JPH06210392A - Binder composition for casting mold and production of casting mold - Google Patents

Abstract

PURPOSE:To provide the binder compsn. for the casting mold capable of producing the casting mold having a less degradation rate of high compressive strength even if sand temp. falls or the amt. of a hardener is small. CONSTITUTION:This binder compsn. for the casting mold contains a phenol- aldehyde modified resin as an essential component. This phenol-aldehyde modified resin is obtd. by ternary cocondensation polymn. of phenols, bisphenols and aldehydes. Phenol, resorcinol, nonyl phenol, etc., are used alone or in combination as the phenols. Bisphenol A, bisphenol E, bisphenol Z, etc., are used alone or in combination as the bisphenols. Formaldehyde, paraformaldehyde, furfural and glyoxal are used alone or in combination as the aldehyde compd. This binder compsn. for the casting mold and refractory granular material are kneaded and the casting mold is obtd. by a desired method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder composition used in the production of molds, which prevents the resulting mold from being deteriorated in strength even when the sand temperature is low, and uses a curing agent in a small amount. The present invention relates to a binder composition capable of improving mold strength even when the amount is small. Also, using this binder composition,
The present invention relates to a method for manufacturing a mold.

[0002]

2. Description of the Related Art Conventionally, a mold is prepared by filling a model with kneading sand obtained by kneading a refractory granular material and a binder composition, and then curing the binder in the binder composition. Being manufactured. As the binder, various curable resins such as furan resin, water-soluble phenol resin, urethane resin, etc. are used. Among them, the water-soluble phenolic resin is known to be capable of preventing deterioration of the working environment at the time of producing a self-hardening or gas-curing mold since it is cured with an organic ester or carbon dioxide gas (Japanese Patent Laid-Open No. 50-130627). Japanese Patent Publication, Japanese Patent Publication No. 61-43132, Japanese Patent Publication No. 61-37022).
The water-soluble phenol resin referred to here is an alkaline phenol-formaldehyde resin, which is obtained by polycondensing phenol and formaldehyde in the presence of an alkali, or by polycondensing and then adding an alkali. However, when a binder composition containing this alkaline phenol-formaldehyde resin and a refractory granular material are kneaded to produce a mold, compared to the case where a binder composition containing a furan resin is used. As a result, there is a problem that the strength of the obtained mold is low.

Therefore, it has been proposed to use bisphenol instead of phenol and use a phenolic resin obtained by polycondensing bisphenol and formaldehyde as a binder (Japanese Patent Laid-Open No. 62-40948). JPA
63-40636). The bisphenol referred to here is one in which bisphenol A, bisphenol F, bisphenol C, or the like is used alone. Therefore, the obtained phenolic resin is one obtained by binary condensation polymerization of bisphenol and formaldehyde.

The mold obtained by using this bisphenol-formaldehyde binary polycondensation resin can improve its strength to some extent, but it has not been sufficiently satisfactory. That is, when the temperature (sand temperature) of the refractory granular material to be kneaded with this resin is high, the obtained mold strength is sufficiently satisfactory, but when the sand temperature is low, the mold strength decreases. It had a serious drawback. Further, even when the amount of the curing agent used is reduced, there is a drawback that the obtained mold strength is significantly lowered.

[0005]

Therefore, the inventors of the present invention have made it possible to reduce the strength of the obtained mold even when the sand temperature is low and the amount of the curing agent used is small. Various studies were conducted to obtain a drug composition. As a result, not the binder obtained simply by the binary condensation polymerization of bisphenols and formaldehyde, but the binder of the phenolic resin obtained by the ternary copolycondensation of phenols with a specific bisphenol and an aldehyde compound. The present inventors have found that, when used as an agent, even if the sand temperature is low and the amount of the curing agent used is small, the decrease in strength of the obtained mold can be suppressed, and the present invention has been accomplished.

[0006]

Means for Solving the Problems That is, the present invention provides a binder composition for a template containing a phenol-aldehyde-modified resin as a main component, wherein the phenol-aldehyde-modified resin contains phenols and the following general formula ( The present invention relates to a binder composition for a template, which is obtained by copolycondensing a bisphenol represented by 1) and an aldehyde compound. The present invention also relates to a method for producing a mold using the binder composition for a mold.

