NIR LEDs and NIR lasers as feasible alternatives to replace oven processes for treatment of thermal-responsive coatings

  • Christian SchmitzEmail author
  • Bernd Strehmel


Near-infrared (NIR) laser sources (800–1000 nm) can potentially reduce the processing time for curing by a fast heating and incorporation of NIR absorbers into the coating. The latter converts NIR laser light absorbed into thermal energy. This curing technique was successfully applied to one-component thermoset coatings based on blocked polyisocyanate/hydroxy-polyester and melamine formaldehyde/hydroxy-acrylate resins with heptamethine cyanines as near-infrared absorbing material. The laser curing was additionally compared with LED sources. In general, the curing time significantly decreases in comparison with traditional heat sources. Furthermore, the photopolymerization of acrylates or epoxides can be induced simultaneously by adding suitable initiators due to photochemical generation of radicals and cations. Curing of the thermoset resin system and the photopolymerization process created interpenetrating networks. Principally, the techniques reported based on photonic NIR sources may help to substitute oven techniques where thermal activation of curing reactions is typically induced by oven or heating with infrared radiators for coating applications.


Laser curing Near-infrared light Thermoset coating Light-emitting diode Thermal radiation Radiation curing 



The authors thank the county of North Rhine-Westphalia for funding the project REFUBELAS (Grant 005-1703-0006) and FEW Chemicals GmbH for the NIR sensitizers.

Supplementary material

11998_2019_197_MOESM1_ESM.pdf (99 kb)
Supplementary material 1 (PDF 98 kb)


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Copyright information

© American Coatings Association 2019

Authors and Affiliations

  1. 1.Department of Chemistry, Institute of Coatings and Surface ChemistryNiederrhein University of Applied SciencesKrefeldGermany

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