JP6528167B2 - Caking material for mold, caking agent coated refractory and method for manufacturing the same, method for manufacturing mold, casting method - Google Patents

Description

  The present invention relates to a caking material for a mold, a caking agent coated refractory using the caking material for the mold and a method for producing the same, a method for producing a mold using the caking agent coated refractory, and the mold Relates to the casting method.

  When casting a molten metal in a mold, the molten metal, which is a high-temperature molten metal, comes into contact with the surface of the mold, so that the so-called seizing occurs that the mold sand is baked and adheres to the surface of the casting obtained by casting. There is a problem of Therefore, conventionally, in order to protect the mold from the high temperature of the molten metal and to prevent the occurrence of the seizure, it is carried out that a mold-forming agent formed by containing graphite, zircon, aluminum oxide or the like is applied to the surface of the mold. (See Patent Documents 1 to 4 and the like).

Japanese Patent Publication No. 58-28015 Japanese Patent Publication No. 58-19376 Japanese Patent Publication No. 58-47251 Japanese Patent Publication No. 58-47252

  However, the mold-coating agent is used by dispersing it in water or dispersing it in a solvent such as alcohol, and it is necessary to carry out complicated work such as dispersion work, coating on a mold and drying. was there. In addition, there is also a problem that the work environment may be deteriorated, such as generation of an odor due to volatilization of alcohol.

  The present invention has been made in view of the above-described points, and it is an object of the present invention to enable casting without the need of using a mold wash.

  The present invention has been made based on the finding that silicon carbide has poor wettability with a molten metal (molten metal), and the caking material for a mold according to the present invention comprises a binder and silicon carbide. It is characterized in that it contains

  When the refractory aggregate is bonded by the caking agent of the caking material for the mold to bond the refractory aggregate to produce the mold, silicon carbide contained in the caking material for the mold is present on the surface of the mold, It is possible to prevent the occurrence of seizure at the time of casting due to silicon carbide having poor wettability with the molten metal, and it becomes possible to carry out casting without the need to use a coating agent.

  The binder coated refractory according to the present invention is characterized in that the surface of the refractory aggregate is coated with a binder layer composed of a caking material for a mold containing a binder and silicon carbide. It is a thing.

  When forming a caking agent coated refractory coated with a caking agent layer containing a caking agent and silicon carbide to produce a mold, silicon carbide contained in the caking agent layer is formed on the surface of the mold It is possible to prevent seizing during casting due to silicon carbide having poor wettability with molten metal and enabling casting without the need to use a coating agent.

Examples of the binder, Ru water-soluble inorganic compound is used.

The water-soluble inorganic compound exerts a caking effect by the supply of water and solidifies by drying to be bonded to the fireproof aggregate, whereby the mold can be produced, and the water-soluble inorganic compound is cast. Even if the high temperature of the molten metal acts, it hardly generates harmful substances or offensive odors and does not deteriorate the working environment, and the water-soluble inorganic compound is easily dissolved in water to obtain a mold having good disintegration property after casting It can be done.

  In the method for producing a binder coated refractory according to the present invention, a binder is mixed with a binder and a powder of silicon carbide, and the binder is mixed with the binder to form a binder on the surface of the refractory aggregate. It is characterized in that a caking agent layer comprising a caking material for a mold containing silicon carbide is coated.

  As described above, when the binder and the silicon carbide powder are mixed and mixed with the refractory aggregate, the ratio of the binder and the silicon carbide powder is adjusted to be mixed with the refractory aggregate. It is easy to produce a binder-coated refractor which can be adapted to the required performance.

  Further, in the method for producing a binder coated refractory according to the present invention, the binder and the powder of silicon carbide are mixed, and the mixture is mixed with the refractory aggregate and mixed to form the surface of the refractory aggregate. It is characterized by coating the caking agent layer which consists of caking material for molds containing a caking agent and silicon carbide.

  Thus, if the binder and the silicon carbide powder are mixed in advance, the binder and the silicon carbide powder can be uniformly dispersed, and by mixing this with the refractory aggregate, A binder layer can be formed on the surface of the refractory aggregate in a state where the silicon carbide powder is uniformly dispersed.

  In the method for producing a binder coated refractory according to the present invention, the refractory aggregate and the powder of silicon carbide are mixed, and then the binder is blended with the mixture to mix, thereby forming the surface of the refractory aggregate. It is characterized by coating the caking agent layer which consists of caking material for molds containing a caking agent and silicon carbide.

  Thus, if the refractory aggregate and the silicon carbide powder are mixed beforehand, the silicon carbide powder can be uniformly dispersed in the refractory aggregate, and the silicon carbide powder is uniformly dispersed. A binder layer can be formed on the surface of the fireproof aggregate.

  Further, in the method for producing a binder coated refractory according to the present invention, after mixing the refractory aggregate and the binder, the powder of silicon carbide is mixed and mixed with the mixture to form the surface of the refractory aggregate. It is characterized by coating the caking agent layer which consists of caking material for molds containing a caking agent and silicon carbide.

  Thus, if the fireproof aggregate and the caking additive are mixed in advance, the caking additive can be uniformly dispersed in the fireproof aggregate, and the fireproof aggregate is in a state where the caking additive is uniformly attached. The binder layer can be formed on the surface of

Further, in the method for producing a mold according to the present invention, the caking agent-coated refractory described above using a water-soluble inorganic compound as a caking agent is filled in a forming die, and water is supplied to the inside of the forming die. It is characterized in that the binder in the layer is made tacky, and then the inside of the mold is dried to solidify the binder.

When a caking agent coated refractor using a water soluble inorganic compound as a caking agent is filled in a molding die and water is supplied, the water soluble inorganic compound of the caking agent absorbs water, becomes tacky, and fire resistance An aggregate can be bonded by the adhesive force of a water-soluble inorganic compound , and then by drying and solidifying it, a mold in which a refractory aggregate is bonded with a solidified water-soluble inorganic compound can be obtained It is.

  Further, in the method for producing a mold according to the present invention, the caking agent coated refractory described above is filled in a forming die, and steam is allowed to pass through the forming die to solidify or harden the caking agent, thereby making the fireproofing with caking agent. It is characterized in that aggregate is joined.

  When steam is passed through a mold filled with a binder-coated refractory, the binder-coated refractory can be efficiently heated by the action of high latent heat and sensible heat of the steam, and the binder is solidified quickly. It can be cured and can produce a mold with high productivity in a short time.

  Superheated steam can be used as the above-mentioned steam.

  Superheated steam is high-temperature dry steam, which has high heating efficiency, less generation of excess steam in the mold, and accelerates the temperature rise of the binder coated refractories in the mold for production. It is possible to further enhance the sex.

  After passing steam through the mold, a drying gas can be passed through the mold.

  It is possible to vaporize the condensed water produced by passing steam through the mold with a drying gas and to dry the molded mold in the mold.

  Further, the casting method according to the present invention is characterized in that the mold manufactured as described above is used without applying a mold wash, and the molten metal is poured into the mold for casting.

  As described above, silicon carbide contained in the mold caking material is present on the surface of the mold, and it is possible to prevent occurrence of seizure during casting due to silicon carbide having poor wettability with the molten metal. It is possible to carry out casting without the need to use a mold wash. Therefore, as in the case of using a mold wash, the troublesome work of dispersion of the mold wash, application to the mold, drying of the mold, etc. becomes unnecessary and problems of working environment such as generation of odor due to volatilization of alcohol It will be gone.

  According to the present invention, the silicon carbide contained in the caking material for molds can prevent the occurrence of seizure during casting and enables casting without the need for using a mold wash. It is.

An example of a manufacturing method of a mold concerning the present invention is shown, and (a) (b) (c) is a sectional view in each process, respectively. It is a perspective view which shows the mold used for a pouring test.

  Hereinafter, embodiments of the present invention will be described.

  Silicon carbide (SiC) is a covalent compound in which carbon and silicon are bonded at 1: 1, and has conventionally been used for polishing / abrasives, refractory materials, heating elements and the like. And when the present inventors measured the contact angle of the molten metal with respect to the surface of silicon carbide, they found out the phenomenon that silicon carbide had poor wettability with the molten metal.

  The present invention utilizes this phenomenon that silicon carbide is poorly wetted with the molten metal, and the caking material for the mold used in the present invention is a caking agent for the mold and the molten metal as described above. Is formed by containing silicon carbide having poor wettability.

The binder contained in the foundry binder, a thermosetting resin, saccharide, there is a water-soluble inorganic compounds, the present invention Ru with those selected from water-soluble inorganic compound.

  Examples of the thermosetting resin include phenol resin such as resol type, novolak type and benzylic ether type, epoxy resin, furan resin, isocyanate compound, amine polyol resin, polyether polyol resin and the like. And curing agents such as isocyanate compounds, organic esters, hexamethylenetetramine and the like, and curing catalysts such as tertiary amines, pyridine derivatives, organic sulfonic acids, etc. . These can be used alone or in combination of two or more.

  When a phenolic resin is used as a binder, the phenolic resin can be prepared by reacting phenols with formaldehyde in the presence of a reaction catalyst. Here, phenols mean phenols and derivatives of phenols. For example, in addition to phenols, trifunctional ones such as m-cresol, resorcinol, 3,5-xylenol, bisphenol A, dihydroxydiphenylmethane, etc. 4 Functionalized, difunctional o such as o-cresol, p-cresol, p-ter-butylphenol, p-phenylphenol, p-cumylphenol, p-nonylphenol, 2,4 or 2,6-xylenol Mention may be made of-or p-substituted phenols, and further chlorine or bromine-substituted halogenated phenols and the like may be used. Of course, in addition to selecting and using one of these, it is also possible to use a mixture of multiple types.

