Method for manufacturing a hardening agent composition for mold making

Abstract

To provide a mold-forming hardening agent composition that can suppress discoloration. [Solution] A method for producing a mold-forming curing agent composition containing xylene sulfonic acid, Step 1: The total content of aliphatic and alicyclic compounds in the decomposition system xylene is 0.2% by mass or less, and A method for producing a curing agent composition for mold making, comprising step 2, after step 1, sulfonating the xylene contained in the decomposition system xylene to obtain xylenesulfonic acid.

Description

Technical Field

[0001] The present invention relates to a method for producing a hardening agent composition for mold molding.

Background Art

[0002] Generally, an acid-curable mold is produced by adding a binder composition for mold molding containing an acid-curable resin and a hardening agent composition containing sulfonic acid, sulfuric acid, phosphoric acid, etc. to refractory particles such as silica sand, kneading them, filling the obtained kneaded sand into a prototype such as a wooden mold, and curing the acid-curable resin. For the acid-curable resin, furan resin, phenolic resin, etc. are used, and for the furan resin, furfuryl alcohol-urea-formaldehyde resin, furfuryl alcohol-formaldehyde resin, furfuryl alcohol-phenol-formaldehyde resin, and other known modified furan resins are used.

[0003] Xylene sulfonic acid may be used as a hardening agent for curing the furan resin (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The hardening agent composition for mold molding containing xylene sulfonic acid is usually transparent brown, but occasionally it turns black and becomes opaque. If it turns black and becomes opaque, there is a risk of being confused with other materials used for mold molding and being used erroneously, and in some cases, it may lead to an accident.

[0006] An object of the present invention is to provide a hardening agent composition for mold molding that can suppress discoloration. [Means for solving the problem]

[0007] The xylene used as a raw material for xylenesulfonic acid is generally industrial-grade xylene. Industrial-grade xylene is broadly classified into modified xylene and decomposed xylene. Investigations revealed that some mold-forming curing agent compositions containing xylenesulfonic acid produced using decomposed xylene discolored. Therefore, analysis was conducted on the decomposed xylene used to produce the xylenesulfonic acid in the discolored mold-forming curing agent compositions and the decomposed xylene used to produce the xylenesulfonic acid in the mold-forming curing agent compositions that did not discolor. The results showed that the decomposed xylene used to produce the xylenesulfonic acid in the discolored mold-forming curing agent compositions contained specific impurities that were not present in the decomposed xylene used to produce the xylenesulfonic acid in the mold-forming curing agent compositions that did not discolor. From this, we found that when a mold-forming curing agent composition containing xylene sulfonic acid is manufactured using decomposed xylene containing the specific impurity, the specific impurity remains in the mold-forming curing agent composition and is included in the composition, causing discoloration of the composition. Based on this finding, we completed the present invention.

[0008] The present invention A method for producing a mold-forming curing agent composition containing xylene sulfonic acid, Step 1: The total content of aliphatic and alicyclic compounds in the decomposition system xylene is 0.2% by mass or less, and The process includes step 2, following step 1, in which the xylene contained in the decomposition system xylene is sulfonated to obtain xylene sulfonic acid. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a mold-forming curing agent composition that can suppress discoloration. [Modes for carrying out the invention]

[0010] <Method for producing a hardening agent composition for mold making> The method for producing the mold-forming curing agent composition of this embodiment (hereinafter also referred to as the curing agent composition) is as follows: A method for producing a mold-forming curing agent composition containing xylene sulfonic acid, Step 1: The total content of aliphatic and alicyclic compounds in the decomposition system xylene is 0.2% by mass or less, and The process is followed by step 2, in which the xylene contained in the decomposition system xylene is sulfonated to obtain xylene sulfonic acid. According to the manufacturing method of this embodiment, a curing agent composition that can suppress discoloration can be produced.

[0011] [Process 1] Decomposition-type xylene is produced by the thermal decomposition of naphtha and is a mixture of o-xylene, m-xylene, p-xylene, and ethylbenzene. In addition to these compounds, it also contains aromatic compounds other than xylene and ethylbenzene, as well as aliphatic and alicyclic compounds. Among these, aliphatic and alicyclic compounds are the causes of discoloration of the curing agent composition. Therefore, from the viewpoint of reducing the content of aliphatic and alicyclic compounds in the curing agent composition and suppressing discoloration of the curing agent composition, the total content of aliphatic and alicyclic compounds in the decomposition-type xylene is set to 0.2% by mass or less, preferably 0.05% by mass or less.

[0012] Examples of aliphatic compounds that may be included in the decomposition system xylene include n-pentane, n-hexane, and n-heptane.

