Polyurethane Adhesives and Sealants Based on Hydrophobic Polyols

Thermosetting polyurethane polymers are staples of adhesive and sealant formulations used in a variety of industrial applications. Polyurethane materials generally provide reliable service under most application conditions, but the long-term performance and durability of some polyurethanes can be compromised by direct and prolonged contact with bulk water or high ambient humidity. The Dow Chemical Company has recently developed a class of hydrophobic polyols designed to impart hydrophobicity to polyurethane formulations while retaining the traditional performance and processing benefits associated with polyether polyols, including low viscosity, tunable molecular weight, and fidelity of polyol functionality. This paper describes the rational design of adhesive and sealant materials using the VORAPELTM family of hydrophobic polyols. An experimental design was employed to explore the correlation between polyol functionality and equivalent weight and the associated thermal and mechanical properties of cured polyurethane materials. The hydrophobic nature of polymers prepared using VORAPELTM polyols was demonstrated through a series of wet aging studies which provided evidence of improved resistance to water uptake and plasticization compared with polymers prepared using nonhydrophobic polyols of comparable molecular weight and functionality. Furthermore, it has been demonstrated that the use of the VORAPELTM hydrophobic polyols in adhesive and sealant formulations does not adversely impact key performance properties when compared with analogous formulations prepared with non-hydrophobic polyols. The information provided in this paper is intended to serve as a design template to enable formulators and application development specialists to effectively incorporate VORAPELTM polyols into their own product designs.