JPS6144583B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing a mold. The method of the present invention can be applied to obtain molds from refractory particulate solid materials, particularly for obtaining cores and main molds for foundries. Refractory fine particulate solid substances typically used in manufacturing molds such as cores and main molds for casting include silica sand, zircon sand, and chromite sand. These are also sometimes called mold aggregates. Traditionally, the foundry industry has used "inorganic binders" such as cement and water glass to bind aggregates together. However, when producing castings using these binders, there are problems such as poor molding productivity, poor collapsibility after casting, poor surface finish of castings, poor dimensional accuracy, and recycling of aggregates such as silica sand. In recent years, organic binders have been in the spotlight due to limitations in their use, and have greatly improved the above-mentioned drawbacks. Organic binders include acid-curing binders, mainly furan-based binders, and urethane-type binders, and they are used in a "self-hardening" manner in which they self-cure in the presence of a catalyst or accelerator, and in a catalytic manner. Alternatively, there is a "cold box" method for high-speed mold production in which an accelerator is blown into a mold as a gas to react and harden.
In this cold box usage method, sulfur dioxide gas is used for the acid-curing type, and amine gas is used for the urethane type, so these gases must be used on the premise that they will be used in a closed system and for final treatment, so it is necessary to use the gases that are suitable for each. Equipment had to be installed and it had to be put into practical use. Regarding a method that does not use sulfur dioxide gas or amine gas in manufacturing a mold, there is a method disclosed in JP-A-50-29423. This method utilizes polymerization of acrylic acid ester to bond aggregates such as silica sand, and when obtaining molds such as cores and main molds, the inside of the mold is kept in a substantially oxygen-free state. This can be said to be the third type of cold box that enables high-speed mold production within several seconds to several minutes by blowing inert gas such as nitrogen gas or carbon dioxide gas. The technology disclosed in this application has the great advantage of not requiring the use of harmful gases such as sulfur dioxide gas or amine-containing gas, as well as high production speed. However, JP-A-1973-
The invention disclosed in Publication No. 29423 is a method that can mold a mold under the limited conditions of ``providing an environment substantially free of oxygen'' and ``in the presence of peroxide.'' Although the present invention commonly uses acrylic esters or methacrylic esters, it does not use "peroxides" that require care in handling and storage, and is produced in a "substantially oxygen-free environment". This invention is different from the invention of JP-A-50-29423 in that the mold can be formed not only anaerobically but also under normal conditions, that is, in air. The property of the present invention, which can be polymerized and cured in air at room temperature to form a mold, is the "self-hardening" property of the "vinyl polymer" which is completely different from "acid curing type" and "urethane type", and it is a long-awaited furan in the industry. It is the third organic self-hardening binder system after urethane-based and urethane-based binders, and on the other hand, when it is polymerized and hardened anaerobically, it can be said to be a "cold box". That is, the present invention provides an amine activator comprising cobalt naphthenate or cobalt octenoate and a carboxylic acid, a polymerization accelerator comprising N.N-dialkylallylamine, a fine particulate solid substance, and an acrylic ester or methacrylic acid. The present invention provides a method for manufacturing a mold in air at room temperature by mixing with ester (hereinafter simply referred to as ester) and polymerizing and curing it in the absence of peroxide,
It also provides a method that can be carried out in an environment substantially free of oxygen. The amines used as polymerization accelerators in the present invention are N.N-dialkylallylamines such as N.N-dimethylaniline and N.N-dimethyltoluidine. Further, the amine used in the present invention is preferably a liquid one. The amine activator referred to in the present invention is composed of cobalt naphthenate or cobalt octenoate (hereinafter referred to as cobalt soap) and carboxylic acid. is not valid. Regarding the carboxylic acid, which is one of the essential components of the amine activator used in the present invention, basically any carboxylic acid having 2 or more carbon atoms can be used, but water or alcohol is preferred. or have a high solubility for the ester, or are themselves liquid carboxylic acids.
Specific examples of such carboxylic acids include acetic acid, propionic acid, caprylic acid, acrylic acid, methacrylic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, cyanoacetic acid, bromoacetic acid, and chloropropionic acid. Among these, those that can be used to bind and mold silica sand in the presence of oxygen in a self-hardening manner can also be molded in a nitrogen environment. For example, trichloroacetic acid can cause a reaction in a self-hardening manner, but it cannot be used in the mold. Sufficient strength can be provided when used in a nitrogen atmosphere. The fine particulate solid material used in the present invention is, for example, a refractory fine particulate solid material, and in particular for casting, specific examples include silica sand, zircon sand, and chromite sand.
However, the method of the present invention does not limit the type of solid material or the use of the molded product. Next, the structure of the ester in the present invention is not particularly defined, but polyfunctional esters are naturally preferred in view of the intended use. Specific examples include polyfunctional esters with a single structure such as ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; An oligoester type in which several (meth)acrylic acid ester groups are incorporated at the ends of a basic carboxylic acid oligoester, a urethane type having (meth)acrylic acid ester groups at the ends of a urethane oligomer, or even an epoxy type. Polyfunctional esters having a specific molecular weight distribution can also be used as the esters referred to in the present invention. Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. When mixing the ester, cobalt soap, dialkylallylamine, carboxylic acid, and a fine particulate solid material, such as silica sand, each component may be added separately, or, for example, the dialkylallylamine may be premixed with the ester and added. However, it is preferable to avoid mixing cobalt soap with the ester or mixing all three components other than the ester. This is because mutually unfavorable reactions may occur. Furthermore, in the present invention, "an environment substantially free of oxygen" means that an inert gas such as nitrogen gas or carbon gas is aerated into the molded model to replace it with air, or oxygen is eliminated by exposing it to reduced pressure, or This can be achieved by first venting inert gas and then blocking the air. Naturally, the main purpose of the method of the present invention is to perform the process at room temperature, but when solid particles such as silica sand are heated or used anaerobically, an inert gas is heated or molds etc. It goes without saying that the reaction speed can be accelerated by heating the model. Next, standard formulations and mixing ratios when using the present invention to manufacture molds will be explained. The amount of ester is 0.8 to 3%, preferably 1 to 2%, based on the aggregate such as silica sand. Cobalt soap is 0.5-15% based on ester, preferably 1-5%, N.
N-dialkylallylamine is also 0.5 to 10%, preferably 1 to 5%, based on the ester, and carboxylic acid is 0.5 to 10%, preferably 1 to 5%, based on the ester.
It is. Examples are shown below, and the molded test piece used was 50 mmφ x 50 mmH, and the curing performance was measured in terms of coercive pressure (compressive strength) (Kg/cm ² ). The kneading method used an efficient mixer, and the ester was mixed first, then the amine, then the cobalt soap, and then the carboxylic acid. When curing in air for self-hardening, the mixture was kneaded and then poured into split molds using a manual filling method. When curing in a cold box or anaerobically, after kneading, put a rammer into a cylinder with an inner diameter of 50 mmφ and an inlet and outlet pipe, close the inner cylinder, and flow nitrogen gas through the inlet pipe at a flow rate of 20/min. It was released from the same outlet pipe. After stopping the nitrogen gas for 10 seconds, the inlet and outlet were closed and the atmosphere was maintained for 110 seconds.
The test piece was taken out and the resistance pressure was measured.
That is, it is shown by the counter pressure after 2 minutes. All percentages in the formulation examples are by weight. The main aggregate used is silica sand, an Australian product with the brand name Freemantle. The particle size structure is as shown in Table 1 below.

