MOLDED PART COMPRISING A CHEMICALLY BOUND PHOSPHATE CERAMIC

Description

[0001] Molded part comprising a chemically bonded phosphate ceramic.

[0002] So-called chemically bonded phosphate ceramics are used for a wide variety of applications, for example, in prosthetics, as dental cements, and in the manufacture of structural components. One important application is the production of non-combustible components that emit as few or no harmful emissions as possible in the event of a fire. For example, in the event of a fire, components made of phenolic resins and / or modified plastics such as flame-retardant unsaturated polyester resins and flame-retardant epoxy resins may emit harmful gases. These can include, for example, hydrogen cyanide, carbon monoxide, nitrogen oxides, sulfur dioxide, hydrogen fluoride, carbon dioxide, and hydrogen bromide.

[0003] EP 0 861 216 B1 describes a chemically bonded phosphate ceramic marketed under the brand name Vubonite ®. The production of molded parts made of Vubonite ® often leads to geometric distortion of the molded parts due to shrinkage. This geometric distortion and the stresses within the molded part cause hairline cracks on the surface. Furthermore, surface finishing of the molded parts, e.g., through a decorative wet application such as painting, is not possible because the surface tensions lead to adhesion failures between the surface of the molded part and the application structure.

[0004] Furthermore, Vubonite ®< does not allow for the targeted adjustment of viscosity and, in addition, exhibits a high mass density of approximately 1750 kg / m 3<. Molded parts manufactured with Vubonite ®< still only achieve a thermal insulation (thermal conductivity) of approximately 1000 mW / (m·K).

[0005] The following describes a chemically bonded phosphate ceramic that is improved over the aforementioned disadvantages. Furthermore, a composition for producing the chemically bonded phosphate ceramic, the phosphate ceramic, as well as processes for producing the phosphate ceramic and processes for producing molded parts are disclosed. The aim of the present invention is to provide molded parts from the composition.

[0006] The invention relates to the molded part defined in independent claim 1. This molded part comprises a chemically bonded phosphate ceramic, wherein the phosphate ceramic contains between 0.2 mass% and 2 mass% Al, between 0.2 mass% and 1.5 mass% Zn, and between 20 and 35 mass% CaO. A:

[0007] Composition for producing a chemically bonded phosphate ceramic with: Component A) as a liquid component comprising 50 to 100 percent by weight of a phosphoric acid compound in aqueous solution and component B) a calcium silicate, wherein the mixing ratio of component A) to component B) is 45:70 to 110:140, or 45:100 to 100:140 parts by weight.

[0008] Due to the high proportion of the phosphoric acid compound present in aqueous solution, polycondensation between the phosphate as component A) and the calcium silicate as component B) can occur particularly well, so that a chemically bonded phosphate ceramic can be formed.

[0009] A "chemically bonded phosphate ceramic" in the sense of the technical teaching described here refers to solid, ceramic-like materials that can be formed by an exothermic, energy-releasing polycondensation between phosphate components and calcium silicate components of mixtures. The curing of the chemically bonded phosphate ceramics occurs via the exothermic polycondensation reaction and does not require the high-temperature sintering step typical for other ceramic materials. During sintering, a ceramic structure is formed from granular or powdery green materials at temperatures often exceeding 800 °C and up to 2500 °C.

[0010] The composition for producing the chemically bonded phosphate ceramic is particularly well-suited for molded part manufacturing processes, such as compression molding and / or injection molding, in which the mixture of components A) and B) of the composition is introduced into the cavity of a mold. The molded part can then be cured within a few minutes using high pressures greater than 10 daN / cm² and temperatures up to 160 °C. In injection molding technology, the chemically bonded phosphate ceramic is injected into the cavity at pressures of up to 3000 bar. Other manufacturing technologies include fiber injection molding, vacuum injection, and pultrusion of continuous profiles.

[0011] For the purposes of the present invention, "molded parts" refers to all parts that can be manufactured with the chemically bonded phosphate ceramic described here, for example, 2-dimensional plates and 3-dimensional parts, such as finished components and semi-finished products, as well as laminates in which layers containing the phosphate ceramic are combined with layers of a different composition, such as mineral wool layers, metal fiber layers, or metal layers. The layers can, in particular, be layers obtained by impregnating fiber mats with the composition for the chemically bonded phosphate ceramic. The thickness of the layer structures can be varied by stacking the impregnated fiber mats, for example, using hand-laying techniques.

[0012] Component A) contains no other components besides water. By varying the proportion of water, the viscosity of the composition can be adapted for different injection molding and / or pressing processes as well as laminating processes. The proportion of the phosphoric acid compound in component A) is preferably 60 to 100 wt.% for applications such as pressing, injection molding and / or laminating processes, e.g. hand lay-up processes, and the remaining proportion is water to adjust the viscosity. For processes such as pressing and injection molding, the proportion of component A) to component B) is preferably 45:70 to 110:100 45:100 to 100:100 parts by weight and for processes in which a molded part is cast or in which foaming agents are additionally used, the proportion of component A) to B) is 100:140 parts by weight.

[0013] Furthermore, the proportion of the phosphoric acid compound in aqueous solution in component A) is preferably 70 wt% to 95 wt%, with 5 to 30 wt% being water.

[0014] The phosphoric acid compound in aqueous solution can, in particular, comprise or consist of an aqueous solution of phosphoric acid. In general, 85% or 95% phosphoric acid can be used as the phosphoric acid compound in aqueous solution for all compositions for producing a chemically bonded phosphate ceramic. Compared to the lower concentration of 85%, 95% phosphoric acid has a significantly lower water content, which is advantageous for pressed parts because the proportion of free water in the molded part is lower, thus significantly reducing the electrical conductivity (rated insulation voltage according to DIN EN 60670-12 and DIN EN 61439) in the molded part.

