Curing agent composition for forming casting mold

Abstract

To provide a curing agent composition for molding a mold capable of suppressing cracks of a hard vinyl chloride pipe of a facility for molding a mold.SOLUTION: A curing agent composition for molding a mold containing at least an acid component, water, and dixylylsulfone, wherein the acid component contains xylenesulfonic acid, a content of the water is 50.0 mass% or more and 99.0 mass% or less, and a content of the dixylylsulfone is more than 0 mass% and less than 0.43 mass%.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] An acid-hardening self-hardening mold is produced by supplying a binder composition for mold making and a hardener composition for mold making to a kneader through piping by a supply device, kneading them with refractory particles, and then filling a master such as a wooden mold with the resulting mixed sand and hardening the acid-hardening resin (e.g., Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-88591 Summary of the Invention [Problem to be solved by the invention]

[0004] The mold-making equipment, including the supply device and the kneader, uses piping made of rigid polyvinyl chloride (hereinafter also referred to as rigid PVC pipes). However, when the hardener composition for mold-making is delivered within the mold-making equipment, the rigid PVC pipes of the mold-making equipment often crack, causing problems with liquid leakage.

[0005] The present invention provides a hardener composition for mold making that can suppress cracking of rigid PVC pipes in mold making equipment. [Means for solving the problem]

[0006] Analysis of the mold-making hardener composition being delivered through the cracked PVC hardener pipe revealed the presence of dixylyl sulfone and diisononyl phthalate, which were not incorporated into the mold-making hardener composition. Dixylyl sulfone is a by-product of the synthesis of xylene sulfonic acid from xylene. Therefore, the dixylyl sulfone in the mold-making hardener composition is likely a by-product of the synthesis of xylene sulfonic acid. Furthermore, the mold-making device uses flexible polyvinyl chloride piping (hereinafter also referred to as flexible PVC pipe) in addition to rigid PVC pipes. Diisononyl phthalate is used as a plasticizer for the flexible PVC pipes. Therefore, the diisononyl phthalate in the mold-making hardener composition is likely derived from the flexible PVC pipes. Based on these findings, it was speculated that dixylyl sulfone or diisononyl phthalate may be the cause of the cracks in the rigid PVC pipes. Therefore, rigid PVC pipes were immersed in a dixylyl sulfone aqueous solution, a diisononyl phthalate aqueous solution, and an aqueous solution of dixylyl sulfone and diisononyl phthalate, respectively. No cracking was observed in the rigid PVC pipes immersed in the dixylyl sulfone aqueous solution or the diisononyl phthalate aqueous solution, but cracking was observed only in the rigid PVC pipes immersed in the dixylyl sulfone and diisononyl phthalate aqueous solution. Because diisononyl phthalate originates from the flexible PVC pipes used in the mold-making device, replacing the flexible PVC pipes with piping made of a different material could be considered to prevent the inclusion of diisononyl phthalate, but this is economically difficult. Therefore, the inventors focused on dixylyl sulfone and conducted further research. They discovered that cracking of rigid PVC pipes can be suppressed by reducing the dixylyl sulfone content below a certain amount in a hardener composition for mold-making containing xylene sulfonic acid as an acid component, thereby completing the present invention.

[0007] The hardener composition for mold making of the present invention comprises: A hardener composition for mold making containing at least an acid component, water, and dixylyl sulfone, the acid component contains xylene sulfonic acid, The water content is 50.0% by mass or more and 99.0% by mass or less, The content of dixylyl sulfone is more than 0% by mass and less than 0.43% by mass. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a hardener composition for mold making that can suppress cracking of rigid PVC pipes in mold making equipment. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Hardening agent composition for casting> The hardener composition for mold making of this embodiment (hereinafter also referred to as hardener composition) contains at least an acid component, water, and dixylyl sulfone, the acid component contains xylene sulfonic acid, the water content is 50.0 mass% or more and 99.0 mass% or less, and the dixylyl sulfone content is more than 0 mass% and less than 0.43 mass%. The hardener composition of this embodiment can suppress cracking of rigid PVC pipes.

[0010] [Acid component] The hardener composition contains xylene sulfonic acid as an acid component that hardens the acid-hardening resin contained in the binder composition for mold formation.

[0011] The content of xylene sulfonic acid in the curing agent composition is preferably 10.0% by mass or more, more preferably 15.0% by mass or more, from the viewpoint of curing the acid-curable resin. The content of xylene sulfonic acid in the curing agent composition is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, from the viewpoint of curing the acid-curable resin.

