JP6923533B2 - Mold manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a mold, and in particular, while improving workability at a molding site, which is a manufacturing site for a mold, the mold is advantageously manufactured, and the filling property of coated sand and the strength of the mold are improved. It's about how you can make it happen.

Conventionally, as one of the methods for manufacturing a mold used for casting a molten metal, a coated sand made by coating a mold sand made of a fire-resistant aggregate with a predetermined binder is used to obtain a desired shape. A method of molding a mold is adopted, and as a binder used there, for example, in "Casting Engineering Handbook" edited by the Japan Foundry Engineering Society, pp. 78-90, an inorganic type such as water glass is used. In addition to binders, organic binders using resins such as phenol resin, furan resin, and urethane resin have been clarified, and there, self-hardening molds are molded using these binders. The method has also been clarified.

Then, using water glass, which is one of the inorganic binders among these binders, a coated sand formed by covering a predetermined refractory aggregate (mold sand) is formed, and then molding of the mold is performed. Various methods have been proposed as methods for performing the above. For example, in Japanese Patent Application Laid-Open No. 2008-036712, silica sand (refractory aggregate), alkali silicate (water glass), and amorphous carbon dioxide have been proposed. Mold materials or mold parts containing silicon-containing aggregates have been identified. Further, there, at the molding site of the mold, the silica sand, water glass and amorphous silicon dioxide are kneaded, and a wet alkaline silicate (water glass) is adhered to the surface of the silica sand. It is made into a mold material (coated sand) in a wet form (wet state), and it is filled in a predetermined molding mold so that a mold having a desired shape is formed.

However, such a wet coated sand reacts with carbon dioxide in the air and gradually hardens, so that the pot life is short and the storage stability is not sufficient. Generally, the coated sand in such a wet state is manufactured at the molding site of the mold and then filled in the molding mold as it is to mold the target mold. Therefore, in order to transport finely powdered refractory aggregate and water glass to a molding site with many obstacles and knead them with a mixer to obtain a wet coated sand, the viscosity of the water glass is high. Because of this, it takes a lot of time and effort, and the viscosity of water glass makes it difficult to mix with refractory aggregates. In addition, mixers for mixing and molding molds for molding, etc. There is an inherent problem of poor molding workability, such as the equipment becoming dirty easily. Moreover, since the work is performed at the molding site, there is a high risk that the worker will be injured by the strongly alkaline water glass.

On the other hand, unlike the wet coated sand as described above, water glass is used as a binder to form a dried coating layer of such a binder on the surface of the refractory aggregate. A dry coated sandwich having room temperature fluidity is disclosed in Japanese Patent Application Laid-Open No. 2012-076115. There, such dry coated sand is coated with a solid coating layer containing a water-soluble inorganic compound such as water glass as a binder, which forms a mold for molding. A method has been clarified in which the coated sand is solidified by aerating water vapor after being filled in the cavity to obtain a desired mold. In such a molding method, there is a method. Since it is necessary to blow steam into the molding mold after filling the coated sand in a dry state, and therefore it is necessary to provide a special steam blowing device, the conventional device can be used as it is. There is an inherent problem that it cannot be done and increases the manufacturing cost of the mold.

Moreover, there, after wetting the dry coated sand filled in the molding mold with steam, it is solidified by drying it to form the mold, so such a wet coated In order to effectively dry the sand, it is necessary to add a new process of blowing heated gas in addition to blowing steam, which leads to molding from filling into the mold to drying solidification to hardening. There is also the inherent problem of longer cycles and reduced mold productivity.

Japanese Unexamined Patent Publication No. 2008-036712 Japanese Unexamined Patent Publication No. 2012-076115

"Handbook of Casting Engineering", pp. 78-90

Here, the present invention has been made against the background of such circumstances, and the problem to be solved thereof is to improve the workability at the molding site while improving the filling property of the coated sand and the strength of the mold. The purpose is to provide a method for manufacturing a mold that can effectively achieve the above, and another issue is that there is no need to newly install a special device, and basically the device for conventional molding is used as it is. It is an object of the present invention to provide a method capable of advantageously producing a desired mold.

Then, in order to solve the above-mentioned problems, the present invention can be preferably carried out in various aspects as listed below, and each aspect described below is adopted in any combination. It is possible. It should be noted that the aspects or technical features of the present invention are not limited to those described below, and can be recognized based on the invention idea that can be grasped from the description of the entire specification. Should be understood.

(1) An aqueous medium containing a surfactant and / or a polyhydric alcohol is added to a dry coated sand obtained by coating the surface of a fire-resistant aggregate with a water-soluble binder. A method for producing a casting mold, which comprises filling a mold with the obtained moistened coated sand after moistening and molding.
(2) The aqueous medium is based on 100 parts by mass of the coated sand.
The method for producing a mold according to the above aspect (1), wherein the coating is added to the coated sand at a ratio of 0.5 to 6 parts by mass.
(3) The aqueous medium is added so that the surfactant is 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 above-described aspect (
1) Or the method for producing a mold according to the above aspect (2).
(4) The aqueous medium is added so that the polyhydric alcohol is 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 producing a mold according to any one of the above-mentioned mode (1) to the above-mentioned aspect (3).
(5) The embodiments (1) to (4), wherein spherical particles are further added when the dry coated sand is moistened.
The method for producing a mold according to any one of the above.
(6) The embodiment (5), wherein the amount of the spherical particles added 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 producing a mold.
(7) The embodiment (1), wherein a second water-soluble binder is further added when the dry coated sand is moistened.
The method for producing a mold according to any one of the above aspects (6).
(8) The embodiment (8), wherein 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 producing a mold according to any one of 1) to (7).
(9) The embodiment (1), wherein as the water-soluble binder, one or two or more of thermosetting resins, sugars, proteins, compound polymers, salts and inorganic polymers are selected and used. ) To the method for producing a mold according to any one of the above aspects (8).
(10) The embodiment (10), wherein the inorganic polymer is water glass.
The method for producing a mold according to 9).
(11) One of the above-described embodiments (1) to (10), wherein heated air or dry air is aerated in the molding mold filled with the moistened coated sand. The method for producing a mold according to the description.
(12) One of the above-described embodiments (1) to (11), wherein the carbon dioxide gas or the organic ester gas is allowed to be aerated in the molding mold filled with the moistened coated sand. The method for producing a mold according to the description.
(13) The method for producing a mold according to any one of the above aspects (1) to (12), wherein the molding die is heated to a temperature of 40 ° C. to 250 ° C.

As described above, in the present invention, using a water-soluble binder such as water glass as a binder, first, a dry coated sand is prepared in advance, and then it is brought to the molding site. At the molding site, it is possible to mold the desired mold simply by preparing a surfactant and / or a polyhydric alcohol-containing aqueous medium for moistening the dry coated sand. In a molding site where the working environment is poor, there is no need to knead the viscous water glass with the refractory aggregate, and therefore the workability at the molding site can be significantly improved. Further, in the mixer, even if the dry coated sand is moistened by adding a surfactant and / or an aqueous medium containing a polyhydric alcohol and mixing the mixture, the mixture adheres to the inside of the mixer. In addition to the fact that there are few water-soluble binders and the equipment is not easily soiled, workers do not handle water-soluble binders such as water glass at the molding site. There was no fear of receiving it.

