JP2885395B2 - Hardener composition for mold production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a mold,
The present invention relates to a curing agent composition for producing a mold for accelerating the curing of an acid-curable resin such as a furan resin or a phenol resin as a binder.

[0002]

2. Description of the Related Art Conventionally, alkyl (C ₁ -C ₄ ) substituted aromatic sulfonic acids have been used as a curing agent for accelerating the curing of acid curable resins such as furan resins and phenol resins. For example, an aqueous solution such as xylene sulfonic acid is generally used. However, in the xylene sulfonic acid aqueous solution, as the xylene sulfonic acid concentration is higher, the crystals are likely to precipitate. In particular, when the curing speed of the acid-curable resin is to be accelerated at a low temperature in winter, the concentration of the xylene sulfonic acid aqueous solution must be increased. It was sometimes clogged by precipitation.

For this reason, the curing agent composition contains 50 to 95% by weight of an alkyl-substituted aromatic sulfonic acid, and 10 to 50% by weight of xylene sulfonic acid and 50 to 50% of ethylbenzene sulfonic acid as an alkyl-substituted aromatic sulfonic acid.
It has been proposed to use one consisting of 90% by weight (Japanese Patent Publication No. 4-56025). When this curing agent composition is used, since xylene sulfonic acid and ethylbenzene sulfonic acid are contained in a well-balanced manner, the sulfonic acid in the curing agent composition can be prevented from precipitating to some extent in winter, which is preferable. . However, it is not enough to increase the aromatic sulfonic acid concentration in winter in the winter with a curing agent containing an aromatic sulfonic acid to further increase the acid strength, and it is necessary to add an inorganic acid such as sulfuric acid. In that case, in order to prevent crystal precipitation at low temperatures, a lower alcohol such as methanol was conventionally added, but there was a risk of ignition and various restrictions were imposed on production equipment, transportation, storage and handling.

[0004]

In order to avoid such a problem, the amount of the alkyl-substituted aromatic sulfonic acid in the curing agent composition described in JP-B-4-56025 must be reduced. Can be considered. However, when the amount of the alkyl-substituted aromatic sulfonic acid is reduced, the curing rate of the acid-curable resin cannot be accelerated, and a high-strength mold cannot be produced in a short time.

[0005] Accordingly, an object of the present invention is to provide a curing agent composition for producing a mold, wherein the curing rate of an acid-curable resin is not reduced even when the amount of an alkyl-substituted aromatic sulfonic acid is reduced. In order to achieve the above object, a specific amount of an inorganic acid for accelerating the curing of the acid-curable resin is contained, and a specific amount of ethylbenzenesulfonic acid is contained so that the alkyl-substituted aromatic sulfonic acid does not precipitate in winter. That is.

[0006]

That SUMMARY OF THE INVENTION The present invention is an alkyl (C ₁ ~C ₄₎ 10~45% by weight substituted aromatic sulfonic acid, a lower (C ₁ ~C ₄₎ alcohol 4-12 wt%, inorganic A curing agent composition for producing a mold, comprising an acid and water, wherein the content of ethylbenzene sulfonic acid in an alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid (y weight%)
Relates to a curing agent composition for producing a mold, characterized by satisfying the following formulas (1) and (2). ^{y <1.6137x 4 -6.9891x 3 -3.9963x 2} + 16.572x + 84.773 ......... (1) y> -21.622x 4 + 112.48x 3 -205.5x 2 + 147.61x-5.1287 ......... (2) [ In the formulas (1) and (2), x represents an inorganic acid (% by weight) / water (% by weight) in the curing agent composition for mold production, and
0.6 <x <3.3. Also, y> 0. ]

[0007] The curing agent composition for producing a mold according to the present invention comprises:
The alkyl (C ₁ -C ₄ ) substituted aromatic sulfonic acid is
It contains 5% by weight. As the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid, aromatic sulfonic acid may have 1 to carbon atoms
Those having one or more alkyl groups of 4 are used, and specifically, xylenesulfonic acid, ethylbenzenesulfonic acid, mesitylenesulfonic acid, cumenesulfonic acid, diethylbenzenesulfonic acid and the like are used. In particular, it is preferable to use an alkyl (C ₁ -C ₄ ) substituted aromatic sulfonic acid composed of xylene sulfonic acid and ethylbenzene sulfonic acid. This is because, according to this combination, precipitation of crystals in winter is small, and a curing promoting effect is exerted on various acid-curable resins, so that the versatility is high. If the amount of the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid is less than 10% by weight, it is difficult to obtain a high-strength template, which is not preferable. On the other hand, if the amount of the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid exceeds 45% by weight, sulfonic acid may be precipitated at a low temperature in winter, which is not preferable.

