JP3092981B2 - Resin composition for mold, binder composition for mold, mold composition, and method for producing mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin composition for a mold and a sand mold for a casting in a self-hardening mold and a gas-curable mold molding method, and more particularly to a method of curing a water-soluble phenol resin with an organic ester . For casting molds used in the production method of sand molds for castings to make refractory granular materials
In a resin composition, reusability of a refractory particulate material is remarkably improved, and a mold resin composition containing the same is provided.
The present invention relates to a method for producing an agent composition, a mold composition, and a sand mold for casting.

[0002]

2. Description of the Related Art As a molding method for producing a mold such as a main mold or a core using an organic binder, a self-hardening mold method, a cold box mold method, and a cloning method (shell method) are known. In particular, the organic self-hardening molding method is already a general-purpose molding method in place of the inorganic type from the viewpoint of productivity, casting quality, safety and health mainly in the field of mechanical casting. On the other hand,
In order to produce a mold at a medium and high speed, a cloning method of producing a mold by heating and curing a so-called coated sand in which a phenol resin is coated on a granular refractory is widely used. However, in order to improve energy saving during mold production, mold production speed, and quality of molds and castings, cold box mold method of curing at room temperature with gaseous or aerosol-like materials is a casting method as an alternative to cloning method. The industry has been seriously trying to introduce it. Recently, as a binder composition to improve casting quality and work environment, a casting used in organic self-hardening mold molding method and gas-curable mold molding method in which a water-soluble phenol resin is used as a binder and cured with an organic ester. The binder composition for sand is disclosed in JP-A-50-13
No. 0627, JP-A-58-154433, JP-A-58-1544
No. 34, etc. became known. In the mold making method using this binder, unlike conventional acid-curing binders, since the binder composition does not contain sulfur or nitrogen elements, the working environment due to the generation of sulfurous acid gas during pouring Although there is no contamination of the casting or the casting has few defects due to sulfur and nitrogen elements, the recyclability of the binder type molding sand is extremely poor, and its use is limited. Some things are well known, and there is a strong demand for improvement.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. In such a binder composition, since the strength of the obtained mold is low, the amount of the resin added has to 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, in order to remove residual organic matter and alkali on the sand surface, strong mechanical polishing and regeneration treatment is performed, and at the same time, the proportion of fresh sand replenished is increased. At present, they are dealing with disposable items. For this reason,
When foundry sand is used for recycling, the sand recycling rate is at most about 85% (FOUNDRY TRADE JOURNAL-
8 / 22DECEMBER 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, the use of recycled sand generally increases the strength of the mold as compared with fresh sand, so the amount of binder added is slightly reduced in the recycled sand system. In addition, since a high-strength mechanical polishing and regeneration treatment is not required, the recovery rate of the recycled sand is about 95% or more. Sand regeneration is an important economic issue when producing molds and cores from sand bound by a curable binder. To reclaim sand from the mold or core, after removing the casting, mechanically vibrate or disassemble the used mold and core to break the sand apart, break up clumps or aggregates and collect the sand . Since the surface of the recovered sand contains unburned components of the binder, the sand is usually regenerated next. Three generally accepted methods for reclaiming reclaimed sand (mechanical, wet, thermal)
There is. Wet regeneration is a relatively unfavorable method due to the disposal problems associated with wash water and the energy costs required to dry the sand. Thermal regeneration is also a relatively unfavorable method due to the high energy costs of this method. On the other hand, the mechanical regeneration method is the most economical, and thus is the most commonly used and widely used regeneration method in the foundry industry. In the reclaimed sand thus obtained, the binder process of curing a water-soluble phenol resin with an organic ester has a drawback unique to this process as described above in that sufficient mold strength cannot be obtained, and has been widely used. This is a completely different phenomenon from the case of an acid-curable furan resin, and 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 content concentration in a binder is disclosed in JP-A-1-262042, and the recycled sand is pretreated with a silane solution in advance. The method is disclosed in Japanese Patent Application Laid-Open No. 1-262043. However, although some of these methods slightly improve the strength of the reclaimed sand, satisfactory mold strength cannot be obtained.

