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 Art

[0002] As a binder used in manufacturing a mold, various organic binders are used. Among them, alkaline phenolic resin is widely used particularly in the field of steel casting as an organic binder that can improve the quality of castings and the working environment.

[0003] However, when kneading an alkaline phenolic resin with, particularly, recycled sand of artificial sand, that is, recovered sand intended for reuse after once casting or recycled sand repeatedly used multiple times, to mold a mold, the fluidity of the mold composition significantly deteriorates compared to new sand, and it cannot be filled tightly. For this reason, there are drawbacks such as sand lumps, sintering, and intrusion in the obtained castings, which cause deterioration in the quality of the castings.

[0004] Regarding the above problems, various proposals have been made so far to improve the fluidity of casting sand. For example, when molding a mold by kneading artificial sand, which is a refractory particle, with a self-hardening water-soluble phenolic resin and a curing agent, a surfactant or a lubricant is contained in the binder for the purpose of improving the fluidity of the mold composition, as disclosed in Patent Document 1. Patent Document 2 discloses that a nonionic surfactant is contained in a curing agent for an alkaline phenolic resin for the purpose of improving the fluidity of kneaded sand and reducing the generation of bubbles in a one-component type.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in Patent Document 1, when a surfactant is added to a binder (alkali phenol resin), bubbles are generated during preparation and use, making handling inconvenient. Also, when a lubricant such as a fatty acid is added to the binder, the fatty acid is neutralized and precipitates as aggregates, making storage inconvenient. On the other hand, in Patent Document 2, when a nonionic surfactant is added to a curing agent for alkali phenol resin, the fluidity improvement effect plateaus even when a certain amount or more of the nonionic surfactant is added, making significant improvement in fluidity difficult.

[0007] The present invention provides a mold composition with excellent fluidity and a method for producing the same, while suppressing deterioration in handling properties during use and storage of mold-forming binder compositions and mold-forming hardening agents compositions. [Means for solving the problem]

[0008] The present invention This is a template composition containing fire-resistant 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) above, 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 between 1.2 and 23.)

[0009] Furthermore, the present invention relates to a mold-forming curing agent composition containing a curing agent, 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) above, 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 between 1.2 and 23.)

[0010] The present invention also provides a method for producing a mold composition, which includes refractory particles, a binder composition for mold molding containing a phenolic resin, and a step of mixing the curing agent composition for mold molding.

Effects of the Invention

[0011] According to the present invention, it is possible to provide a mold composition with excellent fluidity and a method for producing the same, while suppressing deterioration in handling properties during the use and storage of the binder composition for mold molding and the curing agent composition for mold molding.

Brief Description of the Drawings

[0012] [Figure 1] Cross-sectional view of a wooden mold for evaluating the smoothness of the mold surface [Figure 2] External photograph of a mold according to an example produced for evaluating the smoothness of the surface [Figure 3] External photograph of a mold according to a comparative example produced for evaluating the smoothness of the surface [Figure 4] Cross-sectional view of a mold or the like in the evaluation of casting quality [Figure 5] Cross-sectional view of a mold or the like in the evaluation of casting quality [Figure 6] Cross-sectional view of a mold or the like in the evaluation of casting quality [Figure 7] Cross-sectional view of a mold or the like in the evaluation of casting quality [Figure 8] External photograph of a casting according to an example in the evaluation of casting quality [Figure 9] External photograph of a casting according to a comparative example in the evaluation of casting quality

Modes for Carrying Out the Invention

[0013] <Mold Composition> The mold composition of the present embodiment 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)n-H (1) (In the general formula (1), R represents a linear or branched alkyl 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.)

[0014] The mold composition of this embodiment is excellent in fluidity. The reason why the mold composition of this embodiment exhibits such an effect is not clear, but it is considered as follows.

