In this article we review the pros and cons of eliminating cosolvents or switching to other organic solvents. Synthetic routes to minimize NMP usage are cited from the literature. Commercially available NMP-free and cosolvent-free aqueous Witcobond® PUD grades are discussed. Examples of a wide range of solid content and average-particle-size PUDs are given. The physical properties of these grades can be hard and mar resistant, strong and tough or soft and pliable. The applications of these solvent-free PUDs in textiles, coatings and adhesives are briefly reviewed. Examples of starting formulations are also given.
The other option is to make the PUDs without any cosolvent. This option is the most preferred but is also the most challenging.