CN107150103B

CN107150103B - Mold molding set, mold molding sand composition, and method for producing same

Info

Publication number: CN107150103B
Application number: CN201710112858.0A
Authority: CN
Inventors: 永井康弘; 饭塚毅; 原泽大; 竹下幸佑
Original assignee: Gun Ei Chemical Industry Co Ltd
Current assignee: Gun Ei Chemical Industry Co Ltd
Priority date: 2016-03-02
Filing date: 2017-02-28
Publication date: 2020-05-05
Anticipated expiration: 2037-02-28
Also published as: JP6736313B2; JP2017154157A; CN107150103A

Abstract

The molding kit of the present invention contains the following components (A), (B) and (C). The molding sand composition of the present invention is a mixture of the following components (a), (B), (C), and (D). The method for producing a sand composition for mold making of the present invention comprises mixing the following component (a), component (B), component (C), and component (D) in a specific order. (A) The components: magnesium sulfate or ammonium sulfate; (B) the components: an acid curing agent; (C) the components: a binder comprising furfuryl alcohol; (D) the components: a refractory particulate material.

Description

Mold molding set, mold molding sand composition, and method for producing same

Technical Field

The present invention relates to a mold molding set, a mold molding sand composition, and a method for producing the same.

This application claims priority based on application 2016-.

Background

Conventionally, as one of casting molds, a self-hardening mold is known. The self-curing mold is manufactured by the following method: a binder (acid-curable binder) mainly composed of an acid-curable resin and a curing agent such as sulfuric acid or xylene sulfonic acid are added to a refractory particulate material such as silica sand and kneaded, and the resulting kneaded sand is filled into a mold to cure the binder (see non-patent document 1).

The acid-curable resin is generally a resin (furan resin) mainly composed of furfuryl alcohol, urea, phenol, formaldehyde, or the like. The acid-curable resin is a structure that is cured by polycondensation while performing a dehydration reaction with an acid (curing agent), and the progress of curing is affected by water generated by the dehydration reaction. Therefore, the surface portion of the mold which is likely to come into contact with air tends to be easily solidified due to the progress of the dehydration reaction, but the interior portion of the mold which is less likely to come into contact with air tends to be less likely to be solidified due to the progress of the dehydration reaction. Therefore, the self-curing mold using the acid-curable binder may have a difference in the degree of curing between the inside and the surface thereof, and the strength may be insufficient.

In addition, in the case of a low temperature such as in winter, the curing rate is reduced as a whole, and therefore, the binder tends to be hard to cure, and it is difficult to obtain a mold having sufficient strength.

Therefore, for example, a method has been proposed in which sulfuric acid is often used as a curing agent, and the difference in the degree of curing between the inside and the surface of the mold is reduced by increasing the overall curing speed. Further, since the solidification rate is increased by using a large amount of sulfuric acid, a mold having sufficient strength can be easily obtained even in a low temperature environment such as in winter.

Documents of the prior art

Non-patent document

Non-patent document 1: "cast molding method", fourth edition, society of Law, Japan society for foundry technology, 8 years, 11 months, 18 days, p 136-137

Disclosure of Invention

Problems to be solved by the invention

However, in the case of the method using a large amount of sulfuric acid, a curing agent having a sulfuric acid content of more than 10 mass% is generally used. Since such a curing agent is a designation for a substance harmful to the outside of medical use, the standard for storage and management of the curing agent is becoming strict.

Further, since sulfuric acid is a strong acid, the treatment of a curing agent containing a large amount of sulfuric acid requires careful attention, and workability may be deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a mold molding set and a mold molding sand composition that can produce a mold having a sufficient solidification rate and high strength even if the amount of sulfuric acid used is reduced, and a method for producing the same.

Means for solving the problems

The present invention has the following aspects.

[1] A molding kit for a mold, comprising the following components (A), (B) and (C).

(A) The components: magnesium sulfate or ammonium sulfate;

(B) the components: an acid curing agent;

(C) the components: a binder comprising furfuryl alcohol.

[2] The set for mold making according to [1], further comprising the following component (D).

(D) The components: a refractory particulate material.

[3] The set for mold making according to [1] or [2], wherein the component (B) comprises sulfuric acid.

[4] The mold molding kit according to any one of [1] to [3], wherein the component (C) further contains at least one selected from the following components (C1), (C2) and (C3).

(C1) The components: at least one compound selected from phenols and urea;

(C2) the components: a reactant selected from furfuryl alcohol and (C1) and an aldehyde;

(C3) the components: a condensate of furfuryl alcohol.

[5] A sand composition for mold making which is a mixture of the following components (A), (B), (C) and (D).

(A) The components: magnesium sulfate or ammonium sulfate;

(B) the components: an acid curing agent;

(C) the components: a binder comprising furfuryl alcohol;

(D) the components: a refractory particulate material.

[6] The sand composition for mold making according to [5], wherein the component (B) comprises sulfuric acid.

[7] The sand composition for mold making according to [5] or [6], wherein the component (C) further comprises at least one selected from the following components (C1), (C2) and (C3).

(C1) The components: at least one compound selected from phenols and urea;

(C3) the components: a condensate of furfuryl alcohol.

[8] A method for producing a sand composition for mold making according to any one of [5] to [7], comprising a step (I) of mixing the component (D) with the component (A), a step (II) of mixing the mixture (I) obtained in the step (I) with the component (B), and a step (III) of mixing the mixture (II) obtained in the step (II) with the component (C).

[9] A method for producing a sand composition for mold making according to any one of [5] to [7], comprising a step (IV) of mixing the component (D) with the component (B), a step (V) of mixing the mixture (IV) obtained in the step (IV) with the component (C), and a step (VI) of mixing the mixture (V) obtained in the step (V) with the component (A).

Effects of the invention

According to the present invention, it is possible to provide a mold molding set and a mold molding sand composition that can produce a mold having a sufficient solidification rate and high strength even if the amount of sulfuric acid used is reduced, and a method for producing the mold molding sand composition.

Detailed Description

In the following description, the "mold" is a structure molded by using the mold molding package of the present invention or the mold molding sand composition of the present invention.

[ Package for Molding mold ]

The molding kit of the present invention comprises the following components (A), (B) and (C). The molding kit of the present invention may contain the following component (D). The component (A), the component (B), the component (C) and the component (D) are present in a non-contact state, i.e., in a non-contact state, until immediately before use of the mold package. The molding kit may be, for example, an aggregate of containers each containing each component.

(A) The components: magnesium sulfate or ammonium sulfate;

(B) the components: an acid curing agent;

(C) the components: a binder comprising furfuryl alcohol;

(D) the components: a refractory particulate material.

< ingredient (A) >

(A) The ingredient is magnesium sulfate or ammonium sulfate.

Magnesium sulfate is particularly preferable as the component (A) because the initial strength of the mold is higher.

The magnesium sulfate may be an anhydride or a hydrate.

< ingredient (B) >

(B) The component (A) is an acid curing agent.

Examples of the component (B) include sulfuric acid, organic sulfonic acids, and carboxylic acids. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The organic sulfonic acid is an organic compound in which a sulfo group is replaced by a carbon skeleton.

Examples of the organic sulfonic acid include xylene sulfonic acid, p-toluene sulfonic acid, benzene sulfonic acid, and methane sulfonic acid. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds. Among them, xylene sulfonic acid is preferable because it has excellent performance as a curing agent and is liquid at ordinary temperature.

