Use of surface modified colloidal silica as open time extender in white deco paints

 
Several researches carried out in CoRI have shown that by the use of nanoparticles such as colloidal silica, the mechanical and protective properties of water based systems are strongly improved. Moreover, nowadays, an important demand exists for open time extenders. It has been pointed out that the addition of surface modified colloidal silica into some water based white deco paints induced an extension of their open time. To evaluate the role of colloidal silica in the coalescence process, the surface tension of these paints during their drying has been measured. Dynamic surface tension evolution have shown that their surface tensions are not affected by the use of colloidal silica on the contrary of other open time extenders. Another mechanism takes probably place during the film formation to slow down the process and to prevent the closing of the paint surface. This is the aim of this study.