WATERBORNE RESIN DEVELOPMENT FOR FLEXIBLE ADHERENT PRIMER

THE URETHANE, EPOXY, AND POLYSULFIDE PRIMERS PRESENTLY UTILIZED ON MILITARY AIRCRAFT ARE EFFICIENT FORMULATIONS BUT ARE SOLVENT-BORNE. IT IS INCREASINGLY IMPORTANT TO CONVERT TO WATERBORNE SYSTEMS TO MINIMIZE AIR POLLUTION IN THE VICINITY OF BASES APPLYING THESE COATINGS. THE PURPOSE OF THIS PROPOSAL IS TO DEVELOP A WATERBORNE URETHANE OR POLYSULFIDE THAT WILL MEET THE SPECIFICATIONS OF MIL-P-85853, I.E. METAL ADHESION, FLEXIBILITY AT LOW TEMPERATURE, SOLVENT RESISTANCE, WATER RESISTANCE, CHROMATE PIGMENT-COMPATIBILITY, AND FAST DRYING. WATERBORNE URETHANES ARE PRESENTLY DISPERSION STABILIZED BY A SMALL AMOUNT OF AMINE-NEUTRALIZED FREE CARBOXYL, USUALLY AT ABOUT 1 MOL CARBOXYL/2999 GMS POLYMER. THIS CARBOXYL ALSO ENABLES ADHESION TO METAL. THERE ARE A NUMBER OF COMMERCIALLY AVAILABLE PROPRIETARY COMPOSITION URETHANE DISPERSIONS SUITABLE FOR THIS APPLICATION. WE ARE ALSO PROPOSING TO SYNTHESIZE A NUMBER OF WATERBORNE URETHANES WITH KNOWN COMPOSITION SO THAT ADHESION, SOLVENT RESISTANCE, BLISTERING RESISTANCE, ETC., CAN BE CORRELATED WITH COMPOSITION. SINCE POLYSULFIDES ENABLE BETTER METAL ADHESION AND LOW WATER PERMEABILITY, WE ARE ALSO PROPOSING TO EVALUATE POLYSULFIDE-URETHANE AND ACRYLATE-CURED POLYSULFIDE EMULSIONS. MONSANTO HAS A NEW "URETHANE SUBSTITUTE" SYSTEM. WE ARE PROPOSING AN INITIAL EFFORT WITH THIS SYSTEM AS WELL.