JP3173842B2 - Mold resin composition and method for producing mold using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a binder composition for a curable mold and a method for producing a sand mold for a casting in a self-hardening mold and a gas-curable mold molding method, and more particularly to a water-soluble phenol resin. Using the organic ester as a curing agent, in a binder composition used in a method for producing a sand mold for casting for molding a refractory particulate material, the reusability of the refractory particulate material is remarkable, and practically improved. And a binder composition for a curable mold.

[0002]

2. Description of the Related Art Recently, as a binder composition for improving casting quality and working environment, an organic self-hardening mold molding method and a gas-curable mold molding method in which a water-soluble phenol resin is used as a binder and this is cured with an organic ester. The binder composition for molding sand used in the method is disclosed in JP-A-50-130627, Patent No. 155403.
No. 0, Patent No. 1554031 and the like. Especially in the field of cast steel, binders centered on water glass, which is a method of molding sand molds for castings conventionally used,
That is, a part of the water glass / CO ₂ , water glass / dikal method is being converted to the mold making method. However, when the molding sand cast by the molding method using the water-soluble phenol resin is reused, the strength of the molded mold tends to gradually decrease. This is a completely opposite phenomenon as compared with the molding method using a furan resin. As a result, the molding method using a water-soluble phenol resin has a sand regenerating property (the mold once cast is broken down and re-formed as molding sand. It is well known that the ease of use is extremely poor and its use is limited, and improvement is strongly demanded.

[0003]

In such a binder composition, since the strength of the resulting mold is low, the amount of the resin must be increased in order to obtain the mold strength required for molding. One of the major drawbacks of this binder is that the more difficult it is to use recovered sand that has been cast and then reused, or to use recycled sand that has been used multiple times, the more difficult it is to maintain mold strength. However, there is a drawback that a vicious circle is likely to occur, such as an increase in the amount used for In addition, such an increase in the amount of the binder in the mold leads to an increase in the amount of pyrolysis gas at the time of pouring, and also has drawbacks such as gas defects in the casting and deterioration of the working environment. In order to reduce such defects as much as possible, generally remove residual organic substances and alkalis on the sand surface and perform mechanical polishing and regenerating treatment of the strength, and at the same time, increase the replenishment rate of fresh sand or At present, they are dealing with disposable items. For this reason,
When using foundry sand for recycling, the rate of sand regeneration is at most
The limit was about 85% (FOUNDRY TRADE JOURNAL-8
/ 22 DECEMBER 1989).

The difference in sand reproducibility becomes even more apparent when compared with the case of acid-curable furan resins, which are widely used. That is, in the case of an acid-curable furan resin, in general, the use of recycled sand can increase the strength of the mold as compared with the use of fresh sand. Since the polishing and regenerating process is not required, the recovery rate of the reclaimed sand is about 95% or more. Sand regeneration is also an important economic issue when making molds and cores from sand bound by a curable binder.

In order to reclaim sand from a mold or a core, after the casting is removed, the used mold and the core are broken up by mechanical vibration or decomposition to break up the sand, break up lumps or agglomerates, and remove the sand. to recover. Since the surface of the recovered sand contains unburned components of the binder, the sand is usually regenerated next. Generally, three methods (mechanical, wet, and thermal) are known as methods for reclaiming reclaimed sand. The wet regeneration method is a relatively unfavorable method due to the disposal problems associated with the wash water and the energy costs required to dry the sand, and the thermal regeneration method is relatively unfavorable due to the high energy cost of this method. This is an undesirable method. On the other hand, the mechanical regeneration method is the most economical, so it is most commonly used in the foundry industry and is a widely used regeneration method.

[0006] In the recycled sand thus obtained, the binder process of curing a water-soluble phenol resin with an organic ester has a drawback unique to the present process as described above in that sufficient mold strength cannot be obtained. Since it is completely different from the case of the widely used acid-curable furan resin, improvement is strongly desired. Recently, for the purpose of improving the strength of a mold using recycled sand, a method by lowering the resin solid concentration in the binder is disclosed in JP-A-1-262042, and the recycled sand is pre-treated with a silane solution in advance. The method is disclosed in Japanese Patent Application Laid-Open No. 1-262043. However, some of these methods improve the strength of the recycled sand,
Satisfactory mold strength cannot be obtained.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that
Of water-soluble phenol resin obtained by reacting phenols and aldehydes as binder, and organic ester as curing agent, used in the method of manufacturing sand mold for casting for molding refractory granular material In particular, by using a binder composition containing a specific amount of a specific metal element as a resin composition having a specific property, the resin composition is molded from a regenerated refractory granular material (hereinafter referred to as “regenerated sand”). It has been found that the strength of the obtained mold is greatly improved, and the present invention has been completed.

