Mold-forming binder composition

Abstract

To provide a mold molding binder composition with excellent storage stability suppressing thickening upon storage and suppressing deterioration in the fluidity and fillability of a mold molding composition, a mold molding composition and a mold production method.SOLUTION: A mold molding binder composition comprises: an alkali phenol resin; an imidazole compound expressed by the following formula (1); and water. In the general formula (1), R1, R2, R3 and R4 respectively denote hydrogen or a hydrocarbon group having a carbon number of 1 or more to 4 or less.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] A mold-making method is known in which a phenolic resin is used as a binder, and the phenolic resin is cured with an organic ester, carbon dioxide, or amine gas. For example, Patent Document 1 describes an organic binder for molds that contains a phenolic resin, a polyisocyanate compound, an organic solvent, and a specific organic nitrogen compound, which is used for molding phenolic urethane-based gas-curing molds or self-hardening molds with the aim of exhibiting excellent mold strength (initial strength).

[0003] When binders containing phenolic resin are left standing for a long time, the phenolic resin thickens, reducing storage stability. This leads to problems such as poor quantitative accuracy when automatically supplied by pumps, uneven mixing, and deterioration of the fluidity and fillability of mold-making compositions containing refractory particles and binder compositions. Poor fillability of mold-making compositions can result in unevenness on the surface of the resulting mold, or a decrease in the surface strength of the mold, leading to casting defects such as sand inclusion, seizing, insertion, and shrinkage in the resulting castings.

[0004] Regarding the above issues, Patent Document 2 describes a carbon dioxide-curing binder composition that uses a mixture of a water-soluble phenolic resin and a cyclic urea compound, with the aim of improving the surface stability of the mold while maintaining high mold strength and suppressing the thickening of the binder. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-192477 [Patent Document 2] Japanese Patent Publication No. 2000-15389 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The technology described in Patent Document 2 was insufficient in suppressing the thickening of the binder and improving storage stability.

[0007] The present invention provides a mold-forming binder composition, a mold-forming composition, and a method for manufacturing a mold that have excellent storage stability, suppressing thickening during storage, particularly when stored in a high-temperature environment (e.g., 50°C), and suppressing deterioration of the fluidity and fillability of the mold-forming composition. [Means for solving the problem]

[0008] The present invention relates to a mold-forming binder composition containing an alkali phenol resin, an imidazole compound represented by the following formula (1), and water.

[0009] [ka] (In the above general formula (1), R 1 , R 2 , R 3 and R 4 Each of these independently represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a mold-forming binder composition, a mold-forming composition, and a method for manufacturing a mold that have excellent storage stability, suppressing thickening during storage and suppressing deterioration of the fluidity and fillability of the mold-forming composition. [Modes for carrying out the invention]

[0011] <Bonding agent composition for mold making> The mold-forming binder composition of this embodiment (hereinafter also simply referred to as the binder composition) is a mold-forming binder composition containing an alkali phenol resin, an imidazole compound represented by the following formula (1), and water.

[0012] [Chemical formula] (In the general formula (1), R 1 , R 2 , R 3 and R 4 each independently represent hydrogen or a hydrocarbon group having 1 to 4 carbon atoms.)

[0013] According to the binder composition of the present embodiment, thickening during storage, particularly thickening during storage in a high-temperature (e.g., 50°C) environment, is suppressed, and deterioration of the fluidity and filling property of the mold molding composition is suppressed, and a binder composition excellent in storage stability can be provided. The reason why the binder composition of the present embodiment exhibits such an effect is not clear, but it is considered as follows.

[0014] It is considered that the thickening of the alkaline phenolic resin is due to the condensation of methylol groups. On the other hand, it is considered that an imidazole compound having a small steric structure and having a lone pair of electrons on a nitrogen atom coordinates with the methylol group, thereby suppressing the condensation of methylol groups.

[0015] [Alkaline phenolic resin] The aforementioned alkali-phenol resin is generally obtained by polycondensing a phenol compound and an aldehyde compound under alkaline conditions. The phenol compound can be one or more of the following: phenol, bisphenol A, bisphenol F, cresol, 3,5-xylenol, resorcinol, catechol, nonylphenol, p-tert-butylphenol, isopropenylphenol, phenylphenol, and other substituted phenols, or mixtures of various phenol compounds such as cashew nut shell liquid. The aldehyde compound can be one or more of the following: formaldehyde, acetaldehyde, furfural, glyoxal, etc. These compounds can be used as aqueous solutions as needed. Furthermore, these may be mixed with monomers that can condense with aldehyde compounds such as urea, melamine, and cyclohexanone, monohydric aliphatic alcohol compounds such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butyl alcohol, or water-soluble polymers such as polyacrylates, cellulose derivative polymers, polyvinyl alcohol, and lignin derivatives.