[0015] When a nonionic surfactant is contained in a casting composition composed of a phenol resin, a curing agent, and refractory particles, it is considered that the surface tension of the mixture of the phenol resin and the curing agent decreases, the slipperiness between the refractory particles improves, and the fluidity improves. On the other hand, when a fatty acid is contained in the casting composition, it reacts with the alkali metal in the water-soluble phenol resin to precipitate as a fatty acid salt, and a bearing effect is exhibited between the refractory particles, and it is considered that the fluidity improves. That is, the mechanism of the fluidity improvement effect obtained by containing a nonionic surfactant and the mechanism of the fluidity improvement effect obtained by containing a fatty acid are different. It is considered that the fluidity improvement effect is significantly improved by using additives with different mechanisms in combination.

[0016] 〔Refractory particles〕 As the refractory particles, conventionally known ones such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, and alumina ball sand can be used, and recycled sand obtained by recovering and regenerating used refractory particles can also be used. The refractory particles can be used alone or in combination of two or more.

[0017] From the viewpoints of improving the mold strength and economy, the average particle diameter of the refractory particles is preferably 50 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, and from the viewpoint of improving the mold strength, it is preferably 1000 μm or less, more preferably 800 μm or less, still more preferably 600 μm or less. In this specification, the average particle diameter is measured by the method described in the examples.

[0018] 〔Phenol resin〕 The aforementioned phenolic resin is generally obtained by polycondensation of a phenolic compound and an aldehyde compound under alkaline conditions. The phenolic compound can be one or more of the following: phenol, bisphenol A, bisphenol F, cresol, 3,5-xylenol, resorcinol, catechol, nonylphenol, p-tert-butylphenol, isopropenylphenol, phenylphenol, and other substituted phenols, or mixtures of various phenolic compounds such as cashew nut shell liquid. The aldehyde compound can be one or more of the following: formaldehyde, acetaldehyde, furfural, glyoxal, etc. These compounds can be used as aqueous solutions as needed. Furthermore, these may be mixed with monomers that can condense with aldehyde compounds such as urea, melamine, and cyclohexanone, monohydric aliphatic alcohol compounds such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butyl alcohol, or water-soluble polymers such as polyacrylates, cellulose derivative polymers, polyvinyl alcohol, and lignin derivatives.

[0019] Examples of alkali catalysts used in the synthesis of the phenolic resin include alkali metal hydroxides such as LiOH, NaOH, and KOH, with NaOH and KOH being particularly preferred. These alkali catalysts may also be used in mixtures.

[0020] The phenolic resin is preferably in aqueous solution form, and the solid content (solid content after drying at 105°C for 3 hours) is preferably 30% by mass or more, and 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, and more preferably 75% by mass or less, from the viewpoint of improving mold strength and workability. Furthermore, the solid content of the aqueous phenolic resin solution is preferably 30 to 80% by mass, and 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] From the viewpoint of improving mold strength, the content of the phenol resin per 100 parts by mass of the refractory particles in the mold composition 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 workability and economic efficiency, the content of the phenol resin per 100 parts by mass of the refractory particles in the mold composition 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. Furthermore, from the viewpoint of improving mold strength, improving workability and economic efficiency, the content of the phenol resin per 100 parts by mass of the refractory particles in the mold composition 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.

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

[0024] The compounds represented by the general formula (1) include compounds in which the alkyl group or alkenyl group represented by R in the general formula (1) has 8 or more carbon atoms, preferably 10 or more, and more preferably 12 or more carbon atoms, from the viewpoint of improving the fluidity of the template composition and the availability of raw materials. The compounds represented by the general formula (1) include compounds in which the alkyl group or alkenyl group represented by R in the general formula (1) has 22 or fewer carbon atoms, preferably 20 or fewer, and more preferably 18 or fewer carbon atoms, from the viewpoint of improving the fluidity of the template composition, storage stability, and the availability of raw materials. The compounds represented by the general formula (1) include compounds in which the alkyl group or alkenyl group represented by R in the general formula (1) has 8 to 22 carbon atoms, preferably 10 to 20, and more preferably 12 to 18 carbon atoms, from the viewpoint of improving the fluidity of the template composition, storage stability, and the availability of raw materials.

[0025] The compound represented by the general formula (1) includes compounds 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 viewpoint of improving the fluidity of the mold composition and the availability of raw materials. The compound represented by the general formula (1) includes compounds in which n in the general formula (1) is 23 or less, preferably 18 or less, and more preferably 13 or less, from the viewpoint of improving the fluidity of the mold composition, storage stability, and the availability of raw materials. Furthermore, the compound represented by the general formula (1) includes compounds 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, from the viewpoint of improving the fluidity of the mold composition, storage stability, and the availability of raw materials.