[Chemical 2]

In the binder composition for a mold according to the present invention,
It mainly contains a phenol-aldehyde modified resin. The phenol-aldehyde-modified resin is obtained by copolycondensing phenols, the bisphenols represented by the above general formula (1), and an aldehyde compound. Phenols include compounds represented by the following general formula (2), compounds represented by the following general formula (3),
Alternatively, the compounds represented by the following general formula (4) are used alone or in combination.

[0008]

[Chemical 3] (In the formula, R ₅ and R ₆ represent a hydrogen atom or a hydrocarbon group having 2 or less carbon atoms.)

[Chemical 4] (In the formula, R ₇ represents a hydrogen atom, a hydroxyl group or a hydrocarbon group having 2 or less carbon atoms.)

[Chemical 5] (In the formula, R ₈ represents an aliphatic hydrocarbon group having 3 or more carbon atoms or an aromatic hydrocarbon group.)

Among the phenols, specific examples of the compound represented by the general formula (2) include phenol, cresol and 3,5-xylenol. Specific examples of the compound represented by the general formula (3) include resorcinol and catechol. Further, specific examples of the compound represented by the general formula (4) include nonylphenol and P-tert.
-Butylphenol, isopropenylphenol, phenylphenol, etc. may be mentioned.

Specific examples of the bisphenols represented by the general group (1) include bisphenol A, bisphenol F, bisphenol C, bisphenol E, bisphenol Z, bisphenol S, bisphenol AF, bisphenol AP, di-sec-butyl-bisphenol. A, J
-Isopropyl-bisphenol A, 1,1-ethylidene-bisphenol, methyl-ethyl-methylene-bisphenol, methyl-isobutyl-methylene-bisphenol, methyl-hexyl-methylene-bisphenol, methyl-phenyl-methylene-bisphenol, 4,4 ' -Thiodiphenol and the like are used, and they are used alone or in a mixture. As the aldehyde compound, formaldehyde, paraformaldehyde, furfural, glyoxal, etc. are used alone or in combination.

When phenols, bisphenols and aldehyde compounds are copolycondensed, the molar ratio of each compound is preferably as follows. That is, the ratio of the number of moles of the aldehyde compound to the total number of moles of the phenols and the number of moles of the bisphenols is 1.0 to 5.0.
[(Mol number of phenols + mol number of bisphenols): mol number of aldehyde compound = 1: 1.0 to 5.0] is preferable. In particular, the molar ratio of the aldehyde compound is more preferably 1.5 to 3.0. When the molar ratio of the aldehyde compound is less than 1.0, there is a tendency that the strength of the mold is not sufficiently improved even when molding is performed using the obtained phenol-aldehyde modified resin. On the contrary, when the molar ratio of the aldehyde compound exceeds 5.0, the aldehyde odor of the obtained phenol-aldehyde modified resin is strong and the working environment may be deteriorated. The ratio of the number of moles of bisphenols to the number of moles of phenols is 0.00
About 1 to 1000 is preferable. In particular, it is more preferable that the molar ratio of bisphenol is 0.01 to 90. When the number of moles of bisphenol is less than 0.001 or exceeds 1000, the strength of the obtained mold tends not to be sufficiently improved.

