JPH0899149A - Binder composition for casting mold, casting mold composition and production of casting mold - Google Patents

Abstract

PURPOSE: To obtain an improved binder compsn. for casting molds to be used in process for production of casting molds by using a phenol aldehyde modified resin as a binder and curing the binder by an org. ester and/or carbon dioxide. CONSTITUTION: The casting molds are produced by using the binder compsn. for casting molds consisting of the phenol aldehyde modified resin and an org. nitrogen compd. as essential components, a casting mold compsn. compounded with the binder compsn. and the binder compsn. thereof. The formaldehyde smells produced at the time of molding of the casting molds and at the time of casting are greatly suppressed and the working environment can greatly be improved; further, the casting mold strength is improved. In addition, the flow property and packability of system sand are improved.

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 mold, which significantly suppresses formaldehyde odor generated during molding and casting of the mold, remarkably improves working environment, and kneading. The present invention relates to a binder composition capable of improving sand flowability and filling property, and further improving mold strength. The present invention also relates to a mold composition containing the binder composition, and a method for producing a mold using the binder composition.

[0002]

2. Description of the Related Art As a molding method for producing a mold such as a main mold or a core using an organic binder, a self-hardening mold method, a cold box mold method, and a cloning method (shell method) are known. In particular, the organic self-hardening mold making method has already become a general-purpose molding method in place of the inorganic type from the viewpoints of productivity, casting quality, safety and health centering on the field of mechanical casting. On the other hand,
To manufacture molds at medium and high speeds, so-called Coated Sand, which is a phenolic resin coated on a granular refractory
The cloning method of manufacturing a mold by heat-curing is widely used. However, energy saving during mold manufacturing,
In order to improve the mold production speed and the quality of molds and castings, the cold box mold method, which cures at room temperature with a gaseous or aerosol substance, is seriously introduced in the foundry industry as a mold manufacturing method that replaces the cloning method. Is coming.

[0003]

As a binder composition used in the organic self-hardening mold molding method and the gas-curable mold molding method, a casting in which a water-soluble phenol resin is used as a binder and is cured with an organic ester. A binder composition for sand is disclosed in JP-A-50-130627, JP-A-58-154433, and JP-A-58-154433.
It is known from, for example, JP-A-58-154434. Further, the use of a phenolic resin obtained by polycondensing bisphenol and formaldehyde as a binder (JP-A-62-40948, JP-A-63-40636) and potassium alkaline bisphenol-phenol copolymerization It is also known to use a resol type resin as a binder (Japanese Patent Laid-Open No. 5-123818).

Further, recently, a process using carbon dioxide has been proposed as a gas curing mold forming method (Japanese Patent Publication No. 1-224263). This uses a carbon dioxide gas, which has less adverse effects on the human body than an organic ester gas, and thus is particularly noted from the viewpoint of safety and hygiene.

[0005] In the mold making method using these binder compositions, since the binder composition does not contain elemental sulfur, the influence of vulcanization is greater than that of the casting molding method using the acid-curable resin. On the other hand, there is a problem in that the work environment due to the formaldehyde odor generated during molding and casting and the fluidity and filling property of the kneading sand using the binder are improved.

Further, the kneading sand using the water-soluble phenol resin is inferior in the fluidity of the kneading sand and the filling property to the model etc. as compared with the case of using the furan resin or the phenol urethane resin. For this reason, uneven kneading of the resin, a decrease in the surface strength of the molded mold, and irregularities on the surface of the mold occur, and defects occur in the cast product. Specifically, sand kami, baking,
Casting defects such as insertion and squeezing occur, causing quality deterioration, and their improvement is desired.

Further, Japanese Patent Application Laid-Open No. 5-927737 discloses a binder composition for foundry sand containing a water-soluble phenolic resin and an organic nitrogen compound as essential components, but the strength of the obtained mold is low. There was a problem.

[0008]

As a result of intensive studies to solve the above problems, the present inventors have found that a phenol / aldehyde-modified resin is used as a binder, and is cured with an organic ester and / or carbon dioxide gas. In the binder composition for use, by using an organic ester-curable binder composition comprising an organic nitrogen compound as a formaldehyde scavenger in combination with a phenol / aldehyde-modified resin, Formaldehyde odor generated during molding and casting of the mold can be significantly suppressed, the working environment can be significantly improved, the fluidity and filling of the kneading sand can be improved, and the mold strength can be improved, resulting in casting defects. The present inventors have completed the present invention by discovering that an excellent mold can be produced.

