JP6240474B2 - Self-hardening binder composition for mold making - Google Patents

Description

  The present invention relates to a binder composition for molding a self-hardening mold, a mold composition using the same, and a method for producing the mold.

  Acid-curing self-hardening mold is a hardened material containing a self-hardening mold-forming binder containing acid-hardening resin such as furan resin, and phosphoric acid, organic sulfonic acid, sulfuric acid, etc. An agent is added and these are kneaded, and then the obtained kneaded sand is filled in an original mold such as a wooden mold and the acid curable resin is cured.

  The furan resin contains aldehydes as raw materials. Since the aldehydes volatilize at the time of mold making, an aldehyde odor is generated, which causes a deterioration of the working environment. Therefore, it is required to suppress the volatilization of aldehydes during mold making.

  In order to solve the above problems, for example, Patent Document 1 discloses a resin composition for a mold obtained from a urea compound such as an alkyl urea and a furan resin. Patent Document 2 discloses a resin-based substance selected from the group consisting of phenol-based resole resins, furan resins, resorcin resins, phenol-based resorcin resins, ethylene urea-terminated resins, and mixtures thereof. Patent Document 3 discloses a furan resin composition having a urea content of 1 to 10% by weight and a pH of 7 to 10 at 25 ° C.

JP 2008-183580 A JP-A-53-49053 JP 2006-70247 A

  However, in patent document 1, the reduction | decrease of the aldehyde generate | occur | produced at the time of hardening is not enough. The ethylene urea-terminated resin disclosed in Patent Document 2 does not have a specific resin structure. The resin composition disclosed in Patent Document 3 needs to be adjusted in pH, and the mold strength is reduced unless a specific curing accelerator is used.

  The present invention is for self-hardening mold molding, which can reduce formaldehyde odor during mold molding, while maintaining excellent storage stability without adjusting pH, and can maintain the strength of the resulting mold. A binder composition and a composition for a mold using the same are provided.

  The self-hardening mold forming binder composition of the present invention contains at least one selected from furan resin, urea, alkylene urea and alkyl urea, and the urea content is 0.8% by mass or more. It is a binder composition for self-hardening mold making having a content of 2.0% by mass or less and a pH at 25 ° C. of 6.0 or less.

  The mold composition of the present invention is a mold composition comprising refractory particles, the self-hardening mold making binder composition, and a curing agent for curing the self-hardening mold making binder composition. It is a thing.

  The method for producing a mold of the present invention comprises a method for mixing a refractory particle, a binder composition for self-hardening mold making, and a curing agent for curing the binder composition for self-hardening mold making. A mold manufacturing method including a mixing step of obtaining a composition, and a curing step of filling the mold composition in a mold and curing the mold composition.

  According to the present invention, a self-hardening mold capable of reducing the formaldehyde odor during mold molding and maintaining the strength of the mold obtained while maintaining excellent storage stability without adjusting the pH. A binder composition for molding can be provided. In addition, according to the present invention, a mold composition and a mold can be produced that are excellent in storage stability, can reduce formaldehyde odor during mold molding, and can maintain the strength of the resulting mold. A method can be provided.

  The self-hardening mold making binder composition of the present embodiment (hereinafter, also simply referred to as “binder composition”) includes at least one selected from furan resin, urea, alkylene urea, and alkyl urea. And the urea content is 0.8 mass% or more and 2.0 mass% or less, and the pH at 25 ° C. is 6.0 or less. The self-hardening binder for molding molds according to the present embodiment is capable of reducing the formaldehyde odor during mold molding, while maintaining excellent storage stability without adjusting the pH. There exists an effect that intensity | strength can be maintained. The reason for such an effect is not clear, but is considered as follows.

  Addition of urea is effective for reducing formaldehyde generated during mixing. However, when urea is added to a binder composition having a pH of 6 or less, urea reacts with aldehydes during high temperature storage to cause precipitation. Moreover, precipitation can be suppressed by adjusting the pH, but the mold strength is reduced. The binder composition for self-hardening mold making according to this embodiment can improve the solubility of the precipitate without adjusting the pH by adding alkylene urea / alkyl urea, so that the storage stability is improved. Although excellent, the formaldehyde odor at the time of mold making can be reduced, and the strength of the obtained mold can be maintained.

  Hereinafter, the components contained in the binder composition of the present embodiment will be described.

[Binder composition for self-hardening mold making]
<Furan resin>
The binder composition of the present embodiment contains a furan resin as an acid curable resin from the viewpoint of improving the curing rate of the mold and the final strength of the mold.

  In the present embodiment, a furan resin is used as the acid curable resin from the viewpoint of ease of work. The furan resin can be used without particular limitation as long as it is obtained by polymerizing a monomer composition containing furfuryl alcohol and can be used as a binder for mold making. Examples of the furan resin include furfuryl alcohol condensate, furfuryl alcohol and aldehyde condensate, furfuryl alcohol and urea condensate, furfuryl alcohol, phenol and aldehyde condensate, furfuryl alcohol. And a condensate composed of one or more selected from the group consisting of a condensate of furfuryl alcohol, urea and aldehydes, or two or more selected from the above group. Of these, from the viewpoint of improving mold strength, a condensate of furfuryl alcohol and urea, a condensate of furfuryl alcohol, melamine and aldehydes, a condensate of furfuryl alcohol, urea and aldehydes are preferred, and furfuryl alcohol and urea. A condensate of aldehydes is more preferable.

  The monomer composition used for the synthesis of the furan resin contains furfuryl alcohol, and one or more monomers selected from, for example, aldehydes, urea, phenols, and melamine are selected according to the desired condensate. And can be used.

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

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

When manufacturing the condensate of furfuryl alcohol and aldehydes, it is preferable to use 0.01-1 mol of aldehydes with respect to 1 mol of furfuryl alcohol. Moreover, when manufacturing the condensate of furfuryl alcohol, aldehydes, and urea, 0.05-3 mol of aldehydes and 0.03-1.5 mol of urea are used with respect to 1 mol of furfuryl alcohol. It is preferable to do.

