Advances in Blocked Isocyanates and Curatives, and Their Use in Polyurethanes

摘要

Recent developments in blocked isocyanate prepolymers and curatives arernpresented. The blocked isocyanate prepolymers are derived from urethane prepolymersrnthat contain low levels of residual monomer. These starting prepolymers are producedrnusing Crompton Corporation’s advanced “Low Free” manufacturing technology. Thernselection and optimization of the prepolymers and curatives are discussed. This includesrndata on novel blocked prepolymers produced from TDI, MDI, or PPDI and blockingrnagents. These new blocked prepolymers feature easy processing that allows thernformulator a broad choice of diamines for chain extension. The derived materials givernexcellent dynamic and mechanical properties. Field successes of these novelrnpolyurethane blocked systems are given to illustrate their high performance in therndemanding applications of binders, coatings and elastomers.rnCrompton Corporation also offers blocked curatives based on the coordinationrncomplex (MDA)_3~*NaCl (MDA = 4,4’-methylenedianiline). Standard products are sold asrndispersions in dioctyl phthalate (DOP). Due to growing health concerns surroundingrnDOP, Crompton Corporation has developed a DOP free product, Caytur 21-DIDP. DIDPrnis diisodecyl phthalate. The properties of Caytur 21 and Caytur 21-DIDP are discussed.