That is, the present invention relates to a binder composition for a mold, which comprises a phenol / aldehyde-modified resin and an organic nitrogen compound as essential components.

The present invention is also a mold composition characterized by being obtained by kneading a mixture of 0.1 to 15 parts by weight of the binder composition for a mold described above with 100 parts by weight of the refractory aggregate. Regarding things.

Further, the present invention relates to a method for producing a mold, which comprises using the binder composition for a mold described above and using an organic ester and / or carbon dioxide gas as a curing agent.

The phenol / aldehyde-modified resin used in the present invention is obtained by co-condensing an aldehyde compound with one or more compounds selected from bisphenols represented by the following general formula (1): Alternatively, one or more compounds selected from phenols and the above general formula
It is obtained by co-condensing one or more compounds selected from the bisphenols represented by (1) with an aldehyde compound.

[0013]

[Chemical 3]

Specific examples of the bisphenols represented by the general formula (1) include bisphenol A, bisphenol F, bisphenol C, bisphenol E, bisphenol Z, bisphenol S, bisphenol AF, bisphenol AP, di-sec-butyl- Bisphenol A, di-isopropyl-bisphenol A, 1,1-ethylidene-bisphenol, methyl-ethyl-methylene-
Bisphenol A, methylisobutyl-methylene-bisphenol, methyl-hexyl-methylene-bisphenol, methyl-phenyl-methylene-bisphenol,
4,4'-thiodiphenol and the like can be mentioned, and these can be used alone or in a mixture.

The phenols are represented by the following general formula (2)
One or more selected from the compounds represented by (4) to (4) are used.

[0016]

[Chemical 4]

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

[0018]

[Chemical 5]

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

[0020]

[Chemical 6]

(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,
3,5-xylenol and the like can be mentioned. The compound represented by the general formula (3) is a polyhydric phenol, and specific examples thereof include resorcinol and catechol. Further, the compound represented by the general formula (4) is mainly one in which an alkyl group having 3 or more carbon atoms or a phenyl group is bonded to the para position, and specific examples thereof include nonylphenol and p-tert.
-Butylphenol, isopropenylphenol, phenylphenol and the like. Also, a mixture of various phenols such as cashew nut shell liquid can be used. Particularly, as the phenols, a mixture of phenol and cresol is preferable.

As the aldehyde compound, formaldehyde, paraformaldehyde, furfural, glyoxal, etc. may be used alone or in combination.

When bisphenols, or phenols and bisphenols, and an aldehyde compound are co-condensed, 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 number of moles of bisphenols, or the total number of moles of phenols and the number of moles of bisphenols is 1.
0 to 5.0 [(the number of moles of bisphenols, or the number of moles of phenols + the number of moles of bisphenols): the number of moles of aldehyde compounds = 1: 1.0 to 5.0] is preferable. In particular, the molar ratio of the aldehyde compound is 1.5 to
A value of 3.0 is more preferable. When the molar ratio of the aldehyde compound is less than 1.0, the strength of the mold tends not to be sufficiently improved even when molding is performed using the obtained phenol / aldehyde modified resin. On the other hand, when the molar ratio of the aldehyde compound exceeds 5.0, the phenol / aldehyde-modified resin obtained has a strong aldehyde odor, which may deteriorate the working environment. When phenols and bisphenols are used in combination, the ratio of the number of moles of bisphenols to the number of moles of phenols is 0.001 to 1000.
(Number of moles of phenols: Number of moles of bisphenols =
1: 0.001 to 1000) is preferable. In particular, the molar ratio of bisphenols is more preferably 0.01 to 90. If the number of moles of bisphenols is less than 0.001 or exceeds 1000, the strength of the obtained mold tends to be insufficiently improved.

Copolycondensation of bisphenols or phenols and bisphenols with 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 bisphenols or phenols and bisphenols are dissolved, and co-condensation polymerization is preferably performed. At this time, as the reaction catalyst, an alkali catalyst such as potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH) is used, but especially potassium hydroxide (KOH) is used. Is preferred. 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, or a minimum amount of potassium hydroxide may be used as a reaction catalyst. Then, after completion of the copolycondensation, a predetermined amount of potassium hydroxide may be added. Further, after the copolycondensation is completed, 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 number of moles of hydroxyl groups of bisphenols, or the total number of moles of hydroxyl groups of phenols and the number of moles of hydroxyl groups of bisphenols, the ratio of the total number of moles of alkali is: 0.2 ~
It is preferably 1.2. In addition, the concentration of the phenol / aldehyde-modified resin in the alkaline aqueous solution is 30-
It is preferably 75% by weight.

