JP2001314939A - Component of binding agent for gas hardening mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binding component for a mold having higher strength than that of prior components for manufacturing a mold and also having a longer usable time. SOLUTION: A triethanolamine is added regarding a binding component for molding sand using a water-soluble phenol resin and a gas or aerosol type organic ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a binder composition for a gas-curable mold. More specifically, improved refractory granules are used in a gas-curing mold molding method in which a water-soluble phenol resin is used as a binder, and a gas or aerosol organic ester is injected into the mold to produce a mold. The present invention relates to a binder composition for a mold.

[0002]

2. Description of the Related Art A gas-curable molding method in which a binder containing a water-soluble phenol resin as an essential component is cured with a gaseous organic ester as a binder composition used in a gas-curable mold molding method is disclosed in It is known from JP 58-154434.
In the mold making method using this binder composition, since sulfur element is not included in the binder composition, there is a feature that the influence of sulfuration is less than that in the casting method using an acid-curable resin. On the other hand, it has disadvantages such as low mold strength, short use time (hereinafter referred to as usable time) after mixing the refractory granules and the binder containing the water-soluble phenol resin, and the like. Improvement is desired.

[0003]

As an industrial method of the gas-curing mold molding method, a binder containing a water-soluble phenol resin as an essential component and a refractory granule are both mixed by a mixer with an emphasis on efficient production. A method is employed in which binder-coated granules are prepared by mixing and stored in a sand storage tank. Then, at the time of sand molding from the sand storage tank, the binder-coated granular material is appropriately filled into a mold by, for example, an air blow method, and then cured at room temperature by passing gaseous organic esters thereinto for casting. Sand mold has been obtained. At this time, the amount of the binder-coated granular material stored in the sand storage tank is generally several tens to several hundred times the volume of the mold. good. However, an increase in the amount of the binder-coated granules to be stored means that the binder-coated granules obtained by mixing the water-soluble phenol resin solution and the refractory granules with a mixer become longer. For example, the mold obtained by using the binder-coated granules left standing for 24 hours has a remarkably lower strength than the mold obtained by using the one immediately after mixing the binder and the granular aggregate. However, there is a problem that the performance as a mold is not maintained.

[Means for Solving the Problems]

[0004] Therefore, if the working life of the binder-coated granules can be prolonged, it is possible to increase the production amount of the binder-coated granules produced at one time, which results in the mold production efficiency. Will lead to a dramatic improvement. The present invention has found that the performance as a mold is maintained even when the usable time of the binder-coated granular material is extended, and the strength of the mold is improved.

That is, the present invention provides: A binder composition used in a gas-curable mold molding method for producing a mold by using a water-soluble phenol resin as a binder for refractory granules and injecting a gaseous or aerosol-like organic ester into the binder. 1. A binder composition for gas-curable molds, characterized in that the binder composition contains triethanolamine. 2. The gas-curable binder composition according to the above item 1, wherein the addition amount of triethanolamine is 2 to 10% by weight based on the resin solid content of the water-soluble phenol resin. 2. The gas-curable binder composition according to the above item 1, wherein the addition amount of triethanolamine is 2 to 10% by weight based on the resin solid content of the water-soluble phenol resin. Any one of the above items 1 to 3, wherein methyl formate is used as a gaseous or aerosol organic ester.
It is a binder composition for gas-curable molds of the description. By using the gas-curable mold molding method of the present invention, the mold obtained from the binder-coated granules left for a long time also has the working strength, and the strength of the mold itself can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION

[0006] The water-soluble phenol resin used in the present invention is a resol resin obtained by addition and condensation of phenols and aldehydes. Phenols include, for example, phenol, cresol, resorcinol, xylenol, bisphenol A, cumylphenol, nonylphenol, butylphenol, phenylphenol,
Ethyl phenol, octyl phenol, amyl phenol, naphthol, bisphenol F, bisphenol C, catechol, hydroquinone, pyrogallol, phloroglucin, lignin, bisphenol A residue, chlorophenol, dichlorophenol, other substituted phenols, etc. Among them, a phenol resin obtained by a reaction using formaldehyde alone or in combination with paraformaldehyde, acetaldehyde and furfural aldehyde is exemplified, but formaldehyde alone is preferred. The water-soluble phenolic resin in the present invention preferably has a molar ratio of formaldehyde to phenol in the range of 1.5: 1 to 2.5: 1.
When the amount of formaldehyde is smaller than the above range, the mold strength tends to decrease, and when the amount is larger than the above range, the effect of improving the pot life is low. Suitable alkaline catalysts used in the production of these water-soluble phenolic resins are the hydroxides of alkali metals, sodium hydroxide, potassium hydroxide, lithium hydroxide and mixtures thereof, with potassium hydroxide being most preferred. . The molar ratio of alkali to phenols in the binder is from 0.3: 1 to 1.
2: 1 is preferred. The water-soluble phenol resin may be added in powder form to foundry sand or its reclaimed sand, or may be mixed with a solution such as an aqueous solution of phenol resin or a slurry dispersion. The most preferred embodiment of the water-soluble phenolic resin is an aqueous solution of an alkali phenol-formaldehyde resin obtained from phenol and formaldehyde,
Those having a resin solid content of 30 to 80% by weight in the aqueous solution are preferred. The phenolic resins obtained therefrom are usually preferably those having a weight average molecular weight of 500 to 5,000.

