JP2020082128A - Binder composition, sand composition, manufacturing method of casting mold - Google Patents

Abstract

To provide a binder composition capable of reducing S addition amount to refractory granular material while keeping a usable life, viscosity, and mold strength in a practical range, and to provide a sand composition and a manufacturing method of a casting mold.SOLUTION: A binder composition curing by an acid catalyst containing S-containing acid is used. The binder composition contains a following (A) component and a following (B) component, has mass ratio (A:B) of the following (A) component to the following (B) component of 100:0.5 to 100:45, and has content of the following (B) component with respect to gross mass of solid content of the binder composition of 0.5 to 30 mass%, where the (A) component is furfuryl alcohol or Furan resin and the (B) component is novolak type phenolic resin.SELECTED DRAWING: None

Description

The present invention relates to a binder composition, a sand composition and a method for producing a mold.

Conventionally, a self-hardening mold is known as one of casting molds (hereinafter, also simply referred to as “mold”). A self-hardening mold is a refractory granular material such as silica sand, a binder containing a furan resin as a main component (acid-curable binder), and an acid catalyst (curing agent) such as sulfuric acid or xylene sulfonic acid. After adding and kneading, the obtained sand composition (kneading sand) was filled in a wooden mold, a resin mold, a mold or the like (hereinafter, these are also collectively referred to as a “mold for mold making”) and the mixture was viscous. It is manufactured by a method of curing a binder.

An acid-curable binder is a binder that undergoes polycondensation while dehydrating with an acid catalyst and cures. If the work life is too short, the acid-curable binder will be acid-curable before being filled into the mold for molding the sand composition The binder may harden. Therefore, the pot life is required so that the time for filling the sand composition into the casting mold can be secured. On the other hand, after the sand composition has been filled in the mold for molding, it is preferable that the acid-curable binder is cured quickly from the viewpoint of productivity, and the mold removal time is preferably shorter.

As a method for accelerating the curing speed of the binder, the amount of sulfur atom added to the refractory granular material can be increased by increasing the amount of acid catalyst added or by using an acid catalyst with a high sulfur atom content (S content). (Amount of S added), that is, a method of increasing the S content in the sand composition, a method of blending a hardening accelerator such as resorcin with a binder, and the like are known.
Increasing the S content in the sand composition will increase the S content in the resulting mold. As a result, the amount of sulfur oxide (SOx) such as sulfurous acid gas generated when pouring into the mold increases, which may deteriorate the working environment.

Therefore, in order to increase the curing rate of the binder without increasing the S content in the sand composition, a method of adding a curing accelerator to the binder is effective.
For example, Patent Document 1 discloses a binder composition containing a furan resin, at least one of resorcin and a resorcin-based resin, and calcium hydroxide.

Patent No. 5581114

Since a binder using a furan resin and resorcin in combination has a high curing speed, a practical working life can be obtained by using an acid catalyst having a low S content. Moreover, since an acid catalyst having a low S content is used, the amount of sulfur oxide generated during pouring into the mold can be reduced. In addition, since the binder using the furan resin and resorcin together can maintain an appropriate viscosity, it is easy to knead with the refractory granular material and the acid catalyst. Furthermore, if a binder containing a furan resin and resorcin is used in combination, a mold having high strength can be obtained.
However, in recent years, with the withdrawal of resorcinol manufacturers, there is concern about stable supply. Moreover, the price of resorcin has risen.
Therefore, there is a demand for an alternative binder while maintaining the same performance as a binder using a furan resin and resorcin in combination.

The present invention has been made in view of the above circumstances, and a binder composition and a sand composition capable of reducing the amount of S added to a refractory granular material while keeping the pot life, viscosity, and mold strength in practical ranges. And it aims at providing the manufacturing method of a mold.

The present invention has the following aspects.
[1] A binder composition which is cured with an acid catalyst containing an S-containing acid,
Contains the following component (A) and the following component (B),
The mass ratio (A:B) of the following component (A) and the following component (B) is 100:0.5 to 100:45,
The binder composition in which the content of the following component (B) is 0.5 to 30 mass% with respect to the total mass of the solid content of the binder composition.
Component (A): Furfuryl alcohol or furan resin (B) Component: Novolac type phenol resin [2] The binder composition of [1], wherein the component (B) has a mass average molecular weight of 200 to 8000.
[3] In [1] or [2], the content of the raw material monomer remaining in the component (B) is less than 0.1% by mass based on the total mass of the solid content of the component (B). Binder composition.
[4] The binder composition according to any one of [1] to [3], wherein the content of the component (A) is 70 to 99.5 mass% with respect to the total mass of the solid content of the binder composition. object.
[5] Any of [1] to [4], wherein the total content of the component (A) and the component (B) is 97% by mass or more based on the total mass of the solid content of the binder composition. Binder composition.
[6] The binder composition according to any one of [1] to [5], which further contains the following component (C).
(C) component: silane coupling agent [7] A sand composition containing the binder composition of any one of [1] to [6], a refractory granular material, and an acid catalyst containing an S-containing acid. object.
[8] The sand composition according to [7], wherein the content of the binder composition is 0.1 to 3 parts by mass in terms of solid content based on 100 parts by mass of the refractory granular material.
[9] A method for producing a mold, in which the sand composition of [7] or [8] is filled in a mold for molding, and the binder composition contained in the sand composition is cured.