The carboxylic acid does not exhibit a curing action at a low temperature, but if the temperature is increased, the carboxylic acid exerts a curing action and functions as a curing agent.

Examples of the carboxylic acid include lactic acid, citric acid, malic acid, tartaric acid, malonic acid, succinic acid, maleic acid, oxalic acid, acetic acid, benzoic acid, and phosphoric acid. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The component (B) is particularly preferably in the following form.

i) An acid curing agent comprising sulfuric acid.

ii) an acid curing agent having a sulfuric acid content (concentration) of 10% by mass or less (here, the sulfuric acid content is an amount relative to the total mass of the acid curing agent. ).

In the form i), the content (concentration) of sulfuric acid is preferably 3% by mass or more, and more preferably 5% by mass or more, based on the total mass of the component (B). If the content of sulfuric acid is 3% by mass or more, the curing speed can be further increased.

In the form i), the upper limit of the content of sulfuric acid with respect to the total mass of the component (B) is not particularly limited, and may be more than 10 mass%, but is preferably 50 mass% or less, more preferably 40 mass% or less, and still more preferably 30 mass% or less. However, since the mold molding kit of the present invention can produce a mold having a sufficient curing rate and high strength even when the amount of sulfuric acid used is reduced, it is not necessary to make the content of sulfuric acid more than 10 mass%. The content of sulfuric acid with respect to the total mass of the component (B) is preferably 10 mass% or less in consideration of handling properties, workability, and the like.

When the component (B) contains water, the total mass of the component (B) also contains the water content in the component (B).

In the form of ii), the content (concentration) of sulfuric acid is 10 mass% or less, more preferably 8 mass% or less, with respect to the total mass of the component (B). The mold molding kit of the present invention can produce a mold having a sufficient curing rate and high strength even if the content of sulfuric acid is 10 mass% or less.

In consideration of handling property, workability, and the like, the smaller the content of sulfuric acid, the more preferable. The mold molding kit of the present invention can produce a mold having a sufficient solidification rate and high strength even if the content of sulfuric acid is 10% by mass or less, and therefore the content of sulfuric acid can be 0% by mass.

When an acid curing agent having a sulfuric acid content of 0 mass% is used as the component (B), it is preferable to increase the contents of the components (a) and (B) in the mold making kit.

In the form i) or ii), the sulfuric acid and at least one of an organic sulfonic acid and a carboxylic acid are preferably contained, and more preferably at least an organic sulfonic acid is contained.

(B) The component (b) may be used in the form of an aqueous solution. The content of water is preferably 25 to 50% by mass, more preferably 30 to 60% by mass, based on the total mass of the component (B).

< ingredient (C) >

(C) The ingredient is a binder containing furfuryl alcohol.

(C) The component (B) is a substance condensed and solidified by an acid (component (B)).

(C) The component (C) preferably contains at least one selected from the following components (C1), (C2) and (C3) in addition to furfuryl alcohol. In the present invention, furfuryl alcohol, the following component (C1), component (C2), and component (C3) are collectively referred to as a "binder component".

(C1) The components: at least one compound selected from phenols and urea;

(C3) the components: a condensate of furfuryl alcohol.

Examples of the phenols include phenol, cresol, resorcinol, bisphenol a, bisphenol C, bisphenol E, bisphenol F, bisphenol Z, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

Examples of the aldehydes include formaldehyde, glyoxal, and furfural. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds. However, depending on the type of the component (C1), when glyoxal or furfural is used alone as the aldehyde, the acid curing may not sufficiently progress. In such a case, at least formaldehyde may be used as the aldehyde.

(C) Component (C) preferably comprises component (C2), and particularly preferably comprises a reactant of urea and aldehydes. The component (C) contains a reactant of urea and aldehydes, and thus the normal temperature strength of the mold is further improved.

The reactant of urea and aldehyde includes methylolated urea which is an adduct of urea and aldehyde, and methyleneated urea which is a condensate of methylolated urea.

Here, an example of the adduct and the condensate will be described below, taking a case where the aldehyde is formaldehyde.

When urea is reacted with formaldehyde in the presence of a basic catalyst, formaldehyde is added to urea as follows to produce 1 to 3 hydroxymethyl groups (-CH) in 1 molecule₂OH) methylolated urea.

[ chemical formula 1]

The ratio of each methylolated urea in the above mixture varies depending on the ratio of urea to formaldehyde, and therefore cannot be generally said, but the methylolated urea having 1 or 2 methylol groups in 1 molecule is a main component. The more the number of hydroxymethyl groups in 1 molecule increases, the smaller the rate of formation due to steric hindrance.

The main component herein means 50 mass% or more of 100 mass% of the mixture.

In the present invention, "in 100 mass% means" with respect to the total mass ". For example, "in 100% by mass of the mixture" means "with respect to the total mass of the mixture" that is, "when the total mass of the mixture is 100% by mass".

When the reaction system is changed from basic to acidic in the state where hydroxymethylated urea is produced, hydroxymethylated urea is condensed with each other as shown below to produce methyleneated urea.

In the following formulae, the moiety other than the methylol group of the methylolated urea is represented by "R" or "R'" for the sake of simplifying the chemical formula.

[ chemical formula 2]

The reaction of urea with formaldehyde as described above can be carried out in furfuryl alcohol, for example, as described below. According to the following method, the urea is obtained in a state where a reactant of urea and aldehydes is dissolved in furfuryl alcohol.

First, furfuryl alcohol, urea, and aldehydes are mixed, and an aqueous solution of an alkaline catalyst (e.g., sodium hydroxide, potassium hydroxide, etc.) is added to adjust the pH of the mixture to 9 to 10. The mixture is heated to react urea with aldehydes (first addition reaction), to obtain, for example, an adduct of urea and aldehydes (hydroxymethylated urea) as described above. The ratio of urea to aldehydes (aldehydes/urea) is preferably 1.5 to 2.0 in terms of a molar ratio.

Next, an acidic catalyst (e.g., hydrochloric acid, sulfuric acid, etc.) is added to the reaction solution, the pH of the reaction solution is adjusted to 2 to 4, and the condensation reaction of hydroxymethylated urea proceeds to obtain, for example, a condensate of hydroxymethylated urea (methyleneated urea) described above.

An aqueous solution of an alkaline catalyst (e.g., sodium hydroxide, potassium hydroxide, etc.) is added to the reaction solution again to adjust the pH of the reaction solution to 9 to 10, and urea is further added. In the first addition reaction, since the aldehyde is used in excess of the urea, the aldehyde is free in the reaction liquid. The reaction solution is made alkaline again, and urea is added to react the free aldehydes with urea (second addition reaction) to obtain an adduct of urea and aldehydes (hydroxymethylated urea).

The reason why the addition reaction is carried out in 2 stages is as follows.

That is, when the proportion of the methylated urea in furfuryl alcohol is increased, precipitation occurs. Hydroxymethylated urea and methyleneated urea are present in the furfuryl alcohol in moderate proportions to maintain the methyleneated urea in solution in the furfuryl alcohol. Thus, as described above, it is preferable to carry out the second addition reaction after the condensation reaction to produce hydroxymethylated urea.

Most of furfuryl alcohol exists in a free state in the reaction liquid, but a part of furfuryl alcohol may react with aldehydes in the reaction of urea with aldehydes.

