JP5635347B2 - Self-hardening mold composition - Google Patents

Description

  The present invention relates to a composition for a self-hardening mold.

  Self-hardening molds, especially acid-hardening self-hardening molds, include self-hardening mold-forming binder compositions containing acid-hardening resins such as furan resin in refractory particles such as silica sand, phosphoric acid, organic It is manufactured by adding a curing agent containing sulfonic acid, sulfuric acid and the like, kneading them, filling the obtained kneaded sand into a mold such as a wooden mold, and curing the acid curable resin.

  Examples of the furan resin include furfuryl alcohol, furfuryl alcohol / urea formaldehyde resin, furfuryl alcohol / formaldehyde resin, furfuryl alcohol / phenol / formaldehyde resin, and other known modified furan resins.

  In order to improve the strength of the mold, Patent Literature 1 discloses an acid curable refractory granular material composition for molding which contains a specific solvent, and Patent Literature 2 contains a chlorinated organic solvent. A binder composition for mold making is disclosed. Patent Document 3 discloses an organic foamed flow self-hardening mold composition containing a polyhydric alcohol as an additive. Patent Document 4 discloses a diluent such as ketones or polyhydric alcohols. A binder composition for castings is disclosed.

WO99 / 14003 publication JP 2009-269062 A JP-A-2-21929 JP 62-28041 A

  As a condition for improving the productivity of the acid curable self-hardening mold, the deep part curability is good. Deep part curability refers to the curing performance of a portion that does not come in contact with the outside air (a portion that is in contact with the prototype) when the prototype is filled with kneaded sand. Since the curing reaction of the acid curable resin proceeds by a dehydration condensation reaction, the curing of the deep portion of the mold that is not exposed to the outside air is considered to be slow because the reaction water is not easily removed. Usually, the deep part of the mold is important because it is a contact part with an original mold such as a wooden mold and is a part forming the surface of the casting. Accordingly, there is a need for a binder composition that is not only fast but also needs to be sufficiently cured, and that is suitable for it, that is, has good deep part curability.

  However, when a mold is produced using the binder composition of Patent Documents 1, 3 and 4, the mold deep-curing property is not sufficient, and depending on the conditions, the mold deep-curing is slow so that productivity is improved. It was difficult to make. Moreover, when manufacturing using the binder composition of patent document 2, it is described that hydrochloric acid is produced | generated because it uses a chlorinated solvent, and also the chlorinated solvent itself to be used is safe. There is a problem.

  The present invention provides a self-hardening mold composition that can improve the deep curability of the mold.

The self-hardening mold composition of the present invention is a self-hardening mold composition comprising a mixture of a refractory particle, a binder composition containing an acid-curable resin, and a curing agent. At least one selected from the group consisting of a dihydric alcohol represented by the formula (1), an ether group-containing dihydric alcohol represented by the following general formula (2), and a ketone represented by the following general formula (3). A self-hardening mold composition containing 0.0049 to 0.069% by weight of the compound (A) in the self-hardening mold composition.
HO—R ¹ —OH (1)
(R ¹ is an alkylene group having 2 to 8 carbon atoms.)
HO— (R ² O) _n —H (2)
(R ² is an alkylene group having 2 to 4 carbon atoms, and n is a number of 2 to 5)
R ³ —CO—R ⁴ (3)
(R ³ and R ⁴ are each a hydrocarbon group having 1 to 6 carbon atoms, and when R ³ and R ⁴ form a ring, the total number of carbon atoms of R ³ and R ⁴ is an alkylene group having 3 to 6 carbon atoms. is there.)

Further, the binder composition of the present invention is a binder composition containing an acid curable resin, and is represented by a dihydric alcohol represented by the following general formula (1) and the following general formula (2). At least one compound (A) selected from the group consisting of an ether group-containing dihydric alcohol and a ketone represented by the following general formula (3) is added to the binder composition in an amount of 0.5-7. It is a binder composition containing 0% by weight.
HO—R ¹ —OH (1)
(R ¹ is an alkylene group having 2 to 8 carbon atoms.)
HO— (R ² O) _n —H (2)
(R ² is an alkylene group having 2 to 4 carbon atoms, and n is a number of 2 to 5)
R ³ —CO—R ⁴ (3)
(R ³ and R ⁴ are each a hydrocarbon group having 1 to 6 carbon atoms, and when R ³ and R ⁴ form a ring, the total number of carbon atoms of R ³ and R ⁴ is an alkylene group having 3 to 6 carbon atoms. is there.)

