JP2784715B2 - Binder composition for mold production, sand composition for mold production, and method for producing mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder composition and a sand composition which can be suitably used especially for producing a self-hardening mold. The present invention also relates to a method for producing a mold using the sand composition.

[0002]

2. Description of the Related Art Conventionally, a self-hardening mold is prepared by adding a binder made of an acid-curable resin such as furfuryl alcohol and a curing agent such as phosphoric acid or benzenesulfonic acid to a refractory granular material such as silica sand. Thereafter, the kneaded sand is filled in a mold, and the binder is cured to produce the mixture. In such a conventional method, the initial strength of the mold is generally low because the curing speed of the binder is low. When the initial strength of the mold is low, it takes time to remove the mold from the mold, and there is a disadvantage that the effective use of the mold is hindered.

For this reason, a sulfonic acid compound having a relatively high acid strength has been used as a curing agent for curing the binder, or the amount of the curing agent used has been increased. However, with this approach,
In some cases, the final mold strength was too high to make the mold difficult to collapse. When the mold collapse becomes difficult, it becomes difficult to apply the conventional mold collapse process, or it becomes difficult to remove the binder attached to the surface of the sand, and the mold sand cannot be regenerated rationally. there were. In addition, when the type and amount of the curing agent are changed, there is a disadvantage that the binder starts to be cured when kneading sand is obtained, thereby shortening the pot life of the kneading sand.

[0004] Under such circumstances, attempts have been made to change the binder itself, instead of changing the type of the curing agent. For example, Japanese Patent Application Laid-Open No. 56-56753 proposes that furfuryl alcohol contain a mononuclear phenol, a dinuclear phenol, and a resole-type phenol formaldehyde resin containing almost no methylolated product. I have. When a resol-type phenol formaldehyde resin containing almost no such low-molecular-weight resin is used as one of the binders, the time required for increasing the molecular weight can be omitted, and the initial template strength can be improved.

[0005]

The present invention also aims at increasing the initial strength of the mold by changing the binder, instead of changing the kind of the curing agent. However, unlike the above-mentioned JP-A-56-56753, instead of changing the binder itself, by adding a special compound in the binder, the binder when contacting with the curing agent is added. It is intended to increase the curing speed and thereby increase the initial strength of the mold.

[0006]

That is, the present invention relates to a binder composition for producing a mold mainly comprising a binder composed of an acid-curable resin, wherein the binder composition comprises: General formula (1)
Wherein 0.5 to 63.0% by weight of a curing accelerator comprising one or more of the compounds represented by formula (1) is contained. The present invention also relates to a sand composition for producing a mold using the binder composition for producing a mold. The present invention also relates to a method for producing a mold using the sand composition for producing a mold.

Embedded image (In the formula, X ₁ and X ₂ represent any of H, CH _{3 and} C ₂ H _5. )

The binder composition for producing a mold according to the present invention comprises:
It comprises a binder composed of an acid-curable resin and a curing accelerator. The curing accelerator is composed of one or more compounds represented by the general formula (1). That is, 2,5-
Bishydroxymethylfuran, 2,5-bismethoxymethylfuran, 2,5-bisethoxymethylfuran, 2-hydroxymethyl-5-methoxymethylfuran, 2-hydroxymethyl-
5-ethoxymethylfuran and 2-methoxymethyl-5-ethoxymethylfuran are used alone or in combination as a curing accelerator. In particular, it is preferable to use 2,5-bishydroxymethylfuran as a curing accelerator. 2,
5-Bishydroxymethylfuran has a higher reactivity than 2,5-bismethoxymethylfuran or 2,5-bisethoxymethylfuran and accelerates the curing reaction of a binder composed of an acid-curable resin. is there. The reason for the high reactivity of 2,5-bishydroxymethylfuran is that the hydroxyl group contributes to the curing reaction. That is, in the case of 2,5-bismethoxymethylfuran or the like, methoxymethyl ether is once hydrolyzed to generate a hydroxyl group and then contributes to the curing reaction, so that the accelerating action of the curing reaction is slightly inferior. It is known that when furfuryl alcohol is reacted with formaldehyde to obtain a furan resin, 2,5-bishydroxymethylfuran is produced as an initial condensate (see the book "Introduction to Polymer Drugs", Sanyo Kasei Kogyo Co., Ltd.), it has not been known that this 2,5-bishydroxymethylfuran has a function of accelerating the curing of an acid-curable resin used in the production of a mold.

