Unique low-monomer urethane prepolymers have been developed for use in adhesives and sealants. This technology creates prepolymers with less than 0.1% free methylene diphenyl diisocyanate (MDI) and other isocyanates, providing unsurpassed industrial hygiene standards, excellent performance, and improved processing.
Low-monomer urethane prepolymers minimise exposure to free isocyanate, a subject of increasing regulatory focus. Benefits of low-monomer urethanes include improved industrial hygiene, enabling adhesive and sealant formulations to meet increasingly strict levels of free monomer, minimising EH&S workload related to isocyanates, and eliminating any toxic classification (H351-free).
Synthesising low-monomer urethanes enhances phase segregation between hard and soft segment domains, leading to controlled morphology. Low-monomer urethane technology enables design of prepolymers for specific applications with a tailored balance between viscosity and NCO content for desired property and processing advantages. Recent case studies for adhesives and sealants will be discussed. Low-monomer urethane prepolymers are available across isocyanate chemistries, including MDI, isophorone diisocyante (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyante (TDI), and 1,4 phenylene diisocyanate (pPDI), and with a range of polyols, including polyethers, polyesters, polycaprolactones, and polycarbonates.