[0026] The content of the compound represented by general formula (1) per 100 parts by mass of the refractory particles in the mold composition 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 general formula (1) per 100 parts by mass of the refractory particles in the mold composition 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 viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency. Furthermore, the content of the compound represented by general formula (1) in the mold composition per 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 viewpoint of improving the fluidity of the mold composition, suppressing foaming, storage stability, and economic efficiency.

[0027] The content of the compound represented by general formula (1) in the mold composition, relative to 100 parts by mass of the phenol 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 phenol 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 viewpoint of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency. Furthermore, the content of the compound represented by general formula (1) in the mold composition, relative to 100 parts by mass of the phenol 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, even more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, from the viewpoint of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency.

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

[0029] The fatty acids preferably include fatty acids with a melting point of 45°C or lower, from the viewpoint of storage stability and improving the fluidity of the template composition.

[0030] Examples of the aforementioned fatty acids include linear aliphatic carboxylic acids, branched aliphatic carboxylic acids, saturated fatty acid carboxylic acids, and unsaturated aliphatic carboxylic acids. Specifically, 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 viewpoint of improving the fluidity of the template composition and the availability of raw materials, the aforementioned fatty acids preferably include one or more 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 viewpoint of improving the fluidity of the mold composition, foam suppression, 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 viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency.

[0032] The content of the fatty acid in the mold composition relative to 100 parts by mass of the phenol resin and the curing agent 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 phenol resin and the curing agent 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 viewpoint of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency. Furthermore, the content of the fatty acid in the mold composition relative to 100 parts by mass of the phenol 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, even more preferably 0.1 to 5 parts by mass, and even more preferably 0.1 to 3 parts by mass, from the viewpoint of improving the fluidity of the mold composition, anti-foaming properties, storage stability, and economic efficiency.

[0033] The ratio of the fatty acid content to the total content of the compound represented by general formula (1) and the fatty acid in the mold composition (fatty acid content / (total content of the compound represented by general formula (1) and the fatty acid)) is preferably 0.05 or higher, more preferably 0.08 or higher, and even more preferably 0.1 or higher, from the viewpoint of improving the fluidity of the mold composition. The ratio of the fatty acid content to the total content of the compound represented by general formula (1) and the fatty acid in the mold composition is preferably 0.6 or lower, more preferably 0.5 or lower, and even more preferably 0.4 or lower, from the viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency. The ratio of the fatty acid content to the total content of the compound represented by 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 viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency.

[0034] The mass ratio of the compound represented by general formula (1) to the fatty acid in the template composition (mass of the compound represented by general formula (1) / mass of the fatty acid) is preferably 0.15 or higher, more preferably 0.5 or higher, and even more preferably 0.9 or higher, from the viewpoint of improving the fluidity of the template composition. The mass ratio of the compound represented by general formula (1) to the fatty acid in the template composition is preferably 100 or less, more preferably 20 or less, and even more preferably 10 or less, from the viewpoint of improving the fluidity of the template composition, foam suppression, storage stability, and economic efficiency. The mass ratio of the compound represented by general formula (1) to the fatty acid in the template composition is preferably 0.15 to 100, more preferably 0.5 to 20, and even more preferably 0.9 to 10, from the viewpoint of improving the fluidity of the template composition, foam suppression, storage stability, and economic efficiency.

[0035] [Hardening agent] The curing agent can be used without particular limitations as long as it cures the phenolic resin, but ester compounds are preferred from the viewpoint of improving mold strength. Examples of ester compounds include lactones, 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, carbonate esters, and mixtures thereof. Specifically, examples of lactones include γ-butyrolactone, propionactone, 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, and examples of carbonate esters include ethylene carbonate and propylene carbonate. Among these, from the viewpoints of ease of controlling mold strength, availability, and economic efficiency, one or more selected from γ-butyrolactone, propionactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, triethylene glycol diacetate, dimethyl succinate, 2-ethyl dimethyl succinate, 2-methyl dimethyl glutarate, and 2-methyl dimethyl adipate are preferred. Furthermore, in gas-curable mold molding methods using ester compounds, methyl formate is preferred.