  Moreover, the manufacturing method of the self-hardening mold of this invention is a manufacturing method of the self-hardening mold which has the process of hardening the said composition for self-hardening molds of this invention.

  According to the self-hardening mold composition, the pressure-sensitive adhesive composition, and the self-hardening mold manufacturing method of the present invention, it is possible to improve the deep curability of the mold.

  The self-hardening mold composition of the present invention is a self-hardening mold composition comprising a mixture of a refractory particle, a binder composition containing an acid curable resin, and a curing agent. From the dihydric alcohol (A1) represented by the formula (1), the ether group-containing dihydric alcohol (A2) represented by the general formula (2), and the ketone (A3) represented by the general formula (3). A self-hardening mold composition containing 0.0049 to 0.069 wt% of at least one compound (A) selected from the group consisting of the above-mentioned self-hardening mold composition.

  The compound (A) used in the present invention is composed of a solvent such as diol, but it is considered that the solvent such as diol surrounds water generated in the curing reaction by hydrogen bonding via an oxygen atom (hydroxyl group). Due to the dehydrating action, this is presumed to improve deep hardening. Hereinafter, the components contained in the self-hardening mold composition of the present invention will be described.

≪Binder composition≫
The binder composition used in the present invention contains an acid curable resin.

<Acid curable resin>
Examples of the acid curable resin include furfuryl alcohol, furfuryl alcohol and aldehyde condensate, phenol and aldehyde condensate, melamine and aldehyde condensate, and urea and aldehyde condensate. What consists of 1 type chosen from a group, and what consists of 2 or more types of mixtures chosen from these groups can be used. Moreover, what consists of 2 or more types of cocondensates chosen from the said group and what consists of a mixture of 1 or more types chosen from the said group and the said cocondensates can also be used. Of these, from the viewpoint of deep curability and resin viscosity, a condensate of furfuryl alcohol, phenols and aldehydes, a condensate of furfuryl alcohol, melamine and aldehydes, and furfuryl alcohol, urea and aldehydes. A furan resin composed of one kind selected from the group consisting of condensates, or a furan resin composed of a mixture of two or more kinds selected from these groups is preferred. Further, from the viewpoint of reducing the amount of formaldehyde generated during molding and improving the mold strength, a condensate of furfuryl alcohol, urea, and aldehydes is preferable. Among these, from the viewpoint of adjusting the viscosity of the binder composition to an appropriate range, the acid curable resin preferably contains furfuryl alcohol.

  Examples of the aldehydes include formaldehyde, acetaldehyde, glyoxal, furfural, terephthalaldehyde, and the like, 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 or terephthalaldehyde.

  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 phenols and aldehydes, it is preferable to use 1-3 mol of aldehydes with respect to 1 mol of phenols. Moreover, when manufacturing the condensate of a melamine and aldehydes, it is preferable to use 1-3 mol of aldehydes with respect to 1 mol of melamine. Moreover, when manufacturing the condensate of urea and aldehydes, it is preferable to use 1.0-2.0 mol of aldehydes with respect to 1 mol of urea, and 1.5-2.0 mol is used. It is more preferable to use 1.7 to 2.0 mol.

  When producing a condensate of furfuryl alcohol, aldehydes and urea, it is preferable to condense urea and aldehydes in furfuryl alcohol under an acid catalyst, and aldehydes per mole of furfuryl alcohol. It is preferable to use 0.05 to 3 mol of urea and 0.03 to 1.5 mol of urea.

  The content of the acid curable resin in the binder composition is preferably 50 to 99% by weight, more preferably 55 to 99% by weight, and still more preferably, from the viewpoint of improving the final mold strength. Is 60 to 99% by weight.

  In particular, when the acid curable resin contains furfuryl alcohol, the content of furfuryl alcohol in the binder composition is preferably 25 from the viewpoint of adjusting the viscosity of the binder composition to an appropriate range. It is -98 weight%, More preferably, it is 30-98 weight%, More preferably, it is 35-98 weight%.

