JPS61276737A - Peroxide composition for casting mold - Google Patents

Abstract

PURPOSE:To provide the reduction of a production cost, the improvement of safety, etc. by forming hydrous acetone peroxide by emulsification and dispersion or solubilization with a surface active agent. CONSTITUTION:Acetone is oxidized by hydrogen peroxide water in the presence of an acid catalyst to form acetone peroxide which is then emulsified or dispersed or solubilized by the surface active agent with dialkyl ester of aliphat dibasic acid or arom. dibasic acid as a carrier agent. Such peroxide compsn. is composed of the components (weight %) consisting of 35-60% acetone peroxide, 35-60% water or water and carrier agent and 0.1-5% surface active agent. Since the compsn. is hydrous, the safety is improved as the oxidizing agent for an acid cold box method and since the process for production is simplified, the cost of production is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an oxidizing agent used when forming a mold by adding sulfur dioxide to a granular refractory aggregate mixture containing an acid-curable resin and an oxidizing agent. It is related to. More specifically,
The present invention relates to certain aqueous organic peroxide compositions used as oxidizing agents for the acid-curable molds.

[Conventional technology]

Conventionally, for high-speed mold production applications such as automobile castings, the cloning method, which uses novolac-type phenolic resin as a binder and heat-cures it, or the hot-box method, which heats and cures liquid phenolic resin or furan-based resin, has been widely used. has been used. All of these are 200-30
It is common to bake and harden at 0°C, which causes various problems such as energy consumption, hardening time, distortion of the mold, poor dimensions of the casting due to deformation, and work environment.

In recent years, the so-called cold box method, in which a mold is formed by blowing a gaseous or aerosol-like substance at room temperature, has been attracting attention and becoming popular as a molding method to overcome these difficulties.

As a cold box method, there is a urethane-based cold box method in which curing is performed using a polyol compound and a polyisocyanate as a binder and a tertiary amine as a catalyst. However, in the urethane cold box method, even if the granular refractory mixture containing polyol and polyisocyanate is left to stand, the curing reaction proceeds gradually, resulting in a short pot life of the mixture or problems such as drop defects, gas defects, etc. There are drawbacks such as many casting defects. Another cold box method currently available is an acid curing cold box method in which an acid curing resin and an oxidizing agent are added to granular refractories, and then sulfur dioxide is blown into the refractory to form a mold.

[Problem that the invention seeks to solve]

In this method, the curing reaction does not proceed unless the granular refractory mixture and sulfur dioxide come into contact with each other, so the pot life of the mixture is long. However, this acid-curing cold box method requires the use of expensive organic peroxides as oxidizing agents, and the stability of organic peroxides However, there is a need for inexpensive and highly safe peroxides.

Hydrogen peroxide is an inexpensive and highly safe peroxide, but hydrogen peroxide easily decomposes due to alkaline earth metal oxides and other impurities contained in the granular refractory aggregate. The usable time after mixing a mixture of fire-resistant aggregate with resin and peroxide, the so-called pot life, is so short that it is practically unusable.

[Means for solving problems]

Under such circumstances, the inventors of the present invention have conducted extensive research and have come up with the invention of a peroxide composition for curable molds that is inexpensive, highly safe, and has excellent performance.

That is, the present invention provides a peroxide composition that is used as an oxidizing agent when producing a mold by injecting gaseous or aerosolized sulfur dioxide into a granular refractory aggregate mixture to which an acid-curable resin and an oxidizing agent have been added. The present invention relates to a peroxide composition for molds, which is a hydrous acetone peroxide composition prepared homogeneously by emulsifying and dispersing or solubilizing with a surfactant.

Normally, an acetone peroxide composition is reacted dropwise with hydrogen peroxide using a mineral acid such as sulfuric acid as a catalyst and acetone and an aliphatic or aromatic dibasic acid diester as a carrier agent while cooling, and after the reaction is completed, the aqueous layer is separated. and neutralize and wash the non-aqueous layer.
It is a non-aqueous peroxide composition produced by drying and purifying. The manufacturing process for this product is complicated and requires a lot of man-hours, the yield is significantly lower considering the amount of raw materials used, and it is not only expensive, but also dangerous because it is non-aqueous.

On the other hand, polyhydric alcohols such as glycerin, N-methyl-2-
There are hydrous homogenized ketone peroxide compositions that use nitrogen-containing water-soluble solvents such as pyrrolidone as carrier agents, but these carrier agents act as curing retarders for acid-curing resins and are inexpensive and highly safe. When used as an oxidizing agent in the acid-curing cold box method, it causes poor curing of the mold, making it practically unusable.

The peroxide composition of the present invention improves these drawbacks, does not contain a solvent that acts as a curing retarder for homogenization, and is water-containing, so it has excellent performance as an oxidizing agent in the acid-curing cold box method. , does not require complicated manufacturing processes, is inexpensive, and
Since it is water-containing, it has excellent safety against fires, etc., and provides practically satisfactory results.

A preferred method for producing the hydrous acetone peroxide composition of the present invention is to oxidize acetone with aqueous hydrogen peroxide over an acid catalyst to oxidize acetone peroxide with a dialkyl aliphatic dibasic acid or an aromatic dibasic acid. This is a method of emulsifying, dispersing or solubilizing with a surfactant, using an ester or the like as a carrier agent, without separating water during or after production.

As the surfactant used in the present invention, it is preferable to use at least one type of nonionic or anionic surfactant.

The proportions of each component in the peroxide composition of the present invention are generally 35 to 60% by weight of acetone peroxide, 35 to 60% by weight of water or water and carrier agent, and 0.1 to 5% by weight of surfactant. It is.

Generally, when forming a mold, silica sand containing quartz as a main component, zircon sand, and chromite sand are used as granular refractory aggregate, but this does not particularly limit the present invention. Examples of acid-curable resins include furan resins, phenol resins, urea resins, melamine resins, and co-condensates or mixtures thereof, and these resins are usually used in an amount of 5 to 20 parts by weight per 1000 parts by weight of the granular fire-resistant aggregate. part is used. The peroxide composition of the present invention usually has an aggregate of 1000
It is used in an amount of 3 to 10 parts by weight.

〔Example〕

Examples will be described below to explain the present invention in more detail, but the scope of the present invention is not limited by these Examples.

Examples 1 to 3 and Comparative Example 1 Acetone peroxide 50% by weight, carrier agent 33
% by weight, 1% by weight of surfactant, and 16% by weight of water as an oxidizing agent in the acid curing cold box process of the hydrous acetone peroxide composition according to the present invention and the commercially available hydrous ketone peroxide composition. In order to evaluate the performance, a mold was molded and the mechanical properties of the mold were investigated.

A mixture of 3000 parts by weight of Australian flattery silica sand, 35 parts by weight of furan resin, and 14 parts by weight of peroxide composition was added and kneaded at 25 * 25 x 250 m/m.
The mold was filled into a mold, gaseous sulfur dioxide was blown into the mold, and the mixture was cleaned with compressed air to form a mold.

After molding, the bending strength of the mold was measured over time. The results are shown in Table 1.

Claims (1)

[Claims] 1. Peroxide used as an oxidizing agent when manufacturing a mold by injecting gaseous or aerosolized sulfur dioxide into a granular refractory aggregate mixture to which an acid-curable resin and an oxidizing agent have been added. 1. A peroxide composition for molds, which is a hydrous acetone peroxide composition prepared homogeneously by emulsifying and dispersing or solubilizing with a surfactant. 2. The composition according to claim 1, wherein the surfactant is at least one of a nonionic surfactant and an anionic surfactant.