  The reaction temperature when synthesizing the furan resin varies depending on the raw materials used, and the viscosity of the resulting binder composition, residual amount of aldehyde, shortening the production time, preventing runaway reaction of the furan resin, and preventing evaporation of the raw material. From a viewpoint, 50-150 degreeC is preferable, 70-130 degreeC is more preferable, and 80-130 degreeC is still more preferable. From the same viewpoint, the reaction time for synthesizing the furan resin is preferably 0.5 to 12 hours, more preferably 1 to 10 hours, and further preferably 3 to 8 hours.

  When the furan resin is produced, furan resin, furfuryl alcohol as a raw material, water contained in the raw material, water generated during the reaction, and the like are included, but it may not be removed from the viewpoint of economy. The furan resin composition contains components other than furan resin, furfuryl alcohol and furan resin, such as water.

  The content of the furan resin in the binder composition for self-hardening mold making of the present embodiment is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 65% by mass or more from the viewpoint of improving the mold strength. preferable. The content of the furan resin in the binder composition of the present embodiment is more preferably 98% by mass or less, and still more preferably 95% by mass or less, from the viewpoint of viscosity reduction. In addition, the content of the furan resin in the binder composition of the present embodiment is preferably 50 to 98 mass%, more preferably 60 to 95 mass%, from the viewpoint of improving the mold strength and reducing the viscosity. 95 mass% is still more preferable.

<Urea>
Urea in the binder composition for self-hardening mold making of the present embodiment is urea that has not undergone condensation reaction with formaldehyde or furfuryl alcohol, either remaining as an unreacted component or separately added. Either is fine. From the viewpoint of reducing formaldehyde, the urea content in the binder composition for self-hardening mold making is 0.90% by mass or more, preferably 0.95% by mass or more, and more preferably 1.00% by mass or more. preferable. From the viewpoint of reducing nitrogen gas during heating, the urea content in the self-hardening mold forming binder composition is 2.0% by mass or less, preferably 1.9% by mass or less, and 1.7% by mass. % Or less is more preferable. In addition, the urea content in the self-hardening mold forming binder composition is 0.90 to 2.0% by mass from the viewpoints of reducing formaldehyde and reducing nitrogen gas during heating. 95-1.9 mass% is preferable, and 1.00-1.70 mass% is more preferable. Urea in the binder composition for self-hardening mold making is measured by the method described in the examples.

<Alkylene urea and alkyl urea>
The binder composition for self-hardening mold making of this embodiment contains at least one selected from alkylene urea and alkyl urea.

  Examples of the alkylene urea include ethylene urea and propylene urea, which are preferable from the viewpoint of improving storage stability.

  Examples of the alkyl urea include methyl urea, ethyl urea, propyl urea, cyclohexyl urea, dimethyl urea, diethyl urea, dipropyl urea, and dicyclohexyl urea, and ethyl urea, propyl urea, and dimethyl urea are preferable.

  Among the alkylene urea and the alkyl urea, ethylene urea is more preferable from the viewpoint of improving storage stability.

  The total content of alkylene urea and alkyl urea in the self-hardening mold forming binder composition of the present embodiment is preferably 0.05% by mass or more, and 0.08% by mass from the viewpoint of improving storage stability. The above is more preferable, and 0.10% by mass or more is still more preferable. Further, the total content of alkylene urea and alkyl urea in the self-hardening mold forming binder composition of the present embodiment is preferably 3.0% by mass or less from the viewpoint of reducing nitrogen gas during heating. 0.0 mass% or less is more preferable, and 1.5 mass% or less is still more preferable. From the above viewpoint, the total content of alkylene urea and alkyl urea in the self-hardening binder composition for mold making according to this embodiment is preferably 0.05 to 3.0% by mass, and 0.08 to 2%. 0.0 mass% is more preferable, and 0.10-1.5 mass% is still more preferable.

<Urea compound>
The total content of alkylene urea, alkyl urea and urea in the self-hardening mold forming binder composition of the present embodiment is preferably 0.95% by mass or more from the viewpoint of reducing formaldehyde odor during mixing. 0.000 mass% or more is more preferable, and 1.10 mass% or more is still more preferable. In addition, the total content of alkylene urea, alkyl urea, and urea in the self-hardening mold forming binder composition of the present embodiment is preferably 3.5% by mass or less from the viewpoint of reducing nitrogen gas during heating. 3.0 mass% or less is more preferable, and 2.5 mass% or less is still more preferable. From the above viewpoint, the total content of alkylene urea and alkyl urea in the self-hardening binder composition for mold making according to this embodiment is preferably 0.95 to 3.5% by mass, and 1.00 to 3%. 0.0 mass% is more preferable, and 1.10 to 2.5 mass% is still more preferable.

<Curing accelerator>
The binder composition of the present embodiment may contain a curing accelerator from the viewpoint of preventing cracking of the mold and improving the final mold strength. As the curing accelerator, from the viewpoint of improving the final mold strength, a compound represented by the following general formula (1) (hereinafter referred to as curing accelerator (1)), a phenol derivative, an aromatic dialdehyde, and tannin. One or more selected from the group consisting of categoricals 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 . ]

  The content of the curing accelerator in the binder composition is preferably 0.5% by mass or more, more preferably 1.8% by mass or more, from the viewpoint of improving the final strength of the mold. The content is more preferably 2.5% by mass or more, and still more preferably 3.0% by mass or more. The content of the curing accelerator in the binder composition is preferably 63% by mass or less and 50% by mass from the viewpoint of improving the solubility of the curing accelerator in the furan resin and improving the final strength of the mold. % Or less is more preferable and 40% by mass or less is still more preferable.

  As the curing accelerator (1), 2,5-bishydroxymethylfuran, 2,5-bismethoxymethylfuran, 2,5-bisethoxymethylfuran, 2-hydroxymethyl-5-methoxymethylfuran, 2-hydroxy Examples include methyl-5-ethoxymethylfuran and 2-methoxymethyl-5-ethoxymethylfuran. Among these, 2,5-bishydroxymethylfuran is preferably used from the viewpoint of improving the final template strength.

