JP2018024005A - Binder composition for shaping mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder composition for shaping a mold which can further suppress deterioration of a working environment in producing the mold while realizing sufficient mold strength.SOLUTION: The binder composition for shaping a mold contains an acetal compound represented by the general formula (1) in the figure, and an acid-setting resin. (In the general formula (1), Rrepresents a hydrogen atom, hydroxy group, acetoxyalkyl group, or C1-5 alkyl group; and Rand Reach independently represent a C1-5 alkyl group, or Rand Rare bonded to form a C2-10 alkylene group.)SELECTED DRAWING: None

Description

  The present invention relates to a binder composition for mold making.

  In general, an acid-curable mold comprises a binder composition for mold making containing an acid-curable resin on a refractory particle such as silica sand, and a curing agent composition containing a sulfonic acid, sulfuric acid, phosphoric acid or the like. After these are added and kneaded, the obtained kneaded sand is filled into a mold such as a wooden mold and the acid curable resin is cured. Furan resin, phenol resin, etc. are used for acid curable resins. Furan resin includes furfuryl alcohol, furfuryl alcohol / urea / formaldehyde resin, furfuryl alcohol / formaldehyde resin, furfuryl alcohol / phenol, Formaldehyde resin and other known modified furan resins are used. Such a mold manufacturing method is capable of molding work with a high degree of freedom, and because it is excellent in the thermal properties of the mold, it can manufacture high-quality castings, so machine parts, construction machine parts, automobile parts, etc. It is widely used in casting of castings.

  An important item in casting a mold or casting a desired casting using the mold is to improve the working environment during casting. Acid curable molds use organic sulfonic acid, sulfuric acid and other acids as curing agents, and SOx such as sulfur dioxide and other pyrolytic gases during casting deteriorate the working environment. There is a fear. Therefore, it is desired to suppress the generation of SOx.

In the following Patent Document 1, a technique for reducing generation of SO ₂ gas by using 2,6-dihydroxybenzoic acid as a curing agent instead of an acid containing a sulfur atom is disclosed.

  Other important items for mold making or casting a desired casting using the mold include mold curing speed and mold strength. If the mold curing speed is slow, the productivity of the mold will decrease, and if the mold strength is insufficient, the mold will crack or the core will crack at the time of casting. May become defective.

  In the following Patent Document 2, a technique for improving the mold curing speed and the mold strength by using a binder composition for mold making containing a furfural derivative and a furfurylated urea resin is disclosed.

  In addition, since the reaction rate is affected by temperature, the concentration of the curing agent may be adjusted to obtain a desired curing rate and mold strength. For example, when the temperature of the working environment is low, especially when the refractory particles are low temperature, the reaction rate decreases, so the concentration of the curing agent in the curing agent composition is increased so that the desired curing rate and mold strength are obtained. (For example, Patent Documents 3 and 4).

  However, when an acid containing a sulfur atom is used as a curing agent, increasing the amount of the acid used to obtain a desired curing rate and mold strength under low temperature conditions will increase the amount of SOx generated, such as sulfur dioxide. The environment gets worse.

  For example, when 2,6-dihydroxybenzoic acid is used as a curing agent instead of an acid containing a sulfur atom, the amount of SOx generated can be suppressed, but the desired mold strength cannot be obtained depending on the temperature of the working environment. There is.

  For such a problem, a technique is disclosed in which a sufficient mold strength can be obtained without using an acid containing a sulfur atom as a curing agent by including a furanaldehyde compound in the binder composition (for example, Patent Document 5).

JP2013-240827A JP 2013-151019 A JP-A-62-130740 JP-A-53-129292 WO2015 / 098642 pamphlet

  However, if the binder composition contains a furanaldehyde compound, the unreacted furanaldehyde compound volatilizes when the mold is cured. There is a risk of worsening.

  The present invention provides a binder composition for mold making that can further suppress deterioration of the working environment during mold production while obtaining sufficient mold strength.

  The binder composition for mold making of the present invention contains an acetal compound represented by the following general formula (1) and an acid curable resin.