[0005]

The present inventors have SUMMARY OF THE INVENTION As a result of intensive studies to solve the above problems, a casting for molding a refractory granular material by curing a water-soluble phenolic resin <br/> organic esters In the molding resin composition used in the method for producing a sand mold, by using a molding resin composition containing a specific amount of a specific metal element, a mold was formed from a regenerated refractory granular material (hereinafter referred to as “regenerated sand”). It has been found that the strength of the mold is greatly improved, and the present invention has been completed. That is, the present invention relates to phenol under alkaline conditions.
A water-soluble phenolic resin obtained by reacting le with an aldehyde in the mold production method of curing an organic ester
In the mold resin composition to be obtained , the resin
Contains 0.0005-5% by weight of Group B-VIII metal elements
Refractory granular bone whose main component is after and / or recovered aggregate
The present invention relates to a resin composition for a mold, which is used for a material . The present invention also relates to a method for producing a mold, comprising using a binder composition for a mold containing the resin composition .

The present invention will be described in more detail.
Among the IB to VIII groups, the resin composition contains Cu, A in the IB group.
Mg, Ca, Sr, Ba, Zn, Cd for group g, II, Sc, for group III
For Y, Al, Ga, In, Tl, and IV groups, Ti, Zr, Hf, Sn, Pb, V
Group, V, Nb, Ta, Bi, group VI, Cr, Mo, W, Po, group VII, Mn, Tc, Re, group VIII, Fe, Co, Ni compounds containing, obtained by 0.0005 be wt% mixed and / or dissolved as a metal element in a water-soluble phenolic resin. Examples of the form of the metal element-containing compound used in the present invention include metal powder,
There are various forms such as oxides, hydroxides, inorganic acid salts, organic acid salts, and complex compounds, and any of these forms can be used. A water-soluble phenol resin in which the metal element is a binder ,
Or At the A than it placed free Marete the binder composition comprising an organic ester curing agent and is not in any way bound by the form of a compound containing a metal element. Hereinafter, specific examples of the metal element and a compound containing the metal element will be given, but the invention is not limited thereto.

As the metal powder, Cu, Ag, II, Mg, Ca, Sr, Ba, Zn, Cd, etc. for the IB group, Al, Sc, and the like for the III group.
Group IV, Ti, Zr, Sn, etc. for Group IV, Sb, Bi, etc. for Group V, Cr, Mo, etc. for Group VI, Mn, Tc, etc. for Group VII, Fe, C for Group VIII.
o, Ni, etc., but B, Si,
As and Te are not preferred. Examples of the alloy powder include duralumin, magnalium, and ferromanganese.
Typical compounds containing a metal element of Groups IB to VIII of the periodic table include salts and double salts, hydroxides, oxides, hydrocarbon groups such as alkyl groups and aryl groups, and metal atoms. Bound organometallic compounds, nitrides, alkoxides, hydrides, carbides, metal imides, peroxides, sulfides, phosphides, nitrates, anilides, phenolates,
Hexaammonides, ferrocene and analogs thereof,
Examples include dibenzenechromium and its analogous compounds, inorganic heteropolymers, metal carbonyls, metal-containing enzymes, clathrate compounds, metal complexes, chelate compounds, and coordination polymers.

A typical structure of a salt, a hydroxide or an oxide containing the metal element of Groups IB to VIII of the periodic table is represented by the following general formula.

