JPH06179044A - Binder composition for gas curing casting mold and production of casting mold - Google Patents

Abstract

PURPOSE:To provide the binder compsn. for production of a gas curing casting mold having an excellent collapsing property. CONSTITUTION:This binder compsn. for the gas curing casting mold contains a binder consisting of a furan resin which can be cured by blowing sulfur dioxide of a gaseous state, etc., in the presence of a peroxide and a decay accelerator consisting of trialkyl ester of phosphoric acid or triaryl ester of phosphoric acid The number of carbon atoms of the alkyl group in the trialky ester of phosphic acid are 1 to 20. The number of carbon atoms of the aryl group in the triaryl ester of phosphic acid are 6 to 20. The binder cures and the gas curing casting mold is obtd. if the peroxide and the binder compsn. for the gas curing casting mold are added and kneaded to and with refractory aggregate and sulfur dioxide of the gaseous state, etc., is blown thereto. The decay accelerator acts on the furan resin of the gas curing type to accelerate the deterioration of the furan resin, thereby improving the collapsing property of the gas curing casting mold.

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 producing a gas-curing mold, and more particularly to a binder composition comprising a furan-based resin which can be gas-cured by injecting sulfur dioxide in the form of gas or aerosol. The present invention relates to a binder composition containing a binder. The present invention also relates to a method for producing a mold using this binder composition (so-called Hardox method).

[0002]

2. Description of the Related Art A gas hardening mold is generally disintegrated in order to separate a casting from a casting mold after pouring cast iron or the like into a casting. Conventionally, when casting is obtained using cast iron, since the pouring temperature is high, the gas hardening mold is exposed to this high temperature molten metal, the hardening binder deteriorates, and the gas hardening mold easily collapses. We were able to. However, when an aluminum casting is obtained by using aluminum having a low pouring temperature, the gas hardening mold is not exposed to a high temperature, and the hardening binder is hard to deteriorate. Therefore, in order to separate the casting from the mold, the mold is heat-treated at a high temperature for a long time to deteriorate the binder, and then the mold is disintegrated. However, heat treatment at a high temperature for a long time to disintegrate the mold is wasteful in terms of cost and labor.

Therefore, in a heat-curing mold of a type different from the gas-curing mold, specifically, in a heat-curing mold manufactured by the shell mold method using a phenolic resin as a binder, the following proposals have been made. Has been done. That is, by using as a binder a melt of 10 to 50 parts by weight of a phosphoric acid ester with respect to 100 parts by weight of a phenolic resin, the disintegration property of the obtained heat-curing mold is improved, and long-term heating at high temperature is achieved. It has been proposed to eliminate the need for heat treatment over time (Japanese Patent Publication No. 61-2454).

However, this method has a drawback that the preparation of the binder is complicated. That is, it was necessary to melt the phenolic resin and add the melted or softened phosphoric ester to the binder to adjust the binder. In addition, when an aluminum casting is obtained, the phenolic resin is adjusted in this way, and when a casting other than the aluminum casting is obtained, the phenolic resin is not adjusted. It was necessary to prepare some type of phenolic resin.

On the other hand, the following proposals have been made for self-hardening molds of different types from gas-curing molds. That is, it has been proposed that a binder obtained by modifying furfuryl alcohol with urea and formaldehyde is kneaded with a phosphoric acid ester to improve the disintegration property of the obtained self-hardening mold (Japanese Patent Application Laid-Open No. 2004-242242). 58-50151).

In this method, it is only necessary to add and knead the phosphate ester to the binder, and the binder can be easily adjusted. However, the furfuryl alcohol is modified with urea and formaldehyde, and it can be applied only to a binder that is self-hardening and made of a specific furan resin, and has a drawback that it is poor in versatility.

[0007]

Therefore, the inventors of the present invention have made various studies by changing the type of mold, the type of binder, the type of phosphoric acid ester, etc. There was found. That is, it was found that, by adding and kneading the phosphoric acid triester to the furan-based resin used as the binder of the gas-curing mold, the disintegration property of the obtained gas-curing mold was improved, The invention was reached.
Therefore, according to the present invention, in order to promote the disintegration of the above-mentioned heat-curing mold, the complicated work such as melting the phosphoric acid ester in the phenolic resin is unnecessary, and the disintegration of the self-hardening mold is eliminated. As when improving
It became unnecessary to strictly control the type of the binder, and it became possible to apply it to a gas-curing mold using a furan-based resin in a versatile and convenient manner.

[0008]

Means for Solving the Problems That is, the present invention relates to a binder made of a furan resin which can be cured by blowing sulfur dioxide in the form of gas or aerosol in the presence of a peroxide, and a binder represented by the following general formula: The present invention relates to a binder composition for a gas curing mold, characterized by containing a disintegration accelerator represented by (1). Moreover, it is related with the method of obtaining a gas hardening mold using this binder composition.

[Chemical 2] (In the formula, R is an alkyl group having 1 to 20 carbon atoms or 6 to 20 carbon atoms.
Represents an aryl group of. )

As a furan resin which can be cured by blowing a gaseous or aerosol form of sulfur dioxide in the presence of a peroxide, a known furan resin which has been conventionally used for producing a gas curing mold is used. Can be used. The furan-based resin referred to here is a resin containing at least part of furfuryl alcohol or modified furfuryl alcohol. As the modified furfuryl alcohol, furfuryl alcohol modified with formaldehyde (formaldehyde modified furan resin), furfuryl alcohol modified with urea (urea modified furan resin), furfuryl alcohol modified with phenol (phenol modified furan). Resins), furfuryl alcohol modified with melamine (melamine-modified furan resins), etc. can be used. Then, the furan-based resin functions as a binder by being heated and cured by blowing in a gaseous or aerosol form of sulfur dioxide.

