JP5549830B2 - Resin coated sand using phenolic novolac resin - Google Patents

Description

  The present invention relates to a resin coated sand using a phenol novolak resin.

  Phenol novolak resins are used in a wide range of fields such as molding materials, epoxy resin curing agents, photoresist resins, and epoxy resin raw materials. And it is known that the characteristics, particularly the reactivity, vary depending on the ratio of ortho positions in the methylene bond derived from the aldehydes as the raw material, that is, the ortho ratio (see Non-Patent Document 1). For example, it is known that when the ortho ratio is increased, the curability by the amine compound is accelerated, and in the case of a novolac epoxy resin obtained by epoxidizing a phenol novolac resin, the curability may be similarly accelerated. Are known. For this reason, novolak resins having various ortho ratios are manufactured according to the application.

  For example, when p-toluenesulfonic acid is used as a catalyst in the reaction between phenol and formalin, an ortho ratio of about 20% can be produced. By using oxalic acid, an ortho ratio of about 40% can be obtained. It is known that it can be manufactured. It is also known that by using zinc acetate, a product having an ortho ratio exceeding 60% called a high ortho novolak can be produced. In addition, when producing phenolic novolak resins having an ortho ratio of about 40%, compared to the case of producing an ortho ratio of about 20%, the catalyst used is a weak acid, so the reaction is carried out for a long time or the temperature is raised. Attempts have also been made to improve the reaction rate, such as dehydration (see Patent Document 1).

In addition, by carrying out the reaction between phenols and aldehydes under an oxalic acid catalyst under specific conditions of 110 to 160 ° C. under pressure, a phenol novolak resin having an ortho ratio of 40 to 60% is obtained. A method for producing a phenol novolak resin with good yield and industrially advantageous is disclosed (see Patent Document 2).
In recent years, casting molds have been required to reduce the manufacturing time per one molding cycle in accordance with the rationalization of production, and the coated sand used therefor has been strongly required to have faster curability. .
JP-A-62-275121 JP 2002-179749 A "Phenolic resin": 48-52 pages, 1987, published by Plastics Age Co., Ltd.

  However, this method of improving the reaction rate has a problem that the yield is low, furthermore, a problem that a large amount of raw material phenols are contained in the wastewater such as distillate water and separated water, and an industry that requires equipment for pressurization. There was a problem above. The present invention produces a phenol novolak resin having an ortho ratio of 30 to 60%, preferably 40 to 55% in good yield (70% or more), and using this phenol novolak resin, high curability is obtained. It is an object to provide a resin coat sand having.

As a result of repeated research to solve the above problems, the present inventors have deactivated the catalytic action of the metal compound with a chelating agent after the reaction between the phenol and the aldehyde under the catalyst of the metal compound, It has been found that the desired phenol novolak resin can be obtained with good yield, and further that the resin coated sand using the phenol novolak resin has higher curability.
That is, the present invention relates to the following.
(1) In a resin coated sand composed of at least a fireproof aggregate and a phenolic novolak resin having an ortho ratio of 30 to 60%, the phenolic novolak resin is phenols and formaldehyde in the presence of a metal compound as a catalyst. Is added at a temperature of 100 to 160 ° C. for 0.01 to 6 hours, and then a chelating agent is added to deactivate the catalytic action of the metal compound, and then the reaction is further continued. The chelating agent is ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), trans-1,2-cyclohexadiamine-N, N, N ′, N′-tetraacetic acid (CyDTA), diethylenetriamine-N, N, N ′, N′-pentaacetic acid (DTPA), ethylenediaminediacetic acid (EDDA), iminodiacetic acid (IDA), hyde Roxyethyliminodiacetic acid (HIDA), ethylenediaminedipropionic acid (EDDP), ethylenediaminetetrakismethylenephosphonic acid (EDTPO), hydroxyethylethylenediaminetetraacetic acid (EDTA-OH), diaminopropanoltetraacetic acid (DPTA-OH), nitrilotrismethylene 1 selected from phosphonic acid (NTPO), bis (aminophenyl) ethylene glycol tetraacetic acid (BAPTA), nitrilotripropionic acid (NTP), dihydroxyethylglycine (DHEG), and glycol ether diamine tetraacetic acid (GEDTA) Resin coated sand characterized by being 2 or more.
(2) The phenol is one or more selected from phenol, cresol, xylenol, ethylphenol, phenylphenol, t-butylphenol, t-amylphenol, bisphenol A and resorcinol, Resin coated sand.
(3) The resin coat sand as described above, wherein the formaldehyde is one or more selected from formalin, paraformaldehyde, and trioxane.
(4) The resin coat sand as described above, wherein the metal compound is one or more selected from monovalent to hexavalent metal oxides, organic salts, inorganic salts, and hydroxides. .