[0016] Examples of alkali catalysts used in the synthesis of the alkali-phenol resin include alkali metal hydroxides such as LiOH, NaOH, and KOH, with NaOH and / or KOH being particularly preferred. Alternatively, these alkali catalysts may be mixed with the binder composition. The alkali metal hydroxide is preferably used in an amount of 0.01 to 6 moles, more preferably 0.5 to 2.5 moles, per mole of phenol.

[0017] Generally, the alkali phenol resin is used in aqueous solution form. The alkali phenol resin content in the aqueous alkali phenol resin solution (solid mass after drying the aqueous alkali phenol resin solution at 105°C for 3 hours) is preferably 30% by mass or more, and more preferably 50% by mass or more, from the viewpoint of improving mold strength. The alkali phenol resin content in the aqueous alkali phenol resin solution is preferably 85% by mass or less, and more preferably 75% by mass or less, from the viewpoint of improving mold strength and workability. Furthermore, the alkali phenol resin content in the aqueous alkali phenol resin solution is preferably 30 to 85% by mass, and more preferably 50 to 75% by mass, from the viewpoint of improving mold strength and workability.

[0018] The weight-average molecular weight (Mw) of the alkali phenol resin is preferably 500 or more, more preferably 800 or more, and even more preferably 1200 or more, from the viewpoint of improving mold strength. The weight-average molecular weight (Mw) of the alkali phenol resin is preferably 8000 or less, more preferably 5000 or less, and even more preferably 3000 or less, from the viewpoint of improving mold strength and workability. Furthermore, the weight-average molecular weight (Mw) of the alkali phenol resin is preferably 500 to 8000, more preferably 800 to 5000, and even more preferably 1200 to 3000, from the viewpoint of improving mold strength and workability. The weight-average molecular weight of the alkali phenol resin is measured by the method described in the examples.

[0019] From the perspective of improving the mold strength, the content of the alkaline phenolic resin in the binder composition is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and even more preferably 40% by mass or more. From the perspective of suppressing the thickening during storage of the binder composition and improving the fluidity of the mold molding composition, the content of the alkaline phenolic resin in the binder composition is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 55% by mass or less, even more preferably 53% by mass or less, even more preferably 52% by mass or less, even more preferably 50% by mass or less, even more preferably 49% by mass or less, even more preferably 48% by mass or less, and even more preferably 46% by mass or less. Further, from the perspective of improving the mold strength, suppressing the thickening during storage of the binder composition, and improving the fluidity of the mold molding composition, the content of the alkaline phenolic resin in the binder composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, still more preferably 30 to 60% by mass, even more preferably 40 to 60% by mass, even more preferably 40 to 55% by mass, even more preferably 40 to 53% by mass, even more preferably 40 to 52% by mass, even more preferably 40 to 50% by mass, even more preferably 40 to 49% by mass, even more preferably 40 to 48% by mass, and even more preferably 40 to 46% by mass.

[0020] 〔Imidazole compound〕 From the perspective of suppressing the thickening during storage of the binder composition, the imidazole compound contains a compound in which R in the general formula (1) 1 represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms.

[0021] From the perspective of suppressing the thickening during storage of the binder composition, the imidazole compound contains a compound in which R in the general formula (1) 2 represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms, preferably hydrogen or a hydrocarbon group having 1 to 2 carbon atoms.

[0022] From the perspective of suppressing the thickening during storage of the binder composition, the imidazole compound contains a compound in which R in the general formula (1)3 The compound contains hydrogen, or a hydrocarbon group having 1 to 4 carbon atoms, preferably hydrogen, or a hydrocarbon group having 1 to 2 carbon atoms, more preferably hydrogen, or a methyl group.

[0023] The imidazole compound is selected from the viewpoint of suppressing thickening of the binder composition during storage, as shown in the general formula (1) R 4 The compound contains hydrogen, or a hydrocarbon group having 1 to 4 carbon atoms, preferably hydrogen, or a methyl group, more preferably hydrogen.

[0024] The imidazole compound is selected from the viewpoint of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition, as R in the general formula (1). 1 , R 2 , R 3 and R 4 This includes compounds in which the total number of carbon atoms is preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, even more preferably 5 or less, even more preferably 4 or less, even more preferably 3 or less, even more preferably 2 or less, even more preferably 1 or less, and even more preferably 0.

