Pigments on amorphous silica carriers

Amorphous precipitated silica was applied as a carrier for pigments. The silica surface was modified with silane coupling agents, such as 3-aminopropyltriethoxysilane,N-2-(aminoethyl)-3-aminopropyltrimethoxysilane and 3-ureidopropyltrimethoxysilane. Pigments were obtained by attaching organic dyes, C.I. Acid Red 18 and C.I. Acid Violet 1, to a modified silica surface. The adsorption process was conducted in an aqueous suspension of the modified silica in the presence of the dye. Various amounts of the modifying compounds were used in order to determine their effect on the dye adsorption process. The structural and microscopic properties, zeta potential and agglomerate size distribution were examined for the modified silicas and the obtained pigments. Colours of the obtained pigments were measured.