According to the present invention, there are provided a binder composition, a sand composition and a method for producing a mold, which can reduce the amount of S added to the refractory granular material while keeping the pot life, the viscosity and the mold strength in the practical ranges. it can.

In the following specification, the “mold” means a product produced by using the binder composition of the present invention. Further, the “solid content” refers to a nonvolatile content at 100° C.

[Binder composition]
The binder composition of the present invention is a binder that is cured with an acid catalyst containing an S-containing acid and contains the following (A) component and (B) component. The binder composition preferably further contains the component (C) shown below. Further, the binder composition may contain components (other components) other than the component (A), the component (B) and the component (C).
(A) component: furfuryl alcohol or furan resin (B) component: novolac type phenol resin (C) component: silane coupling agent

<(A) component>
The component (A) is furfuryl alcohol or furan resin.
The furan resin is a resin whose main raw material is furfuryl alcohol, urea, formaldehyde, etc., and is polycondensed and cured while dehydrating with an acid catalyst.
As the furan resin, one or more condensates or co-condensates of furfuryl alcohol or furfuryl alcohol and either urea and aldehydes, and a mixture of furfuryl alcohol as a main component, are used as necessary. It is preferable to use one containing at least one of phenols and bisphenols.

Examples of phenols include phenol, cresol, resorcin, nonylphenol, cashew nut shell liquid (CNSL) and the like. These phenols may be used alone or in combination of two or more.
Examples of bisphenols include bisphenol A, bisphenol F, bisphenol C, bisphenol S, bisphenol E, and bisphenol Z. These bisphenols may be used alone or in combination of two or more.

Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, furfural, glyoxal, glutardialdehyde, phthalic dialdehyde and the like. These aldehydes may be used alone or in combination of two or more. However, depending on the type of condensate, acid curing may not proceed when glyoxal or furfural is used alone as the aldehyde. In such a case, at least formaldehyde may be used as the aldehyde.

When a condensate or a cocondensate of furfuryl alcohol and an aldehyde is produced, it is preferable to use 0.1 to 1 mol of the aldehyde with respect to 1 mol of the furfuryl alcohol. When the amount of the aldehydes used is at least the above lower limit, a condensate having a low degree of polymerization is obtained, so that the pot life is set more easily. On the other hand, when the amount of the aldehydes used is not more than the above upper limit value, a condensate having a high degree of polymerization is obtained, so that the final template strength is further improved.

When producing a condensate or co-condensate of urea and aldehydes, it is preferable to use 1 to 3 moles of aldehydes, and more preferably 1.3 to 2.5 moles per 1 mole of urea. And more preferably 1.5 to 2 mol.

The nitrogen atom content derived from urea or the like is preferably in the range of 0.1 to 6% by mass, and is 0.1 to 4.5% by mass, based on the total mass of the furan resin. Is more preferable.
The nitrogen atom content affects the initial strength and final strength of the template, and when the nitrogen atom content is low, the initial strength of the template tends to be high, and when the nitrogen atom content is high, the template is The final strength of the product tends to increase.
Therefore, it is preferable to appropriately adjust the nitrogen atom content as necessary, and if the nitrogen atom content is within the above range, it is possible to obtain a template in which both the initial strength and the final strength are preferable.

The following two are particularly preferable embodiments of the furan resin. The (co)condensate below means at least one of a condensate and a cocondensate.
i) A mixture of (co)condensate (a) obtained by condensing urea, furfuryl alcohol and aldehydes, furfuryl alcohol and optionally at least one of phenols and bisphenols.
ii) A mixture of a condensation product of urea and an aldehyde, furfuryl alcohol, and optionally at least one of phenols and bisphenols.

When the furan resin has such a mode as i) to ii), the pot life can be set more easily and the mold strength can be further improved. Among these, the aspect of i) is preferable from the viewpoint of easy production.
In the aspect of i), the ratio of the (co)condensate (a) in the furan resin is preferably 5 to 90% by mass, and more preferably 10 to 80% by mass. The ratio of furfuryl alcohol is preferably 10 to 95% by mass, more preferably 20 to 90% by mass.
In the aspect of ii), the ratio of the condensation product of urea and aldehydes in the furan resin is preferably 3 to 30% by mass, and more preferably 5 to 20% by mass. The ratio of furfuryl alcohol is preferably 70 to 97% by mass, and more preferably 80 to 95% by mass.
In the embodiments i) to ii), the ratio of at least one of the phenols and the bisphenols in the furan resin is preferably 40% by mass or less, and more preferably 1 to 30% by mass.

In addition to the above, as the furan resin, for example, a mixture of furfuryl alcohol and one or more kinds selected from the group consisting of 2,5-bis(hydroxymethyl)furan, phenols and bisphenols; urea and aldehyde. It is also possible to use a mixture of a condensate with a similar compound, furfuryl alcohol, and 2,5-bis(hydroxymethyl)furan.

The furan resin can be obtained by a general production method. An example is shown below.
First, a part of the furan resin raw material (furfuryl alcohol, aldehydes, urea, etc.) is mixed with an aqueous sodium hydroxide solution to make it alkaline, and the temperature is raised to form an adduct with aldehydes. Next, acidify the reaction solution using hydrochloric acid, etc., and proceed the reaction such as condensation of furfuryl alcohol, urea and aldehydes, etc., and then make the reaction solution alkaline again, and the remaining furan resin raw material and necessary Accordingly, a silane coupling agent is mixed to obtain a mixture containing a furan resin, water, and optionally a silane coupling agent.
The amount of hydrochloric acid added here is too small to proceed to the curing reaction. Further, the unreacted furfuryl alcohol plays a role of a diluent for reducing the viscosity of the furan resin as a whole, and in the curing reaction, it is resinified as a component constituting the cured product to be a cured product.

