WO2010013629A1

WO2010013629A1 - Binder composition for casting mold formation and process for producing casting mold using the binder composition for casting mold formation

Info

Publication number: WO2010013629A1
Application number: PCT/JP2009/063132
Authority: WO
Inventors: 康弘永井; 正司吉村
Original assignee: 群栄化学工業株式会社
Priority date: 2008-07-29
Filing date: 2009-07-22
Publication date: 2010-02-04
Also published as: JP4663764B2; CN102105241A; JP2010029905A

Abstract

A binder composition for casting mold formation which can give a casting mold having sufficient strength without complicating the production step; and a process for producing a casting mold using the binder composition for casting mold formation. The binder composition for casting mold formation is characterized by comprising an acid-curable resin, water, and the chloride of a metal. The composition is further characterized in that the acid-curable resin comprises furfuryl alcohol and one or more products of the condensation or co-condensation of one or more members selected from a group consisting of furfuryl alcohol, phenols, and urea with an aldehyde, and that the metal is an alkaline earth metal and/or a zinc-family element.

Description

Binder composition for mold making and method for producing mold using binder composition for mold making

The present invention relates to a mold forming binder composition capable of improving the strength of a mold, and a mold production method using the mold forming binder composition.
This application claims priority based on Japanese Patent Application No. 2008-194719 filed in Japan on July 29, 2008, the contents of which are incorporated herein by reference.

Conventionally, a self-hardening mold is known as one of casting molds. The self-hardening mold is obtained by adding and kneading a binder mainly composed of an acid curable resin and a curing agent such as xylene sulfonic acid or phosphoric acid to a refractory granular material such as silica sand. It is manufactured by a method in which sand is filled into a mold and the binder is cured.

The acid curable resin is generally a resin mainly composed of furfuryl alcohol, urea, phenol, formaldehyde or the like, and is cured by polycondensation while dehydrating with an acid. The progress of curing of such an acid curable resin is affected by water generated by a dehydration reaction. That is, the surface portion that comes into contact with air tends to undergo a dehydration reaction and tends to harden. Accordingly, the self-hardening mold using the binder mainly composed of the acid curable resin has a difference in the degree of cure between the inside and the surface, and the strength is insufficient.
Therefore, there is a method of reducing the difference in the degree of cure between the inside and the surface by using a large amount of sulfuric acid as an acid and increasing the overall curing rate. However, it is known that when a large amount of sulfuric acid is used, a cured product constituting the mold is thermally decomposed and sulfurous acid gas is generated during pouring of the obtained mold. Sulfurous acid gas deteriorates the working environment or inhibits casting spheroidization. Therefore, it is not preferable to use a large amount of sulfuric acid.

As a method of improving the strength of the mold without using sulfuric acid, there is a method of blending a chloride such as calcium chloride in a refractory granular material (see Patent Document 1).
In this method, in order to absorb water generated by the dehydration reaction, a chloride such as calcium chloride is used in a powder form to absorb moisture. Furthermore, hydrochloric acid having a curing catalytic action is generated from chloride to promote curing.

Japanese Patent Publication No.51-3294

However, in Patent Document 1, it is necessary to mix the refractory granular material and the chloride in advance using a hopper or the like separately from the production line for obtaining the kneaded sand in order to mix the chloride powder. The manufacturing process has become complicated. Further, the chloride powder has a property of easily absorbing moisture. Therefore, there is a problem that it is difficult to manage in the factory in a powder state, and since it becomes a lump when it absorbs moisture, it is difficult to uniformly mix it in the refractory granular material.
As described above, the manufacturing method of Patent Document 1 has many inconveniences in manufacturing and is not practical, and has hardly been implemented.
In addition, as a result of confirmation by the present inventor, as in Patent Document 1, when using powdered metal chloride, it takes time to generate hydrochloric acid exhibiting a hardening promoting action, thereby improving the initial strength of the mold. I found it difficult to do. Therefore, in order to improve the initial strength of the mold, it is necessary to add the metal chloride to a certain amount or more. However, when the amount of the metal chloride added is large, the amount of hydrochloric acid produced increases, and a decomposition reaction may occur due to excess hydrochloric acid after curing, and the final strength of the mold tends to decrease.
In order to increase the curing speed, a method of directly adding hydrochloric acid having a curing catalytic action is also conceivable, but hydrochloric acid generates corrosive hydrogen chloride, which is difficult to store in a mold manufacturing factory, and is realistic. It wasn't.

The present invention has been made in view of the above circumstances, and is capable of obtaining a mold having a sufficient strength without complicating the production process, and a caking additive for mold making. It aims at obtaining the manufacturing method of the casting_mold | template using an agent composition.

The binder composition for mold making of the present invention contains an acid curable resin, water, and a metal chloride, and the acid curable resin is selected from the group consisting of furfuryl alcohol, phenols, and urea. 1 type or 2 types or more and 1 type or 2 types or more of a condensate or a cocondensate of aldehydes, and furfuryl alcohol (IUPAC name: 2-furanomethanol), The said metal is alkaline-earth It is a metal and / or zinc group element.

The method for producing a mold of the present invention comprises a step of mixing a binder composition for mold making, a refractory granular material and a curing agent to obtain kneaded sand, filling the kneaded sand into a mold for mold making, It has the process of hardening the binder composition for molding.
In the manufacturing method of the casting_mold | template of this invention, it is preferable that a refractory granular material is an alumina sand.

According to the binder composition for mold making of the present invention, the strength of the mold, particularly the initial strength, can be improved without complicating the process of the mold.
According to the method for producing a mold of the present invention, a mold having improved mold strength, particularly initial strength, can be obtained.