[0025] Specific examples of the imidazole compound include one or more selected from the group consisting of imidazole, 1-methylimidazole, 1,2-dimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 1-isobutyl-2-methylimidazole, 1-isopropylimidazole, 2-isopropylimidazole, 1-t-butylimidazole, 1-propylimidazole, 2-propylimidazole, 1-vinylimidazole, 1,2,4,5-tetramethylimidazole, 1-butylimidazole, 2-butylimidazole, 1-ethylimidazole, 2-methyl-1-vinylimidazole, 1-alliimidazole, 4-methylimidazole, and 4-ethylimidazole. The imidazole compound is preferably one or more selected from the group consisting of imidazole, 1-methylimidazole, 1,2-dimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-isobutyl-2-methylimidazole, from the viewpoint of suppressing thickening during storage of the binder composition and improving the fluidity of the mold-making composition, and more preferably imidazole, 1-methylimidazole, 1,2-dimethylimidazole, and 2-ethylimidazole. The compound comprises one or more selected from the group consisting of , and 2-ethyl-4-methylimidazole, more preferably one or more selected from the group consisting of imidazole, 1-methylimidazole, 1,2-dimethylimidazole, and 2-ethylimidazole, even more preferably one or more selected from the group consisting of imidazole, 1-methylimidazole, and 1,2-dimethylimidazole, even more preferably imidazole and / or 1-methylimidazole, and even more preferably imidazole. Furthermore, from the viewpoint of availability, the imidazole compound is preferably imidazole and / or 2-ethyl-4-methylimidazole.

[0026] The content of the imidazole compound in the binder composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.7% by mass or more, even more preferably 2% by mass or more, even more preferably 4% by mass or more, even more preferably 7% by mass or more, even more preferably 9% by mass or more, and even more preferably 13% by mass or more, from the viewpoint of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition. The content of the imidazole compound in the binder composition is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, and even more preferably 17% by mass or less, from the viewpoint of improving mold strength. Furthermore, the content of the imidazole compound in the binder composition is preferably 0.1 to 30% by mass, more preferably 0.1 to 25% by mass, even more preferably 0.1 to 20% by mass, even more preferably 0.1 to 17% by mass, even more preferably 0.7 to 17% by mass, even more preferably 2 to 17% by mass, even more preferably 4 to 17% by mass, even more preferably 7 to 17% by mass, even more preferably 9 to 17% by mass, and even more preferably 13 to 17% by mass, from the viewpoint of suppressing thickening of the binder composition during storage, improving the fluidity of the mold-making composition, and improving mold strength.

[0027] The content of the imidazole compound in the binder composition per 100 parts by mass of the alkali phenol resin is preferably 0.2 parts by mass or more, more preferably 1 part by mass or more, even more preferably 4 parts by mass or more, even more preferably 8 parts by mass or more, even more preferably 14 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 27 parts by mass or more, from the viewpoint of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition. The content of the imidazole compound in the binder composition per 100 parts by mass of the alkali phenol resin is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, from the viewpoint of improving mold strength. Furthermore, the content of the imidazole compound in the binder composition relative to 100 parts by mass of the alkali phenol resin is preferably 0.2 to 60 parts by mass, more preferably 0.2 to 50 parts by mass, even more preferably 0.2 to 45 parts by mass, even more preferably 0.2 to 40 parts by mass, even more preferably 0.2 to 35 parts by mass, even more preferably 1 to 35 parts by mass, even more preferably 4 to 35 parts by mass, even more preferably 8 to 35 parts by mass, even more preferably 14 to 35 parts by mass, even more preferably 20 to 35 parts by mass, and even more preferably 27 to 35 parts by mass, from the viewpoint of suppressing thickening of the binder composition during storage, improving the fluidity of the mold-making composition, and improving the strength of the mold.

[0028] 〔water〕 The water content in the binder composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition. The water content in the binder composition is preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of improving mold strength, suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition. Furthermore, the water content in the binder composition is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, even more preferably 25 to 45% by mass, and even more preferably 25 to 40% by mass, from the viewpoint of suppressing thickening of the binder composition during storage, improving the fluidity of the mold-making composition and improving mold strength.

[0029] [Other ingredients] The binder composition may further contain additives such as silane coupling agents, aluminates, and oxyanion compounds, to an extent that does not hinder the effects of this embodiment.

[0030] [Silane coupling agent] The binder composition preferably contains a silane coupling agent from the viewpoint of improving mold strength. Examples of the silane coupling agent include γ-(2-amino)propylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane. The content of the silane coupling agent in the binder composition is preferably 0.1 to 5% by mass, more preferably 0.3 to 1% by mass, from the viewpoint of improving mold strength.