  Examples of the phenol derivative include resorcin, cresol, hydroquinone, phloroglucinol, methylene bisphenol, and the like. Among these, resorcin is preferable from the viewpoint of deep moldability of the mold and the viewpoint of improving the final mold strength. The content of the phenol derivative in the binder composition is preferably 1 to 25% by mass from the viewpoint of the solubility of the phenol derivative in the furan resin and the final mold strength, It is more preferably 2 to 15% by mass, and further preferably 3 to 10% by mass. In particular, when resorcin is used, the content of resorcin in the binder composition is 1 to 10% by mass from the viewpoint of the solubility of resorcin in the furan resin and the final mold strength. It is preferable that it is 2-7 mass%, and it is still more preferable that it is 3-6 mass%.

  Examples of the aromatic dialdehyde include terephthalaldehyde, phthalaldehyde, 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 preventing cracking of the mold, terephthalaldehyde and terephthalaldehyde derivatives are preferable, and terephthalaldehyde is more preferable. The content of the aromatic dialdehyde in the binder composition is preferably 0.1 to 0.1 from the viewpoint of sufficiently dissolving the aromatic dialdehyde in the furan resin and suppressing the odor of the aromatic dialdehyde itself. It is 15 mass%, More preferably, it is 0.5-10 mass%, More preferably, it is 1-5 mass%.

Examples of tannins include condensed tannins and hydrolyzed tannins. Examples of these condensed tannins and hydrolyzed tannins include tannins having a pyrogallol skeleton and a resorcin skeleton. Moreover, you may add the extract from natural products, such as a leaf bark extract containing these tannins, and a leaf derived from a plant, a fruit, a seed | species, and a worm hump parasitic on a plant.

<Water>
The binder composition of the present embodiment 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. When using such a condensate in a binder composition, water may be removed by topping, if necessary, but it must be removed during production as long as the curing reaction rate can be maintained. There is no. Further, 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 a viscosity that is easy to handle, the water content of the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more. More preferably, it is more than mass%. However, from the viewpoint of maintaining the curing reaction rate, the water content of the binder composition is preferably 30% by mass or less, and more preferably 25% by mass or less. In addition, the water content of the binder composition is preferably 0.5 to 30% by mass from the viewpoint of adjusting the viscosity of the binder composition to an easy-to-handle viscosity and maintaining the curing reaction rate. 25 mass% is more preferable, and 3-25 mass% is still more preferable.

<Other additives>
Further, the binder composition may further contain an additive such as a silane coupling agent. For example, it is preferable that a silane coupling agent is contained in the binder composition 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-glycidoxypropylmethyldiethoxysilane Epoxy silanes such as 3-glycidoxypropyltriethoxysilane, ureido silane, mercapto silane, sulfide silane, methacryloxy silane, acryloxy silane and the like are used. Amino silane, epoxy silane, and ureido silane are preferable. More preferred are aminosilane and epoxysilane, and even more preferred is aminosilane. Among aminosilanes, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane is preferable. 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 final strength of the mold. From the same viewpoint, the content of the silane coupling agent in the binder composition is preferably 0.5% by mass or less, and more preferably 0.3% by mass or less.

  The ionic compound is an ionic compound containing one or more anions selected from the group consisting of bisulfite ion, sulfite ion, pyrosulfite ion, thiosulfate ion, thionate ion and dithionite ion.

  The ionic compound is preferably added to the binder composition in the form of a salt with a cation. Sulfurous acid salt as bisulfite ion compound, sulfite salt as sulfite ion compound, pyrosulfite salt as pyrosulfite ion compound, thiosulfate salt as thiosulfate ion compound, tetrathionate salt as dithionate compound, dithione A salt of dithionite can be used as the acid ion compound. From the viewpoint of improving the mold curing speed and mold strength, the anions are preferably thiosulfate ions, hydrogen sulfite ions and sulfite ions, more preferably thiosulfate ions and hydrogen sulfite ions, and even more preferably thiosulfate ions.

  When a salt is used as the ionic compound, a metal salt is given as a cation in the ionic compound. Examples of the metal salt include monovalent, divalent and trivalent metals. From the viewpoint of improving the storage stability of the binder composition, a metal having a valence of 2 or less is preferred, and a monovalent metal is more preferred.

  The cation in the ionic compound of the present embodiment is one or more elements selected from the group consisting of elements of Group 1, Group 2 and Group 12 of the periodic table from the viewpoint of improving the mold curing rate and mold strength. A cation (metal ion) is preferable, a cation consisting of one or more elements selected from the group consisting of Group 1 and Group 2 elements of the Periodic Table is more preferable, and than Group 1 elements of the Periodic Table A cation composed of one or more elements selected from the group is more preferred. From the same viewpoint, Na ion and K ion are preferable in the first group of the periodic table, and Na ion is more preferable. From the same point of view, Mg ion and Ca ion are preferable in Group 2 of the periodic table, and Zn ion is preferable in Group 12 of the periodic table. Among the elements of Groups 1, 2 and 12 of the periodic table, from the same viewpoint, Na ion, K ion, Mg ion, Ca ion and Zn ion are preferable, Na ion and K ion are more preferable, Na Ions are more preferred.

Specific examples of the salt of hydrogen sulfite ion (HSO ₃ ⁻ ) include sodium hydrogen sulfite, potassium hydrogen sulfite, lithium hydrogen sulfite, magnesium hydrogen sulfite, calcium hydrogen sulfite, zinc hydrogen sulfite and the like.

Specific examples of the salt of sulfite ion (SO ₃ ²⁻ ) include sodium sulfite (anhydrous or heptahydrate), potassium sulfite, lithium sulfite, magnesium sulfite (hexahydrate), calcium sulfite (1/2 water) Japanese hydrate), zinc sulfite (dihydrate), barium sulfite, bismuth sulfite, silver sulfite and the like.

Specific examples of the salt of pyrosulfite ion (S ₂ O ₅ ²⁻ ) include sodium pyrosulfite, potassium pyrosulfite, magnesium pyrosulfite, calcium pyrosulfite, and zinc pyrosulfite.

