Mold composition

Abstract

To provide a mold composition having excellent fluidity while suppressing treatability deterioration in use and preservation of a bonder composition for molding a casting mold and a curative agent composition for molding a casting mold.SOLUTION: A mold composition comprises refractory particles, a phenolic resin, a curative agent, a compound shown by the following general formula (1): RO-(CH2CH2O)n-H (1), and fatty acid having a carbon number of 8 or more to 22 or less, (in the general formula (1), R denotes a straight or branched alkyl group or an alkenyl group having a carbon number between 8 and 22 inclusive, and n denotes an average additional mol number and shows a number between 1.2 and 23 inclusive).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a mold composition. [Background technology]

[0002] Various organic binders are used in the production of casting molds, among which alkaline phenolic resins are widely used, particularly in the field of steel casting, as they can improve the quality of castings and the working environment.

[0003] However, when alkaline phenolic resins are mixed with recycled sand, particularly artificial sand, i.e., recycled sand intended for reuse after casting or recycled sand that has been reused multiple times, to form a mold, the fluidity of the mold composition is significantly worse than that of virgin sand, making it difficult to fill the mold tightly. As a result, the resulting castings suffer from defects such as sand inclusions, seizures, and intrusions, resulting in a deterioration in the quality of the castings.

[0004] In response to the above-mentioned problems, various proposals have been made to improve the fluidity of foundry sand. For example, Patent Document 1 discloses that when artificial sand, which is a refractory particle, is used to form a mold by kneading a self-hardening water-soluble phenolic resin and a hardener, a surfactant or lubricant is added to the binder in order to improve the fluidity of the mold composition, and Patent Document 2 discloses that a nonionic surfactant is added to a hardener for alkaline phenolic resin in order to improve the fluidity of the mixed sand and reduce the generation of bubbles in a one-component system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-216895 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-40896 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 1, when a surfactant is added to a binder (alkaline phenolic resin), bubbles are generated during preparation or use, making handling inconvenient. Furthermore, when a lubricant such as a fatty acid is added to a binder, the fatty acid is neutralized and precipitates as aggregates, making handling inconvenient during storage. Meanwhile, in Patent Document 2, when a nonionic surfactant is added to a curing agent for alkaline phenolic resin, the fluidity-improving effect reaches a plateau even when a certain amount or more of the nonionic surfactant is added, making it difficult to significantly improve fluidity.

[0007] The present invention provides a foundry composition that has excellent fluidity while suppressing deterioration in handleability during use and storage of a binder composition for foundry formation and a hardener composition for foundry formation, and a method for producing the same. [Means for solving the problem]

[0008] The present invention provides The mold composition contains refractory particles, a phenolic resin, a curing agent, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH2CH2O)nH (1) (In the general formula (1), R represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and n represents the average number of moles added, which is 1.2 to 23.)

[0009] The present invention also provides a hardener composition for mold making, which contains a hardener, a compound represented by the following formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH2CH2O)nH (1) (In the general formula (1), R represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and n represents the average number of moles added, which is 1.2 to 23.)

[0010] The present invention also provides a method for producing a foundry composition, which comprises the step of mixing refractory particles, a binder composition for foundry production containing a phenolic resin, and the hardener composition for foundry production. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a foundry composition having excellent fluidity while suppressing deterioration in the handleability of the binder composition for foundry formation and the hardener composition for foundry formation during use and storage, and a method for producing the same. [Brief explanation of the drawings]

[0012] [Figure 1] Cross-section of a wooden mold for evaluating the smoothness of the mold surface [Figure 2] Photograph of the appearance of a mold according to the example manufactured for evaluating surface smoothness [Figure 3] Photograph of the appearance of a comparative mold manufactured for evaluating surface smoothness [Figure 4] Cross-section of molds etc. for casting quality evaluation [Figure 5] Cross-section of molds etc. for casting quality evaluation [Figure 6] Cross-section of molds etc. for casting quality evaluation [Figure 7] Cross-section of molds etc. for casting quality evaluation [Figure 8] Appearance photograph of a casting related to an example of casting quality evaluation [Figure 9] Appearance photograph of a casting according to a comparative example in casting quality evaluation DETAILED DESCRIPTION OF THE INVENTION

[0013] <Mold composition> The mold composition of this embodiment is The composition contains refractory particles, a phenolic resin, a curing agent, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH2CH2O)nH (1) (In the general formula (1), R represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and n represents the average number of moles added, which is 1.2 to 23.)

[0014] The mold composition of this embodiment has excellent fluidity. The reason why the mold composition of this embodiment exhibits such an effect is not clear, but is thought to be as follows.

[0015] We believe that adding a nonionic surfactant to a foundry composition consisting of a phenolic resin, a hardener, and refractory particles reduces the surface tension of the phenolic resin and hardener mixture, improving the sliding properties between the refractory particles and improving fluidity. On the other hand, adding a fatty acid to a foundry composition reacts with the alkali metal in the water-soluble phenolic resin to form a fatty acid salt, which precipitates, providing a bearing effect between the refractory particles and improving fluidity. In other words, the fluidity-improving effects achieved by adding a nonionic surfactant and those achieved by adding a fatty acid are different mechanisms. We believe that the fluidity-improving effects are significantly improved by using additives with different mechanisms in combination.

[0016] [Fire-resistant particles] The refractory particles may be any of conventionally known types such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, and alumina ball sand. Also usable is recycled sand obtained by recovering and recycling used refractory particles. The refractory particles may be used alone or in combination of two or more types.

[0017] The average particle size of the refractory particles is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more from the viewpoint of improving mold strength and economic efficiency, and is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 600 μm or less from the viewpoint of improving mold strength. In this specification, the average particle size is measured by the method described in the Examples.

