Crylcoat 2637-4 Carboxylated polyester resin Cytec Surface Specialties North America South and Central America Polyester Coatings Crylcoat™ 2637-4 is a carboxylated polyester resin designed to produce clear-coats with Primid hardeners. Coatings based on Crylcoat™ 2637-4 are characterised by very good flow, transparency and yellowing resistance. Carboxylated polyester resin. Exhibits very good flow, transparency and yellowing resistance. Used to clear-coats with Primid hardeners.