The reactant of urea and aldehyde may be the component (C) obtained by reacting urea and aldehyde in the absence of furfuryl alcohol and then mixing them with furfuryl alcohol or the like.

(C2) When the component (b) is a reaction product of furfuryl alcohol and an aldehyde, it is preferable to use 0.1 to 1 mole of the aldehyde per 1 mole of furfuryl alcohol. If the amount of the aldehyde used is 0.1 mol or more, the resulting condensate has a low polymerization degree, and therefore the final mold strength will be well expressed.

(C2) When the component (b) is a reaction product of a phenol and an aldehyde, it is preferable to use 1 to 3 moles of the aldehyde based on 1 mole of the phenol. If the amount of the aldehyde used is 1 mole or more, the setting of the pot life becomes easy because it becomes a condensate having a low polymerization degree, and if it is 3 moles or less, it becomes a condensate having a high polymerization degree, and the expression of the final mold strength becomes good.

The component (C) is particularly preferably in the following form because the usable time can be easily set and the mold strength can be further improved.

iii) a mixture of furfuryl alcohol and a reactant obtained by condensing urea, furfuryl alcohol and aldehydes.

iv) a mixture of furfuryl alcohol and a reactant of urea and aldehydes.

v) a mixture of furfuryl alcohol and a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde, and a reactant of a phenol and an aldehyde.

vi) mixtures of reactants of phenols and aldehydes with furfuryl alcohol.

In the form of iii), the content of the reactant obtained by condensing urea, furfuryl alcohol, and aldehydes is preferably 15 to 45 mass%, more preferably 25 to 35 mass%, with respect to the total mass of the component (C). The furfuryl alcohol content is preferably 55 to 85 mass%, more preferably 65 to 75 mass%.

In the form of iv), the content of the reactant of urea and aldehydes is preferably 3.5 to 20% by mass, more preferably 6.9 to 13.5% by mass, based on the total mass of the component (C). The furfuryl alcohol content is preferably 80 to 96.5 mass%, more preferably 86.5 to 93.1 mass%.

In the form of v), the content of the reactant obtained by condensing urea, furfuryl alcohol, and aldehydes is preferably 7.5 to 22.5% by mass, and more preferably 12.5 to 17.5% by mass, based on the total mass of the component (C). The content of the reactant of phenols and aldehydes is preferably 7.5 to 22.5% by mass, more preferably 12.5 to 17.5% by mass. The furfuryl alcohol content is preferably 55 to 85 mass%, more preferably 65 to 75 mass%.

In the form of vi), the content of the reactant of phenols and aldehydes is preferably 10 to 40% by mass, more preferably 20 to 30% by mass, based on the total mass of the component (C). The content of furfuryl alcohol is preferably 60 to 90 mass%, more preferably 70 to 80 mass%.

When the component (C) contains water, the total mass of the component (C) also contains the water content in the component (C).

The content of the binder component relative to the total mass of the component (C) is preferably 2 to 98 mass%, more preferably 70 to 98 mass%, and still more preferably 81.5 to 94.5 mass%. When the content of the binder component is 2% by mass or more, the usable time can be easily set, and the initial strength of the mold tends to be further improved, and when the content is 98% by mass or less, the final strength of the mold tends to be further improved.

The nitrogen atom content of urea or the like is preferably 0.1 to 6% by mass, more preferably 0.4 to 4.5% by mass, based on the total mass of the component (C).

The content of nitrogen atoms derived from urea or the like affects the initial strength and the final strength of the mold, and when the content of nitrogen atoms is low, the initial strength of the mold tends to be high, and when the content of nitrogen atoms is high, the final strength of the mold tends to be high.

Therefore, it is preferable to adjust the nitrogen atom content as needed, and if the nitrogen atom content is within the above range, a mold having both preferable initial strength and preferable final strength can be obtained.

(C) The component (b) may contain a component (arbitrary component) other than the binder component.

Examples of the optional component include a silane coupling agent, a formaldehyde reducing agent, and water.

If the component (C) contains a silane coupling agent, the strength of the mold is further improved.

Examples of the silane coupling agent include N- β (aminoethyl) γ -aminopropylmethyldimethoxysilane and the like.

The content of the silane coupling agent is preferably 0.01 to 3% by mass, more preferably 0.1 to 1% by mass, based on the total mass of the component (C). If the content of the silane coupling agent is 0.01% by mass or more, the strength of the mold can be improved, and if it is 3% by mass or less, a significant increase in cost can be suppressed.

The formaldehyde reducing agent is used for reducing formaldehyde generated when molten metal is poured into a mold.

Examples of the formaldehyde reducing agent include urea, resorcinol, pyrogallol, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The content of the formaldehyde reducing agent is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, based on the total mass of the component (C). If the content of the formaldehyde reducing agent is 0.1% by mass or more, the component (C) is excellent in reduction of formaldehyde, and if the content is 5% by mass or less, a significant increase in cost can be suppressed.

The water includes all of water obtained from condensation water generated when a reaction product of the (C1) component and the aldehyde is synthesized, water supplied by a raw material in an aqueous solution state (for example, formalin or the like), and water separately added as necessary.

The content of water is preferably 1 to 25% by mass based on the total mass of the component (C). When the water content is 1% by mass or more, the strength of the mold tends to be easily expressed, and when the water content is 25% by mass or less, the curing property of the component (C) tends to be further improved, and a mold having high strength tends to be easily obtained.

When the component (C) includes at least one of the component (C2) and the component (C3), the component (C) generally contains about 3 to 15 mass% of water as water resulting from condensation of water generated during synthesis of the component (C2) and the component (C3). Thus, when the water content in the component (C) is less than 3 mass%, it is necessary to remove water from the component (C).

From the viewpoint of the fire-fighting law, the content of water with respect to the total mass of the component (C) is preferably 20 to 25 mass%. If the water content is 20 to 25 mass%, the water does not have a flash point and thus does not correspond to a dangerous substance in the fire-fighting method. That is, since the component (C) is treated as a non-hazardous substance, the handling property of the component (C) is improved.

< ingredient (D) >

(D) The component is a refractory particulate material.

As the component (D), conventionally known materials such as silica sand, chrome sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, and the like can be used. Further, sand (recovered sand) obtained by recovering the used refractory particulate material, sand (reclaimed sand) obtained by a reclamation process, or the like may be used. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds. Particularly, chromium sand, zirconium sand, and alumina sand are preferable for the portion requiring fire resistance.

< content >

The contents of the respective components are as follows.

The content of the component (a) is in terms of an acid anhydride. In the case where the component (B) contains water, the content of the component (B) also contains the content of water in the component (B), and in the case where the component (C) contains water, the content of the component (C) also contains the content of water in the component (C).

(A) The mass ratio of the component (a) to the component (B), (component (a), (B), and preferably 1: 0.5-1: 10, more preferably 1: 1-1: 3, more preferably 1: 1-1: 2. (A) if the ratio of the component (B) to the component (B) is too small, curability may be insufficient, and if it is too large, the final strength of the mold may be reduced.

(B) The mass ratio of the component (B) to the component (C), (component (B), (C)), is preferably 1: 2-1: 10, more preferably 1: 2.5-1: 5. (C) if the ratio of the component (B) to the component (A) is too small, the final strength of the mold may be reduced, and if too large, the mold may be degraded after injection.