3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 1 and 2 and Comparative Examples 1 to 4 over time. 3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 3 to 6 and Comparative Example 1 over time. 3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 7 to 11 and Comparative Example 1 over time. 3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 12 to 16 and Comparative Example 3 over time. 6 is a bar graph showing the compressive strength of the test pieces obtained in Examples 17 to 20 and Comparative Example 5 over time. 3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 21 to 24 and Comparative Example 6 over time. 3 is a bar graph showing the compressive strength of the test pieces obtained in Examples 25 to 28 and Comparative Example 7 over time.

[Binder composition for mold making]
The binder composition for mold making of the present invention (hereinafter referred to as “binder composition”) is used as a binder when producing a mold, and includes an acid curable resin, water, And containing metal chlorides.

An acid curable resin is a substance that is cured by polycondensation with an acid. In the present invention, as the acid curable resin, one or more of a condensate or a cocondensate of one or two or more selected from the group consisting of furfuryl alcohol, phenols and urea and an aldehyde, and Use one containing furfuryl alcohol.

Examples of aldehydes include formaldehyde, glyoxal, and furfural. You may use these in combination of 2 or more type. However, depending on the type of condensate, when glyoxal or furfural is used alone as an aldehyde, acid curing may not proceed. In such a case, at least formaldehyde may be used as the aldehyde.

Examples of phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, bisphenol F, and bisphenol Z. You may use these in combination of 2 or more type.

Further, when producing a condensate of phenols and aldehydes, it is preferable to use 1 to 3 moles of aldehydes per mole of phenols. If the amount of aldehyde used is 1 mol or more, it becomes a condensate with a low degree of polymerization, so that the pot life can be easily set. Good expression.

When producing a condensate of furfuryl alcohol and aldehydes, it is preferable to use 0.1 to 1 mol of aldehyde per 1 mol of furfuryl alcohol. If the amount of aldehyde used is 0.1 mol or more, it becomes a condensate with a low degree of polymerization, so that the pot life can be easily set, and if it is 1 mol or less, it becomes a condensate with a high degree of polymerization. The final template strength is improved.

Further, the content of nitrogen atoms derived from urea or the like is preferably in the range of 0.1 to 6% by mass per 100% by mass of the total of the acid curable resin and water, and is preferably 0.1 to 4%. More preferably, it is 5 mass%.
The nitrogen atom content affects the initial strength and final strength of the template. 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 high. The final strength of the steel tends to increase.
Accordingly, it is preferable to appropriately adjust the nitrogen atom content as necessary. If the nitrogen atom content is within the above range, a template having a favorable initial strength and final strength can be obtained.

The following four examples are particularly preferable for the acid curable resin. In addition, the (co) condensate in the following means a condensate and / or a cocondensate.
i) A mixture of a (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes with furfuryl alcohol.
ii) A mixture of urea and aldehyde condensate and furfuryl alcohol.
iii) A mixture of (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes, a condensate of phenol and aldehydes, and furfuryl alcohol.
iv) A mixture of a condensation product of phenol and aldehydes and furfuryl alcohol.
It is preferable that the acid curable resin is in such a form of i) to iv) because a binder composition that can easily set the pot life and can improve the mold strength can be obtained.
In the embodiment i), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 15 to 45% by mass, and preferably 25 to 35% by mass. Is more preferable. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the embodiment ii), the ratio of the condensate of urea and aldehydes in the acid curable resin is preferably 3.5 to 20% by mass, and more preferably 6.9 to 13.5% by mass.
The ratio of furfuryl alcohol is preferably 80 to 96.5% by mass, and more preferably 86.5 to 93.1% by mass.
In the embodiment of iii), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 7.5 to 22.5% by mass, More preferably, the content is 5 to 17.5% by mass. The ratio of the condensate of phenol and aldehyde is preferably 7.5 to 22.5% by mass, and more preferably 12.5 to 17.5% by mass. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the embodiment iv), the ratio of the condensate of phenol and aldehyde in the acid curable resin is preferably 10 to 40% by mass, and more preferably 20 to 30% by mass. The ratio of furfuryl alcohol is preferably 60 to 90% by mass, and more preferably 70 to 80% by mass.

The content of the acid curable resin in the binder composition is preferably 2 to 98% by mass, more preferably 70 to 98% by mass, and 81.5 to 94.5% by mass. More preferably it is.
When the content of the acid curable resin in the binder composition is 2% by mass or more, it is easy to set the pot life and the initial strength of the mold tends to be improved. On the other hand, if it is 98% by mass or less, the final strength of the mold tends to be improved.

The binder composition of the present invention contains water. Here, the water includes water derived from the combined water of metal chlorides, water derived from condensed water produced when synthesizing each (co) condensate such as a condensate of urea and aldehydes, an aqueous raw material (for example, All water supplied by formalin, etc.) and any water added separately as needed.
The water content in the binder composition is preferably 1 to 25% by mass, and more preferably 3 to 15% by mass.
When the content of water in the binder composition is 1% by mass or more, the strength of the mold tends to be easily developed. On the other hand, when it is 25% by mass or less, a significant cost increase of the binder composition can be suppressed.

As the metal chloride, an alkaline earth metal chloride and / or a zinc group element chloride is used. Specific examples include calcium chloride, magnesium chloride, barium chloride, and zinc chloride, and one or more of these are used. Of these, calcium chloride is preferably used because of its low cost and excellent solubility.
The content of the metal chloride in the binder composition is preferably 1 to 5% by mass, more preferably 2.5 to 3.5% by mass in terms of anhydride.
When the content of the metal chloride is within the above range, both the initial strength and final strength of the mold can be improved.
On the other hand, when the content of the metal chloride in the binder composition is less than 1% by mass, it tends to be difficult to obtain the initial strength of the mold. If it exceeds 5% by mass, the initial strength of the mold can be obtained, but the final strength of the mold cannot be maintained. This is presumably because a decomposition reaction occurs in the mold due to excessively generated hydrochloric acid.

