Process for the preparation of a dicalcium phosphate dihydrate suitable for use in toothpastes

摘要

In the process for the preparation of dicalcium phosphate dihydrate, which has a good compatibility with fluorine and stability to hydrolysis and causes the minimum possible after-thickening when used in toothpastes, by reaction of calcium carbonate suspended in water with an aqueous solution of orthophosphoric acid, precipitation of dimagnesium phosphate trihydrate, as a stabilizer, by reaction of aqueous solutions of a magnesium salt and of orthophosphoric acid in the presence of a basic compound and subsequent addition of tetrasodium pyrophosphate to the reaction mixture as a further stabilizer and final filtration, drying and grinding of the precipitate, 0.2 to 0.6% by weight of tetrasodium pyrophosphate, calculated with respect to the dicalcium phosphate dihydrate precipitated in the reaction mixture, is added to the aqueous reaction mixture.