[0018] [Phenol resin] The phenolic resin is generally obtained by polycondensation of a phenolic compound and an aldehyde compound under alkaline conditions. Among these, the phenolic compounds include phenols such as phenol, bisphenol A, bisphenol F, cresol, 3,5-xylenol, resorcinol, catechol, nonylphenol, p-tert-butylphenol, isopropenylphenol, phenylphenol, and other substituted phenols, as well as mixtures of various phenolic compounds such as cashew nut shell liquid. Furthermore, the aldehyde compounds include formaldehyde, acetaldehyde, furfural, glyoxal, and the like, and these compounds can be used alone or in combination. These compounds can be used as aqueous solutions, if necessary. Furthermore, these may be mixed with monomers capable of condensing with aldehyde compounds such as urea, melamine, and cyclohexanone, monohydric aliphatic alcohol compounds such as methanol, ethanol, isopropyl alcohol, normal propyl alcohol, and butyl alcohol, water-soluble polymer polyacrylates, cellulose derivative polymers, polyvinyl alcohol, and lignin derivatives.

[0019] The alkali catalyst used in the synthesis of the phenolic resin includes hydroxides of alkali metals such as LiOH, NaOH, and KOH, with NaOH and KOH being particularly preferred. These alkali catalysts may also be used in combination.

[0020] The phenolic resin is preferably in the form of an aqueous solution, and the solid content (solid content after drying at 105°C for 3 hours) is preferably 30% by mass or more, more preferably 50% by mass or more, from the viewpoint of improving mold strength. The solid content of the aqueous phenolic resin solution is preferably 85% by mass or less, more preferably 75% by mass or less, from the viewpoint of improving mold strength and workability. The solid content of the aqueous phenolic resin solution is preferably 30 to 80% by mass, more preferably 50 to 75% by mass, from the viewpoint of improving mold strength and workability.

[0021] The weight average molecular weight (Mw) of the phenolic resin is preferably 500 or more, more preferably 800 or more, and even more preferably 1200 or more, from the viewpoint of improving mold strength. The weight average molecular weight (Mw) of the phenolic resin is preferably 8000 or less, more preferably 5000 or less, and even more preferably 3000 or less, from the viewpoint of improving mold strength and workability. Furthermore, the weight average molecular weight (Mw) of the phenolic resin is preferably 500 to 8000, more preferably 800 to 5000, and even more preferably 1200 to 3000, from the viewpoint of improving mold strength and workability. The weight average molecular weight of the phenolic resin is measured by the method described in the Examples.

[0022] The content of the phenolic resin in the mold composition relative to 100 parts by mass of the refractory particles is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and even more preferably 0.3 parts by mass or more, from the viewpoint of improving mold strength. The content of the phenolic resin in the mold composition relative to 100 parts by mass of the refractory particles is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 1 part by mass or less, from the viewpoint of improving workability and economic efficiency. Furthermore, the content of the phenolic resin in the mold composition relative to 100 parts by mass of the refractory particles is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 1 part by mass, from the viewpoint of improving mold strength, workability, and economic efficiency.

[0023] [Compound represented by the above general formula (1)] The compound represented by the general formula (1) includes a compound in which R in the general formula (1) represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and preferably a linear alkyl or alkenyl group having 8 to 22 carbon atoms.

[0024] From the viewpoints of improving the fluidity of the mold composition and availability of raw materials, the compound represented by the general formula (1) includes a compound in which the carbon number of the alkyl or alkenyl group represented by R in the general formula (1) is 8 or more, preferably 10 or more, and more preferably 12 or more. From the viewpoints of improving the fluidity of the mold composition, storage stability, and availability of raw materials, the compound represented by the general formula (1) includes a compound in which the carbon number of the alkyl or alkenyl group represented by R in the general formula (1) is 22 or less, preferably 20 or less, and more preferably 18 or less. From the viewpoints of improving the fluidity of the mold composition, storage stability, and availability of raw materials, the compound represented by the general formula (1) includes a compound in which the carbon number of the alkyl or alkenyl group represented by R in the general formula (1) is 8 to 22, preferably 10 to 20, and more preferably 12 to 18.

[0025] From the viewpoints of improving the fluidity of the mold composition and the availability of raw materials, the compound represented by the general formula (1) includes a compound in which n in the general formula (1) is 1.2 or more, preferably 1.5 or more, and more preferably 1.8 or more. From the viewpoints of improving the fluidity of the mold composition, the storage stability, and the availability of raw materials, the compound represented by the general formula (1) includes a compound in which n in the general formula (1) is 23 or less, preferably 18 or less, and more preferably 13 or less. Furthermore, from the viewpoints of improving the fluidity of the mold composition, the storage stability, and the availability of raw materials, the compound represented by the general formula (1) includes a compound in which n in the general formula (1) is 1.2 to 23, preferably 1.5 to 18, and more preferably 1.8 to 13.

[0026] The content of the compound represented by formula (1) in the mold composition relative to 100 parts by mass of the refractory particles is preferably 0.001 parts by mass or more, more preferably 0.003 parts by mass or more, and even more preferably 0.005 parts by mass or more, from the viewpoint of improving the fluidity of the mold composition. The content of the compound represented by formula (1) in the mold composition relative to 100 parts by mass of the refractory particles is preferably 0.1 parts by mass or less, more preferably 0.05 parts by mass or less, and even more preferably 0.02 parts by mass or less, from the viewpoints of improving the fluidity of the mold composition, foam suppression, storage stability, and economy. The content of the compound represented by the general formula (1) in the mold composition relative to 100 parts by mass of the refractory particles is preferably 0.001 to 0.1 parts by mass, more preferably 0.003 to 0.05 parts by mass, and even more preferably 0.005 to 0.02 parts by mass, from the viewpoints of improving the fluidity of the mold composition, foam suppression, storage stability, and economy.

