Hydrophobic treatment of woven cotton fabrics with polyurethane modified aminosilicone emulsions

Woven cotton fabrics were treated with a polyurethane modified aminosilicone fluid commonly used as a fabric softener. The aminoethylaminopropyl polydimethylsiloxane was modified with an aqueous dispersion of polycarbonate diol polyurethane using isopropyl alcohol as co-solvent resulting in stable micro-emulsions with an average droplet size of 1.5 μm. Polycarbonate polyurethane was chosen due to its good hydrolytic stability and low water absorption levels. Fabrics were treated either by immersion in emulsions or by spray coating. Treated fabrics had static water contact angles exceeding 143o with droplet shedding angles of less than 50o depending on the droplet volume. Treated textiles were breathable with vapor permeability levels of 5.6 mg (m day Pa)−1 that was similar to untreated fabrics. Good droplet shedding action was achieved based on the inherent fiber roughness. Accelerated ageing tests corresponding to 5 years using CIEL*a*b standards (7.5 × 106 lx∙hours exposure) indicated that no ageing occurred, with the overall color parameter of ΔE < 2.0 indicating invisible color changes to the naked eye. This sustainable approach can be easily scaled and may be a valuable treatment alternative for delicate fabrics commonly encountered in Heritage preservation; but also for many other cotton-based textiles.