Epoxy and Phenolic Resins

Epoxy and phenolic resins are important classes of step-growth resins with a multitude of end uses. This chapter describes high solids, waterborne epoxies, and epoxy resins. Epoxy resins are prepared by reaction of epichlorohydrin (ECH) with novolac phenolic resins. When cross-linked with phenolic resins, these resins form films that are more flexible than films from homopolymer bisphenol A (BPA) epoxy resins and also provide excellent adhesion. Epoxy resins are used on a large scale to make water dispersible acrylic graft copolymers. The chapter also describes phenolic resins. Phenolic resins are divided into two broad classes: resole phenolics, which are made using alkaline catalysts and high ratios of formaldehyde to phenol, and novolac phenolics, which are made using acid catalysts and low ratios of formaldehyde to phenol. The phenolic resins used in coatings are soluble molecules or oligomers. They are usually made from phenols that have one of the reactive sites blocked, reducing functionality to two.