[0036] The content of the curing agent in the mold composition per 100 parts by mass of the phenol resin 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 viewpoint of improving mold strength and improving curing speed. The content of the curing agent in the mold composition per 100 parts by mass of the phenol resin 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 viewpoint of improving mold strength, improving curing speed, and economic efficiency. The content of the curing agent in the mold composition per 100 parts by mass of the phenol resin 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 viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0037] [Other ingredients] The aforementioned mold composition preferably contains resorcinol from the viewpoint of improving the working environment. Since resorcinol has the effect of capturing formaldehyde, it can reduce the amount of formaldehyde contained in the pyrolysis gas during pouring, after pouring, and when dismantling the mold.

[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 viewpoint 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 viewpoint 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 viewpoint 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 other components include solvents such as water, alcohols, ether alcohols, and glycols. Among these, from the viewpoint of the tactile feel of the mixed sand and odor suppression, one or more selected from the group consisting of water, alcohols, ether alcohols, and glycols is preferred, one or more selected from the group consisting of water, C1-C3 alcohols, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and benzyl alcohol is more preferred, one or more selected from the group consisting of methanol, ethanol, diethylene glycol, and triethylene glycol is even more preferred, and water and triethylene glycol are even more preferred.

[0040] From the viewpoint of uniformly mixing the raw materials, 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, odor suppression, and economic efficiency, 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 economic 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.

[0041] <Hardening agent composition for mold making> The mold-forming curing agent composition of this embodiment (hereinafter sometimes simply referred to as the curing agent composition) contains the curing agent, the compound represented by the general formula (1), and the fatty acid. When the compound represented by the general formula (1) or a fatty acid having 8 to 22 carbon atoms is added to a mold-forming binder composition, bubbles or aggregates are generated. However, when the compound represented by the general formula (1) and a fatty acid having 8 to 22 carbon atoms are included in the curing agent composition, it is possible to improve the fluidity of the mold composition while suppressing bubbles and aggregates.

[0042] The content of the compound represented by general formula (1) 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 viewpoint of improving the fluidity of the mold composition. The content of the compound represented by general formula (1) in the curing agent 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 viewpoint 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 curing agent 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 viewpoint 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 curing agent 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. The content of the fatty acid in the curing agent 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, from the viewpoint 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 curing agent 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 viewpoint of improving the fluidity of the mold composition, storage stability, low-temperature stability, and economic efficiency.

[0044] From the viewpoint of improving mold strength, 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 economic efficiency, 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. Furthermore, from the viewpoint of improving mold strength and economic efficiency, 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.

[0045] The ratio of the fatty acid content to the total content of the compound represented by general formula (1) and the fatty acid in the curing agent composition (fatty acid content / (total content of the compound represented by general formula (1) and the fatty acid)) is preferably 0.05 or higher, more preferably 0.08 or higher, and even more preferably 0.1 or higher, from the viewpoint of improving the fluidity of the mold composition. The ratio of the fatty acid content to the total content of the compound represented by general formula (1) and the fatty acid in the curing agent composition is preferably 0.6 or lower, more preferably 0.5 or lower, and even more preferably 0.4 or lower, from the viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency. The ratio of the fatty acid content to the total content of the compound represented by general formula (1) and the fatty acid in the curing agent 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 viewpoint of improving the fluidity of the mold composition, foam suppression, storage stability, and economic efficiency.

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

[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 viewpoint of reducing formaldehyde and improving mold strength. 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, from the viewpoint of reducing formaldehyde, improving mold strength, and economic efficiency. Furthermore, 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, from the viewpoint of reducing formaldehyde, improving mold strength, and economic efficiency.

[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 viewpoint 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 is preferred; one or more selected from the group consisting of C1-C3 alcohols, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, and benzyl alcohol is more preferred; one or more selected from the group consisting of methanol, ethanol, diethylene glycol, triethylene glycol, and benzyl alcohol is even more preferred; and triethylene glycol is even more preferred.