[0027] The content of the compound represented by general formula (1) in the mold composition relative to 100 parts by mass of the phenolic resin and the curing agent is preferably 0.5 parts by mass or more, more preferably 0.75 parts by mass or more, even more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, from the viewpoint of improving the fluidity of the mold composition. The content of the compound represented by general formula (1) in the mold composition relative to 100 parts by mass of the phenolic resin and the curing agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, from the viewpoints of improving the fluidity of the mold composition, foam suppression, storage stability, and economy. The content of the compound represented by the general formula (1) in the mold composition relative to a total of 100 parts by mass of the phenolic resin and the curing agent is preferably 0.5 to 15 parts by mass, more preferably 0.75 to 15 parts by mass, even more preferably 1 to 15 parts by mass, still more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, from the viewpoints of improving the fluidity of the mold composition, foam-inhibiting properties, storage stability, and economy.

[0028] 〔fatty acid〕 The fatty acid includes a fatty acid having 8 or more carbon atoms, preferably 10 or more carbon atoms, and more preferably 12 or more carbon atoms, from the viewpoints of improving the fluidity of the mold composition and the availability of raw materials. The fatty acid includes a fatty acid having 22 or less carbon atoms, preferably 20 or less carbon atoms, and more preferably 18 or less carbon atoms, from the viewpoints of storage stability, improving the fluidity of the mold composition, and the availability of raw materials. The fatty acid also includes a fatty acid having 8 to 22 carbon atoms, preferably 10 to 20 carbon atoms, and more preferably 12 to 18 carbon atoms, from the viewpoints of storage stability, improving the fluidity of the mold composition, and the availability of raw materials.

[0029] The fatty acid preferably has a melting point of 45° C. or less, from the viewpoint of storage stability and improving the fluidity of the mold composition.

[0030] Examples of the fatty acid include linear aliphatic carboxylic acids, branched aliphatic carboxylic acids, saturated aliphatic carboxylic acids, and unsaturated aliphatic carboxylic acids, and specific examples include lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, oleic acid, linoleic acid, and linolenic acid. From the viewpoints of improving the fluidity of the mold composition and of the availability of raw materials, the fatty acid preferably includes at least one selected from the group consisting of oleic acid, linolenic acid, and lauric acid.

[0031] The content of the fatty acid per 100 parts by mass of the refractory particles in the mold composition is preferably 0.0005 parts by mass or more, more preferably 0.00075 parts by mass or more, and even more preferably 0.001 parts by mass or more, from the viewpoint of improving the fluidity of the mold composition. The content of the fatty acid per 100 parts by mass of the refractory particles in the mold composition is preferably 0.05 parts by mass or less, more preferably 0.02 parts by mass or less, and even more preferably 0.01 parts by mass or less, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency. Furthermore, the content of the fatty acid per 100 parts by mass of the refractory particles in the mold composition is preferably 0.0005 to 0.05 parts by mass, more preferably 0.00075 to 0.02 parts by mass, and even more preferably 0.001 to 0.01 parts by mass, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency.

[0032] The content of the fatty acid in the mold composition relative to 100 parts by mass of the phenolic resin and the curing agent in total is preferably 0.05 parts by mass or more, more preferably 0.075 parts by mass or more, even more preferably 0.1 parts by mass or more, even more preferably 0.25 parts by mass or more, and even more preferably 0.4 parts by mass or more, from the viewpoint of improving the fluidity of the mold composition. The content of the fatty acid in the mold composition relative to 100 parts by mass of the phenolic resin and the curing agent in total is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, from the viewpoints of improving the fluidity of the mold composition, foam-inhibiting properties, storage stability, and economy. The content of the fatty acid in the mold composition relative to a total of 100 parts by mass of the phenolic resin and the curing agent is preferably 0.05 to 7 parts by mass, more preferably 0.075 to 7 parts by mass, even more preferably 0.1 to 7 parts by mass, still more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, from the viewpoints of improving the fluidity of the mold composition, foam-inhibiting properties, storage stability, and economy.

[0033] The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid in the mold composition (the content of the fatty acid / (the total content of the compound represented by the general formula (1) and the fatty acid)) is preferably 0.05 or more, more preferably 0.08 or more, and even more preferably 0.1 or more, from the viewpoint of improving the fluidity of the mold composition. The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid in the mold composition is preferably 0.6 or less, more preferably 0.5 or less, and even more preferably 0.4 or less, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economical efficiency. The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid in the mold composition is preferably 0.05 to 0.6, more preferably 0.08 to 0.5, and even more preferably 0.1 to 0.4, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economical efficiency.

[0034] The mass ratio of the compound represented by general formula (1) to the fatty acid in the mold composition (mass of the compound represented by general formula (1) / mass of the fatty acid) is preferably 0.15 or more, more preferably 0.5 or more, and even more preferably 0.9 or more, from the viewpoint of improving the fluidity of the mold composition. The mass ratio of the compound represented by general formula (1) to the fatty acid in the mold composition is preferably 100 or less, more preferably 20 or less, and even more preferably 10 or less, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economy. The mass ratio of the compound represented by general formula (1) to the fatty acid in the mold composition is preferably 0.15 to 100, more preferably 0.5 to 20, and even more preferably 0.9 to 10, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economy.

[0035] [Curing agent] The curing agent may be any agent capable of curing the phenolic resin, but is preferably an ester compound from the viewpoint of improving mold strength. Examples of such ester compounds include lactones or organic ester compounds derived from monohydric or polyhydric alcohols having 1 to 10 carbon atoms and organic carboxylic acids having 1 to 10 carbon atoms, carbonates, and mixtures thereof. Specific examples of lactones include γ-butyrolactone, propionolactone, and ε-caprolactone. Examples of organic ester compounds include ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triethylene glycol diacetate, triethylene glycol monoacetate, ethyl acetoacetate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, triacetin, dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate. Examples of carbonate esters include ethylene carbonate and propylene carbonate. Among these, from the viewpoints of ease of controlling mold strength, availability, and economy, one or more selected from γ-butyrolactone, propionolactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, triethylene glycol diacetate, dimethyl succinate, dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate are preferred. Furthermore, in gas-curing mold-making methods using ester compounds, methyl formate is preferred.

