JP7014801B2 - Use of acid-containing coating compositions in the foundry industry - Google Patents

Description

The present invention comprises the use of a coating composition in casting, in particular an aqueous phase having a pH of 5 or less and one or more refractories, as well as a coating composition each used in accordance with the present invention. With respect to the water glass coupled casting forming elements made, in particular the casting mold and / or the casting core. The present invention further relates to a method for producing a coated water glass coupled casting molding element (mold or core). The present invention also relates to a kit comprising a coating composition whose contents are used in accordance with the present invention. The present invention is defined in the appended claims.

Casting in consumable molds is an extensive method for manufacturing near-net-shaped parts, especially in metal casting. After casting, the mold is destroyed and the casting is taken out. The molds are negative, they contain cavities in which castings are performed and produce castings intended for shaping. The inner contour of future castings can be formed by cores. In the manufacture of the mold, the cavity can be molded into a molding material using a model of the cast to be manufactured. The core is usually molded in another core mold.
Mold base materials used in casting molds (also referred to as "molds" for the purposes of the present invention) and casting cores (also referred to as "cores" for the purposes of the present invention) are predominantly. Granular refractory material, such as washed graded silica sand. Other suitable mold base materials known per se are, for example, zircon sand, chromite sand, chamotte, olivine sand, feldspar-containing sand, and andalsite sand. The mold-based material can also be a mixture of mold-based materials different from those described, or a mixture of other preferred mold-based materials. The refractory mold base material is preferably in free flow form, which can be introduced into a suitable cavity where it can be compressed. The mold base material or the corresponding molding material mixture (molding material) is compressed to increase the strength of the casting mold. To produce a casting mold, the mold base material is bonded using an organic or inorganic molding material binder (binder). The molding material binder creates a strong cohesive force between the particles of the molding material and provides the mechanical stability required for the casting mold. The production of molds and cores in industrial practice is generally and advantageously carried out in a shooting machine or molding machine that compresses particulate constituents and cures the binder, which is also used in the context of the present invention. It also applies to the molds and cores that are made.

Casting molds can be manufactured using organic or inorganic molding material binders, the curing of which can be carried out by cold or hot processes, respectively. The cold process referred to by those skilled in the art is carried out at substantially room temperature without heating the casting mold. Curing in this case is usually achieved by a chemical reaction initiated by passing a catalytic gas through a molding material mixture to be cured after shaping, which mixture comprises a mold base material and a molding material binder. For hot processes, the post-molded molding material mixture is at a temperature high enough to remove, for example, the solvent present in the molding material binder, and / or a chemical reaction that cures the molding material binder, eg, chemistry by cross-linking. Heat to a temperature high enough to initiate the reaction.
A common feature of all organic molding material binders is that, regardless of their curing mechanism, when liquid metals are introduced into casting molds, they undergo pyrolysis, resulting in contaminants such as benzene, toluene, xylene, etc. It may release phenol, formaldehyde, and other pyrolysis and / or cracking products, some of which are unspecified. Various measures have been successful in minimizing these emissions, but nonetheless, at present, they cannot be completely avoided in the case of organic molding material binders.
Molding material binders that are based on inorganic materials and contain at most very low percentages of organic compounds can be used to minimize or prevent the emission of decomposition products during the casting process. This type of molding material binder system has already been known for quite some time, for example, from GB782205A, US6972059B1, US5582232A, US5474606A, and US7022178.

The term "inorganic molding material binder" is used herein in a very predominant manner, preferably up to 95% by weight, more preferably over 99% by weight, very preferably completely, a molding material consisting of water and an inorganic material. Refers to a binder, and the proportion of the organic compound in this kind of inorganic molding material binder is preferably less than 5% by mass, more preferably less than 1% by mass, and very preferably 0% by mass.
In the context of this specification, the expression "inorganically bound" means that the mold or core is bound by an inorganic molding material binder (as defined above).
Alkali metal water glass is particularly important as a constituent of the inorganic molding material binder. Alkali metal waterglass is a vitreous, in other words, amorphous, water-soluble sodium silicate, potassium silicate, and lithium silicate, mixtures thereof, and the corresponding aqueous solution, which are solidified from the melt. Point to. The term "waterglass" below refers to their amorphous, water-soluble sodium silicate, potassium silicate and / or lithium silicate and / or aqueous solutions thereof and / or a mixture of the aforementioned silicates. And / or their solutions, in each case a molar ratio (molar ratio) of SiO ₂ to M ₂ O in the range 1.6-4.0, preferably 1.8-2.5. M ₂ O represents the total amount of lithium oxide, sodium oxide and potassium oxide. The expression "waterglass bond" means that the casting molding element, more specifically the mold or core, is manufactured or can be manufactured using a molding material binder containing or consisting of waterglass. Means that. For example, US77770629B2 proposes a molding material mixture containing a water glass-based molding material binder and a particulate metal oxide as well as a refractory mold base material, and the particulate metal oxide used is preferably preferred. Precipitated silica or fumed silica.

However, compared to organic molding material binders, inorganic molding material binders also have drawbacks. For example, casting molds or cores made using known inorganic molding material binders are relatively less stable or less stable to atmospheric moisture and / or to water or watery moisture. Lower. Thus, for example, as is usual with organic molding material binders, it is not possible to reliably store such casting molds or cores for extended periods of time.

Especially in relation to steel casting, the surface of the casting forming element, more specifically the surface of the mold and core, is coated with a coating commonly referred to as a "refractory coating", especially the surface in contact with the cast metal. Here the refractory coating forms a boundary layer or barrier layer between the mold / core and the metal, especially to control the suppression of defect mechanisms in these respects, or to take advantage of metallurgical effects. .. Generally speaking, refractory coatings in casting technology have the following functions, in particular:
-Function to improve the smoothness of the casting surface;
-Function to maximize the separation of liquid metal from mold or core;
-A function to prevent chemical reactions between the mold / core constituents and the melt, thereby facilitating the separation between the mold / core and the casting; and / or-bubbles, inserts, burrs, And / or intended to serve the function of preventing surface defects in castings such as scooping.
Further functions are generally established and optimized, and / or for specific intended purposes, by the precise composition of the refractory coating or coating composition to be applied to the mold or core, as described above and where appropriate. Adapt.
Coating compositions for use in casting typically include the following components: (i) one or more fine particle refractories, ie, fine particle, fire resistant or highly fire resistant inorganic materials, and (ii) one. Or a carrier solution containing a plurality of compounds (water, alcohol, etc.) and (iii) further components such as, for example, one or more refractory coating binders (hereinafter abbreviated as "binder") and / or killing. Containing or consisting of a biological agent and / or a wetting agent and / or a rheology additive. Therefore, ready-to-use coating compositions for coating molds and cores are typically particulate, fire resistant or highly refractory in carrier fluids, such as in aqueous (hydrous) carrier fluids or non-aqueous (anhydrous) carrier fluids. It is a suspension of a sex inorganic material (refractory); see below for more information on carrier fluids.