(A) The mass ratio of the total of the component(s) and the component (B) to the component (C) ({ (A) component + (B) component }/(C) component) is preferably 0.1 to 10, more preferably 0.3 to 5, and still more preferably 0.5 to 2. (C) If the ratio of the component (a) to the total of the components (a) and (B) is too small, the final strength of the mold may decrease, and if too large, the mold may have a reduced disintegratability after injection.

The contents of the respective components when the kit for mold making contains the component (D) are as follows.

(A) The content of component (D) is preferably 0.05 to 0.5 parts by mass, more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of component (D). When the content of the component (A) is within the above range, sufficient curing properties can be obtained even if the content of sulfuric acid in the component (B) is 10% by mass or less, and the mold strength can be made good.

If the content of the component (A) is less than 0.05 parts by mass, curing properties may become insufficient. On the other hand, if the content of the component (A) exceeds 0.5 parts by mass, the curing properties are good, but the final strength of the mold may be lowered. The reason is considered that if the content of the component (A) is increased, sulfuric acid is excessively generated by a reaction with the component (B), and the curing of the component (C) is completed earlier, as described in detail later.

In particular, when the component (B) does not contain sulfuric acid, the content of the component (A) is preferably 0.2 to 0.5 parts by mass with respect to 100 parts by mass of the component (D).

(B) The content of the component (D) is preferably 0.045 to 1.2 parts by mass, more preferably 0.075 to 0.9 parts by mass, per 100 parts by mass of the component (D). When the content of the component (B) is within the above range, a mold having a higher strength can be easily obtained. In particular, when the component (B) does not contain sulfuric acid, the content of the component (B) is preferably 0.1 to 1.0 part by mass per 100 parts by mass of the component (D).

(C) The content of component (D) is preferably 0.3 to 2.0 parts by mass, more preferably 0.5 to 1.5 parts by mass, per 100 parts by mass of component (D). When the content of the component (C) is 0.3 parts by mass or more, a mold having a higher strength can be easily obtained, and when the content is 2.0 parts by mass or less, the mold after injection can be easily disassembled.

< Effect >

The mold molding kit of the present invention described above contains component (A), component (B) and component (C). When the component (a) is contacted with the component (B), sulfuric acid is produced due to a metathesis reaction. The generated sulfuric acid has a curing catalyst function in the same manner as the component (B). The mold molding kit of the present invention can utilize the generated sulfuric acid for the curing of the component (C), and therefore, it is possible to produce a mold having a sufficient curing rate and high strength even when the amount of the component (B), i.e., the amount of the sulfuric acid used as the acid curing agent, is reduced during the production of the mold.

Further, since the component (B) containing sulfuric acid in an amount exceeding 10 mass% is a specification of a harmful substance for medical use, the storage and management standards are strict, and the handling of the component (B) requires careful attention, which may reduce workability.

However, if the mold molding kit of the present invention is used, a mold having a sufficient curing rate and high strength can be produced without using the component (B) containing sulfuric acid in an amount exceeding 10 mass%. Thus, since the component (B) can be used without being separated from the prescribed hazardous substance for medical use, the storage and management are easy, and the workability is excellent.

[ Sand composition for Molding mold ]

The molding sand composition of the present invention (hereinafter, also simply referred to as "sand composition") is a mixture of the following components (a), (B), (C) and (D).

(A) The components: magnesium sulfate or ammonium sulfate;

(B) the components: an acid curing agent;

(C) the components: a binder comprising furfuryl alcohol;

(D) the components: a refractory particulate material.

The components (a), (B), (C) and (D) contained in the sand composition are the same as the components (a), (B), (C) and (D) exemplified previously in the description of the mold making kit of the present invention, and therefore, the description thereof is omitted.

(A) The content of component (D) is preferably 0.05 to 0.5 parts by mass, more preferably 0.1 to 0.3 parts by mass, per 100 parts by mass of component (D). When the content of the component (A) is within the above range, sufficient curing properties can be obtained even if the content of sulfuric acid in the component (B) is 10% by mass or less, and the mold strength can be made good. In particular, when the component (B) does not contain sulfuric acid, the content of the component (A) is preferably 0.2 to 0.5 parts by mass with respect to 100 parts by mass of the component (D).

(B) The content of the component (D) is preferably 0.045 to 1.2 parts by mass, more preferably 0.075 to 0.9 parts by mass, per 100 parts by mass of the component (D). When the content of the component (B) is within the above range, a mold having a higher strength can be easily obtained. Particularly, when the component (B) does not contain sulfuric acid, the content of the component (B) is preferably 0.1 to 1.0 part by mass with respect to 100 parts by mass of the component (D).

< method for producing Sand composition >

The following embodiments can be mentioned as a method for producing the sand composition.

(first embodiment)

The method for producing the sand composition of the present embodiment includes the following steps (I), (II), and (III).

A step (I): mixing the component (D) with the component (A).

Step (II): and (B) mixing the mixture (I) obtained in step (I) with the component (B).

Step (III): and (C) mixing the mixture (II) obtained in step (II) with the component (C).

In the step (I), the component (D) and the component (a) are mixed to obtain a mixture (I).

(D) The mixing ratio of the component (A) to the component (A) is preferably 0.05 to 0.5 parts by mass per 100 parts by mass of the component (D).

In the step (II), the mixture (I) and the component (B) are mixed to obtain a mixture (II).

The mixing ratio of the mixture (I) and the component (B) is preferably a ratio of 0.045 to 1.2 parts by mass of the component (B) to 100 parts by mass of the component (D) in the mixture (I).

In the step (III), the mixture (II) and the component (C) are mixed to obtain a sand composition.

The mixing ratio of the mixture (II) and the component (C) is preferably a ratio of 0.3 to 2.0 parts by mass of the component (C) to 100 parts by mass of the component (D) in the mixture (II).

In the step (I), the step (II) and the step (III), the mixing method is not particularly limited as long as it is a general mixing method, and examples thereof include a method using a stirrer or the like.

(second embodiment)

The method for producing the sand composition of the present embodiment includes the following steps (IV), (V), and (VI).

Step (IV): mixing the component (D) with the component (B).

Step (V): and (C) mixing the mixture (IV) obtained in step (IV) with the component (C).

Step (VI): and (c) mixing the mixture (V) obtained in step (V) with the component (a).

In the step (IV), the component (D) and the component (B) are mixed to obtain a mixture (IV).

(D) The mixing ratio of the component (B) to the component (B) is preferably 0.045 to 1.2 parts by mass relative to 100 parts by mass of the component (D).

In the step (V), the mixture (IV) and the component (C) are mixed to obtain a mixture (V).

The mixing ratio of the mixture (IV) and the component (C) is preferably a ratio of 0.3 to 2.0 parts by mass of the component (C) to 100 parts by mass of the component (D) in the mixture (IV).

In the step (VI), the mixture (V) and the component (a) are mixed to obtain a sand composition.

The mixing ratio of the mixture (V) and the component (a) is preferably a ratio of 0.05 to 0.5 parts by mass of the component (a) to 100 parts by mass of the component (D) in the mixture (V).

In the step (IV), the step (V) and the step (VI), the mixing method is not particularly limited as long as it is a general mixing method, and for example, a method using a stirrer or the like is exemplified.

(third embodiment)

The method for producing a sand composition of the present embodiment includes the following steps (VII), (VIII), and (IX).

Step (VII): mixing the component (D) with the component (A).