Further, the phenol / aldehyde-modified resin is further excellent in the fluidity of the kneading sand and the filling property in the model when it is kneaded with the refractory granular material by further cocondensing alcohols. As the alcohols, monohydric alcohols having 2 to 10 carbon atoms are preferable, and examples thereof include ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl. Examples thereof include alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol and decyl alcohol. Particularly, as the monohydric alcohol, propyl alcohol, isopropyl alcohol,
Most preferably butyl alcohol, isobutyl alcohol, sec-butyl alcohol or tert-butyl alcohol is used. The blending ratio is preferably 0.0001 to 0.5 times the mole number of bisphenols or the total number of moles of phenols and bisphenols. In particular, it is more preferable that the alcohol is 0.01 to 0.2 times mol. The number of moles of alcohols is 0.
If it is less than 0001 times the molar amount, there is no effect of adding alcohols, and if it exceeds 0.5 times the molar amount, the strength of the template tends not to be sufficiently improved.

In the present invention, the organic nitrogen compound is preferably one or more selected from urea, urea compounds, amide compounds and amine compounds.

The urea used in the present invention is
Granular urea, urea aqueous solution, or urea dissolved in other solvent may be used. Urea compounds include monomethylol urea, dimethylol urea, trimethylol urea, which are compounds of aldehydes and urea, and urea formalin resin, which is a condensate of these compounds, and urea salts such as urea oxalate, urea phosphate, urea nitrate, and sulfuric acid. Examples of urea and double salts of urea include gypsum urea, magnesium urea sulfate, magnesium urea nitrate, lime nitrate nitrate and the like. Examples of the amide compound include acrylic amide, amide sulfonic acid, amide phosphoric acid, amide sulfuric acid, and metal amides thereof such as Ca amide sulfonate, Mg amide sulfonate, Al amide sulfonate, Fe amide sulfonate, and Zn amide sulfonate. , And other metal salts such as amide phosphoric acid and amide sulfuric acid. Examples of the amine compound include aliphatic primary amine, aliphatic secondary amine, unsaturated aliphatic amine, alicyclic amine, aromatic amine, cyclic amine (hexamine, melamine, etc.).

The above-mentioned organic nitrogen compounds used in the present invention may be added to the sand for casting or the reclaimed sand in powder form, but the water or solvent solution of the above organic nitrogen compounds or their slurry dispersion may be prepared in advance. A liquid may be prepared and added. Examples of the solvent used as the solvent solution include lower alcohols such as ethanol and propanol, polyhydric alcohols such as glycerin and ethylene glycol, and commonly known solvents such as acetone and ester compounds.

In order to produce the binder composition for molds of the present invention, one or more selected from the above organic nitrogen compounds may be simply dissolved in the phenol / aldehyde modified resin. It may be added at the reaction stage of the modified resin and incorporated into the chemical structure of the resin composition. Alternatively, the above-mentioned organic nitrogen compound is an aqueous solution, a solvent solution (dissolved in an organic ester or other solvent) in a direct pretreatment when the resin is mixed with the molding sand or the reclaimed sand to be molded. It does not matter even if it is kneaded in the form of a dispersion liquid or the like.

In the binder composition for a mold of the present invention, the content of the above-mentioned organic nitrogen compound according to the present invention is nitrogen% by weight.
The amount is preferably 0.05 to 5% by weight, more preferably 0.1 to 5% by weight based on the solid content in the phenol / aldehyde modified resin.
It is 2% by weight. When the nitrogen weight% is less than 0.05% by weight, there is almost no effect of suppressing the formaldehyde odor generated during mold making and casting, while when it exceeds 5% by weight, problems such as poor casting quality may occur. Further, when the nitrogen weight% of the above organic nitrogen compound contained in the phenol / aldehyde-modified resin is in the range of 0.1 to 2 weight%, the effect of suppressing the formaldehyde odor is extremely exerted, and mold molding is performed with regenerated sand that is repeatedly used. Even if it is cast, the quality of the casting is not a problem.

