Hoechst Aktiengesellschaft

Gerhard Kalteyer

Franz-Josef Dany

Hedwig Prell

Gerhard Nolte

Joachim Kandler

Renate Adrian

Werner Gohla

Horst Klassen

Hermann Schrodter

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 tooth-pastes, 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 final filtration, drying and grinding of the precipitate, 0.2 to 0.8% by weight of polyphosphoric acid, calculated with respect to the dicalcium phosphate dihydrate precipitated in the reaction mixture, is added to the reaction mixture as a further stabilizer.

Process for the preparation of a dicalcium phosphate dihydrate suitable

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.

A detergent containing 5 to 50% by weight of at least one surfactant, 0.5 to 60% by weight of a matrix substance and also standard laundry aids, contains as matrix substance an amorphous, low-water sodium disilicate having a water content of 0.3 to 6% by weight which has preferably been produced by partial dehydration of commercially available powdered amorphous sodium disilicate having a water content of 15 to 23% by weight.

Detergent containing sodium disilicate having a water content of 0.3 to

Tooth pastes contain a cleaning agent consisting of dicalcium phosphate-dihydrate. The cleaning agent has an adsorptive power of more than 60 g H.sub.2 /100 g. Disclosed is the cleaning agent and a process for making it.

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Erftstadt, Germany

Gerhard Kalteyer