| abstract |
A polyurethane resin consists of a reaction product of a phosphated polyol, a polyisocyanate and optionally a stabilizing monomer having a salt-forming group, for example, 2,2-dimethyolol propionic acid. The phosphated polyol may be a hydroxyl-terminated, phosphated polyester polyol which is a reaction product of a carboxylic acid, a polyol and a phosphate monomer. The phosphate monomer may be 2-phosphonobutane-1,2,4-tricarboxylic acid. The invention provides aqueous dispersions of phosphated polyurethane resins which are particularly suitable as metal primers for metals such as galvanised steel. The metal primers have improved adhesion under agressive enviroments. |