JPS6144584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved mold release agent for die casting. More specifically, the present invention relates to a water-soluble mold release agent for die casting that prevents pollution of the factory environment and improves economic efficiency by simplifying the wastewater treatment process.

Die-casting mold release agents are used in high-temperature molds, so conventionally graphite, which has high heat resistance and a low coefficient of friction, is dispersed in hot oil such as mineral oil, fat, synthetic oil, wax, etc. have been used.

This type of mold release agent has high mold release performance. However, because it contains reactive graphite, it pollutes the natural and factory environments significantly, and when using a mold release agent, kerosene is exclusively used as a diluent, so when sprayed onto a hot mold, A large amount of hydrocarbon gas is generated, which has a negative impact on health, and
There was also a risk of fire.

Therefore, it is now rarely used except in cases where die casting is carried out under particularly harsh conditions.

In addition, in order to avoid environmental pollution caused by graphite, die-casting mold release agents are used that are made of a mixture of mineral oils, oils, synthetic oils, waxes, etc., excluding graphite, but these are very diluted. As long as kerosene was used as the agent, the problems of health hazards and fire hazards caused by the generated hydrocarbon gas could not be solved.

Those using kerosene as a diluent as described above are generally referred to as oil-based mold release agents. On the other hand, mold release agents for die casting that use water as a diluent have also been produced, and are called emulsified die casting mold release agents, and are currently widely used.

This emulsion is obtained by emulsifying and dispersing the above-mentioned mixed oils such as mineral oils, fats and oils, synthetic oils, waxes, etc. in water using an emulsifier. The advantage of this is that water can be used as a diluent, so when a mold release agent is injected into a hot mold, most of the gas generated is water vapor, so there is no adverse effect on health and there is no risk of fire. Furthermore, the latent heat of vaporization of water has a significant cooling effect on the mold.

However, in the case of this emulsified mold release agent, the oil forms an extremely stable emulsified state due to the emulsifier, and unlike the case where oil is simply mixed in water, it is different from the case where the oil is simply mixed in water. It is difficult to remove the oil to below the environmental standard (3 mg/) by simply doing so, and therefore it is necessary to perform the oil removal process using advanced technology and a huge processing cost, which ultimately increases the cost of die-cast products. It had the disadvantage of inviting people.

The present invention has been made to improve these conventional drawbacks, and is made by combining polyoxyethylene, polyoxypropylene, or a copolymer of both poly(oxyethylene/oxypropylene) with
Among the ether-type compounds of dihydric, dihydric, or polyhydric alcohols, water-soluble ones are selected as the main ingredient, and these are used singly or in a mixture of two or more.
The various materials used as additives are also water-soluble, and the mold release agent for die casting is completely water-soluble.

Therefore, since water can be used as a diluent when injected into a mold, the advantage of the conventional emulsified die casting mold release agent is that the gas generated when injected into a hot mold is reduced. The water-soluble mold release agent for die-casting of the present invention has the advantage that most of the water vapor is water vapor, so there is no adverse effect on health, there is no risk of fire, and there is a cooling effect on the mold due to the latent heat of vaporization of water. It is also equipped as is. A further advantage of the mold release agent according to the present invention is that, as can be inferred from the general chemical structural formula of the main component of the mold release agent described below, chemical bonds are broken at the ether bond positions when subjected to thermal decomposition. Therefore, residual carbon is extremely small, and therefore hydrogen gas generation is also minimal, which means that the mold is less contaminated and the incidence of blowholes is low.

Furthermore, the biggest advantage is that it is composed only of substances that are completely soluble in water, and its properties are a pale yellow transparent liquid that can be freely diluted with water, and the deoiling process can be omitted in the wastewater treatment process. It is. Even if oil is mixed in from another source, a simple oil removal process is sufficient.

The water-soluble mold release agent for die casting of the present invention has a pH of about 7 and is neutral, and when diluted 50 to 100 times before use, the BOD (oxygen consumption by activated sludge) is 150 to 300 mg/ As long as heavy metals and harmful substances are not mixed into the wastewater from the outside, it can be immediately subjected to activated sludge treatment, and has the advantage of easily obtaining wastewater that meets environmental standards.

Below, one of the polyoxyalkylene glycols that are the main components of the water-soluble mold release agent for die casting of the present invention.
By showing specific examples of general chemical structural formulas of valent, divalent, trivalent and polyvalent ether compounds, the material of the mold release agent according to the present invention will be further clarified.

