Preparation of open cell sponge rubber for printing application

Abstract

In this research, sponge rubbers having numerous open cells were prepared by salt leaching technique. The nitrile butadiene rubber (NBR) with 40% acrylonitrile was compounded with vulcanization ingredients, and fine powder of water-soluble salts: sodium chloride and sodium nitrate. The compounding process was performed by using a Brabender and two-roll mill filled with various types of anionic and nonionic surfactants, which were used in order to wash out the salts from the rubber composites. The following properties of all rubber compounded samples were determined; cure characteristic, removal weight of sodium salt, hardness of sponge rubber, ink adsorption and impression test. The hardness property depended on carbon black types and contents and particle size of salts and contents. NaNO₃ could also form the open cell but the pore interconnection was not enough. The optimal recipe sponge rubber composition for NaNO₃-based porosity formation is formula 5 (100 mesh NaNO₃). Whereas system of NaCl was blended with the surfactant, nonionic surfactant as formula 9 (NaCl mixed Emanon), was the most effective recipe to prepare the porous rubber, giving the best imprint quality and pressed character surface.