Methods for manufacturing molds.

Abstract

Provided is a casting mold manufacturing method that is capable of effectively improving workability at a molding site while improving coated sand fillability and casting mold strength. Provided is a method that is capable of advantageously manufacturing an intended casting mold by using a conventional molding device as is without any need to newly install a special device. The intended casing mold is formed by adding an aqueous medium prepared by including a surfactant and / or a polyhydric alcohol in dry-state coated sand obtained by covering the surface of a refractory aggregate with a water-soluble binder, moistening the coated sand, and then filling a molding die with the obtained moist coated sand.

Description

Method for manufacturing a mold The present invention relates to a method for manufacturing a mold, and more particularly, to a method capable of advantageously manufacturing a mold while improving workability at a molding site, which is a mold manufacturing site, and improving the filling property of coated sand and the strength of the mold. Conventionally, as one of the methods for manufacturing a mold used for casting molten metal, a method of molding a mold of a desired shape using coated sand obtained by coating mold sand made of a refractory aggregate with a predetermined binder has been adopted. As the binder used there, for example, in "Casting Engineering Handbook" edited by the Japan Foundry Engineering Society, pages 78 to 90, in addition to inorganic binders such as water glass, organic binders using resins such as phenolic resin, furan resin, and urethane resin are also disclosed. There, a method of molding a self-hardening mold using these binders is also disclosed. And as a method of performing mold molding after forming coated sand obtained by coating a predetermined refractory aggregate (mold sand) with water glass, which is one of the inorganic binders among these binders, various methods have been proposed. For example, in Japanese Patent Application Laid-Open No. 2008-036712, a mold material or a mold part containing an aggregate containing silica sand (refractory aggregate), alkali silicate (water glass), and amorphous silicon dioxide is disclosed. Also, there, at the mold molding site, the silica sand, water glass, and amorphous silicon dioxide are kneaded, and a wet form (wet state) of a mold material (coated sand) in which a wet alkali silicate (water glass) adheres to the surface of the silica sand is obtained, and then it is filled into a predetermined mold, and a mold of a desired shape is molded. However, such wet coated sand reacts with carbon dioxide in the air and gradually hardens, resulting in a short pot life and insufficient storage stability. Therefore, such wet coated sand is generally manufactured at the mold making site and then directly filled into the molding die to form the desired mold. However, transporting fine powder refractory aggregates and water glass to a mold making site with many obstacles and kneading them with a mixer to obtain wet coated sand is quite laborious and time-consuming due to the high viscosity of water glass. In addition to the difficulty of mixing with refractory aggregates due to the viscosity of water glass, there are problems with poor workability in mold making, such as the devices for mixers for mixing and molding dies for molding being easily soiled. Moreover, since it is a work at the mold making site, there is also an inherent problem that workers are highly likely to be chemically burned by strongly alkaline water glass. On the other hand, different from the wet coated sand as described above, a dry coated sand having normal temperature fluidity, which is formed by using water glass as a binder to form a dried coating layer of such a binder on the surface of refractory aggregates, is disclosed in Japanese Patent Laid-Open No. 2012-076115. In that case, such dry coated sand is coated with a solid coating layer containing a water-soluble inorganic compound such as water glass as a binder. After it is filled into the molding cavity of a molding die for mold making, a method of solidifying such coated sand by passing steam is disclosed to obtain the desired mold. However, in such a molding method, after filling the dry coated sand, it is necessary to blow steam into the molding die. Therefore, since it is necessary to specially provide a steam blowing device, the conventional device cannot be used as it is, and there is an inherent problem of increasing the manufacturing cost of the mold. Moreover, in that method, after the dry coated sand filled in the mold is wetted with steam, it is solidified by drying to form a mold. Therefore, in order to effectively dry such wetted coated sand, in addition to blowing in steam, it is also necessary to add a new step of blowing in a heated gas. As a result, the molding cycle from filling the mold to drying and solidifying or hardening becomes longer, and there is also an inherent problem that the productivity of the mold decreases. Japanese Patent Application Laid-Open No. 2008-036712, Japanese Patent Application Laid-Open No. 2012-076115 "Casting Engineering Handbook", pages 78-90 Here, the present invention has been made against such a background. The problem to be solved is to provide a method for manufacturing a mold that can effectively improve the workability at the molding site while improving the fillability of the coated sand and the strength of the mold. Another problem is to provide a method that can advantageously manufacture a target mold basically using the conventional equipment for molding without the need to newly install special equipment. The present invention can be preferably implemented in various aspects listed below in order to solve the above problems. In addition, each of the aspects described below can be adopted in any combination. It should be understood that the aspects or technical features of the present invention are not limited to those described below, and can be recognized based on the inventive concept grasped from the description of the entire specification. (1) An aqueous medium containing a surfactant and / or a polyhydric alcohol is added to dry coated sand obtained by coating the surface of a refractory aggregate with a water-soluble binder, and after wetting, the obtained wetted coated sand is filled into a mold for molding. A method for manufacturing a mold, characterized by this. The aqueous medium is added to 100 parts by mass of the coated sand and then wetted. After that, the obtained wetted coated sand is filled into a mold for molding. A method for manufacturing a mold, characterized by this. (2) The aqueous medium is, with respect to 100 parts by mass of the coated sand It is added to the coated sand at a ratio of 0.5 to 6 parts by mass. The method for manufacturing a mold according to the above aspect (1), characterized in that . (3) The surfactant is added to the aqueous medium so as to be in a ratio of 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble binder in the coated sand. The method for manufacturing a mold according to the above aspect ( 1) or the above aspect (2). (4) The polyhydric alcohol is added to the aqueous medium so as to be in a ratio of 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble binder in the coated sand. The method for manufacturing a mold according to any one of the above aspects ( 1) to (3). (5) When wetting the dry coated sand, spherical particles are further added. The method for manufacturing a mold according to any one of the above aspects ( 1) to (4). (6) The addition amount of the spherical particles is 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble binder in the coated sand. The method for manufacturing a mold according to the above aspect (5), characterized in that (7) When wetting the dry coated sand, a second water-soluble binder is further added. The method for manufacturing a mold according to any one of the above aspects ( 1) to (6). (8) The water content in the dry coated sand is 5 to 55% by mass of the solid content of the water-soluble binder. The method for manufacturing a mold according to the above aspect ( The method for manufacturing a mold according to any one of (1) to the above aspect (7). (9) As the water-soluble binder, one or more of a thermosetting resin, saccharides, proteins, synthetic polymers, salts, and inorganic polymers are selected and used, characterized by the above aspect (1) to the above aspect (8). The method for manufacturing a mold according to any one of them. The method for manufacturing a mold according to any one of (1) to (8) above, characterized in that one or more of a thermosetting resin, saccharides, proteins, synthetic polymers, salts, and inorganic polymers are selected and used as the water-soluble binder. The method for manufacturing a mold according to any one of (1) to (8) above, characterized in that one or more of a thermosetting resin, saccharides, proteins, synthetic polymers, salts, and inorganic polymers are selected and used as the water-soluble binder. The method for manufacturing a mold according to any one of (1) to (8) above, characterized in that one or more of a thermosetting resin, saccharides, proteins, synthetic polymers, salts, and inorganic polymers are selected and used as the water-soluble binder. (10) The method for manufacturing a mold according to the above aspect (9), characterized in that the inorganic polymer is water glass. The method for manufacturing a mold according to the above aspect (9), characterized in that the inorganic polymer is water glass. (11) The method for manufacturing a mold according to any one of (1) to (10) above, characterized in that heated air or dry air is passed through the mold filled