JPH0559256A - Acid curing agent composition and synthetic resin composition - Google Patents

Abstract

PURPOSE:To obtain an acid curing agent having a long serviceable time without changing a curing rate. CONSTITUTION:Copper sulfide is added to an acid curing agent constituted of xylenesulfonic acid and sulfuric acid to prepare an acid curing agent compsn. This is mixed with sand and then well admixed with a furfuryl alcohol-urea- formaldehyde resin to prepare a curable resin compsn. The serviceable time of the curable resin compsn. can be lengthened hardly changing the curing rate thereof to facilitate the handling of the curable resin compsn. as compared with the use of the conventional acid curing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acid curing agent composition for improving the pot life of a curable synthetic resin, and a curable synthetic resin composition containing the acid curing agent composition. is there.

[0002]

2. Description of the Related Art Furfuryl alcohol-urea-formaldehyde resin, resol-type phenol-formaldehyde resin, furfuryl alcohol-urea-phenol-formaldehyde resin and the like are used as binders for acid-curable resins, and they are cured at room temperature. Strong acids are used as the curing agent.

[0003]

However, the acid curing agent composed of a strong acid has a drawback that the pot life is short.

For example, in the field of casting, the above-mentioned synthetic resin and strong acid are used together to obtain casting sand, which is molded to produce a mold to produce casting, and the sand used once is Repeatedly used.

However, in the process of collecting and regenerating sand, the sand heated at a high temperature of 1400 ° C. and heated is used to cool the sand at once, but it does not always cool, and even if it cools, only the surface is cooled. The temperature of the sand is not uniform and the temperature is not stable. When it was attempted to prepare molding sand again using such sand, the curing reaction often started immediately and was often cured in a mixer in which the sand, synthetic resin and curing agent were mixed.

Under the present circumstances, there is a demand for a foundry sand binder which has a long pot life even when it is hardened at around room temperature and hardens immediately when hardening starts.

[0007]

SUMMARY OF THE INVENTION The inventors of the present invention have made extensive studies in view of the above circumstances and, surprisingly, when a specific heavy metal salt is added to strong acids, the synthetic resin composition is uncured. The inventors have found that the time that can be used under the above condition, that is, the pot life can be remarkably extended, and the present invention has been completed.

That is, the present invention provides an acid curing agent composition comprising a strong acid (A) and at least one salt (B) selected from the group consisting of heavy metal sulfonates, heavy metal sulfates and heavy metal chlorides, And a synthetic resin composition comprising the acid curing agent composition and a formaldehyde resin.

As the strong acids (A), any of known and conventional ones can be used. For example, inorganic mineral acids such as phosphoric acid and sulfuric acid, organic sulfonic acids such as paratoluenesulfonic acid, benzenesulfonic acid and xylenesulfonic acid. Is mentioned. The strong acids (A) may be used alone or in combination of two or more. Usually, an organic sulfonic acid is used, but it is preferable to use an inorganic mineral acid together with the organic sulfonic acid when the curing speed is increased or the atmosphere is relatively low temperature.

As the salt (B), a heavy metal sulfonate,
At least one salt selected from the group consisting of heavy metal sulfates and heavy metal chlorides is used. Heavy metal has a specific gravity of 4.0
The above metals are mentioned, for example, cobalt, nickel,
Examples include chromium, iron, copper, manganese, molybdenum, zinc, titanium and the like.

Examples of the salt (B) include cobalt paratoluenesulfonate, nickel paratoluenesulfonate,
Chromium paratoluene sulfonate, iron paratoluene sulfonate, copper paratoluene sulfonate, manganese paratoluene sulfonate, manganese paratoluene sulfonate, molybdenum paratoluene sulfonate, zinc paratoluene sulfonate, cobalt benzene sulfonate, xylene sulfonate Heavy metal sulfonate of cobalt, cobalt sulfate,
Heavy metal sulfates such as nickel sulfate, chromium sulfate, iron sulfate, copper sulfate, manganese sulfate, molybdenum sulfate, zinc sulfate, cobalt chloride, nickel chloride, chromium chloride, iron chloride, copper chloride, manganese chloride, molybdenum chloride, zinc chloride, etc. Heavy metal chlorides of These salts (B) may be used alone or in combination of two or more kinds. These salts (B) themselves are
In the temperature range of about 0 to 50 ° C., most of the later-described synthetic resins to be cured cannot be cured.

The acid curing agent composition of the present invention comprises a strong acid (B).
It can be easily obtained by adding salt (B) to. The amount of the salt (B) to be added to the strong acid (A) is not particularly limited, but usually 0.05 to 5 parts by weight of the salt (B) per 100 parts by weight of the strong acid (A), a curing unique to the strong acid used. It is preferable to use 0.1 to 3 parts by weight from the viewpoint that the speed is not significantly changed and the pot life is prolonged effectively.

The acid curing agent composition of the present invention only needs to contain a strong acid (A) and a salt (B) as essential components, and water may be added as necessary to adjust the absolute value of the curing rate. Alternatively, an organic solvent may be used in combination.

