Composition for mold

Abstract

To provide a composition for mold capable of suppressing decrease in mold strength under a low-temperature environment without increasing sulfur content, a curing agent composition for mold molding, and a method for manufacturing a mold.SOLUTION: A composition for mold comprises: an acid-curable resin; a curing agent for curing the acid-curable resin; and refractory particles. The curing agent contains an aromatic sulfonic acid (A), and an average total carbon number of an alkyl group possessed by the aromatic sulfonic acid (A) contained in the curing agent per one molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Acid-hardening self-hardening molds are produced by adding a binder for mold making containing an acid-hardening resin and a hardener containing phosphoric acid, organic sulfonic acid, sulfuric acid, or the like to refractory particles such as silica sand, kneading the mixture, filling a master such as a wooden pattern with the resulting mixed sand, and hardening the acid-hardening resin. Examples of acid-hardening resins include furan resins and phenolic resins. Examples of furan resins that have been used include furfuryl alcohol, furfuryl alcohol-urea-formaldehyde resins, furfuryl alcohol-formaldehyde resins, furfuryl alcohol-phenol-formaldehyde resins, and other known modified furan resins (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2013-151019 Summary of the Invention [Problem to be solved by the invention]

[0004] Binder compositions for mold formation containing a furan resin are used in a variety of regions, from cold to warm climates, but they suffer from the problem of reduced mold strength in low-temperature environments (for example, below 5°C).To address this problem, it is thought that increasing the amount or concentration of the curing agent added can suppress the reduction in mold strength of the binder composition for mold formation in low-temperature environments.

[0005] However, because hardeners contain acids containing sulfur atoms, such as organic sulfonic acids and sulfuric acids, increasing the amount or concentration of hardener used can cause poor spheroidization of the casting due to SOx gases such as sulfur dioxide during casting, resulting in a decline in casting quality. Therefore, there is a need to prevent a decline in mold strength in low-temperature environments without increasing the sulfur content in the hardener.

[0006] The present invention provides a foundry composition, a hardener composition for mold making, and a method for producing a mold that can suppress a decrease in mold strength in a low-temperature environment without increasing the sulfur content. [Means for solving the problem]

[0007] The present invention provides A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms.

[0008] The present invention also provides A hardener composition for mold making containing a hardener that hardens an acid-hardening resin, the curing agent contains an aromatic sulfonic acid (A) represented by the general formula (A), the aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the general formula (A'), The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less.

[0009] The present invention also provides A method for manufacturing a mold, comprising: a mixing step of mixing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles to obtain a foundry composition; and a curing step of filling a mold with the foundry composition and hardening the foundry composition, the curing agent contains an aromatic sulfonic acid (A) represented by the general formula (A), the aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the general formula (A'), The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a foundry composition, a hardener composition for mold making, and a method for producing a mold, which can suppress a decrease in mold strength in a low-temperature environment without increasing the sulfur content. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Mold composition> The mold composition of the present embodiment is A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms.

[0012] The foundry composition of this embodiment can suppress a decrease in mold strength in a low-temperature environment without increasing the sulfur content. Although the reason why the foundry composition of this embodiment exhibits such an effect is not clear, it is thought that the aromatic sulfonic acid (A') contained in the foundry composition of this embodiment is more hydrophobic than xylene sulfonic acid, which has conventionally been used as a curing agent for acid-curing resins for mold production, and therefore the curing rate of the acid-curing resin is accelerated, thereby suppressing a decrease in mold strength due to a decrease in the curing rate in a low-temperature environment.

[0013] [Acid-curable resin] The acid-hardening resin may be any known resin. Examples of the acid-hardening resin include one or more selected from the group consisting of furan resin, condensates of melamine and aldehydes, and condensates of urea and aldehydes. The acid-hardening resin preferably contains a furan resin, from the viewpoints of improving the hardening rate of the mold and improving the strength of the mold.

