JP2001347339A - Binder composition for mold and material for mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve collasability of a mold after casting while attaining its high mechanical strength and further to improve the dimensional stability by suppressing the thermal expansion of the mold. SOLUTION: A mold is shaped by using a binder composition for a mold containing a binder and a collasability improving agent as essential components, in which the binder is composed of a resin composition containing a triazine derivative and phenols, and the collasability improving agent is composed of one or more kinds selected from the groups consisting of phosphoric ester, a halogen compound, organic carboxylate, thermoplastic resin, glycols, alkali metal nitrate, amino acid and amino acid salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material used for producing a mold, and more particularly to a binder composition for a mold and a material for a mold suitable as a material for a shell mold.

[0002]

2. Description of the Related Art Conventionally, as a casting mold, a resin mold containing sand and a resin as a binder as essential components has been known. Also, among the resin types, non-ferrous castings such as aluminum alloys, magnesium alloys, and copper alloys,
In sand casting of iron castings such as cast steel and cast iron, a shell mold using a phenolic resin as a binder is widely used as a main mold and a core. By the way, the mold is required to have sufficient mechanical strength so as not to collapse during the casting operation, and to be easily collapsed so that the product can be easily broken after casting and the product can be easily taken out. However, in the conventional shell mold, there is a problem that the phenol resin binding the sand particles is excellent in heat resistance, so that the disintegration after casting is poor.

[0003]

Therefore, additives which can promote the decomposition of the binder at the time of casting to promote the collapse of the mold, for example, 1, 2, 8, 9, and 9 in the periodic table of the elements.
10,13,14,15,16,17 families (of the old periodic table)
Ia, IIa, IIIb, IVb, Vb, VIb, VIIb, and VII
A method has been proposed in which a carbonate and / or bicarbonate of an element selected from Group I) is added to a phenol resin (JP-A-58-70939). However, mold materials using this type of additive can provide good easy disintegration when a sufficient amount of heat is supplied from the molten metal to the mold during casting and the ultimate temperature of the mold is high, but aluminum castings and alloy castings are obtained. If the casting temperature is relatively low, or if the mold is thick and the temperature at the center is low,
There is a disadvantage that the disintegration of the mold is insufficient.

On the other hand, in order to produce a high quality casting,
Dimensional stability of the mold is also required. That is, if the sand expands due to the heat received from the molten metal during casting, the dimensions of the mold change, and it is required to prevent this. In the prior art, the coefficient of thermal expansion of the mold was reduced by increasing the amount of binder relative to the amount of sand, or by adding and mixing a bisphenol A resin. However, when the amount of the binder is increased, the amount of gas generated at the time of casting increases, so that there is a problem that defective products such as gas defects occur frequently and a cost increases. Also, bisphenol A
When a resin is used, there are problems that the strength of the mold is easily reduced and there is a concern that an environmental hormone may be generated.

[0005] The present invention has been made in view of the above circumstances, and while improving the high mechanical strength of the mold, improving the easy collapse after casting, and improving the dimensional stability by suppressing the thermal expansion of the mold. The purpose is to:

[0006]

In order to solve the above-mentioned problems, a binder composition for a mold of the present invention comprises a binder and a disintegration improver as essential components. Is composed of a resin composition containing a triazine derivative and a phenol, wherein the disintegration enhancer is a phosphoric acid ester, a halogen compound, an organic carboxylate, a thermoplastic resin, a glycol, an alkali metal nitrate, an amino acid, and an amino acid. It is characterized by being at least one member selected from the group consisting of salts. It is preferable that the binder comprises a co-condensation resin of a triazine derivative and a phenol. Alternatively, the binder may be a resin composition obtained by mixing a co-condensation resin of a triazine derivative and a phenol and / or a triazine derivative and a phenol resin. Some or all of the co-condensation resin of the triazine derivative and a phenol is, [- NH-CH ₂ - phenol] bond _{number, [- NH-CH 2 -NH-} ] bonding number, and [phenol -CH ₂ - phenol ] to the total of the number of bonds [-NH-CH ₂ - phenol] average percentage of bond number 3
0 to 80% and a number average molecular weight (Mn) of 300 to 8
It is preferably a phenol / triazine derivative co-condensation resin having a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 1.30 or less. The amount of the disintegration improver used is 1 to 100 parts by weight of the resin composition used as the binder.
It is preferable to add 50 parts by weight. The mold material of the present invention comprises the binder composition of the present invention and refractory particles.

[0007] Alternatively the mold material of the present invention contains a refractory particles and binder as essential components, wherein the binder is, [- NH-CH ₂ - phenol] bond number, [-
NH-CH ₂ -NH-] bonding number, and [phenol -
CH ₂ - phenol] relative to the total of the number of bonds [-NH-
CH ₂ - phenol] average percentage of binding numbers 30% to 80%
Having a number average molecular weight (Mn) of 300 to 800, a weight average molecular weight (Mw) and a number average molecular weight (M
n) and a phenol / triazine derivative co-condensation resin having a ratio (Mw / Mn) of 1.30 or less. The disintegration improver may not be contained. The binder may be a resin composition obtained by mixing the phenol / triazine derivative co-condensation resin and a phenol resin. Alternatively, the binder may be a resin composition obtained by mixing the phenol / triazine derivative co-condensation resin, the triazine derivative and a phenol resin.
In particular, in the present invention [-NH-CH ₂ - phenol]
Bond _{number, [- NH-CH 2 -NH-} ] bonding number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - phenol] average percentage of binding numbers 30% to 80% And a number average molecular weight (Mn) of 300
Phenol-triazine derivative co-condensation resin having a weight average molecular weight (Mw) and a number average molecular weight (Mn) of 1.30 or less,
Useful as a binder for shell molds.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The refractory particles used in the present invention are not particularly limited as long as they are inorganic particles capable of molding a mold and having fire resistance enough to withstand a casting operation. Specifically, silica sand is preferably used, but in addition to this, olivine sand,
Special sand such as zircon sand, chromite sand, and alumina sand; slag-based particles such as ferrochrome-based slag, ferronickel-based slag, converter slag, and porous particles such as nigai cera beads, or recovered after use in casting Regenerated particles and the like can also be used.
One type of these refractory particles may be used alone, or two or more types may be used in combination.

