JPS648680B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering waste wax used in a lost wax casting method.

In recent years, as one of the casting methods, the so-called lost wax casting method, in which a mold model is molded with a wax-like substance and then cast, has come to be adopted.

The present inventor previously invented a lost wax composition in which terephthalic acid or isophthalic acid is added to a wax composition for the purpose of improving the lack of strength of model materials and surface sinking of thick parts, etc., and filed a patent application. Ivy.

(Japanese Patent Publication No. 52-30218).

The model molded using this lost wax composition had high bending strength and a significantly low shrinkage rate, resulting in very small surface sinkage, smooth casting surface, and improved dimensional accuracy.

However, once this lost wax composition has been used, it cannot be reused because it is difficult to remove moisture from the steam used to melt the molded model and remove it from the mold, as well as sand from the mold. Unable to do so, we had to discard all of it and always use new ones. Therefore, it has been desired to develop a method for recycling this waste wax.

The present inventor was studying to develop a method for recycling this waste wax, and discovered that a wax composition as good as new could be recovered by washing the wax using a specific method, and completed the present invention.

That is, the gist of the present invention is a lost wax recovery method characterized by using a lost wax composition containing terephthalic acid or isophthalic acid in a lost wax casting method and bringing the obtained waste wax into contact with an alkaline solution.

Wax components used in the present invention include paraffin, ceresin, carnauba wax, castor wax, wax wax, beeswax, rosin, which are generally commercially available as waxes for lost wax models.
Examples include synthetic waxes and the like singly or in mixtures.

Commercially available coarsely crushed terephthalic acid or isophthalic acid may be used as is, but in order to obtain a smooth casting surface for the molded model, it is used after being finely pulverized to a particle size of 200 mesh or less, especially to the extent that 95% or more passes through a 325 mesh sieve. things are desirable.

Examples of the alkaline solution used in the present invention include aqueous solutions of alkaline substances such as sodium hydroxide and potassium hydroxide. Ethyl alcohol and other water-soluble organic solvents can also be added to these aqueous solutions.

To further explain the present invention, waste wax obtained by using the above-mentioned lost wax composition is collected, put into a suitable dissolving tank, water is added and the temperature is raised to dissolve the waste wax, and a predetermined amount of alkali is added. The solution may be added under stirring, stirred and mixed thoroughly, and then allowed to stand to separate and remove the lower aqueous layer. The wax component in the upper layer can then be dehydrated and dried by heating or other treatment to recover the wax component, and by adding terephthalic acid or isophthalic acid to the obtained wax component, a lost wax composition that is as good as new can be obtained. I can do things.

Next, the present invention will be explained with reference to examples, but the present invention is not limited to these examples.

Example 1 20 kg of waste wax was placed in a dissolving tank equipped with a stirrer, 50 kg of water was poured, and the temperature inside the dissolving tank was raised to 50°C.

Separately, approximately 1 g of the above waste wax was accurately weighed and collected in a 200 ml Erlenmeyer flask, and 100 ml of an equal volume mixture of benzene and ethyl alcohol was added, heated on a hot water bath until the waste wax was completely dissolved, and phenolphthalein was used as an indicator. Titration with N/10 normal potassium hydroxide aqueous solution required 264.60 ml of potassium hydroxide aqueous solution to reach the discoloration point. Therefore, the amount of isophthalic acid contained in 1 g of waste wax is 0.392 from the following formula.
7.8 kg of isophthalic acid is mixed in 20 kg of waste wax.

Amount of N/10 potassium hydroxide solution required to neutralize 1 g of waste wax (ml) / 0.675 ml (Amount of N/10 potassium hydroxide solution required to neutralize 1 g of isophthalic acid with a purity of 99.98%) =Amount of isophthalic acid contained in 1 g of waste wax Based on the above, the amount of sodium hydroxide required for 7.8 kg of isophthalic acid contained in 20 kg of waste wax was calculated as follows.

7800g (Isophthalic acid) / (Isophthalic acid molecular weight) 166 = 46.987 moles 2 moles of sodium hydroxide are required, 46.987 moles x
2 = 93.974 mol The molar concentration of sodium hydroxide is 1/40 (molecular weight)
=0.025 mole, so 93.974 mole/0.025 mole=
3758.96g 20kg of waste wax was dissolved and formed two layers with water, so it was stirred, and flaky sodium hydroxide (purity 99.99%) calculated above was added, the temperature was raised to 90°C, and stirring was performed for 30 minutes. Next, the mixture was allowed to stand for 30 minutes, the lower aqueous layer was separated, and the upper wax layer was collected in a separate container.

The obtained wax portion was dehydrated by stirring at a temperature of 110°C. The amount of wax obtained was 10.55 kg, and the recovery rate was 87.9% based on the pure wax content. Isophthalic acid is added to 10 kg of wax obtained here.
When 6.67 kg was added and thoroughly mixed, a wax composition similar to that of a new product was obtained.

Claims (1)

[Claims] 1. A method for recovering lost wax, which comprises using a lost wax composition containing terephthalic acid or isophthalic acid in a lost wax casting method, and bringing the obtained waste wax into contact with an alkaline solution.