（ただし、前記一般式（１）中、Ｒ_１は水素原子、水酸基、若しくはアセトキシアルキル基、又は炭素数１〜５のアルキル基を示す。Ｒ_２及びＲ_３はそれぞれ独立に炭素数１〜５のアルキル基を示すか、又は、Ｒ_２とＲ_３は結合して炭素数２〜１０のアルキレン基を示す。）

(However, in said general formula (1), R < ₁ > shows a hydrogen atom, a hydroxyl group, an acetoxyalkyl group, or a C1-C5 alkyl group. R < ₂ > and R < ₃ > are C1-C5 each independently. R ₂ and R ₃ are bonded to each other to represent an alkylene group having 2 to 10 carbon atoms.)

  ADVANTAGE OF THE INVENTION According to this invention, the binder composition for mold making which can suppress further the deterioration of the working environment at the time of mold manufacture can be provided, obtaining sufficient mold strength.

<Binder composition for mold making>
The binder composition for mold making according to this embodiment (hereinafter, also simply referred to as a binder composition) contains an acetal compound represented by the following general formula (1) and an acid curable resin.

（ただし、前記一般式（１）中、Ｒ_１は水素原子、水酸基、若しくはアセトキシアルキル基、又は炭素数１〜５のアルキル基を示す。Ｒ_２及びＲ_３はそれぞれ独立に炭素数１〜５のアルキル基を示すか、又は、Ｒ_２とＲ_３は結合して炭素数２〜１０のアルキレン基を示す。）

(However, in said general formula (1), R < ₁ > shows a hydrogen atom, a hydroxyl group, an acetoxyalkyl group, or a C1-C5 alkyl group. R < ₂ > and R < ₃ > are C1-C5 each independently. R ₂ and R ₃ are bonded to each other to represent an alkylene group having 2 to 10 carbon atoms.)

  According to the binder composition of the present embodiment, it is possible to further suppress deterioration of the working environment during mold production while obtaining sufficient mold strength. The reason for such an effect is not clear, but is considered as follows.

  The acetal compound represented by the general formula (1) is dealcoholized by the acid in the curing agent composition for curing the acid curable resin, and furfural is generated. The rate at which furfural is produced is slower than the rate at which the furfural reacts with the acid in the acid curing agent composition and cures, and the produced furfural is sequentially cured by the curing agent composition. The amount of furfural can be suppressed. Since the acetal compound represented by the general formula (1) is used in place of the furanaldehyde compound, volatilization of the unreacted furanaldehyde compound at the time of template curing can be suppressed. According to the binder composition for molding, deterioration of the working environment at the time of mold production can be further suppressed while obtaining sufficient mold strength.

[Acetal compound represented by general formula (1)]
In General Formula (1), R ₁ represents a hydrogen atom, a hydroxyl group, an acetoxyalkyl group, or an alkyl group having 1 to 5 carbon atoms.

When R ₁ is an acetoxyalkyl group, R ₁ is preferably an acetoxymethyl group from the viewpoint of obtaining sufficient template strength.

When R ₁ is an alkyl group, the number of carbon atoms in R ₁ is preferably 1 or more from the viewpoint of obtaining sufficient template strength. When R ₁ is an alkyl group, from the viewpoint of obtaining sufficient template strength, the carbon number of R ₁ is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. In addition, when R ₁ is an alkyl group, from the viewpoint of obtaining sufficient template strength, the carbon number of R ₁ is preferably 1 to 5, more preferably 1 to 4, and still more preferably 1 to 3. R ₁ may be a linear alkyl group or a branched alkyl group.

From the viewpoint of obtaining sufficient template strength, R ₁ is preferably at least one selected from the group consisting of a hydrogen atom, a hydroxyl group, and an acetoxymethyl group, and more preferably hydrogen.