with the moistened coated sand. The method for manufacturing a mold according to any one of (1) to (10) above, characterized in that heated air or dry air is passed through the mold filled with the moistened coated sand. The method for manufacturing a mold according to any one of (1) to (10) above, characterized in that heated air or dry air is passed through the mold filled with the moistened coated sand. (12) The method for manufacturing a mold according to any one of (1) to (11) above, characterized in that carbon dioxide gas or organic ester gas is passed through the mold filled with the moistened coated sand. The method for manufacturing a mold according to any one of (1) to (11) above, characterized in that carbon dioxide gas or organic ester gas is passed through the mold filled with the moistened coated sand. The method for manufacturing a mold according to any one of (1) to (11) above, characterized in that carbon dioxide gas or organic ester gas is passed through the mold filled with the moistened coated sand. (13) The method for manufacturing a mold according to any one of (1) to (12) above, characterized in that the mold is heated to a temperature of 40°C to 250°C. The method for manufacturing a mold according to any one of (1) to (12) above, characterized in that the mold is heated to a temperature of 40°C to 250°C. The method for manufacturing a mold according to any one of (1) to (12) above, characterized in that the mold is heated to a temperature of 40°C to 250°C. Thus, in the present invention, by using a water-soluble binder such as water glass as a binder, first, dry coated sand is prepared in advance and brought to the molding site. On the other hand, at the molding site, only an aqueous medium containing a surfactant and / or a polyhydric alcohol for wetting the dry coated sand is prepared, and the desired mold can be formed. Therefore, at the molding site with a poor working environment, there is no need to knead viscous water glass with refractory aggregates, and thus the workability at the molding site can be significantly improved. Further, in the mixer, by adding and mixing an aqueous medium containing a surfactant and / or a polyhydric alcohol to the dry coated sand, even when it is wetted, the mixture adheres less to the mixer and the device is not easily soiled. In addition, at the molding site, since there is no handling of water-soluble binders such as water glass, there is no risk of workers being chemically injured by such water glass or other water-soluble binders. Moreover, since a surfactant and / or a polyhydric alcohol is added to the aqueous medium used for wetting the coated sand, the filling property of the coated sand during mold casting can be advantageously improved, and the strength of the obtained mold can be effectively improved. This feature can be advantageously exhibited. Also, in the present invention, the dry coated sand prepared in advance hardly changes over time due to carbon dioxide gas in the air unless an aqueous medium is added, and it has excellent storage stability. Therefore, a large amount of dry coated sand can be prepared in advance at a location different from the molding site. At the molding site, a part of it is used, and an aqueous medium containing a surfactant and / or a polyhydric alcohol is added to it. After wetting, the desired mold can be formed. It has a practical advantage, and the wetted dry coated sand has better filling property into the mold than the wet coated sand prepared at the molding site as in the prior art, and moreover, it exhibits the special feature that the mold release property from the mold of the formed mold is also improved. Furthermore, according to the method for manufacturing a mold according to the present invention, at the molding site, by filling the wet-coated sand into the molding die and only heating it, etc., the moisture in the aqueous medium containing a surfactant and / or a polyhydric alcohol is evaporated, dried and solidified or cured. Therefore, there is no need to newly install special devices such as a water vapor generator or a water vapor ventilation mechanism as in the case of using dry-coated sand as it is. Basically, molding can be performed using the conventional devices as they are. As a result, it is possible to avoid an increase in equipment cost and thus an increase in the manufacturing cost of the mold. Also, there is no need to newly adopt a water vapor blowing process, and thereby, it is possible to advantageously avoid the problem of lengthening the molding cycle. It is a front schematic view showing one mold split surface of a mold half constituting a molding die used for evaluating filling property and filling fluidity. Incidentally, in the method for manufacturing a mold according to the present invention, the dry-coated sand prepared in advance is generally produced by mixing a water-soluble binder in an aqueous solution state as a binder with a refractory aggregate and then evaporating the moisture from the mixture. In other words, it is produced by evaporating the moisture of the water-soluble binder in an aqueous solution state, and a dried coating layer composed of the solid content of the water-soluble binder as the binder is formed on the surface of such a refractory aggregate at a predetermined thickness. It is in a dry state and has good normal temperature fluidity. In particular, in the present invention, the water content in such dry-coated sand is desirably in the range of 5 to 55% by mass, preferably 10 to 50% by mass, based on the solid content of the water-soluble binder. In particular, when the water-soluble binder is water glass, it is desirably 20 to 50% by mass. If the water content is less than 5% by mass, there is a problem that a water-soluble binder such as water glass is vitrified and does not return to a solution state even when water is added again. On the other hand, if it exceeds 55% by mass, there is a problem that it does not become a dry state. Here, in the dry coated sand used in the present invention, the range of the amount of moisture that gives a dry state varies depending on the properties of the water-soluble binder. For this reason, in the present invention, the dry state refers to a state in which, regardless of the amount of moisture, when the dynamic angle of repose is measured, a measured value of the dynamic angle of repose can be obtained. The dynamic angle of repose means that the coated sand is accommodated in a cylinder whose one end in the axial direction is closed with a transparent plate material (for example, a container with a diameter of 7.2 cm and a height of 10 cm is filled with coated sand up to half of its volume), and the axis is held so as to be in the horizontal direction, and the cylinder is rotated around the horizontal axis at a constant speed (for example, 25 rpm). As a result, the slope of the flowing coated sand layer in the cylinder becomes flat, and the angle formed between the slope and the horizontal plane is measured. On the other hand, a state in which the coated sand is wet and does not flow in the cylinder, the slope of the coated sand layer is not formed as a flat surface, and the dynamic angle of repose cannot be measured is referred to as wet coated sand. In the present invention, by using the dry coated sand as described above, its pot life can be extended and its storage stability can be advantageously improved. Therefore, such dry coated sand can be prepared in large quantities in advance at a place such as a factory, which is different from the molding site, and a part of it can be transported to the molding site and used for molding the target mold. Thus, it can greatly contribute to the efficiency improvement of the molding work. In addition, as the refractory aggregate constituting the coated sand as described above, any refractory substance that functions as a base material of the mold and various refractory granular or powdery materials that have been conventionally used for molds can be used. Specifically, silica sand, recycled silica sand, and special sands such as alumina sand, olivine sand, zircon sand, and chromite sand, as well as slag-based particles such as ferrochrome slag, ferronickel slag, and converter slag; artificial particles such as alumina-based particles and mullite-based particles and recycled particles thereof; alumina balls, magnesia clinkers, and the like can be mentioned. Note that these refractory aggregates can be new sand, or recycled sand or recovered sand that has been used once or multiple times for molding the mold as foundry sand, or even mixed sand obtained by adding new sand to such recycled sand or recovered sand and mixing them. And such refractory aggregates are generally used as those having a particle size of about 40 to 130 in the AFS index, preferably about 60 to 110 in particle size. Further, the binder that coats the refractory aggregate as described above is also referred to as a binder, and in the present invention, a water-soluble binder will be used. As this water-soluble binder, as long as it is water-soluble, any of inorganic polymers, thermosetting resins, saccharides, synthetic polymers, salts, and proteins can be used. And these may be used alone or two or more of them may be selected and used, but in particular, it is preferable to use an inorganic polymer. In addition, these water-soluble binders may be diluted with water or a solvent in advance and then used. And as the inorganic polymer used as such a water-soluble binder, water glass, colloidal silica, alkyl silicate, bentonite, cement, and the like can be mentioned. Among them, water glass is preferably used. Further, such water glass is a soluble silicate compound, and examples of such silicate compounds include sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, lithium silicate, ammonium silicate, and the like. In particular, in the present invention, sodium silicate (water glass) is advantageously used. Furthermore, such sodium silicate is usually classified into five types numbered from 1 to 5 according to the molar ratio of SiO₂ / Na₂O and is used. Specifically, sodium silicate No. 1 has a molar ratio of SiO₂ / Na₂O of 2.0 to 2.3, sodium silicate No. 2 has a molar ratio of SiO₂ / Na₂O of 2.4 to 2.6, and sodium silicate No. 3 has a molar ratio of SiO₂ / Na₂O of 2.8 to 3.3. In addition, sodium silicate No. 4 has a molar ratio of SiO₂ / Na₂O of 3.3 to 3.5, and sodium silicate No. 5 has a molar ratio of SiO₂ / Na₂O of 3.6 to 3.8. Among these, sodium silicate Nos. 1 to 3 are also defined in JIS-K-1408. And these sodium silicates may be used alone or in combination, and by mixing, it is also possible to adjust the molar ratio of SiO₂ / Na₂O. In addition, in order to advantageously obtain the dry-coated sand used in the present invention, the sodium silicate constituting the water glass used as the binder desirably has a molar ratio of SiO₂ / Na₂O generally of 1.9 or more, preferably 2.0 or more, more preferably 2.1 or more. In the classification of sodium silicate described above, sodium silicate corresponding to Nos. 1 and 2 is particularly advantageously used. Such sodium silicate Nos. 1 and 2 each give a dry-coated sand with stable and good characteristics even in a wide range of sodium silicate concentrations in water glass. Also, the upper limit of the molar ratio of SiO₂ / Na₂O in such sodium silicate will be appropriately selected according to the characteristics of water glass in the form of an aqueous solution, but generally it is 3.5 or less, preferably 3.2 or less, more preferably 2.7 or less. Here, when the molar ratio of SiO₂ / Na₂O is less than 1.9, the viscosity of water glass becomes low, and it becomes difficult to make it dry unless the moisture content is made quite low. On the other hand, when it is more than 3.5, the solubility in water decreases, and the adhesion to the surface of the refractory aggregate is not sufficient, so that the adhesion area cannot be obtained and the mold strength decreases. In addition, the water glass used in the present invention means a solution of a silicic acid compound in a state dissolved in water. It is used in the state of the stock solution purchased in the market as it is, and in addition, water is added to such a stock solution and used in a diluted state. And from such water glass, the solid content (water glass component) excluding volatile substances such as water and solvents is called the non-volatile content, which corresponds to the soluble silicic acid compound such as sodium silicate described above. Also, the higher the ratio of such non-volatile content (solid content), the higher the concentration of the silicic acid compound in the water glass. Therefore, the non-volatile content of the water glass used in the present invention, when it is composed only of the stock solution, corresponds to the ratio excluding the amount of water in such a stock solution. On the other hand, when a diluted solution obtained by diluting the stock solution with water is used, the remaining amount excluding the amount of water in the stock solution and the amount of water used for dilution corresponds to the non-volatile content of the water glass used. And the non-volatile content in such water glass will be set at an appropriate ratio according to the type of the water glass component (soluble silicic acid compound), etc. Advantageously, it is desirable that it is contained at a ratio of 20 to 50% by mass. By appropriately allowing the water glass component corresponding to this non-volatile content to exist in the aqueous solution, when mixing (kneading) with the refractory aggregate, the refractory aggregate can be uniformly coated with the water glass component without unevenness, whereby the target mold can be advantageously molded according to the present invention. When the concentration of the water glass component in the water glass becomes too low and the total amount of the non-volatile content is less than 20% by mass, it is necessary to increase the heating temperature or the heating time for drying the coated sand, and for this reason, problems such as energy loss are caused. Also, when the ratio of the non-volatile content in the water glass becomes too high, it becomes difficult to uniformly coat the surface of the refractory aggregate with the water glass component, which also causes problems in improving the characteristics of the target mold. Therefore, it is desirable to prepare the water glass in the form of an aqueous solution so that such non-volatile content is 50% by mass or less, and thus the water content is 50% by mass or more. Incidentally, examples of the thermosetting resin, which is one of the water-soluble binders other than the inorganic polymers described above, include resol-type phenol resins, furan resins, water-soluble epoxy resins, water-soluble melamine resins, water-soluble urea resins, water-soluble unsaturated polyester resins, water-soluble alkyd resins, and the like. Further, it is also advantageously adopted to blend a curing agent such as an acid or esters with this thermosetting resin to improve its thermosetting properties. Among these thermosetting resins, the use of a resol-type phenol resin is preferred, and such a phenol resin can be prepared by reacting phenols and formaldehydes in the presence of a reaction catalyst. In the present invention, a water-soluble alkaline resol resin is preferably used as such a phenol resin. By using such an alkaline resol resin, it is possible to provide a mold that can be used in a wide range of fields such as cast iron and cast steel. In addition, as the saccharides, which are another type of water-soluble binder, known ones such as monosaccharides, oligosaccharides, and polysaccharides can be used. One kind can be selected from various monosaccharides, oligosaccharides, and polysaccharides and used alone, or a plurality of kinds can be used in combination without any problem. Among them, examples of the monosaccharides include glucose, fructose, galactose, etc., and examples of the oligosaccharides include disaccharides such as maltose, sucrose, lactose, cellobiose, etc. And examples of the polysaccharides include amylose, dextrin, xanthan gum, curdlan, pullulan, cycloamylose, chitin, cellulose, starch, etc. In addition to these, gums such as plant mucilages such as gum arabic may be used, and further, a carboxylic acid can also be used as a curing agent for saccharides, particularly polysaccharides. Furthermore, examples of the synthetic polymer used as the water-soluble binder include polyethylene oxide, poly-α-hydroxyacrylic acid, acrylic acid copolymers, acrylic ester copolymers, methacrylic ester copolymers, polyacrylamide, anionized polyacrylamide, cationized polyacrylamide, polyaminoalkyl methacrylate, acrylamide / acrylic acid copolymers, polyvinylsulfonic acid, polystyrenesulfonic acid, sulfonated maleic acid polymers, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyvinyl methyl ether, polyether-modified silicone, or modified products thereof, etc. And these can be used alone or in combination of multiple selections. Furthermore, as the salts, those that solidify by adding water and then drying are used. For example, sulfates such as magnesium sulfate and sodium sulfate, bromides such as sodium bromide and potassium bromide, carbonates such as sodium carbonate and potassium carbonate, chlorides such as barium chloride, sodium chloride, and potassium chloride, etc. can be mentioned. In addition, examples of the protein include gelatin and glue. And the water-soluble binder as described above is desirably used at a ratio of 0.1 to 2.5 parts by mass in terms of solid content conversion considering only the non-volatile content with respect to 100 parts by mass of the refractory aggregate. Among them, a ratio of 0.2 to 2.0 parts by mass is particularly preferably adopted, and a predetermined coating layer is formed on the surface of the refractory aggregate. Here, the measurement of the solid content is carried out as follows. That is, 10 g of the sample is weighed and placed in an aluminum foil dish (length: 90 mm, width: 90 mm, height: 15 mm), placed on a hot plate maintained at 180 ± 1 °C, left for 20 minutes, then the sample dish is inverted and left on the hot plate for another 20 minutes. Next, the sample dish is taken out from the hot plate, cooled in a desiccator, and then weighed, and the solid content (mass %) is calculated by the following formula. Solid content (mass %) = [mass after drying (g) / mass before drying (g)] × 100 In addition, if the amount of the water-soluble binder used is too small, it becomes difficult to form a coating layer on the surface of the refractory aggregate, resulting in a problem that it becomes difficult to sufficiently solidify or cure the coated sand. On the other hand, if the amount of the water-soluble binder used is too large, the water-soluble binder adheres excessively to the surface of the refractory aggregate, making it difficult to form a uniform coating layer. At the same time, the coated sand may adhere to each other and agglomerate (composite granulation), which may have an adverse effect on the mold properties and make it difficult to remove the sand from the core after casting the metal. In the present invention, a dry coated sand formed by using the above-described water-soluble binder to form a coating layer on the surface of a refractory aggregate is the object. Such a coating layer can contain known additives as appropriate, if necessary. In order to incorporate such an additive into the