ABSTRACT
Numerous formulations of rigid, non-yellowing polyurethane were examined for optical clarity, impact resistance, and deep dome forming, and weathering. The non-yellowing, water-white, transparent rigid polyurethanes never made an effective cladding material for polycarbonate windshield and canopies, the formulation effort generated several families of materials potentially useful for other applications. The harder, more cross-linked, polyurethane plastics had excellent long-term weathering stability. They just did not have the exceptional 370 Polymeric Thermosetting Compounds impact resistance of polycarbonate. The polyurethane would adhere strongly to the glass even if there was only a pinpoint area free of release agent. One of the unresolved problems that we had when making castings of our non-yellowing, water-white, transparent rigid polyurethanes was finding a 100% effective release agent for casting it against glass surfaces. For non-transparent applications, the hot melt adhesives could contain a filler which would reduce cost and improve thermal conductance of the adhesive, thereby speeding up the laminating process.