[0012] The curing agent composition may contain one or more conventionally known acid components other than xylenesulfonic acid as the acid component that cures the acid-curing resin, such as carboxylic acids such as 2,6-dihydroxybenzoic acid, oxalic acid, maleic acid, pyruvic acid, malonic acid, 2-furancarboxylic acid, phthalic acid, fumaric acid, lactic acid, citric acid, and malic acid; sulfonic acid compounds other than xylenesulfonic acid, such as toluenesulfonic acid (particularly p-toluenesulfonic acid) and methanesulfonic acid; phosphoric acid; sulfuric acid; etc. Among these, sulfuric acid is preferred from the viewpoint of improving mold strength.

[0013] When the curing agent composition contains sulfuric acid, the content of sulfuric acid in the curing agent composition is preferably more than 0% by mass, and more preferably 3.0% by mass or more, from the viewpoint of improving the strength of the mold. The content of sulfuric acid in the curing agent composition is preferably 30% by mass or less, more preferably 20.0% by mass or less, and even more preferably 10.0% by mass or less, from the viewpoint of improving the strength of the mold. Furthermore, when the curing agent composition contains sulfuric acid, the content of sulfuric acid in the curing agent composition is preferably more than 0% by mass and 30% by mass or less, more preferably 3.0% by mass or more and 20.0% by mass or less, and even more preferably 3.0% by mass or more and 10.0% by mass or less, from the viewpoint of improving the strength of the mold.

[0014] 〔water〕 The hardener composition contains water from the viewpoint of uniformly mixing the hardener composition, the refractory particles, and the binder composition for mold formation.

[0015] The water content in the hardener composition is 50.0% by mass or more, preferably 60.0% by mass or more, from the viewpoint of uniformly mixing the hardener composition, the refractory particles, and the binder composition for mold making. The water content in the hardener composition is 99.0% by mass or less, preferably 80.0% by mass or less, from the viewpoint of improving mold strength. The water content in the hardener composition is 50.0% by mass or more and 99.0% by mass or less, preferably 60.0% by mass or more and 80.0% by mass or less, from the viewpoint of uniformly mixing the hardener composition, the refractory particles, and the binder composition for mold making.

[0016] [Dixylyl sulfone] The curing agent composition contains dixylyl sulfone, which is produced as a by-product during the synthesis of xylene sulfonic acid.

[0017] The content of dixylyl sulfone in the curing agent composition is less than 0.43% by mass, and preferably 0.35% by mass or less, from the viewpoint of suppressing cracking of the rigid PVC pipe of the mold-making equipment. The content of dixylyl sulfone in the curing agent composition is more than 0% by mass, and preferably 0.05% by mass or more, from the viewpoint of production costs. The content of dixylyl sulfone in the curing agent composition is more than 0% by mass and less than 0.43% by mass, and preferably 0.05% by mass or more and 0.35% by mass or less, from the viewpoint of suppressing cracking of the rigid PVC pipe of the mold-making equipment and from the viewpoint of production costs.

[0018] The ratio of the dixylyl sulfone content to the xylene sulfonic acid content in the curing agent composition (dixylyl sulfone content / xylene sulfonic acid content) is preferably 0.001 or more, more preferably 0.005 or more, from the viewpoint of production costs. The ratio of the dixylyl sulfone content to the xylene sulfonic acid content in the curing agent composition (dixylyl sulfone content / xylene sulfonic acid content) is preferably 0.012 or less, more preferably 0.011 or less, from the viewpoint of suppressing cracking of the rigid PVC pipe of the mold-making equipment. The ratio of the dixylyl sulfone content to the xylene sulfonic acid content in the curing agent composition (dixylyl sulfone content / xylene sulfonic acid content) is preferably 0.001 or more and 0.012 or less, more preferably 0.005 or more and 0.011 or less, from the viewpoint of production costs and suppressing cracking of the rigid PVC pipe of the mold-making equipment.

[0019] The formation of dixylyl sulfone during the synthesis of xylene sulfonic acid from xylene can be suppressed by adjusting the reaction temperature and reaction time, changing the sulfonium ion source, and the like.

[0020] [Other ingredients] The curing agent composition may contain other components as long as the effects of the mold of this embodiment are not impaired. Examples of such other components include the following components.

[0021] The curing agent composition may contain one or more organic solvents selected from the group consisting of alcohols and ether alcohols, with alcohols being more preferred.

[0022] From the viewpoint of improving mold strength, the alcohols are preferably methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, or benzyl alcohol, and the ether alcohols are preferably 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, or ethylene glycol monophenyl ether.