(A) Example of ether type compound with monohydric alcohol R-O [CH ₂・CH ₂ O] _n [CH ₂・CH (CH ₃ ) O] _o・H (B) Ether type compound with dihydric alcohol example (C) Example of ether type compound with trihydric alcohol (D) Example of ether type compound with polyhydric alcohol In the above general chemical structural formula, R represents an alkyl group, and subscripts m and n are positive integers including 0 representing the number of moles of oxyalkylene.

In practice, mold release agents for die casting are determined by the size of the die casting machine, the method of the die casting machine (fully automatic, semi-automatic, manual, etc.), the type of casting alloy to be used, the weight of the casting, the shape of the mold, the working conditions ( The required properties differ somewhat depending on the amount of mold release agent sprayed, shot speed, etc.), and it is difficult to limit the types unconditionally, so the properties are currently adjusted for each target.

Next, specific formulation examples will be shown.

Example Polyoxypropylene glycol sorbitan ether (molecular weight 700, water soluble) 25 parts Poly(oxyethylene oxypropylene) glyceryl ether (molecular weight 2000, water soluble) 20 parts surfactant 10 parts antioxidant 1 part antifoaming agent 4 Part water 40 parts Example Poly(oxyethylene/oxypropylene) normal butyl ether (molecular weight 200, water soluble) 15 parts Poly(oxyethylene/oxypropylene) glyceryl ether (molecular weight 5000, water soluble) 30 parts Surfactant 10 parts Oxidation Inhibitor 1 part Antifoaming agent 4 parts Water 40 parts Example Poly(oxyethylene/oxypropylene) trimethylolpropane (molecular weight 1000, water soluble) 10 parts Poly(oxyethylene oxypropylene) glyceryl ether (molecular weight 5000, water soluble) ) 30 parts polyoxyethylene polypropylene glycol ether (molecular weight 4600, water soluble) 10 parts antioxidant 1 part antifoaming agent 4 parts water 45 parts Among the properties required for a mold release agent for die casting, the most important ones are: These are heat resistance, lubricity, lubricant film strength, and adhesion to molds.

As for heat resistance, the raw materials themselves should be selected to have high heat resistance, but this can be improved by adding an appropriate antioxidant, if necessary.

In die casting, the molten alloy is forced into the mold at high speed, creating considerable frictional resistance on the mold surface. Therefore, the problem can be solved by adding a lubricity improver if necessary. In the above examples, surfactants with particularly high lubricity were selected and added.

Adhesiveness depends on the properties of the raw material itself, but it also greatly affects the viscosity and the interfacial tension of the dilutable release agent. Therefore, a large amount of surfactant is added so that the interfacial tension shows a sufficiently low value when diluted with water, and the viscosity is lower than that of polyoxyalkylene, which is the main component of the mold release agent for die casting of the present invention. It is adjusted by blending two or more types of alcohol ether type compounds and changing the mixing ratio as appropriate.

Since the mold release agent for die casting of the present invention has the above-mentioned formulation, it not only has the advantages of an emulsified die casting mold release agent, but also has extremely excellent effects that have never been seen before. . In other words, the gas generated when injected into a high-temperature mold is mostly water vapor, so it does not have any adverse effects on health, there is no risk of fire, and the conventional technology that the latent heat of vaporization of water has a cooling effect on the mold. In addition to the effects of the emulsified form, there is a new advantage in that during thermal decomposition, there is very little residual carbon and very little hydrogen gas is generated, resulting in less mold contamination and a lower incidence of blowholes. effective. Furthermore, the most outstanding advantage of the present invention is that the deoiling step can be omitted in the wastewater treatment process. Therefore,
It does not require an extremely sophisticated and difficult deoiling process to remove oil to below environmental standards, and can significantly improve economic efficiency. In addition, the mold release agent of the present invention is a light yellow transparent liquid and can be freely diluted with water, so it can be transported in a concentrated state.
It can be diluted 50 to 100 times during use, does not require transportation costs, is neutral, can be immediately subjected to activated sludge treatment, and can easily obtain wastewater that meets environmental standards, among other things. There are advantages.

Claims (1)

[Scope of Claims] 1. An ether type compound of polyoxyethylene, polyoxypropylene, or a copolymer of both poly(oxyethylene/oxypropylene) and a monohydric, dihydric or polyhydric alcohol, which is water-soluble. 1. A mold release agent for die casting, characterized in that a water-soluble mold release agent for die casting is used, and a water-soluble one such as an antioxidant, a lubricity improver, and a surfactant is blended therein as additives. 2. The mold release agent for die casting according to claim 1, wherein the water-soluble ether type compound is a single compound. 3. The mold release agent for die casting according to claim 1, wherein the water-soluble ether type compound is a mixture of two or more types.