Specific examples of the salt of thiosulfate ion (S ₂ O ₃ ²⁻ ) include sodium thiosulfate (anhydrous or pentahydrate), potassium thiosulfate, barium thiosulfate (monohydrate), magnesium thiosulfate (6 Hydrate), calcium thiosulfate, zinc thiosulfate and the like.

Specific examples of the salt of thionate ion (S _X O ₆ ²⁻ ) include sodium tetrathionate (dihydrate) potassium tetrathionate, magnesium tetrathionate, calcium tetrathionate, zinc tetrathionate and the like.

Specific examples of the salt of dithionite ion (S ₂ O ₄ ²⁻ ) include sodium dithionite, potassium dithionite, magnesium dithiothionite, calcium dithionite, zinc dithionite and the like.

  Among these ionic compounds, sodium bisulfite, potassium bisulfite, sodium sulfite, sodium thiosulfate, potassium thiosulfate, magnesium thiosulfate, calcium thiosulfate, sodium tetrathionate from the viewpoint of improving the mold curing speed and mold strength. And sodium dithionite, sodium bisulfite, potassium bisulfite, sodium sulfite, sodium thiosulfate, potassium thiosulfate, magnesium thiosulfate and calcium thiosulfate are more preferred, sodium thiosulfate, potassium thiosulfate, magnesium thiosulfate and Calcium thiosulfate is more preferable, and sodium thiosulfate is still more preferable.

  Quantitative analysis of bisulfite ion, sulfite ion, pyrosulfite ion, thiosulfate ion, thionate ion and dithionite ion can be confirmed by ion chromatography and elemental analysis for the measurement of anion content in ionic compounds . Further, alkali metals of these salts can be qualitatively and quantitatively analyzed by ICP emission spectrometry.

  The content of the ionic compound is preferably 0.006% by mass or more, more preferably 0.09% by mass or more in the binder composition, from the viewpoint of improving the curing rate of the mold and improving the mold strength. More preferred is 0.02% by mass or more. The content of the ionic compound is preferably 0.6% by mass or less, more preferably 0.5% by mass or less in the binder composition from the viewpoint of storage stability of the binder composition. More preferably, it is 2% by mass or less. From the above viewpoint, the content of the ionic compound is preferably 0.006 to 0.6% by mass in the binder composition, more preferably 0.09 to 0.5% by mass, and 0.02 -0.2 mass% is still more preferable.

  From the viewpoint of improving the mold strength, the self-hardening binder composition for mold making of the present embodiment has a pH at 25 ° C. of 6.0 or less, preferably 5.5 or less, and more preferably 5.0 or less. The lower limit of the pH is not particularly limited, but is preferably 2.0 or more from the viewpoint of suppressing metal corrosion. In order to control the pH of the self-hardening mold making binder composition within the above range, the self-hardening mold making binder composition may be added to an alkaline aqueous solution such as sodium hydroxide aqueous solution or potassium hydroxide aqueous solution, or It can adjust by adding acidic aqueous solution, such as acidic aqueous solution. In addition, in this specification, pH is measured by the method as described in an Example.

[Mold composition]
The binder composition of this embodiment can be mixed with refractory particles and a curing agent to form a mold composition. The mold composition of this embodiment contains the binder composition of this embodiment, refractory particles and a curing agent.

  As the refractory particles, conventionally known ones such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, etc. can be used. Recycled ones can also be used.

  The said hardening | curing agent is a hardening | curing agent which hardens the binder composition of this embodiment. Examples of the curing agent include xylene sulfonic acid (particularly m-xylene sulfonic acid), toluene sulfonic acid (particularly p-toluene sulfonic acid), sulfonic acid compounds such as methane sulfonic acid, phosphoric acid, acidic phosphoric acid ester, and the like. One or more conventionally known compounds such as an acidic aqueous solution containing phosphoric acid compound, sulfuric acid and the like can be used. Further, the curing agent may contain one or more solvents selected from the group consisting of alcohols, ether alcohols and esters, and carboxylic acids. Among these, alcohols and ether alcohols are preferable and ether alcohols are more preferable from the viewpoint of improving the final mold strength. Moreover, when the said solvent and the said carboxylic acid are contained, since the moisture content in a hardening | curing agent is reduced, final mold intensity | strength further improves. The content of the solvent or the carboxylic acid in the curing agent is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass, from the viewpoint of improving the final mold strength. Moreover, it is preferable to contain methanol and ethanol from a viewpoint of reducing the viscosity of a hardening | curing agent.

  From the viewpoint of improving the final mold strength, the alcohols are preferably propanol, butanol, pentanol, hexanol, heptanol, octanol, benzyl alcohol, and the ether alcohols include 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, ethylene glycol monophenyl ether are preferred, and the esters include butyl acetate, butyl benzoate, Ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl Ether acetate are preferred. As the carboxylic acids, a carboxylic acid having a hydroxyl group is preferable, and lactic acid, citric acid, and malic acid are more preferable from the viewpoint of improving the final template strength and reducing odor.

  In the mold composition of the present embodiment, the ratio of the refractory particles, the binder composition, and the curing agent can be appropriately set, but from the viewpoint of improving the mold curing rate and the mold final strength, the fire resistance The binder composition is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the conductive particles, and 1.5 parts by mass with respect to 100 parts by mass of the refractory particles from the viewpoint of economy and improvement in casting quality. Part or less is preferred. From the viewpoint of improving the curing rate of the mold and the final strength of the mold, the curing agent is preferably 0.07 parts by mass or more with respect to 100 parts by mass of the refractory particles. From a viewpoint, 1.0 mass part or less is preferable with respect to 100 mass parts of refractory particles.

  Furthermore, the mass ratio of the binder composition to the curing agent is 20 masses for the curing agent with respect to 100 mass parts of the binder composition from the viewpoint of improving the curing rate of the mold and the final strength of the mold. Part or more is preferable, and 30 parts by mass or more is more preferable. The mass ratio of the binder composition and the curing agent is preferably 60 parts by mass or less, and 50 parts by mass or less, with respect to 100 parts by mass of the binder composition, from the viewpoints of economy and improved casting quality. Is more preferable.