  As the aldehydes, formalin which is in the form of an aqueous solution is most suitable, but a form such as paraformaldehyde, acetaldehyde, benzaldehyde, trioxane or tetraoxane can be used, and in addition, a part of formaldehyde is It is also possible to use it in place of aldehyde or furfuryl alcohol.

  It is preferable to set the blending ratio of the above-mentioned phenols and aldehydes in the range of 1: 0.5 to 1: 3.5 in molar ratio. Further, as a reaction catalyst, when preparing a novolak type phenol resin, an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid, or an organic acid such as oxalic acid, paratoluenesulfonic acid, benzenesulfonic acid or xylenesulfonic acid, and acetic acid Zinc or the like can be used. When preparing a resol type phenolic resin, oxides and hydroxides of alkaline earth metals can be used, and further, aliphatic amines such as dimethylamine, triethylamine, butylamine, dibutylamine, dibutylamine, tributylamine, diethylenetriamine, dicyandiamide and the like can be used. Primary, secondary, tertiary amines, aliphatic amines having an aromatic ring such as N, N-dimethylbenzylamine, aniline, aromatic amines such as 1,5-naphthalenediamine, ammonia, hexamethylenetetramine, etc. Other divalent metal naphthenic acids and divalent metal hydroxides can also be used.

  The novolak type phenol resin and the resol type phenol resin may be used alone or in combination of both in any ratio. Moreover, when diluting and using, solvents, such as alcohol, ketones, esters, and polyhydric alcohols, can be used.

  Next, as saccharides, monosaccharides, oligosaccharides and polysaccharides can be used, and among various monosaccharides, oligosaccharides and polysaccharides, one type is selected and used alone, and a plurality of types are selected and used in combination You can also

  Examples of monosaccharides include, but are not limited to, glucose (glucose), fructose (fructose), galactose and the like.

  Examples of oligosaccharides include disaccharides such as maltose (malt sugar), sucrose (sucrose), lactose (lactose), cellobiose and the like.

  Further, as polysaccharides, there are starch sugar, dextrin, xanthan gum, curdlan, pullulan, cycloamylose, chitin, chitosan, cellulose, starch and the like, and one kind of them is selected or plural kinds are used in combination be able to. Examples of starch include raw starch and processed starch. Specifically, raw starches such as potato starch, corn starch, high amylose, sweet potato starch, tapioca starch, sago starch, rice starch, amaranth starch, and their processed starches (soy roasted dextrin, enzyme-modified dextrin, acid-treated starch, Oxidized starch), dialdehyded starch, etherified starch (carboxymethyl starch, hydroxyalkyl starch, cationic starch, methylolated starch etc.), esterified starch (acetic acid starch, phosphoric acid starch, succinic acid starch, octenyl succinic acid starch, maleic acid starch Examples include acid starch, higher fatty acid esterified starch, etc., crosslinked starch, kraftized starch, and heat-treated starch. Among these, roasted dextrin, cyclodextrin, enzyme-modified dextrin, acid-treated starch, low molecular weight starch such as oxidized starch, and starch with low viscosity such as cross-linked starch are preferable. Furthermore, a plant containing saccharides such as wheat, rice, potato, corn, tapioca, sweet potato, sago, amaranthus powder and the like can be used. In addition, commercially available sugars for food use may also be used, such as white coarse, medium coarse, granulated sugar, invert sugar, top white sugar, white white sugar, and 3-point sugar. Furthermore, phenol-modified saccharides obtained by reacting saccharides with phenols can also be used.

  Carboxylic acid may be added to the saccharide, particularly as a polysaccharide curing agent. The carboxylic acid is not particularly limited, and polyvalent carboxylic acids such as oxalic acid, maleic acid, succinic acid, citric acid, butanetetradicarboxylic acid, methyl vinyl ether-maleic anhydride copolymer and the like may be mentioned. it can. The blending amount of the carboxylic acid is preferably in the range of 0.1 to 10 parts by mass of the carboxylic acid with respect to 100 parts by mass of the saccharide. It is preferable to mix the carboxylic acid with the saccharide in the state of being dissolved in water in advance, since the effect as a curing agent is exhibited highly.

  Water-soluble inorganic compounds are not particularly limited, but water glass, sodium chloride, sodium phosphate, sodium carbonate, sodium vanadate, sodium borate, sodium aluminum oxide, sodium chloride, potassium chloride, potassium carbonate, sulfuric acid compound Can be used. These can be used alone or in combination of two or more arbitrary ones.

Additional water glass is a mixture of silicic anhydride (SiO ₂₎ and sodium oxide _(Na 2 O), also called sodium silicate, represented by the general formula _{Na 2 O · nSiO 2 · xH} 2 O shown in JIS K1408, It is possible to use powdery, liquid or crystalline ones. Further, potassium silicate (K ₂ O · nSiO ₂ ) can also be used.

Water glass is very soluble in water and solidifies upon drying. For this reason, by using water glass as a binder, it is possible to produce a mold that is easily disintegrated by water. Further, since water glass can be obtained at low cost, the mold can be manufactured at low cost. Furthermore, since Na ₂ SiO ₃ has a relatively high melting point of 1088 ° C., a mold having high heat resistance can be produced.

  The above-mentioned sodium chloride is edible as sodium chloride (NaCl) is said to be edible, harmless to the human body, inexpensive and easy to use. And since it is easily dissolved in water, by using sodium chloride as a binder, it is possible to produce a mold that is easily disintegrated with water. In particular, the solubility of sodium chloride in water in the temperature range of 0 to 100 ° C. is 35.7 to 39.1 g with respect to 100 g of water, and the change due to the water temperature is small, so the workability is good. Furthermore, since NaCl has a relatively high melting point of 1413 ° C., a mold having high heat resistance can be produced.

As sodium phosphate mentioned above, monosodium phosphate hydrate (NaH ₂ PO ₄ .xH ₂ O), disodium phosphate hydrate (Na ₂ HPO ₄ .xH ₂ O), trisodium phosphate hydrate or the like can be used objects _{(Na 3 PO 4 · xH 2} O). And sodium phosphate is soluble in water so that the dissolution amount in 100 g of water is 1.5 g (0 ° C.), and the melting point of disodium phosphate hydrate is 1340 as trisodium phosphate hydrate is 1.5 g (0 ° C.). As it is ° C, the melting point of sodium phosphate is relatively high. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

The above-mentioned sodium carbonate (K ₂ CO ₃ ) is easily dissolved in water and is inexpensive, as the amount dissolved in 100 g of water is 7.1 g (0 ° C.). The melting point is relatively high at 851 ° C. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

The above-mentioned sodium vanadate (Na ₃ VO ₄ ) is soluble in water and has a relatively high melting point of 866 ° C. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

The above-mentioned sodium borate (Na ₂ B ₄ O ₇ · x H ₂ O) is easily dissolved in water so that the amount dissolved in 100 g of water is 1.6 g (10 ° C.), and is inexpensive. The melting point is relatively high at 741 ° C. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

The above-mentioned sodium aluminum oxide (NaAlO ₂ ) is soluble in water and has a high melting point of 1700 ° C. or higher. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

  The potassium chloride (KCl) described above is easily dissolved in water and is inexpensive, as the amount dissolved in 100 g of water is 28.1 g (0 ° C.). The melting point is relatively high at 776 ° C. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

The above potassium carbonate (K ₂ CO ₃ ) is easily dissolved in water so that the amount dissolved in 100 g of water is 129.4 g (0 ° C.), and is relatively high such that the melting point is 891 ° C. For this reason, it can be easily disintegrated with water and a mold having high heat resistance can be produced.

Further, the above-mentioned sulfuric acid compound is not particularly limited, but it is possible to use MgSO ₄ , Na ₂ SO ₄ .xH ₂ O, Al ₂ (SO ₄ ) ₃ .xH ₂ O, K ₂ SO ₄ , NiSO _4. Examples thereof include xH ₂ O, ZnSO ₄ .xH ₂ O, MnSO ₄ .xH ₂ O, and K ₂ Mg (SO ₄ ) ₂ .xH ₂ O.

Sulfuric acid compounds are easily dissolved in water and are inexpensive. For example, the amount dissolved in 100 g of water is 26.9 g (0 ° C.) for magnesium sulfate (MgSO ₄ ), 19.4 g (20 ° C.) for sodium sulfate decahydrate (Na ₂ SO ₄ · 10 H ₂ O), Aluminum sulfate 12-hydrate (Al ₂ (SO ₄ ) 3 12 H ₂ O) 36.2 g (20 ° C.), potassium sulfate (K ₂ SO ₄ ) 10.3 g (0 ° C.), nickel sulfate 7 hydrate _(NiSO 4 · _7H 2 O) is 39.7g (20 ℃), manganese pentahydrate sulfate _(MnSO 4 · _5H 2 O) is 75.3g (25 ℃). For this reason, by using a sulfuric acid compound as a caking agent, it is possible to inexpensively manufacture a mold that is easily disintegrated by water. The melting point of the sulfuric acid compound is, for example, 1185 ° C. for magnesium sulfate (MgSO ₄ ), 884 ° C. for sodium sulfate · decahydrate (Na ₂ SO 4 · 10H ₂ O), aluminum sulfate · 12 hydrate (Al ₂ (SO ₂ ) ₄ ) ₃ · 12H ₂ O) at 770 ° C, potassium sulfate (K ₂ SO ₄ ) at 1067 ° C, nickel sulfate heptahydrate (NiSO ₄ · 7H ₂ O) at 840 ° C, zinc sulfate heptahydrate (ZnSO ₄ · 7 H ₂ O) at 740 ° C, manganese sulfate pentahydrate (MnSO ₄ · 5 H ₂ O) at 850 ° C, magnesium potassium sulfate (K ₂ Mg (SO ₄ ) ₂ · 6 H ₂ O) 927 The relatively high temperature of ° C. makes it possible to produce molds with high heat resistance.