  According to the present invention, a phenol novolak resin having a good yield (70% or more) and an ortho ratio of 30 to 60%, preferably an ortho ratio of 40 to 55% can be obtained. High curability is obtained.

Hereinafter, the manufacturing method of the phenol novolak resin used for this invention is demonstrated in detail.
The phenolic novolak resin used in the present invention is a phenolic novolak resin obtained by reacting phenols with formaldehyde, and uses a metal compound as a catalyst for the reaction, and further loses the catalytic action of the metal compound. It is characterized by using a chelating agent to make it active. The phenols used in the present invention are not particularly limited, and examples thereof include phenol, cresol, xylenol, ethylphenol, phenylphenol, t-butylphenol, t-amylphenol, bisphenol A, resorcinol and the like. Phenols may be used alone or in combination of two or more.

Examples of aldehydes used in the present invention include formalin, paraformaldehyde, trioxane and the like. Aldehydes may be used alone or in combination of two or more. Of these, formalin and paraformaldehyde are preferable in terms of handling properties. The amount of the aldehyde used varies depending on the molecular weight of the target phenol novolak resin, but is usually 0.5 to 0.99 mol times based on 1 mol of the phenol.
If the amount is less than 0.5 mol times, the yield may decrease, and if it exceeds 0.99 mol times, gelation may occur.

  The metal compound used as the catalyst is preferably selected from monovalent to hexavalent metal oxides, organic salts, inorganic salts, and hydroxides. The metal compounds may be used alone or in combination of two or more, but may be used in the form of a solid or powder, or may be used in a state dispersed in an aqueous solution or solvent. Examples of the metal compound include zinc oxide, zinc salicylate, zinc acetate, manganese sulfate, titanium oxide, sodium chloride, vanadium pentoxide, indium oxide, chromium oxide, cobalt oxide, nickel acetate, barium acetate, copper acetate, tin hydroxide, Antimony hydroxide, lithium hydroxide, strontium hydroxide, lanthanum hydroxide, zinc chloride, zinc hydroxide, magnesium oxalate, calcium carbonate, magnesium hydroxide and the like can be mentioned. The usage-amount of a metal compound is 0.0001-0.1 mol times normally as a metal ion with respect to 1 mol of phenols. Preferably, it is 0.0002-0.05 mol times with respect to 1 mol of phenols, More preferably, it is 0.0003-0.01 mol times, Especially preferably, it is 0.0004-0.005 mol times. If the amount is less than 0.0001 mol times, the reactivity may be remarkably lowered. If the amount exceeds 0.1 mol times, the reaction may proceed explosively.

