| 摘要 |
PROBLEM TO BE SOLVED: To provide a color developing concentrate which is stable to calcium in service water. SOLUTION: The homogeneous single-part color developing concentrate ready to use has pH 7-13 and contains a) at least 0.01 mol/l color developing agent in the form of a free base, b) at least 0.005 mol/l antioxidant for the color developing agent, c) water, d) a photographically inert water-miscible or water-soluble hydroxy-containing straight chain organic solvent for the color developing agent having a molecular weight of 50-200 and present in the concentrate in such a concentration that the mass ratio of the water to the solvent ranges from 15:85 to 50:50, e) at least 0.005 mol/l polyaminopolyphosphonic acid having at least 5 phosphonic acid groups or its salt, f) at least 0,0001 mol/l hydroxyalkylidenediphosphonic acid, its salt, morpholinomethanediphosphonic acid or its salt and g) a buffer soluble in the organic solvent.
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