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

摘要

The invention relates to an aqueous solution of acrylic acid polymers, obtainable 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, wherein the comonomer content does not exceed 30% by weight, based on total monomer content.

主权项

1. An aqueous solution of an acrylic acid polymer, 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; said acrylic acid polymer has a weight average molecular weight ranging from 1000 to 2500 g/mol; and at most 8% of phosphorous contained in said acrylic acid polymer is present in the form of phosphinate and/or phosphonate groups bound at a polymer chain end.