[0036] The content of the curing agent per 100 parts by mass of the phenolic resin in the mold composition is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, from the viewpoints of improving mold strength and curing rate, respectively. The content of the curing agent per 100 parts by mass of the phenolic resin in the mold composition is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 45 parts by mass or less, from the viewpoints of improving mold strength, curing rate, and economic efficiency, respectively. The content of the curing agent per 100 parts by mass of the phenolic resin in the mold composition is preferably 10 to 70 parts by mass, more preferably 15 to 60 parts by mass, even more preferably 20 to 50 parts by mass, and even more preferably 25 to 45 parts by mass, from the viewpoints of improving mold strength, curing rate, and economic efficiency, respectively.

[0037] [Other ingredients] From the viewpoint of improving the working environment, the mold composition preferably contains resorcinol, which has the effect of capturing formaldehyde, thereby reducing the amount of formaldehyde contained in the pyrolysis gas during and after pouring and when the mold is dismantled.

[0038] The content of resorcinol in the mold composition is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and even more preferably 0.005% by mass or more, from the viewpoints of reducing formaldehyde and improving mold strength. The content of resorcinol in the mold composition is preferably 0.06% by mass or less, more preferably 0.04% by mass or less, and even more preferably 0.02% by mass or less, from the viewpoints of reducing formaldehyde, improving mold strength, and economic efficiency. Furthermore, the content of resorcinol in the mold composition is preferably 0.001 to 0.06% by mass, more preferably 0.003 to 0.04% by mass, and even more preferably 0.005 to 0.02% by mass, from the viewpoints of reducing formaldehyde, improving mold strength, and economic efficiency.

[0039] The mold composition may contain other components as long as they do not impair the effects of the present invention. Examples of such other components include solvents such as water, alcohols, ether alcohols, and glycols. Among these, from the viewpoints of the feel of the mixed sand and odor suppression, one or more selected from the group consisting of water, alcohols, ether alcohols, and glycols are preferred, one or more selected from the group consisting of water, alcohols having 1 to 3 carbon atoms, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and benzyl alcohol are more preferred, one or more selected from the group consisting of methanol, ethanol, diethylene glycol, and triethylene glycol are even more preferred, and water and triethylene glycol are even more preferred.

[0040] The content of the solvent in the mold composition is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more, from the viewpoint of uniformly mixing the raw materials. The content of the solvent in the mold composition is preferably 0.9% by mass or less, more preferably 0.8% by mass or less, and even more preferably 0.7% by mass or less, from the viewpoint of uniformly mixing the raw materials, odor suppression, and economical efficiency. The content of the solvent in the mold composition is preferably 0.01 to 0.9% by mass, more preferably 0.02 to 0.8% by mass, and even more preferably 0.03 to 0.7% by mass, from the viewpoint of uniformly mixing the raw materials, odor suppression, and economical efficiency.

[0041] <Hardening agent composition for casting> The hardener composition for foundry molding of this embodiment (hereinafter sometimes simply referred to as the hardener composition) contains the hardener, the compound represented by the general formula (1), and the fatty acid. When the compound represented by the general formula (1) or the fatty acid having 8 to 22 carbon atoms is added to a binder composition for foundry molding, bubbles and aggregates are generated. However, when the compound represented by the general formula (1) and the fatty acid having 8 to 22 carbon atoms are contained in the hardener composition, the fluidity of the mold composition can be improved while suppressing the generation of bubbles and aggregates.

[0042] The content of the compound represented by general formula (1) in the hardener composition is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, from the viewpoint of improving the fluidity of the mold composition. The content of the compound represented by general formula (1) in the hardener composition is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less, from the viewpoints of improving the fluidity of the mold composition, storage stability, low-temperature stability, and economic efficiency. Furthermore, the content of the compound represented by general formula (1) in the hardener composition is preferably 1 to 10% by mass, more preferably 1.5 to 7% by mass, and even more preferably 2 to 5% by mass, from the viewpoints of improving the fluidity of the mold composition, storage stability, low-temperature stability, and economic efficiency.

[0043] The content of the fatty acid in the hardener composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more, from the viewpoint of improving the fluidity of the mold composition. From the viewpoints of improving the fluidity of the mold composition, storage stability, low-temperature stability, and economic efficiency, the content of the fatty acid in the hardener composition is preferably 6% by mass or less, more preferably 5% by mass or less, even more preferably 4% by mass or less, and even more preferably 3% by mass or less. Furthermore, the content of the compound represented by general formula (1) in the hardener composition is preferably 0.1 to 6% by mass, more preferably 0.2 to 5% by mass, even more preferably 0.3 to 4% by mass, and even more preferably 0.3 to 3% by mass, from the viewpoints of improving the fluidity of the mold composition, storage stability, low-temperature stability, and economic efficiency.

[0044] The content of the curing agent in the curing agent composition is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 85% by mass or more, from the viewpoint of improving mold strength and from the viewpoint of economy. The content of the curing agent in the curing agent composition is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, from the viewpoint of improving mold strength and from the viewpoint of economy. Furthermore, the content of the curing agent in the curing agent composition is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, even more preferably 80 to 97% by mass, and even more preferably 85 to 97% by mass, from the viewpoint of improving mold strength and from the viewpoint of economy.