The curing accelerator is contained in the binder composition for producing a mold in an amount of 0.5 to 63.0% by weight. In particular, it is preferable that the curing accelerator is contained at 1.8 to 50.0% by weight, and it is more preferable that the curing accelerator is contained at 2.5 to 50.0% by weight. More preferably, the curing accelerator is contained in an amount of 5.0 to 40.0% by weight, and most preferably, the curing accelerator is contained in an amount of 7.0 to 40.0% by weight. If the amount of the curing accelerator is less than 0.5% by weight, the curing reaction of the binder is not sufficiently promoted, and the initial strength of the mold is not improved to a satisfactory degree, which is not preferable. Conversely, if the amount of the curing accelerator exceeds 63.0% by weight, the amount of the binder becomes relatively small, and the curing accelerator becomes difficult to dissolve in the binder,
Precipitation occurs in the binder composition for producing a mold, which is not preferable.

[0009] The binder composition for producing a mold contains an acid-curable resin as a binder. As the acid-curable resin, a conventionally known resin is used. These resins are used alone or in combination as a binder. Specific examples of the acid-curable resin include furfuryl alcohol, furfuryl alcohol /
Aldehyde polycondensates, phenols / aldehyde polycondensates, melamine / aldehyde polycondensates, urea / aldehyde resin polycondensates, etc. are used alone or in combination. Further, those obtained by further co-condensing two or more of these polycondensates can also be used as the acid-curable resin. Aldehydes polycondensed with furfuryl alcohol and the like include formaldehyde, glyoxal,
Conventionally known aldehyde compounds such as furfural can be used. In particular, in the present invention, it is preferable to use formaldehyde.

When a phenol / aldehyde polycondensate is used as the acid-curable resin, phenols such as phenol, resorcinol, bisphenol A,
Bisphenol F, a compound represented by the following general formula (2),
A conventionally known phenol compound such as a compound represented by the following general formula (3) can be used alone or in combination.

Embedded image (In the formula, R ₁ represents any of a hydrocarbon group having 1 to 10 carbon atoms.)

Embedded image (In the formula, R ₂ and R ₃ represent any of hydrocarbon groups having 1 to 10 carbon atoms.) The phenol / aldehyde polycondensate is prepared by charging a phenol monomer at a ratio of 2 to 40% by weight. That is, it is preferable that the phenolic monomer is prepared at a charge amount of 2 to 40% by weight. Therefore, the resulting phenols /
The reduced amount of the phenolic monomer in the binder composed of the aldehyde polycondensate is also preferably 2 to 40% by weight. Phenolic monomer content (converted amount) is 2
When the amount is less than the weight percentage, the curing reaction of the binder is relatively slow, and the initial strength of the obtained mold tends to decrease. Conversely, the phenolic monomer content (converted amount) is 40
If the amount is more than 10% by weight, the viscosity of the binder composition for producing a mold tends to increase, and the storage stability tends to decrease.

When a urea / aldehyde polycondensate is used as the acid-curable resin, it is preferable to contain urea bonded to the aldehyde in a certain ratio. That is, in the binder composition for producing a mold, it is preferable to use an amount of urea in which nitrogen atoms derived from urea are contained in a ratio of 0.1 to 6.0% by weight, and particularly, nitrogen atoms in an amount of 0.1 to 4.5%. It is more preferred to use the amount of urea contained in the proportion by weight. When a urea / aldehyde polycondensate containing this amount of urea is used as the acid-curable resin, the final strength of the resulting mold tends to be improved. If the amount of urea used is such that the proportion of nitrogen atoms is less than 0.1% by weight, the final strength of the resulting mold will not tend to improve. Conversely, if the amount of urea used is such that the proportion of nitrogen atoms exceeds 6.0% by weight, castings such as pinholes tend to occur in castings made using this mold.
In addition, although the case where the urea / aldehyde polycondensate is used as the acid-curable resin has been described here, the case where another acid-curable resin is used is also used in the binder composition for mold production. , A nitrogen atom derived from urea is
It is preferable to use one contained at a ratio of 0.1 to 6.0% by weight.

Further, the binder composition for producing a mold according to the present invention preferably contains 0.5 to 30% by weight of water. More preferably, the water content is 15.5 to 25% by weight. This water content is for lowering the viscosity of the binder composition for producing a mold and making it easier to use.
When the water content is less than 0.5% by weight, the viscosity of the binder composition for producing a mold tends to not decrease. Conversely, if the water content exceeds 30% by weight, the curing reaction of the acid-curable resin is inhibited, and the initial strength of the mold tends not to be sufficiently improved.