In the binder composition, a silane coupling agent such as N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane may be added for the purpose of improving the strength of the obtained template.
In the binder composition of the present invention, the silane coupling agent can be contained in an amount of 0.01 to 3% by mass, and more preferably 0.1 to 1% by mass. When 0.01% by mass or more of the silane coupling agent is contained, the strength of the mold can be improved, and if it is 3% by mass or less, a significant cost increase can be suppressed.

Further, the binder composition may contain urea, resorcinol, pyrogallol and the like for the purpose of reducing formaldehyde generated during casting pouring.
In this case, the total content of these in the binder composition is preferably 0.1 to 3% by mass, and more preferably 0.5 to 1% by mass. If these total content is 0.1 mass% or more, it becomes a binder composition excellent in reduction of formaldehyde, and if it is 3 mass% or less, a significant cost increase can be suppressed.

The binder composition of the present invention can be obtained by a general production method. An example of the method for producing the binder composition of the present invention is shown below.
First, a part of the raw material of acid curable resin (furfuryl alcohol, aldehydes, urea, phenols, etc.) is mixed with an aqueous sodium hydroxide solution to make it alkaline, and the temperature is raised to produce a (co) condensate. . Next, it is acidified using hydrochloric acid or the like, and after a reaction such as a condensate of urea and aldehyde is allowed to proceed, it is rendered alkaline again, and the remaining acid curable resin raw materials are mixed to obtain an acid curable resin.
Since the amount of hydrochloric acid added here is small, it does not progress to the curing reaction.
Then, the acid curable resin, water, and the metal chloride are mixed and dissolved in the acid curable resin by mixing and dissolving the metal chloride and other components such as a silane coupling agent added as necessary. A binder composition of the present invention containing is obtained.

The binder composition of the present invention contains a metal chloride already dissolved. Therefore, it is not necessary to control the humidity at the mold manufacturing site so that the metal chloride does not absorb moisture. Moreover, it is not necessary to complicate the process for obtaining the kneaded sand.

[Mold manufacturing method]
The method for producing a mold according to the present invention comprises a step of mixing a binder composition, a refractory granular material and a curing agent to obtain kneaded sand, filling the kneaded sand into a mold for mold making, A step of curing the binder composition;

As the refractory granular material, conventionally known materials such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Recycled ones can also be used.
In particular, it is preferable to use chromite sand, zircon sand, and alumina sand for a portion that requires fire resistance, and among them, it is preferable to use alumina sand that does not cost and has no problem with disposal.

As the curing agent, one or more conventionally known compounds such as sulfonic acid compounds such as xylene sulfonic acid, phosphoric acid compounds, and sulfuric acid can be used.
By the way, in kneading sand, the binder composition of this invention and a hardening | curing agent are mixed. At this time, chlorine liberated in the water in the binder composition and a part of the curing agent react to produce hydrochloric acid having a curing catalytic action.
When each of the above-mentioned curing agents is compared with hydrochloric acid, the curing rate tends to be higher in the order of hydrochloric acid, sulfuric acid, phosphoric acid compound, and sulfonic acid compound. On the other hand, the curing strength is obtained in the order of sulfonic acid compound, phosphoric acid compound, sulfuric acid and hydrochloric acid.
Therefore, in the present invention, it is preferable to use an appropriate curing agent in consideration of the balance between the initial strength and final strength of the mold.

The mixing ratio of the refractory granular material, the binder composition and the curing agent in the kneaded sand can be set as appropriate, but the mixing ratio of the binder composition is 0.3 to 2 with respect to 100 parts by mass of the refractory granular material. The amount is preferably 0.5 to 1.5 parts by mass. Further, the mixing ratio of the curing agent is preferably 0.045 to 1.2 parts by mass, and more preferably 0.075 to 0.9 parts by mass. With such a mixing ratio, it is easy to obtain a mold having sufficient strength.
In the step of obtaining the kneaded sand, the binder composition, the refractory granular material and the curing agent are mixed to obtain the kneaded sand. At this time, the mixing method is not particularly limited as long as it is a general mixing method, and for example, a stirrer or the like can be used.

The content of the metal chloride in the kneaded sand having the above mixing ratio is preferably 0.003 to 0.2% by mass, more preferably 0.005 to 0.15% by mass, It is preferable that it is 05 mass% or less.
When the content of the metal chloride in the kneaded sand is in the above range, a sufficiently strong mold can be easily obtained, and particularly when it is 0.05% by mass or less, the hydrochloric acid generated by the metal chloride is almost completely cured. All tend to evaporate and tend not to affect the final strength of the mold.
For example, when the mixing ratio of the binder composition to 100 parts by mass of the refractory granular material is 1 part by mass and the mixing ratio of the curing agent is 0.4 parts by mass, the content of metal chloride in the kneaded sand is In order to make it 0.05 mass% or less, what is necessary is just to use the binder composition which contains a metal chloride 5 mass% or less in conversion of an anhydride as a binder composition.

Next, a mold is produced from the obtained kneaded sand.
As a method for producing the mold, a self-hardening mold making method can be employed. That is, when the kneaded sand is filled in a predetermined mold for mold making, the binder composition in the kneaded sand is cured by the action of the curing agent. As a result, a template can be obtained.
In the mold manufacturing method of the present invention, a binder composition in which metal chlorides are uniformly mixed and dissolved in advance is used. Therefore, the metal chloride is easily dispersed uniformly throughout the kneaded sand, and the hydrochloric acid generated from the metal chloride improves not only the surface of the mold but also the internal hardening, thereby further improving the strength of the mold. .

