| abstract |
In accordance with an exemplary embodiment of the present invention, an optically clear polyurethane/polyurea polymer may be prepared by reacting a cycloaliphatic diisocyanate with polyesters, polyethers, and polycarbonates which may comprise hydroxyl groups and/or primary amine groups. This reaction may be carried out using 0.5 to 0.9 equivalents of the hydroxyl/amine groups followed by the reaction of 0.1 to 0.5 equivalents of water. The glycol, amine, and water may then be reacted with a cycloaliphatic diisocyanate in a ratio of about 1.77 to about 3.5 NCO for each OH, HOH, NH 2 . The resulting prepolymer may then be reacted with an aromatic diamine curing agent such as diethyltoluene diamine in an equivalent ratio of about 0.85 NH 2 /1.0 NCO to about 1.1 NH 2 /1.0 NCO, and in one embodiment, from about 0.90 NH 2 /1.0 NCO to 0.98 NH 2 /1.0 NCO. In one embodiment, 0.2 to 0.3 comprises the range of water equivalents for the water diisocyanate reaction. |