[0045] The ratio of the content of the fatty acid in the hardener composition to the total content of the compound represented by the general formula (1) and the fatty acid (the content of the fatty acid / (the total content of the compound represented by the general formula (1) and the fatty acid)) is preferably 0.05 or more, more preferably 0.08 or more, and even more preferably 0.1 or more, from the viewpoint of improving the fluidity of the mold composition. The ratio of the content of the fatty acid in the hardener composition to the total content of the compound represented by the general formula (1) and the fatty acid is preferably 0.6 or less, more preferably 0.5 or less, and even more preferably 0.4 or less, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economical efficiency. The ratio of the content of the fatty acid in the hardener composition to the total content of the compound represented by the general formula (1) and the fatty acid is preferably 0.05 to 0.6, more preferably 0.08 to 0.5, and even more preferably 0.1 to 0.4, from the viewpoints of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economical efficiency.

[0046] [Other ingredients] The curing agent composition preferably contains resorcinol from the viewpoint of improving the working environment.

[0047] The content of resorcinol in the curing agent composition is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, from the viewpoints of reducing formaldehyde and improving mold strength. From the viewpoints of reducing formaldehyde, improving mold strength, and economic efficiency, the content of resorcinol in the curing agent composition is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less. Furthermore, from the viewpoints of reducing formaldehyde, improving mold strength, and economic efficiency, the content of resorcinol in the curing agent composition is preferably 1 to 20% by mass, more preferably 1.5 to 15% by mass, even more preferably 2 to 10% by mass, and even more preferably 2 to 5% by mass.

[0048] The curing agent composition may contain other components as long as they do not impair the effects of the present invention. Examples of other components include solvents such as water, alcohols, ether alcohols, and glycols. Among these, from the viewpoints of compatibility between the curing agent and the phenolic resin, the tactile feel of the mold composition, and odor suppression, one or more selected from the group consisting of alcohols, ether alcohols, and glycols are preferred, more preferably one or more selected from the group consisting of alcohols having 1 to 3 carbon atoms, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and benzyl alcohol, even more preferably one or more selected from the group consisting of methanol, ethanol, diethylene glycol, triethylene glycol, and benzyl alcohol, and even more preferably triethylene glycol.

[0049] The content of the solvent in the curing agent composition is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of uniformly mixing the raw materials. The content of the solvent in the curing agent composition is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of uniformly mixing the raw materials, odor suppression, and economic efficiency. The content of the solvent in the curing agent composition is preferably 1 to 30% by mass, more preferably 2 to 25% by mass, and even more preferably 3 to 20% by mass, from the viewpoint of uniformly mixing the raw materials, odor suppression, and economic efficiency.

[0050] <Method of manufacturing the mold composition> The mold composition can be produced by a known method, including a mixing step of mixing the refractory particles, the binder composition for foundry molding containing the phenolic resin, and the hardener composition.

[0051] [Binder composition for mold making] The content of the water-soluble phenolic resin in the binder composition for mold formation (hereinafter sometimes simply referred to as the binder composition) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of improving mold strength. The content of the water-soluble phenolic resin in the binder composition is preferably 95% by mass or less, more preferably 80% by mass or less, even more preferably 70% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of improving mold strength and workability. Furthermore, the content of the water-soluble phenolic resin in the binder composition is preferably 10 to 95% by mass, more preferably 20 to 80% by mass, even more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass, from the viewpoint of improving mold strength and workability.

[0052] [Other ingredients] The binder composition may further contain additives such as water, a silane coupling agent, urea, a surfactant, and alcohols to the extent that the effects of this embodiment are not impaired. The binder composition preferably contains a silane coupling agent, since this can further improve the final strength of the resulting mold. Examples of silane coupling agents include γ-(2-amino)propylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane. The content of the silane coupling agent in the binder composition is preferably 0.1 to 5% by mass, more preferably 0.3 to 1% by mass, from the viewpoint of improving mold strength.

[0053] In the mixing step, the raw materials can be mixed using a known general method, for example, a method in which the raw materials are added and kneaded using a batch mixer, or a method in which the raw materials are supplied to a continuous mixer and kneaded.

[0054] <Mold manufacturing method> In the method for producing a mold according to the present embodiment, a mold can be produced by utilizing a conventional mold production process as is. A preferred method for producing a mold includes a curing step of filling a mold frame with the above-described mold composition and curing the mold composition.