[0014] The furan resin is obtained by polymerizing a monomer composition containing furfuryl alcohol, and can be used without any particular limitation as long as it can be used as a binder for mold making. Examples of the furan resin include one or more selected from the group consisting of furfuryl alcohol, condensates of furfuryl alcohol, condensates of furfuryl alcohol and aldehydes, condensates of furfuryl alcohol and urea, condensates of furfuryl alcohol, phenols and aldehydes, condensates of furfuryl alcohol, melamine and aldehydes, and condensates of furfuryl alcohol, urea and aldehydes (urea-modified furan resin), as well as co-condensates of two or more selected from the group.

[0015] From the viewpoint of improving the mold curing rate and mold strength, the furan resin is preferably one or more selected from the group consisting of furfuryl alcohol, condensates of furfuryl alcohol and aldehydes, condensates of furfuryl alcohol and urea, condensates of furfuryl alcohol, phenols and aldehydes, condensates of furfuryl alcohol, melamine and aldehydes, and condensates of furfuryl alcohol, urea and aldehydes, as well as one or more selected from the group consisting of co-condensates of two or more selected from the above group. From the viewpoint of the global environment, furfuryl alcohol is preferably furfuryl alcohol produced from plants, which are non-petroleum resources.

[0016] Examples of the aldehydes include formaldehyde, acetaldehyde, glyoxal, furfural, terephthalaldehyde, hydroxymethylfurfural, etc., and one or more of these can be used as appropriate. From the viewpoint of improving mold strength, it is preferable to use formaldehyde, and from the viewpoint of reducing the amount of formaldehyde generated during molding, it is preferable to use furfural, terephthalaldehyde, or hydroxymethylfurfural.

[0017] Examples of the phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, and bisphenol F, and one or more of these can be used.

[0018] The furan resin can be produced by a known method. For example, when the furan resin is a urea-modified furan resin, the urea-modified furan resin can be obtained by reacting 100 parts by mass of furfuryl alcohol with 0.6 to 30 parts by mass of urea and 0.4 to 50 parts by mass of paraformaldehyde.

[0019] [Curing agent] The curing agent cures the acid-curable resin and contains the aromatic sulfonic acid (A) represented by the general formula (A).

[0020] [Aromatic sulfonic acid (A)] The aromatic sulfonic acid (A) is represented by the general formula (A). 1 , R 2 , R 3 , R 4 and R 5 and each independently represent hydrogen or an alkyl group. When the aromatic sulfonic acid (A) has an alkyl group, the alkyl group may be either a linear alkyl group or a branched alkyl group.

[0021] The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A) is preferably 1 or more and 14 or less.

[0022] The aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by the general formula (A') in order to prevent a decrease in the curing rate and a decrease in mold strength in a low-temperature environment. 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each of the ' independently represents hydrogen or an alkyl group. The alkyl group contained in the aromatic sulfonic acid (A') may be either a linear alkyl group or a branched alkyl group.

[0023] The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A') is preferably 1 or more and 14 or less.

[0024] The total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in one molecule of the aromatic sulfonic acid (A'), is, from the viewpoint of suppressing a decrease in the curing rate and a decrease in mold strength in a low-temperature environment, 3 or more, preferably 7 or more, and more preferably 10 or more. From the same viewpoint, the total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in one molecule of the aromatic sulfonic acid (A'), is 18 or less, preferably 16 or less, and more preferably 14 or less.

[0025] The content of the aromatic sulfonic acid (A') in the aromatic sulfonic acid (A) is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, from the viewpoint of suppressing a decrease in curing rate and a decrease in mold strength in a low-temperature environment. The content of the aromatic sulfonic acid (A') in the aromatic sulfonic acid (A) is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of solubility in a curing agent.

[0026] From the viewpoint of suppressing a decrease in the curing rate and a decrease in mold strength in a low-temperature environment, the aromatic sulfonic acid (A) preferably contains an aromatic sulfonic acid (A") represented by the following general formula (A"): The alkyl group contained in the aromatic sulfonic acid (A") may be either a linear alkyl group or a branched alkyl group. [ka] (In the general formula (A"), R 1 ", R 2 ", R 3 ", R 4 " and R 5 " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2.

