JPH0620583B2 - Peroxide composition for mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an oxidizing agent used when sulfur dioxide is added to a granular refractory aggregate mixture containing an acid-curable resin and an oxidizing agent to form a mold. It is about. More specifically,
The present invention relates to a specific organic peroxide composition used as an oxidizing agent for the acid-curable mold.

[Conventional technology]

Conventionally, cloning methods that use novolac-type phenol resin as a binder and heat cure, or hot-box method that heat-cures liquid phenol resin or furan resin is generally used for high-speed mold production applications such as automobile castings. It has been. All of them are usually baked and cured at 200 to 300 ° C., which causes various problems such as energy consumption, curing time, mold distortion, dimensional defect of casting due to deformation, and working environment.

In recent years, a so-called cold box method, in which a gaseous or aerosol substance is blown at room temperature to form a mold, has been drawing attention and spreading as a molding method for improving these difficulties.

As a cold box method, there is a urethane cold box method in which a polyol compound and polyisocyanate are used as a binder and a tertiary amine is used as a catalyst for curing. However, in the urethane cold box method, even when the granular refractory mixture to which the polyol and polyisocyanate are added is left standing, the curing reaction gradually proceeds, and the pot life of the mixture is short, or soot defects, gas defects, etc. There are problems such as many casting defects. Another cold-box method currently available is an acid-curable cold-box method in which a thermosetting resin and an oxidizer are added to a granular refractory material, and then sulfur dioxide is blown to mold a mold.

[Problems to be solved by the invention]

In this method, the curing reaction does not proceed unless the particulate refractory mixture and sulfur dioxide come into contact with each other, so that the mixture has a long pot life, and an acid-curable resin excellent in heat resistance represented by a furan resin is used as a binder. Therefore, there are advantages such as less casting defects. However, this acid-curable cold box method requires the use of an expensive organic peroxide as an oxidant, and there is a concern that the stability of the organic peroxide is uncertain. Oxide is required.

In addition, hydrogen peroxide solution is mentioned as an inexpensive and highly safe peroxide, but the hydrogen peroxide solution is easily decomposed by the alkali content, metal oxide, and other impurities contained in the granular refractory aggregate, The usable time after mixing the mixture obtained by adding and kneading the resin and the peroxide to the refractory aggregate, that is, the so-called usable time is short and cannot be used for the shaft.

[Means for solving problems]

Under these circumstances, the inventors of the present invention have conducted intensive studies and as a result have come to invent a peroxide composition for a curable mold which is inexpensive, highly safe, and excellent in performance.

That is, the present invention relates to a peroxide used as an oxidizing agent when a gaseous refractory aggregate mixture containing a thermosetting resin and an oxidizing agent is injected with gaseous or aerosol sulfur dioxide to produce a mold. A peroxide composition for a template, which is a ketone peroxide composition containing at least one dilution stabilizer selected from compounds represented by the following [I] and [II]: It relates to things.

[I]

(In the formula, R ₁ and X are the same or different alkyl groups,
The sum of carbon numbers of R ₁ and X is 2 to 20. ) [II] (In the formula, n is an integer of 1 to 3, and Y is an alkylene group having 2 to 3 carbon atoms, an alkenylene group, or an alkynylene group.

R ₂ and R ₃ may be the same or different, and the sum of all carbon atoms is an alkyl group, alkenyl group, alkynyl group having 3 to 20 carbon atoms,
It is a cycloalkyl group, an aryl group or an aralkyl group. ) Usually, a ketone peroxide composition undergoes a dropwise reaction in an aqueous hydrogen peroxide solution with a mineral acid such as sulfuric acid as a catalyst, an aliphatic or alicyclic ketone, and an aliphatic or aromatic dibasic acid diester as a carrier agent under cooling, After the reaction is completed, the aqueous layer is separated, and the non-aqueous layer is neutralized, washed, dried and purified to produce a non-aqueous peroxide composition. The manufacturing process of this product is complicated and it takes a lot of man-hours.
Not only is it expensive, but it is also non-aqueous, which poses a danger.

On the other hand, there are polyhydric alcohols such as glycerin, water-containing homogenized ketone peroxide compositions using nitrogen-containing water-soluble solvents such as N-methyl-2-pyrrolidone as a carrier agent,
These carrier agents serve as a curing retarder for the acid-curable resin and are inexpensive and highly safe, but when used as an oxidizing agent for the acid-curable cold box method, they cause mold curing failure and are practically unusable.