[0055] In addition to the above-described embodiment, the present invention also discloses the following embodiments. <1> A mold composition comprising refractory particles, a phenolic resin, a curing agent, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH2CH2O)nH (1) (In the general formula (1), R represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and n represents the average number of moles added, which is 1.2 to 23.) <2> The content of the phenolic resin is 0.1 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the refractory particles. <1> The template composition according to claim 1. <3> The content of the phenolic resin is 0.3 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the refractory particles. <1> or <2> The template composition according to claim 1. <4> The content of the curing agent is 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the phenolic resin. <1> ~ <3> 10. The mold composition according to any one of claims 1 to 9. <5> The content of the curing agent is 25 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the phenolic resin. <1> ~ <4> 10. The mold composition according to any one of claims 1 to 9. <6> the curing agent contains at least one selected from γ-butyrolactone, propionolactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, dimethyl succinate, triethylene glycol diacetate, dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate; <1> ~ <5> 10. The mold composition according to any one of claims 1 to 9. <7> the content of the compound represented by the general formula (1) is 0.001 parts by mass or more and 0.1 parts by mass or less relative to 100 parts by mass of the refractory particles; <1> ~ <6> 10. The mold composition according to any one of claims 1 to 9. <8> The content of the compound represented by the general formula (1) is 0.005 parts by mass or more and 0.02 parts by mass or less relative to 100 parts by mass of the refractory particles. <1> ~ <7> 10. The mold composition according to any one of claims 1 to 9. <9> the content of the compound represented by the general formula (1) is 1% by mass or more and 10% by mass or less relative to 100 parts by mass of the total of the phenolic resin and the curing agent; <1> ~ <8> 10. The mold composition according to any one of claims 1 to 9. <10> the content of the compound represented by the general formula (1) is 1% by mass or more and 5% by mass or less relative to 100 parts by mass of the phenolic resin and the curing agent in total; <1> ~ <9> 10. The mold composition according to any one of claims 1 to 9. <11> The compound represented by the general formula (1) includes a compound in which R in the general formula (1) represents a linear alkyl or alkenyl group having 10 to 20 carbon atoms, and n represents a number of 1.8 to 13. <1> ~ <10> 10. The mold composition according to any one of claims 1 to 9. <12> The content of the fatty acid relative to 100 parts by mass of the refractory particles is 0.001 parts by mass or more and 0.01 parts by mass or less. <1> ~ <11> 10. The mold composition according to any one of claims 1 to 9. <13> The content of the fatty acid is 0.25 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total of the phenolic resin and the curing agent. <1> ~ <12> 10. The mold composition according to any one of claims 1 to 9. <14> the content of the fatty acid is 0.4 parts by mass or more and 3 parts by mass or less relative to 100 parts by mass of the total of the phenolic resin and the curing agent; <1> ~ <13> 10. The mold composition according to any one of claims 1 to 9. <15> The fatty acid includes a fatty acid having a melting point of 45°C or less. <1> ~ <14> 10. The mold composition according to any one of claims 1 to 9. <16> The fatty acid includes one or more selected from the group consisting of oleic acid, linoleic acid, and lauric acid. <1> ~ <15> 10. The mold composition according to any one of claims 1 to 9. <17> the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.05 or more and 0.6 or less; <1> ~ <16> 10. The mold composition according to any one of claims 1 to 9. <18> the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.1 or more and 0.4 or less; <1> ~ <17> 10. The mold composition according to any one of claims 1 to 9. <19> A hardener composition for mold making, comprising a hardener, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms: RO-(CH2CH2O)nH (1) (In the general formula (1), R represents a linear or branched alkyl or alkenyl group having 8 to 22 carbon atoms, and n represents the average number of moles added, which is 1.2 to 23.) <20> The content of the curing agent in the curing agent composition is 80% by mass or more and 97% by mass or less. <19> The hardener composition for mold making according to claim 1. <21> The content of the curing agent in the curing agent composition is 85% by mass or more and 97% by mass or less. <19> or <20> The hardener composition for mold making according to claim 1. <22> the curing agent contains at least one selected from γ-butyrolactone, propionolactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, dimethyl succinate, triethylene glycol diacetate, dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate; <19> ~ <21> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <23> The content of the compound represented by the general formula (1) is 1% by mass or more and 10% by mass or less. <19> ~ <22> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <24> The content of the compound represented by the general formula (1) is 2% by mass or more and 5% by mass or less. <19> ~ <23> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <25> The compound represented by the general formula (1) includes a compound in which R in the general formula (1) represents a linear alkyl or alkenyl group having 10 to 20 carbon atoms, and n represents a number of 1.8 to 13. <19> ~ <24> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <26> The content of the fatty acid is 0.1% by mass or more and 6% by mass or less. <19> ~ <25> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <27> The content of the fatty acid is 0.3% by mass or more and 3% by mass or less. <19> ~ <26> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <28> The fatty acid includes a fatty acid having a melting point of 45°C or less. <19> ~ <27> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <29> The fatty acid includes one or more selected from the group consisting of oleic acid, linoleic acid, and lauric acid. <19> ~ <28> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <30> the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.05 or more and 0.6 or less; <19> ~ <29> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <31> the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.1 or more and 0.4 or less; <19> ~ <30> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <32> Further, it contains resorcinol, and the content of resorcinol is 2% by mass or more and 10% by mass or less. <19> ~ <31> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <33> Further, it contains resorcinol, and the content of resorcinol is 2% by mass or more and 5% by mass or less. <19> ~ <32> 10. The hardener composition for mold making according to claim 9, wherein the hardener composition is a hardener for molding a foundry material. <34> A binder composition for foundry molding containing refractory particles and a phenolic resin, and <19> ~ <33> 10. A method for producing a mold composition, comprising the step of mixing the hardener composition for foundry molding according to any one of the above items. [Example]

[0056] Examples that specifically illustrate the present invention will be described below.

[0057] <Raw material evaluation method> [Weight average molecular weight (Mw) of phenolic resin] (a) Sample preparation: Add the same weight of ion-exchanged water to the sample, neutralize it by adding 0.1% by weight of H2SO4, filter the resulting precipitate, wash it with water, and dry it. Dissolve it in tetrahydrofuran (THF) to prepare a sample for GPC. (b) Column: Use one guard column TSX (Toyo Soda Kogyo Co., Ltd.) HXL (6.5 mm diameter x 4 cm), one TSK3000HXL (7.8 mm diameter x 30 cm), and one TSK2500HXL (7.8 mm diameter x 30 cm). Connect the guard column, 3000HXL, and 2500HXL in this order from the injection port. (c) Standard material: Polystyrene (manufactured by Toyo Soda Kogyo Co., Ltd.) (d) Eluent: THF (flow rate: 1cm 3 / min) (e) Column temperature: 25°C (f) Detector: ultraviolet spectrophotometer (quantitative at the wavelength of the maximum peak of ultraviolet absorption of phenol) (g) Division method for molecular weight calculation: Time division (2 sec)

[0058] <Method for measuring the average particle size of refractory particles> Based on the method specified in Appendix 2 of JIS Z2601 (1993) "Testing Methods for Molding Sand", measurements are taken using sieves of 850, 600, 425, 300, 212, 150, 106, 75, and 53 μm, and the particle size at 50% of the cumulative mass is taken as the average particle size.