[0031] [Aluminate] The binder composition preferably contains an aluminate from the viewpoint of improving mold strength. Examples of the aluminate include alkali metal salts of aluminic acid. From the viewpoint of improving mold strength, sodium aluminate is preferred. From the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. From the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. Furthermore, from the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1 to 3% by mass.

[0032] [Oxyanionic compounds] When curing the binder composition with carbon dioxide, it is preferable to include an oxyanion compound from the viewpoint of improving mold strength and improving the curing speed of the mold. This is because it is thought that the oxyanion compound forms an ionomer and polymerizes the alkali phenol resin only after absorbing carbon dioxide. Examples of the oxyanion compound include boric acid and borate compounds. Examples of borates include sodium tetraborate decahydrate (borax), potassium tetraborate decahydrate, sodium metaborate, sodium pentaborate, and potassium pentaborate. From the viewpoint of improving mold strength and improving the curing speed of the mold, sodium tetraborate decahydrate (borax) is preferred.

[0033] The content of the oxyanion compound in the binder composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of improving mold strength and improving the curing speed of the mold. The content of the oxyanion compound in the binder composition is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving mold strength and improving the fluidity of the mold-making composition. Furthermore, the content of the oxyanion compound in the binder composition is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, even more preferably 5 to 15% by mass, and even more preferably 6 to 10% by mass, from the viewpoint of improving mold strength, improving the curing speed of the mold and improving the fluidity of the mold-making composition.

[0034] The total content of boric acid compounds in the oxyanion compound is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass, from the viewpoint of improving mold strength and improving mold hardening speed.

[0035] The total content of boric acid and borate in the oxyanion compound is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass, from the viewpoint of improving mold strength and improving mold hardening speed.

[0036] The borax content in the oxyanion compound is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and even more preferably 100% by mass, from the viewpoint of improving mold strength and improving mold hardening speed.

[0037] <Method for manufacturing molds> In the mold manufacturing method of this embodiment, the mold can be manufactured by using the conventional mold manufacturing process as is. A preferred mold manufacturing method includes a mixing step of mixing at least refractory particles and the binder composition to obtain a mold-forming composition, and a curing step of filling the mold-forming composition into a mold and curing the mold-forming composition.

[0038] [Mixing process] [Fire-resistant particles] The refractory particles usable in the mold manufacturing method of this embodiment include conventionally known materials such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, and alumina ball sand. Recycled sand obtained by recovering and recycling used refractory particles can also be used. The refractory particles can be used individually or in combination of two or more types.

[0039] The average particle size of the refractory particles is preferably greater than 50 μm, more preferably 70 μm or more, even more preferably 120 μm or more, and even more preferably 150 μm or more, from the viewpoint of improving mold strength and economic efficiency. From the same viewpoint, it is preferably 600 μm or less, more preferably 400 μm or less, even more preferably 300 μm or less, and even more preferably 250 μm or less. In this specification, the average particle size is measured by the method described in the examples.

[0040] In the aforementioned mixing process, known methods can be used to mix each raw material. For example, methods include adding and kneading each raw material using a batch mixer, or supplying each raw material to a continuous mixer and kneading it.

[0041] The ratio of the refractory particles to the binder composition can be set as appropriate, but from the viewpoint of improving mold strength and economic efficiency, the content of the binder composition per 1000 parts by mass of the refractory particles is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. Furthermore, the alkali phenol resin per 1000 parts by mass of the refractory particles is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less.

[0042] In the mixing step described above, when obtaining the mold-making composition, the imidazole compound may be further mixed separately from the binder composition. In that case, the content of the imidazole compound in the mold-making composition is preferably within the range of the content of the imidazole compound per 100 parts by mass of the alkali phenol resin.

[0043] Alternatively, a mold-making composition can be obtained by mixing fire-resistant particles, an aqueous alkali-phenol resin solution containing the aforementioned alkali-phenol resin but without the imidazole compound, and the imidazole compound. In this case, the amount of the imidazole compound used is the same as the amount described in the aforementioned binder composition.

[0044] Furthermore, a mold-making composition can also be obtained by separately mixing the refractory particles, the aqueous alkali phenol resin solution, the imidazole compound, and other components used in the binder composition. In this case, the alkali phenol resin content is preferably 3 parts by mass or more, and preferably 80 parts by mass or less, per 1000 parts by mass of refractory particles. The amounts of the imidazole compound and other components used in the binder composition are the same as those described in the binder composition.

[0045] When the imidazole compound is mixed separately from the binder composition as described above, the imidazole compound is a mold-making additive. The mold-making additive of this embodiment contains the imidazole compound. The preferred embodiment of the imidazole compound in the mold-making additive of the present invention is the same as the preferred embodiment of the imidazole compound in the binder composition.