  Furthermore, the content of the curing agent is 10 masses of the curing agent with respect to 100 parts by mass of the furan resin in the binder composition from the viewpoint of minimizing the amount of water contained in the mold and the mixing efficiency in the mixer. Part or more is preferable, and 15 parts by mass or more is more preferable. The mass ratio of the binder composition and the curing agent is preferably 40 parts by mass or less, and 35 parts by mass or less with respect to 100 parts by mass of the binder composition, from the viewpoints of economy and improved casting quality. Is more preferable, and 25 parts by mass or less is still more preferable.

  The binder composition of this embodiment is suitably used for mold production.

[Mold manufacturing method]
A mold can be produced by curing the mold composition of the present embodiment. In the mold manufacturing method of the present embodiment, the mold can be manufactured using the conventional mold manufacturing process as it is. As a preferred mold production method, a mold composition is obtained by mixing refractory particles, a mold-forming binder composition of the present embodiment, and a curing agent for curing the mold-molding binder composition. Examples thereof include a mixing step and a method for producing a mold having a curing step of filling the mold composition in a mold and curing the mold composition.

  In relation to the above-described embodiment, the present invention further discloses the following composition, production method, or application.

<1> Furan resin, urea, and at least one selected from alkylene urea and alkyl urea are contained, the urea content is 0.8% by mass or more and 2.0% by mass or less, and 25 ° C. A binder composition for molding a self-hardening mold having a pH of 6.0 or less.

〔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。〕
＜１３＞更に、水分を含有し、粘結剤組成物中の水分含有量が、好ましくは０．５質量％以上であり、より好ましくは１質量％以上であり、更に好ましくは３質量％以上であり、好ましくは３０質量％以下であり、より好ましくは２５質量％以下であり、好ましくは０．５〜３０質量％であり、より好ましくは１〜２５質量％であり、更に好ましくは３〜２５質量％である前記＜１＞〜＜１２＞の何れかの鋳型造型用粘結剤組成物。
＜１４＞更に、シランカップリング剤を含有する、前記＜１＞〜＜１３＞の何れかの鋳型造型用粘結剤組成物。
＜１５＞前記シランカップリング剤の含有量が、好ましくは０．０１質量％以上、より好ましくは０．０５質量％以上であり、好ましくは０．５質量％以下、より好ましくは０．３質量％以下である、前記＜１４＞の鋳型造型用粘結剤組成物。
＜１６＞前記シランカップリング剤がＮ−β−（アミノエチル）−γ−アミノプロピルメチルジメトキシシランである前記＜１４＞又は＜１５＞の鋳型造型用粘結剤組成物。
＜１７＞２５℃におけるｐＨが、好ましくは６．０以下であり、より好ましくは５．５以下であり、更に好ましくは５．０以下であり、好ましくは２．０以上である、前記＜１＞〜＜１６＞の何れかの鋳型造型用粘結剤組成物。
＜１８＞耐火性粒子と、前記＜１＞〜＜１７＞の何れかの鋳型造型用粘結剤組成物と、前記鋳型造型用粘結剤組成物を硬化させる硬化剤とを含有する、鋳型用組成物。
＜１９＞前記耐火性粒子と前記粘結剤組成物と前記硬化剤との比率が、前記耐火性粒子１００質量部に対して、前記粘結剤組成物が好ましくは０．５質量部以上１．５質量部以下で、前記硬化剤が好ましくは０．０７質量部以上１．０質量部以下である、前記＜１８＞の鋳型用組成物。
＜２０＞前記粘結剤組成物と前記硬化剤の質量比は、前記粘結剤組成物１００質量部に対して、好ましくは硬化剤２０質量部以上、より好ましくは３０質量部以上であり、好ましくは硬化剤６０質量部以下、より好ましくは５０質量部以下である、前記＜１８＞又は＜１９＞の鋳型用組成物。
＜２１＞前記硬化剤の含有量が、粘結剤組成物中のフラン樹脂１００質量部に対して好ましくは１０質量部以上であり、より好ましくは１５質量部以上であり、好ましくは４０質量部以下であり、より好ましくは３５質量部以下であり、更に好ましくは２５質量部以下である、前記＜１８＞〜＜２０＞の何れかの鋳型用組成物。
＜２２＞前記耐火性粒子と、前記＜１＞〜＜１７＞の何れかの鋳型造型用粘結剤組成物と、前記鋳型造型用粘結剤組成物を硬化させる硬化剤とを混合して、鋳型用組成物を得る混合工程、及び前記鋳型用組成物を型枠に詰め、当該鋳型用組成物を硬化する硬化工程を含む鋳型の製造方法。
＜２３＞フラン樹脂、尿素、並びにアルキレン尿素及びアルキル尿素から選ばれる少なくともいずれか１つを含有し、当該尿素の含有量が０．８質量％以上２．０質量％以下であり、かつ２５℃におけるｐＨが６．０以下である組成物の、自硬性鋳型造型用粘結剤組成物としての使用。
＜２４＞前記フラン樹脂が、好ましくはフルフリルアルコールの縮合物、フルフリルアルコールとアルデヒド類の縮合物、フルフリルアルコールと尿素の縮合物、フルフリルアルコールとフェノール類とアルデヒド類の縮合物、フルフリルアルコールとメラミンとアルデヒド類の縮合物、フルフリルアルコールと尿素とアルデヒド類の縮合物よりなる群から選ばれる１種以上、又は前記群から選ばれる２種以上からなる共縮合物、より好ましくはフルフリルアルコールと尿素の縮合物、フルフリルアルコールとメラミンとアルデヒド類の縮合物、フルフリルアルコールと尿素とアルデヒド類の縮合物、更に好ましくはフルフリルアルコールと尿素とアルデヒド類の縮合物である前記＜２３＞の使用。
＜２５＞前記フラン樹脂の含有量が、好ましくは５０質量％以上、より好ましくは６０質量％以上、更に好ましくは６５質量％以上、好ましくは９８質量％以下、より好ましくは９５質量％以下、好ましくは５０〜９８質量％、より好ましくは６０〜９５質量％、更に好ましくは６５〜９５質量％である前記＜２３＞又は＜２４＞の使用。
＜２６＞前記尿素の含有量が、好ましくは０．９０質量％以上、より好ましくは０．９５質量％以上、更に好ましくは１．００質量％以上、好ましくは２．０質量％以下、より好ましくは１．９質量％以下、更に好ましくは１．７質量％以下、好ましくは０．９０〜２．０質量％、より好ましくは０．９５〜１．９質量％、更に好ましくは１．００〜１．７０質量％である前記＜２３＞〜＜２５＞の何れかの使用。
＜２７＞前記アルキレン尿素が、好ましくはエチレン尿素及び／又はプロピレン尿素である前記＜２３＞〜＜２６＞の何れかの使用。
＜２８＞前記アルキレン尿素が、好ましくは、エチレン尿素、プロピレン尿素よりなる群から選ばれる１種以上である前記＜２３＞〜＜２７＞の何れかの使用。
＜２９＞前記アルキル尿素が、好ましくは、メチル尿素、エチル尿素、プロピル尿素、シクロヘキシル尿素、ジメチル尿素、ジエチル尿素、ジプロピル尿素、ジシクロヘキシル尿素、エチル尿素、プロピル尿素、ジメチル尿素よりなる群から選ばれる１種以上である前記＜２３＞〜＜２８＞の何れかの使用。
＜３０＞前記アルキレン尿素及び前記アルキル尿素の合計の含有量が、好ましくは０．０５質量％以上、より好ましくは０．０８質量％以上、更に好ましくは０．１０質量％以上、好ましくは３．０質量％以下、より好ましくは２．０質量％以下、更に好ましくは１．５質量％以下、好ましくは０．０５〜３．０質量％、より好ましくは０．０８〜２．０質量％、更に好ましくは０．１０〜１．５質量％である前記＜２３＞〜＜２９＞の何れかの使用。
＜３１＞更に、硬化促進剤を含有する前記＜２３＞〜＜３０＞の何れかの使用。
＜３２＞前記硬化促進剤の含有量が、好ましくは０．５質量％以上、より好ましくは１．８質量％以上、更に好ましくは２．５質量％以上、より更に好ましくは３．０質量％以上であり、好ましくは６３質量％以下、より好ましくは５０質量％以下、更に好ましくは４０質量％以下である、前記＜３１＞の使用。
＜３３＞前記硬化促進剤が、下記一般式（１）で表される硬化促進剤（１）、多価フェノール類、及び芳香族ジアルデヒドからなる群より選ばれる１種以上である前記＜３１＞又は＜３２＞の使用。