MaXb (wherein, M is the metal element belonging to group IB to VIII, and X is an oxygen atom
Anions or anions of hydroxyl or inorganic acids or
Acids exhibiting anionic groups or sequestering of organic acids
Anion group. A and b represent an integer of 1 or more.
Show. ) As M, as described above, Cu, A
Mg, Ca, Sr, Ba, Zn, Cd, etc. for group g, II, Al,
 Sc, Ga, etc., group IV: Ti, Zr, Sn, etc., group V: Sb, Bi
Group VI, Cr, Mo, etc., group VII, Mn, Tc, etc., group VIII
Is Fe, Co, Ni, etc., but is usually called semimetal
B, Si, As, Te, etc. are not preferred. As a specific example of X
Represents an oxygen atom, a hydroxyl group, or an anion group of an inorganic acid.
Halogen (F, Cl, Br, etc.), SO_Four, SO_Three, S_TwoO_Three, S_TwoO₆,
SiF₆, MoO_Four, MnO_Four, NO_Three, NO_Two, ClO_Three, ClO, CO_Three, HC
O_Three, CrO_Four, IO_Three, PO_Three, PO_Four, HPO_Three, HPO_Four, H_TwoPO_Four , P
_TwoO₇, H_TwoPO_Two, SiO_Three, BO_Two, BO_Three, B_FourO₇, Fe (CN)₆Etc.
Can be The anionic groups of organic acids include formic acid and vinegar.
Acid, oxalic acid, tartaric acid, benzoic acid, etc.
On-atom group, etc., sulfamic acid, xylene
Sulfonic acid, toluene sulfonic acid, phenol sulfone
Acid, benzenesulfonic acid, alkylbenzenesulfonic acid
And the like. Change
Of organic phosphoric acid such as methylphosphoric acid and ethylphosphoric acid
Atomic groups and the like. As a double salt, M_Two ³⁺ (SO_Four)_Three
・ M_Two ¹⁺ SO_Four・ 24H_TwoO can be represented by the general formula
Alum etc.³⁺A is equivalent to trivalent metal
l, V, Mn, Fe, etc.¹⁺Examples thereof include Na and K.

Typical 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, aluminum fluoride, vanadium chloride, molybdenum chloride, manganese chloride, iron chloride, nickel chloride, calcium sulfate, calcium carbonate, Examples include magnesium phosphate, calcium phosphate, aluminum chloride, tin chloride, calcium formate, magnesium succinate, calcium toluenesulfonate, magnesium acetate, zinc acetate, aluminum acetate, magnesium aluminate and the like. As double salts, there are potassium alum, ammonium alum and the like.
Examples of the hydroxide include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide and the like. Examples of the oxide include magnesium oxide, calcium oxide, barium oxide, zinc oxide, aluminum oxide, and the like. In addition, a complex compound composed of a combination of two or more of these oxides and oxidation of the oxide and other elements Compounds composed of a combination with a compound or a salt are preferably used.

Representative examples of the compound used in the present invention include the following.

Examples of cements include hydraulic lime, Roman cement, natural cement, Portland cement, alumina cement, blast furnace cement, silica cement, fly ash cement, masonry cement, expansive cement, special cement, and blast furnace slag. Blast furnace grounds,
Magne refining grounds, ferrochrome grounds, bentonite, etc., whose main chemical structures are mCaO.nSiO ₂ , m
_{CaO · nAl 2 O 3, mBaO} · nAl 2 O 3, CaO · mAl 2 O 3 · nSi
_{O 2, CaO · mMgO · nSiO} 2, mCaCO 3 · nMgCO 3, mCa
O · nFe ₂ O ₃ · lCaO · mAl ₂ O ₃ · nFe ₂ O ₃ (l, m,
n is represented by a combination of 0 or an integer of 1 or more. ).