R ₂ and R ₃ each independently represent an alkyl group having 1 to 5 carbon atoms, or R ₂ and R ₃ are bonded to each other to represent an alkylene group having 2 to 10 carbon atoms. R ₂ and R ₃ are eliminated as an alcohol by the acid in the curing agent composition. The smaller the molecular weight of the desorbed alcohol, the higher the volatility and the smaller the amount remaining in the mold, which is preferable from the viewpoint of suppressing the reduction in mold strength and suppressing the decrease in the curing rate. Therefore, when R ₂ and R ₃ each represent an alkyl group, the carbon number of R ₂ and R ₃ is each independently 1 or more, preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. . Also, _{R 2} and _{R 3,} if each represents an alkyl group, the carbon number of _{R 2} and _{R 3} are from the same viewpoint, 1-5 are preferred independently, more preferably 1 to 3, 1 to 2 Is more preferable. R ₂ and R ₃ may be each independently a linear alkyl group or a branched alkyl group, but a linear alkyl group is preferable from the viewpoint of suppressing reduction in template strength and suppressing decrease in curing rate. When R ₂ and R ₃ are combined to represent an alkylene group, the alkylene group has 2 or more carbon atoms from the same viewpoint, preferably 10 or less, more preferably 4 or less, and still more preferably 2. Further, when an alkylene group by bonding _{R 2} and _{R 3,} the carbon number of the alkylene group is from the same viewpoint, 2-10, 2-4 preferably, 2 is more preferable.

  The molecular weight of the acetal compound represented by the general formula (1) is preferably 111 or more, and preferably 250 or less from the viewpoint of obtaining sufficient mold strength and obtaining a sufficient mold curing rate.

  The content of the acetal compound represented by the general formula (1) in the binder composition for mold making according to this embodiment is from the viewpoint of obtaining sufficient mold strength and obtaining a sufficient mold curing rate. 25 mass% or more is preferable, 30 mass% or more is more preferable, and 35 mass% or more is still more preferable. The content of the acetal compound represented by the general formula (1) in the binder composition for mold making according to this embodiment is from the viewpoint of obtaining sufficient mold strength and obtaining a sufficient mold curing rate. 60 mass% or less is preferable, 55 mass% or less is more preferable, and 50 mass% or less is still more preferable. From the same viewpoint, the content of the acetal compound represented by the general formula (1) in the binder composition for mold making according to this embodiment is preferably 25 to 60% by mass, and 30 to 55% by mass. More preferably, 35-50 mass% is still more preferable.

[Acid curable resin]
The binder composition may contain a conventionally known acid curable resin as a binder component. In the present specification, the acetal compound represented by the general formula (1) is not included in the acid curable resin.

  Examples of the acid curable resin include furfuryl alcohol, condensate of furfuryl alcohol, condensate of furfuryl alcohol and aldehydes, condensate of furfuryl alcohol, urea and aldehydes (urea-modified furan resin), urea and ethylene. Condensates of urea and aldehydes (urea / ethylene urea co-condensation resin), ones selected from the group consisting of condensates of melamine and aldehydes, and condensates of urea and aldehydes, and from these groups What consists of 2 or more types of mixtures chosen can be illustrated. Moreover, what consists of 2 or more types of cocondensates chosen from these groups can also be used. Of these, from the viewpoint of improving the mold curing speed and mold strength, furfuryl alcohol, condensate of furfuryl alcohol, condensate of furfuryl alcohol, urea, and aldehydes, and condensate of urea, ethylene urea, and aldehydes. It is preferable to use one or more selected from the above, and co-condensates thereof. Since furfuryl alcohol can be produced from a plant which is a non-petroleum resource, it is preferable to use furfuryl alcohol from the viewpoint of the global environment.

  The content of the acid curable resin in the binder composition is preferably 35% by mass or more, more preferably 40% by mass or more, and still more preferably 45% by mass or more from the viewpoint of improving the mold strength. From the same viewpoint, the content of the acid curable resin in the binder composition is preferably 70% by mass or less, more preferably 65% by mass or less, and further preferably 60% by mass or less. From the same viewpoint, the content of the acid curable resin in the binder composition is preferably 35 to 70% by mass, more preferably 40 to 65% by mass, and still more preferably 45 to 60% by mass.

  The binder composition may contain a furanaldehyde compound. However, if the content of the furanaldehyde compound in the binder composition is large, the unreacted furanaldehyde compound volatilizes when the mold is cured, and the working environment may be deteriorated. Therefore, the content of the furanaldehyde compound in the binder composition is preferably 3% by mass or less, and more preferably 1% by mass or less.