Moreover, since the surfactant and / or the polyhydric alcohol is added to the aqueous medium used for moistening the coated sand, the filling property of the coated sand at the time of molding is advantageously improved. At the same time, the feature that the strength of the obtained mold can be effectively improved can be exhibited advantageously.

Further, in the present invention, the dry coated sand prepared in advance hardly changes with time due to carbon dioxide gas in the air unless an aqueous medium is added, and is excellent in storage stability. A large amount of the coated sand in the state is prepared in advance at a place different from the molding site, and at the molding site, a part thereof is used and a surfactant and / or a polyhydric alcohol-containing aqueous medium is added thereto. After moistening, it has the practical advantage of being able to mold the desired mold, and moistened such dry coated sand can be obtained at the molding site as in the past. Compared to the wet coated sand produced, the filling property into the molding die is better, and the mold releasability from the molding die of the molded mold is also improved, which is a special feature.

Further, according to the method for producing a mold according to the present invention, at the molding site, a moistened coated sand is simply filled in a molding mold and heated or the like, and a surface active agent and / or a polyhydric alcohol-containing aqueous solution is used. Since the water vapor of the medium is evaporated and dried, solidified or hardened, it is necessary to newly install special equipment such as a water vapor generator and a water vapor ventilation mechanism, as in the case of using the dry coated sand as it is. Basically, it is possible to perform molding using the conventional equipment as it is, which can avoid an increase in equipment cost and, in turn, an increase in mold manufacturing cost. It is not necessary to newly adopt a steam blowing process, which makes it possible to advantageously avoid a long molding cycle.

It is a front schematic view which shows one mold split surface of the mold semi-body which constitutes the mold used for the evaluation of the filling property and the filling fluidity.

By the way, in the method for producing a mold according to the present invention, in a dry coated sand prepared in advance, generally, a water-soluble binder in an aqueous solution is mixed with a refractory aggregate as a binder, and then A dry coating layer made of the solid content of the water-soluble binder, which is a binder, is produced by evaporating the water from the mixture, in other words, by evaporating the water content of the water-soluble binder in the aqueous solution state. It is in a dry state and has good room temperature fluidity, which is formed on the surface of the refractory aggregate at a predetermined thickness. In particular, in the present invention, the water content in such a dry coated sand is preferably 5 to 55% by mass, preferably 10 to 50% by mass, based on the solid content of the water-soluble binder. It is desirable to be% by mass. In particular, when the water-soluble binder is water glass, it is preferably 20 to 50% by mass. If the amount of water is less than 5% by mass, the water-soluble binder such as water glass is vitrified, and even if water is added again, there is a problem that the solution does not return, while 55% by mass. If the amount is more than the above, the problem of not being in a dry state arises.

Here, in the dry coated sand used in the present invention, the range of the amount of water that gives the dry state differs depending on the properties of the water-soluble binder. Therefore, the dry state in the present invention means that the measured value of the dynamic angle of repose can be obtained when the dynamic angle of repose is measured regardless of the amount of water. The dynamic rest angle means that the coated sand is housed in a cylinder in which one end in the axial direction is closed with a transparent plate material (for example, in a container having a diameter of 7.2 cm and a height of 10 cm). Coated that is flowing in a cylinder by holding the coated sand up to half the volume), holding the axis in the horizontal direction, and rotating it around the horizontal axis at a constant speed (for example, 25 rpm). The slope of the sand layer becomes a flat surface, and the angle formed between the slope and the horizontal plane is measured. On the other hand, when the coated sand is moist 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, it is called a wet coated sand. I will do it.

In the present invention, by using the dry coated sand as described above, the pot life can be extended and the storage stability can be advantageously improved. Therefore, such a dry coated sand is molded. It is possible to prepare a large amount in advance at a place such as a factory, which is different from the site, and transport a part of it to the molding site so that it can be used for molding the target mold. It can greatly contribute to the efficiency of molding work.

The refractory aggregate constituting the coated sand as described above is a refractory substance that functions as a base material of the mold, and is a variety of refractory granular or powdery materials that have been conventionally used for the mold. Can be used, specifically, special sands such as alumina sand, olivine sand, zircon sand, and chromate sand, as well as silica sand and recycled silica sand, ferrochrome slag, ferronickel slag, and refractory slag. Such as slag-based particles; artificial particles such as alumina-based particles and murite-based particles and their regenerated particles; alumina balls, magnesia clinker and the like can be mentioned. It should be noted that these fire-resistant aggregates may be fresh sand, or recycled sand or recovered sand that has been used once or multiple times as casting sand for molding a mold, and further, such regeneration. There is no problem even if it is mixed sand made by adding new sand to sand or recovered sand and mixing them. Then, such a refractory aggregate is generally used as having a particle size of about 40 to 130 in AFS index, preferably about 60 to 110.

Further, the binder for coating the refractory aggregate as described above is also called a binder, and in the present invention, a water-soluble binder is used. As the water-soluble binder, any of inorganic polymers, thermosetting resins, saccharides, synthetic polymers, salts, and proteins can be used as long as it is water-soluble. Then, these may be used alone or may be used by selecting two or more, but it is particularly preferable to use an inorganic polymer. Further, these water-soluble binders may be used after being diluted with water or a solvent in advance.

Examples of the inorganic polymer used as such a water-soluble binder include water glass, colloidal silica, alkyl silicate, bentonite, cement, etc. Among them, water glass is preferably used. Become. Further, such water glass is a soluble silicic acid compound, and examples of such a silicic acid compound include sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, lithium silicate, and ammonium silicate. However, in particular, in the present invention, sodium silicate (sodium silicate) is advantageously used.

Further, such sodium silicate is usually classified into the types of Nos. 1 to 5 according to the molar ratio of _{SiO 2} / Na _{2 O and used.} Specifically, sodium silicate No. 1 has _{a molar ratio of SiO 2} / Na ₂ O of 2.0 to 2.3, and sodium silicate No. 2 has a molar ratio of SiO ₂ / Na ₂ O. The molar ratio is 2.4 to 2.6, and sodium silicate No. 3 has _{a molar ratio of SiO 2} / Na ₂ O of 2.8 to 3.3. In addition, sodium silicate No. 4 has _{a molar ratio of SiO 2} / Na ₂ O of 3.3 to 3.5, and sodium silicate No. 5 has a molar ratio of _{SiO 2} / Na _{2 O.} Is 3.6 to 3.8. Among these, sodium silicate Nos. 1 to 3 are also specified in JIS-K-1408. Then, these sodium silicates may be used alone or in a mixed manner, and _{the molar ratio of SiO 2} / Na ₂ O can be adjusted by mixing them.