[0027] The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A") is preferably 1 or more and 2 or less from the viewpoint of solubility in a curing agent.

[0028] The total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in one molecule of the aromatic sulfonic acid (A"), is preferably 0 or more, and more preferably 1 or more, from the viewpoint of solubility in a curing agent. The total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in the aromatic sulfonic acid (A"), is preferably 2 or less, from the viewpoint of preventing a decrease in the curing rate and a decrease in mold strength in a low-temperature environment.

[0029] The content of the aromatic sulfonic acid (A") in the aromatic sulfonic acid (A) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and still more preferably 40% by mass or more, from the viewpoint of suppressing a decrease in the curing rate and a decrease in the mold strength in a low-temperature environment. The content of the aromatic sulfonic acid (A") in the aromatic sulfonic acid (A) is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less, from the viewpoint of suppressing a decrease in the curing rate and a decrease in the mold strength in a low-temperature environment.

[0030] The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is greater than 2.0, preferably 3.0 or greater, from the viewpoint of suppressing a decrease in curing rate and a decrease in mold strength in a low-temperature environment. The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the molding composition per molecule of the aromatic sulfonic acid (A) is 11.0 or less, preferably 7.0 or less, from the viewpoint of solubility in the curing agent. The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) per molecule of the aromatic sulfonic acid (A) can be calculated by the following method.

[0031] [Method for calculating the average total number of carbon atoms in the alkyl groups contained in the aromatic sulfonic acid (A) per molecule of the aromatic sulfonic acid (A)] For example, when the curing agent contains one type each of aromatic sulfonic acid (A') and aromatic sulfonic acid (A"), the amount of substance α1 of the aromatic sulfonic acid (A') in the curing agent can be calculated from the molecular weight and content of the aromatic sulfonic acid (A') in the curing agent, and the amount of substance β1 of the aromatic sulfonic acid (A") in the curing agent can be calculated from the molecular weight and content of the aromatic sulfonic acid (A") in the curing agent. Then, where α2 is the total number of carbon atoms in the alkyl groups in one molecule of aromatic sulfonic acid (A'), and β2 is the total number of carbon atoms in the alkyl groups in one molecule of aromatic sulfonic acid (A"), the "average total number of carbon atoms in the alkyl groups in aromatic sulfonic acid (A) per molecule of said aromatic sulfonic acid (A)" can be calculated using the following formula: The average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) per molecule of the aromatic sulfonic acid (A) = (α1 × α2 + β1 × β2) / (α1 + β1)

[0032] The curing agent may contain an inorganic acid from the viewpoint of improving the final mold strength and the curing speed. Specific examples of the inorganic acid include one or more acids selected from the group consisting of hydrochloric acid, sulfuric acid, and phosphoric acid.

[0033] When the curing agent contains the inorganic acid, the content of the inorganic acid in the curing agent is preferably 30% by mass or more, more preferably 40% by mass or more, from the viewpoint of improving the final mold strength and curing speed. When the curing agent contains the inorganic acid, the content of the inorganic acid in the curing agent is preferably 60% by mass or less, more preferably 50% by mass or less, from the viewpoint of improving the final mold strength.

[0034] [Fire-resistant particles] The refractory particles may be one or more of conventionally known refractory particles such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, etc., or may be recovered or recycled used refractory particles. Of these, silica sand is preferred.

[0035] In the mold composition, the mass ratio of the refractory particles, the acid-curing resin, and the curing agent can be set as appropriate. From the viewpoint of improving the curing rate and the mold strength, the mass ratio of the acid-curing resin is preferably 0.5 to 1.5 parts by mass and the curing agent is preferably 0.07 to 1 part by mass relative to 100 parts by mass of the refractory particles.

[0036] [Other additives] The mold composition may contain a curing accelerator, a silane coupling agent, and a solvent, which will be described later.

