| 摘要 |
The synthetic layered silicates (sheet-silicates, phyllosilicates) modified by quaternary ammonium compounds (QAC) have the general formula: n Na2O x 1 MgO x x SiO2 x y Al2O3 x z H2O; n = 0.05-0.15; x = 0.8-1.3; y = 0.03-0.1; z = 1-3. The quaternary ammonium compound to be used preferably has two short-chain (C1-2) and two long-chain (C>12) hydrocarbon radicals. Preference is given to layered silicates of the formula: 0.1-0.15 Na2O x 1 MgO x 0.85-0.95 SiO2 x 0.03-0.06 Al2O3 and a water content dependent on the degree of drying, which are modified by dimethyldistearylammonium chloride. To prepare the QAC-modified layered silicates, oxides of Na, Mg, Si and Al are mixed in aqueous solution in a molar ratio of 0.05-0.2 Na2O:1 MgO:1-2.5 SiO2:0.05-0.1 Al2O3, subjected to shearing and crystallised in an alkaline medium by stirring at elevated temperature for several hours, the reaction mixture is diluted and brought to a pH of 7-9 with acid, the QAC is added, the mixture is stirred at elevated temperature, and the solid is separated off. The modified layered silicates are used as thickeners for oils and greases.
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