The curing agent composition for producing a mold according to the present invention contains a lower (C ₁ -C ₄ ) alcohol. As lower alcohol, methanol, ethanol, isopropyl alcohol and the like are used. The lower alcohol has an effect of preventing the precipitation of an alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid, and methanol is particularly preferable since this effect is remarkable. The content of lower (C ₁ -C ₄ ) alcohol is preferably 4 to 12% by weight. Lower alcohol content of 4% by weight
If it is less than 3, the effect of preventing the precipitation of the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid crystals tends to decrease. On the other hand, the content of lower alcohol is 12% by weight.
If it exceeds, there is a risk that the obtained curing agent composition for producing a mold may have a risk of ignition.

The curing agent composition for producing a mold according to the present invention contains an inorganic acid. As inorganic acids,
Sulfuric acid, phosphoric acid, or the like is used. The inorganic acid has a function of accelerating the curing of the acid-curable resin, and sulfuric acid is particularly preferable since the effect is remarkable. The content of the inorganic acid is 0.1% with respect to the amount of water in the curing agent composition for mold production.
It is contained in a ratio of 6 to 3.3. If the content ratio of the inorganic acid to water is less than 0.6, the effect of promoting the curing of the acid-curable resin decreases, which is not preferable. On the other hand, when the content ratio of the inorganic acid to water exceeds 3.3, a large amount of the inorganic acid remains in the obtained template, and the physical properties of the template are undesirably reduced. When sulfuric acid is used as the inorganic acid and methanol is used as the lower alcohol, methyl sulfuric acid and water are partially generated in the curing agent composition for producing a mold. The amount and the content of methanol are determined based on the amount of sulfuric acid and the amount of methanol initially added and blended. If the amount of sulfuric acid and the amount of methanol initially added are unknown, the curing agent composition for mold production is topped at 120 ° C. under reduced pressure of 10 mmHg, methanol is subjected to gas chromatography, and water is Karl Fischer. By the method, the amount of sulfuric acid is determined by potentiometric titration.

In the present invention, the content (% by weight) of ethylbenzene sulfonic acid in the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid contained in the curing agent composition for producing a mold is as follows: It is necessary that the ratio satisfies the expressions (1) and (2). That is, equation (1) is expressed as [y <
^{1.6137x 4 -6.9891x 3 -3.9963x 2 + 16.572x} + 84.77
3]. Equation (2) is expressed as [y> −21.622.
is that ^{x 4 + 112.48x 3 -205.5x 2 +} 147.61x-5.1287]. Here, x used in the formulas (1) and (2) indicates the ratio of the content of the inorganic acid to the amount of water in the curing agent composition for producing a mold. Therefore, as described above, x takes an arbitrary value in the range of 0.6 to 3.3. Further, since ethylbenzene sulfonic acid is always contained in the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid, y is always larger than 0 (ie, y>
0). When the content (% by weight) of ethylbenzene sulfonic acid in the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid does not satisfy the formula (1), the content of ethyl benzene sulfonic acid becomes relatively high. This is not preferable because the balance with other sulfonic acids may be deteriorated and sulfonic acid crystals may precipitate. In addition, when the formula (2) is not satisfied, the content ratio of ethylbenzenesulfonic acid is relatively low, and there is a possibility that sulfonic acid crystals are precipitated, which is not preferable.

In the present invention, the more preferable content ratio (% by weight) of ethylbenzenesulfonic acid in the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid is represented by the following formula:
It is a range satisfying (3) and (4). That is, equation (3) is
^{[Y <-2.4892x 4 + 25.657x 3} -86.42x 2 + 85.415x +
60.782]. Equation (4) is expressed as [y> −
^{9.8752x 4 + 46.656x 3 -69.815x 2 +} 26.902x + 38.22
2]. Here, x used in the formulas (3) and (4) is the same as x used in the formulas (1) and (2) with respect to the amount of water in the curing agent composition for mold production. It shows the ratio of the content of the inorganic acid. Equation (1)
Similarly to (2), y> 0 is satisfied. When the content (% by weight) of ethylbenzene sulfonic acid in the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid does not satisfy the formula (3), the content of ethyl benzene sulfonic acid slightly increases, When the curing agent composition for producing a mold is stored for a long period of time in winter, the sulfonic acid crystals tend to precipitate. In addition, even when the formula (4) is not satisfied, the content ratio of ethylbenzenesulfonic acid is slightly lowered, and when the curing agent composition for mold production is stored for a long time in winter, sulfonic acid crystals precipitate. Tend to occur.