That is, the present invention relates to a method for producing phenol under alkaline conditions.
Water-soluble phenolic resin obtained by reacting phenols and aldehydes as binder, and organic ester as curing agent,
The properties of the binder composition used in the method for manufacturing a sand mold for casting for molding a refractory granular material containing recycled and / or recovered aggregate as a main component are as follows : (a) the resin has a weight average molecular weight of 500 ~
8,000, (b) solid content is 30 to 75% by weight, (c) the molar ratio of formaldehyde to phenol is 1.0 to 3.0, and (d) the molar ratio of alkali metal hydroxide such as potassium hydroxide and sodium hydroxide to phenol. Is 0.3 to 1.5, and
(e) An object of the present invention is to provide a binder composition for a curable mold, which contains 30 to 50,000 ppm of a divalent metal element with respect to a phenol-formaldehyde resin composition.
More preferably, (a) the phenol-formaldehyde resin has a weight average molecular weight of 1,000 to 5,000, (b) the solid content is 40 to 65% by weight, (c) the molar ratio of formaldehyde to phenol is 1.5 to 2.5, and (d) Potassium hydroxide to phenol, the molar ratio of an alkali metal hydroxide such as sodium hydroxide is 0.3 to 1.2, and (e) a divalent metal element is 100 to 30,000 ppm with respect to the phenol-formaldehyde resin composition. An object of the present invention is to provide a binder composition for a curable mold, characterized by being incorporated. When the properties (a), (b), (c), (d), and (e) of the resin are outside the above ranges, the mold strength tends to be greatly reduced.

The divalent metal element (e) used in the present invention will be described in more detail. The method for obtaining the binder composition of the present invention is as follows. , C
a, Sr, Ba, Zn, Cd, Sn, Pb for Group IV, Mn, V for Group VII
In Group III, a compound containing one or more metal elements selected from the group consisting of Fe, Co, and Ni is added to a water-soluble phenol resin and / or an organic ester as a metal element in an amount of 30 to
It is obtained by mixing and / or dissolving 50,000 ppm, preferably 100 to 30,000 ppm. The respective metal element concentrations are 50 to 50,000 ppm for Group IB Cu and 30 for Group IIA Mg.
~ 50000ppm, 50 ~ 50000ppm for Ca, 50 ~ 50000pp for Sr
m, 50 to 50000 ppm for Ba, 30 to 50000 pp for IIB group Zn
m, 50 to 50000 ppm for IVB group Sn, 50 to 5 ppm for VIIA group Mn
0000 ppm, 50-50,000 ppm for group VIII Fe, 50-500 for Co
00ppm, 50 ~ 50000ppm for Ni, 30 ~ 500 for total concentration
It is 00 ppm, preferably 100 to 30,000 ppm.

The form of the metal element-containing compound used in the present invention includes metal powder, oxide, hydroxide, inorganic acid salt,
There are various forms such as an organic acid salt and a complex compound, and any form can be used. It suffices that the metal element is contained in the binder composition, and is not limited to the form of the compound containing the metal element. Hereinafter, specific examples of the metal element and a compound containing the metal element will be described, but the invention is not limited thereto.

The metal alloy powder which is hydrated to take the form of a divalent metal includes ferronickel, magnalium, ferromanganese and the like. More specifically, typical examples of the compound containing a divalent metal element include salts and double salts,
Hydroxides, oxides, organometallic compounds in which a hydrocarbon group such as an alkyl group or an aryl group is bonded to a metal atom, a nitride,
Alkoxides, hydrides, carbides, metal imides, peroxides, sulfides, phosphides, nitrates, anilides, phenolates, hexaammonides, ferrocene and its analogous compounds, dibenzenechromium and its analogous compounds, inorganic heteropolymers, metals Examples include carbonyl, metal-containing enzymes, clathrate compounds, metal complexes, chelate compounds, and coordination polymers.

A typical structure of a salt, hydroxide or oxide containing the metal element is represented by the following general formula. MaXb (wherein, M is a divalent metal element, X is an oxygen atom or a hydroxyl group, an anion atom of an inorganic acid or an anion atom of an organic acid, or an anion atom of an acid exhibiting sequestering properties. A and b each represent an integer of 1 or more.)
As for M, similarly to the above, Cu for Group IB, Mg, for Group II,
Ca, Sr, Ba, Zn, Cd, Sn, Pb for Group IV, Mn, for Group VII
In the group VIII, Fe, Co, Ni and the like can be mentioned, but B, Si, As, Te and the like which are usually called semimetals are not preferable.

Specific examples of X include an oxygen atom, a hydroxyl group, and halogens (F, Cl, Br, etc.) as an anionic group of an inorganic acid.
, SO ₄ , SO ₃ , S ₂ O ₃ , S ₂ O ₆ , SiF ₆ , MoO ₄ , MnO ₄ , N
_{O 3, NO 2, ClO 3} , ClO, CO 3, HCO 3, CrO 4, IO 3, P
_{O 3, PO 4, HPO 3} , HPO 4, H 2 PO 4, P 2 O 7, H 2 PO 2, Si
O ₃ , BO ₂ , BO ₃ , B ₄ O ₇ , Fe (CN) _{6 and the} like. Examples of the anionic group of the organic acid include anionic groups of carboxylic acids such as formic acid, acetic acid, oxalic acid, lactic acid, tartaric acid, and benzoic acid, and sulfamic acid, xylenesulfonic acid, toluenesulfonic acid, and phenol. Sulfonic acid,
Anionic groups of organic sulfonic acids such as benzenesulfonic acid and alkylbenzenesulfonic acid are exemplified. Further, anionic groups of organic phosphoric acids such as methylphosphoric acid and ethylphosphoric acid are exemplified.

Representative compounds used in the present invention as such salts, double salts and hydroxides include the following. As salts, calcium chloride, magnesium chloride, barium chloride, copper chloride, zinc chloride, calcium bromide, vanadium chloride, molybdenum chloride, manganese chloride, iron chloride, nickel chloride, calcium sulfate, calcium carbonate, magnesium phosphate, calcium phosphate, Tin chloride, calcium formate, magnesium oxalate, calcium toluenesulfonate, magnesium acetate, zinc acetate,
There are zinc lactate and the like.