  Examples of the furanaldehyde compound include at least one selected from the group consisting of furfural, 5-hydroxymethylfurfural, and 5-acetoxymethylfurfural.

[Curing accelerator]
The binder composition may contain a hardening accelerator from the viewpoint of improving the mold strength. As the curing accelerator, from the viewpoint of improving the mold strength, at least one selected from the group consisting of a compound represented by the following general formula (2) (hereinafter referred to as curing accelerator (2)) and an aromatic dialdehyde. Is preferred.

〔式中、Ｘ_１及びＸ_２は、それぞれ水素原子、ＣＨ_３又はＣ_２Ｈ_５の何れかを表す。〕

[Wherein, X ₁ and X ₂ each represent a hydrogen atom, CH ₃ or C ₂ H ₅ . ]

  Examples of the curing accelerator (2) include 2,5-bishydroxymethyl furan, 2,5-bismethoxymethyl furan, 2,5-bisethoxymethyl furan, 2-hydroxymethyl-5-methoxymethyl furan, 2- Examples include hydroxymethyl-5-ethoxymethylfuran and 2-methoxymethyl-5-ethoxymethylfuran. Of these, 2,5-bishydroxymethylfuran is preferably used from the viewpoint of improving the mold strength.

  Examples of the aromatic dialdehyde include terephthalaldehyde, phthalaldehyde and isophthalaldehyde, and derivatives thereof. These derivatives mean compounds having a substituent such as an alkyl group on the aromatic ring of an aromatic compound having two formyl groups as the basic skeleton. From the viewpoint of improving the mold strength, terephthalaldehyde and terephthalaldehyde derivatives are preferable, and terephthalaldehyde is more preferable.

  The content of the curing accelerator in the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably 2% by mass or more from the viewpoint of improving the mold strength. The content of the curing accelerator in the binder composition is preferably 50% by mass or less, more preferably 40% by mass or less, and more preferably 30% by mass from the viewpoint of solubility of the curing accelerator and improvement of mold strength. The following is more preferable.

[water]
The binder composition may further contain water. For example, when synthesizing various condensates such as a condensate of furfuryl alcohol and aldehydes, an aqueous raw material is used or condensed water is generated. Therefore, the condensate is usually in the form of a mixture with water. It is obtained by. In using such a condensate in the binder composition, water may be removed by topping, if necessary, but it is intentionally removed during production as long as the curing reaction rate can be maintained. There is no need. Moreover, water may be further added for the purpose of adjusting the binder composition to a viscosity that is easy to handle. When water is further added for the purpose of adjusting the binder composition to an easy-to-handle viscosity, the viscosity of the binder composition (25 from the viewpoint of workability during the production of the mold making composition and the mold production). Is preferably 70 mPa · s or less, and more preferably 50 mPa · s or less.

  The binder composition may further contain an additive such as a silane coupling agent. For example, it is preferable that the binder composition contains a silane coupling agent because the final strength of the obtained mold can be further improved. As the silane coupling agent, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- aminosilanes such as γ-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, Epoxy silanes such as 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, ureidosilane, mercaptosilane, sulfide silane, methacryloxysilane, acryloxysilane, and the like are used. Amino silane, epoxy silane, and ureido silane are preferable. More preferred are aminosilane and epoxysilane. Among aminosilanes, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane is preferable. Of the epoxy silanes, 3-glycidoxypropylmethyldimethoxysilane is preferred.

  The content of the silane coupling agent in the binder composition is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more from the viewpoint of improving the mold strength. From the same viewpoint, the content of the silane coupling agent in the binder composition is preferably 5% by mass or less, and more preferably 4% by mass or less. From the same viewpoint, the content of the silane coupling agent in the binder composition is preferably 0.01 to 5% by mass, and more preferably 0.05 to 4% by mass.

  The binder composition for mold making of this embodiment is suitably used for making a self-hardening mold. Here, the self-hardening mold is a mold in which, when a binder composition and a curing agent are mixed with sand, a polymerization reaction proceeds with time, and the mold is cured. As temperature of the sand used in that case, it is the range of -20 degreeC-50 degreeC, Preferably it is 0 degreeC-40 degreeC. The mold can be appropriately cured by selecting a suitable amount of a curing agent for the sand at such a temperature and adding it to the sand.

