Effect of surface modification on physicochemical properties of precipitated sodium¯aluminium silicate, used as a pigment in acrylic dispersion paints

Sodium¯aluminium silicates of high dispersion were obtained and studies of the surface modification of the silicates using silane coupling agents are described. The best modifiers were selected, which induced a change of the silicate surface from a hydrophilic to a hydrophobic one. Physicochemical analyses of the modified silicates were performed and methods of evaluating the degree of surface modification of the silicate were presented. Near infrared spectroscopy (NIR) was used to determine the degree of condensation of the silicate surface silanol groups. The degree of hydrophobization of silicate surface was determined using a calorimetric method. Studies of morphology and microstructure were performed using transmission electron microscopy (TEM). Particle size and the tendency to form primary and secondary agglomerate structures were determined using dynamic light scattering technique (DLS). Attempts were made to apply the unmodified and modified sodium¯aluminium silicates as fillers and pigments in acrylic dispersion paints. The modified sodium¯aluminium silicates exerted a most pronounced advantageous effect on resistance to wet scrubbing.