Fewer coats of paint

  • AkzoNobel provides performance coatings to many markets including transportation, construction and industrial markets.  Performance functions include anti-corrosion, anti-abrasion, antifouling and chemical resistance. The coatings are applied to many different substrates including steel, tinplate, concrete, aluminium, plastics and composites.
  • Usually, several layers of paint are applied to build up a coating “scheme”.  The layers may be of the same composition but very often different paints are applied in layers to achieve a certain performance on a certain substrate. Often, higher total scheme thickness results in better performance. The limiting factor is the film thickness that can be applied in one coat (typically 300 microns dry film thickness (DFT) for an anticorrosive type product, from 40 microns DFT for a high performance polyurethane topcoat)
  • In the case where the same paint is applied in several layers, there is a maximum limit to the film thickness that can be applied.  This could be because the wet film will sag at high thickness.  Sometimes the limit is because escape of solvent is not sufficient at high build.  Sometimes a thick film cures to induce an internal stress that is detrimental to the coating’s performance.  Sometimes several layers are required to ensure that there are no pinholes or other defects that could undermine the coating’s performance
  • In the case where several different paints are applied in layers, this is because the individual layers are performing different functions. In other words, a single type of paint cannot provide all of the functionality the market demands. Typically the first layer has the function of securing excellent adhesion to the substrate and also providing protection to the substrate.  A primer for steel is an example of this.  Subsequent layers provide a different function.  An example could be a topcoat that provides color and gloss but also excellent durability in harsh exterior environments
  • There is a further special case where the chosen topcoat cannot adequately adhere to the primer.  In this case, a third type of paint is introduced which has the main function of securing excellent adhesion between the primer and topcoat. This is often called a “tie-coat”
  • This need is driven by the opportunity to use less paint and fewer coats, either of which could improve the sustainability of our customers’ operations by reducing material use
  • We invite proposals for technology or processes that can achieve the above and approaches may include, but should not be limited to:
  • Alternative chemistries that can provide multiple functions, such as a primer for steel that also has excellent durability to sunlight
  • A coating that can segregate after application, providing 2 separate continuous layers
  • An application method that improves the adhesion of coatings to substrates
  • A technology that can be formulated into coatings to promote adhesion between coatings based on different chemistries,like for example enabling removal of tie-coats/intermediate coats within schemes

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