Fabrication Of Superhydrophobic Leather Coating

Leather has attracted consumer’s attention due to its excellent air permeability, heat preservation, and other functions. Unfortunately, leather has a bad hydrophobic property that would lead to leather products easily be destroyed by water. Therefore, to obtain superhydrophobic leather coating is of great significance. This study on fabrication of superhydrophobic leather coating is based on our previous team work of highly hydrophobic leather finishing agent.The superhydrophobic leather coating was fabricated by layer-by-layer. The conditions of fabricating superhydrophobic leather coating were optimized with the water contact angle of the treated leather as measurable indicator. The optimal process fabricating superhydrophobic leather coating was that spraying polyacrylate emulsion as undercoat, 4 layers of commercially available hydrophobic silica with the concentration of 2.0% were followed. And this method was also universal on other cellulose-based substrates. However, the durable abrasion of the superhydrophobic leather coating was bad. After 25 times abrasion, the water contact angle of the treated leather was decreased by 27°.In order to improve the durable abrasion of fabricating superhydrophobic leather coating by layer-by-layer, commercially available hydrophobic silica was modified with amino groups, the functional monomers which could react with amino groups were introduced to the emulsion polymerization simultaneously. The conditions of fabricating superhydrophobic leather coating were optimized with the water contact angle of the treated leather before and after abrasion test and the performance of the emulsion as measurable indicators. The optimal process fabricating durable superhydrophobic leather coating was that the reaction pH, temperature, time were 9, 110 ℃, 10 min, respectively. Contrast to layer- by- layer, the durable abrasion of fabricating superhydrophobic leather coating was increased. After 25 times abrasion, the water contact angle of the treated leather was decreased by 11°.To further improve the durable abrasion of superhydrophobic leather coating, the wear-resistant polyurethane and homemade hydrophobic silica were introduced by physical blending. The conditions of fabricating superhydrophobic leather coating were optimized with the water contact angle of the treated leather before and after abrasion test as measurable indicators. The mass ratio of polyurethane and commercially available hydrophobic silica was 1:2 to 1:1, the size of homemade hydrophobic silica particle was 140 nm, the mass ratio of homemade hydrophobic silica particle and commercially available hydrophobic silica was 1:6, the treatment temperature was 110 ℃, the superhydrophobic leather coating exhibited excellent durable abrasion. After 25 times abrasion, the water contact angle of the treated leather was retained.