In the present invention, a resin composition containing a triazine derivative and a phenol is used as a binder. Particularly, a co-condensation resin of a triazine derivative and a phenol is preferable. Alternatively, a resin composition obtained by mixing a co-condensation resin of a triazine derivative and a phenol with a phenol resin, a resin composition obtained by mixing a triazine derivative and a phenol resin, or a resin composition obtained by mixing a triazine derivative and a phenol A resin composition obtained by mixing a condensation resin, a triazine derivative, and a phenol resin is also preferably used.

[0010] Triazine derivatives used in the present invention
As a co-condensation resin of a product and a phenol, particularly, [-N
H-CH_Two-Phenol] bond number, [-NH-CH_Two-N
H-] bond number, and [phenol-CH_Two-Fenault
[-NH-CH] in the total number of bonds_Two-Fenault
The average ratio of the number of bonds is 30 to 80%,
The molecular weight (Mn) is 300 to 800 and the weight average
Ratio (Mw) between the average molecular weight (Mw) and the number average molecular weight (Mn)
/ Mn) having a physical property value of 1.30 or less
Le triazine derivative co-condensation resins are preferred. The binding
The ratio is, for example,¹³Easy to find by C-NMR measurement
Can be. ¹³[-NH-CH by C-NMR measurement_Two
-Phenol] binding band around 41 ppm (4
1.2 ppm) and [-NH-CH_Two-NH-]
The combined absorption band is around 45 ppm (45.5 ppm).
Yes, [Phenol-CH_Two-Phenol] bond
As for the absorption band, 2-2 'is around 31 ppm and 2-4' is 44p.
pm, and 4-4 'is around 41 ppm.
H_TwoEach CH in total integrated value of bond_TwoOf the integral of the bond
By determining the ratio, the coupling ratio can be determined.
The bond ratio is the cocondensation rate of the triazine derivative-phenols.
When the bonding ratio is less than 30%, the
Durability, heat resistance, hydrolysis resistance, etc.
The characteristics of the mold when the mold is formed are relatively deteriorated. Coupling ratio
If it is more than 80%, it is difficult and difficult to manufacture
There is no. A more preferred binding ratio is 50 to 80%,
Suitably it is 60-70%.

The triazine derivative is a compound represented by the following formula (I).

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In this formula, R1, R2 and R3 are each an alkylated methylol group, a hydrogen atom, an amino group,
Represents any of an alkyl group, a phenyl group, a hydroxyl group, a hydroxylalkyl group, an ether group, an ester group, an acid group, an unsaturated group, a cyano group, and a halogen atom.
In the above formula (I), it is desirable that at least two of R1, R2 and R3 are alkylated methylol groups. Preferred examples of such a triazine derivative include di- (alkylated methylol) melamine and tri-
One or two selected from (alkylated methylol) melamine, di- (alkylated methylol) benzoguanamine, di- (alkylated methylol) acetoguanamine
Mixtures of more than one species.

The phenol / triazine derivative co-condensation resin having the above physical properties is more preferably a trinuclear body having a skeleton of the following formula (II), a tetranuclear body having a skeleton of the following formula (III), It is mainly composed of a mixture of a pentanuclear body having a skeleton of IV) and a hexanuclear body having a skeleton of the following formula (V). Hydrogen atoms represented by these chemical formulas are substituted by amino groups, alkyl groups, phenyl groups, hydroxyl groups, hydroxylalkyl groups, ether groups, ester groups, acid groups, unsaturated groups, cyano groups, halogen atoms, etc. Is also good. In addition, the main structure means that 80% by weight or more of the entire resin is composed of the 3 to 6 nuclei.

[0014]

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In addition to the above nuclei, compounds having skeletons of the following formulas (VI), (VII) and (VIII), straight novolaks (novolaks not bonded to triazine derivatives), and the like are inevitable impurities as resins. 20% by weight or less of the whole may be contained. Among these, it is particularly desirable that the content of straight novolak is 5% by weight or less.

[0016]

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The phenol-triazine derivative co-condensation resin having the above physical properties has a narrow molecular weight distribution, a high binding ratio between phenol and melamine, and phenol and melamine are arranged regularly and almost alternately. Is high. That is, since the nitrogen content is high, even if it has no halogen group, it has high flame retardancy and heat resistance. Since it is a novolak type, no harmful gas is generated during curing. Further, when used as a binder for mold making, a mold having excellent mechanical strength, good disintegration properties and low coefficient of thermal expansion can be obtained. The reason is that the above composition has a narrow molecular weight distribution and is highly reactive and forms a tough cured product. Further, since phenol-melamine bonds having a high carbonization promoting effect are alternately arranged, they are excellent in disintegration. Further, the crosslinking density at the time of curing is relatively small, and the cured product is flexible, so that the cushioning property is increased and the expansion of sand is easily absorbed.

