JP3123032B2 - Binder 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 used for manufacturing a mold, and more particularly to a binder composition capable of improving the disintegration of a mold. The present invention also relates to a method for producing a mold using the binder composition.

[0002]

2. Description of the Related Art A casting mold is generally collapsed in order to separate a casting from a casting mold after pouring cast iron or the like into a casting. Conventionally, when castings are obtained using cast iron, since the pouring temperature is high, the mold is exposed to this high-temperature molten metal, the hardened binder deteriorates, and the mold can easily collapse. Was. However, when an aluminum casting is obtained by using aluminum having a low pouring temperature, the mold is not exposed to high temperatures, and the hardened binder may not easily deteriorate. Therefore, in order to separate the casting and the mold, the mold is subjected to heat treatment at a high temperature for a long time to deteriorate the binder, and thereafter, the mold is collapsed.

However, in order to break the mold,
Prolonged heat treatment at high temperature is wasteful in terms of cost and labor. For this reason, it has been proposed to include a halogen-containing organic compound such as tetrabromobisphenol A or dibromopentyl glycol in a binder composition for producing a mold (Japanese Patent Publication No. 60-39450). The mold obtained using this binder composition is excellent in disintegration, but has the following disadvantages. That is, a mold containing a halogen-containing organic compound emits a halogen gas at the time of pouring, gives off a bad smell and deteriorates the working environment, and when a mold is used as a main mold, the mold has a halogen. In some cases, gas contact caused rust-like corrosion.

[0004] On the other hand, the following proposals have been made regarding a heat-curable mold manufactured by a shell mold method using a phenolic resin as a binder. That is,
Phosphate ester is added to 100 parts by weight of phenolic resin.
It has been proposed that by using 0 to 50 parts by weight of a melted binder as a binder, the disintegration property of the obtained heat-cured mold is improved, and a long-time heat treatment at a high temperature becomes unnecessary. (Japanese Patent Publication No. 61-2454).

This method is satisfactory in terms of disintegration of the heat-curable mold, but has a drawback that the preparation of the binder is complicated. That is, the binder must be adjusted by melting the phenolic resin and adding the melted or softened phosphate ester thereto. In addition, when obtaining an aluminum casting, such adjustment is performed on the phenolic resin, and when obtaining a casting other than the aluminum casting, such adjustment is not performed on the phenolic resin. It was necessary to prepare various types of phenolic resins.

It is also known to add and mix a phosphate ester to a furan-based resin in order to improve the disintegration of a self-hardening mold using a specific furan-based resin (Japanese Patent Laid-Open No. 58-50151). Gazette). However, this method relates to a case where a self-hardening furan-based resin obtained by modifying furfuryl alcohol with urea and formaldehyde is used as a binder, and is used for a heat-curable furan-based resin and other resins. There is no disclosure of

[0007]

Accordingly, the present inventors have conducted various studies in an attempt to use other compounds different from conventionally known halogen-containing organic compounds and phosphoric acid esters as disintegration accelerators. As a result, it has been found that, if a specific monocarboxylic acid ester or dicarboxylic acid ester is added to the binder and kneaded, it shows good disintegration properties with respect to the self-hardening mold and the heat-curable mold, and the present invention. It has arrived.

[0008]

That is, the present invention relates to a compound represented by the general formula: R ₁ COOR _{2 wherein} R ₁ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, It represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and R ₂ represents an alkyl group having 1 to 4 carbon atoms. Or a general formula R ₃ (COOR ₂ ) _{2 wherein} R ₂ represents an alkyl group having 1 to 4 carbon atoms, and R ₃ represents an alkylene group having 1 to 20 carbon atoms and 2 to 20 carbon atoms. A phenylene group having 6 to 20 carbon atoms, or an aralkylene group having 7 to 20 carbon atoms. ] Is added to a self-hardening or heat-curable binder to produce a binder composition for mold production. The present invention also relates to a method for producing a mold using the binder composition.