coating layer, a method of premixing a predetermined additive into the water-soluble binder and then kneading or mixing it with the refractory aggregate, or a method of separately adding a predetermined additive to the refractory aggregate and uniformly kneading or mixing the whole together with the water-soluble binder, etc. are adopted. In the present invention, solid oxides and salts are advantageously used as such an additive. By containing these solid oxides and salts, the moisture resistance of the coated sand can be advantageously improved. Among them, as the solid oxides, for example, the use of oxides of elements such as silicon, zinc, magnesium, aluminum, calcium, lead, boron, etc. is effective. In particular, among them, the use of silicon dioxide, zinc oxide, aluminum oxide, and boron oxide is desirable. Among silicon dioxides, precipitated silicic acid and pyrogenic silicic acid are preferably used. On the other hand, as the salts, there are silicofluorides, silicates, phosphates, borates, tetraborates, carbonates, etc. Among them, the use of zinc carbonate, basic zinc carbonate, potassium metaborate, sodium tetraborate, and potassium tetraborate is desirable. And these solid oxides and salts are generally used in a proportion of about 0.5 to 5% by mass with respect to the non-volatile content in the water-soluble binder. In addition, as other additives, it is also effective to contain a coupling agent that strengthens the bond between the refractory aggregate and the water-soluble binder. For example, silane coupling agents, zirconium coupling agents, titanium coupling agents, etc. can be used. Also, it is effective to contain a lubricant that contributes to improving the fluidity of the coated sand. For example, waxes such as paraffin wax, synthetic polyethylene wax, montanic acid wax; fatty acid amides such as stearic acid amide, oleic acid amide, erucic acid amide; alkylene fatty acid amides such as methylene bis stearic acid amide, ethylene bis stearic acid amide; stearic acid, stearyl alcohol; metal stearates such as lead stearate, zinc stearate, calcium stearate, magnesium stearate; monoglyceryl stearate, stearyl stearate, hydrogenated oil, etc. can be used. Furthermore, as mold release agents, paraffin, wax, light oil, machine oil, spindle oil, insulating oil, waste oil, vegetable oil, fatty acid ester, organic acid, graphite fine particles, mica, vermiculite, fluorine-based mold release agents, silicone-based mold release agents, etc. can also be used. And these other additives are generally contained in a proportion of 5% by mass or less, preferably 3% by mass or less, based on the non-volatile components in the water-soluble binder. Incidentally, in the present invention, when manufacturing the pre-prepared dry coated sand, generally, a water-soluble binder as a binder is kneaded or mixed with refractory aggregates according to a conventional method together with additives used as necessary to uniformly mix them, and the surface of such refractory aggregates is coated with the water-soluble binder. By evaporating the moisture of such a water-soluble binder, a method of obtaining a dry powdery coated sand having normal temperature fluidity is adopted. However, the evaporation of the moisture in the coating layer at that time needs to be carried out quickly before the solidification or hardening of the water-soluble binder progresses. Therefore, in the present invention, after introducing (mixing) the water-soluble binder in the form of an aqueous solution to the refractory aggregates, it is desirable to remove the contained moisture within 5 minutes, more preferably within 3 minutes, to obtain a dry powdery coated sand. If the evaporation time becomes long, the mixing (kneading) cycle becomes long, the productivity decreases, and the time for the water-soluble binder to come into contact with CO2 in the air becomes long, increasing the risk of problems such as deactivation. Incidentally, the moisture content of the dry powdery coated sand thus obtained is generally preferably about 5 to 55% by mass, particularly 10 to 50% by mass, based on the solid content of the water-soluble binder. In particular, when the water-soluble binder is water glass, it will be formed as a coated sand prepared by adjusting such a moisture content to 20 to 50% by mass. Furthermore, in the manufacturing process of such dry-coated sand, as one of the effective means for rapidly evaporating the moisture in such a water-soluble binder, a method is adopted in which refractory aggregates are pre-heated and then kneaded or mixed with a water-soluble binder in the form of an aqueous solution. By kneading or mixing the water-soluble binder with the pre-heated refractory aggregates, the moisture in the water-soluble binder can be extremely rapidly evaporated by the heat of such refractory aggregates. Thus, the moisture content of the obtained coated sand can be effectively reduced, and a dry powder having normal-temperature fluidity can be advantageously obtained. The pre-heating temperature of such refractory aggregates is appropriately selected according to the moisture content and blending amount of the water-soluble binder, etc., but generally, it is desirable to heat the refractory aggregates to a temperature of about 100 to 160°C, preferably about 100 to 140°C. If this pre-heating temperature is too low, moisture evaporation cannot be effectively carried out, and drying takes a long time. Therefore, it is desirable to adopt a temperature of 100°C or higher. On the other hand, if the pre-heating temperature is too high, when the obtained coated sand is cooled, the hardening of the water-soluble binder component proceeds, and in addition, composite granulation progresses, which causes problems in the functions of the coated sand, particularly physical properties such as strength. And in the present invention, after using the dry coated sand obtained as described above and transporting it to the molding site, which is the production site of the mold, at the molding site, an aqueous medium containing a surfactant and / or a polyhydric alcohol is added to wet it, and then the obtained wetted coated sand is filled into a molding die to mold the target mold. Here, the step of wetting the dry coated sand by adding a surfactant and / or a polyhydric alcohol-containing aqueous medium simply involves putting the dry coated sand and a predetermined amount of the above aqueous medium into a suitable mixer and mixing them to wet the coated sand, so it can be carried out with extremely simple operations. Even at the molding site with a poor working environment, it can be carried out extremely simply and easily. Moreover, due to the addition of the surfactant, the compatibility between the water-soluble binder that becomes the coating layer of the coated sand and water is enhanced, and the fluidity of the wetted coated sand can be advantageously improved. With the improvement of the fluidity, the fillability of the coated sand into the mold forming die is improved, and it is possible to fill the mold forming die without defects, especially in the case of a mold forming die with a complex shape and a long cavity path from the filling port to the completion of filling. Also, when a polyhydric alcohol is added, the strength of the mold can be advantageously improved, and since it has a moisturizing effect, it has the advantage of improving the moisture retention of the wetted coated sand and extending the pot life. Furthermore, for such wetting of the dry coated sand, it only requires the addition of a surfactant and / or a polyhydric alcohol-containing aqueous medium, and it does not involve kneading a viscous water-soluble binder with refractory aggregates. Therefore, the workability is extremely good, and the wetted coated sand is not likely to adhere to the mixer, molding die, etc., so the device is not easily soiled. Also, at the molding site, since there is no need to handle a water-soluble binder, especially water glass, there is also an advantage that the operator is not likely to get chemical burns. Here, the surfactant and / or polyhydric alcohol-containing aqueous medium used in the present invention is prepared by adding at least one of the surfactant and the polyhydric alcohol to water at a predetermined ratio and dissolving or dispersing it. In addition, various additives pointed out in this specification and other additives known to those skilled in the art can be added and contained as necessary in this aqueous medium. When adding such an aqueous medium to dry coated sand, it is desirable to use the aqueous medium such that the amount of the surfactant is 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the solid content of the water-soluble binder in such coated sand. Among them, it is preferable to use the aqueous medium such that the amount is 0.5 to 15.0 parts by mass, particularly 0.75 to 12.5 parts by mass. As this surfactant, any of cationic, anionic, amphoteric, nonionic, silicone-based, and fluorine-based surfactants can be used. Specifically, examples of cationic surfactants include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like. Examples of anionic surfactants include fatty acid soaps, N-acyl-N-methylglycine salts, N-acyl-N-methyl-β-alanine salts, N-acylglutamic acid salts, alkyl ether carboxylates, acylated peptides, alkyl sulfonates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, dialkyl sulfosuccinate esters, alkyl sulfacetates, α-olefin sulfonates, N-acylmethyl taurine, sulfated oils, higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, secondary higher alcohol ethoxysulfates, polyoxyethylene alkyl phenyl ether sulfates, monoglycer sulfates, fatty acid alkanolamide sulfates, alkyl ether phosphates, alkyl phosphates, and the like. Further, examples