JP2003136184A - Organic caking additive composition for mold and material for mold made by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic caking additive composition for a mold which is considered for an environment by improving the bench life of a kneaded sand by reducing the influence of a bivalent metal salt, alleviating the influence of the bench life in the case of storing the bivalent metal salt in a foundry sand containing a recovered sand and/or a regenerated sand, further prolonging the recycling life of the foundry sand to perform a resource conservation or the reduction in an industrial waste of the foundry sand, and reducing the influence to a natural environment such as a soil contamination or the like even in the case of embedding the waste containing the bivalent metal salt of a lead, a zinc or the like generated in the case of recovering or regenerating the foundry sand. SOLUTION: The organic caking additive composition for the mold comprises an organic solvent solution containing a phenolic resin component and a polyisocyanate component in such a manner that the phenolic resin component contains a benzyl ether type phenolic resin obtained by the bivalent metal salt catalytic reaction of a phenol and the like with an aldehyde and the like so that the content of the bivalent metal salt is 50 ppm or less in terms of a metal element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic binder composition for casting molds and a casting mold material using the same. More specifically, an organic binder composition for a mold, which improves the pot life of the kneading sand used for the urethane curable mold, particularly the mold produced by the amine cold box method, and is environmentally friendly It relates to a material for a mold.

[0002]

2. Description of the Related Art Urethane curable molds used in sand mold casting have been manufactured by the amine cold box method or the room temperature self-hardening method. In recent years, the amine cold box has been used from the viewpoint of mold dimensional accuracy and productivity. Law has come to be emphasized.

This amine cold box method is a component of a two-component organic binder composition, that is, a solution of a benzyl ether type phenol resin in an organic solvent (phenol resin component).
And polyisocyanate organic solvent solution or polyisocyanate itself (polyisocyanate component) are added to the molding sand and kneaded. After filling the kneading sand into the molding die, a tertiary amine curing catalyst is aerated to give a phenol resin. This is a method for producing a mold in a short time by promoting the urethanization reaction between the polyisocyanate and the polyisocyanate.

However, the kneading sand has a room temperature curing property due to the urethanization reaction accelerating action of the divalent metal salt which is generally used as a reaction catalyst for benzyl ether type phenolic resin, so that it takes a rest like a molding site. After that, when the molding of the mold is restarted by using the kneading sand in the sand hopper, the strength is lower than the setting, or in some cases, various molding defects are caused, such as deterioration of the strength of the kneading sand, so-called kneading sand. It is easy to cause molding troubles due to the pot life.

From the viewpoint of resource saving of foundry sand, a used mold is generally crushed and collected as sand particles, and then sized to be recovered sand, or the recovered sand is subjected to polishing treatment,
In some cases, it is regenerated as reclaimed sand by reducing the amount of organic binders and contaminants attached to the surface of the recovered sand by roasting. Generally, these recovered sands and / or reclaimed sands are used alone or mixed with a predetermined amount of fresh sand for replenishment or sand property adjustment (hereinafter, the recovered sands and / or reclaimed sands are contained. Called casting sand).

However, since the divalent metal salt having the urethane reaction accelerating ability at room temperature as described above is gradually accumulated in the foundry sand containing the recovered sand and / or the reclaimed sand, which is repeatedly used, It is feared that not only the pot life of the kneading sand is affected, but also the recycling life of the molding sand is shortened. In addition, fine particles that are collected by a dust collector when making recovered sand or reclaimed sand from used molds and foundry sand that has deteriorated due to repeated use are generally used as reaction catalysts, such as lead and zinc. Since they contain valent metal salts, when they are landfilled as industrial waste, there is a concern that they may affect the natural environment such as soil pollution.

[0007]

The object of the present invention is to improve the pot life of kneaded sand by reducing the influence of (1) divalent metal salts, especially in the amine cold box method. Alternatively, the effect of the pot life associated with the accumulation of divalent metal salts on foundry sand containing reclaimed sand is reduced, and (2) the recycling life of the foundry sand is extended to conserve resources and industrial waste of the foundry sand. (3) For landfilling industrial waste containing divalent metal salts such as lead and zinc, which are generated when (3) recovering or reclaiming foundry sand from used urethane curable molds. An object of the present invention is to provide an environmentally-friendly organic binder composition for a template, which can reduce the influence on the natural environment such as soil pollution, and a material for a template using the same.