[0013] Examples of alicyclic compounds that may be included in the decomposition system xylene include cyclopentane, cyclohexane, hexylidenecyclopropane, ethylcyclohexane, bicyclo[3.2.1]octane, and 2-ethyl-:2-ethylbicyclo[2.2.1]heptane.

[0014] The method for reducing the total content of aliphatic and alicyclic compounds in the decomposition system xylene to 0.2% by mass or less is not particularly limited, and known methods can be used. An example of a known method for reducing the total content of aliphatic and alicyclic compounds in the decomposition system xylene to 0.2% by mass or less is the method described in Japanese Patent Application Publication No. 10-218798.

[0015] When the total content of aliphatic compounds and alicyclic compounds in the decomposition system xylene is to be 0.2% by mass or less based on the method described in Japanese Patent Publication No. 10-218798, step 1 in the production method according to this embodiment includes, for example, step 1-1 of contacting the decomposition system xylene with sulfuric acid at a temperature of 0°C to 80°C, and step 1-2 of distilling the decomposition system xylene after step 1-1.

[0016] [Process 1-1] The sulfuric acid used in contact with the decomposition-type xylene can be ordinary sulfuric acid, either as is or diluted with water to produce sulfuric acid at a concentration of 50-98%.

[0017] The treatment temperature when contacting the decomposed xylene with sulfuric acid is preferably 0°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher, from the viewpoint of separating xylene and impurities in the decomposed xylene, and similarly preferably 80°C or lower, more preferably 60°C or lower, and even more preferably 50°C or lower.

[0018] In step 1-1, the amount of sulfuric acid used in the contact treatment is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, per 10,000 parts by mass of xylene in the decomposition system xylene, from the viewpoint of separating xylene and impurities in the decomposition system xylene. Similarly, from the same viewpoint, it is preferably 100 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 10 parts by mass or less.

[0019] The aforementioned contact process may be in batch or continuous mode, and there are no particular limitations on pressure or time.

[0020] [Step 1-2] In the step 1-2, xylene is distilled in the presence of sulfuric acid. In the step 1-2, the method for distilling xylene is not particularly limited and can be performed by a known method.

[0021] The distillation temperature in the step 1-2 is preferably 20°C or higher and 200°C or lower.

[0022] [Step 2] In the step 2, except for using the xylene obtained in the step 1, xylene can be sulfonated by a known method to obtain xylene sulfonic acid. Thereby, a curing agent composition containing xylene sulfonic acid can be produced.

[0023] In the step 2, the sulfonium ion source when sulfonating xylene is not particularly limited, and examples thereof include sulfuric acid and fuming sulfuric acid.

[0024] In the step 2, from the viewpoint of promoting the sulfonation reaction, the reaction time when sulfonating xylene is preferably 10 minutes or longer, more preferably 50 minutes or longer, still more preferably 90 minutes or longer, and from the viewpoint of suppressing by-products, it is preferably 150 minutes or shorter, more preferably 120 minutes or shorter, still more preferably 100 minutes or shorter.

[0025] In the step 2, from the viewpoint of promoting the sulfonation reaction, the reaction temperature when sulfonating xylene is preferably 40°C or higher, more preferably 80°C or higher, still more preferably 110°C or higher, and from the viewpoint of suppressing by-products, it is preferably 200°C or lower, more preferably 150°C or lower, still more preferably 120°C or lower.

[0026] In the step 2, from the viewpoint of reducing the residual xylene amount, the amount of sulfuric acid when sulfonating xylene is preferably 145 parts by mass or more, more preferably 165 parts by mass or more, still more preferably 180 parts by mass or more with respect to 100 parts by mass of xylene, and from the viewpoint of reducing residual sulfuric acid, it is preferably 350 parts by mass or less, more preferably 260 parts by mass or less, still more preferably 190 parts by mass or less.

[0027] The curing agent composition may contain components other than xylenesulfonic acid. Examples of components other than xylenesulfonic acid that may be included in the curing agent composition include acid-based curing agents other than xylenesulfonic acid, solvents, etc., that can cure acid-curable resins.

[0028] As the acid-based curing agent, one or more conventionally known compounds can be used, such as sulfonic acid compounds including toluenesulfonic acid (especially p-toluenesulfonic acid) and methanesulfonic acid, phosphoric acid compounds including phosphoric acid and acidic phosphoric acid esters, and sulfuric acid.

[0029] Examples of solvents that may be included in the curing agent composition include water, alcohols, and ether alcohols.

[0030] The total content of xylene sulfonic acid and the other acid-based curing agents in the curing agent composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, from the viewpoint of improving mold strength, and from the viewpoint of dissolving the curing agent composition, it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 80% by mass or less.