Copolycondensation of phenols, bisphenols and aldehyde compounds is generally carried out in an aqueous solution to obtain a phenol-aldehyde modified resin. For example, it is preferable that a predetermined amount of an aldehyde compound is gradually added to an aqueous solution in which a predetermined amount of phenols and bisphenols are dissolved, and copolycondensation is performed. At this time, it is preferable to use potassium hydroxide (KOH) as a reaction catalyst. Since the phenol-aldehyde modified resin in the present invention is adjusted to an alkaline aqueous solution, a predetermined amount of potassium hydroxide may be used in the copolycondensation polymerization, or a minimum amount of potassium hydroxide may be used as a reaction catalyst. Then, after the copolycondensation is completed, a predetermined amount of potassium hydroxide may be added. Further, after the copolycondensation is finished, sodium hydroxide (NaOH) or lithium hydroxide (LiOH) may be used together with potassium hydroxide so as to have a predetermined alkalinity. Furthermore, after the copolycondensation is carried out using an acid catalyst, the copolycondensation may be then proceeded using an alkali catalyst such as potassium hydroxide. In the alkaline aqueous solution of the phenol-aldehyde modified resin, the ratio of the total alkali moles to the total moles of the phenolic hydroxyl groups and the bisphenol hydroxyl groups is preferably 0.2 to 1.2. The concentration of the phenol-aldehyde modified resin in the alkaline aqueous solution is preferably 30 to 75% by weight.

The binder composition for a mold according to the present invention mainly contains a phenol-aldehyde modified resin, but the following substances may be contained as other substances. For example, a silane coupling agent is preferably contained in order to further improve the strength of the obtained template. As the silane coupling agent, various conventionally known ones can be used. In particular, γ
-Glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, N-glycidyl-N, N-
Bis [3- (trimethoxysilyl) propyl] amine or the like can be used.

Further, in the binder composition for a template according to the present invention, various surfactants such as nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants, or urea and urea compounds By containing an organic nitrogen compound such as an amide compound, it is possible to improve the fluidity of the kneading sand kneaded with the refractory granular material and the filling property into the model. Furthermore, when reclaimed sand is used as the refractory granular material, the strength of the resulting mold is obtained by including various polyvalent metal salts such as calcium chloride and aluminum oxide in the binder composition for the mold. Can be further improved.

To manufacture a mold using the binder composition for a mold according to the present invention, a self-hardening mold molding method or a gas-curable mold molding method is generally employed. As a specific example of the self-hardening mold making method, 0.1 to 5 parts by weight of an organic ester is added and kneaded to 100 parts by weight of the refractory granular material. Subsequently, the binder composition for a mold according to the present invention is added in an amount of 0.4 to 15 parts by weight in the form of an alkaline aqueous solution, and kneaded again. A self-hardening mold can be obtained by filling a model with the thus obtained kneading sand and allowing it to stand and cure.
Further, as a specific example of the gas-curable mold making method, with respect to 100 parts by weight of the refractory granular material, the binder composition for a mold according to the present invention is 0.4 to 15 parts by weight in the form of an alkaline aqueous solution. And knead. The obtained kneaded sand is filled in a gas hardening model with pressurized air by blowing. Then, gaseous or aerosol organic ester 0.05-10
A gas-curable mold can be obtained by blowing in parts by weight and curing. As the organic ester used, alkyl formate having an alkyl group having 1 to 3 carbon atoms, preferably methyl formate can be used. Further, in the case of using a carbon dioxide gas instead of an organic ester in a gaseous state to cure the binder composition for a mold, an appropriate amount of boric acid, borate, or aluminate is contained in the binder composition. It is possible to cure the phenol-aldehyde modified resin by the addition of a compound having an oxyanion such as, and the synergistic action of the compound having an oxyanion and carbon dioxide gas.
4263 publication).

As the refractory granular material used for producing the mold, various conventionally known materials can be used, for example, silica sand containing quarts as a main component, chromite sand, zircon sand, olivine sand. , Alumina sand, mullite sand, synthetic mullite sand, etc. can be used. Also,
Needless to say, as the refractory granular material, it is also possible to use a material mainly composed of such recycled sand or recovered sand.

