JP3221810B2 - Binder composition for mold, mold composition 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 producing a mold. 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 molding method is already a general-purpose molding method in place of the inorganic type from the viewpoint of productivity, casting quality, safety and health mainly in the field of mechanical casting. On the other hand,
So-called coated sand, in which phenolic resin is coated on granular refractories to produce molds at high speeds
A cloning method of producing a template by heat-curing is widely used. However, energy saving during mold production,
In order to improve mold production speed, mold and casting quality, cold box mold method of curing at room temperature with gaseous or aerosol-like material has been seriously introduced in the casting industry as a mold production method that replaces the cloning method. Is coming.

[0003]

As a binder composition for use in an organic self-hardening mold molding method and a gas-curable mold molding method, a casting obtained by using a water-soluble phenol resin as a binder and curing the same with an organic ester. The binder composition for sand is disclosed in JP-A-50-130627, JP-A-58-154433,
It is publicly known, for example, from JP-A-58-154434. Further, a phenolic resin obtained by polycondensation of bisphenol and formaldehyde may be used as a binder (JP-A-62-40948, JP-A-63-40636), or potassium-alkaline bisphenol-phenol copolymer It is also known to use a type resole resin as a binder (Japanese Patent Application Laid-Open No. H5-123818).

[0004] Recently, a process using carbon dioxide has been proposed as a molding method for gas curing (Japanese Patent Publication No. 1-224263). This is particularly noted from the viewpoint of health and safety because it uses carbon dioxide gas, which has less adverse effect on the human body than organic ester gas.

[0005] The mold making method using these binders has advantages such as a lower tendency of sulfuration as compared with the mold making method using an acid-curable resin because no sulfur atom is contained in the binder. On the other hand, it has disadvantages such as low mold strength, short pot life, and poor sand recyclability as compared with the acid-curable mold molding method, and further improvement is desired.

JP-A-5-50177 discloses a method for producing a sand mold for castings containing a water-soluble phenolic resin and an aromatic aldehyde as essential components. JP-A-4-118146 discloses a water-soluble phenolic resin and phosphorus aldehyde. A method for producing a sand mold for castings containing an acid triester as an essential component is disclosed in JP-A-4-118147, which discloses a method for producing a sand mold for castings containing a water-soluble phenol resin and a ketone compound as essential components. However, there was a problem that the strength of the obtained mold was low.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a phenol / aldehyde-modified resin is used as a binder and this is cured with an organic ester and / or carbon dioxide gas. In the binder composition for,
The present inventors have found that the use of one or more selected from a specific aromatic aldehyde, a phosphoric acid triester and a ketone compound in a phenol-aldehyde-modified resin greatly improves the strength of a mold, and the present invention It has been completed.

That is, the present invention relates to a phenol-aldehyde-modified resin and one or more aromatic aldehydes, phosphoric acid triesters and ketone compounds having one or more carbonyl groups in one molecule. As an essential component.

The present invention also provides a mold composition obtained by kneading a mixture comprising 0.1 to 15 parts by weight of the binder composition for a mold with 100 parts by weight of a refractory aggregate. About things.

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

The aromatic aldehydes used in the present invention include terephthalaldehyde, salicylic aldehyde, cinnamaldehyde, benzaldehyde and the like.

The following are specific examples of the phosphoric triesters used in the present invention.

[0013] Trimethyl phosphate, triethyl phosphate, tributyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, trisisopropylphenyl phosphate, tricresyl phosphate, tri-2-ethylhexyl phosphate, etc. is there.

The ketone compounds used in the present invention preferably have a molecular weight of 60 to 250, and specific examples thereof include the following.

