A method for the preparation of alkali - staerkephosphaten

摘要

The invention comprises alkali-metal starch phosphates containing 6-12% by weight of molecularly bound phosphorus in the form of phosphate. The phosphates are made by mixing at 40-70 DEG C. an aqueous alkali-metal phosphate solution, pH 4-6.5, saturated or almost saturated at 40-70 DEG C., with an amount of starch not exceeding half the weight of phosphate solution, separating and drying the phosphate-soaked starch, and heating it, optionally in vacuo to 120-170 DEG C. for at least 2 hours. A preferred phosphate solution contains 55-65% of sodium orthophosphate (calculated as anhydrous salt). In an example, an aqueous solution of NaH2PO4.2H2O and Na2HPO4.7H2O at 80-100 DEG C. is cooled to 55 DEG C., corn starch is added, and the resulting slurry stirred at 40-50 DEG C. The filtered residue is heated in vacuo at 150-155 DEG C. for 10 hours, yielding a sodium starch phosphate containing 9.6% of phosphorus.