Step (VIII): and (C) mixing the mixture (VII) obtained in step (VII) with the component (C).

Step (IX): and (c) mixing the mixture (VIII) obtained in the step (VIII) with the component (B).

In the step (VII), the component (D) and the component (a) are mixed to obtain a mixture (VII).

In the step (VIII), the mixture (VII) is mixed with the component (C) to obtain a mixture (VIII).

The mixing ratio of the mixture (VII) and the component (C) is preferably a ratio of 0.3 to 2.0 parts by mass of the component (C) to 100 parts by mass of the component (D) in the mixture (VII).

In the step (IX), the mixture (VIII) and the component (B) are mixed to obtain a sand composition.

The mixing ratio of the mixture (VIII) and the component (B) is preferably a ratio of 0.045 to 1.2 parts by mass of the component (B) to 100 parts by mass of the component (D) in the mixture (VIII).

In the step (VII), the step (VIII) and the step (IX), the mixing method is not particularly limited as long as it is a general mixing method, and for example, a method using a stirrer or the like is exemplified.

< Effect >

The sand composition of the present invention described above is a mixture of the component (a), the component (B), the component (C), and the component (D). When the component (A) is brought into contact with the component (B), sulfuric acid is produced due to the metathesis reaction. The generated sulfuric acid has a curing catalyst function in the same manner as the component (B). The sand composition of the present invention can utilize the generated sulfuric acid for curing the component (C), and therefore, a mold having a sufficient curing rate and high strength can be produced even when the amount of the component (B), i.e., the amount of the sulfuric acid used as an acid curing agent, is reduced during the production of the mold.

However, if the sand composition of the present invention is used, a mold having a sufficient solidification rate and high strength can be produced without using the component (B) containing sulfuric acid in an amount exceeding 10 mass%. Thus, since the component (B) can be used without being separated from the prescribed hazardous substance for medical use, the storage and management are easy, and the workability is excellent.

In addition, the sand composition of the present invention can be easily produced by the above-described method for producing a sand composition.

However, as described above, the component (B) may be used in the form of an aqueous solution, and the component (C) may contain water. For example, when the component (D) is mixed with the component (C) and then the component (B) is mixed, if the component (D) is impregnated with water derived from the component (C), the dispersibility of the component (B) in the mixture may be reduced and the component (C) may be unevenly cured. Therefore, it is preferable to mix the component (B) and the component (D) in advance before mixing the component (C) and the component (D), and specifically, the method for producing the sand composition of the first embodiment and the second embodiment is preferable.

In addition, when the component (D) is mixed with the component (B) or the component (D) is mixed with the component (C) and then the component (a) is mixed, if the component (D) is wetted with water derived from the component (B) or water derived from the component (C), the component (a) becomes powdery, and hence the mixing dispersion may be reduced. This problem is significant when the sand composition is continuously produced or when a large amount of the sand composition is produced. Therefore, when a sand composition is continuously produced or a large amount of sand composition is produced, it is preferable to mix the component (a) and the component (D) in advance before mixing the component (B), the component (C), and the component (D), and specifically, the method for producing a sand composition according to the first embodiment is preferable.

In the case of producing a sand composition in a batch manner or in the case of producing a small amount of sand composition, it is preferable to add the component (a) at the end, and specifically, the method for producing a sand composition according to the second embodiment is preferable.

[ method for producing mold ]

A mold is manufactured using the mold molding set or sand composition of the present invention.

When a mold is produced using the mold making kit of the present invention, the component (a), the component (B), the component (C), and the component (D) contained in the mold making kit are mixed to prepare a sand composition, the obtained sand composition is filled into a mold for mold production, and the component (C) in the sand composition is solidified to produce a mold. The order of mixing the components is preferably the same as in the methods for producing the sand compositions of the first, second, and third embodiments described above. When the mold kit does not contain component (D), component (D) is prepared separately from the mold kit, and component (a), component (B), and component (C) contained in the mold kit are mixed with component (D) prepared separately.

When a casting mold is produced using the sand composition of the present invention, the sand composition is filled into a mold for producing a casting mold, and the component (C) in the sand composition is solidified to produce a casting mold.

As a method for producing a mold, a self-setting mold molding method can be used. That is, when the sand composition is filled into a mold for mold molding, the component (C) in the sand composition is solidified by the action of sulfuric acid generated by the double decomposition reaction between the component (a) and the component (B) and the action of the unreacted component (B) that has not undergone the double decomposition reaction. As a result, a mold can be obtained.

An example of the embodiment of the present invention is shown below.

The components in the following embodiments are as follows.

(A) The components: magnesium sulfate or ammonium sulfate;

(B) the components: an acid curing agent;

(B-i) component (A): an acid curing agent comprising sulfuric acid;

(B-ii) component (A): an acid curing agent having a sulfuric acid content of 10 mass% or less with respect to the total mass of the acid curing agent;

(C) the components: a binder comprising furfuryl alcohol;

(C-iii) component (iv): a binder which is a mixture of furfuryl alcohol and a reactant obtained by condensing urea, furfuryl alcohol, and an aldehyde;

(C-iv) component (C): a binder which is a mixture of furfuryl alcohol and reactants of urea and aldehydes;

(C-v) component: a binder which is a mixture of furfuryl alcohol and a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde, and a reactant of a phenol and an aldehyde;

(C-vi) component (C-vi): a binder which is a mixture of furfuryl alcohol and reactants of phenols and aldehydes;

(D) the components: a refractory particulate material.

[10] A molding kit comprising the above-mentioned component (A), component (B-i) and component (C).

[11] A molding sand composition comprising the above-mentioned component (A), component (B-i), component (C) and component (D).

[12] The set for mold making according to [10] or the sand composition for mold making according to [11], wherein a content of sulfuric acid with respect to a total mass of the component (B-i) is 3 to 10 mass%.

[13] A molding kit comprising the above-mentioned component (A), component (B-ii) and component (C).

[14] A molding sand composition comprising the above-mentioned component (A), component (B-ii), component (C) and component (D).

[15] The set for mold making according to [13] or the sand composition for mold making according to [14], wherein the component (B-ii) contains at least one of an organic sulfonic acid and a carboxylic acid.

[16] The mold making kit according to [13] or the mold making sand composition according to [14], wherein the component (B-ii) contains not sulfuric acid but an organic sulfonic acid.

[17] A molding kit comprising the above-mentioned component (A), component (B) and component (C-iii).

[18] A molding sand composition comprising the above-mentioned component (A), component (B), component (C-iii) and component (D).

[19] The set for mold molding according to [17] or the sand composition for mold molding according to [18], wherein a content of a reactant obtained by condensing urea, furfuryl alcohol and aldehydes is 15 to 45 mass% and a content of furfuryl alcohol is 55 to 85 mass% with respect to a total mass of the component (C-iii).

[20] The set for mold molding according to [19] or the sand composition for mold molding according to [19], wherein the content of a reactant obtained by condensing urea, furfuryl alcohol and aldehydes is 25 to 35% by mass and the content of furfuryl alcohol is 65 to 75% by mass, based on the total mass of the component (C-iii).

[21] A molding kit comprising the above-mentioned component (A), component (B) and component (C-iv).

[22] A molding sand composition comprising the above-mentioned component (A), component (B), component (C-iv) and component (D).