In order to advantageously obtain the dry coated sand used in the present invention, sodium silicate constituting water glass used as a binder generally has a molar ratio of _{SiO 2} / Na _{2 O of 1.9 or more.} , It is preferably 2.0 or more, more preferably 2.1 or more, and in the above-mentioned classification of sodium silicate, sodium silicate corresponding to Nos. 1 and 2 is used particularly advantageously. Become. Such sodium silicate No. 1 and No. 2 respectively provide a dry coated sandwich having stable and good characteristics even in a wide range of sodium silicate concentration in water glass. _{Further, the upper limit of the molar ratio of SiO 2} / Na ₂ O in such sodium silicate is appropriately selected according to the characteristics of water glass in the form of an aqueous solution, but is generally 3.5 or less. It is preferably 3.2 or less, more preferably 2.7 or less. Here, when _{the molar ratio of SiO 2} / Na ₂ O is smaller than 1.9, the viscosity of the water glass becomes low, and it becomes difficult to bring it into a dry state unless the water content is considerably lowered. On the other hand, if it is larger than 3.5, the solubility in water is lowered, and the refractory aggregate is not sufficiently adhered to the surface, so that the bonding area cannot be increased and the mold strength is lowered.

Further, the water glass used in the present invention means a solution of a silicic acid compound in a state of being dissolved in water, and is used in the state of a stock solution as purchased on the market, or water is added to such a stock solution. It will be used in a diluted state after being added. The solid content (water glass component) obtained by removing volatile substances such as water and solvent from such water glass is called a non-volatile content, which corresponds to the above-mentioned soluble silicic acid compound such as sodium silicate. To do. Further, 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 corresponds to the ratio excluding the amount of water in the undiluted solution when it is composed only of the undiluted solution, while the undiluted solution is made into water. When a diluted solution obtained by diluting is used, the residual 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. Will be done.

The non-volatile content in such water glass will be set to an appropriate ratio depending on the type of the water glass component (soluble silicic acid compound) and the like, but is preferably a ratio of 20 to 50% by mass. It is desirable that it is contained in. By appropriately allowing the water glass component corresponding to this non-volatile component to be present in the aqueous solution, the water glass component is evenly and uniformly applied to the refractory aggregate when mixed (kneaded) with the refractory aggregate. Can be coated, whereby the desired mold can be advantageously molded according to the present invention. If the concentration of the water glass component in the water glass becomes too low and the total amount of non-volatile components is less than 20% by mass, the heating temperature is raised or the heating time is lengthened for drying the coated sand. Therefore, problems such as energy loss will be caused. Further, if the proportion of the non-volatile content in the water glass becomes too high, it becomes difficult to uniformly cover the surface of the refractory aggregate with the water glass component, which also causes a problem in improving the characteristics of the target mold. From the point of view, it is desirable to prepare water glass in the form of an aqueous solution so that the non-volatile content is 50% by mass or less, and therefore the water content is 50% by mass or more.

By the way, as a thermosetting resin which is one of the water-soluble binders other than the above-mentioned inorganic polymer, a resol type phenol resin, a furan resin, a water-soluble epoxy resin, a water-soluble melamine resin, a water-soluble urea resin, and a water-soluble resin are used. Examples thereof include unsaturated polyester resin and water-soluble epoxy resin. Further, it is also advantageous to add a curing agent such as an acid or an ester to the thermosetting resin to improve its thermosetting characteristics. Among these thermosetting resins, it is preferable to use a resol type phenol resin, and such a phenol resin can be prepared by reacting phenols and formaldehydes in the presence of a reaction catalyst. .. Further, in the present invention, as such a phenol resin, a water-soluble alkaline resole resin is mentioned as a suitable one. By using such an alkaline resole 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.

Further, as the saccharide which is one of the other water-soluble binders, known saccharides such as monosaccharides, oligosaccharides and polysaccharides can be used, and among various monosaccharides, oligosaccharides and polysaccharides, 1 It does not matter whether the species are selected and used alone or in combination of multiple species. Among them, examples of monosaccharides include glucose (dextrose), fructose (fructose), galactose and the like, and examples of oligosaccharides include maltose (malt sugar), sucrose (sucrose), lactose (lactose), cellobiose and the like. Disaccharides can be mentioned. Examples of the polysaccharide include starch sugar, dextrin, zansangum, curdlan, pullulan, cycloamylose, chitin, cellulose, starch and the like. In addition to this, gums of plant mucilage such as gum arabic may be used, and carboxylic acid can also be used as a curing agent for sugars, particularly polysaccharides.

Further, as the synthetic polymer used as a water-soluble binder, polyethylene oxide, poly-α-hydroxyacrylic acid, acrylic acid-based copolymer, acrylic acid ester-based copolymer, methacrylic acid ester-based copolymer, polyacrylamide. , Anionic polyacrylamide, cationized polyacrylamide, polyaminoalkyl methacrylate, acrylamide / acrylic acid copolymer, polyvinyl sulfonic acid, polystyrene sulfonic acid, sulfonated maleic acid polymer, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyvinyl methyl ether , Polyethylene-modified silicone, or modified products thereof. Then, these may be used alone or may be used by selecting a plurality of them.

Furthermore, as salts, those that harden 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, sodium carbonate and carbonate. Examples thereof include carbonates such as potassium, chlorides such as barium chloride, sodium chloride, and potassium chloride. In addition, examples of the protein include gelatin, glue and the like.

The water-soluble binder as described above may be used at a ratio of 0.1 to 2.5 parts by mass in terms of solid content when considering only the non-volatile content with respect to 100 parts by mass of the fire-resistant aggregate. Desirably, among others, a proportion of 0.2 to 2.0 parts by mass is particularly advantageously adopted to form a predetermined coating layer on the surface of the fire resistant aggregate. Here, the measurement of the solid content is carried out as follows. That is, 10 g of the sample was weighed and contained in an aluminum foil dish (length: 90 mm, width: 90 mm, height: 15 mm), placed on a heating plate held at 180 ± 1 ° C., and left for 20 minutes. The sample dish is inverted and left on the heating plate for an additional 20 minutes. Next, the sample dish is taken out from the heating plate, allowed to cool in a desiccator, weighed, and the solid content (mass%) is calculated by the following formula.
Solid content (mass%) = [mass after drying (g) / mass before drying (g)]
× 100

If the amount of the water-soluble binder used is too small, it becomes difficult for a coating layer to be formed on the surface of the refractory aggregate, which causes a problem that the coated sand is difficult to solidify or harden sufficiently. Further, even if the amount of the water-soluble binder used is too large, the water-soluble binder is excessively adhered to the surface of the refractory aggregate, making it difficult to form a uniform coating layer, and the coated sands are mutually coated. There is also a risk of sticking and agglomerating (composite particles), which adversely affects the physical characteristics of the mold and also raises the problem of making it difficult to remove sand from the core after casting the metal.

Then, in the present invention, a dry coated sandwich formed by forming a coating layer on the surface of a fire-resistant aggregate by using the above-mentioned water-soluble binder is targeted. If necessary, such a coating layer may appropriately contain a known additive. In order to include such an additive in the coating layer, a method of pre-blending a predetermined additive in a water-soluble binder and then kneading or mixing it with a refractory aggregate, or separately from the water-soluble binder. , A method is adopted in which a predetermined additive is added to a refractory aggregate and the whole is uniformly kneaded or mixed together with a water-soluble binder.