The peroxide composition of the present invention improves these problems, does not contain a solvent that serves as a curing retarder for homogenization, contains the above specific dilution stabilizer, and has an acid curable cold box method. As an oxidant, it is excellent in performance, does not require a complicated manufacturing process, is inexpensive, and is also excellent in safety against fire and the like, and thus provides practically satisfactory results.

As a preferred method for producing the ketone peroxide composition of the present invention, at least one of an aliphatic ketone having 3 to 8 carbon atoms or an aliphatic ketone having 6 to 10 carbon atoms is treated with an aqueous solution of hydrogen peroxide under an acid catalyst. In this method, a ketone peroxide formed by oxidation and the above-mentioned dilution stabilizer are mixed.

The proportion of each component in the peroxide composition of the present invention is 20 to 60% by weight of ketone peroxide, 80 to 40% by weight of a dilution stabilizer.
Is generally preferred, and preferably ketone peroxide 30 to
50% by weight, dilution stabilizer 70 to 50% by weight. Further, it may contain less than 5% by weight of water.

When the proportion of ketone peroxide exceeds 60% by weight, the concentration of active oxygen is increased, the tendency of spontaneous decomposition is accelerated, and the danger is significantly increased. When the proportion of ketone peroxide is less than 20% by weight, when the refractory granular aggregate and the ketone peroxide composition are kneaded, some of the ketone peroxide is decomposed by impurities present in the refractory granular aggregate. However, the absolute amount of sulfur dioxide as an oxidant is insufficient, and the curing speed is rapidly reduced. Further, even if the proportion of the dilution stabilizer is less than 40% by weight, the ketone peroxide becomes unstable and the tendency of spontaneous decomposition becomes faster, and the risk is significantly increased, while it is necessary to use more than 80% by weight. Absent. When the water content is 5% by weight or more, water is essentially a retarder for this curing reaction, and the curing rate becomes so slow that it cannot be practically used.

The composition of the present invention may contain a nonionic or anionic surfactant in addition to the above essential components.

Usually, when molding a mold, zircon sand or chromite sand is used as the granular refractory aggregate in addition to silica sand containing silica as a main component, but the present invention is not particularly limited to this. Examples of the acid-curable resin include furan resin, phenol resin, urea resin, melamine resin or co-condensates or mixtures thereof, and these resins are usually 5 to 20 parts by weight with respect to 1000 parts by weight of the granular refractory aggregate. Part used. The peroxide composition of the present invention is usually used in an amount of 3 to 10 parts by weight based on 1000 parts by weight of aggregate.

〔Example〕

Hereinafter, examples will be described to describe the present invention in more detail, but the scope of the present invention is not limited by these examples.

Examples 1-5 and Comparative Examples 1-5 Inventive and comparative ketone pars consisting of 1000 parts by weight of Australian flattery silica sand, 15 parts by weight of furan resin, 40 parts by weight of ketone peroxide and 60% by weight of dilution stabilizer. A circular mold (for measuring white smoke, mold weight 60 kg) and 25 x 25 were prepared by adding 5 parts by weight of the oxide composition and kneading.
A mold (for bending strength measurement) of × 250 m / m was filled, and then sulfur dioxide gas was injected into the mold filled with the mixture, followed by washing with clean air to mold the mold.

The molten metal at about 1420 ° C. was poured into the molded white smoke measuring mold, and the time from the pouring to the time when no white smoke was emitted was measured. or,
The bending strength measurement mold was measured for strength over time after molding. Further, the residual ratio of active oxygen after storage at 25 to 35 ° C. for 3 months was also examined. The results are shown in Table 1.

Claims (2)

[Claims] 1. A peroxide composition used as an oxidizing agent when a gaseous or aerosol sulfur dioxide is injected into a granular refractory aggregate mixture containing an acid-curable resin and an oxidizing agent to produce a mold. A peroxide composition for a template, which is a ketone peroxide composition containing at least one dilution stabilizer selected from the compounds represented by the following [I] and [II]. [I] (In the formula, R ₁ and X are the same or different alkyl groups,
The sum of carbon numbers of R ₁ and X is 2 to 20. ) [II] (In the formula, n is an integer of 1 to 3, Y is an alkylene group having 2 to 3 carbon atoms, an alkenylene group or an alkynylene group. R ₂ and R ₃ may be the same or different, and all of the carbon numbers are An alkyl group having a sum of 3 to 20, an alkenyl group, an alkynyl group,
It is a cycloalkyl group, an aryl group or an aralkyl group. ) 2. The method according to claim 1, wherein the ketone peroxide is at least one of an aliphatic ketone peroxide having 3 to 8 carbon atoms and an alicyclic ketone peroxide having 6 to 10 carbon atoms. Composition.