<Mold production method>
The method for producing a mold according to the present embodiment comprises mixing a refractory particle, a binder for mold molding, and a curing agent composition containing a curing agent for curing the binder composition for mold molding. A mixing step of obtaining a mold composition, and a curing step of filling the mold composition in a mold and curing the mold composition. The mold manufacturing method can further suppress deterioration of the working environment during mold manufacturing while obtaining sufficient mold strength.

(Fireproof particles)
As the refractory particles, one or more conventionally known ones such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used, and used fire resistance. Those obtained by collecting or regenerating particles can also be used. Among these, it is preferable to contain silica sand.

[Curing agent composition]
The said hardening | curing agent composition contains an acid from a viewpoint of preventing the deterioration of the working environment at the time of mold hardening, and a viewpoint of mold intensity improvement.

[acid]
The acid is not particularly limited as long as the acid can cure the binder composition. Examples of the acid include 2,6-dihydroxybenzoic acid, oxalic acid, maleic acid, pyruvic acid, malonic acid, 2-furancarboxylic acid, phthalic acid, fumaric acid, lactic acid, citric acid, malic acid and other carboxylic acids, xylene Use one or more conventionally known compounds such as sulfonic acid (especially m-xylenesulfonic acid), toluenesulfonic acid (especially p-toluenesulfonic acid), sulfonic acid compounds such as methanesulfonic acid, phosphoric acid and sulfuric acid. it can. However, when an acid containing sulfur such as sulfonic acid or sulfuric acid is used as a curing agent, SOx gas is generated during casting. Therefore, the content of the acid containing sulfur in the curing agent composition is preferably 60% by mass or less. 30 mass% or less is more preferable, 10 mass% or less is further more preferable, 1 mass% or less is further more preferable, and substantially 0 mass% is still more preferable. In such a case, the amount of SOx gas generated during casting can be reduced to zero. From the viewpoint of improving the strength of the template while suppressing SOx gas, the acid preferably contains a carboxylic acid, more preferably the proportion of the carboxylic acid in the acid is greater, and even more preferably a carboxylic acid. Among the carboxylic acids, at least one selected from the group consisting of 2,6-dihydroxybenzoic acid, oxalic acid and maleic acid is more preferable, and oxalic acid is more preferable.

  The content of the acid in the curing agent composition is appropriately adjusted in order to obtain a desired reaction rate and mold strength, depending on the temperature of the working environment and the temperature of the refractory particles. From the viewpoint of improving the mold strength, the content is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. Similarly, the content of the acid in the curing agent composition is preferably 80% by mass or less, more preferably 70% by mass or less, and still more preferably 60% by mass or less from the viewpoint of improving the mold strength. The content of the acid in the curing agent composition is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, and still more preferably 20 to 60% by mass from the viewpoint of improving the mold strength.

[Other ingredients]
The said hardening | curing agent composition may contain another component in the range which does not impair the effect of the casting_mold | template of this embodiment. Examples of the other components include the following components.

  The curing agent composition may contain one or more solvents selected from the group consisting of alcohols and ether alcohols. Among these, alcohols are more preferable.

  From the viewpoint of improving mold strength, the alcohols are preferably methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, and benzyl alcohol, and the ether alcohols are ethylene glycol monoethyl ether, ethylene glycol mono Butyl 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 are preferred.

  The content of the solvent in the curing agent composition is appropriately adjusted in order to obtain a desired reaction rate and mold strength, depending on the temperature of the working environment and the temperature of the refractory particles. From the viewpoint of improving the mold strength and 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 still more preferably 20% by mass or more. From the same viewpoint, 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 still more preferably 70% by mass or less. Moreover, 5-90 mass% is preferable from the same viewpoint, as for content of the said solvent in the said hardening | curing agent composition, 10-80 mass% is more preferable, and 20-70 mass% is still more preferable.

  In addition, regarding the hardening | curing agent composition, the state at the time of use does not ask | require. For example, in the case of a solid, it may be used by coating refractory particles, but it is preferably liquid at the time of use, and more preferably liquid at 25 ° C.