By using the binder composition for a mold of the present invention, it is possible to improve the environment and the fluidity and filling property of the kneading sand by the effect of suppressing the formaldehyde odor. In addition to the effect of suppressing the formaldehyde odor, the fluidity and filling property of the kneading sand can be further improved. It is considered that, by using the organic nitrogen compound such as urea, urea compound, and amide compound together with the surfactant, both effects are synergistically improved.

As the surfactant used in the present invention,
Nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants and the like can be used. Specific examples of the surfactant include fatty acid type surface active agents such as fatty acid soap (for example, metal salt of stearic acid), rosin acid soap, naphthenic acid soap, fatty acid sarcoside, proteolytic product fatty acid amide soap, and the like as anionic surfactant. The agent is a long-chain alcohol sulfate ester salt (for example, a metal salt of 2-ethylhexyl sulfate ester, a metal salt of oleyl sulfate ester, etc.), a secondary alcohol sulfate ester salt, an olefin sulfate ester salt, a fatty acid ethylene glycolide sulfate ester salt, and a polyoxy ester. Ethylene alkyl ether sulfate ester salt, polyoxyethylene alkylphenyl sulfate ester salt, fatty acid monoglyceride fatty acid ester salt, fatty acid polyhydric alcohol sulfate ester salt, sulfated oil (olive oil,
Castor oil, beef tallow, bran oil, cottonseed oil, rapeseed oil, corn oil, other vegetable oils, sperm whale oil, wax, etc.), fatty acid alkyl sulfate ester salt, fatty acid amide sulfate ester salt (oleic acid, ricinoleic acid amide sulfate), fatty acid anilide Sulfate ester type surfactants such as sulfate ester salts (sulfates of oleic acid anilide) and fatty acid monoalkanolamide sulfate ester salts are alkanes (C _{8 to} C
₂₀ ) Sulfonates, petroleum sulfonates, α-olefin sulfonates, α-sulfo fatty acid salts, sulfoethanol fatty acid ester salts, alkylsulfoacetates, fatty acid amide sulfonates, alkenylsulfosuccinates, dialkenylsulfosuccinates Acid salt, sulfosuccinic acid monoalkylamide, polyoxyethylene isooctylphenyl ether sulfonate, naphthalene sulfonate formalin condensate, naphthalene sulfonate, dinaphthyl methane sulfonate, alkylphenol sulfonate, lignin sulfonate, Alkylbenzene sulfonate (ABS,
LAS), alkyl diphenyl ether disulfonate, alkyl phosphate ester salt (2-ethylhexyl phosphate, etc.), polyoxyethylene alkylphenol ether phosphate ester salt, polyoxyethylene alkylphenol phosphate ester salt, etc. sulfonate and phosphate ester type surfactant Can be used as the salt form, K salt,
Examples thereof include Na salt, Li salt, and ammonium salt, and are not particularly limited.

As the nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl naphthyl ether, polyoxyethylenated castor oil,
Polyoxyethylene abiethyl alcohol, polyoxyethylene alkyl thioether, polyoxyethylene alkylamide, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene glycol ethylenediamine, polyoxyethylene monofatty acid ester, polyoxyethylene difatty acid Polyoxyethylene type surfactants such as ester, polyoxyethylene propylene glycol fatty acid ester, polyoxyethylene sorbitan mono fatty acid ester, polyoxyethylene sorbitan tri fatty acid ester, ethylene glycol mono fatty acid ester, propylene glycol mono fatty acid ester, diethylene glycol mono ester Fatty acid ester, glycerin monofatty acid ester, pentaerythritol fatty acid Polyhydric alcohol type and alkylolamide type surfactants such as stell, sorbitan monofatty acid ester, sorbitan sesquifatty acid ester, sorbitan trifatty acid ester, sucrose fatty acid ester, fatty acid monoethanolamide and fatty acid monoisopropanolamide are polyoxyethylene alkyl Amine-type surfactants such as amine, N-alkyl propylene diamine, N-alkyl polyethylene polyamine, N-alkyl polyethylene polyamine dimethyl sulfate, alkyl biguanide, long-chain amine oxide and the like can be used.