In order to obtain a mold using the curing agent composition for producing a mold according to the present invention, an acid-curable resin and the curing agent composition for producing a mold according to the present invention are added and kneaded to a refractory granular aggregate. After filling the kneaded sand into a mold, the acid-curable resin is cured. As the refractory granular aggregate, in addition to quartz sand having quartz as a main component, fresh sand or recycled sand such as chromite sand, zircon sand, olivine sand, and alumina sand is used. As the reclaimed sand, those obtained by a usual mechanical abrasion type or roasting type are used, but those regenerated by the abrasion type have a high yield, are economically excellent, and are generally preferable. Further, for the purpose of further improving the mold strength, the silane coupling agent may be added to the acid-curable resin solution or when the acid-curable resin is added to the refractory granular aggregate. Examples of the silane coupling agent include γ- (2-amino) aminopropylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and the like can be used.

As a specific method for producing a mold using the curing agent composition for producing a mold according to the present invention, the following method can be employed. For example, with respect to 100 parts by weight of the refractory granular aggregate, 0.2 to 3 parts by weight of a curing agent composition for producing a mold according to the present invention is mixed, and then 0.5 to 5 parts by weight of an acid-curable resin is mixed. After kneading sand is obtained, the kneading sand is filled in a mold, and then the acid-curable resin is cured, whereby a mold can be manufactured. The order of addition of the curing agent composition for mold production and the acid-curable resin may be simultaneous, or the acid-curable resin may be added to the refractory granular aggregate first. As for the mixing, molding and curing temperatures, there is no particular need for heating or cooling, and the temperature may be adjusted depending on the ambient temperature. In addition, when using the curing agent composition for producing a mold according to the present invention, conventionally known additives such as an additive for promoting curing may be used.

[0014]

【Example】

Examples 1 to 17 and Comparative Examples 1 to 8 An industrial xylene containing 83% by weight of xylene (a mixture of ortho, meta, and para bodies) and 17% by weight of ethylbenzene were mixed with a predetermined amount of ethylbenzene. Then, alkyl-substituted aromatic sulfonic acids A to J shown in Table 1 were prepared.

[0015]

[Table 1]

The alkyl-substituted aromatic sulfonic acids A to J
, A lower alcohol, sulfuric acid and water were added so as to have the weight ratios shown in Tables 2 and 3 to prepare curing agent compositions No. 1 to 25 for mold production. In addition, all the amounts in Tables 2 and 3 are% by weight, the value of y is also% by weight, and only the value of x is unitless.

[0017]

[Table 2]

[0018]

[Table 3]

The curing agent compositions No. 1 to 25 for mold production obtained as described above were allowed to stand at -15 ° C.
After the elapse of days, it was determined whether or not crystals precipitated. The results are shown in Tables 4 and 5. In addition, Tables 4 and 5 also show which of the dangerous substance classifications according to the Fire Service Law this curing agent composition for producing a mold corresponds to. Then, using the curing agent compositions No. 1 to 25 for producing a mold, a mold was obtained as follows. That is, 0.5 parts by weight of the curing agent compositions No. 1 to 25 are added to 100 parts by weight of molding sand, and mixed for 1 minute. One part by weight of a furan resin is added to the mixed sand, and the mixture is further kneaded for one minute. A test piece was filled with the kneaded sand to prepare a mold, and the compressive strength of the mold after 24 hours was measured. The results are shown in Tables 4 and 5.

[0020]

[Table 4]

[0021]

[Table 5]

FIG. 1 is a plot of the curing agent compositions for mold production used in Examples 1 to 17 and Comparative Examples 1 to 8, with the value of y as the vertical axis and the value of x as the horizontal axis. is there. In addition, the curves (1) to (4) respectively correspond to the above equation (1).
4 to (4). The numbers with circles in FIG. 1 are the example numbers, and the numbers with triangles are the comparative example numbers. As is apparent from FIG. 1, the curing agent compositions for producing molds according to Comparative Examples 1 and 2 in which the weight% of ethylbenzenesulfonic acid is so large that the formula (1) is not satisfied, precipitates after 3 days. You can see that. In addition, it can be seen that the cured compositions for producing molds according to Comparative Examples 3 and 4 in which the amount by weight of ethylbenzenesulfonic acid is so small as not to satisfy the formula (2) also precipitate after 3 days. In the curing agent composition for producing a mold according to Comparative Example 5, although the precipitation of crystals could be prevented because the amount by weight of methanol was too large, the curing agent composition itself corresponds to a dangerous substance according to the Fire Defense Law. Further, in the curing agent composition for producing a mold according to Comparative Example 6, since the weight% of methanol was too small, precipitation of crystals was observed after 3 days. In the curing agent composition for producing a mold according to Comparative Example 7, since the weight percent of the alkyl-substituted sulfonic acid is too small, the precipitation of crystals hardly occurs, but the strength of the obtained mold is greatly reduced. In addition, in the curing agent composition for producing a mold according to Comparative Example 8, since the weight percent of the alkyl-substituted sulfonic acid was too large,
Crystals precipitate after 3 days.