The disintegration accelerator used in the present invention is a compound comprising a monocarboxylic acid ester or a dicarboxylic acid ester represented by the above-mentioned general formula. Specifically, butyl acetate, ethyl acetate, butyl stearate, benzoic acid Butyl acrylate, dibutyl sebacate, dibutyl maleate, coconut fatty acid methyl ester, dimethyl phthalate, dimethyl succinate, dimethyl adipate, dimethyl azelate, dimethyl dodecanedioate, and the like can be preferably used. The monocarboxylic acid ester or dicarboxylic acid ester used in the present invention has a certain chain length of the hydrocarbon, but if the chain length of the hydrocarbon is too long, the compatibility with the binder becomes poor, It is not preferable because the disintegration of the template is reduced. This disintegration accelerator can be used by adding to and mixing with either a self-hardening binder made of a furan-based resin or a thermosetting binder.

As the self-hardening binder, a furan resin can be used. As the heat-curable binder, a furan-based resin applied to a so-called warm box method, a resol-based or novolak-based phenol resin applied to a so-called shell mold method, an unsaturated polyester-based resin applied to a so-called shell mold method Resin or the like can be used. Here, the furan-based resin includes furfuryl alcohol (furan resin), furfuryl alcohol modified with formaldehyde (formaldehyde-modified furan-based resin), furfuryl alcohol modified with urea (urea-modified furan-based resin), and phenol-modified And a furfuryl alcohol (a phenol-modified furan-based resin), a furfuryl alcohol modified with a melamine (a melamine-modified furan-based resin), and the like.

The above binder and disintegration accelerator are added and mixed to obtain the binder composition for producing a mold according to the present invention. The mixing ratio of the binder and the disintegration promoter can be an appropriate ratio depending on the type of the binder and the like, but generally speaking, 2 to 15 parts by weight based on 100 parts by weight of the binder Part is preferred. When the amount of the disintegration promoter is less than 2 parts by weight, the disintegration of the obtained template tends to be difficult to improve. On the other hand, even if the amount of the disintegration promoter exceeds 15 parts by weight, the disintegration of the obtained mold tends to be improved in a saturated state.

A self-hardening mold is obtained by using the binder composition according to the present invention as follows. That is, a hardener such as xylene sulfonic acid is added to a binder composition comprising a self-hardening binder made of a furan-based resin and a disintegration accelerator, followed by mixing with a refractory granular bone such as silica sand. Add to the material and knead. Then, by filling the kneaded material in the model and curing the binder, a self-hardening mold can be obtained.

To obtain a heat-curable mold, a desired curing agent is added to and mixed with a binder composition comprising a heat-curable binder and a disintegration accelerator. In the present invention, it is preferable to use a curing agent comprising a salt of a strong acid and a weak base. As the strong acid, a conventionally known strong acid can be used. In particular, benzenesulfonic acid, phenolsulfonic acid, toluenesulfonic acid, xylenesulfonic acid, and lower alkylsulfonic acid are preferably used alone or in combination. . On the other hand, as the weak base, a conventionally known weak base can be used. In particular, a weak base having at least one metal atom selected from the group consisting of aluminum, copper, zinc and iron can be used alone or in combination. It is preferable to use them. Then, an acidic salt obtained by reacting the above-described strong acid with a weak base serves as a curing agent. After adding and mixing this curing agent or another curing agent, it is added and kneaded to a refractory granular aggregate such as silica sand. Then, if the kneaded material is filled into the model and subjected to a heat treatment, the binder is cured and a heat-cured mold can be obtained.

When manufacturing a self-hardening mold, the curing agent is
It is preferable to add and mix about 10 to 70 parts by weight with respect to 100 parts by weight of the binder. When producing a heat-curable mold, the curing agent is preferably used in an amount of 5 to 70 parts by weight based on 100 parts by weight of the binder. If the amount of the curing agent is smaller than the above-mentioned amount, there is a tendency that a mold having sufficient strength cannot be obtained. On the other hand, even when the amount of the curing agent is larger than the above-mentioned amount, there is a tendency that the improvement of the mold strength is saturated.