Methyl ethyl ketone, methyl propyl ketone, isopropyl methyl ketone, butyl methyl ketone,
Isobutyl methyl ketone, pinacolone, diethyl ketone, dipropyl ketone, diisopropyl ketone, mesityl oxide, methyl heptenone, cyclobutanone, cyclopentanone, cyclohexanone, methylcyclohexanone, holone, isophorone, acetophenone, propiophenone, butyrophenone, valerophenone, benzophenone, dibenzophenone Benzyl ketone, 2-acetonaphthone, 2-
Examples include acetofuron, diacetyl, acetylbenzoyl, benzyl, acetylacetone, benzoylacetone, dibenzoylmethane, acetonylacetone, phenacylacetone, and 2,6-peptanedione.

The reason why the mold strength can be greatly improved by using the binder composition of the present invention is presumed as follows. That is, the presence of the compound as described above induces surface hydrogen bonding between the refractory granular material and the phenol-aldehyde-modified resin, thereby chemically improving surface properties such as improvement in interfacial adhesion. In addition, by physically improving, modifying, and improving the properties of the cured mold at the composition interface, i.e., the solid-liquid, liquid-liquid interface, and the cohesive force with respect to the refractory particles and the diffusivity and diffusivity. it is conceivable that.

To produce the binder composition for a mold of the present invention, the above-mentioned compound according to the present invention is usually used in an amount of 0.1 to 50% by weight based on the solid content of the phenol-aldehyde-modified resin with respect to the phenol-aldehyde-modified resin. %, Preferably 1 to 40% by weight. If the amount of the compound is less than 0.1% by weight, there is almost no effect of improving the strength of the mold, while if it exceeds 50% by weight, the strength of the mold decreases.

The form in which the phenol-aldehyde-modified resin and the compound as described above are used in combination may be contained in the phenol-aldehyde-modified resin or an aqueous solution,
When an organic ester is used as a curing agent, it may be mixed in the organic ester, or may be separately added to the refractory granular material. At this time, it may be added by diluting it with a known solvent to improve the kneading property.

In order to produce a mold by the self-hardening molding method using the binder composition for a mold of the present invention, the binder composition for a mold of the present invention is added to 100 parts by weight of the refractory granular material. 0.1 to 15 parts by weight, preferably 0.3 to 5 parts by weight, as a solid content in the form of an aqueous solution, and an organic ester as a curing agent 0.1.
05 to 9 parts by weight, preferably 0.1 to 5 parts by weight, can be kneaded by a well-known method, and a mold can be manufactured by using a conventional self-hardening mold manufacturing process as it is.

In the present invention, in order to produce a mold by a gas-curable mold molding method, first, a refractory granular material is used.
100 parts by weight of kneading sand obtained by adding 0.1 to 15 parts by weight, preferably 0.3 to 5 parts by weight of the binder composition for a mold of the present invention as a solid content in the form of an aqueous alkaline solution, or pressurized air The mold is manufactured by blowing into a model by blowing in the above and then blowing in 0.05 to 9 parts by weight of a gaseous or aerosol organic ester to cure the phenol-aldehyde-modified resin mixture.

Further, when a silane coupling agent is used in combination with the binder composition for a mold of the present invention, the silane coupling agent is added to 100 parts by weight of the binder composition for a mold of the present invention.
0.001 to 1 part by weight, preferably 0.002 to 0.5 part by weight is added, and a mold can be formed by the same process as described above.

The above compounds used in the present invention may be added in powder form to foundry sand or its reclaimed sand. However, a solvent solution of the above compounds or a slurry dispersion of these is prepared and added in advance. Is also good.

As the organic ester as a curing agent used in the present invention, a lactone or an organic ester derived from a monohydric or polyhydric alcohol having 1 to 10 carbon atoms and an organic carboxylic acid having 1 to 10 carbon atoms can be used alone. Or a mixture is used, but in the self-hardening mold molding method, it is preferable to use γ-butyrolactone, propionlactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, etc. In the method, it is preferable to use methyl formate. Furthermore, in the case of curing the binder composition for a mold using carbon dioxide gas instead of an organic ester in a gaseous state,
An appropriate amount of a compound having an oxyanion, such as boric acid, borate, or aluminate, is added to the binder composition, and the compound having the oxyanion and carbon dioxide gas cooperate to form a phenol / aldehyde-modified resin. It can be cured (JP-A-1-224263). The binder composition for a mold of the present invention is not particularly limited, regardless of whether it is a self-hardening mold molding method or a gas-curable mold molding method.