[0023] The content of the organic solvent in the curing agent composition is adjusted appropriately to obtain a desired reaction rate and mold strength depending on the temperature of the working environment and the temperature of the refractory particles, but generally, from the viewpoint of improving mold strength and dissolving the curing agent composition, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. From the same viewpoints, the content of the solvent in the curing agent composition is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0024] <Mold composition> The foundry composition of this embodiment contains a binder composition for foundry molding (hereinafter also referred to as a binder composition) containing refractory particles and an acid-curing resin, and the hardener composition.

[0025] [Fire-resistant particles] The refractory particles may be one or more of conventionally known refractory particles such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, etc., or may be recovered or recycled used refractory particles. Of these, silica sand is preferred.

[0026] [Binder composition for mold making] The binder composition contains an acid-hardening resin as a binder component.

[0027] The acid-hardening resin may be at least one selected from the group consisting of furan resin, condensates of melamine and aldehydes, condensates of urea and aldehydes, and condensates of ethylene urea and aldehydes. From the viewpoint of improving mold strength, the acid-hardening resin preferably contains furan resin.

[0028] The furan resin is obtained by polymerizing a monomer composition containing furfuryl alcohol, and can be used without any particular limitation as long as it can be used as a binder for mold making. From the viewpoint of significantly improving mold strength in a low-temperature environment while reducing the content of monomeric furfuryl alcohol, the furan resin may be selected from the group consisting of a condensate of furfuryl alcohol and urea, a condensate of furfuryl alcohol and melamine, a condensate of furfuryl alcohol and ethyleneurea, a condensate of furfuryl alcohol, urea, and aldehydes (urea-modified furan resin), a condensate of furfuryl alcohol, melamine, and aldehydes, a condensate of furfuryl alcohol, ethyleneurea, and aldehydes, a furfuryl alcohol condensate, It is preferable that the resin contains one or more selected from the group consisting of condensates of furfuryl alcohol and aldehydes, and condensates of furfuryl alcohol, phenols, and aldehydes, as well as one or more co-condensates selected from the group consisting of two or more selected from the above group, and it is more preferable that the resin contains one or more selected from the group consisting of urea-modified furan resin, furfuryl alcohol condensates, and condensates of furfuryl alcohol and aldehydes, as well as one or more co-condensates selected from the group consisting of two or more selected from the above group.

[0029] Examples of the aldehydes include formaldehyde, acetaldehyde, glyoxal, furfural, terephthalaldehyde, hydroxymethylfurfural, etc., and one or more of these can be used as appropriate. From the viewpoint of improving mold strength, 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.

[0030] Examples of the phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, and bisphenol F, and one or more of these can be used.

[0031] The furan resin can be produced by a known method. For example, when the furan resin is a urea-modified furan resin, the urea-modified furan resin can be obtained by reacting 100.0 parts by mass of furfuryl alcohol with 0.6 to 30.0 parts by mass of urea and 0.4 to 50.0 parts by mass of paraformaldehyde.

[0032] From the viewpoint of improving mold strength, the content of the furan resin in the acid-hardening resin 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, even more preferably substantially 100% by mass, and even more preferably 100% by mass.

[0033] The content of the acid-hardening resin in the binder composition is preferably 5.0% by mass or more, more preferably 6.0% by mass or more, and even more preferably 7.0% by mass or more, from the viewpoint of improving mold strength. The content of the acid-hardening resin in the binder composition is preferably 45.0% by mass or less, more preferably 43.0% by mass or less, and even more preferably 42.0% by mass or less, from the viewpoint of maintaining good kneadability with the refractory aggregate and suppressing a decrease in mold strength.

[0034] In the mold composition, the mass ratio of the refractory particles, the binder composition, and the hardener composition can be set as appropriate. From the viewpoint of improving mold strength, however, it is preferable that the binder composition be in the range of 0.5 to 1.5 parts by mass and the hardener be in the range of 0.07 to 1 part by mass per 100 parts by mass of the refractory particles.

[0035] <Mold manufacturing method> The hardener composition for foundry molding can be used to manufacture a foundry mold. The method for manufacturing a foundry mold of this embodiment includes a mixing step of mixing the refractory particles, the binder composition, and the hardener composition to obtain the foundry composition, and a curing step of curing the foundry composition.