As one of such additives, solid oxides and salts are advantageously used in the present invention. The inclusion of these solid oxides and salts can advantageously improve the moisture resistance of the coated sand. Among them, as the solid oxide, for example, the use of oxides of elements such as silicon, zinc, magnesium, aluminum, calcium, lead and boron is effective. In particular, among them, it is desirable to use silicon dioxide, zinc oxide, aluminum oxide, and boron oxide. Further, among silicon dioxide, precipitated silicic acid and exothermic silicic acid are preferably used. On the other hand, examples of salts include siliceous salts, silicates, phosphates, borates, tetraborates, carbonates, etc. Among them, zinc carbonate, basic zinc carbonate, potassium metaborate, tetraborate, etc. The use of sodium phosphate and potassium tetraborate is desirable. Then, these solid oxides and salts are generally used in a ratio of about 0.5 to 5% by mass with respect to the non-volatile content in the water-soluble binder.

Further, as other additives, it is also effective to include a coupling agent that strengthens the bond between the refractory aggregate and the water-soluble binder. For example, a silane coupling agent, a zircon coupling agent, and a titanium coupling agent. Etc. can be used. It is also effective to include a lubricant that contributes to improving the fluidity of the coated sand. For example, waxes such as paraffin wax, synthetic polyethylene wax and montanic acid wax; Fatty acid amides; alkylene fatty acid amides such as methylene bisstearic acid amide and ethylene bisstearic acid amide; stearic acid, stearyl alcohol; lead stearate, zinc stearate, calcium stearate, magnesium stearate and other metal stearate salts; It is possible to use acid monoglyceride, stearic stearate, hardened oil and the like. 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, 蛭 葉, fluorine-based mold release agent, silicone-based mold release agent. Agents and the like can also be used. Each of these other additives is contained in a proportion of 5% by mass or less, preferably 3% by mass or less, based on the non-volatile component in the water-soluble binder.

By the way, in the present invention, when producing a dry coated sand prepared in advance, generally, a water-soluble binder as a binder is added to a fire-resistant aggregate together with an additive used as necessary. By kneading or mixing according to a conventional method, and uniformly mixing, the surface of the fire-resistant aggregate is covered with a water-soluble binder, and the water content of such a water-soluble binder is evaporated. A method for obtaining a dry powdered coated sand having fluidity at room temperature will be adopted, but the evaporation of water in the coating layer at that time is rapid before the solidification or hardening of the water-soluble binder progresses. Therefore, in the present invention, within 5 minutes after adding (mixing) the water-soluble binder in the form of an aqueous solution to the fire-resistant aggregate, more preferably 3. Within minutes, it is desirable to remove the water content to obtain a dry powdered coated sand. If the evaporation time is long, the mixing (kneading) cycle is long, the productivity is lowered, and the water-soluble binder is _{exposed to CO 2} in the air for a long time, which may cause problems such as deactivation. Is high. The water content of the dry powdered coated sand thus obtained is generally about 5 to 55% by mass, particularly 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 formed as a coated sand having such a water content adjusted to 20 to 50% by mass.

Further, in the manufacturing process of such a dry coated sand, as one of the effective means for rapidly evaporating the water content in the water-soluble binder, the refractory aggregate is preheated, and the refractory aggregate is preheated. A method is adopted in which a water-soluble binder in the form of an aqueous solution is kneaded or mixed so as to be mixed. By kneading or mixing a water-soluble binder with this preheated refractory aggregate, the moisture in the water-soluble binder evaporates extremely quickly with the heat of such refractory aggregate. Therefore, the water content of the obtained coated sand can be effectively reduced, and a dry powder having room temperature fluidity can be advantageously obtained. The preheating temperature of the refractory aggregate is appropriately selected according to the water content of the water-soluble binder, the blending amount thereof, etc., but is generally about 100 to 160 ° C, preferably 100 to. It is desirable to heat the refractory aggregate to a temperature of about 140 ° C. If this preheating temperature becomes too low, it will not be possible to effectively evaporate the water and it will take time to dry. Therefore, it is desirable to adopt a temperature of 100 ° C. or higher, and the preheating temperature. If the temperature becomes too high, the water-soluble binder component will harden when the obtained coated sand is cooled, and in addition, composite particle formation will proceed. Will occur.

Then, in the present invention, the dry coated sand obtained as described above is used, and after transporting it to the molding site, which is the manufacturing site of the mold, the surfactant and / / are used at the molding site. Alternatively, an aqueous medium containing a polyhydric alcohol is added to moisturize the mixture, and the obtained moisturized coated sand is filled in a molding die to form a desired mold. In the step of adding a surfactant and / or a polyhydric alcohol-containing aqueous medium to the dry coated sand to moisten it, simply, the dry coated sand and a predetermined amount of the aqueous medium are suitable. Since it is sufficient to moisten the coated sand by putting it in a mixer and mixing it, it can be carried out with extremely simple work, and it is extremely easy and easy even at a molding site where the work environment is bad. You can do it. Moreover, by adding the surfactant, the compatibility between the water-soluble binder serving as the coating layer of the coated sand and the water content is enhanced, and the fluidity of the coated sand in a wet state can be advantageously improved. And, due to the improvement of its fluidity, the filling property of the coated sand into the molding die is improved, and even in the molding die having a complicated shape and a long cavity path from the filling port to the completion of filling, the mold is defective. It is possible to fill without. Further, when the polyhydric alcohol is added, the strength of the mold can be advantageously improved and the moisturizing effect is obtained, so that the moisturizing property of the coated sand in a wet state is improved and the pot life is extended. There is an advantage that it can be done.

Furthermore, in order to moisten such a dry coated sand, it is only necessary to add a surfactant and / or a polyhydric alcohol-containing aqueous medium, and a viscous water-soluble binder is kneaded into the fire-resistant aggregate. Since it is not a squeeze, the workability is extremely good, and the moistened coated sand does not easily adhere to the mixer, mold, etc., so that the device is not easily soiled. At the molding site, since the water-soluble binder, especially water glass, is not handled, there is an advantage that the worker is not likely to be damaged by chemicals.

Here, the surfactant and / or polyhydric alcohol-containing aqueous medium used in the present invention dissolves by adding at least one of the surfactant and the polyhydric alcohol to water at a predetermined ratio. Or it is prepared by dispersing. In addition, various additives pointed out in this specification and other additives known to those skilled in the art will be added and contained in this aqueous medium, if necessary.

Then, when adding such an aqueous medium to the dry coated sand, the amount of the surfactant is 0.1 to 20. With respect to 100 parts by mass of the solid content of the water-soluble binder in the coated sand. It is desirable to use an aqueous medium so as to have 0 parts by mass, and it is particularly preferable to use an aqueous medium so as to have 0.5 to 15.0 parts by mass, particularly 0.75 to 12.5 parts by mass. .. As the surfactant, any of cationic, anionic, amphoteric, nonionic, silicone-based and fluorine-based can be used.