[0017]

【Example】

[Preparation of Caking Binder Composition Aqueous Solution 1] To a 50% aqueous potassium hydroxide solution, phenols and bisphenols in the amounts determined by the molar ratio shown in Table 3 were added, stirred and dissolved. While maintaining this solution at 80 ° C., an amount of the aldehyde compound determined by the molar ratio shown in Table 3 was gradually added.
Then, the reaction was continued at 80 ° C. until the weight average molecular weight of the phenol-aldehyde modified resin in the reaction solution reached 2500. The determination at the time when the weight average molecular weight reached 2500 was performed by measuring the viscosity of the reaction solution. After completion of the reaction, after cooling to room temperature, 50% aqueous potassium hydroxide solution is added so that the ratio of the number of moles of phenols to the total number of moles of bisphenols is 0.85. It was Thus, an alkaline aqueous solution of the phenol-aldehyde modified resin was obtained. Then, γ-glycidoxypropyltrimethoxysilane was added to 0.5 parts by weight of the aqueous solution with respect to 100 parts by weight of the aqueous solution. As described above, 10 types of binder composition aqueous solutions for molds were prepared. The content of the binder composition (phenol-aldehyde modified resin and silane coupling agent) in the aqueous binder composition solution was 50% by weight.

The item A in Table 3 is the ratio of the number of moles of the aldehyde compound to the total number of moles of phenols and bisphenols. That is, [aldehyde compound / (mol number of phenols + mol number of bisphenols)]. The item B is the ratio of the number of moles of bisphenols to the number of moles of phenols. That is, [moles of phenols /
The number of moles of bisphenols)]. Below, A in the table
And B are similar to this.

[Preparation of Binder Composition Aqueous Solution 2 for Template] The molar ratio of phenols, bisphenols and aldehyde compounds is set as shown in Table 1, and the weight of the phenol-aldehyde modified resin in the reaction solution is set. Except for continuing the reaction until the time when the average molecular weight reached 1800, 4 kinds of binder composition aqueous solutions 2 for templates were prepared by the same method as the binder composition aqueous solution 1 for templates.

[Preparation of Binder Composition Aqueous Solution 3 for Template] In preparing the binder composition aqueous solution 2 for a template, 25 parts by weight of an aqueous solution of a phenol-aldehyde modified resin obtained after the reaction is completed, Sodium borate decahydrate 5 parts by weight, 50%
By mixing with 5 parts by weight of potassium hydroxide, four types of aqueous binder composition solutions 3 for templates were obtained.

[Preparation of Binder Composition Aqueous Solution 4 for Mold] 50
%, And phenol was added to the potassium hydroxide aqueous solution and stirred to dissolve. While maintaining this solution at 80 ° C., formaldehyde was gradually added so that the ratio of the number of moles of phenol to the number of moles of phenol was 1.5. Then, the reaction was continued at 80 ° C. until the weight average molecular weight of the phenol-formaldehyde resin in the reaction solution reached 2500. After completion of the reaction, the mixture was cooled to room temperature, and 50% aqueous potassium hydroxide solution was added so that the ratio of the number of moles of potassium hydroxide to the number of moles of phenol was 0.85. Thus, an alkaline aqueous solution of phenol-formaldehyde resin was obtained. Then, γ-glycidoxypropyltrimethoxysilane was added to 0.5 parts by weight of the aqueous solution with respect to 100 parts by weight of the aqueous solution. As described above, one kind of binder composition aqueous solution for a mold was prepared. The content of the binder composition (phenol-formaldehyde resin and silane coupling agent) in the aqueous binder composition solution is 50% by weight.
Met.

[Preparation of Binder Composition Aqueous Solution 5 for Mold] 50
% Bisphenol A to a potassium hydroxide aqueous solution,
Stir to dissolve. While maintaining this solution at 80 ° C., formaldehyde was gradually added so that the ratio of the number of moles of bisphenol A was 3.0. And
The reaction was continued at 80 ° C. until the weight average molecular weight of the bisphenol A-formaldehyde resin in the reaction solution reached 2500. After completion of the reaction, the mixture was cooled to room temperature, and 50% aqueous potassium hydroxide solution was added so that the ratio of the number of moles of potassium hydroxide to the number of moles of bisphenol A was 0.85. Thus, an alkaline aqueous solution of bisphenol A-formaldehyde resin was obtained. And
γ-Glycidoxypropyltrimethoxysilane was added to 0.5 parts by weight of the aqueous solution based on 100 parts by weight of the aqueous solution.
As described above, one kind of binder composition aqueous solution for a mold was prepared. The content of the binder composition (bisphenol A-formaldehyde resin and silane coupling agent) in the aqueous binder composition solution was 50% by weight.