〔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。〕
＜３４＞更に、水分を含有し、粘結剤組成物中の水分含有量が、好ましくは０．５質量％以上であり、より好ましくは１質量％以上であり、更に好ましくは３質量％以上であり、好ましくは３０質量％以下であり、より好ましくは２５質量％以下であり、好ましくは０．５〜３０質量％であり、より好ましくは１〜２５質量％であり、更に好ましくは３〜２５質量％である前記＜２３＞〜＜３３＞の何れかの使用。
＜３５＞更に、シランカップリング剤を含有する、前記＜２３＞〜＜３４＞の何れかの使用。
＜３６＞前記シランカップリング剤の含有量が、好ましくは０．０１質量％以上、より好ましくは０．０５質量％以上であり、好ましくは０．５質量％以下、より好ましくは０．３質量％以下である、前記＜３５＞の使用。
＜３７＞前記シランカップリング剤がＮ−β−（アミノエチル）−γ−アミノプロピルメチルジメトキシシランである前記＜３５＞又は＜３６＞の使用。
＜３８＞２５℃におけるｐＨが、好ましくは６．０以下であり、より好ましくは５．５以下であり、更に好ましくは５．０以下であり、好ましくは２．０以上である、前記＜２３＞〜＜３７＞の何れかの使用。 <2> The furan resin is preferably a furfuryl alcohol condensate, a furfuryl alcohol / aldehyde condensate, a furfuryl alcohol / urea condensate, a furfuryl alcohol / phenol condensate / aldehyde condensate, One or more selected from the group consisting of furyl alcohol, melamine and aldehydes, one or more selected from the group consisting of furfuryl alcohol, urea and aldehydes, or a cocondensate consisting of two or more selected from the above group, more preferably The condensate of furfuryl alcohol and urea, the condensate of furfuryl alcohol, melamine and aldehydes, the condensate of furfuryl alcohol, urea and aldehydes, more preferably the condensate of furfuryl alcohol, urea and aldehydes. <1> a binder composition for self-hardening mold making.
<3> The content of the furan resin is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 65% by mass or more, preferably 98% by mass or less, more preferably 95% by mass or less, preferably Is 50 to 98% by mass, more preferably 60 to 95% by mass, and still more preferably 65 to 95% by mass, <1> or <2> the binder composition for self-hardening mold making.
<4> The urea content is preferably 0.90% by mass or more, more preferably 0.95% by mass or more, still more preferably 1.00% by mass or more, preferably 2.0% by mass or less, more preferably Is 1.9% by mass or less, more preferably 1.7% by mass or less, preferably 0.90 to 2.0% by mass, more preferably 0.95 to 1.9% by mass, and still more preferably 1.00 to 1.00% by mass. The binder composition for self-hardening mold making according to any one of <1> to <3>, which is 1.70% by mass.
<5> The self-hardening mold forming binder composition according to any one of <1> to <4>, wherein the alkylene urea is preferably ethylene urea and / or propylene urea.
<6> The self-hardening mold forming binder composition according to any one of <1> to <5>, wherein the alkylene urea is preferably one or more selected from the group consisting of ethylene urea and propylene urea.
<7> The alkyl urea is preferably selected from the group consisting of methyl urea, ethyl urea, propyl urea, cyclohexyl urea, dimethyl urea, diethyl urea, dipropyl urea, dicyclohexyl urea, ethyl urea, propyl urea, dimethyl urea. The self-hardening mold forming binder composition according to any one of <1> to <6>, wherein the composition is a seed or more.
<8> The total content of the alkylene urea and the alkyl urea is preferably 0.05% by mass or more, more preferably 0.08% by mass or more, still more preferably 0.10% by mass or more, preferably 3. 0 mass% or less, more preferably 2.0 mass% or less, still more preferably 1.5 mass% or less, preferably 0.05 to 3.0 mass%, more preferably 0.08 to 2.0 mass%, More preferably, the binder composition for self-hardening mold making according to any one of <1> to <7>, which is 0.10 to 1.5% by mass.
<9> The total content of alkylene urea, alkyl urea, and urea is preferably 0.95% by mass or more, more preferably 1.00% by mass or more, further preferably 1.10% by mass or more, preferably 3 0.5% by mass or less, more preferably 3.0% by mass or less, further preferably 2.5% by mass or less, preferably 0.95-3.5% by mass, more preferably 1.00-3.0% by mass. More preferably, the binder composition for self-hardening mold making according to any one of <1> to <8>, which is 1.10 to 2.5% by mass.
<10> The binder composition for mold making according to any one of <1> to <9>, further comprising a curing accelerator.
<11> The content of the curing accelerator is preferably 0.5% by mass or more, more preferably 1.8% by mass or more, still more preferably 2.5% by mass or more, and still more preferably 3.0% by mass. It is above, Preferably it is 63 mass% or less, More preferably, it is 50 mass% or less, More preferably, it is 40 mass% or less, The binder composition for mold making of said <10>.
<12> Said <10>, wherein the curing accelerator is at least one selected from the group consisting of a curing accelerator (1) represented by the following general formula (1), a polyhydric phenol, and an aromatic dialdehyde. > Or <11> a binder composition for mold making.