Specific examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts. Examples of anionic surfactants include fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acylglutamate, alkyl ether carboxylate, and acyl. Peptide, alkyl sulfonate, alkylbenzene sulfonate, alkylnaphthalene sulfonate, dialkyl sulfosulfonic acid ester salt, alkyl sulfoacetate, α-olefin sulfonate, N-acylmethyl taurine, sulfated oil, higher alcohol Sulfate ester salt, secondary higher alcohol sulfate ester salt, alkyl ether sulfate salt, secondary higher alcohol ethoxysulfate, polyoxyethylene alkylphenyl ether sulfate salt, monoglyculfate, fatty acid alkylolamide sulfate ester salt, alkyl ether phosphorus Examples thereof include acid ester salts and alkyl phosphate ester salts. Further, examples of the amphoteric surfactant include carboxybetaine type, sulfobetaine type, aminocarboxylic acid salt, imidazolinium betaine and the like. In addition, examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkyl phenyl ether (for example, Emulgen 911), polyoxyethylene sterol ether, and polyoxyethylene lanolin derivative. , Polyoxyethylene polyoxypropylene alkyl ether (eg, Newpol PE-62), polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil, hardened castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, Polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, sucrose fatty acid ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, alkylamine oxide, acetylene glycol, Examples include acetylene alcohol. Further, among various surfactants, those having a siloxane structure as a non-polar moiety are referred to as silicone-based surfactants, and those having a perfluoroalkyl group are referred to as fluorine-based surfactants. Examples of the silicone-based surfactant include polyester-modified silicone, acrylic-terminated polyester-modified silicone, polyether-modified silicone, acrylic-terminated polyether-modified silicone, polyglycerin-modified silicone, and aminopropyl-modified silicone. Examples of the fluorine-based surfactant include perfluoroalkyl sulphonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyltrimethylammonium salt, perfluoroalkylethylene oxide adduct, and perfluoroalkyl group. Examples include contained oligomers. Then, these surfactants are used alone or in combination of two or more kinds.

Further, the polyhydric alcohol used in place of or in combination with the above-mentioned surfactant is generally 0.1 to 20.0 mass by mass with respect to 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 has a proportion of such polyhydric alcohol, preferably 0.5 to 15.0 parts by mass, more preferably 0.75 to 12.5 parts by mass. , Will be 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, and 1,2-pentane. Glycol, 1,5-pentanediol, 1,2-hexanediol, 2-ethyl-1,3-hexanediol, 1,6-hexanediol, 1,2-heptandiol, 1,2-octanediol, 1, Examples thereof include 2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, trimethylolethane, and trimethylolpropane. And these can be used alone or in admixture of two or more.

The aqueous medium containing the surfactant and / or the polyhydric alcohol prepared as described above can also contain various known additives, if necessary. For example, an acid or an ester may be contained as a curing agent. Among them, the acid is preferably sulfuric acid, hydrochloric acid, carbonic acid or sulfonic acid, and the ester is a lactone such as γ-butyrolactone or ε-caprolactone. 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 monovalent or multivalent. Further, as a curing accelerator, a metal salt, a metal powder, or the like may be contained. Therefore, the metal salt is preferably a metal salt such as calcium, magnesium, aluminum or iron, and the metal powder is preferably a metal powder such as calcium, magnesium, zinc, aluminum or silicon. Furthermore, alcohols such as methanol, which is an organic solvent, and drying accelerators such as ketones such as acetone and diacetone alcohol, and PROXEL GXL [1,2-benzoisothiazole-3 (2H) -on, manufactured by Lonza Japan Co., Ltd. ], PROXEL IB (polyhexamethylene biguanidine) and other preservatives, and silane coupling agents can be added in small amounts.

In addition, a second water-soluble binder can be added as a further additive for adjusting the mold strength. The second water-soluble binder is appropriately selected from the water-soluble binders exemplified above, and is the same as or different from the water-soluble binder coating the coated sand. However, there is no problem. By adding such a second water-soluble binder at the time of molding, the second water-soluble binder may be further added when it is desired to increase the strength of the mold depending on the shape and size of the mold to be manufactured. Therefore, the strength can be improved. Since the amount of the second water-soluble binder added is for adjustment, the solid content of the second water-soluble binder added is smaller than the solid content of the water-soluble binder in the coated sand. Is desirable.

Further, according to the present invention, when an aqueous medium containing a surfactant and / or a polyhydric alcohol is added to the dry coated sand to moisten it, spherical particles are added as a further additive. That is also effective. By adding such spherical particles, it is possible to advantageously contribute to the improvement of the filling property of the coated sand at the time of molding. Such spherical particles may be added in a state of being mixed with the surfactant and / or the polyhydric alcohol-containing aqueous medium, and may be added separately from the surfactant and / or the polyhydric alcohol-containing aqueous medium. It is also possible to do. The amount of the spherical particles added is about 0.1 to 20.0 parts by mass, preferably 0.5 to 15.0 parts by mass, based on 100 parts by mass of the solid content of the water-soluble binder in the coated sand. More preferably, it is 0.75 to 12.5 parts by mass.

As such spherical particles, those having a sphericity of 0.5 or more are usually desirable, and among them, those having a sphericity of 0.7 or more, more preferably 0.9 or more are preferably used. It will be. Here, the sphericity is the average value of the aspect ratios (minor axis / major axis ratios) obtained from the projected shapes of 10 single particles randomly selected in the scanning electron microscope observation. Means. The average particle size of such spherical particles is about 0.1 to 25.0 μm, preferably about 1.0 to 20.0 μm, and the material of the spherical particles is not particularly limited. Advantageously, spherical particles such as amorphous silica, alumina, and titanium oxide are preferably used.

By the way, in the wet state of the dry coated sand described above, a predetermined amount of a surfactant and / or a polyhydric alcohol-containing aqueous medium is added to the dry coated sand at the molding site of the mold. , By mixing with a normal mixer, the desired moistened coated sand will be formed, but the amount of water supplied by the surfactant and / or polyhydric alcohol-containing aqueous medium used therein will be , It is to be appropriately determined according to the type and amount of the water glass component constituting the coated sand, and generally, in order to moisten the dry coated sand, with respect to 100 parts by mass of the coated sand. , 0.5 to 5 parts by mass, preferably 0.75 to 4 parts by mass, and more preferably 1 to 3 parts by mass. The amount of the surfactant and / or polyhydric alcohol-containing aqueous medium is determined by the amount of water, surfactant, or polyhydric alcohol added, but is generally 100 parts by mass of the coated sand. On the other hand, it is appropriately determined at a ratio of 0.5 to 6 parts by mass, preferably at a ratio of 0.75 to 4 parts by mass, and more preferably at a ratio of 1 to 3.5 parts by mass. .. If the amount of the surfactant and / or the aqueous medium containing a polyhydric alcohol added is too small, it is not possible to sufficiently moisten the dry coated sand, and therefore, mutual moistening between the coated sands cannot be realized. As a result of the weakening of the adhesion of the coated sand and the deterioration of the fluidity of the coated sand, the filling property into the molding die is deteriorated, and as a result, the strength of the obtained mold is lowered. On the other hand, if the amount of the surfactant and / or the polyhydric alcohol-containing aqueous medium added is too large, the filling operation into the molding die becomes difficult, and in addition, the drying operation after filling into the molding die takes time. In short, it causes problems such as long molding time.