[0059] <Production of raw materials> [Production of Binder Composition] Water and 92% by mass paraformaldehyde (2.00 times the mol of phenol) were added to an aqueous solution prepared by mixing 10 mol of phenol, 50% by mass potassium hydroxide aqueous solution (0.40 times the mol of phenol), and 50% by mass sodium hydroxide aqueous solution (0.40 times the mol of phenol). A polycondensation reaction was carried out at 80°C, and the reaction was continued until the weight-average molecular weight of the phenolic resin reached 2000. Next, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane was added to 100 parts by mass of the reaction solution to obtain a binder composition (solid content 49.1 to 50% by mass) containing a phenolic resin (weight-average molecular weight 2000).

[0060] [Production of refractory particles] [Production of refractory particles 1] A mold composition was obtained by adding 0.26% by mass of a curing agent (gamma-butyrolactone 96% by mass, resorcinol 4% by mass) and 1.3% by mass of a water-soluble phenolic resin composition to 100% by mass of Fremantle sand (natural silica sand). A mold was made using the mold composition, and FC250 casting material was poured into the mold at 1400°C with an S / M ratio of 3.5 (the S / M ratio represents the ratio of the mold mass to the casting mass). After casting, Fremantle sand (natural silica sand) was mixed with the molding sand recovered from the mold to a concentration of 5% by mass, and the mixture was reclaimed using a Nippon Chuzo M-type rotary reclaimer. The above process was repeated five times to obtain refractory particles 1 with an average particle size of 378 μm.

[0061] [Production of refractory particles 2] The same production method was used to produce refractory particles 1, except that 10 mass% of Fremantle sand (natural silica sand: average particle size 528 μm) was added to the recovered foundry sand, thereby obtaining refractory particles 2 with an average particle size of 407 μm.

[0062] [Production of refractory particles 3] Refractory particles 3 having an average particle size of 348 μm were obtained in the same manner as in the production of refractory particles 1, except that Fremantle sand (natural silica sand) was not added to the recovered foundry sand.

[0063] [Production of refractory particles 4] Refractory particles 4 having an average particle diameter of 396 μm were obtained in the same manner as in the production of refractory particles 1, except that Fremantle sand was replaced with Espearl #40L (manufactured by Yamakawa Sangyo Co., Ltd.: average particle diameter 406 μm).

[0064] [Production of Refractory Particles 5] The same production method was used to produce refractory particles 1, except that the Fremantle sand was changed to Espearl #40L (manufactured by Yamakawa Sangyo Co., Ltd.) and the amount of Espearl #40L added to the recovered foundry sand was changed to 10 mass %, thereby obtaining refractory particles 5 with an average particle size of 398 μm.

[0065] [Production of Refractory Particles 6] The same production method was used to produce refractory particles 1, except that Fremantle sand was replaced with Espal #40L (manufactured by Yamakawa Sangyo Co., Ltd.) and no Espal #40L was added to the recovered foundry sand. Refractory particles 6 having an average particle size of 390 μm were obtained.

[0066] [Fireproof particles 7] Fremantle sand (natural silica sand: average particle size 528 μm) was used as refractory particles 7.

[0067] [Refractory particles 8] Espearl #40L (manufactured by Yamakawa Sangyo Co., Ltd.) was used as the refractory particles 8.

[0068] <Production of mold composition> [Examples 1-1 to 1-13, Comparative Examples 1-1 to 1-6] 100 parts by mass of refractory particles 1 and 0.26 parts by mass of a curing agent composition shown in Table 1 were added and kneaded for 40 seconds using a kneader (tabletop mixer KM-300, Aikosha Seisakusho Co., Ltd.). Then, 1.3 parts by mass of a binder composition shown in Table 1 was added and kneaded for 40 seconds to obtain a mold composition.

[0069] Examples 1-14 100 parts by mass of refractory particles 1, 0.0091 parts by mass of the compound of general formula (1) (R: lauryl, n=5), 0.0026 parts by mass of oleic acid, and 0.26 parts by mass of the curing agent composition shown in Table 1 were added and kneaded for 40 seconds using a kneader (tabletop mixer KM-300, Aikosha Seisakusho Co., Ltd.). Thereafter, 1.3 parts by mass of the binder composition shown in Table 1 was added, and the mixture was kneaded for 40 seconds to obtain a mold composition.

[0070] [Examples 1-15 to 1-21, Comparative Examples 1-7 to 1-13] The same procedures as in Example 1-1 were carried out except that the refractory particles, binder composition, and hardener composition shown in Table 2 were used, to obtain mold compositions of Examples 1-15 to 1-21 and Comparative Examples 1-7 to 1-13.

[0071] 〔evaluation〕 The mold compositions of Examples 1-1 to 1-21 and Comparative Examples 1-1 to 1-13 were evaluated for fluidity and filling property by the following methods. The evaluation results are shown in Tables 1 and 2.

[0072] [Liquidity assessment] The mold composition immediately after mixing was filled into a cylindrical PVC pipe (φ50 mm × 300 mmH) that stood upright until a ridge formed on the top of the PVC pipe. The sand on the ridge was scraped off, the PVC cylinder was lifted, and the width (mm) of the spread mold composition was measured. The larger the value, the better the fluidity.

[0073] [Filling density evaluation] The mass of the mold composition in the PVC pipe was measured and calculated from the volume of the PVC pipe. The larger the value, the higher the packing density and the better the fluidity.