  In the self-hardening mold, it is preferable that the binder composition has a low viscosity from the viewpoint of preventing kneading unevenness and uniform expression of the mold strength. From the above viewpoint, the viscosity of the binder composition at 25 ° C. measured with an E-type viscometer is preferably 1 to 80 mPa · s, more preferably 5 to 60 mPa · s, and still more preferably 8 to 40 mPa · s.

  In a binder composition obtained from a compound having an amino group (for example, urea, etc.), it is considered that the amino group forms a cross-linking bond with the resin component, and has a favorable influence on the flexibility of the obtained template. Is done. The amino group content can be estimated by the nitrogen content (% by weight). Note that the flexibility of the mold is necessary when the mold is removed from the original mold. In particular, when a mold having a complicated shape is formed, if the mold has high flexibility, it is possible to prevent mold cracks caused by stress concentration at a portion where the thickness of the mold is thin at the time of mold removal. In the binder composition used in the present invention, the nitrogen content in the binder composition is 2.0% by weight from the viewpoint of preventing cracking of the obtained mold and improving the final mold strength. Preferably, it is 2.2% by weight or more, more preferably 2.3% by weight or more, and even more preferably 2.5% by weight or more. Further, from the viewpoint of preventing gas defects due to nitrogen in the casting, the nitrogen content in the binder composition is preferably 4.0% by weight or less, more preferably 3.8% by weight or less. Preferably, it is 3.7% by weight or less, more preferably 3.6% by weight or less. Taking the above viewpoints together, the nitrogen content in the binder composition is preferably 2.0 to 4.0 wt%, more preferably 2.2 to 3.8 wt%. It is still more preferably 3 to 3.7% by weight, still more preferably 2.5 to 3.6% by weight. In order to adjust the nitrogen content in the binder composition within the above range, the content of the nitrogen-containing compound in the binder composition may be adjusted. As the nitrogen-containing compound, urea, melamine, a condensate of urea and aldehydes, a condensate of melamine and aldehydes, a urea resin, a urea-modified resin, and the like are preferable. The nitrogen content in the binder composition can be quantified by the Kjeldahl method. Furthermore, urea, urea resin, furfuryl alcohol / urea resin (urea-modified resin), and nitrogen content derived from furfuryl alcohol / urea formaldehyde resin, 13C-NMR for urea-derived carbonyl groups (C = O groups) It can also be determined by quantifying with. From the viewpoint of improving deep part curability, the nitrogen content in the binder composition is preferably 2.0 to 4.0% by weight, more preferably 3.0 to 4.0% by weight. preferable.

  The content of the binder composition in the self-hardening mold composition is preferably 0.4 to 5.0% by weight, more preferably 0.6 to 3.0% by weight from the viewpoint of improving the mold strength. 8 to 2.0% by weight is more preferable.

<Compound (A)>
From the viewpoint of improving the deep curability of the self-hardening mold, the composition for self-hardening mold of the present invention is a dihydric alcohol (A1) represented by the general formula (1) and an ether represented by the general formula (2). It contains at least one compound (A) selected from the group consisting of a group-containing dihydric alcohol (A2) and a ketone (A3) represented by the general formula (3).

The dihydric alcohol (A1) is represented by the general formula (1), and R ¹ is an alkylene group having 2 to 8 carbon atoms. For example, ethylene group, propylene group, 1-methylethylene group, butylene group, 1-methylpropylene group, pentylene group, hexylene group, 1-butylethylene group, heptylene group, octylene group and the like can be mentioned. From the viewpoint of improving deep-part curability, R ¹ preferably has 2 to 6 carbon atoms, and more preferably 4 to 6 carbon atoms. Specific compounds include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexane. Examples include diol, 1,2-hexanediol, 1,7-heptanediol, 1,8-octanediol, and the like. Among these, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol are preferable from the viewpoint of improving the deep curability of the mold.