Then, in the present invention, the wet state of the dry coated sand obtained as described above is used, and the wet product is filled in a predetermined molding die, specifically, a molding cavity of the molding die. Then, by drying the moistened coated sand, a mold having a desired shape is formed. At that time, the moistened coated sand used directly uses a water-soluble binder. Compared to the wet coated sand obtained by kneading with fire-resistant aggregate, the fluidity is better, and the adhesion and adhesive strength between the sands are reduced, so the filling property is effectively improved. Further, since the adhesion to the molding die can be effectively reduced, the stain on the molding die can be advantageously suppressed, and the mold releasability from the molding die can be advantageously improved. be. A blow filling method using a blow head is preferably adopted for filling the molding mold of such a moistened coated sand, and the blow pressure at that time is about 0.2 to 0.6 MPa. It is preferably about 0.3 to 0.5 MPa.

Further, in this way, the moistened coated sand filled in the molding die is dried and solidified or hardened to dry the moistened coated sand when molding the target mold. It is desirable to heat the molding die in order to take advantage of it, which is recommended in the present invention. By using this heated molding die, the drying of the filled moistened coated sand can be effectively advanced, so that the molding time can be advantageously shortened. As the heating temperature of such a molding mold, a temperature in the range of 40 to 250 ° C., preferably 70 to 200 ° C., and more preferably 100 to 175 ° C. is generally adopted. If the heating temperature is less than 40 ° C, it is difficult to sufficiently exert the drying promoting effect by heating, and there is a problem that the molding time becomes long. If the heating temperature is higher than 250 ° C, the mold is moistened. The solidification or curing of the coated sand becomes too fast, and the filling property deteriorates. In addition, the moistened coated sand becomes too dry and loses its adhesiveness, and the adhesive effect becomes low. Problems such as a decrease in strength will also be caused.

Then, in order to accelerate the drying of the moistened coated sand filled in the mold, it is also effective to directly heat the filled moistened coated sand with microwaves. In particular, when the mold molding mold is a resin mold, it is preferably adopted. Further, by aerating heated air or dry air into the molding mold filled with the moistened coated sand and passing it through the packed layer of the moistened coated sand, drying is promoted and the molding is filled more quickly. It is also effective to solidify or harden the moistened coated sand. In addition, it is also one of the effective drying means to dry the inside of the molding mold under reduced pressure by sucking the molding mold filled with the moistened coated sand under reduced pressure, and in particular, it is affected by heat such as a resin mold. It is being used advantageously in molds made of easily acceptable materials.

Further, in the present invention, as described above, the moisture of the surfactant and / or the polyhydric alcohol-containing aqueous medium used for the moistening is removed from the moistened coated sand filled in the molding die. By removing the mold, the target mold is formed. At that time, the water glass constituting the coating layer on the surface of the coated sand is usually not added with any additives. It is solidified by evaporation to dryness of water, and if an oxide, salt, or the like is added as a curing agent, it will be cured. Then, for the curing of such water glass, it is also effective to allow carbon dioxide gas or organic ester gas to be aerated in the molding mold filled with the moistened coated sand, whereby, as in the conventional case, It is possible to rapidly cure the water glass and advantageously increase the molding speed. Examples of the organic ester gas include methyl formate, ethyl formate, propyl formate, γ-butyrolactone, γ-propion lactone, ethylene glycol diacetate, diethylene glycol diacetate, glycerin diacetate, triacetin, and propylene carbonate. It is atomized and used.

In addition, according to the present invention, as a method of moistening a dry coated sand and molding it by a predetermined molding mold, it is possible to manufacture a mold by adopting various known molding methods. Further, the present invention can be carried out in a mode in which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art, and such a mode of implementation does not deviate from the gist of the present invention. To the extent, it should be understood that all of them belong to the scope of the present invention.

Hereinafter, the present invention will be clarified more concretely by using some examples, but the present invention shall not be construed in any way by the description of such examples. Should be understood. In the following examples and comparative examples, "%" and "part" are all shown on a mass basis unless otherwise specified. Further, the water content, filling property, filling fluidity, and strength of the coated sand (CS) obtained in Examples and Comparative Examples were evaluated as follows.

-Measurement of water content relative to solid content of water-soluble binder-
The method is not particularly limited as long as it can measure the amount of water in CS, and an effective measuring method can be selected depending on the type of binder. An example of the measurement method is shown below.

(When the water-soluble binder is water glass)
10 g of each CS is weighed and stored in a crucible that has been air-baked and weighed, and the amount of water content (W1) in the CS is determined by using the mass reduction amount (%) after heating at 900 ° C. for 1 hour. It is calculated from the following formula (1). The weighing is measured to the fourth decimal place. Next, the binder solid content (B1) with respect to CS is calculated using the following formula (2), and then the water content (W2) with respect to the binder solid content is calculated from the water content in CS using the following formula (3). ) Is used for calculation.
W1 = [(M1-M2) / M3] × 100 ... (1)
[W1: Moisture content in CS (%), M1: Total quality of crucible and CS before firing (g), M2: Total mass of crucible and CS after firing (g), M3: CS before firing Mass (g)]
B1 = [B2 / (100 + B2)] × (100-W1) ・ ・ ・ (2)
[B1: Solid content of binder relative to CS (%), B2: Solid content of binder added to 100 parts of sand (parts), W1: Moisture content in CS (%)]
W2 = (W1 / B1) x 100 ... (3)
[W2: Moisture content (%) with respect to the solid content of the binder, W1: Water content (%) in CS, B1: Solid content of the binder with respect to CS (%)]

(When the water-soluble binder is a water-soluble resole resin)
Weigh 2.0 g of each CS and contain 100 ml of Aquamicron ML (manufactured by Mitsubishi Chemical Corporation), which is a dehydrating solvent, in a flask of Karl Fischer Moisture Analyzer (manufactured by Hiranuma Sangyo Co., Ltd .: AQV-7 HIRANUMA AQUACOUNTER) [in advance. , Karl Fischer titer (Sigma-Aldrich Laborchemikalien Gmbh: Hydranal Composite 5) is added dropwise to keep the water content to 0], and then the mixture is stirred with a magnetic stirrer for several minutes. Hydranal Composite 5 was added dropwise to quantify the amount of water (W1) in CS. Then, from the water content (W1) in CS, the water content (W2) with respect to the solid content of the binder was calculated using the above formulas (2) and (3).

-Measurement of filling property and evaluation of filling fluidity-
The CS of each example or each comparative example is divided into one mold half body 5 having a mold split surface as shown in FIG. 1 and the other mold half body (5) having a mold split surface symmetrical thereto. ), The formed mold is filled from the filling port 6 with a blow pressure of 0.3 MPa, and the mold is molded at a molding temperature of 150 ° C. and a molding time of 180 seconds, and the mass of the obtained mold is obtained. (G) is measured. Next, in the molded mold, the filling state of CS for the flow paths 1 to 4 in the cavity is visually evaluated. As for the filling state of each flow path, it is determined that ◯: is filled, Δ: is filled, but there is a slight defect, and ×: the flow path portion cannot be filled and the flow path portion is missing. It should be noted that those in which the flow paths 2 to 4 are filled and the flow path 1 is filled with Δ or more are accepted.