[0036] In the mixing step, the order in which the binder composition, the hardener composition, and the refractory particles are added and mixed is not particularly limited. The binder composition and the hardener composition may be mixed to produce a mold-making composition, and then the mold-making composition and the refractory particles may be mixed. Alternatively, the binder composition, the hardener composition, and the refractory particles may be added and mixed separately. However, from the viewpoints of storage stability and mold productivity, it is preferable to mix the binder composition, the hardener composition, and the refractory particles to obtain a mold-making composition. Furthermore, from the viewpoint of improving mold strength, it is preferable to add the hardener composition to the refractory particles and mix them, and then add the binder composition and mix them. Furthermore, when two or more hardener compositions are used, the individual hardener compositions may be mixed and then added, or each hardener composition may be added separately.

[0037] The contents of the components in the binder composition and the hardener composition, and the contents of the components in the foundry composition, can be considered to be the blending amounts of the components in the binder composition and the hardener composition, and the blending amounts of the components in the foundry composition.

[0038] In the mixing step, the raw materials can be mixed using a known general method, for example, a method in which the raw materials are added and kneaded using a batch mixer, or a method in which the raw materials are supplied to a continuous mixer and kneaded.

[0039] In the mold manufacturing method of this embodiment, the mold can be manufactured by utilizing the conventional mold manufacturing process as is, except for the mixing step. [Example]

[0040] Examples that specifically illustrate the present invention will be described below.

[0041] <Examples 1 to 6, Comparative Example 1> [Preparation of Curing Agent Composition] [Preparation of Curing Agent Composition A] 576 parts by mass of industrial xylene (manufactured by ENEOS Corporation) was charged into a three-neck flask and stirring was initiated. Next, 424 parts by mass of 25% fuming sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was charged into a dropping funnel and added dropwise to the three-neck flask at a constant rate. After the addition of the fuming sulfuric acid was completed, the reaction was carried out at 100°C for 1 hour. After the reaction was completed, the remaining xylene was removed by topping to obtain curing agent composition A. The content of dixylyl sulfone in curing agent composition A measured by the following method was 0.22% by mass. The content of xylene sulfonic acid was 47.08% by mass, and the content of sulfuric acid was 9.4% by mass. The contents of xylene sulfonic acid and sulfuric acid were calculated from the blend amounts of the raw materials.

[0042] [Preparation of Curing Agent Composition B] A three-neck flask was charged with 576 parts by mass of industrial xylene (manufactured by ENEOS Corporation) and stirring was initiated. Next, 424 parts by mass of 25% fuming sulfuric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was charged into a dropping funnel and added dropwise to the three-neck flask at a constant rate. After the addition of the fuming sulfuric acid was completed, the reaction was carried out at 125°C for 1 hour. After the reaction was completed, the remaining xylene was removed by topping to obtain curing agent composition B. The content of dixylyl sulfone in curing agent composition B, measured by the following method, was 0.62% by mass. The content of xylene sulfonic acid was 46.68% by mass, and the content of sulfuric acid was 9.4% by mass. The contents of xylene sulfonic acid and sulfuric acid were calculated from the blend amounts of the raw materials.

[0043] [Quantitative Determination of Dixylyl Sulfone in Curing Agent Composition] 100 cc of water was placed in a 500 cc separatory funnel. Next, 6 to 10 g of the curing agent composition was weighed out and placed in the separatory funnel. The liquid in the separatory funnel was neutralized with 25% sodium hydroxide (25 w / v% sodium hydroxide solution, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). 200 ml of petroleum ether (petroleum ether, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and the mixture was shaken for approximately 15 minutes. The lower layer (aqueous layer) was extracted and washed three times with approximately 50 cc of water. The mixture was then dehydrated with approximately 40 to 50 g of anhydrous sodium sulfate (sodium sulfate (anhydrous), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and allowed to stand for approximately 15 minutes. Next, the weight of the 500 cc recovery flask was accurately weighed. The liquid in the separatory funnel was filtered into a 500 cc recovery flask using filter paper (No. 2 filter paper, manufactured by Advantec Co., Ltd.). The separatory funnel was then washed with petroleum ether three or four times and poured into a recovery flask. The liquid in the recovery flask was topped with petroleum ether in an evaporator, and the weight of the recovery flask after drying was precisely weighed. The difference in weight between the recovery flask before and after drying was divided by the amount of curing agent composition charged to calculate the proportion of dixylyl sulfone in the curing agent composition.

