N-Methyl-2-Pyrrolidone (NMP) is the most common co-solvent used in the manufacture of waterborne polyurethane dispersions. The unique properties of NMP aid in both the processing of the polyurethane dispersions as well as the film formation of the applied polyurethane coating. In addition, the NMP can help with substrate wetting, freeze/thaw stability, and adhesion to some substrates.
In some applications due to substrate sensitivity to NMP or regulatory constraints, customers may prefer waterborne polyurethanes without this common co-solvent. In response, Bond Polymers International has developed NMP Free waterborne polyurethanes which still contain a co-solvent necessary for proper film formation but utilize an alternate solvent in place of the NMP. The alternate co-solvent also aids in film formation similar to the NMP and has the advantage of being a faster evaporator than NMP resulting in generally faster dry times. These products are uncompounded waterborne polyurethane resins which may be suitable for some applications as supplied. However, they may require the addition of additives such as wetting agents, defoamers, thickeners, and or other additives to optimize them for your specific application.