When the mold is manufactured, the amount of the binder to be used is 0.5 to 3 to 100 parts by weight of the refractory granular aggregate.
About 0 parts by weight is preferable. If the amount of the binder is less than 0.5 parts by weight, the strength of the mold tends to be insufficient. Further, even if the amount of the binder exceeds 3.0 parts by weight, the improvement of the mold strength tends to be saturated. In the above, after adding and mixing the binder composition and the hardener, it was added and kneaded with the refractory granular aggregate to produce a mold, but the refractory granular aggregate, the binder, It goes without saying that a mold may be produced by separately adding and kneading the disintegration accelerator and the curing agent.

[0016]

【Example】

Examples 1 to 8, Comparative Examples 1 and 2 First, a binder composition containing a binder and a disintegration promoter shown in Table 1 was prepared. And Australian ACI
18 parts by weight of this composition and 5.4 parts by weight of a curing agent solution were added to and kneaded with 1000 parts by weight of sand to obtain a sand mixture.
In addition, Kao Lightener TK-3 manufactured by Kao Quaker Co., Ltd. was used as the curing agent solution. The sand mixture obtained as described above was filled in a wooden mold of 50 mmφ × 50 mmh to obtain a columnar core.

[0017]

[Table 1]

The decay rate of the core obtained as described above was measured by the following measuring method. That is, the obtained core is 24
After leaving for a period of time, the core was wrapped in aluminum foil, placed in an electric furnace, and left at 700 ° C. for 20 minutes. Then, after cooling to room temperature over about 3 hours, the aluminum foil was peeled off, and the core was shaken on a 5-mesh sieve for 5 minutes to measure the weight of the remaining core. Then, the disintegration rate (%) = [(core weight before shaking-core weight after shaking) / core weight before shaking] x 100 was used to calculate the disintegration rate. The results are shown in Table 1.

As is clear from the results in Table 1, the self-hardening molds according to Examples 1 to 8 obtained by using the binder compositions containing a disintegration accelerator such as butyl acetate, etc. It can be seen that, compared to the self-hardening molds according to Comparative Examples 1 and 2, which were obtained using a binder containing no, excellent in disintegration property.

Examples 9 to 16 and Comparative Examples 3 and 4 First, a binder composition containing a binder and a disintegration promoter shown in Table 2 was prepared. And Australian silica sand 10
18 parts by weight of the composition and a curing agent solution with respect to 00 parts by weight
5.4 parts by weight were added and kneaded to obtain a sand mixture. The curing agent solution used was composed of 40% by weight of toluenesulfonic acid-copper salt, 40% by weight of methanol and 20% by weight of water. The sand mixture obtained as described above was blown into a vertical mold making machine for a furan warm box at an air pressure of 4.0 kg / cm ^{2 and} baked at a curing temperature of 200 ° C. for 30 seconds. And 50m
A cylindrical core of mφ × 50 mmh was obtained.

[0021]

[Table 2]

The decay rate of the core obtained as described above was measured in the same manner as in Example 1. The results are shown in Table 2.

As is clear from the results in Table 2, the heat-curable molds according to Examples 9 to 16 obtained by using the binder compositions containing a disintegration accelerator such as butyl acetate, It can be seen that the heat-curable molds according to Comparative Examples 3 and 4, which were obtained using a binder containing no, had excellent disintegration properties.