Examples of the chelating agent for deactivating the catalytic action of the metal compound include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), trans-1,2-cyclohexadiamine-N, N, N ′, N′— Tetraacetic acid (CyDTA), diethylenetriamine-N, N, N ′, N′-pentaacetic acid (DTPA), ethylenediaminediacetic acid (EDDA), iminodiacetic acid (IDA), hydroxyethyliminodiacetic acid (HIDA), ethylenediaminedipropion Acid (EDDP), ethylenediaminetetrakismethylenephosphonic acid (EDTPO), hydroxyethylethylenediaminetetraacetic acid (EDTA-OH), diaminopropanoltetraacetic acid (DPTA-OH), nitrilotrismethylenephosphonic acid (NTPO), bis (aminophenyl) ethylene Glycol tetraacetic acid (B APTA), nitrilotripropionic acid (NTP), dihydroxyethylglycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA) and the like. A chelating agent may be used alone or in combination of two or more.
The amount of chelating agent used is usually 0.01 to 100 moles per mole of the metal compound. If the amount used is too large, the strength of the synthetic product will be adversely affected. Therefore, the amount is preferably 0.01 to 20 moles, more preferably 0.1 to 10 moles, particularly preferably 0 to 1 mole of the metal compound. .4 to 6 mole times.

  In the present invention, the above phenols, aldehydes, and metal compound (catalyst) are used, and the reaction is usually performed at 100 to 160 ° C. under normal pressure. Also, the ortho ratio can be controlled by changing the timing of adding the chelating agent. That is, the ortho ratio decreases when reacted at the initial stage of the reaction, and increases when reacted after a long reaction with the metal compound (catalyst). The ortho ratio can be determined by infrared spectroscopic analysis.

Depending on the application, phenolic novolak resins having various ortho ratios are manufactured. As ortho ratios of phenol novolak resins used for resin coated sands, molding materials, resin materials for casting, etc., 60% is preferable, and 40 to 55% is more preferable.
In the case of producing a resin coat sand using a phenolic novolak resin, if the ortho ratio is less than 30%, problems such as slow hardening of the resin coat sand, and if it exceeds 60%, the resin coat sand There is a risk of problems such as a significant decrease in strength.

  In order to obtain a phenol novolak resin having an ortho ratio of 30 to 60%, a phenol, an aldehyde, and a metal compound (catalyst) are reacted for 0.01 to 6 hours at 100 to 160 ° C. under normal pressure. Thereafter, a chelating agent is preferably added. Furthermore, after adding a chelating agent, it is preferable to make it react at 80-160 degreeC for 1 to 5 hours. The temperature at which the chelating agent is added is not particularly limited, but is preferably 110 ° C. or lower in order to eliminate the risk of bumping.

  In order to obtain a phenol novolak resin having an ortho ratio of 30 to 49%, it is preferable to react at 100 to 160 ° C. and normal pressure for 0.01 to 1 hour, and then add a chelating agent. In order to obtain a phenol novolak resin having an ortho ratio of 50 to 60%, it is preferable to react at 100 to 160 ° C. under normal pressure for 1 to 6 hours, and then add a chelating agent. In order to obtain a phenol novolak resin having an ortho ratio of 40 to 55%, the reaction may be performed at 100 to 160 ° C. under normal pressure for 0.1 to 3 hours, and then a chelating agent may be added.

  The resin coat sand of the present invention can be produced, for example, as follows. A separable flask equipped with a thermometer, a condenser, and a stirrer is charged with phenols, aldehydes, and a metal compound, and heated to react. Subsequently, a chelating agent is added continuously or discontinuously at a predetermined temperature, and the temperature is kept until the reaction is completed. Thereafter, atmospheric dehydration and vacuum dehydration are performed as necessary to obtain the phenol novolac resin. The resin coat sand according to the present invention does not require special production conditions, and can be produced by a commonly used production method such as a kneading mixer or a speed mixer. For example, the phenol novolak resin adjusted to a particle size of 0.85 to 5.66 mm is added to a refractory aggregate heated to 120 to 180 ° C. and stirred to melt coat the surface of the sand particles (refractory aggregate). Next, a curing agent is added and kneaded until the lump of sand particles (fireproof aggregate) is broken. Next, the resin coat sand of the present invention is obtained by adding a lubricant and stirring and mixing. Usually, the addition of a lubricant is preferable because it provides the resin coated sand with the effect of imparting fluidity and improving releasability. In addition, as for the coated sand of this invention, it is desirable to add a lubricant as needed.

