WATER BASED, SOLVENT FREE, TWO COMPONENT ALIPHATIC POLYURETHANE COATING

摘要

A water based, solvent free, two component polyurethane-polyurea dispersion containing up to 65% solids. The first component is a polyester-polyol phase and an aqueous amine phase mixture. The polyester-polyol is a combination of modified polyester-polyols, low viscosity polyether or polyester-polyols, chain extending low molecular weight polyols, neutralizing amines and a detergent. It has a solids content of 90-100% and is totally hydroxyl functional with a carboxylic acid number of 10 and 50, a hydroxyl number of 180 and 300, an equivalent weight range of 165 and 365 and a viscosity of 600-1500 cps at 25 °C. The amine phase is a combination of neutralizing and chain extending amines having ratios preformulated to provide a balanced chain extending cross-linking reaction in aqueous phase with -NCO reactive groups. The aqueous amine blend has an equivalent weight of 40 to 50 and a solids content of 40-60%. The polyester-polyol and amine phases are combined in water at room temperature to form an aqueous component having a solids content of 33 to 48% and has an equivalent ratio between polyester-polyol phase and amine phase of 1.75:1 to 2.25:2. The second component is a 100% solids aliphatic isocyanate having a viscosity of between 1000-3500 cps at 25 °C and provides an NCO to functional groups in the polyester-polyol/amine component ratio of between about 1:1.3 to 1:1.7. This solvent free dispersion dries to a film coating having properties equal to conventional solvent based polyurethane coatings.