The binder composition for producing a mold according to the present invention comprises:
An acid-curable resin such as furfuryl alcohol and the general formula (1)
And a curing accelerator consisting of the compound represented by the formula: In addition, when producing an acid-curable resin such as furfuryl alcohol, a compound represented by the general formula (1) is produced at the same time, and as a result, a mold is produced in which the acid-curable resin and a curing accelerator are mixed. A binder composition for use may be obtained. Further, even when moisture is contained in the binder composition for producing a mold, the moisture may be added later, or the moisture may be produced simultaneously with the production of the acid-curable resin.

In order to produce a mold using the binder composition for producing a mold according to the present invention, it is generally preferable to produce the mold by the following method. That is, first, the binder composition for mold production according to the present invention and a curing agent for curing the binder composition for mold production according to the present invention are blended with the refractory granular material, and kneaded to form a sand for mold production. Obtain the composition. As the refractory granular material, conventionally known ones such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand containing quartz as a main component can be used. As the curing agent, conventionally known phosphorus compounds and sulfonic acid compounds can be used. In particular, in the present invention, it is preferable to use a phosphorus-based compound such as phosphoric acid, condensed phosphoric acid, a phosphoric acid ester, and a phosphate salt alone or in combination. The reason is as follows. That is, such a curing agent composed of a phosphorus-based compound has a lower acid strength and a lower curing speed as compared with a curing agent composed of a sulfonic acid-based compound, but generates less harmful gas at the time of pouring, which is favorable. This is because a working environment can be obtained.
The reason why the curing speed is low is that it does not become a particularly serious problem because the curing speed of the binder composition for producing a mold according to the present invention itself is improved. Still, yet, furthermore,
When it is desired to increase the curing rate, it is preferable to use a phosphorus-based compound having an excellent working environment, and a sulfonic acid-based compound and / or sulfuric acid having a high acid strength and capable of increasing the curing rate.

The thus obtained sand composition for producing a mold can be generally produced by a self-hardening molding method. That is, a mold can be obtained by filling a predetermined mold with the sand composition for producing a mold, and curing the mixed and kneaded binder composition for producing a mold by the action of a curing agent. The binder composition for mold production according to the present invention has a relatively high curing speed, and after the mold composition is filled with the sand composition for mold production, the mold can be sufficiently removed after about 30 minutes to 1 hour.
A high quality casting can be manufactured by pouring into the mold.

[0016]

【Example】

Examples 1 to 12 and Comparative Examples 1 to 3 For furfuryl alcohol (acid-curable resin), Table 1
-Accelerator shown by-Aldrich Fine Chemical Co., Ltd .: 2,5-Furandimethanol [1883-75-6] (CAS registration number)-
Was added and mixed to prepare a binder composition for mold production containing a curing accelerator in the ratio shown in Table 1. Then, 1 part by weight of the binder composition for mold production and 0.45 part by weight of a curing agent (aqueous solution of 70% toluenesulfonic acid) were added to 100 parts by weight of Kaketsu flotation silica sand and kneaded, and the mixture was kneaded. A composition was obtained. Immediately thereafter, the sand composition for mold production was
A test piece frame of φ × 50 mmh was filled, and a test mold was obtained at 25 ° C. by a self-hardening mold molding method. Then, after the sand composition for mold production was obtained and filled in the test piece frame, the compressive strength of the test mold after 1 hour and 24 hours had been measured. The results are shown in Table 1.

[0017]

[Table 1]

As is evident from the results in Table 1, when the binder composition for producing a mold to which a curing accelerator was added was used, the strength of the mold after one hour had elapsed and after 24 hours had elapsed. It can be seen that the strength of the casting mold also becomes higher. And
It can be seen that as the content of the curing accelerator is gradually increased from 0.5% by weight, the strength of each mold gradually increases. At this time, the maximum value is reached when the curing accelerator is contained at 50% by weight, and when the curing accelerator is further increased, the strength of each mold gradually decreases, and when it exceeds 65% by weight, the viscosity for mold production increases. It can be seen that the binder composition becomes non-uniform. When the amount of the curing accelerator is less than 0.5% by weight,
It can be seen that the strength of each mold does not improve much.

Examples 13 to 24 and Comparative Examples 4 to 6 Example 1 was repeated except that an equal weight mixture of a 70% aqueous solution of toluenesulfonic acid and 85% phosphoric acid was used as the curing agent.
Test molds were prepared as in # 12. Then, the compressive strength of this mold was measured and shown in Table 2.