The phenol-aldehyde modified resin used in the present invention is obtained by co-condensing at least one compound selected from bisphenols represented by the following general formula (1), an aldehyde compound and an alcohol. those obtained or, with one or more compounds selected from bisphenols represented by one or more compounds selected from the phenols and the general formula (1), an aldehyde compound, Al
A call such is obtained by co-condensing.

[0025]

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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, methyl isobutyl-methylene-bisphenol, methyl-hexyl-methylene-bisphenol, methyl-phenyl-methylene-bisphenol,
4,4'-thiodiphenol and the like are used alone or as a mixture.

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

[0028]

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

[0030]

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

[0032]

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(Wherein, R ₈ represents an aliphatic or aromatic hydrocarbon group having 3 or more carbon atoms).

Among the phenols, specific examples of the compound represented by the general formula (2) include phenol, cresol,
3,5-xylenol and the like. The compound represented by the general formula (3) is a polyhydric phenol, and specific examples include resorcinol and catechol. The compound represented by the general formula (4) is mainly a compound 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 and the like are used alone or in combination.

When co-condensing bisphenols, or phenols and bisphenols, and aldehyde compounds, 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 the bisphenols or the total number of moles of the phenols and the number of moles of the bisphenols is 1.
0 to 5.0 [(mol number of bisphenols or mol number of phenols + mol number of bisphenols): mol number of aldehyde compound = 1: 1.0 to 5.0]. In particular, the molar ratio of the aldehyde compound is 1.5 to
3.0 is more preferred. When the ratio of the number of moles of the aldehyde compound is less than 1.0, there is a tendency that the strength of the mold is not sufficiently improved even when molding is performed using the obtained phenol / aldehyde-modified resin. Conversely, if the ratio of the number of moles of the aldehyde compound exceeds 5.0, the obtained phenol / aldehyde-modified resin has a strong odor of aldehyde, which may deteriorate the working environment. When phenols and bisphenols are used together, the ratio of the number of moles of bisphenols to the number of moles of phenols is about 0.001 to 1000 (the number of moles of phenols: the number of moles of bisphenols = 1: 0.001 to 1000 ) Is preferred. In particular, the ratio of the number of moles of bisphenols is more preferably 0.01 to 90.
When the number of moles of the bisphenol is less than 0.001 or more than 1,000, the strength of the obtained mold tends not to be sufficiently improved.

Copolycondensation polymerization of bisphenols or phenols and bisphenols with an aldehyde compound is generally carried out in an aqueous solution to obtain a phenol-aldehyde-modified resin. For example, it is preferable to obtain by co-condensation polymerization while gradually adding a predetermined amount of an aldehyde compound to an aqueous solution in which a predetermined amount of a bisphenol or a phenol and a bisphenol are dissolved. At this time, as a reaction catalyst, an alkali catalyst such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and lithium hydroxide (LiOH) is used, but potassium hydroxide is particularly preferable. 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 at the time of copolycondensation, or a minimum amount of potassium hydroxide is used as a reaction catalyst. After completion of the copolycondensation, a predetermined amount of potassium hydroxide may be added. After the completion of the copolycondensation, sodium hydroxide or lithium hydroxide may be used in combination with potassium hydroxide so as to attain a predetermined alkalinity. Further, after co-condensation polymerization using an acid catalyst, co-condensation polymerization may be subsequently advanced using an alkali catalyst such as potassium hydroxide. In the aqueous alkali solution of the phenol-aldehyde-modified resin, the ratio of the number of moles of the total alkali to the total number of moles of the hydroxyl group of the bisphenol or the number of moles of the hydroxyl group of the phenol and the number of moles of the hydroxyl group of the bisphenol is It is preferably from 0.2 to 1.2. Further, the concentration of the phenol / aldehyde-modified resin in the aqueous alkali solution is preferably 30 to 75% by weight.