[Wherein, X ₁ and X ₂ each represent a hydrogen atom, CH ₃ or C ₂ H ₅ . ]
<13> Further, water is contained, and the water content in the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 3% by mass or more. Preferably 30% by mass or less, more preferably 25% by mass or less, preferably 0.5 to 30% by mass, more preferably 1 to 25% by mass, and still more preferably 3 to 3% by mass. The binder composition for mold making according to any one of <1> to <12>, wherein the composition is 25% by mass.
<14> The binder composition for mold making according to any one of <1> to <13>, further comprising a silane coupling agent.
<15> The content of the silane coupling agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, preferably 0.5% by mass or less, more preferably 0.3% by mass. % Or less, the binder composition for mold making according to the above <14>.
<16> The binder composition for molding according to the above <14> or <15>, wherein the silane coupling agent is N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane.
<17> The pH at 25 ° C. is preferably 6.0 or less, more preferably 5.5 or less, still more preferably 5.0 or less, and preferably 2.0 or more, <1 The binder composition for mold making according to any one of> to <16>.
A mold comprising <18> refractory particles, a binder for molding a mold according to any one of <1> to <17>, and a curing agent for curing the binder composition for molding. Composition.
<19> The ratio of the refractory particles, the binder composition, and the curing agent is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the refractory particles. <18> The mold composition according to the above <18>, wherein the curing agent is preferably in the range of 0.07 parts by mass to 1.0 part by mass.
<20> The mass ratio of the binder composition and the curing agent is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, with respect to 100 parts by mass of the binder composition. The mold composition according to <18> or <19>, preferably 60 parts by mass or less, more preferably 50 parts by mass or less.
<21> The content of the curing agent is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and preferably 40 parts by mass with respect to 100 parts by mass of the furan resin in the binder composition. The composition for a mold according to any one of the above <18> to <20>, which is below, more preferably 35 parts by mass or less, and still more preferably 25 parts by mass or less.
<22> Mixing the refractory particles, the binder for mold making according to any one of <1> to <17>, and a curing agent for curing the binder composition for mold making. A mold production method comprising: 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.
<23> Furan resin, urea, and at least one selected from alkylene urea and alkyl urea, the urea content is 0.8% by mass or more and 2.0% by mass or less, and 25 ° C. Use of a composition having a pH of 6.0 or less as a binder composition for self-hardening mold making.
<24> The furan resin is preferably a furfuryl alcohol condensate, a furfuryl alcohol and aldehyde condensate, a furfuryl alcohol and urea condensate, a furfuryl alcohol, a phenol and an aldehyde condensate, One or more selected from the group consisting of furyl alcohol, melamine and aldehydes, one or more selected from the group consisting of furfuryl alcohol, urea and aldehydes, or a cocondensate consisting of two or more selected from the above group, more preferably The condensate of furfuryl alcohol and urea, the condensate of furfuryl alcohol, melamine and aldehydes, the condensate of furfuryl alcohol, urea and aldehydes, more preferably the condensate of furfuryl alcohol, urea and aldehydes. Use of <23>.
<25> The content of the furan resin is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 65% by mass or more, preferably 98% by mass or less, more preferably 95% by mass or less, preferably Is 50 to 98 mass%, more preferably 60 to 95 mass%, still more preferably 65 to 95 mass%, the use of <23> or <24> above.
<26> The urea content is preferably 0.90% by mass or more, more preferably 0.95% by mass or more, still more preferably 1.00% by mass or more, preferably 2.0% by mass or less, more preferably Is 1.9% by mass or less, more preferably 1.7% by mass or less, preferably 0.90 to 2.0% by mass, more preferably 0.95 to 1.9% by mass, and still more preferably 1.00 to 1.00% by mass. Any use of <23> to <25>, which is 1.70% by mass.
<27> The use according to any one of <23> to <26>, wherein the alkylene urea is preferably ethylene urea and / or propylene urea.
<28> The use according to any one of <23> to <27>, wherein the alkylene urea is preferably one or more selected from the group consisting of ethylene urea and propylene urea.
<29> The alkyl urea is preferably selected from the group consisting of methyl urea, ethyl urea, propyl urea, cyclohexyl urea, dimethyl urea, diethyl urea, dipropyl urea, dicyclohexyl urea, ethyl urea, propyl urea, dimethyl urea. Any use of <23> to <28>, which is a seed or more.
<30> The total content of the alkylene urea and the alkyl urea is preferably 0.05% by mass or more, more preferably 0.08% by mass or more, still more preferably 0.10% by mass or more, preferably 3. 0 mass% or less, more preferably 2.0 mass% or less, still more preferably 1.5 mass% or less, preferably 0.05 to 3.0 mass%, more preferably 0.08 to 2.0 mass%, The use of any one of <23> to <29>, more preferably 0.10 to 1.5% by mass.
<31> The use of any one of <23> to <30>, further comprising a curing accelerator.
<32> The content of the curing accelerator is preferably 0.5% by mass or more, more preferably 1.8% by mass or more, still more preferably 2.5% by mass or more, and still more preferably 3.0% by mass. The use of <31> above, preferably 63% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.
<33> The above <31, wherein the curing accelerator is at least one selected from the group consisting of a curing accelerator (1) represented by the following general formula (1), a polyhydric phenol, and an aromatic dialdehyde. > Or <32>.

