Résumé : |
Nitrocellulose, Cellulose Acetate Butyrate, Acrylic, and Polyurethane lacquers and water-dilutable lacquer-emulsion topcoats have been employed by the leather industry as topcoating materials for many years. They impart excellent handling, drying and aesthetic properties to the finish and have been perfected over the years to provide relatively trouble-free application. Due to changing Federal regulations and local legislation which require that the finisher use coatings with lower solvent emissions, the conversion to increasing amounts of water-based topcoat systems in the leather industry is underway.
The scope of this presentation is designed to provide the finisher with a better understanding of the key formulation and application parameters which must be considered to facilitate a smooth transition from solvent to water-based topcoat systems. Key application and handling properties of "water" topcoat systems such as coating rheology, formulation viscosity, surface tension, drying, effects of cosolvent/coalescent,water evaporation/humidity effects,recoatability and equipment requirements for spray and roller-coating applications must be carefully controlled to produce the desired application, finish appearance, and physical properties. |