[Table] Among the carboxylic acids shown in the examples, substances that are solid at room temperature were used in aqueous solutions. The name of the acid was used as is. Example 1 Blend; Various esters (Table 2) 2% of each to silica sand N.N-dimethylaniline 2% to ester cobalt octenoate 2.5% to ester acrylic acid 2% to ester The above formulation was used for "self-hardening" and air was added. The results of curing at room temperature (25°C) are shown in Table 2 below.

【table】

[Table] Example 2 Formulation; Various esters (Table 3) 2% each to silica sand N.N-dimethylaniline 5% to ester cobalt octenoate 5% to ester acetic acid 5% to ester Same as Example 1. The results of curing as "self-hardening" are shown in Table 3 below.

[Table] Example 3 Formulation; Trimethylolpropane triacrylate
2% vs. silica sand N・N-dimethylaniline 2% vs. ester acrylic acid 2% vs. ester Cobalt soap (Table 4) (Table 4) vs. ester The results of curing as "self-hardening" in the same manner as in Example 1 are as follows. As shown in Table 4 below.

[Table] Example 4 Formulation; Trimethylolpropane triacrylate
2% to silica sand N.N-dimethyltoluidine 1% to ester cobalt octenoate 2.5% to ester acrylic acid 1% to ester Similarly, the results of curing as "self-hardening" were as shown in Table 5 below.

[Table] Example 5 Formulation; Trimethylolpropane triacrylate
2% to refractory aggregate N・N-dimethylaniline 2% to ester cobalt octenoate 5% to ester acrylic acid 2% to ester Similarly to Example 1, refractory aggregates other than silica sand were hardened as "self-hardening". The results are shown in Table 6 below.

[Table] Example 6 Formulation; Trimethylolpropane triacrylate
2% silica sand N・N-dimethylaniline 5% ester cobalt octenoate 5% ester carboxylic acid (Table 7) 5% each ester Similarly, the results of hardening as "self-hardening" are as follows: As shown in Table 7.

[Table] Example 7 Formulation; M-8030 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) 2% to silica sand N.N-dimethylaniline 5% to ester cobalt octenoate 5% to ester carboxylic acid (Table 8) Table 8) For esters, similarly, the curing characteristics as "self-hardening" are as follows:
It is as shown in the table.

[Table] Example 8 Trimethylolpropane triacrylate
% silica sand as shown in Table 9 below, and was cured ``anaerobically'' using nitrogen gas. The counter pressure after passing gas for 10 seconds and holding for 110 seconds at 25° C. is shown as the counter pressure after 2 minutes.

[Table] Example 9 Compound Novolac epoxy acrylate ^* 2% to silica sand N・N-dimethylaniline 3% to ester cobalt octenoate 3% to ester acrylic acid 3% to ester *Nippon Kayaku R-113 and Neo Mixture of Pentyl Glycol Diacrylate The kneaded sand prepared in the above formulation was immediately poured into a mold after being kneaded, and its curing characteristics in air, that is, as self-hardening, were evaluated. The results were as follows.

【table】

Claims (1)

[Claims] 1 An amine activator consisting of cobalt naphthenate or cobalt octenoate and carboxylic acid and N.
A method for producing a mold, which comprises mixing a polymerization accelerator containing N-dialkylallylamine, a particulate solid substance, and an acrylic ester or a methacrylic ester, and polymerizing and curing the mixture in the absence of peroxide.