Synthesis And Characteristics Of Organic Bentonite Gel

The organic bentonite gel is a kind of thixotropic gel. It is mainly used as the thickener, viscosity regulator, thixotrope, agent for suspension, emulsion stabilizer and adsorbent in organic disperse system. It has been used extensively in oil-based drill slurry, paint, print ink, lubricant grease, household chemical industrial products and ointment, etc. In addition, it is a raw material for polymer/ montmorillonite nanometer compound material. In this paper, using Liaoning's Ca-bentonite as matrices, modifying with sodium compound at first, organically modifying with Octadecyl/Hexadecyl ammonium chloride as the cover agent, based on hydrothermal process, and dispersing the modified bentonite into the dimethyl benzene-methyl alcohol system fully, we synthesized the high-grade organic bentonite gel with stable quality and excellent characteristics. By some test and analyze methods as XRD, TEM etc., and by modern colloid chemistry theories, we investigated the structure and properties of the gel, the synthesized mechanism of the material, the gel characteristics, the nanometer characteristics, the thixotropy of the organic gel and its application in the epoxy-resin anti-rusting paint etc. The main contents and results of the paper are included as following:1. The suitable modification and purification process and process parameters are selected by sodium modification and purification experiment based on studying systematically the physical properties, mineral and chemical compositions of the bentonite run-of mine. The results show that after the sodium purification, the physical and chemical properties are improved significantly; the impurity in the bentonite sample has obviously decreased; the montmorillonite content are raised to 90%; the sodium purification has a remarkable effect. The purification process uses the continuous dynamic centrifugal separation technique to guarantee the quality stability of sodium purified product, so it can provide the matrix with excellent properties and stable quality to the next organic modification and gel synthesis.2. The organic bentonite gel with 5.0Pa·s and stable quality is synthesized using sodium purified bentonite as matrix, octadecyl/Hexadecyl ammonium chloride as the cover agent, dimethyl benzene-methyl alcohol as the organic dispersant, based on hydrothermal process, filtering, grinding and drying, gel synthesis process etc. The main influence elements on the gel properties are studied. The hydrothermal process uses the auto control system of the temperature in the reaction kettle. The grinding and drying process uses strong-power grinding and drying process. It makes grinding and drying carry out at the same time to promote the drying efficiency and avoid the excessive dry and reduce the product quality. The bentonite matrix selects the low layer charge bentonite. The optimum process conditions of organic modification are determined by the orthogonal tests with different cover agent dosages and pulp pH values and different reaction time and the single element optimization test. The influence of the moisture content of the organic bentonite product on the gel characteristics is studied, so the suitable range of the moisture content is determined. The quality stability and excellent properties of the organic bentonite gel can be guaranteed by the above-mentioned process optimization and process conditions experiment. The economic benefit is good if the organic bentonite product is industrial.3. By some test and analyze methods as XRD, TEM etc., and by modern colloid chemistry theories, we investigated the structure and properties of the gel. The results show that the organic bentonite gel is an artificial space-truss-structure plastomer with large quantity of solution, which is formed by dispersed organic montmorillonite with end-to-end and end-to-face combination and it is a kind of elastic and jelly gel. The organic cover agent Octadecyl/Hexadecyl ammonium chloride configurated in montmorillonite interlayer with paraffin-type monolayer. The angle between the straight chain and the Si-0 layer is 25.9°. The influence of gel temperature on the gel properties is remarkable. By analyzing the TEM photos and observing the dispersed gel, the organic bentonite gel has favorable transparence and nanometer effect. It can be used in such high-new technical fields as high-grade paint, cosmetic and polymer/ montmorillonite nanometer compound material etc. The thixotropy of the organic bentonite gel is good and the thixotropy value is about 1.6.The dynamic theory models of the organic bentonite gel swelling can be described:(1) the linear diffusion of the surface region swelling, the dynamic equation(2) the swelling in the gel internal space-truss-structure is described withLi-Tanaka equation, the dynamic equation is4. The application experiment in the epoxy-resin anti-rusting paint of the organic bentonite gel indicates: After the organic bentonite gel is used in the paint, it can make the dispersive and grinding effect of the paint better, make the paint not easy to sink to the bottom, make the main mechanical physical properties excellent, and it can improve the storage stability of the paint more effectively, so it would have a properties advantage if it would be used in the paint extensively.