The phenol / triazine derivative co-condensation resin having the above physical properties can be obtained by the following first to third production methods. [First Production Method] First, as a first step, an aldehyde is added to a triazine derivative to obtain a methylolated triazine derivative. Examples of the triazine derivative include melamine, acetoguanamine, benzoguanamine, cyanuric acid, methyl cyanurate, ethyl cyanurate, acetyl cyanurate, cyanuric chloride and the like. Among them, melamine, acetoguanamine, benzoguanamine, and the like, in which any two or three of R1, R2, and R3 in the above formula (I) are an amino group, are preferable. From the viewpoint of improving the disintegration property, melamine, acetoguanamine, benzoguanamine and the like having a large number of nitrogen atoms and a small number of oxygen atoms in the molecule are preferable. Aldehydes are not particularly limited, but formalin, paraformaldehyde, and the like are preferable industrially from the viewpoint of cost and ease of handling. The molar ratio of the aldehyde to the triazine derivative is not particularly limited, but is preferably 0.5 to 6.0, more preferably 1.5 to 6.0.
4.0, optimally between 2.0 and 3.5. If the molar ratio is less than 0.5, the unreacted triazine derivative remains unpreferably, and if it is greater than 6.0, the effect of enhancing the disintegration is undesirably reduced. The pH of the system at the time of the reaction is not particularly limited, but a pH of 5 to 8 is preferable since a catalyst is not particularly required. This production method is also advantageous in that no catalyst or pH adjuster is required. If the pH is lower than 5, condensation between melamines proceeds, and if the pH is higher than 8, it is necessary to use a catalyst, which increases the cost. More preferably, the pH is 6-7. Reaction temperature is 50
The reaction time is preferably about 0.5 to 2.0 hours. If the reaction temperature is lower than 50 ° C., there occurs a problem that the reaction is not completed and free formalin remains. A more preferred range of the reaction temperature is 60 to 70 ° C.

Next, as a second step, an alcohol is substituted for the methylolated triazine derivative to obtain an alkylated methylol triazine derivative. in this way,
By converting the triazine derivative to an alkylated methylol triazine derivative, it is possible to lower the reactivity in the subsequent third step, to preferentially bind to phenols, and to increase the phenol-triazine derivative cocondensation rate. Thus, a resin having the above-described bonding ratio can be produced. The alcohol is preferably a monohydric alcohol such as methanol, ethanol, or butanol, and more preferably methanol. These are industrially inexpensive and have the advantage of high reactivity.
The molar ratio of alcohol to triazine derivative is 1-2.
It is preferably 0. When the molar ratio is less than 1, the bonding ratio between the triazine derivatives increases, and when the molar ratio is more than 20, the amount of alcohol that does not participate in the reaction increases, and the yield deteriorates. A more preferred range of the molar ratio is 5 to 15, and most preferably 7 to 10. The pH of the reaction system is preferably from 5 to 8, and if the pH is lower than 5, a problem occurs that condensation between triazine derivatives proceeds excessively. If the pH is higher than 8, a problem that a catalyst is required occurs. A more preferred pH is 6-7. Reaction temperature is 5
The temperature is preferably 0 to 80 ° C, and the reaction time at this time is about 0.5 to 5 hours. A reflux device may be used for the reaction. If the reaction temperature is lower than 50 ° C., there is a problem that the reaction is not completed and unsubstituted methylol groups are likely to remain. A more preferred reaction temperature is 60 to 70 ° C.

Next, as a third step, a phenol is added to the alkylated methylol triazine derivative, heated, co-condensed by a dealcoholization reaction and dehydration concentration to produce a phenol-triazine derivative co-condensed resin. . At this time, there is no particular need to add a solvent.
This is because the reactivity of the triazine derivative can be suppressed by converting to an alkylmethylol. The phenols are not particularly limited, but alkylphenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, nonylphenol, octylphenol, polyphenols such as bisphenol A, bisphenol F, bisphenol S, resorcinol, catechol, phenylphenol, amino Phenol and the like. Further, these phenols are not limited to only one kind, and two or more kinds can be used in combination. However, among the above, particularly preferred are phenol, cresol, xylenol and the like, because the softening point of the product is suitable and it is industrially easy to use. The molar ratio of the phenol to the triazine derivative is preferably from 1 to 20. If the molar ratio is less than 1, there is a problem that the binding ratio between the triazine derivatives is high. If the molar ratio is more than 20, phenol that does not participate in the reaction increases, and the yield deteriorates. A more preferred range of the molar ratio is 5 to 15, and most preferably 7 to 10. The maximum heating temperature at the time of the dealcoholization reaction and the dehydration concentration is preferably 120 ° C or higher, more preferably 160 to 200 ° C. If the maximum heating temperature is lower than 120 ° C., there occurs a problem that the reaction does not proceed sufficiently. When the co-condensation is completed, the resin may be taken out. The viscosity of the resulting resin is usually 10 ° C at 200 ° C.
It is about 0 to 1000 cP.

[Second Manufacturing Method] In the first manufacturing method, the first step, the second step, and the third step are performed separately. One process,
The chemical reaction can proceed in the same order as the second step and the third step. That is, by mixing the triazine derivative, the aldehydes, the phenols, and the alcohol at once, a methylolated triazine derivative is selectively generated by a difference in reactivity,
Next, the alcohol is substituted with the methylolated triazine derivative to generate an alkylated methylol triazine derivative, and further heated after the alkylated methylol triazine derivative is formed, whereby the alkylated methylol triazine derivative and the phenol are co-polymerized. The phenol / triazine derivative co-condensation resin can be produced by condensation. According to such a method, there is an advantage that the operation can be simplified because the raw materials can be charged at once. The reaction conditions and the like may be the same as in the first production method.

