JPH06142821A - Production of casting mold - Google Patents

Abstract

PURPOSE:To stably and efficiently produce the casting mold by using a hardener consisting of acid amide and/or urea deriv. as its effective component. CONSTITUTION:Granular refractory aggregate formed by mixing a phenolic resin soln., a polyisocyanate compd. soln. and granular refractory aggregate by a mixer and coating the mixture with a binder is introduced into a molding flask and is molded. The curing catalyst contg. the acid amide and/or urea deriv. is then introduced into the molding flask to cure the molding The phenolic resin to be used in the embodiment is a bendiether resin, resol resin and novolak resin having solubility in org. solvents. The polyisocynate compd. is arom., aliphat. or alicyclic polyisocynate. As a result, the curing of the casting mold is stably completed even if there are fluctuations in curing temp., the consumption of the curing catalyst, curing time, etc., as compared with the method of permeating the curing catalyst, such as ternary amine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in hardening behavior of a casting mold which is hardened and manufactured by the Ashland method.

[0002]

2. Description of the Related Art Conventionally, as a method for industrially manufacturing a casting mold, since heating is not required for manufacturing the mold, the Ashland method (eg, cold box method, no-bake method) is advantageous in terms of energy consumption. Law) is known. As an example, a method of manufacturing a mold by the Ashland cold box method will be described. First, the phenol resin solution,
The polyisocyanate compound solution and the granular refractory aggregate are mixed with a mixer to prepare a granular refractory aggregate coated with a binder, and the granular refractory aggregate is blown into a mold for producing a mold for molding. Next, a curing catalyst such as a tertiary amine is passed through the mold to cure at room temperature and demold to produce a casting mold.

[0003]

However, in the above-mentioned conventional method, there are cases where the curing of the mold is not completed due to variations in the curing conditions such as the curing temperature, the amount of the curing catalyst used, the curing time, etc. There are problems that the yield rate of mold production is lowered or becomes unstable. It is an object of the present invention to improve the efficiency of mold production by stably completing the curing of the mold even if the curing conditions change.

[0004]

In order to achieve the above-mentioned object, a method for producing a mold of the present invention comprises a granular fire resistance coated with a binder containing a phenol resin, a polyisocyanate compound, a curing accelerator and a solvent. A method of introducing an aggregate into a mold and molding the mixture, and then introducing a curing catalyst into the mold to cure the aggregate, wherein the curing accelerator contains an acid amide and / or a urea derivative as an active ingredient. It is characterized by

The phenol resin used in the present invention is an organic solvent-soluble benzyl ether resin, resole resin or novolac resin obtained by addition / condensation of phenols and formaldehyde.

As the polyisocyanate compound, known aromatic, aliphatic or alicyclic polyisocyanates can be used. Specifically, for example, diphenylmethane diisocyanate, polymethylene polyphenylene polyisocyanate (hereinafter referred to as Polymec MDI) ,
Hexamethylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate can be mentioned.

The hardening accelerator in the present invention is a component which increases the amount of hardening completed when a hardening catalyst is applied to the binder-coated granular refractory aggregate introduced into the mold, The active ingredients are acid amides and urea derivatives. These compounds may be used alone or as a mixture. The acid amide includes an imide, and examples thereof include N, N-dimethylacetamide, oleic acid amide, N, N-dialkylbenzamide, N-alkylsuccinimide, and a cyclic acid such as N-methyl-2-pyrrolidone. Amides are also preferred. Examples of the urea derivative include tetramethylurea, N, N′-diphenylurea and the like, 1,3
Cyclic ureas such as -dimethyl-2-imidazolidone are also preferred.

As the solvent for the binder, any solvent used in the preparation of the binder-coated granular refractory aggregate in the Ashland method can be used in the present invention. Specifically, an organic solvent such as an aliphatic hydrocarbon type, an alicyclic hydrocarbon type, an aromatic hydrocarbon type, a halogenated hydrocarbon type, a ketone type, an ester type, an ether type, or an alcohol type is used alone or as a mixture. Can be used. Furthermore, the binder solution is a silane compound such as 3-glycidoxypropyltrimethoxysilane for improving the adhesion between the resin component and the aggregate, if desired, and isophthalic acid chloride as a pot life extender. In addition to the acid chloride as an example, a deterioration inhibitor, a drying inhibitor, a release agent and the like can be included.

The granular refractory aggregate used in the present invention is, for example, all kinds of sand including fine sand, clay sand, reclaimed sand, etc. Sand of about 50 to 600 μm is particularly preferable. The mixing ratio of the phenol resin, the polyisocyanate compound or the solvent to the granular refractory aggregate is 0.01 to 10% by weight based on the granular refractory aggregate in order to improve the curability of the mold and secure the strength. A range is preferred,
Particularly, the range of 0.1 to 5.0% by weight is preferable. The curing accelerator is preferably used as an active ingredient in an amount in the range of 1 to 50 parts by weight, particularly preferably in an amount of 5 to 20 parts by weight, based on 100 parts by weight of the phenol resin. .

