Low molecular weight phosphorus-containing polyacrylic acids and use thereof as scale inhibitors in water-carrying systems

A method, comprising adding an aqueous solution of an acrylic acid polymer to a water carrying system,

• wherein the aqueous solution of the acrylic acid polymer is obtained by polymerization of acrylic acid in feed mode with peroxodisulfate as initiator in the presence of hypophosphite in water as solvent, wherein:
• (i) water and optionally one or more ethylenically unsaturated comonomers are initially charged, and
• (ii) acrylic acid in acidic, unneutralized form, optionally one or more ethylenically unsaturated comonomers, aqueous peroxodisulfate solution and aqueous hypophosphite solution are added continuously, and
• (iii) a base is added on completion of the acrylic acid feed to the aqueous solution,
• and wherein the comonomer content does not exceed 30% by weight, based on total monomer content.

A method, comprising adding an acrylic acid polymer to a water carrying system, wherein the acrylic acid polymer is obtained by polymerization of acrylic acid in feed mode with peroxodisulfate as initiator in the presence of hypophosphite in water as solvent, wherein:

• (i) water and optionally one or more ethylenically unsaturated comonomers are initially charged, and
• (ii) acrylic acid in acidic, unneutralized form, optionally one or more ethylenically unsaturated comonomers, aqueous peroxodisulfate solution and aqueous hypophosphite solution are added continuously, and
• (iii) a base is added on completion of the acrylic acid feed to the aqueous solution,
• and wherein the comonomer content does not exceed 30% by weight, based on total monomer content.