NOVELTY - A wind turbine blade has polyurethane-based coating layer, as outermost layer on at least one portion of outer surface of blade. The coating layer includes a polyurethane binder formed from base component containing polyols, and curing agent component containing polyisocyanates. The polyols have average functionality of 2-8. The polyisocyanates have average functionality of less than 3. The polyisocyanates are chosen from polyisocyanates having functionality of 2-3 and polyisocyanates of allophanate type having molecular weight of 250-2000 g/mol.    USE - Wind turbine blade.    ADVANTAGE - The wind turbine blade has excellent flexibility, corrosion resistance and durability.    DETAILED DESCRIPTION - A wind turbine blade has polyurethane-based coating layer, as outermost layer on at least one portion of outer surface of blade. The coating layer includes a polyurethane binder formed from a base component containing polyols, and a curing agent component containing polyisocyanates. The polyols have an average functionality of 2-8. Polyols (50 weight% or 70 weight%) have aliphatic polyester segments and molecular weight of 300-3000 g/mol. The polyisocyanates have an average functionality of less than 3. The polyisocyanates (50 weight% or 70 weight%) are chosen from polyisocyanates having aliphatic polyester segments, molecular weight of 500-3000 g/mol and functionality of 2-3, polyisocyanates of allophanate type having a molecular weight of 250-2000 g/mol and functionality of 2-3 and polyisocyanates of the uretdion type having molecular weight of 250-2000 g/mol and functionality of 2-3. INDEPENDENT CLAIMS are included for the following:    (1) coating composition, which comprises base component containing polyols, curing agent component containing one or more polyisocyanates, and component chosen from filler, pigment, additives, accelerator and solvent; and    (2) method for coating substrate, which involves applying the coating composition on at least one portion of the surface of a substrate and curing the coating composition at 90 degrees C or less.