The refractory coating or coating composition is applied to the inner contour or core of the mold by a suitable application method such as spraying, dipping, flow coating or spread and then dried onto the refractory coating or refractory coating. A coating based on a sex coating film is obtained. Coatings based on fire resistant coatings can be dried by supplying heat or radiant energy, for example by microwave radiation, or by drying in ambient air. In the case of a coating composition containing flammable compounds in the carrier liquid, it can also be dried by burning these compounds.
The term "refractory" herein can withstand exposure of molten iron to temperatures normally involved in the casting or solidification of cast iron, for at least a short period of time, in line with the usual understanding of those skilled in the art. Used to refer to compositions, materials, and minerals. The compositions, materials, and minerals referred to as "high refractory" are those that can temporarily withstand the heat of casting of molten steel. The temperature that can occur during the casting of molten steel is usually higher than the temperature that can occur during the casting of molten iron or cast iron. Refractory compositions, materials and minerals (refractory) as well as highly refractory compositions, materials and minerals are known to those of skill in the art from, for example, DIN 51060: 2000-06.

The refractory used in the coating composition is usually a mineral oxide, silicate or clay mineral. Examples of refractories that are also suitable in relation to the present invention are quartz, aluminum oxide, zirconium dioxide, aluminum silicate, bauxite, zirconium silicate, olivine, talc, mica, graphite, coke, talc, diatomaceous soil, etc. Kaolin, fired kaolin, metakaolinite, iron oxide, chromite, and bauxite, which can be used individually or in any desired combination with each other. Refractories are used, among other things, to seal holes in casting molds or cores for liquid metal insertion. In addition, refractories provide insulation between the casting mold or core and the liquid metal. Refractories are usually provided in powder form. Unless otherwise specified, the powdered refractory in that case is measured by light scattering according to an average particle size in the range of 0.1-500 μm, preferably 1-200 μm (preferably ISO 13320: 2009-10). ). Particularly suitable as refractories are materials that have a melting point at least 200 ° C. higher than the temperature of the particular metal melt used and / or do not react with the metal melt.

Refractories are usually dispersed in the carrier fluid. The carrier liquid is preferably in liquid form under standard conditions (20 ° C. and 1013.25 hPa) and / or is configurable at 160 ° C. and standard pressure (1013.25 hPa). It is an ingredient. Preferred carrier liquids that are also suitable in relation to the present invention are selected from the group consisting of water and organic carrier liquids and also mixtures thereof with each other and / or mixtures with further constituents. Suitable organic carrier liquids are preferably alcohols containing polyalcohols and polyether alcohols. Preferred alcohols are ethanol, n-propanol, isopropanol (2-propanol), n-butanol, and glycols. Water and aqueous mixtures (including aqueous solutions) are often preferred as carrier fluids.
The main purpose of the refractory coating binder (binder) is to fix the refractory present in the coating composition onto the molding material. Examples of binders that are also suitable in relation to the present invention are synthetic resins (organic polymers) or dispersions of synthetic resins such as polyvinyl alcohol, polyacrylates, polyvinyl acetates and / or corresponding copolymers of the polymers described above. Polyvinyl alcohol is preferred. Suitable binders are also natural resins, dextrins, starches, and peptides.

Biocides prevent the invasion of bacteria. Examples of biocides that are also suitable in relation to the present invention are formaldehyde, 2-methyl-4-isothiazolin-3-one (MIT), 5-chloro-2-methyl-4-isothiazolin-3-one ( CIT), and 1,2-benzisothiazolin-3-one (BIT). Biocides, preferably the individual biocides described above, are typically used in a total amount of 10-1000 ppm, preferably 50-500 ppm, based on the total mass of the immediate use coating composition in each case (which). Is intended to be applied directly to the mold or core).
Rheology additives (standardizing agents) are used to set the desired refractory coating fluidity for processing. Also suitable inorganic standardizing agents in the context of the present invention are, for example, swelling clays such as sodium bentonite, or even attapargite (parigolskite). Examples of suitable organic standardizing agents in relation to the present invention are cellulose derivatives, more specifically swelling polymers such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose; plant mucilage, polyvinyl. Includes pyrrolidone, pectin, gelatin, agar, polypeptides and / or arginates. The rheological additives or standardizing agents described above are preferred components of the coating composition used in accordance with the present invention.

Wetting agents may also be used to achieve more effective wettability of the molding material, especially in the case of aqueous coating compositions (ie, containing water as a carrier or as a component of the carrier). It is possible. Those of skill in the art are aware of ionic and nonionic wetting agents. The ionic wetting agent used is, for example, dioctyl sulfosuccinate, and the nonionic wetting agent used is, for example, an alkyne diol or an ethoxylated alkyne diol. The wetting agents mentioned above are also preferred components of the aqueous coating composition used according to the present invention.
The coating composition may further comprise an antifoaming agent, a pigment and / or a dye. The defoaming agent used can be, for example, silicone oil or mineral oil. Examples of pigments are red and yellow iron oxide, as well as graphite. Examples of dyes are commercially available dyes known to those of skill in the art. The antifoaming agents, pigments and / or dyes mentioned above are also preferred components of the coating composition used according to the present invention.

In order to meet the growing demands in the fields of environmental protection and emission protection, inorganic molding material binders, especially water glass-containing molding material binders, will be used in the future production of molds and cores in the steel casting field. It should be just as important. In order to achieve the desired or required casting quality, it is usually necessary or advantageous to coat the inorganically bonded mold and core with a refractory coating, as described above. Therefore, to protect the environment and emissions, avoid the use of organic carrier liquids as much as possible and preferably include water as a water-based refractory coating, ie as a single carrier liquid, or at least as the main fraction of the carrier liquid. Using a refractory coating is also logically valuable when choosing a refractory coating.
However, as mentioned above, casting molding elements, especially molds and cores, manufactured using an inorganic molding material binder, more specifically using a water glass-containing molding material binder, are water or water-like moisture. Has low stability to exposure to. Therefore, the water present in the water-based coating composition can damage the inorganically bound molds and cores treated (coated) with them. As a result, in particular, the strength of the mold and core thus coated can be detrimentally reduced. This particular problem known in casting techniques (see, eg, WO00 / 05010A1) is, for example, a particularly strong cure of the mold and core, an expensive and unconvenient process for drying the applied refractory coating, or Existing means used, including adaptation of molding material mixtures, are currently only poorly addressed.

