The uniquely functional cosolvent N-methyl-pyrrolidone (NMP) iswell suited for use in waterborne polyurethane dispersions (PUDs). The use of cosolvents during polyurethane dispersion production is often necessary to enable a smooth reaction between the hydrophilic diol components [e.g., dimethylolpropionic acid (DMPA)] and the more hydrophobic polyurethane prepolymer. In addition, the cosolvent used during the PUD production phase remains in the system and later becomes a useful coalescing solvent when the PUD is applied as a coating to a substrate. The utility of NMP is diminished by the negative health effects of NMP exposure, and for many years the industry has sought an effective and safer substitute for NMP. Taminco, now a subsidiary of Eastman Chemical Company, has identified and developed the needed replacement, TamiSolve® NxG. It is a more effective cosolvent than NMP and it also exhibits an improved Health, Environment and Safety (HES) profile relative to NMP.
Waterborne PUDs are used as coatings, adhesives, sealants and elastomers. Waterborne PUD-based coatings display excellent adhesion to challenging substrates like plastic and metal. Dried/cured PUD coatings have excellent mechanical properties and environmental resistance, and waterborne PUD-based coatings are becoming the coatings of choice for demanding applications like floor coatings, as well as those used in industrial environments. Application of waterborne PUD coatings and adhesives can expose the applicator to volatile compounds that are emitted from the formulation. Therefore, the HES profile of the formulation’s ingredients is very important. In addition, the atmosphere is also exposed to the VOC content emitted from an applied PUD-based coating and/or adhesive. Obviously, the use of safer solvents, and in lower amounts, markedly improves the HES profile of a given PUD-based product.