[0046] [Curing process] In the curing step, the mold-forming composition is packed into a mold and cured. A commonly known method can be used to cure the mold-forming composition. One method for curing the mold-forming composition is curing it with a curing agent. Examples of curing agents include organic ester compounds and carbon dioxide.

[0047] As the organic ester compound, lactones having 3 to 10 carbon atoms, organic esters derived from monohydric or polyhydric alcohols having 1 to 10 carbon atoms and organic carboxylic acids having 1 to 10 carbon atoms, or alkylene carbonates having 1 to 8 carbon atoms can be used alone or in combination. In self-hardening mold making methods, it is preferable to use γ-butyrolactone, propionactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, ethylene carbonate, propylene carbonate, etc., and in gas-curable mold making methods using organic esters, it is preferable to use methyl formate.

[0048] When an organic ester is used as the curing agent, the amount of the organic ester is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 35 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the binder composition, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0049] When an organic ester is used as the curing agent, the amount of organic ester is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and more preferably 70 parts by mass or less, and more preferably 60 parts by mass or less, per 100 parts by mass of phenolic resin, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0050] When carbon dioxide is used as the curing agent, the flow rate of the carbon dioxide should be such that, from the viewpoint of improving the strength of the mold, the mold is 100 cm 3 The flow rate is preferably 0.2 L / min or more, more preferably 1 L / min or more, even more preferably 5 L / min or more, even more preferably 10 L / min or more, and even more preferably 15 L / min or more, and from the viewpoint of economy, a mold of 100 cm 3 The flow rate is preferably 30 L / min or less, more preferably 25 L / min or less. The carbon dioxide flow time is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 25 seconds or more, from the viewpoint of improving mold strength, and preferably 90 seconds or less, more preferably 70 seconds or less, even more preferably 50 seconds or less, and even more preferably 40 seconds or less, from the viewpoint of economic efficiency. The curing temperature is preferably -5°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher, from the viewpoint of improving mold strength, and preferably 45°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower, from the viewpoint of economic efficiency.

[0051] When carbon dioxide is used as the curing agent, the amount of carbon dioxide is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and preferably 100 parts by mass or less, and more preferably 75 parts by mass or less, per 100 parts by mass of the binder composition, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0052] When carbon dioxide is used as the curing agent, the amount of carbon dioxide is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and more preferably 200 parts by mass or less, and more preferably 150 parts by mass or less, per 100 parts by mass of alkali phenolic resin, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0053] <Mold making composition> The mold-making composition of this embodiment contains the refractory particles and the binder composition. That is, the mold-making composition of this embodiment contains the refractory particles, the alkali phenol resin and the imidazole compound.

[0054] The content of the binder composition is as described in the mixing step of the mold manufacturing method with respect to the refractory particles.

[0055] The content of the alkali phenol resin is as described in the mixing step of the mold manufacturing method relative to the refractory particles. The content of the imidazole compound is as described in the binder composition relative to the alkali phenol resin.