[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 for manufacturing the mold composition> The mold composition can be manufactured by known methods. An example of a method for manufacturing the mold composition is a method that includes a mixing step of mixing the refractory particles, the mold-forming binder composition containing the phenolic resin, and the curing agent composition.

[0051] [Binding agent composition for mold making] From the viewpoint of improving mold strength, the content of the water-soluble phenol resin in the mold-forming binder composition (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 and workability, the content of the water-soluble phenol 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. Furthermore, from the viewpoint of improving mold strength and workability, the content of the water-soluble phenol 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.

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

[0053] In the aforementioned mixing process, known methods can be used to mix each raw material. For example, methods include adding and kneading each raw material using a batch mixer, or supplying each raw material to a continuous mixer and kneading it.

[0054] <Method for manufacturing molds> In the mold manufacturing method of this embodiment, the mold can be manufactured by using the conventional mold manufacturing process as is. A preferred mold manufacturing method is one which includes a hardening step in which the mold composition is packed into a mold and the mold composition is hardened.

[0055] With regard to the embodiments described above, the present invention further discloses the following embodiments. <1> A template composition containing fire-resistant 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) above, 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 between 1.2 and 23.) <2> The content of the phenolic resin is 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the fire-resistant particles. <1> The mold composition described above. <3> The content of the phenolic resin is 0.3 parts by mass or more and 1 part by mass or less per 100 parts by mass of the fire-resistant particles. <1> or <2> The mold composition described above. <4> The content of the curing agent is 10 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the phenolic resin. <1> ~ <3> A mold composition as described in any of the following. <5> The content of the curing agent is 25 parts by mass or more and 45 parts by mass or less per 100 parts by mass of the phenolic resin. <1> ~ <4> A mold composition as described in any of the following. <6> The curing agent comprises at least one selected from γ-butyrolactone, propionactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, dimethyl succinate, triethylene glycol diacetate, dimethyl 2-ethyl succinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate. <1> ~ <5> A mold composition as described in any of the following. <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 per 100 parts by mass of the fire-resistant particles. <1> ~ <6> A mold composition as described in any of the following. <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 per 100 parts by mass of the fire-resistant particles. <1> ~ <7> A mold composition as described in any of the following. <9> The content of the compound represented by the general formula (1) relative to 100 parts by mass of the phenol resin and the curing agent is 1% by mass or more and 10% by mass or less. <1> ~ <8> A mold composition as described in any of the following. <10> The content of the compound represented by the general formula (1) relative to 100 parts by mass of the phenol resin and the curing agent is 1% by mass or more and 5% by mass or less. <1> ~ <9> A mold composition as described in any of the following. <11> The compound represented by the general formula (1) includes a compound in which R in the general formula (1) represents a linear alkyl group or alkenyl group having 10 to 20 carbon atoms, and n is a number between 1.8 and 13. <1> ~ <10> A mold composition as described in any of the following. <12> The content of the fatty acid per 100 parts by mass of the fire-resistant particles is 0.001 parts by mass or more and 0.01 parts by mass or less. <1> ~ <11> A mold composition as described in any of the following. <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 phenol resin and the curing agent. <1> ~ <12> A mold composition as described in any of the following. <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 phenol resin and the curing agent. <1> ~ <13> A mold composition as described in any of the following. <15> The aforementioned fatty acid includes a fatty acid having a melting point of 45°C or lower. <1> ~ <14> A mold composition as described in any of the following. <16> The aforementioned fatty acid comprises one or more selected from the group consisting of oleic acid, linolenic acid, and lauric acid. <1> ~ <15> A mold composition as described in any of the following. <17> The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) is 0.05 or more and 0.6 or less. <1> ~ <16> A mold composition as described in any of the following. <18> The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) is 0.1 or more and 0.4 or less. <1> ~ <17> A mold composition as described in any of the following. <19> A mold-forming curing agent composition containing 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) above, 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 between 1.2 and 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 mold-forming curing agent composition described above. <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 mold-forming curing agent composition described above. <22> The curing agent comprises at least one selected from γ-butyrolactone, propionactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, propylene carbonate, dimethyl glutarate, dimethyl adipate, dimethyl succinate, triethylene glycol diacetate, dimethyl 2-ethyl succinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate. <19> ~ <21> A mold-forming curing agent composition as described in any of the above. <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> A mold-forming curing agent composition as described in any of the above. <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> A mold-forming curing agent composition as described in any of the above. <25> The compound represented by the general formula (1) includes a compound in which R in the general formula (1) represents a linear alkyl group or alkenyl group having 10 to 20 carbon atoms, and n is a number between 1.8 and 13. <19> ~ <24> A mold-forming curing agent composition as described in any of the above. <26> The content of the aforementioned fatty acids is 0.1% by mass or more and 6% by mass or less. <19> ~ <25> A mold-forming curing agent composition as described in any of the above. <27> The content of the aforementioned fatty acids is 0.3% by mass or more and 3% by mass or less. <19> ~ <26> A mold-forming curing agent composition as described in any of the above. <28> The aforementioned fatty acid includes a fatty acid having a melting point of 45°C or lower. <19> ~ <27> A mold-forming curing agent composition as described in any of the above. <29> The aforementioned fatty acid comprises one or more selected from the group consisting of oleic acid, linolenic acid, and lauric acid. <19> ~ <28> A mold-forming curing agent composition as described in any of the above. <30> The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) is 0.05 or more and 0.6 or less. <19> ~ <29> A mold-forming curing agent composition as described in any of the above. <31> The ratio of the content of the fatty acid to the total content of the compound represented by the general formula (1) is 0.1 or more and 0.4 or less. <19> ~ <30> A mold-forming curing agent composition as described in any of the above. <32> Furthermore, it contains resorcinol, with a resorcinol content of 2% by mass or more and 10% by mass or less. <19> ~ <31> A mold-forming curing agent composition as described in any of the above. <33> Furthermore, it contains resorcinol, with a resorcinol content of 2% by mass or more and 5% by mass or less. <19> ~ <32> A mold-forming curing agent composition as described in any of the above. <34> Fire-resistant particles, a mold-forming binder composition containing phenolic resin, and <19> ~ <33> A method for producing a mold composition, comprising the step of mixing a mold-forming hardening agent composition described in any of the above. [Examples]