As the hydroxide, calcium hydroxide,
Examples include magnesium hydroxide and zinc hydroxide. Examples of the oxide include magnesium oxide, calcium oxide, barium oxide, zinc oxide, nickel oxide, and the like. Further, a complex compound composed of a combination of two or more of these oxides and the oxidation of the oxide and other elements A double compound composed of a combination with a substance or a salt is preferably used.

Typical examples of the compound used in the present invention include the following. Cement includes hydraulic lime, Roman cement, natural cement, Portland cement, blast furnace cement, silica cement, fly ash cement, masonry cement, expansive cement, special cement, etc. , Ferrochrome dregs,
There are Ca bentonite, its main representative chemical structure _{mCaO · nSiO 2, mCaO · nAl} 2 O 3, mBaO · nAl 2 O
_{3, CaO · mAl 2 O 3} · nSiO 2, CaO · mMgO · nSiO 2,
mCaCO ₃ · nMgCO ₃ , mCaO · nFe ₂ O ₃ , lCaO · mAl ₂
O ₃ .nFe ₂ O ₃ (where l, m, and n are represented by a combination of 0 or an integer of 1 or more). The oxide or composite compound includes other clay raw materials, iron oxide raw materials and other mineral raw materials. When the oxide is used, the particle size is preferably as small as possible, and the average particle size is usually 200 μm or less, preferably 50 μm or less.

Examples of the organometallic compound in which a hydrocarbon atom such as an alkyl group or an aryl group containing the divalent metal element is bonded to a metal atom are as follows. Zn (C ₆ H ₅ )
₂ , Grignard reagents such as (CH ₂ = CH) ₂ Zn, Ca (C ₂ H ₅ ) ₂ and R-Mg-X (R: alkyl or aryl group, X: halogen). Examples of the divalent metal alkoxide containing the metal element include Zn (OCH ₃ ) ₂ . Examples of the hydride containing the divalent metal element include CaH ₂ and BaH ₂ . CaC ₂ containing the divalent metal element is exemplified. Examples of the metal imide containing the divalent metal element include Ca (NH ₂ ) ₂ . As the peroxide containing the divalent metal element, CaO ₂ ,
BaO ₂ , BaO _{4 and the} like can be mentioned. Examples of the sulfide containing the divalent metal element include ZnS, Cu ₂ S, and CuS. Examples of the nitrate containing the divalent metal element include CuNO ₂ . Zn-phenolate containing the divalent metal element,
Ca-phenolate and the like can be mentioned. Examples of hexaammonides containing the divalent metal element include Ca (NH ₃ ) ₆ . Ferrocene and its analogous compounds containing the divalent metal element include ferrocene (Fe (C ₅ H ₅ ) ₂ ), Zn (C ₅ H ₅ ) ₂ ,
_{Ni (C 5 H 5) 2} , Mn (C 5 H 5) 2 and the like. Examples of the inorganic heteropolymer containing the divalent metal element include the following. Hydrogenated inorganic heteropolymers such as beryllium hydride polymer and magnesium hydride polymer. Examples of the inclusion compound containing the divalent metal element include cyclic polyether (crown ether), cyclic polyamine (azacrown compound), cyclic polythiaether (thiacrown compound), composite donor crown compound, and bicyclic crown compound (Cryptand), polymer crown compound, cyclic phenol (caxarene), complex with cyclodextrin derivative and the like. For example, dibenzo-18-crown-6 and Ca ²⁺
Complex (complex salt compound) with cryptad [2.2.2]
Complexes with Ca ²⁺ and the like.

Examples of the metal complex containing the divalent metal element include Cl ⁻ , CN ⁻ , NCS ⁻ , SO ₄ ²⁻ , NO ₂ ⁻ , ONO ⁻ , and NO.
_{^{3 -, HCOO -, C 2}} O 4 2-, CO 3 2-, OH -, H 2 N · CH 2 · CO
^{O -, F -, Br -} , ONO -, I -, NH 2 -, SCN - anionic and / or the _{like, H 2 N · CH 2 ·} CH 2 NH 2, C 6 H 5 N, N
Neutral ligands such as H ₃ and H ₂ O and / or H ₂ N · NH ³⁺ , H ₂ N
・ It has a cationic ligand such as CH ₂ , CH ₂ , NH ₃ ⁺ , and is selected from coordination numbers 2 to 8. For example, [Zn (NH ₃ ) ₆ ] Cl ₂ It is. Other compounds containing the divalent metal element include Ni (CO) ₄ and Mn ₂ (CO)
Metal carbonyls such as ₁₀ and metal-containing enzymes such as carboxypeptidase A and thermolysin.