Ref. WO 00/05010 describes water-based coatings, especially if the coating composition used contains certain water-soluble or water-miscible aids such as esters, carbonates, esters or lactones of polyhydric alcohols. It specifies how it can be applied to molds and cores that have been gasified with carbon dioxide and bound with sodium silicate. The individual components of the coating system are preferably mixed with each other only immediately prior to the coating procedure.
Document WO2013 / 044904A1 has a very high solid content due to the combination of specific clays as a component of a water-containing refractory coating, but nevertheless has a viscosity equivalent to that of a commercially available refractory coating for immediate use and is inorganic. It specifies the possibility of producing refractory coatings that are bonded by molding material binders and can significantly improve the quality of cores and molds coated with these refractory coatings.
Documents DE102011115025A1 and WO2013 / 050022A2 show that mixing an aqueous coating composition with a particular salt in a particular concentration range improves the quality of the coated inorganic cores and molds, and in particular the cores and molds. It is clearly stated that the storage stability of the product is clearly improved. The salts are magnesium and / or salts of manganese, especially sulfates and chlorides thereof.

Documents DE102011115024A1 and WO2013 / 050023A2 show that the addition of certain additives to the aqueous coating composition clearly improves the quality of the coated inorganic cores and molds, especially their storage stability. There is. It is an ester of formic acid (methanoic acid) that is used as an additive component of the coating composition, and the chain length of the alcohol or alcohol mixture used for esterification is particularly less than 6 on average, more preferably less than 3. It is a carbon atom of.
Document DE27350753A1 describes a composition for coating a mold used in the processing of molten metal, and a mold coated with this composition. The composition described above may include, for example, formic acid or a salt thereof.
Document DE102006040385A1 discloses a temperature-stable BN molded mold release layer based on ceramic and vitreous binders; however, this document is based on the corresponding particulate mold base material for use in casting. ) Does not disclose the use of inorganically bound templates or cores.

For the priority application to this application, the German Patent and Trademark Office searched for the following prior art: DE102006040385A1, DE102006002246A1 and DE102005041863A1.
However, as shown in our own research, even in the case of the prior art procedures described above, the problems identified above still exist to some extent.
Therefore, a further improved coating composition for use in casting intended to have or enable one or more, preferably all of the following advantageous properties, starting from the prior art. is necessary:
-The strength of the coated mold and / or core that can be produced thereby, in particular the mold and core, was produced using an inorganic molding material binder, more specifically using a water glass-containing molding material binder. Increases if compared to molds and cores coated with known water-containing refractory coatings or coating compositions;
-The storage stability of the coated mold and / or core that can be produced thereby and also the resistance to moisture in the atmosphere are compared to the mold and core coated with a known water-containing refractory coating or coating composition. And increase;
-The storage stability of the coating composition itself is not significantly impaired or further enhanced as compared to known hydrous coating compositions;
-Applying the coating composition to hot molds and / or cores (ie, especially those molds and / or cores having temperatures above 50 ° C, preferably temperatures in the range 50-100 ° C). Will be possible, or at least improved;
-The coated mold and / or core that can be produced thereby enables high casting quality and smoothness of the casting surface, preferably defect-free casting quality, more preferably defect-free casting quality;
-Inorganic bonded molding elements, especially water glass bonded casting molding elements, especially molds and / or cores, can also be used for iron and / or steel casting, or used for these purposes. The possibilities to do are expanded.

In general, an object of the present invention has been to identify coating compositions for use in casting that retain or enable one or more or all of the above properties.
Here, the main object of the present invention is to adversely affect the properties of inorganically bonded casting elements, particularly water glass bonded casting elements, preferably molds and / or cores, especially their strength. It was to make it possible to use a coating composition in casting that could be used without.

A further object of the present object is to provide a coated inorganically bonded casting molding element, in particular a casting mold and / or a casting core, comprising a coating composition to be identified in accordance with the present invention, in each case. It was to do.
A further object of the present invention is to provide a corresponding method for producing an inorganically bonded cast molding element coated with a water-containing refractory coating.
Further, an object of the present invention is to provide a kit whose contents include a coating composition specified in accordance with the present invention.

The present invention is more strictly defined or described in the appended claims. Specific and / or preferred embodiments of the invention are described more accurately below. Unless otherwise specified, preferred embodiments or embodiments of the invention may be combined with other embodiments or embodiments of the invention, in particular other preferred embodiments or embodiments. Combining the preferred embodiments or embodiments with each other also yields the preferred embodiments or embodiments of the invention in each case. With respect to the coating compositions used in accordance with the present invention, embodiments, embodiments or properties described in the context of the invention or described as preferred are, in each case, coated in the method of the invention. It is effective for molds or cores, and in correspondence with or in the same sense as the kits of the present invention.
More strictly identified embodiments, components or features "contains" or "contains", coating compositions used according to the invention, methods of the invention, coated molds or cores of the invention, and. The kits of the invention are described below, and the corresponding variants of said uses, methods, coated molds or kits, which should be understood in a narrower range, are also intended to be disclosed in each case. And said variants "consisting of" these embodiments, components or features are more precisely defined in each case.
According to the present invention, the above-mentioned further embodiments of main purpose and general purpose are for producing a coating on a water glass binding mold or on a water glass binding core for use in casting.
(A) With one or more refractories,
(B) Use of a coating composition comprising an aqueous phase having a pH of 5 or less, preferably 4 or less.
A waterglass binding template or a waterglass binding core is achieved by use, including particulate amorphous silicon dioxide.

Waterglass-bonded molds or water-glass-bonded cores, as well as particulate amorphous silicon dioxide, usually have a relatively large amount of conventional molding base material. See above for the selection of preferred mold-based materials.
The refractory material in the coating composition (see component (a)) is preferably quartz, aluminum oxide, zirconium dioxide, aluminum silicate, bauxite, zirconium silicate, olivine, talc, mica, graphite, coke. One or more substances selected from the group consisting of talus, diatomaceous earth, kaolin, calcined kaolin, metakaolinite, iron oxide, and bauxite.
For the purposes of the present invention, the pH in the coating composition is determined in each case from the suspension, or preferably from the suspension according to standard method DIN 19260: 2012-10.
The cast molding element that can be coated (coated) with the coating composition of the present invention can be manufactured by any desired method known per se, for example by shooting, casting or 3D printing techniques.

While no guarantee of accuracy is given, when the aqueous coating composition of the invention is used accordingly, the water fraction of the coating composition is a coated water glass bonded casting molding element (mold or core). Means that the bond structure in the alkali metal silicate skeleton will be attacked and further chemical reactions such as acid-base reactions will result in weakening of the bond structure and the bond structure will probably be temporarily eliminated again. However, in the end, the strength is increased in the portion of such a coated waterglass coupled casting element as compared to the prior art.
A coated waterglass bond comparison mold manufactured under the same conditions except that the comparative coating composition obtained from the coating composition by adding sodium hydroxide until the pH reaches 7 is used. Alternatively, the coated water glass bond mold or the coated water glass bond core has less bending strength when dried as compared to the coated water glass bond comparative core. It is preferable to use by. Of particular technical relevance in industrial practice are, in fact, these "acidic" coating compositions (ie, those comprising an aqueous phase having a pH of 5 or less, preferably 4 or less). The "alkali" (pH 7 and above) homogeneity results in a coated waterglass binding mold or core showing a significant reduction in bending strength upon drying.