On the other hand, it can be seen that the curing agent compositions for producing molds according to Examples 1 to 17 are less likely to cause precipitation of crystals, and that the obtained molds have high strength. In particular, the curing agent composition for mold production satisfying the formulas (3) and (4), that is, Examples 1, 3,
The curing agent compositions for producing molds according to 5, 6, 9, 10, 13 to 15 were preferable because no crystals were precipitated even after 30 days. On the other hand, the curing agent composition for producing a mold, which satisfies the formulas (1) and (2) but does not satisfy the formulas (3) and (4), ie, Examples 2, 4, 7, 8, 11 , 12,16,
In the curing agent composition for producing a mold according to No. 17, crystals were precipitated after a lapse of 10 to 30 days.

[0024]

As described above in detail, the curing agent composition for producing a mold according to the present invention comprises ethylbenzene sulfonic acid and another alkyl (C ₁ -C ₄ ) substituted aromatic sulfonic acid in a well-balanced manner. An alkyl-substituted aromatic sulfonic acid,
Since the aqueous solution composition contains a specific amount of a lower (C ₁ -C ₄ ) alcohol and a specific amount of an inorganic acid with respect to water, the aqueous solution composition contains an alkyl-substituted aromatic compound even at a low temperature in winter. Aromatic sulfonic acid hardly precipitates. Therefore, in order to produce a mold at a low temperature in winter, even if this curing agent composition is supplied by a pump or the like, this pump can be prevented from being clogged by precipitation of the alkyl-substituted aromatic sulfonic acid,
There is an effect that a high-strength mold can be continuously and efficiently manufactured.

In addition, since the curing agent composition for producing a mold according to the present invention contains only 12% by weight or less of lower alcohol, danger such as ignition is less likely to occur. Therefore,
The use of the curing agent composition for producing a mold according to the present invention has an effect that the safety of an operator can be improved.

[Brief description of the drawings]

FIG. 1 is a graph in which a vertical axis represents a value of y and a horizontal axis represents a value of x. The values of x and y of the curing agent composition for mold production used in Examples and Comparative Examples are shown in FIG. It is shown. Numbers with circles indicate examples, and numbers with triangles indicate comparative examples. In addition, (1) to (4) are curves representing equations (1) to (4), respectively.

Claims (5)

(57) [Claims] 1. An alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid 10-45% by weight, a lower (C ₁ -C ₄ ) alcohol 4
12%, inorganic acids, and a mold for producing the curing agent composition containing water, alkyl (C ₁ -C ₄₎ the content of ethylbenzene sulfonic acid in substituted aromatic sulfonic acid (y wt%) Satisfies the following formulas (1) and (2): ^{y <1.6137x 4 -6.9891x 3 -3.9963x 2} + 16.572x + 84.773 ......... (1) y> -21.622x 4 + 112.48x 3 -205.5x 2 + 147.61x-5.1287 ......... (2) [ In the formulas (1) and (2), x represents an inorganic acid (% by weight) / water (% by weight) in the curing agent composition for mold production, and
0.6 <x <3.3. Also, y> 0. ] 2. An alkyl (C ₁ -C ₄ ) substituted aromatic sulfonic acid 10-45% by weight, a lower (C ₁ -C ₄ ) alcohol 4
12%, inorganic acids, and a mold for producing the curing agent composition containing water, alkyl (C ₁ -C ₄₎ the content of ethylbenzene sulfonic acid in substituted aromatic sulfonic acid (y wt%) Satisfies the following formulas (3) and (4): y <−2.4892x ⁴ + 25.657x ³ −86.42x ² + 85.415x + 60.782 …… (3) y> −9.8752x ⁴ + 46.656x ³ −69.815x ² + 26.902x + 38.222 …… (4) [In the formulas (1) and (2), x represents an inorganic acid (% by weight) / water (% by weight) in the curing agent composition for producing a mold, and
0.6 <x <3.3. Also, y> 0. ] 3. The curing agent composition according to claim 1, wherein the alkyl (C ₁ -C ₄ ) -substituted aromatic sulfonic acid comprises xylene sulfonic acid and ethylbenzene sulfonic acid. 4. The curing agent composition for producing a mold according to any one of claims 1 to 3, wherein methanol is used as the lower alcohol. 5. The curing agent composition according to claim 1, wherein sulfuric acid is used as the inorganic acid.