[Other ingredients]
The mold manufacturing method of the present embodiment includes an acid curable resin, a curing accelerator, water, an additive such as a silane coupling agent, an acidic substance, a solvent, and the like to such an extent that the effects of the present embodiment are not impaired. Also good.

  In the mixing step, the order of adding and mixing the binder composition and the curing agent composition, and the refractory particles is not particularly limited, and the binder composition and the curing agent composition are mixed. After producing the mold molding composition, the mold molding composition and the refractory particles may be mixed, and the binder composition, the curing agent composition, and the refractory particles are added and mixed, respectively. However, from the viewpoint of storage stability and mold productivity, it is preferable to mix the binder composition, the curing agent composition, and refractory particles to obtain a mold composition. Further, from the viewpoint of improving the mold strength, it is preferable to add and mix the curing agent composition to the refractory particles, and then add and mix the binder composition. Moreover, when using 2 or more types of hardening | curing agent compositions, you may add after mixing each hardening | curing agent composition, and you may add each hardening | curing agent composition separately.

  The ratio of the refractory particles, the binder composition and the curing agent composition can be set as appropriate in order to obtain a desired mold strength depending on the temperature of the working environment and the temperature of the refractory particles. From the viewpoint of improving mold strength, the binder composition is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the refractory particles, and from the viewpoint of economy and improvement of casting quality, the fire resistance 3.0 parts by mass or less is preferable with respect to 100 parts by mass of the conductive particles, and 1.5 parts by mass or less is more preferable. From the viewpoint of improving mold strength, the curing agent composition is preferably 0.10 parts by mass or more, more preferably 0.20 parts by mass or more, and economical viewpoint and casting quality with respect to 100 parts by mass of the refractory particles. From an improvement viewpoint, 2.0 mass parts or less are preferable with respect to 100 mass parts of the refractory particles, and 1.0 mass part or less is more preferable. The ratio of the refractory particles, the binder composition, and the curing agent composition is 100 parts by mass of the refractory particles from the viewpoint of improving mold strength, from the viewpoint of economic efficiency, and from the viewpoint of improving casting quality. On the other hand, the binder composition is preferably 0.5 to 3.0 parts by mass, and more preferably 0.5 to 1.5 parts by mass. From the viewpoint of improving the mold strength, from the viewpoint of economic efficiency, and from the viewpoint of improving the casting quality, the curing agent composition is preferably 0.10 to 2.0 parts by mass with respect to 100 parts by mass of the refractory particles. 20-1.0 mass part is more preferable.

[Other ingredients]
In the mixing step, an acid curable resin, a curing accelerator, water, an additive such as a silane coupling agent, an acidic substance, and a solvent may be added to such an extent that the effects of the present embodiment are not impaired. An acid curable resin, a curing accelerator, water, an additive such as a silane coupling agent, an acidic substance, and a solvent may be used for the component that can be used in the binder composition and the curing agent composition. Similar ingredients and amounts can be used.

  In the mixing step, as a method of mixing the raw materials, a known general method can be used, for example, a method of adding each raw material by a batch mixer and kneading, or a method of supplying each raw material to a continuous mixer and kneading. The method of doing is mentioned.

  In the mold manufacturing method of the present embodiment, the mold can be manufactured using the conventional mold manufacturing process as it is except for the mixing step.

  Examples and the like specifically showing the present invention will be described below.

<Evaluation method>
[Furfuryl alcohol / furfural content of binder composition]
Measurement was performed by gas chromatography. (Create a calibration curve with furfuryl alcohol and furfural)
Measurement condition:
Internal standard solution: 1,6-hexanediol Column: PEG-20M Chromosorb WAW DMCS 60 / 80mes / h (manufactured by GL Sciences Inc.)
Column temperature: 80 to 200 ° C. (8 ° C./min)
・ Injection temperature: 210 ℃
-Detector temperature: 250 ° C
Carrier gas: 50 mL / min (He)

<Preparation example>
[Production of furfural dimethyl acetal]
In a three-necked flask, 100 parts by mass of furfural, 123 parts by mass of methanol, 2.8 parts by mass of ammonium chloride, and 62 parts by mass of molecular sieve 3A were mixed and reacted in a nitrogen atmosphere under reflux for 10 hours. . After cooling, filtration was performed to obtain furfural dimethyl acetal.

