Waterproof Breathable Polymeric Coatings Based on Polyurethanes

The performance of environmentally friendly water-based polyurethane dispersions (PUD) for waterproof breathable coating was studied. The effect of the nature of PUD, number of coatings, incorporation of additives, and processing conditions on the breathable properties of cotton fabric was evaluated. The relative proportions of hydrophilic and hydrophobic components had a direct influence on the breathable properties of the coated cotton samples. The increase in hydrophilic component resulted in an increased water vapor penetration and lower water resistance to water penetration in the coated samples. For all the compositions, the durability of the coatings was found to improve with the incorporation of polymeric binder in the coating formulation. The air permeability values of the coated samples were found to be orders of magnitude lower than the control (uncoated) fabric sample.