| abstract |
Polyurethane / urea including hydrophilic moieties and alkoxysilane groups of formula (I) -X-CO-NR2-Y-Si- (Z) 3 in which X selects between O and NR2; each occurrence of R2 is independently selected from H, C1-C6 alkyl, substituted C1-C6 alkyl, cycloalkyl, aryl and benzyl; Y is selected from linear and branched C1-C8 alkylene; and Z is an organic group inert to isocyanate groups below 100 ° C. At least one group Z is an alkoxy group of 1 to 4 carbon atoms. The polyurethane / urea can be in an aqueous dispersion, which can be used to prepare coatings. The dispersion is prepared (i) by reacting an organic polyisocyanate with a high molecular weight polyol, optionally a low molecular weight isocyanate reactive compound, an isocyanate reactive compound containing hydrophilic groups, and / or an amine chain extender forming a prepolymer: (ii) reacting the prepolymer of (i) with a compound of formula (II) OCN-Y-Si- (Z) 3 in which Y and Z are as defined above; and (iii) dispersing the reaction product of (II) in an aqueous medium. |