[Preparation of Caking Binder Composition Aqueous Solution 6] Aqueous Binder Composition Aqueous Solution 4 except that the reaction was continued until the weight average molecular weight of the phenol-formaldehyde resin in the reaction solution reached 1800. In the same way as
A seed binder solution aqueous solution 6 was prepared.

[Preparation of Binder Composition Aqueous Solution 7 for Template] Aqueous binder composition aqueous solution for templates except that the reaction was continued until the weight average molecular weight of the bisphenol A-formaldehyde resin in the reaction solution reached 1800. In the same manner as in 5, one type of binder composition aqueous solution 7 for a mold was prepared.

[Preparation of Binder Composition Aqueous Solution 8 for Template] When preparing the binder composition aqueous solution 6 for a template, an aqueous solution of a phenol-formaldehyde resin obtained after completion of the reaction 25
Parts by weight, 5 parts by weight of sodium tetraborate decahydrate, 50
% Potassium hydroxide (5 parts by weight) was mixed to obtain one kind of binder composition aqueous solution 8.

[Preparation of Binder Composition Aqueous Solution 9 for Template] In preparing the binder composition aqueous solution 7 for a template, 25 parts by weight of an aqueous solution of bisphenol A-formaldehyde resin obtained after completion of the reaction, and 5 parts by weight of sodium borate decahydrate and 5 parts by weight of 50% potassium hydroxide were mixed to obtain one kind of binder composition aqueous solution 8.

Examples 1 to 4 To 100 parts by weight of silica sand (sand temperature of 10 ° C. or 35 ° C.) which is a refractory granular material, 2.0 parts by weight of each of the four types of aqueous binder composition aqueous solutions 2 prepared in advance is prepared. And knead,
Four types of kneaded sand were obtained. Each kneaded sand was filled in a 50mmφ × 50mmh gas test piece frame, and 100 parts by weight of silica sand was used.
1.2 parts by weight of methyl formate was injected, and a mold was molded by a gas-curable mold manufacturing method. Then, the compressive strength (kg / cm ² ) of this mold after 24 hours was measured. The results are shown in Table 1. The rate of decrease in compressive strength was also measured, and the results are shown in Table 1. The decrease rate of the compressive strength is [(compressive strength of the mold after 24 hours at sand temperature of 35 ° C-sand temperature at 10 ° C
Compressive strength of the mold after 24 hours) / 24 at sand temperature 35 ° C
The compressive strength of the mold after the passage of time] × 100. The reduction rate of the compression strength in Table 2 is also calculated by this formula.

Comparative Examples 1 to 4 Instead of the binder binder aqueous solution 2, the binder binder aqueous solution 6 (Comparative Example 1), the binder binder composition 7 (Comparative Example 2), A template was obtained in the same manner as in Example 1 except that a mixed aqueous solution of the binder composition aqueous solutions 6 and 7 (Comparative Examples 3 and 4) was used. Then, using this mold, the compression strength (kg / cm ² ) and the like of the obtained mold after 24 hours were measured in the same manner as in Example 1. The results are also shown in Table 1.

[0029]

[Table 1]

Examples 5 to 8 To 100 parts by weight of silica sand (sand temperature of 10 ° C. or 35 ° C.) which is a refractory granular material, 3.0 parts by weight of each of the four types of aqueous binder composition aqueous solutions 3 prepared in advance was prepared. And knead,
Four types of kneaded sand were obtained. Fill each kneaded sand into a 50 mmφ x 50 mmh gas test piece frame, and add 10 liters of carbon dioxide gas
Aeration was performed at a flow rate of 2 minutes for 2 minutes, and a mold was molded by a gas-curable mold manufacturing method. Then, in the same manner as in Example 1, 24
The compressive strength (kg / cm ² ) and the like after the passage of time were measured. The results are shown in Table 2. In addition, in Table 2, the types of bisphenols and the like are described as in Table 1.