In the present invention, the preferable addition amount of triethanolamine is 0.5 to 20% by weight based on the resin solid content of the water-soluble phenol resin, and more preferably the addition amount is based on the resin solid content of the water-soluble phenol resin. 2 to 10% by weight. When the amount of triethanolamine added is less than 0.5% by weight based on the solid content of the resin, the strength of the resulting mold is low, and the mold obtained by using the binder-coated granules left standing for 24 hours. Does not maintain the required strength. If the amount exceeds 20% by weight based on the resin solid content, the initial strength tends to be low. The timing of adding triethanolamine is not particularly limited, but it is preferable to add it after the water-soluble phenol resin is produced.

Various additives are effective as an additive for improving the fluidity of the binder-coated granules according to the present invention, such as nonionic surfactants, cationic surfactants, and anionic surfactants. Surfactants, amphoteric surfactants and the like can be used. To be more specific, as nonionic surfactants, polyoxyethylene alkyl ethers, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-type surfactants such as polyoxyethylene-polyoxypropylene glycol ethylenediamine,
Examples include polyhydric alcohol surfactants such as ethylene glycol monofatty acid ester, glycerin monofatty acid ester, and sorbitan trifatty acid ester, and alkylolamide surfactants such as fatty acid monoethanolamide and fatty acid monoisopropanolamide.

Specific examples of the anionic surfactant include a metal salt of stearic acid, a fatty acid type surfactant such as naphthenic acid, a metal salt of oleic sulfate, a polyoxyethylene alkyl ether sulfate, an aliphatic monoglyceride aliphatic. Ester salts, sulfated oils such as olive oil, fatty acid alkyl sulfates, sulfate ester type surfactants such as aliphatic amide sulfates, sulfonate type surfactants, and phosphate ester type surfactants are used. it can.

Specific examples of the cationic activator include quaternary ammonium salts such as alkylpyridinium salt, alkylquinolinium sulfate, acylaminoethylpyridinium salt, aliphatic triethanolamine, aliphatic triethanolamine formate, Polyoxyethylene fatty acid triethanolamine, fatty acid dibutylaminoethanol, a quaternary ammonium salt having an ester bond amine and an ether bond such as p-isooctylphenoxyethoxyethylbenzylammonium salt are alkylimidazoquine,
1-hydroxyethyl-2-alkylimidazoine, 1
Heterocyclic amine type surfactants such as -acetylaminoethyl-2-alkylimidazoline and quaternary salts thereof can be used.

Examples of the amphoteric surfactant include N-alkyltriglycidin, dimethylalkylbetaine, alkylbetaine, alkyldi (aminoethyl) glycine hydrochloride, dialkyldiethylenetriaminoacetic acid hydrochloride,
N-alkyltaurine salts and the like can be used. In addition, a fluorine surfactant and a silicon-based surfactant can also be used, and the surfactant is not particularly limited. The preferable addition amount of the surfactant is 10% of the resin solid content of the water-soluble phenol resin.
It is 0.01 to 1 part by weight based on 0 part by weight.

Further, a silane coupling agent can be added as an agent for improving the adhesion between the refractory aggregate and the binder. The silane coupling agent is used in an amount of 0.1 to 2.% based on 100 parts by weight of the resin solid content of the water-soluble phenol resin of the present invention.
It is preferred to add 0 parts by weight. Specific examples of the silane coupling agent include γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like.

The refractory granules used in the present invention include, for example, refractory granular sands conventionally used for mold casting, such as silica sand, chromite sand, zircon sand, and olivine sand. Fine powder sand, clay sand, recycled sand and the like can also be used. Other than sand, mullite sand, alumina sand, hollow alumina beads, shirasu balloon, glass beads, and the like can be used. Usually, molding sand is preferable, and sand having an average particle size of about 50 to 600 μm is preferable.