The content of the component (A) is preferably 70 to 99.5 mass%, more preferably 75 to 99 mass%, and further preferably 80 to 95 mass% with respect to the total mass of the solid content of the binder composition. .. When the content of the component (A) is at least the above lower limit, it is possible to suppress an increase in the viscosity of the binder composition. In addition, the strength of the mold is improved. When the content of the component (A) is at most the above upper limit value, the content of the component (B) in the binder composition can be secured, and the curing speed of the binder composition is increased.

<(B) component>
The component (B) is a novolac type phenol resin.
The component (B) is obtained by reacting raw material monomers in the presence of an acid catalyst (hereinafter, also referred to as “acid catalyst for resin production”), specifically, at least one of phenols and bisphenols. It is obtained by reacting with aldehydes and is usually a solid.

Examples of the phenols include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 3,5-xylenol, m-ethylphenol, m-propylphenol, m-butylphenol, p-butylphenol, o-Butylphenol, resorcinol, hydroquinone, catechol, 3-methoxyphenol, 4-methoxyphenol, 3-methylcatechol, 4-methylcatechol, methylhydroquinone, 2-methylresorcinol, 2,3-dimethylhydroquinone, 2,5-dimethyl Resorcinol, 2-ethoxyphenol, 4-ethoxyphenol, 4-ethylresorcinol, 3-ethoxy-4-methoxyphenol, 2-propenylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 3,4. 5-trimethylphenol, 2-isopropoxyphenol, 4-pyroxyphenol, 2-allylphenol, 3,4,5-trimethoxyphenol, 4-isopropyl-3-methylphenol, pyrogallol, phloroglicinol, 1,2. , 4-benzenetriol, 5-isopropyl-3-methylphenol, 4-butoxyphenol, 4-t-butylcatechol, t-butylhydroquinone, 4-t-pentylphenol, 2-t-butyl-5-methylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3-phenoxyphenol, 4-phenoxyphenol, 4-hexyloxyphenol, 4-hexanoylresorcinol, 3,5-diisopropylcatechol, 4-hexylresorcinol, 4-heptyloxyphenol, 3,5-di-t-butylphenol, 3,5-di-t-butylcatechol, 2,5-di-t-butylhydroquinone, di-sec-butylphenol, 4-cumylphenol, Nonylphenol, 2-cyclopentylphenol, 4-cyclopentylphenol and the like can be mentioned. These phenols may be used alone or in combination of two or more.
Examples of the bisphenols include bisphenol A, bisphenol F, bisphenol C, bisphenol S, bisphenol E, and bisphenol Z. These bisphenols may be used alone or in combination of two or more.

Examples of the aldehydes include formaldehyde, trioxane, furfural, paraformaldehyde, benzaldehyde, methyl hemiformal, ethyl hemiformal, propyl hemiformal, salicylaldehyde, butyl hemiformal, phenyl hemiformal, acetaldehyde, propylaldehyde, phenylacetaldehyde, α-. Phenylpropyl aldehyde, β-phenylpropyl aldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, o-chlorobenzaldehyde, o-nitrobenzaldehyde, m-nitrobenzaldehyde, p-nitrobenzaldehyde, o-methylbenzaldehyde, Examples thereof include m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde and the like. These aldehydes may be used alone or in combination of two or more.

Examples of the acid catalyst for resin production include hydrochloric acid, sulfuric acid, phosphoric acid, sulfonic acid, carboxylic acid, and salts with a metal such as zinc chloride or zinc acetate.
Examples of the sulfonic acid include paratoluene sulfonic acid, xylene sulfonic acid, benzene sulfonic acid and methane sulfonic acid.
Examples of the carboxylic acid include lactic acid, citric acid, malic acid, tartaric acid, malonic acid, succinic acid, maleic acid, oxalic acid, acetic acid and benzoic acid.
These acid catalysts for resin production may be used alone or in combination of two or more.

The mass average molecular weight of the component (B) is preferably 200 to 8000, more preferably 200 to 6500, further preferably 200 to 4000, particularly preferably 200 to 3000, and most preferably 200 to 2000. When the mass average molecular weight of the component (B) is at least the above lower limit value, the curing speed of the binder composition will be faster, and by using an acid catalyst with a lower S content, a practical working life will be obtained. Be done. Moreover, since the acid catalyst having a lower S content is used, the amount of S added to the refractory granular material (that is, the S content in the sand composition) can be further reduced. The larger the mass average molecular weight of the component (B), the faster the curing rate, and as a result, the amount of S added to the refractory granular material tends to be reduced, but the mass average molecular weight of the component (B) increases. Along with this, the viscosity of the binder composition tends to increase. Considering the balance between the reduction of the amount of S added and the viscosity of the binder composition, the mass average molecular weight of the component (B) is preferably 8,000 or less.
The mass average molecular weight of the component (B) can be measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

The reaction of at least one of the phenols and the bisphenols with the aldehyde can be performed by a known method. For example, a method may be mentioned in which at least one of phenols and bisphenols, aldehydes, an acid catalyst for resin production, water and the like are charged into a reaction vessel and an arbitrary reaction temperature is maintained for an arbitrary reaction time. After completion of the reaction, the reaction solution is neutralized if necessary, and the reaction solution is concentrated under reduced pressure to remove water to obtain the component (B). A silane coupling agent may be added before or after neutralization of the reaction solution, if necessary. In this case, a mixture containing the component (B) and the silane coupling agent is obtained.
Examples of the silane coupling agent include N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-glycidoxy. Examples include propyltrimethoxysilane and the like.