[Third Manufacturing Method] In the third manufacturing method,
First, as a first step, phenols are subjected to an addition reaction with aldehydes to obtain methylolated phenols. The types of phenols and aldehydes may be the same as in the first production method. The molar ratio of the aldehyde to the phenol is not particularly limited, but is preferably 0.5
６6.0, more preferably 1.5-4.0, and most preferably 2.0-3.5. When the molar ratio is less than 0.5, unreacted phenol remains unpreferably,
If it is larger than 6.0, free formalin remains, and it is not preferable because triazine derivatives are easily condensed when the triazine derivative is added later. The pH of the system at the time of the reaction is not particularly limited, but a pH of 5 to 8 is preferable since a catalyst is not particularly required. This production method is also advantageous in that no catalyst or pH adjuster is required. If the pH is lower than 5, the condensation of phenol proceeds too much, and if the pH is higher than 8, a catalyst is required, which is not preferable. More preferably pH
6 to 7. The reaction temperature is preferably 50 to 100 ° C., and the reaction time at that time is about 0.5 to 4 hours. If the reaction temperature is lower than 50 ° C., there occurs a problem that the reaction is not completely completed and free formalin remains, and if it is higher than 100 ° C., there is a problem that gelation may occur. A more preferable range of the reaction temperature is 70 to 80 ° C.

Next, as a second step, the methylolated phenols are subjected to an alcohol substitution reaction to obtain alkylated methylolphenols. The alcohol may be the same as that used in the first production method. The molar ratio of alcohol to phenols is preferably from 1 to 20. If the molar ratio is less than 1, there is a problem that the binding ratio between phenols is high, and if it is more than 20, there is a problem that the alcohol that does not participate in the reaction increases and the yield deteriorates. A more preferred range of the molar ratio is 5 to 15, and most preferably 7 to 10. The pH of the reaction system is preferably from 10 to 14, and if the pH is less than 10, the substitution reaction becomes difficult to proceed. A more preferred pH is 1
2 to 13. To adjust the pH to the above range, alkali metal hydroxide, alkaline earth metal hydroxide, 1,8
-Diazabicyclo-7-undecene (DBU) or the like may be added to the reaction system. The reaction temperature is preferably 50 to 100 ° C., and the reaction time at this time is about 0.5 to 4 hours. A reflux device may be used for the reaction. If the reaction temperature is lower than 50 ° C., there occurs a problem that the reaction is not completely completed and unsubstituted methylol groups tend to remain, and if it is higher than 100 ° C., gelation may occur. A more preferred reaction temperature is 70 to 80 ° C.

Next, as a third step, a triazine derivative is added to the alkylated methylolphenols, heated, co-condensed by a dealcoholization reaction and dehydration concentration to produce a phenol / triazine derivative cocondensation resin. . At this time, since there is no free formalin, the triazine derivatives do not react with each other. The triazine derivative may be the same as that used in the first production method. The molar ratio of the phenol to the triazine derivative is preferably from 1 to 20. If the molar ratio is less than 1, there is a problem that the binding ratio between the triazine derivatives is high, and if it is more than 20, there is a problem that the amount of phenol not involved in the reaction increases and the yield deteriorates. A more preferred range of the molar ratio is 5 to 15, and most preferably 7 to 10. The maximum heating temperature at the time of the dealcoholization reaction and the dehydration concentration is preferably 120 ° C or higher, more preferably 160 to 200 ° C. If the maximum heating temperature is lower than 120 ° C., there occurs a problem that the reaction does not proceed sufficiently. When the co-condensation is completed, the resin may be cooled and taken out. The physical properties of the obtained resin are almost the same as those of the first production method.

Among the first to third production methods described above, the first production method is most preferable from the viewpoint of narrowing the molecular weight distribution and increasing the cocondensation rate of the triazine derivative-phenol. The reason why the molecular weight distribution is narrowed and the cocondensation rate is increased in the first production method is that by replacing the triazine derivative with an alkylated methyloltriazine derivative, it is easy to control the reactivity so as to preferentially bind to phenols. It is in.

The co-condensation resin of a triazine derivative and a phenol used as a binder in the present invention is not limited to those having the above-mentioned physical properties, but may be a triazine derivative and a phenol obtained by a conventionally known production method. Co-condensation resins with the same can also be used. For example, as disclosed in JP-A-8-183827, the molar ratio (P / M) of phenol (P) to melamine (M) is in the range of 4.0 to 19.0 and phenol ( P), phenol, melamine and formaldehyde are mixed so that the molar ratio {F / (P + M)} of melamine (M) and formaldehyde (F) is in the range of 40.45 to 0.75, and the acid catalyst is mixed. To produce a phenol-melamine co-condensation resin by reacting at a pH of 4.0 or less, or as described in JP-A-55-108415, by mixing melamine, phenol and formaldehyde. Calcium hydroxide was added to the solution so as to have a pH of 8, and the mixture was refluxed at 97 ° C. Then, a novolak-type phenol resin and polyethylene glycol were further added. Added Lumpur, a method for producing a phenol-melamine resin by dehydration under reduced pressure or JP 3-2,
As described in JP 43613, phenol, formalin, and calcium hydroxide are reacted at 50 ° C., sulfuric acid is added to adjust the pH to 3.5, melamine is added to the reaction solution, and the mixture is heated at 85 ° C. for 60 minutes. A method of producing a phenol-melamine resin by reacting and adding sodium hydroxide and cooling, or Japanese Patent Application Laid-Open No. 9-12489.
No. 6, phenol, melamine, formalin, triethylamine, etc.
After heating to 180 ° C, dehydration is carried out by raising the temperature to 180 ° C over 2 hours, and further, unreacted phenol is removed under reduced pressure to obtain a phenol-melamine resin. May be used.

