Raising The Bar - Formulators of latex architectural paints and coatings have made tremendous progress in recent years and raised the bar with new product introductions. These new paint formulations not only perform better but are also demonstrating significant improvements with regard to environmental and human health attributes. Add to this a dedicated effort by many to improve the overall sustainability of their formulations while controlling costs, and one can see that the job of a formulator today is more challenging than ever.

Fortunately, paint chemists don't have to work alone. Additive suppliers like Ashland Aqualon Functional Ingredients, a commercial unit of Ashland are dedicated to collaborating with top chemists and paint producers to develop and commercialize an ongoing stream of new and advanced rheology modifiers and other additives that help formulators achieve their goals.
Better color reproduction, improved flow and leveling, sag resistance and anti-spatter are a few of the top goals most often mentioned by formulators of premium deco paints in 2011. However, on the surface, many of these properties seem to contradict each other - better leveling with improved sag is a good example. The Aquaflow line of nonionic synthetic associative thickeners (NSATs) has been delivering a steady stream of new advancements for years. This line now includes three grades of Aquaflow XLS, a second-generation KU builder (low shear effective) that has been engineered with unique structure recovery behavior and optimized for multiple resin systems to deliver superior leveling combined with exceptional sag resistance, not previously demonstrated from NSAT chemistry. This means paints formulated with Aquaflow NSATs can routinely achieve Leneta leveling values of 9-10, delivering a beautiful, drip-free finished surface that won't show brush marks.

Near-Zero VOC Paints

In addition to Aquaflow XLS, Ashland Aqualon Functional Ingredients has also developed and launched new high-shear effective NSATs (ICI builders), including NHS-350 and NMS-450 grades that are highly efficient. These not only offer cost savings potential, but because less can be used, increased free water is available to formulators. All of these new Aquaflow products, and others introduced over the past five years, are free of aklylphenol ethoxylates (APEOs), solvent-free and employ new carrier technology that lowers as-sold viscosity for easier incorporation and improved plant handling. These attributes are necessary for the newest near-zero volatile organic compound (VOC) "green" paints that have rapidly been gaining share in virtually all markets.

"The architectural coatings manufacturers in North America and Europe have been aggressively driving toward lower total VOC content for nearly a decade," said Dale MacDonald, vice president, Coatings Additives, for Ashland Aqualon Functional Ingredients.

Determining VOC Content

However the definition of VOCs in coatings differs significantly in the U.S. when compared to Europe. Europe has taken the position that any chemical or substance with a boiling point above 250°C degrees will not be counted as a VOC in paint. There are many organic solvents with boiling points just above 250°C that are effectively exempted in Europe, but at the same time may contribute to VOC in the U.S.
For many years, the U.S. has relied upon the Environmental Protection Agency (EPA) Method 24 to determine VOC content of paints. Many believe this method is inaccurate for today's low VOC formulations. There is a clear movement to replace the outdated Method 24 with a new gas chromatography-mass spectrometry method.

"Adoption of this more precise method would leapfrog the U.S. past Europe in terms of restricting more materials and raising the bar regarding what chemists and formulators must achieve to deliver low- or true zero-VOC coatings," added MacDonald.
There is also speculation that Europe and the world will soon migrate to a similar and/or common standard because major raw materials from multinational suppliers are selling to world markets.

Rheology Modifiers for Waterborne Decorative Coatings

Ashland is not only making advances in synthetic thickeners. Natrosol hydroxyethylcellulose (HEC) and Natrosol Plus modified HEC are the world's most widely used rheology modifiers for waterborne decorative coatings. Natrosol HEC is a brand valued and respected throughout the world because of cost-effective performance, superior consistency and unsurpassed colorant compatibility. It is also one of the best rheology modifiers for creamy, in-can appearance and stability (anti-syneresis).

In 2010, Ashland introduced its newest addition to this product family with Natrosol HE 3KB, a highly efficient version which combines the most desired attributes of spatter-resistance and bio-stability in a product that often demonstrates superior brush leveling and thus, applied hiding. In addition to customer-valued performance, HEC remains one of the most cost-effective thickener technologies and also excels on the sustainability front. The cellulose ether chemistry is derived from natural, renewable wood and cotton feedstocks. In addition, HEC is typically sold as a dispersible dry powder, which means no APEO content, no added solvents or carriers and the lowest carbon-footprint impact from transportation.
It is also noteworthy that specific grades of Natrosol HEC are commonly used upstream in the paint supply chain, as a protective colloid in the emulsion polymerization of latex polymers, which are subsequently employed as primary film formers in latex paint.

Moving Away From APEO

The movement away from APEO-containing materials began in Europe, where alkylphenol chemistry was initially identified as potentially harmful to human reproductive health, particularly when they enter the water supply. This concern has spread rapidly throughout the world. Though some legacy APEO-based materials remain in use, most paint producers will not qualify any new materials unless they are APEO-free.

Ashland's line of specialty surfactants, offered under the Dextrol and Strodex trade names, offers new grades that are both APEO-free and solvent-free, thus contributing essentially zero-VOC to paint formulations, while providing multiple benefits. These new, high-performance surfactants offer environmentally preferred alternatives to legacy, APEO-containing nonionic surfactants and wetting agents and serve to improve color, gloss and overall formulation stability. Specific types can also enhance freeze-thaw resistance and stabilize reactive pigments such as ZnO.

Ashland's Manufacturing Site in China

At the end of 2010, Ashland celebrated the grand-opening and start-up of its newest and most advanced manufacturing site in China. This world-class facility, located in the Nanjing Chemical Industry Park, and dedicated to producing Natrosol HEC products, is Ashland's fourth HEC production facility, joining those in North America and the Netherlands. In addition to high-volume local production of HEC, this investment includes an applications laboratory and state-of-the-art training facilities for our sales organization, distributors and customers. Natrosol HEC is a cellulosic polymer used as an additive in a wide variety of industrial and consumer products including latex paints, paper coatings and personal care items such as shampoos and shower gels.