[23] The set for mold molding according to [21] or the sand composition for mold molding according to [22], wherein the content of the reactant of urea and aldehyde is 3.5 to 20% by mass and the content of furfuryl alcohol is 80 to 96.5% by mass, based on the total mass of the component (C-iv).

[24] The set for mold molding according to item [23] or the sand composition for mold molding according to item [23], wherein a content of a reactant of urea and aldehyde is 6.9 to 13.5 mass% and a content of furfuryl alcohol is 86.5 to 93.1 mass% with respect to a total mass of the component (C-iv).

[25] A molding kit comprising the above-mentioned components (A), (B) and (C-v).

[26] A molding sand composition comprising the above-mentioned component (A), component (B), component (C-v) and component (D).

[27] The set for mold molding according to [25] or the sand composition for mold molding according to [26], wherein the content of a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde is 7.5 to 22.5% by mass, the content of a reactant of a phenol and an aldehyde is 7.5 to 22.5% by mass, and the content of furfuryl alcohol is 55 to 85% by mass, based on the total mass of the (C-v) component.

[28] The set for mold molding according to [27] or the sand composition for mold molding according to [27], wherein a content of a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde is 12.5 to 17.5% by mass, a content of a reactant of a phenol and an aldehyde is 12.5 to 17.5% by mass, and a content of furfuryl alcohol is 65 to 75% by mass, based on a total mass of the (C-v) component.

[29] A molding kit comprising the above-mentioned components (A), (B) and (C-vi).

[30] A molding sand composition comprising the above-mentioned component (A), component (B), component (C-vi) and component (D).

[31] The set for mold molding according to [29] or the sand composition for mold molding according to [30], wherein the content of the reactant of phenol and aldehyde is 10 to 40% by mass and the content of furfuryl alcohol is 60 to 90% by mass, based on the total mass of the component (C-vi).

[32] The set for mold casting according to [31] or the sand composition for mold casting according to [31], wherein the content of the reactant of phenol and aldehyde is 20 to 30% by mass and the content of furfuryl alcohol is 70 to 80% by mass based on the total mass of the component (C-vi).

[33] A mold molding kit comprising the above-mentioned component (A), component (B), and component (C), wherein the mass ratio of the component (A) to the component (B) (component (A): (B)) is 1: 0.5-1: 10, the mass ratio of the (B) component to the (C) component (the (B) component and the (C) component being 1: 2-1: 10, the mass ratio of the total of the component (A) and the component (B) to the component (C) ({ (A) component + (B) component }/(C) component) is 0.1 to 10.

[34] A molding sand composition comprising the above-mentioned component (A), component (B), component (C), and component (D), wherein the mass ratio of the component (A) to the component (B) (component (A): component (B)) is 1: 0.5-1: 10, the mass ratio of the (B) component to the (C) component (the (B) component and the (C) component being 1: 2-1: 10, the mass ratio of the total of the component (A) and the component (B) to the component (C) ({ (A) component + (B) component }/(C) component) is 0.1 to 10.

[35] The mold making kit according to [33] or the mold making sand composition according to [34], wherein the component (A): (B) the components are 1: 1-1: 3, (B) component: (C) the components are 1: 2.5-1: 5, { (A) component + (B) component }/(C) component is 0.3 to 5.

[36] The set for mold molding according to [35] or the sand composition for mold molding according to [35], wherein the component (A): (B) the components are 1: 1-1: 2, (B) component: (C) the components are 1: 2.5-1: 5, { (A) component + (B) component }/(C) component is 0.5 to 2.

[37] A set for mold casting, comprising the component (A), the component (B), the component (C) and the component (D), wherein the content of the component (A) is 0.05-0.5 parts by mass, the content of the component (B) is 0.045-1.2 parts by mass, and the content of the component (C) is 0.3-2.0 parts by mass, based on 100 parts by mass of the component (D).

[38] A sand composition for casting mold, comprising the component (A), the component (B), the component (C) and the component (D), wherein the component (A) is contained in an amount of 0.05 to 0.5 parts by mass, the component (B) is contained in an amount of 0.045 to 1.2 parts by mass, and the component (C) is contained in an amount of 0.3 to 2.0 parts by mass, based on 100 parts by mass of the component (D).

[39] The set for mold molding according to [37] or the sand composition for mold molding according to [38], wherein the content of the component (A) is 0.1 to 0.3 parts by mass, the content of the component (B) is 0.075 to 0.9 parts by mass, and the content of the component (C) is 0.5 to 1.5 parts by mass, based on 100 parts by mass of the component (D).

[40] A molding kit for a mold, comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-iii) as the component (C).

[41] A molding sand composition comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-iii) as the component (C).

[42] The set for mold molding according to [40] or the sand composition for mold molding according to [41], wherein a content of a reactant obtained by condensing urea, furfuryl alcohol and aldehydes is 15 to 45 mass% and a content of furfuryl alcohol is 55 to 85 mass% with respect to a total mass of the component (C-iii).

[43] The set for mold molding according to [42] or the sand composition for mold molding according to [42], wherein a content of a reactant obtained by condensing urea, furfuryl alcohol and aldehydes is 25 to 35% by mass and a content of furfuryl alcohol is 65 to 75% by mass, based on a total mass of the component (C-iii).

[44] A molding kit for a mold, comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-iv) as the component (C).

[45] A molding sand composition comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-iv) as the component (C).

[46] The set for mold molding according to [44] or the sand composition for mold molding according to [45], wherein the content of the reactant of urea and aldehyde is 3.5 to 20% by mass and the content of furfuryl alcohol is 80 to 96.5% by mass based on the total mass of the component (C-iv).

[47] The set for mold molding according to [46] or the sand composition for mold molding according to [46], wherein the content of the reactant of urea and aldehyde is 6.9 to 13.5 mass% and the content of furfuryl alcohol is 86.5 to 93.1 mass% with respect to the total mass of the component (C-iv).

[48] A molding kit for a mold, comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-v) as the component (C).

[49] A molding sand composition comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-v) as the component (C).

[50] The set for mold molding according to [48] or the sand composition for mold molding according to [49], wherein a content of a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde is 7.5 to 22.5% by mass, a content of a reactant of a phenol and an aldehyde is 7.5 to 22.5% by mass, and a content of furfuryl alcohol is 55 to 85% by mass, based on a total mass of the (C-v) component.

[51] The set for mold molding according to [50] or the sand composition for mold molding according to [50], wherein the content of a reactant obtained by condensing urea, furfuryl alcohol and an aldehyde is 12.5 to 17.5% by mass, the content of a reactant of a phenol and an aldehyde is 12.5 to 17.5% by mass, and the content of furfuryl alcohol is 65 to 75% by mass, based on the total mass of the (C-v) component.

[52] A molding kit for a mold, comprising the component (A), the component (B-i) or (B-ii) as the component (B), and the component (C-vi) as the component (C).

[53] A molding sand composition comprising the component (A), the component (B-i) or the component (B-ii) as the component (B), and the component (C-vi) as the component (C).

[54] The set for mold molding according to [52] or the sand composition for mold molding according to [53], wherein the content of the reactant of phenol and aldehyde is 10 to 40% by mass and the content of furfuryl alcohol is 60 to 90% by mass, based on the total mass of the component (C-vi).

[55] The set for mold molding according to [54] or the sand composition for mold molding according to [54], wherein the content of the reaction product of phenol and aldehyde is 20 to 30% by mass and the content of furfuryl alcohol is 70 to 80% by mass based on the total mass of the component (C-vi).

