Bayer MaterialScience researchers explore factors influencing weathering performance of two-component polyurethane topcoats

2-component polyurethane coatings exceed industry standards for weatherability

19-Feb-2008

The power of polyurethane topcoats first debuted in the industrial maintenance and marine markets in the mid-1970s as part of a corrosion protection system. Polyurethane topcoats have evolved over the years into a versatile technology that can be formulated to create low VOC coatings and productivity enhancing coatings, as well as long-lasting, cost-effective coatings. However, recently there has been a call for ultra-high weathering performance topcoats for applications such as sports facilities, water tanks and bridges where coating systems are expected to provide aesthetic appeal along with corrosion protection.

In a quest to explore whether current weathering performance specifications for two-component polyurethane topcoats - such as SSPC Paint Specification No. 36 - go far enough in defining the highest level of polyurethane performance available for these demanding applications, Edward P. Squiller, director, Specialty Coatings and Kurt Best, senior scientist, both of Bayer MaterialScience (BMS) LLC, authored a paper: 2-Component Polyurethane Topcoats - Formulating Variables Affecting Weathering Performance. The authors discussed their paper at the recent 2008 Paint and Coatings Expo.

There are many potential variables in typical corrosion protection topcoat formulations that influence performance and application characteristics, as well as the cost structure of the coating. These variables include isocyanate index and resin selection, which play a major role in determining the weatherability of the final product.

In their paper, the authors compare some key formulating variables of aliphatic polyurethane topcoats and their resulting performance in an accelerated weathering study. Aliphatic polyisocyanates traditionally result in topcoats with much better outdoor weathering characteristics versus aromatic polyisocyanates, and are primarily used in outdoor topcoat applications in which gloss and color retention are required.

Through their research, the authors discovered that all of the polyurethane topcoats tested met the highest performance level specified by SSPC Paint Spec. #36 with regard to loss of gloss and yellowing, therefore concluding that the topcoats are capable of achieving a much higher performance standard. However, the authors caution against reading too much into just one accelerated test method relative to other important considerations.

https://www.chemeurope.com/en/news/78138/bayer-materialscience-researchers-explore-factors-influencing-weathering-performance-of-two-component-polyurethane-topcoats.html