The ether group-containing dihydric alcohol (A2) is represented by the general formula (2), R ² is an alkylene group having 2 to 4 carbon atoms, and an alkylene having 2 to 3 carbon atoms from the viewpoint of improving the deep curability of the template. Group is preferable, and an alkylene group having 2 carbon atoms is more preferable. Specifically, R ² includes an ethylene group, a propylene group, and a butylene group. n represents the average number of repeating alkyleneoxy groups, and is a number of 2 to 5, preferably 2 to 4, more preferably 2 to 3, from the viewpoint of improving the deep curability of the mold. Specific compounds include diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, pentapropylene glycol, dibutylene glycol, tributylene glycol, tetrabutylene glycol, penta Examples include butylene glycol and mixtures thereof. Diethylene glycol, triethylene glycol, and dipropylene glycol are preferred from the viewpoint of improving deep-part curability.

The ketone (A3) is represented by the general formula (3), and R ³ and R ⁴ are each a hydrocarbon group having 1 to 6 carbon atoms, and the carbon number of R ³ and R ⁴ from the viewpoint of improving deep curability. 2-8 are preferable and 2-7 are more preferable. Examples of R ³ and R ⁴ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a heptyl group, a phenyl group, and a methylphenyl group, and preferably a methyl group, an ethyl group, and a phenyl group. When R ³ and R ⁴ form a ring, the total number of carbon atoms of R ³ and R ⁴ is an alkylene group having 3 to 6 carbon atoms, and the number of carbon atoms of R ³ and R ⁴ is from the viewpoint of improving the deep curability of the template. Is preferably 4-5. In the case of forming a ring, the alkylene group composed of R ³ and R ⁴ is preferably a butylene group or a pentylene group, for example. When no ring is formed, acetone, methyl ethyl ketone, and acetophenone are preferred as specific compounds of ketone (A3). In the case of forming a ring, specific compounds of ketone (A3) include cyclopentanone and cyclohexanone, with cyclohexanone being preferred. As for the ketone (A3) as a whole, cyclohexanone, acetone, and acetophenone are preferable, and cyclohexanone is more preferable from the viewpoint of improving deep-part curability.

  The compound (A) used in the present invention is 0.0049% by weight or more, preferably 0.0069% by weight or more, and preferably 0.0069% by weight or more in the composition for self-hardening molds from the viewpoint of improving the deep curability of the mold. More preferably, it is more than wt%. Further, from the viewpoint of improving the deep curability of the mold, it is 0.069% by weight or less, preferably 0.049% by weight or less, more preferably 0.03% by weight or less in the self-hardening mold composition. More preferred is 02% by weight or less. When these viewpoints are put together, the compound (A) is 0.0049 to 0.069% by weight, preferably 0.0069 to 0.049% by weight, and preferably 0.01 to 0% in the self-hardening mold composition. 0.03 wt% is more preferable, and 0.01 to 0.02 wt% is still more preferable.

  The compound (A) may be contained in the binder composition in advance from the viewpoint of improving the depth hardness of the self-hardening mold composition and facilitating blending. That is, the binder composition of the present invention contains an acid curable resin and the compound (A), and the compound (A) is added to the binder composition from the viewpoint of improving the deep curability of the mold. It is a binder composition containing 5 to 7.0% by weight. The compound (A) is preferably contained in the binder composition in an amount of 0.7 to 5.0% by weight, and 1.0 to 3.0% by weight from the viewpoint of improving the deep curability of the mold and maintaining the mold strength. It is more preferable to contain, and it is still more preferable to contain 1.0 to 2.0 weight%.

  The content weight ratio of the compound (A) to the refractory particles is preferably 0.000025 to 0.00105 from the viewpoint of improving the deep part curability of the mold and maintaining the mold strength, and is 0.00005 to 0.0007. More preferably, it is more preferably 0.00007 to 0.0005, still more preferably 0.0001 to 0.0003, and still more preferably 0.0001 to 0.0002.

<Curing accelerator>
The binder composition used in the present invention may contain a curing accelerator from the viewpoint of preventing cracking of the mold and improving the mold strength. The curing accelerator is preferably at least one selected from the group consisting of a compound represented by the following general formula (4), a phenol derivative, and an aromatic dialdehyde from the viewpoint of improving the mold strength.

