In the processing of recycled polymers we have often encountered the problem of the formation of static electricity

The formation of this charge, during the recycling phases of the plastic polymers, can cause a bad functioning of the mixing between the raw material and the additives or dyes, or a danger for the workers approaching the mixers, hoppers, conveyor belts and dryers.

The movement of the polymer, in environmental conditions in which there is a low percentage of humidity, a sliding and contact of the granules with each other and along the walls of the machines that contain them, they can generate static electricity, of different intensity according to the path that the polymer has led and the environmental external conditions.

The presence of static charges can lead to an anomalous mixing of the components, in fact it can happen that separations occur between the polymer granules and the colored ones. due to the different electrostatic charge they absorb.

This induced separation could increase the presence of the granules, which absorb the same charge, towards the walls of the hoppers or feed pipes or discharge ports. The phenomenon is accentuated when we have a properly dried granule or the presence of humidity in the air, in fact, with greater humidity, the water, which is polar, dissipates the charge.

You can see a classic example in our view at home, when you generate static electricity by walking on a carpet in the presence of low air humidity. Humidifiers add water to the air and minimize the build-up of static electricity.

The solution of the problem sees two concomitant factors:

• Make sure that the machines that transport, process and dry the polymer have a correct dispersion system for the electrical charges.

• Regarding the polymer in production it is advisable to use an additive antistatic, which has the function of interrupting the accumulation of electrostaticity between the different granules, allowing transport and mixing without problems.

There are numerous additives on the market that solve the problem easily, economically and efficiently, without affecting the properties of the polymers.

For example the Polyethylene glycol 400 to be mixed in very small quantities (0.010%), has an economic cost and a satisfactory yield.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.