[0037] The foundry composition is suitable for use in the production of self-hardening molds. Here, a self-hardening mold is a mold in which, when a binder composition and a hardener are mixed with sand, a polymerization reaction progresses over time, resulting in hardening of the mold. The temperature of the sand used in this process is preferably in the range of -20°C to 50°C, and more preferably 0°C to 40°C. By selecting an appropriate amount of hardener and adding it to the sand at such a temperature, the mold can be properly hardened.

[0038] <Mold manufacturing method> A mold can be produced by curing the foundry composition. A preferred method for producing a mold includes a mixing step of mixing the acid-curable resin, the curing agent, and the refractory particles to obtain the foundry composition, and a curing step of filling a mold with the foundry composition and curing the foundry composition.

[0039] [Mixing process] In the mixing step, the order in which the acid-hardening resin, the curing agent, and the refractory particles are added and mixed is not particularly limited. The acid-hardening resin and the curing agent may be mixed to prepare a mold-making composition, and then the mold-making composition and the refractory particles may be mixed. Alternatively, the acid-hardening resin, the curing agent, and the refractory particles may be added and mixed separately. However, from the viewpoints of storage stability and mold productivity, it is preferable to mix the acid-hardening resin, the curing agent, and the refractory particles to obtain the mold composition. Furthermore, from the viewpoint of improving mold strength, it is preferable to add the curing agent to the refractory particles and mix them, and then add the acid-hardening resin and mix them. Furthermore, when two or more curing agents are used, the respective curing agents may be mixed and then added, or each curing agent may be added separately.

[0040] [Binder composition for mold making] The acid-curing resin can also be added in the form of a binder composition for mold formation (hereinafter simply referred to as a binder composition) containing the acid-curing resin.

[0041] The content of the acid-curing resin in the binder composition is preferably 65% ​​by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, from the viewpoint of improving mold strength. The content of the acid-curing resin in the binder composition is preferably 98% by mass or less, more preferably 95% by mass or less, from the viewpoint of reducing viscosity.

[0042] [Curing accelerator] The binder composition may contain a hardening accelerator to improve mold strength. Specific examples and amounts of hardening accelerators are described in WO 2015 / 098642.

[0043] [water] The binder composition may further contain water. For example, when synthesizing various condensates, such as a condensate of furfuryl alcohol and aldehydes, the raw materials are used in aqueous solution form or condensation water is generated, so the condensate is usually obtained in the form of a mixture with water. When using such a condensate in a binder composition, the water may be removed by topping or the like, if necessary. However, as long as the curing reaction rate can be maintained, it is not necessary to remove the water during production. Furthermore, water may be further added to the binder composition for the purpose of adjusting the viscosity of the binder composition to an easy-to-handle setting. When water is further added to adjust the viscosity of the binder composition to an easy-to-handle setting, the water content of the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more. However, from the viewpoint of maintaining the curing reaction rate, the water content of the binder composition is preferably 30% by mass or less, more preferably 25% by mass or less. The water content of the binder composition is preferably 0.5 to 30% by mass, more preferably 1 to 25% by mass, and even more preferably 3 to 25% by mass, from the viewpoint of adjusting the viscosity of the binder composition to be easy to handle and maintaining the curing reaction rate.

[0044] [Other additives] The binder composition may further contain additives such as a silane coupling agent. For example, the binder composition preferably contains a silane coupling agent, since this can further improve the final strength of the resulting mold. Specific examples of silane coupling agents include those described in International Publication No. 2015 / 098642. From the perspective of improving mold strength, preferred silane coupling agents include aminosilanes such as N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, and 3-aminopropyltrimethoxysilane, with N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane being more preferred.

[0045] From the viewpoint of improving the final strength of the mold, the content of the silane coupling agent in the binder composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.2% by mass or more. From the same viewpoint, the content of the silane coupling agent in the binder composition is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0046] [Hardening agent composition for casting] The curing agent can also be added in the form of a hardener composition for mold making (hereinafter also simply referred to as a hardener composition) containing the curing agent.