[0015] A further variant of a composition described here additionally comprises in component A) as a liquid component or as a combination of a liquid component with solids at least one of the following compounds: 0.2 to 10, preferably 0.2 to 7% by weight of an aluminum compound, 0.2 to 10, preferably 0.2 to 9% by weight of a zinc compound, and a boron-oxygen compound.

[0016] It is possible that only one of the above-mentioned compounds, at least two, or even all three compounds are present in the compositions described here. Due to the additional compounds, such compositions are suitable not only for injection molding and pressing but also for hand-laying processes, in which, for example, fiber layers or fiber plies, such as fiber mats made of natural fibers or mineral fibers, are introduced into a mold, impregnated with the compositions described here, and then further fiber layers can be applied and impregnated again until a desired layer thickness is achieved. For example, in impregnation systems, several fiber mats can be impregnated simultaneously with the compositions described here in a single process step.

[0017] The additional compounds can cause a controlled exothermic polycondensation reaction between the phosphate components and the calcium silicate components of the compositions described here, with the zinc compound and the aluminum compound serving as activators and accelerating the polycondensation, while the boron-oxygen compound serves as a retarder and delays the polycondensation, resulting in an extended pot life (processing time).

[0018] These compounds can either be added to the liquid component A) and dissolved therein before and / or during the mixing of component A) with component B). Furthermore, all or part of the compounds can be added as solids after the liquid component A) has been mixed with the solid component B).

[0019] Adding the compounds during mixing and / or after mixing components A) and B) has the advantage that the mixing time for adding the solids can be reduced compared to completely dissolving the solids in component A) before mixing with component B). For example, the mixing time for adding the solids to the mixture of components A) and B) can be a few minutes, while dissolving the solids in the liquid component A) can take several hours. For example, certain aluminum compounds can be difficult or impossible to dissolve, so the phosphoric acid aqueous component A) must be heated to an elevated temperature, for example, around 40 °C, for several hours.

[0020] Furthermore, the reactivity of the mixture of components A) and B) can also be controlled by adding the above-mentioned compounds as solids after mixing components A) and B) or during the mixing of both components. This is particularly advantageous when environmental influences such as changes in room temperature and / or humidity occur, to which a rapid response is required.

[0021] Furthermore, component A) may contain 0.2 to 9 wt%, preferably 1 to 9 wt%, more preferably 2 to 4 wt% of the boron-oxygen compound.

[0022] Higher proportions of the boron-oxygen compound as a retarder increase the pot life of the compositions described here and thus enable a longer processing time.

[0023] Borates, e.g. boric acid, but preferably borax Na 2 B 4 O 7 ×10H 2 0, can be used as boron-oxygen compounds.

[0024] Furthermore, the proportion of the aluminum compound in component A) can be 0.2 to 7 wt%, preferably 2 to 6 wt%.

[0025] With increasing concentrations, the aluminum compound as an activator leads to an increasingly exothermic polycondensation between the phosphate component of component A) and the calcium silicate component of component B), whereby the aluminum compound is also involved in the polycondensation, for example through the formation of aluminum phosphates.

[0026] The aluminum compound may in particular comprise oxide and / or hydroxide compounds of aluminum such as aluminum oxide Al 2 O 3 and / or aluminum hydroxide Al(OH) 3, preferably aluminum hydroxide, more preferably amorphous aluminum hydroxide.

[0027] As aluminum compounds, compounds that are practically insoluble in water and have solubilities of no more than 2 mg / l, preferably 1.5 mg / l, are generally preferred. A preferred aluminum compound is aluminum hydroxide, with amorphous aluminum hydroxide being particularly well-suited for dissolving in the liquid component A) before mixing with component B) in order to reduce or prevent flocculation of aluminum compounds during the dissolution process.

[0028] The proportion of the zinc compound in component A) can be 0.2 to 9 wt.%, preferably 1 to 6 wt.%, more preferably 1 to 3 wt.%. Higher weight percentages of the zinc compound as an activator lead to a more exothermic polycondensation reaction, whereby the zinc compound can also participate in the polycondensation, for example, through the formation of zinc phosphates.

[0029] Oxide and / or hydroxide compounds of zinc, such as zinc oxide ZnO and / or zinc hydroxide Zn(OH) 2 , are particularly suitable as zinc compounds.

[0030] In general, water-insoluble zinc compounds should be used, as they are particularly suitable for polycondensation, similar to the insoluble aluminum compounds discussed above. The insoluble zinc compounds should have a solubility of no greater than 2 mg / l in water.

[0031] The proportion of the phosphoric acid compound in aqueous solution in component A) can be in particular 50 to 75 wt.%, preferably 55 to 68 wt. Such weight percentages are particularly well suited for compositions in which molded parts of any thickness can be produced by hand-laying fiber layers by impregnating the fiber layers with the compositions described here. After curing the composition to form the chemically bonded phosphate ceramic, the fiber mats are embedded in the chemically bonded phosphate ceramic as a matrix.

[0032] In the hand lay-up process, the above-mentioned proportions of the phosphoric acid compound in component A) are particularly suitable for enabling a controlled exothermic polycondensation, in which in particular the temperature increase during the exothermic polycondensation does not exceed 20 °C / m 2< surface area of ​​the chemically bonded phosphate ceramic produced or per m 2< surface area of ​​the laminate arrangement produced with the chemically bonded phosphate ceramic.

