Polyurethane prepared from diamine and prepolymer

A polyurethane prepared by reacting at least one substituted aromatic diamine with an isocyanate terminated prepolymer prepared by reacting a polyisocyanate having an isocyanato functionality of 2 to 3, with a polyol comprised of about 80 to about 100 weight percent polymeric polyols selected from polyester polyols, polyether polyols and hydroxyl terminated unsaturated polymeric polyols and correspondingly, about 20 to about 0 weight percent monomeric hydrocarbon diols having 3 to 8 carbon atoms, where the ratio of isocyanato groups to hydroxyl groups of the polyol, or polyol mixture, is in the range of about 1.3/1 to about 5/1, and where the ratio of amino groups of said diamine to excess isocyanato groups of said hydroxyl groups is in the range of about 0.5/1 to about 1.1/1;

• characterized in that said substituted aromatic diamine is selected from at least one of the groups consisting of
• (I) cyclohexyl-3,5-diamino-4-tert-butylbenzoate and/or phenyl-3,5-diamino-4-tert-butylbenzoate;
• (II) a 3,5-diamino-4-tert.-alkylbenzonitrile of the formula ##STR6## wherein R.sub.1 is selected from butyl, tertiary amyl and tertiary hexyl radicals;
• and
• (III) an alkylene bis(3-amino-4-tert.-alkylbenzoate) of the following formula:
• ##STR7## wherein R.sub.1 is selected from tertiary butyl, tertiary amyl and tertiary hexyl radicals and R.sub.3 is selected from straight chain saturated alkylene radicals containing 2-10 carbon atoms.