JPS5934457B2 - Mold manufacturing method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a mold.

Conventionally, to manufacture foundry molds, sand is mixed with various binders of inorganic or organic materials and molded.

In this case, each of these inorganic or organic binders has advantages and disadvantages.

For example, in the case of gas-type water glass, when the sand is discarded after use, the water glass stuck to the sand inlet gradually dissolves and alkaline substances are eluted, making the surrounding soil alkaline.

As a result, not only do plants wither away, but also organisms living in the soil and water die.

Thus, due to pollution problems, there is a demand for a foundry sand binder that can replace water glass.

As one solution to this problem, organic binders made from self-hardening furan or phenol are attracting attention, and such organic binders can remove organic substances by rubbing or burning sand after use. Sand can also be reused, but it produces a foul odor when burned.

Furthermore, the hardening speed of the binder and the mechanical strength of the mold vary considerably depending on factors such as the properties of the sand, water content, temperature, humidity, and the type and concentration of the acid used as a hardening agent, making handling difficult.

In addition, because polymerization proceeds during the storage period of the binder raw material, there was a runner-up in that it had to be consumed within one year after production.

The inventor of the present invention made extensive studies to create an organic foundry sand binder free from the above-mentioned drawbacks, and discovered that a water-soluble styrene-maleic acid copolymer has extremely good properties as a foundry sand binder. It is.

As a result of further study, it was found that when mixing styrene-maleic acid copolymer and silica sand, it is easier to work with lower viscosity.
The higher the viscosity of the compound obtained by mixing, the greater the resistance pressure during wetting and the less likely the mold will collapse. Therefore, it is possible to obtain a good mold by adding a water-soluble thickener to the silica sand in advance. This discovery led to the completion of the present invention.

That is, the gist of the present invention is a method for manufacturing a mold, which comprises adding water to a mixture of silica sand, a water-soluble thickener, and a water-soluble salt of a styrene-maleic acid copolymer and molding the mixture into a mold shape. A method for producing a mold is characterized in that an aqueous solution of a salt of a styrene-maleic acid copolymer is added to a mixture of silica sand and a water-soluble thickener, and the mixture is molded into a mold shape.

The water-soluble thickener used in the present invention has the ability to dissolve in water and thicken the aqueous solution, and generally a water-soluble polymer is used.

Examples of water-soluble polymers include water-soluble starch, gelatin, carboxymethyl cellulose, hydroxyethyl cellulose, dextrin, polyvinyl alcohol, and bot ethylene glycol.The water-soluble thickener is added to silica sand and mixed to form a compound. Since water or an aqueous solution of a styrene-maleic acid copolymer salt is added to impart a viscosity to the formulation, it is preferable that the composition has a high dissolution rate in water, is powdery, and has a small and uniform particle size.

Further, the amount of water-soluble thickener added is not particularly limited and varies depending on the type of thickener, but in general, 0.1 to 2.0 parts by weight is preferably used per 100 parts by weight of silica sand. .

The styrene-maleic acid copolymer used in the present invention is a copolymer of styrene and a maleic acid compound, and the maleic acid compound refers to maleic anhydride, maleic acid,
It is a general term for maleic acid esters, etc.

Any known method may be used to copolymerize styrene and a maleic acid compound. For example, styrene, a maleic acid compound, and a catalyst such as azobisisobutyronitrile are added to an organic solvent such as butyl acetate. A copolymerization reaction is carried out by heating to 95° C. for several hours, and after the reaction is completed, a styrene-maleic acid copolymer is obtained by removing with a solvent.

Depending on the physical properties required for the foundry sand binder, a part of the styrene-maleic acid copolymer may be added to methyl alcohol, ethyl alcohol, methyl alcohol, isobutyl alcohol, lauryl sulfol, or β-hydroxy methacrylate. Esterification may be performed with a compound having a hydroxyl group such as ethyl or β-hydroxypropyl acrylate.

Next, the styrene-maleic acid copolymer is reacted with an alkali to form a salt, and in the present invention, water-soluble salts are used. Examples include sodium hydroxide, potassium hydroxide, ammonia, ammonium compounds, and particularly sodium salts and ammonium salts are preferably used.

In the present invention, the above-mentioned salt is added and mixed with the silica sand together with a water-soluble thickener to form a compound, and the salt is added in contact with water, or an aqueous solution of the above-mentioned salt is prepared in advance and the aqueous solution is mixed with the silica sand to increase the water-solubility. It can be used in two ways: by being added to a mixture with a sticky agent, but in the first method, it is used in the form of a powder with small and uniform particle size. It is preferable because it is dispersed.

The amount of the salt added is not particularly limited, but o, i to 2.0 parts by weight are preferably used per 100 parts by weight of silica sand.

In addition, when it is added as an aqueous solution to a mixture of silica sand and a water-soluble thickener, if the viscosity of the aqueous solution is too high, it becomes difficult to mix, so the preferred viscosity is 1000-30000 centipoise, more preferably 3000 to 5000 centipoise. Therefore, although the concentration of the aqueous solution varies depending on the copolymer composition, the type of alkali, etc., an aqueous solution having a concentration of 5 to 20% by weight is generally suitably used.

The amount of the above aqueous solution added is 1 to 1 per 100 parts by weight of silica sand.
0 parts by weight is preferred.

In the present invention, as described above, a water-soluble thickener and a styrene-maleic acid copolymer salt are mixed and dispersed in silica sand and added to the water, or a water-soluble thickener is mixed and dispersed in silica sand, and then styrene-maleic acid is mixed and dispersed. A molding composition is obtained by adding an aqueous solution of a maleic acid copolymer salt.