[0033] The mixing ratio of component A) to component B) can furthermore preferably be 75:70 to 110:100, or 70:100 to 100:100, preferably 75:100 to 100:100, or 70:100 to 90:100 by weight. Particularly for pressing, the weight ratios of component A) to B) are set at 70:100 to 90:100. For the hand-laying process, ratios of 75:70 to 110:100, or 75:100 to 100:100 by weight are preferred.

[0034] According to a further embodiment of the composition described here, component A) may additionally contain a metal sulfate compound, which may also be mixed and dissolved in the liquid component A) before mixing with component B) or which may be added to both components A) and B) as a solid during or after mixing them.

[0035] The proportion of the metal sulfate compound in component A) can be 0.01 to 1 wt.%, with this metal sulfate compound preferably being selected from the sulfates of the alkali metals or combinations thereof, in particular Na, e.g., Na 2 SO 4 or K 2 SO 4 . Compared to the zinc compound or the aluminum compound, the metal sulfate compound has a lower effect on the exothermicity of the exothermic polycondensation, which allows the reaction rate to be influenced more specifically.

[0036] Component A) may additionally contain a metal halide compound, the proportion of which in component A) may be 0.01 to 1 wt.%. NaBr or NaCl can be used as the metal halide compound, although potassium or cesium compounds of the bromides or chlorides are also possible.

[0037] According to a further embodiment of the present composition, the calcium silicate of component B) can be selected from wollastonite, in particular β-wollastonite.

[0038] Wollastonite is a naturally occurring mineral with the chemical composition Ca 3 [Si 3 O 9 ]. Its crystal structure features SiO 3 2-< chains linked by calcium ions, forming a single-chain silicate belonging to the inosilicate group. The softening point of β-wollastonite is above 1500 °C, allowing it to be used for the production of refractory molded parts.

[0039] According to a further embodiment of the present composition, the calcium silicate or wollastonite may have a grain size D 50 of < 70 µm, preferably 5 µm - <50 µm, in particular 5 to 25 µm.

[0040] The inventor has recognized that, with an otherwise identical composition of component A) and a constant stirring speed during mixing of components A) and B), the temperature increase of the exothermic reaction can be controlled by adding calcium silicates of different grain sizes as component B). The exothermicity of the polycondensation reaction increases with decreasing grain size D 50 of the calcium silicate particles. A further advantage is that homogeneous and stress-free surfaces can be achieved.

[0041] Foamed molded parts can also be produced using the compositions described here. The grain size D 50 of the calcium silicate, especially wollastonite, determines, among other things, the structure of the cells with gas inclusions created in the foamed, chemically bonded phosphate ceramic. The size of these cell structures can be influenced by the addition of the foaming agents described below.

[0042] For the production of foamed chemically bonded phosphate ceramics with reduced densities, component A) may further contain a foaming agent, preferably hydrogen peroxide H 2 O 2 and / or water mixed with carbonic acid H 2 CO 3 .

[0043] The addition of foaming agents allows the chemically bonded phosphate ceramic to foam through the release of oxygen in the case of hydrogen peroxide or carbon dioxide in the case of carbonic acid. The density of the chemically bonded phosphate ceramic can be reduced from values ​​in the unfoamed state of approximately 1750 kg / m³ to below 300 kg / m³, depending on the proportion of foaming agent. For this purpose, the foaming agents can be added in a proportion of up to 40% by weight of component A). Weight savings are particularly crucial for molded parts that must be lightweight, such as components in shipbuilding or aircraft construction. Hydrogen peroxide can be added in a concentration of up to 50% by weight.

[0044] For the production of fire-resistant components for ceilings, walls, and floors, for example in shipbuilding, aircraft construction, rail vehicle construction, building construction, and tunnel construction, halogen-free compositions are also sought, for example to prevent the evolution of HBr or HCl in the event of a fire. Therefore, it is further advantageous that certain compositions described here, which serve to produce a halogen-free, non-combustible, chemically bonded phosphate ceramic, are free of halogen compounds. In particular, both components A) and B) are halogen-free according to a further embodiment. For the production of refractory molded parts, the composition described here also contains no organic compounds according to a further embodiment. This makes it particularly easy to produce refractory, inorganic, chemically bonded phosphate ceramics that are temperature-resistant at elevated temperatures up to 1500°C and higher.

[0045] According to a further embodiment of the composition described here, it consists exclusively of components A) and B) and thus contains no other components. This means that, apart from the above-described compounds of components A) and B), no further compounds are present in the compositions described here. For example, unlike phosphate ceramics known from the prior art, the compositions described here can therefore not contain any zirconium compounds, for example ZrO 2 , or iron oxide compounds. This allows for a technically less complex and more cost-effective production of the compositions described here.However, it should be noted that even if no targeted addition of iron oxide compounds to components A) and B) of the composition is made, the cured phosphate ceramic described here may still contain minimal amounts of iron oxide in the order of 0.1 to 0.4 mass%, since this oxide may be present as an impurity, for example, in wollastonite.

[0046] A process for producing a chemically bonded phosphate ceramic using one of the above-mentioned compositions is also described, comprising the following process steps: A) Mixing of components A) and B), B) Hardening of the mixture of components A) and B) to form the chemically bonded phosphate ceramic.

[0047] In process step A), component B) is preferably introduced into the liquid component A) as a solid component of a calcium silicate. It is advantageous if the mixture is stirred, with mixing times ranging from one minute to less than 10 minutes, preferably 2.5 to 3 minutes, and the stirring speed being 500 to 5000 rpm, preferably 1000 to 3000 rpm, more preferably 2000 to 3000 rpm.

[0048] In process step A), after mixing component B) with the liquid component A), further solid components of component A) can be introduced into the mixture, for example the compounds already described above, the aluminum compound, the zinc compound, the metal sulfate compound, or the boron-oxygen compound. This has the advantage that adding the solid components of component A) during mixing of components A) and B) or after their mixing can result in a shorter mixing time. Alternatively, it is also possible to first dissolve all components present as solids in the phosphoric acid liquid compound of component A) and then mix with component B).