The phenol / aldehyde-modified resin is further co-condensed with an alcohol, so that when kneaded with the refractory granular material, the kneaded sand is excellent in fluidity and filling property in a model. As the alcohols, monohydric alcohols having 2 to 10 carbon atoms are preferable. For example, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl Alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, caprylic alcohol, nonyl alcohol, decyl alcohol and the like can be mentioned. In particular, as monohydric alcohols, propyl alcohol, isopropyl alcohol,
Most preferably, butyl alcohol, isobutyl alcohol, sec-butyl alcohol or tert-butyl alcohol is used. The mixing ratio is preferably 0.0001 to 0.5 times the mole number of the bisphenols or the total number of moles of the phenols and the bisphenols. In particular, it is more preferable that the amount of the alcohol is 0.01 to 0.2 times mol. The number of moles of alcohols is 0.
If the molar ratio is less than 0001 times, there is no effect of adding alcohols. Conversely, if it exceeds 0.5 times, the strength of the mold tends not to be sufficiently improved.

As the refractory granular material, inorganic refractory granular materials such as chromite sand, zircon sand, olivine sand, and alumina sand are used in addition to silica sand containing quartz as a main component, but are not particularly limited. Absent. Further, a silane coupling agent may be added for the purpose of further improving the mold strength. Preferred silane coupling agents include γ-aminopropyltriethoxysilane and γ- (2
-Aminoethyl) aminopropyltrimethoxysilane and the like.

[0040]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. [Preparation of aqueous solution of binder composition 1 for mold] To a 50% aqueous solution of potassium hydroxide, phenols, bisphenols, and alcohols in amounts specified by the molar ratio shown in Table 1 were added, 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. Weight average molecular weight
The determination when the temperature reached 2500 was made by measuring the viscosity of the reaction solution. After the reaction is completed, the reaction mixture is cooled to room temperature, and then subjected to 50% hydroxylation so that the ratio of the number of moles of potassium hydroxide to the total number of moles of hydroxyl groups of phenols and the number of moles of hydroxyl groups of bisphenols becomes 0.85. An aqueous potassium solution was added. As described above, an alkaline aqueous solution of the phenol / aldehyde-modified resin was obtained. Then, various compounds shown in Table 1 were added to an aqueous solution of 10 parts by weight based on 100 parts by weight of the phenol-aldehyde-modified resin. As described above, the aqueous binder composition aqueous solution 1 for a mold was prepared. The binder composition in the binder composition aqueous solution
(Phenol-aldehyde-modified resin, various compounds) content was 50% by weight. The solid content of the phenol / aldehyde-modified resin aqueous solution was measured by heating a sample (2.0 ± 0.1 g) weighed in an air circulation furnace to 100 ° C. for 3 hours.

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

[Preparation of aqueous solution of binder composition for template 2] The aqueous solution of binder composition for template was prepared except that the reaction was continued until the weight average molecular weight of the phenol-aldehyde-modified resin in the reaction solution reached 1800. In the same manner as in 1, an aqueous solution 2 of the binder composition for a mold was prepared. Table 2 shows the reaction molar ratio and the type and amount of the added compound.

[Preparation of aqueous solution of binder composition for mold 3] In the preparation of aqueous solution of binder composition for mold 2, 90 parts by weight of an aqueous solution of a phenol-aldehyde-modified resin obtained after completion of the reaction was added. 5 parts by weight of sodium borate decahydrate, 95%
5 parts by weight of potassium hydroxide were mixed to prepare a binder composition aqueous solution 3 for a mold. Table 3 shows the reaction molar ratio and the type and amount of the compound added.