[0056] The following describes specific examples illustrating the present invention.

[0057] <Method for evaluating raw materials> [Weight-average molecular weight (Mw) of phenolic resin] (a) Sample preparation: Add an equal weight of deionized water to the sample, neutralize with 0.1% by weight of H2SO4, filter the resulting precipitate, wash with water, and dry. Dissolve this in tetrahydrofuran (THF) to prepare the sample for GPC. (b) Columns: Use one Guard Column TSX (manufactured by Toyo Soda Industries Co., Ltd.) HXL (6.5 mmφ × 4 cm), one TSK3000HXL (7.8 mmφ × 30 cm), and one TSK2500HXL (7.8 mmφ × 30 cm). Connect them in the order of Guard Column - 3000HXL - 2500HXL from the injection port side. (c) Standard material: Polystyrene (manufactured by Toyo Soda Industrial Co., Ltd.) (d) Eluent: THF (flow rate: 1cm 3 / min) (e) Column temperature: 25℃ (f) Detector: Ultraviolet spectrophotometer (quantification at the wavelength of the maximum peak of ultraviolet absorption of phenol) (g) Splitting method for molecular weight calculation: Time splitting (2 sec)

[0058] <Method for measuring the average particle size of fire-resistant particles> Based on the method specified in Annex 2 of JIS Z2601 (1993) "Test Methods for Foundry Sand," measurements were taken using sieves of 850, 600, 425, 300, 212, 150, 106, 75, and 53 μm, and the particle size at 50% mass accumulation was taken as the average particle size.