[0031] The content of the solvent in the curing agent composition is adjusted as appropriate to obtain the desired reaction rate and mold strength depending on the temperature of the working environment and the temperature of the refractory particles. Generally, from the viewpoint of 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 viewpoint of improving mold strength, 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.

[0032] When producing a curing agent composition containing components other than xylenesulfonic acid, the curing agent composition can be obtained by mixing the components other than xylenesulfonic acid with xylenesulfonic acid using a known method.

[0033] <Mold composition> The mold composition of this embodiment contains refractory particles, a mold-forming binder composition containing an acid-curable resin (hereinafter also referred to as the binder composition), and the curing agent composition.

[0034] [Fire-resistant particles] As the aforementioned refractory particles, one or more conventionally known types such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Used refractory particles that have been recovered or recycled can also be used. Among these, silica sand is preferred.

[0035] [Binding agent composition for mold making] The aforementioned binder composition contains an acid-curable resin as a binder component.

[0036] Examples of the acid-curable resin include one or more selected from the group consisting of furan resin, melamine and aldehyde condensates, urea and aldehyde condensates, and ethyleneurea and aldehyde condensates. From the viewpoint of improving mold strength, the acid-curable resin preferably contains furan resin.

[0037] The furan resin is obtained by polymerizing a monomer composition containing furfuryl alcohol and can be used without particular limitations as long as it can be used as a binder for mold making. The furan resin is obtained from the viewpoint of significantly improving mold strength in low-temperature environments while reducing the content of monomeric furfuryl alcohol, and includes condensates of furfuryl alcohol and urea, furfuryl alcohol and melamine, furfuryl alcohol and ethylene urea, furfuryl alcohol, urea and aldehydes (urea-modified furan resin), furfuryl alcohol, melamine and aldehydes, furfuryl alcohol, ethylene urea and aldehydes, furfuryl alcohol condensate, It is preferable to contain one or more selected from the group consisting of condensates of furfuryl alcohol and aldehydes, and condensates of furfuryl alcohol, phenols and aldehydes, and one or more selected from the group consisting of two or more co-condensates selected from the aforementioned group. It is more preferable to contain one or more selected from the group consisting of urea-modified furan resin, furfuryl alcohol condensates, and condensates of furfuryl alcohol and aldehydes, and one or more selected from the group consisting of two or more co-condensates selected from the aforementioned group.

[0038] Examples of the aforementioned 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 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.

[0039] Examples of the aforementioned phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, and bisphenol F, and one or more of these can be used.

[0040] The furan resin can be produced by known methods. For example, if the furan resin is a urea-modified furan resin, it 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.

[0041] From the viewpoint of improving mold strength, the content of furan resin in the acid-curable 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.

[0042] From the viewpoint of improving mold strength, the content of the acid-curable 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 maintaining good kneadability with the refractory aggregate and suppressing a decrease in mold strength, the content of the acid-curable 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.

[0043] In the above-mentioned mold composition, the mass ratio of the refractory particles, the binder composition, and the curing agent composition can be set as appropriate, but from the viewpoint of improving mold strength, it is preferable that the binder composition is in the range of 0.5 to 1.5 parts by mass and the curing agent is in the range of 0.07 to 1 part by mass per 100 parts by mass of the refractory particles.

[0044] <Method for manufacturing molds> The method for manufacturing a mold according to this embodiment includes a mixing step of mixing the refractory particles, the binder composition, and the curing agent composition to obtain the mold composition, and a curing step of curing the mold composition.

[0045] In the mixing step, there are no particular limitations on the order in which the binder composition, the curing agent composition, and the refractory particles are added and mixed. The binder composition and the curing agent composition may be mixed to produce a mold-making composition, and then the mold-making composition may be mixed with the refractory particles. Alternatively, the binder composition, the curing agent composition, and the refractory particles may be added and mixed separately. However, from the viewpoint of storage stability and mold productivity, it is preferable to mix the binder composition, the curing agent composition, and the refractory particles together to obtain the mold-making composition. Furthermore, from the viewpoint of improving mold strength, if a sample of refractory particles diluted with the curing agent composition is used, the curing agent compositions may be mixed together before addition, or they may be added separately.

[0046] The content of each component in the binder composition and the curing agent composition, as well as the content of each component in the mold composition, can be considered as the blending amounts of each component in the binder composition and the curing agent composition, and the blending amounts of each component in the mold composition.

[0047] In the aforementioned mixing process, known methods can be used to mix each raw material. For example, methods include adding and kneading each raw material using a batch mixer, or supplying each raw material to a continuous mixer and kneading it.

