Лако-красочные материалы — производство

As the name indicates, saturated polyesters are polymers with ester linkages in their backbone. They are the condensation products of polyols and polybasic acids. The early development of saturated polyesters traces back to preparation of glyptal resins, formed from glycerol and phthalic anhydride, which are also the foundation for development of alkyd resins, as mentioned earlier. Though in a strictly chemical sense, the term polyester can also be applied to alkyd resins, the essential difference is the presence of oil or fatty

acid in an alkyd resin, while saturated polyesters are free of such compounds. Therefore, saturated polyesters are sometimes also termed oil-free alkyds. Due to the absence of unsaturated oil or fatty acids, saturated polyesters cannot air-dry via oxidative poly­merization as do alkyds, so they need to be formulated in coatings with curing agents or cross-linkers. Based on the curative, they can be cured at ambient conditions or require baking. In general, com­pared to alkyds, the cured films of polyesters are superior in most performance properties such as color and gloss retention, water and chemical resistance, and overall durability.