As the cationic surfactant, a long-chain primary amine salt (acetate, hydrochloride), dialkyldimethylammonium salt, alkyldimethylethylammonium salt, alkyldimethylbenzylammonium salt, alkylpyridinium salt, alkylquinolium salt is used. Salt, alkylisoquinolium salt, alkylpyridinium sulfate, acylaminoethyldiethylamine salt (formate, acetate, lactate), acylaminoethylmethyldiethylammonium salt, fatty acid polyethylene polyamide, acylaminoethylpyridinium salt, acylcholamino Quaternary ammonium salts such as formylmethylpyridinium salts and amide-bonded ammonium salt types are stearilooxymethylpyridinium salts, fatty acid triethanolamine, fatty acid triethanolamine formate salts. A quaternary ammonium salt type having an ester-bonded amine and an ether bond such as polyoxyethylene fatty acid triethanolamine, fatty acid dibutylaminoethanol, cetyloxymethylpyridinium salt, and p-isooctylphenoxyethoxyethyldimethylbenzylammonium salt is an alkylimidazoline. , 1-Hydroxyethyl-2-alkylimidazoline, 1-acetylaminoethyl-2-alkylimidazoline, 2-alkyl-4-hydroxymethyloxazoline, and heterocyclic amine type surfactants such as quaternary salts thereof can be used.

Further, as the amphoteric surfactant, N-alkyltriglycine, dimethylalkylbetaine, N-alkyloxymethyl-N, N-diethylbetaine, alkylbetaine, N-alkyl-β-aminopropionate, alkyldiamine (Aminoethyl) glycine hydrochloride, dialkyldiethylenetriaminoacetic acid hydrochloride, N-alkyltaurine salt, aminoethylimidazoline organic acid salt and the like can be used.

In addition, fluorine-based surfactants, silicon-based surfactants and the like can be used, and the surfactants are not particularly limited.

The blending amount of the surfactant is not particularly limited, but is preferably 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the phenol / aldehyde modified resin.
Parts by weight. When the compounding amount of the surfactant is out of the above range, the fluidity and the filling property of the kneading sand deteriorate.

When a surfactant is used in combination with the binder composition for molds of the present invention, one or more selected from the above surfactants may be simply dissolved in the phenol / aldehyde modified resin, Alternatively, when the molding sand or reclaimed sand to be molded is to be kneaded with the phenol / aldehyde-modified resin, the above-mentioned surfactant is directly powdered in the form of powder, or an aqueous solution, a solvent solution (organic ester or other solution). It may be dissolved in the solvent of 1) or kneaded in the form of a dispersion or the like. As a solvent when making a solvent solution,
Examples include lower alcohols such as ethanol and propanol, polyhydric alcohols such as glycerin and ethylene glycol, and commonly known solvents such as acetone and ester compounds.

When a silane coupling agent is used in combination with the binder composition for a template of the present invention, the silane coupling agent is 0.001 to 100 parts by weight based on 100 parts by weight of the binder composition for a template of the present invention. 1 part by weight, preferably 0.002 to 0.5 part by weight, can be added to mold the mold by a conventional process. As the silane coupling agent used in the present invention, known silane coupling agents can be used.
-Aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane and the like can be mentioned. In the present invention, it is preferable to use this silane coupling agent together with the binder composition.

In order to manufacture a mold using the binder composition for a mold of the present invention, a self-hardening mold molding method or a gas-curable mold molding method is generally adopted. As a specific example of the self-hardening mold making method, 0.05 to 9 parts by weight of an organic ester as a curing agent is added and kneaded to 100 parts by weight of a refractory granular material. Subsequently, the binder composition for a mold of the present invention is added in the form of an aqueous alkali solution so that the solid content is 0.1 to 15 parts by weight, and the mixture is 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 template molding method, the binder composition for a template of the present invention as solid content in the form of an alkaline aqueous solution with respect to 100 parts by weight of the refractory granular material.
Add and knead so as to be 0.1 to 15 parts by weight. The obtained kneaded sand is filled in a gas hardening model with pressurized air by blowing. Next, by blowing 0.05 to 9 parts by weight of a gaseous or aerosol organic ester and curing, a gas-curable mold can be obtained.