A coated waterglass bond comparison mold manufactured under the same conditions except that the comparative coating composition obtained from the coating composition by adding sodium hydroxide until the pH reaches 7 is used. Or the coated waterglass binding mold or the coated waterglass binding core is further used by the present invention in that it has increased storage stability as compared to the coated waterglass binding comparison core. preferable.
In the context of the use of the coating composition according to the invention, the water glass binding template or water glass binding core comprises particulate amorphous silicon dioxide.
The term "particulate amorphous silicon dioxide" refers to particulate synthetic silicon dioxide, preferably precipitated silica and / or fumed silica, in the context of the present invention. Fumed silica is preferred.

Precipitated silica is known in itself and can be obtained by a method known in itself, for example, by reacting an aqueous alkali metal silicate solution with a mineral acid. Subsequently, the resulting precipitate is separated, dried and, if appropriate, ground. Fumed silica is also known in itself, and can be obtained by solidification from the gas phase at a high temperature, preferably by a method known in itself. Fumeed silica forms silicon monoxide gas by reducing silica sand, for example, by flame hydrolysis of silicon tetrachloride, or for the purposes of the present invention, preferably with coke or smokeless charcoal in an arc furnace. It can be produced by subsequent oxidation to form silicon dioxide. Another preferred form of particulate amorphous silicon dioxide according to the invention is obtained during the production of zirconium dioxide. A further possibility known per se for producing particulate amorphous silicon dioxide is the spraying of molten silicon dioxide. The primary amorphous silicon dioxide particles in this case are formed without a grinding operation (as in other preferred manufacturing methods).
After the manufacturing operation identified above, the primary amorphous silicon dioxide particles (“primary particles”) are often in agglomerate form, i.e., present as agglomerates of the primary particles. The particle shape of the primary particles of particulate amorphous silicon dioxide is preferably spherical. Spherical primary particles can be observed, for example, by a scanning electron microscope. Preferably, the primary particles of particulate amorphous silicon dioxide are spherical and have a sphericity of 0.9 or greater as determined by evaluation of a two-dimensional microscope (preferably a scanning electron microscope) image.

Waterglass-bonded molds and cores, including those containing particulate amorphous silicon dioxide (as well as conventional mold-based materials), and their manufacture are known per se from, for example, WO2006 / 024540 and WO2009 / 056320. .. The aforementioned templates and cores, which are known per se, are suitable for the purposes of the present invention.
According to one embodiment, similarly preferred is the aqueous phase (b).
It comprises (b1) water and (b2) one or more acids having pKa <5, more preferably pKa <4.
Preferably, the volume of the component (b1) to the mass of the component (b2) is in the range of 10: 1 to 200: 1, more preferably in the range of 10: 1 to 100: 1. The invention or preferred use of the invention.
In the preparation of a coating composition for use in accordance with the present invention, the one or more acids are in the usual form, i.e., in solid or liquid form, optionally diluted, preferably diluted with water to form the coating composition. Can be mixed with the additional constituents of the component (in other words, in particular the refractory of component (a) and water of component (b1)) to set or reach the desired pH.

Certain preferred ratios of material (b1) to (2) are effective as long as one or more acids of component (b2) are selected from the group of organic acids, as described in more detail below. The mass of the constituent (b2) in this case is, in each case, related to the total mass of one or more pure organic acids (ie, not including adhering material or crystalline water). do. When an acid has more than one pKa value (eg, citric acid), the pKa referred to for the purposes of the present invention is the lowest (first) pKa in each case.
In a further embodiment of the present invention or preferred use of the invention of the coating composition, the ratio of the mass of the constituent (b1) to the total mass of the aqueous phase (b) is preferably greater than 50%, more preferably greater than 70%. Very preferably over 90%.

In another preferred embodiment of the present invention or preferred use of the invention of the coating composition, the aqueous phase preferably has a pH of 4 or less.
In general, it is preferred to use the present invention in which two or more preferred embodiments are realized at the same time.
Particularly preferred combinations of the preferred parameters, properties, and constituents of the invention are generally apparent from the appended claims.
One particularly preferred variant is the use of the present invention or preferred invention of the coating composition, wherein the constituent (b2) comprises one or more acids selected from the group consisting of inorganic and organic acids. The organic acid described above in this case preferably comprises a group consisting of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids, preferably monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids that are solid at 25 ° C. and 1013 mbar (or 1013 hPa). Be selected. Particularly preferably, the organic acid is selected from the group consisting of citric acid and oxalic acid. The above-mentioned inorganic acid is preferably selected from the group consisting of hydrochloric acid, nitrate, phosphoric acid, and acidic phosphates such as aluminum phosphate, and more preferably from the group consisting of hydrochloric acid, nitrate, and phosphoric acid.
It is preferable to use an organic acid in the constituent (b2) or in combination with one or more inorganic acids as the component (b2). Particularly preferred is the use of organic acids in or as a constituent (b2).

In the above-mentioned preferred modification of the use of the coating composition of the present invention, the ratio of the total mass of the inorganic acid and the organic acid of the component (b2) to the total mass of the coating composition is preferably in the range of 0.1 to 10%. (Ie, in the range of 0.1-10% by weight), more preferably in the range of 0.5-5% (ie, in the range of 0.5-5% by weight), even more preferably in the range of 1-5%. In the range (ie, in the range of 1-5% by weight), very preferably in the range of 1-3.5% (ie, in the range of 1-3.5% by weight), particularly preferably in the range of 2.5-3. It is in the range of 5.5% (ie, in the range of 2.5-3.5% by weight).
Further particularly preferred is the use of the present invention in the coating composition, preferably the use of the present invention shown to be preferred, wherein the constituent (a) is particulate amorphous silicon dioxide, preferably primary particles (i). Particley amorphous silicon dioxide that is spherical and / or has D90 <10 μm, preferably D90 <1 μm, as determined by laser diffraction, more preferably (i) zirconium dioxide and / or (i) as by-components. ii) Containing particulate amorphous silicon dioxide containing Lewis acid and very preferably containing zirconium dioxide. The coating composition in which the primary particles of particulate amorphous silicon dioxide of the component (a) are (i) spherical and / or (ii) have D90 <10 μm, preferably D90 <1 μm as determined by laser diffraction. The use of the present invention of a thing is preferred. Preferably, the primary particles of the particulate amorphous silicon dioxide of the component (a) are (i) spherical and have a sphericity of 0.9 or more as determined by evaluation of a two-dimensional microscopic image. Modern commercial electronic or optical microscopy systems enable digital image analysis and thus facilitate particle morphology. Digital image analysis is preferred for sphericity testing.