Further, if the metal chloride is in a powder form, it cannot exhibit a curing promoting action, but can be dissolved in water or the like and further contacted with an acid to produce hydrochloric acid to exhibit a curing action.
In the present invention, the metal chloride is previously dissolved in the binder composition together with water. Therefore, when a curing agent is added, hydrochloric acid having a reaction for curing can be obtained immediately. For this reason, it is not necessary to add a certain amount or more of metal chloride as in the case of mixing powdered metal chloride. Rather, the initial strength of the mold is reduced while minimizing the addition amount. Can be improved. That is, excessive hydrochloric acid is hardly generated and the final strength tends to be improved.
Thus, according to the manufacturing method of the casting_mold | template using the binder composition of this invention, the casting_mold | template which improved both initial strength and final strength can also be obtained.

In such a method for producing a mold using the binder composition of the present invention, even when alumina sand is used as the refractory granular material, it is possible to obtain a mold strength equivalent to that when using conventional silica sand. It becomes.
Alumina sand has attracted attention as a refractory granular material for molds because of its high fire resistance and excellent crushing resistance. However, since its heat capacity is larger than that of silica sand, which is a conventional refractory granular material, a mold manufactured using this material is used. Has a slow curing rate and tends to increase the difference in the degree of cure between the inside and the surface, making it difficult to obtain strength and difficult to put into practical use.
However, the binder composition of the present invention can improve the initial strength of the mold and the strength after a long period of time while improving not only the surface of the mold but also the internal curing. Even when a refractory granular material such as large alumina sand is used, a mold strength equivalent to that obtained when conventional silica sand is used can be obtained. Therefore, even a refractory granular material having a high heat capacity such as alumina sand can be produced.

Furthermore, in the present invention, hydrochloric acid having a curing catalytic action is generated in the mold manufacturing process. Therefore, it is possible to reduce the use amount of the curing agent, and it is possible to suppress the use amount of sulfuric acid.
If the amount of sulfuric acid used can be reduced in this way, the amount of sulfurous acid gas generated can be greatly reduced, and a better working environment can be obtained. At the same time, the rate of occurrence of hindered spheroidization due to sulfur in the sulfurous acid gas Can also be reduced.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In addition, the composition of the binder composition used in each Example and Comparative Example and each physical property of the obtained mold (test piece) were measured by the following methods.

(Water content)
The water content was determined by the moisture test method for chemical products of JIS K 0068.

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

(Compressive strength)
For the compressive strength (mold strength) of the test pieces obtained in each of the examples and comparative examples, use a desktop counter pressure tester (manufactured by Takachiho Kikai Co., Ltd.) according to the testing method for foundry sand of JIS Z 2601. Measured with

(The bulk density)
The bulk density of the test pieces obtained in each Example and Comparative Example was determined by the following general formula (I). METLER PM 4000 (manufactured by Nippon Shibel Hegner Co., Ltd.) was used as an electronic balance used for mass measurement.
The bulk density is measured to confirm that the wooden mold is filled with approximately the same mass of kneaded sand.
Test piece bulk density (g / cm ³ ) = Test piece mass (g) / Test piece volume (cm ³ ) (I)

[Example 1]
(Binder composition)
859.2 parts by mass of furfuryl alcohol, 47.05 parts by mass of urea, 65.9 parts by mass of paraformaldehyde of 92% by mass, and 2.0 parts by mass of a 15% by mass aqueous sodium hydroxide solution, The mixture was placed in a four-necked flask equipped with a stirrer and allowed to react at 80 ° C. for 1 hour. Then, 3.0 parts by mass of 10% by mass hydrochloric acid was added, and further reacted for 3 hours. Thereafter, 2.0 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 28.84 parts by mass of urea were added and reacted for another 30 minutes. Thereafter, a silane coupling agent (N-β (aminoethyl) γ- 2 parts of aminopropylmethyldimethoxysilane), a binder composition (A) comprising (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes, free furfuryl alcohol and water. 1010 parts by mass were obtained. The water content in 1010 parts by mass of the binder composition (A) was 4.5% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin and water was 3.5% by mass. It was.
To 96.03 parts by mass of the obtained binder composition (A), 3.97 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved to obtain a binder composition (B). 100 parts by mass (containing 3% by mass of calcium chloride in terms of anhydride) was obtained.

(Kneading sand)
Next, 1.03 parts by mass of the binder composition (B) and a curing agent (67% by mass of xylene sulfonic acid and sulfuric acid) with respect to 100 parts by mass of silica sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd., free mantle new sand). 0.4 parts by mass of a 75% by mass aqueous solution containing 8% by mass and kneaded with a Shinagawa universal agitator (MIXER, manufactured by Shinagawa Kogyo Co., Ltd.) to obtain kneaded sand.

A portion of the kneaded sand thus obtained is immediately filled into a test piece preparation wooden mold having a mold with an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 30 ° C. and a humidity of 35%. After 30 minutes, the test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

[Comparative Example 1]
1.0 mass part of binder composition (A) and 0.4 mass part of hardening | curing agent were added with respect to 100 mass parts of silica sand, and it knead | mixed with the Shinagawa type universal stirrer, and kneaded sand was obtained.
A part of the kneaded sand obtained was filled into a test piece production wooden mold under the same conditions as in Example 1 and cured, and the test piece was taken out after 30 minutes from the start of curing (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

[Comparative Example 2]
100 parts by mass of silica sand and 0.04 parts by mass of calcium chloride dihydrate (manufactured by Pure Chemical Co., Ltd.) are mixed in advance, and 100.04 parts by mass of calcium chloride-containing sand (0.03 mass of calcium chloride in terms of anhydride). Part contained).
With respect to 100.04 parts by mass of calcium chloride-containing sand (containing 0.03 parts by mass of calcium chloride in terms of anhydride), 1.0 part by mass of the binder composition (A) and 0.4 parts by mass of the curing agent, And kneaded with a Shinagawa universal stirrer to obtain kneaded sand.
A part of the kneaded sand obtained was filled into a test piece production wooden mold under the same conditions as in Example 1 and cured, and the test piece was taken out after 30 minutes from the start of curing (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

[Example 2]
A test piece was prepared in the same manner as in Example 1 except that alumina sand (Alsand 350 # new sand, manufactured by Cosmo Co., Ltd.) was used instead of silica sand, and 30 minutes from the start of curing in the same manner as in Example 1. The compressive strength and bulk density after 1 hour, 3 hours and 24 hours were measured. The results are shown in Table 1.

