding cores from this test series are shown in Figures 6a - 6d. As can be seen from these, complete molding was achieved for all composite molding cores of this type. Fig. 6a is an illustration of a composite molding core produced with a binder content of 1.2 mass percent, whereas Figs. 6b - 6c are illustrations of a composite molding core for which a binder content of 1.5 mass percent was used. Fig. 6d shows a detailed section in the area of ​​the recess.

[0205] Table 17: Visual evaluation of the shape and index BM / BET*100

[0206] * = based on the dso value, which is approximately 150, 190 and 250 pm

[0207] ** = BET = theoretical specific surface area in cm 2 / G

[0208] Further composite molding cores were produced based on other particulate materials. For this purpose, the binder system used for the composite molding cores described above was also used, with the components Askocure 388 (P1) and Askocure 688 (P2) in a mass ratio of 1:1 and subsequent amine application. The mass fractions of the binder were between 2 and 5 mass percent, as listed in Table 18. The binder content was selected to be somewhat higher than for the above test series based on sand No. 19 due to the partially higher specific surface area and partially higher absorbency of the materials used. The index BM / BETx100, calculated as a function of the BET of the various particulate materials used, was in the range of 1.53 - 2.32. The particle sizes given in Table 18 for the various materials were determined by sieve analysis.

[0209] The foundry scrap listed as No. 1 is foundry scrap sand, i.e., used sand generated in an iron foundry. This includes both core and molding sand in a ratio of approximately 1:1. The 0.1-0.5 mm fraction of this used sand was sieved out and used as particulate material for the purposes of this invention.

[0210] The nutshell granulate (No. 2) is a commercially available nutshell granulate based primarily on hazelnut shells. It was sieved to 0.1–0.5 mm, and this fraction was used as particulate material for the purposes of this invention.

[0211] The olive stone granulate (No. 3) is also a commercially available product which was sieved at 0.1 - 0.5 mm and this fraction was used as particulate material in the context of this invention.

[0212] The recycled glass granulate listed as No. 4 is a commercially available white glass granulate which was sieved at 0.1 - 0.5 mm and this fraction was used as particulate material in the context of this invention.

[0213] To produce the recyclate from PMMA kitchen sinks listed as No. 5, PMMA / quartz-based kitchen sinks were crushed and the 0.1 - 0.5 mm fraction was sieved out and used as particulate material within the meaning of this invention.

[0214] Recyclate No. 6 was obtained analogously from polyester / quartz-based kitchen sinks. For this purpose, kitchen sinks were crushed, and the 0.1–0.5 mm fraction was sieved out. This fraction was subsequently used as particulate material within the meaning of this invention. Alternatively, this material preparation can also be applied to kitchen countertops, sinks, shower trays, or bathtubs based on polyester / quartz (or other fillers), as well as acrylate / quartz (or other fillers).

[0215] Table 18: Strength and index of composite molded cores based on alternative particulate materials

[0216] * the strength was measured on cut-out test bars 22x22x160 mm

[0217] ** = BET = theoretical specific surface area in cm 2 / G

[0218] An example of a composite mold core produced with a foundry scrap (No. 1 in Table 18) is shown in Figure 7. The darker coloration compared to the composite mold cores shown in Figures 4 - 6 is induced by the darker color of the foundry scrap compared to the other sands used.

[0219] Tests were conducted on some composite molded cores for post-treatment, such as the application of a composite molded shell. The composite molded shell was applied by impregnation and / or coating.

[0220] The treatment of the composite molded cores was carried out

[0221] - with a flood primer based on an aqueous acrylate (AC3600) in combination with a 2-component epoxy resin,

[0222] - a sole treatment with 2-component epoxy resin (2-K-EP) by impregnation or coating, and optionally a black paint finish.

[0223] Figure 8a shows an example of flood impregnation of a composite molded part core.

[0224] Figure 8b shows an example of a 2-component EP coating and subsequent black painting.

[0225] Figures 9a and 9b show a composite molded part after impregnation and coating. The composite molded part core shown in Figures 6c and 6d was used as the composite molded part core. The homogeneous and full-surface composite molded part shell is particularly evident when comparing the representations in Figures 6c and 6d with those in Figures 9a and 9b.

[0226] The applied composite molded part shell can be very thin, chemically and physically very resistant, and / or decorative. The composite molded part shell can itself be surface-coated and / or represent a fully colored and functionalized outer layer. Due to the low layer thickness and the potential for saving binder for the production of the composite molded part core, the composite molded part shell can also be comparatively expensive.

[0227] The composite molded part core can - since it can be covered and / or protected by the composite molded part shell - be manufactured very inexpensively, lightweight, recyclable, sustainable, with an even further reduced binder content, renewable raw materials, inorganic or organic recyclates or mixtures of these, e.g. old foundry sand, rice husk ash, limestone granulate, ceramic granulate, wood chips, expanded glass, polystyrene, expanded clay and others.

[0228] Table 20 shows that the exemplary composite molded parts, as obtained with composite molded part cores as described in the context of this invention, are at least equal to, and usually even better than, the composite molded parts available on the market - in this case PMMA and polyester-based kitchen sinks - when comparing various technical properties.