[0020]

[Table 2]

As is evident from the results in Table 2, when the binder composition for producing a mold to which a curing accelerator was added was used, the strength of the mold after one hour had passed, and after 24 hours had passed. It can be seen that the strength of the casting mold also becomes higher. And
It can be seen that when the amount of the curing accelerator is gradually increased from 0.5% by weight, the strength of each mold also gradually increases. At this time, the maximum value is obtained when the curing accelerator is added at 40% by weight, and the strength of each mold gradually decreases as the curing accelerator is further increased. It can be seen that the binder composition becomes non-uniform. When the amount of the curing accelerator is less than 0.5% by weight,
It can be seen that the strength of each mold does not improve much.

Preparation of Binder Compositions 1 to 15 for Mold Production Furfuryl alcohol alone, or furfuryl alcohol and furfuryl alcohol / aldehyde polycondensate, phenols / aldehyde polycondensate, melamine / aldehyde polymer Preparing a mixture with a resin selected from the group consisting of a condensate and a urea / aldehyde polycondensate as a binder;
Binder compositions 1 to 15 for the production of molds were prepared comprising the amounts of the binder and the curing accelerator shown in Tables 3 and 4. The amounts of each binder, moisture, cure accelerator and other materials are given in weight percent in the composition. In addition, the nitrogen content is the weight percentage of the nitrogen atom with respect to all the atoms in the composition.
This is a measure of the amount of urea in the composition.

The binder such as furfuryl alcohol / aldehyde polycondensate is produced by the following method. [Preparation of Furfuryl Alcohol / Formaldehyde Polycondensate] By a conventional method, furfuryl alcohol and formaldehyde were reacted under acidic conditions for a predetermined time to obtain a furfuryl alcohol / formaldehyde polycondensate. [Preparation of phenol / aldehyde polycondensate] According to a conventional method, a phenol and an aldehyde (formaldehyde or furfural) are reacted for a predetermined time under basic conditions, and after completion of the reaction, neutralized with paratoluenesulfonic acid aqueous solution.
A phenol / aldehyde polycondensate was obtained. [Adjustment of melamine / formaldehyde polycondensate] According to a conventional method, melamine and formaldehyde are reacted under a basic condition for a predetermined time, and after the reaction is completed, the mixture is neutralized with paratoluenesulfonic acid aqueous solution to obtain a melamine / formaldehyde polycondensate. Obtained. [Preparation of urea / aldehyde polycondensate] Urea and aldehydes (formaldehyde or glyoxal) are allowed to react with each other for a predetermined period of time under basic conditions according to a conventional method.
Neutralization was performed with an aqueous solution of p-toluenesulfonic acid to obtain a urea / aldehyde polycondensate.

[0024]

[Table 3]

[0025]

[Table 4]

In the present invention or in the table, the content (quantity ratio) of each component in the binder composition for producing a mold is shown.
Is measured as follows. [Content of compound represented by general formula (1) such as furfuryl alcohol and 2,5-bishydroxymethylfuran] The content was measured by gas chromatography. The gas chromatography conditions are as follows. That is, equipment used: GC-14A manufactured by Shimadzu Corporation, column used: PEG-20M chromosorb
WAW DMCS 10% 60/80 mesh 0.5m × 3mmφ, detector: FI
D, carrier gas: He. [Water content] It was measured by the Karl Fischer method. [Content of phenol monomer equivalent amount (prepared amount) such as phenol] The content was measured by an ultraviolet absorption altimeter. [Nitrogen content] It was measured by the Kjeldahl method.

Examples 25 to 36 Test molds were produced in the same manner as in Examples 1 to 12, except that the above-mentioned binder compositions 1 to 15 for producing a mold were used.
Then, the compressive strength of this mold was measured and shown in Table 5.

[0028]

[Table 5]

As is clear from Table 5, although there is variation depending on the type of the binder, when the binder composition for producing a mold containing a predetermined amount of 2,5-bishydroxymethylfuran is used, The initial strength of the relatively obtained mold was high, and the strength of the mold after 24 hours had passed was satisfactory. On the other hand, if 2,5-bishydroxymethylfuran is not contained, or is contained in a very small amount, the initial strength of the mold is low and the passage of 24 hours Later mold strength was also unsatisfactory.