[0049] In a further variant of a described process for producing a chemically bonded phosphate ceramic, during process step A) after mixing components A) and B), compounds selected from: Foaming agents, fibers, polyester pastes with unsaturated polyester resin, water, fillers, or combinations of these compounds.

[0050] Foaming agents, preferably hydrogen peroxide and / or carbonic acid, for example in the form of carbonated water, can preferably be added in a proportion of 2 to 10 wt% based on the total mixture A) and B) in order to achieve foaming of the chemically bonded phosphate ceramic as already described above.

[0051] Adding foaming agents after mixing components A) and B) results in a longer stirring time and thus a reduced processing time (pot life). To prevent a reduced pot life, the foaming agent can also be added directly to the liquid component A), as described above. To enhance the effectiveness of hydrogen peroxide as a foaming agent, it is recommended to add it in staggered steps.

[0052] Mineral fibers and natural fibers are preferred as fibers. Natural fibers include cotton fibers, hemp fibers, flax fibers, sisal fibers, vulcanized fibers, and thermoplastic fibers, or combinations of these. Vulcanized fibers, for example, can be made from cellulose fibers treated with zinc chloride. Sisal fibers are obtained from the leaf fibers of some agave species.

[0053] Examples of mineral fibers that can be used include glass fibers, carbon fibers, basalt fibers, or rock wool fibers, as well as a combination of these fibers. Furthermore, mineral fibers and natural fibers can also be combined. The fibers are preferably added in a proportion of up to 70 vol%, approximately 2 to 30 wt%, of the total mixture of components A) and B). Metal fibers can also be used. The fibers allow for the reinforcement of molded parts, i.e., targeted structural strength of molded parts and the maintenance of the integrity of the component design over long periods of time in the high temperature range that comply with standards. The fibers are embedded in the chemically bonded phosphate ceramic as the matrix material.

[0054] Polyester pastes with unsaturated polyester resin can preferably be present in a styrene solvent and contain less than 65% by weight of color pigments. Especially in the case of foamed chemically bonded phosphate ceramics described here, the addition of the polyester paste in a proportion of up to 3% by weight, preferably 0.3 to 2.2% by weight, can result in an improved cell structure and color variation of the foamed material.

[0055] To adjust the viscosity of the mixture of components A) and B), water can also be added as required in a proportion of preferably 2 to 15% by weight of the total mixture A) and B).

[0056] Fillers can be selected, for example, from materials such as fly ash, hollow glass bodies, expanded glass granules, expanded polystyrene and sand and can be added in a proportion of less than 30% by weight, preferably 20% by weight, of the mixture A) and B).

[0057] The stirring times for the additional stirring of these compounds into the mixture of components A) and B) can be up to 10 minutes, preferably one to three minutes.

[0058] In a further variant of a process described here, after the mixing of components A) and B), an exothermic reaction takes place to form the chemically bonded phosphate ceramic, wherein this exothermic reaction is controlled and the temperature during the exothermic reaction does not rise by more than 20 °C, preferably not more than 17 °C and more preferably not more than 12 °C, per m 2< surface of the chemically bonded phosphate ceramic produced.

[0059] As already described above, when components A) and B) are mixed, an exothermic polycondensation occurs at least between the phosphate component and the calcium silicate component. Other compounds present, such as the zinc compound or the aluminum compound, the metal sulfate compound, and the boron-oxygen compound, may also participate in the polycondensation. By adjusting the weight percentage of component A) and adapting the grain size D 50 of the calcium silicate solid particles of component B), a controlled chemical polycondensation can occur, in which the temperature does not rise by more than 20 °C, especially without cooling.Such a controlled exothermic polycondensation reaction is particularly advantageous in the hand-laying processes already described above, in which fiber mats or fiber layers are impregnated with a mixture of components A) and B) and these mixtures are then cured, whereby, depending on the number of fiber layers, stress-free and dimensionally stable molded parts of different thicknesses can be produced.

[0060] It was found that increasing the weight percentage of the phosphoric acid compound in aqueous solution in component A) increases the temperature increase (exothermicity) of the polycondensation reaction. Likewise, increasing the weight percentage of the zinc compound and the aluminum compound in component A) results in increased heat generation during polycondensation. However, this effect of both compounds is less pronounced than that of the phosphoric acid compound, and thus these compounds, as well as the other solids described above, allow for fine-tuning of the controlled exothermic polycondensation reaction.

[0061] Increasing the proportion of the boron-oxygen compound, preferably borax, as a retarder primarily leads to an increased pot life.

[0062] As already described above, with the same composition of component A) and constant stirring time and stirring speed, the exothermic reaction of the polycondensation can also be intensified by reducing the grain size D 50 of the calcium silicate particles.

[0063] Due to the controlled exothermic reaction, dimensionally accurate, stress-free molded parts can be produced, which exhibit no shrinkage or surface tension. This shrinkage and surface tension create adhesion failures with an application material, such as a paint, and exhibit hairline cracks in the surface matrix.

[0064] To carry out a controlled exothermic polycondensation, component A) preferably contains: 50 to 75% by weight, preferably 55 to 68% by weight, of the phosphoric acid solution, and - if present - 0.2 to 9% by weight, preferably 1.5 to 5% by weight, of the zinc compound, 0.2 to 7% by weight, preferably 4 to 6% by weight, of the aluminum compound and 0.2 to 9% by weight, preferably 2 to 9% by weight, of the boron oxygen compound, wherein the mixing ratio with component B), the calcium silicate, is 75:70 to 110:100, furthermore 70:100 to 100:100 parts by weight.