[0008]

Means for Solving the Problems The present inventor has conducted earnest research on the pot life of the kneading sand used in the amine cold box method, and as a result, found that the content of the divalent metal salt in the benzyl ether type phenol resin solution was It was found that when the amount was less than a specific amount, the pot life of the kneaded sand was significantly improved, and based on this finding, further research was conducted to complete the present invention.

That is, the organic binder composition for a template of the present invention is an organic binder composition for a template comprising at least a phenol resin component and a polyisocyanate component, wherein the phenol resin component is An organic solvent solution containing at least a benzyl ether type phenolic resin obtained by a divalent metal salt catalytic reaction of phenols and aldehydes and having a divalent metal salt content of 50 ppm or less in terms of metal element. Is characterized by.

In the organic binder composition for a template of the present invention, "the content of the divalent metal salt is 10 ppm or less in terms of metal element", "the divalent metal salt contains a lead metal element. “Containing” is included as an aspect.

Further, the casting material of the present invention is characterized by containing at least the above-mentioned organic binder composition for casting and molding sand.

The mold material of the present invention "contains a silane coupling agent and / or a curing retarder",
"The foundry sand contains recovered sand and / or reclaimed sand" is included as its mode.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The organic binder composition for molds of the present invention comprises at least a phenol resin component and a polyisocyanate component.

The phenol resin component is a solution of a benzyl ether type phenol resin in an organic solvent, and the content of the divalent metal salt in the solution is reduced to 50 ppm or less, preferably 10 ppm or less in terms of metal element, At least one selected from a benzyl ether type phenol resin, a modified benzyl ether type phenol resin and a mixture thereof is not particularly limited, but is generally 30.
It is an organic solvent solution that is contained in a proportion of -80% by mass.

When the content of the divalent metal salt exceeds 50 ppm, the pot life of the kneading sand cannot be improved, and moreover, the above-mentioned recovery sand and / or reclaimed sand cannot be added to the casting sand. It is not possible to reduce the pot life of kneading sand and the recycling life of the foundry sand due to the accumulation of valent metal salts, or the impact on the natural environment of landfilling industrial waste.

The phenol resin component (a solution of a benzyl ether type phenol resin in an organic solvent) is produced, for example, by the following method. That is, first in the presence of a divalent metal salt,
Phenols and aldehydes are reacted, for example, at a ratio of 0.8 to 3.0 mol of aldehyde to 1 mol of phenol to a desired degree of condensation, and then concentrated to obtain a benzyl ether type phenol resin. Alternatively, a modified benzyl ether type phenolic resin or a mixture thereof is prepared by mixing or reacting a modifying agent after the reaction process or after the reaction. Next, the obtained benzyl ether type phenol resin and / or modified benzyl ether type phenol resin is made into a solution with an appropriate organic solvent, and an insoluble metal ion scavenger is added to the solution, preferably at 40 ° C. or higher. It is produced by reducing the divalent metal salt at a temperature of 1 to 10 hours and separating and removing the insoluble matter in the solution with a solid-liquid separator such as a centrifuge or a filter.

Examples of the phenols include alkylphenols such as phenol, cresol, xylenol and p-tert-butylphenol, polyhydric phenols such as resorcinol, bisphenol F and bisphenol A, and mixtures thereof.

Examples of aldehydes include formaldehyde, formalin, paraformaldehyde, polyoxymethylene, glyoxal, furfural, and mixtures thereof.

The modifier is not particularly limited, but examples thereof include novolac type or resol type phenol resin, alkyd resin, xylene resin, urea resin, epoxy compound, furfuryl alcohol, polyvinyl alcohol, urea, amides, flaxseed. Examples thereof include oil, cashew nut shell liquid, starches, monosaccharides and mixtures thereof.