of amphoteric surfactants include carboxybetaine type, sulfobetaine type, aminocarboxylates, imidazolinium betaines, and the like. In addition, examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene secondary alcohol ethers, polyoxyethylene alkyl phenyl ethers (e.g., Emulgen 911), polyoxyethylene sterol ethers, polyoxyethylene lanolin derivatives, polyoxyethylene polyoxypropylene alkyl ethers (e.g., Newpol PE-62), polyoxyethylene glycerin fatty acid esters, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyethylene glycol fatty acid esters, fatty acid monoglycerides, polyglycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, sucrose fatty acid esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, alkyl amine oxides, acetylene glycols, acetylene alcohols, and the like.Among various surfactants, those having a siloxane structure as a nonpolar moiety are particularly referred to as silicone-based surfactants, and those having a perfluoroalkyl group are referred to as fluorine-based surfactants. Examples of silicone-based surfactants include polyester-modified silicone, acrylic-terminated polyester-modified silicone, polyether-modified silicone, acrylic-terminated polyether-modified silicone, polyglycerin-modified silicone, aminopropyl-modified silicone, and the like. Examples of fluorine-based surfactants include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl trimethylammonium salts, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl group-containing oligomers, and the like. And these surfactants will be used alone or in combination of two or more. In addition, the polyhydric alcohol used instead of or together with the above surfactant is generally in a proportion of 0.1 to 20.0 parts by mass, preferably 0.5 to 15.0 parts by mass, and more preferably 0.75 to 12.5 parts by mass, based on 100 parts by mass of the solid content of the water-soluble binder in the dry coated sand. An aqueous medium containing such a polyhydric alcohol is added to the coated sand. Specific examples of the polyhydric alcohol used here include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, dipropylene glycol, propylene glycol, butylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 2-ethyl-1,3-hexanediol, 1,6-hexanediol, 1,2-heptanediol, 1,2-octanediol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, and the like. And these can be used alone or in combination of two or more. In addition, the aqueous medium containing the surfactant and / or polyhydric alcohol prepared as described above can also contain various known additives as required. For example, as a curing agent, an acid or an ester may be contained. Among them, as the acid, sulfuric acid, hydrochloric acid, carbonic acid, and sulfonic acids are preferable, and as the ester, lactones such as γ-butyrolactone and ε-caprolactone, and esters derived from alcohols having 1 to 10 carbon atoms and carboxylic acids having 1 to 10 carbon atoms such as ethylene glycol diacetate, triacetin, diethylene glycol diacetate, and triethylene glycol diacetate are preferable. The alcohol having 1 to 10 carbon atoms at this time may be monohydric or polyhydric. Further, as a curing accelerator, a metal salt, a metal powder, or the like may be contained. Therefore, as the metal salt, metal salts of calcium, magnesium, aluminum, iron, etc. are preferable, and as the metal powder, metal powders of calcium, magnesium, zinc, aluminum, silicon, etc. are preferable. Furthermore, drying accelerators such as alcohols such as methanol which are organic solvents, and ketones such as acetone and diacetone alcohol, preservatives such as PROXEL GXL [1,2-benzisothiazol-3(2H)-one] and PROXEL IB (polyhexamethylene biguanide) manufactured by Lonza Japan Co., Ltd., and silane coupling agents can also be added in a small amount and contained. In addition, for adjusting the mold strength, as a further additive, a second water-soluble binder can be added. As this second water-soluble binder, it can be appropriately selected from the water-soluble binders exemplified above, and it can be the same as or different from the water-soluble binder coating the coated sand, without any problem. By adding such a second water-soluble binder during mold molding, depending on the shape and size of the mold to be manufactured, when it is desired to increase the strength of the mold, etc., the strength can be improved by further adding the second water-soluble binder. Note that since the addition amount of such a second water-soluble binder is for adjustment, it is desirable to make the solid content of the second water-soluble binder added less than the solid content of the water-soluble binder in the coated sand. Furthermore, in accordance with the present invention, when adding an aqueous medium containing a surfactant and / or a polyhydric alcohol to dry coated sand to wet it, it is also effective to add spherical particles as an additional additive. By adding such spherical particles, it is possible to advantageously contribute to improving the fillability of the coated sand during mold casting. Such spherical particles may be added in a state mixed with the aqueous medium containing the surfactant and / or the polyhydric alcohol, or may also be added separately from the aqueous medium containing the surfactant and / or the polyhydric alcohol. Also, the addition amount of such spherical particles is about 0.1 to 20.0 parts by mass, preferably 0.5 to 15.0 parts by mass, and more preferably 0.75 to 12.5 parts by mass, based on 100 parts by mass of the solid content of the water-soluble binder in the coated sand. And as such spherical particles, those having a sphericity of 0.5 or more are usually desirable. Among them, those having a sphericity of preferably 0.7 or more, and more preferably 0.9 or more are advantageously used. Here, the sphericity means the average value of the aspect ratio (ratio of the minor axis to the major axis) obtained from the projected shape, by randomly selecting 10 single particles and observing them with a scanning electron microscope. Also, the average particle diameter of such spherical particles is about 0.1 to 25.0 μm, preferably about 1.0 to 20.0 μm. As long as the particles are spherical, the material is not particularly limited, but advantageously, spherical particles such as amorphous silica, alumina, and titanium oxide are preferably used. Incidentally, when wetting the above-mentioned dry coated sand, at the mold-making site, a predetermined amount of a surfactant and / or a polyhydric alcohol-containing aqueous medium is added to the dry coated sand and mixed with a normal mixer to form the intended wet coated sand. The amount of water supplied by the surfactant and / or the polyhydric alcohol-containing aqueous medium used there is appropriately determined according to the type and amount of the water glass component constituting the coated sand. Generally, in order to wet the dry coated sand, it is appropriately determined at a ratio of 0.5 to 5 parts by mass, preferably 0.75 to 4 parts by mass, more preferably 1 to 3 parts by mass, per 100 parts by mass of the coated sand. Further, the amount of the surfactant and / or the polyhydric alcohol-containing aqueous medium is determined by the amount of water, surfactant, or polyhydric alcohol added. Generally, it is appropriately determined at a ratio of 0.5 to 6 parts by mass, preferably 0.75 to 4 parts by mass, more preferably 1 to 3.5 parts by mass, per 100 parts by mass of the coated sand. If the addition amount of this surfactant and / or the polyhydric alcohol-containing aqueous medium is too small, wetting of the dry coated sand cannot be sufficiently achieved. Therefore, the mutual adhesion between the coated sands becomes weak, and the fluidity of the coated sand deteriorates, resulting in poor filling property into the mold, and problems such as a decrease in the strength of the obtained mold are caused. On the other hand, if the addition amount of the surfactant and / or the polyhydric alcohol-containing aqueous medium becomes too large, in addition to the problem that the filling operation into the mold becomes difficult, it takes time for the drying operation after filling into the mold, and problems such as an increase in the molding time occur. And in the present invention, using the wetted product of the dry coated sand obtained as described above, filling it into a predetermined mold, specifically into the molding cavity of the mold, and drying the wetted coated sand, a mold of the desired shape is to be molded. At this time, the wetted coated sand used has better fluidity and lower sticking and adhesive force between sands than the wetted coated sand obtained by directly kneading a water-soluble binder with refractory aggregates. Therefore, the filling property can be effectively improved, and the adhesion to the mold can also be effectively reduced, so that the contamination of the mold can be advantageously suppressed, and the mold release property of the mold from the mold can also be advantageously improved. In addition, for filling such wetted coated sand into the mold, a blow filling method using a blow head is preferably adopted, and the blow pressure at that time is about 0.2 to 0.6 MPa, preferably about 0.3 to 0.5 MPa. Also, in this way, when drying the wetted coated sand filled in the mold to solidify or cure it to mold the desired mold, it is desirable and recommended in the present invention to heat the mold in order to advantageously promote the drying of the wetted coated sand. By using this heated mold, the drying of the filled wetted coated sand can be effectively advanced, so that the molding time can be advantageously shortened. In general, the heating temperature of such a mold is in the range of 40 to 250 °C, preferably 