Examples 1 to 6 and Comparative Examples 1 to 4 The mold strength in the self-hardening mold making method was evaluated. That is,
For 100 parts by weight of silica sand, 0.3 parts by weight of triacetin,
A mixture obtained by adding and kneading 1.5 parts by weight of the aqueous binder composition solution for a mold 1 was filled into a test piece model of 50 mmφ × 50 mmh, and the compressive strength 24 hours after the kneading was measured. At the same time, the fluidity and filling properties of the kneaded sand were measured. That is,
Attach a pedestal to the bottom of a test tube with an inner diameter of 50 mm and an effective inner length of 100 mm, pass through a 3 mm sieve and roughly fill the test tube with kneading sand. Next, the excess kneading sand at the top was scraped off and applied to a “Compactability tester manufactured by George Fisher Co.”, and pressurized with a squeeze pressure of 10 kg / cm ² . Thereafter, the decrease in height of the kneading sand was measured, and the decrease height X
mm [= C. B. (Compactability)] was used as an index for the fluidity and filling properties of the kneaded sand. The smaller the value of X, the better the fluidity and filling properties of the kneaded sand. Table 1 shows the results
Shown in

[0045]

[Table 1]

Examples 7 to 12 and Comparative Examples 5 to 8 The mold strength in the gas-curable mold making method was evaluated. That is, a mixture formed by adding and kneading 2.0 parts by weight of a binder composition aqueous solution 2 for 100 parts by weight of silica sand to a 50 mmφ × 50
The test piece was filled into a mmh gas-hardening test piece model. 1.5 parts by weight of gaseous methyl formate was injected into the model, and the compressive strength was measured 24 hours after the injection. Table 2 shows the results.

[0047]

[Table 2]

Examples 13 to 18 and Comparative Examples 9 to 12 A mixture obtained by adding and kneading 3.5 parts by weight of an aqueous solution 3 of a binder composition for a mold was added to 100 parts by weight of silica sand as a refractory granular material.
A test piece frame for gas of 0 mmφ × 50 mmh was filled, carbon dioxide gas was passed at a flow rate of 10 liter / min for 2 minutes, and a mold was formed by a gas-curable mold manufacturing method. After 24 hours, the compression strength (kg / cm ² ) of the mold was measured. Table 3 shows the results.

[0049]

[Table 3]

[0050]

As is apparent from the above embodiments, according to the manufacturing method of the present invention, a mold having a higher strength can be obtained as compared with the mold obtained by the conventional manufacturing method. As a result, it becomes possible to reduce the amount of the binder used, so that the molding sand can be easily collected, and the amount of gas generated from the casting mold at the time of casting can be reduced. A sound casting can be produced, which is practically useful.

Continuation of the front page (56) References JP-A-61-238439 (JP, A) JP-A-4-118146 (JP, A) JP-A-4-118147 (JP, A) JP-A-63-142016 (JP) , A) JP-A-63-177938 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22C 1/00-1/26

Claims (7)

(57) [Claims] 1. A phenol-aldehyde-modified resin (A) obtained by co-condensing at least one compound selected from bisphenols represented by the following general formula (1), an aldehyde compound and alcohols: ) And aromatic aldehydes,
A binder composition for a mold, comprising, as an essential component, at least one selected from phosphoric acid triesters and ketone compounds having one or more carbonyl groups in one molecule. . Embedded image 2. An aldehyde compound and an alcohol which are co-condensed with at least one compound selected from phenols and at least one compound selected from bisphenols represented by the following general formula (1): Phenol obtained by
Aldehyde-modified resin (a) and at least one selected from aromatic aldehydes, phosphoric acid triesters and ketone compounds having at least one carbonyl group in one molecule
and (b) as an essential component. Embedded image 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 any one of claims 1 to 4 , wherein the binder composition is 0.1 to 100 parts by weight of the refractory aggregate.
A mold composition obtained by kneading a mixture consisting of 15 parts by weight. 6. The organic ester curing agent of 0.05 to 9 parts by weight, based on 100 parts by weight of the refractory aggregate, any one of claims 1 to 4
A mold composition obtained by kneading a mixture consisting of 0.1 to 15 parts by weight of a binder composition for a mold as described in Item. 7. A method for producing a mold, comprising using the binder composition for a mold according to any one of claims 1 to 4 and using an organic ester and / or carbon dioxide as a curing agent. .