The water-soluble inorganic compound can be used alone or in combination of any one selected from those listed above, or in combination of any two or more.

The invention of the above binder, a shall use a water-soluble inorganic compound alone.

  The caking material for a mold used in the present invention is formed by containing silicon carbide and these caking agents. Silicon carbide is used as a powder, and the particle size of the powder is not particularly limited. For example, the particle size is preferably in the range of 0.1 to 300 μm. Further, the ratio of the caking agent to silicon carbide contained in the caking material for the mold is not particularly limited, but 0.5 to 200 parts by mass of silicon carbide with respect to 100 parts by mass of the caking agent (solid content) In particular, the range of 50 to 150 parts by mass is preferable.

  In producing a mold using a caking material for a mold, for example, the caking material for a mold may be mixed with a refractory aggregate, and this may be filled into a mold for forming a mold and then molded. .

  Here, when the caking agent of the caking material for the mold is a thermosetting resin, when the mixture of the fireproof aggregate and the caking material for the mold is filled in a mold heated to a high temperature, the thermosetting resin melts. Since it hardens | cures, the cast which joined the fireproof aggregate with the hardened | cured material of a thermosetting resin can be obtained.

  When the caking agent of the caking material for the mold is a saccharide or a water-soluble inorganic compound, the mixture of the fireproof aggregate and the caking material for the mold is filled with a mixture of water and moisture into the mold. Alternatively, after the mixture of the fireproof aggregate and the caking material for the mold is filled in the mold, water is supplied into the mold. When water acts on the caking material for the mold, the saccharides in the caking material for the mold absorb the water and become wet, and the water-soluble inorganic compound dissolves in the water and becomes wet, and all are gelatinized In this case, the fireproof aggregate is bonded by this adhesive action. Then, the mold is heated or dry gas is supplied to the mold to dry the saccharide and the water-soluble inorganic compound, and the saccharide and the water-soluble inorganic compound are solidified to obtain the saccharide and the water-soluble inorganic compound. It is possible to obtain a mold in which the refractory aggregate is bonded with a solidified material.

  The above-mentioned refractory aggregate is not particularly limited, but can be exemplified by borax, mountain sand, alumina sand, olivine sand, chromite sand, zircon sand, mullite sand, others, artificial sand and the like. These can be used alone or in combination of two or more.

  In the present invention, the caking material for the mold may be used by being mixed with the fireproof aggregate as described above, but the surface of the fireproof aggregate may be used by covering the caking material for the mold It is also good. It can be used as a binder coated refractory (so-called resin coated sand) by coating the surface of the particles of the refractory aggregate with a caking material for a mold to form a binder layer. The binder layer made of the mold caking material is preferably solid at an ambient temperature (for example, 20 to 40 ° C.) at which the caking material for mold is stored and used. When the binder layer is solid, the binder-coated refractories become free-flowing particles, and the fluidity is good and the workability is improved.

  The amount of caking material for molds to be coated on the fireproof aggregate differs depending on the components of the caking material for the mold and the use of the mold, etc., and can not be specified indiscriminately. It is generally preferred to set the content of the binder in the range of 0.5 to 6.0 parts by mass.

  A lubricant may be contained in the binder layer in order to improve the flowability of the binder-coated refractory. As lubricants, aliphatic hydrocarbon lubricants such as paraffin wax and carnauba wax, higher aliphatic alcohols, aliphatic amide lubricants such as ethylenebisstearate amide and stearic acid amide, metallic soap lubricants, fatty acid ester lubricants Composite lubricants and the like can be used, among which metal soap lubricants are preferred. As the metal soap-based lubricant, calcium stearate, barium stearate, zinc stearate, aluminum stearate, magnesium stearate or the like, or a combination of two or more of these can be used. It is generally preferable that the lubricant be blended in the range of 0.02 to 0.15 parts by mass in solid content with respect to 100 parts by mass of the refractory aggregate.

  In forming a caking agent layer made of caking material for a mold on the surface of the fireproof aggregate, a method of mixing the caking agent and the powder of silicon carbide with the fireproof aggregate and mixing them in advance, A method of mixing the binder and the powder of silicon carbide, mixing this mixture into the fireproof aggregate and mixing, after mixing the fireproof aggregate and the powder of silicon carbide, the binder is mixed with this There is a method of mixing and mixing, and after mixing a refractory aggregate and a caking agent, a powder of silicon carbide is mixed and mixed therewith. In any of the methods, a caking agent layer composed of a caking material for a mold containing a caking agent and a powder of silicon carbide can be formed on the surface of the refractory aggregate.

  First, a representative method will be described with respect to a method for producing a binder coated sand by blending a binder and powder of silicon carbide with the refractory aggregate and mixing them.

  When the binder is a thermosetting resin, powder of powder of thermosetting resin in solid form and powder of silicon carbide are added to the refractory aggregate heated to a temperature at which the thermosetting resin melts, for example, 110 to 180 ° C. Are added separately and mixed by stirring. The solid thermosetting resin is melted by heating with the fireproof aggregate, and the surface of the fireproof aggregate can be coated in a state where the melted thermosetting resin and the silicon carbide powder are mixed. After that, the solid caking agent layer made of a caking material for a mold containing a thermosetting resin and silicon carbide by solidifying the thermosetting resin by cooling or natural cooling while holding stirring and mixing to solidify the thermosetting resin. To obtain a binder coated refractory coated with the fireproof aggregate.

  When the binder is a saccharide or a water-soluble inorganic compound, it is used in a state in which powder particles of the saccharide or the water-soluble inorganic compound are dissolved or dispersed in water. Then, an aqueous solution or dispersion of this saccharide or water-soluble inorganic compound and a powder of silicon carbide are respectively blended in the refractory aggregate, and this is stirred and mixed. When such stirring is performed, when an aqueous solution or dispersion of saccharides or a water-soluble inorganic compound is mixed with the fireproof aggregate, the powder of silicon carbide is simultaneously kneaded, which makes it possible to mix the saccharides with the fireproof aggregate An aqueous solution or dispersion of an inorganic compound and a powder of silicon carbide can be uniformly mixed. After this, by retaining the stirring and mixing while evaporating the water, the refractory aggregate is covered with a solid caking agent layer comprising a caking material for a mold containing a saccharide, a water-soluble inorganic compound and silicon carbide. Binder coated refractories can be obtained. At this time, the refractory aggregate is previously heated in the same manner as described above, and the refractory aggregate is prepared by mixing and mixing an aqueous solution or dispersion of saccharides and a water-soluble inorganic compound with a powder of silicon carbide. The heat of can evaporate the water. Alternatively, the water may be evaporated by mixing while heating from the outside.

  Next, a typical method will be described for a method of producing a binder-coated refractory by mixing a binder and a powder of silicon carbide, blending the mixture with the refractory aggregate, and mixing the mixture. .

  When the binder is a thermosetting resin, the thermosetting resin is heated and melted, a powder of silicon carbide is mixed with the molten thermosetting resin, and the mixture is stirred and kneaded. Do. Next, the mixture of the thermosetting resin and the silicon carbide powder is cooled, solidified, and crushed into powdery particles. Then, powder particles containing the powder of the thermosetting resin and the silicon carbide are added to the refractory aggregate heated to a temperature at which the thermosetting resin melts, for example, 110 to 180 ° C., and mixed by stirring, the refractory aggregate The thermosetting resin is melted by heating according to the above, and the surface of the refractory aggregate can be coated with the thermosetting resin melted in the state where the silicon carbide powder is mixed. After that, the solid caking agent layer made of a caking material for a mold containing a thermosetting resin and silicon carbide by solidifying the thermosetting resin by cooling or natural cooling while holding stirring and mixing to solidify the thermosetting resin. To obtain a binder coated refractory coated with the fireproof aggregate.

  When the binder is a saccharide or a water-soluble inorganic compound, it is used in a state in which powder particles of the saccharide or the water-soluble inorganic compound are dissolved or dispersed in water. Then, powder of silicon carbide is mixed with an aqueous solution or dispersion of a saccharide or a water-soluble inorganic compound, and this is stirred and mixed to obtain a mixed solution of saccharide or a water-soluble inorganic compound and silicon carbide. Next, this mixture is added to the refractory aggregate and mixed by stirring. After this, by retaining the stirring and mixing while evaporating the water, the refractory aggregate is covered with a solid caking agent layer comprising a caking material for a mold containing a saccharide, a water-soluble inorganic compound and silicon carbide. Binder coated refractories can be obtained. At this time, the fireproof aggregate is previously heated in the same manner as described above, and the mixed liquid of saccharides and a water-soluble inorganic compound and silicon carbide is mixed and mixed with this, whereby the heat of the fireproof aggregate is water. It can be evaporated. Alternatively, the water may be evaporated by mixing while heating from the outside.