Examples 37 to 48 and Comparative Example 10 A curing accelerator shown in Table 6 was added to a furfuryl alcohol / formaldehyde polycondensate containing 0.3% of hydroxymethylfuran and mixed. A test mold was produced in the same manner as in Examples 1 to 12, except that a binder composition for producing a mold containing a curing accelerator was used.
Then, the compressive strength of this mold was measured and shown in Table 6.

[0031]

[Table 6]

As is evident from the results in Table 6, when the binder composition for producing a mold to which a curing accelerator was added was used, the strength of the mold after 1 hour was increased, and after 24 hours. It can be seen that the strength of the casting mold also becomes higher. And
It can be seen that as the content of the curing accelerator is gradually increased from 0.5% by weight, the strength of each mold gradually increases. At this time, when the content of the curing accelerator is about 40% by weight, the maximum value is reached, and when the curing accelerator is further increased,
It can be seen that the strength of each mold gradually decreases. When the amount of the curing accelerator is less than 0.5% by weight, the strength of each mold is not improved much.

Examples 49-60 and Comparative Examples 11-13 Examples 1 to 60 were repeated except that 85% phosphoric acid was used as a curing agent.
A test mold was produced in the same manner as in 12. Then, the compressive strength of this mold was measured and shown in Table 7. Regarding the measurement of the compressive strength, these examples differ from Examples 1 to 12 only in that the compressive strength of the mold after 2 hours has passed is measured.

[0034]

[Table 7]

As is clear from the results in Table 7, when the binder composition for producing a mold to which a curing accelerator was added was used, the strength of the mold after 2 hours had passed, and after 24 hours had passed. It can be seen that the strength of the casting mold also becomes higher. And
It can be seen that when the amount of the curing accelerator is gradually increased from 0.5% by weight, the strength of each mold also gradually increases. At this time, the maximum value is obtained when the curing accelerator is added at 40% by weight, and the strength of each mold gradually decreases as the curing accelerator is further increased. It can be seen that the binder composition becomes non-uniform. When the amount of the curing accelerator is less than 0.5% by weight,
It can be seen that the strength of each mold does not improve much. Further, as is clear from the results in Table 7, the initial strength of the mold (strength after 1-2 hours has elapsed) when phosphoric acid is used as the curing agent is higher than when toluenesulfonic acid is used.
Becomes lower.

Examples 61 to 65 and Comparative Examples 14 to 16 Table 8 consisting of a binder comprising furfuryl alcohol, a mixture of furfuryl alcohol / formaldehyde polycondensate and urea / formaldehyde polycondensate, an effect promoter and the like. The binder composition for mold production shown was prepared, and the binder composition for mold production was prepared with respect to 100 parts by weight of regenerated furan.
0.8 parts by weight and curing agent (60% xylene sulfonic acid aqueous solution)
0.4 parts by weight were added and kneaded to obtain a sand composition for producing a mold.
Thereafter, a test mold was manufactured in the same manner as in Examples 1 to 12. Then, the compressive strength of this mold was measured and shown in Table 8.

[0037]

[Table 8]

As is evident from the results in Table 8, when the binder composition for producing a mold to which a curing accelerator was added was used, the strength of the mold after 1 hour had increased, and after 24 hours had elapsed. It can be seen that the strength of the casting mold also becomes higher. When the amount of water in the binder composition for producing a mold is too large (Comparative Example 16), the strength of the mold tends to be hardly increased.

[0039]

The binder composition for producing a mold according to the present invention contains:
It contains a predetermined amount of 2,5-bishydroxymethylfuran. The hydroxyl group of this 2,5-bishydroxymethylfuran is highly reactive, and when contacted with a curing agent such as phosphoric acid, the hydroxyl group or the methylol group of the binder in the binder composition undergoes a condensation reaction to form a binder. This has the effect of accelerating the curing speed. Further, the methoxy group or ethoxy group of 2,5-bismethoxymethylfuran or 2,5-bisethoxymethylfuran is
Upon contact with a curing agent such as phosphoric acid, it is hydrolyzed to be converted into a hydroxyl group, and has the effect of accelerating the curing speed of the binder as in the case of 2,5-bishydroxymethylfuran.