[0056] With regard to the embodiments described above, the present invention further discloses the following embodiments. <1> A mold-forming binder composition containing an alkali phenol resin, an imidazole compound represented by the following formula (1), and water. [ka] (In the above general formula (1), R 1 , R 2 , R 3 and R 4 Each of these independently represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms. <2> The content of the imidazole compound in the mold-forming binder composition is 0.1% by mass or more and 30% by mass or less. <1> The mold-forming binder composition described above. <3> The content of the imidazole compound in the mold-forming binder composition is 0.1% by mass or more and 17% by mass or less. <1> or <2> The mold-forming binder composition described above. <4> The content of the imidazole compound in the mold-forming binder composition is 0.2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the alkali phenol resin. <1> ~ <3> A mold-forming binder composition according to any one of the items. <5> The content of the imidazole compound in the mold-forming binder composition is 0.2 parts by mass or more and 35 parts by mass or less per 100 parts by mass of the alkali phenol resin. <1> ~ <4> A mold-forming binder composition according to any one of the items. <6> The imidazole compound represented by formula (1) comprises one or more selected from the group consisting of imidazole, 1-methylimidazole, 1,2-dimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-isobutyl-2-methylimidazole. <1> ~ <5> A mold-forming binder composition according to any one of the items. <7> The alkali phenol resin content in the mold-forming binder composition is 10% by mass or more and 70% by mass or less. <1> ~ <6> A mold-forming binder composition according to any one of the items. <8> The alkali phenol resin content in the mold-forming binder composition is 40% by mass or more and 60% by mass or less. <1> ~ <7> A mold-forming binder composition according to any one of the items. <9> The water content in the aforementioned binder composition is 25% by mass or more and 40% by mass or less. <1> ~ <8> A mold-forming binder composition according to any one of the items. <10> Contains oxyanion compounds, <1> ~ <9> A mold-forming binder composition according to any one of the items. <11> The oxyanion compound contains a borate compound. <10> The mold-forming binder composition described above. <12> The content of the boric acid compound in the oxyanion compound is 95% by mass or more. <10> or <11> The mold-forming binder composition described above. <13> The content of the oxyanion compound in the mold-forming binder composition is 1% by mass or more and 30% by mass or less. <10> ~ <12> A mold-forming binder composition according to any one of the items. <14> The content of the oxyanion compound in the mold-forming binder composition is 6% by mass or more and 10% by mass or less. <10> ~ <13> A mold-forming binder composition according to any one of the items. <15> It is for carbon dioxide curing. <1> ~ <14> A mold-forming binder composition according to any one of the following items. <16> Fire-resistant particles, and <1> ~ <14> A method for manufacturing a mold, comprising a mixing step of mixing a mold-forming binder composition described in any one of the items to obtain a mold-forming composition, and a curing step of filling a mold-forming composition into a mold and curing the mold-forming composition. <17> Fire-resistant particles, and <1> ~ <14> A mixing step to obtain a mold-making composition by mixing a mold-making binder composition described in any one of the items, and a curing step to pack the mold-making composition into a mold and harden the mold-making composition using carbon dioxide gas, <16> A method for manufacturing a mold as described above. <18> <1> ~ <15> A mold-forming binder composition according to any one of the above, and a mold-forming composition containing refractory particles. <19> A mold-making composition comprising an alkali phenol resin, an imidazole compound represented by the following formula (1), and refractory particles. [ka] (In the above general formula (1), R 1 , R 2 , R 3 and R 4 Each of these independently represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms. <20> The content of the alkali phenol resin in the mold-forming composition is 3 parts by mass or more and 80 parts by mass or less per 1000 parts by mass of the refractory particles. <18> or <19> The mold-making composition described above. <21> The content of the alkali phenol resin in the mold-forming composition is 3 parts by mass or more and 25 parts by mass or less per 1000 parts by mass of the refractory particles. <18> ~ <20> A mold-making composition according to any one of the items. <22> The content of the imidazole compound in the mold-forming composition is 0.2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the alkali phenol resin. <18> ~ <21> A mold-making composition according to any one of the items. <23> The content of the imidazole compound in the mold-forming composition is 0.2 parts by mass or more and 35 parts by mass or less per 100 parts by mass of the alkali phenol resin. <18> ~ <22> A mold-making composition according to any one of the items. <24> The imidazole compound represented by formula (1) comprises one or more selected from the group consisting of imidazole, 1-methylimidazole, 1,2-dimethylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, and 1-isobutyl-2-methylimidazole. <18> ~ <23> A mold-making composition according to any one of the items. <25> It is for carbon dioxide curing. <18> ~ <23> A mold-making composition according to any one of the items. [Examples]

[0057] The following describes specific examples illustrating the present invention.

[0058] <Method for evaluating raw materials> [Weight-average molecular weight (Mw) of alkali phenolic resin] The weight-average molecular weight (Mw) of the alkali phenol resin was measured by GPC (gel permeation chromatography) under the following conditions. (a) Sample preparation: An equal weight of deionized water was added to the sample, and neutralization was performed by adding 0.1% by mass of H2SO4. The resulting precipitate was filtered, washed with water, and dried. This was dissolved in tetrahydrofuran (THF) to prepare the sample for GPC. (b) Columns: One Guard Column TSX (manufactured by Toyo Soda Industries Co., Ltd.) HXL (6.5 mmφ × 4 cm), one TSK3000HXL (7.8 mmφ × 30 cm), and one TSK2500HXL (7.8 mmφ × 30 cm) were used. The columns were connected in the order of Guard Column - 3000HXL - 2500HXL from the injection port side. (c) Standard material: Monodisperse polystyrene with known weight-average molecular weight (manufactured by Toyo Soda Co., Ltd.) (d) Eluent: THF (flow rate: 1cm 3 / min) (e) Column temperature: 25℃ (f) Detector: Ultraviolet spectrophotometer (quantification at the wavelength of the maximum peak of ultraviolet absorption of phenol) (g) Splitting method for molecular weight calculation: Time splitting (2 sec)