The organic ester, which is a curing agent used in the template composition of the present invention, is a lactone or has 1 to 10 carbon atoms.
A monohydric or polyhydric alcohol and an organic ester derived from an organic carboxylic acid having 1 to 10 carbon atoms are used alone or in a mixture, but in a self-hardening mold molding method, γ-butyrolactone, propiolactone, ε-caprolactone, It is preferable to use ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin and the like. Particularly in the self-hardening mold making method, such compounds can be dissolved in the above organic ester curing agent. Further, it is preferable to use methyl formate in the gas-curable molding method. Further, in the case of using a carbon dioxide gas to cure the binder composition for a mold instead of an organic ester in a gaseous state, 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 the above, and the synergistic action of the compound having an oxyanion with carbon dioxide gas (JP-A-1-224263).
The binder composition for a mold of the present invention is not particularly limited by either the self-hardening mold molding method or the gas-curable mold molding method.

In the mold composition of the present invention, as the refractory granular material, reclaimed sand such as chromite sand, zircon sand, olivine sand, and alumina sand is used in addition to silica sand containing silica as a main component. In particular, as the refractory granular material, a material whose main component is aggregate after regeneration and / or recovery is preferable.

By using the binder composition for a mold of the present invention, formaldehyde odor during molding and casting of the mold can be significantly suppressed and the working environment can be remarkably improved. The action is estimated as follows. That is, by allowing at least one selected from the above organic nitrogen compounds to be present in the phenol / aldehyde modified resin, formaldehyde for reacting with and capturing the formaldehyde generated when the phenol / aldehyde modified resin undergoes a curing reaction. It is thought that the odor is suppressed.

The reason why the flowability and filling property of the kneading sand are improved by using a surfactant together with the binder composition for a mold of the present invention is that the sand surface kneaded with the binder is used. The hydrophobic groups of the surfactant are oriented in the
It is presumed that the fluidity and filling of the kneaded sand will be improved. In addition, the reason why organic nitrogen compounds such as urea are effective in improving the fluidity and filling of the kneaded sand is
Organic ester whose aldehyde-modified resin is a curing agent and /
Alternatively, since the lipophilic organic nitrogen compound-formaldehyde adduct produced by the reaction of formaldehyde and organic nitrogen compound generated when the reaction of polymerizing by carbon dioxide is induced, the fluidity and filling property of the kneading sand are It is supposed to improve.

[0046]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

[Preparation of Binder Composition Aqueous Solution 1 for Mold] 50
%, An amount of phenols, bisphenols and alcohols determined by the molar ratio shown in Table 1 was added to the aqueous solution of potassium hydroxide, and the mixture was stirred and dissolved. While maintaining this solution at 80 ° C., an amount of the aldehyde compound determined by the molar ratio shown in Table 1 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% hydroxylation was carried out so that the ratio of the number of moles of hydroxyl groups of phenols and the total number of moles of hydroxyl groups of bisphenols was 0.85. Aqueous potassium solution was added. In this way, an alkaline aqueous solution of the phenol / aldehyde modified resin was obtained. Then, the organic nitrogen compound shown in Table 1 was used as nitrogen weight% and 2% was added to the solid content in the phenol / aldehyde modified resin. Further, 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, an aqueous binder composition solution for a mold was prepared. The content of the binder composition (phenol / aldehyde modified resin, organic nitrogen compound and silane coupling agent) in the aqueous binder composition solution is 50.
% By weight.

The item A in Table 1 is the number of moles of phenols, the number of moles of bisphenols, or the number of moles of aldehyde compounds relative to the total number of moles of phenols and bisphenols. Is the ratio of That is, [the number of moles of aldehyde compound / (the number of moles of phenols + the number of moles of bisphenols)]. The item B is the ratio of the number of moles of bisphenols to the number of moles of phenols when phenols and bisphenols are used in combination. That is, [the number of moles of bisphenols / the number of moles of phenols]. Further, the item C is the ratio of the number of moles of alcohols to the number of moles of phenols, the number of moles of bisphenols, or the total number of moles of phenols and bisphenols. That is, [moles of alcohols / (moles of phenols + mols of bisphenols)]. Hereinafter, A to C in the table are the same as this.