In the present invention, the co-condensation resin of a triazine derivative and a phenol and / or the phenol resin used by mixing with the triazine derivative is obtained by subjecting a phenol and a formaldehyde to a condensation reaction by a well-known method. Examples of phenols include alkylphenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, nonylphenol and octylphenol, polyphenols such as bisphenol A, bisphenol F, bisphenol S, resorcinol, catechol, and phenylphenol.
Aminophenol and the like. Especially phenol,
Cresol is preferred because it is relatively inexpensive among the above phenols. In the present invention, a phenolic resin,
Or triazine derivatives used as a mixture with a co-condensation resin of a triazine derivative and a phenol and a phenol resin include melamine, acetoguanamine, benzoguanamine, cyanuric acid, methyl cyanurate, ethyl cyanurate, acetyl cyanurate, cyanuric chloride, and the like. Is mentioned. In particular, among the above triazine derivatives, melamine and benzoguanamine are preferable because they are widely used, relatively economical, and easily available.

In the present invention, when a resin composition obtained by mixing a co-condensation resin of a triazine derivative and a phenol with a phenol resin is used as a binder, a co-condensation resin of a triazine derivative and a phenol (C ) And the phenolic resin (P) are in a weight ratio of C: P = 99:
1-1: 99, preferably 70:30 to 10:90. If the amount of the co-condensed resin of the triazine derivative and the phenol is too large, the softening point of the resin composition increases,
If the amount is too small, the collapsibility deteriorates and the coefficient of thermal expansion further increases. When a resin composition obtained by mixing a triazine derivative and a phenol resin as a binder is used, the mixing ratio of the triazine derivative (T) and the phenol resin (P) is T: P = 99: 1-1: 99, preferably 70:30 to 10:90. If the blending amount of the triazine derivative is too large, the softening point of the resin composition will be high and workability will be poor. If too small, the disintegration will be poor and the coefficient of thermal expansion will be further increased. When a co-condensation resin of a triazine derivative and a phenol, or a resin composition obtained by mixing a triazine derivative and a phenol resin is used as a binder, a co-condensation resin of a triazine derivative and a phenol (C) and a triazine The compounding ratio of the derivative (T) and the phenolic resin (P) is such that, among 100 parts by weight of the binder, C
Is 1 to 98 parts by weight, T is 1 to 98 parts by weight, P is 1 to 98 parts by weight.
Parts by weight, preferably 5 to 90 parts by weight of C, and 5 to 90 parts by weight of T
Parts by weight, P is in the range of 5 to 90 parts by weight.

The disintegration improver used in the present invention is one selected from the group consisting of phosphate esters, halogen compounds, organic carboxylate salts, thermoplastic resins, glycols, alkali metal nitrates, amino acids, and amino acid salts. Or two or more. Specific examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate,
Trischloropropyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, xylenyl diphenyl phosphate, trilauryl phosphate, tricetyl phosphate Orthophosphoric acid esters such as tristearyl phosphate, trioleyl phosphate, trischloroethyl phosphate; triphosphyl phosphates such as trimethyl phosphite, tributyl phosphite, triphenyl phosphite, tris nonyl phenyl phosphite, and tris chloroethyl phosphite. Phosphoric acid triester; phosphite diester such as dimethyl phosphite, diethyl phosphite, dibutyl phosphite; butyl phosphonate, di (2-ethylhexyl) 2
And phosphonic acid esters such as -ethylhexylphosphonate.

Specific examples of the halogen compound include cobalt chloride, iron chloride, aluminum chloride, chlorinated paraffins, brominated paraffins, chlorinated polyethylene, brominated polyethylene, brominated polyphenyl, chlorinated polyphenyl, and tetrabromo. Ethane, tetrabromobutane, dibromoethane, 1,2-dibromo-3-chloropropane,
1,2,3-tribromopropane, tetrabromobenzene, chlorinated diphenyl, tetrabromobisphenol A, tetrabromophthalic anhydride, hexabromobenzene, hexabromocyclododecane, pentabromochlorocyclohexane, ethylated tetrabromobisphenol A, dibromo Neopentyl glycol polyester, trisdichloropropyl phosphate, and the like. Specific examples of the organic carboxylate include formate such as sodium formate and potassium formate; acetate such as zinc acetate, sodium acetate and potassium acetate; and oxalate such as sodium oxalate, potassium oxalate and oxalic chloride. In addition,
Various butyrate, benzoate, citrate, succinate,
Acrylates and the like. Specific examples of the thermoplastic resin include nylon, polyester, polyethylene glycol, polyethylene, and polystyrene.

Specific examples of glycols include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol and the like. Specific examples of the alkali metal nitrate include potassium nitrate, sodium nitrate, lithium nitrate and the like. Specific examples of amino acids include asparagine, aspartic acid, alanine, arginine, isoleucine, glycine, glutamine, glutamic acid, cystine, cysteine, serine, thyroxine, tyrosine, tryptophan, threonine, valine, histidine, 4-hydroxyproline, and δ-hydroxy. Lysine, phenylalanine, proline, methionine, lysine, leucine and the like can be mentioned. Specific examples of amino acid salts include, as alkali metal salts or alkaline earth metal salts of amino acids, potassium aspartate, sodium aspartate, sodium glutamate, potassium glutamate and the like; cysteine hydrochloride and arginine hydrochloride as hydrochlorides and sulfates, Glutamic acid hydrochloride, lysine hydrochloride, etc .; Examples of the alkyl ester include ethyl ester and methyl ester of a core amino acid; and hydrochloride of the alkyl ester. Furthermore, there are arginine glutamate, lysine glutamate, glycylglycine and the like.