The disintegration accelerator contained in the binder composition according to the present invention together with this binder accelerates the disintegration property of the obtained gas-curing mold, and has the above general formula ( It is represented by 1). Specifically, trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, trixylyl phosphate, trilauryl phosphate, tricetyl phosphate, tristearyl phosphate, etc. can be used. , Triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate are preferably used.

The binder composition can be cured by blowing sulfur dioxide in the form of gas or aerosol in the presence of peroxide. As a peroxide,
An organic peroxide such as a ketone type or aromatic type can be used. Specific examples of the ketone-based organic peroxide include peroxides of aliphatic ketones having 3 to 8 carbon atoms or 6 to 1 carbon atoms.
Examples thereof include peroxides of alicyclic ketone of 0. Such a ketone peroxide is obtained by oxidizing aliphatic ketone or the like with hydrogen peroxide in the presence of an acid catalyst. Further, this ketone peroxide is rarely used alone, and is often used in the form of a composition stabilized with a diluent stabilizer (carrier agent) such as phthalic acid ester.

In the binder composition for gas curing molds according to the present invention, the proportion of the disintegration accelerator is preferably 2 to 15 parts by weight per 100 parts by weight of the binder. When the amount of the disintegration promoter is less than 2 parts by weight, it tends to be difficult to improve the disintegration property of the obtained template. On the other hand, even when the amount of the disintegration promoter exceeds 15 parts by weight, the improvement of the disintegration property of the obtained template tends to be saturated. Further, the amount of the peroxide used when curing the binder composition is preferably 5 to 60 parts by weight with respect to 100 parts by weight of the binder. If the amount of peroxide is less than 5 parts by weight, it tends to be impossible to obtain a mold having sufficient strength. On the other hand, even if the amount of the peroxide exceeds 60 parts by weight, the improvement of the mold strength tends to be saturated.

To a refractory granular aggregate such as silica sand, the peroxide and the binder composition according to the present invention are added and kneaded, and gaseous or aerosol sulfur dioxide is blown to cure the binder. If so, a gas curing mold can be obtained. Further, to the refractory granular aggregate, a binder, a peroxide and a disintegration accelerator are separately added and kneaded, and by blowing in a gaseous or aerosol form of sulfur dioxide, the binder is cured,
A gas cure mold may be obtained. At this time, the refractory granular aggregate 10
The amount of the binder added to 0 parts by weight is preferably about 0.5 to 3.0 parts by weight. If the amount of the binder is less than 0.5 part 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 in the mold strength tends to be saturated.

[0014]

【Example】

Examples 1 to 8 and Comparative Examples 1 and 2 First, the compositions containing the binder and the disintegration accelerator shown in Table 1 were prepared. And ACI sand from Australia
17 parts by weight of this composition and 5.1 parts by weight of methyl ethyl ketone peroxide were added to 1000 parts by weight and kneaded to obtain a sand mixture. After filling this sand mixture into a 50 mmφ × 50 mmh cylindrical model, SO ₂ (sulfur dioxide) gas was blown in for 1 second and pressurized air was blown for 5 seconds to cure the binder and obtain a cylindrical core. It was

[0015]

[Table 1]

The disintegration rate of the core thus obtained was measured by the following measuring method. That is, the obtained core is 24
After being left for a period of time, this 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 for about 3 hours, the aluminum foil was peeled off, the core was shaken on a 5 mesh sieve for 5 minutes, and the weight of the remaining core was measured. Then, the disintegration rate (%) = [(core weight before shaking-core weight after shaking) / core weight before shaking] × 100 was used to calculate the disintegration rate. The results are shown in Table 1.

As is clear from the results shown in Table 1, the gas-curing molds according to Examples 1 to 8 obtained by using the binder composition containing the disintegration accelerator such as triethyl phosphate were triethyl phosphate. It can be seen that the disintegration property is excellent as compared with the gas-curing molds according to Comparative Examples 1 and 2 obtained by using the binder containing no disintegration accelerator.

[0018]

As described above, a binder composed of a furan resin that can be cured by blowing gaseous sulfur or aerosol sulfur dioxide in the presence of a peroxide, and a binder represented by the general formula (1) Containing a disintegration accelerator, the obtained gas curable mold composition using the binder composition for gas curing mold according to the present invention, deterioration of the gas-cured binder by the action of the disintegration accelerator. Since it can be promoted, it has an effect of being excellent in disintegration. That is, when the binder composition according to the present invention is used, it is possible to satisfactorily disintegrate the gas-curing mold without performing heat treatment at high temperature for a long time, for example, by simply performing heat treatment for a short time. Therefore, the high energy and labor required in the past can be saved. Therefore, when obtaining an aluminum casting in which the binder is less likely to deteriorate, the cost and labor required for collapsing the gas hardening mold can be significantly reduced, and the production cost of the aluminum casting can be reduced. is there.

Claims (2)

[Claims] 1. A binder comprising a furan-based resin which can be cured by blowing gaseous or aerosol sulfur dioxide in the presence of peroxide, and a disintegration accelerator represented by the following general formula (1): A binder composition for a gas-curing mold, which comprises: [Chemical 1] (In the formula, R is an alkyl group having 1 to 20 carbon atoms or 6 to 20 carbon atoms.
Represents an aryl group of. ) 2. A gas after kneading a refractory granular aggregate, a peroxide, a binder made of a furan-based resin, and a disintegration accelerator represented by the general formula (1) according to claim 1. A method for producing a mold, wherein the binder is gas-cured by injecting sulfur dioxide in the form of aerosol or aerosol.