Comparative Examples 5 to 8 Instead of the binder binder aqueous solution 3 for casting, a binder binder aqueous solution 8 (Comparative Example 5) and a binder binder aqueous solution 9 (Comparative Example 6). , And a binder binder aqueous solution 8 and 9
A template was obtained in the same manner as in Example 5 except that the mixed aqueous solution (No. 3) (Comparative Examples 7 and 8) was used. Then, using this mold, the compression strength (kg / c
m ² ) etc. were measured in the same manner as in Example 1. The results are also shown in Table 2.

[0032]

[Table 2]

Examples 9 to 18 To 100 parts by weight of silica sand (sand temperature: 25 ° C.), which is a refractory granular material, triacetin, which is a curing agent, was added in an amount shown in Table 3 and kneaded. Subsequently, 10 kinds of the previously prepared aqueous solution 1 of the binder composition for casting molds were added and kneaded so as to be 1.5 parts by weight, respectively, to obtain 10 kinds of kneading sand. 50 mmφ x each kneading sand
The test piece frame of 50 mmh was filled and the mold was formed by the self-hardening mold manufacturing method. Then, the compressive strength (kg / cm ² ) and the like of this mold after 24 hours were measured in the same manner as in Example 1. The results are shown in Table 3. However, the rate of decrease in compressive strength is calculated by the formula [(compressive strength of the mold when the amount of the curing agent is large-the compressive strength of the mold when the amount of the curing agent is small) / the compression strength of the mold when the amount of the curing agent is large] x 100 It is calculated. The reduction rate of the compression strength in Tables 4 to 6 was also calculated by this formula.

[0034]

[Table 3]

Comparative Examples 9 to 12 Instead of the binder binder aqueous solution 1 for casting, an aqueous binder composition aqueous solution 4 (Comparative Example 9) and an aqueous binder composition aqueous solution 5 (Comparative Example 10). A template was obtained in the same manner as in Example 9, except that a mixed aqueous solution of the binder binder aqueous solutions 4 and 5 (Comparative Examples 11 and 12) was used. Then, using this mold, the compression strength (kg / cm) of the obtained mold after 24 hours has passed
² ) etc. were measured in the same manner as in Example 1. The results are shown in Table 4.

[0036]

[Table 4]

Examples 19 to 22 Four kinds of aqueous solution of binder composition for molds prepared in advance for 100 parts by weight of silica sand (sand temperature is 35 ° C.) which is a refractory granular material.
Was added and kneaded so as to be 2.0 parts by weight, respectively, to obtain four kinds of kneading sand. Each kneaded sand was filled in a 50 mmφ × 50 mmh gas test piece frame, and Table 5 was used for 100 parts by weight of silica sand.
The amount of methyl formate shown in (4) was injected, and a mold was formed by the gas-curable mold manufacturing method. Then, the compression strength (kg / cm ² ) and the like of this mold after 24 hours were measured. The results are shown in Table 5.
It was shown to. In addition, in Table 5, the types of bisphenols and the like are described as in Table 1.

Comparative Examples 13 to 16 In place of the binder binder aqueous solution 2, the binder binder aqueous solution 6 (Comparative Example 13), the binder binder composition 7 (Comparative Example 14), A template was obtained in the same manner as in Example 19 except that a mixed aqueous solution of the binder binder aqueous solutions 6 and 7 (Comparative Examples 15 and 16) was used. Then, using this mold, the compression strength (kg / cm ² ) and the like of the obtained mold after 24 hours were measured in the same manner as in Example 1. The results are also shown in Table 5.

[0039]

[Table 5]

Examples 23 to 26 100 parts by weight of silica sand (sand temperature of 35 ° C.), which is a refractory granular material, was prepared in advance with 4 kinds of aqueous binder composition aqueous solutions for molds 3
Were added so that each of them was 3.0 parts by weight and kneaded to obtain 4 kinds of kneaded sand. Each kneading sand was filled in a 50 mmφ × 50 mmh gas test piece frame, and carbon dioxide gas was aerated at a flow rate of 10 liters / minute and for the time (minutes) shown in Table 6, and a mold was prepared by the gas-curable mold manufacturing method. Was molded. Then, in the same manner as in Example 1, the compression strength (kg / cm ² ) and the like of the mold after 24 hours were measured. The results are shown in Table 6. In addition, in Table 6, the types of bisphenols and the like are described as in Table 2.