As the organic solvent, any known and commonly used organic solvent can be used. For example, acetone, methanol,
Examples thereof include ethanol, toluene, xylene, methyl ethyl ketone, terpene, ethylene glycol, propylene glycol, and tetrahydrofuran.

The absolute value of the curing rate can be adjusted by appropriately diluting the composition comprising the strong acid (A) and the salt (B) with water or an organic solvent. In many cases, the acid curing agent composition of the present invention is usually diluted with a strong acid (A) to a concentration of 30 to 90% by weight and used.

When the acid curing agent composition of the present invention is used as an acid curing agent for a foundry sand binder, it is used at a low concentration when the air temperature and the sand temperature are high, and at a high concentration when the temperature is cold in the winter or when the sand temperature is cold. Is common.

The acid curing agent composition of the present invention thus obtained can extend the pot life until the synthetic resin is cured while maintaining the curing rate of the conventional curing agent. Next, the other aspect of the present invention will be described. Another aspect of the present invention is a curable synthetic resin composition comprising a formaldehyde resin and the above acid curing agent composition.

The formaldehyde resin used in the present invention refers to a synthetic resin obtained by reacting a formaldehyde supply substance with a compound capable of addition or condensation with it as an essential component, such as a resol-type phenol-formaldehyde resin, urea-formaldehyde resin, Furfuryl alcohol-formaldehyde resin and the like can be mentioned.

The formaldehyde resin that can be used here is not particularly limited, but preferably has a number average molecular weight of 200 to 2000, more preferably 300 to 700.

The resol-type phenol-formaldehyde resin can be obtained by reacting, for example, a formaldehyde supply material and phenols as essential components in the presence of a catalyst, if necessary, in a molar ratio of 1.0 or more. Can be easily obtained.

Examples of the formaldehyde supplying substance include an aqueous formaldehyde solution (so-called formalin) and paraformaldehyde. As the phenols, any of the conventionally known ones can be used. For example, phenol, bisphenols such as bisphenol F, bisphenol A, bisphenol AF, cresol,
Alkyl-substituted phenols such as P-tert-butylphenol, halogenophenols such as bromophenol, phenols containing two or more phenolic hydroxyl groups such as resorcin, 1-naphthol, 2-naphthol, 1,6-dihydroxynaphthalene, Naphthols such as naphthols such as 2,7-dihydroxynaphthalene,
Alternatively, dimethoxyxylylene, paravinylphenol, isopropenylphenol and the like can be mentioned. Not only are these phenols alone, but these compounds
You may use it in mixture of 2 or more types.

As the catalyst, any known catalyst can be used, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, barium hydroxide and calcium hydroxide.

In producing the resol type phenol-formaldehyde resin, furfuryl alcohol, furfural, urea, melamine, acetoguanamine, benzoguanamine and the like may be used in combination, if necessary.

On the other hand, the furfuryl alcohol-formaldehyde resin can be easily obtained, for example, by reacting furfuryl alcohol and the above-mentioned formaldehyde supplying substance as essential components in the presence of a catalyst, if necessary.

As the formaldehyde supplying substance and catalyst, any of those which can be used in the production of the resol type phenol-formaldehyde resin can be used.

Of course, when producing a furfuryl alcohol-formaldehyde resin, the above-mentioned phenols, furfural, urea, melamine, acetoguanamine, benzoguanamine and the like may be used in combination, if necessary.

Examples of the furfuryl alcohol-formaldehyde resin include furfuryl alcohol / formaldehyde resin, urea / furfuryl alcohol / formaldehyde co-condensation resin, phenol / furfuryl alcohol / formaldehyde co-condensation resin, urea / phenol / full resin. Furyl alcohol / formaldehyde co-condensation resin and the like can be mentioned.

The formaldehyde resin obtained in the presence of a catalyst tends to have better curability when used after being washed with water. In producing the formaldehyde-based resin, the reaction may be carried out in the presence of an organic solvent or water, if necessary, or the reaction may be carried out in the absence thereof and then they may be added later. For example, when a formaldehyde resin containing an organic solvent or water is used, it is often unnecessary to newly dilute and use the acid curing agent composition.

The formaldehyde resin may be used alone, or two or more resins having different compositions may be used in combination as required. For example, a resol type phenol-formaldehyde resin and a furfuryl alcohol-formaldehyde resin may be mixed and used, or a resin obtained by co-condensing these resins may be used. Furthermore, the formaldehyde resin may be used as it is, or a mixture thereof or a cocondensation resin to which furfuryl alcohol, urea, phenol, or furfural is further added.

The synthetic resin composition of the present invention can be easily obtained by mixing the above acid curing agent composition with a formaldehyde resin. The amount of the acid curing agent composition used with respect to the formaldehyde resin is not particularly limited, but is usually 20 to 80 parts by weight, particularly 3 per 100 parts by weight of the resin solid content.
It is preferable to use 0 to 60 parts by weight.

