Textile & Clothing

Electret fibres for high-performance filter media – chemical research

The collaborative project succeeded in converting commercially available filter materials into electret filters through application of a polyethylene hard paraffin wax with subsequent corona treatment. Thanks to their increased electrostatic attraction and the resulting protective and purification functions, these newly developed textile products provide a substantial contribution to environmental protection.



extile fabrics and non-wovens are the primary means utilised for removing the harmful dust and suspended substance particles from the exhaust air created by production processes. However, the currently employed microglass fibres are suspected to be carcinogenic and the alternatively employed electric filters consume high amounts of energy. Though the potential to overcome these problems is ascribed to flat filter elements, these are equally incapable of resolving the problems posed by mechanical retention of particles unable to pass through the pores. One solution here could be materials with special adsorptive properties. In this context, the electret effect appears particularly beneficial. This effect is based on the exploitation of dipole effects on the surface of ferroelectric materials or plastics which then behave as if permanently exhibiting an electric charge. This achieves an electrostatic attraction otherwise only displayed by electric filters.

The project's aim was to create fibres with electret properties in order to employ textile products for multivalent filter applications. To do so, commercially available filter materials were to be coated with a suitable substance (polyethylene hard paraffin or waxes) and converted into electret filters using conventional corona technology. In particular, relatively thin filter media were to achieve very high separation rates at low pressure loss.


  • The filters can be regenerated through blowback cleaning. The mechanical load did not result in a loss of the electret effect.
  • It was possible to realise quasi-permanence with three materials and to achieve improvements in the initial filtration phase in the critical transition between diffusion and inertial separation.
  • Examinations of the electret effect's ageing behaviour show that sufficient thermal stability can be achieved.
  • Ageing at increased humidity (80%) does not show any effect of humidity on charge stability.

More Project Informations

Project title:  Verbundprojekt: Integrierter Umweltschutz in der Textilindustrie - Plasmagestützte Herstellung von Elektretfasern für Hochleistungs-Filtermedien - Teilvorhaben 2: Chemische Untersuchungen zu elektretfähigen Faserbeschichtungen

Project number:  0339889

Project period:  2000 - 2004

Project region:  Germany (North Rhine-Westphalia)

Project contact:

Herr Notz

+49 (0)2152 / 38-1812

+49 (0)2152 / 38-1503

View Publication

Source: German National Library of Science and Technology Hannover (TIB)