The divalent metal salt used as a reaction catalyst for phenols and aldehydes may be, for example, a divalent metal salt containing a metal element such as lead, zinc, cobalt, manganese, nickel, or the like. Lead naphthenate,
In addition to zinc naphthenate, lead acetate, zinc chloride, zinc acetate, zinc borate, lead oxide and mixtures thereof, there may be mentioned acid / base combinations capable of forming such divalent metal salts, among which, among others, When the divalent metal salt containing the lead metal element is used, the effect of the present invention is remarkably exhibited. The amount of the divalent metal salt used is not particularly limited, but is generally selected in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the phenols.

The organic solvent is not particularly limited, and for example, petroleum hydrocarbons such as paraffins, naphthenes and alkylbenzenes, such as dibasic acid esters,
Examples include organic esters such as fatty acid alkyl esters, ketones such as isophorone, and mixtures thereof.

The metal ion scavenger is not particularly limited as long as it has a divalent metal ion scavenging ability, but in consideration of removal from the solution after the reduction treatment, it is preferably insoluble in the solution. For example, an organic carboxylic acid such as maleic acid, fumaric acid, tartaric acid, an ion exchange resin such as Mitsui Levatit CNP-80, an organic heavy metal scavenger such as Epofrock L-1 manufactured by Miyoshi Yushi Co., Ltd., and a mixture thereof. Is mentioned. The amount of the metal ion scavenger used is not particularly limited because it depends on the type of the metal ion scavenger and the type and amount of the divalent metal salt used, but in consideration of removal efficiency and economic efficiency, it is generally Is from 0.05 to 100 parts by mass of the phenol resin component.
It is selected in the range of 10 parts by mass, preferably 0.1 to 5 parts by mass.

On the other hand, the polyisocyanate component is polyisocyanate or its organic solvent solution. Polyisocyanate is a compound having two or more isocyanate groups in the molecule that develops strength by reacting with a benzyl ether type phenol resin, and typical examples thereof include diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate (hereinafter , Crude MD
I)), an isocyanate prepolymer, and the like. These polyisocyanates are generally 40
It is used as it is, without using a solvent, in an organic solvent solution of -80% by mass.

The mixing ratio of the phenol resin component and the polyisocyanate component is not particularly limited, but phenol resin component / polyisocyanate component = mass basis
A range of 30/70 to 70/30 is suitable.

Next, the mold material according to the present invention contains at least the above-mentioned organic binder composition for mold and molding sand.

Specifically, it is a kneading sand obtained by adding and kneading the above-mentioned organic binder composition for a template (phenol resin component and polyisocyanate component) to foundry sand. Amine cold box method, in which a tertiary amine-based curing catalyst is aerated and cured after filling in a molding die, or kneading sand containing a base, amine, metal ion, etc. as a curing catalyst in a molding frame The urethane-curable mold can be manufactured by a room temperature self-hardening method or the like, in which the mold is filled with, optionally with vibration, and left to cure at room temperature for several hours to 24 hours.

Examples of the foundry sand include silica sand, olivine sand, zircon sand, chromite sand, alumina sand and other special sand, ferrochrome slag, ferronickel slag, converter slag and other slag particles, and nigai cera beads. Examples thereof include porous particles such as (trade name) and recovered sand or recycled sand thereof. These may be used alone or as a mixture of two or more kinds. In particular, in view of the effect of the present invention, casting sand containing recovered sand and / or recycled sand is preferable.

The mixing ratio of the organic binder composition for casting mold and the molding sand is not particularly limited, but generally 0.5 parts of the organic binder composition for casting product is added to 100 parts by mass of the casting sand.
A range of up to 5 parts by mass is suitable.

The mold material according to the present invention is prepared by adding the above-mentioned organic binder composition for a mold (phenol resin component and polyisocyanate component) to the molding sand at room temperature and kneading the mixture in a continuous or batch mixer. Manufactured by. At this time, a silane coupling agent and / or a curing retarder is preferably used.