Further, a sequestering compound containing the divalent metal element may be used. Examples of such sequestering compounds include the following. Representative acetic acid type aminocarboxylic acid type is ethylenediaminetetraacetic acid (EDTA) or a salt thereof, nitrilotriacetic acid (NTA) or a salt thereof, trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) or a salt thereof, Diethylenetriaminepentaacetic acid (DTPA) or salts thereof, triethylenetetraminehexaacetic acid (TTHA) or salts thereof, glycol ether diaminetetraacetic acid (GEDTA) or salts thereof, iminodiacetic acid (IDA) or salts thereof, polyalkylenediaminetetraacetic acid or The salts thereof, and N-hydroxyalkylene iminodiacetic acid or salts thereof are typically phenyl aminocarboxylic acid type, 2-oxyphenyliminodiacetic acid or salts thereof,
Phenyliminodiacetic acid or salts thereof, 2-oxybenzyliminodiacetic acid or salts thereof, benzyliminodiacetic acid or salts thereof, and N, N'-ethylenebis- [2- (O-hydroxyphenyl)] glycine or salts thereof However, a typical aminocarboxylic acid type having a mercaptan group is β-mercaptoethyliminodiacetic acid or a salt thereof, and a typical aminocarboxylic acid type having an ether bond is ethyl ether diamine tetraacetic acid or A typical example of the aminocarboxylic acid type having a thioether bond is ethylthioetherdiaminetetraacetic acid or a typical example of the aminocarboxylic acid type having a sulfonic acid group is β-aminoethylsulfone. Acid-N, N
A typical example of an aminocarboxylic acid type in which diacetate or a salt thereof has a phosphonic acid group is a typical example of an aminocarboxylic acid type in which nitrilodiacetate-methylenephosphonic acid or a salt thereof has a peptide bond; N, N'-diglycylethylenediamine-N ', N'',N''', N ''''-tetraacetic acid or a salt thereof is a typical oxycarboxylic acid type,
Gluconic acid or a salt thereof, citric acid or a salt thereof, and tartaric acid or a salt thereof, and more typical phosphoric acid types include tripolyphosphoric acid or a salt thereof, hydroxyethanediphosphonic acid (HEDP) or a salt thereof, and Examples include nitrilotristyrene phosphonic acid (NTP) or salts thereof, and acetylacetone.

The coordinating polymer having a sequestering ability includes an amine group and / or a nitrogen heterocycle, and / or a Schiff base, and / or an alcohol, a carboxylic acid, and / or a ketone in the molecule. , Esters, amides, and / or aminocarboxylic acids, and / or phosphonic acids, and / or phosphines, and / or polymers having thiols. Among the metal elements described in these specific examples, preferred are Mg, Ca, Ba, Zn,
The group IV is Sn, and the group VIII is Fe, Co, Ni, and among them, Zn, Mg, Ca, and Ni are particularly preferable.

Incidentally, the determination of the metal element in the binder is generally carried out as follows. [Quantitative determination of metal element in binder] The binder is thoroughly mixed and stirred, and 0.5 to 0.8 g is weighed in a 100 ml platinum dish. To this, 10 ml of concentrated nitric acid is added, and after acid decomposition, it is subjected to weak thermal decomposition. HClO ₄ 10m
l and white smoke treatment to bring the residual HClO ₄ to 3 ml. After allowing to cool, 10 ml of HCl (1 + 1, concentration 50%) + 10 ml of H ₂ O are added and dissolved by heating. This is filtered (No5C filter paper) and washed with dilute hydrochloric acid + warm water. The residue remaining on the filter paper is ashed in a 30 ml platinum crucible at 900 to 1000 ° C., then allowed to cool, 2 g of potassium pyrosulfate is added, and the mixture is acid-melted at 800 ° C. Combine the extract from the melt with the previous filtrate and add
And the metal element is determined by ICP (inductively coupled plasma emission spectrometry).

The water-soluble phenolic resin used in the present invention is a resin curable with an organic ester. For example, phenols including phenol, cresol, resorcinol, 3,5-xylenol, and other substituted phenols can be used in a large amount. It is obtained by reaction with an aldehyde such as formaldehyde or paraformaldehyde or a mixture thereof in an aqueous solution of an alkaline substance. Alternatively, a bisphenol-formaldehyde resin may be blended with these resins. Further, a monomer capable of formalin condensation such as urea, melamine, cyclohexanone and the like may be co-condensed to such an extent that it does not become a main constituent unit in weight ratio.

Suitable alkaline substances used in the production of these water-soluble phenolic resins are alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide and mixtures thereof. Potassium oxide is most preferred. The water-soluble phenol resin containing the metal element can be obtained by adding a compound containing the metal element at any stage of producing the resin. That is, the compound containing the metal element is dissolved or mixed in advance with the phenol, and then the polycondensation reaction with the aldehyde is carried out. Can be obtained by dissolving or mixing a compound containing The water used for synthesizing or blending the water-soluble phenol resin may contain or add a predetermined amount of the metal element according to the present invention. The content of the metal compound as a metal element is 30 to 50,000 ppm, and preferably 100 to 50,000 ppm.
~ 30,000 ppm. If the content is less than 30 ppm, the effect of the present invention will not be sufficient, while if it exceeds 50,000 ppm, the effect will be in a saturated region, which is not preferable.

It has never been known that the use of the binder composition of the present invention containing such a metal element significantly improves the strength of recycled sand. On the other hand, a metal ion is known as a catalyst for forming a benzyl ether bond at an ortho position between phenol nuclei of phenols. For example, Japanese Patent Publication No. 47-50873 and U.S. Pat.
No. 5,797, JP-B-54-15797, JP-B-60-23769, etc. describe Group II elements or transition elements.
However, the metal element in these known techniques is a catalyst necessary for causing a resolation or benzyl etherification reaction, but the obtained resole resin is classified as a thermosetting solid resole resin. , The fields of use and the curing mechanisms are completely different. That is, the water-soluble phenolic resin referred to in the present invention is cured by an organic ester as a curing agent triggered by a hydrolysis reaction in a resin exhibiting strong alkalinity, and is cured with the solid resol resin described above. The mechanism is completely different.
In fact, even if an organic ester is added to the resin found in the above-mentioned known documents, no curing reaction is induced due to insufficient alkalinity. Therefore, these known techniques do not correspond to the prior art of the present invention.