[Wherein, X ₁ and X ₂ each represent a hydrogen atom, CH ₃ or C ₂ H ₅ . ]
<34> Further, water is contained, and the water content in the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 3% by mass or more. Preferably 30% by mass or less, more preferably 25% by mass or less, preferably 0.5 to 30% by mass, more preferably 1 to 25% by mass, and still more preferably 3 to 3% by mass. Any one of the above <23> to <33>, which is 25% by mass.
<35> Furthermore, the use in any one of said <23>-<34> containing a silane coupling agent.
<36> The content of the silane coupling agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, preferably 0.5% by mass or less, more preferably 0.3% by mass. % <35> or less.
<37> Use of <35> or <36>, wherein the silane coupling agent is N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane.
<38> The pH at 25 ° C. is preferably 6.0 or less, more preferably 5.5 or less, still more preferably 5.0 or less, and preferably 2.0 or more, <23 Use of any of> to <37>.

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

(Examples 1-7, Comparative Examples 1-10)
41.1 parts by weight of furfuryl alcohol urea formaldehyde resin having a molar ratio of furfuryl alcohol / formaldehyde / urea of 2.5 / 3.6 / 1, 28.6 parts by weight of furfuryl alcohol, 14.6 parts by weight of water Parts, 0.2 parts by mass of N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane as a silane coupling agent, 0.1 parts by mass of 30% sodium thiosulfate, and 2 parts by mass of other components were mixed, A furan resin composition was obtained. The furan resin composition, furfuryl alcohol, water, urea, caustic potash, ethylene urea, and ethyl urea were added to obtain a binder composition having the composition shown in Table 1.

〔Evaluation method〕
<PH of binder composition>
The pH of the binder composition was measured with a pH meter at 25 ° C. by mixing the binder composition, the binder composition and an equal amount of ion-exchanged water.

<Storage stability of caking composition>
100 g of the obtained resin was packed in a 110 cc glass screw tube, stored in a thermostatic bath at 35 ° C., and observed visually every day. The day when the occurrence of precipitation was clearly confirmed was expressed as the number of days elapsed from the start date. In the table, “90 days or more” indicates that no precipitation was observed on the 90th day.

<Amount of aldehyde generated>
Under an atmosphere of 25 ° C. and 55% RH, with respect to 2000 parts by mass of regenerated silica sand, a xylene sulfonic acid / sulfuric acid-based curing agent [Kaolite Curing Agent US-3 manufactured by Kao Quaker Co., Ltd .; -21 mixture (adjusted so that the mass ratio is equivalent to the curing speed)] 8.0 parts by mass, then 20.0 parts by mass of the above-mentioned binder composition prepared in advance was added. By mixing, kneaded sand was obtained. 50 g of the obtained kneaded sand was collected in a 1 L plastic container, capped, and 60 minutes later, the amount of formaldehyde in the plastic container was measured. The measuring method is that a formaldehyde detector tube (Gastech, 91L) is inserted at the tip through a hole formed in the upper part of the plastic container, and suction is continued for 1.5 minutes with a gas collector (Gastech, GV-100S). I went twice. And the indicated value discolored in the detection tube was defined as the amount of formaldehyde generated.

<Moisture in the binder composition>
It was measured by a moisture test method for chemical products shown in JIS K 0068.

<Urea content in binder composition>
Urea in the self-hardening mold forming binder composition was measured by the following LC / MS analysis operation.
(LC / MS analysis conditions)
Column: TSK-gelAmido80 (4.6 mmφ × 250 mm)
Mobile phase: acetonitrile / water = 95/5 (isocratic)
Column oven: 40 ° C
Flow rate: 1.0 mL / min (MS introduction split: 1/4)
Detection: MSD (SIM): POSI detection m / z: 60.1 ± 10
Resolution 0.5 amu, DWELLTIME: 250 msec, ion source heater: 300 ° C.
Analysis time: 15 minutes Sample preparation: diluted with acetone / water = 95/5

  About the obtained binder composition, each item was evaluated by the method mentioned above. The results are shown in Table 1. It was confirmed that all of Examples 1 to 7 were at levels that could be used when evaluated as mold binders. In Comparative Example 7, the initial strength when used as a mold binder was not obtained, and it was not at a usable level. Comparative Example 10 was not evaluated because the amount of formaldehyde generated was large and the odor was significant.

Claims (6)

  It contains at least one selected from furan resin, urea, alkylene urea and alkyl urea, the urea content is 0.8% by mass or more and 2.0% by mass or less, and the pH at 25 ° C. A binder composition for self-hardening mold making which is 6.0 or less.   The binder composition for self-hardening mold making according to claim 1, wherein the alkylene urea is ethylene urea and / or propylene urea. The total content of alkylene urea and alkyl urea is 0 . It is 05 mass % or more and 3.0 mass % or less, The binder composition for self-hardening mold making of Claim 1 or 2.   Furthermore, the binder composition for self-hardening mold making of any one of Claims 1-3 which contains 3 mass% or more of water.   It contains a refractory particle, a binder composition for self-hardening mold making according to any one of claims 1 to 4, and a curing agent for curing the binder composition for self-hardening mold making. Mold composition.   A refractory particle, a binder composition for self-hardening mold making according to any one of claims 1 to 4, and a curing agent for curing the binder composition for self-hardening mold making are mixed. A mold manufacturing method including a mixing step of obtaining a mold composition and a curing step of filling the mold composition into a mold and curing the mold composition.