[0047] The content of the curing agent in the curing agent composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more from the viewpoint of improving mold strength. The content of the curing agent in the curing agent composition is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less from the viewpoint of dissolving the curing agent composition.

[0048] The curing agent composition may contain one or more solvents selected from the group consisting of water, alcohols, ether alcohols, and esters, from the viewpoint of improving handleability.

[0049] Specific examples of the alcohols include one or more selected from the group consisting of propanol, butanol, pentanol, hexanol, heptanol, octanol, and benzyl alcohol.

[0050] Specific examples of the ether alcohols include one or more selected from the group consisting of ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, and ethylene glycol monophenyl ether.

[0051] Specific examples of the esters include one or more selected from the group consisting of butyl acetate, butyl benzoate, ethylene glycol monobutyl ether acetate, and diethylene glycol monobutyl ether acetate.

[0052] When the curing agent composition contains the solvent, the content of the solvent in the curing agent composition is adjusted appropriately to obtain the desired reaction rate and mold strength depending on the temperature of the working environment and the temperature of the refractory particles, but generally, from the viewpoint of dissolving the curing agent composition, the content is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. From the viewpoint of improving mold strength, the content of the solvent in the curing agent composition is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[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] In the mold manufacturing method of this embodiment, the mold can be manufactured by utilizing the conventional mold manufacturing process as is, except for the mixing step.

[0055] In addition to the above-described embodiment, the present invention also discloses the following embodiments. <1> A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): The molding composition, wherein the average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms. <2> the acid-hardening resin is at least one selected from the group consisting of a furan resin, a condensation product of melamine and an aldehyde, and a condensation product of urea and an aldehyde; <1> The mold composition according to claim 1. <3> The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A) is preferably 1 or more and 14 or less. <1> or <2> The mold composition according to claim 1. <4> The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A') is preferably 1 or more and 14 or less. <1> ~ <3> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <5> the total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in one molecule of the aromatic sulfonic acid (A'), is 3 or more, preferably 7 or more, and more preferably 10 or more, and is 18 or less, preferably 16 or less, and more preferably 14 or less; <1> ~ <4> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <6> The content of the aromatic sulfonic acid (A') in the aromatic sulfonic acid (A) is preferably 1.0% by mass or more, more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, and is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 60% by mass or less. <1> ~ <5> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <7> The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A") represented by the following general formula (A"): <1> ~ <6> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. [ka] (In the general formula (A"), R 1 ", R 2 ", R 3 ", R 4 " and R 5 " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2. <8> The number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A") is preferably 1 or more and 2 or less. <7> The mold composition according to claim 1. <9> The total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups in one molecule of the aromatic sulfonic acid (A"), is preferably 0 or more, more preferably 1 or more, and is preferably 2 or less. <7> or <8> The mold composition according to claim 1. <10> The content of the aromatic sulfonic acid (A") in the aromatic sulfonic acid (A) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and even more preferably 40% by mass or more, and is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less. <7> ~ <9> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <11> the average total number of carbon atoms in the alkyl groups contained in the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0, preferably 3.0 or more, and is 11.0 or less, preferably 7.0 or less; <1> ~ <10> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <12> The curing agent contains an inorganic acid. <1> ~ <11> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <13> The content of the inorganic acid in the curing agent is preferably 30% by mass or more, more preferably 40% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less. <12> The mold composition according to claim 1. <14> The refractory particles are one or more selected from silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand; <1> ~ <13> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <15> a mass ratio of the refractory particles, the acid-hardening resin, and the curing agent is 0.5 to 1.5 parts by mass of the acid-hardening resin and 0.07 to 1 part by mass of the curing agent relative to 100 parts by mass of the refractory particles; <1> ~ <14> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <16> The acid-hardening resin contains a furan resin. <1> ~ <15> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <17> Further containing a curing accelerator, a silane coupling agent, and a solvent, <1> ~ <16> 10. The mold composition according to claim 9, wherein the mold composition is a mixture of 10 and 11. <18> A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) comprises an aromatic sulfonic acid (A') represented by the following general formula (A') and an aromatic sulfonic acid (A") represented by the following general formula (A"): [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms. [ka] (In the general formula (A"), R 1 ", R 2 ", R 3 ", R 4 " and R 5 " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2. <19> A hardener composition for mold making containing a hardener that hardens an acid-hardening resin, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): A hardener composition for mold making, wherein the average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the hardener per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms. <20> The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A") represented by the following general formula (A"): <19> The hardener composition for mold making according to claim 1. [ka] (In the general formula (A"), R 1 ", R 2 ", R 3 ", R 4 " and R 5 " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2. <21> The curing agent contains an inorganic acid. <19> or <20> The hardener composition for mold making according to claim 1. <22> The acid-hardening resin contains a furan resin. <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 curing agent in the hardener composition for mold making is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% 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> Contains one or more solvents selected from the group consisting of water, alcohols, ether alcohols, and esters, <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 content of the solvent in the hardener composition for mold making is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. <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> A method for manufacturing a mold, comprising: a mixing step of mixing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles to obtain a foundry composition; and a curing step of filling a mold with the foundry composition and hardening the foundry composition, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): The method for producing a mold, wherein the average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. [ka] (In the general formula (A), R 1 , R 2 , R 3 , R 4 and R 5 each independently represents hydrogen or an alkyl group. [ka] (In the general formula (A'), R 1 ', R 2 ', R 3 ', R 4 ' and R 5 Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms. <27> The aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A") represented by the following general formula (A"): <26> A method for producing the mold described in [ka] (In the general formula (A"), R 1 ", R 2 ", R 3 ", R 4 " and R 5 " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2. <28> The curing agent contains an inorganic acid. <26> or <27> A method for producing the mold described in <29> The acid-hardening resin contains a furan resin. <26> ~ <28> 10. A method for producing the mold according to any one of the above. [Example]