-Measurement of bending strength-
For a test piece having a size of width: 1.0 cm × height: 1.0 cm × length: 6.0 cm obtained by using each CS, the breaking load thereof was measured by a measuring instrument (manufactured by Takachiho Seiki Co., Ltd .: Measure using a digital casting sand strength tester). Then, using the measured breaking load, the bending strength is calculated by the following formula (4).
Anti-folding strength (N / cm ² ) = 1.5 x 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)]

− Production example of dry CS 1-
As a fire-resistant aggregate, Lunamos # 80 (trade name: manufactured by Kao Quaker Co., Ltd.), which is a commercially available artificial sand for casting, is prepared, and as a water glass used as a binder (water-soluble binder), a commercially available product: No. 2 sodium silicate (trade name: manufactured by Fuji Chemical Co., Ltd., SiO ₂ / Na ₂ O molar ratio: 2.5, solid component: 41.3%) was prepared. Then, after heating the above-mentioned Lunamos # 80 to a temperature of about 120 ° C., it is put into a Shinagawa type universal stirrer (5DM-r type) (manufactured by Dalton Corporation), and further, the water glass is put into 100 of Lunamos # 80. Add 1.21 parts (solid component: 0.50 parts) to the parts and knead for 3 minutes to evaporate the water, while stirring and mixing until the sand granules collapse and then take out. As a result, a dry coated sand: CS1 having free fluidity at room temperature was obtained. The water content of CS1 after such kneading was measured and found to be 0.2% (/ CS).

− Production example of dry CS 2-
Commercially available product: No. 1 sodium silicate (trade name: manufactured by Fuji Chemical Co., Ltd., SiO ₂ / Na ₂ O molar ratio: 2.1, solid component: 48.5%) is used as the binder water glass. According to the same procedure as in Production Example 1 above, except that the amount of water glass added was 1.03 parts (0.50 parts of solid component) with respect to 100 parts of Lunamos # 80. , A dry CS2 was obtained. Then, when the water content of CS2 after the kneading was measured, it was 0.2% (/ CS).

− Production example of dry CS 3-
As a water glass as a binder, a commercially available product: No. 3 sodium silicate (trade name: manufactured by Fuji Chemical Co., Ltd., SiO ₂ / Na ₂ O molar ratio: 3.2, solid component: 38%) was prepared. The dry state was carried out according to the same procedure as in Production Example 1 above, except that the amount of this water glass added was 1.32 parts (0.50 parts of solid component) with respect to 100 parts of Lunamos # 80. CS3 was obtained. Then, when the water content of CS3 after the kneading was measured, it was 0.2% (/ CS).

− Production example of dry CS 4-
As a water-soluble resole as a binder (water-soluble binder), a commercial 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 is put into a Shinagawa type universal stirrer (5DM-r type) (manufactured by Dalton Corporation), and further, a water-soluble resin is added to 100 of Lunamos # 80. The mixture was added at a ratio of 1.33 parts (resin component 0.6) to the parts, and kneaded for 60 seconds to evaporate the water content, while stirring and mixing until the sand grain lumps collapsed. Then, it was taken out from a stirrer to obtain a dry CS4 having free fluidity at room temperature. Moreover, when the water content of CS4 after the obtained kneading was measured, it was 0.2% (/ CS).

− Production example of wet CS 1-
As a refractory aggregate, Lunamos # 80 (trade name: manufactured by Kao Quaker Co., Ltd.), which is a commercially available artificial sand for casting, is prepared, and as a water glass as a binder, a commercially available product: No. 2 sodium silicate (commodity). Name: Made by Fuji Chemical Co., Ltd.) was prepared. Next, the above-mentioned Lunamos # 80 at room temperature was put into a Shinagawa type universal stirrer (5DM-r type) (manufactured by Dalton Corporation), and further, the water glass was added to 100 parts of Lunamos # 80. 21 parts (0.50 parts of solid component) were added, and 0.46 parts of water was added and kneaded for 3 minutes to obtain wet CS5. When the water content of CS5 after such kneading was measured, it was 1.15% (/ CS), and when the dynamic angle of repose was measured, it was in a wet state and did not have room temperature fluidity. The dynamic angle of repose could not be measured.

-Molding example-
(Example 1)
As an anionic surfactant, use a commercially available product: Orphine PD-301 (trade name: manufactured by Nisshin Kagaku Kogyo Co., Ltd.), add 0.02 part of it to 2 parts of water, mix and stir. To obtain a surfactant-containing aqueous solution as an aqueous medium. Then, 100 parts of CS1 obtained in Production Example 1 in the dry state was put into a Shinagawa universal stirrer (5DM-r type), and a surfactant-containing aqueous solution as the aqueous medium was further added. (Therefore, the surfactant is 4.0 parts to 100 parts of the solid content of the water glass in CS1), and the mixture was stirred for 1 minute. The wet CS thus obtained is placed in a blow tank and blown into a molding die composed of a pair of the mold halves 5 heated to 150 ° C. at a gauge pressure of 0.3 MPa to fill the mold. rice field. Then, after holding for 180 seconds, it was removed from the molding die to obtain a mold as a test piece.

(Example 2)
By adding 0.05 part of the anionic surfactant (10 parts to 100 parts of the solid content of water glass which is a water-soluble binder) to 2 parts of water, mixing and stirring. A template (test piece) was prepared according to the same procedure as in Example 1 except that the medium was used as an aqueous medium.

(Example 3)
0.06 part of the anionic surfactant (12 parts to 100 parts of solid content of water glass) was added to 2 parts of water, mixed and stirred to prepare an aqueous medium. Except for this, a mold (test piece) was prepared according to the same procedure as in Example 1.

(Example 4)
A mold (test piece) was prepared according to the same procedure as in Example 2 except that the dry state CS1 was changed to the dry state CS2.

(Example 5)
A mold (test piece) was prepared according to the same procedure as in Example 2 except that the dry state CS1 was changed to the dry state CS3.

(Example 6)
As a silicone-based surfactant, a commercially available product: KF643 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) is prepared, and 0.005 parts thereof (1 part ratio to 100 parts of solid content of water glass). A mold (test piece) was prepared according to the same procedure as in Example 1 except that the aqueous medium was prepared by adding the mixture to two parts of water, mixing and stirring.

(Example 7)
As a silicone-based surfactant, a commercially available product: KF640 (trade name: manufactured by Shin-Etsu Chemical Co., Ltd.) is prepared, and 0.005 parts thereof (1 part ratio to 100 parts of solid content of water glass). A mold (test piece) was prepared according to the same procedure as in Example 1 except that the aqueous medium was prepared by adding the mixture to two parts of water, mixing and stirring.

(Example 8)
A template (test piece) was prepared according to the same procedure as in Example 2 except that a commercially available product: Liporan LB-440 (trade name: manufactured by Lion Corporation) was used as the anionic surfactant.

