Mold release material for die castings

Details Mold release material for die castings Mold release material for die castings

1993-09-16

1995-01-03

Green, Anthony

Compositions: coating or plastic

Coating or plastic compositions

Molds and mold coating compositions

106 3824, 106 3825, 106243, 106244, B28B 738, B28B 736

Patent

active

053782704

DESCRIPTION:

BRIEF SUMMARY
INDUSTRIAL FIELD OF THE INVENTION

This invention relates to an improvement in a mold release material for die castings.


PRIOR ART

Known mold release materials for die castings are ones based on animal and vegetable oils or mineral oil and to which base material is added fatty acid, paraffin wax, silicone oil, graphite and the like to give heat resistance. However, it is known that though such additives may present a mold release material of high heat resistance, adding only fatty acid or paraffin wax causes an increase of viscosity of the mold release material emulsion or causes difficulties in automatic spraying of the material. Adding silicone oil or graphite either causes defects in the product such as crimp or blow holes as a result of the residual solids remaining in the die casting mold or pollutes the mold.
On the other hand, mold release materials for die castings, which are added with solids, are also commercially available. However, where they are used by automatic spraying under a centralized piping feed system, they cause clogging of the nozzle of the automatic spray and working difficulties.
The mold release material of the present invention does not use additives such as silicone oil and graphite which generate residual solids in the die casting mold, and its bases comprise only one or more of animal and vegetable oils, mineral oil, fatty acid and esters thereof. As a result, it does not cause pollution of the die casting mold by silicone oil or graphite, E contamination of the working environment by graphite, or any other public nuisance since the waste water can be easily disposed.
However, water-soluble emulsions constituted only of fats and fatty oil have drawbacks in that the viscosity of the aqueous solution greatly varies. There is a large increase in viscosity as the temperature of the solutions rises, and in an extreme case, the aqueous solution gelatinizes.


DISCLOSURE OF THE INVENTION

To achieve the above objects, in the mold release material of the invention to an emulsion based on one or more of animal and vegetable oils, mineral oil, fatty acid and ester thereof is added an alkali metal or alkaline earth metal salt of ethylenediaminetetraacetic acid (hereinafter referred to as alkali metal or alkaline earth metal salt of EDTA).
The inventor of this invention has conducted extensive research in an attempt to produce and provide a new mold release material for die castings, and as a result he has found that an alkali metal or alkaline earth metal salt of EDTA prevents the aqueous solution of emulsions of these mold release materials from micell formation, forms a stable emulsion that is hardly affected by temperature, and even enables use of hard water as the diluted water of the mold release material to form bivalent metal ion and water soluble complexes that do not form deposits.


BEST EMBODIMENTS TO CARRY OUT THE INVENTION

As described above, the mold release materials for die castings relating to this invention form a stable emulsion by adding to the components of the material an alkali metal or alkaline earth metal salt of EDTA in the range of 10-10,000 ppm. Further, it is confirmed that the addition of alkali metal or alkaline earth metal salt of EDTA does not adversely affect the mold release effect of the material for die castings. To describe the effect of the invention more definitely, an Example for molding a die casting of an aluminum alloy is mentioned below.
If the alkali metal or alkaline earth metal salt of EDTA is added at less than 10 ppm, the effect of the additive is not noticed. If more than 10,000 ppm of the additive is added, an improvement in the effect is not confirmed either.
Below is mentioned an Example of the invention, which uses EDTA-4Na, a representative example of an alkali metal or alkaline earth metal salt of EDTA.


EXAMPLE

The following composition was obtained as a mix of the mold release material for die castings according to the invention.


______________________________________ Fatty acid quaternary ammonium salt 18% Hydrocarb

REFERENCES:
patent: 3034186 (1962-05-01), Holshouser
patent: 4609570 (1986-09-01), Couleau et al.
patent: 4634469 (1987-01-01), Laemmle et al.
patent: 5169891 (1992-12-01), Brown

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