Comparative Examples 17 to 20 Instead of the binder binder aqueous solution 3 for casting, a binder binder aqueous solution 8 (Comparative Example 17) and a binder binder aqueous solution 9 (Comparative Example 18) , And a binder binder aqueous solution 8 and 9
A template was obtained in the same manner as in Example 23, except that the mixed aqueous solution of Comparative Example 19 (Comparative Examples 19 and 20) was used. Then, using this mold, the compression strength (kg / c
m ² ) etc. were measured in the same manner as in Example 1. The results are also shown in Table 6.

[0042]

[Table 6]

As is clear from the results shown in Tables 1 and 2, a phenol-aldehyde modified resin obtained by terpolymerizing three kinds of compounds of phenols, bisphenols and aldehyde compounds as a main component of the binder composition is used. If a mold is produced by using it, a phenol-formaldehyde resin obtained by binary condensation polymerization of one phenol or one bisphenol and formaldehyde, a bisphenol-formaldehyde resin, or a mixture thereof is used as a binder composition. It can be seen that the compression strength of the obtained mold is improved as compared with the case where it is used as the main component. Further, it can be seen that the decrease rate of the compressive strength of the obtained mold is reduced due to the decrease of the sand temperature. Therefore, the molds obtained by the methods according to Examples 1 to 8 have higher compressive strength values than the molds obtained by the methods according to Comparative Examples 1 to 8 The rate of decline is also low. In addition, as is clear from the results of Tables 3 to 6, when the aqueous binder composition solution for a template according to the example was used, when the aqueous binder composition solution for a template according to the comparative example was used. In comparison, it can be seen that even if the amount of the curing agent is reduced, the reduction rate of the compressive strength of the obtained mold is small. Therefore, Examples 9 to
The mold obtained by the method according to 26 can obtain a mold with high compressive strength even when the amount of the curing agent is smaller than that obtained by the method according to Comparative Examples 9 to 20. .

[0044]

As described above, the binder composition for a mold according to the present invention, which mainly contains a specific phenol-aldehyde-modified resin, is used and kneaded with a refractory granular material to form a mold. If obtained, the compressive strength of the mold can be improved as compared with the case of using a conventional resin containing mainly a phenol-formaldehyde resin and / or a bisphenol-formaldehyde resin.
Therefore, if casting is performed using a mold obtained by using the binder composition for a mold according to the present invention, the surface of the mold is unlikely to be corroded during pouring, and a casting of excellent quality can be obtained. Produce an effect.

Further, by using the binder composition for a mold according to the present invention, a mold having a high compressive strength can be obtained even when the sand temperature of the refractory granular material is low and the amount of the curing agent is small. be able to. Therefore, it is possible to avoid heating and refining the refractory granular material before manufacturing the mold, and the manufacturing process of the mold can be simplified. In addition, the energy to heat the refractory particulate material may be eliminated or reduced. Furthermore, since the amount of the curing agent can be reduced, the cost required for the curing agent can be reduced. Therefore, if the binder composition for a mold according to the present invention is used, it is possible to rationalize the production of the mold.

Claims (4)

[Claims] 1. A binder composition for a template containing a phenol-aldehyde-modified resin as a main component, wherein the phenol-aldehyde-modified resin comprises phenols, bisphenols represented by the following general formula (1), and aldehydes. A binder composition for a template, which is obtained by copolycondensation with a compound. [Chemical 1] 2. The binder composition for a mold according to claim 1, wherein the ratio of the number of moles of the aldehyde compound to the total number of moles of the phenols and the bisphenols is 1.0 to 5.0. 3. The ratio of the number of moles of bisphenols to the number of moles of phenols is 0.001 to 1000.
Alternatively, the binder composition for a mold according to item 2. 4. A method for producing a mold, which comprises using the binder composition for a mold according to claim 1, 2, or 3 and using an organic ester and / or carbon dioxide gas as a curing agent.