  The refractory aggregate used in the present invention is used for mold molding such as quartz sand, flat sand, alumina sand, zircon sand, chromite sand, olivine sand, mullite sand, magnesia, fly ash mainly composed of quartz. If it is, it will not specifically limit. In the present invention, various refractory aggregates can be used without any particular limitation, such as these new sand, recovered sand, reclaimed sand, or mixed sand thereof. In addition, the particle size distribution and particle size of the refractory aggregate can be selected without particular limitation as long as it is suitable for casting and the mold formation. Examples of the curing agent include hexamethylenetetramine (hexamine), epoxy resin, and isocyanate. Examples of the lubricant include calcium stearate, zinc stearate, calcium carbonate, talc, and glass powder.

  0.1-10 mass parts is preferable with respect to 100 mass parts of fireproof aggregates, and, as for the compounding quantity of phenol novolak resin, 1-3 mass parts is more preferable. Moreover, 1-30 mass parts is preferable with respect to 100 mass parts of phenol novolak resins, and, as for the compounding quantity of a hardening | curing agent, 10-20 mass parts is more preferable. Moreover, 0-10 mass parts is preferable with respect to 100 mass parts of fireproof aggregates, and, as for the compounding quantity of a lubricant, 0.001-5 mass parts is more preferable, and 0.01-1 mass part is especially preferable.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to an Example. In addition, the ortho ratio was calculated | required by following Formula by the arbitrary transmittance | permeability measured using the infrared spectrophotometer.
Ortho ratio (%) = (log 100 / T ₁ ) / (1.44 × log 100 / T ₀ + log 100 / T ₁ ) × 100
T _o ; 820 cm ⁻¹ transmittance (para-conjugate)
T ₁ ; 760 cm ⁻¹ transmittance (ortho conjugate)
The softening point was measured by the ring and ball method. Furthermore, the yield of phenol novolak resin was calculated with (weight of phenol + weight of formaldehyde + weight of additive) as 100%.

Example 1
In a separable flask equipped with a thermometer, Dimroth condenser, and stirrer, phenol 1000 g (molecular weight 94.11 g / mol, 10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol) and zinc salicylate trihydrate (2 g, molecular weight: 393.61 g / mol, 0.005 mol) are charged, immersed in an oil bath set at 130 ° C., and heated. After maintaining at reflux for 1 hour, the temperature was lowered to 98 ° C., 4 g of EDTA (molecular weight 292 g / mol, 0.014 mol) was added at 98 ° C., and when the reflux was started, the temperature was kept while continuing to reflux for 4 hours. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 998 g of a phenol resin (phenol novolak resin). The ortho ratio was 48% and the softening point was 96 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 78.3%.

(Example 2)
In a separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer, phenol 1000 g (10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol), 2 g of zinc acetate (molecular weight 183.5 g / mol, 0.011 mol) is charged, immersed in an oil bath set at 130 ° C., and heated. After maintaining at reflux for 1 hour and lowering the temperature to 98 ° C., 4 g (0.014 mol) of EDTA was added at 98 ° C. When the reflux was started, the temperature was kept while continuing to reflux for 4 hours. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 904 g of a phenol resin (phenol novolac resin). The ortho ratio was 49% and the softening point was 94 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 70.8%.

(Example 3)
In a separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer, phenol 1000 g (10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol), Charge 2 g (0.005 mol) of zinc salicylate trihydrate, immerse in an oil bath set at 130 ° C., and heat up. The mixture was kept at reflux for 2 hours, and the temperature was lowered to 98 ° C., then 4 g (0.014 mol) of EDTA was added, the temperature was raised again to 104 ° C., and when the reflux was started, the temperature was kept while continuing to reflux for 4 hours. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 994 g of phenol resin (phenol novolac resin). The ortho ratio was 55% and the softening point was 91 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 78.0%.