  As described above, a mixture of a binder and a powder of silicon carbide is prepared in advance, and the mixture is mixed with the fireproof aggregate to produce a binder-coated refractory. A mixture of the agent and the silicon carbide powder and a binder which does not contain the silicon carbide powder may be used in combination, and both may be mixed with the carbonized aggregate to produce a binder-coated refractory. In this case, the mixture of the binder and the silicon carbide should be set higher than the generally required content of silicon carbide, and the amount of the binder not containing the silicon carbide powder to be used in combination should be adjusted. This makes it possible to adjust the amount of silicon carbide contained in the binder layer coated on the refractory aggregate to a necessary amount. Therefore, it is not necessary to prepare in advance a mixture of caking agent and silicon carbide in which many kinds of caking agent and silicon carbide are different.

  Next, after mixing a refractory aggregate and a powder of silicon carbide, a typical method is demonstrated about the method of manufacturing a binder coated refractory by mix | blending and mixing a caking additive with this.

  First, the powder of silicon carbide is uniformly dispersed in the refractory aggregate by stirring and mixing the particles of the refractory aggregate and the powder of silicon carbide. Next, when the binder is a thermosetting resin, the mixture of the refractory aggregate and silicon carbide is heated to a temperature at which the thermosetting resin melts, for example, 110 to 180 ° C., and a solid thermosetting resin is cured thereon. The powdery resinous resin particles are respectively added, stirred and mixed. Solid thermosetting resin is melted by heating with the fireproof aggregate, and the silicon carbide powder dispersed in the fireproof aggregate is mixed with the melted thermosetting resin, and the thermosetting resin melts the surface of the fireproof aggregate in this state. Can be coated with a resin. Then, after that, cooling is performed while holding the stirring and mixing to solidify the thermosetting resin, whereby a refractory aggregate is a solid caking agent layer made of a caking material for a mold containing a thermosetting resin and silicon carbide. Can be obtained. The refractory aggregate may be heated to the above temperature in the initial stage of mixing with the silicon carbide powder.

  When the binder is a saccharide or a water soluble inorganic compound, the saccharide or water soluble inorganic compound is used in a state of being dissolved or dispersed in water. Then, an aqueous solution or dispersion of this saccharide or water-soluble inorganic compound is added to the mixture of the above-mentioned refractory aggregate and powder of silicon carbide, and the mixture is stirred and mixed. By stirring and mixing in this manner, the silicon carbide powder dispersed in the fireproof aggregate is mixed with the aqueous solution or dispersion of the saccharide or the water-soluble inorganic compound, and in this state, the silicon carbide powder is a saccharide It can be coated with an aqueous solution or dispersion of a water-soluble inorganic compound. After this, by retaining the stirring and mixing while evaporating the water, the refractory aggregate is covered with a solid caking agent layer comprising a caking material for a mold containing a saccharide, a water-soluble inorganic compound and silicon carbide. Binder coated refractories can be obtained. At this time, the refractory aggregate is previously heated in the same manner as described above, and the refractory aggregate is prepared by mixing and mixing an aqueous solution or dispersion of saccharides and a water-soluble inorganic compound with a powder of silicon carbide. The heat of can evaporate the water. Alternatively, the water may be evaporated by mixing while heating from the outside.

  Next, after mixing a refractory aggregate and a caking agent, a representative method will be described with respect to a method of producing a caking agent coated refractory by blending and mixing silicon carbide powder thereto. .

  When the binder is a thermosetting resin, powder particles of solid thermosetting resin are added to the refractory aggregate heated to a temperature at which the thermosetting resin melts, for example, 110 to 180 ° C., and the mixture is stirred. Mix and mix. The solid thermosetting resin is melted by heating with the fireproof aggregate, and the melted thermosetting resin can be uniformly mixed with the fireproof aggregate. After uniformly mixing the thus-melted thermosetting resin with the refractory aggregate, powder of silicon carbide is added while the thermosetting resin is in a molten state, and the mixture is stirred and mixed. The silicon carbide powder is uniformly mixed with the molten thermosetting resin, and the surface of the refractory aggregate can be coated with the thermosetting resin melted in a state where the silicon carbide powder is mixed. After that, the solid caking agent layer made of a caking material for a mold containing a thermosetting resin and silicon carbide by solidifying the thermosetting resin by cooling or natural cooling while holding stirring and mixing to solidify the thermosetting resin. To obtain a binder coated refractory coated with the fireproof aggregate.

  When the binder is a saccharide or a water soluble inorganic compound, the saccharide or water soluble inorganic compound is used in a state of being dissolved or dispersed in water. Then, the aqueous solution or dispersion of the saccharide or the water-soluble inorganic compound is mixed with the refractory aggregate, and the aqueous solution or dispersion of the saccharide or the water-soluble inorganic compound is uniformly mixed with the refractory aggregate by stirring. Can. After uniformly mixing the aqueous solution or dispersion of the saccharides and the water-soluble inorganic compound in the refractory aggregate as described above, powder of silicon carbide is added and mixed while maintaining stirring. The silicon carbide powder is uniformly mixed with an aqueous solution or dispersion of a saccharide or water-soluble inorganic compound, and the surface of the refractory aggregate is treated with the aqueous solution or dispersion of the saccharide or water-soluble inorganic compound in a state where the silicon carbide powder is mixed. It can be coated. After this, by retaining the stirring and mixing while evaporating the water, the refractory aggregate is covered with a solid caking agent layer comprising a caking material for a mold containing a saccharide, a water-soluble inorganic compound and silicon carbide. Binder coated refractories can be obtained. At this time, the refractory aggregate is previously heated in the same manner as described above, and the refractory aggregate is prepared by mixing and mixing an aqueous solution or dispersion of saccharides and a water-soluble inorganic compound with a powder of silicon carbide. The heat of can evaporate the water. Alternatively, the water may be evaporated by mixing while heating from the outside.

  In each of the above methods, sugars and water-soluble inorganic compounds are dissolved or dispersed in water, but as a solvent for dissolving or dispersing sugars and water-soluble inorganic compounds in water, water is most preferable as described above. It is also possible to use organic solvents such as alcohol and the like. Further, each of the above-described methods is merely a representative example, and the present invention is not limited to the above-described methods.

  A mold can be manufactured using the binder coated refractory prepared as described above. For example, in the case of a binder coated refractory using a thermosetting resin as a binder, the mold can be formed by supplying the binder coated refractory to a heated mold.

  The heating temperature of the mold is set to a temperature at which the thermosetting resin of the binder melts and cures. For example, when the thermosetting resin is a phenol resin, although depending on the type of the phenol resin, it is desirable to heat the mold to a temperature of 150 ° C. or more. When a mold is formed by supplying and filling a binder-coated refractory in the cavity of the mold, it takes time to reach the strength capable of transferring heat to the binder-coated refractory in the cavity and removing the mold. Therefore, depending on the size of the mold, it is preferable to set the molding time to about 20 seconds to 5 minutes.

  Thus, when a binder coated refractory is supplied to a mold heated to a temperature higher than the temperature at which the thermosetting resin melts and cures, the thermosetting resin in the binder layer is melted by the heat of the mold. Cure with. Therefore, the refractory aggregate can be adhered with the molten thermosetting resin, and the refractory aggregate can be bonded with the hardened thermosetting resin, and in this way, the inside of the mold is obtained. The mold can be formed by

  In the above example, the case of filling the binder coated refractory in the cavity of the heated mold and molding the mold was explained, but the binder coated fireproof is applied so as to sprinkle on the surface of the heated mold. It is also possible to mold the mold by feeding the material and heating the binder coated refractory on the surface of the mold.

  Next, the case of a caking agent coated refractory using saccharides or a water soluble inorganic compound as a caking agent will be described. In this case, the mold is first filled with a binder-coated refractory, and then water is supplied into the mold. The water can be supplied by any method such as passing water through the mold. When water is supplied as described above, the saccharides of the caking agent and the water-soluble inorganic compound absorb the water to cause adhesiveness, and the fireproof aggregate can be cohesive by this adhesive force.

  Next, when the inside of the mold is dried to remove moisture, the saccharides and the water-soluble inorganic compound are dried and solidified, so the fireproof aggregate can be bonded with the solidified saccharide and the water-soluble inorganic compound, and the mold is formed. It can be done. The method for drying the inside of the mold is optional, and for example, there is a method of ventilating dry gas such as heated air to the mold to evaporate water, a method of heating the mold to evaporate water, and the like. As will be described later, by allowing water vapor to flow into the mold filled with the binder-coated refractory, it is possible to supply water with condensed water from the water vapor, and continue to aerate the water vapor as it is. Thus, the inside of the mold can be dried by heating by the latent heat of condensation of steam and sensible heat.

  Further, in the present invention, the mold can be molded by supplying a water vapor into the mold after the cinder coated refractory is filled in the mold, and this method will be described below.