[Preparation of Binder Composition Aqueous Solution 2 for Mold] 50
% Aqueous potassium hydroxide solution, the amounts of phenols, bisphenols and alcohols defined by the molar ratios shown in Example 6 of Table 1 were added and stirred to dissolve. While maintaining this solution at 80 ° C., a 50% aqueous formaldehyde solution in an amount determined by the molar ratio shown in Example 6 of Table 1 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% hydroxylation was carried out so that the ratio of the number of moles of hydroxyl groups of phenols and the total number of moles of hydroxyl groups of bisphenols was 0.85. Aqueous potassium solution was added. Then, the organic nitrogen compound shown in Table 2 was used as nitrogen weight%, and 2% was added to the solid content in the phenol / aldehyde modified resin. Further, the surfactants shown in Table 2 were added in an amount of 2% by weight based on the solid content in the phenol / aldehyde modified resin as a solid content by weight%. Further, 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. The content of the binder composition (phenol / aldehyde modified resin, organic nitrogen compound, surfactant and silane coupling agent) in the binder composition aqueous solution prepared as described above was 50% by weight. .

[Preparation of Binder Composition Aqueous Solution 3 for Mold] 50
% Aqueous potassium hydroxide solution, the amounts of phenols, bisphenols and alcohols defined by the molar ratios shown in Example 6 of Table 1 were added and stirred to dissolve. While maintaining this solution at 80 ° C., a 50% aqueous formaldehyde solution in an amount determined by the molar ratio shown in Example 6 of Table 1 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 1800. The determination at the time when the weight average molecular weight reached 1800 was performed by measuring the viscosity of the reaction solution. After completion of the reaction, after cooling to room temperature, 50% hydroxylation was carried out so that the ratio of the number of moles of hydroxyl groups of phenols and the total number of moles of hydroxyl groups of bisphenols was 0.85. Aqueous potassium solution was added. Then, the organic nitrogen compounds shown in Table 3 were used as nitrogen weight% and 2% was added to the solid content in the phenol / aldehyde modified resin. Further, the surfactant shown in Table 3 was added as a solid content weight% of 2% based on the solid content in the phenol / aldehyde modified resin. Further, 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. The content of the binder composition (phenol / aldehyde modified resin, organic nitrogen compound, surfactant and silane coupling agent) in the binder composition aqueous solution prepared as described above was 50% by weight. .

[Preparation of Binder Composition Aqueous Solution 4 for Template] When preparing the binder composition aqueous solution 2 for a mold, 90 parts by weight of an aqueous solution of a phenol / aldehyde-modified resin obtained after the reaction was completed, Sodium borate decahydrate 5 parts by weight, 95%
5 parts by weight of potassium hydroxide was mixed to prepare an aqueous binder composition solution for a template.

Examples 1 to 15 and Comparative Examples 1 to 3 The formaldehyde odor generated during casting and casting was evaluated in the self-hardening casting method. That is, with respect to 100 parts by weight of sand of Fremantle silica, 0.375 parts by weight of triacetin which is a curing agent and 1.5 parts by weight of the binder composition aqueous solution 1 are added and kneaded. Cast material FC-25 (S / M = 3.5, where S / M represents the weight ratio of the mold and the weight of the casting) was cast. The formaldehyde odor generated during the molding of the mold and 15 minutes after the completion of casting was sensory evaluated. Also, of this mold
The compressive strength (kg / cm ² ) after 24 hours was measured. At the same time, the fluidity and filling property of the kneading sand were measured. That is, inner diameter 50
Attach a pedestal to the bottom of a test cylinder with an internal effective length of 100 mm and an internal effective length of 100 mm, and pass the 3 mm sieve through it to roughly fill the test cylinder with kneading sand. Next, the excess kneaded sand on the upper side was scraped off, and the mixture was applied to a "compactability tester manufactured by George Fisher" and pressurized with a squeeze pressure of 10 kg / cm ² . The decrease in the height of the kneading sand after this is measured, and this decrease height X
mm [= C. B. (Compactability)] was used as an index of fluidity and filling of the kneading sand. The smaller the X, the better the fluidity and filling of the kneading sand. The results are shown in Table 1.

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[Table 1]

* Evaluation criteria for formaldehyde odor (same for the following examples and comparative examples) ◎ Almost no formaldehyde odor. ○ Minimize formaldehyde odor. △ Formaldehyde has a certain odor and irritation is observed in the eyes. × Strong formaldehyde odor and sufficient irritation to the eyes.

Examples 16 to 27 and Comparative Example 4 Formaldehyde odor generated during casting and casting was evaluated in the self-hardening casting method. That is, a mold formed from a mixture formed by adding 0.375 parts by weight of triacetin, which is a curing agent, and 1.5 parts by weight of the binder composition aqueous solution 2 to 100 parts by weight of Fremantle silica sand, and kneading, Cast material FC-25 (S / M = 3.5, where S / M represents the weight ratio of the mold and the weight of the casting) was cast. The formaldehyde odor generated during the molding of the mold and 15 minutes after the completion of casting was sensory evaluated. Moreover, the bulk specific gravity was measured by the following method. The results are shown in Table 2.