〔式中、Ｘ₁及びＸ₂は、それぞれ水素原子、ＣＨ₃又はＣ₂Ｈ₅の何れかを表す。〕

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

  Examples of the compound represented by the general formula (4) include 2,5-bishydroxymethylfuran, 2,5-bismethoxymethylfuran, 2,5-bisethoxymethylfuran, and 2-hydroxymethyl-5-methoxymethylfuran. 2-hydroxymethyl-5-ethoxymethylfuran and 2-methoxymethyl-5-ethoxymethylfuran. Among these, 2,5-bishydroxymethylfuran is preferably used from the viewpoint of improving the mold strength. The content of the compound represented by the general formula (4) in the binder composition improves the viewpoint of solubility of the compound represented by the general formula (4) in the acid curable resin and the mold strength. From the viewpoint, it is preferably 0.5 to 63% by weight, more preferably 1.8 to 50% by weight, still more preferably 2.5 to 50% by weight, and 3.0 to 40% by weight. % Is even more preferred.

  Examples of the phenol derivative include resorcin, cresol, hydroquinone, phloroglucinol, methylene bisphenol, and the like. Of these, resorcin is preferable from the viewpoint of improving the deep curability of the mold and improving the mold strength. The content of the phenol derivative in the binder composition is preferably 1 to 25% by weight from the viewpoint of the solubility of the phenol derivative in the acid curable resin and the improvement of the mold strength. It is more preferably 15% by weight, and further preferably 3 to 10% by weight. In particular, when resorcin is used, the content of resorcin in the binder composition is determined in terms of the solubility of resorcin in the acid curable resin, the viewpoint of improving the deep curability of the mold, and the final mold strength. From the viewpoint of improvement, it is preferably 1 to 10% by weight, more preferably 2 to 7% by weight, and further preferably 3 to 6% by weight.

  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 from the viewpoint of sufficiently dissolving the aromatic dialdehyde in the acid curable resin and suppressing the odor of the aromatic dialdehyde itself. It is 1 to 15% by weight, more preferably 0.5 to 10% by weight, and further preferably 1 to 5% by weight.

<Water>
The binder composition used in the present invention 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. However, when such a condensate is used in a binder composition, it is not necessary to remove these waters derived from the synthesis process. Further, water may be further added for the purpose of adjusting the binder composition to a viscosity that is easy to handle. However, if water is excessive, the curing reaction of the acid curable resin may be inhibited. Therefore, the water content in the binder composition is preferably in the range of 0.5 to 30% by weight from the viewpoint of making the binder composition easy to handle and maintaining the initial mold strength. A range of 5 to 25% by weight is more preferable. Furthermore, it is preferably 5 to 10% by weight from the viewpoint of improving the final mold strength. Moreover, the remarkable difference in deep part curability is recognized when the water content is in the range of 5 to 25% by weight.

<Other additives>
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 included because the final mold strength can be improved. Examples of silane coupling agents include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxy. Aminosilanes such as silane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxy Epoxy silanes such as propyltriethoxysilane, ureido silane, mercapto silane, sulfide silane, methacryloxy silane, acryloxy silane and the like are used. Amino silane, epoxy silane, and ureido silane are preferable. The content of the silane coupling agent in the binder composition is preferably 0.01 to 0.5% by weight, and 0.05 to 0.3% by weight from the viewpoint of improving the final mold strength. % Is more preferable.

≪Fireproof particles≫
As the refractory particles, conventionally known particles such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Recycled ones can also be used. The content of the refractory particles in the self-hardening mold composition is preferably 91.5 to 99.5% by weight, more preferably 95 to 99% by weight, and still more preferably 97 to 98.8% by weight.

≪Curing agent≫
Examples of the curing agent include xylene sulfonic acid (especially 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 a phosphoric acid compound and sulfuric acid can be used. Further, the curing agent includes at least one solvent selected from the group consisting of alcohols other than the compound represented by the general formula (1), ether alcohols other than the compound represented by the general formula (2), and esters. Alternatively, carboxylic acids can be contained. In addition, the hardening | curing agent used by this invention is also called a hardening | curing agent composition. Among these, from the viewpoint of improving the final mold strength, the alcohols and the ether alcohols are preferably contained, and the ether alcohols are more preferably contained. Moreover, when the said solvent and carboxylic acid are contained in a hardening | curing agent, since the moisture content in a hardening | curing agent is reduced, final mold intensity | strength further improves. The content of the solvent and the carboxylic acids in the curing agent is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoint of improving the final mold strength.

