Soft Thermoplastic Polyurethanes

Soft plasticizer-free thermoplastic polyurethanes (TPUs) have been developed that exhibit durometers below 70A on the Shore scale of hardness.  As a thermoplastic, these materials do not require vulcanization steps and are recyclable. The TPUs have been characterized in terms of their chemical and abrasion resistance, tensile, set and tear characteristics. By employing hydrocarbon polyols along with suitable chain extenders, TPUs with specific gravity less than 1.0 that exhibit acceptable physical properties and low compression set characteristics have been prepared.  These soft TPUs also offer better resistance to polar solvents like acetone or methanol and are predominantly made from raw materials based on renewable resources. To compliment these, other soft TPUs have been developed that are resistant to hydrophobic media such as limonene and oil #3. These TPUs can also exhibit excellent compression set characteristics. It is envisioned that the combination of attributes could prove to be useful for applications where TPUs would not normally be considered, including some where cross-linked rubbers have been predominantly used in the past.