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

[0060] [Manufacturing of fire-resistant particles] [Manufacturing of fire-resistant particles 1] A mold composition was obtained by adding 0.26% by mass of a hardening agent (96% by mass of γ-butyrolactone, 4% by mass of resorcinol) and 1.3% by mass of a water-soluble phenolic resin composition to 100% by mass of Fremantle sand (natural silica sand). Using a mold formed with this mold composition, casting material FC250 was poured at 1400°C with an S / M ratio of 3.5 (the S / M ratio represents the ratio of the mass of the mold to the mass of the casting). The casting sand recovered from the mold after casting was mixed with Fremantle sand (natural silica sand) to a concentration of 5% by mass and regenerated 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] [Manufacturing of fire-resistant particles 2] In the production of refractory particles 1, the same manufacturing method was used except that 10% by mass of Fremantle sand (natural silica sand: average particle size 528 μm) was added to the recovered foundry sand, and refractory particles 2 with an average particle size of 407 μm were obtained.

[0062] [Manufacturing of fire-resistant particles 3] In the production of refractory particles 1, the same manufacturing method was used except that the addition of Fremantle sand (natural silica sand) to the recovered foundry sand was omitted, and refractory particles 3 with an average particle size of 348 μm were obtained.

[0063] [Manufacturing of fire-resistant particles 4] In the production of refractory particles 1, the same manufacturing method was used except that Fremantle sand was replaced with Espar #40L (manufactured by Yamakawa Sangyo Co., Ltd.: average particle size 406 μm), and refractory particles 4 with an average particle size of 396 μm were obtained.

[0064] [Manufacturing of fire-resistant particles 5] In the production of refractory particles 1, the same manufacturing method was used except that the Fremantle sand was replaced with Espar #40L (manufactured by Yamakawa Sangyo Co., Ltd.) and the amount of Espar #40L added to the recovered foundry sand was changed to 10% by mass, thereby obtaining refractory particles 5 with an average particle size of 398 μm.

[0065] [Manufacturing of fire-resistant particles 6] In the production of refractory particles 1, the same manufacturing method was used except that the Fremantle sand was replaced with Espar #40L (manufactured by Yamakawa Sangyo Co., Ltd.), and the Espar #40L was not added to the recovered foundry sand. Refractory particles 6 with 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 particle 7.

[0067] [Refractory particles 8] Espal #40L (manufactured by Yamakawa Sangyo Co., Ltd.) was used as fire-resistant particle 8.

[0068] <Manufacturing 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 the curing agent composition shown in Table 1 were added and kneaded for 40 seconds using a mixing machine (tabletop mixer KM-300, Aikousha Seisakusho Co., Ltd.). Then, 1.3 parts by mass of the binder composition shown in Table 1 were added and kneaded for 40 seconds to obtain the 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 mixing machine (tabletop mixer KM-300, Aikousha Seisakusho Co., Ltd.). Then, 1.3 parts by mass of the binder composition shown in Table 1 were added and kneaded for 40 seconds to obtain a mold composition.

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

[0071] 〔evaluation〕 The fluidity and filling properties of the mold compositions from Examples 1-1 to 1-21 and Comparative Examples 1-1 to 1-13 were evaluated using the following method. The evaluation results are shown in Tables 1 and 2.

[0072] [Liquidity Assessment] The mold composition immediately after mixing was filled into an upright cylindrical PVC pipe (φ50mm x 300mmH) until a mound formed on the top surface of the pipe. The sand on the mound was scraped off, the PVC pipe was lifted, and the width (mm) of the expanded mold composition was measured. A larger value indicates better fluidity.

[0073] [Evaluation of filling density] The mass of the mold composition in the PVC pipe was measured and calculated from the volume of the PVC pipe. A larger value indicates a higher packing density and superior 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 having a mesh opening of 3.35 mm and a wire diameter of 1.27 mm, and then filled into a wooden mold for evaluating the smoothness of the mold surface. A cross-sectional view of the wooden mold is shown in Figure 1. The mold composition was filled to a height higher than the top surface of the wooden mold, and any excess mold composition on the top surface was immediately scraped off to form the mold. After the mold composition inside the wooden mold hardened, the mold was removed from the wooden mold and the surface smoothness was observed visually. The appearance of the mold produced for Example 1-1 is shown in Figure 2, and the appearance of the mold produced for Comparative Example 1-1 is shown in Figure 3. Since the mold composition of Example 1-1 has improved fluidity and filling density compared to the mold composition of Comparative Example 1-1, the mold produced for Example 1-1 has higher surface smoothness than the mold produced for Comparative Example 1-1. Therefore, mold repair can be reduced, and the quality of the casting is also significantly improved.