The content of the raw material monomer remaining in the component (B) is preferably less than 0.1% by mass, more preferably 0.05% by mass or less, based on the total mass of the component (B). When the content of the raw material monomer remaining in the component (B) is less than the above upper limit value, skin irritation to an operator can be reduced when molding a mold.
The content of the raw material monomer remaining in the component (B) is preferably as small as possible, and 0% by mass is particularly preferable.

The content of the component (B) is 0.5 to 30% by mass, preferably 1 to 25% by mass, and more preferably 5 to 20% by mass, based on the total mass of the solid content of the binder composition. When the content of the component (B) is at least the above lower limit value, the curing speed of the binder composition is increased, and a practical pot life is obtained by using an acid catalyst having a low S content. Moreover, since the acid catalyst having a low S content is used, the amount of S added to the refractory granular material can be reduced. When the content of the component (B) is at most the above upper limit value, increase in viscosity of the binder composition can be suppressed. In addition, the strength of the mold is improved.

The mass ratio (A:B) of the component (A) and the component (B) is 100:0.5 to 100:45, preferably 100:1 to 100:30, and 100:5 to 100:25. More preferable. The higher the ratio of the component (B) to the component (A), the faster the curing rate of the binder composition, and the use of an acid catalyst having a low S content, and the amount of S added to the refractory granular material. Can be reduced. The smaller the ratio of the component (B) to the component (A), the more the increase in the viscosity of the binder composition can be suppressed. In addition, the strength of the mold is improved.

The total content of the components (A) and (B) is preferably 97% by mass or more, and more preferably 98% by mass or more, based on the total mass of the solid content of the binder composition. When the total content of the components (A) and (B) is at least the above lower limit value, the strength of the mold can be maintained well. The total content of the components (A) and (B) may be 100% by mass based on the total mass of the solid content of the binder composition.

<(C) component>
The component (C) is a silane coupling agent.
Examples of the silane coupling agent include N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-glycidoxy. Examples include propyltrimethoxysilane and the like.

As described above, a silane coupling agent may be used when the component (A) or the component (B) is produced. In that case, the component (A) or the component (B) is a silane coupling agent. It is obtained as a mixture with.
The component (C) may be the one used during the production of the component (A) or the component (B), or may be added later during the production of the binder composition. Further, it may be added at the time of producing the sand composition, or the refractory granular material may be previously coated or mixed with the component (C).

The content of the component (C) is preferably 0.01 to 3% by mass, and more preferably 0.1 to 2% by mass based on the total mass of the solid content of the binder composition. When the content of the component (C) is at least the above lower limit, the effect of improving the strength of the mold can be sufficiently obtained. The effect of improving the strength of the mold tends to be more easily obtained as the content of the component (C) increases, but if the amount is too large, the effect only reaches the ceiling. Therefore, the content of the component (C) is preferably 3% by mass or less.

<Other ingredients>
The binder composition contains components (other components) other than the component (A), the component (B) and the component (C), if necessary, as long as the effects of the present invention are not impaired. May be.
Examples of other components contained in the binder composition include resins (other resins) other than the components (A) and (B), water, and the like.
Examples of other resins include resol type phenol resins, melamine resins, urea resins and the like.

The content of water is preferably 1 to 25% by mass, more preferably 1 to 15% by mass, based on the total mass of the binder composition. The closer the water content is to the above lower limit, the more improved the strength of the mold.
Water may be used or water may be produced when producing the components (A) and (B). In that case, the components (A) and (B) are mixed with water. Obtained as.
The water contained in the binder composition may be used or produced during the production of the component (A) or the component (B), or may be added afterwards during the production of the binder composition. ..

<Manufacturing method>
The binder composition can be obtained by mixing the component (A) and the component (B) and, if necessary, one or more of the component (C) and the other component.

10-300 mPa*s is preferable and, as for the viscosity of a binder composition, 15-200 mPa*s is more preferable.
The viscosity of the binder composition is a value measured by an E-type viscometer at 25°C.

<Effect>
Since the binder composition of the present invention described above contains the component (A) and the component (B) in a specific mass ratio and the content of the component (B) is specified, the curing rate is fast. Therefore, by using an acid catalyst having a low S content, a practical pot life can be obtained. Moreover, since an acid catalyst having a low S content is used, the amount of S added to the refractory granular material can be reduced, and the amount of sulfur oxide generated during pouring into the mold can also be reduced. In addition, since the binder composition of the present invention can maintain an appropriate viscosity, it can be easily kneaded with a refractory granular material or an acid catalyst. Furthermore, a mold having high strength can be obtained by using the binder composition of the present invention. Further, the component (B) is available at a lower price than resorcin and can be stably supplied.
As described above, according to the binder composition of the present invention, it is possible to reduce the amount of S added to the refractory granular material while keeping the pot life, the viscosity and the mold strength in the practical ranges, and to reduce the addition amount of the conventional furan resin. While maintaining the performance equivalent to that of a binder using resorcin in combination, the manufacturing cost of the binder composition and the mold can be reduced, and stable supply is possible.

