| 摘要 |
Novel alkali metal alumosilicates are prepared, which exchange cations, are insoluble in water, contain bound water and are amorphous in terms of X-ray diffraction, by reacting aqueous solutions of alkali metal silicate and alkali metal aluminate. The procedure comprises the following steps: a) mixing together the alkali metal silicate solution and the alkali metal aluminate solution in the presence of 0.005-10% by weight (based on the entire reaction batch) of ionic surfactants which are stable with respect to hard water and are selected from the group of the anionic, zwitterionic and cationic surfactants under atmospheric pressure and at room temperature of the solutions, b) stirring this mixture continuously for approximately 30 minutes, the alumosilicate being precipitated, c) separating the precipitation product present as a suspension in the aqueous phase from the aqueous phase, d) freeing the precipitation product of mother liquor clinging thereto by washing with water which may, if appropriate, contain the same ionic surfactants, and e) subsequent drying at temperatures of 20-150 DEG C. In doing so, the process steps are tailored to one another in such a way, that the process product obtained is the novel alkali metal alumosilicate, which contains ionic surfactants in amounts of 0.01-50% by weight, based on the mixture of anhydrous alkali metal alumosilicate and surfactant, and bound water and which, per mole of Al2O3, has 0.7-1.5 mol of Cat2/nO (Cat = a cation of valency n) and 0.8-6 mol of SiO2 and a calcium-binding capacity of 50-200, especially of 80-160 mg CaO/g of anhydrous alkali metal alumosilicate and a particle size below 30 mu , preferably at most 8 mu . |