[Production of urea / ethylene urea condensate]
In a three-necked flask, 100 parts by mass of 37% formaldehyde solution, 106 parts by mass of ethylene urea, and 25 parts by mass of urea were mixed and reacted at 100 ° C. for 3 hours to obtain a urea / ethylene urea condensate. The composition of the urea / ethylene urea condensate was 66 mass% urea / ethylene urea cocondensation resin and 34 mass% water.

<Examples 1-3 and Comparative Examples 1 and 2>
(Production of binder composition)
The acetal compound, acid curable resin, and silane coupling agent shown in Table 1 were mixed at a predetermined mass ratio to produce binder compositions of Examples 1 to 3 and Comparative Examples 1 and 2. In Table 1, “FFA” means furfuryl alcohol, “FL” means furfural, and “silane coupling agent” means 3-glycidoxypropylmethyldimethoxysilane. For furfural diethyl acetal and furfural ethylene acetal, commercially available reagents (manufactured by Tokyo Chemical Industry Co., Ltd.) were used.

[Manufacture of curing agent composition]
2,6-dihydroxybenzoic acid and methanol were mixed at predetermined mass ratios shown in Table 1, respectively, to produce curing agent compositions of Examples 1 to 3 and Comparative Examples 1 and 2. In Table 1, “DHB” means 2,6-dihydroxybenzoic acid, and “MeOH” means methanol.

[Manufacture of mold composition]
Under the conditions of 25 ° C. and 55% RH, 0.4 parts by mass of the hardener composition shown in Table 1 was added to and mixed with 100 parts by mass of fresh sand (free mantle), and then the caking shown in Table 1 was made. 1.0 parts by mass of the agent composition was added and mixed to obtain a mold composition.

<Test example>
[Odor during mold production]
The odor of the mold composition immediately after kneading was evaluated according to the following criteria.
3: No specific odor 2: Low specific odor 1: Strong specific odor

(Cutability)
The mold composition immediately after kneading was filled into a cylindrical test piece frame having a diameter of 50 mm and a height of 50 mm, and the mold was removed after 5 minutes. The moldability was evaluated according to the following criteria. The moldability was used as an evaluation showing the mold strength and the mold handling.
3: Mold strength is fully expressed and mold removal is possible 2: Mold strength is slightly insufficient, but mold removal is possible 1: Mold strength is insufficient and mold removal is difficult

  The evaluation results are shown in Table 1.

Claims (6)

Binder composition for mold making containing an acetal compound represented by the following general formula (1) and an acid curable resin.

(In the general formula (1), R ₁ represents a hydrogen atom, a hydroxyl group, an acetoxyalkyl group, or an alkyl group having 1 to 5 carbon atoms. R ₂ and R ₃ each independently represents 1 to 1 carbon atoms. 5 represents an alkyl group, or R ₂ and R ₃ are bonded to each other to represent an alkylene group having 2 to 10 carbon atoms.) In the general formula (1), R ₂ and R ₃ each independently represent an alkyl group having 1 or 2 carbon atoms, or R ₂ and R ₃ are bonded to each other to represent an alkylene group having 2 carbon atoms. The binder composition for mold making according to claim 1.   The mold according to claim 1 or 2, wherein the acid curable resin is at least one selected from furfuryl alcohol, a condensate of furfuryl alcohol, urea, and aldehydes, and a condensate of urea, ethylene urea, and aldehydes. Binder composition for molding.   A refractory particle, a binder for molding a mold according to any one of claims 1 to 3, and a curing agent composition comprising a curing agent for curing the binder composition for molding. A composition for molds to be contained.   The composition for casting_mold | template of Claim 4 whose said hardening | curing agent contains carboxylic acid.   A refractory particle, a binder for molding a mold according to any one of claims 1 to 3, and a curing agent composition comprising a curing agent for curing the binder composition for molding. A method for producing a mold, comprising: a mixing step of mixing to obtain a mold composition; and a curing step of filling the mold composition in a mold and curing the mold composition.