[0040]

Thus, it contains a compound represented by the general formula (1) such as 2,5-bishydroxymethylfuran.
When a mold is produced using the binder composition for producing a mold according to the present invention, the curing speed of the binder is increased, so that the initial strength of the mold is improved. Therefore, after filling the sand composition using the binder composition for mold production into a mold, the mold can be removed from the mold in a short time, and the productivity of the mold is improved by effective use of the mold. It has the effect of being able to do so. Further, the binder composition for producing a mold according to the present invention, by changing the composition of the composition itself, to accelerate the curing speed, or to increase the amount of the curing agent used, or It is less necessary to use a large amount of a curing agent having a high acid strength. Therefore, when obtaining or after obtaining a sand composition for mold production obtained by kneading a binder composition for mold production, a refractory granular material, and a curing agent, it is easily affected by a large amount or a high acid strength curing agent. Also, the effect that the hardening of the sand composition for mold production can be prevented from being shortened and the working life of the sand composition for mold production can be prevented from being shortened. Furthermore,
Since it is not necessary to use a large amount of a curing agent or to use a sulfonic acid-based curing agent having a high acid strength, it is possible to produce a mold in a favorable working environment.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B22C 1/00 B22C 1/22

Claims (18)

(57) [Claims] 1. A binder composition for producing a mold mainly comprising a binder comprising an acid-curable resin, wherein the binder composition comprises a compound represented by the following general formula (1): A binder composition for producing a mold, comprising 0.5 to 63.0% by weight of one or more curing accelerators. Embedded image (In the formula, X ₁ and X ₂ represent any of H, CH _{3 and} C ₂ H _5. ) 2. The binder composition for producing a mold according to claim 1, wherein the curing accelerator is contained in an amount of 1.8 to 50.0% by weight. 3. The binder composition according to claim 1, which contains 2.5 to 50.0% by weight of a curing accelerator. 4. The binder composition according to claim 1, which contains 5.0 to 40.0% by weight of a curing accelerator. 5. The binder composition for producing a mold according to claim 1, wherein the curing accelerator is contained in an amount of 7.0 to 40.0% by weight. 6. An acid-curable resin, furfuryl alcohol, furfuryl alcohol / aldehyde polycondensate,
A phenol / aldehyde polycondensate, a melamine / aldehyde polycondensate, and a urea / aldehyde resin polycondensate alone or in combination of two or more, or two or more selected from the above group The binder composition for producing a mold according to any one of claims 1 to 5, wherein a condensate is used. 7. The binder composition for producing a mold according to claim 6, wherein the aldehyde is selected from the group consisting of formaldehyde, glyoxal and furfural. 8. The binder composition for producing a mold according to claim 6, wherein formaldehyde is used as the aldehyde. 9. The method according to claim 1, wherein the phenol is selected from the group consisting of phenol, resorcinol, bisphenol A, bisphenol F, a compound represented by the following general formula (2) and a compound represented by the following general formula (3). Item 7. A binder composition for producing a mold according to Item 6. Embedded image (In the formula, R ₁ represents any of a hydrocarbon group having 1 to 10 carbon atoms.) (In the formula, R ₂ and R ₃ represent any of C 1 to C 10 hydrocarbon groups.) 10. The nitrogen content in the binder composition is 0.1
The binder composition for producing a mold according to any one of claims 1 to 9, wherein the amount is from 6.0 to 6.0% by weight. The nitrogen content in the binder composition is 0.1
11. The binder composition for producing a mold according to claim 10, wherein the amount is from 4.5 to 4.5% by weight. 12. The binder composition for producing a mold according to claim 6, wherein a phenol / aldehyde polycondensate obtained by charging 2 to 40% by weight of a phenol monomer and performing polycondensation is used as the acid-curable resin. Stuff. 13. The water content in the binder composition is 0.5
The binder composition for producing a mold according to any one of claims 1 to 12, wherein the amount is from 30 to 30% by weight. 14. The binder composition for producing a mold according to any one of claims 1 to 13, wherein the curing accelerator comprises 2,5-bishydroxymethylfuran. 15. A refractory granular material, a binder composition for producing a mold according to any one of claims 1 to 14, and curing for curing the binder composition for producing a mold. And a sand composition for producing a mold. 16. A phosphorus compound alone as a curing agent,
16. The sand composition for producing a mold according to claim 15, wherein a phosphorus compound and a sulfonic acid compound and / or sulfuric acid are mixed and used. 17. The sand composition for producing a mold according to claim 15, wherein a curing agent selected from the group consisting of phosphoric acid, condensed phosphoric acid, a phosphoric acid ester and a phosphate is used. 18. A binder composition for mold production, which is filled in a predetermined mold with the sand composition for mold production according to claim 15, 16 or 17, and is contained in the sand composition for mold production. And a method for producing a mold.