  From the viewpoint of improving the final mold strength, the alcohols are preferably propanol, butanol, pentanol, hexanol, heptanol, octanol, and benzyl alcohol. The ether alcohols are 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 esters include butyl acetate, butyl benzoate, ethylene glycol Monobutyl ether acetate, diethylene glycol monobutyl ether Le acetate is preferred. Moreover, it is preferable to contain methanol and ethanol from a viewpoint of reducing the viscosity of a hardening | curing agent composition, and a viewpoint of the storage stability improvement of a hardening | curing agent composition. 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. The content of the curing agent in the self-hardening mold composition is preferably 0.12 to 3.5% by weight, more preferably 0.2 to 1.0% by weight, from the viewpoint of improving the mold strength. More preferred is ˜0.6% by weight.

  As a method for preparing the self-hardening mold composition (kneaded sand) of the present invention, for example, the above-mentioned binder composition of the present invention and a curing agent for curing the binder composition are added to the refractory particles. A method of kneading these with a batch mixer or a continuous mixer can be exemplified. At this time, it is preferable to add the binder composition of the present invention after the curing agent is added to the refractory particles. According to the said method, since the binder composition of this invention contains the compound (A), a compound (A) is supplied to the composition for final self-hardening casting_mold | templates. That is, since the compound (A) is blended in advance in the binder composition of the present invention, when the binder composition is mixed with the refractory particles and the curing agent, the compound ( It is speculated that A) is blended uniformly and contributes to the improvement of deep part curability. In addition, when obtaining the composition for self-hardening molds of this invention, you may use the binder composition which does not contain a compound (A). In that case, the compound (A) may be separately added to the refractory particles or the like when the binder composition is added to the refractory particles or before or after the addition. Moreover, when obtaining the composition for self-hardening casting_mold | templates of this invention, you may use the binder composition which contains a compound (A) out of the range of 0.5 to 7.0 weight% in a composition. In that case, what is necessary is just to adjust the quantity of each component so that compound (A) may contain in the range of 0.0049-0.069 weight% in the final composition for self-hardening casting_mold | templates.

  The ratio of the refractory particles, the binder composition, and the curing agent in the self-hardening mold composition can be set as appropriate, but the binder composition is 0.5 to 1. per 100 parts by weight of the refractory particles. 5 parts by weight and the curing agent is preferably in the range of 0.07 to 1 part by weight. With such a ratio, it is easy to obtain a mold having sufficient strength. Furthermore, the content of the curing agent is 10 to 10 parts by weight with respect to 100 parts by weight of the acid curable resin in the binder composition from the viewpoint of reducing the amount of water contained in the mold as much as possible and the mixing efficiency in the mixer. The amount is preferably 40 parts by weight, more preferably 15 to 35 parts by weight, and still more preferably 18 to 25 parts by weight.

≪Method of manufacturing self-hardening mold≫
The self-hardening mold composition of the present invention includes a step of curing a self-hardening mold composition obtained by mixing refractory particles, a binder composition containing an acid curable resin, and a curing agent. It is suitable for a mold manufacturing method. That is, the self-hardening mold manufacturing method of the present invention is a self-hardening mold manufacturing method using the above-mentioned self-hardening mold composition of the present invention as the self-hardening mold composition.

  When the self-hardening mold composition of the present invention is filled in a mold for mold making and the self-hardening mold composition is cured at 25 ° C. or lower, the deep curability is higher than when it exceeds 25 ° C. Becomes better. This is because the amount of water decreases in order to cure at the same curing rate when the temperature is low.

  Examples that specifically illustrate the present invention will be described below. The evaluation items in the examples were measured as follows.

<Deep hardness>
Immediately after preparation of the self-hardening mold composition, the mold is taken out from the polycup when the mold compressive strength reaches 0.3 MPa when the mold compressive strength reaches 0.3 MPa, and the deep part of the mold (contacts the bottom of the polycup). Surface hardness) was measured with a furan mold surface hardness tester (manufactured by Nakayama). In addition, the value of the deep part hardness shown in Table 1 is the value of the scale (unitless) indicated by the surface hardness tester for furan mold, and the deeper part curability becomes better as the numerical value is larger.

