Composition for mold

Abstract

The present invention pertains to a composition for a mold, the composition comprising an acid-curable resin, a curing agent for curing the acid-curable resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A), and the average total number of carbon atoms, per molecule of the aromatic sulfonic acid (A), of an alkyl group of the aromatic sulfonic acid (A) contained in the curing agent is more than 2.0 and at most 11.0. The present invention can provide: a composition which is for a mold and is capable of suppressing a decrease in mold strength in a low-temperature environment without increasing a sulfur content; a curing agent composition for shaping a mold; and a mold manufacturing method.

Description

Foundry composition

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

[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 mold with the resulting mixed sand, and hardening the acid-hardening resin. Examples of acid-hardening resins include furan resins and phenolic resins, and 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, JP 2013-151019 A).

[0003] The present invention provides a foundry composition containing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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 alkyl groups per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.0: (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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.

[0004] The present invention also provides a hardener composition for mold making, containing a hardener that hardens an acid-hardening resin, wherein the hardener contains an aromatic sulfonic acid (A) represented by the general formula (A), the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by the general formula (A'), and the aromatic sulfonic acid (A) contained in the hardener has an average total number of carbon atoms in alkyl groups per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.0.

[0005] The present invention also provides a method for manufacturing a mold, comprising: a mixing step of mixing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles to obtain a foundry composition; and a curing step of filling a form with the foundry composition and curing the foundry composition, wherein the curing agent contains an aromatic sulfonic acid (A) represented by general formula (A), the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by general formula (A'), and the aromatic sulfonic acid (A) contained in the curing agent has an average total carbon number of more than 2.0 and 11.0 or less per molecule of the aromatic sulfonic acid (A). Detailed Description of the Invention

[0006] Binder compositions for foundry molding containing a furan resin are used in a variety of regions, from cold to warm climates, but have 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 foundry molding in low-temperature environments.

[0007] 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 lead to 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 suppress the decline in mold strength in low-temperature environments without increasing the sulfur content in the hardener.

[0008] 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.

[0009] The present invention provides a foundry composition containing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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 alkyl groups per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.0: (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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.

[0010] The present invention also provides a hardener composition for mold making, containing a hardener that hardens an acid-hardening resin, wherein the hardener contains an aromatic sulfonic acid (A) represented by the general formula (A), the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by the general formula (A'), and the aromatic sulfonic acid (A) contained in the hardener has an average total number of carbon atoms in alkyl groups per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.0.

[0011] The present invention also provides a method for manufacturing a mold, comprising: a mixing step of mixing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles to obtain a foundry composition; and a curing step of filling a form with the foundry composition and curing the foundry composition, wherein the curing agent contains an aromatic sulfonic acid (A) represented by general formula (A), the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by general formula (A'), and the aromatic sulfonic acid (A) contained in the curing agent has an average total carbon number of more than 2.0 and 11.0 or less per molecule of the aromatic sulfonic acid (A).

[0012] 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.

[0013] An embodiment of the present invention will be described below.

[0014] <Foundry composition> The foundry composition of this embodiment is a foundry composition containing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A), the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A') represented by the following general formula (A'), and 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 11.0 or less. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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.

[0015] 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.

[0016] [Acid-hardening 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 viewpoint of improving the hardening rate of the mold and the strength of the mold.

[0017] 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 is usable 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 consisting of furfuryl alcohol, condensates of furfuryl alcohol, urea and aldehydes, and the like.

[0018] 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.

[0019] 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, formaldehyde is preferably used, and from the viewpoint of reducing the amount of formaldehyde generated during molding, furfural, terephthalaldehyde, or hydroxymethylfurfural is preferably used.

[0020] 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.

[0021] 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.

[0022] [Curing Agent] The curing agent cures the acid-curing resin and contains the aromatic sulfonic acid (A) represented by the general formula (A).

[0023] [Aromatic Sulfonic Acid (A)] The aromatic sulfonic acid (A) is represented by the general formula (A). In the general formula (A), R 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.

[0024] 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.

[0025] The aromatic sulfonic acid (A) contains the aromatic sulfonic acid (A') represented by the general formula (A') from the viewpoint of suppressing 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 symbols 'A' and 'B' 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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. (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.)

[0030] 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.

[0031] The total number of carbon atoms, which is the sum of the carbon atoms of the alkyl groups contained 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 contained in the aromatic sulfonic acid (A"), is preferably 2 or less, from the viewpoint of suppressing a decrease in the curing rate and a decrease in mold strength in a low-temperature environment.