Japanese Unexamined Patent Publication (Kokai) No. 2-261815 discloses a benzyl ether type resin obtained by subjecting a phenol and a formaldehyde to a condensation reaction in the presence of a divalent metal ion under an acidic condition of pH 7 or less, and then obtaining an excess of alkali. In the presence, unreacted formaldehyde is reacted and the phenol nucleus is converted to methylol to obtain a benzyl ether type organic ester-curable water-soluble resol resin. The purpose of the metal ion in the known technique is a catalyst for the purpose of forming a benzyl ether bond between ortho positions of phenol nuclei, and a benzyl ether type water-soluble resole resin [NMR (Can be confirmed by (nuclear magnetic resonance) analysis) is compared with a known water-soluble phenol resin having a methylene-type bond between phenol nuclei produced under strong alkaline conditions using an alkali metal as a synthesis catalyst. However, it is not improved by focusing on the problem of the water-soluble phenol resin in the recycled sand. In this respect, it is decisively different from the present invention.

As the organic ester 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 alone or in a mixture is used. In the self-hardening molding method, it is preferable to use γ-butyrolactone, propionlactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, etc., and in the gas-curing molding method, methyl formate is used. Is preferred.

Examples of the refractory granular material include quartz sand, chromite sand, zircon sand, olivine sand, and alumina sand mainly composed of quartz. In the present invention, as these refractory granular materials, either new sand or regenerated sand can be used, but the effect of improving the mold strength is particularly remarkable when regenerated sand is used. When using reclaimed sand, the reclaimed sand used is one that can be obtained by ordinary abrasion or roasting.
The method for obtaining the recycled sand is not particularly limited. In the binder composition of the present invention, conventionally known silane coupling agents can be used as other additives. Specific examples thereof include γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like. In the present invention, it is preferable to use this silane coupling agent together with a binder composition.

In producing a sand mold for casting by the self-hardening molding method using the binder composition of the present invention, a known method is employed. For example, in 100 parts by weight of recycled sand, 0.05 to 9 parts by weight, preferably 0.1 to 5 parts by weight, of an organic ester of a curing agent, which is a component of the binder composition according to the present invention, and 0.4 to 0.4 parts by weight of a water-soluble phenol resin aqueous solution 15 parts by weight, preferably 0.6 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.

[0029]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Synthesis Example 1 255 parts by weight of water, 267 parts by weight of phenol, and 34 parts by weight of magnesium salt of ethylenediaminetetraacetate, which is a divalent metal element compound, were added to a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer. Heat on bath, 85 ° C
For 30 minutes. Then, after adding 282 parts by weight of 48% potassium hydroxide, 158 parts by weight of 92% paraformaldehyde were added over 1 hour. After continuing the reaction at the same temperature to obtain a resin solution having a weight average molecular weight of 350, 4.0 g of γ-aminopropyltriethoxysilane was added to obtain a resin solution sample containing 1,931 ppm as a magnesium element.

Synthesis Example 2 According to Synthesis Example 1, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 530, and 4.0 g of γ-aminopropyltriethoxysilane was added in the same manner. A resin solution sample containing ppm was obtained.

Synthesis Example 3 According to Synthesis Example 1, the reaction was further continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 1060. Similarly, 4.0 g of γ-aminopropyltriethoxysilane was added, and 1,931 as a magnesium element was added. A resin solution sample containing ppm was obtained.

Synthesis Example 4 According to Synthesis Example 1, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 3,620. Similarly, 4.0 g of γ-aminopropyltriethoxysilane was added, and 1,931 as a magnesium element was added. Resin solution sample containing ppm (solid content
49%). Thereafter, the resin solution sample was placed in an eggplant flask and kept at 65 ° C., and the pressure was reduced to 5 mmHg by an evaporator to evaporate the water.
59%, 68% and 74% were obtained. In addition, the resin solution sample of low solid content was obtained by using the resin solution sample of Synthesis Example 4,
Dilution with water gave solids of 25%, 31% and 40% respectively.

Synthesis Example 5 According to Synthesis Example 1, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 7570, and 4.0 g of γ-aminopropyltriethoxysilane was added in the same manner. A resin solution sample containing ppm was obtained.

Synthesis Example 6 According to Synthesis Example 1, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 9350. Similarly, 4.0 g of γ-aminopropyltriethoxysilane was added, and 1,931 as a magnesium element was added. A resin solution sample containing ppm was obtained.

Synthesis Example 7 264 parts by weight of water, 277 parts by weight of phenol, and 292 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Then 92% paraformaldehyde
163 parts by weight were added over 1 hour. After continuing the reaction at the same temperature to obtain a resin solution having a weight average molecular weight of 350, a resin solution sample to which 4 parts by weight of γ-aminopropyltriethoxysilane was added was obtained.