The silane coupling agent is used for suppressing the deterioration of the mold strength due to humidity, and suitable examples include N-β (aminoethyl) γ-aminopropyltrimethoxysilane and γ-. Examples thereof include amino silanes such as aminopropyltriethoxysilane and epoxy silanes such as γ-glycidoxypropyltrimethoxysilane. These silane coupling agents are
Generally, it is used by being contained in the phenol resin component in an amount of about 0.01 to 5% by mass.

On the other hand, the curing retarder is used for suppressing the urethanization reaction, and preferred examples thereof include isophthalic acid chloride, salicylic acid and benzoic acid. These curing retarders are generally used in the phenol resin component or polyisocyanate component in an amount of 0.
It is used by incorporating it in an amount of about 01 to 10% by mass, or when adjusting the material for a mold.

[0032]

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

The measuring and evaluating methods in the examples are as follows.

(1) Content of divalent metal salt in phenol resin component (benzyl ether type phenol resin solution) After pretreatment with JIS K0102-5.4 (decomposition with nitric acid and sulfuric acid), ICP emission spectroscopic analysis Law (JIS
K0102.54.3).

(2) Strength immediately after kneading (mold strength) The material for the mold (kneading sand) was immediately manufactured and then immediately subjected to bending strength test piece molding apparatus (two pieces were taken, blow conditions: pressure 0.3 MPa).
× bending time 3 seconds, triethylamine gassing time + air purging conditions: pressure 0.3 MPa × time 10 seconds, and two bending strength test pieces (10 mm × 30 mm × 85)
mm) was prepared and its strength was immediately measured to obtain the strength immediately after kneading (mold strength).

(3) Pot life The remaining kneading sand that was not used for measuring the strength immediately after kneading was stored in a vinyl bag and sealed, and stored at room temperature. Immediately after kneading, after opening for a predetermined time, immediately after kneading Similar to the strength measurement, a bending strength test piece was prepared and its strength was measured to obtain the bending strength after a predetermined time. Strength immediately after kneading (mold strength)
On the other hand, it was evaluated that the smaller the deterioration in strength over time, the better the pot life.

<Production Example (Production of Phenolic Resin Component A)
> 100 g of phenol, 58.9 g of 92% by mass paraformaldehyde and lead naphthenate as a divalent metal salt in a three-neck reaction flask equipped with a reflux condenser, a thermometer and a stirrer.
After charging 32 g and reacting at reflux temperature for 90 minutes,
The mixture was concentrated under heating to obtain a benzyl ether type phenol resin having a water content of 1% by mass or less. Next, an organic ester-based or aromatic hydrocarbon-based organic solvent and γ-glycidoxypropyltrimethoxysilane as a silane coupling agent are added to obtain a phenol resin component A (benzyl ether type phenol) having a resin content of 50% by mass. An organic solvent solution of resin) was prepared. The content of the divalent metal salt in the obtained phenol resin component A was 303 ppm in terms of lead element.

<Example 1> Phenol prepared in the production example
With respect to 100 parts by mass of the resin component A, the phenol resin component
Add 1 part by mass of insoluble tartaric acid to A and mix with stirring.
Treatment at 80 ° C for 3 hours until the temperature drops below 30 ° C
Allow to stand and purge with nitrogen (pressure is 9.8 × 10) ^FourPa (1.
0 kgf / cm²)) And press filtration to
It is used in the present invention by removing the insoluble matter in the Nol resin component A.
Phenolic resin component B with reduced divalent metal salt content
Was prepared. In addition, the filter paper is Advantech Toyo Corporation
JIS P 3801 type 2 (product name: No. 2,
Retained particle size: 5 μm) was used. Also obtained pheno
Content of divalent metal salt in resin component B
Was 2 ppm.

Next, in a Kawasaki desk mixer manufactured by Dalton Co., Ltd., 1000 g of Sanei No. 6 silica sand at room temperature, 10 g of phenol resin component B, and 75% by mass of polyisocyanate component 1 containing isophthalic acid chloride as a reaction retarder.
After adding 0 g, the mixture was stirred and kneaded for 40 seconds to prepare a mold material. The mold strength and pot life (strength after 3 hours and 7 hours) of the obtained mold material were evaluated. The results are shown in Table 1.