(Example 4)
In a separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer, phenol 1000 g (10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol), Manganese sulfate 2 g (molecular weight 151.01 g / mol, 0.013 mol) is charged, immersed in an oil bath set at 130 ° C., and heated. The mixture was kept at reflux for 0.5 hours, and the temperature was lowered to 98 ° C., 4 g of NTA (molecular weight: 191 g / mol, 0.021 mol) was added, and when the reflux was started, the mixture was kept for 4 hours while continuing to reflux. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 960 g of a phenol resin (phenol novolac resin). The ortho ratio was 40% and the softening point was 98 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 75.3%.

(Example 5)
In a separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer, phenol 1000 g (10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol), Charge 1.3 g of calcium carbonate (molecular weight 100 g / mol, 0.013 mol), immerse in an oil bath set at 130 ° C., and heat up. After maintaining at reflux for 0.5 hours and lowering the temperature to 98 ° C., 8.3 g of DTPA (molecular weight 393 g / mol, 0.021 mol) was added, and when the reflux was started, the temperature was maintained while continuing to reflux for 4 hours. . Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 951 g of a phenol resin (phenol novolac resin). The ortho ratio was 44% and the softening point was 93 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 74.1%.

(Example 6)
In a separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer, phenol 1000 g (10.6 mol), paraformaldehyde (92%) 200 g (6.13 mol), formalin (37%) 230 g (2.84 mol), 0.75 g of magnesium hydroxide (molecular weight 58.3 g / mol, 0.013 mol) is charged, immersed in an oil bath set at 130 ° C., and heated. The mixture was kept at reflux for 0.5 hours, and the temperature was lowered to 98 ° C., then 5.1 g of EDDP (molecular weight: 241 g / mol, 0.021 mol) was added, and when the reflux was started, the mixture was kept warm for 4 hours. . Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 934 g of a phenol resin (phenol novolac resin). The ortho ratio was 45% and the softening point was 95 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 72.7%.

(Comparative Example 1)
A separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer was charged with 1000 g of phenol, 200 g of paraformaldehyde (92%), and 230 g of formalin (37%), and 1.0 g of hydrochloric acid was added as a catalyst. It was immersed in a bath and heated to reflux for 3 hours in a reflux state, and further 2.0 g of hydrochloric acid was added and heated to reflux for 3 hours. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 882 g of a phenol resin (phenol novolac resin). The ortho ratio was 26%, and the softening point was 98 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 69.2%.

(Comparative Example 2)
A separable flask equipped with a thermometer, a Dimroth condenser, and a stirrer was charged with 1000 g of phenol, 200 g of paraformaldehyde (92%), and 230 g of formalin (37%), and 3.6 g of zinc acetate was added as a catalyst, and the temperature was set to 130 ° C. It was immersed in an oil bath, heated, and refluxed for 4 hours in a reflux state. Next, atmospheric distillation and vacuum distillation were sequentially performed to obtain 750 g of a phenol resin (phenol novolac resin). The ortho ratio was 68% and the softening point was 95 ° C. Moreover, the yield of the obtained phenol resin (phenol novolak resin) was 58.8%.

(Manufacture of resin-coated sand)
A method for producing a resin-coated sand using the phenol novolak resins obtained from Examples 1 to 6 and Comparative Examples 1 and 2 is as follows.
Using a speed muller manufactured by Enshu Iron Works, 200 g of the phenol novolak resin is added to 10 kg of flat sand heated to 150 to 160 ° C., and the resin is melt coated on the sand surface. Thereafter, 30 g of hexamethylenetetramine was added, 10 g of calcium stearate was added, mixed and stirred, and the sand was discharged to obtain a resin-coated sand.

(Evaluation of bending strength)
The test piece was molded at 250 ° C. for 60 seconds by placing the resin-coated sand obtained above in a heating mold (10 × 10 × 100 mm). After cooling to room temperature (25 ° C.), a bending test was performed using a bending tester (three-point bending type) at a fulcrum distance of 50 mm and a test speed of 25 mm / min, and the strength at break was measured.