70 to 200 °C, and more preferably 100 to 175 °C. If the heating temperature is less than 40 °C, it is difficult to fully exert the drying promotion effect by heating, and there is a problem that the molding time becomes long. If it is higher than 250 °C, the solidification or curing of the wetted coated sand filled in the mold becomes too fast, and its filling property deteriorates. In addition, problems such as the wetted coated sand being over-dried, losing its adhesiveness, having a low adhesion effect, and the strength of the obtained mold decreasing are also caused. And, in order to accelerate the drying of the wetted coated sand filled in the mold, it is also effective to directly heat such filled wetted coated sand with microwaves, and particularly when the mold is a resin mold, it is preferably adopted. Further, by passing heated air or dry air through the mold filled with wetted coated sand and passing it through the filled layer of wetted coated sand, it is also effective to promote drying and more rapidly achieve solidification or hardening of the filled wetted coated sand. In addition, by subjecting the mold filled with wetted coated sand to reduced-pressure suction, drying the inside of such mold under reduced pressure is also one of the effective drying means, and particularly in the case of a mold made of a material such as a resin mold that is susceptible to heat influence, it is advantageously adopted. Furthermore, in the present invention, as described above, by removing the moisture of the surfactant and / or polyhydric alcohol-containing aqueous medium used for the wetting from the wetted coated sand filled in the mold, the target mold will be molded. At this time, the water glass constituting the coating layer on the surface of the coated sand usually solidifies by evaporation and drying of water if no additives are added, and if oxides, salts, etc. are added as hardening agents, it will be hardened. And, for the hardening of such water glass, it is also effective to pass carbon dioxide gas or organic ester gas through the mold filled with wetted coated sand. By this, it is possible to rapidly harden the water glass as in the conventional case and advantageously increase the molding speed. As the organic ester gas, for example, methyl formate, ethyl formate, propyl formate, γ-butyrolactone, γ-propionolactone, ethylene glycol diacetate, diethylene glycol diacetate, glycerin diacetate, triacetin, propylene carbonate, etc. are used in a gaseous or misty state. In addition, according to the present invention, as a method of wetting dry coated sand and molding it with a predetermined molding die, various known molding methods can be adopted to manufacture a mold. Furthermore, the present invention can be implemented in various modified, corrected, improved, etc. aspects based on the knowledge of those skilled in the art. It should be understood that any such implementation aspects belong to the scope of the present invention as long as they do not deviate from the gist of the present invention. Hereinafter, the present invention will be further specifically clarified using several examples. However, it should be understood that the present invention is not to be construed in any way limited by the description of such examples. In the following examples and comparative examples, "%" and "parts" are both shown on a mass basis unless otherwise specified. In addition, the evaluation of the moisture content, fillability, filling fluidity, and strength of the coated sand (CS) obtained in the examples and comparative examples was performed as follows, respectively. -Measurement of the moisture content relative to the solid content of the water-soluble binder- As long as it is a method capable of measuring the moisture content in CS, it is not particularly limited, and an effective measurement method can be selected according to the type of binder. An example of the measurement method is shown below. (When the water-soluble binder is water glass) Weigh 10 g of each CS and place it in a crucible that has been air-fired and weighed. After heating it at 900 °C for 1 hour, use the mass reduction percentage (%) to calculate the moisture content (W1) in CS from the following formula (1). The weighing is measured up to the fourth decimal place. Next, calculate the binder solid content (B1) relative to CS using the following formula (2), and then calculate the moisture content relative to the binder solid content from the moisture content in CS using the following formula (3). W1 = [(M1 - M2) / M3] × 100 ...(1) [W1: Moisture content in CS (%), M1: Total mass of the crucible and CS before firing (g), M2: Total mass of the crucible and CS after firing (g), M3: Mass of CS before firing (g)] B1 = [B2 / (100 + B2)] × (100 - W1) ··· (2) [B1: Solid content of the binder with respect to CS (%), B2: Solid content of the binder added per 100 parts of sand (parts), W1: Moisture content in CS (%)] W2 = (W1 / B1) × 100 ··· (3) [W2: Moisture content with respect to the solid content of the binder (%), W1: Moisture content in CS (%), B1: Solid content of the binder with respect to CS (%)] (When the water-soluble binder is a water-soluble resol resin) Weighed 2.0 g of each CS and put it into a flask of a Karl Fischer moisture meter (manufactured by Hiranuma Sangyo Co., Ltd.: AQV - 7 HIRANUMA AQUACOUNTER) containing 100 ml of Aquamicron ML (manufactured by Mitsubishi Chemical Corporation), a dehydration solvent [previously, the Karl Fischer reagent (manufactured by Sigma - Aldrich Laborchemikalien Gmbh: Hydranal Composite 5) was dropped to make the moisture content 0]. After that, it was stirred for several minutes using a magnetic stirrer, and then the Hydranal Composite 5 was dropped to quantify the moisture content (W1) in CS. Then, from the moisture content (W1) in CS, the moisture content (W2) with respect to the solid content of the binder was calculated using the above formulas (2) and (3). -Measurement of fillability and evaluation of filling fluidity- For each CS of each example or each comparative example, one mold half 5 having a mold split surface as shown in FIG. 1 and the other mold half (5) having a symmetric mold split surface are combined to form a molding die. The die is filled from its filling port 6 at a blow pressure of 0.3 MPa, molded at a mold temperature of 150 ° C. and a molding time of 180 seconds, and the mass (g) of the obtained mold is measured. Next, in the molded mold, the filling state of the CS with respect to the flow paths 1 to 4 in the cavity is visually evaluated. The filling state of each flow path is judged as follows: ○: filled, △: filled but slightly defective, ×: not filled and the flow path portion is defective. Note that those in which the flow paths 2 to 4 are filled and the flow path 1 is filled with △ or more are judged as acceptable. -Measurement of flexural strength- For test pieces with dimensions of width: 1.0 cm × height: 1.0 cm × length: 6.0 cm obtained using each CS, the breaking load is measured using a measuring instrument (manufactured by Takachiho Seiki Co., Ltd.: Digital Foundry Sand Strength Tester). Then, using the measured breaking load, the flexural strength is calculated by the following formula (4). Flexural strength (N / cm 2 ) = 1.5 × LW / ab 2 ···(4) [L: distance between fulcrums (cm), W: breaking load (N), a: width of test piece (c m), b: thickness of test piece (cm)] -Manufacturing Example 1 of Dry CS- As a refractory aggregate, commercially available artificial sand for casting, Lunamos #80 (trade name: manufactured by Kao Quaker Co., Ltd.), was prepared. As the water glass used as a binder (water-soluble binder), a commercially available product: sodium silicate No. 2 (trade name: manufactured by Fuji Chemical Co., Ltd., molar ratio of SiO2 / Na2O: 2.5, solid content: 41.3%) was prepared. Then, after heating the above Lunamos #80 to a temperature of about 120°C, it was put into a Shinagawa-type universal stirrer (5DM-r type) (manufactured by Dalton Co., Ltd.). Furthermore, the water glass was added at a ratio of 1.21 parts (solid content: 0.50 parts) per 100 parts of Lunamos #80, kneaded for 3 minutes, while evaporating the moisture, and stirred and mixed until the sand grain lumps disintegrated, and then taken out to obtain dry-coated sand: CS1 with free fluidity at room temperature. When the moisture content of CS1 after such kneading was measured, it was 0.2% ( / CS). -Manufacturing Example 2 of Dry CS- As the water glass of the binder, a commercially available product: sodium silicate No. 1 (trade name: manufactured by Fuji Chemical Co., Ltd., molar ratio of SiO2 / Na2O: 2.1, solid content: 48.5%) was used, and the addition amount of such water glass was 1.03 parts (solid content 0.50 parts) per 100 parts of Lunamos #80. Except for this, according to the same procedure as in Manufacturing Example 1 above, dry CS2 was obtained. When the moisture content of CS2 after its kneading was measured, it was 0.2% ( / CS). -Manufacturing Example 3 of Dry CS- As the water glass of the binder, a commercially available product: sodium silicate No. 3 (trade name: manufactured by Fuji Chemical Co., Ltd., molar ratio of SiO2 / Na2O: 3.2, solid content: 38%) was prepared, and the addition amount of this water glass was 1.32 parts (solid content 0.50 parts) per 100 parts of Lunamos #80. Except for this, according to the same procedure as in Manufacturing Example 1 above, dry CS3 was obtained. When the moisture content of CS3 after its kneading was measured, it was 0.2% ( / CS). -Manufacturing Example 4 of Dry CS- As the water-soluble resol which is a binder (water-soluble binder), a commercially available product: HPR833 (trade name: manufactured by Asahi Organic Materials Co., Ltd., non-volatile component: 45%) was