[0032] 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.

[0033] The average total number of carbon atoms per molecule of the aromatic sulfonic acid (A) in the alkyl group of the aromatic sulfonic acid (A) contained in the curing agent is greater than 2.0, preferably 3.0 or more, 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 per molecule of the aromatic sulfonic acid (A) in the alkyl group of the aromatic sulfonic acid (A) contained in the casting composition 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 per molecule of the aromatic sulfonic acid (A) in the alkyl group of the aromatic sulfonic acid (A) can be calculated by the following method.

[0034] [Method for Calculating 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)] 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 is determined 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 is determined from the molecular weight and content of the aromatic sulfonic acid (A") in the curing agent. Then, where the total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A') per molecule is defined as α2 and the total number of carbon atoms in the alkyl groups of the aromatic sulfonic acid (A") per molecule of the aromatic sulfonic acid (A") is defined as β2, 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 using the following formula: 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) = (α1 × α2 + β1 × β2) / (α1 + β1)

[0035] 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.

[0036] 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.

[0037] [Refractory 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. Among these, silica sand is preferred.

[0038] In the casting 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, however, it is preferable that the acid-curing resin is in the range of 0.5 to 1.5 parts by mass and the curing agent is in the range of 0.07 to 1 part by mass per 100 parts by mass of the refractory particles.

[0039] [Other Additives] The mold composition may contain a curing accelerator, a silane coupling agent, and a solvent, which will be described later.

[0040] 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.

[0041] <Method for Producing a Mold> 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-curing 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.

[0042] [Mixing Step] In the mixing step, the order in which the acid-curing resin, the curing agent, and the refractory particles are added and mixed is not particularly limited. The acid-curing resin and the curing agent may be mixed to produce a mold-making composition, and then the mold-making composition and the refractory particles may be mixed. Alternatively, the acid-curing 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-curing 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-curing 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.

[0043] [Binder Composition for Foundry Formation] The acid-curable resin can also be added in the form of a binder composition for foundry formation (hereinafter also simply referred to as a binder composition) containing the acid-curable resin.

[0044] The content of the acid-hardening 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, and is preferably 98% by mass or less, more preferably 95% by mass or less from the viewpoint of reducing viscosity.

[0045] [Curing Accelerator] The binder composition may contain a curing accelerator from the viewpoint of improving mold strength. Specific examples and amounts of the curing accelerator to be added are described in WO 2015 / 098642.

[0046] [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, if necessary, but it is not necessary to remove it during production as long as the curing reaction rate can be maintained. Furthermore, water may be further added for the purpose of adjusting the viscosity of the binder composition to an easy-to-handle setting. When water is further added for the purpose of adjusting 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 an easy-to-handle level and maintaining the curing reaction rate.

[0047] [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, as 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.

[0048] 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.

[0049] [Hardening Agent Composition for Foundry Forming] The curing agent can also be added in the form of a hardener composition for foundry forming (hereinafter also simply referred to as a hardener composition) containing the curing agent.

[0050] 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, and 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.

[0051] From the viewpoint of improving handleability, the curing agent composition may contain one or more solvents selected from the group consisting of water, alcohols, ether alcohols, and esters.

[0052] Specific examples of the alcohols include one or more selected from the group consisting of propanol, butanol, pentanol, hexanol, heptanol, octanol, and benzyl alcohol.

[0053] 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.

[0054] 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.

[0055] When the curing agent composition contains the solvent, the content of the solvent in the curing agent composition is appropriately adjusted depending on the temperature of the working environment and the temperature of the refractory particles to obtain a desired reaction rate and mold strength, 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.

[0056] 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.

[0057] 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.