(Evaluation of curability)
The test piece was molded at 250 ° C. for 30 seconds by placing the resin-coated sand obtained above in a heating mold (5 × 40 × 180 mm). A load of 500 g was applied after 20 seconds from the mold and placed on a test bench, and the deflection value was measured with a dial gauge. The distance between fulcrums was 150 mm. In general, a material having a small deflection value has high curability.

  Table 1 shows the characteristics (ortho fraction, softening point, yield) of the phenolic novolak resins obtained from Examples 1 to 6 and Comparative Examples 1 and 2 and the characteristics of the resin-coated sand using the same (flexural strength, curability). )showed that.

The ortho ratios of the phenol resins (phenol novolak resins) obtained in Comparative Examples 1 and 2 were 26% and 68%, and the yields were 69.2% and 58.8%, which were less than 70%. It was. And the resin coating sand using the phenol novolak resin of Comparative Examples 1 and 2 had a bending strength of 3.9 MPa or less and a deflection value of 4.4 mm or more.
On the other hand, the ortho ratio of the phenol resins (phenol novolak resins) obtained in Examples 1 to 6 is 40 to 55%, and the yield is 70.8 to 78.3%, which is 70% or more. there were. And the resin coat sand using the phenol novolak resins of Examples 1 to 6 has a bending strength of 4.1 MPa or more and a deflection value of 3.2 mm or less, which is higher in curability than the comparative example. I understood that I have it.

  By producing a resin-coated sand using the phenolic novolak resin obtained by the present invention, a phenolic novolak resin can be efficiently produced without the need for special production equipment, and the resin-coated sand has high curability. Can be obtained. Thereby, it becomes possible to shorten the manufacturing cycle at the time of mold making.

  Moreover, by using a metal compound as a catalyst and further using a chelating agent to deactivate the catalytic action of the metal compound, a phenol resin (phenol novolak resin) can be obtained with a suitable ortho ratio and high yield. It was. Therefore, it can be seen that the ortho ratio can be arbitrarily controlled by selecting the addition time of the chelating agent. On the other hand, when a metal compound (catalyst) or a chelating agent is not used, it can be seen that a product having a suitable ortho ratio cannot be obtained. Moreover, when a chelating agent is not used, it is found that it is difficult to control the ortho ratio and that the yield of phenol resin (phenol novolac resin) is low.

Claims (4)

At least in a resin coat sand composed of a refractory aggregate and a phenolic novolak resin having an ortho ratio of 30 to 60%, the phenolic novolak resin contains phenols and formaldehyde in the presence of a metal compound as a catalyst. The reaction is carried out at 100 to 160 ° C. for 0.01 to 6 hours, and then a chelating agent is added to deactivate the catalytic action of the metal compound, and then the reaction is further continued. The agent is ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), trans-1,2-cyclohexadiamine-N, N, N ′, N′-tetraacetic acid (CyDTA), diethylenetriamine-N, N, N ', N'-pentaacetic acid (DTPA), ethylenediaminediacetic acid (EDDA), iminodiacetic acid (IDA), hydroxy Ethyliminodiacetic acid (HIDA), ethylenediaminedipropionic acid (EDDP), ethylenediaminetetrakismethylenephosphonic acid (EDTPO), hydroxyethylethylenediaminetetraacetic acid (EDTA-OH), diaminopropanoltetraacetic acid (DPTA-OH), nitrilotrismethylenephosphonic acid One or more selected from (NTPO), bis (aminophenyl) ethylene glycol tetraacetic acid (BAPTA), nitrilotripropionic acid (NTP), dihydroxyethylglycine (DHEG), glycol ether diamine tetraacetic acid (GEDTA) Resin coatet sand characterized by   The phenol is one or more selected from phenol, cresol, xylenol, ethylphenol, phenylphenol, t-butylphenol, t-amylphenol, bisphenol A, and resorcinol. Resin coated sand.   The resin coat sand according to claim 1 or 2, wherein the formaldehyde is one or more selected from formalin, paraformaldehyde, and trioxane.   The metal compound is one or two or more selected from monovalent to hexavalent metal oxides, organic salts, inorganic salts, and hydroxides. Resin coated sand.