Preparation of the binder-coated granular refractory aggregate is carried out, for example, by using a binder solution consisting of a phenol resin, a polyisocyanate compound, a curing accelerator and a solvent, and the granular refractory aggregate, preferably -10 to 50. It can be carried out at a temperature in the range of ° C by sufficiently kneading the components so that the components are uniformly mixed. The binder solution is prepared by separately preparing a phenol resin solution and an isocyanate compound solution in advance, and adding a curing accelerator to either one or both of them, or a curing accelerator solution is prepared separately from these solutions. It is preferable to prepare and add these solutions to the granular refractory aggregate at the time of kneading with the granular refractory aggregate. The prepared binder-coated granular refractory aggregate, for example, is stored in a sand magazine, the desired amount is introduced into the mold making mold by blowing with air, then, such as base, amine, metal ions A mold is manufactured by introducing a curing catalyst usually used in the Ashland method into the mold and removing the mold.

[0011]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Hereinafter, all "parts" mean "parts by weight". Examples 1 to 4 First, 50 parts of benzyl ether group-containing phenol resin manufactured by Hodogaya Chemical Co., Ltd., 20 parts of isophorone, 30 parts of petroleum-based solvent (SW-1800 manufactured by Maruzen Sekiyu KK) and 3
A solution consisting of 0.3 parts of glycidoxypropyltrimethoxysilane was prepared. In this solution, a predetermined amount of the curing accelerator N shown in Table 1 was added to 50 parts of the phenol resin.
-Methyl-2-pyrrolidone was added and dissolved. Separately, a solution consisting of 75 parts of polymeric MDI, 25 parts of a petroleum solvent (IP-150 manufactured by Idemitsu Kosan Co., Ltd.) and 0.3 part of isophthalic acid chloride was prepared. The phenol resin solution and the polyisocyanate solution were added at a ratio of 0.9 parts to 100 parts of Fremantle silica sand, and kneaded with a Shinagawa mixer for 90 seconds. A diameter of 460 parts of the binder-coated sand that can be connected to the ventilation device is 50
mm and a height of 300 mm were weighed in a cylindrical mold and solidified so that the packing density was 1.67 g / cc. Next, 0.03 ml of triethylamine was injected into the aeration device with a microsyringe, connected to the mold, and subjected to aeration curing at 30 liters / min for 40 seconds. One minute after aeration, the sand mold was taken out and the hardened portion was weighed. In addition,
The binder-coated sand was transferred to the sand magazine of a V-TOP330C cold box molding machine manufactured by Naniwa Seisakusho equipped with a die for dog-bone type sand mold, and blown into the sand magazine at a gauge pressure of 3.0 kgf / cm ^2. It was blown into a dogbone-shaped sand mold. Next, a triethylamine gas generator was used to perform gassing with a gauge pressure of 2.5 kgf / cm ² for 1 second to allow the inside of the mold to permeate and cure, followed by air purging with a gauge pressure of 3.0 kgf / cm ² for 3 seconds. The mold was demolded to produce a dogbone-shaped sand mold, and the density and tensile strength of this sand mold were measured. Table 1 shows the results of weighing the hardened parts of the manufactured mold (sand mold) and the performance thereof.

[Table 1] From Table 1, it was possible to remarkably increase the amount of curing without lowering the density and tensile strength of the mold. Further, the tensile strength (moisture resistance) after standing for 24 hours in an atmosphere of room temperature and 90% humidity was also improved.

Examples 5-7 A mold was prepared in the same manner as in Example 1 except that a predetermined amount of oleic acid amide was used as the curing accelerator instead of the predetermined amount of N-methyl-2-pyrrolidone. Was manufactured. Table 2 shows the results of weighing the hardened parts of the manufactured mold.

[Table 2]

Examples 8 to 10 Similar to Example 1 except that 5 parts of the curing enhancer shown in Table 3 was used in place of the predetermined amount of N-methyl-2-pyrrolidone as the curing enhancer. Then, a mold was manufactured. Table 3 shows the results of weighing the hardened parts of the produced mold.

[Table 3] Comparative Example 1 A mold was produced in the same manner as in Example 1 except that the curing enhancer was not used. Table 1 or Tables 2 and 3 show the results of weighing the hardened parts of the produced molds and their performances.

[0014]

As described above, according to the present invention, the curing amount can be increased without deteriorating the performance required for the casting mold such as the tensile strength of the manufactured mold. Therefore, the completion of the curing of the mold becomes more complete, and even if the curing conditions vary depending on the season, for example, the yield rate of the mold production is dramatically improved and stabilized, and the efficiency of the mold production can be significantly improved. As a result, the amount of the curing catalyst used can be reduced and the curing time can be shortened.

Claims (1)

[Claims] 1. A granular refractory aggregate coated with a binder containing a phenol resin, a polyisocyanate compound, a curing accelerator and a solvent is introduced into a mold to be molded, and then the curing catalyst is introduced into the mold. In the method for producing a mold for introducing and curing the above, the curing accelerator contains an acid amide and / or a urea derivative as an active ingredient.