Particularly preferred is the use of the present invention of the coating composition, preferably the use of the present invention shown to be preferred, wherein the constituent (a) is quartz, aluminum oxide, zirconium dioxide, aluminum silicate, bauxite. Includes one or more substances selected from the group consisting of zirconium silicate, olivine, talc, mica, graphite, coke, talus, diatomaceous earth, kaolin, calcined kaolin, metakaolinite, iron oxide, and bauxite.
"D90" of the primary particles of particulate amorphous silicon dioxide represents their particle size distribution. The particle size distribution is determined by a method known per se, by laser diffraction, preferably by standard methods according to DIN ISO 13320: 2009-10. Regarding the cumulative frequency distribution of the volume average particle size distribution function, the D90 value confirmed here indicates that the 90% by volume primary particles have a particle size of a specific value (for example, 10 μm) or less. A suitable instrument for determining the particle size distribution is a self-known "Mastersizer 3000" type laser diffractometer manufactured by Malvern, United Kingdom, preferably a "Colter LS 230" type laser diffractometer manufactured by Beckman Coulter, USA. The measurement is preferably carried out by a "polarization scattering intensity difference measurement"("PIDS") technique. Using the laser diffraction technique described above, the scattered light signal is evaluated in each case according to the Mee theory, preferably taking into account the refraction and absorption behavior of the primary particles.

If the primary particles of particulate amorphous silicon dioxide are present as agglomerates and / or aggregates and / or otherwise aggregates of multiple primary particles, these are to eliminate the resulting distortion as much as possible. Is preferably loosely separated by mechanical means, or similarly by a method known per se, to determine the particle size distribution of the primary particles.
The term "subcomponent" is used in the context of the present invention to indicate that the particulate amorphous silicon dioxide of the constituent (a) is, for example, from an upstream production procedure and / or an upstream treatment procedure for particulate amorphous silicon dioxide. Represents the inclusion of only a small amount of such sub-ingredients that may occur as impurities or deposits in. In each case, the sub-component is preferably in an amount of 18% by mass (or mass fraction) or less, more preferably, based on the total mass of the particulate amorphous silicon dioxide of the component (a). It is present in an amount of 12% by mass or less, most preferably 8% by mass or less.

One of the above-mentioned sub-components in the component (a) can be Lewis acid. However, it is also possible to include more than one Lewis acid and / or a mixture thereof. In the context of the present invention, "Lewis acid" refers to G.I. N. An acid according to the approach proposed by Lewis, according to which the acid is an electron pair acceptor, a molecule or ion with an incomplete noble gas configuration, which accepts the electron pair provided by the Lewis base. , So-called Lewis adducts can be formed with the base. Lewis acids are electrophilic, while Lewis bases are nucleophilic. Therefore, according to conventional concepts, molecules and ions that are not acids can also be interpreted as acids.
In addition to the above constituents, the coating compositions used in accordance with the present invention may include additional constituents such as esters, lactones and / or acid anhydrides such as methyl formate, ethyl formate, propylene carbonate, γ-butyrolactone, diacetin. , Triacetin, a "dibasic acid ester" known per se (a mixture of two or more dimethyl esters of dicarboxylic acids, especially glutaric acid, succinic acid, and adipic acid), anhydrous acetic acid, methyl carbonate, and ε-caprolactone. It may be included.

In one configuration, the use of the coating composition of the present invention or the preferred use of the coating composition of the present invention is preferred, wherein the coating composition comprises the following constituents:
-One or more biocides,
-One or more wetting agents,
-Contains one or more rheological additives and-one or more binders, preferably one or more or all of polyvinyl alcohol.
Suitable biocides include conventional biocides such as fungicides, especially fungicides, algae and / or fungicides. The biocides further shown above may preferably be used. Suitable wetting agents are preferably the wetting agents further listed above. Suitable rheological additives are preferably the rheological additives listed above. Suitable binders are preferably the binders listed above. Polyvinyl alcohol is a particularly preferred binder.
In a further embodiment, it is preferred to use the present invention of a coating composition, wherein the coating composition has a solid content of less than 80% by weight, preferably less than 45% by weight, based on the total mass of the coating composition in each case.

The coating composition for use in accordance with the present invention is preferably immediate use, which means that it is intended for immediate application to a casting mold or core. Alternatively, the coating composition for use in accordance with the present invention can be in the form of a concentrate, in which case it is diluted by the addition of water or an aqueous mixture, especially before being applied to a casting mold or core. Intended. Unless otherwise specified, this applies to all embodiments of the invention. In each individual case, one of ordinary skill in the art will determine whether the coating composition should be used immediately or further diluted.
According to a further embodiment, the coating composition is, in each case, an amount of 2% by weight or less, preferably in the range of 0.05 to 0.80% by weight, based on the total weight of the coating composition. The preferred use of the present invention or the present invention, preferably comprising one or more binders containing polyvinyl alcohol, is particularly preferred.

The solid content of the coating composition for use in accordance with the present invention is determined in relation to the present invention according to the data sheet P79 from Section 6 of the March 1976 edition of the Veryin Germany Giessureifachleute.
According to another embodiment, the preferred use of the coating composition in the present invention or in the present invention is particularly preferred, the coating composition being used for casting metal melts having temperatures above 900 ° C, preferably above 1250 ° C. For, preferably applied to a water glass bond mold or water glass bond core for use in casting metal melts containing iron and / or steel.
Further preferred is the preferred use of the coating composition of the invention or in the present invention, in which the coating composition is applied to a water glass binding mold or water glass binding core for use in iron or steel casting.