[0056] <Methods for measuring physical properties> [Water content] Measurement was carried out using an automatic moisture measuring device (Hiranuma Sangyo Co., Ltd., AQV-2200A) based on the Karl Fischer method specified in JIS K 0068.

[0057] [Content of furfuryl alcohol and bishydroxymethylfuran] Measurement was carried out by gas chromatography analysis under the following conditions using a gas chromatograph (Shimadzu Corporation, GC-2014S). Measurement sample dilution solvent: Methanol Calibration curves: Calibration curves for furfuryl alcohol and bishydroxymethylfuran were prepared using 1,6-hexanediol as an internal standard. Column: PEG-20M Chromosorb WAW DMCS 60 / 80 mesh (GL Sciences) Column temperature: 80-200°C (8°C / min) Injection temperature: 210℃ Detector temperature: 250°C Carrier gas: 50 mL / min (He)

[0058] 〔viscosity〕 The viscosity was measured using an E-type viscometer (RE-80R, manufactured by Toki Sangyo Co., Ltd.) at 25°C with a standard rotor (cone angle 1°34', cone radius: 24 mm) at a rotation speed of 100 rpm.

[0059] <Production Example of Binder Composition for Mold Forming> [Furan resin] A three-neck flask equipped with a stirrer, condenser, and thermometer was charged with 555.5 g of furfuryl alcohol, 4.1 g of triethylamine, 5.9 g of 85% by weight aqueous phosphoric acid solution, and 157.1 g of 92% by weight paraformaldehyde at room temperature while stirring. The temperature was raised to 100°C, and a condensation reaction was carried out. When the furfuryl alcohol reached 33% by weight of the flask contents, 38.1 g of urea was added. The temperature was then raised and the reaction was carried out at 105°C for 1 hour. The reaction was then air-cooled to 70°C, and 18.7 g of urea was added. The flask contents were reacted at 70°C for 20 minutes to obtain a reaction product containing furan resin. Analysis of the resulting reaction product revealed that the furfuryl alcohol content was 19.2% by weight and the water content was 8.9% by weight. The amount of furan resin was determined as the remaining amount after subtracting the furfuryl alcohol and water content from the resulting reaction product.