[Sand composition]
The sand composition of the present invention comprises the above-described binder composition of the present invention, a refractory granular material, and an acid catalyst containing an S-containing acid.
The sand composition may contain components (other components) other than the binder composition, the refractory granular material and the acid catalyst.

<Fireproof granular material>
As the refractory granular material, natural sand such as silica sand, chromite sand, zircon sand, olivine sand, amorphous silica, alumina sand and mullite sand; conventionally known materials such as artificial sand can be used. Further, it is also possible to use a product obtained by collecting used refractory granular material (recovered sand) or a product subjected to a recycling treatment (reclaimed sand). These refractory granular materials may be used alone or in combination of two or more.
From the viewpoint of production cost, natural sand is preferable, and silica sand is more preferable. Artificial sand is preferable from the viewpoint of being less likely to expand by heat. Natural sand and artificial sand may be mixed and used in consideration of the balance between production cost and heat resistance.

The average particle size of the refractory granular material is preferably 50 to 600 μm, more preferably 100 to 550 μm, and further preferably 200 to 500 μm. When the average particle diameter of the refractory granular material is at least the above lower limit, a mold having high strength can be obtained. When the average particle diameter of the refractory granular material is equal to or less than the above upper limit value, the surface property of the casting cast using the mold is also excellent.
The average particle diameter of the refractory granular material is the median diameter of the cumulative volume of 50% of the refractory granular material measured by the dynamic light scattering method.

<Binder composition>
The binder composition contained in the sand composition is the binder composition of the present invention described above, and the description thereof is omitted.
The content of the binder composition is, in terms of solid content, preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2 parts by mass, relative to 100 parts by mass of the refractory granular material. When the content of the binder composition is at least the above lower limit value, a mold having higher strength can be easily obtained. The effect of improving the strength of the mold tends to be obtained more easily as the content of the binder composition increases, but as the content of the binder composition increases, the binder composition of the binder composition during pouring is increased. The amount of gas generated by thermal decomposition also tends to increase. Considering the balance between the improvement of the strength of the mold and the reduction of gas generation during pouring, the content of the binder composition is preferably 2 parts by mass or less.

<Acid catalyst>
The acid catalyst is a catalyst that cures the binder composition when producing the mold.
The acid catalyst contains at least an S-containing acid. The acid catalyst may contain an acid (other acid) other than the S-containing acid.

The S-containing acid is an acid containing a sulfur atom in the molecule.
Examples of the S-containing acid include inorganic acids such as sulfuric acid; organic acids such as organic sulfonic acid.
Organic sulfonic acid is an organic compound in which a sulfo group is substituted on the carbon skeleton. Examples of the organic sulfonic acid include paratoluene sulfonic acid, xylene sulfonic acid, benzene sulfonic acid and methane sulfonic acid. Among these, xylene sulfonic acid is preferable because of its excellent performance as a curing agent. These organic sulfonic acids may be used alone or in combination of two or more.
As the S-containing acid, it is preferable to use a combination of sulfuric acid and organic sulfonic acid from the viewpoint of excellent curing speed and mold strength.

The other acid is an acid other than the S-containing acid, that is, an acid containing no sulfur atom in the molecule.
Examples of the other acid include inorganic acids such as phosphoric acid and hydrochloric acid; organic acids such as carboxylic acid.
Examples of the carboxylic acid include lactic acid, citric acid, malic acid, tartaric acid, malonic acid, succinic acid, maleic acid, oxalic acid, acetic acid and benzoic acid. These carboxylic acids may be used alone or in combination of two or more.

5 mass% or more is preferable with respect to the total mass of an acid catalyst, and, as for content of S containing acid, 10 mass% or more is more preferable. When the content of the S-containing acid is at least the above lower limit, the strength of the mold will be further improved. The content of the S-containing acid may be 100% by mass based on the total mass of the acid catalyst.
When the acid catalyst contains another acid, the content of the S-containing acid is preferably 90% by mass or less, and more preferably 80% by mass or less, based on the total mass of the acid catalyst.

The content of the other acid is preferably 10 to 95 mass% and more preferably 20 to 90 mass% with respect to the total mass of the acid catalyst. When the content of the other acid is at least the above lower limit value, the S content in the acid catalyst and the sand composition can be further reduced. When the content of the other acid is not more than the above upper limit value, the strength of the mold is further improved.

The content of the acid catalyst is preferably 0.01 to 3 parts by mass, and more preferably 0.02 to 2 parts by mass with respect to 100 parts by mass of the refractory granular material. When the content of the acid catalyst is at least the above lower limit, the binder composition can be sufficiently cured. When the content of the acid catalyst is not more than the above upper limit value, the S content in the sand composition can be further reduced.

