Monomer and VOC-free unsaturated polyester resin in modern impregnation machines

Jaco de Beer, Tectra Automation


Published in:

Electricity+Control, January 2016 (pages 16 – 18)

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Varnish has been extensively used in the electrical industry as insulation, coating, bonding and impregnation material. During the manufacturing of rotational machines coils will be impregnated with varnish to improve life expectancy. These manufacturing processes however release amounts of monomer and VOCs in the form of emissions. Early varnish can now be replaced with monomer and VOC-free polyester resin.

Polyester resin is a versatile thermoplastic that forms part of the polymer family. Since development and manufacture of polyester resin it has successfully been used in the production of various items ranging from electrical motors to yachts. Polyester resin will cure to an infusible solid after being exposed to the correct conditions, these conditions could include the application of heat, catalyst or photo initiators. During the curing of polyester resin volatile organic compounds or VOCs will be released into the atmosphere if present in the resin composition. Monomers will also be released into the atmosphere in the form of emissions. T

hese monomers when released to atmosphere gives curing resin its distinct smell. If in high enough concentration these VOCs and monomer emissions are both dangerous to employees in the working area and the environment [1]. Removing VOCs and monomer emissions from the working environment and atmosphere is both a costly and energy intense practice. The research project will compare and analyse traditional polyester resin with monomer and VOC-free unsaturated polyester resin in order to determine if a newer version of polyester resin can achieve greater environmental benefits while not sacrificing cycle time, durability and mechanical properties of the cured resin.


Take note

  • Varnishes are commonly used electrical insulators.
  • Traditionally, varnishes emitted monomer and volatile organic compounds during curing.
  • Modern varnishes exist which do not have these characteristics, and research is underway to prove their suitability and replacement.