  FIG. 1 shows an example of the manufacture of a mold using water vapor. As shown in FIG. 1 (a), a cavity 3 is provided inside the mold 1 and an injection port is formed on the upper surface of the mold 1 An exhaust port 6 is formed on the lower surface of the mold 1 respectively. The exhaust port 6 is formed in a small diameter so that the binder coated refractory 2 can not pass through, or closed with a mesh 5 such as a wire mesh so that the binder coated refractory 2 does not leak from the exhaust port 6 . The mold 1 can be divided vertically or horizontally. Further, the binder-coated refractory 2 is stored in the hopper 7, and the hopper 7 is connected to an air supply pipe 9 with a cock 8.

  Then, after matching the nozzle opening 7 a at the lower end of the hopper 7 with the injection opening 4 of the mold 1, air is blown into the hopper 7 to pressurize it by switching the cock 8 from closed to open. The binder coated refractory 2 is blown into the mold 1 to fill the cavity 3 of the mold 1 with the binder coated refractory 2. When a plurality of inlets 4 and outlets 6 are provided in the mold 1 as in the embodiment of FIG. 1, the cinder coated refractory 2 may be inserted from one or a plurality of locations among the plurality of inlets 4. Good.

  Here, in the binder coated refractory 2, the binder layer coated on the fireproof aggregate is solid, and the binder coated refractory 2 does not have adhesiveness on the surface, and the flowability is good. is there. Therefore, when the binder-coated refractory 2 is filled into the mold 1 as described above, the binder-coated refractory 2 can be smoothly poured into the cavity 3 of the mold 1, and the mold 1 with good filling property The inside can be filled with the binder coated refractories 2, which can prevent the occurrence of filling failure.

  After the binder coated refractory 2 is filled in the mold 1 as described above, the hopper 7 is removed from the inlet 4 of the mold 1 and, as shown in FIG. The pipe 10 is connected, the cock 11 of the air supply pipe 10 is opened, and water vapor is blown into the cavity 3 of the mold 1 to pass the water vapor through the mold 1.

  Here, as steam, saturated steam can be used as it is, but in the present invention, superheated steam is preferably used. Superheated steam is steam in a completely gaseous state, which is further heated to a temperature above the boiling point by further heating saturated steam, and is dry steam at 100 ° C. or above. The superheated steam obtained by heating the saturated steam may be one expanded at a constant pressure without increasing the pressure, or may be pressurized steam at an increased pressure without expansion. The temperature of the superheated steam blown into the mold 1 is not particularly limited, and since the temperature of the superheated steam can be increased to about 900 ° C., the temperature may be set between 100 and 900 ° C. according to the need. Just do it.

  When the steam is blown into the mold 1 in this way, the steam comes into contact with the surface of the binder coated refractory 2 so that the latent heat of the steam is taken away by the binder coated refractory 2 and condenses. However, since the steam has high latent heat and sensible heat, the temperature of the binder-coated refractory 2 rapidly rises to around 100 ° C. due to the latent heat and sensible heat transferred when the steam condenses. The time during which the binder coated refractory 2 is heated to around 100 ° C. by the heat transfer of the latent heat of the water vapor and the sensible heat in this manner depends on the temperature of the water vapor and the flow rate of blowing into the mold 1. Although it changes with the filling amount of the caking agent coated refractory 2, etc., it is a short time of about 3 to 30 seconds normally. The water vapor blown into the mold 1 from the inlet 4 is discharged from the exhaust port 6 after heating the binder coated refractory 2 in the mold 1.

  The temperature of the binder coated refractory 2 can be rapidly raised by the latent heat of condensation of the steam blown into the mold 1 and the sensible heat as described above, and the condensation of the steam forms in the mold 1 The condensed water is evaporated by heating with steam which is subsequently blown into the mold 1, so that the temperature in the mold 1 rapidly rises to around the temperature of the steam, and at this temperature the binder is coated. The refractory 2 can be heated.

  And when the binder of the binder coated refractory 2 is a thermosetting resin, the binder coated refractory 2 filled in the mold 1 is heated by the latent heat of condensation of steam and the sensible heat to be cured. The thermosetting resin can be melted and cured by raising the temperature to a temperature higher than the curing temperature of the insulating resin, and the mold is formed in a state in which the refractory aggregate is bonded with the cured thermosetting resin. It is possible to

  Thus, by supplying steam to the mold 1 to heat the binder coated refractory 2, the binder coated refractory 2 is instantaneously heated with high latent heat of condensation and sensible heat of the steam, The thermosetting resin of the binder layer can be cured, and the mold can be manufactured in a short time without the need to heat the mold 1 to a high temperature beforehand, and the productivity of the mold Can be improved. In addition, even if toxic gas is generated from the thermosetting resin of the caking agent during heating, it can be absorbed by the condensed water of the water vapor, and environmental pollution can be reduced.

  When the binder of the binder coated refractory 2 is a saccharide or a water-soluble inorganic compound, the steam comes into contact with the binder coated refractory 2 as described above when the steam is started to be blown into the mold 1 Because the heat is taken away to generate condensed water, the condensed water acts on the binder of the binder coated refractory 2. When condensed water acts on saccharides and water-soluble inorganic compounds in the solid state caking agent layer of the caking agent coated refractory 2, when the caking agent is saccharides, the condensed water is absorbed to swell or It dissolves and gelatinizes, and when the binder is a water-soluble inorganic compound, it dissolves in the condensed water to become liquid and gelatinizes, and all the binders consisting of saccharides and water-soluble inorganic compound are paste-like. Becomes tacky. Thus, when the tackiness of the caking agent is generated, the refractory aggregate of the caking agent-coated refractory 2 filled in the mold 1 is bonded by the tackiness of the caking agent. Subsequently, the caking agent coated refractory 2 is heated by the latent heat of condensation of the water vapor blown into the molding die 1 and the sensible heat successively, and the water acting on the caking agent evaporates and is dried. The caking agent comprising the inorganic compound can be dried and solidified, and the refractory aggregate can be bonded by the solidified caking agent to form a mold.

  Thus, when manufacturing the mold by heating the binder in the binder layer of the binder coated refractory 2 with steam to manufacture a mold, saccharides and water-soluble inorganic compounds contained as the binder are heated. It does not generate a large amount of harmful gas when it solidifies, and it can manufacture a mold without polluting the environment.

  As described above, steam is introduced into the mold 1 filled with the binder coated refractory 2, and the binder coated refractory 2 is heated and solidified or cured by the latent heat of condensation of steam and sensible heat, and the mold is In manufacturing, the condensed water generated in the mold 1 is heated and vaporized by the steam which is blown later as described above, and is discharged from the exhaust port 6, but the shape of the cavity 3 of the mold 1, etc. In some cases, part of the condensed water may remain in the mold 1 without sufficient vaporization of the condensed water. When the condensed water remains in the mold 1 as described above, the residual condensed water is contained in the mold demolded from the mold 1 in a state of being permeated as moisture. When the mold contains water, when casting is performed using this mold, when a high-temperature molten metal is poured into the mold, the water contained in the mold is heated at the high temperature of the molten metal and is rapidly vaporized. Extremely dangerous accidents such as explosion of mold may occur.

  Therefore, in this case, steam is passed through the mold 1 filled with the binder coated refractory 2 as described above to heat the binder coated refractory 2 to form a mold, and then the supply of steam is stopped. Instead of the steam, dry gas may be passed into the mold 1. The dry gas is supplied into the mold 1 from the inlet 4, and thus the dry air supplied into the mold 1 is a binder-coated refractory 2 of the mold molded in the mold 1. Pass between the particles and are discharged from the exhaust port 6. Therefore, when residual condensed water remains as moisture in the mold molded in the mold 1, this water is vaporized in the dry gas and discharged from the exhaust port 6 together with the dry gas, and the mold is dried. It is something that can be

Here, in the present invention, the dry gas means a dry gas in which the water content (rate) in the gas is lower than the water content (rate) of the steam supplied to the mold 1, and the drying process was performed. It does not mean gas, and if the water content (rate) is low, it is not necessary to carry out the drying process. The water content of the dry gas is not particularly limited, but the water content is preferably 200 g / m ³ or less, more preferably 100 g / m ³ or less, and particularly preferably 50 g / m ³ or less It is. By supplying the dry gas having such a low water content to the mold 1, the mold can be efficiently dried. Also, the drying gas does not need to be heated and used. Heating and using the dry gas is not desirable because it requires equipment and energy costs to heat it, and therefore, the present invention does not heat or cool the dry gas at the same temperature, that is, as described above. The dry gas is used with the ambient temperature of the process of producing the mold, for example, the ambient temperature in the factory where the mold production facility is installed. The atmosphere temperature varies depending on the season, time, etc., but is usually in the range of about 0 ° C. to 50 ° C.

  Moreover, the kind of dry gas is not specifically limited, Air, inert gas, such as nitrogen, etc. can be used. Among them, air in the atmosphere is preferable because it can be used as it is without cost.

As described above, when stopping the supply of water vapor to the mold 1 and drying the mold through the mold 1, the time for passing the dry gas through the mold 1 depends on the size of the mold and the dry gas. Although it is not particularly limited depending on the supply amount of and the like, it is usually about 10 to 90 seconds. If the time for passing the dry gas is less than 10 seconds, drying of the mold in the mold 1 may be insufficient. Conversely, if the time for passing the dry gas exceeds 90 seconds, not only the drying quality will be excessive, but also the molding cycle from the loading of the binder coated refractory 2 into the mold 1 to the mold removal It may be long and cause problems with productivity.

