Low molecular mass, phosphorus-containing polyacrylic acids and use thereof as dispersants

Process for preparing aqueous solutions of acrylic acid polymers by polymerizing acrylic acid in feed mode with a radical initiator in the presence of hypophosphite in water as solvent, by (i) initially introducing water and optionally one or more ethylenically unsaturated comonomers, (ii) continuously adding acrylic acid in acidic, non-neutralized form, optionally one or more ethylenically unsaturated comonomers, aqueous radical initiator solution and aqueous hypophosphite solution, (iii) after the end of the acrylic acid feed, adding a base to the aqueous solution, the comonomer content not exceeding 30% by weight, based on the total monomer content, the aqueous hypophosphite solution being added over a total feed time composed of three successive feed time spans t