Taking charge

Graham Lewis, Corporate Key Accounts Manager – Colorex, from Forbo Flooring Systems takes a closer look at the basic construction types of vinyl electrostatically discharged (ESD) flooring.

As laboratory and office equipment becomes more technically advanced, the potential for electrostatic discharges increases. ESD is the transfer of an electrostatic charge between two objects of different polarity – the most common is between an individual and the floor, and this is known as a triboelectric charge. In general environments, the majority of commercial flooring products are sufficient. Increasingly, however, stricter requirements are specified and specialist flooring is needed.

It is worthwhile understanding the make-up of ESD flooring itself, as the production process can have an impact on its overall performance. There are two basic construction types of vinyl ESD flooring: those with chemical additives and those with pressed conductive chips.

In the former, the tiles have generally been cut down from sheets that have a high plasticiser content as the initial manufacturing process takes into account a need to be flexible and ability to be rolled. However, this plasticiser also “outgases”, and so may prove a problem in relation to the issue of airborne molecular contamination.

During production, antistatic chemical additives called surfactants are added. However, these rely on a relative air humidity of 40% or above to gain their ESD performance, which in some cases isn’t conducive to the environment in which they are placed. These surfactants also migrate out, reducing the performance of the product.

Alternatively, products manufactured under pressed chip production offer a highly compressed tile with a compact surface. The special production process starts with vinyl sheets being cut into small chips, which are then coated with a conductive substance. By very high pressure and high temperature, these conductive coated chips are compressed into solid blocks of homogeneous material, which are subsequently sliced into single tiles. In the finished product, the conductive coating of the chips forms a dense network of tiny black veins. These are the “conductor paths” for the secure drainage of electrostatic charges through the whole thickness of the tiles.

This production process generates a material of superior quality with an extremely high and uniform compression and a pore-free, easy to clean surface meeting the highest hygiene requirements up to certified cleanroom suitability.