According to a further embodiment, the preferred use of the coating composition in the present invention or in the present invention is particularly preferred, where the coating composition is the temperature of the water glass binding core or water glass binding mold above 50 ° C, preferably above 70 ° C. More preferably, it is applied to a water glass binding mold or a water glass binding core at a temperature of less than 100 ° C. Surprisingly, the resulting mold or core obtained formed or remaining under these conditions can be used in subsequent work and / or processing steps under these conditions.
A further subject of the invention is the use of an acid to set a pH of 5 or less, preferably 4 or less in the aqueous phase of the coating composition for application to a water glass binding template or water glass binding core. be. The aforementioned acids are preferably selected from the group consisting of inorganic and organic acids. The organic acids here are preferably from monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids, preferably monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids that are solid at 25 ° C. and 1013 mbar, more preferably citric acid and oxalic acid. It is selected from the group of. The inorganic acid here is preferably selected from the group consisting of hydrochloric acid, nitrate, phosphoric acid and acidic phosphates such as aluminum phosphate, more preferably from the group consisting of hydrochloric acid, nitrate and phosphoric acid. .. In a preferred variant of the use of the acid of the invention described above, the water glass binding template or the water glass binding core comprises particulate amorphous silicon dioxide and the acid preferably sets a pH of 4 or less. Used for.
Similarly, the subject matter of the present invention is a coated water glass binding mold, preferably with high storage stability, or a coated water glass binding core, preferably with high storage stability, for use in casting. The manufacturing method is as follows:
(1) A step of providing or producing a coating composition already defined in relation to the use of the coating composition according to the present invention.
A step of providing or manufacturing an uncoated water glass binding mold or an uncoated water glass binding core, and (3) a coating composition provided or manufactured from step (1) of step (2). ) Is a method including a step of applying to a mold provided or manufactured from or a core provided or manufactured.

The coating composition produced or provided in step (1) of the method of the present invention can be produced by a method known per se. For example, an appropriate amount of water can be introduced first, and then additional components for making the coating composition, such as a high shear stirrer such as a gear stirrer or a dissolver stirrer, are suitable. Each desired amount can be added to this initial filling while stirring using a stirrer. If desired, the constituents can be miscible by conventional methods before or during addition. Thus, for example, before or after addition to the first water filling, one or more rheological additives are mixed using a high shear stirrer, individually or with one or more refractories. You may. If one or more refractories are not miscible with additional rheological additives, they may be individually miscible and added to the initial water filling. Then, for example, additional constituents of the coating composition, eg, one or more acids, in any order, preferably with stirring, preferably using a high shear stirrer, the first water filling-rheology. Additives and / or may contain fire resistant agents-may be added to one or more fire resistant coating binders, one or more rheological agents, one or more wetting agents, one or more. The first water filling-rheology of the defoamer, one or more pigments and / or one or more dyes, in any order, preferably with stirring, preferably using a high shear stirrer. Additives and / or fire resistant agents may be included-may be added.

The coating composition produced or provided in step (1) of the method of the present invention can be used immediately for application to a casting molding element, and thus has a concentration suitable for use as, for example, a mold or a dipping bath for a core. Exists in. It is also possible to further produce the aforementioned coating composition as a concentrate first by conventional methods, which later, eg, just before use of the coating composition, eg, further water, a template and / or Dilute by adding to an immediate use concentration (or consistency) suitable for application to the core. For coating compositions used in accordance with the present invention, where the amount or condition is stated in relation to the present invention, the coating composition referred to in each case is ready for immediate use (template or unless otherwise stated. Intended for immediate application to core). The individual constituents of the coating composition for use in accordance with the present invention must not be mixed with each other only immediately prior to the intended application of the mold or core, but for use according to the present invention. Due to the high storage stability of the coating composition, mixing may be done at a much earlier stage.

In step (2) of the method of the invention, the uncoated waterglass binding mold provided or manufactured or the uncoated waterglass binding core provided or manufactured may be described, for example, in WO 2006/024540 or WO2009 /. As described in 056320, it can be manufactured by a conventional method.
Applying the coating composition provided or manufactured from step (1) to the mold or core provided or manufactured in step (3) is the step (2) of the method of the present invention. According to, by a method known per se, preferably by a coating method shown to be suitable above, more preferably used in accordance with the present invention, the mold or core is immersed in a coating composition provided as a dipping bath. By doing so, it can be carried out.
In a preferred embodiment of the aforementioned method of the invention, the provided or manufactured mold or the provided or manufactured core comprises particulate amorphous silicon dioxide.

In a more preferred embodiment of the aforementioned method of the invention, or a more preferred embodiment of a preferred method according to the invention, the coating on the mold is more at a mold temperature or core temperature above 50 ° C, preferably above 70 ° C. It is preferably carried out at a temperature of less than 100 ° C.
A further subject of the invention is also a coated mold or coated core for use in casting, in each case.
(X) With a water glass bond mold or a water glass bond core,
(Y) A coated mold or a coated core, including a coating comprising the coating composition defined above, in relation to the use of the coating composition of the present invention.
In a preferred embodiment of this latter subject of the invention, the coated mold or coated core can be produced by the aforementioned method of the invention or the preferred method according to the invention.

In each case, the waterglass-bonded mold and / or the waterglass-bonded core comprises particulate amorphous silicon dioxide, such a coated mold of the invention disclosed above or such of the invention. The coated core disclosed in is preferred.
The molds disclosed above and / or the cores disclosed above the present invention are preferably used for casting metal melts having temperatures above 900 ° C., preferably metal melts containing iron and / or steel. For casting, more preferably for casting metal melts containing iron and / or steel having a temperature above 1250 ° C.
The subject matter of the present invention is also a separate component,
(U) For producing a coating on a water glass bond mold or water glass bond core for use in casting,
A coating composition comprising (a) one or more refractories and (b) an aqueous phase having a pH of 5 or less.
(V) A binder containing water glass and
(W) A kit containing particulate amorphous silicon dioxide.

In a preferred alternative form, the kit of the invention comprises the coating composition as a component (U), the coating composition as defined above in relation to the use of the coating composition of the invention.
The use of the above-mentioned coating compositions of the present invention has been found to have the following advantages in particular over the equivalent or equivalently used coating compositions known from the prior art, and / or embodiments under consideration. Demonstrate such benefits according to:
-Improved strength of coated waterglass binding molds and / or cores that can be produced using it, preferably waterglass binding molds and / or cores containing particulate amorphous silicon dioxide;
-Improved storage stability of coated waterglass binding molds and / or cores that can be produced using it, preferably waterglass binding molds and / or cores containing particulate amorphous silicon dioxide;
-Resistance to atmospheric moisture of coated water glass binding molds and / or cores that can be manufactured using it, water glass binding molds and / or cores containing particulate amorphous silicon dioxide. Improvement;
-For hot molds and / or cores (ie, preferably molds and / or cores with temperatures above 50 ° C, preferably temperatures in the range 50-100 ° C), preferably waterglass-bonded molds and /. Alternatively, an improvement in the possibility of applying the coating composition to the core, more specifically to the waterglass binding template and / or the core containing particulate amorphous silicon dioxide; and / or-described coating composition. Waterglass Bonding Casting Elements for Casting Iron and / or Steel, More Specifically, Molds and / or Cores, Preferably Waterglass Bonds Containing Particle Amorphous Silicon Dioxide, By Use of the Invention Improved possibility of using molds and / or cores.
These advantages also apply mutatis mutandis to other subjects and aspects of the invention.