The binder composition for a mold of the present invention is obtained by adding these disintegration improvers to the binder and mixing them.
When the amount of the disintegration enhancer is too small, the effect of improving the disintegration by adding the disintegration enhancer is insufficient,
If the amount is too large, the mechanical strength of the mold is significantly reduced. Accordingly, the disintegration improver is added in an amount of 1 to 50 parts by weight, preferably about 3 to 20 parts by weight, based on 100 parts by weight of the resin composition used as a binder. Further, in the present invention, when a part or all of the binder used contains a phenol / triazine derivative co-condensation resin having the above-mentioned physical property values, it is preferable that the disintegration improver is not added. Since it is possible to achieve easy disintegration, it is not necessary to use a disintegration enhancer. When the disintegration improver is not used, a decrease in the mechanical strength of the mold is suppressed, so that the mechanical strength of the mold is improved. Furthermore, the binder composition for a mold or the binder may be blended with various additives, for example, a silane coupling agent, an anti-caking agent, a release agent, a deodorant, and the like, if necessary. .

The mold material of the present invention preferably has a form in which the surface of the refractory particles is coated with a binder composition or a binder for a mold. The coating of the binder composition for a mold or the binder can be performed by using various conventionally known techniques. For example, a method such as a dry hot coating method, a semi-hot coating method, a cold coating method, and a powdered solvent method can be used. Among them, the dry hot coating method is preferable because of excellent productivity. During the production of the mold material, a lubricant or the like may be added as an optional component, if necessary. In addition, heated refractory particles (aggregate) 100
0.2 to 10 parts by weight of the resin composition and 0.1 to 0.1 parts by weight of hexamethylenetetramine to the resin composition.
It is well known to add 1 to 30 parts by weight.

According to the present invention, a co-condensation resin of a triazine derivative and a phenol, or a co-condensation resin of a triazine derivative and a phenol and / or a triazine as a binder for binding refractory particles as aggregates. By using a resin composition obtained by mixing a derivative and a phenolic resin, and further forming a mold using a binder composition for a mold obtained by adding a disintegration improver, mechanical strength and easy disintegration A mold having excellent thermal stability and small dimensional stability is obtained. The mold thus obtained has good collapsibility even when the casting temperature is relatively low, such as aluminum casting, and has a small coefficient of thermal expansion, so that the product has excellent dimensional accuracy and cracks in the mold during casting. It is also prevented from occurring. Particularly, [-NH-
CH ₂ - phenol] bond number, [- NH-CH ₂ -NH
-] bond number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - phenol] is the average percentage of bonding number 30 to 80%, a number average molecular weight (Mn) of 300 ８００800, and a ratio (Mw) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
When a phenol / triazine derivative co-condensation resin having a physical property value of (/ Mn) of 1.30 or less is used as a binder for bonding refractory particles to each other, high mechanical strength and low thermal expansion in a mold are achieved. In addition, good disintegration can be obtained without adding a disintegration enhancer. If a disintegration improver is added, the disintegratability is further improved. Further, a phenol-triazine derivative co-condensation resin having the above physical properties, a phenol resin, or a phenol resin and a triazine derivative,
Alternatively, it may be used in combination with a phenol / triazine derivative co-condensation resin whose physical property value is out of the above range.In such a case, good mechanical strength, low thermal expansion and easy disintegration can be achieved, and The advantage that the cost can be reduced as compared with the case where the phenol / triazine derivative co-condensation resin having physical properties is used alone is obtained.
The material for a mold of the present invention is particularly suitable as a material for a shell mold, and the phenol / triazine derivative co-condensation resin having the above-mentioned physical properties is useful as a binder for a shell mold.

[0035]

EXAMPLES Hereinafter, the effects of the present invention will be clarified by showing specific examples. << Production Example of Binder >> With the composition shown in Table 1, a binder composition for a mold or a binder was produced. In Examples 1 to 7 and Comparative Example 1, a disintegration improver was added to obtain a binder composition. In Examples 1 to 7 and Comparative Examples 1 to 3, a silane coupling agent was added as a surface modifier. Table 1
In the above, the numbers indicate the amount of compounding, and the unit is part by weight.

Example 1 Binder Composition Using Mixed Resin Composition of Phenol Resin and Triazine Derivative First, phenol 940. was added to a four-necked flask equipped with a stirrer, a reflux condenser and a thermometer. 0 parts by weight, 567.6 parts by weight of formalin having a concentration of 37% by weight, and 9.4 parts by weight of oxalic acid as a reaction catalyst are precisely weighed and gradually stirred until the reflux temperature (about 100 ° C.) is reached. Warmed. After reaching the reflux temperature, reflux reaction was performed for 2 hours. After the distillation reaction, a dehydration reaction was further performed under vacuum to obtain a phenol resin P1. Next, 100 parts by weight of the phenol resin P1
20 parts by weight of melamine, 1 part by weight of γ-aminopropylalkoxysilane as a silane coupling agent,
3 parts by weight of sodium glutamate was added and mixed as a disintegrating agent to obtain a binder.

(Example 2) Pheno by a well-known manufacturing method
Of Binder Using Polycondensation Resin of Triol and Triazine Derivatives
In the same apparatus as in Example 1, phenol 940.0 weight
Parts, melamine 20 parts by weight, concentration of 37% by weight formalin
Accurately weigh 567.6 parts by weight and 9.4 parts by weight of oxalic acid
And reach the reflux temperature (about 100 ° C) with stirring
Until the temperature rose. Let react for 2 hours at reflux,
After the distillation reaction, a dehydration reaction is further performed under vacuum to
Thus, a tri-triazine derivative co-condensation resin C1 was obtained. Next, 1
00 parts by weight of phenol / triazine derivative co-condensation resin
Γ-amino as a silane coupling agent for C1
1 part by weight of propylalkoxysilane as disintegration improver
And add 3 parts by weight of sodium glutamate and mix.
A binder was obtained. Phenol tria obtained in this example
About gin derivative co-condensation resin C1, ¹³C-NMR measurement
[-NH-CH_Two-Phenol] bond, [-N
H-CH_Two-NH-] bond, and [phenol-CH_Two
-Phenol] bond density.
The ratio was calculated. For the measurement, "JN" manufactured by JEOL Ltd.
M-LA400 type nuclear magnetic resonance apparatus "was used. The result
As a result, [-NH-CH_Two-Pheno
The ratio of the number of bonds was 3%. Also, the weight average
Molecular weight (Mw) and number average molecular weight (Mn)
Uses HLC-8020, a high-speed GPC device manufactured by Co., Ltd.
did. As a result, the number average molecular weight (Mn) was 670.
Weight average molecular weight (Mw) and number average molecular weight (Mn)
(Mw / Mn) was 2.27.