[0024]

As described above, as described above, a self-hardening or heat-curing binder is added to a compound represented by the general formula R ₁ COOR ₂ [wherein R ₁
Is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having a carbon number of 2-20, an aryl group having 6 to 20 carbon atoms, or carbon atoms shows an aralkyl group of 7 to 20, R ₂ is carbon Number is 1-4
Represents an alkyl group. Or a general formula R ₃ (COOR ₂ ) ₂
[Wherein, R ₂ represents an alkyl group having 1 to 4 carbon atoms;
₃ represents an alkylene group having 1 to 20 carbon atoms, an alkenylene group having 2 to 20 carbon atoms, a phenylene group having 6 to 20 carbon atoms, or an aralkylene group having 7 to 20 carbon atoms. The mold obtained by using the binder composition containing the disintegration accelerator represented by the formula (1) can promote the deterioration of the binder hardened by the action of the disintegration accelerator, and thus has excellent disintegration properties. This has the effect. That is, if the binder composition according to the present invention is used, even if a high-temperature and long-time heat treatment is not performed, for example, only a short-time heat treatment is performed, the self-hardening mold or the heat-curable mold can be favorably formed. It can be disintegrated, and has the effect of saving the high energy and labor conventionally required. Therefore, when obtaining an aluminum casting in which the binder hardly deteriorates, the cost and labor required for disintegrating the mold can be significantly reduced, and the production cost of the aluminum casting can be reduced.

Claims (8)

(57) [Claims] 1. A binder comprising a furan resin and a general formula R ₁ COOR _{2 wherein} R ₁ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, It represents an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and R ₂ represents an alkyl group having 1 to 4 carbon atoms. Or a general formula R ₃ (COOR ₂ ) _{2 wherein} R ₂ represents an alkyl group having 1 to 4 carbon atoms, and R ₃ represents an alkylene group having 1 to 20 carbon atoms and 2 to 20 carbon atoms. A phenylene group having 6 to 20 carbon atoms, or an aralkylene group having 7 to 20 carbon atoms. A binder composition for producing a self-hardening mold, comprising a disintegration accelerator represented by the formula: 2. A self-hardening mold, which comprises kneading a refractory granular aggregate, a hardener, a binder, and the disintegration promoter according to claim 1 and then curing the binder. Manufacturing method. 3. A binder curable with a curing agent comprising a salt of a strong acid and a weak base, and a general formula R ₁ COOR _{2 wherein} R ₁ is
An alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or 7
And R ₂ represents an alkyl group having 1 to 4 carbon atoms. Or a general formula R ₃ (COOR ₂ ) _{2 wherein} R ₂ represents an alkyl group having 1 to 4 carbon atoms, and R ₃ represents an alkylene group having 1 to 20 carbon atoms and 2 to 20 carbon atoms. A phenylene group having 6 to 20 carbon atoms, or an aralkylene group having 7 to 20 carbon atoms. And a disintegration accelerator represented by the formula (1): 4. The binder composition according to claim 3, wherein the curing agent comprises a salt of a strong acid and a weak base. 5. The method according to claim 5, wherein the salt of the strong acid and the weak base is at least one strong acid selected from the group consisting of benzenesulfonic acid, phenolsulfonic acid, toluenesulfonic acid, xylenesulfonic acid and lower alkylsulfonic acid, and aluminum,
The binder composition according to claim 4, which is a salt with a weak base having at least one metal atom selected from the group consisting of copper, zinc and iron. 6. After kneading a refractory granular aggregate, a curing agent, a binder curable by heating with the curing agent, and the disintegration accelerator according to claim 3, the binder is heat-cured. A method for producing a heat-curable mold. 7. The method for producing a heat-curable mold according to claim 5, wherein the curing agent comprises a salt of a strong acid and a weak base. 8. A salt of a strong acid and a weak base, wherein at least one strong acid selected from the group consisting of benzenesulfonic acid, phenolsulfonic acid, toluenesulfonic acid, xylenesulfonic acid and lower alkylsulfonic acid, and aluminum,
7. The method for producing a heat-curable mold according to claim 6, which is a salt with a weak base having at least one metal atom selected from the group consisting of copper, zinc and iron.