The amount of the acid curing agent composition used with respect to the formaldehyde resin is appropriately switched to an acid curing agent composition comprising a strong acid having a higher curing rate, a curing agent having a lower curing rate, or diluted with water. It is preferable to adjust by adjusting the curing agent or mixing the curing agents.

The synthetic resin composition of the present invention may further contain sand, stones, fillers, release agents, flame retardants, surfactants, etc., if necessary. For example, when the synthetic resin composition of the present invention is used as a binder for foundry sand, the formaldehyde resin and the acid curing agent composition of the present invention may be kneaded with sand in this order, in the reverse order, or simultaneously. The foundry sand thus obtained can extend the pot life without changing the absolute value of the temperature required for the hardening temperature.

The synthetic resin composition of the present invention is, for example, various molding materials, glass fiber sizing agents, binders for foundry sand, binders for grinding wheels, adhesives, binders for friction materials, binders for refractory materials, It can be used in any fields where resol type phenolic resin has been used, such as binders for heat insulating materials, foam materials, resin concrete, rubber reinforcing agents, paints for various purposes, coating agents, etc. It can be expected to be made.

[0034]

The present invention will be described in more detail with reference to examples. Hereinafter, "parts" means parts by weight, unless otherwise specified.
"%" Means% by weight. Example 1 0.5 part of copper sulfate was added to an acid curing agent obtained by mixing 40 parts of xylensulphonic acid, 10 parts of sulfuric acid, and 50 parts of water, and dissolved at room temperature to obtain a curing agent composition 1.

5 kg of new Fremantle sand adjusted at 30 ° C. and 70% RH for 24 hours revolves at 20 RPM and rotates at 60 RP
16 of curing agent composition 1 in a planetary mold of M while stirring
Parts (amount corresponding to 40 parts based on 100 parts of furfural / urea / formaldehyde co-condensed resin described later), and then furfural / urea / formaldehyde co-condensed resin (nitrogen content 4.3%, pH 7.0, specific gravity) 1.17,
Viscosity 25cps or less) 40 parts (0.
(Amount equivalent to 8 parts) is sequentially added and kneaded well for 30 seconds,
A composition for casting mold was prepared.

Immediately after kneading, the mixture was well packed into a wooden mold having a diameter of 50 mm and a height of 50 mm, left standing at 30 ° C. and 70% RH, and the compressive strength (unit: kg / cm ² ) with time was measured. . This was defined as the normal strength.

On the other hand, after kneading, it is left as it is, and after 2 minutes,
After 4 minutes, 6 minutes, 8 minutes, and 10 minutes, the mold was put in and left in the same manner as the test piece of normal strength, and the compressive strength after 24 hours was measured. This is defined as the pot strength, and the pot strength is shown to show the length of pot life.

The results are shown in Table 1. Comparative Example 1 A composition for a casting mold was prepared in the same manner as in Example 1 except that the acid curing agent composition 1 except that 0.5 part of copper sulfate was used was used. Was measured.

The results are shown in Table 1. Example 2 A composition for a casting mold was prepared in the same manner as in Example 1 except that the amount of copper sulfate used was changed to 2 parts, and the normal strength and pot strength were measured in the same manner.

The results are shown in Table 1.

[0041]

[Table 1]

As can be seen from Table 1, the curable resin composition using the acid curing agent composition of the present invention can extend the pot life without changing the curing rate itself.

[0043]

In the present invention, since the acid curing agent is used in combination with at least one salt selected from the group consisting of heavy metal sulfonates, heavy metal sulfates and heavy metal chlorides, the curing rate of the curable resin composition itself The pot life can be significantly extended without changing the.

Therefore, for example, in the field of casting molds, it is effective in significantly extending the pot life of the kneading sand and reducing troubles during molding. Furthermore, since the corrosiveness of the metal due to the acid curing agent is significantly reduced, it is almost unnecessary to replace the metallic container, pump, valve, etc. when storing, transporting or distributing.

Claims (6)

[Claims] 1. A strong acid (A) and a heavy metal sulfonate,
An acid curing agent composition comprising at least one salt (B) selected from the group consisting of heavy metal sulfates and heavy metal chlorides. 2. The acid curing agent composition according to claim 1, wherein the strong acid (A) is sulfuric acid and / or aromatic sulfonic acid, and the salt (B) is a heavy metal sulfonate and / or a heavy metal sulfate. 3. The acid curing agent composition according to claim 1, wherein 0.05 to 5 parts by weight of the salt (B) is used with respect to 100 parts by weight of the strong acid (A). 4. The acid curing agent composition according to claim 1, wherein the salt (B) is at least one sulfonate selected from the group consisting of cobalt, nickel, chromium, iron, copper, manganese, molybdenum and zinc. Stuff. 5. A synthetic resin composition comprising the composition according to claim 1 and a formaldehyde resin. 6. The composition according to claim 5, wherein the formaldehyde resin is a furfuryl alcohol-formaldehyde resin or a resol-type phenol-formaldehyde resin.