prepared. Then, after heating the above-mentioned Lunamos #80 to a temperature of about 120°C, it was put into a Shinagawa type universal stirrer (5DM-r type) (manufactured by Dalton Co., Ltd.). Further, the water-soluble resol was added at a ratio of 1.33 parts (resin component 0.6) per 100 parts of Lunamos #80, and kneading was carried out for 60 seconds while evaporating the moisture, and stirring and mixing were carried out until the sand grain mass collapsed. Then, by taking it out from the stirrer, dry CS4 with free fluidity at normal temperature was obtained. Also, when the moisture content of the obtained kneaded CS4 was measured, it was 0.2% ( / CS). - Manufacturing Example 1 of Wet CS As the refractory aggregate, commercially available artificial sand for casting, Lunamos #80 (trade name: manufactured by Kao Quaker Co., Ltd.) was prepared, and as the water glass of the binder, a commercially available product: No. 2 sodium silicate (trade name: manufactured by Fuji Chemical Co., Ltd.) was prepared. Next, the above-mentioned Lunamos #80 at normal temperature was put into a Shinagawa type universal stirrer (5DM-r type) (manufactured by Dalton Co., Ltd.), and further, the water glass was added at a ratio of 1.21 parts (solid component 0.50 part) per 100 parts of Lunamos #80, and 0.46 part of water was added, and kneading was carried out for 3 minutes to obtain wet CS5. When the moisture content of the kneaded CS5 was measured, it was 1.15% ( / CS), and when the dynamic angle of repose was measured, since it was in a wet state and did not have fluidity at normal temperature, the dynamic angle of repose could not be measured. - Molding Example of Mold (Example 1) As an anionic surfactant, a commercially available product: Orphen PD-301 (trade name: manufactured by Nissin Chemical Industry Co., Ltd.) was used. 0.02 part of it was added to 2 parts of water, and mixed and stirred to obtain an aqueous solution containing a surfactant as an aqueous medium. Then, 100 parts of CS1 obtained in the above dry-state Production Example 1 was put into a Shinagawa type universal stirrer (5DM-r type), and the aqueous solution containing a surfactant as the above aqueous medium was further added (therefore, the surfactant was in a ratio of 4.0 parts with respect to 100 parts of the solid content of water glass in CS1), and stirred for 1 minute. The thus-obtained wet CS was put into a blow tank, and blown into a molding die composed of a pair of the above mold halves 5 heated to 150°C at a gauge pressure of 0.3 MPa for filling. After holding for 180 seconds, it was removed from the molding die to obtain a mold as a test piece. (Example 2) 0.05 part of an anionic surfactant (in a ratio of 10 parts with respect to 100 parts of the solid content of water glass which is a water-soluble binder) was added to 2 parts of water, and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1 except that an aqueous medium was used. (Example 3) 0.06 part of an anionic surfactant (in a ratio of 12 parts with respect to 100 parts of the solid content of water glass) was added to 2 parts of water, and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1 except that an aqueous medium was used. (Example 4) A mold (test piece) was produced according to the same procedure as in Example 2 except that dry CS1 was changed to dry CS2. (Example 5) A mold (test piece) was produced according to the same procedure as in Example 2 except that dry CS1 was changed to dry CS3. (Example 6) As a silicone-based surfactant, a commercially available product: KF643 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared. Using 0.005 parts (at a ratio of 1 part per 100 parts of the solid content of water glass), it was added to 2 parts of water and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 7) As a silicone-based surfactant, a commercially available product: KF640 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared. Using 0.005 parts (at a ratio of 1 part per 100 parts of the solid content of water glass), it was added to 2 parts of water and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 8) A mold (test piece) was produced according to the same procedure as in Example 2, except that a commercially available product: Lipolan LB-440 (trade name: manufactured by Lion Corporation) was used as the anionic surfactant. (Example 9) A mold (test piece) was produced according to the same procedure as in Example 2, except that a commercially available product: Surfynol 465 (trade name: manufactured by Nisshin Chemical Industry Co., Ltd.) was used as the nonionic surfactant. (Example 10) A mold (test piece) was produced according to the same procedure as in Example 2, except that a commercially available product: Surfynol 485 (trade name: manufactured by Nisshin Chemical Industry Co., Ltd.) was used as the nonionic surfactant. (Example 11) Using a commercially available product: Orfin PD-301 (trade name: manufactured by Nisshin Chemical Industry Co., Ltd.) as the anionic surfactant, 0.02 parts of it (at a ratio of 4 parts per 100 parts of the solid content of water glass), and 0.04 parts of glycerin as the polyhydric alcohol (at a ratio of 8 parts per 100 parts of the solid content of water glass), were added to 2 parts of water and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 12) As an anionic surfactant, a commercially available product: Orfin PD-301 (trade name: manufactured by Nissin Chemical Industry Co., Ltd.) was used, 0.05 part of which (at a ratio of 10 parts per 100 parts of the solid content of water glass) and, as a polyhydric alcohol, 0.04 part of glycerin (at a ratio of 8 parts per 100 parts of the solid content of water glass) were added to 2 parts of water, and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 13) As a surfactant, a commercially available product: Orfin PD-301 (trade name: manufactured by Nissin Chemical Industry Co., Ltd.) was used, 0.05 part of which (at a ratio of 10 parts per 100 parts of the solid content of water glass) was added to 2 parts of water, and mixed and stirred. To the obtained aqueous medium, 0.05 part of HS311 (trade name: manufactured by Nippon Steel & Sumikin Materials Co., Ltd.), which is spherical particles (at a ratio of 10 parts per 100 parts of the solid content of water glass), was added and used. A mold (test piece) was produced according to the same procedure as in Example 1. When the aspect ratio of HS311 was measured, it was 0.91. (Example 14) A mold (test piece) was produced according to the same procedure as in Example 2, except that dry CS1 was changed to dry CS4. (Example 15) As a polyhydric alcohol, glycerin was used, 0.04 part of which (at a ratio of 8 parts per 100 parts of the solid content of water glass) was added to 2 parts of water, and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 16) As a polyhydric alcohol, a commercially available polyethylene glycol: PEG400 (product name: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used, 0.04 part of which (at a ratio of 8 parts per 100 parts of the solid content of water glass) was added to 2 parts of water, and mixed and stirred. A mold (test piece) was produced according to the same procedure as in Example 1, except that an aqueous medium was used. (Example 17) As the polyhydric alcohol, glycerin was used. 0.04 part thereof (at a ratio of 8 parts with respect to 100 parts of the solid content of the water glass) was added to 2 parts of water, and 0.05 part of HS311 (trade name: manufactured by Nippon Steel & Sumikin Materials Co., Ltd.) as spherical particles (at a ratio of 10 parts with respect to 100 parts of the solid content of the water glass) was added to the aqueous medium obtained by mixing and stirring, and a mold (test piece) was produced according to the same procedure as in Example 1, except for the above use. (Example 18) A mold (test piece) was produced according to the same procedure as in Example 15, except that dry CS1 was changed to dry CS4. (Comparative Example 1) A mold (test piece) was produced according to the same procedure as in Example 1, except that ordinary tap water without addition of a surfactant or a polyhydric alcohol was used as the aqueous medium. (Comparative Example 2) The wet CS5 was put into a blow tank and blown into a molding die heated to 150 ° C. at a gauge pressure of 0.3 MPa for filling. Then, after holding in the mold for 180 seconds, it was taken out from the molding die to obtain a mold (test piece). (Comparative Example 3) A mold (test piece) was produced according to the same procedure as in Example 14, except that ordinary tap water without addition of a surfactant or a polyhydric alcohol was used as the aqueous medium. For each of the molds (test pieces) obtained in the above Examples 1 to 18 and Comparative Examples 1 to 3, the moldability was measured and the filling fluidity was evaluated according to the above test method, and the strength was measured, and the results are shown in Tables 1 to 3 below. As is clear from the results of Tables 1 to 3, in Examples 1 to 18, it is recognized that the molds obtained from the CS wet-molded using the surfactant and / or polyhydric alcohol-containing aqueous medium according to the present invention all show good moldability and filling fluidity of the coated sand. On the other hand, in the molds shaped from those obtained by wetting dry CS with only water or directly forming wet CS using water glass according to Comparative Examples 1 to 3, it is recognized that the filling property and filling fluidity of CS into the molding die are not sufficient. In addition, it is recognized that the molds obtained in Examples 1 to 18 have effectively improved strength compared to the comparative examples using CS wetted by kneading only water. 1 - 4 Flow path 5 Mold half 6 Filling port