Synthesis Example 8 According to Synthesis Example 7, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 530, and then a resin solution sample to which 4 parts by weight of γ-aminopropyltriethoxysilane was similarly added. I got

Synthesis Example 9 According to Synthesis Example 7, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 1060, and then a resin solution sample to which 4 parts by weight of γ-aminopropyltriethoxysilane was similarly added. I got

Synthesis Example 10 According to Synthesis Example 7, a resin solution sample having a weight average molecular weight of 3,620 without adding a divalent metal compound was obtained. Thereafter, the resin solution sample was placed in an eggplant flask and kept at 65 ° C., and the pressure was reduced to 5 mmHg by an evaporator to evaporate water, thereby obtaining a resin solution sample having a solid content of 59%, 68% and 74%, respectively. . A resin solution sample having a low solid content was prepared in Synthesis Example 4.
Was diluted with water to obtain 25%, 31% and 40% solids, respectively.

Synthesis Example 11 According to Synthesis Example 7, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 7570, and then a resin solution sample to which 4 parts by weight of γ-aminopropyltriethoxysilane was similarly added. I got

Synthesis Example 12 According to Synthesis Example 7, the reaction was further continued at the same temperature to obtain a resin solution having a weight average molecular weight of 9350, and a resin solution sample to which 4 parts by weight of γ-aminopropyltriethoxysilane was similarly added. I got

Synthesis Example 13 263 parts by weight of water, 275.5 parts by weight of phenol, and 291 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Thereafter, 47.8 parts by weight of 92% paraformaldehyde were added over 18 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight average molecular weight of 2300, followed by cooling. Then, 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane were added to obtain a resin solution sample (formaldehyde / phenol). Molar ratio = 0.5).

Synthesis Example 14 263 parts by weight of water, 275.5 parts by weight of phenol and 291 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Thereafter, 95.5 parts by weight of 92% paraformaldehyde were added over 35 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2300, followed by cooling, and adding 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane to obtain a resin solution sample (formaldehyde / phenol). the molar ratio of = 1.0) synthesis
Example 15 To a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, 263 parts by weight of water, 275.5 parts by weight of phenol and 291 parts by weight of 48% potassium hydroxide were added, and the mixture was heated and maintained at 85 ° C. while stirring. did. Thereafter, 163 parts by weight of 92% paraformaldehyde were added over 60 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2300, followed by cooling, and adding 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane to obtain a resin solution sample (formaldehyde / phenol). Molar ratio = 1.7).

Synthesis Example 16 263 parts by weight of water, 275.5 parts by weight of phenol, and 291 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a hot water bath with stirring. Maintained at 85 ° C. Thereafter, 286.5 parts by weight of 92% paraformaldehyde were added over 105 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2300, followed by cooling, and adding 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane to obtain a resin solution sample (formaldehyde / phenol). Molar ratio = 3.0).

Synthesis Example 17 263 parts by weight of water, 275.5 parts by weight of phenol and 291 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a hot water bath with stirring. Maintained at 85 ° C. Thereafter, 382 parts by weight of 92% paraformaldehyde were added over 140 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2300, followed by cooling, and adding 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane to obtain a resin solution sample (formaldehyde / phenol). Molar ratio = 4.0).

Synthesis Example 18 263 parts by weight of water, 275.5 parts by weight of phenol and 68.5 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Thereafter, 163 parts by weight of 92% paraformaldehyde were added over 60 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2,300, followed by cooling. Then, 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane were added to obtain a resin solution sample (potassium hydroxide). / Phenol molar ratio = 0.2).

Synthesis Example 19 263 parts by weight of water, 275.5 parts by weight of phenol and 514 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Thereafter, 163 parts by weight of 92% paraformaldehyde were added over 60 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2,300, followed by cooling. Then, 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane were added to obtain a resin solution sample (potassium hydroxide). / Phenol molar ratio = 1.5).

Synthesis Example 20 263 parts by weight of water, 275.5 parts by weight of phenol, and 1369 parts by weight of 48% potassium hydroxide were added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and heated on a water bath with stirring. Maintained at 85 ° C. Then 92% paraformaldehyde
163 parts by weight were added over 60 minutes. The reaction was continued at the same temperature to obtain a resin solution having a weight-average molecular weight of 2,300, followed by cooling. Then, 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane were added to obtain a resin solution sample (potassium hydroxide). / Phenol molar ratio = 4.0).

Examples 1 to 20 In accordance with Synthesis Example 4, divalent metal compounds shown in Table 1 were added.
A resin solution containing a divalent metal element was obtained, a test piece for an anti-pressure test was prepared according to a predetermined method, and the mold strength after preparation was measured. Table 1 shows the results.

Comparative Example 1 A resin solution containing no divalent metal element was obtained according to Synthetic Example 10, a test piece for coercive pressure test was prepared according to a predetermined method, and the mold strength after preparation was measured. Table 1 shows the results.

Comparative Example 2 A water-soluble phenol resin solution (solid content: 40%) was obtained according to the description in Examples of JP-A-1-262042, and a test piece for an anti-pressure test was prepared and prepared according to a predetermined method. The strength of the subsequent mold was measured. Table 1 shows the results.

Comparative Example 3 Sand was treated according to the method described in Examples of JP-A 1-262043. That is, a 40% aqueous solution of γ-aminopropyltriethoxysilane was previously added to 100 parts by weight of the reclaimed sand.
After treatment at 25 ° C. by adding 0.024 parts by weight, a test piece for a pressure resistance test was prepared according to a predetermined method, and the mold strength after preparation was measured. Table 1 shows the results.

