Hydrothermal synthesis of highly swelling saponite, hectorite etc. - with addn. of sodium hydrogen carbonate, used in cosmetics, paint, drilling mud etc.

摘要

Prodn. of highly swelling (a) saponite, (b) hectorite and (c) saponite-hectorite hybrids involves hydrothermal reaction of cpds. contg. (a) Mg, Si and Al, (b) Mg, Si and Li or (c) Mg, Si, Al and Li under pressure in an autoclave, followed by filtration, washing with water, drying at elevated temp. and pulverisation. The novel features are that NaHCO3 is added in such amts. that the molar ratio of the components in the aq. mixt. is: (a) 1.9-2.8 NaHCO3 : 1.2 SiO2 : 1.0 Mg(OH)2 : 0.1 Al(OH)3 : 80-100 H2O; (b) 1.9-2.8 NaHCO3 : 1.2-1.5 SiO2 : 1.0 Mg(OH)2 : 0.05-0.16 LiOH : 80-100 H2O; and (c) 1.9-2.8 NaHCO3 : 1.2-1.5 SiO2 : 1.0 Mg(OH)2 : 0.05-0.1 Al(OH)3 : 0.05-0.16 LiOH : 80-100 H2O. The starting materials are water glass; Mg(OH)2 or MgO; Al(OH)3, aluminate or moist hydrate for Al; and LiOH. USE/ADVANTAGE - A 5% aq. suspension of the powder has a viscosity of 120-210, pref. 150-190 Pa.s after stirring for 30 s and swelling for 16 h (claimed). The prod. is synthesised from starting materials free from sulphate and has unusually high swelling capacity after conditioning. Smectites of this type are useful in cosmetics, lacquers, paints, sewage treatment and drilling muds.