Claims

DEPCT6303 / 04 / 25621. Method of manufacturing molding dies, in which an aqueous medium containing a surfactant and / or polyhydric alcohol is added to dry coated sand obtained by coating the surface of heat-resistant aggregate particles with a water-soluble binder while the coated sand is moistened, and the moistened coated sand is 1. The molding process under Patent 1, where the aqueous medium is added to the coated sand at a ratio of 0.5-6 parts by mass relative to 100 parts by mass of the coated sand.

2. The molding process under Patent 1 or 2, where the aqueous medium is added to the coated sand in such a way that the amount of surfactant is within the range of 0.1-20.0 parts by mass relative to 100 parts by mass of the water-soluble binder solids in the coated sand.

3. The molding process under Patent 1 to 3, where the aqueous medium is added to the coated sand in such a way that the amount of polyhydric alcohol is within the range of 0.1-20.0 parts by mass.0 parts by mass relative to 100 parts by mass of the solid content of the water-soluble binder in the coated sand.

5. Any of the mold manufacturing methods under claims 1 to 4, whereby spherical particles are added to the coated sand when the dry coated sand is moistened.

6. Any of the mold manufacturing methods under claim 5, whereby spherical particles are added to the coated sand at a ratio of 0.1-20.0 parts by mass relative to 100 parts by mass of the solid content of the water-soluble binder in the coated sand.

7. Any of the mold manufacturing methods under claims 1 to 6.

7. One of the molding methods under claims 1 through 7, whereby a second water-soluble binder is added to the dry coating sand when the dry coating sand is moistened.

8. One of the molding methods under claims 1 through 7, whereby the water content in the dry coating sand is 5-55% by mass relative to the solid content of the water-soluble binder.

9. One of the molding methods under claims 1 through 8, whereby at least one of the thermosetting resins, saccharides, proteins, synthetic polymers, salts and inorganic polymers is used as a water-soluble binder. 10.

11. Any of the claims 1 through 10, in which hot or dry air is passed through a molding die filled with moist sand coating; 12. Any of the claims 1 through 11, in which carbon dioxide gas or organic ester gas is passed through a molding die filled with moist sand coating; 13. Any of the claims 1 through 12, in which the molding die is heated to a temperature of 40°C–250°C. ----------------------------------------------------------- Page 1 of 2 pages of Claims 1. A method of manufacturing casting molds in which an aqueous solution containing a surfactant and / or polyhydric alcohol is added to dry-state coated sand obtained by coating the surface of refractory concrete aggregate particles with a water-soluble binder; for example, the coated sand is moistened, and the moistened coated sand is then added to a molding dies to be shaped into a casting mold.

21. The method of manufacturing casting molds according to claim 1 in which the aqueous solution is added to the coating sand at a ratio of 0.5-6 parts by mass with a proportion of 100 parts by mass of coating sand.

3. The method of manufacturing casting molds according to claim 1 or 2 in which the aqueous solution is added to the coating sand in which the amount of surfactant is in the range of 0.1-20.0 parts by mass with 100 parts by mass of the amount of water-soluble binder solids in the coating sand.

4. The method of manufacturing casting molds according to one of claims 1 through 3 in which the aqueous solution is added to the coating sand such that the amount of polyhydric alcohol is in the range of 0.1-20.0 parts by mass with 100 parts by mass of the amount of water-soluble binder solids in the coating sand.

5. The method of manufacturing casting molds according to one of claims 1 through 4 in which spherical particles are added to the coating sand when the dry coating sand is moistened.

6. The method of manufacturing casting molds according to claim 5, in which spherical particles are added to the coating sand at a ratio of 0.1-20.0 parts by mass with 100 parts by mass of the amount of solid of the soluble binder in the coating sand. 7.

8. A method of manufacturing molds under any of the claims 1 through 6 where a second water-soluble binder is added to the dry coating sand when the coating sand is moistened.

9. A method of manufacturing molds under any of the claims 1 through 7 where the water content in the dry coating sand is 5-55% by mass relative to the solid content of the water-soluble binder.

10. A method of manufacturing molds under any of the claims 1 through 8 where at least one of the thermosetting resins, saccharides, proteins, synthetic polymers, salts, and inorganic polymers are used as water-soluble binders.

11. A method of manufacturing molds under claim 9 where the inorganic polymer is liquid glass.

12. A method of manufacturing molds under any of the claims 1 through 10 where warm or dry air is passed through the mold with moistened coating sand. A method of manufacturing a casting mold according to one of the claims 1 through 11 in which carbon dioxide or an organic ester gas is passed through a mold with moistened, coated sand.13.A method of manufacturing a casting mold pursuant to any of the claims 1 through 12 where the mold is heated to a temperature of 40 degrees Celsius to 250 degrees Celsius.