Method for Eliminating Pollutants Contained in an Elastic Part

Abstract

A method of eliminating pollutants contained in an elastomer part, the method including a step of extracting pollutants by immersing the part in a solvent, the solvent being ethanol.

Description

Various experimental results are provided in diagrams 1, 2, and 3.

Diagram 1 shows the percentage of extractables remaining on a nitrile rubber gasket as a function of the extraction time.

Diagram 1 shows that putting a nitrile rubber gasket into contact with ethanol, at a given temperature of 45° C. for example, presents an extremely advantageous effect on the extraction level of the pollutants contained in the gasket. After being immersed for 5 h in ethanol, a high reduction in the quantity of extractables contained in the gasket is observed, with the percentage of extractables remaining falling to 35%. Then, the experimental measurements reveal a steady reduction in the percentage of extractables remaining, passing to 25% of extractables remaining after 15 h, and to 7% of extractables remaining after 25 h.

Diagram 2 shows the percentage of extractables remaining on a nitrile rubber gasket as a function of extraction temperature.

The diagram shows the influence of temperature in the step of extracting, in ethanol, pollutants contained in a nitrile rubber gasket. By placing the nitrile rubber gasket in ethanol for 15 h at different temperatures, it can be seen that the percentage of extractables remaining varies as a function of the applied temperature. The experimental results show that the higher the temperature of the extraction reaction, the lower the percentage of extractables remaining in the gasket. Thus, immersing the gasket in ethanol for 15 h at 25° C., causes 20% of the extractables to be eliminated, i.e. a percentage of extractables remaining of 80%, while the percentages of extractables remaining at 45° C. and at 75° C. reach 25% and 10% respectively.

Diagram 3 shows the percentage of extractables remaining on an ethylene propylene diene monomer (EPDM) gasket as a function of the duration of extraction.

Diagram 3 shows the influence of the duration of extraction on the level of extractables remaining in an EPDM gasket. In identical manner to diagram 1, this diagram shows a drop in the percentage of extractables remaining, with increasing duration of immersion in ethanol of the EPDM gasket. Thus, immersion at 60° C. for 8 h results in the percentage of pollutants eliminated rising to 75%, i.e. only 25% of pollutants remaining in the gasket, the percentage of extractables remaining falling to 20% and to 10% after 15 h and 25 h respectively.

It should be noted that the duration and the temperature of extraction can be established by taking account of various criteria, in particular the final level of extractables remaining in the gasket, and the type of elastomer material to be treated. Thus, some materials, such as nitrile rubber, are more sensitive to extraction in ethanol, and conditions that are too severe (long duration, high temperature) are thus likely to affect the properties of the gasket, such as its mechanical properties.

The present invention is described above with reference to particular embodiments, but any useful modifications could be made by the person skilled in the art, without going beyond the ambit of the present invention, as defined by the accompanying claims.

Claims

1. A method of eliminating pollutants contained in an elastomer part, said method being characterized in that it comprises a step of extracting pollutants by immersing the part in a solvent, said solvent being ethanol.

2. A method according to claim 1, in which said extraction step is performed in an extraction column in which the ethanol flows.

3. A method according to claim 1, in which said extraction step is performed at a temperature lying in the range 20° C. to 75° C., and preferably in the range 25° C. to 70° C.

4. A method according to claim 1, in which said extraction step is conducted over a duration lying in the range 1 h to 72 h, and preferably in the range 2 h to 48 h.

5. A method according to claim 1, in which said pollutants are pollutants of low molecular weight.

6. A method according to claim 1, in which said pollutants are pollutants of high molecular weight.

7. A method according to claim 1, in which said elastomer part is a pump gasket.

8. A method according to claim 1, in which the ethanol is renewed continuously during the pollutant extraction step.