Developing a new class of high performance, low temperature activation polyurethane hot melt adhesives, we stumbled across a unique property of these materials – the ability to be processed into a water-solvent hybrid dispersion. These new hybrid dispersions show properties typical of solvent based PU adhesive formulations, such as excellent wetting of substrates, inherent shear stability and fast drying. Simultaneously, they possess the desired properties typically associated with water based PU adhesives, including the possibility to formulate to high solid content and to achieve a wide range of application viscosities independent of the molecular weight of the PU polymer. All this while reducing the effective solvent content down to a quarter of a typical solvent based PU formulation. In our talk, we will demonstrate how to formulate such hybrid adhesive dispersions and illustrate, how they can be used to address problems that both solvent based and water based adhesive formulations still struggle to solve. We will further discuss how this new technology can provide a pathway to reduce the need for traditional solvent based formulations in the area of 1C and 2C solvent based heat activation adhesive applications, where a robust material handling, long open times and a high initial bond strength are essential.
Co-authors: Dr. Fabian Schuster, Dr. Anne Fischer, Dr. Jörg Tillack