[Comparative Example 3]
A test piece was prepared in the same manner as in Comparative Example 1 except that alumina sand was used instead of silica sand, and the compressive strength and bulk density after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

[Comparative Example 4]
Test pieces were produced in the same manner as in Comparative Example 2 except that alumina sand was used instead of silica sand, and the compressive strength and bulk density after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 1.

From Table 1 and FIG. 1, Example 1, Comparative Example 1 and Comparative Example 2 using the same silica sand as the refractory granular material are compared.
A comparative example in which calcium chloride was not used at all for the compressive strength (initial strength) after 30 minutes and the compressive strength (final strength) after 24 hours in Example 1 in which calcium chloride was contained in the binder composition. It is clearly higher than 1, and it can be said that the effect of improving the strength of the mold is obtained. On the other hand, the compression strength after 30 minutes in Comparative Example 2 in which calcium chloride was mixed with silica sand was higher than that in Comparative Example 1 in which no calcium chloride was used, but was not as high as in Example 1.
From Table 1 and FIG. 1, Example 2, Comparative Example 3, and Comparative Example 4 using the same alumina sand as the refractory granular material are compared.
The compressive strength after 30 minutes and the compressive strength after 24 hours in Example 2 in which calcium chloride was contained in the binder composition were clearly higher than those of Comparative Example 3 in which no calcium chloride was used. It can be said that the effect of improving the strength is obtained. On the other hand, the compressive strength after 30 minutes and the compressive strength after 24 hours in Comparative Example 4 in which calcium chloride was mixed with alumina sand showed higher values than Comparative Example 3 in which no calcium chloride was used. It was not about two.

In the said Example 1, 2, 0.03 mass% of calcium chloride is contained in kneaded sand. On the other hand, Comparative Examples 2 and 4 contain 0.03% by mass of calcium chloride in the kneaded sand. That is, the calcium chloride content in the kneaded sand of Examples 1 and 2 and Comparative Examples 2 and 4 is the same.
Nevertheless, the compressive strength after 30 minutes and the compressive strength after 24 hours in Examples 1 and 2 are clearly superior to Comparative Examples 2 and 4, respectively. This is because, in Examples 1 and 2, since calcium chloride was previously dissolved in the binder composition, it could react with acid immediately to form hydrochloric acid, and it was easy to obtain compressive strength after 30 minutes. It is thought that. In Examples 1 and 2, it is considered that the compressive strength after 24 hours was easily obtained because calcium chloride in the kneaded sand was easily dispersed uniformly.
Furthermore, the compressive strength after 30 minutes in Example 2 is superior to the compressive strength after 30 minutes of Comparative Example 1. That is, when the binder composition of the present invention is used, even when alumina sand having a large heat capacity is used, an initial strength equal to or higher than that obtained when silica sand having a small heat capacity is used by a normal method is obtained. Can be said.

[Examples 3 to 6]
1 part by mass of each of the following binder compositions and 0.4 part by mass of a curing agent (75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. The kneaded sand of each example was obtained by adding and kneading with a Shinagawa universal stirrer.

Example 3: Binder composition (B) (containing 3% by mass of calcium chloride in terms of anhydride).
Example 4: Binding agent composition (A) 93.6 parts by mass, 6.4 parts by mass of magnesium chloride hexahydrate (MgCl ₂ .6H ₂ O) was mixed and dissolved to give 100 parts by mass. Agent composition (C) (containing 3% by mass of magnesium chloride in terms of anhydride).
Example 5: Baking agent composition (A): 96.48 parts by mass of 3.52 parts by mass of barium chloride dihydrate (BaCl ₂ .2H ₂ O) was mixed and dissolved to give 100 parts by mass. Agent composition (D) (containing 3% by mass of barium chloride in terms of anhydride).
Example 6: Binder composition (E) (chlorinated) which was prepared by mixing and dissolving 3.0 parts by mass of zinc chloride (ZnCl ₂ ) in 97.0 parts by mass of the binder composition (A). Containing 3% by weight of zinc).

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 2.

From Table 2 and FIG. 2, in Examples 3 to 6, the compressive strength after 30 minutes and the compressive strength after 24 hours are both Comparative Examples 1 using a binder composition in which a metal chloride is not mixed. It is clearly higher and it can be said that the effect of improving the strength of the mold is obtained.
Therefore, it can be said that the effect of improving the initial strength and final strength of the mold can be obtained by mixing not only calcium chloride but also zinc group element and alkaline earth metal chlorides into the binder composition.

[Examples 7 to 11]
1 part by mass of each of the following binder compositions and 0.4 part by mass of a curing agent (75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. The kneaded sand of each example was obtained by adding and kneading with a Shinagawa universal stirrer.