[0059] [Average particle diameter] (For particles larger than 53 μm) Based on the method specified in Annex 2 of JIS Z2601 (1993) "Test Methods for Foundry Sand," measurements were taken using sieves of 850, 600, 425, 300, 212, 150, 106, 75, and 53 μm, and the particle size at 50% mass accumulation was taken as the average particle size. (For particles smaller than 53 μm) This is the average particle diameter at 50% volume cumulative, measured using a laser diffraction particle size distribution analyzer (LA-920, Horiba, Ltd.). The analysis conditions are as follows: • Measurement method: Flow method • Dispersion medium: Ion-exchanged water • Dispersion method: stirring, built-in ultrasonic for 3 minutes • Sample concentration: 2 mg / 100 cc

[0060] <Preparation of alkaline phenolic resin aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 380.0 g of phenol, 666.3 g of 48% potassium hydroxide aqueous solution, 297.3 g of water, and 263.7 g of 92% paraformaldehyde were mixed and reacted at 85°C to obtain an alkaline phenol resin aqueous solution. The solid content concentration of the alkaline phenol resin aqueous solution was 58.6% by mass. The weight-average molecular weight (Mw) of the alkaline phenol resin was 1820.

[0061] <Example 1-1> [Preparation of binder composition] A binder composition according to Example 1-1 was obtained using 80.7 parts by mass of the alkali phenol resin aqueous solution (47.3 parts by mass of phenol resin), 10.5 parts by mass of imidazole, and 8.8 parts by mass of water. The composition of the obtained binder composition is shown in Table 1.

[0062] <Comparative Example 1-1> [Preparation of binder composition] The procedure for Comparative Example 1-1 was carried out in the same manner as in Example 1-1, except that a predetermined amount of the alkali phenol resin aqueous solution and water were used to obtain the composition shown in Table 1. The composition of the obtained binder composition is shown in Table 1.

[0063] <Comparative Examples 1-2 and 1-3> [Preparation of binder composition] The procedure was carried out in the same manner as in Example 1-1, except that the additives shown in Table 1 were used instead of imidazole, to obtain the binder compositions of Comparative Examples 1-2 and 1-3. The compositions of the obtained binder compositions are shown in Table 1.

[0064] <Evaluation of Example 1-1 and Comparative Examples 1-1 to 1-3> The following evaluations were performed on each binder composition in Example 1-1 and Comparative Examples 1-1 to 1-3.

[0065] [Evaluation of viscosity increase rate] For each binder composition, the viscosity at 25°C was measured using an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) immediately after manufacturing and after being stored in a sealed container at 50°C for 30 days. The viscosity increase rate was calculated according to the following formula. Viscosity increase rate (%) = (Viscosity after 30 days of storage at 50°C) / (Viscosity immediately after manufacturing) × 100 A smaller value for the viscosity increase rate indicates less thickening and better storage stability of the binder composition. The evaluation results are shown in Table 1.

[0066] [Liquidity Assessment] A kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade was used to prepare a mold-making composition. 1000 parts by mass of refractory particles, 10 parts by mass of the binder composition stored at 50°C for 30 days, and 2.5 parts by mass of triacetin were added and mixed at a rotation speed of 300 rpm for 2 minutes. The obtained mold-making composition was filled into a 50 mmΦ × 300 mm test tube from the top to the top of the tube, and its weight was measured. Silica sand ("Mikawa Silica Sand R Grade 6," manufactured by Mikawa Silica Co., Ltd.) was used as the refractory particles. The average particle size of the refractory particles was 181 μm. The evaluation results are shown in Table 1.

[0067] [Table 1]

[0068] <Example 2-1> [Preparation of binder composition] The binder composition of Example 2-1 was obtained using 80.7 parts by mass of the alkali phenol resin aqueous solution (47.3 parts by mass of alkali phenol resin), 1.5 parts by mass of sodium aluminate, 6.5 parts by mass of sodium tetraborate decahydrate (borax), 0.8 parts by mass of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent, and 10.5 parts by mass of imidazole. The composition of the obtained binder composition is shown in Table 2.

[0069] <Examples 2-2 to 2-12 and Comparative Examples 2-1 to 2-6> [Preparation of binder composition] The procedure was carried out in the same manner as in Example 2-1, except that predetermined amounts of alkaline phenol resin aqueous solution, sodium aluminate, sodium tetraborate decahydrate, and 3-glycidoxypropyltrimethoxysilane, and the compounds listed in Table 2 were used to obtain the binder compositions of Examples 2-2 to 2-12 and Comparative Examples 2-1 to 2-6.

[0070] <Evaluation of Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-6> The following evaluations were performed on each binder composition in Examples 2-1 to 2-12 and Comparative Examples 2-1 to 2-6.