As the oxide or compound, there are other raw materials of clay, iron oxide and other minerals. When the oxide is used, its particle size is preferably as small as possible, and the average particle size is usually 200 μm or less, preferably 50 μm.
The following is good. Examples of the organometallic compound in which a metal atom is bonded to a hydrocarbon group such as an alkyl group or an aryl group containing the metal element in Groups IB to VIII of the periodic table are as follows. Al (CH ₃ ) ₃ , Al (C ₂ H ₅ ) ₃ , Al (C ₆ H ₅ ) ₃ , (C ₂ H ₅ )
₂ AlI, (C ₂ H ₅ ) ₂ AlH, (C ₂ H ₅ ) ₂ AlCN, Al (iC ₄ H ₉ ) ₃ , (CH ₂ = C
_{H) 3 Al, Zn (C} 6 H 5) 2, 2 and _{(CH 2 = CH) 2 Zn} , Ca (C 2 H 5), R-
Grignard reagents such as Mg-X (R; alkyl or aryl group, X; halogen). Periodic Table IB-VIII
Examples of the metal alkoxide containing the metal element of Group III include Al
[OCH (CH ₃ ) ₂ ] ₃ , Zn (OCH ₃ ) _{2 and the} like. Examples of the hydride containing the metal element of Groups IB to VIII of the periodic table include Al.
H ₃ , CaH ₂ , BaH _{2 and the} like. Examples of the carbide containing the metal element belonging to Groups IB to VIII of the periodic table include Al ₄ C ₃ and CaC ₂ . Examples of the metal imide containing the metal element from Groups IB to VIII of the periodic table include Ca (NH ₂ ) ₂ . As the peroxide containing the metal element belonging to the group IB to VIII of the periodic table,
O ₂ , BaO ₂ , BaO _{4 and the} like can be mentioned. Examples of the sulfide containing the metal element belonging to the groups IB to VIII of the periodic table include ZnS, Cu2S, and CuS.
And the like. Examples of the phosphide containing the metal element from Groups IB to VIII of the periodic table include AlP. The nitro compound containing the metal elements of the periodic table IB~VIII group, CuNO _2, and the like. Examples of the anilide containing the metal element of Groups IB to VIII of the periodic table include Al (NHPh) ₃ . Examples of the phenolate containing the metal element from Groups IB to VIII of the periodic table include Al-phenolate, Zn-phenolate, Ca-phenolate and the like.

Examples of hexaammonides containing the metal element of Groups IB to VIII of the periodic table include Ca (NH ₃ ) ₆ .
Ferrocene and its analogous compounds containing the metal element of Groups IB to VIII of the periodic table 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, V (C 5 H 5) 2
And the like. Examples of the dibenzene chromium containing the metal element of Groups IB to VIII of the periodic table and its analogous compounds include:
Cr (C ₆ H ₆ ) ₂ , Mo (C ₆ H ₆ ) ₂ , V (C ₆ H ₆ ) _{2 and the} like.

Examples of the inorganic heteropolymer containing the metal element of Groups IB to VIII of the periodic table include the following. Hydrogenated inorganic heteropolymers such as beryllium hydride polymer, magnesium hydride polymer, and aluminum hydride polymer. Inorganic polymers such as aluminum nitride containing Al-N bonds. Alumino-silicates such as zeolites, calcite and fluorite. Layered silicates such as mica. Other examples include aluminum phosphate and hydrotalcite.

Examples of the clathrate compounds containing the metal element belonging to groups IB to VIII of the periodic table include cyclic polyethers (crown ethers), cyclic polyamines (azacrown compounds), cyclic polythiaethers (thiacrown compounds), and composite donors. Complexes with crown compounds, bicyclic crown compounds (cryptands), polymer crown compounds, cyclic phenols (kaxarenes), cyclodextrin derivatives, and the like. For example, a complex of dibenzo-18-crown-6 with Ca ²⁺ , a complex of cryptad [2.2.2] with Ca ^2+, and the like can be mentioned. Examples of the metal complex containing the metal element of Groups IB to VIII of the periodic table include Cl ⁻ , CN ⁻ , NCS ⁻ , SO ₄ ²⁺ , NO ²⁻ , ONO ⁻ NO ³⁻ , and CH _{3.
^{COO -, C 2 O 4 2-}} , CO 3 2-, OH -, H 2 N · CH 2 COO -, F -, B
^{r -, ONO -, I -} , NH 2-, SCN - anionic, such as and /
Or a neutral ligand such as H ₂ N · CH ₂ CH ₂ NH ₂ , C ₆ H ₅ N, NH ₃ , H ₂ O and / or H ₂ N · NH ³⁺ , H ₂ N · CH ₂ It has a CH ₂ .NH ₃ ⁺ cationic ligand and is selected from a coordination number of 2 to 8. For example, [Al (C ₂ O ₄ ) ₃ ] Cl ₃ ,
[Zn (NH ₃ ) ₆ ] Cl _{2 and the} like. In addition, Periodic Table IB-VI
Compounds containing the Group II metal element include Ni (CO) ₄ , Mn ₂
Examples include metal carbonyls such as (CO) ₁₀ , metal-containing enzymes such as carboxypeptidase A and thermolysin, and zircoaluminum compounds.