[56] A mold-making sand composition according to any one of the mold-making kits [40], [42] to [44], [46] to [48], [50] to [52], [54] and [55], or any one of the mold-making sand compositions [41] to [43], [45] to [47], [49] to [51] and [53] to [55], wherein the sand composition contains a component (B-i) as a component (B) and has a sulfuric acid content of 3 to 10 mass% based on the total mass of the component (B-i).

[57] A mold-making sand composition according to any one of the set of [40], [42] to [44], [46] to [48], [50] to [52], [54] and [55], or any one of the set of [41] to [43], [45] to [47], [49] to [51] and [53] to [55], wherein the sand composition contains a component (B-ii) as a component (B), and the component (B-ii) contains at least one of an organic sulfonic acid and a carboxylic acid.

[58] A mold-making sand composition according to any one of the set of [40], [42] to [44], [46] to [48], [50] to [52], [54] and [55], or any one of the set of [41] to [43], [45] to [47], [49] to [51] and [53] to [55], wherein the sand composition contains a component (B-ii) as the component (B), and the component (B-ii) contains an organic sulfonic acid without containing sulfuric acid.

[59] A mold-forming sand composition according to any one of the mold-forming kits of [40], [42] to [44], [46] to [48], [50] to [52] and [54] to [58], or any one of the mold-forming sand compositions of [41] to [43], [45] to [47], [49] to [51] and [53] to [58], wherein the mass ratio of the component (A) to the component (B) (the component (B)) is 1: 0.5-1: 10, the mass ratio of the (B) component to the (C) component (the (B) component and the (C) component being 1: 2-1: 10, the mass ratio of the total of the component (A) and the component (B) to the component (C) ({ (A) component + (B) component }/(C) component) is 0.1 to 10.

[60] The set for mold molding according to [59] or the sand composition for mold molding according to [59], wherein the component (A): (B) the components are 1: 1-1: 3, (B) component: (C) the components are 1: 2.5-1: 5, { (A) component + (B) component }/(C) component is 0.3 to 5.

[61] The set for mold molding according to [60] or the sand composition for mold molding according to [60], wherein the component (A): (B) the components are 1: 1-1: 2, (B) component: (C) the components are 1: 2.5-1: 5, { (A) component + (B) component }/(C) component is 0.5 to 2.

[62] The set for molding a mold according to any one of [40], [42] to [44], [46] to [48], [50] to [52], and [54] to [61], further comprising the component (D), wherein the content of the component (A) is 0.05 to 0.5 parts by mass, the content of the component (B) is 0.045 to 1.2 parts by mass, and the content of the component (C) is 0.3 to 2.0 parts by mass, based on 100 parts by mass of the component (D).

[63] The sand composition for mold making according to any one of [41] to [43], [45] to [47], [49] to [51] and [53] to [61], wherein the content of the component (A) is 0.05 to 0.5 part by mass, the content of the component (B) is 0.045 to 1.2 parts by mass and the content of the component (C) is 0.3 to 2.0 parts by mass, based on 100 parts by mass of the component (D).

[64] The set for mold molding according to [62] or the sand composition for mold molding according to [63], wherein the content of the component (A) is 0.1 to 0.3 parts by mass, the content of the component (B) is 0.075 to 0.9 parts by mass, and the content of the component (C) is 0.5 to 1.5 parts by mass, based on 100 parts by mass of the component (D).

[ examples ] A method for producing a compound

The present invention will be described specifically with reference to the following examples, but the present invention is not limited thereto. The measurement of the physical properties of the test pieces (molds) obtained in the examples and comparative examples was carried out by the following methods.

(measurement of Water content)

The water content was determined by the water content test method of chemicals according to JIS K0068.

(measurement of Nitrogen atom content)

The nitrogen atom content was determined by the titration method of the plant drainage test method of JIS K0102.

(measurement of usable time)

The usable time was determined by JACT test method HM-2.

(measurement of compressive Strength)

The compression strength (mold strength) of the test pieces obtained in each of examples and comparative examples was measured by using a table-top compression tester (made by kukukumi mechanical corporation) based on the test method of the casting sand of JIS Z2601.

(measurement of bulk Density)

The bulk density of the test pieces obtained in the respective examples and comparative examples was determined by the following general formula (1). An electronic balance used for mass measurement was METTLER PM 4000 (product of ltd., japan Siber Hegner & co.).

The bulk density was measured to confirm that a wood pattern was filled with a sand composition having substantially the same mass.

Bulk Density (g/cm) of test pieces³) Mass (g) of specimen/volume (cm) of specimen³)…(1)

[ example 1]

< preparation of Binder >

859.2 parts by mass of furfuryl alcohol, 47.05 parts by mass of urea, 65.9 parts by mass of 92% by mass of paraformaldehyde, and 2.0 parts by mass of a 15% by mass aqueous solution of sodium hydroxide were charged into a 4-neck flask equipped with a thermometer, a cooler, and a stirrer, and a reaction was carried out at 80 ℃ for 1 hour (first addition reaction), then, 3.0 parts by mass of 10% by mass of hydrochloric acid was added, and a reaction was further carried out for 3 hours (condensation reaction), then, 2.0 parts by mass of a 15% by mass aqueous solution of sodium hydroxide and 28.84 parts by mass of urea were added, and a reaction was further carried out for 30 minutes (second addition reaction), thereby obtaining a reaction mixture, and 2 parts by mass of a silane coupling agent (N- β (aminoethyl) γ -aminopropylmethyldimethoxysilane) was added to the obtained reaction mixture, thereby obtaining 1010 parts by mass of a binder.

In 100 mass% of the obtained binder, the content of furfuryl alcohol was 72.0 mass%, the content of a reactant of urea and paraformaldehyde was 13.5 mass%, the content of a condensate of furfuryl alcohol was 9.82 mass%, the content of a silane coupling agent was 0.18 mass%, and the content of water was 4.5 mass%. The nitrogen atom content in 100 mass% of the binder was 3.5 mass%.

< production of Sand composition >

To 100 parts by mass of silica sand (Fremantle new sand, manufactured by mitsubishi corporation) as component (D), 0.3 part by mass of magnesium sulfate (anhydride) was added as component (a), and the mixture was kneaded by a mitaka universal MIXER (MIXER, manufactured by mitaka corporation) to obtain mixture (I) (step (I)).

Next, 0.3 part by mass of a 75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid was added to the obtained mixture (I) as a component (B), and the mixture was kneaded by a pinkish universal mixer to obtain a mixture (II) (step (II)).

Next, 0.8 part by mass of the binder prepared previously was added to the obtained mixture (II) as component (C), and kneaded by a pinkish universal mixer to obtain a sand composition (step (III)).

With respect to the resulting sand composition, the pot life was determined. The results are shown in Table 1.

The above procedure is referred to as "procedure (1)".

< production of test piece >

A part of the obtained sand composition was immediately filled into a wooden mold for test piece production having a cylindrical mold with an inner diameter of 50mm and a height of 50mm under conditions of a temperature of 15 ℃ and a humidity of 55% to cure the composition, and the test piece was taken out after 90 minutes had elapsed from the start of curing (demolding time 90 minutes).

With respect to the obtained test pieces, the compressive strength and the bulk density after the elapse of 90 minutes, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

[ example 2]

A sand composition was produced in the same manner as in example 1 except that 0.3 part by mass of ammonium sulfate was used as the component (a), and test pieces were produced using the obtained sand composition, and various measurements were performed. The results are shown in Table 1.