<Other ingredients>
The sand composition may contain components (other components) other than the binder composition, the refractory granular material, and the acid catalyst, if necessary, as long as the effects of the present invention are not impaired. ..
Examples of other components contained in the sand composition include silane coupling agents, antiblocking agents, water, and solvents other than water (other solvents).
Examples of the silane coupling agent include the component (C) exemplified above in the description of the binder composition.
Examples of the anti-blocking agent include zeolite; metal salts capable of hydration such as magnesium sulfate, sodium sulfate and ammonium sulfate.
Examples of the other solvent include alcohols such as methanol, ethanol, 1-propanol, and 2propanol.

<Manufacturing method>
The sand composition is obtained by mixing the binder composition, the refractory granular material and the acid catalyst, and optionally other components.
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.

As the acid catalyst, the above-mentioned acids may be used alone or in combination with several kinds of acids, but a solvent may be used here and the solution may be used, that is, the acid catalyst solution may be used.
The content of the acid catalyst with respect to the total mass of the solution of the acid catalyst is preferably 10 to 100% by mass, and more preferably 15 to 100% by mass.
The content of the solvent with respect to the total mass of the solution of the acid catalyst is preferably 0 to 90% by mass, and more preferably 0 to 85% by mass.
Examples of the solvent used for the solution of the acid catalyst include water, alcohol, and a mixture thereof. Examples of the alcohol include the alcohols exemplified above in the description of the optional components contained in the sand composition. When the acid catalyst is a liquid at room temperature (25° C.), it may be diluted with the above solvent before use.

<Effect>
Since the sand composition of the present invention described above contains the binder composition of the present invention described above, the amount of S added to the refractory granular material is within the practical range of the pot life and the mold strength. Has been reduced.
Further, by using the sand composition of the present invention, a mold having a reduced S content can be obtained, so that the amount of sulfur oxide generated during pouring into the mold can be reduced.

[Mold manufacturing method]
The mold is produced by using the above-described sand composition of the present invention, filling the sand composition in a mold for molding, and curing the sand composition.
As a method for producing a mold, a self-hardening mold making method can be adopted. That is, when the sand composition is filled in the mold for molding, the binder composition in the sand composition is cured by the action of the acid catalyst. As a result, a mold can be obtained.

<Effect>
According to the mold manufacturing method of the present invention described above, since the sand composition of the present invention is used, it is possible to manufacture a mold having practical strength and having a reduced S content.
Further, since the S content of the mold obtained by the present invention is reduced, the amount of sulfur oxide generated during pouring into the mold can be reduced.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The component (A), the component (B) and their comparative products (component (B')), the component (C), the refractory granular material and the acid catalyst used in each example are shown below. Further, various measuring methods and evaluation methods are as follows.

<(A) component>
The component (A) of the aspect i) was prepared as follows.
In a four-necked flask equipped with a thermometer, a condenser and a stirrer, 827.1 parts by mass of furfuryl alcohol, 24.18 parts by mass of urea, 33.9 parts by mass of 92% by mass paraformaldehyde, and 15% by mass. 2.0 parts by mass of an aqueous sodium hydroxide solution was added, and the mixture was reacted at 80° C. for 1 hour (first addition reaction). Thereafter, 3.0 parts by mass of 10% by mass hydrochloric acid was added, and the reaction was further continued for 3 hours (condensation reaction). Then, 2.0 mass parts of 15 mass% sodium hydroxide aqueous solution and 14.82 mass parts of urea were added, and it was made to react for further 30 minutes (2nd addition reaction), and the reaction mixture was obtained. 1.8 parts by mass of a silane coupling agent (N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane) was added to the obtained reaction mixture, and the component (A), the silane coupling agent and water were included. 908.8 parts by mass of the mixture (α) was obtained.
The content of the component (A) with respect to the total mass of the mixture (α) was 88.2% by mass, the content of the silane coupling agent was 0.2% by mass, and the content of water was 11.6% by mass. Is. The nitrogen atom content was 2.3 mass% with respect to the total mass of the component (A).

<(B) component>
The components shown below were used as the component (B).
-Novolak type phenol resin (i): trade name "BPF-SG" manufactured by Gunei Chemical Industry Co., Ltd., mass average molecular weight 310.
-Novolak type phenol resin (ii): trade name "PSM-4261" manufactured by Gunei Chemical Industry Co., Ltd., mass average molecular weight 1050.
-Novolak type phenol resin (iii): product name "PSM-4324" manufactured by Gunei Chemical Industry Co., Ltd., mass average molecular weight 1950.
-Novolak type phenol resin (iv): trade name "PSM-4326" manufactured by Gunei Chemical Industry Co., Ltd., mass average molecular weight 6400.

<(B') component>
As the comparative product of the component (B) (component (B′)), the following was used.
Resol type phenol resin: trade name "GEB-100KF" manufactured by Gunei Chemical Industry Co., Ltd., mass average molecular weight 1000.
-Resorcin: Sumitomo Chemical Co., Ltd. trade name "Resorcin".

<(C) component>
As the component (C), the product name “Sila Ace S-310” manufactured by JNC Corporation was used.

<Fireproof granular material>
Quartz sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd., Fremantle Shinsand) was used as the refractory granular material.

<Acid catalyst>
The following acid catalysts were used.
GH-20: Acid catalyst containing sulfuric acid and xylene sulfonic acid (trade name "GH-20" manufactured by Gunei Chemical Industry Co., Ltd., S content 17.59% by mass relative to the total mass of the acid catalyst).
LH-100: an acid catalyst containing metaxylene sulfonic acid and lactic acid (trade name "LH-100" manufactured by Gunei Chemical Industry Co., Ltd., S content 3.44% by mass relative to the total mass of the acid catalyst).