Further, a sequestering compound containing the metal element belonging to the group IB to VIII of the periodic table may be used. Examples of such sequestering compounds include the following. Representative acetic acid type aminocarboxylic acid types include ethylenediaminetetraacetic acid (EDTA) or salts thereof, nitrilotriacetic acid (NTA) or salts thereof, trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA).
Or a salt thereof, diethylenetriaminepentaacetic acid (DTP
A) or a salt thereof, triethylenetetramine hexaacetic acid (T
THA) or a salt thereof, glycol ether diamine tetraacetic acid (GEDTA) or a salt thereof, iminodiacetic acid (ID
A) or a salt thereof, polyalkylenediaminetetraacetic acid or a salt thereof, and N-hydroxyalkyleneiminodiacetic acid or a salt thereof, is a typical phenyl-based aminocarboxylic acid type of 2-oxyphenyliminodiacetic acid or a salt thereof. Salts, 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 a salt thereof is a typical aminocarboxylic acid type having a mercaptan group, and β-mercaptoethyliminodiacetic acid or a salt thereof is an aminocarboxylic acid having an ether bond. A typical type is ethyl ether diamine tetraacetic acid or a salt thereof, an aminocarboxylic acid having a thioether bond.A typical type is ethyl thioether diamine tetraacetic acid or a salt thereof is an aminocarboxylic acid having a sulfonic acid group. A typical acid type is β-aminoethylsulfonic acid-N, N-diacetate or a salt thereof, and a typical aminocarboxylic acid type having a phosphonic acid group is nitriloacetic acid-methylene phosphonic acid. Or a salt thereof, a typical aminocarboxylic acid type having a peptide bond is N,
N'-Diglycylethylenediamine-N ', N'',N''', N ''''
-Tetraacetic acid or salts thereof are representative of the oxycarboxylic acid type, gluconic acid or salts thereof, citric acid or salts thereof, and tartaric acid or salts thereof, and further typical of phosphoric acid type are , Tripolyphosphoric acid or salts thereof, hydroxyethanediphosphonic acid (HEDP) or salts thereof, and nitrilotristyrenephosphonic acid (NTP)
Or salts thereof, and acetylacetone. Examples of the coordination polymer having such a sequestering ability include an amine group, and / or a nitrogen heterocycle, and / or a Schiff base, and / or an alcohol, a carboxylic acid, and / or a ketone, an ester, or the like.
Amides, and / or aminocarboxylic acids, and / or phosphonic acids, and / or phosphines, and / or
Alternatively, a polymer having a thiol can be used.

Among the metal-containing compounds of groups IB to VIII described in these specific examples, preferred metal elements are II to VI.
Group II metal element, more preferably II, III, IV
Group metal elements, among which Zn, Ca, Mg, A
l and Zr are preferred. The determination of the metal element in sand and in the resin composition for a mold is generally performed as follows.

[Quantitative Determination of the Metal Element in Sand] Sand is ground to 150 mesh or less, and 0.2 to 0.3 g is weighed in a 100 ml platinum dish. To this, 5 ml of concentrated hydrochloric acid, 3 ml of concentrated hydrofluoric acid, and 10 ml of concentrated perchloric acid were added to volatilize Si, and then HCL (1 + 1) 10 ml + H ₂ O 10 m
Add l and heat to dissolve residual salts. This is filtered (No.
5C filter paper), and wash with diluted 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 acid-fused at 800 ° C. The extract of the melt was combined with the previous filtrate,
After making 100 ml of the solution in a measuring flask, the metal element is quantified by ICP (inductively coupled plasma emission spectrometry).