  In order to pass dry gas into the mold 1 after the supply of water vapor to the mold 1 is stopped, after closing the cock 11 of the air supply pipe 10 for steam supply, the drawing of FIG. Remove the air supply pipe 10 connected as shown in FIG. 1 (b) and connect the air supply pipe 13 for dry gas supply to the inlet 4 of the mold 1, as shown in FIG. 1 (c). This can be done by opening the cock 14 of the pipe 13 and supplying the drying gas from the air supply pipe 13 into the mold 1. At this time, when air in the atmosphere is used as the dry gas, a blower such as a compressor or a gas supply fan is connected to the gas supply pipe 13 and the air in the atmosphere of the mold manufacturing process is directly formed from the blower for the gas supply pipe 13 Can be blown into the mold 1

  As described above, by bonding the fireproof aggregate with the caking agent in the caking agent layer of the caking agent coated refractory 2, when manufacturing the mold, in the caking agent layer other than the caking agent Since the powder of silicon carbide is contained in the above, the powder of silicon carbide is present in an exposed state on the surface of the mold.

  The casting can be carried out by pouring a molten metal, which is a high temperature molten metal, into the mold manufactured as described above and casting it. At this time, when the binder is a thermosetting resin such as a phenol resin, the thermosetting resin has high bond strength of the fireproof aggregate and high heat resistance, so casting using a relatively high temperature metal is possible. It is When the binder is a saccharide or a water-soluble inorganic compound, the saccharide is pyrolyzed at a relatively low temperature, so it is easily pyrolyzed by the heat of the molten metal, and the saccharide or water-soluble inorganic compound is easily soluble in water By soaking the mold in water after casting, the bonding strength with saccharides and water-soluble inorganic compounds is lost. Therefore, the mold can be easily disintegrated, and there is no need for impacting the mold or long-term heating at high temperature to decompose the binder in order to remove the casting from the mold. And the casting can be easily removed from the mold.

  Here, although the phenomenon that silicon carbide is poorly wetted by the molten metal that is the molten metal has been found by the present inventors, as described above, the powder of silicon carbide is exposed on the surface of the mold. Existing. For this reason, when casting the molten metal by pouring it into the mold, the molten metal is repelled by the powder of silicon carbide and hardly intrudes between the particles of the refractory aggregate, and the molten metal penetrates between the particles of the refractory aggregate. Can be reduced. Therefore, the seizing which generate | occur | produces by penetration of a molten metal at the time of casting can be prevented. As a result, there is no need to apply a coating on the surface of the mold to prevent the occurrence of burn-in, and casting can be performed without coating.

  In addition, when manufacturing a mold using a binder coated refractory coated with a binder layer containing silicon carbide as described above, a binder coated refractory coated with a binder layer containing silicon carbide The material may be used in combination with a binder coated refractory coated with a binder layer containing no silicon carbide. In this case, the silicon carbide content of the caking agent layer containing silicon carbide is set high, and the mixing amount of the caking agent coated refractory coated with the caking agent layer containing no silicon carbide used in combination is adjusted This makes it possible to adjust the amount of silicon carbide in situ to the required anti-seizure effect.

  Next, the present invention will be specifically described by way of examples.

( Reference Example 1 )
10 kg of ACI silica sand heated to 135 ° C. was charged in a whirl mixer, to which powder of phenolic resin and silicon carbide shown in Table 1 were added in amounts shown in Table 1. After kneading this for 30 seconds, a solution of 30 g of hexamethylenetetramine dissolved or dispersed in 450 g of water was added as needed, and knead until the lumps of sand grains were broken. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to obtain 2.0% by mass of phenolic resin relative to silica sand, as shown in Table 1. Binder coated refractory ( Reference Examples 1-1 to 1-5) in which the surface of silica sand is coated with a solid binder layer containing silicon carbide powder of the following.

(Comparative example 1)
A binder-coated refractory was obtained in the same manner as in Reference Example 1 except that silicon carbide was not used.

The fusion points of the binder layer of the binder-coated refractory of Reference Example 1 and Comparative Example 1 prepared as described above were measured in accordance with JACT test method C-1 “fusion point test method”. The results are shown in Table 1.

In addition, using the binder coated refractories of Reference Example 1 and Comparative Example 1, test pieces were formed assuming mold formation. That is, heating the molding die capable of molding a width 10mm × length 70 mm × thickness of 10mm of the test piece to 240 ° C. ± 5 ° C., binder coated refractory of Example 1 and Comparative Example 1 in the molding die The sample was blown in with an air pressure of 0.1 MPa gauge pressure and filled, and after 60 seconds, a test piece assuming a mold was formed by demolding.

  The flexural strength of this test piece was measured in accordance with JACT test method SM-1. The results are shown in Table 1.

As seen in Table 1, the welding point of the binder layer was almost the same as in Reference Example 1 and Comparative Example 1. The bending strength of the reference example 1 is slightly lower than that of the comparative example 1 but no significant difference is observed, and a mold is obtained by containing silicon carbide in the caking agent layer of the caking agent coated refractory. It was confirmed that there was no problem in the strength as

Further, using the mold having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the caking agent coated refractor of Reference Example 1 and Comparative Example 1 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference example 2 )
10 kg of ACI silica sand preheated to 125 ° C. is charged in a whirl mixer, and a solution in which 200 g of dextrin and 30 g of citric acid as its curing agent are dispersed or dissolved in 150 g of water is added. It was added and mixed. After knead until the lump of sand grains collapsed, 10 g of calcium stearate was added as a lubricant and the mixture was kneaded for 30 seconds, and this was discharged from the whirl mixer. By aeration and cooling this, the surface of silica sand is coated with a solid binder layer containing 2.0% by mass of dextrin based on silica sand and silicon carbide powder in the amounts shown in Table 4. The obtained binder coated refractories ( Reference Examples 2-1 to 2-4) were obtained.

(Comparative example 2)
A binder coated refractory was obtained in the same manner as in Reference Example 2 except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 2 and Comparative Example 2 prepared as described above, test pieces were formed on the assumption of mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 2 or Comparative Example 2 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa, which was prepared in the following manner, was supplied at a flow rate of 60 kg / h, and the superheated steam was bubbled into the molding die for 60 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The bending strength of the test piece obtained by molding in this manner was measured in accordance with JIS K 6910. In addition, another test piece was placed in a heating dryer previously set at 250 ° C. and heat treated for 60 minutes, and after cooling, the bending strength was measured according to JIS K 6910. The results are shown in Table 2.

As seen in Table 2, in the case of Reference Example 2 , the bending strength does not decrease much more than that of Comparative Example 2, and by containing silicon carbide in the binder layer of the binder coated refractory. It was confirmed that there was no problem in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the caking agent coated refractories of Reference Example 2 and Comparative Example 2 are molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

(Example 3)
10 kg of ACI silica sand heated to 140 ° C. is charged in a whirl mixer, to which a solution of a water-soluble inorganic compound of the type and amount shown in Table 3 dissolved in 150 g of water and 200 g of silicon carbide powder are added Kneaded for 90 seconds. After the sand grit collapses, add 10 g of calcium stearate as a lubricant and knead for 15 seconds, then remove it from the whirl mixer, aerate it and cool it down to 4.0 wt. Binder coated refractory (Examples 3-1 to 3-4) in which the surface of silica sand is coated with an inorganic compound and a solid binder layer containing 2.0% by mass of silicon carbide powder Obtained.

  Here, as water glass, sodium silicate No. 1 (solid content: 50% by mass) manufactured by Fuji Chemical Co., Ltd., and as sodium chloride, commercially available sodium chloride having a sodium chloride content of 98.3% by mass produced by seawater, As disodium phosphate, reagents from Kishida Chemical Co., Ltd. were used respectively.

(Comparative example 3)
Binder coated refractory (Comparative Example 3-1 to 3--3) in the same manner as Example 3, except that the water-soluble inorganic compounds shown in Table 3 were used in amounts shown in Table 3 and silicon carbide was not used. I got 3).

  Using the binder coated refractories of Example 3 and Comparative Example 3 prepared as described above, test pieces were formed assuming molding of a mold. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Example 3 or Comparative Example 3 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  About the test piece obtained by molding in this way, when smell was smelled immediately after demolding from the mold, no offensive odor was felt. Further, the flexural strength of this test piece was measured in accordance with JIS K 6910. The results are shown in Table 3.

  As seen in Table 3, comparing Example 3 with Comparative Example 3 in which the water-soluble inorganic compound corresponds, the bending strength of Example 3 is greater than that of Comparative Example 3 as seen in Table 3. It was confirmed that the strength of the mold does not become a problem by containing silicon carbide in the binder layer of the binder-coated refractory without causing a significant decrease.

  Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractories of Example 3 and Comparative Example 3 are molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 4 )
A novolak type phenol resin ("# 4800" manufactured by Lignite Co., Ltd.) was charged in a four-necked flask having a stirrer, and was stirred and melted while heating with a mantle heater, and the stirring was continued and the internal temperature became 160 ° C. Silicon carbide powder was added little by little so that the amounts in Table 4 were obtained at that time. After stirring and mixing for another 30 minutes, it was solidified by discharging from a four-necked flask and cooling. By crushing this to a particle size of 0.1 to 5 mm with a crusher, caking agent particles 1 to 3 containing novolac type phenol resin and silicon carbide powder were obtained.

  The softening point of the caking agent particles 1 to 3 obtained as described above was measured according to JIS K 6910. The results are shown in Table 4.