Example 7: Binder composition (F) (chlorinated) which was prepared by mixing and dissolving 1.32 parts by mass of calcium chloride dihydrate in 98.68 parts by mass of binder composition (A). 1% by mass of calcium in terms of anhydride).
Example 8: Binder composition (G) (100% by mass) by mixing and dissolving 3.97 parts by mass of calcium chloride dihydrate in 96.03 parts by mass of binder composition (A) 3% by mass of calcium in terms of anhydride).
Example 9: Binder composition (H) (chlorinated) made by mixing and dissolving 6.62 parts by mass of calcium chloride dihydrate in 93.38 parts by mass of binder composition (A). 5% by mass of calcium in terms of anhydride).
Example 10: Binder composition (I) (salt chloride) prepared by mixing and dissolving 10.6 parts by mass of calcium chloride dihydrate in 89.4 parts by mass of binder composition (A). 8% by mass of calcium in terms of anhydride).
Example 11: Binder composition (J) (chlorinated) obtained by mixing and dissolving 13.25 parts by mass of calcium chloride dihydrate in 86.75 parts by mass of binder composition (A). 10% by mass of calcium in terms of anhydride).

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 3.

In Comparative Example 1 and Examples 7 to 11, the amount of calcium chloride in the binder composition was changed to 0, 1, 3, 5, 8, and 10% by mass. From Table 3 and FIG. 3, the compressive strength after 30 minutes tended to increase as the amount of calcium chloride increased. However, when the amount of calcium chloride is 8% by mass or more, the compressive strength after 24 hours tends to be difficult to obtain. Therefore, it was found that the amount of metal chloride should be adjusted depending on whether the initial strength or the final strength is important. In particular, when the amount of calcium chloride was 5 mass% or less and 3 mass% or more, both the compressive strength after 30 minutes and the compressive strength after 24 hours were clearly improved, which was preferable.

[Examples 12 to 16]
Each kneaded sand was obtained in the same manner as in Examples 7 to 11 except that alumina sand was used instead of silica sand.
Further, a part of each kneaded sand obtained was filled in a wooden piece for test piece preparation under the same conditions as in Examples 7 to 11 and cured, and each test piece was taken out after 30 minutes from the start of curing (die cutting). 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 4.

In Comparative Example 3 and Examples 12 to 16, the amount of calcium chloride in the binder composition was changed to 0, 1, 3, 5, 8, and 10% by mass. From Table 4 and FIG. 4, the compressive strength after 30 minutes tended to increase as the amount of calcium chloride increased. However, when the amount of calcium chloride is 8% by mass or more, the compressive strength after 24 hours tends to be difficult to obtain. Therefore, it was found that the amount of metal chloride should be adjusted depending on whether the initial strength or the final strength is important. In particular, when the amount of calcium chloride was 5 mass% or less and 3 mass% or more, both the compressive strength after 30 minutes and the compressive strength after 24 hours were clearly improved, which was preferable.

[Example 17]
(Binder composition)
47.0 parts by mass of urea, 121.1 parts by mass of a 50% by mass aqueous formaldehyde solution, and 1.2 parts by mass of a 15% by mass aqueous sodium hydroxide solution having a 0.5 liter capacity equipped with a thermometer, a cooler and a stirrer The mixture was placed in a four-necked flask and allowed to react at 80 ° C. for 1 hour, and then 2.5 parts by mass of 10% by mass hydrochloric acid was added and further reacted for 3 hours. Thereafter, 2.5 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 28.8 parts by mass of urea were added and reacted for another 30 minutes to obtain 203.1 parts by mass of a urea-formaldehyde condensate. Thereafter, 100 parts by mass of the condensate of urea and formaldehyde, 400.35 parts by mass of furfuryl alcohol, and a silane coupling agent (N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane) were added to a 1 liter flask. 0 part by mass was added to obtain 501.35 parts by mass of a binder composition (K). The water content in the binder composition (K) 501.35 parts by mass is 10.5% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin and water is 3.5% by mass. Met.
To 96.03 parts by mass of the obtained binder composition (K), 3.97 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved to obtain a binder composition (L). 100 parts by mass (containing 3% by mass of calcium chloride in terms of anhydride) was obtained.

(Kneading sand)
Next, 1.0 part by mass of the binder composition (L) and a curing agent (75% by mass aqueous solution containing 67% by mass of xylenesulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. 4 parts by mass were added and kneaded with a Shinagawa universal stirrer to obtain kneaded sand.

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compression strength and bulk density of the obtained test pieces were measured after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing. The results are shown in Table 5.

[Examples 18 to 20]
1 part by mass of each of the following binder compositions and 0.4 part by mass of a curing agent (75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. The kneaded sand of each example was obtained by adding and kneading with a Shinagawa universal stirrer.

Example 18: Bonding to 100 parts by mass by mixing and dissolving 6.4 parts by mass of magnesium chloride hexahydrate (MgCl ₂ .6H ₂ O) in 93.6 parts by mass of the binder composition (K). Agent composition (M) (containing 3% by mass of magnesium chloride in terms of anhydride).
Example 19: caking was made by mixing and dissolving 3.52 parts by mass of barium chloride dihydrate (BaCl ₂ .2H ₂ O) in 96.48 parts by mass of the binder composition (K). Agent composition (N) (containing 3% by mass of barium chloride in terms of anhydride).
Example 20: Binder composition (O) (chlorinated) which was prepared by mixing and dissolving 3.0 parts by mass of zinc chloride (ZnCl ₂ ) in 97.0 parts by mass of binder composition (K). Containing 3% by weight of zinc).

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 5.

[Comparative Example 5]
1.0 mass part of binder composition (K) and 0.4 mass part of hardening | curing agent were added with respect to 100 mass parts of silica sand, and it knead | mixed with the Shinagawa type universal stirrer, and kneaded sand was obtained.
A part of the kneaded sand obtained was filled into a test piece production wooden mold under the same conditions as in Example 1 and cured, and the test piece was taken out after 30 minutes from the start of curing (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 5.