[0075] [Casting Quality Evaluation] The method for evaluating the quality of the casting will be explained with reference to the drawings. First, a main mold was prepared using the mold composition of Comparative Example 1-1. Figure 4 is a schematic diagram showing the cross-section of the main mold 1, where reference numeral 11 indicates the inner wall of the main mold 1 and reference numeral 12 indicates the cross-section of the main mold 1. A mold 2, which was prepared for mold evaluation and pertains to Example 1-1 or Comparative Example 1-1, was placed inside this main mold 1. Figure 5 is a schematic diagram showing the cross-section of the main mold 1 with the mold 2 placed inside. Next, as shown in Figure 6, 17 kg of molten metal FC200 was poured into the main mold 1 with the mold 2 placed inside at 1400°C to create a casting 3. Figure 7 is a schematic diagram showing the cross-section 3 of the casting 3 and the inner wall 31 of the casting 3 (the surface that was in contact with the mold 2) after removing the main mold 1 and mold 2 from the main mold 1, mold 2, and casting 3 shown in Figure 6. Figure 8 shows a photograph of the inner wall 11 of the casting 3 according to Example 1-1, and Figure 9 shows a photograph of the inner wall 11 of the casting 3 according to Comparative Example 1-1. 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. Therefore, the surface of the inner wall 11 of the casting 3 according to Example 1-1 is smoother than the surface of the inner wall 11 of the casting 3 according to Comparative Example 1-1. As a result, the need for repairs to the casting can be reduced, and the casting quality is significantly improved.

[0076] [Table 1]

[0077] [Table 2]

[0078] The mold composition according to the examples exhibits superior fluidity and packing density compared to the mold composition according to the comparative examples. In particular, as shown in Comparative Examples 1-1 and 1-2, Comparative Examples 1-3 and 1-4, increasing the content of the compound of general formula (1) or the fatty acid does not improve fluidity and packing density. However, as shown in Examples 1-1 to 1-14, using the compound of general formula (1) and the fatty acid in combination improves fluidity and packing density.

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

[0080] [Foaming Rating] The binder composition or curing agent composition listed in the table was placed in a 50 ml transparent glass container and shaken and stirred for 10 seconds using a Yamato Scientific MT-31 touch mixer. After 1 minute, the presence or absence of air bubbles was visually checked.

[0081] [Storage stability] After storage at 25°C for 3 days, the liquid was visually inspected for separation, insoluble matter, and turbidity. The evaluation results are shown in Table 3.

[0082] [Table 3]

[0083] The curing agent compositions of Examples 2-1 to 2-12, which incorporate the compound of formula (1) and fatty acids into the curing agent composition, do not generate bubbles and exhibit superior storage stability compared to the binder composition of Comparative Example 2-1, which incorporates the compound of formula (1) and fatty acids into the binder composition.

Claims

1. A mold composition containing fire-resistant particles, a phenolic resin, a curing agent, a compound represented by the following general formula (1), and a fatty acid having 12 to 18 carbon atoms. RO-(CH ２ CH ２ O)n-H (1) (In the general formula (1) above, R represents a linear or branched alkyl or alkenyl group having 12 to 18 carbon atoms, and n represents the average number of moles added, which is between 1.8 and 13.)

2. The mold composition according to claim 1, wherein the content of the phenolic resin is 0.1 parts by mass or more and 5 parts by mass or less per 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 parts by mass or more and 0.1 parts by mass or less per 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 parts by mass or more and 0.05 parts by mass or less per 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 mold-forming curing agent composition containing a curing agent, a compound represented by the following general formula (1), and a fatty acid having 12 to 18 carbon atoms. RO-(CH ２ CH ２ O)n-H (1) (In the general formula (1) above, R represents a linear or branched alkyl or alkenyl group having 12 to 18 carbon atoms, and n represents the average number of moles added, which is between 1.8 and 13.)

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

8. The mold-forming curing agent composition 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 mold-forming curing agent composition 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 refractory particle, a mold-forming binder composition containing a phenolic resin, and a mold-forming curing agent composition according to claim 6 or 7.

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