<Measurement and evaluation>
(Measurement of water content)
The water content of the mixture (α) was determined by the water content test method for chemical products of JIS K0068.

(Measurement of nitrogen atom content)
The nitrogen atom content was determined by the titration method of the JIS K 0102 factory wastewater test method.

(Measurement of mass average molecular weight)
The mass average molecular weights of the novolac type phenol resin and the resol type phenol resin are GPC measuring device (Tosoh Corporation, HPLC8320GPC) and column (Tosoh Corporation, TSKgel G3000HXL+G2000HKL+G2000HKL), and polystyrene is used as a standard substance. It was measured.

(Measurement of viscosity)
1.1 mL of the binder composition was put in a measuring container, and the viscosity at 25° C. was measured using an E-type viscometer (trade name “VISCOMETER TV-25” manufactured by Toki Sangyo Co., Ltd.).

(Measurement of pot life)
The pot life was determined by JACT test method HM-2.

(Measurement of compressive strength)
The compressive strength (mold strength) of the test pieces obtained in each of the examples and comparative examples was determined by using a tabletop anti-pressure tester (manufactured by Takachiho Machine Co., Ltd.) in accordance with JIS Z 2601 test method for foundry sand. It was measured.

(Calculation of S reduction rate)
The S reduction rate was calculated from the following formula (1).
S reduction rate={(Y−X)/Y}×100 (1)
(In the formula (1), X is the amount of S added per 1 kg of the refractory granular material in each of Examples and Comparative Examples other than Comparative Example 1, and Y is per 1 kg of the refractory granular material in Comparative Example 1. It is the amount of S added.)

[Example 1]
<Production of binder composition>
The mixture (α) is adjusted so that the solid contents of the components (A), (B) and (C) and the blending amount of water (including water contained in the mixture (α)) have the values shown in Table 1. Then, the novolac-type phenol resin (i) as the component (B), the component (C), and water are introduced into a Shinagawa universal stirrer (Mixer manufactured by Shinagawa Kogyo Co., Ltd.), and the mixture is mixed. A binder composition was obtained.
The viscosity of the obtained binder composition was measured. The results are shown in Table 1.

<Production of sand composition>
A catalyst composition obtained by mixing GH-20 and LH-100 in a mass ratio (GH-20:LH-100=58:42) is used as an acid catalyst so that the sand composition has a pot life of 10 minutes. I was there.
The S content with respect to the total mass of the obtained catalyst composition was 11.65% by mass (=17.59×0.58+3.44×0.42).

A Shinagawa universal stirrer (manufactured by Shinagawa Industry Co., Ltd., MIXER) containing 100 parts by mass of the refractory granular material, 0.8 parts by mass of the binder composition obtained above, and 0.32 parts by mass of the catalyst composition. ) And mixed with each other to obtain a sand composition.
The amount of S added per 1 kg of the refractory granular material is 0.373 g (=0.32×0.1165×10).
The S reduction rate was determined for the obtained sand composition. The results are shown in Table 1.

<Manufacture of test pieces>
A part of the obtained sand composition was immediately filled into a wooden mold for making a test piece in which a columnar mold having an inner diameter of 50 mm and a height of 50 mm was formed and cured under the conditions of a temperature of 25° C. and a humidity of 40%. The test piece was taken out 1 hour after the initiation of curing (molding time 1 hour).
The compressive strength of the obtained test piece was measured 24 hours after the initiation of curing. The results are shown in Table 1.

[Examples 2 to 20]
The types of the component (B) were changed to those shown in Tables 1 to 4, and the solid contents of the components (A), (B) and (C), and the blending amount of water (the water contained in the mixture (α)). So as to have the values shown in Tables 1 to 4 except that the blending amounts of the mixture (α), (B) component, (C) component and water were changed. An agent composition was produced.
The viscosity of the obtained binder composition was measured. The results are shown in Tables 1 to 4.

Using the obtained binder composition, and so that the mass ratio of GH-20 and LH-100 is the value shown in Tables 1 to 4 so that the pot life of the sand composition is 10 minutes. A sand composition and a test piece were produced in the same manner as in Example 1 except that the catalyst composition changed to was used.
The S content with respect to the total mass of the catalyst composition, the S addition amount per kg of the refractory granular material, the S reduction rate, and the compressive strength of the test piece were measured. The results are shown in Tables 1 to 4.

[Comparative Example 1]
The mixture (α) is adjusted so that the solid contents of the components (A), (B) and (C) and the blending amount of water (including water contained in the mixture (α)) have the values shown in Table 5. A binder composition was produced in the same manner as in Example 1 except that the amounts of the components (B), (C) and water were changed.
The viscosity of the obtained binder composition was measured. The results are shown in Table 5.

Using the obtained binder composition, and changing the mass ratio of GH-20 and LH-100 to the values shown in Table 5 so that the pot life of the sand composition is 10 minutes. A sand composition and a test piece were produced in the same manner as in Example 1 except that the above catalyst composition was used.
The S content with respect to the total mass of the catalyst composition, the S addition amount per kg of the refractory granular material, and the compressive strength of the test piece were measured. The results are shown in Table 5.