[ example 3]

A sand composition was produced in the same manner as in example 1 except that the amount of magnesium sulfate (anhydride) added was changed to 0.1 part by mass, and test pieces were produced using the obtained sand composition, and various measurements were performed. The results are shown in Table 1.

[ example 4]

A sand composition was produced in the same manner as in example 1 except that the amount of magnesium sulfate (anhydride) added was changed to 0.5 parts by mass, and test pieces were produced using the obtained sand composition, and various measurements were performed. The results are shown in Table 1.

[ example 5]

A sand composition was produced in the same manner as in example 1 except that the amount of magnesium sulfate (anhydride) added was changed to 0.4 parts by mass, and 0.3 parts by mass of a 67% strength by mass aqueous solution containing 67% by mass of xylene sulfonic acid was used as the component (B), and various measurements were performed on test pieces produced using the obtained sand composition. The results are shown in Table 1.

[ example 6]

< production of Sand composition >

To 100 parts by mass of silica sand (Fremantle new sand, manufactured by mitsubishi corporation) as component (D), 0.3 part by mass of a 75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid was added as component (B), and the mixture was kneaded by a cottawa universal mixer to obtain mixture (IV) (step (IV)).

Next, 0.8 parts by mass of the binder prepared in the same manner as in example 1 was added to the obtained mixture (IV) as the component (C), and the mixture was kneaded by a "pinkish" universal mixer to obtain a mixture (V) (step (V)).

Next, 0.3 parts by mass of magnesium sulfate (anhydride) was added to the obtained mixture (V) as the component (a), and the mixture was kneaded by a "pinkish" universal mixer to obtain a sand composition (step (VI)).

The above procedure is referred to as "procedure (2)".

< production of test piece >

Test pieces were produced in the same manner as in example 1 except that the obtained sand composition was used, and various measurements were performed. The results are shown in Table 1.

Comparative example 1

A sand composition was produced in the same manner as in example 1 except that the component (a) was not used, and a test piece was produced using the obtained sand composition, and various measurements were performed. The results are shown in Table 2.

Comparative example 2

A sand composition was produced in the same manner as in example 1 except that 0.3 part by mass of a 66 mass% aqueous solution containing 24 mass% of xylene sulfonic acid and 42 mass% of sulfuric acid was used as the component (B), and the resulting sand composition was used to produce test pieces, and various measurements were performed. The results are shown in Table 2.

Comparative examples 3 to 7

A sand composition was produced in the same manner as in example 1 except that 0.3 part by mass of another sulfate (anhydride) of the type shown in table 2 was used instead of the component (a), and test pieces were produced using the obtained sand composition, and various measurements were performed. The results are shown in Table 2.

[ TABLE 1]

[ TABLE 2]

The abbreviations in tables 1 and 2 are as follows.

Acid curing agent (1): an aqueous solution having a concentration of 75% by mass containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid.

Acid curing agent (2): an aqueous solution having a concentration of 67% by mass of xylene sulfonic acid was contained.

Acid curing agent (3): an aqueous solution having a concentration of 66% by mass and containing 24% by mass of xylene sulfonic acid and 42% by mass of sulfuric acid.

From the results shown in tables 1 and 2, when examples 1 to 6 were compared with comparative example 1, the compression strength (initial strength) after 90 minutes and the compression strength after 3 hours of the test pieces (molds) of examples 1 to 6 using magnesium sulfate or ammonium sulfate as the component (a) were much higher than the mold of comparative example 1 not using the component (a). From the above results, it can be said that the effect of improving the curability of the component (C) is obtained in examples 1 to 6.

In addition, when examples 1, 3 and 4 are compared, the compression strength (initial strength) after 90 minutes and the compression strength after 3 hours of the mold tend to be increased as the amount of magnesium sulfate is increased.

In addition, when example 1 and example 5 were compared, the same degree of compressive strength as that of example 1 was obtained even in the mold of example 5 in which the acid curing agent (2) containing no sulfuric acid was used.

In addition, when example 1 and example 6 were compared, the same degree of compressive strength as that of example 1 was obtained even in the mold of example 6 produced in step (2).

On the other hand, the mold of comparative example 2, which used the acid curing agent (3) having a high sulfuric acid concentration without using the component (a), had improved curability and shortened pot life as compared with comparative example 1, but the strength of the mold was lower than those of the molds of examples 1 and 2. In addition, in the case of comparative example 2, the sulfuric acid concentration in the acid curing agent was high at 42 mass%, which may specify a harmful substance for medical use and may lower workability.

When example 1 and comparative examples 3 to 7 were compared, the compression strength (initial strength) after 90 minutes and the compression strength after 3 hours of the casting mold of comparative examples 3 to 7 using another sulfate instead of the component (a) were lower than those of the casting mold of example 1, and the effect of improving the curability of the component (C) was not obtained.

[ Industrial Applicability ]

By using the mold making jacket or the mold making sand composition of the present invention, a mold having a sufficient curing rate and high strength can be produced even if the amount of sulfuric acid used is reduced.

Claims

1. A set for mold making, comprising the following components (A), (B) and (C):

(A) the components: magnesium sulfate;

(B) the components: an acid curing agent having a sulfuric acid content of 10 mass% or less with respect to the total mass of the component (B);

(C) the components: a binder comprising furfuryl alcohol.

2. The mold molding set according to claim 1,

also comprises the following (D) components:

(D) the components: a refractory particulate material.

3. The mold molding set according to claim 1 or 2,

the component (B) comprises sulfuric acid.

4. The mold molding set according to claim 1 or 2,

the component (C) further contains at least one selected from the following components (C1), (C2) and (C3), and the components (C1) to (C3) are as follows:

(C1) the components: at least one compound selected from phenols and urea;

(C3) the components: a condensate of furfuryl alcohol.

5. The mold molding set according to claim 3,

(C1) the components: at least one compound selected from phenols and urea;

(C3) the components: a condensate of furfuryl alcohol.

6. A sand composition for mold making, which is a mixture of the following components (A), (B), (C) and (D), wherein the components (A) to (D) are as follows:

(A) the components: magnesium sulfate;

(C) the components: a binder comprising furfuryl alcohol;

(D) the components: a refractory particulate material.

7. The sand composition for molding mold according to claim 6,

the component (B) comprises sulfuric acid.

8. The sand composition for molding mold according to claim 6 or 7,

(C1) the components: at least one compound selected from phenols and urea;

(C3) the components: a condensate of furfuryl alcohol.

9. A method for producing the sand composition for mold making according to claim 6 or 7, wherein,

the method for producing a sand composition for mold making comprises a step (I) of mixing the component (D) with the component (A), a step (II) of mixing the mixture (I) obtained in the step (I) with the component (B), and a step (III) of mixing the mixture (II) obtained in the step (II) with the component (C).

10. A method for producing the sand composition for mold making according to claim 8, wherein,

11. A method for producing the sand composition for mold making according to claim 6 or 7, wherein,

the method for producing a sand composition for mold making comprises a step (IV) of mixing the component (D) with the component (B), a step (V) of mixing the mixture (IV) obtained in the step (IV) with the component (C), and a step (VI) of mixing the mixture (V) obtained in the step (V) with the component (A).

12. A method for producing the sand composition for mold making according to claim 8, wherein,