[0065] If the metal sulfate compound is also present, it is used in a proportion of 0.2 to 4 wt% of component A) in order to enable a controlled exothermic polycondensation.

[0066] Varying the weight proportions of these compounds within these limits makes it particularly easy to achieve a controlled exothermic reaction. In principle, however, a controlled exothermic polycondensation can also be achieved by varying the above-mentioned compounds of component A) in larger weight percentages, as described above.

[0067] Furthermore, a method for producing a two-dimensional or three-dimensional laminate arrangement using one of the compositions described above is described, comprising the process steps: A1) Mixing components A) and B), B1) Applying the mixture of components A) and B) to the at least one first fiber layer, and C1) Curing the mixture of components A) and B) to form the component with the chemically bonded phosphate ceramic and the at least one first fiber layer.

[0068] Such a process is particularly well suited for use as a so-called hand-lay-up process for producing laminates in which a first fiber layer is embedded in a matrix of chemically bonded phosphate ceramic. Mixtures of components A) and B) are particularly advantageous, as they enable a controlled exothermic reaction as described above, so that even using the hand-lay-up process, dimensionally accurate, stress-free molded parts with homogeneous (stress-free) surfaces and laminate arrangements can be produced particularly easily.

[0069] The two- or three-dimensional laminate arrangement can, for example, be a plate as a two-dimensional laminate and a component or a semi-finished product as a 3D laminate.

[0070] A variation of the above-mentioned process using a second fiber layer includes the additional process steps: B2) the second fiber layer is applied to the first fiber layer after process step B1), B3) the mixture of components A) and B) is applied to the at least second fiber layer, wherein in process step C1) the mixture of components A) and B) is cured to form the component comprising a chemically bonded phosphate ceramic with at least the first and second fiber layer.

[0071] Using such a process, at least a second fiber layer can be arranged on the first fiber layer, thus determining the thickness of the laminate assembly to be produced. Using the process described here, any desired additional fiber layers can be arranged on already impregnated layers and then dried by curing. This hand-laying method can also be used to produce fire-resistant molded parts that can exhibit low thermal conductivities of less than 110 mW / (m K) and in which targeted delamination can occur (see a more detailed description of these components below).

[0072] The fiber layers can in particular be mineral fiber layers or natural fiber layers.

[0073] Furthermore, in the above-mentioned manufacturing process, in process step C1), the mixture of components A) and B) can be exposed to microwave radiation.

[0074] The microwave radiation causes the molded parts to dry within a very short time, usually 10 to 30 seconds, resulting in a very good surface quality without surface tension.

[0075] The microwave radiation can preferably comprise radiation with an energy density of 4 to 60 kW / m3. Essentially, two different frequencies can preferably be used: firstly, a frequency of 915 MHz with a power of less than 125 kW and, secondly, radiation with a frequency of 2.45 GHz with a power of < 30 kW.

[0076] The use of microwave radiation described here can be applied to molded parts in which only the chemically bonded phosphate ceramic is present, possibly together with fibers or fiber layers embedded therein, but it can also be used when layers comprising the chemically bonded phosphate ceramic are arranged on mineral wool layers.

[0077] "Mineral wool layers" generally refers to layers made of mineral fibers. Mineral wool layers can be, for example, glass wool layers or rock wool layers. Rock wool layers can be made from raw materials such as spar, dolomite, basalt, diabase, anorthosite, and recycled materials.

[0078] In the presence of mineral wool layers, the application of microwave curing causes water from the uncured mixture of components A) and B) to penetrate the fibers of the mineral wool layer, pulling the material mixture along with it. This results in better adhesion of the layer of chemically bonded phosphate ceramic formed by curing to the adjacent mineral wool layer. The penetration depth into the mineral wool layer is approximately 0.8 to 1.2 mm and, with regard to the adhesion of both layers, meets the requirements of DIN EN 1607 and DIN EN 12430.

[0079] The adhesion between the chemically bonded phosphate ceramic layer and the mineral wool layer can be so high that the mineral wool layer tears during the tensile test according to DIN EN 1607 and no delamination occurs between the ceramic layer and the mineral wool layer, which shows that in these cases the cohesion within the mineral wool layer is lower than the adhesion to the chemically bonded phosphate ceramic layer. This occurs particularly when there are no deliberately introduced gaps between the phosphate ceramic layer and the mineral wool layer, which would lead to deliberate delamination in the event of a fire at high temperatures (see description below, also with regard to Figure 2 ).

[0080] Such composite materials, consisting of a mineral wool layer and a phosphate ceramic layer arranged on top, do not require any adhesive layers between them. Conventional components often have adhesive layers between the phosphate ceramic layer and the mineral wool layer.

[0081] In a further variant of a described method for producing a molded part or a composite material, a metal layer, preferably a light metal layer, is additionally used, wherein the density of the metal can be below 3 g / cm 3 . This metal layer is preferably embedded in the phosphate ceramic layer, which can additionally comprise fibers or fiber layers.

[0082] The advantage of metal layers, especially light metal layers, is that they significantly increase the strength of partition walls, semi-finished products, and components with such metal layers. The use of light metal layers, which can also be light metal honeycombs, such as aluminum honeycombs, allows for the production of particularly stable components, such as partition walls, that are also very lightweight. Aluminum, in particular, can be used as a light metal.

[0083] Instead of the hand-laying process, two- or three-dimensional molded parts can also be produced using one of the above-mentioned compositions by a variant of a process described here comprising the following process steps: A2) Mixing components A) and B), B2) Introducing the mixture of components A) and B) into the cavity of a mold, and C2) Curing the mixture of components A) and B) to form the molded part with the chemically bonded phosphate ceramic.