The examples shown below are intended to describe and describe the invention in more detail without limiting the scope of the invention.
(Example 1)
Production of Coating Composition The coating composition of the present invention (“SZ1”) shown in Table 1 and the comparative coating composition (“SZ2” and “SZ3”) which are not of the present invention, respectively, mix the components shown in each other. It was manufactured by the conventional method.
For this purpose, the required amount of water in each case is first introduced into the glass beaker (in each case a batch size of about 2 kg of the coating composition as a "concentrate", see Table 1) and rheology addition. Agents and refractory materials (phyllosilicates, zircon flowers, graphite) were added and then these components were mixed in a conventional manner for 3 minutes using a high shear dissolver stirrer. The other constituents of the coating composition (see Table 1) were then added in the indicated proportions, followed by stirring for an additional 2 minutes using a high shear dissolver stirrer. As a result, the dilutable refractory coating composition concentrate shown in Table 1 was obtained in each case.

References to "DIN grounds" in Table 1 indicate that each indicated component of the coating composition allows a sample of this component to have a nominal mesh size in μm corresponding to the values listed (eg). "80" represents "analytical sieve with mesh size 80 μm"), and after sieving with an analytical sieve, it indicates that it exists in a pulverized state (according to DIN ISO 3310-1: 2001-09), in each case. Remains in the range of 1-10% by weight based on the amount of sample used.

The dilute refractory coating composition concentrate shown in Table 1 above is subsequently diluted with water to mold and / or by dipping operation for the intended purpose herein (preferably in the form of a dipping bath). A coating composition for immediate use (for application to the core) was produced. Other properties of the ready-to-use coating composition obtained in each case from each dilution used and also from the dilutions used are shown in Table 1a below.

As is apparent from Table 1a, the coating compositions for application to the test cores by dip coating or dip bath for the purposes intended herein are (i) each of them in application to the test cores. The properties, and also (ii) the properties obtained of each of the coated test cores, were manufactured in such a way that they could be reliably and easily compared (density and flow time were set to be as similar as possible; but the present invention. The pH of the coating composition SZ1 of the above is different from the coating compositions SZ2 and SZ3 which are not the present invention).
The densities of the immediate use coating compositions shown in Table 1a were measured according to the standard test method DIN EN ISO 2811-2 (Method A).

The flow times of the ready-to-use coating compositions shown in Table 1a were measured according to standard test method DIN 5321 (1974) and determined using 4 cups of DIN.
The pH values of the ready-to-use coating compositions shown in Table 1a were measured from the suspension in each case according to standard test method DIN 19260: 2012-10.
The coating compositions SZ1 and SZ3 each contained attapulsite as a rheological additive. The coating composition SZ2 is of the type described in Ref. WO 00/05010.

(Example 2)
Investigation of softening of the core for castings In order to determine the softening of the core for castings (that is, the maximum decrease in bending strength), the test core (test piece) is used as a multi-core shooting machine (model LUT) made by Multiserw as before. , Gas pressure: 2 bar, shot time: 3.0 seconds, shooting pressure: 4.0 bar) (according to "core system 1" shown in Table 4). 1 hour after core production, by immersion at room temperature (25 ° C.) with the above immediate use coating compositions "SZ1", "SZ2" and "SZ3" (see Table 1a) (conditions: immersion for 1 second). Retention time in the coating composition for 3 seconds; removal for 1 second), the test core was coated (coated). The wet film thickness of the refractory coating was adjusted to about 250 μm in each case. Then, the coated test cores were dried in a forced air oven under the following conditions (120 ° C. for 1 hour), and in each case, changes in their bending strength under the drying conditions were examined.
Each of the coated test cores was dried for 1 hour, during which time their bending strength (at N / cm ² corresponding to the definition given in the October 1978 edition, the Verein Deutscher Giessureifachleute data sheet R202). , Using standard test equipment of type "Multiserw-Morek LRu-2e", in each case by standard measurement program "Rg1v_B 870.0 N / cm ² " (3-point bending strength) at different time points during drying. Then, the measurement was performed 1 hour after the completion of the drying operation.

For the coated test cores investigated, Table 2 shows the drying of the newly coated (still wet) test cores, in each case, based on the bending strength (initial value) before the start of drying. The maximum decrease in bending strength under the conditions is reported in% in each case.

The expression "core breakage" here and below refers to the invalidation of the coated core during the drying procedure in each case, where the coated core measures the bending strength and in each case. It means that it could not be used in the subsequent casting procedure.
From the values reported in Table 2, the maximum reduction in bending strength of the test core coated with the coating composition (SZ1) of the present invention is higher than that of the comparative coating composition (SZ2 and SZ3) which is not the invention. It turns out that it was significantly smaller. As is more apparent from the values in Table 2, it was not possible to produce a coated core that could be used under selected conditions with the comparative coating composition SZ3, which is not the present invention.

(Example 3)
Investigation of Storage Stability of Coated and Uncoated Casting Cores In order to determine storage stability, the water glass bond test cores (test pieces) were prepared by conventional methods (as described in Example 2). Manufactured (in the same way) and their bending strength was measured as described above (storage time 1 hour, relative humidity range 30-60%, storage temperature 20) in each case without coating immediately after their production. ~ 25 ° C.); see Table 3 (item "Uncoated after 1 hour").

As shown in Table 3 below, one hour after core production (ie, after the same time interval from their production), at room temperature (25 ° C.), the corresponding test cores were coated with the coating composition SZ1 and. Each case is coated with SZ3 by immersion (conditions: immersion for 1 second; retention time in the coating composition for 3 seconds, removal for 1 second) (coating composition is as shown in Example 1). Same), in each case in a forced air oven, dried at 120 ° C. for 1 hour. The coated and dried test cores are then subjected to a duration of 4 days (as long as it is possible to produce coated cores or as long as no damage to the cores was previously observed. ), It was subjected to a preservation test. The temperature during storage was 35 ° C. in each case and the relative humidity was 75% in each case. After the storage test was completed, the bending strength of the test core was determined as described above. The results of these storage tests are reported in Table 3 below. The test cores (“core system 1”) used in all the tests of Example 3 are the cores whose production conditions are specified in Table 4 below.

From the values reported in Table 3, the water glass bond test cores coated with the coating composition (SZ1) of the present invention, especially after storage for 4 days, still had more than 40% of the initial strength. On the other hand, the test core coated with the comparative coating composition (SZ3) which is not the present invention cannot be used under the same conditions; since it fell apart during storage, its bending strength is above. It turns out that it could no longer be measured under the defined conditions. Under test conditions, the uncoated comparative core breaks after just 131 minutes, i.e., exactly, application of the coating composition of the invention to the test core stabilizes the test core under dry conditions. The transformation brought about.