The thoroughly mixed by stirring to mold resin composition [Determination of the metal element of the mold resin composition], the platinum dish for 100ml
Weigh 0.5-0.8 g. To this, 10 ml of concentrated nitric acid is added, and after acid decomposition, it is subjected to weak thermal decomposition. 10 ml of concentrated perchloric acid is added and white smoke treatment is performed to make 3 ml of concentrated perchloric acid. After cooling, HCl (1 + 1) 10ml + H ₂ O
Add 10 ml and heat to dissolve. 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 melted at 800 ° C. The extracted melt is combined with the above filtrate to make a 100 ml solution in a volumetric flask, and the metal element is quantified by ICP (inductively coupled plasma emission analysis).

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, bisphenol A, and other substituted phenols can be used. And aldehydes such as formaldehyde, acetaldehyde and furylaldehyde or a mixture thereof in a large amount of an aqueous solution of an alkaline substance. Also, urea,
Formalin-condensable monomers such as melamine and cyclohexanone may be co-condensed to such an extent that they do not become main constituent units 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 performed. obtained by dissolving or mixing the compounds containing. The content of the metal compound as a metal element is preferably 0.0005 to 5% by weight, more preferably 0.1 to 5% by weight.
001 to 3% by weight. If the amount is less than 0.0005% by weight, the effect of the present invention is not sufficient. If the amount is more than 5% by weight, the effect is in a saturation region.

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. 47-5087
No. 3, U.S. Pat. No. 3,485,797, 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, and the obtained resole resin is classified into a thermosetting solid resole resin. However, 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 described in the above patent, no curing reaction is induced due to insufficient alkalinity. Therefore, these known techniques do not correspond to the prior art of 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, and the like.In the gas-curing molding method, methyl formate is used. Is preferred. Examples of the refractory granular material include silica 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 reclaimed sand is used, a reclaimed sand obtained by a normal abrasion or roasting method is used, but the method for producing the reclaimed 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 are preferably γ-aminopropyltriethoxysilane and γ-aminopropyltriethoxysilane.
(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. When a sand mold for casting is manufactured by a self-hardening molding method using the binder composition of the present invention, a well-known method is employed. For example, an organic ester of a curing agent, which is a binder composition according to the present invention, is added in an amount of 0.05 to 9 parts by weight, preferably 0.1 to 5 parts by weight, and 0.4 to 15 parts by weight of a water-soluble phenol resin aqueous solution in 100 parts by weight of recycled sand. Preferably, 0.6 to 5 parts by weight are 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 The present invention will be described below 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 ethylenediaminetetraacetate 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. C. for 30 minutes. Then 48
After adding 282 parts by weight of potassium hydroxide, 158 parts by weight of 92% paraformaldehyde was added over 1 hour. The reaction was continued at the same temperature, and cooled when the viscosity of the resin solution reached 100 cp at 25 ° C. Then, 4.0 g of γ-aminopropyltriethoxysilane was added, and a resin solution containing 1,931 ppm as a magnesium element (solid content of 49%) was added. %, Weight average molecular weight 2300).

Synthesis Example 2 263 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, 163 parts by weight of 92% paraformaldehyde was added over 1 hour. The reaction was continued at the same temperature, and when the viscosity of the resin solution reached 100 cp at 25 ° C., the mixture was cooled, 3.5 parts by weight of zinc chloride and 4 parts by weight of γ-aminopropyltriethoxysilane were added, and 1,98 parts as zinc element was added.
Resin solution containing 3ppm (solid content 49%, weight average molecular weight 23
00).

Synthesis Example 3 264 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. The reaction was continued at the same temperature, and when the viscosity of the resin solution reached 100 cp at 25 ° C., the mixture was cooled, and 4 parts by weight of γ-aminopropyltriethoxysilane was added. The resin solution (solid content 49%, weight average molecular weight 2300) I got

Examples 1 to 20 The metal compounds shown in Table 1 were added according to Synthesis Example 1 to obtain a resin solution containing a metal element, and a test piece for a pressure resistance test was prepared according to a predetermined method. The change over time in the mold strength was measured.