[0084] Such a process can be used to produce molded parts by pressing or injection molding. In pressing or injection molding, a mold is used that is at least two-part, but also multi-part, and has a cavity into which the mixture of components A) and B) is introduced. The cavity, together with other components of the molding tool, such as concave dies, forms a negative mold for the desired final shape of the molded part. The material inserts are often made of stainless steel or tool steel with PTFE, either by spraying or in film applications. The tools can be heated up to 160 °C, and the internal pressure in the molds can be > 10 daN / cm²<. The mold holding time of the mixture in the mold is up to 15 minutes, preferably about three to 10 minutes, depending on the structure of the cavity and the formulation of the mixtures A) and B).

[0085] Also described is a molded part comprising a chemically bonded phosphate ceramic, wherein the phosphate ceramic contains between 0.2 mass% to 2 mass% aluminum and between 0.2 mass% to 1.5 mass% zinc.

[0086] It was found that such chemically bonded phosphate ceramics exhibit reduced values ​​for aluminum, especially for zinc, compared to conventional, commercially available Vubonite ®< phosphate ceramics. Conventional Vubonite ®< phosphate ceramics typically contain more than 2.7 mass% Zn.

[0087] The mass percentages of these elements and other elements can be analyzed, particularly using inductively coupled plasma mass spectrometry (ICP-MS). This makes it particularly easy to distinguish between the phosphate ceramics described here and conventional phosphate ceramics in cured coatings with chemically bonded phosphate ceramics.

[0088] The phosphate ceramics described here preferably contain between 0.5 mass% to 1.4 mass% aluminum and between 0.5 mass% to 1.2 mass% zinc.

[0089] Furthermore, the molded part with the chemically bonded phosphate ceramic can contain between 6 to 18 mass% phosphorus, preferably between 7 to 12 mass% P, as determined by ICP-MS.

[0090] Furthermore, the molded part may contain between 0.23 and 0.35 mass% Na, as determined by ICP-MS. This element can be introduced into the chemically bonded phosphate ceramic primarily through the metal sulfate compound and, if present, the metal halide.

[0091] The mass% of B determined by ICP-MS can range from 0.15 mass% to 0.35 mass%.

[0092] The phosphate ceramic in the molded part may also additionally contain between 16 and 38 mass%, preferably 20 to 35 mass%, more preferably 25 to 30 mass%, of silicon dioxide SiO 2. According to the invention, calcium oxide CaO is present in the preferred mass percentages of SiO 2.

[0093] Different mass% of CaO and SiO 2 may be due primarily to different sources of supply for component B), especially wollastonite, since the proportions of these two oxides vary between different mining regions.

[0094] Since, as described below, the analysis of the elements Si and Ca by ICP-MS is subject to significant error, these elements can be better determined by X-ray fluorescence analysis (XRF) in an oxide matrix, which yields the mass percentages of the oxides of the corresponding elements. However, the mass percentages of the other elements Al, Zn, and P, which were determined by ICP-MS, could be confirmed by XRF.

[0095] For refractory phosphate ceramics that do not release harmful halogen-containing emissions in the event of fire, the phosphate ceramic of the molded part contains less than 0.001 mass% of a halogen, usually chlorine or bromine, and is preferably completely halogen-free.

[0096] Furthermore, it is preferred that the phosphate ceramic does not contain any organic components, as already described above.

[0097] Due to the described phosphate ceramic material, the molded parts according to the invention can be manufactured stress-free, so that the surface of the components is stress-free. This means, in particular, that the surface of these molded parts is free of hairline cracks or adhesion fractures. Furthermore, the phosphate ceramic layer can be applied to mineral wool layers in a particularly thin layer, with a thickness of 0.8 to 1.8 mm, preferably 1 to 1.5 mm.

[0098] The molded parts according to the invention with the described chemically bonded phosphate ceramics can further comprise an adjacent mineral wool layer. The bonding of the mineral wool layer to the phosphate ceramic can be achieved by wetting the mineral wool layer with the phosphate ceramic. In particular, the penetration depth of the phosphate ceramic into the mineral wool layer can be between 0.8 and 1.2 mm and, with regard to adhesion requirements, can comply with the DIN EN 1607 standard.

[0099] As already described above, microwave drying can inject water into the mineral wool layer, thereby creating a particularly stable bond between the mineral wool layer and the chemically bonded phosphate ceramic layer. Conventional composite materials often have an adhesive layer between the mineral wool layer and the phosphate ceramic layer, which is not necessary for the phosphate ceramic layers described here.

[0100] The chemically bonded phosphate ceramics described here can be used to produce particularly fire-resistant molded parts that meet at least IMO FTP Code B15 to A60 standards in shipbuilding, as well as DIN EN 13501 standards in building construction and DIN EN 45545 standards in rail vehicle construction. These molded parts can exhibit low thermal conductivities of less than 110 mW / (m·K).

[0101] In the following, the invention and the compositions described here will be explained in more detail using exemplary embodiments and figures.

[0102] The Figures 1 to 4 show various embodiments of molded parts or laminate arrangements containing layers with the phosphate ceramic according to the invention, in cross section.

[0103] Figure 5 shows a surface photograph of a component made of a conventional phosphate ceramic with hairline cracks.

