Tetracalcium phosphate-based materials and process for their preparation

Claim 1

A tetracalcium phosphate-based setting composition comprising 100 parts by weight of tetracalcium phosphate particles and about 5 to about 80 parts by weight of an aqueous solution of an acid calculated as an acid, the aqueous solution of acid containing about 30 to about 70% of at least one acid selected from the group consisting of: (a) at least one carboxylic acid selected from the group consisting of lactic acid, malic acid, citric acid, fumaric acid, maleic acid, malonic acid, pyruvic acid, succinic acid, ascorbic acid, gluconic acid and glutaric acid; (b) phosphoric acid; (c) homopolymers of acrylic acid represented by the formula ##STR5## wherein n is 50 to 50,000; (d) copolymers of acrylic acid and itaconic acid represented by the formula ##STR6## wherein l is 5 to 10, m is 1 to 5 and n is 50 to 50,000; and (e) copolymers of acrylic acid and fumaric acid represented by the formula ##STR7## wherein l is 5 to 10, m is 1 to 5, and n is 50 to 50,000, the tetracalcium phosphate particles being produced by a process comprising the steps of (1) sintering or fusing a powder mixture at a temperature of not lower than 1,400° C., the mixture comprising a powder of calcium source and a powder of phosphorous source in a Ca/P molar ratio of 2:1, and about 0.005 to about 5 parts of an aluminum compound, calculated as Al 2 O 3 , per 100 parts of tetracalcium phosphate to be produced in terms of the theoretical amount, and (2) finely dividing the obtained product.