[Comparative Examples 2 to 5]
The kind of the component (B) was changed to that shown in Table 5, and the solid contents of the components (A), (B) and (C), and the blending amount of water (including water contained in the mixture (α)). ) Becomes a value shown in Table 5, except that the blending amounts of the mixture (α), the component (B), the component (C) and water were changed to obtain a binder composition in the same manner as in Example 1. Manufactured.
The viscosity of the obtained binder composition was measured. The results are shown in Table 5.

Using the obtained binder composition, and changing the mass ratio of GH-20 and LH-100 to the values shown in Table 5 so that the pot life of the sand composition is 10 minutes. A sand composition and a test piece were produced in the same manner as in Example 1 except that the above catalyst composition was used.
The S content with respect to the total mass of the catalyst composition, the S addition amount per kg of the refractory granular material, the S reduction rate, and the compressive strength of the test piece were measured. The results are shown in Table 5.

[Comparative Examples 6 to 15]
The components (B′) shown in Tables 6 and 7 are used instead of the component (B), the solid contents of the components (A), (B′) and (C), and the blending amount of water (mixture (α) Example 1 except that the amounts of the mixture (α), the component (B′), the component (C) and the water were changed so that the water content (including water contained in) was the values shown in Tables 6 and 7. A binder composition was produced in the same manner.
The viscosity of the obtained binder composition was measured. The results are shown in Tables 6 and 7.

Using the obtained binder composition, and so that the mass ratio of GH-20 and LH-100 has the values shown in Tables 6 and 7 so that the pot life of the sand composition is 10 minutes. A sand composition and a test piece were produced in the same manner as in Example 1 except that the catalyst composition changed to was used.
The S content with respect to the total mass of the catalyst composition, the S addition amount per kg of the refractory granular material, the S reduction rate, and the compressive strength of the test piece were measured. The results are shown in Tables 6 and 7.

The compounding amounts of the component (A), the component (B) or the component (B'), and the component (C) in Tables 1 to 7 are solid contents. Further, the blending amount of the component (C) includes the amount of the silane coupling agent included in the mixture (α), and the blending amount of water includes the amount of water included in the mixture (α).
The content of each component in Tables 1 to 7 is the content (% by mass) of each component with respect to the total mass of the solid content of the binder composition. “A+B” is the total content (% by mass) of the components (A) and (B) with respect to the total mass of the solid content of the binder composition. “A:B” is a mass ratio of the component (A) and the component (B). “A+B′” is the total content (% by mass) of the components (A) and (B′) with respect to the total mass of the solid content of the binder composition. “A:B′” is the mass ratio of the component (A) and the component (B′).
In addition, about the compounding quantity and content of each component in Tables 1-7, the sum total may not be 100 mass% because of the relation of the effective figures rounded off.

From the results of Tables 1 to 7, the viscosity of the binder composition obtained in each example was within the practical range. Further, the S reduction rate in each of the sand compositions obtained in each example was high, and it was shown that the S addition amount to the refractory granular material was sufficiently reduced. Furthermore, the test pieces obtained in the respective examples had higher strength than the test pieces obtained in Comparative Examples 11 to 15, and all were within the practical range.
On the other hand, in the case of Comparative Examples 2 to 5, the S reduction rate was high, but compared with the Examples using the same type of component (B), the binder compositions obtained in Comparative Examples 2 to 5 were used. The viscosity was high and the strength of the test piece was low.
In Comparative Examples 6 to 10, the viscosity of the binder composition and the strength of the test piece were within the practical range, but the S reduction rate was low.
Therefore, according to the binder composition of the present invention, it is possible to reduce the amount of S added to the refractory granular material while keeping the pot life, viscosity and mold strength in the practical range, and to use furan resin and resorcin in combination. It was shown that the production cost of the binder composition and the mold can be reduced while maintaining the performance equivalent to that of the binders (Comparative Examples 11 to 15).

Claims (9)

A binder composition which is cured by an acid catalyst containing an S-containing acid,
Contains the following component (A) and the following component (B),
The mass ratio (A:B) of the following component (A) and the following component (B) is 100:0.5 to 100:45,
The binder composition in which the content of the following component (B) is 0.5 to 30 mass% with respect to the total mass of the solid content of the binder composition.
(A) component: furfuryl alcohol or furan resin (B) component: novolac type phenol resin The binder composition according to claim 1, wherein the component (B) has a mass average molecular weight of 200 to 8000. The binder according to claim 1 or 2, wherein the content of the raw material monomer remaining in the component (B) is less than 0.1% by mass based on the total mass of the solid content of the component (B). Composition. The binder composition according to any one of claims 1 to 3, wherein the content of the component (A) is 70 to 99.5 mass% with respect to the total mass of the solid content of the binder composition. .. 5. The total content of the component (A) and the component (B) with respect to the total mass of the solid content of the binder composition is 97% by mass or more, according to any one of claims 1 to 4. Binder composition. The binder composition according to claim 1, further comprising the following component (C).
Component (C): Silane coupling agent A sand composition containing the binder composition according to any one of claims 1 to 6, a refractory granular material, and an acid catalyst containing an S-containing acid. The sand composition according to claim 7, wherein the content of the binder composition is 0.1 to 3 parts by mass in terms of solid content with respect to 100 parts by mass of the refractory granular material. A method for producing a mold, comprising filling the sand composition according to claim 7 or 8 in a mold for molding, and curing the binder composition contained in the sand composition.