Example 3 Binder Composition Using Phenol / Triazine Derivative Cocondensation Resin According to First Production Method Using the same apparatus as in Example 1, a concentration of 37% by weight was added to 126 parts by weight of melamine. 81 parts by weight of formalin
The temperature was raised to 0 ° C. After reacting at 80 ° C. for 1 hour, 320 parts by weight of methanol was added and reflux reaction was performed for 2 hours. To this reaction solution, 846 parts by weight of phenol was added, the temperature was raised to 180 ° C. while removing methanol and dehydrating under normal pressure, and unreacted phenol was removed under reduced pressure to form a phenol / triazine derivative cocondensation resin C2. Obtained. Next, with respect to 100 parts by weight of the phenol / triazine derivative co-condensation resin C2, γ-
1 part by weight of aminopropylalkoxysilane and 3 parts by weight of sodium glutamate as a disintegration improver were added and mixed to obtain a binder. The phenol obtained in this example
About triazine derivative co-condensation resin C2, [-NH-CH ₂ -phenol] bond,
[-NH-CH ₂ -NH-] bonds, and [phenol -CH ₂ - phenol] and the density of binding was measured weight average molecular weight (Mw) and number average molecular weight (Mn).
As a result, [—NH—CH ₂ —
[Phenol] bond number was 70%. The number average molecular weight (Mn) is 470, and the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
Was 1.10.

Example 4 Binder Composition Using Mixed Resin Composition of Phenol / Triazine Derivative Co-Condensation Resin and Phenol Resin An example was prepared by adding 50 parts by weight of the phenolic resin P1 obtained in Example 1. 50 parts by weight of the phenol / triazine derivative cocondensation resin C2 obtained in Step 3 were added, 1 part by weight of γ-aminopropylalkoxysilane was added as a silane coupling agent, and 3 parts by weight of sodium glutamate was added as a disintegration enhancer and mixed. Thus, a binder was obtained. Example 5 Binder Composed of a Mixed Resin Composition of Triazine Derivative and Phenol Resin To 100 parts by weight of phenolic resin P1 obtained in Example 1, 10 parts by weight of benzoguanamine was used as a silane coupling agent. 1 part by weight of aminopropylalkoxysilane and 3 parts by weight of sodium glutamate as a disintegration improver were added and mixed to obtain a binder.

Example 6 A binder composition was obtained in the same manner as in Example 4 except that the disintegration improving agent was changed to 10 parts by weight of triphenyl phosphate. Example 7 A binder composition was obtained in the same manner as in Example 3 except that the disintegration improving agent was changed to 10 parts by weight of tetrabromobisphenol A.

Example 8 A binder was obtained in the same manner as in Example 4 except that the disintegrating agent and the silane coupling agent were not added. That is, to 50 parts by weight of the phenolic resin P1 obtained in Example 1, 50 parts by weight of the phenol / triazine derivative co-condensation resin C2 obtained in Example 3 were added and mixed to obtain a binder.

Comparative Example 1 Binder Composition Consisting of Phenol Resin A phenol resin P1 was obtained in the same manner as in Example 1. Next, 1 part by weight of γ-aminopropylalkoxysilane as a silane coupling agent and 10 parts by weight of tetrabromobisphenol A as a disintegration improver are added to 100 parts by weight of the phenol resin P1, and mixed. A composition was obtained. (Comparative Example 2) A binder was obtained in the same manner as in Comparative Example 1 except that the disintegration improver was not added. That is, phenol resin P1 was obtained in the same manner as in Example 1. next,
1 part by weight of γ-aminopropylalkoxysilane as a silane coupling agent was added to 100 parts by weight of the phenol resin P1 and mixed to obtain a binder.

Comparative Example 3 Binder Composed of Bisphenol A-Modified Phenolic Resin In the same apparatus as in Example 1, phenol 752.0 parts by weight, bisphenol A 456.0, formalin 567.6 parts by weight with a concentration of 37% by weight were used. And 9.4 parts by weight of oxalic acid as a reaction catalyst were precisely weighed and gradually heated to a reflux temperature (about 100 ° C.) with stirring. After reaching the reflux temperature, a reflux reaction was performed for 2 hours. After the distillation reaction, a dehydration reaction was further performed under vacuum to obtain a modified phenol resin P2. Next, 1 part by weight of γ-aminopropylalkoxysilane was added as a silane coupling agent to 100 parts by weight of the modified phenol resin P2 and mixed to obtain a binder.

(4) Molding material (resin-coated sand)
Production Example 1 A resin-coated sand for a shell mold was produced using each binder composition or binder obtained in each of the above Examples and Comparative Examples. First, a binder composition or 1.5 parts by weight of a binder was added to 100 parts by weight of a flattery sand previously heated to 150 ° C. using a speed mixer for hot coating manufactured by Enshu Tekko Co., Ltd. After kneading for 1 minute, 20 parts by weight of an aqueous solution of hexamethylenetetramine having a concentration of 15% by weight was added and further kneaded. When the kneaded sand changed from the wet state to the dry state, 0.1 part by weight of calcium stearate was added as a lubricant to 100 parts by weight of the flattery sand, and after mixing, the sand was discharged and cooled to room temperature. Thus, a resin coated sand for a shell mold mold was obtained.