In order to produce a mold using the binder composition for a gas-curable mold of the present invention, a water-soluble phenol resin containing triethanolamine is first added to 100 parts by weight of the refractory granules. The kneaded sand to which 0.5 to 2.5 parts by weight of solid content has been added is filled into the model by hand or by using pressurized air, and then the gaseous or aerosol-like organic ester is added to 0.3 to 1. 5 parts by weight are blown and cured to produce a mold. The gaseous or aerosol organic ester used in the present invention is preferably an alkyl formate having 1 to 3 carbon atoms in the alkyl group, and the most preferred organic ester is methyl formate from the viewpoint of boiling point and activity. It is preferably dispersed as a vapor or an aerosol in water. The time required for aeration of the catalyst is often in the range of several seconds to several minutes, but when removing the mold from the frame, remove the mold from the frame after leaving it for a sufficient time to prevent damage to the mold. Is preferred.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. (All parts are parts by weight)

EXAMPLES (Production of water-soluble phenol resin) An aqueous solution containing 27.2 parts of phenol and 10 parts of potassium hydroxide was mixed and dissolved. 46.9 parts of a 37% aqueous formaldehyde solution were further added thereto (formaldehyde: phenol molar ratio: 2: 1). The mixture solution was heated under reflux for 3 hours and then cooled to obtain a potassium alkaline phenol / formaldehyde resin aqueous solution. (The resin solid content was 50% by weight, and the weight average molecular weight of the resin was 2200.) The solid content was determined to be 2.0 ± sample in an air circulation furnace.
0.1 g was heated at 100 ° C. for 3 hours and measured.

(Example 1) 100 parts by weight of the aqueous solution of potassium alkaline phenol / formaldehyde resin,
A solution consisting of 0.3 parts by weight of glycidoxypropyltrimethoxysilane was prepared. To this solution, a predetermined amount of triethananolamine shown in Table 1 was added to 100 parts of the aqueous solution of the potassium alkaline phenol / formaldehyde resin to obtain a binder. 2 parts by weight of the obtained binder aqueous solution was added to 100 parts by weight of Fremantle silica sand, and kneaded with a Shinagawa mixer for 90 seconds. Immediately after kneading the binder-coated sand, the mixture was allowed to stand for 2 hours and 24 hours.
m, weighed into a cylindrical mold having a packing density of 1.6 g / cc, filled with 1 part by weight of gaseous methyl formate into the mold, vented, and then allowed to mold for 1 minute and 24 hours, respectively. Was measured for compressive strength. Table 1 shows the results.

Comparative Example 1 A mold was produced in the same manner as in Example 1 except that triethanolamine was not used. The compression strength of the mold was measured and the results are shown in Table 1. In Table 1, both initial strength (immediately after kneading) and pot life (after 2 hours and 24 hours) have good compressive strength (1.50 or more).
For those that are not, the item of the judgment is marked with ○, and the pot life (2 hours and 24 hours)
(After time), those having a low compressive strength (less than 1.0) are marked as x, and the compressive strength is a value that can be used (more than 1.0 and less than 1.5), and the binder is left for 24 hours. The sample which did not decrease in compressive strength even when the coated granular material was used was designated as Δ.

[0018]

[Table 1]

According to Table 1, even after the binder-coated granular aggregate was allowed to stand for 24 hours, the mold obtained using the binder-coated granular aggregate to which triethanolamine was added had the initial compressive strength,
Both the 24-hour compressive strength is higher than the mold obtained from the binder-coated granular aggregate to which triethanolamine is not added, and the strength as a mold is maintained.

[0020]

As described above, the composition for casting production of the present invention has a longer pot life than the conventional composition for casting production, and is mixed with a binder and granular refractory aggregate and left for several hours. Even if it does, since the strength as a mold can be maintained, there is an excellent effect that the productivity of the mold can be dramatically improved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/17 C08K 5/17 C08L 61/08 C08L 61/08 F-term (Reference) 4E092 AA02 AA03 AA04 AA18 AA19 AA26 AA31 AA45 BA01 BA04 CA03 4J002 CC041 DE147 DJ007 DL007 EH036 EN108 FA087 FD146 FD341 GT00

Claims (4)

[Claims] 1. A binder used in a gas-curable mold molding method in which a water-soluble phenol resin is used as a binder for refractory granules, and a gaseous or aerosol-like organic ester is injected into the binder to produce a mold. A binder composition for a gas-curable mold, comprising a binder composition containing triethanolamine. 2. The binder composition for gas-curable molds according to claim 1, wherein the amount of triethanolamine added is 0.5 to 20% by weight based on the resin solid content of the water-soluble phenol resin. 3. The binder composition for a gas-curable mold according to claim 1, wherein the amount of triethanolamine added is 2 to 10% by weight based on the solid content of the water-soluble phenol resin. 4. A gas or aerosol organic ester comprising methyl formate.
The binder composition for a gas-curable mold according to any one of the above.