[0060] [Examples 1 to 13 and Comparative Examples 1 to 6] The above-described furan resin, furfuryl alcohol, water, and a silane coupling agent (KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain the compositions shown in Table 1, thereby obtaining binder compositions for mold formation according to Examples 1 to 13 and Comparative Examples 1 to 6, respectively.

[0061] <Production Example of Hardener Composition for Mold Making> [Examples 1 to 13 and Comparative Examples 1 to 6] The compounds described below were mixed to obtain the compositions shown in Table 2, thereby obtaining hardener compositions for mold making according to Examples 1 to 13 and Comparative Examples 1 to 6, respectively. Benzene sulfonic acid (Benzene sulfonic acid (anhydrous) reagent, manufactured by Tokyo Chemical Industry Co., Ltd.) m-Xylenesulfonic acid (reagent m-xylene-4-sulfonic acid, manufactured by Tokyo Chemical Industry Co., Ltd.) p-Toluenesulfonic acid (p-Toluenesulfonic acid I hydrate, a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 4-Ethylbenzenesulfonic acid (4-ethylbenzenesulfonic acid, a reagent manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Linear dodecylbenzenesulfonic acid (reagent dodecylbenzenesulfonic acid (soft type) (mixture) manufactured by Tokyo Chemical Industry Co., Ltd.) Branched dodecylbenzenesulfonic acid (Teika Power B120, manufactured by Teika Corporation) 4-Cumene sulfonic acid (Teikatox 500, manufactured by Teika Corporation) Sulfuric acid (95% sulfuric acid, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ·ethanol ·water

[0062] <Method of manufacturing a mold composition> [Examples 1 to 13 and Comparative Examples 1 to 6] Under conditions of 5°C and 55% RH, 0.32 parts by mass of a hardener composition for foundry molding shown in Table 2 was added to 100 parts by mass of furan reclaimed silica sand (LOI%=2.7, particle size index AFS-GFN=48.3), and then 0.8 parts by mass of a binder composition for foundry molding shown in Table 1 was added. These were mixed in a tabletop mixer (KPL9000S, manufactured by Kenmix Co., Ltd.) to obtain foundry compositions according to Examples 1 to 13 and Comparative Examples 1 to 6, respectively.

[0063] [Evaluation of mold strength retention rate] Immediately after mixing, the foundry composition was filled into a cylindrical test piece frame with a diameter of 50 mm and a height of 50 mm under conditions of 5°C and 55% RH, and demolded after 2 hours. The frame was then left to stand for 24 hours under the same conditions of 5°C and 55% RH to prepare a mold test piece. The compressive strength (MPa) of the mold test piece was measured under conditions of 5°C and 55% RH using the method described in JIS Z 2604-1976, and this was designated as the "mold strength after 24 hours at 5°C." Separately, a mold test piece was prepared under conditions of 25°C and 55% RH using the same method as the "mold strength after 24 hours at 5°C," and the compressive strength (MPa) was measured and designated as the "mold strength after 24 hours at 25°C." The mold strength retention rate can be calculated using the following formula: Mold strength retention rate (%) = (mold strength after 24 hours at 5°C) / (mold strength after 24 hours at 25°C) × 100 The higher the value, the higher the mold strength retention rate. The evaluation results are shown in Table 3.

[0064] [Table 1]

[0065] [Table 2]

[0066] [Table 3]

Claims

1. A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): the aromatic sulfonic acid (A) contained in the curing agent has an average total number of carbon atoms in the alkyl group per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.

0. 【Chemical 1】 (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. 【Chemistry 2】 (In the general formula (A'), R １ ', R ２ ', R ３ ', R ４ ' and R ５ Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms.

2. 2. The molding composition according to claim 1, wherein each alkyl group in one molecule of the aromatic sulfonic acid (A') has 1 or more and 14 or less carbon atoms.