Next, to mold a mold, the mold composition obtained as described above is injected into a mold-like mold, the mold is removed,
Dry and create a mold.

At this time, any known drying method may be used, such as placing the mold in a drying oven, blowing hot air on it, placing it in a high-frequency heater, leaving it to air dry after making the mold, etc. can give.

Next, molten metal or the like is poured into the completed mold, and after cooling, the mold is destroyed to obtain a casting.

In this case, any known method may be used to destroy the mold, and since the binder of the mold composition of the present invention is water-soluble, it can be immersed in water, and the mold simply collapses.

The structure of the present invention is as described above, and since the binder is made of a specific water-soluble polymer, this binder and an aqueous solution of the binder are very stable.
It does not change in any way even if it is left for years, and it has almost no odor or toxicity and is very easy to handle.

In addition, since an aqueous solution thickener is added to the silica sand in advance and then water or an aqueous solution of a salt of a styrene-maleic acid copolymer is added, the viscosity of water or the aqueous solution is low and can be easily mixed and dispersed uniformly. The mold thus obtained has uniform strength and has a high resistance pressure when wetted, making it difficult to collapse, making it easy to handle.

Furthermore, sand hardly sticks to the casting during manufacturing, and furthermore, the mold after manufacturing the casting can be immersed in water and disintegrated, so there is no dust generation and the working environment is improved.

In addition, the mold sand after destruction can be easily reused by washing with water, burning, etc., and SOx and NO are removed during casting and burning.
There is no generation of harmful gases such as x, HCL, etc.

Next, examples of the present invention will be described.

Note that the term "parts" below means "parts by weight."

Further, the counter pressure was measured according to JIS-Z-2604 foundry sand strength testing method.

Example 1 100 parts of silica sand, 1 part of powdered polyethylene oxide and powdered styrene-maleic acid copolymer (molecular weight 400
0. After adding 1 part of a sodium salt having an acid value of 170) and stirring and mixing thoroughly, 5 parts of water was added and quickly mixed to obtain a molding composition.

The obtained composition was poured into a mold-like mold, tamped, and the mold was removed after about 10 minutes, resulting in a mold with a beautiful surface.

The counter pressure was 35o9/crj.

Next, the resulting mold was fed to a high-frequency heater and dried, resulting in a resistance pressure of 13! A template of 9/crlL was obtained.

Molten pig iron at 1300° C. was poured into the mold, and after cooling, the mold was struck with a hammer to break it down, resulting in a casting with a beautiful surface.

The sand from the destroyed mold could be reused by rubbing it.

Example 2 Powdered carboxymethyl cellulose in silica sand lOO part
．． After adding 5 parts and stirring and mixing thoroughly, 4 parts of a 15% aqueous solution of sodium salt of styrene-maleic acid copolymer (molecular weight 4500, acid value 190) was added and quickly mixed and dispersed to obtain a molding composition.

The resulting composition was poured into a mold and tamped for about 10 minutes.
When the mold was removed after a few minutes, a mold with a beautiful surface was obtained.

The counter pressure was 4oo9/cyrt. When the obtained mold was supplied to a drying oven and dried, the resistive pressure was 18 kg/c.
A template for IIL was obtained.

1300 in the mold after drying obtained by the above method.
℃ molten pig iron was poured and then cooled.

After cooling, this mold was immersed in water, and the mold collapsed easily, yielding a casting with a beautiful surface.

Almost no dust is generated during this operation, and the silica sand in the water can be reused by washing with water.

Example 3 After adding 2 parts of powdered soluble starch to 100 parts of silica sand and thoroughly stirring and mixing, 10% of ammonia cum salt of styrene-maleic acid copolymer (molecular weight 6000, acid value 150) was added.
Four parts of an aqueous solution was added and quickly mixed and dispersed to obtain a molding composition.

The obtained composition is poured into a mold-like mold and tamped to form a mold of about 1
When the mold was removed after a period of time, a mold with a beautiful surface was obtained.

The counter pressure was 340 g/ffl. The obtained mold is 2
After being left to dry for 4 hours, the resistance pressure was 13 kg/ffl.
A mold was obtained.

Molten pig iron at 1,300°C was poured into the mold, and after cooling, the mold was crushed to obtain a casting with a beautiful surface.

The crushed silica sand could be reused by burning it in a combustion furnace.

Claims (1)

[Claims] 1. A method for manufacturing a mold, which comprises adding water to a mixture of silica sand, a water-soluble thickener, and a water-soluble salt of a styrene-maleic acid copolymer, and molding the mixture into a mold shape. . 2. The manufacturing method according to claim 1, wherein the water-soluble thickener is powdered water. 3. The manufacturing method according to claim 1, wherein the water-soluble salt is powdered water. 4 Claim 1 in which the water-soluble salt is a sodium salt
Manufacturing method described in section. 5. The manufacturing method according to claim 1, wherein the water-soluble salt is an ammonium salt. 6. A method for producing a mold, which comprises adding an aqueous solution of a styrene-maleic acid copolymer salt to a mixture of silica sand and a water-soluble thickener and molding the mixture into a mold shape. 1. The manufacturing method according to claim 6, wherein the water-soluble thickener is in powder form. 8. The manufacturing method according to claim 6, wherein the salt is a sodium salt. 9. The manufacturing method according to claim 6, wherein the salt is an ammonium salt. 10. The manufacturing method according to claim 6, wherein the concentration of the salt in the aqueous solution is 5 to 20% by weight. 11. The manufacturing method according to claim 6, wherein the amount of the aqueous salt solution added is 1 to 10 parts by weight based on 100 parts by weight of silica sand.