[0044] [Checking for cracks in polyvinyl chloride test pieces] The curing agent composition A, the curing agent composition B, and water were mixed to the compositions shown in Examples 1 to 6 and Comparative Example 1 in Table 1, respectively, to obtain the curing agent compositions according to each Example and Comparative Example. 110 g of each curing agent composition according to each Example and Comparative Example and 1.1 g of diisononyl phthalate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were charged into a 200 ml glass bottle and mixed. Next, a 100 × 25 × 3 mm polyvinyl chloride (PVC) test piece (manufactured by TP Giken Co., Ltd.) was fixed with bolts to a rounded polyethylene mounting base with a radius of 130 mm to prepare an immersion test kit. The prepared kit was placed in the bottle containing the curing agent composition. At this time, the test piece in the bottle was half immersed. The bottle was then capped and placed in a 35°C thermostatic chamber for 14 days. After 14 days, the test piece was visually inspected for cracks and evaluated according to the following criteria. The evaluation results are shown in Table 1. A: No cracks B: Fine cracks present C: Large cracks present D: Completely broken

[0045] [Table 1]

[0046] The curing agent compositions according to Examples 1 to 6 did not cause any cracks or only minute cracks in the polyvinyl chloride test pieces, whereas the curing agent composition according to Comparative Example 1 caused the polyvinyl chloride test pieces to break completely. This shows that the curing agent composition according to Comparative Example 1 corresponds to a conventional curing agent composition.

[0047] <Example 7 and Comparative Example 2> [Production of Foundry Composition] Under conditions of 35°C and 55% RH, 0.32 parts by mass of a hardener composition for foundry molding shown in Table 2 was added to 100 parts by mass of furan reclaimed silica sand and mixed. Next, 0.8 parts by mass of Kao Lightner EF-5402 (manufactured by Kao-Quaker Corporation) was added as a binder composition for foundry molding, and the mixture was mixed to obtain a foundry composition.

[0048] [Evaluation of mold compressive strength] The foundry composition immediately after mixing was filled into a cylindrical test piece frame with a diameter of 50 mm and a height of 50 mm. After 30 minutes, the frame was demolded and the compressive strength (MPa) was measured according to the method described in JIS Z 2604-1976. This strength was designated the "compressive strength after 30 minutes." Separately, a foundry composition was similarly filled into a test piece frame, the frame was demolded after 2 hours, and the compressive strength (MPa) was measured according to the method described in JIS Z 2604-1976 24 hours after filling and designated the "compressive strength after 24 hours." A higher value indicates higher mold strength. The evaluation results are shown in Table 2. The mold (Example 7) produced using the curing agent composition according to the present invention (Example 1) had mold strength similar to that of the mold (Comparative Example 2) produced using the curing agent composition according to Comparative Example 1, which corresponds to a conventional curing agent composition. This demonstrates that the mold produced using the curing agent composition according to the present invention has mold strength sufficient for practical use.

[0049] Table 2

Claims

1. A hardener composition for mold making containing at least an acid component, water, and dixylyl sulfone, the acid component contains xylene sulfonic acid, The water content is 50.0% by mass or more and 99.0% by mass or less, A hardener composition for mold making, having a dixylyl sulfone content of more than 0% by mass and less than 0.43% by mass.

2. The hardener composition for mold making according to claim 1 , wherein the acid component contains sulfuric acid.

3. 3. The hardener composition for molding a foundry mold according to claim 2, wherein the content of sulfuric acid in the hardener composition for molding a foundry mold is more than 0% by mass and 30% by mass or less.

4. A foundry composition comprising a binder composition for foundry molding containing refractory particles and an acid-hardening resin, and the hardener composition for foundry molding according to any one of claims 1 to 3.

5. The foundry composition of claim 4 , wherein the acid-hardening resin comprises a furan resin.

6. A method for producing a mold, comprising: a mixing step of mixing a binder composition for foundry formation containing refractory particles and an acid-curing resin with the hardener composition for foundry formation according to any one of claims 1 to 3 to obtain a foundry composition; and a curing step of curing the foundry composition.

7. The method for producing a mold according to claim 6 , wherein the acid-hardening resin contains a furan resin.

8. A hardener composition for mold making containing at least an acid component, water, and dixylyl sulfone, the acid component contains xylene sulfonic acid, The water content is 50.0% by mass or more and 99.0% by mass or less, The content of dixylyl sulfone is more than 0% by mass and less than 0.43% by mass, A hardener composition for mold making, wherein the ratio of the content of dixylyl sulfone to the content of xylene sulfonic acid in the hardener composition for mold making (dixylyl sulfone content / xylene sulfonic acid content) is 0.001 or more and 0.012 or less.

9. 4. Use of the hardener composition for foundry molding according to claim 1 for producing a mold.

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