<Example 2> In Example 1, the retained particle diameter of the filter paper was 5 μm to 6 μm (JISP 38).
01 Type 1, product name: No. In the same manner as in Example 1 except that the phenol resin component C used in the present invention was subjected to the reduction treatment of the divalent metal salt, except for changing to 1). The content of the divalent metal salt in the obtained phenol resin component C was 40 ppm in terms of lead element.

Next, a mold material was prepared in the same manner as in Example 1 except that the phenol resin component C was used in place of the phenol resin component B described in Example 1, and the mold strength and pot life were set. evaluated. The results are shown in Table 1.

<Comparative Example 1> In Example 1, the retained particle diameter of the filter paper was changed from 5 μm to 7 μm (JISP 3
801 5 types A, product name: No. 801 In the same manner as in Example 1 except that the phenol resin component D was treated to reduce the divalent metal salt to be compared, except that the phenol resin component D was changed to 5A). The content of the divalent metal salt in the obtained phenol resin component D was 60 ppm in terms of lead element.

Next, a mold material was prepared in the same manner as in Example 1 except that the phenol resin component D was used in place of the phenol resin component B described in Example 1, and the mold strength and pot life were set. evaluated. The results are shown in Table 1.

Comparative Example 2 Phenolic resin component A produced in the production example in place of the phenolic resin component B in Example 1 (the content of the divalent metal salt is 303 pp in terms of lead element).
A mold material was prepared in the same manner as in Example 1 except that m) was used, and the mold strength and pot life were evaluated. The results are shown in Table 1.

[0045]

[Table 1]

<Example 3> In Example 1, instead of the Sanei No. 6 silica sand, a polishing treatment was performed on the Niigai Cera beads # 550.
A mold material was prepared in the same manner as in Example 1 except that the reclaimed sand of Example 1 was used, and the mold strength and the pot life were evaluated. The results are shown in Table 2.

<Comparative Example 3> In Comparative Example 2, instead of the Sanei No. 6 silica sand, a polishing treatment was applied to the Niguei Cera beads # 550.
A mold material was prepared in the same manner as in Comparative Example 2 except that the reclaimed sand of Example 2 was used, and the mold strength and the pot life were evaluated. The results are shown in Table 2.

[0048]

[Table 2]

[0049]

As described above, according to the organic binder composition of the present invention used for preparing a urethane curable mold, benzyl having a divalent metal salt content as a phenol resin component is much smaller than that of the conventional one. The following effects are exhibited by using the ether type phenol resin solution.

(I) Particularly in the amine cold box method, (1) since the pot life of the material for the mold is significantly improved, (2) the divalent value for the foundry sand containing the recovered sand and / or the reclaimed sand. It is possible to reduce the influence of the pot life associated with the accumulation of metal salts. Further, (3) the recycling life of the foundry sand is extended, so that the resource of the foundry sand and the reduction of industrial waste can be reduced.

(II) Further, the content of divalent metal salts such as lead and zinc contained in the industrial waste generated when the molding sand is recovered or regenerated from the used urethane curable mold is extremely high. Since the amount is small, there is an advantage that it is possible to reduce the influence on the natural environment such as soil pollution caused by the landfill of industrial waste.

Claims (6)

[Claims] 1. An organic binder composition for a template, comprising at least a phenol resin component and a polyisocyanate component, wherein the phenol resin component is at least a divalent metal salt of phenols and aldehydes. It contains a benzyl ether type phenolic resin obtained by catalytic reaction, and the content of divalent metal salt is 5 in terms of metal element.
An organic binder composition for a template, which is an organic solvent solution containing 0 ppm or less. 2. The organic binder composition for a mold according to claim 1, wherein the content of the divalent metal salt is 10 ppm or less in terms of metal element. 3. The mold composition according to claim 1, wherein the divalent metal salt contains a lead metal element. 4. A mold material containing at least the organic binder composition for a mold according to any one of claims 1 to 3 and molding sand. 5. The mold material according to claim 4, further comprising a silane coupling agent and / or a curing retardant. 6. The molding material according to claim 4, wherein the foundry sand contains recovered sand and / or reclaimed sand.