3. 2. The foundry composition according to claim 1, wherein the content of the aromatic sulfonic acid (A') in the aromatic sulfonic acid (A) is 1.0% by mass or more and 100% by mass or less.

4. 2. The foundry composition according to claim 1, wherein the aromatic sulfonic acid (A) comprises an aromatic sulfonic acid (A") represented by the following general formula (A"): 【Chemistry 3】 (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５ " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2.)

5. 5. The molding composition according to claim 4, wherein each alkyl group in one molecule of the aromatic sulfonic acid (A") has 1 or more and 2 or less carbon atoms.

6. 5. The foundry composition according to claim 4, wherein the content of the aromatic sulfonic acid (A") in the aromatic sulfonic acid (A) is 20% by mass or more and 99% by mass or less.

7. The foundry composition of claim 1 , wherein the hardener comprises an inorganic acid.

8. The foundry composition of claim 1 , wherein the acid-hardening resin comprises a furan resin.

9. 9. The foundry composition according to claim 1, wherein the content of the acid-curing resin relative to 100 parts by mass of the refractory particles is 0.5 parts by mass or more and 1.5 parts by mass or less, and the content of the curing agent relative to 100 parts by mass of the refractory particles is 0.07 parts by mass or more and 1 part by mass or less.

10. A foundry composition comprising an acid-hardening resin, a curing agent for curing the acid-hardening resin, and refractory particles, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) comprises an aromatic sulfonic acid (A') represented by the following general formula (A') and an aromatic sulfonic acid (A") represented by the following general formula (A"): 【Chemistry 4】 (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. 【Chemistry 5】 (In the general formula (A'), R １ ', R ２ ', R ３ ', R ４ ' and R ５ Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms. 【Chemistry 6】 (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５ " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2.)

11. A hardener composition for mold making containing a hardener that hardens an acid-hardening resin, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): a curing agent composition for mold formation, wherein the average total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. 【Chemistry 7】 (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. 【Chemistry 8】 (In the general formula (A'), R １ ', R ２ ', R ３ ', R ４ ' and R ５ Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms.

12. 12. The hardener composition for mold formation according to claim 11, wherein the aromatic sulfonic acid (A) comprises an aromatic sulfonic acid (A″) represented by the following general formula (A″): 【Chemistry 9】 (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５ " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2.)

13. The hardener composition for forming a foundry mold according to claim 11, wherein the hardener contains an inorganic acid.

14. The hardener composition for mold making according to claim 11 , wherein the acid-hardening resin contains a furan resin.

15. The hardener composition for molding a foundry mold according to any one of claims 11 to 14, wherein the content of the hardener in the hardener composition for molding a foundry mold is 10% by mass or more and 95% by mass or less.

16. A method for manufacturing a mold, comprising: a mixing step of mixing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles to obtain a foundry composition; and a curing step of filling a mold with the foundry composition and hardening the foundry composition, The curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), The aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A') represented by the following general formula (A'): a method for producing a mold, wherein the average total number of carbon atoms in the alkyl groups contained in the aromatic sulfonic acid (A) contained in the curing agent per molecule of the aromatic sulfonic acid (A) is more than 2.0 and 11.0 or less. 【Chemistry 10】 (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. 【Chemistry 11】 (In the general formula (A'), R １ ', R ２ ', R ３ ', R ４ ' and R ５ Each ' independently represents hydrogen or an alkyl group, and the alkyl group has a total of 3 to 18 carbon atoms.

17. The method for producing a template according to claim 16, wherein the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A") represented by the following general formula (A"): 【Chemistry 12】 (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５ " each independently represents hydrogen or an alkyl group, and the total carbon atoms of the alkyl group are 0 to 2.)

18. The method for producing a mold according to claim 16 , wherein the hardener contains an inorganic acid.

19. The method for producing a mold according to claim 16, wherein the acid-hardening resin comprises a furan resin.

20. The method for manufacturing a mold according to any one of claims 16 to 19, wherein the temperature of the refractory particles is -20°C or higher and 50°C or lower.

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