Greener Reaction Conditions Award: Dow Chemical

Dow Chemical garnered the Greener Reaction Conditions Award for its Evoque precomposite polymer technology, which helps improve paint properties while using as much as 20% less titanium dioxide pigment. This win marks the ninth time that Dow has received a Presidential Green Chemistry Challenge Award during the program’s 18-year history—more than any other company.

TiO₂ is added to paints as the base white pigment. The material is opaque and serves to hide the background color of the painted surface. It also helps prevent discoloring tannin from leaching through the underlying wood and rust stains bleeding through from painted-over nails, screws, and metal surfaces. But TiO₂ is energy intensive to mine, process, and transport, typically making it the most costly ingredient that goes into a can of paint.

In a typical paint formulation, TiO₂ particles can crowd together and become unevenly distributed, which decreases the pigment’s light-scattering power and thus its hiding efficiency. Instead of simply adding more TiO₂ to compensate, Dow Coating Materials scientists took a different approach. They developed an acrylic-based copolymer coating that envelops TiO₂ particles to better separate them, improving particle dispersion and light-scattering efficiency on the painted surface.

Evoque gives paint formulators options for designing different products: choosing to use less TiO₂ to lower cost, using the same amount of TiO₂ and improving performance, or choosing a combination of the two. In addition, an independent life-cycle analysis commissioned by the company documented that the polymer-TiO₂ composite in exterior house paint reduces the paint’s carbon footprint by more than 22%, water consumption by 30%, and NO_x and SO_x emissions by 24%.

“Evoque was developed with the goal of driving gains in sustainability through more efficient raw material use coupled with increased paint performance,” says Keith Watson, global R&D director for Dow Coating Materials. “With the development and market acceptance of Evoque, we are driving innovation that is changing the way paint is made and how we expect paint to perform.”