As shown in Table 4, the core system 1 was composed only of a molding material, a binder, and an additive component.
The binder shown in Table 4 for the core system 1 was, in this case, a commercially available alkali metal water glass binder “Cordis® 8511” (Huttens-Albertus Chemische Werke GmbH).
In this case, the additive shown in Table 4 for the core system 1 is a commercially available binder additive whose main component (95% by mass or more) is particulate amorphous silicon dioxide, "Anorgit (registered trademark)". It was 8396 "(Huttens-Albertus Chemische Werke GmbH).

(Example 4)
Investigation of bending strength of core for coated castings In each case, the water glass bond test core (test piece) containing and not containing particulate amorphous silicon dioxide was used as described in the conventional method (Example 2). Similar, but manufactured in (after provisional maintenance of the core shooting machine used) and their bending strength, for comparative purposes, in each case without coating immediately after manufacture, as described above. It was determined as per (storage time 1 hour, temperature range 20-25 ° C., relative humidity 30-60%) (see Table 6 for test core production conditions).

Further, as shown in Table 5 below, the test core was coated by immersion (conditions: immersion for 1 second; retention time in the coating composition for 5 seconds, removal for 1 second) (coating composition: (Same as that shown in Example 1), in each case in a forced air oven, dried at 120 ° C. for 1 hour. The above test cores were cooled to room temperature, stored for 24 hours (relative humidity in the range of 30-60%, temperature in the range of 20-25 ° C.), then coated with bending strength and dried. I decided like this.

The results of determining the bending strength are reported in Table 5 below. In this case, three different test cores (core systems A, B and C) are used and the manufacturing conditions for each are reported in Table 6 below.

From the values reported in Table 5, it can be seen that the core for castings coated with the coating composition of the present invention achieves high bending strength. In addition, the values reported in Table 5 were successful for casting cores manufactured under different conditions using the coating composition of the present invention (SZ1) with good results (high bending strength). Indicates that it can be coated. On the other hand, it was not possible to produce a usable coating core under the same conditions using the comparative coating composition (SZ3) which is not the present invention.

The binders and additives shown for the cores A, B and C in Table 6 are, in each case, the binders (“Cordis® 8511”) and additives (“Anorgit (Registration)” shown for Table 4. Corresponds to the trademark) 8396 ").
As shown in Table 6, the core systems A, B and C described above were composed only of a molding material, a binder and optionally an additive component in each case.

Claims (16)

For producing coatings on water glass bond molds or water glass bond cores for use in casting,
(A) One or more refractories and
(B) Use of a coating composition comprising an aqueous phase having a pH of 5 or less, wherein the water glass binding template or the water glass binding core contains particulate amorphous silicon dioxide. The aqueous phase (b) is
Contains (b1) water and (b2) one or more acids having a pKa of less than 5 and / or
The ratio of the mass of the component (b1) to the total mass of the aqueous phase (b) is more than 50%.
And / or
The aqueous phase has a pH of 4 or less.
Use according to claim 1. The component (b2) comprises one or more acids selected from the group consisting of inorganic and organic acids.
-The organic acid is selected from the group consisting of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids.
And / or-the inorganic acid is selected from the group consisting of hydrochloric acid , nitric acid, phosphoric acid, and acidic phosphates.
And / or-the ratio of the total mass of the inorganic acid and the organic acid of the component (b2) to the total mass of the coating composition is in the range of 0.1 to 10%.
Use according to claim 2 . The component (a) is
Particulate amorphous silicon dioxide,
And / or quartz, aluminum oxide, zirconium dioxide, aluminum silicate, phyllosilicate, zirconium silicate, olivine, talc, mica, graphite, coke, talc, diatomaceous earth, kaolin, calcined kaolin, metakaolinite, iron oxide , And the use according to any one of claims 1 to 3 , comprising one or more substances selected from the group consisting of bauxite. The coating composition comprises the following constituents:
-One or more biocides,
-One or more wetting agents,
-One or more rheology additives, and-one or more binders,
Use according to any one of claims 1 to 4 , comprising one or more or all of them. The coating composition has a solid content of less than 80% by weight based on the total mass of the coating composition.
And / or the coating composition comprises one or more binders comprising polyvinyl alcohol in a total amount of 2% by weight or less based on the total mass of the coating composition.
Use according to any one of claims 1 to 5 . The coating composition is applied to a water glass bond mold or water glass bond core for use in casting metal melts having temperatures above 900 ° C.
And / or the coating composition is applied to a water glass bond mold or water glass bond core for use in iron or steel casting.
And / or the coating composition is applied to a water glass-bonded mold or a water-glass bonded core at a temperature of the water glass-bonded core or water-glass-bonded mold above 50 ° C and below 100 ° C.
Use according to any one of claims 1 to 6 . The use of an acid to set a pH of 5 or less in the aqueous phase of the coating composition for application to a water glass binding mold or water glass binding core, in said water glass binding mold or said water glass binding. Used, the child contains particulate amorphous silicon dioxide . The acid is selected from the group consisting of inorganic and organic acids.
The organic acid is selected from the group consisting of monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids.
And / or the inorganic acid is selected from the group consisting of hydrochloric acid , nitric acid, phosphoric acid, and acidic phosphates.
And / or the acid is used to set a pH of 4 or less,
The use according to claim 8 . A method for producing a coated waterglass-bonded mold with high storage stability or a coated waterglass-bonded core with high storage stability for use in casting, wherein:
(1) A step of providing or manufacturing the coating composition according to any one of claims 1 to 6 .
(2) A step of providing or manufacturing an uncoated water glass binding mold or an uncoated water glass binding core (the provided or manufactured water glass binding mold or the water glass binding core is a particulate non-crystal. ( Including quality silicon dioxide) , and (3) the step of applying the coating composition provided or manufactured from the above step (1) to the provided or manufactured mold or the provided or manufactured core. Method. 10. The method of claim 10 , wherein the application to the mold is carried out at the temperature of the core or the mold above 50 ° C and below 100 ° C. A coated mold or coated core for use in casting, in each case,
(X) A water glass-bonded mold or a water-glass-bonded core ( the water-glass-bonded mold and / or the water-glass-bonded core contains particulate amorphous silicon dioxide) and
(Y) A coated mold or a coated core comprising a coating comprising the coating composition according to any one of claims 1 to 6 . The coated mold or coated core according to claim 12 , which can be produced by the method according to claim 10 . The coated mold or coated core according to any one of claims 12 to 13 , for use in casting metal melts having temperatures above 900 ° C. With separate components,
(U) For producing a coating on a water glass bond mold or water glass bond core for use in casting,
A coating composition comprising (a) one or more refractories and (b) an aqueous phase having a pH of 5 or less.
(V) A binder containing water glass and
(W) A kit containing particulate amorphous silicon dioxide. The kit according to claim 15 , wherein the coating composition is included as a component (U), and the coating composition is the one according to any one of claims 1 to 6 .