[0052]

[Table 1]

Examples 21 to 24 Resin solutions containing a divalent metal element were obtained according to Synthesis Examples 2 to 5, test pieces for coercive force tests were prepared according to a predetermined method, and the mold strength after preparation was measured. . Table 2 shows the results.

Comparative Examples 4 and 5 A resin solution containing a divalent metal element was obtained according to Synthetic Examples 1 and 6, test pieces for coercive pressure tests were prepared according to a predetermined method, and the mold strength after preparation was measured. . Table 2 shows the results
Shown in

Comparative Examples 6 to 11 Resin solutions containing no divalent metal element were obtained in accordance with Synthesis Examples 7 to 12, test pieces for coercive pressure tests were prepared according to a predetermined method, and the mold strength after preparation was measured. . Table 2 shows the results
Shown in

[0056]

[Table 2]

Examples 25-29 Resins containing divalent metal elements having a solid content of resin solution samples of 31%, 40%, 49%, 59%, 68% and 74%, respectively, according to Synthesis Example 4. A solution was obtained, a test piece for an anti-pressure test was prepared according to a predetermined method, and the strength of the mold after preparation was measured. Table 3 shows the results.

Comparative Examples 12 and 13 A resin solution containing a divalent metal element having a solid content of 25% and 76%, respectively, of a resin solution sample was obtained according to Synthetic Example 4 and subjected to a pressure test according to a predetermined method. Test pieces were prepared and the mold strength after preparation was measured. Table 3 shows the results.

Comparative Examples 14 to 20 According to Synthesis Example 10, the solid content of the resin solution sample was 25%, 31%, 40%, 49%, 59%, 68% and 74%, respectively.
A resin solution containing no valent metal element was obtained, a test piece for a coercive force test was prepared according to a predetermined method, and the mold strength after preparation was measured. Table 3 shows the results.

[0060]

[Table 3]

Examples 30 to 32 According to Synthesis Examples 14 to 16, the formaldehyde / phenol molar ratio was adjusted to 1.0, 1.7 and 3.0, respectively, and
A resin solution containing a valent metal element was obtained, a test piece for an anti-pressure test was prepared according to a predetermined method, and the strength of the prepared mold was measured. Table 4 shows the results.

Comparative Examples 21 and 22 According to Synthetic Examples 13 and 17, the molar ratio of formaldehyde / phenol was adjusted to 0.5 and 4.0, respectively, and a resin solution containing a divalent metal element was obtained. A test piece for a pressure test was prepared, and the time-dependent change in the mold strength after the preparation was measured. Table 4 shows the results.

[0063]

[Table 4]

Examples 33 and 34 According to Synthesis Examples 16 and 19, the molar ratio of potassium hydroxide / phenol was adjusted to 0.85 and 2.0, respectively, and a resin solution containing a divalent metal element was obtained. A test piece for an anti-pressure test was prepared according to the above procedure, and the mold strength after the preparation was measured. Table 5 shows the results.

Comparative Examples 23 and 24 According to Synthesis Examples 18 and 20, the molar ratio of potassium hydroxide / phenol was adjusted to 0.2 and 4.0, respectively, and a resin solution containing a divalent metal element was obtained. A test piece for an anti-pressure test was prepared according to the above procedure, and the mold strength after the preparation was measured. Table 5 shows the results.

[0066]

[Table 5]

Examples 35 to 53 In accordance with Synthesis Example 4, divalent metal compounds shown in Table 6 were added.
A resin solution containing a divalent metal element is obtained, and a test piece for an anti-pressure test is formed according to a gas-curable mold molding method.
The mold strength after the preparation was measured.

Comparative Example 25 A resin solution containing no divalent metal element was obtained according to Synthesis Example 10, and a test piece for an anti-pressure test was prepared according to a gas-curable mold molding method, and the mold strength after preparation was measured. Table 6 shows the results.

[0069]

[Table 6]

[Measurement Method of Self-Hardening Mold Strength] With respect to 100 parts by weight of reclaimed sand in which the type of sand is Fremantle silica sand, 0.375 parts by weight of triacetin was used. Min 49%, weight average molecular weight
3620) was added to 1.5 parts by weight of the mixture and kneaded to obtain a mixture of 50 mmφ × 50 mm
The test piece was filled into the test piece model of h and the pressure resistance after kneading was measured.

[Method of Measuring Gas-Curable Mold Strength] 100 parts by weight of reclaimed sand in which the kind of sand is Fremantle silica sand was used, and the water-soluble phenolic resin (solid content: 49%, weight: A mixture obtained by adding and kneading 1.5 parts by weight of an average molecular weight of 3620) was filled into a 50 mmφ × 50 mmh model for a test piece for gas hardening, and gaseous methyl formate was gassed at 50 parts by weight with respect to a water-soluble phenol resin. The pressure resistance of the piece was measured.

[Preparation method of reclaimed sand] Triacetin as a hardening agent was added to 100 parts by weight of fresh sand of Fremantle silica sand.
0.375 parts by weight, γ-aminopropyltriethoxysilane
1.5% water-soluble phenolic resin (solid content 49%, weight average molecular weight 2300) containing 0.5% by weight (based on phenolic resin)
Using a mold molded from the mixture kneaded by weight,
-25 (S / M = 3.5) was cast, and the collected sand was crushed and regenerated (A regeneration, 2 passes) using an M-type rotary cramer manufactured by Nippon Casting. The reclaimed sand obtained by repeating the above steps five times was used for the preparation for the above mold strength test.

