Polymerization-dimer acids

Dimer acids are the commercial products resulting from clay-catalyzed, high temperature polymerization of unsaturated fatty acids, usually tall oil fatty acids. The products have been commercially available since the 1950s and now, in all forms, represent 40–50 million pounds per year sales in the United States. The products are high boiling, mobile to viscous liquids. Their most important chemical property is carboxyl multifunctionality, which allows conversion to high polymers, mostly polyamides in commercial practice. Dimer-based polyamides have sizeable application as hot-melt adhesives and as reactive components of epoxy resins. There are much smaller uses in other polymer systems. Dimer acids are relatively nontoxic, and are not flammable. In February 1979, single-distilled dimer acids sold in tankcar quantities in the range $0.45–0.55/lb. There were six producers in the business, with one almost entirely a captive consumer.