<Bulk Specific Gravity Measuring Method> Prepared in Examples 16 to 27 and Comparative Example 4 according to the measuring method of the report of "Bulk Specific Gravity Testing Method of Aggregate for Organic Mold"" After molding the mold using the phenol / aldehyde-modified resin, after 24 hours, disassemble this mold and leave it for 24 hours under the environmental conditions of 20 ° C and 60% RH using this disintegrated sand. Was measured. The higher the bulk specific gravity value, the better the sand filling and fluidity.

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[Table 2]

Examples 28 to 35 and Comparative Example 5 To 100 parts by weight of silica sand which is a refractory granular material, 2.0 parts by weight of the aqueous binder composition aqueous solution 3 prepared in advance was added and kneaded. And kneaded sand was obtained. Each kneading sand,
Fill a 50mmφ × 50mmh gas test piece frame with silica sand
Inject 1.2 parts by weight of methyl formate per 100 parts by weight,
A mold was molded by a gas-curable mold manufacturing method. The formaldehyde odor generated during the molding of the mold and 15 minutes after the completion of casting was sensory evaluated. The bulk specific gravity was also measured. Table 3 shows the results.

[0059]

[Table 3]

Examples 36 to 43 and Comparative Example 6 To 100 parts by weight of silica sand, which is a refractory granular material, 3.0 parts by weight of the aqueous binder composition aqueous solution 4 prepared in advance was added and kneaded. And kneaded sand was obtained. Each kneading sand,
A test piece frame for gas of 50 mmφ × 50 mmh was filled, and carbon dioxide was aerated at a flow rate of 10 liters / minute for 2 minutes, and a mold was formed by a gas-curable mold manufacturing method. The formaldehyde odor generated 15 minutes after the completion of casting was sensory evaluated. The bulk specific gravity was also measured. The results are shown in Table 4.

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[Table 4]

[0062]

As is apparent from the above examples, when the binder composition for a mold of the present invention is used and cured with an organic ester and / or carbon dioxide gas, it is generated during molding and casting of the mold. Significantly suppress formaldehyde odor,
The working environment can be significantly improved, and the mold strength can be further improved. Further, by additionally using a surfactant in the binder composition for a mold of the present invention, the fluidity and filling property of the kneading sand for molding can be improved.

Claims (10)

[Claims] 1. A phenol / aldehyde modified resin (A) obtained by co-condensing one or more compounds selected from bisphenols represented by the following general formula (1) with an aldehyde compound: A binder composition for a template, which comprises a nitrogen compound (B) as an essential component. [Chemical 1] 2. Obtained by co-condensing an aldehyde compound with one or more compounds selected from phenols and one or more compounds selected from bisphenols represented by the following general formula (1): Phenol / aldehyde modified resin
A binder composition for a template, which comprises (a) and an organic nitrogen compound (b) as essential components. [Chemical 2] 3. The binder composition for a mold according to claim 1, wherein bisphenol A or bisphenol F is used as the bisphenol. 4. The binder composition for a mold according to claim 2, wherein a mixture of phenol and cresol is used as the phenol. 5. The binder composition for a mold according to claim 1, wherein the phenol / aldehyde-modified resin is obtained by further co-condensing alcohols. 6. The binder composition for a template according to claim 1, wherein the organic nitrogen compound is one or more selected from urea, urea compounds, amide compounds and amine compounds. 7. The method according to claim 1, further comprising a surfactant.
The binder composition for a mold according to any one of 1. 8. The binder composition for a mold according to claim 1, which is contained in an amount of 0.1 to 100 parts by weight of the refractory aggregate.
A mold composition obtained by kneading a mixture of 15 parts by weight. 9. An organic ester curing agent 0.05 to 9 parts by weight, based on 100 parts by weight of the refractory aggregate, any one of claims 1 to 7.
Item 10. A mold composition obtained by kneading a mixture of 0.1 to 15 parts by weight of the binder composition for a mold according to Item. 10. A method for producing a mold, which comprises using the binder composition for a mold according to any one of claims 1 to 7 and using an organic ester and / or carbon dioxide gas as a curing agent. .