In Comparative Example 5 and Examples 17 to 20, urea and formaldehyde condensate and furfuryl alcohol are used as the acid curable resin.
Here, from Table 5 and FIG. 5, in Examples 17 to 20 using the binder composition mixed with metal chloride, the compressive strength after 30 minutes and the compressive strength after 24 hours are both It is clearly higher than Comparative Example 5 using a binder composition in which a metal chloride is not mixed, and it can be said that an effect of improving the strength of the mold is obtained. The same can be said for Table 2 and FIG. 2 described above, in which furfuryl alcohol, a condensate of urea and formaldehyde, and furfuryl alcohol are used as the acid curable resin.
Therefore, even when urea-formaldehyde condensate and furfuryl alcohol are used as the acid curable resin, it can be said that the effect of improving the initial strength and final strength of the mold can be obtained by adding metal chloride.

[Example 21]
(Binder composition)
861.2 parts by mass of furfuryl alcohol, 47.05 parts by mass of urea, 65.9 parts by mass of paraformaldehyde of 92% by mass, and 2.0 parts by mass of a 15% by mass aqueous sodium hydroxide solution, The mixture was placed in a four-necked flask equipped with a stirrer and allowed to react at 80 ° C. for 1 hour. Thereafter, 2.0 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 28.84 parts by mass of urea are added and reacted for another 30 minutes to condense urea, furfuryl alcohol and aldehydes (both ) 1010 parts by mass of a mixture of the condensate, free furfuryl alcohol and water was obtained. The water content in 1010 parts by mass of the mixture was 4.5% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin and water was 3.5% by mass.
Meanwhile, 470.5 parts by mass of phenol, 330 parts by mass of 50% by mass aqueous formaldehyde solution, and 19.5 parts by mass of 25% by mass aqueous ammonia solution were placed in a four-necked flask equipped with a thermometer, a cooler, and a stirrer. The mixture was reacted at 100 ° C. for 1 hour and 10 minutes, and then concentrated to an internal temperature of 80 ° C. at a vacuum degree of 0.015 MPa. Thereafter, 368 parts by mass of furfuryl alcohol was added to obtain 974.1 parts by mass of a mixture of phenol and formaldehyde, furfuryl alcohol and water. The content of water in the mixture of 974.1 parts by mass of the phenol / formaldehyde condensate, furfuryl alcohol and water was 4.5% by mass.
898.2 parts by mass of a mixture of (co) condensate obtained by condensing the urea, furfuryl alcohol and aldehydes produced earlier, free furfuryl alcohol and water, and condensation of phenol and formaldehyde produced later A binder composition comprising 898.2 parts by mass of a mixture of a product, furfuryl alcohol and water and 3.6 parts by mass of a silane coupling agent (N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane) (P) 1800 parts by mass were obtained.
The water content in 1800 parts by mass of the binder composition (P) was 4.5% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin and water was 1.85% by mass. It was.
To 96.03 parts by mass of the obtained binder composition (P), 3.97 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved, and the binder composition (Q) was dissolved. 100 parts by mass (containing 3% by mass of calcium chloride in terms of anhydride) was obtained.

(Kneading sand)
Next, 1.0 part by mass of the binder composition (Q) and a curing agent (75% by mass aqueous solution containing 67% by mass of xylenesulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. 4 parts by mass were added and kneaded with a Shinagawa universal stirrer to obtain kneaded sand.

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 6.

[Examples 22 to 24]
1 part by mass of each of the following binder compositions and 0.4 part by mass of a curing agent (75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. The kneaded sand of each example was obtained by adding and kneading with a Shinagawa universal stirrer.

Example 22: Binding of 100 parts by mass by mixing and dissolving 6.4 parts by mass of magnesium chloride hexahydrate (MgCl ₂ .6H ₂ O) in 93.6 parts by mass of the binder composition (P). Agent composition (R) (containing 3% by mass of magnesium chloride in terms of anhydride).
Example 23: binder composition (P) 96.48 parts by weight of barium chloride dihydrate _(BaCl ₂ · 2H ₂ O) 3.52 parts by mass were mixed and dissolved, and 100 parts by mass caking Agent composition (S) (containing 3% by mass of barium chloride in terms of anhydride).
Example 24: Binder composition (T) (chlorinated) which was prepared by mixing and dissolving 3.0 parts by mass of zinc chloride (ZnCl ₂ ) in 97.0 parts by mass of the binder composition (P). Containing 3% by weight of zinc).

[Comparative Example 6]
1.0 mass part of binder composition (P) and 0.4 mass part of hardening | curing agent were added with respect to 100 mass parts of silica sand, and it knead | mixed with the Shinagawa type universal stirrer, and kneaded sand was obtained.
A part of the kneaded sand obtained was filled into a test piece production wooden mold under the same conditions as in Example 1 and cured, and the test piece was taken out after 30 minutes from the start of curing (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 6.

In Comparative Example 6 and Examples 21 to 24, as the acid curable resin, a (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes, a phenol / formaldehyde condensate and furfuryl alcohol were used. Yes.
Here, as shown in Table 6 and FIG. 6, in Examples 21 to 24 using the binder composition mixed with metal chloride, the compressive strength after 30 minutes indicates that the metal chloride is not mixed. It is higher than Comparative Example 6 using the agent composition, and it can be said that the effect of improving the initial strength of the mold is obtained.
Therefore, when phenol is used as a constituent component of the acid curable resin, it can be said that the addition of metal chloride does not improve the final strength of the mold, but can improve the initial strength.