[0104] Figure 1shows a section of a component 1 having a layer 2 comprising the chemically bonded phosphate ceramic material 2a described here. This ceramic material serves as a matrix for fiber materials 2b. Instead of fibers, fiber mats or fiber layers can also be embedded in the phosphate ceramic material as a matrix. Furthermore, a light metal layer, for example an aluminum honeycomb 4, is embedded in the phosphate ceramic layer 2. Adjacent to the phosphate ceramic layer 2 is a mineral wool layer 3, wherein a small portion 3a of the mineral wool layer is impregnated with the phosphate ceramic with a penetration depth of typically 0.8 to 1.2 mm, and a larger portion 3b is not impregnated with the phosphate ceramic. This results in a particularly strong bond between the mineral wool layer 3 and the phosphate ceramic layer 2.Such components can be installed as so-called lightweight components, for example in ships, rail vehicles or aircraft.

[0105] Figure 2shows a cross-section of a fire-resistant component 1, which also contains a layer 2 with the chemically bonded phosphate ceramic 2a according to the invention, which in this case serves as a matrix for fiber layers 2b. By partially drying the phosphate ceramic layer, for example before microwave irradiation, gaps 5 can be created between the phosphate ceramic layer 2 and the underlying mineral wool layer 3. In the event of a fire, at temperatures above 700°C, the gaps can particularly easily lead to delamination of the phosphate layer from the mineral wool layer, so that a channel forms between the two layers, which forms a gas insulation.This passage can redirect hot fire gases into the fire chamber so that in the event of a fire, the temperature of the side 3c of the component facing away from the fire, namely the side of the mineral wool layer facing away from the phosphate layer, is not increased unduly.

[0106] The mineral wool layer 3 has a similar Figure 1 again, a larger layer area 3b not impregnated with the phosphate ceramic, as well as a small layer 3a, characterized by a penetration depth of 0.8 to 1.2 mm, which is impregnated with the phosphate ceramic. A larger portion 3b of the mineral wool layer 3 is not impregnated with the phosphate ceramic.

[0107] Figure 3 shows in cross-section a variant of a simple molded part in which only a layer 2 containing phosphate ceramic is present, with fiber layers 2b being embedded in the phosphate ceramic 2a.

[0108] Figure 4shows, in cross-section, another embodiment of a molded part according to the invention, in which a layer 2 containing phosphate ceramic is present, which was cured by foaming with foaming agents. Internal cavities, the cells 2c, form in the phosphate ceramic layer 2a, which significantly reduce the density of the layer and thus enable significant weight savings.

[0109] Figure 5 shows a top view of the surface of a conventional molded part manufactured with the phosphate ceramic marketed under the brand name Vubonite®. Hairline cracks 6 are clearly visible, indicating that the surface of this component is not stress-free. In contrast, the surfaces of molded parts according to the invention do not exhibit hairline cracks due to their stress-free nature. 1. Embodiments of described here Components A):

[0110] The following table shows the compositions of four different embodiments A1) to A4) of component A) in wt% of component A), which can be used to produce phosphate ceramics described here (due to rounding to the second decimal place, the sum of the compositions may deviate from 100 wt%): Table 1: component H 2 0 H3PO4 ZnO Amorphous Al(OH) 3 Na 2 B 4 O 7 × 10 H 2 O NaBr NaCl Na 2 SO 4 A1) 26,03 63, 61 2,19 4, 86 2,84 0,41 - 0, 06 A2) 24,40 65,36 2,16 4, 80 2, 80 0, 41 - 0.06 A3) 26,03 63, 61 2,19 4, 86 2,84 - 0,41 0,06 A4) 26, 44 63, 61 2, 19 4,86 2,84 - - 0,06

[0111] Component A4) is of particular interest because it is halogen-free and therefore particularly suitable for the production of fire-resistant, halogen-free molded parts.

[0112] Furthermore, Na 2 SO 4 can be omitted from all components A1) to A4). This is particularly advantageous when a foamed structure of fine quality is required that can also be easily painted.

[0113] These components can be prepared by adding aqueous phosphoric acid and then dissolving the individual components in the aqueous phosphoric acid while stirring and, if necessary, heating. 2. Process of a controlled exothermic polycondensation during curing of a mixture of components A) and B)

[0114] In the following, four different samples (1 to 4) of mixtures A) and B) were mixed and applied to an area of ​​0.0122 m². Component A1) described in Table 1 was used as component A, and component B) was ß-wollastonite as a solid with a grain size D 50 < 70 µm. Mixing ratios and other test parameters can be found in the following table: Table 2: Sample 1 Sample 2 Sample 3 Sample 4 A1) B) A1) B) A1) B) A1) B) temperature RT (approx. 21°C) - RT (approx. 21°C) - RT (approx. 21°C) - RT (approx. 21°C) - Mixing ratio 100 80 100 80 100 80 100 80 Batch quantity [g] 100 80 200 160 400 320 800 640 l / min. ~ 1.000 ~ 1.000 ~ 1.000 ~ 1.000 Stirring time [sec.] 180" 180'' 180" 180''

[0115] The temperature of the mixtures was measured continuously using the ebro EBI 40 TC-01 measuring device.

[0116] For all samples, the temperature rose from approximately 25°C to a maximum of 31°C after mixing over a period of approximately 2.5 hours. Thus, a controlled exothermic polycondensation took place, during which the temperature did not rise by more than 20°C per m 2< surface area of ​​chemically bonded phosphate ceramic formed. Table 3: Sample 1 Sample 2 Sample 3 Sample 4 Components A1) B) A1) B) A1) B) A1) B) temperature RT (approx. 23°C) - RT (approx. 23°C) - RT (approx. 23°C) - RT (approx. 23°C) - Mixing ratio 100 100 100 100 100 100 100 100 Batch quantity [kg] 1,35 1,35 1, 90 1, 90 2,55 2, 55 3, 75 3,75 Stirring time [sec.] 180 180 180 180 Layer structure 1 m 2< area 2 fiber layers 3 fiber layers 4 fiber layers 5 fiber layers