[0058] In addition to the above-described embodiment, the present invention further discloses the following embodiments: <1> A foundry composition containing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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 alkyl groups per molecule of the aromatic sulfonic acid (A) of more than 2.0 and not more than 11.0. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (In the general formula (A'), R １ ', R ２ ', R ３ ', R ４ ' and R ５each independently represents hydrogen or an alkyl group, and the total number of carbon atoms in the alkyl group is 3 to 18.) <2> The foundry composition according to <1>, wherein the acid-curable 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. <3> The foundry composition according to <1> or <2>, wherein each of the alkyl groups in one molecule of the aromatic sulfonic acid (A) preferably has 1 or more and 14 or less carbon atoms. <4> The foundry composition according to any one of <1> to <3>, wherein each of the alkyl groups in one molecule of the aromatic sulfonic acid (A') preferably has 1 or more and 14 or less carbon atoms. <5> The foundry composition according to any one of <1> to <4>, wherein 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, more preferably 10 or more, and 18 or less, preferably 16 or less, and more preferably 14 or less. <6> The foundry composition according to any one of <1> to <5>, wherein 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, even more preferably 5.0% by mass or more, and preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 60% by mass or less. <7> The foundry composition according to any one of <1> to <6>, wherein the aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A") represented by the following general formula (A"): (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５each independently represents hydrogen or an alkyl group, and the total number of carbon atoms in the alkyl group is 0 to 2.) <8> The foundry composition according to <7>, wherein the number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A") is preferably 1 or more and preferably 2 or less. <9> The foundry composition according to <7> or <8>, wherein the total number of carbon atoms, which is the sum of the numbers of carbon atoms in the alkyl groups in one molecule of the aromatic sulfonic acid (A"), is preferably 0 or more, more preferably 1 or more and preferably 2 or less. <10> The foundry composition according to any of <7> to <9>, wherein 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, still more preferably 40% by mass or more, and preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less. <11> The foundry composition according to any one of <1> to <10>, 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, preferably 3.0 or more, and 11.0 or less, preferably 7.0 or less. <12> The foundry composition according to any one of <1> to <11>, wherein the curing agent contains an inorganic acid. <13> The foundry composition according to <12>, wherein the content of the inorganic acid in the curing agent is preferably 30% by mass or more, more preferably 40% by mass or more, preferably 60% by mass or less, and more preferably 50% by mass or less. <14> The foundry composition according to any one of <1> to <13>, wherein the refractory particles are one or more types selected from silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand. <15> The foundry composition according to any one of <1> to <14>, wherein the mass ratio of the refractory particles, the acid-curing resin, and the curing agent is 0.5 to 1.5 parts by mass of the acid-curing resin and 0.07 to 1 part by mass of the curing agent per 100 parts by mass of the refractory particles. <16> The foundry composition according to any one of <1> to <15>, wherein the acid-curing resin contains a furan resin. <17> The foundry composition according to any one of <1> to <16>, further containing a curing accelerator, a silane coupling agent, and a solvent.<18> A foundry composition containing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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″): (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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. (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 number of carbon atoms in the alkyl group is 0 or more and 2 or less.) <19> A hardener composition for mold making, containing a curing agent that hardens an acid-hardening resin, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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 11.0 or less. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (In the general formula (A'), R １', R ２ ', R ３ ', R ４ ' and R ５ <20> The hardener composition for mold formation according to <19>, wherein the aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A″) represented by the following general formula (A″): (In the general formula (A"), R １ ", R ２ ", R ３ ", R ４ " and R ５<22> The hardener composition for foundry molding according to any one of <19> to <21>, wherein the acid-curing resin contains a furan resin. <23> The hardener composition for foundry molding according to any one of <19> to <22>, wherein the content of the hardener in the hardener composition for foundry molding is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less. <24> The hardener composition for foundry molding according to any one of <19> to <23>, wherein the hardener contains one or more solvents selected from the group consisting of water, alcohols, ether alcohols, and esters. <25> <26> A method for producing a mold, comprising: a mixing step of mixing an acid-curing resin, a curing agent that cures the acid-curing resin, and refractory particles to obtain a foundry composition; and a curing step of filling a mold with the foundry composition and curing the foundry composition, wherein the curing agent comprises 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. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (In the general formula (A'), R １ ', R ２ ', R３ ', R ４ ' and R ５ Each of the symbols ' independently represents hydrogen or an alkyl group, and the total number of carbon atoms in the alkyl group is 3 to 18.) <27> The method for producing a template according to <26>, wherein the aromatic sulfonic acid (A) contains an aromatic sulfonic acid (A") represented by the following general formula (A"): (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 number of carbon atoms in the alkyl group is 0 to 2.) <28> The method for producing a mold according to <26> or <27>, wherein the curing agent contains an inorganic acid. <29> The method for producing a mold according to any one of <26> to <28>, wherein the acid-curing resin contains a furan resin.

[0059] <Methods for Measuring Physical Properties> [Water Content] Measurement was carried out based on the Karl Fischer method specified in JIS K 0068 using an automatic moisture measuring device (AQV-2200A, manufactured by Hiranuma Sangyo Co., Ltd.).

