Study On Preparation Of New-Tape Nano Aluminous Flame Retardant By Carbonation And Thermal Hydrolysis With High Concentration

Aluminum trihydroxide (ATH) is the most widely used flame retardant and smoke suppressant in the world. It is widely used in plastics, rubbers. But the commonly used ATH also has such shortcomings as large particle size, low decomposition temperature, low effectiveness on flame retardancy. The decomposition temperature of nano aluminum trihydroxide (CG-ATH), which produced by Research Center of the Ministry of Education for High Gravity Engineering and Technology, increases to 350℃, and thus this can expand CG-ATH's filed of application on polymers.The viscosity of the suspension increases quickly during carbonation precipitation of the ATH and thermal hydrolysis preparation of modified ATH while the solid content rises and conglomeration forms, and the suspension evolves into a viscous Non-Newtonian fluid. Therefore, the concentration is not very high while preparation of Alumina Trihydroxide and modified Alumina Trihydroxide. The maximum content of ATH reaches 0.14g/mL by carbonation, and the maximum content of MATH thermal hydrolysis reaches 78g/L. However, the high concentration not only realized disperse and adjustable fluidity of the ATH suspension but also reduced the equipment investment and energy cost greatly during production and application process. Therefore, studies about the high concentration is extremely valuable.Surfactants were utilized to stabilize and decrease the viscosity of suspension, and were adopted by some reactions. Combined with the knowing about the surfactants, a way was proposed to intensify the mass transfer with them. A rheology method has been used to select dispersants for the ATH suspension. Surfactants were selected to improve fluidity of nano ATH filter cake, among which polymer dispersers show merits. These surfactants improved fluidity so much that the suspension of 12.9 wt% became a Newtonian fluid. An aqueous suspension of solid content up to 64 wt% was obtained with the surfactant.Those surfactants that decreased the viscosity of the aqueous suspension were inactive more or less under the caustic conditions, in which a disperser plus CTAB kept their properties and led to obtaining a concentrated ATH caustic suspension of 40 wt% content with good fluidity at pH above 12 and [Na⁺]=2.7 mol·L^-1. The maximum content of ATH reaches 0.22g/mL during the surfactants were utilized in the carbonation reaction, The surfactants reduced the suspension's viscosity greatly, and the yield increased.A polyelectrolyte surfactant was found to decreases the viscosity of the ATH suspension apparently. The maximum content of ATH with added polyelectrolyte surfactant reaches 293g/L from 78g/L. Nano modified ATH can thus be prepared from a thermal hydrolysis precipitation. The resulting modified ATH has ultra thin rhombic morphology with the beginning of thermal decomposition higher than 350°C and weight loss of 50%...