[0071] [Evaluation of viscosity increase rate] For each binder composition, the viscosity at 25°C was measured using an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.) immediately after manufacturing and after being stored in a sealed container at 50°C for 60 days. The viscosity increase rate was calculated according to the following formula. Viscosity increase rate (%) = (Viscosity after 60 days of storage at 50°C) / (Viscosity immediately after manufacturing) × 100 A smaller viscosity increase rate indicates less thickening and better storage stability of the binder composition. The evaluation results are shown in Table 2.

[0072] [Liquidity Assessment] A kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade was used to prepare a mold-making composition. 1000 parts by mass of refractory particles and 30 parts by mass of the binder composition stored at 50°C for 60 days were added and mixed at a rotation speed of 300 rpm for 2 minutes. The obtained mold-making composition was filled into a 50 mmΦ × 300 mm test tube from the top to the top of the tube, and its mass was measured. A higher mass value indicates better fluidity. The refractory particles used were silica sand ("Mikawa Silica Sand R Grade No. 6," manufactured by Mikawa Silica Co., Ltd.). The average particle size of the refractory particles was 181 μm. The evaluation results are shown in Table 2.

[0073] [Evaluation of mold strength] 1000 parts by mass of refractory particles and 30 parts by mass of the binder composition were added to a kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade, and mixed at a rotation speed of 300 rpm for 2 minutes to obtain a mold-making composition. The obtained mold-making composition was filled into a wooden mold for a test piece measuring 50 mmΦ × 50 mm, and carbon dioxide gas was passed through it at a flow rate of 20 L / min for 30 seconds at 25°C to obtain an evaluation test piece. After the test piece was left to stand at 25°C for 24 hours, the mold compressive strength of the test piece was measured using a compressive strength evaluation tester ("SDW 2000SH Special Type" Imada Seisakusho Co., Ltd.) at a speed of 5 mm / second. The evaluation results are shown in Table 2.

[0074] [Table 2]

[0075] <Example 3-1 and Comparative Example 3-1> [Preparation of binder composition] The alkali phenol resin aqueous solution, sodium aluminate, 3-glycidoxypropyltrimethoxysilane, and imidazole were mixed in predetermined amounts as shown in Table 3 to obtain the binder compositions of Example 3-1 and Comparative Example 3-1. The binder compositions of Example 3-1 and Comparative Example 3-1 were evaluated as follows.

[0076] [Evaluation of viscosity increase rate] The evaluation was performed using the same method as in Example 1. The evaluation results are shown in Table 3.

[0077] [Liquidity Assessment] The evaluation was performed using the same method as in Example 1. The evaluation results are shown in Table 3.

[0078] [Table 3]

Claims

1. A mold-forming binder composition containing an alkali phenol resin, an imidazole compound represented by the following formula (1), and water. 【Chemistry 1】 (In the above general formula (1), R １ , R ２ , R ３ and R ４ Each of these independently represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms.

2. The mold-forming binder composition according to claim 1, wherein the content of the imidazole compound in the mold-forming binder composition is 0.1% by mass or more and 30% by mass or less.

3. The mold-forming binder composition according to claim 1 or 2, wherein the content of the imidazole compound in the mold-forming binder composition is 0.2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the alkali phenol resin.

4. The mold-forming binder composition according to claim 1 or 2, wherein the content of the alkali phenol resin in the mold-forming binder composition is 10% by mass or more and 70% by mass or less.

5. A mold-forming binder composition according to claim 1 or 2, comprising an oxyanion compound.

6. A mold-forming binder composition according to claim 1 or 2, which is for carbon dioxide curing.

7. A method for manufacturing a mold, comprising a mixing step of mixing refractory particles and a mold-forming binder composition according to claim 1 or 2 to obtain a mold-forming composition, and a curing step of filling a mold-forming composition into a mold and curing the mold-forming composition.

8. A mold-making binder composition according to claim 1 or 2, and a mold-making composition containing refractory particles.

9. A mold-making composition comprising an alkali phenol resin, an imidazole compound represented by the following formula (1), and refractory particles. 【Chemistry 2】 (In the above general formula (1), R １ , R ２ , R ３ and R ４ Each of these independently represents hydrogen or a hydrocarbon group having 1 to 4 carbon atoms.

10. The mold-making composition according to claim 8, wherein the content of the alkali phenol resin in the mold-making composition is 3 parts by mass or more and 80 parts by mass or less per 1000 parts by mass of the refractory particles.

11. The mold-making composition according to claim 8, wherein the content of the imidazole compound in the mold-making composition is 0.2 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the alkali phenol resin.

12. A mold-making composition according to claim 8, which is for carbon dioxide curing.

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