SYNTHETISCHE, QUELLFÄHIGE TONMINERALE

摘要

Synthetic clay minerals are made up of elementary three-layer platelets consisting of a central layer of octahedrally oxygen-surrounded metal ions (octahedron layer), which layer is surrounded by two tetrahedrally surrounded, silicon atom-containing layers (tetrahedron layers), a number of such elementary platelets being optionally stacked. The dimensions of the clay platelets vary from 0.01 mum to 1 mum, the number of the stacked elementary three-layer platelets varies from on average one platelet to twenty platelets, while in the octahedron layer at most 30 at. % of the metal ions has been replaced by ions of a lower valency and in the tetrahedron layers at most 15 at. % of the silicon ions has been replaced by ions of a lower valency, such a replacement having taken place in at least one of these layers and these layers having a deficiency of positive charge because of the replacement. They are prepared by bringing the pH of an aqueous liquid containing the components of the clay to a value of 3-9 and the temperature of the liquid to a value of from 60 to 350° C. and maintaining it at said value for the time required for the reaction, the pH being maintained at a value within said range.