[0229] Table 20: Comparison of new composite molded parts (AD) with those available on the market

[0230] Composite molded parts (Sch, E, B, A, M, W., K)

[0231] The polymers mentioned under A to D were used in these examples as the basis for the surface coating

[0232] ** water-based The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are new, individually or in combination, over the prior art. It is further pointed out that the individual figures also describe features which may be advantageous in themselves. The person skilled in the art will immediately recognize that a specific feature described in a figure may also be advantageous without the adoption of further features from this figure. Furthermore, the person skilled in the art will recognize that advantages may also arise from a combination of several features shown in individual or different figures.

Claims

Patent claims 1. A composite molded part core comprising a particulate material and an at least partially cured binder which bonds particles of the particulate material to one another, characterized in that a mass fraction of the at least partially cured binder is <15 mass percent.

2. Composite molded part core according to claim 1, characterized in that at least one surface of the composite molded part core is covered at least in sections, preferably completely, by a composite molded part shell.

3. Composite molded part core according to one of the preceding claims, characterized in that a binding capacity of the at least partially cured binder can be reduced by an activator, wherein the activator is preferably a temperature application or reagent application, by which a chemical and / or physical reaction in or with the binder can be triggered, which reduces the strength of the entire composite molded part core and / or converts the binder into a subsequent product with reduced binding capacity.

4. Composite molded part core according to one of the preceding claims, characterized in that the composite molded part core is impregnated at least in sections and / or a composite molded part shell is formed by an impregnate penetrating at least in sections into the composite molded part core, wherein the impregnate preferably comprises a curable polymer, for example a resin, wherein the curable polymer is preferably an epoxy resin.

5. Composite molded part core according to one of the preceding claims, characterized in that the particulate material has a particle size (dso Sedigraph or laser diffraction) > 5 pm, preferably > 10 pm, preferably > 20 pm and has a particle size (dso sieve analysis or laser diffraction) < 3000 pm, preferably < 250 pm, preferably < 100 pm or comprises a sand whose average particle size dso (sieve analysis or laser diffraction) is in a range of 5 pm - 10 mm, preferably 10 pm - 5 mm, particularly preferably 20 pm - 1 mm.

6. Composite molded part core according to one of the preceding claims, characterized in that the particulate material comprises at least two components which differ at least in an average particle size dso (sieve analysis or laser diffraction).

7. Composite molded part core according to one of claims 2 - 6, characterized in that the composite molded part shell comprises a polymer, wherein the polymer is preferably a solid or liquid or disperse polymer, which is preferably selected from a group comprising acrylates, styrene acrylates, silanes, silicones, alkanes, alcohols, urethanes, epoxides, cellulose, methylcellulose, inorganic polymers and mixtures thereof, preferably acrylates, urethanes or epoxides.

8. Composite molded part core according to one of claims 7, characterized in that the composite molded part shell comprises at least one additive, wherein the additive preferably comprises a coloring component, preferably a dye, a color paste and / or a pigment and / or the additive has a Mohs hardness > 4, preferably > 4.5, more preferably > 5.

9. Composite molded core according to one of the preceding claims, characterized in that a value which corresponds to one hundred times the quotient of the binder content in mass percent and the theoretical specific surface in cm 2 / g (BET) of the particulate material is less than or equal to 5, preferably < 4.5, further preferably < 4, more preferably < 3.5 and particularly preferably < 3.

10. A method for producing a composite molded part, comprising the steps: Providing a composition comprising a particulate material and <15 mass percent of a binder based on the total mass of the composition, Producing a shaped composite molded part core by at least partially curing the binder, Creating a composite molded part shell which partially covers at least one surface of the composite molded part core in the composite material.

11. A method for producing a composite material according to claim 10, characterized in that the production of the composite material molded part shell takes place at a time and / or location interval from the production of the composite material molded part core and the application of one or more cover layers to the composite material molded part shell, preferably at a time and / or location interval.

12. A method for producing a composite material according to any one of claims 10-11, characterized in that the at least partial curing of the binder under Exposure to a temperature > 25°C, more preferably > 30°C, more preferably > 40°C, even more preferably > 50°C, most preferably > 60°C, and / or Exposure to a reagent, preferably gassing, preferably with an amine, and / or Exposure to electromagnetic radiation, preferably UV exposure, light exposure and / or IR exposure and / or by an added catalyst.

13. A method for producing a composite material according to any one of claims 10-12, characterized in that a surface of the composite molded part core and / or the composite molded part shell is machined, preferably mechanically machined, wherein the machining preferably comprises at least one step selected from a group comprising smoothing, grinding, brushing, dust removal, milling, drilling, polishing and deburring.

14. A method for recycling a composite molded part core according to one of claims 1-9 and / or a composite material produced according to one of claims 10-13, characterized in that a binding capacity of the at least partially cured binder is reduced such that the bond between two adjacent particles of the particulate material is eliminated, preferably upon application of pressure and / or shear force, preferably pressure and / or shear force of a mixer or stirrer.

15. A composite molded part comprising a composite molded part core according to any one of claims 1-8, wherein the molded part is preferably intended and suitable for use in the kitchen and / or sanitary area, and / or is preferably selected from a group comprising washbasins, sinks, shower trays, bathtubs, bidets, toilets, worktops, furniture or furniture parts, floor coverings, wall coverings and tiles.

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