Patent ID: 8748000

Claim:
Water-absorbing polymer beads comprising at least partly polymerized ethylenically unsaturated acid-bearing monomers and having a mean sphericity of at least 0.84, a content of hydrophobic solvents of less than 0.005%, by weight, having a centrifuge retention capacity of at least 30 g/g, and a permeability of at least 5×10 −7 to 35×10 −7 cm 3 s/g, and which comprise at least 0.5% to 5%, by weight, based on the ethylenically unsaturated acid-bearing monomers, of calcium sulfate or calcium phosphate, wherein the calcium sulfate or calcium phosphate is added to a solution comprising the ethylenically unsaturated acid monomers used for the polymerization.