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Tuesday, 24 September 2019

Isocyante-free 2K coatings systems:decoupling of pot-life and cure speed

Thursday, 19 March 2015 | Posted by: Sonja Schulte, European Coatings Journal

We all know the advantages and disatvantages of  isocyante based coatings systems. Exposure to free isocyante can result in adverse health effects such as respiratory diseases and severe allergic sensitization. Further isocyantes undergo irreversible side reactions with water which can be problematic for the application of isocyated based coatings such as PUR coatings in humid environments. There is also a need in many application for faster drying and hardness development that can achieved with current isocyante chemistry. However, typical approaches to faster dry times using isocyante chemistry usually lead to shorter formulation pot-life. Now two different isocyante-free approaches will be presented at the European Coatings CONGRESS. Both offer decoupling of pot life and curing speed while offering performance comparable to established systems. In my opinion, this is a real breakthrough in coatings technology!

The European Coatings CONGRESS (20.-21. April 2015, 10:00h), Europe´s leading coatings technology conference taking place during the European Coating SHOW (21.-23. April 2015) offers current trends and development from industry and academia. So it´s not surprising that at this congress two paper will be presented dealing with isocyanate-free urethane coating systems.

Isocyante-free PUR coatings
In Session 17: "2K industrial coatings”, April 21 2015 John Agrypopoulus and co-workers from The Dow Chemical Company USA present a paper entitled "Isocyanate free polyurethane coatings – fundamental chemistry and performance attributes” They conclude: "A new ambient cure, two component isocyante free polyurethane coating technology has been developed. The fundamental chemistry involving the addition of carbamate to an aldehyde moiety to produce urethane structures has been elucidated using 13C-NMR characterization. One significant benefit of this technology is the ability to decouple pot life from cure speed resulting in coatings with faster return to service and higher throughput at room temperature. The coatings have superior properties and excellent weatherability under accelerated testing”

New curing technology based on Michael Addition
Directly after this paper R.Brinkhuis and co-workers from Nuplex Resins, Netherlands, USA present a paper named "New, ultra-fast drying, low VOC, isocyante free technology for 2K coating systems” They expanded "the options of Michael Addition chemistry by focusing on ways to control the inherent reactivity of a malonate-aryloyl system by using its high reactivity potential, whilst creating both a long pot-life and a workable open time. Combined with specially developed resins, the obtained benefits are so profound that it may be recognized as a new type of curing technology, finding use in many different markets and applications.”

Key features and benefits of this new system include:

  • Very fast drying, with fast crosslink density development, and a very long pot-life
  • Application at ambient temperature, or even below
  • Very low solvent content (VOC < 250 g/L)
  • Excellent appearance
  • Thick layer application (> 150 µm) possible
  • Very good chemical resistance
  • Very good mar resistance
  • Excellent flexibility
  • Good outdoor durability
  • Isocyante, formaldehyde and organotin-free cure chemistry

I am really looking forward to these presentations and the reaction of the audience.

See you in Nuremberg!

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Author

Sonja Schulte
European Coatings Journal
Sonja Schulte
Editor-in-Chief, Science & Technology
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