Synthesis and Properties of Organic Bentonite
An organic bentonite is synthesized by a wet process through ion exchange reaction of a quaternary ammonium salt and sodium-based bentonite. Experiments show that with sulfuric acid as the activator, under the conditions of controlling the reaction temperature to 55 ° C-65 ° C and the reaction time to 90 min, the appropriate amount of quaternary ammonium salt is reacted with the sodiumized bentonite slurry. Then filtering,washing and drying the reaction product, we can obtain organic bentonite with excellent dispersibility and thixotropy in organic solvent. The product can be used as a rheological additive and thickener in the fields of paint, ink, grease, oil drilling and et cetera.
In 1934, Smith conducted the first research on the reaction of sodium bentonite with organic amines (R-N), and synthesized organic bentonite. Because quaternary ammonium salts have stronger exchange capacity than organic amines, the performance of the obtained organic clay is superior, many researchers at home and abroad have published many research results of quaternary ammonium salts in place of organic amines to help us further understand of organic clay synthesis, properties and applications.
With sodium-based bentonite as raw material, high-viscosity, low-cost organic bentonite can be formed by wet process. Commercially available bentonite is purified by water suspension method and modified by NaeSiO3, and can be transformed into particle size of 1 ~ 2p. m, exchange capacity of Na ion is larger than ultra-fine and high-quality sodium bentonite with an exceeding 100mmol. The process parameters to be controlled during synthesis are the ratio of raw materials, reaction temperature, reaction time, type and amount of activator, washing method and drying temperature. Under the conditions of strictly controlled technology, the synthesized organic bentonite has good dispersibility and gelability in organic media, and the formed dilute gel shows excellent thixotropy, which can be widely used as a rheological additive used in coatings, greases, oil drilling and other fields.
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