[Example 25]
(Binder composition)
297.2 parts by mass of furfuryl alcohol, 8.0 parts by mass of urea, 20.64 parts by mass of a 50% by mass aqueous formaldehyde solution, and 0.7 parts by mass of a 15% by mass aqueous sodium hydroxide solution, The mixture was placed in a four-necked flask equipped with a stirrer and allowed to react at 80 ° C. for 1 hour. Then, 1.3 parts by mass of 10% by mass hydrochloric acid was added and further reacted for 3 hours. Thereafter, 1.0 part by mass of a 15% by mass aqueous sodium hydroxide solution and 4.9 parts by mass of urea were added and reacted for another 30 minutes, and then a silane coupling agent (N-β (aminoethyl) γ-amino was added. (Propylmethyldimethoxysilane) 0.66 parts by mass and a binder comprising a mixture of (co) condensate obtained by condensing urea, furfuryl alcohol and aldehyde, free furfuryl alcohol and water Composition (U) 334.4 mass parts was obtained. The content of water in the binder composition (U) 334.4 parts by mass is 4.0% by mass, and the nitrogen atom content with respect to the total amount of the acid curable resin and water is 1.8% by mass. Met.
To 96.03 parts by mass of the obtained binder composition (U), 3.97 parts by mass of calcium chloride dihydrate (CaCl ₂ .2H ₂ O) was mixed and dissolved to obtain a binder composition (V). 100 parts by mass (containing 3% by mass of calcium chloride in terms of anhydride) was obtained.

(Kneading sand)
Next, 1.0 part by mass of the binder composition (V) and a curing agent (75% by mass aqueous solution containing 67% by mass of xylenesulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. 4 parts by mass were added and kneaded with a Shinagawa universal stirrer to obtain kneaded sand.

A portion of each kneaded sand thus obtained is immediately filled into a test piece-manufacturing wood mold with a mold having an inner diameter of 50 mm and a height of 50 mm under the conditions of a temperature of 25 ° C. and a humidity of 55%, and curing is started. 30 minutes later, each test piece was taken out (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 7.

[Examples 26 to 28]
1 part by mass of each of the following binder compositions and 0.4 part by mass of a curing agent (75% by mass aqueous solution containing 67% by mass of xylene sulfonic acid and 8% by mass of sulfuric acid) with respect to 100 parts by mass of silica sand. The kneaded sand of each example was obtained by adding and kneading with a Shinagawa universal stirrer.

Example 26: binder composition (U) 93.6 parts by mass of magnesium chloride hexahydrate _(MgCl 2 _· 6H 2 O) by mixing and dissolving 6.4 parts by weight was 100 parts by caking Agent composition (W) (containing 3% by mass of magnesium chloride in terms of anhydride).
Example 27: caking was made by mixing and dissolving 3.52 parts by mass of barium chloride dihydrate (BaCl ₂ .2H ₂ O) in 96.48 parts by mass of the binder composition (U). Agent composition (X) (containing 3% by mass of barium chloride in terms of anhydride).
Example 28: Binder composition (Y) (chlorinated) which was prepared by mixing and dissolving 3.0 parts by mass of zinc chloride (ZnCl ₂ ) in 97.0 parts by mass of binder composition (U). Containing 3% by weight of zinc).

[Comparative Example 7]
1.0 mass part of binder composition (U) and 0.4 mass part of hardening | curing agent were added with respect to 100 mass parts of silica sand, and it knead | mixed with the Shinagawa type universal stirrer, and kneaded sand was obtained.
A part of the kneaded sand obtained was filled into a test piece production wooden mold under the same conditions as in Example 1 and cured, and the test piece was taken out after 30 minutes from the start of curing (molding time 30 minutes).
Therefore, the compressive strength and bulk density of the obtained test pieces after 30 minutes, 1 hour, 3 hours and 24 hours from the start of curing were measured. The results are shown in Table 7.

In Comparative Example 7 and Examples 25 to 28, a binder composition having a nitrogen atom content of 1.8% by mass with respect to the total amount of the acid curable resin and water is used.
Here, from Table 7 and FIG. 7, the compressive strength after 30 minutes and the compressive strength after 24 hours in Examples 25 to 28 using the binder composition mixed with metal chloride are both metal It is clearly higher than Comparative Example 7 using a binder composition in which no chloride is mixed, and it can be said that the effect of improving the strength of the mold is obtained.
Therefore, even when the nitrogen atom content relative to the total amount of the acid curable resin and water is 1.8% by mass, the effect of improving the initial strength and final strength of the mold can be obtained by using the binder composition of the present invention. It can be said.
In addition, Examples 3 to 6 in Table 2 using the binder composition having a nitrogen atom content of 3.5% by mass with respect to the total amount of the acid curable resin and water, and the total of the acid curable resin and water. Comparing with Examples 25 to 28 in Table 7 using the binder composition having a nitrogen atom content of 1.8% by mass relative to the amount, the compressive strength (initial strength) after 30 minutes is the nitrogen atom content Examples 25 to 28 in Table 7 tended to be higher, and the compressive strength after 24 hours tended to be higher in Examples 3 to 6 in Table 2 having a higher nitrogen atom content.

Application of a mold forming binder composition capable of obtaining a sufficiently strong mold without complicating the manufacturing process, and application of a mold manufacturing method using the mold forming binder composition Is possible.

Claims

Contains acid curable resin, water, and metal chloride,
The acid curable resin is one or more of a condensate or a cocondensate of one or more selected from the group consisting of furfuryl alcohol, phenols and urea and an aldehyde, and furfuryl alcohol. Including
The binder composition for mold making, wherein the metal is an alkaline earth metal and / or a zinc group element.
A step of mixing a binder composition for mold making according to claim 1, a refractory granular material and a curing agent to obtain kneaded sand;
A method for producing a mold, comprising the steps of filling kneaded sand into a mold for mold making and curing the binder composition for mold making.
The method for producing a mold according to claim 2, wherein the refractory granular material is alumina sand.