Patent ID: 7223420

Claim:
A powder mixture for resorbable calcium phosphate biocements, characterized by a fraction mixture consisting of, relative to the total volume of the powder mixture: 40–99% by volume of powder having a particle size of 0.1–10 μm 1–20% by volume of powder having a particle size of 10–43 μm 0–59% by volume of powder having a particle size of 43–315 μm which powder is obtained by grinding the spontaneously crystallizing melts of a material comprising crystalline and X-ray amorphous phases, which material a) according to 31 P-NMR measurements, contains Q 0 -groups of orthophosphate and Q 1 -groups of diphosphate, the orthophosphates or Q 0 -groups making up 65 to 99.9% by weight relative to the total phosphorus content of the powder mixture and the diphosphates or Q 1 -groups making up 0.1 to 35% by weight relative to the total phosphorus content of the powder mixture, and b) according to X-ray diffractometric measurements and relative to the total weight of the powder mixture, contains 35 to 99.9% by weight of a main crystal phase selected from the group consisting of Ca 2 K 1−x Na 1+x (PO 4 ) 2 , where x=0.1 to 0.9, Ca 10 Na(PO 4 ) 7 , Ca 10 K(PO 4 ) 7 , mixtures thereof and mixed crystals according to the formula Ca 10 K x Na 1−x (PO 4 ) 7 , where x=0 to 1, and 0.1 to 20% by weight of a substance selected from the group consisting of Na 2 CaP 2 O 7 , K 2 CaP 2 O 7 , Ca 2 P 2 O 7 , NaPO 3 , KPO 3 and mixtures thereof as a secondary crystal phase, and c) besides the main crystal phase, contains an X-ray amorphous phase which in total makes up 0.1 to 65% by weight relative to the total weight of the powder mixture and which material is prepared by combining the substances 30–55% by weight CaO, 35–50% by weight P 2 O 5 , 1–20% by weight Na 2 O, 0.5–20% by weight K 2 O and 0.1–5% by weight MgO and optionally up to 5% by weight SiO 2 , homogenizing and drying the mixture and subjecting it to a step-by-step thermal treatment lasting 1–2 h at 350–450° C., 750–850° C. and 950–1,050° C. respectively, melting the mixture at between 1,550 and 1,650° C., holding it at the melting temperature for between 10 and 60 minutes and finally cooling the mixture in a spontaneous or temperature-controlled manner and grinding it.