[Measurement Method of Weight Average Molecular Weight] (a) A proper amount of water is added to a sample, and H ₂ SO ₄ is added to neutralize the sample.
The precipitate formed is separated by filtration, washed with water and dried. This was dissolved in tetrahydrofuran (THF) to prepare a sample for GPC. (b) Column [manufactured by Shimadzu Corporation] Guard column: Shim-pack GPC-800P (4.6 mmφ × 1.0 cm)
One measurement column: Shim-pack GPC-801, GPC-802, GPC-804
(8.0mmφ × 30cm) 3 columns Connection method: Guard column, Shim-pac from entrance and exit
k Connect in the order of GPC-804,802,801. (c) Standard substance Polystyrene [manufactured by Tosoh Corporation] (d) Eluent THF, flow rate: 1 ml / min (pressure: 40 to 70 kg / cm ² ) (e) Column temperature 40 ° C (f) Detector RI (g ) Division method for molecular weight calculation Time division (10 seconds) [Measurement results] Table 1 Table 1 shows a mold produced by a self-hardening mold molding method, while Comparative Examples 2 and 3 add a divalent metal element. Although some effects are recognized as compared with Comparative Example 1 which is not hampered, it can be seen that Examples 1 to 20 in which a specific divalent metal element is added have remarkably improved mold strength. Table 2 Table 2 shows the results of mold molding by a self-hardening mold molding method. The specific divalent metal element was added, and the weight average molecular weight was 350 and 9,350. Add a valent metal element, weight average molecular weight is 530 ~
7,570 of Examples 21 to 24 showed remarkably improved mold strength, and Comparative Example 6 in which no divalent metal element was added.
It can be seen that No. 11 is inferior in mold strength. Table 3 Table 3 shows the results of the mold making by the self-hardening mold making method. The divalent metal element was added, and the solid content was 25% and 76%.
From those of Comparative Examples 12 and 13, the solid content 31 of Examples 25 to 29
Up to 68% have excellent mold strength improvement
It can be seen that a remarkable effect is recognized even when compared with 14 to 20. Table 4 Table 4 shows the results of mold molding by a self-hardening mold molding method. Comparative examples 21 and 22 were prepared by adding a specific divalent metal element and adjusting the molar ratio of formaldehyde / phenol to 0.5 and 4.0. It can be seen that the molds of Examples 30 to 32, in which the molar ratio of formaldehyde / phenol was adjusted to 1.0, 1.7, and 3.0, respectively, were more excellent in mold strength than those of 22. Table 5 Table 5 is a comparative example in which a specific divalent metal element was added and the molar ratio of potassium hydroxide / phenol was adjusted to 0.2 and 4.0 by molding using a self-hardening molding method. From those of Examples 21 and 22, it can be seen that those of Examples 33 and 34 in which the molar ratio of potassium hydroxide / phenol was adjusted to be 0.2 and 4.0 were excellent in the improvement of the mold strength. Table 6 Table 6 shows the results of mold molding by the gas-curing mold molding method, but Examples 35 to 53 show specific divalent metal elements in Examples 35 to 53 as compared with those of Comparative Example 25 in which a divalent metal element was not added. It can be seen that by adding at a specific concentration, the improvement of the mold strength is excellent.

[0074]

As is clear from the above Examples and Comparative Examples, a binder obtained by adding and adjusting a specific divalent metal element to a specific concentration to a water-soluble phenol resin having a specific property is used as a binder. By using molds made of recycled sand and / or recovered sand as the main component as refractory aggregates, mold strength is remarkably improved, and the amount of binder added is reduced. It is possible to manufacture a casting with few gas defects and the like.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-262042 (JP, A) JP-A-2-4884 (JP, A) JP-A-64-40136 (JP, A) JP-A-63- 212035 (JP, A) JP-A-62-252633 (JP, A) JP-A-58-154434 (JP, A) JP-A-58-154433 (JP, A) JP-A-2-184561 (JP, A) JP-A-2-261815 (JP, A) JP-A-1-166853 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22C 1/00-1/26

Claims (5)

(57) [Claims] A phenol and an aldehyde under alkaline conditions.
After regeneration in a mold production method in which a water-soluble phenolic resin obtained by reacting hydrides is cured with an organic ester and
<br> A resin composition for a mold having the following properties, used together with a refractory aggregate mainly composed of recovered aggregate . (a) The resin has a weight average molecular weight of 500 to 8,000 (b) The solid content is 30 to 75% by weight (c) The molar ratio of formaldehyde to phenol is 1.0
3.0 to (d) The molar ratio of alkali metal hydroxide to phenol is 0.3 to 1.5 (e) At least one or more divalent metal elements are contained in the resin composition at 30 to 50,000 ppm. 2. The bivalent metal element is Cu or IIA of Group IB of the periodic table.
Group Mg, Ca, Sr, Ba, group IIB Zn, group IVB Sn, group VIIA
The resin composition for a mold according to claim 1, wherein the resin composition is one or more selected from the group consisting of Mn, VIII group Fe, Co, and Ni, and the concentration in the resin composition is 100 to 30,000 ppm. 3. A binder composition for a mold, further comprising an organic ester in the resin composition for a mold according to claim 1 or 2. Re 4. A foundry binder composition of claim 3, wherein
A mold composition comprising a refractory aggregate mainly composed of aggregate after birth and / or after recovery . 5. A method for producing a mold, comprising using the binder composition for a mold according to claim 3.