  The softening point of the novolac type phenol resin "# 4800" is 94.5 ° C., and it is confirmed that the softening points of the caking agent particles 1 to 3 do not have much difference with the softening point of the novolac type phenol resin.

10 kg of ACI silica sand heated to 135 ° C. was charged in a whirl mixer, and the above-mentioned granules 1 to 3 were added thereto in the amounts shown in Table 5. The mixture was kneaded for 30 seconds and further kneaded until the lump of sand particles collapsed. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to obtain 2.0% by mass of phenolic resin relative to silica sand, and the amount shown in Table 5 Binder coated refractory ( Reference Examples 4-1 to 4-4) in which the surface of silica sand was coated with a solid binder layer containing silicon carbide powder of the following.

(Comparative example 4)
A binder-coated refractory was obtained in the same manner as in Reference Example 4 , except that novolac type phenolic resin was used as it was, without using silicon carbide.

Using the binder coated refractories of Reference Example 4 and Comparative Example 4 prepared as described above, test pieces were formed assuming mold formation. That is, a molding die capable of molding a test piece having a width of 10 mm × length 70 mm × thickness 10 mm is heated to 240 ° C. ± 5 ° C., and the binder coated refractory of Reference Example 4 or Comparative Example 4 is applied to this molding die. The sample was blown in with an air pressure of 0.1 MPa gauge pressure and filled, and after 60 seconds, a test piece assuming a mold was formed by demolding.

  The mass of the test piece obtained by molding in this manner was measured, and the bulk specific gravity was calculated from the mass and the volume. The bending strength was also measured in accordance with JIS K 6910. These results are shown in Table 5.

As seen in Table 5, in the case of Reference Example 4 , the bending strength does not decrease much more than that of Comparative Example 4, and by containing silicon carbide in the binder layer of the binder coated refractory. It was confirmed that there was no problem in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Reference Example 4 or Comparative Example 4 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 5 )
A mixture of dextrin and silicon carbide is prepared by adding 200 g of dextrin and 30 g of citric acid as a hardener to 150 g of water, adding silicon carbide powder in the amount shown in Table 6, and stirring to disperse or dissolve. did. Then, 10 kg of ACI silica sand preheated to 125 ° C. was charged in a whirl mixer, this mixed solution was added and mixed, and the mixture was mixed until the lumps of sand particles were broken. Next, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to give 2.0% by mass of dextrin based on silica sand as shown in Table 6. Binder coated refractories ( Reference Examples 5-1 to 5-4) in which the surface of silica sand was coated with a solid caking agent layer containing a large amount of silicon carbide powder were obtained.

(Comparative example 5)
A binder coated refractory was obtained in the same manner as in Reference Example 5 except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 5 and Comparative Example 5 prepared as described above, test pieces were formed on the assumption of mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 5 or Comparative Example 5 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa, which was prepared in the following manner, was supplied at a flow rate of 60 kg / h, and the superheated steam was bubbled into the molding die for 60 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The bending strength of the test piece obtained by molding in this manner was measured in accordance with JIS K 6910. In addition, another test piece was placed in a heating dryer previously set at 250 ° C. and heat treated for 60 minutes, and after cooling, the bending strength was measured according to JIS K 6910. These results are shown in Table 6.

As seen in Table 6, in the case of Reference Example 5 , the bending strength does not decrease much more than that of Comparative Example 5, and by containing silicon carbide in the binder layer of the binder coated refractor. It was confirmed that there was no problem in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Reference Example 5 or Comparative Example 5 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

(Example 6)
A water-soluble inorganic compound of the type and amount shown in Table 7 and 200 g of silicon carbide powder were added to 150 g of water and stirred to obtain a mixed solution in which these were dissolved or dispersed. Then, 10 kg of ACI silica sand heated to 140 ° C. was charged into a whirl mixer, and this mixture was added thereto and kneaded for 90 seconds. After the sand grit collapses, add 10 g of calcium stearate as a lubricant and knead for 15 seconds, then remove it from the whirl mixer, aerate it and cool it down to 4.0 wt. Binder coated refractory (Example 6-1 to 6-4) in which the surface of silica sand is coated with an inorganic compound and a solid binder layer containing 2.0% by mass of silicon carbide powder Obtained.

(Comparative example 6)
Binder coated refractory (Comparative Example 6-1 to 6- 6) in the same manner as Example 6, except that the water-soluble inorganic compounds shown in Table 7 were used in the amounts shown in Table 7 and silicon carbide was not used. I got 3).

  Using the binder coated refractories of Example 6 and Comparative Example 6 prepared as described above, test pieces were formed assuming molding of a mold. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Example 6 or Comparative Example 6 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  About the test piece obtained by molding in this way, when smell was smelled immediately after demolding from the mold, no offensive odor was felt. Further, the flexural strength of this test piece was measured in accordance with JIS K 6910. The results are shown in Table 7.

  As seen in Table 7, when the water-soluble inorganic compound compares the corresponding Example 6 and Comparative Example 6, the bending strength of Example 6 is higher than that of Comparative Example 6 as seen in Table 7. It was confirmed that the strength of the mold does not become a problem by containing silicon carbide in the binder layer of the binder-coated refractory without causing a significant decrease.

  Further, using the molding die having the shape shown in FIG. 2 and having a cavity for molding a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Example 6 or Comparative Example 6 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 7 )
10 kg of ACI silica sand heated to 135 ° C. was charged into a whirl mixer, to which powder of silicon carbide was added in an amount shown in Table 8 and stirred for 30 seconds. Next, a phenolic resin shown in Table 8 is added in the amount shown in Table 8, and a solution of 30 g of hexamethylenetetramine dissolved or dispersed in 450 g of water is added as necessary, and mixed until the lump of sand grains is broken. Smelted. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to obtain 2.0% by mass of phenolic resin relative to silica sand, as shown in Table 1. Binder coated refractories ( Reference Examples 7-1 to 7-5) in which the surface of silica sand was coated with a solid binder layer containing silicon carbide powder of the following.

(Comparative example 7)
A binder coated refractory was obtained in the same manner as in Reference Example 7 except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 7 and Comparative Example 7 prepared as described above, test pieces were formed assuming mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 7 or Comparative Example 7 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The flexural strength of this test piece was measured in accordance with JACT test method SM-1. The results are shown in Table 8.

As seen in Table 8, although the bending strength of Reference Example 7 is slightly lower than Comparative Example 7, no significant difference is found, and silicon carbide is contained in the binder layer of the binder coated refractory. It was confirmed that no problem occurs in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Reference Example 7 or Comparative Example 7 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 8 )
10 kg of ACI silica sand preheated to 125 ° C. was charged into a whirl mixer, and powder of silicon carbide was further added in an amount shown in Table 9 and stirred for 30 seconds. Next, a solution obtained by adding 200 g of dextrin and 30 g of citric acid as a curing agent to 150 g of water and dispersing or dissolving it was added and mixed, and the mixture was mixed until the lumps of sand particles were broken. Next, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to give 2.0% by mass of dextrin based on silica sand as shown in Table 9. A binder coated refractory ( Reference Examples 8-1 to 8-4) in which the surface of silica sand was coated with a solid binder layer containing a large amount of silicon carbide powder was obtained.

(Comparative example 8)
A binder coated refractory was obtained in the same manner as in Reference Example 8 , except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 8 and Comparative Example 8 prepared as described above, test pieces were formed assuming molding of a mold. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 8 or Comparative Example 8 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa, which was prepared in the following manner, was supplied at a flow rate of 60 kg / h, and the superheated steam was bubbled into the molding die for 60 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The bending strength of the test piece obtained by molding in this manner was measured in accordance with JIS K 6910. The results are shown in Table 9.

As seen in Table 9, in the case of Reference Example 8 , the bending strength does not decrease much more than that of Comparative Example 8, and by containing silicon carbide in the binder layer of the binder coated refractory. It was confirmed that there was no problem in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, in the same manner as described above, the binder coated refractory of Reference Example 8 or Comparative Example 8 is molded. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

(Example 9)
10 kg of ACI silica sand heated to 140 ° C. was charged into a whirl mixer, and powder of silicon carbide was further added in an amount shown in Table 10, and stirred for 30 seconds. Next, a water-soluble inorganic compound of the type and amount shown in Table 10 was added to 150 g of water, and a solution in which it was dissolved or dispersed was added and mixed to knead until lumps of sand grains were broken. Next, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, this is disbursed from a whirl mixer, aerated and cooled to obtain 4.0% by mass of a water-soluble inorganic compound relative to silica sand, A binder coated refractory (Examples 9-1 to 9-4) in which the surface of silica sand was coated with a solid binder layer containing 0% by mass of silicon carbide powder was obtained.

(Comparative example 9)
Binder coated refractory (Comparative Examples 9-1 to 9-) in the same manner as Example 9, except that the water-soluble inorganic compounds shown in Table 10 were used in the amounts shown in Table 10 and silicon carbide was not used. I got 3).

  Using the binder coated refractories of Example 9 and Comparative Example 9 prepared as described above, test pieces were formed assuming mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Example 9 or Comparative Example 9 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  About the test piece obtained by molding in this way, when smell was smelled immediately after demolding from the mold, no offensive odor was felt. Further, the flexural strength of this test piece was measured in accordance with JIS K 6910. The results are shown in Table 10.