<Mold compression strength after 30 minutes>
Under the conditions of 25 ° C. and 55% RH, a self-hardening mold composition was immediately filled into a cylindrical test piece frame having a diameter of 50 mm and a height of 50 mm, left for 30 minutes, and then removed from the mold. The mold compressive strength was measured by the method described in 2604-1976, and the obtained measured value was defined as the mold compressive strength (MPa) after 30 minutes.

<Mold compression strength after 24 hours>
Immediately after preparation, the composition for a self-hardening mold was filled into a cylindrical test piece frame having a diameter of 50 mm and a height of 50 mm. After 5 hours passed after filling under conditions of 25 ° C. and 55% RH, the mold was removed, and after leaving for 19 hours after removal under the conditions of 25 ° C. and 55% RH, it was described in JIS Z 2604-1976. The mold compressive strength was measured by the method, and the obtained measured value was defined as the mold compressive strength (MPa) after 24 hours.

<Nitrogen content of binder composition>
Measurement was performed by the Kjeldahl method shown in JIS M 8813.

(Examples 1-9 and Comparative Examples 1-7)
In advance, the compound (A) or other solvent was mixed with an acid curable resin, a curing accelerator, and a silane coupling agent to prepare a binder composition having the composition shown in Table 1. Under conditions of 25 ° C. and 55% RH, with respect to 100 parts by weight of furan regenerated sand, a mixture of a curing agent [Kaurightener curing agent TK-3 manufactured by Kao Quaker Co., Ltd. and Kaolitener curing agent F-9 manufactured by Kao Quaker Co., Ltd. (Weight ratio is TK-3 / F-9 = 35/5)] 0.36 parts by weight is added, and then 0.90 part by weight of the above binder composition is added and mixed to form a self-hardening mold. A composition was obtained. About the obtained composition for self-hardening casting_mold | template, each item was evaluated by the method mentioned above. The results are shown in Table 1. In addition, as said furan reproduction | regeneration sand, the weight reduction | decrease rate (LOI) when heated at 1000 degreeC in the air for 1 hour was used by 1.4 weight%.

  As shown in Table 1, Examples 1 to 9 all had better deep part curability than Comparative Examples 1 to 7. Moreover, it was confirmed from the comparison of Example 2 and Example 8 that both deep part sclerosis | hardenability and final mold intensity | strength can be improved by adding resorcin. Moreover, it was confirmed from the comparison between Example 2 and Example 9 that the deep portion curability is improved when the nitrogen content is 3.6% by weight rather than 2.7% by weight.

Claims (4)

A wooden mold is filled with a self-hardening mold composition obtained by mixing refractory particles, a binder composition containing an acid curable resin, and a curing agent, and the acid curable resin is cured. A method for producing a self-hardening mold having steps, which is a dihydric alcohol represented by the following general formula (1), an ether group-containing dihydric alcohol represented by the following general formula (2), and the following general formula (3) A method for producing a self- hardening mold, comprising 0.0049 to 0.069 wt% of at least one compound (A) selected from the group consisting of ketones represented by the formula:
HO—R ¹ —OH (1)
(R ¹ is an alkylene group having 2 to 8 carbon atoms.)
HO— (R ² O) _n —H (2)
(R ² is an alkylene group having 2 to 4 carbon atoms, and n is a number of 2 to 5)
R ³ —CO—R ⁴ (3)
(R ³ and R ⁴ are each a hydrocarbon group having 1 to 6 carbon atoms, and when R ³ and R ⁴ form a ring, the total number of carbon atoms of R ³ and R ⁴ is an alkylene group having 3 to 6 carbon atoms. is there.) The method for producing a self- hardening mold according to claim 1, wherein the binder composition contains 0.5 to 7.0% by weight of the compound (A). The method for producing a self- hardening mold according to claim 1 or 2, wherein a content weight ratio of the compound (A) to the refractory particles [compound (A) / refractory particles] is 0.000025 to 0.00105. The method for producing a self-hardening mold according to any one of claims 1 to 3, wherein the composition for self-hardening mold does not contain a ketone represented by the general formula (3) .