High-Solids Alkyds Resins with Improved Properties Based on Styrene Allyl Alcohol (SAA) Resinous Polyols

By Daniel B. Pourreau, Scott E. Smyth

Stringent VOC content rules on Architectural and Industrial Maintenance (AIM) coatings have recently been enacted by federal, regional, and state regulatory agencies. These new rules effectively ban the use of low-solids solventborne alkyd resins, despite their excellent properties, ease of use, and low cost. In response to these new regulations, alkyd producers have been developing higher solids and waterborne alkyds, but these new resins do not perform as well and are more costly than the higher VOC versions. High-solids alkyd resins typically have lower molecular weights, which can increase their drying times and reduce their durability.

Waterborne alkyds are usually more expensive, despite having lower solids contents. Their dry time is also affected by temperature and humidity and their storage stability is usually lower than solution alkyds. These properties make waterborne alkyds less attractive to contractors who require paints with fast dry times and high coverage and hiding power for maximum productivity. This paper describes the use of commercial resinous polyols to produce alkyd resins with lower solvent demand, plus improved dry times, humidity and UV resistance compared to conventional medium- and long-oil alkyds.

Partial replacement of pentaerythritol with styrene allyl alcohol (SAA) resinous polyols in standard alkyd resin syntheses results in a marked decrease in the resin polydispersities but little change in the number average molecular weights. The SAA polyol can be added to the process as a solid or a liquid, oil-modified polyol. The alkyd resin with the best overall properties was obtained by replacing a portion of the pentaerythritol, soybean oil, and phthalic anhydride with an SAA-modified soy polyol.