[0117] Temperature sensors were positioned at each of the four corners of each sample over an area of ​​0.64 m². After mixing, the temperature of all samples rose from approximately 26 °C to a maximum of 35 °C over a period of approximately 2.0 to 3.5 hours. Thus, a controlled exothermic polycondensation reaction occurred, with the temperature of the chemically bonded phosphate ceramic formed increasing by no more than 20 °C. 3. Elemental analyses of chemically bonded phosphate ceramics:

[0118] The following table lists elemental analyses of molded parts according to the invention (samples 5 to 9) produced by curing a mixture of component A4) described in Table 1 in a weight ratio of 100:100 with ß-wollastonite as component B). These materials described here are compared in the elemental analysis with molded parts (samples 1 to 4) produced with the conventional phosphate ceramic Vubonite ®: Table 4 (Proportions of elements in mass%): sample Al* N / a* CaO** SiO2 ** Zn* P* Br* S* B* 1 1,34 0,23 25-30 25-30 2, 87 11,22 < 0,01 < 0, 01 0,21 2 1,12 0,23 " " 2, 79 10,84 < 0,01 < 0, 01 0,20 3 1,46 0, 31 " " 2, 89 10,91 < 0,01 < 0, 01 0,24 4 1,42 0,26 nb nb 3,22 11,22 < 0, 01 < 0, 01 0,22 5 1,02 0,29 25-30 25-30 0,86 10,81 < 0, 01 < 0,01 0, 18 6 0, 89 0,29 " " 0, 88 10,82 < 0, 01 < 0,01 0, 18 7 0, 95 0,30 " " 0, 87 11,29 < 0,01 < 0, 01 0, 19 8 1,07 0,24 " " 0, 90 10,65 < 0,01 < 0,01 0,20 9 1,00 0,25 nb nb 0, 94 11,22 < 0,01 < 0,01 0,22 nb = not determined * = values ​​determined by ICP-MS ** = values ​​determined by XRF

[0119] For the analysis of the chemically bonded phosphate ceramics, the matrix material of the phosphate ceramics was removed from between the fiber material embedded in the matrix and then digested with HNO3 / HF. After a short time, a water-clear precipitate formed, which is most likely precipitated silica. The values ​​determined for the elements Al, Na, Zn, and P by ICP-MS were confirmed by XRF analysis, while the values ​​for Si and Ca were too low, probably due to the silica precipitate. For this reason, the values ​​for SiO2 and CaO, which were determined by XRF in an oxide matrix, were included in Table 4. The values ​​for S and Br are below the detection limit for ICP-MS.

[0120] It is clearly evident that the phosphate ceramics described here contain less Al, and in particular less Zn, compared to conventional Vubonite ®< ceramics.

[0121] The invention is not limited by the embodiments.

Claims

1. Moulded part comprising a chemically bonded phosphate ceramic, wherein the phosphate ceramic contains between 0.2% by weight and 2% by weight Al, determined by mass spectrometry with inductively coupled plasma, between 0.2% by weight and 1.5% by weight Zn, determined by mass spectrometry with inductively coupled plasma, and between 20 and 35% by weight CaO, determined by X-ray fluorescence analysis.

2. Moulded part according to the preceding claim, wherein the phosphate ceramic contains between 0.5% by weight and 1.4% by weight Al and between 0.5% by weight and 1.2% by weight Zn.

3. Moulded part according to one of the preceding claims 1 or 2, wherein the phosphate ceramic contains between 6 and 18% by weight phosphorus, preferably between 7 and 12% by weight P, determined by mass spectrometry with inductively coupled plasma.

4. Moulded part according to one of the preceding claims 1 to 3, wherein the phosphate ceramic contains between 25 and 30% by weight CaO.

5. Moulded part according to one of the preceding claims 1 to 4, wherein the phosphate ceramic furthermore contains between 16 and 38% by weight, preferably 20 to 35% by weight, further preferably 25 to 30% by weight, SiO2, determined by X-ray fluorescence analysis.

6. Moulded part according to one of the preceding claims 1 to 5, wherein the phosphate ceramic furthermore contains less than 0.001% by weight of a halogen, preferably is halogen-free.

7. Moulded part according to one of the preceding claims 1 to 6, wherein the phosphate ceramic has no organic constituents.

8. Moulded part according to one of the preceding claims 1 to 7, wherein the surface of the component is stress-free.

9. Moulded part according to one of the preceding claims 1 to 8, furthermore having at least one mineral wool layer, wherein the mineral wool layer is impregnated with the phosphate ceramic.

10. Moulded part according to one of the preceding claims 1 to 8, furthermore having a mineral wool layer, adjacent to a layer containing the phosphate ceramic, wherein the bonding of the mineral wool layer to the phosphate ceramic exists due to wetting of the mineral wool layer with the phosphate ceramic.

11. Moulded part according to one of the preceding claims 1 to 8, wherein the phosphate ceramic is applied to a mineral wool layer as a layer with a thickness of from 0.8 to 1.8 mm, preferably 1 mm to 1.5 mm.

12. Moulded part according to claim 10, wherein the depth of penetration of the phosphate ceramic into the mineral wool layer is between 0.8 and 1.2 mm and corresponds to the standard DIN EN 1607 in terms of the adhesion requirements.

13. Moulded part according to one of the preceding claims 9 to 12, wherein no adhesive layer is necessary between the mineral wool layer and the phosphate ceramic.

14. Moulded part according to one of the preceding claims 1 to 8, which is fire-resistant and corresponds at least to the IMO FTP Code class B15 to A60 in shipbuilding as well as to the standard DIN EN 13501 in building construction and to the standard DIN EN 45545 in railway vehicle manufacturing.