{Preparation of Test Piece} In order to evaluate the disintegration of the mold, test pieces were prepared using each of the resin-coated sands obtained above. That is, 1
Using a heating mold of 0 mm × 10 mm × 60 mm, 250
A test piece was formed under the conditions of firing at 60 ° C. for 60 seconds and cooled to room temperature. << Evaluation of Disintegration >> Each of the test pieces thus obtained was wrapped in aluminum foil and subjected to heat treatment for a predetermined time shown in Table 2 using electric furnaces heated to 500 ° C. and 400 ° C., respectively. After cooling to room temperature after the heat treatment, the aluminum foil was peeled off and the bending strength of the test piece was measured. The bending strength before the heat treatment was measured in advance, and the value was used as the initial strength. The bending strength after the heat treatment was defined as the residual strength. Furthermore, the strength residual ratio was determined by the following mathematical formula (1), and this was used as an index of disintegration. The smaller the values of the residual strength and the residual strength ratio, the better the disintegration. The results of the measurement are shown in Table 2 below. Formula (1): Residual strength ratio (%) = (residual strength / initial strength) × 100

{Evaluation of Coefficient of Thermal Expansion} A cylindrical test piece having a diameter of 20 mm and a height of 50 mm was prepared using each of the resin-coated sands obtained above, and after 700 ° C. × 3 minutes or 1000 ° C. × 3 minutes. The subsequent coefficient of thermal expansion was measured. The results are shown in Table 2 below.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

As described above, according to the present invention, a binder composition for a mold suitable for molding a mold having excellent mechanical strength and easy disintegration, small thermal expansion and good dimensional stability. A material or binder is obtained. The mold formed using the binder composition for a mold or the binder of the present invention has good disintegratability even when the casting temperature is relatively low, such as an aluminum casting. In addition, since the coefficient of thermal expansion is small, the dimensional accuracy of the product is excellent, and the mold is prevented from being cracked during casting. The material for a mold of the present invention is particularly suitable as a material for a shell mold, and [-NH-CH
₂ - phenol] bond number, [- NH-CH ₂ -NH-] bonding number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - phenol] average percentage of bond number 30-80%, the number average molecular weight (M
n) is 300 to 800, and the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
The phenol / triazine derivative co-condensation resin having a value of 1.30 or less is effective as a binder for shell mold. Therefore, according to the present invention, a shell mold having excellent mechanical strength and easy disintegration, small thermal expansion and good dimensional stability can be obtained.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Seiji Takagi 700 Shukudaidaicho, Takasaki-shi, Gunma F-term in Gunei Chemical Industry Co., Ltd. (reference) 4E092 AA01 AA02 AA03 AA07 AA21 AA23 AA26 AA28 AA33 AA41 AA45 BA06 BA08 BA09 CA03

Claims (10)

[Claims] 1. A binder comprising a binder composition and a disintegration enhancer as essential components, wherein said binder comprises a resin composition containing a triazine derivative and a phenol, and said disintegration enhancer comprises phosphorus. A binder composition for a mold, which is at least one selected from the group consisting of an acid ester, a halogen compound, an organic carboxylate, a thermoplastic resin, a glycol, an alkali metal nitrate, an amino acid, and an amino acid salt. . 2. The binder composition for a mold according to claim 1, wherein the binder comprises a co-condensation resin of a triazine derivative and a phenol. 3. The binder according to claim 1, wherein the binder comprises a resin composition obtained by mixing a co-condensation resin of a triazine derivative with a phenol and / or a triazine derivative and a phenol resin. A binder composition for a mold. Wherein some or all of the co-condensation resin of the triazine derivative and a phenol is, [- NH-CH ₂ - phenol] bond _{number, [- NH-CH 2 -NH-} ] bonding number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - average percentage of phenol] binding number is 30 to 80%, a number average molecular weight (M
n) is 300 to 800, and the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
Is a phenol / triazine derivative co-condensation resin having a molecular weight of 1.30 or less, the binder composition for a mold according to any one of claims 2 and 3. 5. The method according to claim 1, wherein the disintegration enhancer is added in an amount of 1 to 50 parts by weight based on 100 parts by weight of the resin composition used as the binder. 3. The binder composition for a mold according to item 1. 6. A mold material comprising the refractory particles and the binder composition for a mold according to any one of claims 1 to 5. 7. will contain refractory particles and binder as essential components, wherein the binder is, [- NH-CH ₂ - phenol] bond _{number, [- NH-CH 2 -NH-} ] bonds number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - phenol] average percentage of number of bonds is 30 to 80%, a number average molecular weight (M
n) is 300 to 800, and the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn).
Characterized by comprising a phenol / triazine derivative co-condensation resin having a molecular weight of 1.30 or less. 8. The material for a mold according to claim 7, wherein the binder comprises a resin composition obtained by mixing the phenol / triazine derivative co-condensation resin with a phenol resin. 9. The mold material according to claim 7, wherein said binder comprises a resin composition obtained by mixing said phenol / triazine derivative co-condensation resin, triazine derivative and phenol resin. 10. A co-condensation resins of triazine derivative and a phenol, [- NH-CH ₂ - phenol] bond _{number, [- NH-CH 2 -NH-} ] bonding number, and [phenol -CH ₂ - phenol] relative to the total of the number of bonds [-NH-CH ₂ - phenol] average percentage of bond number 3
0 to 80% and a number average molecular weight (Mn) of 300 to 8
And a phenol / triazine derivative cocondensation resin having a weight average molecular weight (Mw) and a number average molecular weight (Mn) ratio (Mw / Mn) of 1.30 or less. Agent.