[0048] In the mold manufacturing method of this embodiment, the mold can be manufactured by using the conventional mold manufacturing process as is, except for the mixing step. [Examples]

[0049] <Example 1> [Example of a xylene purification method (Step 1)] 150 ml of decomposition-type xylene (mixed xylene manufactured by Tosoh Corporation) is mixed with 0.10 g of 98% sulfuric acid, stirred at 30°C for 10 minutes, and then simple distillation is performed to obtain 145 ml of purified xylene as the fraction at 145°C.

[0050] [Example of xylene sulfonation (Step 2)] 24.75 g of xylene (a mixture of purified xylene (o-xylene, m-xylene, and p-xylene: ethylbenzene = 50:50); total content of aliphatic and alicyclic compounds 0.00 mass) was charged into a three-necked flask, and 43.12 g of 98% sulfuric acid and 31.24 g of 28% fuming sulfuric acid were added dropwise. The mixture was stirred at 200 rpm and reacted at 115°C for 1.0 hour under reflux with a Liebig bottle cap. After the reaction, 0.99 g of 98% sulfuric acid was added dropwise, and aeration was performed at 65°C or higher to obtain the xylene sulfonic acid stock solution. 62.00 g of denatured alcohol and 5.60 g of water were added to the obtained xylene sulfonic acid stock solution to obtain the curing agent composition according to Example 1.

[0051] <Comparative Example 1> A curing agent composition according to Comparative Example 1 was obtained in the same manner as in Example 1, except that xylene was replaced with decomposition-type xylene (mixed xylene manufactured by Tosoh Corporation).

[0052] <Evaluation Method> [Method for measuring the total content of aliphatic and alicyclic compounds in the decomposition system xylene after step 1] A 1 μl sample of the target decomposition system xylene, diluted 100-fold with methanol, was taken and analyzed by gas chromatography (Shimadzu Corporation, GCMS-QP 2020NX) under the following conditions. Column: J&W DB-5MS 60m x 0.25mm I.D. x 0.25um Column layer temperature: 50°C (1 min) - 10°C / min - 270°C (17 min) Inlet temperature: 250℃ Detector temperature: 250℃ Ion source: Ionization method, EI method (electron ionization method) Ionization voltage: 70 eV (at 250°C) Detector: Gain 0.85kV Scan: Analysis time 0-40 minutes, mass number range 33-400, sampling rate 0.5 seconds

[0053] [Evaluation of whether or not discoloration has occurred] 0.01 g of a 5% Alkali Blue 6B aqueous solution (Alkali Blue 6B manufactured by Yamato Chemical Co., Ltd.) was added to 100 g of the curing agent composition according to the examples and comparative examples, and the appearance was evaluated visually according to the following evaluation criteria. The evaluation results are shown in Table 1. ○: Exhibits a blue color and has high transparency. ×: The blue color has low saturation and low transparency.

[0054] [Table 1]

Claims

1. A method for producing a mold-forming curing agent composition containing xylene sulfonic acid, Step 1: The total content of aliphatic compounds and alicyclic compounds in the decomposition system xylene is 0.2% by mass or less, and A method for producing a curing agent composition for mold making, comprising step 2, after step 1, sulfonating the xylene contained in the decomposition system xylene to obtain xylenesulfonic acid.

2. The method for producing a mold-forming curing agent composition according to claim 1, wherein step 1 comprises step 1-1 of contacting decomposition-type xylene with sulfuric acid at a temperature of 0°C to 80°C, and step 1-2 of distilling the decomposition-type xylene after step 1-1.

3. A method for producing a curing agent composition for mold making according to claim 2, wherein the amount of sulfuric acid used in the contact treatment in step 1-1 is 0.1 parts by mass or more and 100 parts by mass or less with respect to 10,000 parts by mass of xylene in the decomposition system xylene.

4. A method for producing a mold-forming curing agent composition according to claim 2, wherein the distillation temperature in step 1-2 is 20°C or higher and 200°C or lower.

5. A method for producing a mold-forming curing agent composition according to claim 1, wherein the reaction time for sulfonating xylene in step 2 is 10 minutes or more and 150 minutes or less.

6. A method for producing a mold-forming curing agent composition according to claim 1, wherein the reaction temperature when sulfonating xylene in step 2 is 40°C or more and 200°C or less.

7. A method for producing a mold-forming curing agent composition according to any one of claims 1 to 6, wherein the amount of sulfuric acid used to sulfonate xylene in step 2 is 145 parts by mass or more and 350 parts by mass or less per 100 parts by mass of xylene.

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