[0060] [Contents 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 curve: A calibration curve for furfuryl alcohol and bishydroxymethylfuran was prepared using 1,6-hexanediol as the internal standard. Column: PEG-20M Chromosorb WAW DMCS 60 / 80 mesh (GL Sciences Inc.) Column temperature: 80 to 200°C (8°C / min) Injection temperature: 210°C Detector temperature: 250°C Carrier gas: 50 mL / min (He)

[0061] [Viscosity] Using an E-type viscometer (RE-80R, manufactured by Toki Sangyo Co., Ltd.), the viscosity was measured at 25° C. using a standard rotor (cone angle 1°34′, cone radius: 24 mm) at a rotation speed of 100 rpm.

[0062] <Production Example of Binder Composition for Mold Forming> [Furan Resin] 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 were added to a three-neck flask equipped with a stirrer, a condenser, and a thermometer 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 of the reaction product after subtracting the furfuryl alcohol and water content.

[0063] [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 so as 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.

[0064] <Production Examples of Hardener Compositions for Foundry 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 foundry mold making according to Examples 1 to 13 and Comparative Examples 1 to 6, respectively.・Benzenesulfonic acid (reagent benzenesulfonic acid (anhydrous) 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 (reagent p-toluenesulfonic acid I hydrate manufactured by Fujifilm Wako Pure Chemical Corporation) ・4-ethylbenzenesulfonic acid (reagent 4-ethylbenzenesulfonic acid manufactured by Fujifilm Wako Pure Chemical Corporation) ・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-cumenesulfonic acid (Teika Tox 500 manufactured by Teika Corporation) ・Sulfuric acid (reagent 95% sulfuric acid manufactured by Fujifilm Wako Pure Chemical Corporation) ・Ethanol ・Water

[0065] <Method for producing foundry 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 benchtop mixer (KPL9000S, manufactured by Kenmix Co., Ltd.) to obtain foundry compositions according to Examples 1 to 13 and Comparative Examples 1 to 6, respectively.

[0066] [Evaluation of Mold Strength Retention] 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 the frame was 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 for 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 can be calculated using the following formula: Mold strength retention (%) = (mold strength after 24 hours at 5°C) / (mold strength after 24 hours at 25°C) x 100 The higher the value, the higher the mold strength retention. The evaluation results are shown in Table 3.

[0067]

[0068]

[0069]

Claims

1. A foundry composition containing an acid-hardening resin, a curing agent that hardens the acid-hardening resin, and refractory particles, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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 mold composition according to claim 1, wherein each alkyl group in one molecule of said aromatic sulfonic acid (A') has 1 or more and 14 or less carbon atoms.

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

4. The foundry composition according to any one of claims 1 to 3, wherein the aromatic sulfonic acid (A) comprises an aromatic sulfonic acid (A") represented by the following general formula (A"): (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. The mold composition according to claim 4, wherein the number of carbon atoms in each alkyl group in one molecule of the aromatic sulfonic acid (A") is 1 or more and 2 or less.

6. The foundry composition according to claim 4 or 5, 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 according to any one of claims 1 to 6, wherein the hardener contains an inorganic acid.

8. The foundry composition according to any one of claims 1 to 7, wherein the acid-hardening resin comprises a furan resin.

9. The foundry composition according to any one of claims 1 to 8, wherein the content of the acid-hardening 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 hardener 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-curing resin, a curing agent that cures the acid-curing resin, and refractory particles, wherein the curing agent comprises 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"): (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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. (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 curing agent that hardens an acid-hardening resin, wherein the curing agent comprises 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'): 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. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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. The hardener composition for mold making according to claim 11, wherein the aromatic sulfonic acid (A) includes an aromatic sulfonic acid (A″) represented by the following general formula (A″): (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 mold making according to claim 11 or 12, wherein the hardener contains an inorganic acid.

14. The hardener composition for mold making according to any one of claims 11 to 13, wherein the acid-hardening resin contains a furan resin.

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

16. A method for producing 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 mold composition, and a curing step of filling a form with the mold composition and hardening the mold composition, wherein the curing agent contains an aromatic sulfonic acid (A) represented by the following general formula (A): The aromatic sulfonic acid (A) contains 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 per molecule of the aromatic sulfonic acid (A) in the alkyl group of more than 2.0 and 11.0 or less. (In the general formula (A), R １ , R ２ , R ３ , R ４ and R ５ each independently represents hydrogen or an alkyl group. (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″): (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 or 17, wherein the hardener contains an inorganic acid.

19. The method for producing a mold according to any one of claims 16 to 18, wherein the acid-hardening resin contains a furan resin.

20. A 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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