  As seen in Table 10, when the water-soluble inorganic compound compares the corresponding Example 9 and Comparative Example 9, the bending strength of the Example 9 is higher than that of the Comparative Example 9 as seen in Table 10. It was confirmed that the strength of the mold does not become a problem by containing silicon carbide in the binder layer of the binder-coated refractory without causing a significant decrease.

  Further, using the mold having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Example 9 or Comparative Example 9 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 10 )
10 kg of ACI silica sand heated to 135 ° C. is charged in a whirl mixer, and a phenolic resin is added thereto in an amount shown in Table 11, and a solution of 30 g of hexamethylenetetramine dissolved in 450 g of water is used as needed Add and knead for 30 seconds. Next, silicon carbide powder was added thereto in the amount shown in Table 1 and kneaded until the lump of sand grains was broken. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to obtain 2.0% by mass of phenolic resin relative to silica sand, as shown in Table 11. Binder coated refractory ( Reference Examples 10-1 to 10-5) in which the surface of silica sand is coated with a solid binder layer containing silicon carbide powder of the following.

(Comparative example 10)
A binder coated refractory was obtained in the same manner as in Reference Example 10 except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 10 and Comparative Example 10 prepared as described above, test pieces were formed assuming mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 10 or Comparative Example 10 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The flexural strength of this test piece was measured in accordance with JACT test method SM-1. The results are shown in Table 11.

As seen in Table 11, although the bending strength of Reference Example 10 is slightly lower than Comparative Example 10, no significant difference is observed, and silicon carbide is contained in the binder layer of the binder coated refractory. It was confirmed that no problem occurs in the strength as a mold.

Further, using the mold having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the caking agent coated refractories of Reference Example 10 and Comparative Example 10 are formed in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

( Reference Example 11 )
10 kg of ACI silica sand heated to 125 ° C. was charged in a whirl mixer, and a solution obtained by adding 200 g of dextrin and 30 g of citric acid as its curing agent to 150 g of water was added and dispersed for 30 seconds. To this was then added silicon carbide powder in the amounts shown in Table 12 and kneaded until the mass of sand grains collapsed. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from the whirl mixer, aerated and cooled to obtain 2.0% by mass of phenolic resin relative to silica sand, and the amount shown in Table 12 Binder coated refractories ( Reference Examples 11-1 to 11-4) in which the surface of silica sand is covered with a solid binder layer containing silicon carbide powder of the following.

(Comparative example 11)
A binder coated refractory was obtained in the same manner as in Example 11 except that silicon carbide was not used.

Using the binder coated refractories of Reference Example 11 and Comparative Example 11 prepared as described above, test pieces were formed assuming mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Reference Example 11 or Comparative Example 11 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa, which was prepared in the following manner, was supplied at a flow rate of 60 kg / h, and the superheated steam was bubbled into the molding die for 60 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  The bending strength of the test piece obtained by molding in this manner was measured in accordance with JIS K 6910. The results are shown in Table 12.

As seen in Table 12, in the case of Reference Example 11 , the bending strength does not decrease much more than that of Comparative Example 11, and by containing silicon carbide in the binder layer of the binder coated refractory. It was confirmed that there was no problem in the strength as a mold.

Further, using the molding die having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Reference Example 11 or Comparative Example 11 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

(Example 12)
10 kg of ACI silica sand heated to 125 ° C. was charged in a whirl mixer, and a solution in which water-soluble inorganic compounds of the type and amount shown in Table 13 were added to 150 g of water and dissolved or dispersed was added and kneaded for 30 seconds. To this was then added silicon carbide powder in the amounts shown in Table 13 and kneaded until the mass of sand grains collapsed. Then, after adding 10 g of calcium stearate as a lubricant and kneading for 30 seconds, the mixture is discharged from a whirl mixer, aerated and cooled to obtain 4.0 mass% of a water-soluble inorganic compound with respect to silica sand, 2.0 A binder coated refractory (Examples 12-1 to 12-4) in which the surface of silica sand was coated with a solid binder layer containing silicon carbide powder in mass% was obtained.

(Comparative example 12)
Binder coated refractory (Comparative Examples 12-1 to 12-) in the same manner as Example 12, except that the water-soluble inorganic compounds shown in Table 13 were used in the amounts shown in Table 13 and silicon carbide was not used. I got 3).

  Using the binder coated refractories of Example 12 and Comparative Example 12 prepared as described above, test pieces were formed assuming mold formation. That is, a mold having a cavity size of 20 mm × 10 mm × 80 mm is used by preheating to 120 ° C., and the binder coated refractory of Example 12 and Comparative Example 12 is molded with an air pressure of 0.1 MPa. It was blown into the mold and filled. Next, a steam pipe was connected to the molding die, and saturated steam with a gauge pressure of 0.4 MPa and a temperature of 143 ° C generated by the boiler was heated with a superheated steam generator ("GE-100" manufactured by Nomura Engineering Co., Ltd.) Superheated steam at 350 ° C. and a gauge pressure of 0.45 MPa was supplied at a flow rate of 60 kg / h, and the superheated steam was ventilated in the molding die for 50 seconds. After this, by demolding, a test piece assuming a mold was obtained.

  About the test piece obtained by molding in this way, when smell was smelled immediately after demolding from the mold, no offensive odor was felt. Further, the flexural strength of this test piece was measured in accordance with JIS K 6910. The results are shown in Table 13.

  As seen in Table 13, when comparing Example 12 and Comparative Example 12 where the water-soluble inorganic compound is corresponding, the bending strength of Example 12 is greater than that of Comparative Example 12 as seen in Table 13. It was confirmed that the strength of the mold does not become a problem by containing silicon carbide in the binder layer of the binder-coated refractory without causing a significant decrease.

  Further, using the mold having the shape shown in FIG. 2 and having a cavity for measuring a mold having a diameter of 109 mm and a height of 74 mm, the binder coated refractory of Example 12 or Comparative Example 12 is molded in the same manner as above. By doing this, a mold (core) for casting test was formed. Then, the mold was placed in a drier set at 200 ° C., heat-treated for 60 minutes, and then subjected to a casting test. The casting test will be described later.

A casting test was conducted using the mold for casting test prepared in the above-mentioned Examples , Reference Examples and Comparative Examples as a core. That is, a mold was set as a core in a green main mold, and a melt of cast iron (corresponding to FC 200) having a casting temperature of 1250 to 1300 ° C. was cast therein. After cooling, the mold was vibrated to cause collapse and the mold sand (silicon sand) was removed from the casting. Then, the surface of the casting in contact with the mold (core) was visually observed to examine the presence or absence of burn-in. Moreover, it cast similarly about the molten metal of aluminum alloy (AC3A equivalent) with a casting temperature of 800-850 degreeC, and test | inspected the presence or absence of the seizure of the surface of a casting.

  The test results of burn-in are shown in Tables 14 and 15. In Tables 14 and 15, "◎" indicates that there is no sticking at all, "○" indicates that there is a slight sticking to the extent that there is no problem as casting, and "△" indicates that there is a slight sticking. Those with a large amount of burn-in were evaluated as "x".

表１４及び表１５にみられるように、各実施例のものは焼き付きが全くないか、僅かであり、塗型剤を鋳型に塗布する必要なく、鋳造することが可能であることが実証された。

As seen in Tables 14 and 15, it was demonstrated that each example had no or only slight sticking and could be cast without the need to apply a mold wash to the mold. .

1 Mold 2 Binder coated refractory

Claims (11)

A mold for caking material containing a binder and silicon carbide, the mold caking material characterized in Rukoto using only water-soluble inorganic compound as a binder. A binder coated refractory comprising a surface of a refractory aggregate coated with a binder layer comprising the binder material for a mold according to claim 1 . A caking of a caking material for a mold containing a caking agent and silicon carbide on the surface of the fireproof aggregate by blending a caking agent and a powder of silicon carbide into the fireproof aggregate and mixing them The method for producing a binder-coated refractory according to claim 2, wherein the agent layer is coated. From a caking material for a mold containing a binder and silicon carbide on the surface of the refractory aggregate, by mixing the binder and the powder of silicon carbide and blending the mixture into the refractory aggregate. The method for producing a binder coated refractory according to claim 2, wherein the binder layer is coated. After mixing the refractory aggregate and the powder of silicon carbide, the binder is mixed and mixed with this, from the caking material for the mold containing the binder and the silicon carbide on the surface of the refractory aggregate The method for producing a binder coated refractory according to claim 2, wherein the binder layer is coated. After mixing the refractory aggregate and the caking agent, the powder of silicon carbide is mixed and mixed with this, from the caking material for the mold containing the caking agent and the silicon carbide on the surface of the refractory aggregate The method for producing a binder coated refractory according to claim 2, wherein the binder layer is coated. A caking agent coated refractory according to claim 2 is filled in a forming die, water is supplied into the forming die to make the caking agent in the binder layer tacky, and then the inside of the forming die is A method for producing a mold characterized by drying to solidify a binder. A refractory aggregate is bonded with a caking agent by filling the caking agent-coated refractory according to claim 2 into a forming die and passing steam through the forming die to solidify or harden the caking agent. A method for producing a mold characterized by the present invention. 9. A method of manufacturing a mold according to claim 8 , wherein superheated steam is used as the steam. The method for producing a mold according to claim 8 or 9 , wherein after passing steam through the mold, a drying gas is passed through the mold. A casting method comprising manufacturing a mold by the method according to any one of claims 7 to 10 , pouring the molten metal into the mold and casting using the mold without applying a mold wash.

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