| abstract |
A polyurethane resin consists of a reaction product of a phosphated polyol, anpolyisocyanate and optionally a stabilising monomer having a salt-forming group,nfor example, 2,2- dimethyolol propionic acid. The phosphated polyol may be anhydroxyl-terminated, phosphated polyester polyol which is a reaction product ofna carboxylic acid, a polyol and a phosphate monomer. The phosphate monomernmay be 2-phosphonobutane-1,2,4-tricarboxylic acid. The invention providesnaqueous dispersions of phosphated polyurethane resins which are particularlynsuitable as metal primers for metals such as galvanised steel. The metal primersnhave improved adhesion under agressive enviroments. |