Examples 21 to 34 Metal compounds shown in Table 2 were added according to Synthesis Example 2 to obtain a resin solution containing a metal element, and a test piece for a pressure resistance test was prepared according to a predetermined method. The change over time in the mold strength was measured.

Comparative Example 1 A resin solution was obtained in the same manner as in Synthesis Example 3, a test piece for an anti-pressure test was prepared in accordance with a predetermined method, and the time-dependent change in the mold strength after preparation was measured.

Comparative Example 2 A water-soluble phenol resin solution (solid content: 40%) was obtained according to the examples described in JP-A 1-262043, and a test piece for an anti-pressure test was prepared according to a predetermined method. Of the mold strength over time was measured.

Comparative Example 3 Sand was treated according to the example described in Japanese Patent Application Laid-Open No. 1-262043. That is, 100 parts by weight of the reclaimed sand was previously treated at 25 ° C. with 0.024 parts by weight of a 40% aqueous solution of γ-aminopropyltriethoxysilane, and a test piece for an anti-pressure test was prepared according to a predetermined method. The change over time in the mold strength was measured. Method of measuring mold strength 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, and the water-soluble phenolic resin of Examples and Comparative Examples of the present invention (solid content 49%, weight average molecular weight) 2300) was added and kneaded with 1.5 parts by weight of
The test piece was packed in a test piece of mmφ × 50 mmh, and the change of the coercive pressure with time after kneading was measured.

Method for Preparing Reclaimed Sand A water-soluble phenol resin containing 0.375 parts by weight of triacetin as a hardener and 0.5% by weight of γ-aminopropyltriethoxysilane (based on phenol resin) per 100 parts by weight of fresh sand of Fremantle silica sand (Solid content 49%, weight average molecular weight 2300) was added to 1.5 parts by weight of a mixture, and FC-25 (S / M = 3.5) was cast using a mold. The collected sand was crushed and manufactured by Nippon Casting. Regeneration (A regeneration, 2 passes) was performed using an M-type rotary Kramer. The reclaimed sand obtained by repeating the above steps five times was used for the preparation for the above mold strength test.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

According to the method for producing a sand mold for a casting for molding a refractory granular material, by using the binder composition for a curable mold of the present invention, the strength of a mold molded from recycled sand is greatly improved. Can be done.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akira Yoshida 1-3-5 Higashiwaki, Toyohashi City, Aichi Prefecture 5 Sara City Minato Street 102 (56) References JP-A-2-184561 (JP, A) JP-A-62 JP-A-2-279815 (JP, A) JP-A-1-262042 (JP, A) JP-B-3-18531 (JP, B2) JP-A-7-508255 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B22C 1/00-1/26

Claims (6)

(57) [Claims] A phenol and an aldehyde under alkaline conditions.
For molds used in mold manufacturing methods in which water-soluble phenolic resins obtained by reacting hydrides are cured with organic esters
In the resin composition, the resin is a metal element of the periodic table IB~VIII group containing 0.0005 wt%, after the reproduction and / or
Used for refractory granular aggregate whose main component is recovered aggregate
A resin composition for a mold. 2. The method according to claim 1, wherein the metal element of the group IB to VIII of the periodic table is II to
The resin composition for a mold according to claim 1, which belongs to Group VIII. 3. A metal element is added at a stage of synthesizing a resin.
The resin composition for a mold according to claim 1 or 2, wherein the resin composition is used. Wherein according to the mold resin composition according to any one of claims 1 to 3, further mold binder composition for you <br/> characterized by containing an organic ester. Re 5. A foundry binder composition of claim 4, wherein
A refractory aggregate mainly composed of aggregate after birth and / or after collection, and a refractory aggregate. 6. A refractory containing the aggregate as a main component after regeneration and / or recovery using the binder composition for a mold according to claim 4.
A method for producing a mold, characterized by molding an aggregate .