(Example 9)
A template (test piece) was prepared 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 template (test piece) was prepared 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)
As an anionic surfactant, a commercially available product: Orphine PD-301 (trade name: manufactured by Nisshin Kagaku Kogyo Co., Ltd.) is used, and 0.02 part (4 parts to 100 parts of solid content of water glass) is used. As a polyhydric alcohol, 0.04 part of glycerin (8 parts to 100 parts of solid content of water glass) is added to 2 parts of water, and mixed and stirred. A template (test piece) was prepared according to the same procedure as in Example 1 except that the medium was used as an aqueous medium.

(Example 12)
As an anionic surfactant, a commercially available product: Orphine PD-301 (trade name: manufactured by Nisshin Kagaku Kogyo Co., Ltd.) is used, and 0.05 parts thereof (10 parts to 100 parts of solid content of water glass) are used. As a polyhydric alcohol, 0.04 part of glycerin (8 parts to 100 parts of solid content of water glass) is added to 2 parts of water, and mixed and stirred. A template (test piece) was prepared according to the same procedure as in Example 1 except that the medium was used as an aqueous medium.

(Example 13)
As a surfactant, a commercially available product: Orphine PD-301 (trade name: manufactured by Nisshin Chemical Industry Co., Ltd.) is used, and 0.05 part thereof (10 parts ratio to 100 parts of solid content of water glass). To an aqueous medium obtained by adding 2 parts of water, mixing and stirring, 0.05 part (trade name: manufactured by Nippon Steel & Sumikin Materials Co., Ltd.) of HS311 (trade name: manufactured by Nippon Steel & Sumitomo Metal Materials Co., Ltd.) of spherical particles (of water glass). A template (test piece) was prepared according to the same procedure as in Example 1 except that 10 parts were added to 100 parts of the solid content. The aspect ratio of HS311 was measured and found to be 0.91.

(Example 14)
A mold (test piece) was prepared according to the same procedure as in Example 2 except that the dry state CS1 was changed to the dry state CS4.

(Example 15)
Glycerin is used as the polyhydric alcohol, and 0.04 part thereof (8 parts is added to 100 parts of solid content of water glass) is added to 2 parts of water, and the mixture is mixed and stirred. A mold (test piece) was prepared according to the same procedure as in Example 1 except that the medium was used as an aqueous medium.

(Example 16)
As the polyhydric alcohol, polyethylene glycol commercially available product: PEG400 (product name: Daiichi Kogyo Seiyaku Co., Ltd.) is used, and 0.04 part thereof (8 parts ratio to 100 parts of solid content of water glass) is 2 parts. A mold (test piece) was prepared according to the same procedure as in Example 1 except that the aqueous medium was prepared by adding to the water of the portion, mixing and stirring.

(Example 17)
Obtained by using glycerin as a polyhydric alcohol, adding 0.04 part thereof (8 parts to 100 parts of solid content of water glass) to 2 parts of water, mixing and stirring. To the aqueous medium obtained, 0.05 part of HS311 (trade name: manufactured by Nippon Steel & Sumikin Materials Co., Ltd.) as spherical particles (10 parts to 100 parts of solid content of water glass) was added. A mold (test piece) was prepared according to the same procedure as in Example 1 except that it was used.

(Example 18)
A mold (test piece) was prepared according to the same procedure as in Example 15 except that the dry state CS1 was changed to the dry state CS4.

(Comparative Example 1)
A mold (test piece) was prepared according to the same procedure as in Example 1 except that ordinary tap water to which no surfactant or polyhydric alcohol was added was used as the aqueous medium.

(Comparative Example 2)
Wet CS5 was placed in a blow tank and blown into a molding mold heated to 150 ° C. at a gauge pressure of 0.3 MPa to fill the mold. Then, after holding it in the mold for 180 seconds, it was taken out from the molding mold to obtain a mold (test piece).

(Comparative Example 3)
A template (test piece) was prepared according to the same procedure as in Example 14 except that ordinary tap water to which no surfactant or polyhydric alcohol was added was used as the aqueous medium.

For each of the molds (test pieces) obtained in Examples 1 to 18 and Comparative Examples 1 to 3 above, the filling property is measured and the filling fluidity is evaluated according to the above-mentioned test method, and the strength is measured. The results were shown in Tables 1 to 3 below.

As is clear from the results of Tables 1 to 3, in Examples 1 to 18, the template obtained from CS moistened with a surfactant and / or a polyhydric alcohol-containing aqueous medium according to the present invention is used. , It is recognized that all of them show good filling property and filling fluidity of the coated sand.

On the other hand, from the ones in which the dry CS is moistened using only water and the one in which the wet CS is directly formed using water glass according to Comparative Examples 1 to 3, molding is performed. It is recognized that the filling property and filling fluidity of CS in the molding die are not sufficient in the formed mold.

Further, it is recognized that the molds obtained in Examples 1 to 18 are effectively improved in strength as compared with the Comparative Example in which CS moistened by kneading only water is used.

1 to 4 Flow path 5 Mold half body 6 Filling port

Claims (13)

A dry coated sand having a water content of 5 to 55% by mass of the solid content of the water-soluble binder, which is obtained by coating the surface of the fire-resistant aggregate with a water-soluble binder, is prepared, and the dry-state coated sand is prepared. An aqueous medium containing a surfactant and / or a polyhydric alcohol is added to the sand to moisten it, and then the obtained moistened coated sand is filled in a molding die to form a molding. A method for manufacturing a mold, which is characterized in that. The method for producing a mold according to claim 1, wherein the aqueous medium is added to the coated sand at a ratio of 0.5 to 6 parts by mass with respect to 100 parts by mass of the coated sand. .. The aqueous medium is added so 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 the coated sand. The method for producing a mold according to claim 1 or 2. The aqueous medium is added so that the polyhydric alcohol has 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 producing a mold according to any one of claims 1 to 3. The method for producing a mold according to any one of claims 1 to 4, wherein spherical particles are further added when the dry coated sand is moistened. The mold according to claim 5, wherein the amount of the spherical particles added 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. Production method. The method for producing a mold according to any one of claims 1 to 6, wherein a second water-soluble binder is further added when the dry coated sand is moistened. A claim characterized in that, after the dry coated sandwich is transported from the manufacturing site to the molding site, the aqueous medium is added to the dry coated sandwich to form the wet coated sandwich. The method for producing a mold according to any one of items 1 to 7. Claims 1 to 8, wherein as the water-soluble binder, one or two or more of thermosetting resins, sugars, proteins, synthetic polymers, salts and inorganic polymers are selected and used. The method for producing a mold according to any one item. The method for producing a mold according to claim 9, wherein the inorganic polymer is water glass. The method for producing a mold according to any one of claims 1 to 10, wherein heated air or dry air is aerated in a molding mold filled with the moistened coated sand. The method for producing a mold according to any one of claims 1 to 11, wherein carbon dioxide gas or organic ester gas is aerated in a molding mold filled with the moistened coated sand. The method for producing a mold according to any one of claims 1 to 12, wherein the molding mold is heated to a temperature of 40 ° C. to 250 ° C.

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