Calcium phosphates
AssigneeMonsanto Company
InventorsEdward J. Griffith, William C. McDaniel
Life of this patent
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Abstract
Novel processes are provided for producing anhydrous dicalcium phosphate (DCPA) and the gamma and beta forms of calcium pyrophosphate (CPP) from the reaction of phosphoric acid and lime. Dentifrice compositions containing the resultant phosphates are also disclosed.
Claims37
A process for producing crystalline platelets of anhydrous dicalcium phosphate which comprises adding an aqueous solution of phosphoric acid to an aqueous slurry of lime particles in proportions to provide a final pH below 5 and a calcium to PO.sub.4 ratio of about 1:1 and at a rate sufficient to enable a substantially complete reaction of said acid and lime particles while maintaining the temperature sufficiently low to form a slurry of dicalcium phosphate dihydrate particles and then heating said latter slurry at a temperature and for a period of time sufficient to convert said dihydrate particles to crystalline platelets of anhydrous dicalcium phosphate having a mass medium diameter of about 12 to 18 microns.
A process for producing platelike crystalline dicalcium phosphate dihydrate comprising adding phosphoric acid to an aqueous slurry of lime.
Plate-like crystalline dicalcium phosphate dihydrate produced by the addition of an aqueous phosphoric acid solution to an aqueous slurry of lime wherein sufficient acid is employed to provide an acidic reaction medium.
Dicalcium phosphate dihydrate comprising substantially uniform platelike crystals, said crystals having a ratio of surface area to thickness of at least about 200.
A dentifrice composition comprising a fluorine source and a polishing agent comprising substantially uniform crystalline platelets of anhydrous dicalcium phosphate derived from a dihydrate produced by the addition of an aqueous phosphoric acid solution to an aqueous slurry of lime.
A dentifrice composition comprising a fluorine source and a polishing agent comprising substantially uniform crystalline platelets of .beta. phase calcium pyrophosphate derived by calcining dehydrated crystals of dicalcium phosphate dihydrate produced by the addition of an aqueous phosphoric acid solution to an aqueous slurry of lime.
Dependencies are inferred from the claim text.