Лако-красочные материалы — производство

As discussed earlier, many polyurethane resin systems offered for coatings contain free — NCO groups, which are expected to react with appropriate cross-linkers during the curing reaction after application. Since isocyanates are reactive to water, until the 1990s, it was thought
difficult to offer waterborne polyurethane resin systems. While iso­cyanate can react with water at ambient temperature, the rate of this reaction is much lower compared to that with polyols or polyamines. For instance, aromatic isocyanates react with water about 1000 times slower than with primary amines, and about 10 times slower than with primary alcohols. This differential reactivity of isocyanates with diffe­rent active H-compounds is an important consideration in the success and commercialization of waterborne polyurethane resins.