[0074] [Mold evaluation] Molds were prepared using the mold compositions of Example 1-1 and Comparative Example 1-1 by the following method. The mold composition immediately after mixing was passed through a sieve with a metal mesh of 3.35 mm openings and 1.27 mm wire diameter, and then filled into a wooden mold for evaluating the mold surface smoothness. A cross-sectional view of the wooden mold is shown in Figure 1. The mold composition was filled higher than the top surface of the wooden mold, and the excess mold composition on the top surface of the wooden mold was immediately scraped off to form the mold. After the mold composition in the wooden mold hardened, the mold was removed from the wooden mold and visually inspected for surface smoothness. The appearances of the molds prepared in Example 1-1 and Comparative Example 1-1 are shown in Figure 2 and Figure 3, respectively. The mold composition of Example 1-1 had improved fluidity and packing density compared to the mold composition of Comparative Example 1-1, and therefore the mold of Example 1-1 had higher surface smoothness than the mold of Comparative Example 1-1. This reduced mold repairs and significantly improved casting quality.

[0075] [Casting quality evaluation] The method for evaluating casting quality will be described with reference to the drawings. First, a main mold 1 was prepared using the mold composition of Comparative Example 1-1. FIG. 4 is a diagram showing a schematic cross-section of the main mold 1, with reference numeral 11 indicating the inner wall of the main mold 1 and reference numeral 12 indicating the cross-section of the main mold 1. A mold 2 according to Example 1-1 or Comparative Example 1-1, which was prepared for mold evaluation, was placed in this main mold 1. FIG. 5 is a schematic cross-sectional view of the main mold 1 with mold 2 placed therein. Next, as shown in FIG. 6, 17 kg of molten metal material FC200 was poured at 1400°C into the main mold 1 with mold 2 placed therein to produce a casting 3. FIG. 7 is a schematic diagram showing a cross-section 3 of the casting 3 and the inner wall (the surface that was in contact with mold 2) 31 of the casting 3 after the main mold 1, mold 2, and casting 3 in the state shown in FIG. 6 were removed. A photograph of the appearance of the inner wall 11 of the casting 3 produced in Example 1-1 is shown in Figure 8, and a photograph of the appearance of the inner wall 11 of the casting 3 produced in Comparative Example 1-1 is shown in Figure 9. The mold composition of Example 1-1 has improved fluidity, packing density, and mold smoothness compared to the mold composition of Comparative Example 1-1, so the surface of the inner wall 11 of the casting 3 of Example 1-1 is smoother than the surface of the inner wall 11 of the casting 3 of Comparative Example 1-1. As a result, the need for repairs on the casting can be reduced, and the quality of the casting is significantly improved.

[0076] [Table 1]

[0077] [Table 2]

[0078] The mold compositions according to the Examples have superior fluidity and packing density compared to the mold compositions according to the Comparative Examples. In particular, as shown in Comparative Examples 1-1 and 1-2, 1-3, and 1-4, the fluidity and packing density do not improve even when the content of the compound of general formula (1) or the fatty acid is increased. However, as shown in Examples 1-1 to 1-14, the fluidity and packing density are improved by using the compound of general formula (1) and the fatty acid in combination.

[0079] [Examples 2-1 to 2-12, Comparative Example 2-1] As shown in Table 3, the hardener compositions used in Examples 1-1 to 1-12 and the binder composition used in Example 1-13 were used to evaluate foaming and storage stability.

[0080] [Foaming evaluation] The binder composition or hardener composition shown in the table was placed in a 50 ml transparent glass container and shaken and stirred for 10 seconds using a Touch Mixer MT-31 manufactured by Yamato Scientific Co., Ltd. After 1 minute, the presence or absence of air bubbles was visually confirmed.

[0081] [Storage stability] After storing at 25°C for 3 days, the presence or absence of liquid separation, insoluble matter, and turbidity was visually confirmed. The evaluation results are shown in Table 3.

[0082] [Table 3]

[0083] The hardener compositions of Examples 2-1 to 2-12, in which the compound of formula (1) and a fatty acid were blended into the hardener composition, did not generate bubbles and had excellent storage stability, compared to the binder composition of Comparative Example 2-1, in which the compound of formula (1) and a fatty acid were blended into the binder composition.

Claims

1. A mold composition containing refractory particles, a phenolic resin, a curing agent, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH ２ CH ２ O)n-H (1) (In the general formula (1), R represents a linear or branched alkyl group or alkenyl group having 8 to 22 carbon atoms, n represents the average number of added moles, and represents a number of 1.2 or more and 23 or less.)

2. The mold composition according to claim 1, wherein the content of the phenolic resin is 0.1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the refractory particles.

3. The mold composition according to claim 1 or 2, wherein the content of the compound represented by the general formula (1) is 0.001 part by mass or more and 0.1 part by mass or less with respect to 100 parts by mass of the refractory particles.

4. The mold composition according to claim 1 or 2, wherein the content of the fatty acid is 0.0005 part by mass or more and 0.05 part by mass or less with respect to 100 parts by mass of the refractory particles.

5. The mold composition according to claim 1 or 2, wherein the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.05 or more and 0.6 or less.

6. A curing agent composition for mold molding containing a curing agent, a compound represented by the following general formula (1), and a fatty acid having 8 to 22 carbon atoms. RO-(CH ２ CH ２ O)n-H (1) (In the general formula (1), R represents a linear or branched alkyl group or alkenyl group having 8 to 22 carbon atoms, n represents the average number of added moles, and represents a number of 1.2 or more and 23 or less.)

7. The curing agent composition for mold molding according to claim 6, wherein the content of the fatty acid is 0.1% by mass or more and 6% by mass or less.

8. The curing agent composition for mold molding according to claim 6 or 7, wherein the content of the compound represented by the general formula (1) is 1% by mass or more and 10% by mass or less.

9. The curing agent composition for mold molding according to claim 6 or 7, wherein the ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) and the fatty acid is 0.05 or more and 0.6 or less.

10. A method for producing a mold composition, comprising the step of mixing a binder composition for mold molding containing refractory particles and a phenolic resin, and the curing agent composition for mold molding according to claim 6 or 7.

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